Download or read book Investigation of Polycrystalline Thin film CuInSe2 Solar Cells Based on ZnSe and ZnO Buffer Layers written by Larry C. Olsen and published by . This book was released on 1996 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Polycrystalline Thin film CuInSe2 Solar Cells Based on ZnSe and ZnO Buffer Layers Final Report February 16 1992 November 15 1995 written by and published by . This book was released on 1996 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: The major objective of this program was to determine the potential of ZnSe and ZnO buffer layers in solar cells based on CuInSe2 and related alloys. Experimental studies were carried out with CIS and CIGSS substrates. ZnSe films were deposited by a CVD process which involved the reaction of a zinc adduct and H2Se. Al/ZnSe/CIS test cells were used for process development. Test cell performance aided in determining the optimum thickness for ZnSe buffer layers to be in the range of 150 Å to 200 Å for Siemens CIS material, and between 80 Å and 120 Å for the graded absorber material. If the buffer layers exceeded these values significantly, the short-circuit current would be reduced to zero. The best efficiency achieved for a ZnSe/CIS cell was an active area value of 9.2%. In general, deposition of a conductive ZnO film on top of a ZnSe/CIS structure resulted in either shunted or inflected I-V characteristics. Two approaches were investigated for depositing ZnO buffer layers, namely, chemical bath deposition and CVD. CVD ZnO buffer layers are grown by reacting a zinc adduct with tetrahydrofuran. Best results were obtained for ZnO buffer layers grown with a substrate temperature ca. 225--250 C. These studies concentrated on Siemens graded absorber material (CIGSS). ZnO/CIS solar cells have been fabricated by first depositing a ZnO buffer layer, followed by deposition of a low resistivity ZnO top contact layer and an Al/Ag collector grid. Several cells were fabricated with an area of 0.44 cm2 that have total area efficiencies greater than 11%. To date, the best performing ZnO/CIS cell had a total area efficiency of 11.3%. In general, the authors find that ZnO buffer layers should have a resistivity> 1,000 ohm-cm and have a thickness from 200 Å to 600 Å. CIS cells studies with ZnO buffer layers grown by CBD also show promise. Finally, simulation studies were carried out using the 1-D code, PC-1D.

Download or read book Investigation of Polycrystalline Thin film CuInSe sub 2 Solar Cells Based on ZnSe and ZnO Buffer Layers Final Report February 16 1992 November 15 1995 written by and published by . This book was released on 1996 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: The major objective of this program was to determine the potential of ZnSe and ZnO buffer layers in solar cells based on CuInSe2 and related alloys. Experimental studies were carried out with CIS and CIGSS substrates. ZnSe films were deposited by a CVD process which involved the reaction of a zinc adduct and H2Se. Al/ZnSe/CIS test cells were used for process development. Test cell performance aided in determining the optimum thickness for ZnSe buffer layers to be in the range of 150 +!to 200 +!for Siemens CIS material, and between 80 +!and 120 +!for the graded absorber material. If the buffer layers exceeded these values significantly, the short-circuit current would be reduced to zero. The best efficiency achieved for a ZnSe/CIS cell was an active area value of 9.2%. In general, deposition of a conductive ZnO film on top of a ZnSe/CIS structure resulted in either shunted or inflected I-V characteristics. Two approaches were investigated for depositing ZnO buffer layers, namely, chemical bath deposition and CVD. CVD ZnO buffer layers are grown by reacting a zinc adduct with tetrahydrofuran. Best results were obtained for ZnO buffer layers grown with a substrate temperature ca. 225--250 C. These studies concentrated on Siemens graded absorber material (CIGSS). ZnO/CIS solar cells have been fabricated by first depositing a ZnO buffer layer, followed by deposition of a low resistivity ZnO top contact layer and an Al/Ag collector grid. Several cells were fabricated with an area of 0.44 cm2 that have total area efficiencies greater than 11%. To date, the best performing ZnO/CIS cell had a total area efficiency of 11.3%. In general, the authors find that ZnO buffer layers should have a resistivity> 1,000 ohm-cm and have a thickness from 200 +!to 600 +! CIS cells studies with ZnO buffer layers grown by CBD also show promise. Finally, simulation studies were carried out using the 1-D code, PC-1D.

Download or read book Nanoscale investigation of potential distribution in operating Cu In Ga Se2 thin film solar cells written by Zhenhao Zhang and published by KIT Scientific Publishing. This book was released on 2014-10-16 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: The distribution of the electrostatic potential in and between the materials in Cu(In,Ga)Se2 thin-film solar cells has a major impact on their superior performance. This thesis reported on the nanoscale imaging of the electrostatic potential on untreated cross sections of operating Cu(In,Ga)Se2 solar cells using Kelvin probe force microscopy.

Download or read book Investigation of Polycrystalline Thin Film CuInSe2 Solar Cells Based on ZnSe Windows Annual Subcontract Report 15 February 1993 14 February 1994 written by and published by . This book was released on 1995 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report concerns studies of CIS solar cells based on ZnSe window layers. ZnSe/CIS devices are fabricated by growing ZnSe films by MOCVD onto Siemens CIS and graded absorber substrates. ZnSe films are grown by reacting H2Se with a zinc adduct. ZnSe/CIS heterojunctions have been studied by depositing transparent aluminum contacts onto ZnSe. These studies indicate that ZnSe/CIS solar cells can be fabricated with an efficiency greater than 14%. Open circuit voltages are typically larger than 500 mV and the optimum range of ZnSe film thickness for maximum efficiency is between 100 Å and 250 Å. Photocurrents are significantly reduced as the film thickness exceeds 250 Å. Photoluminescence spectroscopy has been utilized to characterize the physical nature of CIS substrate surfaces, and ZnSe-CIS interfaces. These studies indicate that a segregated phase(s) exists at the surface of as received Siemens substrates. Additionally, it is determined that the segregated phase(s) still exist after the ZnSe growth process. To date, sputtered ZnO top contact layers have caused degradation of the photovoltaic properties of the ZnSe/CIS structure. Investigations of the effects of MOCVD grown ZnO upon ZnSe/CIS structures will soon be initiated. To establish the feasibility of ZnSe as a window layer, cells have been fabricated by incorporating a protective layer of CdS between the ZnSe and ZnO. A total area efficiency of 11% was obtained with such a structure.

Download or read book Alternative Buffer Layer Development in Cu In Ga Se2 Thin Film Solar Cells written by Peipei Xin and published by . This book was released on 2017 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cu(In,Ga)Se2-based thin film solar cells are considered to be one of the most promising photovoltaic technologies. Cu(In,Ga)Se2 (CIGS) solar devices have the potential advantage of low-cost, fast fabrication by using semiconductor layers of only a few micrometers thick and high efficiency photovoltaics have been reported at both the cell and the module levels. CdS via chemical bath deposition (CBD) has been the most widely used buffer option to form the critical junction in CIGS-based thin film photovoltaic devices. However, the disadvantages of CdS can’t be ignored - regulations on cadmium usage are getting stricter primarily due to its toxicity and environmental impacts, and the proper handling of the large amount of toxic chemical bath waste is a massive and expensive task. ☐ This dissertation is devoted to the development of Cd-free alternative buffer layers in CIGS-based thin film solar cells. Based on the considerations of buffer layer selection criteria and extensive literature review, Zn-compound buffer materials are chosen as the primary investigation candidates. Radio frequency magnetron sputtering is the preferred buffer deposition approach since it’s a clean and more controllable technique compared to CBD, and is readily scaled to large area manufacturing. ☐ First, a comprehensive study of the ZnSe1-xOx compound prepared by reactive sputtering was completed. As the oxygen content in the reactive sputtering gas increased, ZnSe1-xOx crystallinity and bandgap decreased. It’s observed that oxygen miscibility in ZnSe was low and a secondary phase formed when the O2 / (O2 + Ar) ratio in the sputtering gas exceeded 2%. Two approaches were proposed to optimize the band alignment between the CIGS and buffer layer. One method focused on the bandgap engineering of the absorber, the other focused on the band structure modification of the buffer. As a result, improved current of the solar cell was achieved although a carrier transport barrier at the junction interface still limited the device performance. ☐ Second, an investigation of Zn(S,O) buffer layers was completed. Zn(S,O) films were sputtered in Ar using a ZnO0.7S0.3 compound target. Zn(S,O) films had the composition close to the target with S / (S+O) ratio around 0.3. Zn(S,O) films showed the wurtzite structure with the bandgap about 3.2eV. The champion Cu(In,Ga)Se2 / Zn(S,O) cell had 12.5% efficiency and an (Ag,Cu)(In,Ga)Se2 / Zn(S,O) cell achieved 13.2% efficiency. Detailed device analysis was used to study the Cu(In,Ga)Se2 and (Ag,Cu)(In,Ga)Se2 absorbers, the influence of absorber surface treatments, the effects of device treatments, the sputtering damage and the Na concentration in the absorber. ☐ Finally alternative buffer layer development was applied to an innovative superstrate CIGS configuration. The superstrate structure has potential benefits of improved window layer properties, cost reduction, and the possibility to implement back reflector engineering techniques. The application of three buffer layer options – CdS, ZnO and ZnSe was studied and limitations of each were characterized. The best device achieved 8.6% efficiency with a ZnO buffer. GaxOy formation at the junction interface was the main limiting factor of this device performance. For CdS / CIGS and ZnSe / CIGS superstrate devices extensive inter-diffusion between the absorber and buffer layer under CIGS growth conditions was the critical problem. Inter-diffusion severely deteriorated the junction quality and led to poorly behaved devices, despite different efforts to optimize the fabrication process.

Download or read book Investigation of Polycrystalline Thin film CuInSe2 Solar Cells written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thin Film Solar Cells From Earth Abundant Materials written by Subba Ramaiah Kodigala and published by Newnes. This book was released on 2013-11-14 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fundamental concept of the book is to explain how to make thin film solar cells from the abundant solar energy materials by low cost. The proper and optimized growth conditions are very essential while sandwiching thin films to make solar cell otherwise secondary phases play a role to undermine the working function of solar cells. The book illustrates growth and characterization of Cu2ZnSn(S1-xSex)4 thin film absorbers and their solar cells. The fabrication process of absorber layers by either vacuum or non-vacuum process is readily elaborated in the book, which helps for further development of cells. The characterization analyses such as XPS, XRD, SEM, AFM etc., lead to tailor the physical properties of the absorber layers to fit well for the solar cells. The role of secondary phases such as ZnS, Cu2-xS,SnS etc., which are determined by XPS, XRD or Raman, in the absorber layers is promptly discussed. The optical spectroscopy analysis, which finds band gap, optical constants of the films, is mentioned in the book. The electrical properties of the absorbers deal the influence of substrates, growth temperature, impurities, secondary phases etc. The low temperature I-V and C-V measurements of Cu2ZnSn(S1-xSex)4 thin film solar cells are clearly described. The solar cell parameters such as efficiency, fill factor, series resistance, parallel resistance provide handful information to understand the mechanism of physics of thin film solar cells in the book. The band structure, which supports to adjust interface states at the p-n junction of the solar cells is given. On the other hand the role of window layers with the solar cells is discussed. The simulation of theoretical efficiency of Cu2ZnSn(S1-xSex)4 thin film solar cells explains how much efficiency can be experimentally extracted from the cells. - One of the first books exploring how to conduct research on thin film solar cells, including reducing costs - Detailed instructions on conducting research

Download or read book Research on Polycrystalline Thin film CuGaInSe sub 2 Solar Cells written by and published by . This book was released on 1992 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes research to fabricate high-efficiency CdZnS/CuInGaSe[sub 2] (CIGS) thin-film solar cells, and to develop improved transparent conductor window layers such as ZnO. A specific technical milestone was the demonstration of an air mass (AM) 1.5 global, 13% efficient, 1-cm[sup 2]-total-area CIGS thin-film solar cell. Our activities focused on three areas. First, a CIGS deposition: system was modified to double its substrate capacity, thus increasing throughput, which is critical to speeding the process development by providing multiple substrates from the same CIGS run. Second, new tooling was developed to enable an investigation of a modified aqueous CdZnS process. The goal was to improve the yield of this critical step in the device fabrication process. Third, our ZnO sputtering system was upgraded to improve its reliability, and the sputtering parameters were further optimized to improve its properties as a transparent conducting oxide. The characterization of the new CIGS deposition system substrate fixturing was completed, and we produced good thermal uniformity and adequately high temperatures for device-quality CIGS deposition. Both the CIGS and ZnO deposition processes were refined to yield a ZnO//Cd[sub 0.82]Zn[sub 0.18]S/CuIn[sub 0.80]Ga[sub 0.20]Se[sub 2] cell that was verified at NREL under standard testing conditions at 13.1% efficiency with V[sub oc] = 0.581 V, J[sub sc] = 34.8 mA/cm[sup 2], FF = 0.728, and a cell area of 0.979 cm[sup 2].

Download or read book Fundamentals of Polycrystalline Thin Film Materials and Devices written by and published by . This book was released on 1991 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents the results of a one-year research program on polycrystalline thin-film solar cells. The research was conducted to better understand the limitations and potential of solar cells using CuInSe2 and CdTe by systematically investigating the fundamental relationships linking material processing, material properties, and device behavior. By selenizing Cu and In layers, we fabricated device-quality CuInSe2 thin films and demonstrated a CuInSe2 solar cell with 7% efficiency. We added Ga, to increase the band gap of CuInSe2 devices to increase the open-circuit voltage to 0.55 V. We fabricated and analyzed Cu(InGa)Se2/CuInSe2 devices to demonstrate the potential for combining the benefits of higher V{sub oc} while retaining the current-generating capacity of CuInSe2. We fabricated an innovative superstrate device design with more than 5% efficiency, as well as a bifacial spectral-response technique for determining the electron diffusion length and optical absorption coefficient of CuInSe2 in an operational cell. The diffusion length was found to be greater than 1?m. We qualitatively modeled the effect of reducing heat treatments in hydrogen and oxidizing treatments in air on the I-V behavior of CuInSe2 devices. We also investigated post-deposition heat treatments and chemical processing and used them to fabricate a 9.6%-efficient CdTe/CdS solar cell using physical vapor deposition.

Download or read book Investigation of ZnSe and ZnSxSe1 x for Application in Thin Film Solar Cells written by Stephen Armstrong and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: AbstractSuccessful deposition of ZnSe and ZnS?Sei_x layers has been performed with close-spaced thermal evaporation (CSTE). ZnSe (Eg = 2.67eV) and ZnS, Sei, (Eg to 3.6eV) have the potential to replace CdS (Eg = 2.42 eV) as a buffer layer in solar cell applications, giving a two-fold benefit: (i) increased blue response of the cell, potentially allowing more light to reach the pn junction and contribute to photogeneration and (ii) reduce the toxic Cd element of the buffer layer. CSTE has produced films in which the deposition parameters can be controlled to alter the morphology of the as-deposited coatings. SEM and AFM investigations have shown that pinhole free ZnSe and ZnS?Sei_x films can be produced with this deposition process. In addition, the ZnSxSei, layers show a linear shift in lattice constant and a systematic shift in energy bandgap with alloy composition. XRD data and the steep absorption edges in the transmittance data confirm the good crystallinity of the layers. To partner the ZnSe and ZnS, Sei_x buffer layers in a thin film heterojunction, CdTe absorber layers were grown in the superstrate configuration. These CdTe layers were deposited in the same deposition chamber, without breaking vacuum, to reduce the risk of interfacial contamination. ZnSe and ZnSxSei_x / CdTe solar cells were fabricated with the best cell producing PV characteristics of: short circuit current 17mAcm-2, open circuit voltage 460mV and efficiency approaching 3%. The spectral response of all ZnSe and ZnSxSei_x / CdTe devices demonstrated a systematic shift to shorter wavelengths with increasing alloy composition, therefore showing the potential of these materials to increase solar cell efficiency. This low cost deposition process has shown excellent potential to be scaled up for commercial applications.

Download or read book Copper Zinc Tin Sulfide Based Thin Film Solar Cells written by Kentaro Ito and published by John Wiley & Sons. This book was released on 2014-12-11 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beginning with an overview and historical background of Copper Zinc Tin Sulphide (CZTS) technology, subsequent chapters cover properties of CZTS thin films, different preparation methods of CZTS thin films, a comparative study of CZTS and CIGS solar cell, computational approach, and future applications of CZTS thin film solar modules to both ground-mount and rooftop installation. The semiconducting compound (CZTS) is made up earth-abundant, low-cost and non-toxic elements, which make it an ideal candidate to replace Cu(In,Ga)Se2 (CIGS) and CdTe solar cells which face material scarcity and toxicity issues. The device performance of CZTS-based thin film solar cells has been steadily improving over the past 20 years, and they have now reached near commercial efficiency levels (10%). These achievements prove that CZTS-based solar cells have the potential to be used for large-scale deployment of photovoltaics. With contributions from leading researchers from academia and industry, many of these authors have contributed to the improvement of its efficiency, and have rich experience in preparing a variety of semiconducting thin films for solar cells.

Download or read book Development of Stable High efficiency Polycrystalline Thin film Solar Cells Based on CuInSe2 written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of CZTSe Solar Cell with ZnS ZnSe and In2S3 as Buffer Layers written by Madan Morusu and published by . This book was released on 2012 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: Demand for energy is ever growing and so is the demand for renewables as the fossil fuels are depleting at a rapid phase. The main goal of this thesis is to develop an optical model to calculate the optical properties of given cell like external quantum efficiency, reflectance, transmittance and maximum short circuit current. Among today's thin film technologies CIGS and CdTe are profound but the toxic nature of Cd, and hard to mine elements used in CIGS, like In, Ga make the commercial level production not feasible. The use of CZTSe which is mainly made of earth abundant materials, as absorber layer is investigated. Possible replacement materials of predominantly used buffer layer CdS such as ZnS, ZnSe and In2S3 are investigated.

Download or read book Polycrystalline Thin Film Materials and Devices written by and published by . This book was released on 1992 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of Phase II of a research program on polycrystalline thin film heterojunction solar cells are presented. Relations between processing, materials properties and device performance were studied. The analysis of these solar cells explains how minority carrier recombination at the interface and at grain boundaries can be reduced by doping of windows and absorber layers, such as in high efficiency CdTe and CuInSe2 based solar cells. The additional geometric dimension introduced by the polycrystallinity must be taken into consideration. The solar cells are limited by the diode current, caused by recombination in the space charge region. J-V characteristics of CuInSe2/(CdZn)S cells were analyzed. Current-voltage and spectral response measurements were also made on high efficiency CdTe/CdS thin film solar cells prepared by vacuum evaporation. Cu-In bilayers were reacted with Se and H2Se gas to form CuInSe2 films; the reaction pathways and the precursor were studied. Several approaches to fabrication of these thin film solar cells in a superstrate configuration were explored. A self-consistent picture of the effects of processing on the evolution of CdTe cells was developed.

Download or read book Clean Electricity From Photovoltaics written by Mary D Archer and published by World Scientific. This book was released on 2001-06-04 with total page 870 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic cells provide clean, reversible electrical power from the sun. Made from semiconductors, they are durable, silent in operation and free of polluting emissions. In this book, experts from all sectors of the PV community — materials scientists, physicists, production engineers, economists and environmentalists — give their critical appraisals of where the technology is now and what its prospects are./a

Download or read book CuInSe2 Solar Cells with MOCVD ZnO Buffer Layers written by Wenhua Lei and published by . This book was released on 1998 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: