Pressure Effects on the Structural, Mechanical and Opto-Electronic Properties of Potassium-Based Antiperovskites K3XO (X = Cl, Br, I) from First-Principles Investigation

Herein, using first-principle calculations and full potential linearized augmented plane wave, the structural, mechanical, and opto-electronic properties of K3XO (X = Cl, Br, and I) anti-perovskite oxides have been studied under different pressures. The structures optimization shows cell parameters very close to the available experimental and theoretical values. The mechanical stability criteria is checked by computed the elastic constants C11, C12 and C44 using the optimized data. Our results also demonstrate the ductility of the all compounds under study and their usefulness in medium-temperature devices, as they have a relatively high Debye temperature. Furthermore, the calculated band structure revealed a direct band gap for the three antiperovskites, the energy band gap values are about 4.21, 3.55 and 3.16 eV for K3ClO, K3BrO and K3IO, respectively, these values of Eg increase linearly as a function of pressure. We investigate also the optical properties of these compounds under various pressures, such as the dielectric function, absorption coefficient, energy loss function, reflectivity and refractive index, within the photon energy interval 0-25 eV, hence all the studied antiperovskites exhibit excellent optical properties, including low reflectivity and high absorption in the ultraviolet region which is good for photovoltaic applications.