Multifunctional AO-245 Antioxidant Enables UV-Resistant and High-Efficient Perovskite Solar Cells

Ultraviolet (UV) radiation greatly affects the stability of perovskite solar cells (PSCs), limiting their application in extreme environments such as plateaus and deserts. Herein, the antioxidant [triethylene glycol bis (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] (AO-245) is introduced into the perovskite layer by anti-solvent method to improve the UV stability. AO-245 not only demonstrates UV absorption properties but also neutralizes harmful superoxide radicals ( $O_2^{•-}$ ) through a hydrogen atom transfer mechanism (HAT), thereby mitigating the photodegradation damage of perovskite. Additionally, the -OH group in AO-245 can form hydrogen bonds with I^-, inhibit the migration of iodide ions due to photoaging, and synergistically enhance the UV stability of the device. As a result, even after 120 h of exposure to UV light at 275 and 365 nm, the AO-245-modified PSCs retain more than 88% and 83% of their initial power conversion efficiency (PCE), respectively. AO-245 additive passivates the uncoordinated Pb²⁺ through C═O and C─O bonds, thereby enhancing the film's quality and the device's stability. Consequently, the device achieves a PCE of 19.76%, which is among the highest efficiencies observed hole transport material (HTM)-free carbon-based PSCs (C-PSCs). This study provides a simple solution to improve the durability of PSCs under UV radiation, facilitating their application in extreme environments.