Improved One- and Multiple-Photon Excited Photoluminescence from Cd 2+ -Doped CsPbBr 3 Perovskite NCs.

Metal halide perovskite nanocrystals (NCs) attract much attention for light-emitting applications due to their exceptional optical properties. More recently, perovskite NCs have begun to be considered a promising material for nonlinear optical applications. Numerous strategies have recently been developed to improve the properties of metal halide perovskite NCs. Among them, B-site doping is one of the most promising ways to enhance their brightness and stability. However, there is a lack of study of the influence of B-site doping on the nonlinear optical properties of inorganic perovskite NCs. Here, we demonstrate that Cd 2+ doping simultaneously improves both the linear (higher photoluminescence quantum yield, larger exciton binding energy, reduced trap states density, and faster radiative recombination) and nonlinear (higher two- and three-photon absorption cross-sections) optical properties of CsPbBr 3 NCs. Cd 2+ doping results in a two-photon absorption cross-section, reaching 2.6 × 10 6 Goeppert-Mayer (GM), which is among the highest reported for CsPbBr 3 NCs.