DFT study of structural, electronic, and optical characteristics of Cs2RbAuM6 (M = Cl, F)

Using density functional theory (DFT), this study investigates the structural, electronic, optical, and thermoelectric properties of halide double perovskites Cs₂RbAuM₆ (M = Cl, F). The aim is to assess the viability of these materials for next-generation optoelectronic and energy applications and to elucidate the influence of halogen substitution on their multifunctional behavior. Structural stability was verified using the Birch-Murnaghan equation of state combined with total energy minimization. Electronic band structure calculations reveal spin-polarized semiconducting behavior, with halogen choice significantly affecting band gaps. Optical studies demonstrate strong ultraviolet absorption, particularly in Cs₂RbAuCl₆, suggesting potential use in UV detectors. Thermoelectric analysis indicates that Cs₂RbAuF₆ exhibits a higher Seebeck coefficient and figure of merit (ZT), highlighting its promise for thermal energy harvesting. These results underscore the tunability of these materials for tailored applications.