Amorphization of Purely Organic Phosphors into Carbon Dots to Activate Matrix-Free Room-Temperature Phosphorescence for Multiple Applications

The insufficiency of effectively activating purely organic phosphorescence has greatly limited the development and application of purely organic phosphors. Herein, amorphization of purely organic phosphors into carbon dots (C-dots), namely, amorphization strategy, was designed for activating matrix-free room-temperature phosphorescence (RTP) of C-dots. Using citric acid and 2,4,6-trihydrazinyl-1,3,5-triazine (THT) as precursors, the obtained C-dots reserved the ordered structure similar to a THT single crystal in the interior of C-dots. The doped triazine overing is critical for RTP; it not only provides the n–π* transition center but also plays a key role in facilitating the intersystem crossing. The weak interactions among THT molecules, such as π···π stacking and hydrogen bond interactions, and the hydrogen bond among functional groups in the interior of C-dots, together with the steric hindrance formed by polymer-like structures of C-dots, served as matrices to embed and immobilize the emissive center, resulting in the afterglow with a lifetime of 66.4 ms. C-dot-based RTP was successfully used for digital encryption, information protection, and antibacterial protection. Most importantly, the universality of the amorphization strategy provided a simple and advantageous pathway for the activation of C-dot-based matrix-free RTP.