Browsing by Author "Chen, Chin Hsin"

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High efficiency and small roll-off electrophosphorescence from a new iridium complex with well-matched energy levels
(2008-02-18)
Gao, Zhi Qiang
;
Mi, Bao Xiu
;
Tam, Hoi Lam
;
Cheah, Kok Wai
;
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.
Molecular hosts for triplet emitters in organic light-emitting diodes and the corresponding working principle
(2010-08-01)
Mi BaoXiu
;
Gao ZhiQiang
;
Liao ZhangJin
;
Huang Wei
;
Chen, Chin Hsin
This paper summarizes the mechanism and routes for excitation of triplet emitters in dopant emission based phosphorescent organic light-emitting diodes (PhOLEDs), providing a comprehensive overview of recent progress in molecular hosts for triplet emitters in PhOLEDs. Particularly, based on the nature of different hosts, e.g., hole transporting, electron transporting or bipolar materials, in which the dopant emitters can be hosted to generate phosphorescence, the respective device performances are summarized and compared. Highlights are given to the relationships among the molecular structure, thermal stability, triplet energy, carrier mobility, molecular orbital energy level and their corresponding device performances.
New Host Containing Bipolar Carrier Transport Moiety for High-Efficiency Electrophosphorescence at Low Voltages
(2009-02-09)
Gao, Zhi Qiang
;
Luo, Meiming
;
Sun, Xiao Hua
;
Tam, Hoi Lam
;
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.
Strong Luminescent Iridium Complexes with (CN)-N-boolean AND=N Structure in Ligands and Their Potential in Efficient and Thermally Stable Phosphorescent OLEDs
(2009-01-19)
Mi, Boo Xiu
;
Wang, Peng Fei
;
Gao, Zhi Qiang
;
Lee, Chun Sing
;
Lee, Shuit Tong
Homoleptic iridium complexes with (CN)-N-boolean AND=N type ligands, i.e., 1,4-bis (phenyl) phthalazine (BPPa) and 3,6-bis(phenyl)pyridazine (BPPya), are strong phosphorescents, easy to synthesize, and thermally stable, thus having great potential in optical electronic applications, as demonstrated in lr(BPPa)(3)-based OLED devices. A quantum chemistry study shows that (CN)-N-boolean AND=N type ligands can bond to Ir more strongly.
Strong Luminescent Iridium Complexes with C(boolean AND)N=N Structure in Ligands and Their Potential in Efficient and Thermally Stable Phosphorescent OLEDs
(2009-01-19)
Mi, Boo Xiu
;
Wang, Peng Fei
;
Gao, Zhi Qiang
;
Lee, Chun Sing
;
Lee, Shuit Tong
Homoleptic iridium complexes with C(boolean AND)N=N type ligands, i.e., 1,4-bis (phenyl) phthalazine (BPPa) and 3,6-bis(phenyl)pyridazine (BPPya), are strong phosphorescents, easy to synthesize, and thermally stable, thus having great potential in optical electronic applications, as demonstrated in lr(BPPa)(3)-based OLED devices. A quantum chemistry study shows that C(boolean AND)N=N type ligands can bond to Ir more strongly.