Electronic and optical properties of Sb₂Se₃and Sb₂S₃: Theoretical investigations

In recent developments in solar energy research, Sb2Se3 and Sb2S3 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 Sb2Se3 and Sb2S3 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 Sb2Se3 and Sb2S3, respectively. The valence band and conduction band edges are primarily formed by Se 4p, S 3p, and Sb 5p hybridized orbitals. The effective density of states (DOS) exhibit magnitudes on the order of 1019 cm-3. Notably, anisotropic characteristics are observed in the real and imaginary parts of the dielectric function. Furthermore, the absorption coefficient surpasses 105 cm-1 at 1 and 1.2 eV for both Sb2Se3 and Sb2S3. The result indicates that these highly efficient absorber materials are suitable in collecting solar energy.