Band gap engineering in halide cubic perovskites CsPbBr3−yIy (y = 0, 1, 2, 3) – A DFT study

The halide perovskites based solar cells have been attractive due to their excellent power conversion efficiency and low cost. The structural properties of lead based cesium halide perovskites CsPbBr3−yIy (y = 0, 1, 2, 3) are investigated using first principles calculations based on density functional theory. The computed electronic structure profile of CsPbBr3−yIy (y = 0, 1, 2, 3) reveals that these materials exhibit semiconducting behavior at normal pressure. The energy gap of CsPbBr3 is tuned by the substitution of iodine atom for bromine atom in CsPbBr3. 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 Pb-based halide perovskite compounds against the incident photon energy radiation indicate that these materials can be the effective candidates for the solar cell applications.