Ultra-stable dual-color phosphorescence Carbon-Dot@Silica material for advanced anti-counterfeiting

Room temperature phosphorescence (RTP) materials have motivated massive attention due to their great advantages in anti-counterfeiting and optical encryption. However, the commonly used carbon-based RTP materials suffer from drawbacks of photobleaching, quenching and single phosphorescence color outputs, which obstruct their performance in high-level anti-counterfeiting techniques. Herein, we present a universal method for the fabrication of a [email protected] ([email protected]2) composite that possesses ultralong lifetime, high phosphorescence quantum efficiency (PQE), excellent luminescence stability, and dual-color phosphorescence emission. Taking advantage of the restriction by rigid network of SiO2 and stable covalent bonding between CDs and SiO2, the triplet excited states of CDs are stabilized. As a result, the [email protected]2 exhibit ultralong lifetime of 1.33 s and 0.38 s under excitation at 254 nm and 365 nm, respectively. Furthermore, the phosphorescence color of [email protected]2 can change from cyan to yellow when the exciting wavelength switches from 254 nm to 365 nm. The obtained [email protected]2 also exhibit outstanding characteristics of anti-photobleaching and phosphorescence stability in an aqueous solution. Based on the unique phosphorescent properties of the [email protected]2, a stable and dual-color phosphorescence security label is designed for advanced information encryption.