Multiple Atoms Doped Carbon Dots with Room Temperature Phosphorescence for Anticounterfeiting and Information Encryption

Carbon dots (CDs) with room temperature phosphorescence (RTP) have emerged as popular luminescent materials in recent years. RTP CDs have a wide range of applications in several fields, such as anticounterfeiting, information encryption, sensors, and optoelectronics, due to their excellent optical properties, simple preparation process, etc. Therefore, it is significant to develop RTP CDs with a long lifetime and outstanding optical intensity. In the present work, N, P, and B atoms codoped into CDs (N, P, and B-CDs) were synthesized by a simple and green one-step hydrothermal method using arginine, phosphoric acid, and boric acid as precursors. The dense cross-linked network generated by hydrothermal carbonization and the effect of codoping of multiple atoms endowed N, P, and B-CDs with excellent phosphorescence properties. Under UV light, the N, P, and B-CDs showed blue fluorescence, and after the removal of the UV light, the afterglow of the RTP CDs visible to the naked eye was green and still persisted for about 12 s. The absolute photoluminescence quantum yield (QY) and phosphorescence lifetime of N, P, and B-CDs were 15.89% and 902 ms, respectively, indicating long-lifetime RTP CDs. Finally, this work exemplified the remarkable effectiveness of N, P, and B-CDs in anticounterfeiting and information encryption. This work provides an idea for the preparation of simple and efficient RTP CDs and a strategy for the field of anticounterfeiting.