Halide perovskites are promising in the development of multijunction solar cells with enhanced power conversion efficiency (PCE) compared to that of single-junction solar cells. Besides the optimal design limitation for mitigating optical and electrical losses, amalgamating different perovskite absorber layers with optimized bandgap and thickness for a multijunction cell is a topic of concern. Herein, we demonstrate a facile and cost-effective technique called a double-sided sandwich evaporation technique for fabricating a pure and mixed-halide-based perovskite absorbing layer. By tuning the halide ratio and B-site doping, we successfully fabricated MAPbI_xBr_3–x, MAPbI_xCl_3–x, and MAPb_xSn_1–xI₃, formulating a triple-junction tandem solar cell. The solar cell configuration MAPbI_xBr_3–x (1.96 eV)/MAPbI_xCl_3–x (1.593 eV)/Si (1.12 eV) exhibited a higher PCE of 25.84% as compared with the original bandgap combination of MAPbI_xBr_3–x (1.96 eV)/MAPb_xSn_1–xI₃ (1.31 eV)/Si (1.12 eV), showing a PCE of 24.62%. Moreover, theoretical insight for the optimal perovskite thickness was gained using SETFOS by taking into account the reflection of the bottom cell, so the thickness of the top layers could be reduced. The result shows that in the thinner upper and middle perovskite cells, the light absorption ratio of each subcell can be effectively distributed, resulting in a triple-junction tandem solar cell with a PCE of 26.40%.

中文翻译：

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用于硅基三结串联太阳能电池的带隙可调钙钛矿：数值分析辅助实验研究

卤化物钙钛矿在开发多结太阳能电池方面很有前景，与单结太阳能电池相比，其功率转换效率（PCE）更高。除了减轻光学和电损耗的最佳设计限制之外，将具有优化带隙和厚度的不同钙钛矿吸收层合并到多结电池中也是一个值得关注的话题。在这里，我们展示了一种简便且经济有效的技术，称为双面夹层蒸发技术，用于制造纯和混合卤化物基钙钛矿吸收层。通过调整卤化物比例和B位掺杂，我们成功制备了MAPbI _x Br _{3– x}、MAPbI _x Cl _{3– x}和MAPb _xSn _{1– x} I ₃，配制三结串联太阳能电池。_{与MAPbI x} Br ₃的原始带隙组合相比，太阳能电池配置 MAPbI _x Br 3– _x (1.96 eV)/MAPbI _x Cl _{3– x (1.593 eV)/Si (1.12 eV) 表现出更高的 PCE 25.84% – x} (1.96 eV)/MAPb _x Sn _{1– x} I ₃(1.31 eV)/Si (1.12 eV)，PCE 为 24.62%。此外，通过考虑底部电池的反射，使用SETFOS获得了最佳钙钛矿厚度的理论见解，因此可以减少顶层的厚度。结果表明，在较薄的上层和中层钙钛矿电池中，每个子电池的光吸收率可以有效分布，从而得到PCE为26.40%的三结串联太阳能电池。