Theoretical investigation of the structural stabilities, optoelectronic and thermoelectric properties of ternary alloys NaInY2 (Y = S, Se and Te) through modified Becke–Johnson exchange potential

Abstract

The ground-state physical properties of compounds [Formula: see text] [Formula: see text] are investigated using all electron full potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method. These properties include thermoelectric, optical, electronic and structural properties. The generalized gradient approximation (GGA) due to Wu Cohen (WC) exchange potential for the exchange correlation (XC) effects was used. The modified Becke–Johnson (mBJ) approximation has also been exploited for the precise measurement of XC energy. The stability of crystal structures in tetragonal chalcopyrite phase was determined by calculating the enthalpies of formation. The electronic properties have been studied by plotting the total density of states (TDOS) and partial density of states (PDOS) as well as band structures. These properties show that all compounds have direct band gaps. By exploiting the imaginary part of the dielectric function [Formula: see text], optical properties such as energy loss spectrum [Formula: see text], reflectivity [Formula: see text], extinction coefficient [Formula: see text], refractive index [Formula: see text], optical conductivity [Formula: see text] and absorption coefficient [Formula: see text] were calculated. It can be seen that threshold absorption for all compounds occurs in the lower energy regions of solar spectrum. Thermoelectric properties like figure of merit (ZT), power factor (PF), electrical conductivity [Formula: see text], thermal conductivity [Formula: see text] and Seebeck coefficient [Formula: see text], were also calculated by employing Boltz Trap code. While studying transport properties, [Formula: see text] was found to be comparatively more efficient than [Formula: see text] [Formula: see text] having maximum value of ZT. Therefore, first principle study of these chalcopyrite compounds revels that they are promising materials for photovoltaics in the infrared and visible part of solar energy.