Interfacial engineering is a critical strategy for improving efficiency organic-inorganic hybrid perovskite solar cells (PSCs). Here, we introduce an organic small-molecule interlayer exhibiting an excited-state intramolecular proton transfer (ESIPT) effect to optimize the interface between wide-bandgap perovskites and NiOx hole transport layers. The ESIPT-active interlayer enables favorable energy-level alignment and defect passivation, thereby enhancing charge extraction and suppressing interfacial non-radiative recombination.[1] In addition, its dipolar nature and hydrophobicity improve perovskite film quality, leading enlarged grain size and enhanced crystallinity.[2] Consequently, the PSCs achieve an enhanced power conversion efficiency of 20.13% and open-circuit voltage with a reduced Voc deficit of 0.41 V, along with excellent operational stability, demonstrating the potential of this interfacial design strategy for high-performance wide-bandgap PSCs and tandem applications.