Vinylene‐Linked Covalent Organic Framework‐Directed Facet Orientation Reconstruction in Inverted Perovskite Solar Cells

Crystallographic orientation engineering is critical for suppressing defect formation, relieving lattice strain, and promoting charge transport in metal halide perovskites, yet the selective regulation of facet competition during solution crystallization remains challenging. Here, we introduce a vinylene‐linked covalent organic framework, TBD‐COF, as a structurally robust crystallization regulator for high‐performance PSCs. The ordered porous skeleton of TBD‐COF, together with its embedded pyridinic nitrogen atoms, provides spatially distributed interaction sites for coordinating with perovskite precursors and modulating the nucleation and crystal growth processes. Notably, TBD‐COF incorporation redirects the crystallization pathway from conventional (001)‐dominated growth toward an enhanced fraction of (012)‐oriented crystalline domains. This orientation regulation alleviates disordered grain packing and lattice‐strain accumulation, thereby suppressing defect‐assisted nonradiative recombination and facilitating carrier transport. Consequently, the optimized devices achieve a champion power conversion efficiency (PCE) of 27.01% with a remarkable fill factor of 88.72%, representing one of the highest values reported for COF‐incorporated PSCs. Moreover, the TBD‐COF‐modified devices retain 89% of their initial PCE after 1000 h under the ISOS‐L‐2 protocol.