One-pot synthesis of aggregation-induced multi-emission and solid-state room-temperature-phosphorescence carbon dots

Multi-emission carbon dots (M-CDs) have broad applications. However, reports of the synthesis of M-CDs and their emission mechanism are limited. In this study, M-CDs with three emissions are synthesized by a one-pot solvothermal method, and the luminescence mechanism is investigated in detail. The prepared M-CDs show significant concentration-dependent properties. For high-concentration M-CDs (HC CDs) , the surface-defect and carbon-core luminescence states are related to emission centers at 423 and 586 nm, respectively. The emission center at 493 nm are mainly due to the self-absorption of M-CDs. Conversely, low-concentration M-CDs (LC CDs) have 423 and 586 nm emissions. The blue CDs (B-CDs) and red CDs (R-CDs) are extracted from the prepared M-CD solution. The structural and optical properties indicate that the 493 nm peak is related to aggregation and self-absorption between B-CDs and R-CDs in HC CDs. Surprisingly, solid CDs (S-CDs) with solid-state room-temperature phosphorescence (RTP) are simultaneously obtained during the preparation of the M-CDs. The mechanism investigation results show that S-CDs are composed of CDs and NaHCO 3 , and NaHCO 3 acts as an oxygen barrier to prevent the quenching of the triplet and rigidly holds the luminescent guests to suppress vibrational dissipation. The M-CDs are successfully applied to detect Morin, while the S-CDs are demonstrated for optical anti-counterfeiting applications.