Phosphorescence Tuning of Fluorine, Oxygen-Codoped Carbon Dots by Substrate Engineering

Exploiting a precise and reproducible phosphorescence tuning strategy is crucial to tailor-design carbon dots (CDs) for premium gradient anticounterfeiting applications. Toward this target, we designed a facile substrate engineering technique to manipulate the phosphorescence of F, O-codoped CDs. Applying phenolic compounds with different numbers of hydroxyl groups as precursors, the contents of the C–O–C groups in CDs are effectively regulated for gaining outstanding phosphorescence performance as well as the introduction of the F-dopant. After excitation using a UV lamp followed by turning it off, the CDs/polyvinyl alcohol matrix can emit bright yellow room-temperature phosphorescence, which may derive from the synergistic effect of C–F and C–O–C in F and O-codoped CDs. After O and F form a bond, many lone pairs of electrons are generated, which is conducive to the excitation of n → π* and promotes the supplementation of triplet excitons. The phosphorescence tuning of CDs is realized by mixing different substrates, which can provide various phosphorescence lifetimes and colors. Discovering the unique properties, F, O-codoped CDs/substrates can be applied in gradient anticounterfeiting applications. This substrate engineering technique, showing unique and reproducibility with high efficiency, may further facilitate the potential applications of CDs.