Dipole‐Regulated Fullerene Interfaces for Efficient and Stable Wide‐Bandgap Solar Cells and All‐Perovskite Tandems

Endohedral metallofullerenes offer intrinsic cage‐confined dipoles and structural compatibility with fullerene electron‐transport layers, making them attractive for regulating perovskite interfaces. However, the encapsulated metal ion cannot directly coordinate with surface defects, while the outer carbon cage lacks specific anchoring sites, leading to disordered adsorption configurations, electrostatic heterogeneity, and nonuniform coupling with C 60 . Here, we employ 1‐pyreneboronic acid (PyBA) as a molecular director to regulate Gd@C 82 at the wide‐bandgap (WBG) perovskite/C 60 interface. The boronic acid group anchors to the perovskite surface and passivates undercoordinated Pb‐related defects, while the pyrene framework associates with the Gd@C 82 cage and stabilizes favorable molecular configurations. This dual interaction enhances the dipolar character and spatial organization of Gd@C 82 , homogenizes the interfacial potential, and strengthens electronic coupling with C 60 , thereby accelerating electron extraction and suppressing nonradiative recombination. The optimized WBG cells achieve a power conversion efficiency of 20.23%, enabling monolithic all‐perovskite tandem devices with 28.44% efficiency. The modified WBG devices retain over 90% of their initial efficiency after 1451 h of maximum‐power‐point tracking and 1563 h under damp‐heat conditions, while the tandem devices retain over 80% after 531 h of operation. This work establishes molecularly directed endohedral metallofullerenes as a strategy for coordinating surface chemistry and interfacial electrostatics.