Study of narrow band gap double perovskites (Sr/Ba)2BB'O6 (B = In, Tl, B' = Sb, Bi) for optical, thermoelectric, and mechanical properties

Abstract

The double perovskites (DPs) have recently been realized as emerging materials in the field of optoelectronics owing to their remarkable and diverse electronic, optical, thermoelectric, and mechanical properties. Herein, we have comprehensively investigated some of the narrow bandgap DPs for instance; Ba2InBiO6, Ba2TlSbO6, and Sr2TlBiO6 based on DFT-simulation using Wien2k code, and modified Becke and Johnson (mBJ) potential. The reported tolerance factor show structural and formation energy thermodynamic stabilities. Moreover, the narrow bandgaps 0.125 eV, 0.307 eV, and 0.350 eV are computed for Ba2InBiO6, Ba2TlSbO6, and Sr2TlBiO6, respectively. Further, the absorption of light and optical behavior is appropriate for the infrared region and therefore the studied compounds could have potential practical applications in infrared sensors, and surgical equipment. Furthermore, the thermoelectric characteristics are discussed in detail based on various factors e.g., thermal to electrical conductivity ratio, a figure of merit (ZT), and Seebeck coefficient. It was found that ZT has high values at lower temperatures however its value starts decreasing with the temperature rise.