Efficient photosensitized singlet oxygen generation in two-dimensional perovskite nanosheets via energy transfer

Two-dimensional (2D) organic-inorganic hybrid halide perovskites have gained extensive attention in photovoltaics, photodetectors and light-emitting diodes owing to their unique optoelectronic properties and superior stability compared with their three-dimensional (3D) counterparts. However, 2D perovskites have rarely been applied for photochemical conversion applications. Herein, a series of 2D BA₂MA_n-1Pb_nBr_3n+1 perovskite nanosheets have been synthesized through a facile, ligand-free precipitation (LFP) method at room temperature. Using the specific chemical trapping techniques, we show for the first time that the 2D perovskite nanosheets can effectively generate photosensitized singlet oxygen (¹O₂) via energy transfer from triplet excitons to molecular oxygen in non-polar solvent. Based on this discovery, the as-prepared BA₂PbBr₄ and BA₂MAPb₂Br₇ nanosheets successfully catalyze the ENE reaction and 1,2-addition reaction between olefin and singlet oxygen under visible light. Our study is anticipated to develop and demonstrate new mechanisms for 2D halide perovskite materials in photodynamic therapy and photocatalytic applications.