A tris β-diketonate europium(III) complex based OLED fabricated by thermal evaporation method displaying efficient bright red emission

Rashid Ilmi, Danyang Zhang, José D.L. Dutra, Necmi Dege, Liang Zhou, Wai Yeung Wong, Paul R. Raithby, Muhammad S. Khan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

2 Citations (Scopus)


A new tris β-diketonate europium(III) complex [Eu(btfa)3Py-Im] (Eu-1) (4,4,4-trifluoro-1-phenyl-1,3-butanedione (btfa) and 2-(2-pyridyl)benzimidazole (Py-Im)] has been synthesized and structurally characterized. A single crystal X-ray diffraction analysis shows that Eu-1 is octacoordinated and the coordination sphere is composed of a EuO6N2 core with a trigonal dodecahedral (D2d) geometry. The photophysical properties of Eu-1 were analysed in detail and with the help of the experimental PL data and theoretical modelling, energy transfer rates were calculated, and an energy transfer mechanism is proposed for Eu-1. The complex has been used as the emitting layer (EML) to fabricate organic light emitting diodes (OLEDs). Eight OLEDs, of which four single-EML and four double-EML with varying doping concentration, were fabricated via a thermal evaporation method using Eu-1 as the EML. Under the optimum conditions a highly monochromatic bright red emission (CIEx,y = 0.640, 0.311) with brightness (B) = 896 cd/m2, current efficiency (ηc) = 2.26 cd/A, power efficiency (ηp) = 1.92 lm/W and external quantum efficiency (EQE) = 1.6% at very low Vturn-on = 3.4 V was obtained.

Original languageEnglish
Article number106216
JournalOrganic Electronics
Publication statusPublished - Sep 2021


  • 2-(2-pyridyl)benzimidazole
  • Electroluminescence
  • Energy transfer mechanism
  • Europium(III)
  • Photoluminescence

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Chemistry(all)
  • Biomaterials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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