Conventional optical anti-counterfeiting strategies are based on the single-color emission, which are easily deciphered and thus greatly limited in the application of information security. Herein, a multimodal dynamic optical information coding with red, green, and blue (RGB) tricolors has been developed by photoluminescence (PL), persistent luminescence (PersL), thermally stimulated luminescence (TSL), and thermally stimulated persistent luminescence (TSPL). The BaSi 2 O 2 N 2 :Eu 2+ phosphors with a blue emission peak at 494 nm were used as the crucial blue optical information coding material and exhibited the distinctive response properties to light, heat, and force stimuli with intrinsic trap depths of 0.674 and 0.82 eV. More importantly, by combining the red Sr 2 Si 5 N 8 :Eu 2+ ,Dy 3+ and green SrSi 2 O 2 N 2 :Eu 2+ ,Dy 3+ nitride phosphors, a RGB tricolor and multimodal strategy has been successfully developed for anti-counterfeiting applications. The "RGB tricolor flower" with RGB emissions is given as a typical example to achieve the dynamic display of optical information encryption and decoding through the various PL, PersL, TSL, and TSPL modes. Finally, the traditional quick response (QR) code mechanism has been integrated into the design of multi-information encrypted RGB tricolor anti-counterfeiting devices with different identifiabilities of the encrypted information in natural light, PL, PersL, TSL, and TSPL modes. The laminated layers of RGB QR code patterns containing different specific information, such as "DLPU" and "116034", can be effectively recognized in the corresponding modes. The design strategy of RGB tricolor and multimodal optical information encryption and decoding devices in this work greatly improves the security level of advanced optical information technologies and extends the potential applications in dynamic anti-counterfeiting fields.

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Advanced fluorescent anticounterfeiting technology has received widespread attention due to the lack of sufficient security of traditional anti-counterfeiting. Hence, there is a great challenge to continuously develop multi-level anti-counterfeiting technology with higher security. Here, we develop a desired fluorescent anticounterfeiting technology based on CsPbBr 3 perovskite quantum dots (PQDs) and CaAl 2 O 4 :Eu 2+ , Nd 3+ composites with persistent luminescence properties. CsPbBr 3 PQDs can be formed on the surface of the CaAl 2 O 4 host and exhibit an average diameter of around 3.5 nm. The photoluminescence (PL) intensity of CsPbBr 3 PQDs/CaAl 2 O 4 composites is greatly enhanced to 125 times compared to that of pure CsPbBr 3 PQDs, and the desired narrow FWHM of 19 nm is achieved under near-ultraviolet irradiation. Furthermore, highly stable CsPbBr 3 PQDs/CaAl 2 O 4 :Eu 2+ , Nd 3+ composites with triple-modal (UV, IR, and thermal) fluorescent anti-counterfeiting characteristics were developed and used in fabricating anti-counterfeiting labels through screen-printing technology. The results open up a pathway to enhance the photoluminescence properties and stability of perovskite quantum dots for the advanced fluorescent anticounterfeiting application.

As blue emitting component in phosphor-converted white-light-emitting-diodes (pc-wLEDs) encapsulated with near-ultraviolet (NUV) chips, Eu2+ activated fluorapatite structure phosphors play key roles because of strong structural stability and excellent photoluminescent properties. A series of M5(PO4)3F: Eu2+ (M = Ca, Sr) samples have been newly prepared by deposition-precipitation process (DP) and exhibited a 6.7-fold enhancement of photoluminescent (PL) intensity due to the highly dispersed Eu2+ luminescence centers when compared with the reference samples synthesized via traditional solid-state reaction method (SSR). Detailed analysis of crystal field around Eu2+ and the nonlinear fitting of PL spectra concludes that Eu2+ activators with the 4f6 → 4f75d transition preferentially replace Ca1 in 4f symmetry sites leading to a fitted peak at 446 nm and the other sites of 6h are contributed to the 479 nm emitting of Eu2+ ions. Remarkably, tunable chromaticity of DP-M5(PO4)3F: Eu2+ with high color purity (97.79%) retains steady photoelectric converting and full width at half maxima (FWHM) of 46 nm in the device of DP-FAp: 0.03Eu2+@365 nm LED under diverse driving currents, which perfectly satisfies the requirements of excitation light source for oral photocuring materials. Further, the 123.4% color gamut of National Television System Committee (NTSC) standard is efficiently obtained by matching Sr5(PO4)3F: Eu2+, CsPbBr3 and Lu3Al5O12: Mn4+ phosphors with a 365 nm chip (1 W) to achieve high-quality white light (CRI value reaches to 86, CCT is 7107 K and CIE chromaticity coordinate arrives at (0.292, 0.376), indicating a potential candidate for dentistry curing light and high-quality NUV excited pc-wLEDs.

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