Regulating Orientational Crystallization and Buried Interface for Efficient Perovskite Solar Cells Enabled by a Multi‐Fluorine‐Containing Higher Fullerene Derivative

Abstract Perovskite films prepared by the solution process usually result in irregular grain orientation and rich buried interface defects, hindering the further improvement of device performance. Herein, multi‐fluorine‐containing C₆₀‐ and C₇₀ (higher fullerene)‐porphyrin derivatives, F₆₀PD and F₇₀PD, are synthesized and pre‐buried to modify the SnO₂/perovskite heterointerface. The F₇₀PD modification layer provides a better perovskite quality and more effective electron transporting capability compared to the corresponding F₆₀PD, with the F₇₀PD being more effective in regulating the perovskite growth, passivating the buried interface defects, and optimizing the interface energy level alignment. Consequently, the F₇₀PD‐based device delivers superior efficiency and stability than the control and F₆₀PD‐based devices. The F₇₀PD‐based device yields a champion efficiency of 24.09% with negligible hysteresis. Meanwhile, due to the increased activation energy of ion migration, the F₇₀PD‐based device maintains 80% of its initial efficiency after operating at the maximum power point for 1620 h. This study highlights the potential of designing higher fullerene materials for buried interface to further improve the perovskite solar cells’ performance.