Exploring the potential of inorganic cubic halide perovskites RbSrM3 (M=Cl, Br) for advanced optoelectronic applications: A DFT study

Halide perovskites, being a large family attained researchers focus for multiple targets because of their outstanding properties and flexible chemistry. In this study, density functional theory (DFT) based on WIEN2K code were utilized, to thoroughly explore the structural, electronic, optical, and mechanical properties of inorganic cubic halide perovskites, i.e.; RbSrM3 (M = Cl, Br) for optoelectronic applications. Variation in the lattice parameters and unit cell volume were observed, as a result of halogen atom substitution from Cl with Br. Subsequently, the electronic characteristics certify the direct bandgap nature, with bandgap values of 7.73 eV for RbSrCl3 and 6.79 eV for RbSrBr3, respectively. Optical properties proposed the high optical absorption, high conductivity, and low reflectivity. Further analysis into the mechanical properties, including bulk modulus (B), shear modulus (G), young modulus (E), anisotropic factor (A), Poison's ratio (ν), and Pugh's ratio (B/G), comply the near ductility, stiffness, and elastically anisotropic behavior, confirmed the stability and reliability of the designed compound. Debye temperature (θD), showing high capability to withstand against heat produced by lattice vibrations, further associated the thermodynamic stability that support the formation energy calculations. Based on the findings, it is confidently suggested that investigated halide perovskite materials i.e.; RbSrM3 (M = Cl, Br), are promising candidates for next-generation photodetectors and optoelectronic devices.