摘要： The incorporation of bulky organic cations to metal-halide perovskites, forming the 2D-3D heterojunctions, has dramatically improved the stability of perovskite solar cells (PSCs). Nevertheless, the power conversion efficiencies (PCEs) of these PSCs are typically sacrificed because the formed 2D structures possess larger dielectric confinement, wider bandgaps, higher exciton binding energies and lower charge-carrier mobilities than the 3D perovskites. Here, we demonstrate that the environmental stability of the PSCs could be significantly improved without sacrificing the efficiency by introducing hydrophobic polyfluorinated cations (CF3CF2CH2NH3+, 5F-PA+) to the metal-halide perovskites. Due to the large 2D perovskite formation enthalpy with polyfluorinated cations, the addition of such cations will form a protective layer at the grain boundaries of 3D perovskite rather than form the 2D perovskites. The resultant solar cells based on 5F-PA0.05[Cs0.05(MA0.17FA0.83)0.95]0.95Pb(Br0.17I0.83)3 exhibit a substantially increased PCE of 22.86% compared with that (20.69%) of the control Cs0.05(MA0.17FA0.83)0.95Pb(Br0.17I0.83)3 devices. More importantly, the optimized devices could keep 80% of their original PCEs after >3000 h in ambient environment with 65 ± 10% relative humidity, which is attributed to hydrophobic fluorine moieties.