Deep blue oxadiazole-containing thermally activated delayed fluorescence emitters for organic light-emitting diodes

Michael Yin Wong, Simonas Krotkus, Graeme Copley, Wenbo Li, Caroline Murawski, David Hall, Gordon Hedley, Marie Jaricot, David B. Cordes, Alexandra M. Z. Slawin, Yoann Olivier, David Beljonne, Luca Muccioli, Mónica Moral, Juan Carlos Sancho-García, Malte C Gather, Ifor D. W. Samuel, Eli Zysman-Colman

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Abstract

A series of four novel deep blue to sky blue thermally activated delayed fluorescence (TADF) emitters (2CzdOXDMe, 2CzdOXD4MeOPh, 2CzdOXDPh and 2CzdOXD4CF3Ph) have been synthesized and characterized. These oxadiazole-based emitters demonstrated bluer emission compared with reference emitter 2CzPN thanks to the weaker acceptor strength of oxadiazole moieties. In particular, the oxadiazole compounds doped in hosts (mCP and PPT) emitted from 435-474 nm with photoluminescence quantum yields ranging from 14%-55%. The emitters possess relatively large singlet-triplet excited state energy gaps (ΔEST) from 0.25-0.46 eV resulting in long lifetimes of the delayed components ranging from 4.8 to 25.8 ms. Electroluminescent devices using these oxadiazole emitters as dopant emitters gave emission maxima (λEL) from 446 nm to 474 nm with maximum external quantum efficiencies ranging from 4.2-11.2%.
Original languageEnglish
JournalACS Applied Materials & Interfaces
VolumeIn press
Early online date7 Sept 2018
DOIs
Publication statusE-pub ahead of print - 7 Sept 2018

Keywords

  • Thermally activated delayed fluorescence
  • Organic light emitting diodes
  • Oxadiazoles
  • Blue emitters
  • DFT calculations

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