Free energy loss analysis of heterojunction solar cells |
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Authors: | Nils Brinkmann Gabriel Micard Yvonne Schiele Giso Hahn Barbara Terheiden |
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Affiliation: | Department of Physics, University of Konstanz, P.O. Box X916, 78457 Konstanz, Germany |
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Abstract: | For the first time we present a free energy loss analysis (FELA) of heterojunction silicon solar cells (HSSC) to study the influence of the intrinsic buffer layer thickness (tbuffer) on the solar cell efficiency (η). The main advantage of the FELA is that the impact of various loss mechanisms can be directly expressed in absolute percentage of η. Furthermore, it is possible to extract the magnitude of every loss for each region of the solar cell. All quantities required to perform the FELA are obtained by the simulation software AFORS‐HET. The FELA yields an optimum efficiency of 21.24% for tbuffer ≈ 5 nm. The efficiency drop for tbuffer £ 5 nm is ascribed to a lower maximum usable generated power ΦG(22.84% @ 2 nm, 23.98% @ 5 nm). Lower efficiencies for tbuffer ³ 5 nm are attributed to the increased transport loss of holes in the intrinsic buffer layer (0.05% @ 2 nm, 0.65% 8 nm). The η values yielded by the FELA are in agreement with the ones calculated by AFORS‐HET, demonstrating the applicability of the FELA to the HSSC concept. Therewith, we demonstrate that the FELA can be employed to obtain a deeper understanding of the HSSC concept. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) |
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Keywords: | loss analysis simulations heterojunction solar cells free energy |
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