Unveiling the functional properties of Rb based halide double perovskites via first principle calculations

The rapid escalation in overall energy demand and the urgent need for sustainable alternatives have accelerated research on halide double perovskites (HDPs) which have potential for energy conversion and optoelectronic applications. In present work, we have conducted a comprehensive first principle investigations on Rb₂AgMBr₆ (M = As, Co, Rh) compounds to evaluate their structural, and functional properties. The stability of these compounds have been examined with octahedral factor, Goldschmidt and new tolerance factor. The value of octahedral, Goldschmidt and new tolerance factors are found to be in between 0.48 and 0.50, 0.92-0.93 and 3.97-3.99 respectively. The formation energy of the studied compounds are found within the energy range -1.03 to -1.18eV which confirms the stability of these HDPs. Mechanical analysis indicates that these materials remain stable under applied pressures and strains. Electronic band structure and optical absorption studies suggest favorable energy gap ranges between 1.42 and 1.53eV and significant absorption in the visible range which make these DPs suitable for optoelectronic applications. Additionally, phonon dispersion and ab initio molecular dynamics (AIMD) simulations are also performed to confirm the dynamical and thermal stability of studied perovskites. Thermoelectric transport properties reveal promising performance for energy harvesting, offers valuable insights into the multifunctional behaviour of Rb₂AgMBr₆ HDPs, and supports their potential use in next-generation sustainable technologies.