Exploring K2MAuI6 (M = Sc, Y) Double Perovskite Halides for Solar Cells: Insights from DFT-Based Investigations

Double-perovskite halides are believed to satisfy the requirements for resolving energy scarcity concerns and can be valuable materials for generating renewable energy. Research on these halides could therefore be useful for solar cell and thermoelectric device applications. In the current work, DFT calculations based on the FP-LAPW technique were used to investigate the physical parameters of K₂MAuI₆ (M = Sc, Y) double perovskite halides for applications in renewable energy devices. The studied halides are structurally and thermodynamically stable in the cubic phase, as shown by the computed Goldschmidt’s tolerance factor and formation energy. Pugh and Poisson ratios are measured, and mechanical properties are analysed to show that the material is ductile. Furthermore, we computed bandgaps with and without spin orbit coupling (SOC) using electrical properties. To obtain corrected bandgap values with respect to experimental data, we used modified Becke–Johnson potentials to compute the bandgap values of K₂ScAuI₆(E_g = 1.92 eV) and K₂YAuI₆ (E_g = 1.98 eV). This suitable electrical bandgap results in high visible and UV light absorption. As a result, the optical characteristics exhibit a significant absorption coefficient (𝛼(𝜔) ≈ 1.5 × 105 cm − 1 for K₂ScAuI₆and 1.4 × 105 cm − 1 for K₂YAuI₆, substantial conductivity and minimum reflectivity. These materials shows brittle nature showing Pugh ratio of K₂ScAuI₆ (5.40) is stiffer than K₂YAuI₆ (2.57) also anisotrophic nature of the compounds. These halides have the best light absorption in the UV-visible range, according to our computed optical parameter data, which amply demonstrates their appropriateness for solar cell applications. Transport parameters were analysed against chemical potential, carrier concentration, and temperature using the power factor (PF), thermal conductivity, figure of merit, electrical conductivity, and Seebeck coefficient. Our findings can pave a way for the future experimental study which aimed to assess these double perovskites structures for energy applications.