Mechanochemical P–C Bonding Strategy for Work Function Tuning in Printable Carbon–Based Perovskite Solar Cells

In printable mesoscopic perovskite solar cells (p‐MPSCs), the carbon electrode work function is a pivotal parameter governing efficient hole extraction; yet, devising environmentally benign approaches for its modulation remains a critical challenge. Herein, we report a mechanochemical strategy to construct robust P–C bonds by high‐energy ball milling black phosphorus (BP) with graphite, enabling homogeneous P distribution without compromising the intrinsic graphitization degree of carbon. The tailored electronic structure leads to an optimized work function, reduced defect‐state density, and improved perovskite infiltration, thereby enhancing the open‐circuit voltage ( V OC ) and fill factor ( FF ). At an optimal BP loading (3 wt%), the carbon electrode delivers a power conversion efficiency (PCE) of 17.45%, representing a 15.8% improvement over the undoped control. This work pioneers P–C bond engineering through mechanochemistry as a highly effective and scalable strategy, marking a significant advancement in the development of high‐performance carbon‐based perovskite solar cells.