Quasi-rigid-band behavior and band gap changes upon isovalent substitution in Cs$_3$Bi$_2$Br$_{9-x}$I$_x$
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866913787453374464 |
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| author | Butorin, Sergei M. |
| author_facet | Butorin, Sergei M. |
| contents | The recently introduced approach, combining the parameter-free Armiento-Kümmel generalized gradient approximation exchange functional with the nonseparable gradient approximation Minnesota correlation functional, was used to calculate the electronic structure of the Cs$_3$Bi$_2$Br$_{9-x}$I$_x$ series within density functional theory including the spin-orbit coupling. The changes in the band gap size and its dependence on the $x$ value was investigated. The band gap was found to be of indirect nature and it decreases with increasing I content as long as the system is in the $P\overline{3}m1$ phase. A clear non-linear dependence of the band gap size on $x$ was established which is in qualitative and quantitative agreement with reported experimental data. The quasi-rigid band behavior of the states in the valence and conduction bands of the $P\overline{3}m1$ phase is discussed since no significant changes in the shape of the total density of unoccupied states were observed upon the isovalent substitution. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_07641 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Quasi-rigid-band behavior and band gap changes upon isovalent substitution in Cs$_3$Bi$_2$Br$_{9-x}$I$_x$ Butorin, Sergei M. Materials Science The recently introduced approach, combining the parameter-free Armiento-Kümmel generalized gradient approximation exchange functional with the nonseparable gradient approximation Minnesota correlation functional, was used to calculate the electronic structure of the Cs$_3$Bi$_2$Br$_{9-x}$I$_x$ series within density functional theory including the spin-orbit coupling. The changes in the band gap size and its dependence on the $x$ value was investigated. The band gap was found to be of indirect nature and it decreases with increasing I content as long as the system is in the $P\overline{3}m1$ phase. A clear non-linear dependence of the band gap size on $x$ was established which is in qualitative and quantitative agreement with reported experimental data. The quasi-rigid band behavior of the states in the valence and conduction bands of the $P\overline{3}m1$ phase is discussed since no significant changes in the shape of the total density of unoccupied states were observed upon the isovalent substitution. |
| title | Quasi-rigid-band behavior and band gap changes upon isovalent substitution in Cs$_3$Bi$_2$Br$_{9-x}$I$_x$ |
| topic | Materials Science |
| url | https://arxiv.org/abs/2504.07641 |