CsPbX3/LaPO4:Eu3+ dual-emission composites with stimuli-responsive fluorescence switching for advanced anti-counterfeiting

Abstract

All-inorganic metal halide perovskite CsPbX₃ (X = Cl, Br, I) quantum dots (QDs) hold great promise for optoelectronic applications due to their outstanding properties. However, the practical application of brilliant CsPbX₃ QDs is limited by their environmental instability. Here, we report a stability-enhanced composite that is synthesized by the in situ growth of CsPbX₃ QDs on LaPO₄:Eu³⁺ microspheres. The host matrix serves as a physical barrier, effectively isolating the QDs from degradation and boosting their luminescence performance and robustness. The resulting composite exhibits excitation-dependent fluorescence characteristics, allowing for tunable emission from green at 532 nm to orange-red at 596 nm under different excitation sources. Compared to pure CsPbX₃ QDs, the thermal stability of the CsPbX₃/LaPO₄:Eu³⁺ composite is significantly enhanced, with its stability under ultraviolet irradiation and humidity increasing from 19% and 13% to 76% and 87%, respectively. Furthermore, based on this type of composite, we designed an “NCU” anti-counterfeiting label and an ASCII binary code system, where the distinct thermal quenching behaviors of the two components provide new insights for developing optical temperature sensors.