One-step synthesis of multicolor room temperature phosphorescent carbon dots for information encryption applications

Room temperature phosphorescent carbon dots (RTP CDs) are widely applied in fields due to their unique phosphorescent properties. However, some current synthesis methods for RTP CDs are relatively complex and the RTP CDs often have poor phosphorescence stability. Here, the multicolor RTP CDs with green and yellow was proposed in a one-step method. Using biuret as the precursor, the introduction of different matrices (boric acid and inorganic salts) makes the RTP CDs emitting different phosphorescence colors. Both of the RTP CDs exhibit excellent resistance to both prolonged UV exposure and ambient air. Structural analysis reveals that the hydrogen bonds formed between the RTP CDs and the matrix exhibits good oxygen-blocking and waterresistance properties, resulting in good phosphorescence stability. The carbonyl and nitrogen heterocycles on the biuret are the main contributors to the phosphorescent emission of the CDs. Moreover, the halogen bonds and covalent bonds between the CDs and the matrix also influence the phosphorescence emission wavelength. Additionally, the RTP CDs were successfully applied in information encryption. This study provides an effective strategy for preparing RTP CDs with improved phosphorescence stability.