Preparation of Multicolor Room-Temperature Phosphorescence Carbon Dots by Changing the Conjugation Degree of Precursors for Information Encryption

as host protect matrix, achieving an ultralong lifetime (up to 1.597 s). Under 254 nm light excitation, blue RTP for 14 s of B-CDs can be visually observed. By increasing the conjugation degree of the precursor molecules and introducing 4-(1-naphthyl) naphthalene-1-boronic acid and pyren-1-ylboronic acid as guest phosphors, green CDs (G-CDs) and red CDs (R-CDs) were obtained, respectively. Theoretical calculations and band gap analyses suggest that larger conjugated structures can reduce the HOMO-LUMO energy level difference, thereby causing a redshift in emission wavelength. Last, these multicolor CDs composite were applied for information encryption.