A Codoping Strategy for Efficient Planar Heterojunction Sb2S3 Solar Cells

Antimony sulfide is a promising wide bandgap light‐harvesting material owing to its high absorption coefficient, nontoxicity, superior stability, and low cost. However, the reported Sb2S3 absorber suffers from complicated defect characteristics due to its quasi‐1D structure. Herein, a codoping technique from chlorine and selenium is developed in hydrothermal method to regulate the film defect properties and promote the device efficiency. The theoretical calculation and experimental results demonstrate that the Cl&Se codoping plays a synergistic role in absorber film quality improvement. Se doping could efficiently fill the intrinsic deep defect level VS and Cl is a benign n‐type dopant and favor [hk1] oriented deposition. Systematic device physical characterizations verify the codoped device superior heterojunction quality and much lower interface and bulk defect density comparing with control one. The optimal codoping device delivers a certified power conversion efficiency of 7.15% (5.9% for control one), the highest certified value in planar Sb2S3 solar cells. This study develops an effective doping strategy with multi‐element synergistic incorporation which sheds new light on high‐efficiency Sb2S3 solar cells. Sb2S3 is one optimal top‐cell absorption material for Si‐based tandem solar cells. Traditional doping is difficult to achieve efficient heteroatom doping due to complicated defect characteristics. A codoping strategy is developed from Cl and Se doping by hydrothermal method. The synergistic roles of Cl and Se doping help to improve power conversion efficiency from 5.91% (control) to 7.15% (the highest certified value).