Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK.
Humboldt Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939, Köln, Germany.
Angew Chem Int Ed Engl. 2023 Apr 11;62(16):e202218911. doi: 10.1002/anie.202218911. Epub 2023 Mar 8.
The use of thermally activated delayed fluorescence (TADF) emitters and emitters that show preferential horizontal orientation of their transition dipole moment (TDM) are two emerging strategies to enhance the efficiency of OLEDs. We present the first example of a liquid crystalline multi-resonance TADF (MR-TADF) emitter, DiKTa-LC. The compound possesses a nematic liquid crystalline phase between 80 °C and 110 °C. Importantly, the TDM of the spin-coated film shows preferential horizontal orientation, with an anisotropy factor, a, of 0.28, which is preserved in doped poly(vinylcarbazole) films. Green-emitting (λ =492 nm) solution-processed OLEDs based on DiKTa-LC showed an EQE of 13.6 %. We thus demonstrate for the first time how self-assembly of a liquid crystalline TADF emitter can lead to the so-far elusive control of the orientation of the transition dipole in solution-processed films, which will be of relevance for high-performance solution-processed OLEDs.
使用热激活延迟荧光（TADF）发射器和显示其跃迁偶极矩（TDM）优先水平取向的发射器是两种提高 OLED 效率的新兴策略。我们提出了第一个液晶多共振 TADF（MR-TADF）发射器 DiKTa-LC 的示例。该化合物在 80°C 和 110°C 之间具有向列液晶相。重要的是，旋涂薄膜的 TDM 显示出优先的水平取向，各向异性因子 a 为 0.28，在掺杂聚（乙烯基咔唑）薄膜中得以保留。基于 DiKTa-LC 的绿色发射（λ =492nm）溶液处理 OLED 的 EQE 为 13.6%。因此，我们首次展示了如何通过液晶 TADF 发射器的自组装来实现溶液处理薄膜中跃迁偶极取向的难以捉摸的控制，这对于高性能溶液处理 OLED 具有重要意义。
