Bandgap tuning, mechanical and thermoelectric properties of Cs2CuScX6 (X = Cl, Br, I) halide ion substitution for optoelectronic devices using density functional theory

Abstract

As a result of their exceptional optoelectronic properties, the growing need for renewable and sustainable energy has heightened interest in perovskites. Using DFT, mechanical, electronic, optical, and thermoelectric properties of double perovskites (DPs) Cs2CuScX6 (X = Cl, Br, I) were analyzed to gain a comprehensive understanding of these materials. To ensure structural and thermal stability, permissible values for the tolerance factor (tG) and energy of formation (ΔHf) have been determined. The bandgap values of Cl, Br, and I-based compositions are recorded as 1.9 eV, 1.80 eV, and 1.70 eV, respectively. According to their bandgap, Cs2CuScBr6 and Cs2CuScI6 DPs determine the suitability of the materials for use in ideal photovoltaic devices. Further, optical properties are investigated in the energy range 0–10 eV, indicating visible and ultraviolet absorption. The investigated compound Cs2CuScI6 exhibited the highest visible spectrum absorption, making it an ideal candidate for solar cell applications. Moreover, the BoltzTrap code have been used for thermoelectric behaviour for temperature shows that all double perovskites have high Seebeck coefficients and low thermal conductivities.