Understanding excitonic behavior and electroluminescence light emitting diode application of carbon dots

Carbon dots (CDs), due to their low cost, high stability, and high luminous efficiency, have emerged as an excellent material for the emissive layer in next-generation electroluminescent light-emitting diodes (ELEDs). However, improving the efficiency of fluorescent CDs-based ELEDs remains challenging, primarily because it is difficult to utilize triplet excitons in the electroluminescence process. Therefore, enhancing the exciton utilization efficiency of CDs during electroluminescence is crucial. Based on this, we exploited the characteristic large exciton binding energy commonly found in CDs to develop exciton-emitting CDs. These CDs facilitate the radiative recombination of excitons during electroluminescence, thereby improving the electroluminescent efficiency. By rationally selecting precursors, we developed high quantum efficiency CDs and subsequently constructed CDs-based ELEDs. The blue-light device exhibited an external quantum efficiency of over 4 %. This study introduces a novel design concept for CDs, providing a new strategy for developing high-performance blue ELEDs based on CDs.