Greenish yellow organic light emitting devices based on novel iridium complexes containing 2-cyclohexenyl-1-phenyl-1H-benzo[d]imidazole

Liangliang Han, Dongyu Zhang, Yuanhang Zhou, Ying Yang, Han Young Woo, Fali Bai, Renqiang Yang

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

2-Cyclohexenyl-1-phenyl-1H-benzo[d]imidazole (Hcyclopbi) and its heterocyclometalated iridium complexes bis[2-cyclohexenyl-1-phenyl-1H-benzo[d] imidazole](acetylacetonate)iridium(III) [(cyclopbi)2Iracac] and bis[2-cyclohexenyl-1-phenyl-1H-benzo[d]imidazole][2-(3-(trifluoromethyl) -1H-pyrazol-5-yl)pyridinate]iridium(III) [(cyclopbi)2IrCF 3] were firstly designed and synthesized. Owing to the strong electron withdrawing ability of 2-(3-(trifluoromethyl)-1H-pyrazol) compared to that of acetylacetonate, blue shifted phosphorescence 542 nm was obtained for (cyclopbi)2IrCF3 compared to that of (cyclopbi) 2Iracac 545 nm with photoluminescence quantum yields (φ) 0.22 and 0.25, respectively, as well the highest occupied molecular orbit (HOMO) energy level was estimated to be -5.10 eV for (cyclopbi)2IrCF3, 0.19 eV lower than that of -4.91 eV for (cyclopbi)2Iracac. When (cyclopbi)2Iracac was doped into 4,4′-bis(9H-carbazol-9-yl) biphenyl (CBP) as the emitting layer, high efficiency organic light emitting devices (OLEDs) were obtained with maximum current efficiency (ηc) 22.3 cd/A at 3.1 mA/cm2 and maximum brightness 16,300 cd/m2 at 171.6 mA/cm2, which were comparable to those of bis(2-phenylpyridine)(acetylacetonate)iridium(III) [(ppy) 2Iracac] with the same device structure. This results indicate that (cyclopbi)2Iracac and (cyclopbi)2IrCF3 are potential phosphorescent dyes used for OLEDs.

Original languageEnglish
Pages (from-to)1010-1015
Number of pages6
JournalDyes and Pigments
Volume99
Issue number3
DOIs
Publication statusPublished - 2013

Keywords

  • 2-Cyclohexenyl-1-phenyl-1H-benzo[d]imidazole
  • Electroluminescence
  • Greenish yellow phosphorescence
  • Heterocyclometalated iridium complexes
  • Organic light emitting devices
  • Photoluminescence

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Process Chemistry and Technology

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