Design and Synthesis of Iridium Bis(carbene) Complexes for Efficient Blue Electrophosphorescence

被引:125
作者
Hsieh, Cheng-Han [1 ]
Wu, Fang-Iy [1 ]
Fan, Chun-Hsiang [1 ]
Huang, Min-Jie [1 ]
Lu, Kun-Yi [1 ]
Chou, Pei-Yu [1 ]
Yang, Yu-Han Ou [1 ]
Wu, Shih-Hsiang [1 ]
Chen, I-Chia [1 ]
Chou, Shu-Hua [2 ]
Wong, Ken-Tsung [2 ]
Cheng, Chien-Hong [1 ]
机构
[1] Natl Tsing Hua Univ, Dept Chem, Hsinchu 30013, Taiwan
[2] Natl Taiwan Univ, Dept Chem, Taipei 10617, Taiwan
关键词
carbenes; iridium; phosphorescence; photochromism; organic light-emitting diodes; thin films; LIGHT-EMITTING DEVICES; ORGANIC ELECTROPHOSPHORESCENCE; IR(III) COMPLEXES; ENERGY-TRANSFER; EMISSION; PHOSPHORESCENCE; DIODES;
D O I
10.1002/chem.201100317
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Five iridium bis(carbene) complexes, [Ir(pmi)(2)(pypz)] (1), [Ir(mpmi)(2)(pypz)] (2), [Ir(fpmi)(2)(pypz)] (3), [Ir(fpmi)(2)(pyim)] (4), and [Ir(fpmi)(2)(tfpypz)] (5) (pmi=1-phenyl-3-methylimdazolin-2-ylidene-C, C-2'; fpmi=1-(4-fluorophenyl)-3-methylimdazolin-2-ylidene-C,C-2'; mpmi=1-(4-methyl-phenyl)-3-methylimdazolin-2-ylidene-C, C2'; pypz=2-(1H-pyrazol-5-yl)pyridinato; pyim=2-(1H-imidazol-2-yl) pyridinato; and tfpypz=2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridinato), were synthesized and their structures were characterized by NMR spectroscopy, mass spectroscopy and X-ray diffraction. These complexes showed phosphorescent emission with the emission maxima between 453 and 490 nm. Various spectrophotometric measurements, cyclic voltammetric studies, and density functional theory (DFT) calculations show that, unlike most of the phosphorescent cyclometalated iridium complexes, the lowest unoccupied molecular orbital (LUMO) energy and the emissive state of these iridium complexes are mainly controlled by the N,N'-heteroaromatic (N boolean AND N) ligand. Despite the fact that the LUMO levels of these complexes are mainly on the N boolean AND N ligands, the efficiencies of the electroluminescent (EL) devices are very high. For example, the EL devices using [Ir(mpmi)(2)(pypz)], [Ir(fpmi)(2)( pypz)], and [Ir(fpmi)(2)(tfpypz)] as the dopant emitters exhibited light- to deep-blue electrophosphorescence with external quantum efficiencies of 15.2, 14.1, and 7.6% and Commission Internationale d'Enclairage (x, y) coordinates (CIEx,y) of (0.14, 0.27), (0.14, 0.18) and (0.14, 0.10), respectively.
引用
收藏
页码:9180 / 9187
页数:8
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