Towards Extending Solar Cell Lifetimes: Addition of a Fluorous Cation to Triple Cation‐Based Perovskite Films

Organohalide perovskites have emerged as highly promising replacements for thin‐film solar cells. However, their poor stability under ambient conditions remains problematic, hindering commercial exploitation. The addition of a fluorous‐functionalized imidazolium cation during the preparation of a highly stable cesium‐based mixed perovskite material Cs 0.05 (MA 0.15 FA 0.85 ) 0.95 Pb(I 0.85 Br 0.15 ) 3 (MA=methylammonium; FA=formamidinium) has been shown to influence its stability. The resulting materials, which vary according to the amount of the fluorous‐functionalized imidazolium cation present during fabrication, display a prolonged tolerance to atmospheric humidity (>100 days) along with power conversion efficiencies exceeding 16 %. This work provides a general route that can be implemented in a variety of perovskites and highlights a promising way to increase perovskite solar cell stability.