First-Principles Calculations of Halide Double Perovskite K2InBiX6 (X = Cl, Br, I) for Solar Cell Applications

Our method comprises analyzing the optical and electrical characteristics of K₂InBiX₆ (X = Cl, Br, I) halides using DFT. Through analysis of the band structures using the modified Becke-Johnson potential (mBJ), we discovered that the band gap is dramatically shifted from the visible to the infrared spectrum when the anions are changed from Cl to I within the range of 1.5 to 0.9 eV bandgap. The optical absorption in the visible region is increased and the absorption edge is shifted from the visible to the infrared spectrum when Cl is substituted with Br and I. In comparison to K₂InBiBr₆ and K₂InBiCl₆, the higher Seebeck coefficient in K₂InBiI₆ indicates that a smaller bandgap is more appropriate for thermoelectric applications. Our computational study of the thermoelectric and optical characteristics suggests that K₂InBiX₆ is a good fit for solar cell devices.