Aromatic Amine-Improved Boron–Nitrogen-Doped Carbon Dots with Room-Temperature Phosphorescence for Anticounterfeiting

Abstract Carbon dots (CDs) not only possess a unique carbon skeleton and abundant surface functional groups but also have the advantages of eco-friendliness and low toxicity, making them ideal materials for achieving room-temperature phosphorescence (RTP) emission. In this work, a nitrogen precursor modulation strategy using m-phenylenediamine (MPD) and p-phenylenediamine (PPD) was utilized to synthesize boron- and nitrogen-doped RTP carbon dots (BNCDs). The as-prepared BNCDs can be effectively excited under both ultraviolet and visible irradiations. It exhibited superior room-temperature phosphorescence characteristics, including an RTP lifetime of up to 1634 ms for BNCDPPD and a total photoluminescence quantum yield of 25.42% for BNCDMPD. Moreover, BNCDMPD exhibited a long-lived afterglow visible to the naked eye for nearly 31 s. Compared with the carbon-chain structures of aliphatic amines, the rigid conjugated carbon skeletons derived from aminobenzene rings are more favorable for boosting the RTP performance of BNCDs. Furthermore, it was found that the type of precursor is a critical factor governing the generation of dynamic RTP emissions from BNCDs. Benefiting from their excellent RTP performances, these BNCDs hold promising prospects for practical scenarios including visualization of latent fingerprints (LFPs) and anticounterfeiting ink fabrication.