First-principles investigations on the mechanical, thermal, electronic, and optical properties of the defect perovskites Cs ₂ Sn X ₆ ( X = Cl, Br, I)

Abstract

The mechanical properties, thermal properties, electronic structures, and optical properties of the defect perovskites Cs 2 SnX 6 (X = Cl, Br, I) were investigated by first-principles calculation using PBE and HSE06 hybrid functional. The optic band gaps based on HSE06 are 3.83 eV for Cs 2 SnCl 6 , 2.36 eV for Cs 2 SnBr 6 , and 0.92 eV for Cs 2 SnI 6 , which agree with the experimental results. The Cs 2 SnCl 6 , Cs 2 SnBr 6 , and Cs 2 SnI 6 are mechanically stable and they are all anisotropic and ductile in nature. Electronic structures calculations show that the conduction band consists mainly of hybridization between the halogen p orbitals and Sn 5s orbitals, whereas the valence band is composed of the halogen p orbitals. Optic properties indicate that these three compounds exhibit good optical absorption in the ultraviolet region, and the absorption spectra red shift with the increase in the number of halogen atoms. The defect perovskites are good candidates for probing the lead-free and high power conversion efficiency of solar cells.

Photoluminescence Characteristics of Sn2+ and Ce3+-Doped Cs2SnCl6 Double-Perovskite Crystals

“…The absorption spectra of 25% Ce 3+ -doped Cs 2 SnCl 6 crystals at different reaction time are shown in Figure 1. All samples have shown a same strong absorption band with an edge (Figure 1b) at 312 nm (3.97 eV), which is consistent with the absorption edge reported in the literature at 317 nm (3.9 eV) [28] and 313 nm (3.96 eV) [31], indicating this absorption band originates from the absorption of the Cs 2 SnCl 6 matrix. In addition to the absorption of the matrix, the absorption spectra have exhibited an extra weak absorption band between 312 and 390 nm.…”

An ab initio investigation of the structural, mechanical, electronic, optical, and thermoelectric characteristics of novel double perovskite halides Cs2CaSnX6 (X = Cl, Br, I) for optically influenced RRAM devices

“…The vacancy ordering in Cs 2 SnX 6 solves the problem of Sn( ii ) to Sn( iv ) oxidation, but the structural distortion still limits the true potential of tin-based perovskites. 8 Therefore, it is necessary to find new ways to enhance the stability of tin-based double perovskite halides for their true potential in RRAM devices.…”

Structural, Electronic, and Optical Properties of Cs2SnX4 (X = Cl, Br, and I) Multilayers: A Density Functional Theory Study

“…The imaginary part characterizes the energy consumed by forming the electrocouple exciton, related to the interband transition and can reflect the degree of electron receptor transition of the materials. [ 47 ] The variation curves between the imaginary part and the energy are shown in Figure 6d–f. It can be seen that under the same number of layers, the ε 2 ( ω ) of the iodine‐based compounds are higher than that of the bromine‐based compounds and the chlorine‐based compounds.…”