Fan Tianjiao, Liu Qiwei, Zhang Hai, Wang Xuewen, Zhang Dongdong, Duan Lian
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China.
Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory, Xianhu hydrogen Valley, Foshan, 528200, China.
Adv Mater. 2024 Nov;36(45):e2408816. doi: 10.1002/adma.202408816. Epub 2024 Sep 17.
A fast reverse intersystem crossing (RISC) remains an ongoing pursuit for multiresonance (MR) emitters but faces formidable challenges, particularly for indolocarbazole (ICz) derived ones. Here, heavy-atom effect is introduced first to construct ICz-MR emitter using a sulfur-containing substitute, simultaneously enhancing both spin-orbit and spin-vibronic coupling to afford a fast RISC with a rate of 1.2 × 10 s, nearly one order of magnitude higher than previous maximum values. The emitter also exhibits an extremely narrow deep-blue emission peaking at 456 nm with full-width at half-maxima of merely 12 nm and a photoluminescence quantum yield of 92%. Benefiting from its efficient triplet upconversion capability, this emitter achieves not only a high maximum external quantum efficiency (EQE) of 31.1% in organic light-emitting diodes but also greatly alleviates efficiency roll-off, affording record-high EQEs of 29.9% at 1000 cd m and 18.7% at 5000 cd m among devices with ICz-MR emitters.
对于多共振（MR）发光体而言，快速反向系间窜越（RISC）仍是一个持续追求的目标，但面临着巨大挑战，尤其是对于吲哚并咔唑（ICz）衍生的发光体。在此，首次引入重原子效应，使用含硫取代基构建ICz-MR发光体，同时增强自旋轨道和自旋振子耦合，以实现速率为1.2×10 s的快速RISC，比之前的最大值高出近一个数量级。该发光体还表现出极窄的深蓝色发射，在456 nm处达到峰值，半高宽仅为12 nm，光致发光量子产率为92%。受益于其高效的三线态上转换能力，该发光体不仅在有机发光二极管中实现了31.1%的高最大外量子效率（EQE），而且极大地缓解了效率滚降，在含有ICz-MR发光体的器件中，在1000 cd m时实现了创纪录的29.9%的高EQE，在5000 cd m时实现了18.7%的高EQE。
