Long-lived room temperature phosphorescence of halogen-doped carbon dots/SiO2 composites and their anti-counterfeiting applications

Room temperature phosphorescent (RTP) materials have promising application in display lighting, environmental monitoring, and information encryption. In this study, a series of RTP halogen doped carbon dots/SiO 2 composites (RTP X-CDs/SiO 2 , X = F, Cl, Br, I) with long lifetime and tunable particle size were successfully prepared by two-step process involving solvothermal and calcination. The effects of various halogen dopants on the phosphorescence properties and morphologies of the RTP X-CDs/SiO 2 composites were thoroughly investigated. Among them, RTP F-CDs/SiO 2 exhibit an ultra-long lifetime of 1.28 s, a phosphorescence quantum yield of 19.76 %, and remarkable stability against temperature variations, acid and alkali conditions, and exposure to polar solvents. Therefore, RTP F-CDs/SiO 2 were further incorporated into silicone resin to fabricate phosphorescent films, and optical and hydrophobic properties of films with varying RTP F-CDs/SiO 2 mass fractions (2.5 %–15.0 %) were systematically explored. The films demonstrate excellent fluorescence and RTP performance, highlighting their potential for advanced anti-counterfeiting and information encryption.