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:

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.

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.

Download or read book CdTe and Related Compounds Physics Defects Hetero and Nano structures Crystal Growth Surfaces and Applications written by and published by Elsevier. This book was released on 2009-11-11 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Almost thirty years after the remarkable monograph of K. Zanio and the numerous conferences and articles dedicated since that time to CdTe and CdZnTe, after all the significant progresses in that field and the increasing interest in these materials for several extremely attractive industrial applications, such as nuclear detectors and solar cells, the edition of a new enriched and updated monograph dedicated to these two very topical II-VI semiconductor compounds, covering all their most prominent, modern and fundamental aspects, seemed very relevant and useful. - Detailed coverage of the main topics associated with the very topical II-VI semiconductor compound CdTe and its alloy CZT - Review of the CdTe recent developments - Fundamental background of many topics clearly introduced and exposed

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.

Download or read book Coatings and Thin Film Technologies written by Jaime Andres Perez Taborda and published by BoD – Books on Demand. This book was released on 2019-01-03 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of coatings and thin-film technologies is rapidly advancing to keep up with new uses for semiconductor, optical, tribological, thermoelectric, solar, security, and smart sensing applications, among others. In this sense, thin-film coatings and structures are increasingly sophisticated with more specific properties, new geometries, large areas, the use of heterogeneous materials and flexible and rigid coating substrates to produce thin-film structures with improved performance and properties in response to new challenges that the industry presents. This book aims to provide the reader with a complete overview of the current state of applications and developments in thin-film technology, discussing applications, health and safety in thin films, and presenting reviews and experimental results of recognized experts in the area of coatings and thin-film technologies.

Download or read book Stability Studies of CdTe CdS Thin Film Solar Cells written by Bhaskar Reddy Tetali and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Diffusion of Cui+ ions from the back contact along CdTe grain boundaries had been previously reported [16]. An increase in light/dark J-V crossover and bulk Rs with stress time and temperature was observed. A slow degradation component attributed to Cu-related substitutional defect [23] formation/diffusion to the junction and CdS is proposed. This should compensate the CdS over time and increase its photoconductivity/resistivity. An improvement in the current collection and FF within 100 hours of LS was observed. This is possibly due to the enhancement of Cui+ diffusion into the junction and CdS during LS as previously reported [16]. A reduction in light/dark J-V crossover was observed, possibly due to an increase in CdS doping and reduction in the CdS/SnO2 front contact barrier. However, a fast decrease in Voc and increase in recombination current was also observed in the first 1000 hours of LS.

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.

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.

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.

Download or read book Analysis of Cu Difusion in ZnTe Based Contacts for Thin Film CdS CdTe Solar Cells written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ohmic contacts to thin-film CdS/CdTe photovoltaic devices have been formed using a two-layer contact interface of undoped ZnTe (ZnTe) and Cu-doped ZnTe (ZnTe:Cu), followed by Ni or Ti as an outer metallization. Secondary ion mass spectroscopy (SIMS) is used to study Cu diffusion within this back-contact structure, and also, to monitor Cu diffusion from the contact into the CdTe. When Nimetallization is used, the ZnTe:Cu layer becomes increasingly depleted of Cu, and Ni diffusion into the ZnTe:Cu increases as the contact deposition temperature increases from 100 deg. C to 300 deg. C. Cu depletion is not observed when Ni is replaced with Ti. Diffusion of Cu from the ZnTe:Cu layer into the ZnTe layer also increases with contact deposition temperature, and produces a buildup of Cuat the ZnTe/CdTe interface. High-mass resolution SIMS indicates that, although Cu levels in the CdTe remain low, Cu diffusion from the contact proceeds into the CdTe layer and toward the CdTe/CdS junction region.

Download or read book Study of Molybdenum Oxide as a Back Contact Buffer for Thin Film N CdS p CdTe Solar Cells written by Hao Lin and published by . This book was released on 2012 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Back contact improvement is one of the most crucial issues for the realization of highly efficient n-CdS/p-CdTe solar cells. Conventional methods for making a sufficiently ohmic contact to p-CdTe usually involve a solution etching process and a Cu doping process, which are known to negatively affect the device reliability. To resolve this problem, a low-resistance back contact for n-CdS/p-CdTe solar cells has been developed, which utilizes a vapor-deposited transition metal oxide (TMO) thin film as the back contact buffer layer between p-CdTe and the back electrode. The usefulness of TMO is attributed to its unusually high work function which is needed to match that of p-type CdTe in producing a contact of low resistance. As one major representative of TMO materials, molybdenum oxide (MoOx) has been investigated as a novel buffer in this thesis. First, the processes for making low resistance contact with MoOx buffer are explored. To achieve a good ohmic contact to p-CdTe, a water rinse step is necessary in order to remove surface residues from the CdTe surface prior to MoOx deposition. In addition, different methods for depositing MoOx films have been examined, including thermal evaporation and DC sputtering methods. With MoOx as the high work function buffer, various metals can be used as the electrode to realize an ohmic back contact to p-CdTe. Other advantages of the MoOx buffer include dry application by vacuum deposition, and thus it is particularly suitable for the fabrication of ultra-thin CdTe solar cells without introducing additional shorting defects. Second, the mechanism by which MoOx improves the performance of the back contact is studied through the investigation of Ni/CdTe and Ni/MoOx/CdTe interfaces with x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Contrasting differences in the interface formation and core level structure were observed, indicating that the presence of a thin MoOx inter-layer was effective in reducing the unfavorable reaction between Ni and the native tellurium oxide at the CdTe surface. Finally, the stability of CdTe cells with MoOx buffer is studied. MoOx is found to effectively stabilize the device performance, especially the open-circuit voltage (Voc) of the CdTe solar cell during thermal stress tests. The cell with a Ni-only electrode rapidly degrades due to Ni diffusing into the CdTe film and Ni abstracting Te from CdTe. With the addition of a layer of MoOx as the buffer layer, the diffusion of Ni and the reaction between Ni and CdTe are alleviated, resulting in significantly improved device stability. To summarize, an efficient and stable back contact has been developed through the application of a high work function MoOx as the buffer for p-CdTe. As a result, n-CdS/p-CdTe solar cells with improved efficiency and stability have been realized"--Page viii-ix.

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:

Download or read book Properties of Semiconductor Alloys written by Sadao Adachi and published by John Wiley & Sons. This book was released on 2009-03-12 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main purpose of this book is to provide a comprehensive treatment of the materials aspects of group-IV, III−V and II−VI semiconductor alloys used in various electronic and optoelectronic devices. The topics covered in this book include the structural, thermal, mechanical, lattice vibronic, electronic, optical and carrier transport properties of such semiconductor alloys. The book reviews not only commonly known alloys (SiGe, AlGaAs, GaInPAs, and ZnCdTe) but also new alloys, such as dilute-carbon alloys (CSiGe, CSiSn, etc.), III−N alloys, dilute-nitride alloys (GaNAs and GaInNAs) and Mg- or Be-based II−VI semiconductor alloys. Finally there is an extensive bibliography included for those who wish to find additional information as well as tabulated values and graphical information on the properties of semiconductor alloys.

Download or read book Semiconductor Photovoltaic Cells written by Chunfu Zhang and published by Springer Nature. This book was released on 2021-02-25 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores the scientific basis of the photovoltaic effect, solar cell operation, various types of solar cells, and the main process used in their manufacture. It addresses a range of topics, including the production of solar silicon; silicon-based solar cells and modules; the choice of semiconductor materials and their production-relevant costs and performance; device structures, processing, and manufacturing options for the three major thin-film PV technologies; high-performance approaches for multi-junction, concentrator, and space applications; and new types of organic polymer and dye-sensitized solar cells. The book also presents a concept for overcoming the efficiency limit of today’s solar cells. Accessible for beginners, while also providing detailed information on the physics and technology for experts, the book is a valuable resource for researchers, engineers, and graduate students in fields such as physics, materials, energy, electrical and electronic engineering and microelectronics.

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.

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.