Red-emitting, self-oxidizing carbon dots for the preparation of white LEDs with super-high color rendering index

Carbon dots (CDs), as a kind of carbon nanomaterials, have attracted widespread attention due to their unique structure and excellent optical properties, and they are low-cost, environmentally friendly and biocompatible. However, the development of near-infrared (NIR) emission CDs remains a challenge. In this study, we successfully prepared CDs with a maximum emission of 714 nm using citric acid as the carbon source, thiourea and ammonium fluoride as the dopant source, and N,N-dimethylformamide as the solvent. The quantum yield (QY) is as high as 22.64%. Interestingly, the prepared CDs self-oxidize in the presence of oxygen, resulting in a blue shift of their emission. Therefore, they can be used to prepare white light-emitting diodes (WLEDs) without adding other fluorescent substances. Notably, the work presented herein constitutes the first report of WLEDs preparation from single CDs.