Browsing by Author "Mi, Bao Xiu"

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An organic p-type dopant with high thermal stability for an organic semiconductor
(2008)
Gao, Zhi Qiang
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Mi, Bao Xiu
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Xu, Gui Zhen
;
Wan, Yi Qian
;
Gong, Meng Lian
To overcome the thermal instability of a p-doped organic hole transporting layer using the state-of-the-art p-type dopant, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, a potent electron accepter, 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane, has been found to possess superior thermal stability and proved to be an excellent p-type dopant.
High efficiency and small roll-off electrophosphorescence from a new iridium complex with well-matched energy levels
(2008-02-18)
Gao, Zhi Qiang
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Mi, Bao Xiu
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Tam, Hoi Lam
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Cheah, Kok Wai
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Chen, Chin Hsin
Phenylpyridazine ligands coordinating to the iridium(III) atom yield a thermally stable (5 % weight loss at 439 degrees C) homoleptic iridium complex with a high phosphorescent quantum yield (0.32 at room temperature). This material has well-matched energy levels with the host, and highly efficient electrophosphorescence (52 cd A(-1); see figure) with a small roll-off (23 % at 70 mA cm(-2)) in device efficiency is achieved.
New Host Containing Bipolar Carrier Transport Moiety for High-Efficiency Electrophosphorescence at Low Voltages
(2009-02-09)
Gao, Zhi Qiang
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Luo, Meiming
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Sun, Xiao Hua
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Tam, Hoi Lam
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Wong, Man Shing
A new host material for use in phosphorescent OLEDs with desirable electronic properties has been synthesized. The material exhibits superior carrier-transport properties, a narrow optical band gap, relatively high triplet energy, and high thermal stability. It is synthesized by integrating hole-transporting carbazole groups into an electron-transporting phenanthroline core (see figure), and is demonstrated to be an excellent host for phosphorescent dopant emitters.
Organic light-emitting diodes using 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane as p-type dopant
(2009-02-16)
Mi, Bao Xiu
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Gao, Zhi Qiang
;
Cheah, Kok Wai
;
Chen, Chin H.
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友訊交大聯合研發中心
We demonstrate that 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane (F2-HCNQ) can serve as an excellent electrical doping material for hole transport materials with the highest occupied molecular orbital level as high as 5.4 eV, such as N,N(')-di(naphthalene-1-yl)-N,N(')-diphenyl-benzidine (NPB). With its relatively strong electron-accepting ability and high thermal stability, F2-HCNQ doped NPB organic light-emitting diode (OLED) showed improved power efficiency with low driving voltage. The tris(8-hydroxyquinoline)aluminum based OLED with F2-HCNQ doped NPB layer and Cs(2)O doped bathophenanthroline electron transport layer exhibits power efficiency of 3.6 lm/W with driving voltage of 3.2 V at 100 cd/m(2).
p-Doped p-phenylenediamine-substituted fluorenes for organic electroluminescent devices
(2009-07-01)
Gao, Zhi Qiang
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Xia, Ping Fan
;
Lo, Pik Kwan
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Mi, Bao Xiu
;
Tam, Hoi Lam
Two novel p-phenylenediamine-substituted fluorenes have been designed and synthesized. Their applications as hole injection materials in organic electroluminescent devices were investigated. These materials show a high glass transition temperature and a good hole-transporting ability. It has been demonstrated that the 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) doped p-phenylene-diamine-substituted fluorenes, in which F4-TCNQ acts as p-type dopant, are highly conducting with a good hole-transporting property. The organic light emitting devices (OLEDs) utilizing these F4-TCNQ-doped materials as a hole injection layer were fabricated and investigated. The pure Alq(3)-based OLED device shows a current efficiency of 5.2 cd/A at the current density of 20 mA/cm(2) and the operation lifetime is 1500 h with driving voltage increasing only about 0.7 mV/h. The device performance and stability of this hole injection material meet the benchmarks for the commercial requirements for OLED materials. (C) 2009 Elsevier B.V. All rights reserved.