A Rapid and Robust Light-and-Solution-Triggered In Situ Crafting of Organic Passivating Membrane over Metal Halide Perovskites for Markedly Improved Stability and Photocatalysis

Abstract

Despite intriguing optoelectronic attributes in solar cells, light-emitting diodes, and photocatalysis, the instability of organic-inorganic perovskites poises a grand challenge for long-term applications. Herein, we report a simple yet robust strategy via light-and-solution treatment to create an organic membrane that effectively passivates CH₃NH₃PbI₃ (MAPbI₃). Specifically, the restructuring of MA⁺ is observed on MAPbI₃ in aqueous hydrogen iodide. HIO₃ molecules are generated via the reaction between water and I₂ induced by photocatalysis when MAPbI₃ is illuminated. The hydrogen bonding between HIO₃ molecules at different perovskite particles not only directs the creeplike growth of perovskite particles but also in situ forms a passivating layer firmly anchoring on the perovskite surface with hydrophilic -NH₃⁺ groups tethering to perovskites and hydrophobic -CH₃ moieties exposed to air. Intriguingly, such MA⁺ film greatly improves the stability of perovskites against moisture as well as their crystal quality, considerably enhancing the photocatalytic hydrogen evolution rate.