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Impurity And Back Contact Effects On Cdte Cds Thin Film Solar Cells
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Book Synopsis Impurity and Back Contact Effects on CdTe/CdS Thin Film Solar Cells by : Hehong Zhao
Download or read book Impurity and Back Contact Effects on CdTe/CdS Thin Film Solar Cells written by Hehong Zhao and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: CdTe/CdS thin film solar cells are the most promising cost-effective solar cells. The goal of this project is to improve the performance for CdS/CdTe devices by improving the open circuit voltage V[subscript]oc and current density J[subscript]sc. Efforts focused on increasing the V[subscript]oc, which include increasing the doping concentration by introducing Phosphorus and Antimony, finding and testing new back contact materials, and varying the ambient of CSS CdTe. In addition, the effect of Zn2SnO4 on the cells' performance was also studied. Electrical characterization of the thin films and completed devices were carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V), and Spectral Response (SR) measurements. Structural/chemical characterization was done by SEM, XRD and EDS analysis. The ambient of CSS CdTe affects the growth rate, the grain size and electronic properties of CdTe. The N2/O2 mixture with varied ratio (N2/O2=9/1, 7/3, 5/5 and 1/9) was used in this study. The cells' performance and the net carrier concentration were studied as a function of the N2/O2 ratio. The net carrier concentration increases with the increasing O2 concentration. The extrinsic impurities (P and Sb) were incorporated into CdTe layer. Phosphorus was directly introduced into CSS CdTe source. The Sb was incorporated into CdTe by a diffusion process. The effects of the annealing parameters, the excess Sb on CdTe surface, the CdCl2 treatment and the depth of Sb in CdTe were studied. Higher doping concentration up to 1016 cm−3 has been achieved, however, V[subscript]oc is still in the range of 830 mV.
Book Synopsis Fundamentals Of Solar Cells by : Alan Fahrenbruch
Download or read book Fundamentals Of Solar Cells written by Alan Fahrenbruch and published by Elsevier. This book was released on 2012-12-02 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Solar Cells: Photovoltaic Solar Energy Conversion provides an introduction to the fundamental physical principles of solar cells. It aims to promote the expansion of solar photovoltaics from relatively small and specialized use to a large-scale contribution to energy supply. The book begins with a review of basic concepts such as the source of energy, the role of photovoltaic conversion, the development of photovoltaic cells, and sequence of phenomena involved in solar power generation. This is followed by separate chapters on each of the processes that take place in solar cell. These include solar input; properties of semiconductors; recombination and the flow of photogenerated carriers; charge separation and the characteristics of junction barriers; and calculation of solar efficiency. Subsequent chapters deal with the operation of specific solar cell devices such as a single-crystal homojunction (Si); a single-crystal-heterojunction/buried-homojunction (AlGaAs/GaAs); and a polycrystalline, thin-film cell (CuxS/CdS). This book is intended for upper-level graduate students who have a reasonably good understanding of solid state physics and for scientists and engineers involved in research and development of solar cells.
Book Synopsis CdTe/CdS Thin Film Solar Cells Fabricated on Flexible Substrates by : Vasilios Palekis
Download or read book CdTe/CdS Thin Film Solar Cells Fabricated on Flexible Substrates written by Vasilios Palekis and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cadmium Telluride (CdTe) is a leading thin film photovoltaic (PV) material due to its near ideal bandgap of 1.45 eV and its high optical absorption coefficient. The typical CdTe thin film solar cell is of the superstrate configuration where a window layer (CdS), the absorber (CdTe) and a back contact are deposited onto glass coated with a transparent electrode. Substrate CdTe solar cells where the above listed films are deposited in reverse are not common. In this study substrate CdTe solar cells are fabricated on flexible foils. The properties of the Molybdenum back contact, Zinc Telluride (ZnTe) interlayer and CdTe absorber on the flexible foils were studied and characterized using X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Substrate curvature and film flaking was observed during the fabrication as a result of differences in thermal expansion coefficients between the substrate and the deposited films, and also due to impurity diffusion from the foil into the film stack. In order to overcome this problem diffusion barriers where used to eliminate contamination. Silicon dioxide (SiO2), silicon nitride (Si3N4) and molybdenum nitride (MoxNy) were used as such barriers. Electrical characterization of completed devices was carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V) and Spectral Response (SR) measurements. Roll-over was observed in the first quadrant of J-V curves indicating the existence of a back barrier due to a Schottky back contact. The formation of non-rectifying contact to p-CdTe thin-film is one of the major and critical challenges associated with the fabrication of efficient and stable solar cells. Several materials (ZnTe, Cu, Cu2Te, and Te) were studied as potential candidates for the formation of an effective back contact.
Book Synopsis Solar Cells and Modules by : Arvind Shah
Download or read book Solar Cells and Modules written by Arvind Shah and published by Springer Nature. This book was released on 2020-07-16 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a comprehensive introduction to the field of photovoltaic (PV) solar cells and modules. In thirteen chapters, it addresses a wide range of topics including the spectrum of light received by PV devices, the basic functioning of a solar cell, and the physical factors limiting the efficiency of solar cells. It places particular emphasis on crystalline silicon solar cells and modules, which constitute today more than 90 % of all modules sold worldwide. Describing in great detail both the manufacturing process and resulting module performance, the book also touches on the newest developments in this sector, such as Tunnel Oxide Passivated Contact (TOPCON) and heterojunction modules, while dedicating a major chapter to general questions of module design and fabrication. Overall, it presents the essential theoretical and practical concepts of PV solar cells and modules in an easy-to-understand manner and discusses current challenges facing the global research and development community.
Book Synopsis Thin Film Solar Cells by : Jef Poortmans
Download or read book Thin Film Solar Cells written by Jef Poortmans and published by John Wiley & Sons. This book was released on 2006-10-02 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin-film solar cells are either emerging or about to emerge from the research laboratory to become commercially available devices finding practical various applications. Currently no textbook outlining the basic theoretical background, methods of fabrication and applications currently exist. Thus, this book aims to present for the first time an in-depth overview of this topic covering a broad range of thin-film solar cell technologies including both organic and inorganic materials, presented in a systematic fashion, by the scientific leaders in the respective domains. It covers a broad range of related topics, from physical principles to design, fabrication, characterization, and applications of novel photovoltaic devices.
Book Synopsis Effects of Contact-based Non-uniformities in CdS/CdTe Thin-film Solar Cells by : Alan R. Davies
Download or read book Effects of Contact-based Non-uniformities in CdS/CdTe Thin-film Solar Cells written by Alan R. Davies and published by . This book was released on 2008 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Study of Deep Level Defects of N+-CdS/P-CdTe Solar Cells by : Poonam Rani Kharangarh
Download or read book Study of Deep Level Defects of N+-CdS/P-CdTe Solar Cells written by Poonam Rani Kharangarh and published by . This book was released on 2013 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among various photovoltaic materials, polycrystalline cadmium telluride thin film is now the most promising material, due to its low production cost excellent stability and reliability. Current-voltage and capacitance-voltage measurements of CdTe photovoltaic devices at different temperatures can provide valuable information about non-idealities in the n-p semiconductor junction. There are certain limitations which limit the efficiency of CdTe solar cells. There is no real distinction between defects and impurities in CdTe solar cells as both act as beneficial dopants or detrimental traps unlike Si where intentional shallow dopants and traps are distinctly different. Therefore, the role of defect states on CdTe solar cell performance, the effect of processing on defect states, and simple and effective characterization techniques must be investigated and identified. In this research the thin film n+-CdS/p-CdTe solar cells made with evaporated Cu as a primary back contact, are characterized by using the temperature dependence of the reverse bias diode current (J-V-T) to determine the energy levels of deep defects. The results of the J-V-T measurements on solar cells made at NJIT show that while modest amounts of Cu enhance cell performance, an excessive high temperature annealing step degrades device quality and reduces efficiency. This work addresses the error that can be introduced during defect energy level estimation if the temperature dependence of the carrier capture cross-section is neglected. Therefore, the location of traps is derived using a Shockley-Read-Hall recombination model with modified assumptions. A Cu-related deep level defect with activation energy of 0.57eV is observed for Cu evaporated back contact cells and an intrinsic defect with activation energy 0.89eV is found. Frequency dispersion in Capacitance-Voltage measurements confirms the presence of Cu-related deep level traps for cells with a Cu evaporated back contact, whereas no such defects are observed in carbon paste contact. The behavior is believed to be due to diffusion of excess Cu from the contact. It is further observed that majority carrier deep level traps (Cu-related or intrinsic) contribute differently to the degradation of electronic properties of the CdTe solar cells. A simple and effective characterization technique based on temperature dependent capacitance spectroscopy (TDCS) is used to identify majority carrier trapping defects in thin film n+-CdS/p-CdTe solar cell, made with evaporated Cu as a primary back contact. The distinct deep level traps, observed by TDCS seem to be due to the ionization of impurity centers located in the depletion region of n+-CdS/p-CdTe junction.
Book Synopsis Development of CdTe Thin Film Solar Cells on Flexible Foil Substrates by : Deidra Ranel Hodges
Download or read book Development of CdTe Thin Film Solar Cells on Flexible Foil Substrates written by Deidra Ranel Hodges and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Cadmium telluride (CdTe) is a leading thin film photovoltaic (PV) material due to its near ideal band gap of 1.45 eV, its high optical absorption coefficient and availability of various device fabrication methods. Superstrate CdTe solar cells fabricated on glass have to-date exhibited efficiencies of 16.5%. Work on substrate devices has been limited due to difficulties associated with the formation of an ohmic back contact with CdTe. The most promising approach used to-date is based on the use of an interlayer between the CdTe and a metal electrode, an approach that is believed to yield a pseudo-ohmic contact. This research investigates the use of ZnTe and Sb2Te3 as the interlayer, in the development of efficient back contacts. Excellent adhesion and minimum stress are also required of a CdTe thin film solar cell device on a flexible stainless steel (SS) foil substrate. Foil substrate curvature, flaking, delamination and adhesion as a result of compressive strain due to the coefficient of thermal expansion (CTE) mismatch between the flexible SS foil substrate and the solar cell films have been studied. A potential problem with the use of a SS foil as the substrate is the diffusion of iron (Fe), chromium (Cr) and other elemental impurities into the layers of the solar cell device structure during high temperature processing. A diffusion barrier limiting the out diffusion of these substrate elements is being investigated in this study. Silicon nitride (Si3N4) films deposited on SS foils are being investigated as the barrier layer, to reduce or inhibit the diffusion of substrate impurities into the solar cell. Thin film CdTe solar cells have been fabricated and characterized by AFM, XRD, SEM, ASTM D3359-08 tape test, current-voltage (I-V) and spectral measurements. My individual contributions to this work include the Molybdenum (Mo) development, the adhesion studies, the silicon nitride (Si3N4) barrier studies, and EDS and SEM lines measurements and analysis of substrate out-diffused impurities. The rest of my colleagues focused on the development of CdTe, CdS, ZnTe, the CdCl2 heat treatment, and other back contact interlayer materials.
Book Synopsis Study of Back Contact Formation on CdTe/CdS Thin Film Solar Cells by : Jian Tang
Download or read book Study of Back Contact Formation on CdTe/CdS Thin Film Solar Cells written by Jian Tang and published by . This book was released on 1998 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advanced Concepts in Photovoltaics by : Arthur J. Nozik
Download or read book Advanced Concepts in Photovoltaics written by Arthur J. Nozik and published by Royal Society of Chemistry. This book was released on 2014-07-10 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic systems enable the sun’s energy to be converted directly into electricity using semiconductor solar cells. The ultimate goal of photovoltaic research and development is to reduce the cost of solar power to reach or even become lower than the cost of electricity generated from fossil and nuclear fuels. The power conversion efficiency and the cost per unit area of the phototvoltaic system are critical factors that determine the cost of photovoltaic electricity. Until recently, the power conversion efficiency of single-junction photovoltaic cells has been limited to approximately 33% - the so-called Shockley-Queisser limit. This book presents the latest developments in photovoltaics which seek to either reach or surpass the Shockley-Queisser limit, and to lower the cell cost per unit area. Progress toward this ultimate goal is presented for the three generations of photovoltaic cells: the 1st generation based on crystalline silicon semiconductors; the 2nd generation based on thin film silicon, compound semiconductors, amorphous silicon, and various mesoscopic structures; and the 3rd generation based on the unique properties of nanoscale materials, new inorganic and organic photoconversion materials, highly efficient multi-junction cells with low cost solar concentration, and novel photovoltaic processes. The extent to which photovoltaic materials and processes can meet the expectations of efficient and cost effective solar energy conversion to electricity is discussed. Written by an international team of expert contributors, and with researchers in academia, national research laboratories, and industry in mind, this book is a comprehensive guide to recent progress in photovoltaics and essential for any library or laboratory in the field.
Book Synopsis Advances in Thin-Film Solar Cells by : I M Dharmadasa
Download or read book Advances in Thin-Film Solar Cells written by I M Dharmadasa and published by CRC Press. This book was released on 2012-09-17 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book concentrates on the latest developments in our understanding of solid-state device physics. The material presented is mainly experimental and based on CdTe thin-film solar cells. It extends these new findings to CIGS thin-film solar cells and presents a new device design based on graded bandgap multilayer solar cells. This design has been experimentally tested using the well-researched GaAs/AlGaAs system and initial devices have shown impressive device parameters. These devices are capable of absorbing all radiation (UV, visible, and infra-red) within the solar spectrum and combines "impact ionization" and "impurity photovoltaic" effects. The improved device understanding presented in this book should impact and guide future device design and low-cost thin-film solar panel manufacture.
Book Synopsis Advanced Processing of CdTe- and CuIn[subscript 1-x]Ga[subscript x]Se2-Based Solar Cells: Final Technical Report, 26 May 1998-22 December 2001 by : Don Louis Morel
Download or read book Advanced Processing of CdTe- and CuIn[subscript 1-x]Ga[subscript x]Se2-Based Solar Cells: Final Technical Report, 26 May 1998-22 December 2001 written by Don Louis Morel and published by DIANE Publishing. This book was released on 2003 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advanced Characterization Techniques for Thin Film Solar Cells by : Daniel Abou-Ras
Download or read book Advanced Characterization Techniques for Thin Film Solar Cells written by Daniel Abou-Ras and published by John Wiley & Sons. This book was released on 2016-07-13 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book focuses on advanced characterization methods for thin-film solar cells that have proven their relevance both for academic and corporate photovoltaic research and development. After an introduction to thin-film photovoltaics, highly experienced experts report on device and materials characterization methods such as electroluminescence analysis, capacitance spectroscopy, and various microscopy methods. In the final part of the book simulation techniques are presented which are used for ab-initio calculations of relevant semiconductors and for device simulations in 1D, 2D and 3D. Building on a proven concept, this new edition also covers thermography, transient optoelectronic methods, and absorption and photocurrent spectroscopy.
Book Synopsis Overcoming Degradation Mechanisms in CdTe Solar Cells: First Annual Report, August 1998--August 1999 by :
Download or read book Overcoming Degradation Mechanisms in CdTe Solar Cells: First Annual Report, August 1998--August 1999 written by and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have studied the importance of chemical processes for the stability of CdTe solar cells, in particular, diffusion in the ohmic contact/absorber junction regions. Both whole cells and test systems containing only the ohmic contact and the absorber are used. We found several experimental methods to be useable tools to follow the effects of impurity diffusion on the CdTe grain boundaries, grainbulk, and surface. In addition, we have explored alternative contacting schemes.; Our first year of activities led to the following tentative conclusions:; ? Grain boundaries in CdTe/CdS cells are NOT fully passivated and are expected to be electrically active. ; ? There appears to be fast ionic diffusion in the vicinity of the Cu/HgTe/graphite back-contact, possibly enhanced by grain boundarydiffusion. ; ? The macroscopic response to stress is different for cells with identical back-contact, but from different manufacturers. Different factors and/or different reactions to identical factors are possibly at work here.; Ni-P appears to be a promising back-contact material.
Book Synopsis Impact of Back-contact Materials on Performance and Stability of CdS/CdTe Solar Cells by : Samuel Demtsu
Download or read book Impact of Back-contact Materials on Performance and Stability of CdS/CdTe Solar Cells written by Samuel Demtsu and published by . This book was released on 2006 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thin Film Solar Cells by : Jef Poortmans
Download or read book Thin Film Solar Cells written by Jef Poortmans and published by John Wiley & Sons. This book was released on 2006-10-16 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin-film solar cells are either emerging or about to emerge from the research laboratory to become commercially available devices finding practical various applications. Currently no textbook outlining the basic theoretical background, methods of fabrication and applications currently exist. Thus, this book aims to present for the first time an in-depth overview of this topic covering a broad range of thin-film solar cell technologies including both organic and inorganic materials, presented in a systematic fashion, by the scientific leaders in the respective domains. It covers a broad range of related topics, from physical principles to design, fabrication, characterization, and applications of novel photovoltaic devices.
Book Synopsis Back Contact Effects on Junction Photoluminescence in CdTe/CdS Solar Cells by :
Download or read book Back Contact Effects on Junction Photoluminescence in CdTe/CdS Solar Cells written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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