Download or read book Higher Efficiency for Thin Multi Crystalline Silicon Solar Cells by Improving the Rear Surface Passivation written by C. J. J. Tool and published by . This book was released on 2002 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of High efficiency Solar Cells on Thin Silicon Through Design Optimization and Defect Passivation written by Manav Sheoran and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall goal of this research is to improve fundamental understanding of the hydrogen passivation of defects in low-cost silicon and the fabrication of high-efficiency solar cells on thin crystalline silicon through low-cost technology development. A novel method was developed to estimate the flux of hydrogen, released from amorphous silicon nitride film, into the silicon. Rapid-firing-induced higher flux of hydrogen was found to be important for higher defect passivation. This was followed by the fabrication of solar cell efficiencies of ~ 17% on low-cost, planar cast multicrystalline silicon. Solar cell efficiencies and lifetime enhancement in the top, middle, and bottom regions of cast multicrystalline silicon ingots were explained on the basis of impurities and defects generally found in those regions. In an attempt to further reduce the cost, high-efficiency solar cells were fabricated on thin crystalline silicon wafers with full area aluminum-back surface field. In spite of loss in efficiency, wafer thinning reduced the module cost. Device modeling was performed to establish a roadmap towards high-efficiency thin cells and back surface recombination velocity and back surface reflectance were identified as critical parameters for high-efficiency thin cells. Screen-printed solar cells on float zone material, with efficiencies> 19% on 300 Îơm and> 18% on 140 Îơm were fabricated using a novel low-cost fabrication sequence that involved dielectric rear passivation along with local contacts and back surface field.
Download or read book Surface Passivation of Industrial Crystalline Silicon Solar Cells written by Joachim John and published by Institution of Engineering and Technology. This book was released on 2018-11-15 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface passivation of silicon solar cells describes a technology for preventing electrons and holes to recombine prematurely with one another on the wafer surface. It increases the cell's energy conversion efficiencies and thus reduces the cost per kWh generated by a PV system.
Download or read book Aluminum Oxide for the Surface Passivation of High Efficiency Silicon Solar Cells written by Armin Richter and published by . This book was released on 2015-02-23 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Silicon Heterojunction Solar Cells written by W.R. Fahrner and published by Trans Tech Publications Ltd. This book was released on 2006-08-15 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Physics and Technology of Amorphous Crystalline Heterostructure Silicon Solar Cells written by Wilfried G. J. H. M. van Sark and published by Springer Science & Business Media. This book was released on 2011-11-16 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today’s solar cell multi-GW market is dominated by crystalline silicon (c-Si) wafer technology, however new cell concepts are entering the market. One very promising solar cell design to answer these needs is the silicon hetero-junction solar cell, of which the emitter and back surface field are basically produced by a low temperature growth of ultra-thin layers of amorphous silicon. In this design, amorphous silicon (a-Si:H) constitutes both „emitter“ and „base-contact/back surface field“ on both sides of a thin crystalline silicon wafer-base (c-Si) where the electrons and holes are photogenerated; at the same time, a-Si:H passivates the c-Si surface. Recently, cell efficiencies above 23% have been demonstrated for such solar cells. In this book, the editors present an overview of the state-of-the-art in physics and technology of amorphous-crystalline heterostructure silicon solar cells. The heterojunction concept is introduced, processes and resulting properties of the materials used in the cell and their heterointerfaces are discussed and characterization techniques and simulation tools are presented.
Download or read book Design Optimization of Thin Crystalline Silicon Solar Cells written by Dabraj Sarkar and published by . This book was released on 2012 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have explored novel design techniques and engineering tradeoffs such as base doping density, local BSF, local back contacts, and contact width and pitch to reduce the recombination losses. As the crystalline-silicon thickness is reduced to attain substantial cost reduction, excellent surface passivation on both sides is required to fabricate higher-efficiency solar cells. We fabricated back-contact solar cells and a-Si:H/c-Si heterojunction solar cells to achieve this goal. Numerical simulations with FLOODS were used to identify losses in these devices, and optimum device structures were designed, and performance predicted with numerical simulations. A novel remote-plasma CVD (RPCVD)-based process was developed for fabrication of a-Si:H/c-Si heterojunction(HJ) photovoltaic cells. In the RPCVD system, during the deposition process there is no direct exposure of the sample to the plasma. This can reduce the plasma damage to the silicon surface and improve passivation quality. Very high open-circuit voltage measured from fabricated heterojunction cells suggests that RPCVD is a potential technology for achieving improved passivation in HJ cells.
Download or read book High Efficiency Front Junction N Type Crystalline Silicon Solar Cells written by Yuguo Tao and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter aims to provide students/workers in the field of photovoltaics with the valuable information and knowledge needed to understand the physics and operation of high-efficiency front junction n-type crystalline silicon solar cells. The surface recombination and passivation mechanisms, and several promising passivation schemes for front and back cell surfaces, are addressed and reviewed. The advanced cell structures and their fabrication schemes to achieve higher efficiency are described and discussed, including selective emitter on the front and locally doped back surface filed or carrier selective rear contact composed of tunnel oxide and phosphorus-doped polycrystalline silicon thin film. These advanced cell design features have become highly active areas of investigations in the photovoltaic industry for next-generation production cells.
Download or read book High Efficiency Silicon Solar Cells written by Martin A. Green and published by Trans Tech Publications Ltd. This book was released on 1987-01-01 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The early chapters comprehensively review the optical and transport properties of silicon. Light trapping is described in detail. Limits on the efficiency of silicon cells are discussed as well as material requirements necessary to approach these limits. The status of current approaches to passifying surfaces, contacts and bulk regions is reviewed. The final section of the book describes the most practical approaches to the fabrication of high-efficiency cells capable of meeting the efficiency targets for both concentrated and non-concentrated sunlight, including a discussion of design and processing approaches for non-crystalline silicon.
Download or read book Application and Analysis of Silicon Nitride Films for Surface Passivation of High Efficiency Silicon Solar Cells written by and published by . This book was released on 2015 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Two solar cell types are discussed in this thesis. Firstly, the Metal Wrap-Through cell, where the emitter-contact metallization of the front side is wrapped through holes in the wafer to the cell back. Optimization of several cell processing steps led to an increase of more than 2% absolute in cell efficiency. By integrating these optimized process steps a cell efficiency of 17.9% was reached. Using these multicrystalline cells in modules, a highest module efficiency of 17.0% on aperture area was obtained, which was the world record at the end of 2009 and the beginning of 2010. Secondly, the Interdigitated Back Contact cell, where both the emitter and base region and their contacts are positioned at the cell back. This thesis describes the fabrication of this cell based on all-screen-printed patterning and metallization. By optimizing the front surface passivation, a short circuit current of 41.5 mA/cm2 and a cell efficiency of 19.1% was obtained. To further improve cell efficiency, surface passivation by a-SiNx:H is studied. By applying a NH3 plasma prior to a-SiNx:H layer deposition, it was found that the amount of K-centers and thereby the surface passivation could be varied without changing the actual a-SiNx:H deposition process and thus the a-SiNx:H bulk layer properties. Detailed characterization showed a gradual change in the composition of a-SiNx:H in the first 2 nm. By changing the temperature of the NH3 plasma, the amount and penetration depth of N in the first few nm's in the Si substrate were altered."--Samenvatting auteur.
Download or read book Improving Thin film Crystalline Silicon Solar Cell Efficiency with Back Surface Field and Blaze Gratings written by 吳信毅 and published by . This book was released on 2010 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rear Surface Passivation for High Efficiency Silicon Solar Cells written by Alban Jean-Joel Pereau and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Addressing Optical Recombination and Resistive Losses in Crystalline Silicon Solar Cells written by Thomas Gerald Allen and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of any photovoltaic device is determined by its ability to mitigate optical, recombination, and resistive energy losses. This thesis investigates new materials and nascent technologies to address these energy loss mechanisms in crystalline silicon solar cells. Optical losses, specifically the suppression of energy losses resulting from front surface reflection, are first analysed. The use of reactive ion etched black silicon texturing, a nano-scale surface texture, is assessed with respect to the two conventional texturing processes: isotexture and random pyramids. While nano-scale surface textures offer a means of almost eliminating front surface reflection, relatively poor internal optical properties (i.e. light trapping) compared to both conventional textures can compromise any optical gains realised on the front surface. It is also shown that enhanced recombination losses remains a barrier to the application of black silicon texturing to further improve high performance devices, though this will likely have less of an impact on multi-crystalline silicon cells where bulk recombination dominates.The suppression of recombination losses at surface defects by gallium oxide (Ga2O3), an alternative to aluminium oxide (Al2O3), is also investigated. It is demonstrated that, as in Al2O3, thin films of amorphous Ga2O3 can passivate surface defects through a direct reduction of recombination active defects and via the establishment of a high negative charge density. Further investigations demonstrate that Ga2O3 is applicable to random pyramid surfaces textures, and is compatible with plasma enhanced chemical vapour deposited silicon nitride (SiNx) capping for anti-reflection purposes. Indeed, the Ga2O3 / SiNx stack is shown to result in enhanced thermal stability and surface passivation properties comparable to state-of-the-art Al2O3 films. In addition, it is also shown that Ga2O3 can act as a Ga source in a laser doping process, as demonstrated by a proof-of-concept p-type laser doped partial rear contact solar cell with an efficiency of 19.2%. Finally, the resistive losses associated with metal / silicon contacts are addressed. It is demonstrated that a significant asymmetry in the work function of the electron and hole contact materials is sufficient to induce carrier selectivity without the need for heavy doping. This had recently been demonstrated for hole contacts with the high work function material molybdenum oxide. In this thesis specific attention is given to finding a suitable low work function material for the electron contact. Calcium, a common low work function electrode in organic electronic devices, is shown to act as a low resistance Ohmic contact to crystalline silicon without the need for heavy doping. Fabrication of n-type solar cells with partial rear calcium contacts resulted in a device efficiency of 20.3%, limited largely by recombination at the Ca / Si interface. This limitation to device efficiency is shown to be partially alleviated by the application of a passivating titania (TiOx) interlayer into the cell structure, resulting in an increase in device efficiency to 21.8% -- the highest reported efficiency for a TiOx-based heterojunction solar cell to date.
Download or read book Crystalline Silicon Surface Passivation by Amorphous Silicon Compounds written by Roman Petres and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2011-09 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar cells based on crystalline silicon (c-Si) have the potential to make photovoltaic electricity cheaper than coal-based electric power generation within less than 10 years. The largest cost decrease potential on the cell level lies with improved electronic surface passivation. In this work, the current industry standard, amorphous silicon nitride (a-SiNx: H) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD), is investigated and compared to amorphous silicon carbide, silicon carbonitride and silicon oxynitride films deposited by both high- and for the first time also low-frequency (LF) PECVD. It is shown that and an explanation offered as to why LF PECVD is capable of excellent surface passivation, comparable to remote-plasma results in literature and higher than previously published for LF PECVD. The achieved surface passivation quality is sufficient for dielectric rear-surface passivation without an underlying diffused back surface field. It is also shown that the purity grade of precursor gases used for film deposition can be lowered significantly without affecting cell efficiency and long-term stability on the module level, allowing for further cost reduction
Download or read book Facile Grown Native Oxide Based Passivation of Crystalline Silicon written by A. K. M. Zahidur Rahim Chowdhury and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Back Surface Passivation for High Efficiency Crystalline Silicon Solar Cells written by and published by . This book was released on 2012 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Final technical progress report for TetraSun, a Photovoltaic Technology Incubator awardee within the U.S. Department of Energy's (DOE) SunShot Program.
Download or read book Surface Passivation and Open circuit Voltage in Ultra thin Silicon Solar Cells written by Bhumika Chhabra and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon solar cells are the most widely used and optimized solar cells. Because of this, of any solar cell technology they have achieved efficiencies which are closest to their theoretical performance limits of any material. The record one-sun silicon solar cell has an efficiency of 24.7%, compared to a theoretical efficiency of approximately 31% (depending on the solar spectrum). In these devices, the short circuit currents are exceptionally close to their theoretical values. However, the open circuit voltages even in record solar cells are substantially below their theoretical limits. The highest voltage silicon solar cells attain voltages of approximately 739 mV by Sanyo. Other groups have shown the capability of achieving ~ 720 mV by several device structures using different methods of surface passivation. However, while these experimental results suggest a fundamental limiting mechanisms near 739 mV, the theoretical limit from detailed balance calculations is between 830 mV and 860 mV (depending on concentration and spectrum). The more than 100 mV discrepancy still remains a challange. In order to achieve silicon solar cells which approach the detailed balance voltage limits, the work will examine and reduce the fundamental mechanisms controlling the open circuit voltage. The three fundamental factors limiting the open circuit voltage of a solar cells are: (1) fundamental recombination parameters, which for silicon is dominated by Auger recombination; (2) the volume of material in which recombination takes place (which for a given concentration ratio is determined by the thickness of the material), and (3) the surface passivation. In order to overcome existing open circuit voltage limitations, each of these loss mechanisms require new approaches. If all of photo-generated carriers in the ultra-thin device can be extracted out of the device, in the form of current and voltage, then the efficiencies are bound to reach the detail balance limit. This can be possible only with a passivation scheme that allows very low surface recombination velocity and a light trapping scheme that allows the optical path length of 50, i.e. the light bounces back and forth in the device multiple times hence increasing the chances of absorption. Since the device thickness is reduced to a considerable amount, a low surface recombination velocity and an optical path length ~ 50 becomes extremely hard to achieve in ultra-thin wafers with today's technology. The goal of the thesis is to improve the understanding of the open circuit voltage in the silicon solar cells by means of theoretical demonstration of analytical modeling, and by practical means of reduced thickness and surface passivation schemes relevant for ultra-thin silicon solar cells.
