Carbon dots (CDs), an emerging class of zero-dimensional carbon-based nanomaterials, have attracted growing interest due to their excellent photoluminescence properties, good solubility, low toxicity, and facile surface functionalization. These unique advantages have enabled diverse applications in bioimaging, optoelectronic devices, sensing, and catalysis. Nevertheless, despite rapid progress, the field still faces several pressing scientific and technological challenges.
A fundamental issue lies in the lack of a unified understanding of the emission mechanism. Proposed models include quantum confinement, surface defect states, crosslink-enhanced emission, clusteroluminescent states, carbon-core states, and molecular-state luminescence. However, fluorescence behaviors vary considerably with different synthetic routes, resulting in inconsistencies that hinder precise regulation of optical properties. From an application perspective, although CDs show relatively high quantum yields, their quantum yields in the red and near-infrared regions remain insufficient, limiting their potential in advanced displays, energy conversion, and optoelectronics.
Bin Liu, North University of China, Xinghong Zhang, Zhejiang University, China, and colleagues reported the rational synthesis of red, green, and blue emissive CDs (RGB-CDs) by tailoring the ratio of o-phenylenediamine to phytic acid, yielding quantum yields of 60.3%, 68.7%, and 19.0%, respectively. Experimental investigations, combined with theoretical calculations, reveal the underlying emission mechanisms of the RGB-CDs. Based on this, the team demonstrated several high-performance devices:
- White-light LEDs (WLEDs) with a color rendering index up to 98, suitable for high-fidelity lighting in scientific, medical, and advanced illumination scenarios.
- Luminescent solar concentrators (LSCs) employing a tandem design of red and green CDs, achieving a power conversion efficiency of 1.6% with high transparency, promising for building-integrated photovoltaics.
- A self-powered lighting system, wherein integrated WLED–LSC modules sustained ~6 hours of LED illumination after daytime charging.
Importantly, this work highlights the critical role of precursor ratios in determining the formation pathways and luminescence properties of CDs, while showing how surface groups affect emission. Building on previous reports [1-4], which inferred clusteroluminescence in CDs, this study provides the first experimental and theoretical evidence of clusteroluminescence driven by through-space interactions of heteroatoms. This finding offers new theoretical insights into the emission mechanism of CDs and advances their rational design for optoelectronic applications.
- Highly Photoluminescent RGB-Carbon Dots and Their Integration Applications in Light-Emitting Diodes and Luminescent Solar Concentrator
Bin Liu, Genghong Huang, Yaling Wang, Huijie Bai, Suping Jia, Fu-de Ren, Xinghong Zhang
Aggregate 2025
https://doi.org/10.1002/agt2.70167
[1] Bin Liu, Bo Chu, Ya-Ling Wang, Lan-Fang Hu, Shengliang Hu, Xing-Hong Zhang, Carbon dioxide derived carbonized polymer dots for multicolor light-emitting diodes, Green Chem. 2021, 23, 422-429. https://doi.org/10.1039/D0GC03333B
[2] Bin Liu, Zheng Chen, Bo Chu, Ya-Ling Wang, Ning Li, Huinian Zhang, Yongzhen Yang, Shengliang Hu, Xing-Hong Zhang, Clustering-Induced White Light Emission from Carbonized Polymer Dots, Adv. Photonics Res. 2021. https://doi.org/10.1002/adpr.202000161
[3] Ya-Ling Wang, Bin Liu, Jia-Liang Yang, Xiao-Han Cao, Yong-Zhen Yang, Qing Yang, Andreas Greiner, Jun-Ting Xu, Xing-Hong Zhang, Hyperbranched Fractal Nanocarbons for Bright Photoluminescence in Solid State, Adv. Optical Mater. 2019. https://doi.org/10.1002/adom.201900659
[4] Yaling Wang, Genghong Huang, Zishan Yan, Guangqun Cao, Wenjing Zheng, Shengliang Hu, Bin Liu, Yongzhen Yang, Solvent-regulated multicolor-emissive carbon dots and their application in multicolor light-emitting diodes, J. Mater. Chem. C 2024, 12, 15051–15057. https://doi.org/10.1039/D4TC02518K
