Bright and efficient red emitting electroluminescent devices fabricated from ternary europium complexes

Muhammad S. Khan, Rashid Ilmi, Weidong Sun, José D.L. Dutra, Willyan F. Oliveira, Liang Zhou, Wai Yeung Wong, Paul R. Raithby

Research output: Contribution to journalArticle

Abstract

The photophysical properties of two previously synthesized, highly efficient, bright red emitting complexes [Eu(btfa)3DPEPO] (CIE, 0.672; 0.326) (Eu-1) and [Eu(nta)3DPEPO] (CIE, 0.673; 0.326) (Eu-2) (btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione, nta = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione and DPEPO = bis(2-(diphenylphosphino)phenyl)ether oxide) are reported. The complexes have been used as dopants to fabricate several single and double emitting layer (EML) electroluminescent (EL) devices. At the optimum doping concentration of 4 wt%, the single EML device ofEu-1exhibited a pure red color with an external quantum efficiency (EQE) of 2.9% and a maximum brightness (B) = 1320 cd m−2, maximum current efficiency (ηc) = 4.08 cd A−1, maximum power efficiency (ηp) = 3.37 lm W−1with a very low turn-on voltage (Vturn-on) = 3.8 V. Importantly, the single EML device ofEu-2at the optimum doping concentration exhibited pure red EL with EQE of 6.0% with the best EL performance:B= 2108 cd m−2c= 8.45 cd A−1, andηp= 6.98 lm W−1at a very lowVturn-on= 3.5 V. The performances of this device are among the best reported for devices incorporating a europium complex as a red emitter. Furthermore, the EL performances were achieved at the current density of 10 mA cm−2, thereby alleviating a serious efficiency roll-off as a major obstacle to the development of Eu-complex based EL devices.

Original languageEnglish
Pages (from-to)5600-5612
Number of pages13
JournalJournal of Materials Chemistry C
Volume8
Issue number16
Early online date23 Mar 2020
DOIs
Publication statusPublished - 28 Apr 2020

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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