First-principles calculations to investigate structural, electronics, optical and elastic properties of Sn-based inorganic Halide-perovskites CsSnX₃ (X = I, Br, Cl) for solar cell applications

The structural, electronic, optical, and elastic properties of cubic inorganic-perovskites CsSnX₃ (where X = I, Br, Cl) based on Sn were investigated using a Density Functional Theory (DFT) based Cambridge Serial Total Energy Package (CASTEP) code with Ultrasoft Pseudo-Potential (USP) plane-wave and Perdew-Burke-Ernzerhof (PBE) exchange–correlation function of the Generalized Gradient Approximation (GGA). The calculated lattice parameters and band gap match well with the previous studies. These materials have a direct and narrow band gap and can be utilized to increase the conductivity. All the compounds are found anisotropic and ductile according to the anisotropic factor and Poisson's ratio, respectively. These compounds have high optical absorption and conductivity, according to optical characteristics, and have been discovered to be a promising contender for solar cell applications. Due to their direct band gap, these materials are also suitable for light-emitting diodes (LED) and other reflectivity purposes. CsSnI₃ may be a better choice for LEDs and solar cells due to its narrower band gap.