Electronic and Optical Features of Halide Perovskite \(\text {CsGeBr}_{3}\) Using Modified Becke Johnson Potential Within DFT

Cubic perovskite halides are considered as potential materials for photovoltaic applications. In this paper, electronic and optical properties of halide perovskite \(\text {CsGeBr}_{3}\) using full potential augmented plane wave (FP-LAPW) method are presented. An accurate exchange-correlation potential, namely modified Becke Johnson (mBJ) as embodied in Wein2k code (FP-LAPW scheme) is employed in present computations. The direct band gap at Z point (1.12 eV) arises due to valence band maximum of Ge(4s) and conduction band minimum of Ge(4p) states. Optical properties, namely real and imaginary dielectric constants, reflectivity and absorption coefficients, show its usefulness in solar cells and real component of dielectric tensor depicts its usefulness in ultraviolet detection.