1,3,4-oxadiazole-based deep-blue thermally activated delayed fluorescence emitters for organic light emitting diodes

Zhaoning Li, Wenbo Li, Changmin Keum, Emily Archer, Baomin Zhao, Alexandra Martha Zoya Slawin, Wei Huang, Malte Christian Gather, Ifor David William Samuel, Eli Zysman-Colman

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
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Abstract

A series of four 1,3,4-oxadiazole-based thermally activated delayed fluorescence (TADF) derivatives are reported as emitters for organic light emitting diodes (OLEDs). As a function of the nature of the substituent on the weak 1,3,4-oxadiazole acceptor their emission color could be tuned from green-blue to blue. The highly twisted conformation between carbazoles and oxadiazoles results in effective separation of the HOMO and the LUMO resulting in a small singlet-triplet splitting. The corresponding singlet-triplet energy gaps (∆EST) range from 0.22 to 0.28 eV resulting in an efficient reverse intersystem crossing (RISC) process and moderate to high photoluminescence quantum yields (ΦPL), ranging from 35 to 70% in a DPEPO matrix. Organic light-emitting diodes (OLEDs) based on i-2CzdOXD4CF3Ph achieve maximum external quantum efficiency (EQEmax) of up to 12.3% with a sky-blue emission at CIE of (0.18, 0.28) while the device based on i-2CzdOXDMe shows blue emission at CIE of (0.17, 0.17) with a maximum EQE of 11.8%.
Original languageEnglish
Pages (from-to)24772-24785
JournalJournal of Physical Chemistry
Volume123
Issue number40
Early online date16 Sept 2019
DOIs
Publication statusPublished - 10 Oct 2019

Keywords

  • Oxadiazole
  • TADF
  • OLED
  • Orientation
  • Transition dipole
  • Blue emitter

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