基于第一性原理的无铅无机钙钛矿Cs3Bi2X9(X=Cl、Br、I)光电性能表面效应研究

用基于第一性原理的密度泛函理论方法，对Cs₃Bi₂X₉(X=Cl、Br、I)的光电特性进行理论计算，并系统阐述这3种晶体的表面效应对光电性能的影响。结果表明，3种材料的光学特性由铋原子和卤素原子最外层p轨道上的价电子主导。在可见光区中，材料的吸收峰会随卤素原子序数的增加呈现红移，其中一维结构的Cs₃Bi₂Cl₉表面结构在光吸收能力上尤为特别且敏感；二维结构的Cs₃Bi₂Br₉光吸收能力会受厚度影响；零维结构的Cs₃Bi₂I₉非常稳定，且几乎不受表面特性和晶体厚度的影响。

First principles investigation about interference effects of electronic and optical properties of inorganic and lead-free perovskite Cs3Bi2X9 (X=Cl, Br, I)

The electronic and optical properties of the Cs₃Bi₂X₉ (X=Cl, Br, I) was emphatically explored theoretically by density functional theory methods based on first principles, and the influence of interference effect on the these three crystals is systematically elucidated. Our results reveal that the optical properties of the three materials are dominated by the valence electrons in p-orbitals of the Bi and halogen atoms. In the visible region, the absorption peaks have a red shift with increase of atomic number of halogen increases. The optical absorption is special and very sensitive to the interference structure on one-dimensional Cs₃Bi₂Cl₉, but not to that of two-dimensional Cs₃Bi₂Br₉ and zero-dimensional Cs₃Bi₂I₉. The thickness of the Cs₃Bi₂Br₉ film also influences the optical properties. While the zero-dimensional Cs₃Bi₂I₉ is almost unaffected by crystal thickness and surface characteristic.