Composition engineering of Sb₂S₃ film enabling high performance solar cells

Sb₂S₃ is a kind of stable light absorption materials with suitable band gap, promising for practical applications. Here we demonstrate that the engineering on the composition ratio enables significant improvement in the device performance. We found that the co-evaporation of sulfur or antimony with Sb₂S₃ is able to generate sulfur- or antimony-rich Sb₂S₃. This composition does not generate essential influence on the crystal structure, optical band and film formability, while the carrier concentration and transport dynamics are considerably changed. The device investigations show that sulfur-rich Sb₂S₃ film is favorable for efficient energy conversion, while antimony-rich Sb₂S₃ leads to greatly decreased device performance. With optimizations on the sulfur-rich Sb₂S₃ films, the final power conversion efficiency reaches 5.8%, which is the highest efficiency in thermal evaporation derived Sb₂S₃ solar cells.