Tailoring Presynthesized Amorphous Sb2S3 Particles Enables High-Efficiency Pure Antimony Sulfide Solar Cells

At present, hydrothermal deposition techniques are unique to attain high-efficiency antimony sulfide (Sb2S3) solar cells. It is very common that during the mixing of antimony and sulfur sources before the hydrothermal reaction, the solution quickly changes from colorless to yellow due to the formation of amorphous Sb2S3 particles. However, the effect of presynthesized Sb2S3 particles on the deposition kinetics of Sb2S3 absorber layers and the device performance is completely unknown. To pave the pathway toward high-efficiency Sb2S3 solar cells, it is urgent to disclose the mechanism behind such a phenomenon. By accurately controlling the number and size of presynthesized Sb2S3 particles in the hydrothermal precursor solution, it was found that the suspended Sb2S3 particles act as growth centers, facilitating the orderly deposition of the Sb2S3 film on the substrate, which in turn affects the film's thickness, grain size, densification, and crystallinity. Based on this finding, the Sb2S3 solar cell with an efficiency of 7.29% is achieved, which is currently one of the highest fundamental efficiency obtained for Sb2S3 prepared by hydrothermal methods without doping. This study lays the groundwork for investigating the growth mechanism of Sb2S3 produced by hydrothermal deposition techniques and provides guidelines for the preparation of high-efficiency Sb2S3 solar cells.