AIE Molecules UV‐Filtering Effect Improves the Photostability of Organic Solar Cells

Abstract Due to the poor stability of organic solar cells (OSCs), especially ultraviolet light (UV) stability, they are not yet up to the standard for commercial applications. Inverted devices based on the ZnO electron transport layer (ETL) are relatively thermal‐ and air‐stable, while their UV light stability is poor. Moreover, the active layer materials undergo severe degradation under UV light, which also causes the degradation of the device. Here, aggregation‐induced emission (AIE) molecules as an optical barrier layer are coated between ZnO‐ETL and active layer to fabricate efficient OSCs with excellent UV photostability. AIE molecules can avoid direct photodegradation of the active layer materials by absorbing UV light. At the same time, they can passivate the oxygen defects on the ZnO surface and prevent photocatalytic degradation of the active layer materials. Therefore, the ZnO/TPIZ‐based devices maintain 84% of the original power conversion efficiency (PCE) with continuous irradiation by 5 mW cm^–2 UV light (365 nm) for 1500 h, and similarly T₈₀ for more than 700 h under 20 mW cm^–2 UV light exposure. Moreover, the ZnO/TPIZ‐based devices also preserve excellent thermal stability accompanying the upgrading of PCE.