Encapsulation of lead halide perovskite quantum dots in mesoporous NaYF4 matrices with enhanced stability for anti-counterfeiting

Abstract

All-inorganic cesium lead halide (CsPbX₃, X = Cl, Br, and I) perovskite quantum dots (PQDs) have great potential application due to their unique optoelectronic properties. However, poor luminescence stability caused by some inevitable factors such as light, moisture and heat always restricts their practical application. In this work, the stability of CsPbX₃ (X = Cl_0.5Br_0.5, Br, and Br_0.5I_0.5) PQDs is improved by encapsulating them in stable hollow mesoporous NaYF₄:Yb,Tm nanoparticles (HMNPs). Compared to pristine PQDs, HMNP–PQD composites exhibit stable photoluminescence properties that can be maintained for more than 60 days under ambient atmospheric conditions. Thanks to the protection of HMNPs, the composites show much higher long-term stability in highly humid air and enhanced stability against UV light treatment compared to naked CsPbBr₃ PQDs. Based on the proposed confinement effects of PQDs coordinated with the hollow mesoporous structure of NaYF₄:Yb/Tm, the related structural model of NaYF₄:Yb/Tm@PQD composites is discussed. Moreover, dual-mode luminescence can be observed in the NaYF₄:Yb/Tm@PQD nanocomposites under 365 nm UV light and 980 nm laser excitation, indicating that the as-designed composites have great potential for dual-mode anti-counterfeiting application. This work provides a new idea for the stabilization and application of CsPbX₃ PQDs.