Optoelectronic and thermoelectric properties of spinel chalcogenides HgLa2X4 (X=S and Se): A first-principles study

We investigated spinel chalcogenides HgLa₂(S/Se)₄ by using density function theory, and scrutinized the structural, optical, electrical, mechanical and thermoelectric transport characteristics of HgLa₂(S/Se)₄ spinel chalcogenides. The enthalpy of formation, energy of cohesion, and energy volume optimum plots were used to obtain the stability as well as the perfect ground state of these materials. The ductility of these materials was the best illustrated with the help of Poisson's and Pugh's ratios. The band gap results were obtained using Trans and Blaha modified Becke-Johanson potential (TB-mBJ). Both the materials present semi-conducting nature with direct band gap equal to 1.449 and 0.892 eV respectively for HgLa₂S₄ and HgLa₂Se₄. Calculations were also made for optical characteristics with the values of dielectric function, absorption coefficient, optical conductivity, reflectivity, and refractive indices. According to the findings, both of these materials are suitable for infrared optoelectronic applications. These materials were found to have promising optoelectronic and thermoelectric applications after their optical properties and transport aspects were evaluated. Despite tiny levels of temperature conductivities, substantial amounts of power conductivities, the figure of merit (more than unity), as well as Seebeck coefficients all point to the potential use of both the materials in thermoelectric power generators.