JETP Letters: issues online

In this study, we employed the full potential linearized augmented plane wave technique based on density functional theory applied in the WIEN2k code to examine the structural, elastic, electrical, optical, and thermoelectric properties of double perovskite K₂InBiX₆ (X = Cl, Br) compounds. Tolerance factor, formation energy, and phonon dispersion all confirm structural stability. Using the exchange correlation generalized gradients approximation, and modified Becke-Johnson, the electronic characteristics were calculated. The calculated bandgaps using TB-mBJ potential for K₂InBiX₆ (X = Cl, Br) compounds are 1.81 and 1.29 eV, respectively, indicating that the compounds under study are semiconductors. Both materials exhibit thermodynamic stability, as evidenced by an analysis of their elastic and mechanical properties. We estimated the optical properties in terms of the real and imaginary dielectric functions, refractive index, reflectivity and absorption coefficient reflecting their application in photovoltaic and optoelectronic devices. In the temperature range 200-800 K, the thermoelectric properties compounds, such as electrical conductivity, Seebeck coefficient, thermal conductivity, and power factor, have been analyzed. The compound has a positive Seebeck coefficient in this temperature range, indicating that holes are the majority charge carriers and that the material is p-type. The high-power factor of studied compounds suggests its potential application in thermoelectric devices.