Fluorine-substituted bifunctional molecules for enhanced perovskite solar cell performance

In this work, we report a passivation strategy employing a fluorine-substituted small molecule (FMPPY). Introducing FMPPY through an anti-solvent method could effectively reduce the metallic Pb0 and Pb2+ defects, enhance charge transfer, and optimize energy alignment at the perovskite/Spiro-OMeTAD interface. In turn, the interfacial charge recombination is well restricted. Through optimization, a power conversion efficiency (PCE) of 24.8 % is obtained. Moreover, FMPPY-treated devices retain 87 % efficiency after 1500 h, demonstrating excellent long-term stability. This surface reconstruction strategy holds great promise for developing highperformance and stable PSCs.