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A Study Of Cadmium Telluride Solar Cell Architecture Optimization And Fabrication Using Highly Ordered Nano Dome Arrays
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Book Synopsis A Study of Cadmium Telluride Solar Cell Architecture Optimization and Fabrication Using Highly Ordered Nano-dome Arrays by : Shawn A. Waggoner
Download or read book A Study of Cadmium Telluride Solar Cell Architecture Optimization and Fabrication Using Highly Ordered Nano-dome Arrays written by Shawn A. Waggoner and published by . This book was released on 2014 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis High Efficiency Ultra Thin Cadmium Telluride (CdTe) Solar Cells by : Nowshad Amin
Download or read book High Efficiency Ultra Thin Cadmium Telluride (CdTe) Solar Cells written by Nowshad Amin and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin film cadmium telluride absorbers with cadmium sulphide hetero-junction partner are promising candidates for high efficiency low cost solutions of solar energy harvesting devices. These devices have band gaps well-suited for effective absorption of sunlight. Most importantly, the materials used in these devices can be deposited in a variety of industry-friendly ways, so that the cost associated with manufacturing is generally lower than other available technologies. Although poly-crystalline CdS has been found to be the best suited heterojunction partner for CdTe solar cell, the conventional polycrystalline CdS/CdTe cell has few issues that limit device performance. In order to overcome these problems, this study proposes the introduction of poly-CdS to amorphous oxygenated CdS (a-CdS: O) as window layer. The a-CdS: O window material has higher optical band gap (2.5-3.1 eV), better lattice match with CdTe absorber materials and reduced inter-diffusion tendency of CdS and CdTe layers. This book systematically demonstrates the conversion process of poly CdS to a-CdS: O and develops a strategy for the fabrication of suitable a-CdS: O layer to be applied in CdTe solar ce
Book Synopsis Improving Performance in Cadmium Telluride Solar Cells by : Geethika Kaushalya Liyanage
Download or read book Improving Performance in Cadmium Telluride Solar Cells written by Geethika Kaushalya Liyanage and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polycrystalline Cadmium Telluride has been developed to be one of the most commercially successful materials for photovoltaic module production with power conversion efficiencies over 21% for research cells to over 18% for module efficiencies. However, little is known about these record devices architecture or the processing methods. Following conventional understanding of a CdTe solar cell operation, researchers have put extensive efforts over the years to improve the CdTe device performance through improved material quality and diode quality. While this have gained some benefit, performance limiting factors to these devices remains unchanged. Deviating from conventional concepts, better understanding of the device physics is needed in order to further improve these devices. This dissertation focusses on identifying these loss mechanisms and setting guidelines to fabricating high efficiency CdTe devices through both experimental and numerical simulation. Experimental work discusses the details to construction and characterization of a CdTe deposition system and employing the new understanding of improving the CdTe device to achieve high performing CdTe devices. Here the traditional CdS window layer is replaced by a wide bandgap MgxZn1-xO to increase the photocurrent generation with better band alignment. With optimum deposition and processing conditions, work demonstrates a device with power conversion efficiency >16%. With a good front contact, performance of the device can be limited by the poor back contact. Expanding the understanding to front contact band alignment, characteristics of a back buffer layer suitable for CdTe back contact is also explored. Through 1D numerical simulation of the conduction and valence band offset, doping levels of the CdTe and back buffer layer material, this dissertation work sets the guideline to achieving CdTe device performance up to 25%.
Book Synopsis Polycrystalline Thin Film Cadmium Telluride Solar Cells Fabricated by Electrodeposition. Annual Technical Report, 20 March 1995--19 March 1996 by :
Download or read book Polycrystalline Thin Film Cadmium Telluride Solar Cells Fabricated by Electrodeposition. Annual Technical Report, 20 March 1995--19 March 1996 written by and published by . This book was released on 1997 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this project is to develop improved processes for fabricating CdTe/CdS polycrystalline thin-film solar cells. Researchers used electrodeposition to form CdTe; electrodeposition is a non-vacuum, low-cost technique that is attractive for economic, large-scale production. During the past year, research and development efforts focused on several steps that are most critical to the fabricating high-efficiency CdTe solar cells. These include the optimization of the CdTe electrodeposition process, the effect of pretreatment of CdS substrates, the post-deposition annealing of CdTe, and back-contact formation using Cu-doped ZnTe. Systematic investigations of these processing steps have led to a better understanding and improved performance of the CdTe-based cells. Researchers studied the structural properties of chemical-bath-deposited CdS thin films and their growth mechanisms by investigating CdS samples prepared at different deposition times; investigated the effect of CdCl2 treatment of CdS films on the photovoltaic performance of CdTe solar cells; studied Cu-doped ZnTe as a promising material for forming stable, low-resistance contacts to the p-type CdTe; and investigated the effect of CdTe and CdS thickness on the photovoltaic performance of the resulting cells. As a result of their systematic investigation and optimization of the processing conditions, researchers improved the efficiency of CdTe/CdS cells using ZnTe back-contact and electrodeposited CdTe. The best CdTe/CdS cell exhibited a V{sub oc} of 0.778 V, a J{sub sc} of 22.4 mA/cm2, a FF of 74%, and an efficiency of 12.9% (verified at NREL). In terms of individual parameters, researchers obtained a V{sub oc} over 0.8 V and a FF of 76% on other cells.
Book Synopsis Polycrystalline Thin Film Cadmium Telluride Solar Cells Fabricated by Electrodeposition by : J. U. Trefny
Download or read book Polycrystalline Thin Film Cadmium Telluride Solar Cells Fabricated by Electrodeposition written by J. U. Trefny and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this project is to develop improved processes for fabricating CdTe/CdS polycrystalline thin-film solar cells. Researchers used electrodeposition to form CdTe; electrodeposition is a non-vacuum, low-cost technique that is attractive for economic, large-scale production. During the past year, research and development efforts focused on several steps that are most critical to the fabricating high-efficiency CdTe solar cells. These include the optimization of the CdTe electrodeposition process, the effect of pretreatment of CdS substrates, the post-deposition annealing of CdTe, and back-contact formation using Cu-doped ZnTe. Systematic investigations of these processing steps have led to a better understanding and improved performances of the CdTe-based cells.
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 2018-09-05 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar energy conversion plays a very important role in the rapid introduction of renewable energy, which is essential to meet future energy demands without further polluting the environment, but current solar panels based on silicon are expensive due to the cost of raw materials and high energy consumption during production. The way forward is to move towards thin-film solar cells using alternative materials and low-cost manufacturing methods. The photovoltaic community is actively researching thin-film solar cells based on amorphous silicon, cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and dye-sensitised and organic materials. However, progress has been slow due to a lack of proper understanding of the physics behind these devices. This book concentrates on the latest developments and attempts to improve our understanding of solid-state device physics. The material presented is mainly experimental and based on CdTe thin-film solar cells. The author extends these new findings to CIGS thin-film solar cells and presents a new device design based on graded bandgap multi-layer 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 combine "impact ionisation" and "impurity photovoltaic" effects. The improved device understanding presented in this book should impact and guide future photovoltaic device development and low-cost thin-film solar panel manufacture. This new edition features an additional chapter besides exercises and their solutions, which will be useful for academics teaching in this field.
Book Synopsis Cadmium Telluride and Grain Boundaries: a Preliminary Study by : Michael Evan Liao
Download or read book Cadmium Telluride and Grain Boundaries: a Preliminary Study written by Michael Evan Liao and published by . This book was released on 2017 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: The efficacy of the CdCl2 treatment on polycrystalline CdTe-based solar cells was discovered over a quarter of a century ago; and yet, the exact mechanism of this treatment is still not fully understood to this day. In fact, the lack of understanding stems from a debate on the exact role of grain boundaries in CdCl2-treated CdTe solar cells. Some hypothesize that the CdCl2-treatment causes grain boundaries to become beneficial to solar cell performance while others disagree and claim that the treatment simply mitigates the harmful effects of grain boundaries via passivation. A future goal of this project is to determine which, if either, hypothesis is correct by direct wafer bonding single crystalline CdTe. Direct wafer bonding of single crystalline materials would create only one grain boundary at the bonded interface. This approach allows the orientation and surface chemistry of interfaces to be controlled in order to study the chemistry of grain boundaries methodically. However, before any direct wafer bonding can be done, a preliminary study of single crystalline CdTe is necessary. High-quality direct wafer bonding can only be achieved if the surfaces of each wafer satisfy certain requirements. Additionally, analyzing single crystalline CdTe materials prior to bonding is crucial in order to make any insightful connections between results found from direct bonding of single crystalline CdTe and what is observed in polycrystalline CdTe. First, the surface of an (001) CdTe layer epitaxially grown on an (001) InSb substrate is studied using atomic force microscopy. Stacking faults on the CdTe surface are observed and the thickness of the grown CdTe epilayer is calculated by considering the interplanar angles between the (001) and (111) crystallographic planes as well as the dimensions of the stacking faults. While the stacking faults will inhibit successful wafer bonding, the roughness of the regions outside the stacking faults is 0.9 nm, which is an acceptable roughness for direct wafer bonding. High resolution x-ray diffraction is used to study the strain of the CdTe epilayer at the epilayer-substrate interface by generating reciprocal space maps of the (004), (115), and (335) crystallographic planes. It is found that CdTe grown on an (001) InSb substrate at a low growth temperature exhibits nearly 0% relaxation. As a result, the in-plane lattice parameter of the CdTe layer is maximally strained to match the smaller lattice parameter of the InSb substrate. Consequently, the CdTe lattice is tetragonally strained normal to the substrate surface, which causes the out-of-plane lattice parameter of CdTe to be larger than its intrinsic value. Lastly, a CdCl2-treated CdTe-CdS (p-type CdTe on n-type CdS) solar cell structure is simulated using a semiconductor-heterojunction simulation program. In literature, it has been reported that chlorine atoms from the treatment segregate along grain boundaries in polycrystalline CdTe and cause the formation of local p-n junctions by inverting the grain boundaries to n-type. The simulated structure includes one grain and 2 grain boundaries. The grain/bulk CdTe material is p-type while the grain boundaries are made to be n-type with varying doping concentrations. Both the conduction band and valence band energy exhibit downward sloping from the CdTe surface to the CdTe-CdS interface. This structure assumes that the grain boundaries are parallel to the CdTe-CdS interface. While these simulations do not prove the existence of the local type-inversion hypothesis, they do entertain a novel possibility for future devices fabrication methods.
Book Synopsis Studies on Optimizing Cadmium Telluride Solar Cells Through Thickness Reduction and the Addition of a Nickel Oxide Electron-blocking Layer by : Shawn Waggoner
Download or read book Studies on Optimizing Cadmium Telluride Solar Cells Through Thickness Reduction and the Addition of a Nickel Oxide Electron-blocking Layer written by Shawn Waggoner and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cadmium Telluride (CdTe) solar cells are the current leader in thin film photovoltaic technologies: with record device efficiencies comparable to any other thin film photovoltaic, and a lower cost per watt-peak than any other industrial photovoltaic. Yet device efficiency and cost must be further improved to continue making these devices economically competitive. This thesis discusses cost reduction of CdTe solar cells by creating ultrathin ( 1 m thick) CdTe absorber layers through Magnetron Sputter Deposition. Previous research on these devices has demonstrated excellent stability, but significantly reduced efficiency when compared to CdTe devices with thicker (typically 3 m thick) absorber layers. To avoid this efficiency reduction, research is conducted on adding a
Book Synopsis Polycrystalline Thin-Film Cadmium Telluride Solar Cells Fabricated by Electrodeposition: Final Technical Report, 20 March 1995-15 June 1998 by :
Download or read book Polycrystalline Thin-Film Cadmium Telluride Solar Cells Fabricated by Electrodeposition: Final Technical Report, 20 March 1995-15 June 1998 written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes work performed by the Colorado School of Mines Department of Physics under this subcontract. Based on the studies conducted, researchers increased the efficiency of the cells with electrodeposited CdTe and CBD CdS by 3% on average. The improvement came from 1) optimization of CdS initial thickness taking into account CdS consumption of CdTe during the CdTe/CdSpost-deposition treatment; optimization of CdS post-deposition treatment with CdCl2 aimed at prevention of Te diffusion into CdS and improvement of the CdS film morphology and electronic properties. That led to a considerable increase in short circuit current, by 13% on average. 2) Optimization of CdTe thickness and post-deposition treatment which led to a significant increase in Voc, by approx.70 mV. The highest Voc obtained exceeded 800 mV. 3. Development of a ZnTe:Cu/Metal back contact processing procedure that included selection of optimal Cu content, deposition regime and post-deposition treatment conditions. The cell stability was measured on exposure to accelerated stress conditions. Preliminary studies of some new approaches to improvement of CdS/CdTe structure were conducted.
Book Synopsis High Efficiency Cadmium Telluride and Zinc Telluride Based Thin-film Solar Cells by :
Download or read book High Efficiency Cadmium Telluride and Zinc Telluride Based Thin-film Solar Cells written by and published by . This book was released on 1992 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes work to improve the basic understanding of CdTe and ZnTe alloys by growing and characterizing these films along with cell fabrication. The major objective was to develop wide-band-gap (1.6--1.8 eV) material for the top cell, along with compatible window material and transparent ohmic contacts, so that a cascade cell design can be optimized. Front-wall solar cells were fabricated with a glass/SnO2/CdS window, where the CdS film is thin to maximize transmission and current. Wide-band-gap absorber films (E{sub g} = 1.75 eV) were grown by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) techniques, which provided excellent control for tailoring the film composition and properties. CdZnTe films were grown by both MBE and MOCVD. All the as-grown films were characterized by several techniques (surface photovoltage spectroscopy, Auger electron spectroscopy (AES), and x-ray photoelectron spectroscopy (XPS)) for composition, bulk uniformity, thickness, and film and interface quality. Front-wall-type solar cells were fabricated in collaboration with Ametek Materials Research Laboratory using CdTe and CdZnTe polycrystalline absorber films. The effects of processing on ternary film were studied by AES and XPS coupled with capacitance voltage and current voltage measurements as a function of temperature. Bias-dependent spectral response and electrical measurements were used to test some models in order to identify and quantify dominant loss mechanisms.
Book Synopsis Polycrystalline Thin-film Cadmium Telluride Solar Cells Fabricated by Electrodeposition. Annual Technical Report by :
Download or read book Polycrystalline Thin-film Cadmium Telluride Solar Cells Fabricated by Electrodeposition. Annual Technical Report written by and published by . This book was released on 1998 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past year, Colorado School of Mines (CSM) researchers performed systematic studies of the growth and properties of electrodeposition CdS and back-contact formation using Cu-doped ZnTe, with an emphasis on low Cu concentrations. CSM also started to explore the stability of its ZnTe-Cu contacted CdTe solar cells. Researchers investigated the electrodeposition of CdS and its application in fabricating CdTe/CdS solar cells. The experimental conditions they explored in this study were pH from 2.0 to 3.0; temperatures of 80 and 90 C; CdCl2 concentration of 0.2 M; deposition potential from -550 to -600 mV vs. Ag/AgCl electrode; [Na2S2O4] concentration between 0.005 and 0.05 M. The deposition rate increases with increase of the thiosulfate concentration and decrease of solution pH. Researchers also extended their previous research of ZnTe:Cu films by investigating films doped with low Cu concentrations (
Book Synopsis Next Generation Multilayer Graded Bandgap Solar Cells by : A. A. Ojo
Download or read book Next Generation Multilayer Graded Bandgap Solar Cells written by A. A. Ojo and published by Springer. This book was released on 2018-08-16 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will guide Photovoltaics researchers in a new way of thinking about harvesting light energy from all wavelengths of the solar spectrum. It closes the gap between general solar cells books and photovoltaics journal articles, by focusing on the latest developments in our understanding of solid-state device physics. The material presented is experimental and based on II-VI thin-film materials, mainly CdTe-based solar cells. The authors describe the use of new device design, based on multilayer graded bandgap configuration, using CdTe-based solar cells. The authors also explain how the photo-generated currents can be enhanced using multi-step charge carrier production. The possibility of fabricating these devices using low-cost and scalable electroplating is demonstrated. The value of electroplating for large area electronic devices such as PV solar panels, display devices and nano-technology devices are also demonstrated. By enabling new understanding of the engineering of electroplated semiconductor materials and providing an overview of the semiconductor physics and technology, this practical book is ideal to guide researchers, engineers, and manufacturers on future solar cell device designs and fabrications. Discusses in detail the processes of growths, treatments, solar cell device fabrication and solid state physics, improving readers’ understanding of fundamental solid state physics; Enables future improvements in CdTe-based device efficiency; Explains the significance of defects in deposited semiconductor materials and interfaces that affect the material properties and resulting device performance.
Book Synopsis Polycrystalline Thin-film Cadmium Telluride Solar Cells Fabricated by Electrodeposition by : John U. Trefny
Download or read book Polycrystalline Thin-film Cadmium Telluride Solar Cells Fabricated by Electrodeposition written by John U. Trefny and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past year, Colorado School of Mines (CSM) researchers performed systematic studies of the growth and properties of electrodeposition CdS and back-contact formation using Cu-doped ZnTe, with an emphasis on low Cu concentrations. CSM also started to explore the stability of its ZnTe-Cu contacted CdTe solar cells. Researchers investigated the electrodeposition of CdS and its application in fabricating CdTe/CdS solar cells. The experimental conditions they explored in this study were pH from 2.0 to 3.0; temperatures of 80 and 90 deg. C; CdCl2 concentration of 0.2 M; deposition potential from -550 to -600 mV vs. Ag/AgCl electrode; [Na2S2O4] concentration between 0.005 and 0.05 M. The deposition rate increases with increase of the thiosulfate concentration and decrease of solution pH. Researchers also extended their previous research of ZnTe:Cu films by investigating films doped with low Cu concentrations (
Book Synopsis Thin Film Cadmium Telluride Solar Cells. Final Technical Report, July 1, 1979-August 31, 1980 by :
Download or read book Thin Film Cadmium Telluride Solar Cells. Final Technical Report, July 1, 1979-August 31, 1980 written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Efforts during this program have been directed to the construction of apparatus for the chemical vapor deposition of cadmium telluride films, the selection and preparation of substrates, the deposition and characterization of cadmium telluride films, and the fabrication and characterization of solar cells. Cadmium telluride films have been deposited on a number of substrates by the direct combination of cadmium and tellurium on the substrate surface at 500°C or higher at rates of up to 0.6 .mu.m/min. The structural, crystallographic, and electrical properties of cadmium telluride films deposited over a wide range of conditions have been evaluated. A series of doping experiments have been carried out using iodine and indium as the n-type dopant, and phosphorus, arsenic, and antimony as the p-type dopant. Low resistivity films have not been produced thus far. In/W/graphite substrates have been used for the deposition of n-type films with an ohmic interface. However, no suitable substrates have been found to form an ohmic interface with p-type films. Solar cells prepared from these films exhibit relatively good short-circuit current density, up to 15 mA/cm2, but their conversion efficiencies are severely limited by the high series resistance of the devices. It is believed that low resistivity cadmium telluride films can be prepared by optimizing the deposition conditions. In parallel with the search of substrates with low interface resistance, back wall cells, such as p-CdTe/n-CdS/ITO/glass(substrate), should be investigated.
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 Nanostructured Extremely Thin Absorber (ETA) Hybrid Solar Cell Fabrication, Optimization, and Characterization by : Darcy Erin Lambert
Download or read book Nanostructured Extremely Thin Absorber (ETA) Hybrid Solar Cell Fabrication, Optimization, and Characterization written by Darcy Erin Lambert and published by . This book was released on 2011 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Traditional sources of electrical energy are finite and can produce significant pollution. Solar cells produce clean energy from incident sunlight, and will be an important part of our energy future. A new nanostructured extremely thin absorber solar cell with 0.98% power conversion efficiency and maximum external quantum efficiency of 61% at 650 nm has been fabricated and characterized. This solar cell is composed of a fluorine-doped tin oxide base layer, n-type aluminum doped zinc oxide nanowires, a cadmium selenide absorber layer, poly(3-hexylthiophene) as a p-type layer, and thermally evaporated gold as a back contact. Zinc oxide nanowire electrodeposition has been investigated for different electrical environments, and the role of a zinc oxide thin film layer has been established. Cadmium selenide nanoparticles have been produced and optimized in-house and compared to commercially produced nanoparticles. Argon plasma cleaning has been investigated as a method to improve electronic behavior at cadmium selenide interfaces. The thermal anneal process for cadmium selenide nanoparticles has been studied, and a laser anneal process has been investigated. It has been found that the most efficient solar cells in this study are produced with a zinc oxide thin film, zinc oxide nanowires grown under constant -1V bias between the substrate material and the anode, cadmium selenide nanoparticles purchased commercially and annealed for 24 hours in the presence of cadmium chloride, and high molecular weight poly(3-hexylthiophene) spin-coated in a nitrogen environment.
Book Synopsis High Efficiency Cadmium Telluride and Zinc Telluride Based Thin-film Solar Cells. Annual Subcontract Report, 1 March 1990--28 February 1992 by :
Download or read book High Efficiency Cadmium Telluride and Zinc Telluride Based Thin-film Solar Cells. Annual Subcontract Report, 1 March 1990--28 February 1992 written by and published by . This book was released on 1992 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes work to improve the basic understanding of CdTe and ZnTe alloys by growing and characterizing these films along with cell fabrication. The major objective was to develop wide-band-gap (1.6--1.8 eV) material for the top cell, along with compatible window material and transparent ohmic contacts, so that a cascade cell design can be optimized. Front-wall solar cells were fabricated with a glass/SnO2/CdS window, where the CdS film is thin to maximize transmission and current. Wide-band-gap absorber films (E{sub g} = 1.75 eV) were grown by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) techniques, which provided excellent control for tailoring the film composition and properties. CdZnTe films were grown by both MBE and MOCVD. All the as-grown films were characterized by several techniques (surface photovoltage spectroscopy, Auger electron spectroscopy (AES), and x-ray photoelectron spectroscopy (XPS)) for composition, bulk uniformity, thickness, and film and interface quality. Front-wall-type solar cells were fabricated in collaboration with Ametek Materials Research Laboratory using CdTe and CdZnTe polycrystalline absorber films. The effects of processing on ternary film were studied by AES and XPS coupled with capacitance voltage and current voltage measurements as a function of temperature. Bias-dependent spectral response and electrical measurements were used to test some models in order to identify and quantify dominant loss mechanisms.
