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Author : M. Al-Achkar
Publisher :
ISBN 13 :
Total Pages : 321 pages
Book Rating : 4.:/5 (535 download)
Download or read book Efficiency Enhancement and Degradation Processes in Cu ̲xS/CdS Thin Film Solar Cells written by M. Al-Achkar and published by . This book was released on 1990 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Mohamed Al-Achkar
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (599 download)
Download or read book Efficiency Enhancement and Degradation Processes in CussxS/CdS Thin Film Solar Cells written by Mohamed Al-Achkar and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Mohamed Al-Achkar
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (757 download)
Download or read book Efficiency Enhancement and Degradation Processes in CuxS written by Mohamed Al-Achkar and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation has been made into the structure and properties of polycrystalline CuxS-CdS solar cells in order to develop an improved understanding of some of the processes which lead to unsatisfactory reproducibility and long term stability of the characteristics of these devices. The cells studied during this project were fabricated using vacuum evaporation for production of the CdS base layer and the well known chemical exchange process in a CuCl solution for formation of the CuxS layer. In view of the non-uniform thickness of the CuxS layer and non-planar structure of the Cu, S-CdS interface, it was found to be necessary to employ a variety of different characterisation techniques to monitor changes in the structure and properties of the devices. These techniques included I/V, C-V, spectral response and sheet resistance measurements, electrochemical analysis, cathodoluminescence spectroscopy and Rutherford backscattering. Detailed consideration was given to the influence of the conditions of formation on the properties of each cell component, in order to establish procedures necessary for the production of reproducible structures. particular attention was paid to the rate of growth of the CuxS layer and a theoretical analysis was developed to account for the time dependence of the growth in mean thickness of the CuxS layer in terms of the contributions associated with growth at the surface of the CdS layer and in the CdS grain boundary regions. The grain boundary contribution was found to be very sensitive to the CdS grain structure and to the previous treatment given to the CdS layer. Pre-annealing in air at 2000C enhanced the grain boundary penetration while the effect of ion implantation (with either Cu or Zn ions) was found to depend on the initial structure and the implantation conditions, but substantial improvements in the photovoltaic conversion efficiency were shown to be possible as a result of such treatment. The rate of degradation of cells exposed to air was also found to be dependent on the previous history of the cell. An increased concentration of Cd in the CuxS film (due to diffusion from the CdS layer) appeared to reduce the rate of qegradation while use of the standard stabilizing treatment (deposition of Cu overlayer followed by annealing in air) was shown to reduce interfacial diffusion as well as protecting the front surface of the CuxS layer against oxidation.
Author : Vikash Ranjan
Publisher :
ISBN 13 :
Total Pages : 164 pages
Book Rating : 4.:/5 (78 download)
Download or read book Enhancement of the Deposition Processes of Cu(In, Ga)Se2 and Cds Thin Films Via In-situ and Ex-situ Measurements for Solar Cell Application written by Vikash Ranjan and published by . This book was released on 2011 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin films of Cu(In, Ga)Se2 deposited by 1-stage, 2-stage and 3-stage co-evaporation processes result into the highest efficiency solar cells. Controlling the rate and sequences of individual sources during these co-evaporation processes are important for better quality Cu(In, Ga)Se2 absorber layers. At the same time, spectroscopic ellipsometry due to its ex-situ as well as in-situ application is considered as a very powerful tool to understand the material properties as well as to monitor the process. Nevertheless, spectroscopic ellipsometry was not properly utilized until now to characterize Cu(In, Ga)Se2 thin films. In this study, one of our goal is to understand the optical and electrical properties of Cu(In, Ga)Se2 as a function of process and composition. In the first part of this study, we implemented ex-situ spectroscopic ellipsometry (SE) along with other characterization techniques like Secondary ion mass spectroscopy (SIMS), Scanning electron microscopy (SEM), Auger electron spectroscopy (AES), x-ray diffraction (XRD), atomic force microscopy (AFM) etc. to compare Cu(In, Ga)Se2 thin films deposited by the above mentioned three co-evaporation processes. During this study, we were able to use SE to find the thickness, roughness, band gap, Ga grading of the Cu(In, Ga)Se2 deposited by 2-stage and 3-stage process. Finding of SE were correlated by SIMS, AES, SEM etc. In the case of Cu(In, Ga)Se2 deposited by 1-stage process, due to the high surface roughness, we are not able to implement the ex-situ spectroscopic ellipsometry. In the second and third part of this study, real time spectroscopic ellipsometry is implemented to study the material properties of Cu(In, Ga)Se2 thin films as a function of Cu and Ga concentration. Effectively, in a 3-stage co-evaporation process, the composition of the film changes during the process. To monitor and control the composition of Cu(In, Ga)Se2 during the 3-stage process by in-situ ellipsometry, it was necessary to understand the optical properties of Cu(In, Ga)Se2 as a function of Cu atomic percentage (at.%) as well as Ga at.%. Along with this, the inability to implement ex-situ SE for Cu(In, Ga)Se2 thin film motivated us to implement the spectroscopic ellipsometry in real time i.e. during the growth of the film. This in-situ real time application of SE helped us in understanding the micostructural evolution and dependence of the band gap with the Cu atomic percentage (at.%) as well as the Ga at.%. We also used this opportunity to understand the shift in the critical points as a function of temperature for CuInSe2 alloys. Characterization like AES, XRD, AFM etc were performed after the growth at room temperature to corroborate the RTSE findings. In the fourth and last part of this study, the growth of CdS on a Cu(In, Ga)Se2 surface as a function of time was studied using SE as well as AFM. We also used this opportunity to compare the growth of CdS on another substrate (SiO2). Spectroscopic ellipsometry and AFM revealed a quantum confinement effect in the case of CdS on SiO2 whereas no such effect was observed for CdS on Cu(In, Ga)Se2 surface due to the growth of compact CdS layers.
Author : Wei Xia
Publisher :
ISBN 13 :
Total Pages : 173 pages
Book Rating : 4.:/5 (875 download)
Download or read book Approaches to Fabricating High-efficiency Ultra-thin CdTe Solar Cells written by Wei Xia and published by . This book was released on 2012 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis is an investigation of the fabrication, characterization and performance of high-efficiency and ultra-thin CdTe solar cells with an aim of reducing the material usage and cell manufacturing cost. Several approaches have been successfully carried out to directly or indirectly improve the device performance. Major achievements are listed below: 1) A close-spaced sublimation (CSS) process with an improved control of the deposition temperature-time profile was developed to fabricate high-quality ultra-thin CdTe films. Three key factors in the CSS process including oxygen pressure, substrate temperature and thermal etch duration were optimized. 2) A two-stage post-deposition treatment including a high temperature annealing (HTA) followed by a vaporous cadmium chloride treatment (VCC) was developed and optimized for the growth of high-quality CdTe films. The effects of HTA and VCC on ultra-thin CdTe solar cells were revealed by a combination of characterization techniques, including photoluminescence. 3) In a collaborative effort two new back contact buffers, MoOx and Te/Cu, were identified and applied in ultra-thin CdTe solar cells. Substitution of a conventional acid etching method with the new back contact buffers was found to enhance the cell efficiency from ~10% to ~13.5%. Moreover, the new buffers improved the reproducibility of cell fabrication. A low-resistance electrical back contact based on the Te/Cu buffer and Ni as electrode was developed. A thermal activation process was found necessary to promote ohmic contact formation. Cu diffusion into the Te layer and CdTe bulk layer occurred during the thermal activation process and must be controlled to prevent excessive diffusion into the CdS/CdTe junction. The effects of Cu concentration and Te thickness on device performance and cell stability were systematically investigated and a cell efficiency as high as ~15% with good stability has been achieved using an optimized Te/Cu buffer. 4) A novel vaporous zinc chloride treatment was developed for the formation of Cd1xZnxS from CdS films. Compared with conventional fabrication methods, the VZC method features simple setup and operation and is capable of producing Cd1xZnxS films with a homogenous structure. The Zn to Cd doping ratio in Cd1−xZnxS can be easily controlled by adjusting the process parameters. By replacing CdS with a more transparent Cd1−xZnxS as the window layer, CdTe solar cells with a higher (12-14%) short-circuit current, Jsc, have been demonstrated"--Page v-vi.
Author :
Publisher :
ISBN 13 :
Total Pages : 88 pages
Book Rating : 4.:/5 (318 download)
Download or read book Cumulative Index to IEEE Photovoltaic Specialists Conferences, 1962-1980 written by and published by . This book was released on 1980 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jef Poortmans
Publisher : John Wiley & Sons
ISBN 13 : 0470091266
Total Pages : 504 pages
Book Rating : 4.4/5 (7 download)
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.
Author : H. E. Nastelin
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (759 download)
Download or read book Improvements in CdS Thin Film Solar Cells written by H. E. Nastelin and published by . This book was released on 1968 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of two CdS thin film solar cell flight panels, which were included in a satellite experiment in a high radiation orbit, showed no serious degradation after a period of 130 days. The results of balloon flight calibration tests indicate that AM0 performance of CdS thin film solar cells at 80,000 feet very closely parallels simulated AM0 measurements. The evaluation of a number of materials as contacts to the barrier layer of the CdS cell indicates that gold, either evaporated or as the filler in a conductive epoxy such as is presently used in the fabrication process of CdS cells, provides the lowest resistant ohmic contact. A study in the optimization of the barrier formation process shows that a fairly wide latitude exists in the various process parameters, especially as regards low light level performance. (Author).
Author :
Publisher :
ISBN 13 :
Total Pages : 532 pages
Book Rating : 4.3/5 (91 download)
Download or read book Solar Energy Update written by and published by . This book was released on 1983 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Alan G. Stanley
Publisher :
ISBN 13 :
Total Pages : 20 pages
Book Rating : 4.:/5 (15 download)
Download or read book Degradation of CdS Thin Film Solar Cells in Different Environments written by Alan G. Stanley and published by . This book was released on 1970 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Qiaoer Zhou
Publisher :
ISBN 13 :
Total Pages : 288 pages
Book Rating : 4.:/5 (26 download)
Download or read book Thin Film Solar Cells written by Qiaoer Zhou and published by . This book was released on 2011 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Poonam Rani Kharangarh
Publisher :
ISBN 13 :
Total Pages : 134 pages
Book Rating : 4.:/5 (93 download)
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.
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (14 download)
Download or read book Process Development and Basic Studies of Electrochemically Deposited CdTe-Based Solar Cells: Annual Technical Report, Phase II, 16 May 1999 - 13 May 2000 written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project which is performed at the Colorado School of Mines (CSM), part of the NREL Thin-Film Partnership Program. The project addresses long-term research and development issues related to polycrystalline thin-film solar cells. Our general research approach is based on combining activities aimed at improvement of cell performance and stability with activities aimed at increasing ourfundamental understanding of the properties of materials making up the cells; CdTe, CdS, multi-layer back contact, and transparent conducting oxide (TCO) from contact. We emphasize the relation between structural and electronic materials properties and various processing procedures as well as the microscopic mechanisms responsible for the cell performance and its degradation.
Download or read book Sammlung ausgewählter Mittheilungen über schädliche und nützliche Thiere, nebst mehreren technischen und statistischen Notizen written by and published by . This book was released on 1857 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : L. R. Shiozawa
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (759 download)
Download or read book Research on the Mechanism of the Photovoltaic Effect in High Efficiency CdS Thin-film Solar Cells written by L. R. Shiozawa and published by . This book was released on 1969 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three years of research on the operating mechanisms of the CdS thin-film solar cell are described in this report. The essential information contained in all reports previously issued under this contract has been reassembled. New information, not previously reported include data on the antimonochromatic spectral response of different types of cells, measurements of the threshold voltage for electrolytic deposition of copper from Cu2S, observations on the formation of copper whiskers on Cu2S by heating, X-ray crystallographic data on low-temperature phase transformations of cuprous sulfide, measurements of optical transmission of Cu-saturated CdS single crystals, data on the photoconductive rise and decay times of Cu-compensated CdS, discussion of the beneficial role of oxygen in promoting the photovoltaic effect during cell fabrication, and the subsequent degrading effects of oxygen during high temperature exposure. (Author).
Author : H. E. Nastelin
Publisher :
ISBN 13 :
Total Pages : 45 pages
Book Rating : 4.:/5 (227 download)
Download or read book Improvements in CdS Thin Film Solar Cells written by H. E. Nastelin and published by . This book was released on 1968 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of two CdS thin film solar cell flight panels, which were included in a satellite experiment in a high radiation orbit, showed no serious degradation after a period of 130 days. The results of balloon flight calibration tests indicate that AM0 performance of CdS thin film solar cells at 80,000 feet very closely parallels simulated AM0 measurements. The evaluation of a number of materials as contacts to the barrier layer of the CdS cell indicates that gold, either evaporated or as the filler in a conductive epoxy such as is presently used in the fabrication process of CdS cells, provides the lowest resistant ohmic contact. A study in the optimization of the barrier formation process shows that a fairly wide latitude exists in the various process parameters, especially as regards low light level performance. (Author).
Author : Bhaskar Reddy Tetali
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (625 download)
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.
