Communicated by: FrancoisComprehensive DFT investigation of mechanical and electronic properties in Cs2AuMoX6 (X = Cl, Br) for advanced optoelectronic applications

This article investigated the mechanical, optoelectronic, and transport properties of the double perovskites Cs 2 AuMoX 6 (X = Cl, Br) using density functional theory (DFT). We confirm that both Cs 2 AuMoCl 6 and Cs 2 AuMoBr 6 adopt a stable cubic crystal structure with slightly off unity tolerance factors (τ, 0.97 and 0.95). Negative formation and Gibbs free energies were used to validate their thermodynamic stability them for practical applications. Mechanical stability within a brittle nature and anisotropic behavior were observed in consideration of elastic properties. Electronic band structure calculations indicated Cs 2 AuMoCl 6 has indirect band gaps of 1.4 eV while Cs 2 AuMoBr 6 possesses 0.8 eV direct band gaps. Evaluation of these compounds suggests that these are appropriate band gaps for their application in photovoltaic and optoelectronics. The optical properties , including light absorption, polarization, and refractive index , exhibited strong absorption in the visible region, which renders these materials good candidates for photovoltaic applications. Calculations based on the BoltzTraP code predictions suggest modest thermoelectric figures of merit (ZT) of 0.73 and 0.72 for Cs 2 AuMoCl 6 and Cs 2 AuMoBr 6 , respectively. These results demonstrate that Cs 2 AuMoX 6 compounds may find applications in sustainable energy. • Cs 2 AuMoX 6 (X = Cl, Br) compounds studied for optoelectronic applications. • Electronic properties were studied using mBJ. • Band gap energies were 1.4 eV and 0.8 eV for Cs 2 AuMoCl 6 and Cs 2 AuMoBr 6 .