Enhanced Performance of Close-Spaced Sublimation Processed Antimony Sulfide Solar Cells via Seed-Mediated Growth

Antimony sulfide (Sb₂S₃) has attracted much attention due to its great prospect to construct highly efficient, cost-effective, and environment-friendly solar cells. The scalable close-spaced sublimation (CSS) is a well-developed physical deposition method to fabricate thin films for photovoltaics. However, the CSS-processed absorber films typically involve small grain size with high-density grain boundaries (GBs), resulting in severe defects-induced charge-carrier nonradiative recombination and further large open-circuit voltage (V_OC) losses. In this work, it is demonstrated that a chemical bath deposited-Sb₂S₃ seed layer can serve as crystal nuclei and mediate the growth of large-grained, highly compact CSS-processed Sb₂S₃ films. This seed-mediated Sb₂S₃ film affords reduced defect density and enhanced charge-carrier transport, which yields an improved power conversion efficiency (PCE) of 4.78% for planar Sb₂S₃ solar cells. Moreover, the V_OC of 0.755 V that is obtained is the highest reported thus far for vacuum-based evaporation and sublimation processed Sb₂S₃ devices. This work demonstrates an effective strategy to deposit high-quality low-defect-density Sb₂S₃ films via vacuum-based physical methods for optoelectronic applications.