A computational approach to study optoelectronic thermoelectric behavior of ternary zinc Aluminates ZnAl2X4 (X = S, Se, Te) for low-cost energy technologies

Abstract

The search for cost-effective, high-performing energy technologies has accelerated the study of new materials possessing exceptional thermoelectric qualities. This work uses a computational method to explore the thermoelectric and optoelectronic properties of ternary compounds with the goal of finding promising candidates for energy-related uses. We employ Boltzmann transport equations and density functional theory (DFT) to methodically examine the optical characteristics, electronic structure, and thermoelectric performance of ZnAl₂X₄ (X = S, Se, Te) compounds. The band profile reveals a semiconducting nature with direct band gap of 3.41, 3.31, 2.61 eV in ZnAl₂S₄, ZnAl₂Se_{4 and} ZnAl₂Te₄. Further, the plots of electron localization functions (ELF) provide a clear illustration of the significant hybridization of Zn-d, Al-p, and X-p states observed from the density of states. High values of optical absorbance and conductivities in UV regions confirm strong luminescent properties. The reflectance shows a red shift with increasing size and atomic no. of the chalcogenide atoms. Further, thermoelectric efficiency for these materials is estimated by calculating figure of merit values of 0.97, 0.77 and 0.716 at room temperature. Present study suggests these materials’ suitability for next-generation optical and thermoelectric devices.