A DFT study of the electronic structure, optical, and thermoelectric properties of halide perovskite KGeI3-xBrx materials: photovoltaic applications

The halide perovskite-based solar cells are attractive due to their excellent power conversion efficiency and low cost. The electronic structure, optical, and thermoelectric properties of Ge-based halide perovskite KGeI 3- x Br x materials ( x = 0; 1; 2; 3) are investigated based on the density functional theory (DFT). In addition, all these materials are stable in the cubic phase. These materials exhibit semiconducting behavior at normal pressure with a bandgap value lying between 0.611 and 1.126 eV when substitution of iodine atom to bromine one. The physical properties of Ge atom-based halide perovskite compounds indicate that the KGeIBr 2 material can be a good candidate for solar cell applications. As far as our knowledge, this is the first theoretical prediction of the optical properties for these compounds, which still wait for experimental confirmation.