Zhang Xianhe, Chong Kok Chan, Xie Zongliang, Liu Bin
Integrative Sciences and Engineering Program, NUS Graduate School, National University of Singapore, Singapore, 117585, Singapore.
Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117585, Singapore.
Angew Chem Int Ed Engl. 2023 Nov 6;62(45):e202310335. doi: 10.1002/anie.202310335. Epub 2023 Oct 6.
Dual-mode emission materials, combining phosphorescence and delayed fluorescence, offer promising opportunities for white-light afterglow. However, the delayed fluorescence lifetime is usually significantly shorter than that of phosphorescence, limiting the duration of white-light emission. In this study, a carbazole-based host-guest system that can be activated by both ultraviolet (UV) and visible light is reported to achieve balanced phosphorescence and delayed fluorescence, resulting in a long-lived white-light afterglow. Our study demonstrated the critical role of a charge transfer state in the afterglow mechanism, where the charge separation and recombination process directly determined the lifetime of afterglow. Simultaneously, an efficient reversed intersystem crossing process was obtained between the singlet and triplet charge transfer states, which facilitating the delayed fluorescence properties of host-guest system. As a result, delayed fluorescence lifetime was successfully prolonged to approach that of phosphorescence. This work presents a delayed fluorescence lifetime improvement strategy via doping method to realize durable white-light afterglow.
结合磷光和延迟荧光的双模式发光材料为白光余辉提供了广阔的应用前景。然而，延迟荧光寿命通常比磷光寿命短得多，这限制了白光发射的持续时间。在本研究中，报道了一种基于咔唑的主客体体系，该体系可被紫外光（UV）和可见光激活，以实现磷光和延迟荧光的平衡，从而产生长寿命的白光余辉。我们的研究证明了电荷转移态在余辉机制中的关键作用，其中电荷分离和复合过程直接决定了余辉的寿命。同时，在单重态和三重态电荷转移态之间获得了有效的反向系间窜越过程，这促进了主客体体系的延迟荧光特性。结果，延迟荧光寿命成功延长至接近磷光寿命。这项工作提出了一种通过掺杂方法提高延迟荧光寿命的策略，以实现持久的白光余辉。
