Sulfur-Vacancy Passivation via Selenium Doping in Sb2S3 Solar Cells: Density Functional Theory Analysis

Antimony sulfide (Sb2S3) has attracted great attention during the past few decades as a light-harvesting material for solar cells owing to its earth abundance and low toxicity. Meanwhile, various point defects limit the efficiency improvement below the power conversion efficiency (PCE) of 10%, especially for S vacancy defects with lower defect formation energy. However, recent experiments have reported that Se doping has suppressed the density of defects and improved photoelectric performance in Sb2S3 solar cells. We adopt the first principles to simulate defect formation energies, charge localization, phonon spectrum, and defect migration dynamics for Sb2S3 structures, indicating that Se doping contributes to increasing the formation energy and inhibiting the formation of the sulfur vacancy defect. Meanwhile, the addition of Se also reduces the overlap between vibrational configurations in initial and final states, suppresses nonradiative electron–hole recombination, prolongs the minority carrier lifetime, and decreases charge and energy losses in Sb2S3 solar cells. The results contribute to the atomistic understanding of the properties of sulfur-vacancy passivation via Se doping and afford the design of high-performance optoelectronic materials.