The crystal structure, electronic structure and photoelectric properties of a novel solar cells absorber material Sb2Se3−x S x

Sb₂Se_3−xS_x is considered a promising absorber material for solar cell applications because of its tunable band gap. However, theoretical research on Sb₂Se_3−xS_x is still limited. In this research, the crystal structure, electronic structure and photoelectric properties of Sb₂Se_3−xS_x ($x=0$, 0.125, 0.25, 0.5, 0.75) were determined using first-principles calculations based on density functional theory. The band gap is affected by the structural distortion and covalence of Sb₂Se_3−xS_x with increasing S concentration. From $x=0$ to $x=0.75$, the covalence of Sb₂Se_3−xS_x gradually increases. While for $x=0.125$ and $x=0.25$, the structural distortion are more severe than the others. Combining with the affects of both, the band gap decreases first and then increases with increasing S concentration. By calculating the carrier effective masses and optical characteristics of Sb₂Se_3−xS_x, it can be found that Sb₂Se_3−xS_x ($x=0.5$) shows the optimized photoelectric properties. The results provide some guidance for the further development of Sb₂Se_3−xS_x solar cells by adjusting band gap.