Efficient defect passivation of Sb2Se3 film by tellurium doping for high performance solar cells

Defects in a semiconductor dictate the carrier transport and recombination ability, which are critical factors that influence the power conversion efficiency in solar cells. In this study, we demonstrate that the introduction of tellurium is able to fine tune the atomic ratio of Se/Sb in Sb2Se3 thin films, both Se-rich and Sb-rich Sb2Se3 are obtained. Using fine-tuned device fabrication and deep level defect spectroscopy for characterization, we experimentally disclose that Se-rich Sb2Se3 favors the formation of Se-Sb and V-Sb defects, while Sb-rich films benefit the formation of Sb-Se and V-Se defects. With an appropriate excess of Se in Sb2Se3, a net efficiency improvement of 2% is obtained when compared with pristine Sb2Se3 based solar cells. Our study provides an effective strategy to manipulate the defect formation in Sb2Se3 solar cells and inspires further improvement in the efficiency of Sb2Se3 solar cells.