Download or read book Toward Better Understanding and Improved Performance of Silicon Heterojunction Solar Cells written by and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The double-sided silicon heterojunction (SHJ) solar cell is more appropriate for n-type crystal silicon (c-Si) wafers than for p-type c-Si wafers because there is a larger band offset to the valence band edge of hydrogenated amorphous silicon than to the conduction band edge. Thin intrinsic and doped hydrogenated amorphous silicon (a Si:H) double layers by hot-wire chemical vapor deposition (HWCVD) are investigated as passivation layers, emitters, and back-surface-field (BSF) contacts to both p- and n-type wafers. Passivation quality is studied by characterizing the SHJ solar cells and by photoconductive decay (PCD) minority-carrier lifetime measurements. The crystal-amorphous heterointerface is studied with real-time spectroscopic ellipsometry (RTSE) and high-resolution transmission electron microscopy (HRTEM) to detect phase change and material evolution, with a focus on better understanding the factors determining passivation effectiveness. A common feature in effective passivation, emitter, and BSF layers is immediate a-Si:H deposition and an abrupt and flat interface to the c-Si substrate. In this case, good wafer passivation or an excellent heterojunction is obtained, with a low interface recombination velocity (S) or a high open-circuit voltage (Voc). Voc greater than 640 mV, S less than 15 cm/sec, and efficiency of 14.8% have been achieved on polished p type Czochralski-grown (CZ) Si wafers. Collaboration between NREL and Georgia Tech resulted in a 15.7%-efficient HWCVD-deposited SHJ cell on non-textured FZ-Si with a screen-printed Al back surface field (BSF), the highest reported HWCVD SHJ cell. Collaboration between NREL and SunPower demonstrated that HWCVD a-Si:H passivation can be better than the conventional oxides, with a low surface recombination velocity of 42 cm/sec on textured n-type FZ-Si.
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 Silicon Heterojunction Solar Cells Analysis and Basic Understanding written by Martin Bivour and published by . This book was released on 2017-03-29 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of Solar Cell Design written by Inamuddin and published by John Wiley & Sons. This book was released on 2021-08-24 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar cells are semiconductor devices that convert light photons into electricity in photovoltaic energy conversion and can help to overcome the global energy crisis. Solar cells have many applications including remote area power systems, earth-orbiting satellites, wristwatches, water pumping, photodetectors and remote radiotelephones. Solar cell technology is economically feasible for commercial-scale power generation. While commercial solar cells exhibit good performance and stability, still researchers are looking at many ways to improve the performance and cost of solar cells via modulating the fundamental properties of semiconductors. Solar cell technology is the key to a clean energy future. Solar cells directly harvest energy from the sun’s light radiation into electricity are in an ever-growing demand for future global energy production. Solar cell-based energy harvesting has attracted worldwide attention for their notable features, such as cheap renewable technology, scalable, lightweight, flexibility, versatility, no greenhouse gas emission, environment, and economy friendly and operational costs are quite low compared to other forms of power generation. Thus, solar cell technology is at the forefront of renewable energy technologies which are used in telecommunications, power plants, small devices to satellites. Aiming at large-scale implementation can be manipulated by various types used in solar cell design and exploration of new materials towards improving performance and reducing cost. Therefore, in-depth knowledge about solar cell design is fundamental for those who wish to apply this knowledge and understanding in industries and academics. This book provides a comprehensive overview on solar cells and explores the history to evolution and present scenarios of solar cell design, classification, properties, various semiconductor materials, thin films, wafer-scale, transparent solar cells, and so on. It also includes solar cells’ characterization analytical tools, theoretical modeling, practices to enhance conversion efficiencies, applications and patents.
Download or read book High efficiency Silicon Heterojunction Solar Cells written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon heterojunction technology (HJT) uses silicon thin-film deposition techniques to fabricate photovoltaic devices from mono-crystalline silicon wafers (c-Si). This enables energy-conversion efficiencies above 21 %, also at industrial-production level. In this presentation we review the present status of this technology and point out recent trends. We first discuss how the properties of thin hydrogenated amorphous silicon (a-Si:H) films can be exploited to fabricate passivating contacts, which is the key to high- efficiency HJT solar cells. Such contacts enable very high operating voltages, approaching the theoretical limits, and yield small temperature coefficients. With this approach, an increasing number of groups are reporting devices with conversion efficiencies well over 20 % on n-type wafers, Panasonic leading the field with 24.7 %. Exciting results have also been obtained on p-type wafers. Despite these high voltages, important efficiency gains can still be made in fill factor and optical design. This requires improved understanding of carrier transport across device interfaces and reduced parasitic absorption in HJT solar cells. For the latter, several strategies can be followed: Short- wavelength losses can be reduced by replacing the front a-Si:H films with wider-bandgap window layers, such as silicon alloys or even metal oxides. Long-wavelength losses are mitigated by introducing new high-mobility TCO's such as hydrogenated indium oxide, and also by designing new rear reflectors. Optical shadow losses caused by the front metalisation grid are significantly reduced by replacing printed silver electrodes with fine-line plated copper contacts, leading also to possible cost advantages. The ultimate approach to minimize optical losses is the implementation of back-contacted architectures, which are completely devoid of grid shadow losses and parasitic absorption in the front layers can be minimized irrespective of electrical transport requirements. The validity of this approach was convincingly demonstrated by Panasonic, Japan in 2014, reporting on an interdigitated back-contacted HJT cell with an efficiency of 25.6%, setting the new single-junction c-Si record. Finally, given the virtually perfect surface passivation and excellent red response of HJT solar cells, we anticipate these devices will also become the preferred bottom cell in ultra-high efficiency c-Si-based tandem devices, exploiting better the solar spectrum. Such tandem cells have the potential to overcome the fundamental single-junction limit of silicon solar cells (29.4%). Combining HJT cells with perovskite solar cells as top cell appears to be particularly appealing.
Download or read book High Efficiency Crystalline Silicon Solar Cells written by Eun-Chel Cho and published by MDPI. This book was released on 2021-01-06 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is composed of 6 papers. The first paper reports a novel technique for the selective emitter formation by controlling the surface morphology of Si wafers. Selective emitter (SE) technology has attracted renewed attention in the Si solar cell industry to achieve an improved conversion efficiency of passivated-emitter rear-contact (PERC) cells. In the second paper, the temperature dependence of the parameters was compared through the PERC of the industrial-scale solar cells. As a result of their analysis, PERC cells showed different temperature dependence for the fill factor loss as temperatures rose. The third paper reports the effects of carrier selective front contact layer and defect state of hydrogenated amorphous silicon passivation layer/n-type crystalline silicon interface. The results demonstrated the effects of band offset determined by band bending at the interface of the passivation layer and carrier selective front contact layer. In addition, the nc-SiOx: H CSFC layer not only reduces parasitic absorption loss but also has a tunneling effect and field-effect passivation. The fourth paper reports excimer laser annealing of hydrogenated amorphous silicon film for TOPCon solar cell application. This paper analyzes the crystallization of a-Si:H via excimer laser annealing (ELA) and compared this process with conventional thermal annealing. The fifth paper reports the contact mechanism between Ag–Al and Si and the change in contact resistance (Rc) by varying the firing profile. Rc was measured by varying the belt speed and peak temperature of the fast-firing furnace. The sixth paper reports a silicon tandem heterojunction solar cell based on a ZnO/Cu2O subcell and a c-Si bottom subcell using electro-optical numerical modeling. The buffer layer affinity and mobility together with a low conduction band offset for the heterojunction are discussed, as well as spectral properties of the device model.
Download or read book Toward the Structural Understanding and Improved Performance of Quantum Dot Solar Cells written by Matthew A. Becker and published by . This book was released on 2012 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of ISES World Congress 2007 Vol 1 Vol 5 written by D. Yogi Goswami and published by Springer Science & Business Media. This book was released on 2009-09-01 with total page 3091 pages. Available in PDF, EPUB and Kindle. Book excerpt: ISES Solar World Congress is the most important conference in the solar energy field around the world. The subject of ISES SWC 2007 is Solar Energy and Human Settlement, it is the first time that it is held in China. This proceedings consist of 600 papers and 30 invited papers, whose authors are top scientists and experts in the world. ISES SWC 2007 covers all aspects of renewable energy, including PV, collector, solar thermal electricity, wind, and biomass energy.
Download or read book Silicon Heterojunction Solar Cells written by Dong Xu and published by LAP Lambert Academic Publishing. This book was released on 2011-08 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Silicon heterojunction solar cells----Understanding and optimization of a-Si PECVD deposition" is a summary of author's research work on silicon heterojunction solar cells at Institute of Energy Conversion, University of Delaware. The author's team is the first U.S. research group that demonstrates a >18% silicon heterojunction solar cell and the first team in worldwide that demonstrates an all back contact silicon heterojunction solar cell.
Download or read book Silicon Based Thin Film Solar Cells written by Roberto Murri and published by Bentham Science Publishers. This book was released on 2013-03-20 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon Based Thin Film Solar Cells explains concepts related to technologies for silicon (Si) based photovoltaic applications. Topics in this book focus on ‘new concept’ solar cells. These kinds of cells can make photovoltaic power production an economically viable option in comparison to the bulk crystalline semiconductor technology industry. A transition from bulk crystalline Si solar cells toward thin-film technologies reduces usage of active material and introduces new concepts based on nanotechnologies. Despite its importance, the scientific development and understanding of new solar cells is not very advanced, and educational resources for specialized engineers and scientists are required. This textbook presents the fundamental scientific aspects of Si thin films growth technology, together with a clear understanding of the properties of the material and how this is employed in new generation photovoltaic solar cells. The textbook is a valuable resource for graduate students working on their theses, young researchers and all people approaching problems and fundamental aspects of advanced photovoltaic conversion.
Download or read book Silicon Heterojunction Solar Cells The Key Role of Heterointerfaces and Their Impact on the Performance written by Miroslav Mikolášek and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter is dedicated to the processes linked with the collection of photo-generated carriers in silicon heterojunction (SHJ) solar cells with a focus on the key role of the amorphous silicon/crystalline silicon heterojunction. The intention is to explain the role of carrier inversion at the heterointerface and connect it with the properties of the SHJ to obtain deeper understanding of carrier transport properties and collection, which goes beyond amorphous silicon-based structures and will contribute to understanding the new emerging SHJ based on amorphous silicon oxide and metal oxide emitter layers. The study is extended by a simulation of the TCO/emitter interface with the aim to reveal the effect of parasitic Schottky barrier height on the performance of the SHJ solar cell. In addition, the simulation study of SHJ under concentrated light and varied temperatures is outlined to show the main limitations and prospects of SHJ structures for utilization under concentrated light.
Download or read book Fundamental Understanding and Development of Low cost High efficiency Silicon Solar Cells written by and published by . This book was released on 2000 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objectives of this program are (1) to develop rapid and low-cost processes for manufacturing that can improve yield, throughput, and performance of silicon photovoltaic devices, (2) to design and fabricate high-efficiency solar cells on promising low-cost materials, and (3) to improve the fundamental understanding of advanced photovoltaic devices. Several rapid and potentially low-cost technologies are described in this report that were developed and applied toward the fabrication of high-efficiency silicon solar cells.
Download or read book Multiscale Modeling of Silicon Heterojunction Solar Cells written by Pradyumna Muralidharan and published by . This book was released on 2019 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon photonic technology continues to dominate the solar industry driven by steady improvement in device and module efficiencies. Currently, the world record conversion efficiency (~26.6%) for single junction silicon solar cell technologies is held by silicon heterojunction (SHJ) solar cells based on hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si). These solar cells utilize the concept of carrier selective contacts to improve device efficiencies. A carrier selective contact is designed to optimize the collection of majority carriers while blocking the collection of minority carriers. In the case of SHJ cells, a thin intrinsic a-Si:H layer provides crucial passivation between doped a-Si:H and the c-Si absorber that is required to create a high efficiency cell. There has been much debate regarding the role of the intrinsic a-Si:H passivation layer on the transport of photogenerated carriers, and its role in optimizing device performance. In this work, a multiscale model is presented which utilizes different simulation methodologies to study interfacial transport across the intrinsic a-Si:H/c-Si heterointerface and through the a-Si:H passivation layer. In particular, an ensemble Monte Carlo simulator was developed to study high field behavior of photogenerated carriers at the intrinsic a-Si:H/c-Si heterointerface, a kinetic Monte Carlo program was used to study transport of photogenerated carriers across the intrinsic a-Si:H passivation layer, and a drift-diffusion model was developed to model the behavior in the quasi-neutral regions of the solar cell. This work reports de-coupled and self-consistent simulations to fully understand the role and effect of transport across the a-Si:H passivation layer in silicon heterojunction solar cells, and relates this to overall solar cell device performance.
Download or read book Si Heterojunction Solar Cells written by Dong Xu and published by LAP Lambert Academic Publishing. This book was released on 2011 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes author's work of process development and device characterization on traditional front junction silicon heterojunction solar cells and all back contact IBC silicon heterojunction solar cell at Univeristy of Delaware from summer of 2006 to the end of 2008.The work demonstrates a high Voc close to 700mV in surface textured front junction silicon heterojunction solar cells and high efficiency all back contact solar cells by the support of U.S. Department of Energy.
Download or read book Junction Engineering and Device Design for Silicon Heterojunction and Interdigitated Back Contact Silicon Heterojunction Solar Cells written by Lei Zhang and published by . This book was released on 2018 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interdigitated back contact silicon heterojunction (IBC-SHJ) solar cell currently holds the record conversion efficiency for non-concentrated single junction silicon solar cells with an efficiency of 26.7%. The aim of this dissertation is to understand the fundamental loss mechanisms of IBC-SHJ related to the rear surface design and to minimize these losses utilizing advanced numerical simulations, novel test structure characterizations and scalable device fabrication processes. The findings in this dissertation will serve as guidance for the industry-oriented R & D efforts to make IBC-SHJ mass-production cost-effective without compromising the performance. The outcomes of this dissertation are four-fold: ☐ First, a lifetime simulation tool based on the extended Shockley-Read-Hall (SRH) recombination formalism has been developed as guidance to investigate c-Si surface passivation. Plasma enhanced chemical vapor deposition (PECVD) conditions of intrinsic hydrogenated amorphous silicon (i.a-Si:H) films were explored for passivating the commercial n-type c-Si (n.c-Si) wafer surfaces and correlation to the properties of films was established through material characterizations. Passivated lifetime > 1ms with implied open circuit voltage (iVOC) > 700 mV has been achieved. The trade-off between front surface absorption loss and rear surface emitter junction valence band offset effect was simultaneously accommodated with an optimized i.a-Si:H layer. ☐ Second, an advanced two-dimensional (2-D) IBC-SHJ simulation model has been developed to investigate the IBC-SHJ device rear surface design of three regions: emitter contact, base contact and the non-metallized gap region between them. Simulations suggested that IBC-SHJ performance is more sensitive to the surface passivation quality in emitter and gap regions than the base region. The trade-offs between VOC and FF were diagnosed by experimentally varying p-type a-Si:H layers (p.a-Si:H) and their application on SHJ test structures. A graded high-low p.a-Si:H emitter structure was established, demonstrating IBC-SHJ solar cell efficiency of 20.2% fabricated by complex three-step photolithography (PL) process. ☐ Thirdly, to minimize the lateral transport loss over the rear surface gap region, four different passivation structures were investigated utilizing potential industrially-scalable process. Interface defect density (Dit) and interface charge density (Qpass) for the four structures were extracted utilizing a lifetime simulator. The 2-D IBC-SHJ device simulations indicated that > 21.5% conversion efficiency is achievable on devices fabricated with our current process. However, experimental results of IBC-SHJ fabricated with simplified processes suggested that a gap passivation structure which induces inversion at n.c-Si surface should be avoided. ☐ Fourth, to validate the inversion layer effect on IBC-SHJ device, a novel three-terminal rear SHJ test structure was invented. This structure enabled an external DC bias to be applied onto one of the rear contacts for voltage-modulated laser-beam-induced-current (VM-LBIC) measurements. Additionally, device performance was analyzed before and after intentional localized laser damage to base region, which confirmed the detrimental surface inversion effect if any localized high surface recombination region exists within a diffusion length distance from emitter region. ☐ Based on these results, for a commercially viable IBC-SHJ fabrication on n-type c-Si wafer, the following recommendations can be made: 1) Avoid passivation scheme with negative charge that might form inversion layer at the rear surface; 2) Minimize area of localized defective regions with high surface recombination velocity (SRV) and; 3) Low resolution alignment patterning processes which yield gap widths ≥ 100 μm are acceptable if the gap region of IBC-SHJ has an SRV ≤ 5 cm/s.
Download or read book Development of Thin Heterojunction Solar Cells with High Open Circuit Voltage written by Tanmay Monga and published by . This book was released on 2015 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this thesis research is the development of thin silicon heterojunction solar cells with high open circuit voltage (Voc). Heterojunction solar cells are higher in efficiency than diffused junction c-Si solar cells, and they are less vulnerable to light degradation. Furthermore, the low temperature processing of heterojunction cells favour a decrease in production costs and improve cell performance at the same time. Since about 30 % of the module cost is a result of substrate cost, thin solar cells are of economic advantage than their thicker counterparts. This lead to the research for development of thin heterojunction solar cells. For high cell efficiencies and performance, it is important for cells to have a high operating voltage and Voc. Development of heterojunction cells with high Voc required a stable and repeatable baseline process on which further improvements could be made. Therefore a baseline process for heterojunction solar cells was developed and demonstrated as a pilot line at the Solar Power Lab at ASU. All the processes involved in fabrication of cells with the baseline process were optimized to have a stable and repeatable process. The cells produced with the baseline process were 19-20% efficient. The baseline process was further used as a backbone to improve and develop thin cells with even higher Voc. The process recipe was optimized with an aim to explore the limits of Voc that could be achieved with this structure on a much thinner substrate than used for the baseline process. A record Voc greater than 760mV was recorded at SPL using Suns-Voc tester on a 50 microns thick heterojunction cell without metallization. Furthermore, Voc of 754.2 mV was measured on a 50 microns thick cell with metallization by National Renewable Energy Laboratory (NREL), which is a record for Voc for heterojunction cells with metallization. High Voc corresponds to high cell efficiency and therefore, higher module voltage and power with using the same number of cells as compared to other c-Si solar cells.
Download or read book written by and published by . This book was released on 1943 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
