Efficient color-tunable room temperature phosphorescence through confining carbon dots in ionic crystal

Room temperature phosphorescence (RTP) materials are highly attractive in many fields, but it is still a great challenge to obtain RTP materials with color tunability. Herein, we report a new type of multicolor phosphorescence carbon dots (CDs) through confining CDs into rigid crystal network through the introduction of ionic bonds. The RTP color can rationally vary from green (553 nm) to orange-red (640 nm) under different excitation wavelengths. More importantly, the obtained CDs can also maintain their RTP emission in ethanol solution. The excitation-dependent property was owing to the existence of polychromatic emission centers on the surface of CDs, and the generation of RTP can be attributed to the ionic bond in CDs system to suppress non-radiative transition of triplet states. Based on this unique multicolor RTP phenomenon, the CDs were successfully applied in anticounterfeiting and light-emitting diodes. This finding not only provides a new strategy for the preparation of multicolor RTP materials but also reveals a great potential of CDs in developing novel optical materials.