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.