Electronic structure and optical properties of MAg₂X₃ (M = Cs, K, and Rb; X = Cl, Br, and I) for potential applications as a photodetector material through DFT methods

This research demonstrates to the density functional theory (DFT) based calculations on the compounds of CsAg₂I₃, CsAg₂Cl₃, CsAg₂Br₃, KAg₂Cl₃, KAg₂Br₃, KAg₂I₃, RbAg₂Cl₃, RbAg₂Br₃ and RbAg₂I₃. It evaluates the electronic structure, effective mass, total density of states (TDOS), partial density of states (PDOS), and optical properties of the MAg₂X₃ (M = Cs, K, Rb; X = I, Br, Cl) compounds. The bandgap values of CsAg₂I₃, CsAg₂Cl₃, CsAg₂Br₃, KAg₂Cl₃, KAg₂Br₃, KAg₂I₃, RbAg₂Cl₃, RbAg₂Br₃, and RbAg₂I₃ compounds have determined to be at 2.741, 2.013, 2.093, 2.097, 2.107, 2.015, 2.57, 2.133, and 2.045 eV, respectively, where CsAg2I3 2.741 eV compared experimental values (2.60 eV and 3.40 eV). The hole-effective masses for CsAg₂I₃, CsAg₂Cl₃, CsAg₂Br₃, KAg₂Cl₃, KAg₂Br₃, KAg₂I₃, RbAg₂Cl₃, RbAg₂Br₃, and RbAg₂I₃ crystals are 0.335, 0.436, 0.197, 0.884, 0.239, 0.137, 0.765, 0.141, and 0.565, respectively. These crystals have electron effective masses of 0.788, 0.520, 0.329, 0.329, 1.024, 0.614, 0.441, 1.042, 0.490, and 1.142. The UV-visible absorption spectrum study found that CsAg₂I₃ exhibits a steep absorption edge for 200–410nm, overlapped of 200–400nm of reference. Moreover, elastic constant, complex dielectric function, absorption coefficient, direct band energy, indirect band energy, and Urbach energy have been studied. The outcomes are auspicious for a future high-performance Ag halide perovskite-based photodetector material.