Investigation of perovskite KGeBr3 for use in perovskite-Si tandem solar cell using DFT approach

Solar renewable energy is the need today to combat the high decline rate of storage of fossil fuels. Paper presents electronic and optical analysis of KGeBr₃ by employing Density Functional Theory using mBJ potential in FP-LAPW environment using WIEN2K package. Computed energy gap of KGeBr₃ found 0.54 eV in the reciprocal lattice space. Absorption coefficient analysis manifests that KGeBr₃ material absorbs light in the visible spectrum and Si absorbs light in the ultraviolet spectrum. Hence, it is predicted that perovskite KGeBr₃ material will have strong potential to work as a high efficient solar cell in tandem perovskite-Si configuration.