1,10-Phenanthroline-5-amine derived N-doped carbon dots for long-lived visible-light-activated room temperature phosphorescence in the matrix and information encryption application

Room temperature phosphorescence (RTP) materials have received a lot of attention. However, it is still a challenge to realize the practical application of RTP excited under visible light. Herein, five different carbon dots (CDs) were prepared using 1,10-phenanthroline-5-amine (Aphen) as the co-carbon source and nitrogen source, and several polymer-based RTP films were prepared by simple doping. It was found that the phosphorescence emission behavior of polymer films was changed by the surface state structure of different CDs. Non-radiative transition of the triplet excitons of Aphen structure on the CDs surface was effectively inhibited by the hydrogen bonding interaction and the fixed domain-limiting effect of the polymer matrix. Meanwhile, the Aphen structure was bound to the CDs through covalent interaction, which further suppressed the molecular vibration, realizing the efficient organic RTP. The phosphorescence lifetime of the prepared ACCDs-PVA films reached 352.88 ms with a photoluminescence quantum yield of 36.7%. In addition, the dye RhB was co-doped in the ACCDs-PVA system to modulate the afterglow color of the materials via the triplet to single-state energy resonance transfer (TS-FRET) process. Finally, we also developed stable ACCDs-EPO RTP material by exploiting the dense three-dimensional network structure and hydrophobic property of the cured epoxy resin (EPO) matrix. The as-constructed long-lived RTP materials can be employed in information encryption.