Cs Doping Engineering Effectively Improves Photovoltaic Performance of Sb₂S₃ Solar Cells

Solar energy conversion into electricity through photovoltaic technology represents an environmentally friendly way of utilizing renewable energy sources for sustainable energy production. Low-cost and highly stable Sb2S3 solar cells are considered promising photovoltaic materials. However, Sb2S3 solar cells are currently facing problems such as poor electron transport capacity and grain boundary defects. In this work, an Sb2S3 precursor solution is prepared by the sol–gel method, to which a small amount of cesium is added for doping the light absorbing layer. By exploring the doping concentration, the optimal doping concentration of 0.05% is obtained. The doped Sb2S3 exhibits improved crystallinity, reduces surface roughness, increases particle size, decreases grain boundaries, and enhances carrier transport capacity, which is reflected in the increased open-circuit voltage (Voc = 0.678 V), short-circuit current density (Jsc = 15.92 mA/cm2), and power conversion efficiency (PCE = 4.81%). Cs doping effectively suppresses recombination centers by forming S–Cs metal bonds, thereby reducing impurities and reducing film surface defects, which collectively enhance the quality of Sb2S3 films. This study provides valuable insights and strategies for the further modification and optimization of Sb2S3 solar cells.