Carbon Quantum Dots with Highly Efficient Bandgap Emission for Electroluminescent Light-Emitting Diodes

Carbon quantum dots (CQDs) feature bright and tunable photoluminescence, solution processability, and low toxicity, showing great potential in optoelectronics. The multicolor fluorescent CQDs were first fabricated as active layers in our lab, and then the high-performance electroluminescent warm white light-emitting diodes (LEDs) were obtained with the synthesized bright red CQDs. More significantly, through designing the triangular structure of the carbon core, fluorescent CQDs first achieved the narrow-bandwidth (∼30 nm) electroluminescent LEDs with appreciable stability, high color purity, and high luminescence performance. These results lay the foundation for the development of next-generation high performance displays based on CQDs. Here, we will report the large-scale synthesis of CQDs with near-unity photoluminescence quantum yield and the synthesis of red (625 nm) phosphorescent carbon quantum dot organic frameworks (CDOFs) with a quantum yield of up to 42.3% and realization of high-efficiency red phosphorescent electroluminescent LEDs. The LEDs based on the CDOFs exhibited a red emission with a maximum luminance of 1818 cd m −2 and an EQE of 5.6%. This work explores the possibility of a new perspective for developing high-performance CQD-based electroluminescent LEDs. References Yuxin Shi, Louzhen Fan, et al., Red Phosphorescent Carbon Quantum Dot Organic Framework-Based Electroluminescent Light-Emitting Diodes Exceeding 5% External Quantum Efficiency, Am. Chem. Soc. 2021, 143, 45, 18941–18951 Ting Yuan, Louzhen Fan, et al., Carbon Quantum Dots with Near-Unity Quantum Yield Bandgap Emission for Electroluminescent Light-Emitting Diodes, Angew. Chem. Int. Ed. 2023, e202218568. Fanglong Yuan，Louzhen Fan, et al., Engineering triangular carbon quantum dots with unprecedented narrow bandwidth emission for multicolored LEDs, Nat. Commun., 2018, 9, 2249. Figure 1