Ab-Initio Investigation of the Structural, Electronic, Mechanical, and Optical Properties of KZnX3 (X = Cl, Br) Perovskites, Using TB-mBJ

Abstract The structural, mechanical, and optoelectronic properties of cubic halide perovskites KZnX3 (X = Cl, Br) were investigated using density functional theory (DFT) within the full-potential linearized augmented plane wave (FP-LAPW) method, as implemented in the WIEN2k software. The optoelectronic properties were further examined using the Tran–Blaha modified Becke–Johnson (TB-mBJ) potential. The results indicate that both compounds are structurally stable within the generalized gradient approximation of the Perdew–Burke–Ernzerhof (PBE-GGA). KZnCl3 exhibits insulating behavior with an indirect band gap of 4.06 eV, whereas KZnBr3 exhibits semiconducting characteristics with an indirect band gap of 2.23 eV. The calculated elastic constants and formation energies confirmed that both compounds were mechanically and thermodynamically stable. Furthermore, the optical properties were analyzed in the photon energy range of 0–30 eV. Both compounds exhibit strong absorption in the ultraviolet region, indicating their potential for optoelectronic applications, particularly in ultraviolet (UV) devices.