Multifunctional interfacial molecular bridge enabled by an aggregation-induced emission strategy for enhancing efficiency and UV stability of perovskite solar cells

The interface defects between the electron transport layer (ETL) and the perovskite layer, as well as the low ultraviolet (UV) light utilization rate of the perovskite absorption layer, pose significant challenges for the commercialization of perovskite solar cells (PSCs). To address this issue, this paper proposes an innovative multifunctional interface modulation strategy by introducing aggregation-induced emission (AIE) molecule 5-[4-[1,2,2-tri[4-(3,5-dicarboxyphenyl)phenyl]ethylene]phenyl]benzene-1,3-dicarboxylic acid (H8ETTB) at the SnO2 ETL/perovskite interface. Firstly, the interaction of H8ETTB with the SnO2 surface, facilitated by its carboxyl groups, is effective in passivating surface defects caused by non-coordinated Sn and O vacancies. This interaction enhances the conductivity of the SnO2 film and adjusts energy levels, leading to enhanced charge carrier transport. Simultaneously, H8ETTB can passivate non-coordinated Pb2+ ions at the perovskite interface, promoting perovskite crystallization and reducing the interface energy barrier, resulting in a perovskite film with low defects and high crystalline quality. More importantly, the H8ETTB molecule, can convert UV light into light absorbable by the perovskite, thereby reducing damage caused by UV light and improving the device's utilization of UV. Consequently, the champion PSC based on SnO2-H8ETTB achieves an impressing efficiency of 23.32% and significantly improved photostability compared with the control device after continuous exposure to intense UV radiation. In addition, the Cs0.05(FA0.95MA0.05)0.95Pb(I0.95Br0.05)3 based device can achieve maximum efficiency of 24.01%, demonstrating the effectiveness and universality of this strategy. Overall, this innovative interface bridging strategy effectively tackles interface defects and low UV light utilization in PSCs, presenting a promising approach for achieving highly efficient and stable PSCs.