DFT aided comparative screening of mechanical, optoelectronic, and transport properties of double perovskites Cs2ScAuX6 (X = Cl, Br, and I) for green energy applications

[Display omitted] •Cs2ScAuCl6, Cs2ScAuBr6 and Cs2ScAuI6 have FCC cubic structure (Fm3.m space group).•The evaluation of elastic properties confirmed the ductile behavior, anisotropy, and mechanical toughness.•Cs2ScAuCl6, Cs2ScAuBr6 and Cs2ScAuI6 exhibit indirect band gaps of 1.6, 1.5, and 1.05 eV, respectively.•Optical investigations indicate that these materials are capable of absorbing energy within the visible and ultraviolet spectra.•These materials are expected to exhibit greater performance in thermoelectric devices having ZT values of 0.81, 0.76, and 0.83, respectively. A comprehensive comparative analysis has been performed to investigate the Cs2ScAuX6 (X = Cl, Br, and I) employing density functional theory. The WIEN2k code has been applied to optimize the structural arrangement of perovskites and calculate various aspects such as mechanical, optoelectronic, and transport characteristics. The results demonstrated that these perovskite compounds had both structural and chemical stability. The analyzed elastic characteristics of the Cs2ScAuX6 have shown that these compounds are mechanically stable, have anisotropy toughness, and provide durability against plastic deformation. The electronic characteristics are determined precisely and accurately using the Trans-Blaha-modified Becke-Johnson (TB-mBJ) potential. The compounds Cs2ScAuCl6, Cs2ScAuBr6, and Cs2ScAuI6 are semiconductors and have band gaps of 1.6, 1.5, and 1.05 eV, respectively, demonstrating an indirect nature. An investigation examines the optical characteristics within the energy range of 0–6 eV. The chosen materials reveal transparency in the lower energy spectrum of incoming photons and exhibit significant absorption and transmission of light. Therefore, it can be inferred that Cs2ScAuX6 materials possess optical properties that make them suitable for utilization in photovoltaic devices. Further, these materials elaborate substantial electrical conductivity, power factors, and figures of merit (ZT), making them efficient thermoelectric resources. At last, these results would be advantageous for experimental researchers and have also unveiled the substantial capability of these substances to be utilized in solar energy harvesting and thermoelectric devices.