Synthesis of amphiphilic carbon quantum dots with phosphorescence properties and their multifunctional applications

Carbon quantum dots (CQDs) have been widely studied; however, nearly all CQDs can only be used either in aqueous phase or oil phase. There is much less attention on amphiphilic CQDs (ACDs) and their potential applications. In this work, ACDs were successfully prepared by a one-pot hydrothermal treatment of oil soluble N-doped CQDs. The obtained ACDs exhibit favorable aqueous solubility, high photoluminescence (PL) quantum yields, and excellent photostability, showing great potential in Fe³⁺ ion detection. Interestingly, up-conversion PL of the ACDs is also observed and successfully applied in two-photon cell imaging. In addition, the obtained ACDs can be homogeneously dispersed into polyvinyl alcohol (PVA) and polyurethane matrices. Importantly, a room temperature phosphorescence phenomenon can be detected in these ACD-based composites and the ACD/PVA composite films show an ultralong phosphorescence lifetime (450 ms), which expands the scope of research and applications of CQDs.