DFT-enabled Electro-Optical Computations of Vacancy-ordered Metal Perovskite In2MI6 (M = Ti, Zr, Hf, and Ce) Compounds

Abstract The electro-optical properties of all inorganic vacancy-ordered perovskites In2MI6 (M = Ti, Zr, Hf, and Ce) are inspected using Density Functional Theory (DFT), within the FP-LAPW scheme using the modified Becke Johnson (mBJ) method as implemented in the WIEN2k electronic structure package. The computed energy band gaps of In2TiI6, In2ZrI6, In2HfI6, and In2CeI6 are 1.03, 1.97, 2.50, and 1.04 eV, respectively. Electronic structure analysis discloses pronounced hybridization between the In-5s and the I-5p states in the valence bands. Optical analysis indicates that In2TiI6 and In2CeI6 exhibit enhanced optical absorption in infrared, visible and ultraviolet wavelength ranges, while In2ZrI6 and In2HfI6 primarily absorb in the visible and ultraviolet ranges. Among the investigated compounds, In2CeI6 exhibits the lowest reflectivity. All materials show relatively high refractive indices, indicating strong light–matter interaction. These findings suggest that In2MI6 perovskites may be favorable candidates for photovoltaic devices and ultraviolet photodetectors.