Exploring chalcogen influence on Sc2BeX4 (X = S, Se) for green energy applications using DFT

Using density functional theory, the structural, electronic, optical, and thermoelectric properties of Sc₂BeX₄ (X = S, Se) chalcogenides were investigated for energy applications. Both compounds are dynamically and thermodynamically stable with negative formation energies (−2.6 eV for Sc₂BeS₄ and − 2.2 eV for Sc₂BeSe₄). They exhibit direct band gaps: 1.8 eV (S) and 1.2 eV (Se) via TB-mBJ, suggesting strong visible light absorption. Optical parameters reveal high static dielectric constants (9 and 16.5), peak absorption at ∼13.5 eV, and reflectivity under 30 %. Thermoelectric analysis shows p-type behavior with Seebeck coefficients up to 2.5 × 10⁻⁴ V/K and electrical conductivities of 2.45 × 10¹⁸ and 1.91 × 10¹⁸ (Ω m s)⁻¹ at 300 K. The power factors reach 1.25 × 10¹¹ W/K² m s, and ZT values attain 0.80 at 800 K. Debye temperatures (420 K for S, 360 K for Se) suggest low lattice thermal conductivity. These results designate Sc₂BeX₄ as promising candidates for photovoltaic and thermoelectric applications.