DFT based simulation for semiconductor behavior of XGeCl3 (X=K, Rb) halide perovskites under hydrostatic pressure

Abstract The structural and electronic properties of XGeCl₃ (X = K, Rb) were calculated under hydrostatic pressure from 0 to 8 GPa using density functional theory (DFT). It is used Projector Augmented Wave (PAW) method which describes electron-ions interaction. The exchange-correlation functional energy functional was computed using Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). It was observed that the lattice parameters and bond length of XGeCl₃ (X = K, Rb) compounds examined by introducing hydrostatic pressure range of 0 to 8 GPa decreased. The band gap of XGeCl₃ (X = K, Rb) compounds reveals the direct band gap at the R symmetry point in the Brillouin Zone. These compounds exhibit semiconductor behavior with narrow band gap at ambient pressure. The electronic band gap (Eg) of KGeCl₃ and RbGeCl₃ is calculated 0.5802 (eV) and 0.657 (eV) at 0 GPa, respectively. As expected, hydrostatic pressure reduced the band gap, and the metallic character was detected at 5 GPa for both structures. The compounds described in this paper were evaluated for the visible energy area, which might be viable candidates for optoelectronic applications, and turned out to exhibit the direct electronic band.