Efficiency of solar cells can be improved by introducing intermediate bands. However, width and occupation requirements on the intermediate bands bring challenges for materials design. In this study, we systematically investigate the electronic structure of doped CsPbX₃ (X = Cl, Br, or I). A screening in transition metals suggests that Cr and Mo doped perovskites have dispersive and half-filled intermediate bands, which is desirable for building solar cells. However, intermediate bands originated from degenerated d orbitals are easily split when the octahedral symmetry of the local chemical environment around the dopant is broken. To avoid this problem, we further perform a screening of non-transition metals aiming to generate sp orbital-based intermediate bands. It turns out that In and Ga can generate a half-filled intermediate band, which is not sensitive to the local symmetry. The estimated efficiency of In and Ga doped CsPbCl₃ at a doping concentration of 8.3% is 57.97% and 54.21%, notably higher than the Shockley–Queisser limit (40.7%). Results presented here demonstrate the potential of intermediate band engineering in photovoltaic applications.

中文翻译：

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用于太阳能电池的掺杂无机钙钛矿中的半填充中间带

通过引入中间带可以提高太阳能电池的效率。但是，中间带的宽度和占用要求给材料设计带来了挑战。在这项研究中，我们系统地研究了掺杂的CsPbX ₃的电子结构。（X = Cl，Br或I）。过渡金属的筛选表明，Cr和Mo掺杂的钙钛矿具有分散的半填充中间带，这对于构建太阳能电池是理想的。然而，当掺​​杂剂周围的局部化学环境的八面体对称性破裂时，源自简并d轨道的中间带很容易分裂。为避免此问题，我们进一步进行了非过渡金属的筛选，旨在生成基于sp轨道的中间谱带。事实证明，In和Ga可以生成一个半填充的中间带，该中间带对局部对称性不敏感。In和Ga掺杂的CsPbCl ₃的估计效率掺杂浓度为8.3％时分别为57.97％和54.21％，明显高于Shockley-Queisser限值（40.7％）。本文介绍的结果证明了中频工程在光伏应用中的潜力。