Molecular Glue: 1D/3D Heterojunction Suppresses Nonradiative Recombination and C 60 Aggregation for Efficient and Stable Perovskite Solar Cells

ABSTRACT Constructing 1D/3D heterojunctions at the top interface has emerged as a promising strategy to mitigate non‐radiative recombination and improve the stability of perovskite solar cells (PSCs). However, rational molecular design principles of organic components remain elusive, and the morphological instability of fullerene‐based electron transport layers has been largely overlooked. Here, we introduce a heterocyclic amidine‐functionalized molecule, 1H‐pyrazole‐1‐carboxamidine hydroiodide (PCAI), to construct a 1D/3D heterojunction at the perovskite/C 60 interface. The molecular design features multiple hydrogen‐bonding sites, an extended π‐conjugated plane, and compact cationic size, enabling selective formation of phase‐pure 1D (PCA)PbI 4 perovskitoid, while residual PCA + cations uniformly coat the perovskite surface. This surface reconstruction effectively suppresses non‐radiative recombination and optimizes energy‐level alignment, yielding a record‐level power conversion efficiency of 26.33% among 1D/3D heterojunction‐based PSCs. More importantly, PCAI acts as a “molecular glue” that anchors C 60 molecules on the perovskite surface, suppressing C 60 self‐aggregation and preserving interfacial integrity under operational stress. This work establishes a clear structure–property–performance relationship for material design and identifies C 60 morphological evolution as a decisive yet previously underexplored stability factor.