CuIn(Se,Te)2 absorbers with bandgaps < 1 eV for bottom cells in tandem applications
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| Format: | Preprint |
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2023
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| _version_ | 1866909929018753024 |
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| author | Weiss, Thomas Paul Sood, Mohit Vanderhaegen, Aline Siebentritt, Susanne |
| author_facet | Weiss, Thomas Paul Sood, Mohit Vanderhaegen, Aline Siebentritt, Susanne |
| contents | Thin-film solar cells reach high efficiencies and have a low carbon footprint in production. Tandem solar cells have the potential to significantly increase the efficiency of this technology, where the bottom-cell is generally composed of a Cu(In,Ga)Se2 absorber layer with bandgaps around 1 eV or higher. Here, we investigate CuIn(Se1-xTex)2 absorber layers and solar cells with bandgaps below 1 eV, which will bring the benefit of an additional degree of freedom for designing current-matched 2-terminal tandem devices. We report that CuIn(Se1-xTex)2 thin films can be grown single phase by co-evaporation and that the bandgap can be reduced to the optimum range for a bottom cell (0.92 - 0.95 eV). From photoluminescence spectroscopy it is found that no additional non-radiative losses are introduced to the absorber. However, Voc losses occur in the final solar cell due to non-optimised interfaces. Nevertheless, a record device with 9 % power conversion efficiency is demonstrated with a bandgap of 0.96 eV and x=0.15. Interface recombination is identified as a major recombination channel for larger Te contents. Thus, further efficiency improvements are anticipated for improved absorber/buffer interfaces. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2308_16103 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | CuIn(Se,Te)2 absorbers with bandgaps < 1 eV for bottom cells in tandem applications Weiss, Thomas Paul Sood, Mohit Vanderhaegen, Aline Siebentritt, Susanne Applied Physics Thin-film solar cells reach high efficiencies and have a low carbon footprint in production. Tandem solar cells have the potential to significantly increase the efficiency of this technology, where the bottom-cell is generally composed of a Cu(In,Ga)Se2 absorber layer with bandgaps around 1 eV or higher. Here, we investigate CuIn(Se1-xTex)2 absorber layers and solar cells with bandgaps below 1 eV, which will bring the benefit of an additional degree of freedom for designing current-matched 2-terminal tandem devices. We report that CuIn(Se1-xTex)2 thin films can be grown single phase by co-evaporation and that the bandgap can be reduced to the optimum range for a bottom cell (0.92 - 0.95 eV). From photoluminescence spectroscopy it is found that no additional non-radiative losses are introduced to the absorber. However, Voc losses occur in the final solar cell due to non-optimised interfaces. Nevertheless, a record device with 9 % power conversion efficiency is demonstrated with a bandgap of 0.96 eV and x=0.15. Interface recombination is identified as a major recombination channel for larger Te contents. Thus, further efficiency improvements are anticipated for improved absorber/buffer interfaces. |
| title | CuIn(Se,Te)2 absorbers with bandgaps < 1 eV for bottom cells in tandem applications |
| topic | Applied Physics |
| url | https://arxiv.org/abs/2308.16103 |