Zhang Lu, Cheah Kok Wai
Department of Physics and Institute of Advanced Materials, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China.
Sci Rep. 2018 Jun 11;8(1):8832. doi: 10.1038/s41598-018-27238-y.
Thermally activated delayed florescence (TADF) materials can be an efficient host in organic LED (OLED). It is because it is possible to couple energetically the emission energy level of a dopant to the energy levels in the TADF material. In this work fluorescent emitters 2,3,6,7-tetrahydro-1,1,7,7,-tetramethyl-1H,5 H,11H-10-(2-benzothiazolyl)quinolizino-9,9a,1gh coumarin (c545t) and 5,6,11,12-tetraphenyltetracene (rubrene) were used as dopants in a blended TADF host; tris(4-carbazoyl-9-ylphenyl)amine (TCTA) with 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine (Tm3PyBPZ). The blended TADF host has an energy difference between the singlet and triplet excited states (ΔE) around 27 meV with the yield of reverse intersystem crossing (Ф) nearly 100%. This high Ф yield enhances the OLED performance with the c545t doped OLED having 11.9% external quantum efficiency and 10% for the rubrene doped OLED.
热激活延迟荧光（TADF）材料可成为有机发光二极管（OLED）中的高效主体材料。这是因为可以将掺杂剂的发射能级与TADF材料中的能级进行能量耦合。在本工作中，荧光发射体2,3,6,7-四氢-1,1,7,7-四甲基-1H,5 H,11H-10-(2-苯并噻唑基)喹嗪并-9,9a,1gh香豆素（c545t）和5,6,11,12-四苯基并四苯（红荧烯）被用作混合TADF主体材料中的掺杂剂；三（4-咔唑基-9-基苯基）胺（TCTA）与2,4,6-三（3'-（吡啶-3-基）联苯-3-基）-1,3,5-三嗪（Tm3PyBPZ）。该混合TADF主体材料的单重态和三重态激发态之间的能量差（ΔE）约为27 meV，反向系间窜越产率（Ф）接近100%。这种高Ф产率提高了OLED的性能，c545t掺杂的OLED的外量子效率为11.9%，红荧烯掺杂的OLED的外量子效率为10%。
