Theoretical investigation of spin–orbit coupling on structural, electronic and optical properties for CuAB2 (A = Sb, Bi; B = S, Se) compounds using Tran–Blaha-modified Becke–Johnson method: A first-principles approach

Abstract

We investigate the structural, electronic and optical properties of CuAB2 (A = Sb, Bi; B = S, Se) compounds within density functional theory (DFT) using the full potential linear augmented plane wave plus local orbital (FP-LAPW + lo) method. For these total energy calculations, exchange correlation potentials, such as Perdew–Burke–Ernzerhof (PBE) and Tran–Blaha-modified Becke–Johnson (TB-mBJ) functionals, were executed with and without spin–orbit coupling (SOC). The CuSbSe2 compound shows a direct band gap nature and the other compounds of CuSbS2, CuBiS2 and CuBiSe2 show an indirect band gap nature. The calculated bandgap of these chalcogenides are in good agreement with the reported experimental results. The inclusion of SOC causes band degeneracies, which are confirmed from the electronic structure. The mobility of electrons and holes is higher in CuSbS2 and CuBiS2, whereas electron mobility decreases and hole mobility increases from the Sb-to the Bi-containing compounds. The calculated absorption coefficients of these compounds were greater than 105 cm−1, which make them suitable for optoelectronic applications.