Author: Hasitha Padmika Mahabaduge
Publisher:
ISBN:
Category :
Languages : en
Pages : 131

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Book Description
Cadmium telluride (CdTe) solar cells have been developing as a promising candidate for large-scale application of photovoltaic energy conversion and have become the most commercially successful polycrystalline thin-film solar module material. In scaling up from small cells to large-area modules, inevitably non-uniformities across the large area will limit the performance of the large cell or module. The effects of these non-uniformities can be reduced by introducing a thin, high-resistivity transparent buffer layer between the conductive electrodes and the semiconductor diode. ZnO is explored in this dissertation as a high-resistivity transparent buffer layer for sputtered CdTe solar cells and efficiencies over 15% have been achieved on commercially available Pilkington TEC15M glass substrates. The highest open-circuit voltage of 0.858V achieved using the optimized ZnO buffer layer is among the best reported in the literature. The properties of ZnO:Al as a buffer are also investigated. We have shown that ZnO:Al can serve both as a transparent conducting oxide layer as well as a high-resistivity transparent layer for CdTe solar cells. ZnO:Al reactively sputtered with oxygen can give the necessary resistivities that allow it to be used as a high-resistivity transparent layer. Glass is the most common choice as the substrate for solar cells fabricated in the superstrate configuration due to its transparency and mechanical rigidity. However flexible substrates offer the advantages of light weight, high flexibility, ease of integrability and higher throughput through roll-to-roll processing over glass. This dissertation presents significant improvements made to flexible CdTe solar cells reporting an efficiency of 14% on clear Kapton® flexible polyimide substrates. Our efficiency of 14% is, to our knowledge, the best for any flexible CdTe cell reported in literature.

Author: Alan Fahrenbruch
Publisher: Elsevier
ISBN: 0323145388
Category : Technology & Engineering
Languages : en
Pages : 580

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Book Description
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.

Author: Srilatha Bapanapalli
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
ABSTRACT: CdS/CdTe solar cell performance and reproducibility can be improved by integrating a ZTO buffer layer, which interdiffuses into the CdS layer during device fabrication. Reducing the thickness of CdS layer improves the QE in the blue spectral region without affecting the device performance. This buffer layer is expected to prevent the formation of localized TCO/CdTe junction during high temperature processing. The CdS/CdTe Solar Cell was modified by introducing ZTO as a buffer layer between the window layer (CdS) and the absorber layer (CdTe). Studies were performed on different varying ZTO processing parameters like (a) Zn/Sn atomic ratios during sputtering process, (b) ZTO thickness, (c) ZTO heat treatment temperature, and (d) ZTO heat treatment ambient.

Author: Udai P. Singh
Publisher: Springer Nature
ISBN: 9811937249
Category : Technology & Engineering
Languages : en
Pages : 281

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Book Description
This book provides recent development in thin-film solar cells (TFSC). TFSC have proven the promising approach for terrestrial and space photovoltaics. TFSC have the potential to change the device design and produce high efficiency devices on rigid/flexible substrates with significantly low manufacturing cost. TFSC have several advantages in manufacturing compared to traditional crystalline Si-solar cells like less requirement of materials, can be prepared with earth’s abundant materials, less processing steps, easy to dispose, etc. Several universities/research institutes/industry in India and abroad are involved in the research area of thin-film solar cells. The book helps the readers to find the details about different thin-film technologies and its advancement at one place. Each chapter covers properties of materials, its suitability for PV applications, simple manufacturing processes and recent and past literature survey. The issues related to the development of high efficiency TFSC devices over large area and its commercial and future prospects are discussed.

Author: Yann Roussillon
Publisher:
ISBN:
Category : Photovoltaic power systems
Languages : en
Pages : 248

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Book Description

Author: Don Louis Morel
Publisher: DIANE Publishing
ISBN: 1428917292
Category :
Languages : en
Pages : 51

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Book Description

Author: Arvind Shah
Publisher: Springer Nature
ISBN: 3030464873
Category : Science
Languages : en
Pages : 357

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Book Description
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.

Author: Wei Xia
Publisher:
ISBN:
Category :
Languages : en
Pages : 173

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Book Description
"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: Arthur J. Nozik
Publisher: Royal Society of Chemistry
ISBN: 1849739951
Category : Science
Languages : en
Pages : 631

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Book Description
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.

Author: Jonathan Major
Publisher:
ISBN:
Category : Solar cells
Languages : en
Pages :

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Book Description
A systematic study is presented on the control of CdTe and CdS layers during their growth, with the understanding gained being implemented in the production of solar cells with enhanced performance. In particular the growth mechanisms for close space sublimation (CSS)? grown CdTe were evaluated as a function of processing gas (N2, 02 and H2) and nitrogen pressure. Films were shown to form via the Volmer-Weber growth mode with films deposited under nitrogen showing well defined crystal facets. Inclusion of oxygen in the deposition ambient produced islands of a rounded morphology, reduced size and increased number density, whilst hydrogen was shown to increase the island number density and the level of substrate coverage. Growth mechanisms were deduced from the morphologies observed at different stages of growth by ex-situ AFM and SEM and by comparison with growth literature, especially the work of P. Barna. Nucleation density, step flow and impurity incorporation are all invoked in the discussion. Factors influencing the cell performance were evaluated with the aid of a optical beam induced current (OBIC) and external quantum efficiency (EQE) system built as part of this work and having the capacity to measure EQE or OBIC maps with a resolution of 12.5pm. The system was used to evaluate the photovoltaic response of CdTe/CdS devices as a function of wavelength with the impact of the nitric-phosphoric acid (NP) etch on the back surface, the uniformity of CdTe/CdS devices deposited by different methods and the effect of absorber layer thickness of PV uniformity being assessed. The performance of CdTe/CdS devices was evaluated as a function of variables that could be influenced by growth of the CdTe and CdS layers. The use of lower substrate temperature and the incorporation oxygen in CdS increased V? from 0.51 to 0.65V is discussed. Oxygen in the CdTe was also shown to influence the junction position and hence efficiency, while oxygen in the CdS layer was also shown to be vital for the formation of hetero-junctions. The CdTe grain size was shown to be significantly increased for deposition under higher nitrogen pressures (Grain diameter = [0.027P + 0.9]gm, where P is the pressure in Torr), with the average grain diameters being 0.94pm at 2Torr and 5.63pm at 200Torr. Device performance was improved as a result with the peak device efficiency being increased from 2.1% at 2Torr to 14.1% at 100Torr. The series resistance was shown to be minimised for larger grain size, owing to the reduced contribution of grain boundaries. Suggestions for the fabrication of high efficiency solar cells are given with reference to the efficiency limiting factor.