Optimized Design of Back-Contact Thin-Film GaAs Solar Cells
01 Jan 2017-pp 294-296
TL;DR: In this article, the authors attempt to find the optimal design parameters for the doping concentration, thickness of the base region, the length and pitch of back electrodes by employing a validated Sentaurus TCAD model.
Abstract: In this work, we attempt to find the optimal design parameters for the doping concentration, thickness of the base region, the length and pitch of back electrodes by employing a validated Sentaurus TCAD model. Through current-voltage characteristics, one could determine best power conversion efficiency and the correlation between design parameters. While optical shadowing is eliminated in the back-contact design, it is found that electrical shading affects the cell performance and is sensitive to the electrode length and pitch. Through minimizing the length of anode, the efficiency can be elevated significantly. Moreover, a relatively wide cathode results in efficient carrier separation and superior transportation properties. Based on these simulation outcomes, we are able to optimize the design of back-contact back-junction GaAs solar cells
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TL;DR: In this article, an upper theoretical limit for the efficiency of p−n junction solar energy converters, called the detailed balance limit of efficiency, has been calculated for an ideal case in which the only recombination mechanism of holeelectron pairs is radiative as required by the principle of detailed balance.
Abstract: In order to find an upper theoretical limit for the efficiency of p‐n junction solar energy converters, a limiting efficiency, called the detailed balance limit of efficiency, has been calculated for an ideal case in which the only recombination mechanism of hole‐electron pairs is radiative as required by the principle of detailed balance. The efficiency is also calculated for the case in which radiative recombination is only a fixed fraction fc of the total recombination, the rest being nonradiative. Efficiencies at the matched loads have been calculated with band gap and fc as parameters, the sun and cell being assumed to be blackbodies with temperatures of 6000°K and 300°K, respectively. The maximum efficiency is found to be 30% for an energy gap of 1.1 ev and fc = 1. Actual junctions do not obey the predicted current‐voltage relationship, and reasons for the difference and its relevance to efficiency are discussed.
11,071 citations
"Optimized Design of Back-Contact Th..." refers background in this paper
...Since Shockley-Queisser limit was published, GaAs has always been considered to have better conversion efficiency due to its desirable bandgap [4]....
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TL;DR: In this article, the structure of an interdigitated back contact was adopted with crystalline silicon heterojunction solar cells to reduce optical loss from a front grid electrode, a transparent conducting oxide (TCO) layer, and a-Si:H layers as an approach for exceeding the conversion efficiency of 25%.
Abstract: The crystalline silicon heterojunction structure adopted in photovoltaic modules commercialized as Panasonic's HIT has significantly reduced recombination loss, resulting in greater conversion efficiency. The structure of an interdigitated back contact was adopted with our crystalline silicon heterojunction solar cells to reduce optical loss from a front grid electrode, a transparent conducting oxide (TCO) layer, and a-Si:H layers as an approach for exceeding the conversion efficiency of 25%. As a result of the improved short-circuit current (J
sc
), we achieved the world's highest efficiency of 25.6% for crystalline silicon-based solar cells under 1-sun illumination (designated area: 143.7 cm
2
).
1,061 citations
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...6% by adopting the IBC concept [2]....
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TL;DR: Green et al. as discussed by the authors presented consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules, and guidelines for inclusion of results into these tables are outlined and new entries since June 2016 are reviewed.
Abstract: Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since June 2016 are reviewed. URI: http://onlinelibrary.wiley.com/doi/10.1002/pip.2855/abstract [1] Authors: GREEN Martin A. EMERY Keith HISHIKAWA Y. WARTA W. DUNLOP Ewan LEVI Dean HO-BAILLIE Anita Publication Year: 2017 Science Areas: Energy and transport [2]
626 citations
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...3% by Kaneka Corporation [3]....
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11 May 2008
TL;DR: In this article, electrical shading losses due to recombination in the region of base busbar and fingers are analyzed using two-dimensional numerical device and network simulations, and the base doping dependence of these effects is investigated as well as the influence of the rear side passivation.
Abstract: One of the most often mentioned advantages of back-junction back-contacted silicon solar cells is that this cell structure has no shading losses, because metallization fingers and busbars are both located on the rear side of the solar cell. However, this is only true if only optical shading losses are regarded. In this work electrical shading losses due to recombination in the region of base busbar and fingers are analyzed using two-dimensional numerical device and network simulations. The base doping dependence of these effects is investigated as well as the influence of the rear side passivation. The results of the simulations are compared with EQE maps of back-junction solar cells. The influence of the busbars is quantified and the influence on the overall cell performance is discussed.
65 citations
03 Jun 2012
TL;DR: Alta Devices has fabricated a thin-film single-junction GaAs module with an independently confirmed solar energy conversion efficiency of 23.5%, under the global AM1.5 spectrum at one sun intensity as discussed by the authors.
Abstract: Alta Devices has fabricated a thin-film single-junction GaAs module with an independently confirmed solar energy conversion efficiency of 23.5%, under the global AM1.5 spectrum at one sun intensity. This represents a new record for terrestrial modules under non-concentrated sunlight. Reduced shading, intrinsic electrical interconnect, optimized optical coupling, and high efficiency solar cells all contributed to the unmatched performance of this module. Behind these attributes lies the thin and flexible nature of Alta's solar material, which enables high conversion efficiency at the cell and module levels. Because of its thin-film characteristics, this module technology has the potential to reduce the cost of solar energy generation beyond grid parity. The unique combination of a flexible form factor and high performance in outdoor environments makes this technology extremely competitive for both traditional solar installations as well as a variety of advanced photovoltaic (PV) applications.
54 citations
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...8% [5]....
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