Structural, electronic, mechanical and optical properties of K2CuX (X=As, Sb) Ternary Compounds

Abstract

Efficient materials with good optoelectronic properties are required for the good performance of photovoltaic devices. In this work, we present findings of a theoretical investigation of the structural, electronic, elastic, mechanical, and optical properties of K2CuX (X=As, Sb) ternary compounds for the first time. The computations were done within density functional theory (DFT) formalism as implemented in the quantum espresso (QE) software package. Equilibrium lattice constants of 11.87 and 12.44 a.u were computed for K2CuAs and K2CuSb, respectively. The materials under study were found to be semiconducting with indirect bandgaps of 1.349 eV (K2CuAs) and 1.266 eV (K2CuSb). The valence band was found to majorly form through the hybridization of Cu-3d, As-2p, and Cu-5p orbitals in K2CuAs, and Cu-3d, Sb-3p, and Cu-5p orbitals in K2CuSb, while the conduction bands were majorly formed through hybridization of Cu-5p orbitals. The investigated materials were found to be mechanically stable at zero pressure, ductile and ionic. The optical absorption coefficient curves were found to cover the ultraviolet to visible (UV-Vis) regions thus making K2CuAs and K2CuSb good UV-Vis absorbers hence their potentiality for photovoltaic applications.