A DFT exploration of the optoelectronic and thermoelectric features of a novel halide double perovskite A₂YAuI₆ (A = Rb, Cs) for solar cell and renewable energy applications

Double-perovskite halides are potentially useful materials for producing renewable energy and are thought to meet the necessary criteria for addressing energy scarcity issues. Consequently, investigations into these halides have potential uses in the fields of thermoelectric and solar cell gadgets. The physical properties of A(2)YAuI(6) (A = Rb, Cs) double perovskite halides were also investigated in the current work using DFT calculations based on the FP-LAPW approach for applications in renewable energy devices. The calculated Goldschmidt's tolerance factor and formation energy demonstrate that the explored halides are structurally and thermodynamically stable in the cubic phase. By analyzing mechanical properties, the measured Pugh and Poisson ratios demonstrate a ductile nature. In addition, we used electrical characteristics to compute bandgaps both with and without spin orbit coupling (SOC). We calculated the bandgap values of Rb2YAuI6 (E-g = 1.73 eV) and Cs2YAuI6 (E-g = 1.70 eV) using modified Becke-Johnson with spin orbit coupling (mBJ + SOC) potentials in order to get corrected bandgap values with respect to experimental data. Additionally, the optical characteristics of the halides under study were analyzed in light of their complex dielectric functions. Our computed optical parameter results clearly show that these halides have the best light absorption in the UV-visible region, indicating their suitability for use in solar cell applications. The power factor (PF), thermal conductivity, figure of merit, electrical conductivity, and Seebeck coefficient were computed to analyze transport characteristics against chemical potential, carrier concentration and temperature. Our findings can prove beneficial for further experimental research aimed at assessing A(2)YAuI(6) (A = Rb, Cs) in relation to applications using renewable energy devices.