Highly Efficient Organic Blue Electrophosphorescent Devices Based on 3,6‐Bis(triphenylsilyl)carbazole as the Host Material

Tsai, Ming-Han; Lin, Huey-Wen; Su, Hai‐Ching; Ke, Tung Huei; Wu, Chung‐Chih; Fang, Fu-Chuan; Liao, Yuan‐Li; Wong, Ken‐Tsung; Wu, Chih‐I

doi:10.1002/adma.200502283

Cited by 471 publications

(152 citation statements)

References 19 publications

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“…[2b, [9][10][11][12][13][14] Device A was turned on at about 4.2 V and then reached the peak h ext of 9.1 % at 5.0 V and the maximum luminance (L max ) of 5668 cd m À2 at 11.5 V. To further improve the EL efficiency, a mixture of CzSi and UGH2 in a ratio of 2:1 was used in the emissive layer in device B. The presence of the carbazole group in CzSi was expected to improve the progress of holes in the emissive layer, because of its relative high-lying HOMO level (Figure 5 a).…”

Section: 21a C H T U N G T R E N N U N G (285) [Ira C H T U N G T Rmentioning

confidence: 99%

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

Hsieh

Fan

et al. 2011

Chemistry A European J

133

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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,C(2'); 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^N) ligand. Despite the fact that the LUMO levels of these complexes are mainly on the N^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'Énclairage (x,y) coordinates (CIE(x,y)) of (0.14, 0.27), (0.14, 0.18) and (0.14, 0.10), respectively.

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Section: 21a C H T U N G T R E N N U N G (285) [Ira C H T U N G T Rmentioning

confidence: 99%

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

Hsieh

Fan

et al. 2011

Chemistry A European J

133

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“…(1-phenyl-1-H-benzimidazole) (TPBi, devices A2 and B2) and 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ, devices A3 and B3), [24] were applied for examining the electron transport/ hole blocking, charge/carrier balance and for optimizing the device performances. Finally, LiF was used as the electron-injection layer.…”

Section: -Benzenetriyl)-a C H T U N G T R E N N U N G Trisa C H T U Nmentioning

confidence: 99%

Homoleptic Tris(Pyridyl Pyrazolate) Ir^III Complexes: En Route to Highly Efficient Phosphorescent OLEDs

Chen

Yang

Chi

et al. 2010

Chemistry A European J

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Treatment of the metal reagent IrCl(3)nH(2)O with two equivalents of 2-pyridyl pyrazole (N;N)H (3-tert-butyl-5-(2-pyridyl) pyrazole, (bppz)H and 3-trifluoromethyl-5-(2-pyridyl) pyrazole, (fppz)H), afforded the isomeric Ir(III) metal complexes with a general formula cis-[Ir(bppz)(2)Cl(2)]H (2 a), trans-[Ir(bppz)(2)Cl(2)]H (3 a), cis-[Ir(fppz)(2)Cl(2)]H (2 b), and trans-[Ir(fppz)(2)Cl(2)]H (3 b). Single-crystal X-ray diffraction studies on 2 b and 3 a revealed the coexistence of two pyrazolate chelates and two terminal chloride ligands on the coordination sphere. Subsequent reactivity studies confirmed their intermediacy to the preparation of homoleptic mer-[Ir(bppz)(3)] (1 a) and mer-[Ir(fppz)(3)] (1 b) that showed dual intraligand and ligand-to-ligand charge-transfer phosphorescence at room temperature. To attain bright, room-temperature phosphorescence further, we then synthesized two isoquinolinyl pyrazolate complexes, mer-[Ir(bipz)(3)] (4 a) and mer-[Ir(fipz)(3)] (4 b) ((bipz)H=3-tert-butyl-5-(1-isoquinolyl) pyrazole and (fipz)H=3-trifluoromethyl-5-(1-isoquinolyl) pyrazole). Their orange luminescence is mainly attributed to the mixed MLCT/pipi* transition, and the quantum yields were as high as 86 (4 a) and 50 % (4 b) in degassed CH(2)Cl(2) solution at RT. The organic light-emitting diodes (OLEDs) were then fabricated by using 4 a as a dopant, giving orange luminescence with CIE(x,y)=0.55, 0.45 (CIE(x,y)=the 1931 Commission Internationale de L'Eclairage (x,y) coordinates) and peak efficiencies of 14.6 % photon/electron, 34.8 cd A(-1), 26.1 lm W(-1). The device data were then compared with the previously reported heteroleptic complex [Ir(dfpz)(2)(bipz)] (5) ((dfpz)H=1-(2,4-difluorophenyl) pyrazole), revealing the possible effect of the bipz chelate and phosphor design on the overall electrophosphorescent performance, which can be understood by the differences in the carrier-transport properties.

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“…[5] Incorporation of meso, twisted, or insulating linkages, such as carbazole derivatives N,N-dicarbazoly-3,5-benzene (mCP) [5] and 4,4'-bis(9-carbazolyl)-2,2'-dimethyl-biphenyl (CDBP) [6] and tetraA C H T U N G T R E N N U N G (aryl)silane derivatives, is commonly used for the construction of efficient hosts with high T 1 levels and relatively large conjugated areas. [7][8][9] However, the efficient hosts with both high T 1 levels and the good carrier-injection/transporting ability are still insufficient. Recently, some phosphine oxide (PO) hosts for blue-electrophosphorescence derivatives have been reported.…”

mentioning

confidence: 99%

A Simple Phosphine–Oxide Host with a Multi‐insulating Structure: High Triplet Energy Level for Efficient Blue Electrophosphorescence

Han

Zhao

et al. 2011

Chemistry A European J

163

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Highly Efficient Organic Blue Electrophosphorescent Devices Based on 3,6‐Bis(triphenylsilyl)carbazole as the Host Material

Cited by 471 publications

References 19 publications

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

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

Homoleptic Tris(Pyridyl Pyrazolate) Ir^III Complexes: En Route to Highly Efficient Phosphorescent OLEDs

A Simple Phosphine–Oxide Host with a Multi‐insulating Structure: High Triplet Energy Level for Efficient Blue Electrophosphorescence

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Highly Efficient Organic Blue Electrophosphorescent Devices Based on 3,6‐Bis(triphenylsilyl)carbazole as the Host Material

Cited by 471 publications

References 19 publications

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

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

Homoleptic Tris(Pyridyl Pyrazolate) IrIII Complexes: En Route to Highly Efficient Phosphorescent OLEDs

A Simple Phosphine–Oxide Host with a Multi‐insulating Structure: High Triplet Energy Level for Efficient Blue Electrophosphorescence

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Product

Resources

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Homoleptic Tris(Pyridyl Pyrazolate) Ir^III Complexes: En Route to Highly Efficient Phosphorescent OLEDs