N-Heterocycle-Activated π-Cooperative Coordination for Enhancing Structural Stability of Perovskite Solar Cells.

The chemistry of buried interfaces critically dictates the crystallization behavior of perovskite semiconductors in inverted perovskite solar cells, yet remains poorly controlled, giving rise to interfacial coordination disorder that disrupts the organization of self-assembled monolayers (SAMs) during crystallization. Here, we report an N-heterocycle-activated coordination strategy that stabilizes SAM organization while enabling precise regulation of precursor chemistry and crystallization at SAM-perovskite interfaces. Imidazolium-derived molecules integrated into SAMs establish cooperative coordination interactions with neighbouring lead polyhalide species, thereby reshaping the local precursor environment and directing nucleation and crystal growth. This process gives rise to a π-cooperative coordination interaction at the buried interface, which suppresses interfacial grooves and voids, reduces residual solvent-complex intermediates, and promotes the direct formation of phase-pure α-perovskite films. Devices based on this molecularly regulated interface achieve a power conversion efficiency of 26.83% and retain 93.8% of their initial efficiency after 936 h of continuous maximum power point operation. These results establish coordination-mediated interfacial design as a molecular route to couple interfacial order with crystallization control in perovskite semiconductors.