Mesogenic groups control the emitter orientation in multi-resonance TADF emitter films

Dongyang Chen, Francisco Tenopala‐Carmona, Julius A. Knöller, Andreas Mischok, David Hall, Subeesh Madayanad Suresh, Tomas Matulaitis, Yoann Olivier, Pierre Nacke, Frank Gießelmann, Sabine Laschat*, Malte C. Gather*, Eli Zysman‐Colman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

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 (λEL = 492 nm) solution-processed OLEDs based on DiKTa-LC showed an EQEmax 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.
Original languageEnglish
Article numbere202218911
Number of pages12
JournalAngewandte Chemie International Edition
Volume62
Issue number16
Early online date8 Mar 2023
DOIs
Publication statusPublished - 11 Apr 2023

Keywords

  • TADF
  • OLED
  • Liquid crystal
  • Transition dipole moment

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