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Cadmium Telluride

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CdTe thin-film technology is being actively commercialized. CdTe cell efficiencies are over 16% in the laboratory; commercial module efficiencies are likely to be in the 9% range in the first manufacturing plants. Companies have an array of inexpensive options to choose from in CdTe fabrication-there are more than a dozen ways to make 10%—efficient cells.

Press Releases, Articles, Pictures/Tables/Figures, Other Items

Journal Articles

Conference Papers

Post Date	10/29/2008
Title	MEASURING CDS/CDTE BACK CONTACT BARRIER HEIGHTS BY INTERNAL PHOTOEMISSION
Link	(PDF 959 KB) Download Acrobat Reader.
Author	A. Fahrenbruch
Description	The back contact of the CdS/CdTe solar cell is one of the most critical aspects in optimizing efficiency and stability. A fundamental parameter is the barrier height ?bc and its measurement is important to fully understanding the device. Plotting the Internal photoemission (IPE) current response to sub-band-gap light according to the Fowler theory gives an intercept equal to the barrier height. IPE can be applied to completed cells, and to thick, thin, and n/i/p cells. Results are compared for a number of cells from various fabricators, including those with good and bad contacts and electronically thick and thin cells. Results suggest two barriers in parallel: a high one, (~ 0.9 eV) which agrees well with the observed UPS values and a low one (~ 0.3 eV) with a much smaller area fraction (1 - 4%) which dominates the contact transport and corresponds more closely to the values observed for efficient cells. For thick cells, IPE results agree well with thermal measurements.
Venue	33rd IEEE PV Specialists Conference, San Diego, CA, May 12-16, 2008
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	07/2008

Post Date	10/29/2008
Title	EXPLORING BACK CONTACT TECHNOLOGY TO INCREASE CDS/CDTE SOLAR CELL EFFICIENCY
Link	(PDF 237 KB) Download Acrobat Reader.
Author	A. Fahrenbruch
Description	The primary routes for increasing CdS/CdTe solar cell efficiency involve increasing free carrier density, reducing bulk and interface recombination, and/or reducing back contact barrier height ?bc. This paper focuses on the role of the back contact barrier in increasing cell efficiency. Measurement of ?bc and back surface recombination are outlined and three CdTe/MX/M back contact prototypes, each with particular strengths, are discussed.
Venue	Materials Research Society Spring Meeting, San Francisco, CA, 4/9-13, 2007, (MRS Smposia Proc vol 1012, p 283)
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	07/2008

Post Date	05/30/2008
Title	THE ROLE OF POLYCRYSTALLINE THIN-FILM PV TECHNOLOGIES IN COMPETITIVE PV MODULE MARKETS
Link	(PDF 351 KB) Download Acrobat Reader.
Authors	B. Von Roedern, H. S. Ullal
Description	This paper discusses the developments in thin-film PV technologies. It provides an outlook on future commercial module efficiencies achievable based on today?s knowledge about champion cell performance. It also provides a relative cost comparison of thin-film and wafer/ribbon based Si PV modules. In 2007, about 65% of the modules produced in the US were thin-film modules when amorphous silicon modules are also considered.
Venue	Presented at the 33rd IEEE PVSC Conference, San Diego, CA 05/12-16/2008
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2008

Post Date	09/28/2007
Title	THIN FILM CIGS AND CDTE PHOTOVOLTAIC TECHNOLOGIES: COMMERCIALIZATION, CRITICAL ISSUES, AND APPLICATIONS
Link	(PDF 725 KB) Download Acrobat Reader.
Authors	H. S. Ullal, B. Von Roedern
Description	We report here on the major commercialization aspects of thin-film photovoltaic (PV) technologies based on CIGS and CdTe (a-Si and thin-Si are also reported for completeness on the status of thin-film PV). Worldwide silicon (Si) based PV technologies continues to dominate at more than 94% of the market share, with the share of thin-film PV at less than 6%. However, the market share for thin-film PV in the United States continues to grow rapidly over the past several years and in CY 2006, they had a substantial contribution of about 44%, compared to less than 10% in CY 2003. In CY 2007, thin-film PV market share is expected to surpass that of Si technology in the United States. Worldwide estimated projections for CY 2010 are that thin-film PV production capacity will be more than 3700 MW. A 40-MW thin-film CdTe solar field is currently being installed in Saxony, Germany, and will be completed in early CY 2009. The total project cost is Euro 130 million, which equates to an installed PV system price of Euro 3.25/-watt averaged over the entire solar project. This is the lowest price for any installed PV system in the world today. Critical research, development, and technology issues for thin-film CIGS and CdTe are also elucidated in this paper.
Venue	22nd EC PVSEC, Milano, Italy Sep 3-7, 2007, paper presented
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	09/2007

Post Date	04/30/2007
Title	OUTDOOR MONITORING AND HIGH VOLTAGE BIAS TESTING OF THIN FILM PV MODULES
Link	(MS Word 64 KB)
Author	N. G. Dhere
Description	Limitations of accelerated testing to predict all possible degradation modes and mechanisms in the photovoltaic PV modules necessitate that actual outdoor monitoring and testing of PV modules be performed out-doors. For this reason, thin film PV modules from leading US thin film PV manufacturers namely, First Solar (Glass/CdTe/Glass), Shell Solar Glass/CIS/Glass), Shell Solar New (Glass/CIGS/Glass), United Solar (a-Si:H on flexible substrate), Energy Photovoltaics (Glass/a-Si:H/Glass) and Global Solar (CIS on flexible substrate) with additional one crystalline silicon module are being tested. The goal is to assess their performance in the hot and humid climate of Florida and to correlate the PV performance with the meteorological parameters namely, solar irradiance, temperature, relative humidity, wind speed, etc. Statistical data analysis of the recorded data is carried out on a daily basis and on a monthly basis with PVUSA type regression analysis. Current-voltage characteristics (I-V) of module arrays taken on a regular basis complement the results obtained with continuous data monitoring. Moreover, high voltage bias testing of the modules is carried out to study behavior of leakage currents and detect any packaging material and processing flaws and consequently the module reliability.
Venue	DOE Solar Technology Review Meeting, Denver, CO, 4/17-19/2007
Source	FLorida Solar Energy Center
Document Type	Conference Papers (Word document)
Resource Date	03/2007

Post Date	04/30/2007
Title	&NBSP; VOLTAGE DEFICIT IN THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 46 KB)
Author	J. R. Sites
Description	The highest reported efficiency for thin-film CIGS solar cells is 3% larger than the highest seen with CdTe cells. The lower CdTe efficiency is the result of a much larger voltage deficit between CdTe cells and crystalline cells of similar band gap. The explanation for the difference is that CIGS has a natural energy barrier, which repels holes from grain boundaries, but CdTe does not. Significant efficiency increases in CdTe cells will therefore likely require new structures with full absorber depletion and electron reflection at the back contact.
Venue	DOE Solar Technology Review Meeting, Denver, CO 4/17-17/2007
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	03/2007

Post Date	10/26/2006
Title	BOS COST SAVINGS NEEDS AND POTENTIAL FOR LARGE SCALE GROUND BASED PV SYSTEMS UNTIL 2010
Link	(PDF 495 KB) Download Acrobat Reader.
Author	M. Bachler
Description	More and more large scale ground based systems were implemented with thin-film modules in the past years in Germany. Based on module pricing thin film modules appear to be very attractive for this type of application. However there are quite significant differences in balance-of-system (BOS) costs within different c-Si and thin film (TF) module types, which have a high impact on total system costs. The BOS cost portion is significantly higher for systems with TF modules compared to c-Si modules. Existing c-Si modules and BOS components were developed and optimized to achieve cost savings in the past decades already a lot. TF modules as well as the related BOS components are at the very beginning of this development so the cost saving potential ? especially for BOS costs is considered to be significantly higher for TF module based systems. Since a 6.5% degression in the feed-in tariff is required in the German EEG for ground based systems a high cost reduction pressure is imposed on total system costs. The results of BOS cost savings achieved already will be demonstrated for a sample thin-film module.
Venue	Dresden World Conference
Source	Phonix SonnenStrom AG
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	09/2006

Post Date	06/14/2006
Title	CDTE PHOTOVOLTAICS: LIFE CYCLE ENVIRONMENTAL PROFILE AND COMPARISONS
Link	(PDF 210 KB) Download Acrobat Reader.
Author	V. Fthenakis
Description	We discuss the emissions of cadmium throughout all the life stages of CdTe PV modules, from extracting, refining, and purifying the raw materials to producing, using, and disposing or recycling of the modules. Then, we compare these emissions with those in the life cycle of three different types of crystalline Si PV modules. The energy requirement and energy pay back times (EPBT) of CdTe PV modules is considerably shorter than that of crystalline Si modules, although the latter exhibit higher efficiencies. This difference is primarily due to the energy used to process silicon, a fraction of which is derived from fossil fuels, inevitably producing Cd and many other heavy-metal emissions.
Venue	Presented at the European Material Research Society Meeting
Source	N/A
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2006

Post Date	08/25/2006
Title	POLYCRYSTALLINE THIN-FILM PHOTOVOLTAICS: FROM THE LABORATORY TO SOLAR FIELDS
Link	(PDF 682 KB) Download Acrobat Reader.
Authors	B. Von Roedern, H. S. Ullal, K. Zweibel
Description	We review the status of commercial polycrystalline thin-film solar cells and photovoltaic (PV) modules, including current and projected commercialization activities. Major technical progress has occurred in the area of thin-film PV technologies, particularly those based on cadmium telluride (CdTe) and copper indium diselenide (CuInGaSe2)
Venue	Presented at the 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion (WCPEC-4) Waikoloa, Hawaii May 7?12, 2006 Conference Paper NREL/CP-520-39838 May 2006
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2006

Post Date	05/22/2006
Title	TECHNOLOGY CHOICE AND THE COST REDUCTION POTENTIAL OF PHOTOVOLTAICS
Link	(PDF 116 KB) Download Acrobat Reader.
Authors	J. E. Trancik, K. Zweibel
Description	We use a combination of system component analyses and individual experience curves for crystalline silicon (x-Si) modules, thin-film (TF) modules, and the balance of system (BOS) components, to compare future growth scenarios for photovoltaics (PV). The growth rates of TF and x-Si technologies are varied, while overall PV growth is held constant at 30%. For each of these scenarios, we estimate the total investment required for PV to reach a break-even point with fossil fuel based generation; and we investigate the intrinsic/lowest achievable costs from an analysis of potential materials, processing, and efficiency improvements. Our results show that a high growth rate (50 to 70% per year) of new technologies with low intrinsic costs could decrease the total investment required to reach break-even by up to 70 billion USD, as compared to a scenario where x-Si continues to dominate the market. Furthermore, the system component analysis indicates that existing TF modules can reach the low cost levels assumed in the experience curve model. These results suggest that the future growth of photovoltaics (PV) is dependent on which PV technologies grow most rapidly. New, low intrinsic cost technologies that are successfully able to enter the market could dramatically increase the potential for PV to become a globally significant energy conversion technology within the next two decades.
Venue	Trancik and Zweibel, WCPEC-4 2006
Sources	National Renewable Energy Laboratory; Santa Fe Institute
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2006

Post Date	11/07/2006
Title	THE RELATIONSHIP OF CDS/CDTE CELL BAND PROFILES TO J-V CHARACTERISTICS AND BIAS-DEPENDENT QUANTUM EFFICIENCY
Link	(PDF 1.6 MB) Download Acrobat Reader.
Author	A. Fahrenbruch
Description	AMPS models of two extreme profiles are discussed here as illustrations: an n/i/p junction, where Vbi is mainly supported by charge at the contacts, and an n/p junction, where Vbi is supported by charge in the bulk CdTe within the absorber There are several general pathways to increasing the efficiency of CdS/CdTe cells. Since Jsc is close to its limit, those with the most potential yield involve increasing the cell voltage at the maximum power point (Vmax). These are discussed here in a theoretical way to view trends, allowing that they may be very difficult or impossible to realize in practice. One pathway is by increasing the net negative charge in the CdTe by ?p-type doping.? Another is by increasing the minority carrier lifetime (tn) by, for example, control of impurities, reducing growth rate, and/or changing the micro-stoichiometry. These two pathways deal with bulk materials properties. A third pathway is by decreasing the back-contact barrier height Fbc and the recombination there, both interface properties. Many other pathways are less risky and more practical including: thinner windows and/or absorber layers, increasing the window band gap, and optical optimization.
Venue	4th WCPEC ((IEEE PVSC), Hawaii 05/2006 paper
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2006

Post Date	09/19/2006
Title	HOW CDTE SOLAR CELLS OPERATE: DETERMINING COLLECTION USING BIFACIAL DEVICE CHARACTERIZATION
Link	(PDF 113 KB) Download Acrobat Reader.
Authors	D. Desai, S. S. Hegedus, B. E. McCandless, R. W. Birkmire, K. D. Dobson, D. Ryan
Description	The results presented in this paper provide a quantitative understanding of minority carrier transport parameters in CdTe based photovoltaic devices. We have demonstrated that bifacial device characterization is a valuable and efficient tool for analysis of the primary transport parameters and allows separation of the primary CdS/CdTe junction from the back contact. We conclude that for standard front illumination, the fill factor (FF) and spectral response from front (SRF) are limited by voltage dependent collection and L is nearly irrelevant. However, spectral response from back illumination (SRB) is limited by diffusion through the bulk to the depletion edge. W and L were derived by extensive numerical analysis of SRB data. The values of W obtained were independently confirmed by CV measurements, thus validating the numerical model and the analysis procedure. The blocking contact usually observed in CdTe devices is photoconductive and can be effectively eliminated by illumination. This blocking contact barrier has no effect on Voc.
Venue	IEC, U. Delaware, paper given at 4th WCPEC (Hawaii, 2006)
Source	University of Delaware
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2006

Post Date	05/18/2006
Title	HIGH-EFFICIENCY CDTE AND CIGS THIN-FILM SOLAR CELLS: HIGHLIGHTS AND CHALLENGES
Link	(MS Word 602 KB)
Authors	R. Noufi, K. Zweibel
Description	Thin-film photovoltaic (PV) modules of CdTe and Cu(In,Ga)Se2 (CIGS) have the potential to reach cost-effective PV-generated electricity. These technologies have transitioned from the laboratory to the market place. Pilot production and first-time manufacturing are ramping up to higher capacity and enjoying a flood of venture-capital funding. CIGS solar cells and modules have achieved 19.5% and 13% efficiencies, respectively. Likewise, CdTe cells and modules have reached 16.5% and 10.2% efficiencies, respectively. Even higher efficiencies from the laboratory and from the manufacturing line are only a matter of time. Manufacturing-line yield continues to improve and is surpassing 85%. Long-term stability has been demonstrated for both technologies; however, some failures in the field have also been observed, emphasizing the critical need for understanding degradation mechanisms and packaging options. These two thin-film technologies have a common device/module structure: substrate, base electrode, absorber, junction layer, top electrode, patterning steps for monolithic integration, and encapsulation. The monolithic integration of thin-film solar cells can lead to significant manufacturing cost reduction compared to crystalline Si technology. The CdTe and CIGS modules share common structural elements. In principle, this commonality should lead to similar manufacturing cost per unit area, and thus, the module efficiency becomes the discriminating factor that determines the cost per watt. The long-term potential of the two technologies require R&D emphasis on science and engineering-based challenges to find solutions to achieve targeted cost-effective module performance, and in-field durability. Some of the challenges are common to both, e.g., in-situ process control and diagnostics, thinner absorber, understanding degradation mechanisms, protection from water vapor, and innovation in high-speed processing and module design. Other topics are specific to the technology, such as lower-cost and fast-deposition processes for CIGS, and improved back contact and voltage for CdTe devices.
Venue	WPEC4, Hawaii
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	05/2006

Post Date	10/20/2005
Title	A REVIEW OF RISKS IN THE SOLAR ELECTRIC LIFE-CYCLE
Link	(PDF 642 KB) Download Acrobat Reader.
Authors	V. Fthenakis, H. C. Kim
Description	Early studies of risks in the life cycle of solar electric technologies do not represent their current stage of development. Our study updates the data used in previous studies and also accounts for the full life-cycle of photovoltaics. We show that the non-radiological risks of the solar electric- and nuclear-life cycles are approximately equal. This contradicts the conclusions of some earlier studies according to which the former presented much greater occupational and public non-radiological risks than the latter.
Venue	Brussels 2005
Source	Brookhaven National Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2005

Post Date	10/20/2005
Title	LIFE CYCLE ANALYSIS OF PHOTOVOLTAIC SYSTEMS
Link	(PDF 144 KB) Download Acrobat Reader.
Author	V. Fthenakis
Description	Life Cycle Analyses (LCA) at BNL show that: i) The BOS of an optimized installation has an energy payback time (EPBT) of only 0.4 years for average US insolation, which is 70% lower than previously reported estimates. ii) The EPBT of CdTe modules produced and used in the U.S. is 0.85 years. iii) The life-cycle CO2 emissions of the nuclear fuel cycle in the U.S. are about the same as those in the PV cycle; this contrasts European studies showing CO2 emissions from nuclear to be 10 lower than those from PV.
Venue	Solar Program Review Meeting 2005
Source	Brookhaven National Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2005

Post Date	06/13/2005
Title	IMPLICATIONS OF EUROPEAN ENVIRONMENTAL LEGISLATION FOR PHOTOVOLTAIC SYSTEMS
Link	(PDF 434 KB) Download Acrobat Reader.
Authors	M. J. De Wild-Scholten, K. Wambach, E. A. Alsema, A. Jager-Waldau
Description	An overview is given of European environmental legislation which is effective now or proposed and which may have implications for the photovoltaic industry. The focus will be on legislation, which has been implemented already in national law, like the WEEE (waste electrical and electronic equipment)- and ROHS Reach (Registration, Evaluation, Authorisation and Restriction of Chemicals), F-gases (regulation on certain fluorinated greenhouse gases) and EuP (eco-design requirements for energy-using products). A change of the module design, with the research, development, implementation and certification necessary to be able to produce photovoltaic systems that comply with such legislation, may be very time-consuming and expensive. Therefore a pro-active approach by the PV community is desirable. Environmental life cycle thinking and eco-design is becoming increasingly important as part of the European product and waste policy and will have its impact on the PV industry as well. Design-for-recycling must be encouraged to allow for an easy, cost-effective disassembly, with a high retrieval of for instance the precious crystalline silicon solar cells. A closed production cycle, i.e. guaranteed take back system, would probably prevent the commission as well as member states to impose legislative measures.
Venue	20th European PVSC Barcelona
Sources	Deutsche Solar; Energy Research Centre of the Netherlands
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2005

Post Date	06/14/2005
Title	EMPIRICAL TUNING METHODOLOGY FOR AS AND CL DOPING OF MOCVD GROWN CDTE
Link	(PDF 192 KB) Download Acrobat Reader.
Author	V. Barrioz
Description	Photovoltaic solar cells based on CdTe absorbers are still showing comparitively high efficiencies, currently at 16.5%. However, these cells rely on CdCl2 treatments which are not fully understood and constrainflexibility over cell design. In this work, the effect of controlled arsenic and chlorine doping will be discussed as a potential alternative to CdCl2 treatments. The CdTe/CdS structures were grown by MOCVD onto commercial ITO/glass substrates. Numerous growth and post-growth parameters were varied such as; the II:VI precursor ratios, the substrate temperatures (Tsub) and the in situ post-growth annealing ambient gas (H2 or N2). A strategic statistical design of experiments, the Taguchi matrix method, was used, to establish the best combination of material parametersfor photovoltaic solar cell. High arsenic doping concentrations were needed to achieve a good photo-response in the test cells with a Jsc = 24.3 mA.cm-2, but the cell efficiency was limited by other parameters Voc = 0.55 V; FF = 40.9 %. The other main parameters increasing the cell efficiency were the in situ CdCl2 treatment and substrate temperatures of 315oC and 390oC during the growth of CdS and CdTe respectively. Any post-growth annealing at 500oC damaged considerably the photocurrent response. The method has been successful in showing rapid progress with a new approach, using 16 material and process parameters, in just 36 experiments, for achieving acceptable PV test cells.
Venue	20th EU PVSC Barcelona
Source	University of Wales
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2005

Post Date	06/14/2005
Title	ENERGY AND LIFE CYCLE ASSESSMENT OF THIN FILM CDTE PHOTOVOLTAIC MODULES
Link	(PDF 360 KB) Download Acrobat Reader.
Author	M. Raugei
Description	topic of this paper is the Life Cycle Assessment (LCA) of modern CdTe PV modules. The analysis was performed within the framework of the European research project PVACCEPT, and is based on actual production data provided by the former project partner ANTEC Solar GmbH. This latter point makes the present LCA especially worthy of attention as a preliminary indication of the future environmental impact that the upscaling of CdTe module production may entail. The analysis is performed according to the recommendations of ISO norms 14040 and updates, and makes use of an original multi-criteria approach named SUMMA. The performance of the analysed CdTe system is also compared to other examples of advanced PV systems based on different technologies (CIS and mc-Si), which were also part of the PVACCEPT project. Results clearly show an overall very promising picture for CdTe technology, which is found to be characterised by favourable environmental impact indicators (e.g. 60g(abiotic matter)/kWh, 32 g(CO2-eq)/kWh and energy payback of 0.9 yrs.
Venue	20th EU PVSC Barcelona
Source	University of Siena
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2005

Post Date	06/29/2005
Title	NREL PAPERS FOR THE PVSC IN ORLANDO, 2005
Link	(MS Word 41 KB)
Author	N/A
Description	Links to about 20 papers in CIS, CdTe, a-Si, thin Si and reliability.
Venue
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	06/2005

Post Date	05/09/2005
Title	CURRENT TRANSIENTS IN CDS/CDTE SOLAR CELLS
Link	(PDF 194 KB) Download Acrobat Reader.
Author	A. Fahrenbruch
Description	Current transient responses to voltage and illumination steps are investigated to clarify the mechanisms involved in carrier transport in CdS/CdTe cells. For most cells, the response to a dark, forward-bias step after a long dark soak at zero bias is a current growth curve For one such cell, the magnitude of the transient is �� 22% of the starting value with half of the growth occurring within �� 5 sec, the other half requiring 1000's of seconds. The effect is completely reversible and a mirror-image decay curve at zero bias after dark bias-on equilibration can be measured. Similarly, a complex of growth and decay curves are observed on application of illumination steps with constant bias. Similar transients have been observed by McMahon [1] and del Cueto et al. [2]. This is a survey of these effects in cells from three different fabricators. These transients, with varying magnitudes and directions, were seen in all the cells studied. In general, the better the cell, the smaller the magnitudes of the transients. They range from changes by factors of 10 for pathological cells to subtle transients of 1-2% in excellent cells. Beside the important implications these transients have for accurate measurements of cell efficiency and stability, they provide clues about the carrier transport mechanisms.. One of the mechanisms proposed involves the occupation of deep donor traps with small hole cross sections, changing their recombination kinetics. The second hypothesis involves the modulation of the junction barrier profile by changing the charge on deep acceptors and donors by carrier trapping, leading to a change in the effective junction barrier height. A third involves defect mutation such as that of [Cui] donors into [VCd].
Venue	Presented at the MRS Spring Meeting 3/28-4/1/2005, San Francisco REVISED 4/9/2005
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	04/09/2005

Post Date	04/05/2005
Title	PHYSICS OF CDTE PHOTOVOLTAICS: FROM FRONT TO BACK
Link	(PDF 332 KB) Download Acrobat Reader.
Authors	V. G. Karpov, et al.
Description	We discuss physical mechanisms underlying the performance and stability of CdTe based thin-film PV. The processes in (i) photovoltaic junction, (ii) back contact, (iii) nonuniformities, (iv) grain boundaries, and (v) light-induced degradation are addressed including their interactions. The physics of thin film PV turns out to be quite different from that of crystalline PV. High surface-volume ratio and lack of crystallinity result in strong interfacial effects, lateral nonuniformities, and shunting-like and adhesion instabilities in thin film structures. This paper is aimed at presenting a ?big picture?; also, it suggests practical ways of improving thin-film PV.
Venue	MRS Spring Meeting 2005, March 28 ? April 1, San Francisco,
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	03/28/2005

Post Date	07/15/2005
Title	QUANTIFICATION OF LOSSES IN THIN FILM CDS/CDTE CELLS
Link	(PDF 288 KB) Download Acrobat Reader.
Authors	S. Demetsu, J. R. Sites
Description	Quantification of solar cell losses can identify promising pathways for further cell improvements. This paper expands earlier work and applies it specifically to CdS/CdTe cells. For the analysis we have defined four cells: The Target cell is one that should be possible with current industrial processes. The Production cell is typical of today?s production. The Record cell has the highest efficiency (16.5%) reported to date. The Ideal cell has the highest theoretical performance for CdTe. The systematic technique of separating losses, referred to as third level metrics, breaks current, voltage, and fill-factor losses down into their individual loss mechanisms. The losses are expressed both as the deficiency in the specific parameter and as the impact on cell efficiency. The latter allows clear identification of the most significant losses. R-
Venue	PVSC Orlando, FL 2005
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/11/2005
Title	LIFE CYCLE ASSESSMENT OF PHOTOVOLTAICS: PERCEPTIONS, NEEDS, AND CHALLENGES
Link	(PDF 222 KB) Download Acrobat Reader.
Authors	E. A. Alsema, M. J. De Wild-Scholten, V. Fthenakis
Description	High impact publications recently depicted PV technologies as having higher external environmental costs than those of nuclear energy and natural-gas-fueled power plants. These assessments are based on old data and unbalanced assumptions, and they illustrate the need for LCA data describing the continuously improving photovoltaic systems and the inclusion of social benefits in this comparison.
Venue	IEEE Photovoltaic Specialistis Conference, Jan. 3-7, 2005, Orlando, FL
Sources	Brookhaven National Laboratory; Energy Research Centre of the Netherlands; Utrecht University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/15/2005
Title	EARLY PERFORMANCE FOR THE ROOF-MOUNTED, 20-KW THIN FILM CDTE PV-ARRAY AT JASPER RIDGE
Link	(PDF 364 KB) Download Acrobat Reader.
Authors	J. H. Scofield, et al.
Description	Here we report early performance for the grid-connected, 20-kW CdTe PV array installed on the roof of the Leslie Shao-ming Sun Field Station at the Jasper Ridge Biological Preserve. The array was installed in May 2002. Data are reported for 20-mos beginning April 2003. The array originally consisted of 275, BP Solar 80W thin-film CdTe modules arranged in 11-module strings. The monitoring system logged data from 9 sensors on 1-min intervals. Monitoring showed problems with maximum power tracking associated with module degradation, ele-vated module temperatures, and the finite voltage window of the 208VAC-3p inverter. The problems were addressed in May 2004 by re-wiring the array and reprogramming the inverter, resulting in a 20% increase in energy production.
Venue	IEEE PVSC
Source	Oberlin College
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/14/2005
Title	EARLY PERFORMANCE FOR THE ROOF-MOUNTED, 20-KW THIN FILM CDTE PV-ARRAY AT JASPER
Link	(PDF 354 KB) Download Acrobat Reader.
Author	J. H. Scofield
Description	We report early performance for the grid-connected, 20-kW CdTe PV array installed on the roof of the Leslie Shao-ming Sun Field Station at the Jasper Ridge Biological Preserve. The array was installed in May 2002. Data are reported for 20-mos beginning April 2003. The array originally consisted of 275, BP Solar 80W thin-film CdTe modules arranged in 11-module strings. The monitoring system logged data from 9 sensors on 1-min intervals. Monitoring showed problems with maximum power tracking associated with module degradation, elevated module temperatures, and the finite voltage window of the 208VAC-3p inverter. The problems were addressed in May 2004 by re-wiring the array and reprogramming the inverter, resulting in a 20% increase in energy production.
Venue	IEEE PVSC
Source	Oberlin College
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	03/22/2005
Title	QUANTIFICATION OF LOSSES IN THIN-FILM CDS/CDTE SOLAR CELLS
Link	(MS Word 3.5 MB)
Authors	S. Demetsu, J. R. Sites
Description	Quantification of solar cell losses can identify promising pathways for further cell improvements. This paper expands earlier work and applies it specifically to CdS/CdTe cells. For the analysis we have defined four cells: The Target cell is one that should be possible with current industrial processes. The Production cell is typical of today?s production. The Record cell has the highest efficiency (16.5%) reported to date. The Ideal cell has the highest theoretical performance for CdTe. The systematic technique of separating losses, referred to as third level metrics, breaks current, voltage, and fill-factor losses down into their individual loss mechanisms. The losses are expressed both as the deficiency in the specific parameter and as the impact on cell efficiency. The latter allows clear identification of the most significant losses.
Venue	PVSC-31 IEEE
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	01/2005

Post Date	02/15/2005
Title	ANALYTICAL RESULTS OF OUTPUT RESTRICTION DUE TO THE VOLTAGE INCREASING OF POWER DISTRIBUTION LINE IN GRID-CONNECTED CLUSTERED PV SYSTEMS
Link	(PDF 2.4 MB) Download Acrobat Reader.
Authors	Y. Ueda, et al.
Description	Output restriction to prevent over voltage of power distribution line is one of the concerns for grid-connected clustered PV systems. To investigate the behavior of clustered PV systems, "Demonstrative research on clustered PV systems" has being conducted from December, 2002 in Gunma, Japan. More than 200 residential PV systems are already installed in demonstrative research area. Operation point of array output is estimated using minutely averages of collected data. The method to quantify loss due to output restriction is developed in this study.
Venue	IEEE PVSC
Source	Tokyo University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/07/2005
Title	THE ROLE OF POLYCRYSTALLIN THIN-FILM PV TECHNOLOGIES FOR ACHIEVING MID-TERM MARKET-COMPETITIVE PV MODULES
Link	(MS Word 123 KB)
Authors	B. Von Roedern, K. Zweibel
Description	Using efficiency as the main parameter, projecting the cost competitiveness of thin films and x-Si. Current commercial status of CuInSe₂ alloys (collectively, CIS) and CdTe-based photovoltaic (PV) modules, comparing the performance of commercial products with the results achieved for solar cell and prototype module champions. We provide an update for these PV cell and module technologies, and also compare CIS and CdTe performance levels to the results achieved by the crystalline Si PV industry. This comparison shows that CIS and CdTe module technology presently offers the best (and perhaps only) approach for significantly exceeding the cost/performance levels established by crystalline Si PV technologies. A semi-empirical methodology is used for comparing "champion" solar cell and prototype module data with performance achieved on manufacturing lines. Using a conservative assumption that thin-film technologies will eliminate the 40% of PV module costs arising from the Si wafer or ribbon, we estimate the future performance of all established PV module candidates, and conclude that, based on 2004 knowledge about each PV technology, CIS and CdTe should provide cost-competitive advantages over crystalline Si.
Venue	IEEE PV Specialists Conference, 2004
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	01/2005

Post Date	03/22/2005
Title	LBIC ANALYSIS OF THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 1.1 MB)
Authors	T. J. Nagle, J. R. Sites
Description	Light-beam-induced-current (LBIC) measurements are providing a direct link between the spatial non-uniformities inherent in thin-film polycrystalline solar cells, such as CdTe and CIGS, and the overall performance of these cells. LBIC is uniquely equipped to produce quantitative maps of local quantum efficiency with relative ease. Spatial resolution of 1 ?m at 1-sun intensity, and return to the same area after other measurements, is routinely achieved. A wavelength range of 638 to 857 nm is available with diode lasers. The LBIC measurements demonstrate that several types of effects that alter cell performance can be traced to specific local-area features. Examples of such effects include defects related to edges, grids, or scribes, spatial variations in alloying, and local changes due to high-temperature stress.
Venue	IEEE PVSC-31
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	01/2005

Post Date	02/09/2005
Title	TRANSPARENT CONTACT DEVELOPMENT FOR CDSE TOP CELLS IN HIGH EFFICIENCY TANDEM STRUCTURES
Link	(MS Word 65 KB)
Authors	P. Mahawala, et al.
Description	developing transparent contact/CdSe/transparent contact structures deposited on glass/SnO2:F. With these transparent structures we have demonstrated record Jsc's of 17.4 mA/cm2. SnO2 serves as the n contact, and the p contact is ZnSe:Cu. These structures have also exhibited sub band gap transmission of 80%. We have evaluated ZnO and CdS as alternative n contacts and ZnTe as an alternative p contact. Voc's of only 300 mV are being attained with ZnSe:Cu because its Fermi level seems to be near the middle of the band gap of CdSe in spite of favorable valence band alignment. However, using ZnTe:Cu as the p contact we have achieved Voc's up to 575 mV, a new high.
Venue	IEEE
Source	University of South Florida, Tampa
Document Type	Conference Papers (Word document)
Resource Date	11/2004

Post Date	02/09/2005
Title	HIGH THROUGHPUT PROCESSING OF CDTE/CDS SOLAR CELLS
Link	(MS Word 596 KB)
Authors	B. E. McCandless, et al.
Description	Methods for achieving high throughput and materials yield in processing >13% efficient CdTe thin film solar cells are demonstrated, with emphasis on emiconductor deposition and post-deposition processing. Chemical surface deposition was used to deposit uniform 100 cm2 area CdS films 50 nm thick at 0.2 nm/sec, with >80% tilization of solvated Cd species. Vapor transport at 20 Torr was used to deposit dense CdTe films, 1-7 ?m thick, onto CdS-coated substrates with >50% utilization in an unbaffled system. Uniform films have been deposited with translation at up to 12 cm/min and static equivalent growth rate >80 ?m/min. Vapor CdCl2 post-deposition treatments yielded solar cells with AM1.5 conversion efficiency >13% for 6 mm thick CdTe and >8% for 1 mm thick CdTe.
Venue	IEEE PVSC
Source	University of Toledo
Document Type	Conference Papers (Word document)
Resource Date	10/2004

Post Date	02/04/2005
Title	STUDY OF POTENTIAL COST REDUCTIONS RESULTING FROM SUPER-LARGE-SCALE MANUFACTURING OF PV MODULES
Link	(MS Word 112 KB)
Authors	R. Arya, M. Keshner
Description	Short version of multi-GW production report
Venue	NREL Solar Review
Source	Hewlett Packard
Document Type	Conference Papers (Word document)
Resource Date	10/2004

Post Date	02/08/2005
Title	THE IMPROVED INTRINSIC STABILITY OF CDTE POLYCRYSTALLINE THIN FILM DEVICES
Link	(PDF 137 KB) Download Acrobat Reader.
Authors	D. Albin, et al.
Description	Parametric studies of CdS/CdTe device stability.
Venue	DOE/NREL Solar Review 2004
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2004

Post Date	02/08/2005
Title	THERMAL ADMITTANCE SPECTROSCOPY STUDY: PRELIMINARY OBSERVATIONS OF A MEYER-NELDEL RELATIONSHIP IN CDTE DEVICES
Link	(PDF 689 KB) Download Acrobat Reader.
Authors	K. L. Barth, R. A. Enzenroth, W. S. Sampath
Description	CdTe analysis.
Venue	IEEE
Source	Colorado School of Mines, Golden, CO
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2004

Post Date	02/10/2005
Title	CHARACTERISTICS OF CDTE FILMS OF DIFFERENT COMPOSITIONSFABRICATED BY CMBD
Link	(MS Word 965 KB)
Authors	T. M. Razykov, et al.
Description	CdTe films with near stoichiometric compositions and cadmium-rich compositions were fabricated by a novel low-cost chemical molecular beam deposition (CMBD) technique at atmospheric pressure under hydrogen or nitrogen gas flow. X-ray diffraction analysis and scanning electron microscopy studies show different grain growth by CMBD depending on the composition of samples. Those grown with cadmium rich compositions were of poor quality with large discontinuous island structures. On the other hand, samples grown with near stoichiometric compositions were polycrystalline with large grain size and uniform thickness. Additionally, films grown under nitrogen flow contained a cadmium tellurium oxide phase while those grown under hydrogen did not.
Venue	31st IEEE PVSC
Source	Uzbek Academy of Sciences
Document Type	Conference Papers (Word document)
Resource Date	10/2004

Post Date	02/08/2005
Title	CONSISTENT PROCESSING AND LONG TERM STABILITY OF CDTE DEVICES
Link	(PDF 1.4 MB) Download Acrobat Reader.
Authors	K. L. Barth, R. A. Enzenroth, W. S. Sampath
Description	A technology for processing of thin film CdS/CdTe devices has been developed in our laboratory. This inline, continuous, pilot system enables unique processing steps and conditions not available with batch processing and allows the fabrication of a large number of devices. Results from the pilot scale system are applicable to systems processing larger areas.
Venue	IEEE
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2004

Post Date	02/09/2005
Title	PHYSICAL MODES OF THIN-FILM PV DEGRADATION
Link	(PDF 267 KB) Download Acrobat Reader.
Authors	V. G. Karpov, et al.
Description	We discuss physical modes of degradation related to the small thickness and lack of crystallinity in thin-film PV. We discriminate between 1) uniform material degradation through defect generation, light-induced diffusion, and electro-migration; 2) nonuniform degradation through ohmic or non-ohmic shunts; 3) metal contact deterioration. The first can equally apply to bulk and thin-film PV. Two others are specific to thin-film PV.
Venue	IEEE
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2004

Post Date	02/08/2005
Title	INTRODUCTION OF CU IN CDS AND ITS EFFECT ON CDTE SOLAR CELLS
Link	(MS Word 130 KB)
Authors	K. Barri, et al.
Description	The use of copper during the fabrication of CdTe solar cells is a common feature for nearly all processing schemes developed for these devices. Copper is typically introduced in CdTe during the application of the back electrode, to enhance device performance by facilitating the formation of an ohmic back contact. However, Cu has also been associated with observed instability in CdTe. For this work, although Cu was utilized during the cell fabrication process, it was eliminated from the back contact formation step, and instead introduced in the CdS film prior to the deposition of the CdTe. The only fabrication step, where Cu was intentionally introduced, was subsequent to the CdS deposition. Both plain graphite and Sb2Te3/Mo were used as back contacts. Solar cell results suggested that ohmic contacts to CdTe can be attained with undoped graphite as the back electrode. For devices contacted with plain graphite VOC's and FF's in the range of 800-830 mV and 63-67% have been obtained. For Sb2Te3-contacted cells, the incorporation of Cu in CdS has lead to a significant increase in performance even though a back barrier was present in these cells.
Venue	IEEE
Sources	National Renewable Energy Laboratory; University of South Florida, Tampa
Document Type	Conference Papers (Word document)
Resource Date	10/2004

Post Date	02/09/2005
Title	RF SPUTTER ETCH AS A SURFACE CLEANING PROCESS FOR CDTE SOLAR CELLS
Link	(MS Word 171 KB)
Authors	V. Viswanathan, et al.
Description	The primary objective of this work is to investigate the potential of an alternative dry, vacuum-based process, as a surface modification step for CdTe prior to the application of the back contact electrode. RF-sputter etch has been used as an alternative surface cleaning process. The process was optimized for the type of etchant gas, pressure, time, and sputter power. Solar cells exhibited VOC's greater than 830 mV and FF's in the high 60's. This performance demonstrates the potential of this process for the development of an all-dry vacuum based CdTe technology.
Venue	IEEE
Source	University of South Florida, Tampa
Document Type	Conference Papers (Word document)
Resource Date	10/2004

Post Date	02/09/2005
Title	THE INFLUENCE OF VARIOUS FRONT CONTACT MATERIALS ON THE PERFORMANCE OF CDTE SOLAR CELLS
Link	(MS Word 201 KB)
Authors	R. Mamazza, et al.
Description	The use of a resistive, or buffer, layer in the front con-tact structure of CdTe solar cells has been known to improve solar cell performance, in particular when the CdS thickness is relatively small. This paper reviews the performance of CdTe solar cells fabricated on various front contact bi-layer combinations. Conductive (low-r) trans-parent oxides utilized for this work include SnO₂:F, Cd₂SnO₄ and ITO; resistive (high-r) transparent oxides include SnO₂, In₂O₃, and Zn₂SnO₄. All high-r layers were found to be effective within a range of processing condi-tions and process/device characteristics. Buffer layers of Zn-Sn-O appear to be the most promising high-? films for the fabrication of CdTe cells with small CdS thickness without compromising the V_OC and FF.
Venue	IEEE PVSC
Source	University of South Florida, Tampa
Document Type	Conference Papers (Word document)
Resource Date	10/2004

Post Date	02/11/2005
Title	EXPERIMENTAL INVESTIGATION OF EMISSIONS AND REDISTRIBUTION OF ELEMENTS IN CDTE PV MODULES DURING FIRES
Link	(PDF 246 KB) Download Acrobat Reader.
Authors	V. Fthenakis, et al.
Description	This study is based on glass-glass CdTe PV modules which are the only ones in the market. Pieces of commercial CdTe photovoltaic (PV) modules, sizes 3.8 cm by 30.5 cm, were heated to temperatures up to 1100ºC to simulate exposure to residential and commercial building fires. The temperature rate and duration in these experiments were defined according to standard UL and ASTM test protocols. Three different types of analysis were performed: measurements of sample weight loss as a function of temperature; analyses of Cd in the fire emissions; and analysis of Cd distribution in the molten glass, using Synchrotron x-ray fluorescence microprobe. It was found that a small amount of cadmium compounds (0.4 to 0.6% of the Cd content) was carried to the edges by the flow of EVA decomposition products. The pathway for this loss was through the perimeter of the sample before the two sheets of glass fused together. In actual size PV modules, the ratio of perimeter to area is 13.5 times smaller; thus the actual Cd loss during fires would be insignificant (<0.04% of the Cd content).
Venue	European PV Solar Energy Conference, Paris, France, June 7-11, 2004; Paper 5BV.1.32
Source	Brookhaven National Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2004

Post Date	02/09/2005
Title	THE STATUS OF AND CHALLENGES IN CDTE THIN-FILM SOLAR-CELL TECHNOLOGY
Link	(PDF 160 KB) Download Acrobat Reader.
Author	A. Compaan
Description	Polycrystalline CdTe thin- film solar cells have shown high potential for low cost, large-area module fabrication. But successful large-scale commercial production has been elusive. Fabrication of the basic n-CdS / p-CdTe heterojunction is possible by a wide variety of methods, including close-spaced sublimation, vapor-transport deposition, electrodeposition, chemical bath deposition, and magnetron sputtering. An overview of these methods is presented as well as the role of the postdeposition "activation" treatment using CdCl₂.
Venue	Spring 2004 MRS Symp. Amorphous and Nanocrystalline Silicon Science and Technology Proceedings to appear as MRS Symp. Proc.
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2004

Post Date	02/14/2005
Title	CIGS J-V DISTORTION IN THE ABSENCE OF BLUE PHOTONS
Link	(MS Word 158 KB)
Authors	A. O. Pudov, et al.
Description	Common buffer materials used with CuInGaSe₂ (CIGS) absorbers produce conduction-band barriers that may significantly distort the current-voltage curves, especially when short-wavelength photons are excluded from the illumination spectrum. Earlier work documented this effect for CuInSe₂ (CIS) absorbers (band gap near 1.0 eV) with CdS buffers. Higher band-gap (~1.15 eV) CIGS absorbers show little or no distortion with CdS buffer layers. However, wider band-gap (lower electron affinity) ZnS(O,OH) or InS(O,OH) buffers, prepared by chemical-bath deposition, clearly show the J-V distortion. The distortions have a turn-on time constant the order of a minute and turn-off time constant the order of a day, and they correlate with major variations in apparent quantum efficiency measured with varying intensity and spectral content of bias light. The results are consistent with a conduction-band spike barrier that increases with buffer band gap and is larger when the electron concentration in the buffer is small.
Venue	EMRS
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	2004

Post Date	02/08/2005
Title	COPPER INCLUSION AND MIGRATION FROM THE BACK CONTACT IN CDTE SOLAR CELLS
Link	(MS Word 791 KB)
Authors	C. R. Corwine, et al.
Description	Metallic back contacts to CdS/CdTe solar cells will in general form Schottky barriers. Better performance is achieved with the inclusion of Cu in the back contact. This study uses current-voltage, capacitance-voltage, and laser beam induced current measurements to analyze as-deposited CdS/CdTe solar cells prepared with varying back contact Cu amounts and to evaluate changes in cell performance following elevated-temperature stress. A simple model is proposed to explain both the observed differences in device behavior as copper is added or removed from the contact region, and how copper movement depends on electrical bias.
Venue	Draft
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	2004

Post Date	02/07/2005
Title	POLYCRYSTALLINE THIN-FILM PHOTOVOLTAIC TECHNOLOGIES: PROGRESS AND TECHNICAL ISSUES
Link	(PDF 370 KB) Download Acrobat Reader.
Author	H. S. Ullal
Description	Polycrystalline thin-film materials based on copper indium diselenide (CuInSe2, CIS) and cadmium telluride (CdTe) are promising thin-film solar cells for various power and specialty applications. Impressive results have been obtained in the past few years for both thin-film copper indium gallium diselenide (CIGS) solar cells and thin-film CdTe solar cells. NCPV/NREL scientists have achieved world-record, total-area efficiencies of 19.3% for a thin-film CIGS solar cell and 16.5% for thin-film CdTe solar cell. A number of technical R&D issues related to CIS and CdTe have been identified. Thin-film power module efficiencies up to 13.4% has been achieved thus far. Tremendous progress has been made in the technology development for module fabrication, and multi-megawatt manufacturing facilities are coming on line with expansion plans in the next few years. Several 40-480 kW polycrystalline thin-film, grid-connected PV arrays have been deployed worldwide. Hot and humid testing is also under way to validate the long-term reliability of these emerging thin-film power products. The U.S. thin-film production (amorphous silicon [a-Si], CIS, CdTe) is expected to exceed 50 MW by the end of 2005.
Venue	PVSEC 19
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/09/2005
Title	CONTINUOUS, IN-LINE PROCESSING OF CDS/CDTE DEVICES: PROGRESS TOWARDS CONSISTENT STABILITY
Link	(PDF 98 KB) Download Acrobat Reader.
Authors	K. L. Barth, R. A. Enzenroth, W. S. Sampath
Description	Two results pertaining to CdTe device stability are presented here: 1) The process conditions, particularly the CdCl 2 treatment, have a significant effect on device stability and 2) a saturation in the loss of efficiency over time in accelerated indoor stress has been observed for a large number of devices. CdTe, degradation, fabrication...
Venue	EuroPV
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/09/2005
Title	STABILIZATION OF HIGH-EFFICIENCY CDTE PHOTOVOLTAIC MODULES IN CONTROLLED INDOOR LIGHT SOAKING
Link	(PDF 330 KB) Download Acrobat Reader.
Authors	D. Cunningham, J. Pruett, J. A. del Cueto
Description	The performance and stabilization of large-area, high-efficiency 9%, CdTe photovoltaic (PV) modules maintained under controlled light-soaking nominally at 800 Watts/m² irradiance and 65°C module temperature are investigated. Degradation of module performance occurs predominantly in the first few hundred hours of exposure under these conditions; these symptoms included losses in fill factor (FF), open-circuit voltage (V_oc), and short-circuit current (I_sc), which amount to between 7% and 15% total loss in performance. Higher stabilized performance was achieved with lower copper content in the back contact. Transient effects in module V...
Venue
Sources	BP Solar; National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/08/2005
Title	CDTE BACK CONTACT: RESPONSE TO COPPER ADDITION AND OUT-DIFFUSION
Link	(PDF 345 KB) Download Acrobat Reader.
Authors	C. Jenkins, et al.
Description	The back-contact barrier of CdTe solar cells plays an important role in cell operation, and it is substantially altered by both the amount of copper used in forming the contact and the movement of copper away from the contact during elevated temperature stress. It is shown that a simple model can explain the differences in current-voltage curves, cell uniformity, and capacitance as copper is added or moved out of the contact region, as well as the dependence of copper movement on electrical bias.
Venue	draft
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/09/2005
Title	CU K-EDGE X-RAY FINE STRUCTURE CHANGES IN CDTE WITH CDCL₂ PROCESSING
Link	(PDF 86 KB) Download Acrobat Reader.
Authors	A. Compaan, X. Liu, et al.
Description	MR-CAT beamline of the Advanced Photon Source at Argonne National Laboratory to study the fine structure in the Cu K-edge x-ray absorption in 3 mm thick polycrystalline films of CdTe on fused silica. 4 nm of evaporated Cu is diffused either with or without prior vapor CdCl₂ treatments in dry air. Cu absorption is monitored through the Cu K a fluorescence using a 13 element Ge detector. The radial distribution junction inferred from the absorption fine structure indicates predominantly Cu₂Te when Cu is diffused into the as deposited CdTe film but indicates a Cu_xO environment when Cu is diffused after the vapor CdCl₂ treatment.
Venue	European MRS
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/07/2005
Title	TECHNOLOGY AND MARKET CHALLENGES TO MAINSTREAM THIN-FILM PHOTOVOLTAIC MODULES AND APPLICATIONS
Link	(PDF 276 KB) Download Acrobat Reader.
Author	R. Arya
Description	Technology and manufacturing advances over the past 25 years has led to widespread commercial use of thin film modules in many consumer applications. The three leading thin film solar module technologies are - amorphous silicon alloys (a-Si), copper indium diselenide alloys (CIGS), and cadmium telluride CdTe). These three technologies have demonstrated solar cells with efficiencies ~13% (a-Si), ~19% (CIGS), and ~16.5% (CdTe) respectively. Large area power modules are in various stages of initial production with these technologies and the module performance is in the 6%-11% range. Several manufacturing plants are in operation with plant capacities ranging from 3 MW to 30 MW. These plants are continuously increasing production with the present annual production of 1 MW to 5 MW. Technical challenges lie ahead in improving the module performance by reducing the gap between R&D cells and manufactured products so that they can successfully compete with crystalline silicon modules. Reliability of thin film modules in systems has been demonstrated with all three technologies with a fair degree of success. Several 1-480 kW grid-connected thin film module arrays are in deployment worldwide. Thin film modules are finding increasing acceptance for BIPV applications like roofs, facades, awnings etc. used in residential and commercial buildings. The cost of modules and market acceptance with new technologies still remains a major challenge to successful penetration of mainstream photovoltaic markets.
Venue
Source	N/A
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/10/2005
Title	QUANTUM EFFICIENCY OF CDTE SOLAR CELLS IN FORWARD BIAS
Link	(PDF 234 KB) Download Acrobat Reader.
Authors	M. Gloeckler, J. R. Sites
Description	The quantum efficiency of a CdS/CdTe solar cell is measured under forward voltage, the measurement is likely affected by several factors including (1) the voltage dependence of the collection efficiency, (2) series resistance of the cell and instrumentation, (3) the electrical barrier of the back contact, (4) photoconductive effects in the CdS and CdTe, and (5) any secondary barrier in the primary junction. Each of these effects has a distinct signature, but without careful attention to these signatures, misinterpretation is possible and perhaps common. The approach here is to numerically simulate effect (1), and then progressively add effects (2), (3), (4), and (5). In each case, we show the characteristic signature of the apparent quantum efficiency when voltage is varied, we discuss the effect of bias light on the quantum efficiency measurement, we compare when possible with analytical modeling, and we show the impact of each effect on the cell's current-voltage curves, particularly the light/dark crossover. Although the presentation will be specific to CdTe cells, the principles should at least in part apply to other solar cells as well.
Venue	Paris 2004
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/09/2005
Title	NUMERICAL MODELING OF CIGS AND CDTE SOLAR CELLS: SETTING THE BASELINE
Link	(MS Word 669 KB)
Authors	M. Gloeckler, et al.
Description	Numerical modeling of polycrystalline thin-film solar cells is an important strategy to test the viability of proposed physical explanations and to predict the effect of physical changes on cell performance. In general, this must be done with only partial knowledge of input parameters. Nevertheless, for consistent comparisons between laboratories, it is extremely useful to have a common starting point, or baseline. We will discuss guidelines that should be considered assigning input parameters for numerical modeling. Consequently specific baseline parameters for CIGS and CdTe are proposed. The modeling results for these baseline cases are presented and it is discussed how the baseline cases serve to describe some of the most important complications that are often found in experimental CIGS and CdTe solar cells.
Venue	IEEE
Source	Colorado State University
Document Type	Conference Papers (Word document)
Resource Date	2004

Post Date	02/04/2005
Title	POLYCRYSTALLINE THIN-FILM PHOTOVOLTAIC TECHNOLOGIES: PROGRESS AND TECHNICAL ISSUES
Link	(MS Word 1.5 MB)
Author	H. S. Ullal
Description	Polycrystalline thin-film materials based on copper indium diselenide (CuInSe2, CIS) and cadmium telluride (CdTe) are promising thin-film solar cells for various power and specialty applications. Impressive results have been obtained in the past few years for both thin-film copper indium gallium diselenide (CIGS) solar cells and thin-film CdTe solar cells. NCPV/NREL scientists have achieved world-record, total-area efficiencies of 19.3% for a thin-film CIGS solar cell and 16.5% for thin-film CdTe solar cell. A number of technical R&D issues related to CIS and CdTe have been identified. Thin-film power module efficiencies up to 13.4% has been achieved thus far. Tremendous progress has been made in the technology development for module fabrication, and multi-megawatt manufacturing facilities are coming on line with expansion plans in the next few years. Several 40-480 kW polycrystalline thin-film, grid-connected PV arrays have been deployed worldwide. Hot and humid testing is also under way to validate the long-term reliability of these emerging thin-film power products. The U.S. thin-film production (amorphous silicon [a-Si], CIS, CdTe) is expected to exceed 50 MW by the end of 2005.
Venue	PVSEC
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	2004

Post Date	02/08/2005
Title	CONTINUOUS, IN-LINE PROCESSING OF CDS/CDTE DEVICES: PROGRESS TOWARDS CONSISTENT STABILITY
Link	(PDF 98 KB) Download Acrobat Reader.
Authors	K. L. Barth, R. A. Enzenroth, W. S. Sampath
Description	A technology for continuous in-line processing of thin film CdS/CdTe devices has been developed in our laboratory. A CdTe PV device fabrication system has been operating for approximately 6 years and a full prototype manufacturing system for 16.5 x 16.5 inch substrates is under construction. Utilizing this technology, it has been demonstrated that at optimum process conditions good device stability (resistance to performance degradation) can be obtained. Two results pertaining to CdTe device stability are presented here: 1) The process conditions, particularly the CdCl₂ treatment...
Venue	EuroPV
Source	Colorado State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/09/2005
Title	CU K-EDGE XAFS IN CDTE BEFORE AND AFTER TREATMENT WITH CDCL₂
Link	(PDF 204 KB) Download Acrobat Reader.
Authors	X. Liu, et al.
Description	We have used the fine structure in the Cu K-edge x-ray absorption spectrum to help elucidate the lattice location of Cu in polycrystalline, thin-film CdTe solar cells. In particular, we have studied how the typical CdCl₂ vapor treatment in dry air changes the local environment of the Cu in CdTe. We find the Cu absorption spectrum to be similar to that of Cu₂Te in the asdeposited CdTe film but to convert to a spectrum similar to Cu₂O environment after the vapor CdCl₂ treatment.
Venue	Materials Research Society Symposium Proceedings spring 2003, Symposium B "Compound Semiconductor Photovoltaics," paper B3.5
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/01/2003

Post Date	02/09/2005
Title	THE MESOSCALE PHYSICS OF LARGE-AREA PHOTOVOLTAICS
Link	(PDF 252 KB) Download Acrobat Reader.
Authors	V. G. Karpov, et al.
Description	Recent findings make the physics of large-area thin-film devices a distinctive field of its own, considerably different from that of microelectronics. We show that (i) large-area thin-film photovoltaic (PV) devices are intrinsically nonuniform in the lateral directions, (ii) the nonuniformity spans over microscopically large dimensions, which can vary dramatically (from microns to meters) depending on light intensity and bias, and (iii) the nonuniformity significantly impacts the device performance and stability. Our understanding suggests the concept of interfacial layer that blocks the nonuniformity effects and can be applied photo-electrochemically. This concept is experimentally verified.
Venue	29th IEEE Osaka
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/16/2003

Post Date	02/11/2005
Title	CDTE PV: REAL AND PERCEIVED EHS RISKS
Link	(PDF 216 KB) Download Acrobat Reader.
Authors	V. Fthenakis, K. Zweibel
Description	As CdTe photovoltaics reached commercialization, questions were raised about potential cadmium emissions from CdTe PV modules. Some have attacked the CdTe PV technology as unavoidably polluting the environment, and made comparisons of hypothetical emissions from PV modules to cadmium emissions from coal-fired power plants. This paper gives an overview of the technical issues pertinent to these questions and further explores the potential of environmental, health, and safety (EHS) risks during production, use, and decommissioning of CdTe PV modules. The following issues are discussed: (a) the physical and toxicological properties of CdTe, (b) comparisons of Cd use in CdTe PV with its use in other technologies and products, and (c) the possibility of CdTe releases from PV modules. cells.
Venue	NCPV and Solar Program Review Meeting 2003 NREL/CD-520-33586 Page 413
Sources	Brookhaven National Laboratory; National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/09/2005
Title	MANUFACTURING AND TECHNOLOGY DEVELOPMENT PROGRAMS AT FIRST SOLAR
Link	(PDF 334 KB) Download Acrobat Reader.
Authors	A. Abken, et al.
Description
Venue	NCPV and Solar Program Review NREL/CD-520-33586
Source	First Solar, Toledo, OH
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/02/2005
Title	COMPARISON OF ENERGY PRODUCTION AND PERFORMANCE FROM FLAT-PLATE PHOTOVOLTAIC MODULE TECHNOLOGIES DEPLOYED AT FIXED TILT
Link	(PDF 206 KB) Download Acrobat Reader.
Author	J. A. del Cueto
Description	energy rating by technology
Venue
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/07/2005
Title	PRACTICAL DOPING PRINCIPLES
Link	(PDF 270 KB) Download Acrobat Reader.
Author	A. Zunger
Description	Doping compound semiconductors.
Venue	NREL DOE Solar Program Review Meeting 2003
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/07/2005
Title	PROGRESS IN U.S. PHOTOVOLTAICS: LOOKING BACK 30 YEARS AND LOOKING AHEAD 20
Link	(PDF 310 KB) Download Acrobat Reader.
Author	T. Surek
Description	Technology and learning curve analysis of R&D.
Venue	Osaka IEEE
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/09/2005
Title	TEMPERATURE-DEPENDENT ELECTROLUMINESCENCE FROM CDTE/CDS SOLAR CELLS
Link	(PDF 87 KB) Download Acrobat Reader.
Authors	K. J. Price, et al.
Description	Electroluminescence (EL) from polycrystalline CdTe/CdS solar cells was studied over the temperature range ? 30 C to 25 C. We are able to observe above-background EL at forward current densities as low as 3 mA/cm², allowing us to explore the EL behavior at current-voltage regimes within the normal operating parameters of the device. The EL spectrum is very similar to the photoluminescence (PL) spectrum, and is independent of applied voltage. We show that the EL most likely originates from injected electron-hole recombination at the CdTe/CdS junction. The total EL intensity is found to vary as a power-law function of current...
Venue	MRS 2003
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/10/2005
Title	PERTURBATION OF COPPER SUBSTITUTIONAL DEFECT CONCENTRATIONS IN CDS/CDTE HETEROJUNCTION SOLAR CELL DEVICES
Link	(PDF 565 KB) Download Acrobat Reader.
Authors	D. Albin, et al.
Description	The efficacy of implementing terrestrial-based photovoltaics is dictated by trade-offs in device performance, cost, and reliability. Presently, the highest efficiency polycrystalline CdS/CdTe superstrate solar cells utilize back contacts containing copper as an intentional dopant. Accelerated stress data correlates copper diffusion from this contact with performance degradation. Degradation at the device level exhibits two characteristic modes that are influenced by CdTe surface treatments prior to contacting. Rapid degradation associated with a rapidly decreasing open-circuit voltage can occur in cases where processing favors stoichiometric CdTe surfaces. Slower degradation associated with roll-over is typified by treatments favoring the presence of Te at the back contact. The chemical composition and extent of Te-rich contact interfaces is revealed by transmission electron microscopy. Deep-level transient spectroscopy of NP etched and non-etched devices show Te-rich conditions are necessary for the detection of deep-acceptor Cu_Cd defect levels...
Venue	Proceedings of Symposium F, 2002 Spring Meeting of the Materials Research Society San Francisco, CA April 1-5, 2002
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2002

Post Date	02/09/2005
Title	MICRONONUNIFORMITY EFFECTS IN THIN-FILM PHOTOVOLTAICS
Link	(PDF 350 KB) Download Acrobat Reader.
Authors	A. Compaan, V. G. Karpov, D. Shvydka
Description	We discuss effects of micrononuniformities on thin-film photovoltaics. The key factors are the device large area and the presence of potential barriers. We model the nonuniformity effects in the terms of random microdiodes connected in parallel through a resistive electrode. The microdiodes of low open circuit voltages affect macroscopically large regions. They strongly reduce the device performance and induce its nonuniform degradation in several different modes. We support our predictions by experiments.
Venue	2002 IEEE PVSC
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2002

Post Date	02/08/2005
Title	EXTERNAL BIAS EFFECT ON JUNCTION PHOTOLUMINESCENCE IN CDS/CDTE SOLAR CELLS
Link	(PDF 421 KB) Download Acrobat Reader.
Authors	A. Compaan, V. G. Karpov, D. Shvydka
Description	Study photoluminescence (PL) from the CdS/CdTe solar-cell junction region. We observed that applied external bias V does not change the spectral shape of the PL signal, but significantly affects the integral PL intensity I(V). It increases with moderate forward bias, tends to saturate when V is above the open-circuit voltage and is suppressed for reverse bias.
Venue	IEEE
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2002

Post Date	02/07/2005
Title	PV SOLAR ELECTRICITY: ONE AMONG THE NEW MILLENNIUM INDUSTRIES
Link	(PDF 6.0 MB) Download Acrobat Reader.
Author	W. Hoffmann
Description	ABSTRACT: During recent years, solar electricity generation based on photovoltaics has developed into an industry at annual growth rates above 20%. Major market segments served by this industry comprise consumer applications, remote industrial systems, developing countries, and grid-connected systems. The potential in these markets supports sustained future growth, particularly for applications in developing countries and gridconnected systems in the industrial countries, where PV-generated electricity eventually will start to compete with peak grid power. Backed by price experience curves and a laboratory proven technology road map, a module turnover representing 100 billion worlwide can be extrapolated. A sustainable energy contribution to the worldwide energy mix in subsequent decades is foreseen as a result of competitive PV solar electricity applications. Keywords: PV Market Growth ? 1: Strategy ? 2: Cost Reduction ? 3
Venue	17th European Photovoltaic Solar Energy Conference, Munich, Germany, 22-26 October 2001
Source	RWE Schott
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2001

Post Date	02/09/2005
Title	EFFECT OF CDTE THICKNESS REDUCTION IN HIGH EFFICIENCY CDS/CDTE SOLAR CELLS
Link	(PDF 76 KB) Download Acrobat Reader.
Authors	A. Gupta, et al.
Description	High efficiency CdTe solar cells are typically grown with CdTe thicknesses from 3 to 15 mm, although the thickness required for 90% absorption of the incident irradiation at 800 nm is only ~1 mm. In this paper, we present the effect of CdTe thickness reduction on the performance of CdS/CdTe solar cells in which both the CdS and CdTe films were grown by sputtering. We produced a series of cells with different CdTe thickness (from 0.5 to 3.0 mm), and held the CdS thickness and back-contact-processing constant. The effect of CdTe thickness reduction on the diffusion of CdS into CdTe was studied using optical absorption and x-ray diffraction techniques. Only slight decreases occur in open-circuit voltage, short-circuit current, and fill factor with decrease in CdTe film thickness to 1.0 �m. Almost 10% efficient cells were obtained with 1 mm CdTe. Below 1 mm, all cell parameters decrease more rapidly, including the red quantum efficiency.
Venue	Mat. Res. Soc. Symp. Proc. Vol. 668
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2001

Post Date	02/09/2005
Title	PRECONTACT SURFACE CHEMISTRY EFFECTS ON CDS/CDTE SOLAR CELL PERFORMANCE AND STABILITY
Link	(PDF 76 KB) Download Acrobat Reader.
Authors	D. Albin, S. E. Asher, D. Levi, et al.
Description
Venue	28th IEEE PVSC
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2000

Post Date	02/09/2005
Title	NONUNIFORM POWER GENERATION IN CDTE MODULES
Link	(PDF 516 KB) Download Acrobat Reader.
Authors	G. Dorer, R. Harju, V. G. Karpov
Description
Venue	IEEE PVSC
Source	First Solar, Toledo, OH
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2000

Post Date	02/11/2005
Title	HEALTH, SAFETY AND ENVIRONMENTAL ISSUES IN THIN FILM MANUFACTURING
Link	(PDF 50 KB) Download Acrobat Reader.
Authors	E. A. Alsema, et al.
Description	An investigation is made of Health, Safety and Environmental (HSE) aspects for the manufacturing, use and decommissioning of CdTe, CIS and a-Si modules. Issues regarding energy requirements, resource availability, emissions of toxic materials, occupational health and safety and module waste treatment are reviewed. Waste streams in thin film module manufacturing are analyzed in detail and treatment methods are discussed. Finally the technological options for thin film module recycling are investigated. It is concluded that there are no serious HSE bottlenecks for upscaling to production levels of 500 MWp/yr and that adequate methods are available for treatment of the manufacturing wastes. However, on the longer term issues regarding CdTe and CIS module waste treatment, In and Te resource availibility and module recycling need to adressed. Appropriate recycling methods for CdTe and CIS modules do not exist at present but the problem is being adressed by the PV industry.
Venue
Source	Utrecht University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2000

Post Date	02/11/2005
Title	FIRST SOLAR'S CDTE MODULE MANUFACTURING EXPERIENCE; ENVIRONMENTAL, HEALTH AND SAFETY RESULTS
Link	(PDF 203 KB) Download Acrobat Reader.
Authors	J. R. Bohland, K. Smigielski
Description	Consistent with First Solar's proactive cadmium-containing material management practices such as CdTe PV module recycling, this paper reviews our activities and results in preventing environmental exposures and human health risks associated with cadmium materials processing during module manufacturing. Industrial hygiene data for manufacturing activities are presented and engineering controls are discussed. Medical monitoring results comparing recently hired to long-term employees and smokers is reported. Environmental releases to air, water and land have been quantified.
Venue
Source	First Solar, Toledo, OH
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	1999

Post Date	02/09/2005
Title	PROGRESS TOWARD CDTE CELL LIFE PREDICTION
Link	(PDF 1.9 MB) Download Acrobat Reader.
Authors	G. J. Jorgensen, T. J. McMahon
Description	Acclerated environmental testing.
Venue	NCPV PV Program Review 1999
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	1999

Presentations

Post Date	05/18/2006
Title	HIGH EFFICIENCY CDTE AND CIGS
Link	(PowerPoint 28.8 MB)
Author	R. Noufi
Description	Highlights and challenges
Venue	WCPEC4 oral
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/2006

Post Date	06/13/2006
Title	CDTE NATIONAL R&D TEAM MEETING 2006
Link	(PDF 17.3 MB) Download Acrobat Reader.
Author	H. S. Ullal
Description	The presentations from the National R&D Team meeting and Voc Workshop; Large file!
Venue	National R&D Team meeting
Source	National Renewable Energy Laboratory
Document Type	Presentation (Adobe Postscript file)
Resource Date	03/2006

Post Date	12/08/2005
Title	ELECTRONIC STATES THAT CONTROL THE PERFORMANCE OF CDTE SOLAR CELLS
Link	(PowerPoint 1.1 MB)
Author	F. H. Seymour
Description	Admittance spectroscopy, defect correlation
Venue	NREL seminar Dec 7, 2005
Source	Colorado School of Mines, Golden, CO
Document Type	Presentation (Powerpoint presentation)
Resource Date	12/07/2005

Post Date	11/11/2005
Title	THIN FILM PV PARTNERSHIP PROGRAM 2005
Link	(PowerPoint 10.8 MB)
Author	K. Zweibel
Description	Overview of the purpose, strategies, and goals of the Thin Film Partnership Program, including updated module, BOS, and system cost projections for 2005 and 2020.
Venue	2005 DOE Solar Review
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/10/2005

Post Date	11/11/2005
Title	ADVANCES IN CDTE R&D AT NREL
Link	(PowerPoint 1.5 MB)
Author	X. Wu
Description	Summary of efficiency, TCO, contact, and processing achievements in CdTe
Venue	2005 DOE Solar Review
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/2005

Post Date	11/11/2005
Title	UNDERSTANDING THE PHYSICS OF CDS PV
Link	(PowerPoint 3.2 MB)
Author	V. G. Karpov
Description	piezo electric effect discussed
Venue	2005 DOE Solar Review
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/2005

Post Date	11/18/2005
Title	HOT AND HUMID THIN FILM MODULE TESTING IN FLORIDA
Link	(JPG 1.2 MB)
Author	N. G. Dhere
Description	various arrays are tested
Venue	DOE Solar Review 2005 poster
Source	FLorida Solar Energy Center
Document Type	Presentation (JPG image)
Resource Date	11/2005

Post Date	11/17/2005
Title	THIN CDTE CELLS AND HIGH THROUGHPUT PROCESSING
Link	(PowerPoint 3.0 MB)
Author	B. E. McCandless
Description	under 1 micron CdTe; fast deposition
Venue	Solar Review 2005
Source	University of Delaware
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/2005

Post Date	11/17/2005
Title	TECHNOLOGY IN SUPPORT OF THIN FILM CDTE PV MODULE MANUFACTURING
Link	(PowerPoint 9.6 MB)
Author	P. V. Meyers
Description	status of First Solar 2005
Venue	DOE Solar Review 2005
Source	First Solar, Toledo, OH
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/2005

Post Date	11/04/2005
Title	PROGRESS IN CONTINUOUS IN-LINE CDS/CDTE DEPOSITION
Link	(PowerPoint 3.9 MB)
Author	W. S. Sampath
Description	Progress at CSU AVA Technologies in 2005
Venue	DOE Solar Review Meeting
Sources	AVA Technologies; Colorado State University
Document Type	Presentation (Powerpoint presentation)
Resource Date	11/2005

Post Date	11/23/2005
Title	NANOSCALE-DESIGNED CERAMIC FILMS
Link	(PDF 1.9 MB) Download Acrobat Reader.
Author	S. Sambasivan
Description	thermal barriers, conformal alumina films, epitaxial oxide growth
Venue	Nanocommerce 2004, Chicago
Source	Applied thin films
Document Type	Presentation (Adobe Postscript file)
Resource Date	10/2005

Post Date	09/02/2005
Title	PV PAST THE TIPPING POINT
Link	(PowerPoint 31.8 MB)
Author	K. Zweibel
Description	Photovoltaics is growing rapidly, coming down in cost, and technical progress is substantial. We can be assured that PV costs will come down enough to provide electricity at an energy signifiant level.
Venue	Presntation at NREL to Norwegian StudyTour sponsored by CSM August 31, 2005
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	08/31/2005

Post Date	07/28/2005
Title	2002 TO 2005 THIN FILM PARTNERSHIP BUDGET TRENDS
Link	(PowerPoint 38 KB)
Author	K. Zweibel
Description	Budget in thin films for subcontracts is down 36% since 2002.
Venue
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	07/2005

Post Date	06/14/2005
Title	INTEGRATED SYSTEMS FOR SOLAR RESEARCH: DAISY-SOL
Link	(PDF 477 KB) Download Acrobat Reader.
Authors	J. Fritsche, W. Jaegermann
Description	Setup CSS-CdTe CSS-CdS Chem. all in-situ solar cell manufacturing 2 dynamic CSS-chambers UHV-activation (in construction) backcontact formation (evaporation, sputtering) in-situ XPS/UPS-characterisation Rms [nm]
Venue	20th EU PVSC, Barcelona, presentation
Source	Technische Universitat Darmstadt
Document Type	Presentation (Adobe Postscript file)
Resource Date	06/2005

Post Date	06/14/2005
Title	EMPIRICAL TUNING METHO FOR AS AND CL DOPING OF MOCVD CDTE
Link	(PDF 2.9 MB) Download Acrobat Reader.
Author	V. Barrioz
Description	doping studies of MOCVD CdTe
Venue	20th EU PVSC, Barcelona, SuperGen
Source	University of Wales
Document Type	Presentation (Adobe Postscript file)
Resource Date	06/2005

Post Date	05/10/2005
Title	13.9% EFFICIENT TRANSPARENT CDTE CELL WITH NIR TRNASMISSION OF ABOUT 50%
Link	(PowerPoint 1.8 MB)
Authors	X. Wu, et al.
Description
Venue	CdTe National R&D Team
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/06/2005

Post Date	05/09/2005
Title	COPPER AND BUFFER LAYER EFFECTS
Link	(PowerPoint 13.5 MB)
Authors	D. Albin, S. Demetsu
Description
Venue	CdTe R&D Team
Sources	Colorado State University; National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	BIFACIAL CDS/CDTE/ZNTE DEVICE CHARACTERIZATION
Link	(PowerPoint 645 KB)
Authors	D. Desai, S. S. Hegedus
Description
Venue	CdTe National R&D Team
Source	University of Delaware
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	INFLUENCE OF BAND PROFILES ON TRANSPORT AND RECOMBINATION IN CDTE
Link	(PowerPoint 2.4 MB)
Author	A. Fahrenbruch
Description
Venue	CdTe R&D Team
Source	Colorado State University
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	NONLINEAR SHUNTING IN CDTE
Link	(PowerPoint 201 KB)
Authors	V. G. Karpov, D. Shvydka
Description
Venue	CdTe R&D Team
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	PROGRESS AT AVA TECHNOLOGIES
Link	(PowerPoint 2.0 MB)
Authors	K. L. Barth, et al.
Description
Venue	CdTe R&D Team
Source	AVA Technologies
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	HOW THIN FILM PV CAN BE DIFFERENT
Link	(PowerPoint 122 KB)
Author	V. G. Karpov
Description	different device models of CdTe cells, weak diodes, MIS, degradation
Venue	CdTe R&D Team
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	CDTE STABILITY SUBTEAM
Link	(PowerPoint 911 KB)
Author	D. Albin
Description
Venue	CdTe R&D Team
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	ESTIMATION OF ACCELERATION FACTORS BY COMPARISON OF PERFORMANCE DURING ACCELERATED STRESS AND IN OUTDOOR CONDITIONS
Link	(PowerPoint 188 KB)
Author	R. A. Enzenroth
Description
Venue	CdTe R&D Team
Source	Colorado State University
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	STABILITY OF CDS/CDTE WITH AG AND NI BACK CONTACTS
Link	(PowerPoint 2.4 MB)
Authors	D. Albin, A. Davies, S. Demetsu, T. J. McMahon, J. W. Pankow
Description
Venue	CdTe R&D Team
Sources	Colorado State University; National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	CU AND CDCL2 INFLUENCE ON DEEP DEFECTS IN CDTE CELLS
Link	(PowerPoint 285 KB)
Authors	D. Albin, V. Kaydanov, T. Ohno, F. H. Seymour
Description
Venue	CdTe R&D Team
Sources	Colorado School of Mines, Golden, CO; National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	CONDUCTIVE ATOMIC FORCE MICROSCOPY APPLIED TO CDTE/CDS CELLS
Link	(PowerPoint 3.2 MB)
Authors	H. Moutinho, et al.
Description
Venue	CdTe R&D Team
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	CHOOSING DEFECT PROPERTIES FOR DEVICE MODELING
Link	(PowerPoint 1.1 MB)
Author	A. Fahrenbruch
Description
Venue	CdTe R&D Team
Source	Colorado State University
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	LUMINESCENCE STUDIES ON CU AND O DEFECTS IN CRYSTALLINE AND THIN CDTE
Link	(PDF 1.9 MB) Download Acrobat Reader.
Authors	C. R. Corwine, et al.
Description
Venue	May 2005 CdTe National R&D Team meeting
Sources	Colorado State University; National Renewable Energy Laboratory
Document Type	Presentation (Adobe Postscript file)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	MATERIALS CHEMISTRY AND ANALYSIS
Link	(PowerPoint 47 KB)
Author	B. E. McCandless
Description
Venue	CdTe R&D Team
Source	University of Delaware
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	CDS:CU AND BUFFER LAYERS
Link	(PowerPoint 496 KB)
Authors	C. S. Ferekides, et al.
Description
Venue	CdTe R&D Team
Source	University of South Florida, Tampa
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/11/2005
Title	SOLAR FIELDS, LLC
Link	(PowerPoint 1.2 MB)
Author	K. Kormanyos
Description	Introduction to status and plans
Venue	National CdTe R&D Meeting
Source	Solar Fields
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	CDS/CDTE THICKNESS AND O2 EFFECTS ON STABILITY
Link	(PowerPoint 1.5 MB)
Authors	D. Albin, S. Demetsu, T. J. McMahon
Description
Venue	CdTe R&D Team
Sources	Colorado State University; National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	EFFECT OF APPLIED BIAS DURING STRESS: OLD AND NEW RESULTS FOCUSING ON CU CONTACT
Link	(PowerPoint 706 KB)
Authors	S. S. Hegedus, et al.
Description
Venue	CdTe R&D Team
Source	University of Delaware
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	ADVANCES IN CONTINUOUS IN-LINE PROCESSING OF CDTE PV DEVICES
Link	(PowerPoint 1.7 MB)
Authors	K. L. Barth, R. A. Enzenroth, W. S. Sampath
Description
Venue	CdTe R&D Team
Source	Colorado State University
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	PL STUDIES OF CDTE CRYSTALS ION-IMPLANTED WITH CL, CU, OR P
Link	(PowerPoint 285 KB)
Authors	L. Gorrell, S. Liu
Description
Venue	CdTe R&D Team
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	X-RAY FINE STRUCTURE OF CU IN SPUTTERED CDTE (OR WHERE DOES THE CU GO?)
Link	(PowerPoint 1.1 MB)
Authors	S. Liu, et al.
Description
Venue	CdTe R&D Team
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	SENSITIVITY OF THIN FILM CDTE DEVICE OPERATION TO PROCESSING CHEMISTRY
Link	(PowerPoint 1.5 MB)
Author	B. E. McCandless
Description
Venue	CdTe R&D Team
Source	University of Delaware
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	STEADY STATE PHOTOCAPACITANCE OF CDTE CELLS
Link	(PowerPoint 561 KB)
Author	R. A. Enzenroth
Description
Venue	CdTe R&D Team
Source	Colorado State University
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	STABILITY STUDIES WITH CSU AND UT CDTE CELLS
Link	(PowerPoint 4.4 MB)
Author	L. Olsen
Description
Venue	CdTe R&D Team
Source	Pacific Northwest National Lab (PNNL)
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	REAL-TIME, IN-SITU ELLIPSOMETRY OF CDTE FILM GROWTH AND SOLAR CELL ETCH-BACK
Link	(PowerPoint 5.2 MB)
Author	R. W. Collins
Description
Venue	CdTe National R&D Team meeting
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	05/09/2005
Title	PIEZO EFFECT IN CDS/CDTE SOLAR CELLS
Link	(PowerPoint 1.4 MB)
Authors	D. Shvydka, et al.
Description
Venue	CdTe R&D Team
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/05/2005

Post Date	03/17/2005
Title	ALTERNATIVE JUNCTION SUBTEAM
Link	(PowerPoint 851 KB)
Author	J. R. Sites
Description	comparing different junction partners and absorber band gaps
Venue	CIS National R&D Team Meeting March 2005 NREL
Source	Colorado State University
Document Type	Presentation (Powerpoint presentation)
Resource Date	03/08/2005

Post Date	02/09/2005
Title	NREL CDTE RESEARCH
Link	(PowerPoint 6.3 MB)
Authors	T. Gessert, et al.
Description
Venue	DOE Solar Review
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	10/28/2004

Post Date	02/09/2005
Title	HIGH THROUGHPUT PROCESSING OF STABLE CDTE/CDS SOLAR CELLS
Link	(PowerPoint 2.0 MB)
Authors	B. E. McCandless, et al.
Description
Venue	DOE Solar Review 2004
Source	University of Delaware
Document Type	Presentation (Powerpoint presentation)
Resource Date	10/26/2004

Post Date	02/10/2005
Title	TOWARD A TANDEM CELL WITH ALL II-VI SEMICONDUCTORS BY MAGNETRON SPUTTERING
Link	(PDF 1.2 MB) Download Acrobat Reader.
Authors	A. Compaan, et al.
Description	CdTe/HgCdTe
Venue	DOE Solar Review
Source	University of Toledo
Document Type	Presentation (Adobe Postscript file)
Resource Date	10/25/2004

Post Date	02/07/2005
Title	THIN FILMS AND THE SYSTEM DRIVEN APPROACH
Link	(PowerPoint 1.0 MB)
Author	K. Zweibel
Description	Cost analysis of thin films for semiconductor, encapusulation, layer thickness, and efficiency.
Venue	DOE and NREL Solar Review Meeting 2004
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	10/2004

Post Date	02/09/2005
Title	LARGE AREA THIN FILM DEVICES: NONUNIFORMITIES, INTERFACIAL LAYESR, REACG-THROUGH EFFECTS
Link	(PowerPoint 884 KB)
Author	V. G. Karpov
Description
Venue	DOE Solar Review
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	10/2004

Post Date	02/07/2005
Title	2ND GENERATION THIN FILMS
Link	(PowerPoint 8.9 MB)
Author	K. Zweibel
Description	Potential of CIS, CdTe, and a-Si thin films.
Venue	Rice University Solar Energy Workshop
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	09/2004

Post Date	04/22/2005
Title	ADHESION TESTS OF CANDIDATE BACKSHEET AND ENCAPSULANTS
Link	(PDF 425 KB) Download Acrobat Reader.
Authors	G. J. Jorgensen, J. A. del Cueto, et al.
Description	Pull tests of various candidate replacements for EVA
Venue	Thin film module reliability national team meeting
Source	National Renewable Energy Laboratory
Document Type	Presentation (Adobe Postscript file)
Resource Date	06/2004

Post Date	04/22/2005
Title	MOISTURE INGRESS PROTECTION BY COMBINED BACKSHEET AND ENCAPSULANT CONSTRUCTIONS
Link	(PDF 1.7 MB) Download Acrobat Reader.
Authors	G. J. Jorgensen, M. Kempe, C. Kennedy, K. Terwilliger
Description	WVTR, PET, EVA, BRP, TruSeal
Venue	Thin Film Module Reliability National Team Meeting
Source	National Renewable Energy Laboratory
Document Type	Presentation (Adobe Postscript file)
Resource Date	06/2004

Post Date	04/22/2005
Title	EFFECTS OF MOISTURE INGRESS ON PV MODULES
Link	(PDF 528 KB) Download Acrobat Reader.
Author	M. Kempe
Description	Measuring the rate water vapor moves through EVA from the edge and the back
Venue	Thin Film Module Reliability National Team Meeting
Source	National Renewable Energy Laboratory
Document Type	Presentation (Adobe Postscript file)
Resource Date	06/2004

Post Date	04/22/2005
Title	LEAKAGE CURRENTS AND HIGH-VOLTAGE THIN FILM MODULES
Link	(PDF 1.1 MB) Download Acrobat Reader.
Author	N. G. Dhere
Description	FSEC testing of outdoor thin film arrays
Venue	Thin Film Module Reliability Team Meeting
Source	FLorida Solar Energy Center
Document Type	Presentation (Adobe Postscript file)
Resource Date	06/2004

Post Date	04/22/2005
Title	PAST AND PREDICTED THIN FILM MODULE PRODUCTION IN THE US BY TECHNOLOGY
Link	(PowerPoint 45 KB)
Author	K. Zweibel
Description	Annual MWp/yr 2000-2011 by technology
Venue
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/22/2004

Post Date	02/11/2005
Title	PV MODULE RECYCLING IN THE US
Link	(PDF 600 KB) Download Acrobat Reader.
Authors	V. Fthenakis, K. Zweibel
Description	Recycling today and tomorrow
Venue	EIA Workshop
Source	N/A
Document Type	Presentation (Adobe Postscript file)
Resource Date	03/2004

Post Date	02/11/2005
Title	PV MODULE RECYCLING IN THE US
Link	(PowerPoint 3.8 MB)
Authors	V. Fthenakis, K. Zweibel
Description	Recycling today and tomorrow.
Venue	EU Workshop "Waste Challenge"
Sources	Brookhaven National Laboratory; National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	03/2004

Post Date	02/07/2005
Title	PV AS A MAJOR SOURCE OF GLOBAL ELECTRICITY
Link	(PowerPoint 13.2 MB)
Author	K. Zweibel
Description	Projected improvements needs to make PV a major source of electricity.
Venue	University of Toledo
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	02/24/2004

Post Date	02/17/2005
Title	A COMPARISON OF THIN FILMS AND X-SI IN THE US MARKET, HISTORICAL AND PROJECTED
Link	(MS Word 31 KB)
Author	K. Zweibel
Description	Thin films are gaining ground on x-Si and are projected to overtake it in the US about 2010-2011.
Venue	Thin Film Partnership and Paul Maycock's PV News February 2005
Source	PV News
Document Type	Presentation (Word document)
Resource Date	02/17/2004

Post Date	02/11/2005
Title	TRAPPING ALMOST ALL CD IN GLASS ENCAPSULATION IN THE EVENT OF A RESIDENTIAL FIRE: DETAILED EXPERIMENTAL ANALYSIS
Link	(PowerPoint 45.7 MB)
Author	V. Fthenakis
Description
Venue
Source	Brookhaven National Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	2004

Post Date	02/15/2005
Title	THE INTRINSIC STABILITY OF POLYCRYSTALLINE THIN FILM SOLAR CELLS
Link	(PowerPoint 3.0 MB)
Authors	D. Albin, T. Berniard, S. Demetsu, T. J. McMahon, R. Noufi
Description	Indoor, accelerated tests of thin film CIS and CdTe
Venue
Sources	Colorado State University; National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	2004

Post Date	02/09/2005
Title	SUMMARY OF EXPERIMENTS WITH TE THICKNESS VARIATION
Link	(PDF 67 KB) Download Acrobat Reader.
Authors	K. D. Dobson, B. E. McCandless
Description	summary of experiments we have performed to examine the effect of Te thickness on cell stability. At the end we comment on how these results are related to humidity effects during processing and stress.
Venue
Source	University of Delaware
Document Type	Presentation (Adobe Postscript file)
Resource Date	09/05/2003

Post Date	02/09/2005
Title	MAGNETRON SPUTTERING FOR LOW TEMPERATURE DEPOSITION OF CDTE PV
Link	(PowerPoint 1.0 MB)
Author	A. Compaan
Description
Venue	MRS Spring 2003
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	05/2003

Post Date	02/09/2005
Title	THE DYNAMICS OF CADMIUM TELLURIDE ETCHING
Link	(PDF 192 KB) Download Acrobat Reader.
Authors	K. D. Dobson, et al.
Description	CdTe etching was investigated using variable angle spectroscopic ellipsometry and glancing angle x-ray diffraction. Treatment with HNO₃:H₃PO₄ (NP) based etches was shown to form amorphous-Te surface films which spontaneously crystallize following etching. Br₂/methanol (BM) etching forms very thin amorphous-Te films. NP-etched surfaces are stable in ambient air...
Venue	CdTe Team Meeting
Source	University of Delaware
Document Type	Presentation (Adobe Postscript file)
Resource Date	2003

Post Date	02/09/2005
Title	WHEN, WHY AND WHERE ARE CDTE/CDS SOLAR CELLS STABLE?
Link	(MS Word 960 KB)
Authors	K. D. Dobson, I. Visoly-Fisher, et al.
Description	The role of Cu in CdTe/CdS solar cell instability remains the subject of much debate. The investigation of a range of 'Cu'-contacted CdTe/CdS cells, which had received various thermal stress treatments, is described. Cells that were stressed in air exhibit strong current-voltage (I-V) rollover and junction degradation. No such degradation was observed for 'Cu'-contacted cells that had been stressed in dry-N2 atmosphere. Cu is found to diffuse rapidly through the cell structure during back contact annealing and to accumulate in the CdS layer. With stress, significant levels of Cu dope the grain bulk, producing (with Cl) high resistance, photo-conducting CdS. This behavior is independent of stress atmosphere and is, therefore, unlikely to (initially) be a dominating mechanism for cell degradation. Our results suggest simple air oxidation of the back contact interface to be a likely origin of I-V rollover in CdTe/CdS cells.
Venue	CdTe Team Meeting
Source	Weizmann Institute
Document Type	Presentation (Word document)
Resource Date	2003

Post Date	02/07/2005
Title	PROGRESS IN US PV
Link	(PowerPoint 1.5 MB)
Author	T. Surek
Description	50 years of progress in PV.
Venue	Osaka IEEE conference
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	2003

Annual/Final Reports

Post Date	07/09/2008
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 4.2 MB) Download Acrobat Reader.
Authors	R. W. Birkmire, W. N. Shafarman, E. Eser, S. S. Hegedus, B. E. McCandless, K. D. Dobson, S. Bowden
Description	This report describes results achieved during phase V of a V-phase subcontract to develop and understand thin film solar cell technology associated to CuInSe2 and related alloys, a-Si and its alloys and CdTe. This includes application of a-Si to c-Si wafer-type cells as well. Modules based on all these thin films are promising candidates to meet DOE long-range efficiency, reliability and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for the development of viable commercial processes and to improve module performance. The generic research issues addressed are: 1) quantitative analysis of processing steps to provide information for efficient commercial scale equipment design and operation; 2) device characterization relating the device performance to materials properties and process conditions; 3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; 4) development of improved window/heterojunction layers and contacts to improve device performance and reliability; and 5) evaluation of cell stability with respect to illumination, temperature and ambient and with respect to device structure and module encapsulation.
Venue	Institute of Energy Conversion (U. Delaware), Subcontract No. ADJ-1-30630-12, annual report
Source	University of Delaware
Document Type	Annual Report (Adobe Postscript file)
Resource Date	04/01/2008

Post Date	01/14/2008
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 3.8 MB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando
Description	Our effort on device physics has focused on studies of the optical and morphological properties of CdS and CdTe films using spectroscopic ellipsometry. This has been carried out both in situ in real time during the sputter deposition processes and ex situ on films after sputter deposition is interrupted at different stages or after the CdCl2 processing is completed. Other characterization has included EXAFS and high resolution TEM and EDS. Using transparent back contacts we have begun to explore carrier collection through the bifacial response of cells with CdTe layers between 0.7 and 2.3 ?m. We have sought better understanding of the factors controlling growth rates by studying the dependence on gas pressure as well as rf power paying close attention to film morphology and strain. We have explored alternative shunt passivation treatments and have modeled the fundamental physics of ultrathin solar cells.
Venue	University of Toledo, subcontract ZXL-5-44205-01, Annual Report
Source	University of Toledo
Document Type	Annual Report (Adobe Postscript file)
Resource Date	10/2007

Post Date	10/25/2007
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 1.3 MB) Download Acrobat Reader.
Authors	C. Heske, M. Baer
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray absorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. In the last year, we could draw a complete picture of the chemical and electronic properties of the deeply buried chalcopyrite/back contact interface. For these experiments Cu(In,Ga)Se2 ("CIGSe") and Cu(In,Ga)(S,Se)2 ("CIGSSe")/back contact samples pre-pared by the group of W. Shafarman (Institute of Energy Conversion, University of Delaware) were used. We have found a pronounced chemical interaction between absorber and back contact, namely the formation of MoSe2 (and Mo(S,Se)2) and a "diffusion" of Ga into the Mo layer. In addition, we could derive a tentatively flat valence band alignment at this interface. In addition, we have investigated the CdS/CIGSe interface of samples provided by the National Renewable Energy Laboratory (M. Contreras, R. Noufi), which currently holds the world record for respective solar cell devices in terms of photovoltaic performance. Our results show that, in contrast to earlier measurements on samples from a different source, no pronounced S/Se intermixing at this interface can be observed.
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44205-12, annual report
Source	University of Nevada, Las Vegas
Document Type	Annual Report (Adobe Postscript file)
Resource Date	08/15/2007

Post Date	06/22/2007
Title	CHARACTERIZATION AND ANALYSIS OF CIGS AND CDTE SOLAR CELLS
Link	(PDF 1.3 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	The fundamental work on CIGS cells included an analysis of the expected behavior for submicron thin absorbers. A baseline scenario based on experimental results was compared with conditions where the absorber lifetime and its carrier concentration were reduced by an order of magnitude. Additional calculations compared front-side with back-side illumination, again in the context of experimental results, and calculated several consequences of weak-diode areas and partial shunting, both expected to be of increasing importance for thinner CIGS. Finally, a collaboration with NREL compared the differences between 19.5%-efficient CdZnS/CIGS cells and those made with the conventional CdS buffer. A major CdTe project in response to the excessive voltage deficit between CdTe and single-crystal cells has been the analysis of strategies to significantly enhance voltage. One strategy recommended for a major experimental effort is an n-i-p structure with an electron reflector before the back contact. Experimentally, CdTe lifetime and current-voltage curves were measured as a function of copper amount used in the back contact, and the expected impact of low lifetimes, including artificially large A-factors, was calculated. Also, experimentally, CdTe cells made with commercially compatible processing were utilized to determine how CdS thickness affects the cell performance parameters.
Venue	Colorado State University subcontract XXL-5-44205-03, Phase II Annual report
Source	Colorado State University
Document Type	Annual Report (Adobe Postscript file)
Resource Date	04/30/2007

Post Date	07/19/2006
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 6.7 MB) Download Acrobat Reader.
Authors	A. Compaan, V. G. Karpov, R. W. Collins, D. Giolando
Description	Our efforts on device physics have primarily involved modeling of CdS/CdTe based PV junctions, modeling and verification of device shunting instability, observation and studying the nature of spatial and temporal fluctuations of micro (AFM) currents through CdTe junctions, further studying of piezo-PV coupling, XAFS XES structural chemistry study of CdCl2 treated CdS films, spectral ellipsometry study of surface morphology in the course of structure growth, as well as etching, film structure and device parameters vs. magnetron deposition rate, and device parameters for CdTe thickness below 1 micron. During the first year of this award, we have: (1) Developed numerical and analytical (field reversal) models explaining all the major facts pertaining to CdTe/CdS device operations, (2) Developed a quantitative description of shunting instability in thin film PV through the mechanism of dielectric breakdown and verified it experimentally, (3) Experimentally observed gigantic spatial and temporal fluctuations of micro AFM current and proposed their interpretation based on defect motility in CdTe films, (4) Developed a new (bending) technique of piezo-PV characterization and observed increase in the open circuit voltage of devices on flexible substrates subject to certain bending; also, observed the piezo-PV coupling in CIGS based materials, (5) Through XAFS and XES techniques, established the nature of Cu binding in CdS (primarily with S atoms), and effect of substantial compression of certain atomic bonds upon Cu diffusion in CdS, atomic bonds upon Cu diffusion in CdS, (6) Established that increase in the magnetron deposition rate by the factor of 2.5 does not hamper the cell performance when the postdeposition treatment is properly optimized, (7) Experimentally established the relationship between the CdTe film thickness and device efficiency in the range of 2.5 - 0.45 micron, in particular demonstrated high efficiency devices of thickness below 1 micron.
Venue	Subcontract RXL-5-44205-01, University of Toledo, Annual report
Source	University of Toledo
Document Type	Annual Report (Adobe Postscript file)
Resource Date	07/19/2006

Post Date	09/07/2006
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN-FILM SOLAR CELL INTERFACES
Link	(PDF 415 KB) Download Acrobat Reader.
Authors	M. Baer, C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spec-troscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. First funds for this project became available in the middle of July 2005. Since then, the workforce of the group was expanded to the size required for this project. The experimental instrumentation at UNLV ? a four-chamber ultra-high vacuum surface analysis and modification system ? was commissioned and put to routine use after its re-location from the University of W�rzburg, Germany. In addition, a setup for inverse photoemission was integrated and a new electron analyzer was installed at UNLV to al-low state-of-the-art data acquisition and spectral quality. Contacts within the Thin Film PV Partnership Program were established to secure a supply of adequate samples. These samples were analyzed both in the lab at UNLV as well as in our beamtimes at the Advanced Light Source, Lawrence Berkeley National Laboratory (Nov. 2 ? 13, 2005 and May 16 ? 23, 2006). In our first beamtime within this project at the Advanced Light Source we could gather first results with Cu(In,Ga)Se2 samples prepared by NREL. Combined with addi-tional photoemission measurements at UNLV, a detailed picture of the chemical compo-sition at several interfaces and surface of the device structure could be drawn. Also dur-ing the first beamtime at the Advanced Light Source, we conducted first XES measure-ments of CdTe/CdS samples prepared by the group of A. Compaan (University of Toledo). Recently, these synchrotron results could be complemented by initial photo-emission measurements at UNLV of CdTe/CdS thin film stacks provided by X. Wu (NREL).
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44205-12, annual report
Source	University of Nevada, Las Vegas
Document Type	Annual Report (Adobe Postscript file)
Resource Date	07/15/2006

Post Date	05/18/2006
Title	CHARACTERIZATION AND ANALYSIS OF CIGS AND CDTE SOLAR CELLS
Link	(PDF 2.5 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	A number of studies relating to the fundamental operation of CIGS and CdTe solar cells were performed during Phase I. In addition, we have worked closely with industrial and NREL partners to evaluate specific cells, expanded our LBIC (light-beam-induced-current) capabilities, and analyzed the effective efficiency to be expected from several commercial thin-film modules. The fundamental work on CIGS cells included a detailed analysis of grain-boundary effects using two-dimensional modeling. It showed that the relatively benign effects observed are best explained by a decrease in the valence band edge in the vicinity of the grain boundary. A second project, which followed earlier work relating spatial grading of CIGS to performance, showed the increasing importance of an electron reflector at the back of the CIGS absorber as it is made progressively thinner. A third project generalized earlier work on the window/absorber conduction band offset to show that there is a general rule governing when a "spike" leads to a distortion of the current-voltage curve. The CdTe studies included a reasonably convincing explanation of the 1.456-eV photoluminescence peak as a copper-oxygen donor complex about 150 meV below the conduction-band minimum. A second project demonstrated how different combinations of absorber lifetime and back-contact barrier lead to different common features seen with CdTe cells. A third project extended stability and uniformity studies to focus on performance differences among cells with graphite, Ag, and Ni back contacts. Finally, a study of current response following voltage steps showed that reversible transients were essentially always present, but their magnitude varied considerably with sample preparation.
Venue	Subcontract ADJ-1-30630-06
Source	Colorado State University
Document Type	Annual Report (Adobe Postscript file)
Resource Date	05/2006

Post Date	06/02/2006
Title	DOE SOLAR ENERGY TECHNOLOGY PROGRAM FY2005 ANNUAL REPORT
Link	(PDF 5.2 MB) Download Acrobat Reader.
Author	N/A
Description	The majority of the Program?s budget is allocated to PV research and development (R&D). All PV devices convert sunlight directly into electricity. However, there is a variety of materials and processes for creating PV devices, each with its own benefits and drawbacks. The major trade-off is between cost and sunlight-to-electricity conversion efficiency?higher efficiency typically translates into higher cost. Program participants consistently achieve world-record efficiencies for different types of PV, but each effort has the same ultimate goal: optimizing cost and efficiency to produce the least expensive end-use electricity.
Venue	DOE/GO-102006-2314May 2006
Source	National Renewable Energy Laboratory
Document Type	Annual Report (Adobe Postscript file)
Resource Date	05/2006

Post Date	04/10/2006
Title	FULFILLING THE PROMISE OF THIN FILM PV
Link	(PDF 5.5 MB) Download Acrobat Reader.
Author	K. Zweibel
Description	The Thin Film PV Partnership spearheads R&D on emerging thin film PV technologies. Led by the National Center for Photovoltaics and NREL, the Partnership leverages the combined efforts of the thin film PV industry, universities, and government research institutes.
Venue	Brochure excerpt
Source	National Renewable Energy Laboratory
Document Type	Annual Report (Adobe Postscript file)
Resource Date	04/2006

Post Date	02/07/2006
Title	DOE FY2007 CONGRESSIONAL BUDGET REQUEST FOR ENERGY SUPPLY AND CONSERVATION
Link	(PDF 3.4 MB) Download Acrobat Reader.
Author	N/A
Description	Appropriation Account Summary..........................................................................................................3 Appropriation Language ........................................................................................................................7 Energy Efficiency and Renewable Energy ..........................................................................................11 Electricity Delivery & Energy Reliability .........................................................................................511 Nuclear Energy .................................................................................................................................571 Environment, Safety and Health ........................................................................................................705 Legacy Management.........................................................................................................................733
Venue	The Department of Energy?s FY 2007 Congressional Budget justification is available on the Office of Chief Financial Officer/CFO homepage at http://www.mbe.doe.gov/budget
Source	Department of Energy
Document Type	Annual Report (Adobe Postscript file)
Resource Date	02/2006

Post Date	02/01/2006
Title	THIN FILM PV PARTNERSHIP
Link	(MS Word 393 KB)
Author	K. Zweibel
Description	Objectives Support the near-term transition to first-time manufacturing and commercial introduction of reliable thin-film a-Si, CIS, CdTe, and film silicon modules. Build a technology base upon which these advanced PV technologies can successfully improve manufacturing and continue to progress in terms of performance, reliability, and reduced cost for products meant to compete in the PV marketplace. Sustain innovation to support progress toward ambitious long-term PV cost and performance goals (e.g., 15% modules at under $50/m2 and capable of lasting 30 years) appropriate for cost-competitive PV electricity. Accomplishments Four JOULE milestones were met. Two Technology Partners broke ground on major manufacturing expansions (First Solar 50 MWp, and Uni-Solar 25 MWp). Production of thin films in the United States grew from 12 MWp in 2003 to an estimated >40 MWp in 2005. Future Directions � Continue to address key issues supporting the transition to successful first-time manufacturing or major production expansion in each thin film. � Significantly reduce CIS and CdTe layer thicknesses in cells and support transfer of this to manufacturing. � Direct CdTe research toward higher voltage. � Investigate nano-crystalline bottom cells for thin-film silicon multijunctions.___________________________________________
Venue	DOE NREL Annual Report
Source	National Renewable Energy Laboratory
Document Type	Annual Report (Word document)
Resource Date	02/2006

Post Date	01/25/2006
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(MS Word 16.5 MB)
Author	R. W. Birkmire
Description	CdTe, CIS, CIGS, a-Si, thin Si
Venue	Annual Report to National Renewable Energy Laboratory under Subcontract No. ADJ-1-30630-129/05/04 to 9/04/05
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	01/2006

Post Date	02/01/2006
Title	MANUFACTURING PROCESS OPTIMIZATION TO IMPROVE STABILITY, YIELD AND EFFICIENCY OF CDS/CDTE PV DEVICES
Link	(MS Word 238 KB)
Author	W. S. Sampath
Description	Under Phase I of the Thin Film Partnership Program, we have made significant progress. During this year, the reproducibility of device efficiency and stability has been demonstrated during long duration operation of the system with a single charge loading for the CdS, CdTe and CdCl2 process. Currently efforts are underway to advance the back contact processing to the same level as outlined in the SOW. In order to accomplish this, a significant upgrade to increase the processing space in our pilot scale system has been designed, fabricated and is currently being installed. A series of detailed studies on the effect of oxygen during the CdCl2 treatment has been performed. Oxygen has been shown to improve the effectiveness of the CdCl2 treatment. Mathematical modeling of a package design has yielded results that show that moisture can be kept from our device for 22 years at 65C temperature with saturated humidity. Hardware to perform steady state photocapacitance (PHCAP) has been designed, built and tested in our laboratory. The effect of processing on the deep states in CdTe devices can be seen quantitatively. Optimum process conditions lead to lower photocapacitance signals. The feasibility of cooling the substrate in vacuum for optimum processing of the back contact has been demonstrated. A large number of experiments have been performed on laser scribing of CdS/CdTe films. Mechanical scribing has yielded the lowest contact resistance between the scribed region and the metallization, to date. Researchers at National Starch and Chemicals (NSC) have performed many experiments to screen print carbon, nickel and silver films in patterns. The adhesion of these films was tested according to ASTM 3359B and achieved a 5B or "excellent" rating.
Venue	September 2005 - January 2006 Thin Film Partnership Program Subcontract XXL-5-44205-02
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	01/2006

Post Date	12/27/2005
Title	DEEP ELECTRONIC STATES IN CDTE SOLAR CELLS DETECTED WITH ADMITTANCE TECHNIQUES
Link	(MS Word 81 KB)
Author	F. H. Seymour
Description	Deep electronic states (DES) in the absorber layer of thin film polycrystalline CdTe solar cells are believed to be limiting their energy conversion efficiency. Admittance spectroscopy and capacitance transient techniques were applied with a custom-built temperature stage to detect and characterize these DES. CdTe solar cells obtained from two sources that had post-deposition back contact treatments with and without Cu and CdCl2 were studied. DES were detected with activation energies ranging from 0.13 eV to 0.83 eV. One hole trap signature with Ea~0.15 eV was detected in all four cell categories in different concentrations and was attributed to a combination of and the chlorine A-center complex defects. A second hole trap signature with Ea~0.35 eV and detected only in Cu treated cells was attributed to the copper substitutional defect. Analysis of current density voltage temperature data indicates that the defect might be responsible for the improved JSC observed in the CdCl2 treated cells.
Venue	DOE Solar Review 2005
Source	Colorado School of Mines, Golden, CO
Document Type	Annual Report (Word document)
Resource Date	12/2005

Post Date	12/27/2005
Title	THIN CDTE SOLAR CELLS WITH HIGH THROUGHPUT PROCESSING
Link	(MS Word 68 KB)
Author	B. E. McCandless
Description	Progress towards reducing CdTe film thickness and increasing performance and processing throughput for vapor transport (VT) deposited CdTe/CdS solar cells is highlighted. VT devices with 5-7 mm thick CdTe deposited on moving substrates at 9 mm/min using a 20 min vapor CdCl2 treatment at 415�C achieved Voc up to 840 mV and h > 13%. Devices with h = 11% were obtained with 2 min CdCl2 treatments at 465�C. For cells with CdTe thickness ~1.5 mm, h >10% was obtained. Voc and FF decreased for cells with CdTe deposited at >80 mm/min and for cells with mm CdTe. Devices using transparent ZnTe contacts have similar performance to those with opaque contacts and are being used to separate back contact and primary junction effects.
Venue	2005 DOE Solar Review
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	12/2005

Post Date	11/11/2005
Title	POLYCRYSTALLINE THIN FILM DEVICE DEGRADATION STUDIES
Link	(PDF 85 KB) Download Acrobat Reader.
Author	D. Albin
Description	Oxygen during vapor CdCl2 (VCC) treatments significantly reduced resistive shunts observed in CdS/CdTe polycrystalline devices using thinner CdS layers during 100 �C, open-circuit, 1-sun accelerated stress testing. Cu oxidation resulting from the reduction of various trace oxides present in as-grown and VCC treated films is the proposed mechanism by which Cu diffusion, and subsequent shunts are controlled. Graphite paste layers between metallization and CdTe behave like diffusion barriers and similarly benefit device stability. Ni-based contacts form a protective Ni2Te3 intermetallic layer that reduces metal diffusion but degrades performance through increased series resistance.
Venue	DOE Solar Review Meeting 2005 paper
Source	National Renewable Energy Laboratory
Document Type	Annual Report (Adobe Postscript file)
Resource Date	11/10/2005

Post Date	11/17/2005
Title	UNDERSTANDING THE PHYSICS OF CDS-BASED PV: BAND DIAGRAM, INTERFACES, AND NONUNIFORMITIES
Link	(MS Word 120 KB)
Author	V. G. Karpov
Description	Our recent discovery of piezo-PV coupling together with other indicative evidence suggest an adequate band diagram for CdS based thin-film PV. The proposed model is solved analytically leading to numerous predictions that include lack of the carrier collection from CdS, buffer layer effects, and others. This understanding points at new pathways for device improvement.
Venue	DOE Solar Review 2005
Source	University of Toledo
Document Type	Annual Report (Word document)
Resource Date	11/2005

Post Date	11/11/2005
Title	DEEP ELECTRONIC STATES IN CDTE SOLAR CELLS DETECTED WITH ADMITTANCE TECHNIQUES
Link	(MS Word 74 KB)
Author	F. H. Seymour
Description	Deep electronic states (DES) in the absorber layer of thin film polycrystalline CdTe solar cells are believed to be limiting their energy conversion efficiency. Admittance spectroscopy and capacitance transient techniques were applied with a custom-built temperature stage to detect and characterize these DES. CdTe solar cells obtained from two sources that had post-deposition back contact treatments with and without Cu and CdCl2 were studied. DES were detected with activation energies ranging from 0.13 eV to 0.83 eV. One hole trap signature with Ea~0.15 eV was detected in all four cell categories in different concentrations and was attributed to a combination of and the chlorine A-center complex defects. A second hole trap signature with Ea~0.35 eV and detected only in Cu treated cells was attributed to the copper substitutional defect. Analysis of current density voltage temperature data indicates that the defect might be responsible for the improved JSC observed in the CdCl2 treated cells.
Venue	DOE Solar Review 2005
Source	Colorado School of Mines, Golden, CO
Document Type	Annual Report (Word document)
Resource Date	11/2005

Post Date	04/05/2005
Title	ADVANCED PROCESSING OF CDTE- AND CUIN1-XGAXSE2- BASED SOLAR CELLS
Link	(PDF 584 KB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description	CdTe CSS and CIGS sputtering
Venue	NDJ-2-30630-18 PHASE II
Source	University of South Florida, Tampa
Document Type	Annual Report (Adobe Postscript file)
Resource Date	03/2005

Post Date	02/17/2005
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS
Link	(MS Word 7.7 MB)
Authors	R. W. Birkmire, S. S. Hegedus, B. E. McCandless, W. N. Shafarman, et al.
Description
Venue	ADJ-1-30630-12 9/05/03 to 9/04/04
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	10/2004

Post Date	01/18/2004
Title	STABILITY, YIELD AND EFFICIENCY OF CDS/CDTE DEVICES
Link	(MS Word 31 KB)
Author	W. S. Sampath
Description	One-page summary of 2004 accomplishments
Venue	2004 Summary Annual Report for NREL Program; Subcontract No. ADJ-1-30630-07 to Colorado State University
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	10/2004

Post Date	02/09/2005
Title	RESEARCH LEADING TO HIGH THROUGHPUT MANUFACTURING OF THIN-FILM CDTE PV MODULES
Link	(MS Word 7.8 MB)
Author	R. C. Powell
Description	First Solar is actively commercializing CdTe-based thin film photovoltaics. During the past year major additions of production capability have been completed as well as process improvements to achieve higher throughput and efficiency and greater durability. This report presents the results of phase II of the subcontract entitled "Research Leading to High Throughput Manufacturing of Thin-Film CdTe PV Modules". The subcontract supports several important aspects needed to for high volume manufacturing of high efficiency modules including exploration of large area advanced front contact window layers, improvements of the semiconductor deposition system, advancement in understanding of post deposition processing steps and accelerated life testing methods, and progress to the environmental, health and safety programs.
Venue	Annual subcontract report mailto:Doug Rose
Source	First Solar, Toledo, OH
Document Type	Annual Report (Word document)
Resource Date	09/27/2004

Post Date	02/08/2005
Title	STUDIES OF BASIC ELECTRONIC PROPERTIES OF CDTE-BASED SOLAR CELLS & THEIR EVOLUTION DURING PROCESSING & STRESS
Link	(PDF 3.0 MB) Download Acrobat Reader.
Authors	V. Kaydanov, T. Ohno
Description	We emphasize the relation between composition, structural and electronic material properties and various processing procedures as well as the microscopic mechanisms responsible for the cell performance and its degradation.
Venue	ADJ-2-30630-05
Source	Colorado School of Mines, Golden, CO
Document Type	Annual Report (Adobe Postscript file)
Resource Date	11/2003

Post Date	01/21/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(MS Word 26 KB)
Author	J. R. Sites
Description	Work was performed at Colorado State University on basic measurements of CIGS and CdTe solar cells fabricated at a number of collaborating laboratories. The goal is to quantitatively deduce the loss mechanisms in a number of these cells, and to make appropriate comparisons that illuminate where progress is being made.
Venue	Summary Report for 2003, Subcontract ADJ-1-30630-06
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	10/2003

Post Date	02/02/2005
Title	2003 DOE PV PEER REVIEW
Link	(PDF 716 KB) Download Acrobat Reader.
Author	N/A
Description	Review of DOE PV activities in 2003
Venue	US DOE EERE
Source	US DOE
Document Type	Annual Report (Adobe Postscript file)
Resource Date	09/30/2003

Post Date	02/09/2005
Title	RESEARCH LEADING TO HIGH THROUGHPUT MANUFACTURING OF THIN-FILM CDTE PV MODULES PHASE I
Link	(MS Word 5.7 MB)
Author	R. C. Powell
Description	The subcontract supports several important aspects needed to begin high volume manufacturing including further development of the semiconductor deposition reactor, advancement of accelerated life testing methods and understanding, and improvements to the environmental, health and safety programs.
Venue	NREL report RDJ-2-30630-20
Source	First Solar, Toledo, OH
Document Type	Annual Report (Word document)
Resource Date	09/27/2003

Post Date	02/09/2005
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(MS Word 4.6 MB)
Authors	R. W. Birkmire, S. S. Hegedus, B. E. McCandless, W. N. Shafarman, et al.
Description
Venue	Annual report ADJ-1-30630-12
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	09/04/2003

Post Date	03/03/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(MS Word 2.9 MB)
Author	J. R. Sites
Description
Venue	ADJ-1-30630-06
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	09/2003

Post Date	03/04/2005
Title	PROCESSING MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(MS Word 4.5 MB)
Author	R. W. Birkmire
Description
Venue	ADJ-1-30630-12 9/05/02 to 9/04/03
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	09/2003

Post Date	02/10/2005
Title	THE FABRICATION AND PHYSICS OF HIGH-E�CIENCY CDTE THIN-FILM SOLAR CELLS
Link	(PDF 3.9 MB) Download Acrobat Reader.
Author	A. Compaan
Description	Our efforts on cell fabrication have primarily involved the use of magnetron sputtering for deposition. In addition, we have developed and used novel electrochemical treatments at the stage of finishing the devices deposited by other techniques: vapor transfer deposition (VTD) and close space sublimation (CSS), both made at First Solar, LLC.
Venue	NDJ-1-30630-02 September 1, 2002 to August 31, 2003
Source	University of Toledo
Document Type	Annual Report (Adobe Postscript file)
Resource Date	09/2003

Post Date	03/03/2005
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN-FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(MS Word 37 KB)
Author	R. W. Birkmire
Description
Venue	PV Program Contract Summary Report Thin-film PV Partnership Program
Source	University of Delaware
Document Type	Annual Report (Word document)
Resource Date	09/2003

Post Date	02/10/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(MS Word 2.9 MB)
Author	J. R. Sites
Description	The goal has been to quantitatively deduce the loss mechanisms in a number of these cells, and to make appropriate comparisons that illuminate where progress is being made.
Venue	Phase II September 2002 - August 2003 ADJ-1-30630-06
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	09/2003

Post Date	02/08/2005
Title	ADVANCED PROCESSING OF CDTE- AND CUIN_1-XGA_XSE₂
Link	(PDF 1.9 MB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description	This project addresses two thin film technologies CdTe and CIGS. The CdTe component of the project has three task areas. These are: development of simplified processing for the fabrication of CdTe solar cells correlation of the long term stability with process/device characteristics.
Venue	Phase I Final Report to NREL NDJ-2-30630-18
Source	University of South Florida, Tampa
Document Type	Annual Report (Adobe Postscript file)
Resource Date	2003

Post Date	02/15/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(MS Word 1.2 MB)
Author	J. R. Sites
Description	Work has been performed at Colorado State University on basic measurements of CdTe and CI(G)S solar cells fabricated at a number of collaborating laboratories. The goal has been to quantitatively deduce the loss mechanisms in a number of these cells, and to make appropriate comparisons that illuminate where progress is being made. Special emphasis was given to the differences in CdTe cells, both as-deposited and after elevated-temperature stress, that result from variations in the amount of back-contact copper. The second area of study has been further development of small-spot measurement of micro-nonuniforities, including those that develop during temperature stress. The facility focuses a laser beam onto a solar cell with 1-mm beam size, 1-mm resolution and repeatability, and one-sun intensity. The third task has been the determination of defect-state densities in CIGS cells by low-temperature capacitance measurements. Emphasis has been given to the comparisons between CIGS absorbers fabricated by different techniques and among different strategies for the buffer between absorber and transparent contact. The final task area has been numerical simulations of CdTe and CI(G)S cells. Replication of experimental data has been successful in both cases. The CdTe CIGS studies have illuminated the effects of thickness variations in the CdS and CdTe layers, while more recent CIGS studies have shown the impact of the CdS/CIGS conduction band offset on light/dark superposition.
Venue	Subcontract ADJ-1-30630-06 Phase I September 2001 - August 2002
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	09/2002

Post Date	02/08/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(MS Word 1.2 MB)
Author	J. R. Sites
Description	Work has been performed at Colorado State University on basic measurements of CdTe and CI(G)S solar cells fabricated at a number of collaborating laboratories. The goal has been to quantitatively deduce the loss mechanisms in a number of these cells, and to make appropriate comparisons that illuminate where progress is being made. Special emphasis was given to the differences in CdTe cells, both as-deposited and after elevated-temperature stress, that result from variations in the amount of back-contact copper.
Venue	NREL Phase I September 2001 - August 2002 Subcontract ADJ-1-30630-06
Source	Colorado State University
Document Type	Annual Report (Word document)
Resource Date	09/2002

Post Date	02/10/2005
Title	THE FABRICATION AND PHYSICS OF HIGH-EFFICIENCY CDTE THIN-FILM SOLAR CELLS
Link	(PDF 3.1 MB) Download Acrobat Reader.
Author	A. Compaan
Description
Venue	NDJ-1-30630-02 September 1, 2001 to August 31, 2002
Source	University of Toledo
Document Type	Annual Report (Adobe Postscript file)
Resource Date	09/2002

Post Date	03/03/2005
Title	ADVANCED PROCESSING OF CDTE- AND CUIN1-XGAXSE2- BASED SOLAR CELLS
Link	(PDF 1.9 MB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description
Venue	NDJ-2-30630-18
Source	University of South Florida, Tampa
Document Type	Annual Report (Adobe Postscript file)
Resource Date	2002

Post Date	05/11/2009
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 3.6 MB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando
Description	The three overall emphases of this subcontract were the following: 1) improving our understanding of key aspects of CdS/CdTe solar cell device physics, 2) improving our understanding of magnetron sputtering and increasing the sputter deposition rate while maintaining high device quality, and 3) reducing the thickness of CdTe layers in the CdS/CdTe cell below 0.5 ?m while maintaining voltage and fill factor.
Venue	University of Toledo, subcontract ZXL-5-44205-01, Final Report
Source	University of Toledo
Document Type	Final Report (Adobe Postscript file)
Resource Date	04/2009

Post Date	04/27/2009
Title	PROCESSING MATERIALS DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 1.6 MB) Download Acrobat Reader.
Authors	R. W. Birkmire, W. N. Shafarman, E. Eser, S. S. Hegedus, B. E. McCandless, K. D. Dobson, S. Bowden
Description	This report describes results achieved under this subcontract to develop and understand thin-film solar cell technology associated to CuInSe2 and related alloys, a-Si and its alloys, and CdTe. This includes application of a-Si to c-Si wafer-type cells, as well. Modules based on all these thin films are promising candidates to meet DOE long-range efficiency, reliability, and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for developing viable commercial processes and to improve module performance. The generic research issues addressed are: 1) quantitative analysis of processing steps to provide information for efficient commercial-scale equipment design and operation; 2) device characterization relating the device performance to materials properties and process conditions; 3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; 4) development of improved window/heterojunction layers and contacts to improve device performance and reliability; and 5) evaluation of cell stability with respect to illumination, temperature, and ambient and with respect to device structure and module encapsulation.
Venue	Institute of Energy Conversion (IEC), University of Delaware, subcontract ADJ-1-30630-12, Final Report
Source	University of Delaware
Document Type	Final Report (Adobe Postscript file)
Resource Date	04/2009

Post Date	05/11/2009
Title	CHARACTERIZATION AND ANALYSIS OF CIGS AND CDTE SOLAR CELLS
Link	(PDF 2.5 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	The project goals have been to (1) reliably and quantitatively separate individual performance loss mechanisms, (2) expand the tools available for such measurement and analysis, (3) refine the physical explanations for performance losses, and (4) suggest fabrication approaches or modifications that can reduce these losses. A number of studies relating to the fundamental operation of CIGS and CdTe solar cells were performed during the subcontract period. In addition, we have expanded our light-beam-induced-current (LBIC) capabilities and the formalism needed to evaluate spatial nonuniformities, and we have analyzed the effective efficiency to be expected from commercial thin-film modules
Venue	Colorado State University, subcontract XXL-5-44205-03, Final Report
Source	Colorado State University
Document Type	Final Report (Adobe Postscript file)
Resource Date	01/2009

Post Date	05/30/2006
Title	ADVANCED PROCESSING OF CDTE- AND CUIN1-XGAXSE2 CELLS
Link	(PDF 1.0 MB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description	This is the final report for the 3-year project with subcontract # NDJ-2-30630-18. The CdTe section of the report is organized in 2 major sections: (a) a summary of the activities and major results obtained during the first two 2 years (covered in Annual Reports I & II), and (b) activities for year 3. Additional details will be provided within the subsequent sections.
Venue	NDJ-2-30630-18
Source	University of South Florida, Tampa
Document Type	Final Report (Adobe Postscript file)
Resource Date	05/2006

Post Date	05/11/2005
Title	DEVICE PHYSICS OF THIN-FILMPOLYCRYSTALLINE CELLS AND MODULES SUMMARY REPORT FOR 2004, SUBCONTRACT ADJ-1-30630-06
Link	(MS Word 27 KB)
Author	J. R. Sites
Description	Task 1: Whole-cell analysis. The J-V distortions in CIGS cells due to an excessive spike in the conduction-band offset have been broadly documented and explained. The effects of a copper deficiency in the CdTe back contact have been similarly documented and explained. The process for systematic quantification of individual loss mechanisms in both types of cells has been refined and made more routine. Task 2: Highly focused light spot. Light-beam-induced-current (LBIC) measurements have shown that changes is CdTe cell response essentially always occur in localized regions. Additional refinements in cell-mounting, measurement, and display techniques have also made LBIC measurements more routine. Task 3: Defect-states. Low-temperature capacitance measurements with CIGS cells were used to compare absorbers fabricated by evaporation and by selenization, and to compare CdS and Cd-partial-electolyte buffer layers. CdTe photoluminescence was used to identify a key defect state as a copper/oxygen donor complex approximately 150 meV below the conduction band. Task 4. Numerical simulation. One project documented the limitation to cell voltage due to the CdS/CIGS conduction-band offset. A second showed that grading profiles in standard-thickness CIGS absorbers lead at best to only a modest increase in cell efficiency. A third project showed that a broad range of features seen in CdTe quantum-efficiency measurements can be explained with a simple three-layer model.
Venue	ADJ-1-30630-06
Source	Colorado State University
Document Type	Final Report (Word document)
Resource Date	05/2005

Post Date	05/11/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(PDF 3.0 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	The first area of study has been whole-cell analysis. Individual projects have included development of more effective separation of losses, the role of copper incorporation and migration with CdTe cells, the current-voltage consequences of the conduction-band offset in CdS/CIGS cells, alternative buffers for CIGS cells, and the development of the CurVA software for analysis of current-voltage curves. The second area of study has been the use of a highly focused light spot (LBIC) to investigate spatial variations in polycrystalline solar cells. The local effects of elevated- temperature stress on CdTe cells has received the most attention, but we have also demonstrated that LBIC can be combined with other non-uniformity studies on the same cell and that it is possible to partially construct the J-V curve at individual local positions. The third task has been the study of defect-states. With CIGS cells, we used lowtemperature capacitance measurements to compare absorbers fabricated by evaporation with those made by selenization and to compare CdS buffer layers with the Cd-partialelectrolyte. For CdTe, photoluminescence from single crystals with controlled introduction of copper and oxygen has been compared with that from solar-cell material. The final task area has been numerical simulation. We have defined and advocated a set of baseline parameters for CIGS and CdTe cells. Specific projects have included explanations of apparent quantum- and collection-efficiency effects, the impact of conduction-band offset on current-voltage curves, the effects of absorber grading in CIGS cells, and the 2-D analysis of grain-boundary effects.
Venue	ADJ-1-30630-06 September 2001 - October 2004
Source	Colorado State University
Document Type	Final Report (Adobe Postscript file)
Resource Date	05/2005

Post Date	01/03/2006
Title	ENERGY PAY-BACK AND LIFE CYCLE CO2 EMISSIONS OF THE BOS IN AN OPTIMIZED 3.5 MW PV INSTALLATION
Link	tepbos2005
Author	J. Mason
Description	This study is a life-cycle analysis of the balance of system (BOS) components of the 3.5 MWp multi-crystalline PV installation at Tucson Electric Power's (TEP) Springerville, AZ field PV plant. TEP instituted an innovative PV installation program guided by design optimization and cost minimization. The advanced design of the PV structure incorporated the weight of the PV modules as support, thereby eliminating the need for concrete foundations. The estimate of the life-cycle energy requirements embodied in the BOS is 543 MJ/m2, a 71% reduction from those of an older central plant; the corresponding life-cycle greenhouse gas emissions are 29 kg CO2-eq. /m2. From field measurements, the energy payback time (EPT) of the BOS is 0.21 years for the actual location of this plant, and 0.37 years for average US insolation/temperature conditions. This is a great improvement from the EPT of 2 years estimated for an older central plant. The total cost of the balance of system components was $940 US per kWp of installed PV, another milestone in improvement. These results were verified with data from different databases and further tested with sensitivity- and data-uncertainty analyses. Key Words: PV plant; balance of system; life cycle assessment, energy payback, GHG emissions
Venue	website
Source	Tucson Electric
Document Type	Final Report (Hypertext link)
Resource Date	2005

Post Date	04/21/2005
Title	PVACCEPT
Link	PVACCEPT
Author	N/A
Description	PVACCEPT is a German-Italian research project, which was funded by the European Commission within the programme "Innovation and Small and Medium Sized Enterprises". The project aimed at designing and developing marketable solar modules for electricity generation, which are designed in a way to enable their sensitive and inconspicuous integration into old buildings, historical sites, and protected landscapes. The project has officially started on 1st July 2001, and is concluded since 31st December 2004.
Venue
Sources	University of Arts, Berlin; University of Siena
Document Type	Final Report (Hypertext link)
Resource Date	12/2004

Post Date	02/08/2005
Title	STABILITY, YIELD AND EFFICIENCY OF CDS/CDTE DEVICES
Link	(PDF 632 KB) Download Acrobat Reader.
Authors	K. L. Barth, R. A. Enzenroth, W. S. Sampath
Description	Major results have been shown in the areas of device characterization, experimental infrastructure improvements and processing larger area substrates.
Venue	NREL ADJ-1-30630-07
Source	Colorado State University
Document Type	Final Report (Adobe Postscript file)
Resource Date	10/2004

Post Date	02/04/2005
Title	STUDY OF POTENTIAL COST REDUCTIONS RESULTING FROM SUPER-LARGE-SCALE MANUFACTURING OF PV MODULES
Link	(PDF 768 KB) Download Acrobat Reader.
Authors	R. Arya, M. Keshner, K. Zweibel
Description	Technology investments by the U.S. government Dept. of Energy, National Renewable Energy Lab (NREL) and others over the past 30 years have positioned the Solar Energy industry to undergo an inflection. The technology is now very close to good enough. The key issue is cost.
Venue	NREL final report NREL/SR-520-36846 Subcontract No. ADJ-3-33631-01
Sources	Hewlett Packard; National Renewable Energy Laboratory
Document Type	Final Report (Adobe Postscript file)
Resource Date	10/2004

Post Date	02/08/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE CELLS AND MODULES
Link	(PDF 3.0 MB) Download Acrobat Reader.
Author	J. R. Sites
Description	Work has been performed at Colorado State University on basic measurements of CIGS and CdTe solar cells fabricated at a number of collaborating laboratories. The goal has been to explain several features seen in these measurements and quantitatively assess their impact on device performance.
Venue	Subcontract ADJ-1-30630-06 Final Report to NREL
Sources	Colorado State University; National Renewable Energy Laboratory
Document Type	Final Report (Adobe Postscript file)
Resource Date	10/2004

Post Date	03/11/2005
Title	LEARNING FROM THE SUN
Link	(PDF 3.3 MB) Download Acrobat Reader.
Authors	E. A. Alsema, G. J. Schaeffer, et al.
Description	Analysis of the use of experience curves for energy policy purposes: The case of photovoltaic power. Final report of the Photex project
Venue	ECN-C--04-035
Source	Photex
Document Type	Final Report (Adobe Postscript file)
Resource Date	08/2004

Post Date	02/11/2005
Title	WORKSHOP ON LIFE CYCLE ANALYSIS AND RECYCLING OF SOLAR MODULES - THE "WASTE" CHALLENGE
Link	(PDF 12.5 MB) Download Acrobat Reader.
Author	A. Jager-Waldau
Description	First, to rise the awareness of the Photovoltaic Community about the European Directives 2002/96/EC on waste electrical and electronic equipment (WEEE) and 2002/95/EC on the restriction of the use of certain hazardous substances in electrical and electronic equipment (ROHS), which have to be implemented by the Member States in 2004. These directives will have a significant impact on the PV industry, not only because the future waste classification of PV modules is an important issue, but also the sustainability and the green image of the PV industry as a whole has to be considered. The second focus was on Life Cycle Assessment the correct evaluation of External Costs and the Recycling of Solar Modules, which will help to avoid these problems. The workshop gave an overview about the current scientific and political discussion, identified problems and showed the way for possible solutions.
Venue	European Commission EUR 21101 EN
Source	European Commission Joint Research Centre
Document Type	Final Report (Adobe Postscript file)
Resource Date	03/19/2004

Post Date	02/10/2005
Title	THE FABRICATION AND PHYSICS OF HIGH-E�CIENCY CDTE THIN-FILM SOLAR CELLS
Link	(PDF 2.2 MB) Download Acrobat Reader.
Authors	A. Compaan, et al.
Description	Cell structure and fabrication, cell modelling, and characterization of materials and devices.
Venue	NDJ-1-30630-02 September 1, 2001 to August 31, 2004
Source	University of Toledo
Document Type	Final Report (Adobe Postscript file)
Resource Date	01/2004

Post Date	02/07/2005
Title	PV STATUS REPORT 2003
Link	(PDF 671 KB) Download Acrobat Reader.
Author	A. Jager-Waldau
Description	Research, Solar Cell Production and Market Implementation in Japan, USA and the European Union.
Venue	European Commission JRC EUR 20850EN
Source	Institute for Environment and Sustainability
Document Type	Final Report (Adobe Postscript file)
Resource Date	09/2003

Post Date	02/07/2005
Title	NUMERICAL MODELING AS A TOOL FOR ANALYZING THIN-FILM SOLAR CELLS AND INTERPRETING DEVICE AND MATERIAL CHARACTERIZATION MEASUREMENTS
Link	(PDF 116 KB) Download Acrobat Reader.
Author	J. L. Gray
Description	Detailed numerical modeling has proved to be a useful tool in developing many of the current PV technologies such as single crystal Si, GaAs, ? -Si, CdTe, and CIS, to name a few. The purpose of this work is to continue development of ADEPT (A Device Emulation Program and Tool) ? primarily to integrate it with MatLab™.
Venue	NREL Report, contract XAK-8-17619-36
Source	Purdue
Document Type	Final Report (Adobe Postscript file)
Resource Date	2003

Post Date	11/11/2005
Title	TELLURIUM AVALAIBILITY FOR LARGE SCALE PV
Link	(MS Word 140 KB)
Author	J. Guilinger
Description	Analysis of sources of tellurium for multi-GWp PV production
Venue	Report to NREL
Source	World Industrial Minerals
Document Type	Final Report (Word document)
Resource Date	2000

Post Date	02/11/2005
Title	ENVIRONMENTAL ASPECTS OF PV POWER SYSTEMS
Link	(PDF 278 KB) Download Acrobat Reader.
Authors	E. A. Alsema, E. Nieuwlaar
Description	An expert workshop was held as part of the International Energy Agency Photovoltaic Power Systems Implementing Agreement Programme, to address these environmental aspects of PV power systems. The objectives of the workshop were: Review/overview of issues and approaches regarding environmental aspects of PV power systems; Enhanced clarity and consensus regarding well-known aspects like Energy Pay-Back Time; Identification of issues of environmental importance regarding PV power systems ('hot spots'); Identification of issues requiring further attention ('white spots');
Venue	IEA PVPS Task 1 Workshop 25-27 June 1997 Utrecht, The Netherlands Report no. 97072
Source	Utrecht University
Document Type	Final Report (Adobe Postscript file)
Resource Date	12/1997

Post Date	02/11/2005
Title	ENVIRONMENTAL ASPECTS OF SOLAR CELL MODULES
Link	(PDF 466 KB) Download Acrobat Reader.
Author	E. A. Alsema
Description	multicrystalline silicon, amorphous silicon, cadmium telluride and copper indium selenide are reviewed with special attention to future expected technology developments. For each module type an assessment is made of the potential environmental impacts in case of large scale implementation of the technology. In principle the entire module life cycle is taken into consideration: from resource mining, via module production and module utilization until module decommissioning and waste handling. In the report for each module type the following aspects are discussed: energy requirements and energy pay-back time, material requirements and resource depletion, environmental emissions, waste handling, possibilities for recycling of modules, occupational health and safety and external safety.
Venue	Report nr. 96074 ISBN 90-73958-17-2 Netherlands Agency for Energy and the Environment (NOVEM)
Source	Utrecht University
Document Type	Final Report (Adobe Postscript file)
Resource Date	08/1996

Quarterly Reports

Post Date	05/09/2005
Title	STABILITY, YIELD AND EFFICIENCY OF CDS/CDTE DEVICES
Link	(MS Word 70 KB)
Author	W. S. Sampath
Description	During this quarter, we have progressed on the tasks outlined in our SOW for Phase I. Reproducibility of device efficiency and stability has been demonstrated during long duration operation of the system with a single charge loading for the CdS, CdTe and CdCl2 process. Currently efforts are underway to advance the back contact processing to the same level as outlined in the SOW. Preliminary results on interconnection have yielded very promising results. Mathematical modeling of a package design has yielded results that show that moisture can be kept from our device for 22 years at 65C temperature with saturated humidity. Hardware to perform steady state photocapacitance (PHCAP) has been designed, built and tested in our laboratory. The effect of processing on the deep states in CdTe devices can be seen quantitatively. Optimum process conditions lead to lower photocapacitance signals. Many devices and CdS/CdTe samples have been provided to many groups including Larry Olsen of PNNL. Based on our current progress, no difficulties are anticipated in successfully completing the future targets outlined in the SOW. In addition to the tasks outlined above, two members of our team attended the 31st IEEE PVSC. Two oral presentations (preprints were sent to you earlier) were given. In addition, a poster was presented at the ICTMC conference and this paper has been accepted for publication in a journal. A loadlock system for the 16" X 16" substrates has been designed and constructed and is being tested. This activity is supported by another program from DOE-EERE and cost shared by NSC. Two scientists from GE Global Research were given a detailed tour of our facilities and a detailed presentation of our technology was made.
Venue	XXL-5-44205-02 to Colorado State University
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	03/2028

Post Date	09/09/2008
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(PDF 94 KB) Download Acrobat Reader.
Author	J. R. Sites
Description	Discusses (contac) barrier measurement technique, CdTe internal photoemission measurement, non-uniform CdTe barriers affecting "roll-over", CdTe cells with thin CdS layers, sheet resistance and fill factor issues, the effect of shunts on cell performance contour plots (correlations of Voc, Jsc, and FF with material parameters, and collaborative work.
Venue	Colorado State University, Fort Collins, CO, subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	06/02/2009

Post Date	02/24/2009
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 110 KB) Download Acrobat Reader.
Author	C. Heske
Description	We have initiated a detailed study of the CdS/CIGSe interface formation for world-record-class samples. A substantial data set has been recorded, and additional data-taking is currently ongoing. A series of XPS survey spectra is shown that were taken as a function of CdS thickness. Corresponding completed solar cell devices yielded efficiencies in the 15% range, while we are currently also investigating a sample series with efficiencies around 18%. These spectra, to-gether with detail spectra of each core level, the valence band maxima, and the work function are cur-rently being analyzed to develop a comprehensive picture of the electronic structure of these two CdS/CIGSe interface systems.
Venue	Subcontract XXL-5-44205-12 with U. Nevada, Las Vegas, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/15/2009

Post Date	03/11/2009
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 471 KB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando
Description	RTSE has been applied to investigate the dielectric functions of CdTe and CdS thin films sputtered at different temperatures. These dielectric functions are modeled using the critical point (CP) parabolic band approximation. Key characteristics can be deduced including grain size, excitation group speeds, stress, and temperature from the CP parameters. Capabilities for on-line optical monitoring are sought to provide information, not only on layer thicknesses and compositions, but also on grain size, stress, and temperature. As a first application, the parameterization was used to analyze the ellipsometric spectra of a stepwise etched CdTe solar cell. In this study, depth profiles in the void and grain size near the CdTe/CdS interface have been obtained.
Venue	university of Toledo, subcontract ZXL-5-44205-01, quarterly report
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/19/2008

Post Date	11/21/2008
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 107 KB) Download Acrobat Reader.
Author	C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray absorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure is painted. In February this year, the NREL group announced to have achieved a new world record effi-ciency (19.9%) for Cu(In,Ga)Se2 ?CIGSe? ? based thin-film solar cells (Ingrid Repins, Miguel A. Con-treras, Brian Egaas, Clay DeHart, John Scharf, Craig L. Perkins, Bobby To and Rommel Noufi, 19.9%-efficient ZnO/CdS/CuInGaSe2 Solar Cell with 81.2% Fill Factor, Prog. Photovolt. 16, 235 (2008).) This recent efficiency gain (compared to the former world record - 19.5%), is believed to be caused by a small ? but apparently significant ? change in the three-stage process. In comparison to the deposition process used earlier, the difference resulting in the recent world record CIGSe absorber was a termina-tion of the third (and thus last) stage without Ga and hence is considered to be ?In-terminated?. In order to shed light on the expected different chemical surface structure, we investigated a sample from the world record absorber batch (M2992) by x-ray photoelectron spectroscopy (XPS) and xray excited Auger electron spectroscopy (XAES). Both techniques are very surface sensitive (information depth a few nm) and thus well suited to address questions of surface termination. In addition, we also characterized a CIGSe absorber (M2995) deliberately terminated with Ga for comparison.
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44205-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/15/2008

Post Date

11/04/2008

Title

PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURING ISSUES

Link

(PDF 365 KB) Download Acrobat Reader.

Author

R. W. Birkmire

Description

The Effort was focused on two sub-tasks: (1) fabrication of devices with thin CdTe absorber layers, and (2) development of mechanically flexible CdTe cells by deposition onto a temporary support followed by transfer to a flexible polymer substrate.

Best-cell J-V results for VT cells with thin CdTe absorber layers using vapor CdCl2 treatment at 480�C with 2 minute CdCl2

?m)

VOC

(mV)

JSC

(mA/cm2)

FF

(%)

?

(%)

3.0

788

23.1

64.0

11.8

1.5

807

23.8

56.8

10.9

1.0

743

23.4

54.8

9.5

0.8

723

22.5

50.5

8.2

Venue

Institute of Energy Conversion, University of Delaware, subcontract ADJ-30630-12, monthly report

Source

University of Delaware

Document Type

Quarterly Report (Adobe Postscript file)

Resource Date

08/27/2008

Post Date	11/04/2008
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 439 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	The report highlights progress for CdTe-based solar cells. During this period, effort was focused on two sub-tasks: (1) deposition and characterization of device structures with thin CdTe absorber layers and (2) deposition of CdTe/CdS/ITO onto a temporary supporting superstrate for transfer to a flexible polymer substrate.
Venue	Instutute of Energy Conversion, University of Delaware, subcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/08/2008

Post Date	11/19/2008
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 1.1 MB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando
Description	This report presents: 1) properties of phosphorus-doped CdTe films prepared by sputtering from pressed targets of CdTe and Cd3P2, 2) optimization studies on ultra-thin CdS/CdTe cells with efficiencies exceeding 10% for 0.5?
Venue	University of Toledo, subcontract ZXL-5-44205-01, (CdTe), quarterly report
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/2008

Post Date	07/09/2008
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS"
Link	(PDF 123 KB) Download Acrobat Reader.
Author	J. R. Sites
Description	We continued our work on the relationship between voltage and CdS thickness with CdTe cells; the relationship between fill-factor of a cell or module and sheet resistance, geometry, current, and the JSC/VOC ratio; and the effects of local shunts on cell performance. Since the funding of the AVA incubator project took effect, I have shifted our work on CSU and AVA CdTe cells, and the reporting of those results, to the incubator project.
Venue	Coloradio State University, Subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	03/21/2008

Post Date	04/23/2008
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 744 KB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando
Description	We have developed a theory of ac response by systems of distributed diodes in parallel with resistors and capacitors connected through resistive electrodes that can represent many practical devices including photovoltaics and Schottky junctions. In particular, we have shown that: 1. There exist three lateral decay lengths related to the system diodes, shunt resistors, and capacitances respectively that determine the effective frequency-dependent lateral decay length L and describe the physics of ac response in such distributed systems; 2. The response is frequency-independent below a certain characteristic frequency, above which it strongly depends on testing frequency; 3. The 1D and 2D systems behave similarly in the large device regime, l >> L, where l is the device lateral dimension, while in the small device regime, l << L, 2D systems exhibit certain unique behavior; 4. Both the capacitance and conductance are described by closed form analytical expressions as functions of frequency and dc bias and are parametrically dependent on system material characteristics; 5. Our theoretical results establish a basis for a type of admittance characterization applicable to a wide variety of semiconductor structures including photovoltaics and Schottky junctions.
Venue	University of Toledo (CdTe), subcontract ZXL-5-44205-01, quarterly report
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	03/2008

Post Date	04/23/2008
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 466 KB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov, D. Giolando
Description	We have observed that routine maintenance procedures such as CdTe target replacement and cleaning of the corresponding ground shield influence the deposition rate and the quality of the film. For example it has been found that the pinhole density reaches its maximum right after the cleaning of the ground shield and remains relatively high for a few subsequent depositions. On the other hand once a coating of CdTe is developed on the ground shield the pinhole density becomes vanishingly small although the deposition rate can slow by as much as 50% as the ground shroud coating builds up. Not only does this present difficulties for maintaining a solid efficiency baseline throughout the sputtering target life cycle, it also reflects changes in the sputtering plasma. Being a plasma-assisted deposition technique, magnetron sputtering offers a wide range of tweaking opportunities to create thin films with desired physical properties. Without good understanding of the plasma processes the sputtering process can become excessively complicated. The basic principles of magnetron sputtering are well known and readily available in the literature. It is important to apply those principles to a specific deposition process and equipment. In this report we provide the results of the potential distribution measurements done in one of the CdTe deposition chambers at the University of Toledo. This is the same chamber we recently reported the study of the deposition rate and the CdTe film morphology. These measurements of the plasma allow us to link the typical process control data from pressure gauges and power meters to the properties of the deposited film to potential distributions inside the chamber and plasma parameters extracted from the Langmuir probe measurements.
Venue	University of Toledo (CdTe), subcontract ZXL-5-44205-01, quarterly report
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	03/2008

Post Date	12/13/2007
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(PDF 51 KB) Download Acrobat Reader.
Author	L. Olsen
Description	Data were acquired for SSI mini-modules that were coated with PNNL barrier coatings based on the new polymer blend. Results were obtained for coated modules subjected to 85�C and dry conditions, and modules with barrier coatings of thicknesses ranging from 3 microns to 10 microns. The 85�C/Dry testing was done to determine if the coatings react in a negative way with the devices. We found that all coated modules were stable in the 85�C/Dry conditions. Figure 3 gives results for a module with a coating 10 microns thick. Basically, the module is stable. Thus, it is very clear that the SSI mini-module can tolerate 85�C and dry conditions, but not a stress of 86�C/85%RH. Figure 4 gives results for coated mini-modules with the results for a bare module shown for contrast. Although the PNNL barrier coatings have made a tremendous difference, degradation still occurs. The fact that all modules degrade at the same rate, regardless of coating thickness, provides an important clue as to the cause of the degradation. Based on our overall experience, the effectiveness of the barrier coatings should improve with thickness. In general, we find that there are three cell features that can lead to defects in the multi-layer coatings which in turn provide a path for water diffusion: (i) Surface roughness; (ii ) Inadequate edge seal; (iii) Cuts separating individual cells. Since the rate of degradation of efficiency is independent of the coating thickness, we suspect that features (ii) and (iii) are most likely responsible for causing pathways of moisture diffusion. Further studies are required before this problem(s) can be clearly identified. However, the results achieved with the new polymer blends in an 85/85 environment are very encouraging.
Venue	Pacific Northwest National Laboratory, subcontract DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	12/01/2007

Post Date	02/07/2008
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 122 KB) Download Acrobat Reader.
Author	C. Heske
Description	We have derived the electronic structure of the CdS/CIGSe interface in thin film solar cells prepared by NREL. The conduction band alignment at the CdS/CIGSe interface is flat, as expected for a high efficiency CIGSe solar cell. Furthermore, we find direct evidence for a strong interface dipole. Together with the previously reported lack of significant intermixing at the CdS/CIGSe interface, we thus find a modified electronic and chemical interface structure compared to previously studied (less efficient) devices from other manufacturers.
Venue	University of Nevada, Las Vegas, subcontract XXL-5-44202-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/15/2007

Post Date	11/13/2007
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 447 KB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov
Description	We describe a series of experiments involving peel-off of the back contact and then recontacting again while several measurements were made along the way with x-ray fluorescence to monitor the Cu signal and other measurements were made with high resolution SEM and TEM. Finally, x-ray fine structure measurements provide information on the bonding of Cu in the finished cells. All three measurements together provide evidence that Cu remains localized predominantly very near the back contact in the UT sputtered cells with evaporated Cu/Au back contacts.
Venue	University of Toledo, subcontract ZXL-5-44205-01, quarterly report
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/05/2007

Post Date	11/13/2007
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 495 KB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov
Description	The focus of research during this quarter was on back contact development and on the advanced analysis of CdS using real time spectroscopic ellipsometry and its potential applications for monitoring of production lines for CdTe solar cell fabrication. A dielectric function parameterization is possible that uses the grain size as a controlling parameter -- similar to what is now possible with void fraction.
Venue	U. Toledo, subcontract ZXL-5-44205-01, quarterly report
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/05/2007

Post Date	01/14/2008
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 258 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	The IEC VT deposition process is being used to deposit CdTe films with thickness approaching 1 micron suitable for cells with 11% conversion efficiency. However, the thickness uniformity of the obtained deposit is more difficult to control in the high deposition rate regime (10 mm/min) than for baseline thickness ~5-7 mm. Also, the films are more prone to having voids in the CdTe layer, which become shunt paths in devices. The post-deposition processing becomes more critical since thinner films have smaller grains and are therefore more sensitive to grain boundary-enhanced processes such as interdiffusion of CdS-CdTe, oxide penetration, and penetration from any etchants used to process the back contact. In the previous year of work, we showed that 11% baseline performance could be maintained with 1.5-3 micron thick CdTe by reducing the CdCl2 vapor treatment processing time, using milder etchants, and reducing the Cu quantity at the back contact, either by depositing a thinner layer or by incorporating the Cu into the ZnTe contact.
Venue	Institute of Energy Conversion, University of Delaware, subcontrat ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/25/2007

Post Date	11/29/2007
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(PDF 70 KB) Download Acrobat Reader.
Author	J. R. Sites
Description	During the past quarter, two students completed their PhD and one other is preparing for his defense. At the same time, we expanded our work on the analysis of cells with non-uniformities, we began a collaboration on CIGS made with laser-assisted deposition, and we continued several measurement and analysis projects in collaboration with other laboratories.
Venue	Colorado State University, subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/24/2007

Post Date	11/21/2007
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL, AND MANUFACTURABILITY ISSUES
Link	(PDF 321 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	Issues related to high throughput processing of and junction- limiting factors in thin film CdTe solar cells are reported. Concerns over possible sources of impurity contamination of CdTe has prompted further analysis of the influence of soda lime glass (SLG) SLG/SnO2 substrate preparation as well as the chemistry of the CdS growth and its effect on the CdS-CdTe junction region. With respect to high throughput deposition and CdTe usage, we have deposited CdTe films by VT with sub-micron thickness having low pinhole density.
Venue	IEC, University of Delaware, subcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/21/2007

Post Date	08/15/2007
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(PDF 89 KB) Download Acrobat Reader.
Author	L. Olsen
Description	The key objectives of the program are to develop low cost barrier coatings for CIS and CdTe solar cells and to develop an improved understanding of the effects of water on the stability of these types of cells. The scope of this work entails investigations multilayer, barrier coatings for CIS and CdTe thin film solar cells, and studies of stability issues, particularly those related to moisture ingress. Investigation of barrier coatings on SSI and CSU devices will continue in an effort to establish effective approaches encapsulate CIS and CdTe modules. Studies will also be directed towards issues concerning cost of the coating process. The program will be structured into three major tasks: (1) Barrier coatings and stability studies for CIS Solar Cells; (2) Barrier coatings and stability studies for CdTe solar cells; (3) Low cost coating process development.
Venue	PNNL, agreement DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	06/2007

Post Date	08/03/2007
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(PDF 66 KB) Download Acrobat Reader.
Author	J. R. Sites
Description	Reports CIGS nonuniformities, CdTe efficiency (n-p vs. p-i-n), light bias QE, and CdS thickness variation in CdTe cells (all presented at the MRS Spring meeting)
Venue	Colorado State University (Sites), subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/27/2007

Post Date	08/15/2007
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(PDF 56 KB) Download Acrobat Reader.
Author	L. Olsen
Description	Our investigations to date were based on Shell Solar, Inc. (SSI) cells and mini-modules. We found that these cells were extremely vulnerable to damp heat effects. These devices are no longer available to PNNL due to the closing of the Chatsworth CIGS operation. However, we have a supply of 2 in. x 2 in. mini-modules that were used in recent studies that are discussed in this report. Moisture ingress is apparently not an issue if modules are fabricated with glass-to-glass construction. It is clear, however, that CIGS cells and modules fabricated on flexible substrates must have an effective barrier coating. As a result, we plan to concentrate on establishing baseline information concerning the effects of damp heat on CIGS.
Venue	PNNL, agreement DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/2007

Post Date	06/25/2007
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURING ISUES
Link	(PDF 235 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	Issues related to high throughput processing of and junction- limiting factors in CdTe solar cells are reported. Based on the effects of TCO/substrate cleaning described in the previous report, we continued with the study of uncontrolled impurities originating in the glass/SnO 2 substrate. It is vital that this source of variability in film morphology and device performance is eliminated prior to development of cells with sub-micron absorber thickness and evaluation of approaches for VOC > 900 mV. In this report, we present the details of procedures used to establish a performance baseline with cell efficiency >11% for processing CdTe/CdS cells with vapor transport deposited CdTe onto moving commercially available substrates at high growth rate (~10 m/min) using rapid post-deposition processing, with less than 1 min per processing step.
Venue	Institute of Energy Conversion, U. Delaware, Suibcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/24/2007

Post Date	03/14/2007
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 146 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	A study is warranted to determine the effects of glass handling and cleaning and buffer layer formation on the grain structure and variability in performance of the CdTe devices. Statistical analysis of the device performance of more than 450 VT devices using the baseline process revealed a V OC distribution with a sharp maximum at 800 mV and excursions to 850 mV. The effort to demonstrably improve VOC and to fabricate cells with ultra-thin absorber layers will require a tighter baseline distribution. Due to the combination of superstrate configuration and high processing temperatures used for VT CdTe solar cells, uncontrolled impurities originating in the glass/SnO2 and its handling can become trapped in the structure and critically affect junction quality, in which case the intrinsic buffer layer may serve as a diffusion barrier as well as an electronic circuit element. The role of the Ga2O3 in mitigating effects from the SnO2 is demonstrated in for cells made from a single VT deposition with and without Ga2O3 and CdS in the window side of the device.
Venue	IEC, University of Delaware, subcontract ADJ-1-30630-12, monthly report
Source	N/A
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/31/2007

Post Date	02/15/2007
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 348 KB) Download Acrobat Reader.
Authors	M. Baer, C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. In the last months, we started to investigate CdS/CIGSe samples provided by the National Renewable Energy Laboratory. We do not find any evidence for a very strong intermixing process (i.e., S atoms diffusing into the substrate). However, the environment of the sulfur atoms at the growth start of the interface clearly deviates from a perfect CdS environment. Whether this is due to a less perfect crystalline structure (i.e., the formation of very small nm-scale nanoparticles) or some S diffusing into the CIGSe absorber can not unambiguously be differentiated.
Venue	U. Nevada, Las Vegas, subcontract XXL-5-44205-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/11/2007

Post Date	03/14/2007
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(PDF 47 KB) Download Acrobat Reader.
Author	L. Olsen
Description	Studies of photoluminescence in CdTe solar cell structures continued. The objective of this effort is to determine if the PL spectrum for a CdTe device is affected by stress. In particular, we are interested in determining if moisture affects carrier properties. Samples studied were cell structures without back contacts previously provided by CSU. Figure 1 describes our approach to PL studies. This figure is repeated from the last quarterly report. An excitation wavelength of 580 nm was used and band gap emission observed for the excitation beam entering through the glass and through the CdTe side.
Venue	PNNL, DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/2007

Post Date	01/30/2007
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 1.0 MB) Download Acrobat Reader.
Authors	A. Compaan, R. W. Collins, V. G. Karpov
Description	This progress report covers the First Quarter of Phase 2 for the period from June 1, 2006 through August 31, 2006, of the above Thin Film Photovoltaic Partnership Program subcontract. The focus of research during this quarter was on materials issues including high rate deposition and in situ real time analysis of film growth and post-processing. Results of high rate sputter deposition (Task 2.1.3) and real-time spectroscopic ellipsometry study of rf-sputtered solar cells (task 2.3.3) have been described. The most important data obtained from this study are the optical properties of the alloys as functions of composition as well as measurement temperature.
Venue	University of Toledo (CdTe), subcontract ZXL-5-44205-01, Quarterly Report
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	12/2006

Post Date	01/08/2007
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(PDF 106 KB) Download Acrobat Reader.
Author	J. R. Sites
Description	Alan Davies has been working closely with Sampath?s group, Al Enzenroth in particular, to explore buffer layers that would allow the CSU cells to be made with thinner CdS without compromising performance in other ways. Alan Fahrenbruch, also using CdTe cells fabricated by Sampath?s group, has examined transient effects related to photoconductivity and has related these to anomalous AQE effects. Ana Kanevce has added nonuniformities in diode voltage to her simulations of CIGS cells with submicron absorber layers. Several physical conditions (reduced local Ga concentration, reduced local thickness, reduced back electron reflector) can be well approximated by a weak diode with a lower value of VOC in the midst of an array of normal diodes. Ana also worked with Raghu Bhattacharya of NREL on the analysis of CIGS cells that that were fabricated with a solution-grown CdZnS buffer layer. The best of these cells achieved 19.5% efficiency, equal to that achieved with NREL?s standard CdS buffer. At short wavelengths, the CdZnS buffer did achieve about 2 mA/cm2 higher current than the CdS buffer, but it also had slightly less collection in the longer wavelength region.
Venue	Colorado State University, subcontract XXL-5-44205-03, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/27/2006

Post Date	12/22/2006
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(PDF 106 KB) Download Acrobat Reader.
Author	L. Olsen
Description	No substrates with CdTe cell structures were received this quarter from CSU or UT. As a result, studies of photoluminescence in CdTe solar cell structures were initiated. The objective of this effort is to determine if the PL spectrum for a CdTe device is affected by stress. In particular, we are interested in determining if moisture affects carrier properties. Samples studied were cell structures without back contacts provided a year ago by CSU. The approach to the PL studies is described in Figure 1. An excitation wavelength of 580 nm was used and band gap emission observed for the excitation beam entering the through the glass and through the CdTe side.
Venue	PNNL, Memorandum Purchase Order ("subcontract") DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/2006

Post Date	12/20/2006
Title	MANUFACTURING PROCESS OPTIMIZATION TO IMPROVE STABILITY, YIELD, AND EFFICIENCY OF CDS/CDTE PV DEVICES
Link	(PDF 98 KB) Download Acrobat Reader.
Author	W. S. Sampath
Description	We have progressed on the tasks outlined in our SOW for Phase II. Significant advances to the design of module packaging have been made. Desiccant containing materials for the edge seal and sealing of the holes in the back glass have been tested in damp heat tests at NREL with very promising results. Hardware modifications to the pilot system for automated cooling of the substrate in vacuum have been completed and device efficiencies of 11.83 % have been made in "all forward" process. Significant progress has been made in characterizing films with ellipsometry and the use of ellipsometry for quality control is being investigated. Efforts to improve device efficiency and advance device characterization are underway. Based on our current progress, no difficulties are anticipated in successfully completing the future targets outlined in the SOW. A prototype production system to process 16.5x16.5 inch substrates continues to be advanced. This activity is supported by another program from DOE-EERE and cost shared by National Starch and Chemicals (NSC).
Venue	Colorado Stae University, subcontract XXL-5-44205-02, quarterly report
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/17/2006

Post Date	12/08/2006
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 199 KB) Download Acrobat Reader.
Author	C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spec-troscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. We could gather first results for Cu(In,Ga)Se2 (?CIGSe?) and Cu(In,Ga)(S,Se2) (?CIGSSe?) samples prepared by the group of W. Shafarman (Institute of Energy Conversion, University of Delaware). The aim of the conducted experiments is to shed light on the deeply buried absorber/back contact interface in terms of its chemical and electronic properties. We had to develop a suitable lift-off (or cleavage) technique, which allowed us to cleave the absorber/Mo/glass samples at the desired interface. It turned out that gluing the front side of the absorber/Mo/glass thin film stack to a stainless a steel plate using a conductive (Ag-containing) epoxy allows a subsequent division of the stack in two parts and provides the necessary conductivity for the PES measurements. In all cases the thin film stack cleaved at the absorber/Mo inter-face. However, there were differences in terms of the area exposed after lift-off. Compar-ing the CIGSe/Mo/glass and CIGSSe/Mo/glass samples with respect to their cleavage behavior, it seems that for the latter it is rather easy to lift off large areas (in the range of cm2). This is favorable with respect to the characterization by PES but even more impor-tant for the planned inverse photoemission (IPES) measurements, since the IPES detector is not able to ?artificially? reduce the spot size of the e-gun on the sample (which is approx. 1 cm^2) as it can easily be done in the PES case, probing differently sized areas by using different lens modes of the electron analyzer.
Venue	U. Nevada, Las Vegas, Subcontract No. XXL-5-44205-12, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/15/2006

Post Date	11/07/2006
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
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Author	R. W. Birkmire
Description	During this reporting period, effort continued on high throughput fabrication of thin film CdTe/CdS cells with CdTe deposited by vapor transport (VT). The CdS films were deposited by chemical surface deposition (CSD) onto 10 x 10 cm plates of Pilkington TEC15 SnO 2/glass. Particular focus was placed on Ga deposition for the high resistance (HR) Ga2O3 buffer layer and on the chemical state of the TCO. Analysis of the chemical state of the CdTe surface after aniline treatment continued and shows that, like other etchants, the aniline treatment removes surface-bound oxygen and chlorine, generates Te, but also may leave a trace hydrocarbon residue behind.
Venue	IEC (U. Delaware), subcontract ADJ-1-30630-12, quarterly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/04/2006

Post Date	09/28/2006
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
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Author	L. Olsen
Description	Efforts have concentrated on establishing procedures for collaboration with Dr. Sampath's group at CSU and Dr. Compaan's group at the University of Toledo. In both cases, we have supplied patterned SnO2 - coated glass for growth of CdS/CdTe structures. It turns out, however, that removing SnO2 from LOF TEC 15 is not trivial. We received valuable guidance from Dr. Sampath. Referring to Figure 1, we plan to start with SnO2 -coated glass, pattern the SnO2 as illustrated in Figure 1A, send the substrates to CSU and UT for growth of CdS/CdTe devices. In the case of CSU, the back contact will be applied at PNNL for some of the structures. Removing the tin-oxide has turned out to be non-trivial.
Venue	PNNL, Purchase Order DAX-4-44239-01, quarterly report
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/2006

Post Date	09/19/2006
Title	PROCESSING, MATERIALS, DEVICES AND DIAGNOSTICS FOR THIN FILM PHOTOVOLTAICS: FUNDAMENTAL AND MANUFACTURABILITY ISSUES
Link	(PDF 173 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	CdTe cell fabrication focused on evaluation of alternative high resistance (HR) buffer layers and the influence of ambient composition during vapor transport (VT) CdTe deposition and vapor CdCl2 treatment. Aspects of CdTe surface chemistry were investigated with respect to rapid vapor CdCl2 treatment and anilinine etching. Bifacial solar cell analysis of cells with different CdTe thickness was carried out to provide detailed understanding of device operation and its relation to processing optimization.
Venue	IEC, U. of Delaware, subcontract ADJ-1-30630-12, monthly report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	07/31/2006

Post Date	07/25/2006
Title	BARRIER COATINGS
Link	(MS Word 145 KB)
Author	L. Olsen
Description	Coatings to protect thin film cells.
Venue	Quarterly Phase 2, #2
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	07/2006

Post Date	07/13/2006
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(MS Word 42 KB)
Author	J. R. Sites
Description	During the past quarter, our group made progress in several areas as outlined below. Several of us participated actively in the CdTe and CIS team meetings. I made a trip to IEC in February to give a colloquium and discussion several topics of mutual interest. Adjacent to that visit, I attended to the DOE PV module-reliability meeting in Baltimore. I also participated (not at NREL expense) in the DOE?s SAI-input meeting that took place in Chicago in March. Our primarily work with industrial partners was LBIC measurements on Nanosolar cells and with assistance to Heliovolt in the design of current-voltage and quantum-efficiency measurement systems for their cells.
Venue	Quarterly Report V (February - April 2006) Subcontract XXL-5-44205-03 For additional information: www.physics.colostate.edu/groups/photovoltaic
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	07/2006

Post Date	05/30/2006
Title	INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN-FILM SILICON FOR IMPROVED MODULE PERFORMANCE
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Author	J. D. Cohen
Description	Although nc-Si:H does not suffer as severely from light exposure as amorphous silicon, prolonged light soaking typically reduces the conversion efficiency by several percent . Several of our samples were examined both in ?State A?, after a sample had been annealed for 1 hour at 450 K, as well as in ?State B?, a degraded state which we obtained by exposing the sample to 20 hours of red-filtered light (>620 nm) from a tungsten-halogen source at an intensity of 400 mW/cm 2. Effects of such light soaking could be observed both in the photo-transient spectra as well as in drive-level capacitance profiles (DLCP). We see that the TPC signal changes significantly. In particular, the negative signals near 1.5 eV become significantly positive in State B. This corresponds to a loss of hole collection, even more than was achieved by reducing the measurement temperature from 295 K to 275 K in State A. What is particularly surprising, however, is that when such a deep defect response is apparent, we consistently have found that it decreased after prolonged light exposure.
Venue	University of Oregon, 3rd Quarterly report, Subcontract ZXL-5-44205-11
Source	University of Oregon
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/30/2006

Post Date	05/02/2006
Title	STUDIES OF BASIC ELECTRONIC PROPERTIES OF CDTE-BASED SOLAR CELLS
Link	(PDF 22 KB) Download Acrobat Reader.
Author	J. Beach
Description	Study of Deep Electronic States controlling VOC.
Venue	CSM Extension of ADJ-2-30630-05,
Source	Colorado School of Mines, Golden, CO
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/01/2006

Post Date	05/30/2006
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(MS Word 87 KB)
Author	L. Olsen
Description	CdTe cell structures provided by CSU were stressed and then characterized with XPS in an effort to understand the effects of moisture on CdTe devices. If we assume the emission is primarily due to oxides on the grain boundaries, it appears that the unknown complex oxide could play a key role in grain boundary passivation. It could therefore be very valuable to determine the identity of this complex oxide. Based on results for the stressed cell, significant effects of the 60�C/90%RH stress may be formation of Cd(OH)2 along grain boundaries, and elimination of the unknown complex Cd-based oxide along the grain boundaries. If we assume that the unknown oxide is important for grain boundary passivation and/or the hydroxide results in increased recombination at grain boundaries, then it is understandable that both Jsc and Voc would decrease as a result of damp heat. We conclude, therefore, that damp heat does more than just degrade the contacts in CdTe cells. In particular, it appears that formation of Cd(OH)2 leads to increased recombination at grain boundaries, which decreases cell quantum efficiency and increases current losses (larger Jo).
Venue	1st Quarterly Report - Phase II: September 1, 2005 -- November 30, 2005 NREL Subcontract: 48027
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	05/2006

Post Date	06/12/2006
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 78 KB) Download Acrobat Reader.
Authors	M. Baer, C. Heske
Description	Eight CdTe materials samples used in actual solar cell were investigated by X-ray emission spectroscopy (XES). This technique provides detailed informations about the chemical properties of the investigated samples. XES as a photon-in photon-out technique probes the ?near-surface? bulk. In our case, where we have focused on the S L2,3 and Cl L2,3 emission, this method has an information depth of about 100 nm. Based on the results obtained, we will continue the investigation of CdTe/CdS samples and extend them by investigating customized sample series with UPS and IPES to get insight into the band alignments at the various interfaces of the device structure of an CdTe-based solar cell. At the recent CdTe R&D team meeting (as well as at the CIS R&D team meeting) we have initiated a sample exchange with several (six) groups from within the Thin Film Photovoltaic Partnership Program. The planned experiments will shed light on the various interfaces in both CIS and CdTe cells. First samples have already been received at UNLV.
Venue	Subcontract XXL-5-44205-12, University Nevada, Las Vegas, quarterly report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/15/2006

Post Date	04/19/2006
Title	CDTE
Link	(PDF 160 KB) Download Acrobat Reader.
Author	B. E. McCandless
Description	Summary: The CdTe cell fabrication effort focused on CdTe deposition and post deposition processing to increase throughput and raise baseline cell efficiency. The effect of carrier gas composition and substrate temperature on vapor transport (VT) CdTe film growth and device performance was evaluated. Vapor CdCl2 treatments, which allow the treatment temperature to be separated from the CdCl2 and O2 concentration, were refined to allow a new baseline process to be defined with treatments ~ 2 minute in duration. Reduction in treatment time required increasing the treatment temperature of the CdTe/CdS and maintaining the partial pressures of CdCl2 and O2 to ~5 mTorr and 120 Torr, respectively. Similarly, the aniline photo-activated surface treatment was refined to permit effective Te formation in less than 5 minutes, by increasing the intensity of the incident light. In the area of device performance, analysis of J(V) curves has indicated that most CdTe cells can be described with three circuit elements: by a single forward diode (given by A, Jo), a resistance (R), and a voltage dependent photocurrent.
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/2006

Post Date	04/27/2006
Title	CSU CDTE
Link	(MS Word 58 KB)
Author	W. S. Sampath
Description	During this quarter, we have progressed on the tasks outlined in our SOW for Phase II. A fixture for automated cooling of the substrate in vacuum has been designed, fabricated, installed and tested. This is needed for optimum processing of the back contact. Large area devices in the form of strips (~0.5 cm X 8 cm.) have been fabricated and tested at NREL. Efficiency of 10.9% has been measured. The air-to-vacuum-to-air seals in the pilot system have a glass filled teflon liner. These liners have experienced wear and this results in scraping of the glass substrates in the seal. Improved liners have been designed and fabricated and are being installed in the system. Based on our current progress, no difficulties are anticipated in successfully completing the future targets outlined in the SOW. A prototype production system to process 16.5x16.5 inch substrates continues to be advanced. This activity is supported by another program from DOE-EERE and cost shared by National Starch and Chemicals (NSC). We are also in discussion with a reputed company to form a strategic partnership to manufacture large volumes of CdTe PV based on our technology. Numerous documents have been submitted to this group for evaluating our technology. These discussions have advanced significantly.
Venue	XXL-5-44205-02
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	04/2006

Post Date	02/01/2006
Title	STUDIES OF BASIC ELECTRONIC PROPERTIES OF CDTE-BASED SOLAR CELLS
Link	(PDF 152 KB) Download Acrobat Reader.
Author	J. Beach
Description	The goal of this deep electronic states (DES) study is to detect, characterize, and identify DES that may be either limiting or enhancing VOC in order to help cell growers modify their processes to improve their devices. A J-V-T, QE, and impedance characterization analysis was performed on cells received from X. Wu that were processed without intentionally added Cu and with three CdCl2 treatments. This compliments a set of previously analyzed cells with added Cu and the same three CdCl2 treatments. This is part of an ongoing collaborative study with Wu. Further analyses are expected with variable Cu and O2
Venue	CSM Extension of ADJ-2-30630-05, Studies of Basic Electronic Properties of CdTe-based Solar Cells.
Source	Colorado School of Mines, Golden, CO
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/31/2006

Post Date	02/28/2006
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 99 KB) Download Acrobat Reader.
Author	C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission spectroscopy) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as the chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance. In our recent beamtime at the Advanced Light Source, Lawrence Berkeley National Laboratory we collected first results with Cu(In,Ga)Se2 samples prepared by NREL. Together with additional photoemission measurements a detailed picture of the chemical composition at several interfaces and surfaces of the device structure can be drawn. The setup for inverse photoemission at UNLV was commissioned and first spectra were recorded.
Venue	U. Nevada, Las Vegas, subcontract XXL-5-44205-12, 2nd Quarterly Report
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/18/2006

Post Date	12/16/2005
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(MS Word 45 KB)
Author	J. R. Sites
Description	CdTe Device Model; Cu in the Back Contact;Back-Illuminated LBIC; CdTe Photoluminescence; CIGS Thin Absorbers/Back Lighting; Effective Module Efficiency The two key module parameters that control the effective efficiency are the series resistance and leakage conductance of the module; (1) ?Grain-Boundary Recombination in Cu(In,Ga)Se2 Solar Cells,? J. Appl. Phys. 98, 113704, 10 pp (2005). M. Gloeckler, W.K. Metzger, and J.R. Sites. (2) ?Potential of Sub-micrometer Thickness Cu(In,Ga)Se2 Solar Cells,? J. Appl. Phys. 98, 103703, 7 pp (2005). M. Gloeckler and J.R. Sites.
Venue	Subcontract XXL-5-44205-03 Quarterly Report IV (September - November 2005); : http://www.physics.colostate.edu/groups/photovoltaic
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	12/15/2005

Post Date	01/11/2006
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 591 KB) Download Acrobat Reader.
Authors	A. Compaan, V. G. Karpov
Description	This progress report covers the third quarter of Phase 1 for the period September 1, 2005, through November 30, 2005, of the above Thin Film Photovoltaic Partnership Program subcontract. During this quarter we worked on thin CdTe solar cell limitations, spatial and temporal variations in electronic transport through a CdTe-based Schottky barrier, device physics modeling, and ellipsometric diagnostics. In this report we highlight our recent results on the distribution of copper in sputtered CdTe solar cells (task 1.3.4) and recently discovered reversible piezo-effect in CdTe/CdS solar cells consistent with the piezo parameters of CdS, which strongly supports our MIS device model (task 1.2.1).
Venue	RXL-5-44205-01 Phase 1/Quarter 3
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	12/2005

Post Date	12/16/2005
Title	CDTE-BASED SOLAR CELLS
Link	(PDF 670 KB) Download Acrobat Reader.
Author	B. E. McCandless
Description	Alternative Cu-based contact processing for CdTe/CdS devices; Back contact analysis using bifacial CdTe devices; Bifacial Spectral Response Characterization: effect of CdTe thickness
Venue	NREL Subcontract #ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	11/30/2005

Post Date	10/21/2005
Title	CHARACTERIZATION OF THE ELECTRONIC AND CHEMICAL STRUCTURE AT THIN FILM SOLAR CELL INTERFACES
Link	(PDF 414 KB) Download Acrobat Reader.
Author	C. Heske
Description	This project is devoted to deriving the electronic structure of interfaces in Cu(In,Ga)(S,Se)2 and CdTe thin film solar cells. By using a unique combination of spectroscopic methods (photoelectron spectroscopy, inverse photoemission, and X-ray ab-sorption and emission) a comprehensive picture of the electronic (i.e., band alignment in the valence and conduction band) as well as chemical structure can be painted. The work focuses on (a) deriving the bench mark picture for world-record cells, (b) analyze state-of-the-art cells from industrial processes, and (c) aid in the troubleshooting of cells with substandard performance.
Venue	subcontract quarterly report, U. Nevada, Las Vegas, XXL-5-44205-12
Source	University of Nevada, Las Vegas
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	10/13/2005

Post Date	09/13/2005
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(MS Word 44 KB)
Author	J. R. Sites
Description	During the past quarter, we made progress in several areas as outlined below. I am particularly pleased that the two students who completed their PhD this year have accepted R&D positions in the US thin-film photovoltaic industry. Alex Pudov starts at Nanosolar in Palo Alto this week, and Markus Gloeckler will be joining First Solar in Toledo in early October.
Venue	Quarterly Report III (June - August 2005) Subcontract XXL-5-44205-03
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	09/12/2005

Post Date	09/13/2005
Title	DEVELOPMENT OF A WIDE BAND GAP CELL FOR THIN FILM TANDEM SOLAR CELLS
Link	(PDF 64 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	CdZnTe and CIGS alloys
Venue	XAT-4-33624-01 6th Quarterly Report
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/2005

Post Date	09/30/2005
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 605 KB) Download Acrobat Reader.
Authors	A. Compaan, V. G. Karpov
Description	This progress report covers the second quarter of Phase 1 for the period June 1, 2005, through August 31, 2005, of the above Thin Film Photovoltaic Partnership Program subcontract. During this quarter we worked on spatial and temporal variations in electronic transport through a CdTe-based Schottky barrier, ellipsometric diagnostics, device physics modeling, and thin CdTe solar cell limitations. In this report we highlight our recent results on optical spectroscopy of deep levels in CdTe single crystal (task 1.3.1) and analysis of structural evolution during growth of CdS and CdTe from real time spectroscopic ellipsometry (task 1.3.2)
Venue	RXL-5-44205-01 Phase 1/Quarter 2
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/2005

Post Date	10/05/2005
Title	CSU 3RD Q REPORT
Link	(MS Word 103 KB)
Author	W. S. Sampath
Description	During this quarter, we have progressed on the tasks outlined in our SOW for Phase I. A significant extension to our pilot scale system has been designed, fabricated, installed and debugged. This will allow improved process conditions for the back contact process steps. The feasibility of cooling the substrate in vacuum for optimum processing of the back contact has been demonstrated. A large number of experiments have been performed on laser scribing of CdS/CdTe films. Mechanical scribing has yielded the lowest contact resistance between the scribed region and the metallization, to date. Researchers at National Starch and Chemicals (NSC) have performed many experiments to screen print carbon, nickel and silver films in patterns. The adhesion of these films was tested according to ASTM 3359B and achieved a 5B or "excellent" rating. Based on our current progress, no difficulties are anticipated in successfully completing the future targets outlined in the SOW. The nominal 2 MW/yr production prototype system continues to be advanced. This activity is supported by another program from DOE-EERE and cost shared by National Starch and Chemicals (NSC). Three separate groups have expressed interest in licensing our technology for 50 MW/Yr plants. We are also in discussion with a large manufacturer for partnership to manufacture large volumes of CdTe PV. Numerous documents have been submitted to these groups for evaluating our technology. Detailed presentations and demonstrations of our technology were also given to many groups.
Venue	Thin Film Partnership Program (Subcontract No. XXL-5-44205-02
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	09/2005

Post Date	08/31/2005
Title	FABRICATION AND PHYSICS OF CDTE DEVICES BY SPUTTERING
Link	(PDF 529 KB) Download Acrobat Reader.
Authors	A. Compaan, V. G. Karpov
Description	During this quarter we worked on ellipsometric diagnostics, device physics modeling and thin CdTe solar cell limitations. In this report we highlight our recent results on real-time spectroscopic ellipsometry studies of rf-sputtered solar cells (task 1.3.2) and quantitative estimates of nonuniformity loss in solar cell modules, including the effect of series resistance.
Venue	RXL-5-44205-01 Phase 1/Quarter 1
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/2005

Post Date	08/02/2005
Title	IEC MONTHLY REPORT: CDTE
Link	(PDF 2.1 MB) Download Acrobat Reader.
Author	B. E. McCandless
Description	Different aspects of processing vapor transport (VT) solar cells were evaluated and new processing options to address key issues of high throughput are being developed. In particular, variations in device performance are correlated with systematic variations in the CdCl2 treatment and with the exposure of fresh CdTe surfaces to humid ambient prior to CdCl2 treatment. With respect to CdTe deposition, characterization of the VT deposition system was carried out to refine the quantitative model used to monitor deposition rate and Cd utilization. With respect to surface treatments for back contact processing; alternatives to BDH processing, such as aniline treatment, continue to be investigated. Temperature dependant bifacial QE measurements gave new insights into the CdTe device physics. The formation rate and composition of oxide phases in CdTe films was investigated with respect to humidity. Participation in the National CdTe R&D Team meeting held in May 2005 is described.
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/01/2005

Post Date	08/31/2005
Title	ADVANCED PROCESSING OF CDTE- AND CUINXGA1-XSE2
Link	(PDF 325 KB) Download Acrobat Reader.
Author	C. S. Ferekides
Description	quarter of Phase III of the above subcontract. The project deals with two thin film technologies: CdTe and CIGS. The focus areas include: (a) CdTe ? stability, novel back/front contacts, and the development of manufacturing friendly processes; (b) CIGS ? development of two-step non-co-evaporation technology.This is the progress report for the 3rd
Venue	NDJ-2-30630-18 Phase III/Quarter 3
Source	University of South Florida, Tampa
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/2005

Post Date	07/26/2005
Title	RESEARCH LEADING TO HIGH THROUGHPUT MANUFACTURING OF THIN-FILM CDTE PV MODULES
Link	(MS Word 165 KB)
Authors	R. C. Powell, P. V. Meyers
Description	Reactor Design Advanced Front Contacts ChlorineIssues Back-Contact Issues Stabilitiy Issues Third Level Metrics
Venue	RDJ-2-30630-20 (); Q11 Quarterly Report
Source	First Solar, Toledo, OH
Document Type	Quarterly Report (Word document)
Resource Date	07/15/2005

Post Date	08/04/2005
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(MS Word 3.4 MB)
Author	L. Olsen
Description	Work concentrated on studies concerning encapsulation of CdTe cells. Three topics are discussed: further consideration of results for a CSU cell encapsulated with a single dyad/Al-film combination; results for studies of stressed bare cell cells from CSU and University of Toledo; and studies of encapsulated calcium samples subjected to heat and humidity conditions.
Venue	3rd Quarterly Report - Phase I: March 1, 2005 -- May 31, 2005
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	07/2005

Post Date	06/14/2005
Title	CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS
Link	(MS Word 46 KB)
Author	J. R. Sites
Description	During the past quarter, we reported a number of results at both the Materials Research Society Spring Meeting in late March and the CdTe National Team Meeting in early May. Most of the manuscripts or powerpoint slides from these and other presentations are available on our web site: www.physics.colostate.edu/groups/photovoltaic In addition, Markus Gloeckler recently completed his PhD degree. His thesis, which is both attached and on the web page, contains a more extensive description of his work on CIGS grain boundaries, grading effects, and efficiency limitations than that published or submitted for publication.
Venue	Quarterly Report II (March - May 2005) Subcontract XXL-5-44205-03
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	06/13/2005

Post Date	06/27/2005
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(MS Word 1.8 MB)
Author	L. Olsen
Description	The key objectives of the program are to develop low cost barrier coatings for CIS and CdTe solar cells and to develop an improved understanding of the effects of water on the stability of these types of cells. The scope of this work entails investigations of multilayer, barrier coatings for CIS and CdTe thin film solar cells, and studies of stability issues, particularly those related to moisture ingress. Investigation of barrier coatings on SSI and CSU devices will continue in an effort to establish effective approaches to encapsulate CIS and CdTe modules. Studies will also be directed towards issues concerning cost of the coating process. The program will be structured into three major tasks: (1) Barrier coatings and stability studies for CIS Solar Cells; (2) Barrier coatings and stability studies for CdTe solar cells; (3) Low cost coating process development.
Venue	2nd Quarterly Report - Phase I: December 1, 2004 -- February 28, 2005
Sources	Colorado State University; Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	06/2005

Post Date	07/15/2005
Title	QUARTERLY REPORT CDTE
Link	(MS Word 80 KB)
Author	W. S. Sampath
Description	During this quarter, we have progressed on the tasks outlined in our SOW for Phase I. The reproducibility of device efficiency and stability results during long duration operation of the pilot system with a single charge loading for the CdS, CdTe and CdCl2 processes has been reported earlier by us [1]. Currently, efforts are underway to advance the back contact processing to this same level of reproducibility, as outlined in the SOW. In order to accomplish this, a significant upgrade to increase the processing space in our pilot scale system has been designed, fabricated and is currently being installed. A series of detailed studies on the effect of oxygen during the CdCl2 treatment has been performed. Oxygen has been shown to improve the effectiveness of the CdCl2 treatment. Preliminary results on developing a module interconnection process are promising. Many devices and CdS/CdTe films have been provided to many groups including Larry Olsen of PNNL. Based on our current progress, no difficulties are anticipated in successfully completing the future targets outlined in the SOW. A loadlock system for the prototype production system to transport 16.5x16.5 inch substrates has been designed, constructed and successfully tested. This activity is supported by another program from DOE-EERE and cost shared by National Starch and Chemicals (NSC). Three separate groups including Lisa Barnett from DOE headquarters, Bolko Von Roedern of NREL, Dave Miles from NSC and other representatives from DOE, Peter Meyers and Roger Green of First Solar, and members of the Fort Collins business community were all given a detailed tour of our facilities. Detailed presentations and demonstrations of our technology were also given.
Venue	XXL-5-44205-02
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	06/2005

Post Date	05/20/2005
Title	*ADVANCED PROCESSING OF CDTE- AND CUINXGA1-XSE2*
Link	(PDF 277 KB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description	This is the progress report for the 2nd quarter of Phase III of the above subcontract. The project deals with two thin film technologies: CdTe and CIGS. The focus areas include: (a) CdTe ? stability, novel back/front contacts, and the development of manufacturing friendly processes; (b) CIGS ? development of two-step non-co-evaporation technology.
Venue	NDJ-2-30630-18 Phase III/Quarter 2
Source	University of South Florida, Tampa
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/2005

Post Date	05/13/2005
Title	CENTER OF EXCELLENCE
Link	(PDF 529 KB) Download Acrobat Reader.
Authors	R. W. Birkmire, B. E. McCandless
Description	This report covers research conducted at the Institute of Energy Conversion (IEC) for the period from March 3, 2005 to April 3, 2005, under the subject subcontract. The report highlights progress and results obtained under Task 1 (CdTe-based solar cells).
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	04/2005

Post Date	04/05/2005
Title	SUBCONTRACT NO. XXL-5-44205-02 TO COLORADO STATE UNIVERSITY
Link	(MS Word 70 KB)
Author	W. S. Sampath
Description	During this quarter, we have progressed on the tasks outlined in our SOW for Phase I. Reproducibility of device efficiency and stability has been demonstrated during long duration operation of the system with a single charge loading for the CdS, CdTe and CdCl2 process. Currently efforts are underway to advance the back contact processing to the same level as outlined in the SOW. Preliminary results on interconnection have yielded very promising results. Mathematical modeling of a package design has yielded results that show that moisture can be kept from our device for 22 years at 65C temperature with saturated humidity. Hardware to perform steady state photocapacitance (PHCAP) has been designed, built and tested in our laboratory. The effect of processing on the deep states in CdTe devices can be seen quantitatively. Optimum process conditions lead to lower photocapacitance signals. Many devices and CdS/CdTe samples have been provided to many groups including Larry Olsen of PNNL. Based on our current progress, no difficulties are anticipated in successfully completing the future targets outlined in the SOW. In addition to the tasks outlined above, two members of our team attended the 31st IEEE PVSC. Two oral presentations (preprints were sent to you earlier) were given. In addition, a poster was presented at the ICTMC conference and this paper has been accepted for publication in a journal. A loadlock system for the 16" X 16" substrates has been designed and constructed and is being tested. This activity is supported by another program from DOE-EERE and cost shared by NSC. Two scientists from GE Global Research were given a detailed tour of our facilities and a detailed presentation of our technology was made.
Venue	XXL-5-44205-02
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	03/28/2005

Post Date	03/22/2005
Title	QUARTERLY REPORT I (DECEMBER 2004 - FEBRUARY 2005) "CHARACTERIZATION AND ANALYSIS OF CIS AND CDTE CELLS" SUBCONTRACT XXL-5-44205-03
Link	(MS Word 39 KB)
Author	J. R. Sites
Description	CIGS grain boundaries; thins CIGS grading; secondary CIGS junction barriers; Alternative junctions with CIGS; Cdte Cell Operation, LBIC Studies, PL Studies
Venue
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	03/21/2005

Post Date	02/17/2005
Title	RESEARCH LEADING TO HIGH THROUGHPUT MANUFACTURING OF THIN-FILM CDTE PV MODULES
Link	(MS Word 85 KB)
Author	R. C. Powell
Description
Venue	RDJ-2-30630-20
Source	First Solar, Toledo, OH
Document Type	Quarterly Report (Word document)
Resource Date	02/15/2005

Post Date	04/18/2005
Title	RESEARCH LEADING TO HIGH THROUGHPUT MANUFACTURING OF THIN-FILM CDTE PV MODULES
Link	(MS Word 66 KB)
Author	R. C. Powell
Description	We completed the move from Technology Center facilities at Eckel Junction Road. All development personnel and equipment is now located at the Cedar Park facility. Nearly all of the equipment has been installed and is operational. We expect the move to improve the effectiveness of the Technology Development Team
Venue	subcontract rdj-2-30630-20
Source	First Solar, Toledo, OH
Document Type	Quarterly Report (Word document)
Resource Date	02/15/2005

Post Date	05/13/2005
Title	CENTER OF EXCELLENCE
Link	(PDF 757 KB) Download Acrobat Reader.
Authors	R. W. Birkmire, B. E. McCandless
Description	This report covers research conducted at the Institute of Energy Conversion (IEC) for the period from Dec. 04, 2004 to Jan. 03, 2005, under the subject subcontract. The report highlights progress and results obtained under Task 1 (CdTe-based solar cells).
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/14/2005
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(MS Word 2.5 MB)
Author	L. Olsen
Description
Venue
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	12/2004

Post Date	02/14/2005
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(MS Word 2.5 MB)
Author	L. Olsen
Description	Investigations of approaches for applying barrier coatings to CdTe cells from Dr. Sampath's group at Colorado State University (CSU) continued this past quarter. After reviewing our approach to coating the CSU cells, results of accelerated stress tests are given.
Venue	1st Quarterly Report - Phase I: September 1, 2004 — November 30, 2004
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	12/2004

Post Date	02/08/2005
Title	STUDIES OF BASIC ELECTRONIC PROPERTIES OF CDTE-BASED SOLAR CELLS & THEIR EVOLUTION DURING PROCESSING & STRESS
Link	(MS Word 1.9 MB)
Author	V. Kaydanov
Description	CdTe/CdS obtained in the past four months in the following areas: Studies of electroluminescence intensity and pattern in differently processes and treated cells Studies of deep electronic states (DES) with admittance spectroscopy and transient measurements; analysis and classification of the DES signatures Mapping photocurrent collection over a cell area with the high resolution near field scanning optical microscopy (NSOM)
Venue	NREL report
Source	Colorado School of Mines, Golden, CO
Document Type	Quarterly Report (Word document)
Resource Date	10/2004

Post Date	03/03/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 30 KB)
Author	J. R. Sites
Description
Venue	ADJ-1-30630-06
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	09/07/2004

Post Date	02/09/2005
Title	BARRIER COATINGS AND STABILITY OF THIN FILM SOLAR CELLS
Link	(MS Word 62 KB)
Author	L. Olsen
Description	Efforts this past quarter concentrated on developing approaches to applying barrier coatings to CdTe cells from Dr. Sampath's group at Colorado State University (CSU) and carrying out accelerated testing of the cells.
Venue	4th Quarterly Report - Phase II: June 1, 2004 — August 31, 2004
Source	Pacific Northwest National Lab (PNNL)
Document Type	Quarterly Report (Word document)
Resource Date	09/2004

Post Date	03/03/2005
Title	DEVELOPMENT OF A WIDE BAND GAP CELL FOR THIN FILM TANDEM SOLAR CELLS
Link	(PDF 856 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description
Venue	XAT-4-33624-01
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	09/2004

Post Date	05/10/2005
Title	NREL SUBCONTRACT # ADJ-1-30630-12
Link	(PDF 437 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description	a-Si and CdTe
Venue
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	08/23/2004

Post Date	02/09/2005
Title	RESEARCH LEADING TO HIGH THROUGHPUT MANUFACTURING OF THIN-FILM CDTE PV MODULES
Link	(MS Word 108 KB)
Author	R. C. Powell
Description	Progress
Venue	NREL report Q7 RDJ-2-30630-20
Source	First Solar, Toledo, OH
Document Type	Quarterly Report (Word document)
Resource Date	07/19/2004

Post Date	02/08/2005
Title	CSU PHASE III Q3
Link	(PDF 100 KB) Download Acrobat Reader.
Author	W. S. Sampath
Description	Significant advancements have been made in demonstrating a process for consistently fabricating stable CdTe PV. During the past few months, the optimum, baseline absorber/CdCl_z.
Venue	Subcontract No. ADJ-1-30630-07
Source	Colorado State University
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	06/22/2004

Post Date	02/09/2005
Title	CDTE-BASED SOLAR CELLS
Link	(PDF 45 KB) Download Acrobat Reader.
Author	B. E. McCandless
Description
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	06/21/2004

Post Date	02/09/2005
Title	SI AND DIAGNOSTICS
Link	(PDF 239 KB) Download Acrobat Reader.
Author	R. W. Birkmire
Description
Venue	ADJ-1-30630-12
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	06/03/2004

Post Date	02/08/2005
Title	STUDIES OF BASIC ELECTRONIC PROPERTIES OF CDTE-BASED SOLAR CELLS & THEIR EVOLUTION DURING PROCESSING & STRESS
Link	(MS Word 364 KB)
Authors	V. Kaydanov, et al.
Description	Previously we have reported some differences in the EL and Pl spectra obtained from the same small area of a cell, as well as some features of the spectra that supposedly could be attributed to Cu related defects [1, 2]. Here we present results of new comparative studies on differently processed cells: (a) cells intentionally doped non-uniformly with Cu and subjected to wet or dry treatments with CdCl2 of different purity; (b) prepared at CSU with and without Cu-doping.
Venue	NREL quarterly report
Source	Colorado School of Mines, Golden, CO
Document Type	Quarterly Report (Word document)
Resource Date	06/2004

Post Date	02/09/2005
Title	DEVELOPMENT OF A WIDE BAND GAP CELL FOR THIN FILM TANDEM SOLAR CELLS
Link	(PDF 700 KB) Download Acrobat Reader.
Author	N/A
Description	Much of the work this quarter continued to focus on the relative incorporation of S and Se during CuIn(SeS)₂ or Cu(InGa)(SeS)₂ deposition. In the previous quarterly report, we showed that the re was a reproducible difference between films grown with Cu-rich composition and those with Cu-poor composition. Films deposited with Cu/(In+Ga) > 1.1 preferentially incorporate S, while those with Cu/(In+Ga) < 0.9 preferentially incorporate Se. This is shown in Figure 1, which plots the relative S and Se incorporation in films, as measured by EDS, as a function of the S/(S+Se) ratio in the vapor, determined by the average effusion rate measured for each source during the run. For both the Cu-rich and Cu-poor cases, there is no correlation with Ga/(In+Ga) and data is included for CuIn(SeS)₂ films as well as Cu(InGa)(SeS)₂ with different Ga/(In+Ga). Post-deposition KCN etching, to remove a surface Cu_x (SeS)_y...
Venue	2nd Quarterly Report XAT-4-33624-01
Source	University of Delaware
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	05/05/2004

Post Date	02/08/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 35 KB)
Author	J. R. Sites
Description	Measurement and analysis.
Venue	NREL Q10 ADJ-1-30630-06
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	03/05/2004

Post Date	03/03/2005
Title	DEVICE PHYSICS OF THIN-FILM POLYCRYSTALLINE SOLAR CELLS
Link	(MS Word 35 KB)
Author	J. R. Sites
Description
Venue	ADJ-1-30630-06
Source	Colorado State University
Document Type	Quarterly Report (Word document)
Resource Date	03/05/2004

Post Date	02/09/2005
Title	HIGH-EFFICIENCY CADMIUM-TELLURIDE THIN-FILM SOLAR CELLS
Link	(PDF 320 KB) Download Acrobat Reader.
Author	A. Compaan
Description	The report describes our activities and progress in understanding of the effects of the back contact on device open-circuit voltage and efficiency. We propose a new structure for fabricating efficient CdTe/CdS solar cells (in the range of 13%) without Cu doping or post-metal heat treatments. Also, we describe the results of our study of synchrotron xray absorption fine structure (XAFS) aimed at understanding the role of diffused copper in CdCl₂ treated CdTe.
Venue	NDJ-1-30630-02 Phase 3/Quarter 2
Source	University of Toledo
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	03/2004

Post Date	02/10/2005
Title	ADVANCED PROCESSING OF CDTE- AND CUIN_XGA_1-XSE₂-
Link	(PDF 189 KB) Download Acrobat Reader.
Authors	C. S. Ferekides, D. Morel
Description	The focus areas include: (a) CdTe ? stability, novel back/front contacts, and the development of manufacturing friendly processes; (b) CIGS ? development of two-step non-co-evaporation technology.
Venue	NDJ-2-30630-18 Phase III/Quarter 1
Source	University of South Florida, Tampa
Document Type	Quarterly Report (Adobe Postscript file)
Resource Date	03/2004

Post Date	02/08/2005
Title	STUDIES OF BASIC ELECTRONIC PROPERTIES OF CDTE-BASED SOLAR CELLS & THEIR EVOLUTION DURING PROCESSING & STRESS
Link	(MS Word 747 KB)
Author	V. Kaydanov
Description	Our previous studies demonstrated high sensitivity of EL intensity and pattern to the CdTe cell processing and stressing (see, e.g., [1]). In particular, it was found that even a "gentle" stress can significantly effect measured EL whereas the J-V characterization detects only slight changes. EL imaging of a cell proved useful to reveal micro-nonuniformities in electronic properties and clarify mechanisms behind them. Deep states...
Venue	NREL quarterly
Source	Colorado School of Mines, Golden, CO
Document Type	Quarterly Report (Word document)
Resource Date	02/2004

Post Date	02/09/2005
Title	RESEARCH LEADING TO HIGH THROUGHPUT MANUFACTURING OF THIN-FILM CDTE PV MODULES
Link	(MS Word 784 KB)
Author	R. C. Powell
Description	Progress report.
Venue	NREL report Q5 RDJ-2-30630-20
Source	First Solar, Toledo, OH
Document Type	Quarterly Report (Word document)
Resource Date	01/15/2004

Post Date	01/18/2004
Title	RESEARCH LEADING TO HIGH THROUGHPUT MANUFACTURING OF THIN-FILM CDTE PV MODULES
Link	(MS Word 784 KB)
Author	R. C. Powell
Description	Reactor development, uniformity issues, stress testing, back contact improvement
Venue	First Solar: RDJ-2-30630-20; Q5 NREL Quarterly Report
Source	First Solar, Toledo, OH
Document Type	Quarterly Report (Word document)
Resource Date	01/15/2004

Post Date	02/09/2005
Title	CDTE SOLAR CELLS
Link	(PDF 1.7 MB