Study of electronic, mechanical, optical, and thermoelectric aspects of Li2ScCuZ6 (Z = Cl, Br, I) for solar cells and thermoelectric applications

Abstract

Double perovskite (DP) halides are emerging materials for solar cells and thermoelectric (TE) devices due to their stable structures and broad absorption bands in the visible region. Therefore, in the current article, electronic, mechanical, optical, and transport aspects of Li2ScCuZ6 (Z = Cl, Br, I) are elaborated comprehensively. Tolerance and octahedral factors have been calculated to ensure cubic phase stability, while formation energy has been reported to assess thermodynamic stability. The mechanical aspects are analyzed through Born stability criteria, ductility, hardness, and Debye temperature. The analysis of band structures reveals the band gaps 1.68 eV, 1.63 eV, and 1.54 eV for Cl, Br, and I anion-based DPs. The band gap tuning moves the absorption band to the visible region. The electron transition recombination exists between the valence and conduction bands through the 3d-states of Cu and Sc. Moreover, optical behavior has been explained by dielectric constants, absorption, photoconductivity, reflectance, and energy loss parameters. The substantial absorbance and low energy loss in the visible spectrum are anticipated to have potential for solar cell applications. The thermoelectric aspects against temperature and chemical potential have been evaluated, which show the significant Figure of merit (0.76, 0.78, and 0.80) at room temperature. Therefore, large absorption bands in the visible region and thermoelectric performance at room temperature increase their importance for energy harvesting applications.