<p>Optoelectronic and Thermoelectric Properties of High Performance ALSB Semiconductors</p>

<span>This study presents a comprehensive first-principles investigation of the optoelectronic and thermoelectric properties of AlSb in its cubic and hexagonal phases. Structural optimization was performed using the SCAN meta-GGA functional, while the electronic and optical properties were evaluated within the modified Becke-Johnson potential combined with the Hubbard correction (mBJ + U) framework, which provides an improved description of the electronic structure and band-gap values in closer agreement with available experimental data than conventional GGA and SCAN approaches. Both AlSb phases are found to be quasi-direct band-gap semiconductors, with calculated band gaps of 1.71 eV for the cubic phase and 1.50 eV for the hexagonal phase. Additional mBJ + SOC calculations reveal a noticeable reduction of the band gap due to relativistic effects associated with Sb atoms, while preserving the overall electronic-band topology. The optical response reveals strong absorption in the visible and ultraviolet spectral regions, moderate reflectivity, and high refractive indices, indicating pronounced light-matter interaction characteristic of III–V semiconductors. Owing to its reduced symmetry and narrower band gap, the hexagonal phase exhibits enhanced absorption at lower photon energies and a red-shifted optical response compared with the cubic polymorph. Thermoelectric transport calculations demonstrate large negative Seebeck coefficients, thermally activated carrier generation, and a systematic increase in the power factor with carrier concentration for both phases. The cubic phase exhibits higher power-factor values owing to its more dispersive electronic bands and enhanced electrical transport coefficients, whereas the hexagonal phase benefits from lower thermal conductivity, which is advantageous for thermoelectric applications at elevated temperatures. These results establish AlSb as a multifunctional semiconductor with tunable optoelectronic and thermoelectric properties and provide valuable insight into the relationship between crystal structure, electronic structure, and functional performance in III–V semiconductors.</span>