Boosting Efficiency of Hydrothermally Grown Sb <sub>2</sub> S <sub>3</sub> Solar Cells via Rational Sulfur Engineering
Gang Wang, Feng Lin, Yuqian Huang, Junjie Yang, Haolin Wang, Hongling Guo, Zhen Yu, Yongtai Yin, Liang Fang, Bao Lei, Youchao Tu, Jiangfeng Liu, Yi Zhang, Tao Chen
Abstract
Abstract A high‐quality absorber layer is crucial for enhancing the performance of emerging photovoltaic devices, such as antimony sulfide (Sb 2 S 3 ) solar cells, especially for the regulation of their composition and defects. However, traditional sulfur sources (supplying only S 2− ) and annealing‐induced sulfur volatilization in hydrothermally grown Sb 2 S 3 solar cells cause sulfur deficiency, severe defects, and low power conversion efficiencies (PCEs). Here, sodium tetrathionate (Na 2 S 4 O 6 ) is introduced as a rationally designed sulfur‐engineering additive, enhancing precursor solution stability via strong coordination and enabling in situ sulfurization in the annealing process. During hydrothermal growth, Na 2 S 4 O 6 slowly releases elemental sulfur, forming Sb 2 S 3x ( x > 1) as‐prepared films that self‐optimize S/Sb stoichiometry during annealing. This strategy elevates the deposition rate, boosts absorber compactness, and reduces defect density. The optimized devices achieve a PCE of 8.03% (certified 7.78%) under AM 1.5G illumination and an indoor PCE of 18.36% (1000 lux LED), representing the highest certified PCE for pure Sb 2 S 3 solar cells to date. By decoupling sulfur supply from traditional sulfide sources, this work establishes Na 2 S 4 O 6 as a versatile additive for hydrothermal synthesis of metal sulfide photovoltaics, offering a blueprint for precursor solution design in hydrothermal‐processed thin‐film devices.