Synthesis of carbon dots with strong luminescence in both dispersed and aggregated states by tailoring sulfur doping

Carbon dots (CDots) with a strong greenish-yellow fluorescence in both dispersed and aggregated states are prepared. The as-prepared CDots with a size of 3.5 nm possess excellent biocompatibility, good photostability, strong solid-state luminescence, and remarkable resistance to organic solvent, allowing their applications in biological imaging in vitro and in vivo and as the color conversion layer for white light-emitting diodes.