A Tris β-Diketonate Europium(III) Complex Based OLED Fabricated by Thermal Evaporation Method Displaying Efficient Bright Red Emission

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

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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 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 EQE = 1.6% at very low Vturn-on = 3.4 V was obtained
Original languageEnglish
Article number106216
JournalOrganic Electronics
Early online date25 May 2021
Publication statusE-pub ahead of print - 25 May 2021


  • Europium(III)
  • photoluminescence
  • electroluminescence
  • 2-(2-pyridyl)benzimidazole
  • energy transfer mechanism

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

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