Near-infrared emissive carbon dots with 33.96% emission in aqueous solution for cellular sensing and light-emitting diodes

Near-infrared emissive carbon dots (CDs) were synthesized by hydrothermal method. The as-prepared CDs exhibited a relatively high quantum yield (QY) of 33.96% in an aqueous solution, and the peak toward the near-infrared fluorescence reached 685 nm. The CDs exhibited pH-sensitive characteristics under strong acidic conditions. Even at pH = 0, the as-prepared CDs retained a high fluorescence intensity, which proved that they possessed good acid resistance. More importantly, the CDs were sensitive to the Fe3+ changes in living cells. In addition, they could also be used for white and red emissive LEDs. This discovery will expand the use of aqueous-phase high QY CDs in the field of living cell sensing and imaging.