Theoretical investigation of Cs2InBiX6 (X = Cl, Br, I) double perovskite halides using first-principle calculations

Recently, study of non-toxic double perovskites halides has become attractive due to their outstanding tunable optoelectronic properties. We present the analysis of the electronic, optical and thermoelectric properties of Bi based double perovskites halides, Cs2InBiX6 (X = Cl, Br, I) using density-functional theory (DFT). The band structures computed using Trans-Blaha modified Becke-Johnson (TB-mBJ) potential show that band gap tuning from visible (1.84 eV) to infrared (0.65 eV) energy can be resulted by changing anions from Cl to I, respectively. The optical absorption reveals maximum absorption in the ultraviolet range, while absorption edge shifts from visible to infrared energy by changing Cl with I, respectively. Various computed thermoelectric parameters are consistent with the transport parameters. Higher power factor for Cs2InBiI6 shows that narrow band gap can be comparatively more suitable for thermoelectric applications. The calculated thermoelectric and optical parameters indicate Cs2InBiX6 (X = Cl, Br, I) suitable for applications in energy conversion and solar absorbing devices.