One-step synthesis of self-quenching-resistant carbon dot phosphors and their application in fingerprint identification and anti-counterfeiting

Abstract

Owing to the aggregation-caused quenching effects resulting from π–π interactions or resonance energy transfer, obtaining luminescent carbon dots (CDs) in solid state still remains a huge challenge. Herein, a facile one-step strategy for the preparation of solid-state carbon dot phosphors with high yield (around 80%) has been developed via a microwave-assisted reaction between malic acid and levofloxacin. Thus, solid-state carbon dots with fluorine and nitrogen as heteroatomic dopants were successfully synthesized with bright blue fluorescence under UV light and a quantum yield of 18.9%. Through optical analysis, the fluorescence of the obtained fluorine, nitrogen-doped carbon dots (FNCDs) in both the solution and solid state was observed as excitation-independent. In order to investigate the solid state emission mechanism, additional structural analysis was conducted. The skeleton of levofloxacin was retained in solid state CDs together with the carbon-containing and oxygen-containing functional groups, which suppress the π–π interactions, thus resulting in self-quenching resistant carbon dot powder. Moreover, the phosphors were further used for fingerprint identification and anti-counterfeiting, confirming their potential practical applications in these areas.