Extending the Lifetime of Perovskite Solar Cells using a Perfluorinated Dopant

The principle limitation of perovskite solar cells is related to their instability and, hence, their limited lifetime. Herein, we employ an imidazolium iodide dopant, 1‐methyl‐3‐(1H,1H,2H,2H‐nonafluorohexyl)‐imidazolium iodide, containing a perfluorous appendage, which leads to prolonged (unencapsulated, under Ar atmosphere) device activities exceeding 100 days without compromising the power conversion efficiency and other photovoltaic parameters. The extended lifetime of the device can be attributed, at least in part, to the hydrophobic nature of the imidazolium iodide salt. The functionalization of the perovskite material was found to have negligible influence on the perovskite crystal structure. Under cover: Perovskite solar cells are fabricated using perovskite active layers doped with fluorinated imidazolium‐based molecules. These additives significantly increase the stability of the resulting solar cell device owing to the electron‐withdrawing character of the fluorinated salt together with its hydrophobicity, and induce structural and functional changes to the resultant perovskite, leading to stable power conversion efficiency.