In-situ embedding of carbon dots in a trisodium citrate crystal matrix for tunable solid-state fluorescence

It is still a challenging issue to achieve efficient and tunable fluorescent carbon dot (CD) powders. Herein, we report a novel and general solvothermal strategy to in-situ embedding CDs in trisodium citrate crystal matrix, and these CDs exhibit tunable emission from green to yellow and a high quantum yield up to 21.6% in solid state, comparable to that in solution. This intriguing fluorescence phenomenon may be caused by the space confinement from trisodium citrate crystal matrix, thus enabling CDs to effectively suppress the aggregation-induced luminescence quenching. The CD powders have been employed for fabricating white light-emitting devices on blue chips with adjustable color temperature. Moreover, solid-state lighting systems like flexible fluorescent films and plates have been demonstrated by using the CD powders as the luminescent medium. This work provides a facile way to achieve tunable solid-state fluorescence CD powders, which have promising applications in CDs-based luminescence devices.