Comprehensive study of the light-matter interactions, thermoelectric properties, and elastic features of quaternary materials

In this paper, we studied the structural, electronic, optical, mechanical, and thermoelectric properties of LiIn 2 CuSe 4 and LiIn 2 CuTe 4 quaternary chalcogenides, using density functional theory. Both LiIn 2 CuSe 4 and LiIn 2 CuTe 4 have direct band gaps with predictive values of 0.6 eV and 1.2 eV, respectively, revealing their semiconducting nature and relevance for optoelectronic applications. The electronic density of states indicates that the valence bands are primarily influenced by Cu-d and Se(Te)-p states, whereas the conduction bands are primarily controlled by In-s and Se(Te)-p states. Optical spectra indicated strong dielectric responses, high refractive indices, and broad absorption spectra instigating at 1.0 eV, with Te-containing materials exhibiting increased polarizability and peak absorption at lower energies because of relativistic effects. The interband transition trends and energy loss functions show substantial plasmonic resonance characteristics, making these materials potential candidates for high-frequency optoelectronic applications. The Seebeck coefficients become more negative as temperatures increase due to thermally stimulated electron transport.