Insights into the optoelectronic and thermoelectric properties of defect chalcopyrites XAl2Se4 (X = Zn, Cd, and Hg): A density functional theory approach

Abstract

In the current study, we employed the full-potential linearized augmented plane wave plus local orbitals (FP-LAPW + lo) approach within the density functional theory (DFT) to investigate the physical properties of Defect Chalcopyrites XAl2Se4 (X = Zn, Cd, and Hg). Calculations yield precise structural and electronic parameters in good agreement with experimental data, revealing all three compounds as direct wide-bandgap semiconductors. The modified Becke-Johan potential (TB-mBJ) method accurately estimates energy gaps, which increase with decreasing lattice constants. The calculated values are 3.34 eV, 3.12 eV, and 2.30 eV for ZnAl2Se4, CdAl2Se4, and HgAl2Se4, respectively. The optical properties, including dielectric function and absorption coefficient, indicate potential applications in visible and ultraviolet optoelectronic devices. The high anisotropy of these materials further enhances their suitability for a range of linear and nonlinear optical applications. Moreover, ZnAl2Se4 exhibits the highest Seebeck coefficient at room temperature. The positive Seebeck coefficient confirmed the p-type behavior of the studied compounds. The highest observed power factor demonstrates optimal thermoelectric performance for these materials. High electrical conductivity values suggest their suitability as effective electrical conductors, especially at elevated temperatures. This study encourages further research into defect chalcopyrites for applications in optoelectronics and thermoelectric energy conversion.