Electronic and optical properties of Sb₂Se₃ and Sb₂S₃: theoretical investigations

Abstract In recent developments in solar energy research, Sb 2 Se 3 and Sb 2 S 3 emerge as environment friendly photovoltaic absorber materials, distinguished by their narrow bandgap and high absorption coefficient. Theoretical investigations to determine the electronic structure, effective density of states, dielectric function, and absorption coefficient of Sb 2 Se 3 and Sb 2 S 3 crystals have been performed using first-principle methods. The results reveal band gap values of about 0.822 and 1.757 eV (PBE method), 1.114 and 1.778 eV (HSE06 method) for Sb 2 Se 3 and Sb 2 S 3 , respectively. The valence band and conduction band edges are primarily formed by Se 4 p , S 3 p , and Sb 5 p hybridized orbitals. The effective density of states (DOS) exhibit magnitudes on the order of 10 19 cm −3 . Notably, anisotropic characteristics are observed in the real and imaginary parts of the dielectric function. Furthermore, the absorption coefficient surpasses 10 5 cm −1 at 1 and 1.2 eV for both Sb 2 Se 3 and Sb 2 S 3 . The result indicates that these highly efficient absorber materials are suitable in collecting solar energy.