Abstract We present DFT study on hypothetical 3D all-inorganic metal halide perovskites CsBiPbX6 (X = Cl, Br, I). According to the calculations, the perovskites form cubic, orthorhombic, monoclinic, and trigonal phases which are all direct bandgap semiconductors. Typical of metal halide perovskites, valence bands of the considered species are composed of halide anions’ occupied p-orbitals. Their conduction bands contain about equal contributions from vacant p-orbitals of both Bi3+ and Pb2+ cations. Electronic bandgaps of the studied perovskites range from 1.05 eV to 2.10 eV, whereas estimated optical bandgaps of their cubic F43m phase equal 1.50 eV (CsBiPbI6), 1.87 eV (CsBiPbBr6), and 2.40 eV (CsBiPbCl6). The perovskites’ electronic properties can be fine-tuned by mixing of halide anions. Mixed-halides CsBiPbBrnI(6-n), (n = 1–5) are considered here as an example. Majority of these compounds are direct bandgap semiconductor as well with electronic bandgaps falling in the range [1.08–1.72] eV. Their optical bandgaps are expected to exceed the corresponding electronic ones by a few tenths of an electronvolt. Owing to relatively low lead content, direct electronic transitions, and remarkable tunability of electronic properties the proposed materials may find applications in photovoltaics.

中文翻译：

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新型 3D 光敏直接带隙钙钛矿 CsBiPbX6：从头算结构和电子特性

摘要 我们提出了关于假设的 3D 全无机金属卤化物钙钛矿 CsBiPbX6 (X = Cl, Br, I) 的 DFT 研究。根据计算，钙钛矿形成立方相、正交相、单斜相和三角相，都是直接带隙半导体。典型的金属卤化物钙钛矿，所考虑物种的价带由卤化物阴离子占据的 p 轨道组成。它们的导带包含来自 Bi3+ 和 Pb2+ 阳离子的空 p 轨道的大约相等的贡献。所研究的钙钛矿的电子带隙范围从 1.05 eV 到 2.10 eV，而其立方 F43m 相的估计光学带隙等于 1.50 eV (CsBiPbI6)、1.87 eV (CsBiPbBr6) 和 2.40 eV (CsBiPbCl6)。钙钛矿的电子特性可以通过混合卤化物阴离子进行微调。混合卤化物 CsBiPbBrnI(6-n), (n = 1–5) 在这里被视为一个例子。这些化合物中的大多数都是直接带隙半导体以及电子带隙落在 [1.08-1.72] eV 范围内。预计它们的光学带隙将超过相应的电子带隙十分之几电子伏特。由于相对较低的铅含量、直接的电子跃迁和电子特性的显着可调性，所提出的材料可能会在光伏领域得到应用。