Synergetic Effect of the Surfactant and Silica Coating on the Enhanced Emission and Stability of Perovskite Quantum Dots for Anticounterfeiting.

Recently, the growing demand for optical anticounterfeiting technology has motivated intensive research in newly emerging halide perovskite quantum dots (QDs). However, the poor stability and unsatisfactory fluorescence efficiency of such materials are the main obstacles to the application of reliable anticounterfeiting. In this work, we performed a well-controlled investigation of the effect of the surfactant (l-α-phosphatidylcholine, LP) and silica encapsulation on the stability and emission of the CsPbBr QDs. Because of the synergetic effect of the surfactant and core/shell configuration, the resulting CsPbBr/LP/SiO QD composites demonstrated a higher photoluminescence quantum yield (>90%), a better color purity, and a significantly improved stability in heat, ultraviolet light, water, and ambient oxygen, which provide them the basic conditions as a high-tech security ink for anticounterfeiting. By inkjet printing technology, we demonstrated that our CsPbBr/LP/SiO QD composites can act as a smart concealed ink for information encryption and decryption. More importantly, the anticounterfeiting effect can be efficiently sustained even though the paper with designable patterns was crudely treated by water-soaking, heating/cooling cycling, and continuous ultraviolet light switching (1500 cycles). The above results obtained provide effective strategies to improve emission efficiency and stability of perovskite QDs, thereby enduing them anticounterfeiting application potential.