LAUSR

Lead halide perovskites hold promise for photovoltaics, lasers, and light-emitting diode (LED) applications, being known as light-harvesting or -emitting materials. Here we show that colloidal lead halide CsPbCl3 perovskite quantum dots (PQDs), when incorporating divalent manganese (Mn2+) ions, are able to produce spin-paired singlet oxygen molecules with over-unit quantum yield (~1.08) in air condition. Our mechanistic studies and atomic-level density functional theory calculations endorse an energy-migration-mediated quantum cutting process favoring multiple singlet oxygen generation (MSOG), in which one exciton-activated bulk Mn2+ ion (~ 2.0 eV) inside the nanocrystal migrates its energy among the Mn2+ sub-lattice to two surface Mn2+ defect states (~ 1.0 eV), followed by nonradiative energy transfers to two surrounding oxygen molecules. Moreover, super-hydrophobicization of MOSG PQDs through silica-mediated polystyrene encapsulation prevents them from disintegration in aqueous medium, enabling photodegradation of methyl orange at a rate even higher than that of the canonical titanium oxide photocatalyst. The observation of ultra-efficient singlet oxygen generation in PQDs have implications for fields ranging from photodynamic therapy to photocatalytic applications.