Unlocking the Potential of Coinage based Quaternary Chalcogenide Halides for High Temperature Thermoelectric Applications via DFT and ML

Abstract

The search for efficient materials for photovoltaic and thermoelectric applications has gained significant global attention. In this context, quaternary coinage metal mercury chalcogenide halides CuHgSCl, CuHgSBr, CuHgSI, CuHgSeBr, AgHgSBr, and AgHgSI have emerged as promising candidates. While previous studies have explored mercury chalcogenides and coin-metal halides separately, this work represents the first comprehensive investigation of these compounds by integrating both components using first-principles calculations based on density functional theory (DFT). DFT calculations were performed to analyze the structural, electronic, elastic, thermodynamic, optical, and transport properties of these materials using the WIEN2k software package. The study employed the Generalized Gradient Approximation (Perdew-Burke-Ernzerhof), Local Density Approximation (LDA), and modified Becke-Johnson (mBJ) exchange-correlation functionals to achieve accurate predictions. Furthermore, machine learning (ML) models were developed to predict the DFT-computed figure of merit (ZT) values, providing deeper insights into the thermoelectric potential of these compounds. All investigated materials exhibited semiconducting behavior. Excitonic properties, including exciton binding energy and Bohr radius, were evaluated to understand their impact on optoelectronic applications. Optical analyses, encompassing the absorption coefficient, refractive index, dielectric function, optical loss function, and reflectivity, were conducted to assess their suitability for photovoltaic applications. Additionally, thermoelectric studies were performed to evaluate their feasibility for energy conversion technologies. The integration of DFT with ML enhances predictive accuracy for ZT values, reinforcing the potential of these quaternary compounds in thermoelectric applications.