First-Principles Scrutiny of Double Perovskite Halides A2AlAuCl6 (A = Cs, K, Rb): Potential Contenders for Renewable Energy

Double perovskite halides are potentially useful materials for producing renewable energy and are thought to meet the necessary criteria for addressing energy scarcity issues. The physical properties of A(2)AlAuCl(6) (A = Cs, K, Rb) double perovskites were investigated using DFT calculations based on the all-electron FP-LAPW approach. Exchange-correlation effects are treated via mBJ. The analyzed halides are structurally and thermodynamically stable in the cubic phase as depicted from optimized curves and negative formation energies. Furthermore, by looking of the elastic properties, the Pugh and Poisson ratios' examined values demonstrate a ductile nature. Direct bandgap of 2.10 eV, 2.08 eV and 1.98 eV is computed for Cs2AlAuCl6, Rb2AlAuCl6 and K2AlAuCl6, respectively. Furthermore, the optical properties of the studied halides are examined in the context of complex dielectric functions. These halides have the best light absorption in visible region and UV region, suggesting that they are suitable for use in photovoltaic devices. Semi-classical Boltzmann theory was employed to analyze the thermoelectric characteristics. ZT values 0.75, 0.72 and 0.62 for Cs2AlAuCl6, Rb2AlAuCl6 and K2AlAuCl6 are reported at room temperature, indicating their suitability for renewable energy devices.