Abstract
The full-potential linearized augmented plane wave (FP-LAPW) approach was employed to explore the elec-tronic, structural, thermoelectric (TE) and optical aspects of Al2HgS4 and Al2MgS4 cubic spinels. The tolerance factor (tau) for Al2XS4(X = Hg, Mg) compounds is 0.9, which revealed the structure of mentioned compounds in cubic phase. Results indicated that Al2XS4 (X=Hg, Mg) are semiconductors with direct band gap (Eg) of 2.11 and 3.69 eV, correspondingly at Gamma symmetry points. Moreover, In optical properties, The absorption region extends from visible to ultraviolet light, which makes both spinels ideal for optoelectronics devices. Furthermore, the BoltzTrap code was used to investigate thermoelectric (TE) properties, which revealed that as the temperature rises, the thermal conductivity (k/tau), electrical conductivity (sigma/tau), and power factor (PF) increase, but the Seebeck coefficient (S) reduced. The magnitude of figure of merit (ZT) is 0.78 and 0.74 for Al2HgS4 and Al2MgS4, correspondingly. ZT revealed that studied compounds are suitable for TE devices for the source of energy.