Solid experimental evidence for reverse intersystem crossing from high-lying triplet states: A case study on hot exciton mechanism in OLEDs
Solid experimental evidence for reverse intersystem crossing from high-lying triplet states: A case study on hot exciton mechanism in OLEDs
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DOI：
10.1063/5.0081246
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发表时间：
2022-02-21
影响因子：
4
通讯作者：
Ma, Yuguang
中科院分区：
文献类型：
--
作者：
Chen, Liangjian;Qiao, Xianfeng;Ma, Yuguang
热激子已被尝试在有机发光二极管(OLED)中利用三重激子。由于高位三重态(T-n，n>；=2)的瞬变和暗态性质，描述热激子机制的规范方法还没有得到彻底的发展。在这里，一种结合瞬时光致发光和磁致发光(MEL)测量的常规技术已经被证明可以显示5，6，11，12-四苯基萘(Rubrene)分子从T-2态到S-1态的反向系间交叉过程。由于红宝石的T-1远低于S-1，而T-2与S-1共振，因此被选为模型体系。这个热激子过程打开了一条额外的路径，标记为Dexter能量传递通道((CT)-C-3->；T-2->；S-1，DET通道)，以及众所周知的福斯特共振能量传递通道((CT)-C-1->；S-1)，将宿主能量传递给客人。在适当的近似下，在热激子过程辅助下的DET通道可以贡献约46.6%的激子对Rubrene S-1和Rubrene掺杂器件中83.4%的Rubrene发射。这些研究为OLED中的热激子过程的可视化建立了一个原位规范的表征框架。由AIP出版公司独家授权出版。
Hot excitons have been attempted to utilize the triplet excitons in organic light-emitting diodes (OLEDs). Due to the transient and dark nature of high-lying triplet states (T-n, n >= 2), the normative methods to characterize the hot exciton mechanism have not been thoroughly developed. Here, a normal technique combining transient photoluminescence and magneto-electroluminescence (MEL) measurements has been proven to visualize the reverse intersystem crossing process from T-2 to S-1 states in 5,6,11,12-tetraphenylnaphthacene (rubrene) molecules. Rubrene is chosen as a model system since its T-1 is far below S-1 and T-2 is resonant with S-1. This hot exciton process opens an additional route, marked as Dexter energy transfer channel ((CT)-C-3 -> T-2 -> S-1, DET channel), together with the well-known Forster resonance energy transfer channel ((CT)-C-1 -> S-1) to transfer the host energy to the guest. With proper approximates, the DET channel assisted by the hot excitons process can contribute about 46.6% excitons to rubrene S-1 and 83.4% rubrene emission in rubrene-doped devices. These studies set an in situ normative characterizing frame to visualize the hot excitons process in OLEDs. Published under an exclusive license by AIP Publishing.