Iridium Complexes with Cyclometalated 2‐Cycloalkenyl‐Pyridine Ligands as Highly Efficient Emitters for Organic Light‐Emitting Diodes

Abstract

Iridium complexes containing cyclometalated 2‐cyclohexenylpyridine derivatives with rigid and bulky cyclohexene units are synthesized, and found to be highly efficient materials in EL devices (see figure). Devices based on these iridium complexes emit yellowish‐ green light with the very high external quantum efficiency of 18.7%.

Highly Improved Efficiency of Deep-Blue Fluorescent Polymer Light-Emitting Device Based on a Novel Hole Interface Modifier with 1,3,5-Triazine Core

“…5 It is well known that highly efficient blue-light fluorescent PLED is one of the major challenges to further accelerate commercialization of full color display and lighting source applications. [6][7][8][9] According to National Television Standards Committee (NTSC), standard blue light is required to be at Commission Internationale de L'Eclairage (CIE) coordinates of (0.14, 0.08). 10 The preferred CIE coordinates are in the deep-blue area, implying that only a very wide energy band gap would lead to deep-blue emitting.…”

The Efficient Green Emitting Iridium(III) Complexes and Phosphorescent Organic Light Emitting Diode Characteristics

“…These iridium complexes, Ir(chpy) 3 or Ir(mchpy) 3 , with cycloalkenylpyridines have higher HOMO and lower LUMO energy levels than iridium(III) complex, Ir(ppy) 3 . We synthesized 2-cycloalkenylpyridine substituted iridium complexes, Ir(chpy) 3 or Ir(mchpy) 3 , in 44-74% yields and reported (Kang et al 2008). …”

“…In the way to improve and tune the emission colors, we synthesized and reported the iridium(III) complexes using 2-cycloalkenylpyridine derivatives as cyclometalated ligands for OLEDs (Kang et al 2008). Cyclic alkene is expected to give better stability than alkene in the complexes (Takiguchi et al 2002).…”

Molecular hosts for triplet emitters in organic light-emitting diodes and the corresponding working principle

“…Dicarbazole-containing CBP (7) is the most widely used host material for triplet emitters, which can efficiently host green to red phosphorescent emitters with triplet energies smaller than that of CBP (7) (Figure 6) (E T = 2.6 eV [17]) [46,[60][61][62]. Using CBP as the host, and employing a high electron transport material as ETL, Ir(ppy) 3 based device achieved efficiency of 133 lm/W (29%) [25], which is the highest efficiency for Ir(ppy) 3 to date.…”