Electronic structure and optical properties of CsSnI3−yBry (y = 0, 1, 2, 3) perovskites

Abstract

The halide perovskites-based solar cells have been attractive due to their excellent power conversion efficiency and low cost. The structural, electronic and optical properties of Sn-based cesium halide perovskites CsSnI[Formula: see text]Br[Formula: see text] (y = 0, 1, 2, 3) are investigated based on density functional theory. The computed electronic structure profile of CsSnI[Formula: see text]Br[Formula: see text] (y = 0, 1, 2, 3) reveals that these materials exhibit semiconducting behavior at normal pressure. The energy gap of CsSnI3 is tuned by the substitution of bromine atom for iodine atom. Also, it is found that the energy gap values of these materials decrease with increase in pressure and a semiconductor to metallic phase transition is observed at high pressure. The optical properties of these Sn-based halide perovskite compounds against the incident photon energy radiation indicate that these materials can be effective candidates for solar cell applications. The dynamical stability of these perovskites is analyzed by phonon dispersion curve.