Antisolvent Treatment for Antimony Selenide Thin Film Augmenting Optoelectronic Performance

Abstract Simple binary metal chalcogenides, such as Sb₂Se₃, are promising for low‐cost, solution‐processed optoelectronic applications due to their strong anisotropic nature. However, achieving high‐quality Sb₂Se₃ films via spin coating remains challenging because of the slow evaporation of high‐boiling‐point solvents and the need for extended annealing to remove residual anionic impurities. While previous efforts have focused on optimizing precursor chemistry and annealing conditions, effective strategies to improve film quality during deposition remain underexplored. Here, antisolvent treatment is introduced as a novel and effective approach to enhance Sb₂Se₃ film quality, utilizing an elemental precursor ink in a thiol‐amine cosolvent. The study systematically investigates the impact of seven different antisolvents and identifies ethanol as the most effective choice, enabling the formation of dense, uniform Sb₂Se₃ film with enhanced crystallinity, preferential [020] grains, reduced surface oxide impurities, and improved visible light absorption. As a result, CdS/Sb₂Se₃ heterojunction solar cells fabricated with treated films exhibit a two‐fold increase in efficiency, while Sb₂Se₃‐based photodetectors show a four‐fold enhancement in responsivity compared to the devices made with untreated films. The findings demonstrate that antisolvent treatment is a powerful tool for improving the quality of solution‐processed chalcogenide films, paving the way for their broader application in optoelectronic devices.