First principle study of band gap tuning in Cs2InSbX6 (X = Cl, Br, I) for optoelectronic and thermoelectric applications

Abstract

Abstract In this work, density-functional theory based theoretical investigations of novel and less studied double perovskites Cs2InSbX6 (X = Cl, Br, I) are performed to analyze the structural and electronic behaviors. The electronic structures computed using PBEsol are further subjected to Tran-Blaha modified Becke-Johnson (TB-mBJ) potential, and tuning of the semiconducting direct band gap is observed as 1.77 eV, 1.07 eV and 0.35 eV for Cs2InSbX6 (X = Cl, Br, I), respectively. The structural stability is confirmed from the computed tolerance factors and enthalpy of formation. Thermodynamic stability is also revealed by the computed phonon spectra. The halogen ions based band gap tuning in Cs2InSbX6 (X = Cl, Br, I) show systematic variation of the computed optical parameters against impinging energies. The thermoelectric properties are found consistent with various transport parameters. The narrow band gap Cs2InSbI6 (0.35 eV) results comparatively high power factor. The band gap tuning based variations in the optical and thermoelectric parameters have revealed potential applications in energy absorption and conversion devices, respectively.