The humidity-insensitive fabrication of efficient CsPbI3 solar cells in ambient air

Recently, CsPbI3 perovskite solar cells (PSCs) have shown a breakthrough in photovoltaic performance due to their constantly improving power conversion efficiencies (PCEs) because of their admirable photoelectric properties and enhanced thermal stability. However, most fabrication processes take place inside a nitrogen glove box because CsPbI3 is notoriously sensitive to moisture. These tedious and rigorous operational conditions restrict CsPbI3 PSCs' commercialization. In our research, in order to solve the awkward situation of fabricating CsPbI3 PSCs without ambient moisture, we successfully developed an easy, one-step anti-solvent hot substrate (Anti-hot) spin-coating method to fabricate CsPbI3 film. Pre-heating the substrate could change the saturated vapor pressure of the mixed solvents and accelerate the precursor concentrations up to the supersaturation limit. Meanwhile, the anti-solvent method could induce heterogeneous nucleation. As a result, we could efficaciously control nucleation generation and grain growth under ambient moisture conditions and resist erosion and damage by molecular water. Finally, uniform and compact CsPbI3 film could be achieved and the corresponding PSCs reached up to 15.91% in a high humidity environment (RH, ∼50%). We hope that our exploration can provide a synthetic approach for producing high-quality CsPbI3 film for PSCs under ambient conditions.