Use of pyrimidine and pyrazine bridges as a design strategy to improve the performance of thermally activated delayed fluorescence organic light emitting diodes

Paloma Lays dos Santos, Dongyang Chen, Rajamalli Pachai Gounder, Tomas Matulaitis, David Bradford Cordes, Alexandra Martha Zoya Slawin, Denis Jacquemin, Eli Zysman-Colman, Ifor David William Samuel

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)
12 Downloads (Pure)

Abstract

We present a study of two isomeric thermally activated delayed fluorescence (TADF) emitters 9,9'- (sulfonylbis(pyrimidine-5,2-diyl))bis(3,6-di-tert-butyl-9H-carbazole) (pDTCz-DPmS) and 9,9'- (sulfonylbis(pyrazine-5,2-diyl))bis(3,6-di-tert-butyl-9H-carbazole) (pDTCz-DPzS). The use of pyrimidine and pyrazine as bridging units between the electron donor and acceptor moieties is found to be advantageous compared to the phenyl- (pDTCz-DPS) and pyridine-based analogues (pDTCz-3DPyS and pDTCz-2DPyS). Conformational modulation of the donor groups as a function of the bridge results in high photoluminescence quantum yields (ΦPL > 68%) and small energy gaps between singlet and triplet excited states (ΔEST < 160 meV). OLEDs using pDTCz-DPmS and pDTCz-DPzS as emitters exhibit blue and green electroluminescence, respectively, with higher maximum external quantum efficiencies (EQEmax of 14% and 18%, respectively) and reduced efficiency roll-off as compared to the reference devices using pDTCz-DPS, pDTCz-3DPyS, and pDTCz-2DPyS as the emitters. Our results provide a more complete understanding on the impact of the bridge structure in D-A-D TADF systems on the optoelectronic properties of the emitter, and how the balance between color purity and EQE in the devices can be controlled, advancing the design strategies for TADF emitters.
Original languageEnglish
Pages (from-to)45171-45179
JournalACS Applied Materials & Interfaces
Volume11
Issue number48
Early online date7 Nov 2019
DOIs
Publication statusPublished - 4 Dec 2019

Keywords

  • TADF
  • Organic light emitting diodes
  • Pyrimidine
  • Pyrazine
  • Blue OLED
  • Intramolecular hydrogen bond

Fingerprint

Dive into the research topics of 'Use of pyrimidine and pyrazine bridges as a design strategy to improve the performance of thermally activated delayed fluorescence organic light emitting diodes'. Together they form a unique fingerprint.

Cite this