Improved Transparent Conducting Oxides Boost Performance of Thin-Film Solar Cells (Fact Sheet)


Book Description

Today?s thin-film solar cells could not function without transparent conducting oxides (TCOs). TCOs act as a window, both protecting the cell and allowing light to pass through to the cell?s active layers. Until recently, TCOs were seen as a necessary, but static, layer of a thin-film photovoltaic (PV) cell. But a group of researchers at the National Renewable Energy Laboratory (NREL) hasidentified a pathway to producing improved TCO films that demonstrate higher infrared transparency. To do so, they have modified the TCOs in ways that did not seem possible a few years ago.




Silicon Heterojunction Solar Cells


Book Description

The world of today must face up to two contradictory energy problems: on the one hand, there is the sharply growing consumer demand in countries such as China and India. On the other hand, natural resources are dwindling. Moreover, many of those countries which still possess substantial gas and oil supplies are politically unstable. As a result, renewable natural energy sources have received great attention. Among these, solar-cell technology is one of the most promising candidates. However, there still remains the problem of the manufacturing costs of such cells. Many attempts have been made to reduce the production costs of “conventional” solar cells (manufactured from monocrystalline silicon using diffusion methods) by instead using cheaper grades of silicon, and simpler pn-junction fabrication. That is the ‘hero’ of this book; the heterojunction solar cell.




Glow Discharge Processes


Book Description

Develops detailed understanding of the deposition and etching of materials by sputtering discharge, and of etching of materials by chemically active discharge. Treats glow discharge at several levels from basic phenomena to industrial applications--practical techniques diligently related to fundamentals. Subjects range from voltage, distributions encountered in plasma etching systems to plasma-electron interactions that contribute to sustaining the discharge.




Sputtering Materials for VLSI and Thin Film Devices


Book Description

An important resource for students, engineers and researchers working in the area of thin film deposition using physical vapor deposition (e.g. sputtering) for semiconductor, liquid crystal displays, high density recording media and photovoltaic device (e.g. thin film solar cell) manufacturing. This book also reviews microelectronics industry topics such as history of inventions and technology trends, recent developments in sputtering technologies, manufacturing steps that require sputtering of thin films, the properties of thin films and the role of sputtering target performance on overall productivity of various processes. Two unique chapters of this book deal with productivity and troubleshooting issues. The content of the book has been divided into two sections: (a) the first section (Chapter 1 to Chapter 3) has been prepared for the readers from a range of disciplines (e.g. electrical, chemical, chemistry, physics) trying to get an insight into use of sputtered films in various devices (e.g. semiconductor, display, photovoltaic, data storage), basic of sputtering and performance of sputtering target in relation to productivity, and (b) the second section (Chapter 4 to Chapter 8) has been prepared for readers who already have background knowledge of sputter deposition of thin films, materials science principles and interested in the details of sputtering target manufacturing methods, sputtering behavior and thin film properties specific to semiconductor, liquid crystal display, photovoltaic and magnetic data storage applications. In Chapters 5 to 8, a general structure has been used, i.e. a description of the applications of sputtered thin films, sputtering target manufacturing methods (including flow charts), sputtering behavior of targets (e.g. current - voltage relationship, deposition rate) and thin film properties (e.g. microstructure, stresses, electrical properties, in-film particles). While discussing these topics, attempts have been made to include examples from the actual commercial processes to highlight the increased complexity of the commercial processes with the growth of advanced technologies. In addition to personnel working in industry setting, university researchers with advanced knowledge of sputtering would also find discussion of such topics (e.g. attributes of target design, chamber design, target microstructure, sputter surface characteristics, various troubleshooting issues) useful. . Unique coverage of sputtering target manufacturing methods in the light of semiconductor, displays, data storage and photovoltaic industry requirements Practical information on technology trends, role of sputtering and major OEMs Discussion on properties of a wide variety of thin films which include silicides, conductors, diffusion barriers, transparent conducting oxides, magnetic films etc. Practical case-studies on target performance and troubleshooting Essential technological information for students, engineers and scientists working in the semiconductor, display, data storage and photovoltaic industry







Electrochemical Deposition of Transparent Conducting Oxides for Photovoltaic Applications


Book Description

Textured back reflector (BR) is an essential component used in substrate type solar cells for light trapping, which enhances the long wavelength absorption. Most commonly used BR consists of a reflecting metal layer(s) of Ag and/or Al and a transparent conducting oxide (TCO) layer such as ZnO. This type of BR, if properly textured, can lead to about 20% increase in the short-circuit current and cell efficiency. A widely used technique for producing the BR is sputtering due to its simplicity and easy operation for large area thin film solar cell applications. The TCO layer needs to be thick enough (>500 nm) to reach a textured structure and to prevent the metal in the BR from diffusing into the solar cell layers. Thus, the ZnO deposition becomes the bottleneck in the BR process. Significant efforts have been putting on developing novel techniques that can produce ZnO coatings with better texture and high deposition rate. To address the above issue electrodeposition was employed to coat ZnO film, because it gives high deposition rate at low cost. A systematic study of conventional electrodeposition was performed. Further improvements for the electrodeposition process have done to eliminate some of the problems associated with conventional electrodeposition. In addition highly textured BR produced by electrodeposited ZnO changes the electrical structure of the device. The necessity to consider these factors when fabricating solar cells on highly textured BR was emphasized using PVOPTICS and AMPS modeling. Hydrogen is considered to be the fuel of the future. Subsequently there are many attempts of generating H2 by environmentally friendly means. One such proposed system is photo-electrochemical cell (PEC) consist of transparent conducting corrosion resistive (TCCR) layer, a-Si:H solar cell and catalytic layer. The research work done to identify the potential TCCR layers and fabrication of porous nickel catalyst layer will be discussed.




Handbook of Transparent Conductors


Book Description

Transparent conducting materials are key elements in a wide variety of current technologies including flat panel displays, photovoltaics, organic, low-e windows and electrochromics. The needs for new and improved materials is pressing, because the existing materials do not have the performance levels to meet the ever- increasing demand, and because some of the current materials used may not be viable in the future. In addition, the field of transparent conductors has gone through dramatic changes in the last 5-7 years with new materials being identified, new applications and new people in the field. “Handbook of Transparent Conductors” presents transparent conductors in a historical perspective, provides current applications as well as insights into the future of the devices. It is a comprehensive reference, and represents the most current resource on the subject.




Recent Advances in Thin Film Photovoltaics


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.