The development of multicolor carbon dots and their applications in the field of anti-counterfeiting.

The diversity of photoluminescence emission of multicolor carbon dots (mCDs) greatly broadens their application field. Counterfeiting is a problem that has serious consequences for individuals and society. The fluorescent ink based on mCDs has been developed due to their low toxicity and good resistance to photobleaching in the field of anti-counterfeiting. In the background, the preparation strategies of mCDs were discussed in detail, including top-down method and bottom-up method. The common carbon sources for the preparation of mCDs were further summarized, such as phenylenediamine class, amino-substituted naphthalene class, dihydroxyhenzene and benzoquinone class, biomass, and other common carbon sources. Furthermore, in order to understand the structure of CDs, this paper focused on the classification and common characterization techniques of CDs. In addition, the application of mCDs as fluorescent ink in the field of anti-counterfeiting was classified by simple anti-counterfeiting and good multiple anti-counterfeiting. Finally, the paper offered insight into the future development prospects of CDs-based fluorescent ink based on the current development trends.