The integration of dynamic photoluminescence and photochromism to achieve dual-modal characteristics can substantially elevate the security of anticounterfeiting measures. In this study, a novel bifunctional phosphor, namely CaAl 12 O 19 :Eu, Tb possessing dynamic photoluminescence and photochromism, is developed by the sol-gel combustion method. As the duration of exposure to 254 nm ultraviolet radiation increases, the CaAl 12 O 19 :Eu, Tb phosphors exhibit exceptional dynamic luminescent characteristics and pronounced color changes. Furthermore, this exposure results in a photochromic phenomenon on the surface of the samples, causing a shift from white to light brown. With an increase in Tb doping concentration, distinct and diverse chromatic variations easily discernible are observed by the naked eye. In addition, the mechanisms underlying the dynamic photoluminescent and photochromic characteristics are analyzed herein. Furthermore, the application of the bifunctional phosphor CaAl 12 O 19 :Eu, Tb for advanced dual-modal multicolor anticounterfeiting is explored, offering enhanced security against duplication attempts.
Multi-mode dynamic anti-counterfeiting materials can provide complex anti-counterfeiting performance and ensure the anti-counterfeiting strategy becomes more secure. Herein, a new type of multi-mode anti-counterfeiting encryption material of CaAl 12 O 19 :Eu, Er with different Er doping concentration was developed by sol–gel method. Interestingly, the CaAl 12 O 19 :Eu, Er phosphor and its composite have multi-mode anti-counterfeiting characteristics of multi-color down-conversion luminescence, up-conversion luminescence, dynamic luminescence, and photochromism. Effect of different Er doping concentration on the down-conversion luminescence, up-conversion luminescence, dynamic luminescence, and photochromism of CaAl 12 O 19 :Eu, Er was systematically investigated, and the relevant mechanisms were discussed. These anti-counterfeiting features can be simultaneously applied in both bright and dark fields, which can achieve high-level anti-counterfeiting in both spatial and temporal dimensions. The CaAl 12 O 19 :Eu, Er phosphors cannot be easily replaced by other materials with the same anti-counterfeiting properties. They display good application foreground in the field of anti-counterfeiting encryption.
Dual-mode anti-counterfeiting materials with photochromic and dynamic luminescent properties can improve the security of anti-counterfeiting and encryption. This study aimed to synthesize CaAl 12 O 19 :Eu, Ce phosphors with photochromic and dynamic photoluminescent properties. With the extension of 254-nm UV radiation time, the surface of the CaAl 12 O 19 :Eu, Ce phosphors changed in color from white to brownish yellow and was bleached by heating at 520 °C for 5 min, exhibiting excellent fatigue resistance and thermal stability. After co-doping Eu and Ce in CaAl 12 O 19 , the photochromic performance significantly improved, with the ΔR value increasing by 2.6- and 1.8-fold that of the CaAl 12 O 19 :1.0%Eu and CaAl 12 O 19 :1.0%Ce samples, respectively. After 254-nm UV irradiation, the CaAl 12 O 19 :Eu, Ce samples showed time-dependent dynamic luminescence characteristics, changing in color from orange-red to magenta. The mechanisms responsible for the photochromic and dynamic luminescence properties were further investigated. Overall, owing to their photochromism and dynamic photoluminescence, the CaAl 12 O 19 :Eu, Ce/polydimethylsiloxane composites could be applied in advanced anti-counterfeiting and information encryption with higher security in both the bright and dark fields.
危险品化学品经营许可证（带存储）