Composition engineering of SbS film enabling high performance solar cells.

SbS 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 SbS is able to generate sulfur- or antimony-rich SbS. 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 SbS film is favorable for efficient energy conversion, while antimony-rich SbS leads to greatly decreased device performance. With optimizations on the sulfur-rich SbS films, the final power conversion efficiency reaches 5.8%, which is the highest efficiency in thermal evaporation derived SbS solar cells.