Li Xin, Wang Yi-Lin, Chen Chan, Ren Yan-Yan, Han Ying-Feng
Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, People's Republic of China.
Nat Commun. 2022 Sep 13;13(1):5367. doi: 10.1038/s41467-022-33130-1.
Organic radicals, which have unique doublet spin-configuration, provide an alternative method to overcome the efficiency limitation of organic light-emitting diodes (OLEDs) based on conventional fluorescent organic molecules. Further, they have made great breakthroughs in deep-red and near-infrared OLEDs. However, it is difficult to extend their fluorescence into a short-wavelength region because of the natural narrow bandgap of the organic radicals. Herein, we significantly expand the scope of luminescent radicals by showing a new platform of carbon-centered radicals derived from N-heterocyclic carbenes that produce blue to green emissions (444-529 nm). Time-dependent density functional theory calculations and experimental investigations disclose that the fluorescence originates from the high-energy excited states to the ground state, demonstrating an anti-Kasha behavior. The present work provides an efficient and modular approach toward a library of carbon-centered radicals that feature anti-Kasha's rule emission, rendering them as potential new emitters in the short-wavelength region.
具有独特双电子自旋构型的有机自由基，为克服基于传统荧光有机分子的有机发光二极管（OLED）的效率限制提供了一种替代方法。此外，它们在深红色和近红外OLED方面取得了重大突破。然而，由于有机自由基天然的窄带隙，很难将其荧光扩展到短波长区域。在此，我们通过展示一个源自N-杂环卡宾的碳中心自由基新平台，显著扩展了发光自由基的范围，该平台产生蓝色至绿色发射（444-529nm）。含时密度泛函理论计算和实验研究表明，荧光源于从高能激发态到基态的跃迁，呈现出反卡莎行为。目前的工作为构建具有反卡莎规则发射特性的碳中心自由基库提供了一种高效且模块化的方法，使它们成为短波长区域潜在的新型发光体。
