HSE03 functional-based DFT screening the multifaceted properties of inorganic halide perovskites ABI3 (a = ca, Ba; BK, Rb) for cutting-edge optoelectronic applications

Halide perovskites have gained immensive focus in diverse scientific and technological domains because of their inherent structural flexibility. Herein, first-principles calculations were carried out within the CASTEP framework using the HSE03 hybrid functional to investigate the structural, electronic, elastic, bond population, and optical properties of ABI₃ (A = Ca, Ba; B = K, Rb) inorganic halide perovskites. All compounds exhibit semiconducting behavior with band gap values of 2.07 eV for CaKI₃, 1.63 eV for CaRbI₃, 0.936 eV for BaKI₃, and 3.202 eV for BaRbI₃, while their negative formation energies and phonon dispersion spectra further support the dynamic stability. However, CaKI₃ stand out promising candidate based on its favorable dielectric function, high absorption coefficient, and strong optical conductivity. Moreover, mechanically derived parameters from elastic constants (C₁₁, C₁₂, and C₄₄) indicate the mechanical stability and ductility, as demonstrated by their Poisson's ratios (>0.25), Pugh's ratios (>1.75), and adherence with Born criteria. These results suggested that considered ABI₃ (A = Ca, Ba; B = K, Rb) inorganic halide perovskite hold significant potential for modern optoelectronics applications.