First-principles study of novel CuAgX (X = S, se) semiconductors: Probing electronic, optical, thermodynamic, and thermoelectric properties
Abstract
Ternary chalcogenides are the most promising materials due to their tunable optoelectronic capabilities and extraordinarily stable thermoelectric nature. The density functional theory is employed to study the optoelectronic, thermoelectric, and thermodynamic features of novel CuAgX (X = S, and Se) semiconductors. The d orbitals of copper and silver provide a major contribution to the valence band, influencing the overall electronic structure. The electrons from the S-p states to the conduction band are permitted to move freely, increasing the material's conductivity. The VBM and CBM were positioned at the Γ-Γ point, resulting in a direct energy gap for CuAgS material. In these materials, substituting the S with Se decreases the band gap energy. The vital optical properties are investigated for their possible efficiency in optoelectronic devices. The peaks in ε1(ω) decrease and approach the negative energy region, showing metallicity in this range. The CuAgSe with stronger interatomic forces than CuAgS, raises the Debye temperature. Furthermore, CuAgSe exhibits less thermal expansion than CuAgS at 1000 K, resulting in a higher bulk modulus for the CuAgSe material. CuAgSe is somewhat more thermally conductive than CuAgS at higher temperatures.
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