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.