Structural and optical investigations of ZnGa2X4 (XÂ =Â S, Se) compounds for solar photovoltaic applications

In this paper, we have performed electronic and optical investigations for ternary bulk chalcopyrite's ZnGa2X4 (X = S, Se) to explore their utility as solar cell materials. The electronic structure computations presented over here, revealed direct band gap for these compounds. Detailed analysis of these structural results is performed using total and partial density of states. The optical investigations such as absorption spectra, dielectric tensors, refractivity, reflectivity, energy loss and conductivity of both compounds are performed to validate their applicability for solar photovoltaic and other optoelectronic applications. The intense nature of absorption curves observed in the solar energy region (0-5 eV), supports the possible utilization of these materials for the same. All the computations are performed using the different exchange and correlation functions namely, Wu-Cohen generalized gradient approximation (WC-GGA), Perdew et al. (PBE-sol) and the most accurate modified Becke and Johnson (mBJ) potentials within the frame work of density functional theory.