Facile preparation strategy of novel B₂O₃-modified carbon dots with 1.99 s ultra-long Room-Temperature phosphorescence for multidimensional encryption

Facile synthesis of Ultralong room-temperature phosphorescence (URTP) with super stability and long-afterglow are of great significance, but hard to achieve. Herein, a brilliant gram-scale and solvent-free pyrolysis treatment strategy has been developed to prepare high-performance URTP carbon dots (CDs) by regulating different temperature (250-500 °C). The optimized CDs (CD-400) showed room-temperature phosphorescence 1.99 s and lasting over 22 s to naked eyes, which is superior to most of the reported URTP CDs. Owing to the stabilization effects of the modified B₂O₃ layer on the surface, the homogenous distribution of CD-400 with the narrow diameter of 1.44 nm was constructed, displaying a superb stability through hydrogen-bond network. In addition, the doping atoms (N, O) greatly enhanced the n-π* transitions and stabilized triplet excitons radiative transitions, facilitating the effective intersystem crossing (ISC) and the RTP emissions. More importantly, the B₂O₃-modified CDs were successfully applied in the multi-level information encryption (time-resolved RTP performance) and fingerprint identification (bifurcation, whorl and termination details).