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CsPbX3 inorganic perovskites have gained widespread attention due to the excellent stability and interesting properties. This article focuses on the exciton properties of CsPbBr3 with different layer numbers. The electronic and optical properties are also investigated. The distribution of excitons (electrons and holes) is closely related to the density of states near the bottom of the conduction band and the top of valence band. Based on potential analysis, it is found that the excitons are affected by the bromine atoms. With increasing thickness, the bandgap decreases and the absorption spectrum that appears obviously in the bandgap moves to lower energy, the maximum binding energy of bright excitons becomes smaller, and the corresponding Bohr radius becomes larger. These results provide a theoretical basis for the theoretical and experimental studies of CsPbBr3 and provide some guidance for the design of optoelectronic devices.

The Cs2SnX4 (X = Cl, Br, and I) halide perovskites are currently emerging as a new family of 2D materials and promising candidates for photovoltaic and optoelectronic devices. Herein, the structural, electronic, and optical properties of the Cs2SnX4 multilayers (Ms) with 1–3 layers are investigated by density functional theory (DFT). The structural properties show that the bond length variation of Cs2SnX4 is closely related to surface effects. The Cs2SnCl4 Ms have the lowest formation energies and the best stability, and the formation energies decrease and the stability improves when the number of layers increases. The electronic properties show that the direct‐bandgap semiconductor Cs2SnX4 Ms bandgap values (Cl: 1.513–1.188–0.932, Br: 1.342–1.015–0.862, I: 1.198–0.903–0.729) decrease with the change from 1 to 3 layers and from Cl to I. The p orbitals of X atoms and 5p orbitals of Sn atoms are mainly involved in conduction. The optical properties indicate that Cs2SnX4 Ms achieve coverage and adjustability in the near‐infrared and visible‐light ranges. The calculations provide a fundamental theoretical basis for the research and application of Cs2SnX4.

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