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

Abstract Antimony sulfide (Sb 2 S 3 ) 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‐Sb 2 S 3 seed layer can serve as crystal nuclei and mediate the growth of large‐grained, highly compact CSS‐processed Sb 2 S 3 films. This seed‐mediated Sb 2 S 3 film affords reduced defect density and enhanced charge‐carrier transport, which yields an improved power conversion efficiency (PCE) of 4.78% for planar Sb 2 S 3 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 Sb 2 S 3 devices. This work demonstrates an effective strategy to deposit high‐quality low‐defect‐density Sb 2 S 3 films via vacuum‐based physical methods for optoelectronic applications.