Mechanical, optoelectronic, and transport characteristics of stable halide double perovskites K2TlSbY6 (Y = Cl, Br, and I): First principles approach

Abstract

This article reported the mechanical attributes, thermodynamic properties, optoelectronic aspects, and transport characteristics of K2TlSbY6 (Y=Cl, Br, and I), for which first principles computation was employed. We have determined the crystal structure's stability by utilizing the tolerance factor. Calculations of formation energy and ab initio molecular dynamics (AIMD) are being conducted to evaluate the thermal stability of the examined materials. Mechanical stability has been predicted by calculating the elastic constants. The elastic parameters have been governed to investigate the ductility, stiffness, and anisotropy to verify the suitability of these materials for long-term reliable and flexible devices. Thermodynamic features have been ascertained, encompassing acoustic wave velocities, Debye temperature, and melting point. The analysis of electronic characteristics revealed direct band gaps of 1.35 eV, 1.05 eV, and 0.89 eV, K2TlSbCl6 K2TlSbBr6 and K2TlSbI6, respectively. The band gap value is within the acceptable range of semiconductors suitable for solar cell applications. The calculated optical parameters between 0 and 6 eV suggest the appropriateness for solar cell applications. The carrier transport characteristics, power factor, as well as the Figure of merit (ZT) have been evaluated to assess the ability of K2TlSbY6 (Y=Cl, Br, and I) materials to convert thermal energy into useful electric power. Hence, this study's detailed exploration of K2TlSbY6 perovskites provides theoretical evidence of suitability for solar cells and optoelectronic and thermoelectric devices. © 2025 Elsevier B.V.