Bifacial Defect Management of Buried Interface for Enhanced Photovoltaic Performance of Inverted-Perovskite Devices...

The intrinsic aggregation behavior of self-assembled molecules (SAMs) leads to severe heterogeneity or even blankness in the perovskite substrate layer. The direct contact between the bottom surface of perovskite and nickel oxide undergoes a redox reaction, which inevitably leads to perovskite degradation and strengthens the charge transport barrier. Herein, a 1-propenyl-2,3-dimethylimidazole hexafluorophosphate (PDMIMPF₆) molecule with bidirectional defect regulation has been developed. PDMIMPF₆ binds SAMs and perovskite bilayers to modulate defects of the two as well as to blur the interfacial space. The work function of the SAM layer increases due to repair of the aggregation defect in organic functional molecules, contributing to rapid charge transport and reducing the degradation rate of the perovskite. In addition, the PDMIMPF₆ with multifunctional groups has been shown to inhibit FA⁺ migration and passivate the uncoordinated lead defects through hydrogen bonding and coordination interactions. This molecular adhesive strategy achieves a power conversion efficiency of 25.61% for the PDMIMPF₆-treated device. Noticeably, the unencapsulated-device maintaines an initial efficiency of 83.0% at 1200 h under maximum power point tracking, and outstanding humidity stability (91.4%) over 2000 h.