Investigation of structural, optoelectronic and mechanical properties of halide perovskites (CsInX3; X = Br, Cl) using DFT for absorbing layer of perovskite solar cell

Halide perovskite materials belong to a fascinating novel class, and recently captured incredible attention as a leading aspirant for next-generation photovoltaic technology, because of their flexible chemistry and extraordinary optoelectronic properties, they also deliver a pattern for designing new materials for energy conversion and energy storage applications. In this study, we thoroughly explore the structural, electronic, optical and mechanical properties of the inorganic halide cubic perovskites (CsInX3; X = Br, Cl) for solar cell (SC) application, simulated under density functional theory (DFT) based WIEN2k code with PBE-GGA approximation. The optimized lattice parameters were found to be 11.67 angstrom for CsInBr3 and 11.16 angstrom for CsInCl3, respectively. The variation in the structural parameters with changing the halogen atom from Br to Cl was observed. The electronic and optical properties were computed by TB-mBJ method. These halide perovskites reveal an indirect energy bandgap quantified as 1.22 and 2.2 eV, high absorption coefficient and low reflectivity. The elastic constants (C-11, C-12 and C-44) followed the Born stability condition, and confirmed the mechanical stability. According to the Poisson ratio (nu) and Pugh's ratio (B/G), materials endorsed ductile behaviour as well exhibit anisotropic nature. Moreover, our theoretical findings suggested that the investigated materials have high absorption coefficients, high conductivity and low reflectivity, which makes them promising contender for SC applications.