Computational predictions of physical properties of perovskite CsGeR3 (R = F, Cl, Br, and I) materials for optoelectronic applications

• The physical characteristics of halide perovskite materials CsGeR 3 (where R = F, Cl, Br, and I) were investigated using first principle calculations . • The band structure of CsGeR 3 (R = F, Cl, Br, and I) has a 1.87, 1.62, 0.70, 0.62 eV band gap which shows the semiconductor nature. • Cauchy pressure (10.495, −3.904, 0.377, and −1.424), and hardness H v (3.024, 1.922, 2.231, and 2.044) are assessed of CsGeR 3 (R = F, Cl, Br, and I), respectively. • The optical properties of CsGeR 3 have also been examined and evaluated in order to detect the light-matter interaction. Light control or detection becomes a major problem in the modern era that can be solved by perovskite materials. For this purpose, the physical characteristics of halide perovskite materials CsGeR 3 (where R = F, Cl, Br, and I) were investigated by using first principle calculations (CASTEP) and GGA-PBE exchange correlation-functional. Pm3m (221) is the space group of the compounds, which have a cubic structure and five atoms per unit cell. Based on calculations, the band structure of CsGeR 3 (R = F, Cl, Br, and I) has a 1.87, 1.62, 0.70, 0.62 eV band gap which shows the semiconductor nature. The density of states (DOS), partial DOS, and band structure graphs in perovskite materials provide unambiguous evidence of their semiconductive properties. According to the mechanical properties, modulus (B, G, E), Poisson’s ratios (0.30, 0.17,0.25, and 0.23), Pugh’s ratio (2.128, 1.217, 1.694, and 1.540), mechanical index (1.088, 1.040, 1.314, and 1.313), Cauchy pressure (10.495, −3.904, 0.377, and −1.424), and hardness H v (3.024, 1.922, 2.231, and 2.044) are assessed of CsGeR 3 (R = F, Cl, Br, and I), respectively. The optical properties of CsGeR 3 have also been examined and evaluated in order to detect the light-matter interaction. The study involves the examination of thermodynamic factors such as compressibility, sound velocity, melting temperature, and Debye temperature. According to the physical properties, studied materials CsGeR 3 are suitable for optoelectronic applications.