High stability and luminescence efficiency in donor-acceptor neutral radicals not following the Aufbau principle.
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Guo, H., Peng, Q., Chen, X., Gu, Q., Dong, S., Evans, E., Gillett, A., et al. (2019). High stability and luminescence efficiency in donor-acceptor neutral radicals not following the Aufbau principle.. Nature Materials, 18 977-984. https://doi.org/10.1038/s41563-019-0433-1
With their unusual electronic structures, organic radical molecules display luminescence properties potentially relevant to lighting applications; yet, their luminescence quantum yield and stability lag behind those of other organic emitters. Here, we designed donor-acceptor neutral radicals based on an electron-poor perchlorotriphenylmethyl or tris(2,4,6-trichlorophenyl)methyl radical moiety combined with different electron-rich groups. Experimental and quantum-chemical studies demonstrate that the molecules do not follow the Aufbau principle: the singly occupied molecular orbital is found to lie below the highest (doubly) occupied molecular orbital. These donor-acceptor radicals have a strong emission yield (up to 54%) and high photostability, with estimated half-lives reaching up to several months under pulsed ultraviolet laser irradiation. Organic light-emitting diodes based on such a radical emitter show deep-red/near-infrared emission with a maximal external quantum efficiency of 5.3%. Our results provide a simple molecular-design strategy for stable, highly luminescent radicals with non-Aufbau electronic structures.
External DOI: https://doi.org/10.1038/s41563-019-0433-1
This record's URL: https://www.repository.cam.ac.uk/handle/1810/299679
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