Monochromatic red electroluminescence from a homodinuclear europium(iii) complex of a β-diketone tethered by 2,2′-bipyrimidine

Rashid Ilmi, Weidong Sun, José D.L. Dutra, Nawal K. Al-Rasbi, Liang Zhou, Peng Cheng Qian, Wai Yeung Wong, Paul R. Raithby, Muhammad S. Khan

Research output: Contribution to journalArticlepeer-review

32 Citations (SciVal)

Abstract

A new homodinuclear complex [Eu(btfa)3]2bpm (1) was synthesized incorporating 4,4,4-trifluoro-1-phenyl-1,3-butanedione (btfa) as the primary and 2,2′-bipyrimidine (bpm) as the auxiliary ligand. The complex was characterized by analytical and spectroscopic techniques, with special emphasis on the crystal structure and photoluminescence (PL) properties, both experimentally and theoretically. Single crystal X-ray diffraction (SCXRD) analysis reveals that the two Eu(iii) ions in 1 are eight coordinate, where the bpm behaves as a N4 donor linking the two Eu(iii) ions symmetrically. Each Eu(iii) ion displays a distorted square antiprismatic (DSAP, D4d) coordination geometry. Complex 1 displayed bright red emission with (CIE)x,y color coordinates = 0.670; 0.330 and an absolute photoluminescence quantum yield (PLQY) of 54.4%. The theoretical intensity parameters (Ω2 and Ω4), radiative (AR) and non-radiative (ANR) decay rates, intrinsic quantum yield (QEuEu), sensitization efficiency (ηsen) and PLQY were assessed using the LUMPAC software and showed very good agreement with the experimental values. Based on these, an energy transfer (ET) mechanism is proposed and discussed. Moreover, 1 was used as an emitter to fabricate single- A nd double-emitting layer (EML) red-emitting electroluminescent devices. Double-EML device at the optimum doping concentration of 4.0 wt% displayed impressive EL performances, brightness (B) = 812 cd m-2, maximum current efficiency (ηc) = 3.97 cd A-1, maximum power efficiency (ηp) = 3.89 lm W-1, and external quantum efficiency (EQE) = 2.8% at very low Vturn-on = 3.2 V with (CIE)x,y = 0.662, 0.321 which is close to the standard red color recommended by NTSC (0.67, 0.33).

Original languageEnglish
Pages (from-to)9816-9827
Number of pages12
JournalJournal of Materials Chemistry C
Volume8
Issue number29
DOIs
Publication statusPublished - 7 Aug 2020

Funding

MSK acknowledges His Majesty’s Trust Fund for Strategic Research (Grant No. SR/SQU/SCI/CHEM/16/02) for funding. RI thanks HM’s Trust Fund for a postdoctoral fellowship. WYW thanks the Hong Kong Research Grants Council (PolyU 153058/ 19P), Hong Kong Polytechnic University (1-ZE1C) and the Endowed Professorship in Energy from Ms Clarea Au (847S) for the financial support. LZ is grateful to the financial aid from National Natural Science Foundation of China (21771172), Youth Innovation Promotion Association of Chinese Academy of Sciences (2013150). PCQ thanks the Foundation of Wenzhou Science & Technology Bureau (No. W20170003) and the National Natrual Science Foundation of China (No. 21828102). PRR is grateful to the Engineering and Physical Sciences Research Council (EPSRC) for continued funding (Grant EP/K004956/1).

ASJC Scopus subject areas

  • General Chemistry
  • Materials Chemistry

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