3‑Ethoxy-4-hydroxybenzadehyde Surface Passivation of Perovskite Films Enables Exceeding 24% Efficiency in Solar Cells

On the surface of perovskite films, large quantities of defects are produced during preparation and exposure to air ambience, and they are key constraints to the performance of perovskite solar cells (PSCs). Passivating defects via organic molecules is an effective approach to fabricating efficient and stable PSCs. Herein, an organic molecule 3-ethoxy-4-hydroxybenzadehyde (EVL) is employed to passivate the surface defects on perovskite films. The aldehyde (−CHO) functional group of EVL can passivate under-coordinated lead ion (Pb²⁺) defects, and its hydroxyl (−OH) and alkoxy (−O–CH₂) groups can impede the migration of the formamidine ion (FA⁺) and iodide ion (I^–) on the perovskite via hydrogen bond interaction. This research indicates that EVL can significantly reduce the defect state, effectively suppress carrier recombination, and preferably promote hole movement from the perovskite layer to the hole-transport layer. Therefore, EVL passivation produced a significant increase in efficiency from 21.9 to 24.1% and improved the stability of PSCs. This study demonstrates that EVL is an effective passivator in surface defect passivation engineering to enhance the efficiency and stability of PSCs.