Browsing by Author "Shen, WJ"

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Doped blue emitters of 9,10-di(2-naphthyl)anthracene in organic electroluminescent devices
(2003-04-04)
Liu, TH
;
Shen, WJ
;
Yen, CK
;
Iou, CY
;
Chen, HH
Blue EL emission of 9,10-di(2-naphthyl)anthracene (ADN) based emitter in OLED is highly dependent upon its thickness and attenuated by the microcavity effect of the emitter. By carefully tuning the thickness of ADN and optimizing the doping concentration of TBP, one of the highest efficiencies reported for the anthracene based blue emitter at 6.6 cd/A with a CIE of x = 0.13; y = 0.21 is achieved.
Efficient white organic light emitting devices with dual emitting layers
(2005-09-22)
Wu, YS
;
Hwang, SW
;
Chen, HH
;
Lee, MT
;
Shen, WJ
In this paper, a new white organic light-emitting device (OLED) with the structure of indium tin oxide/CFx/1,4-bis[N-(1-naphthyl)-N'-phenylamino]-biphenyl (NPB) (30 mn)NPB: 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene (20 nm; 1.6 %)/2-methyl-9,10-di(2-naphthyl) anthracene: p-bis(p-NN-di-phenyl-aminostyryl)benzene (40 nm, 3%)/aluminum tris(8-hydroxyquinoline) (20 nm)/LiF (1 nm)/Al (200 mn) has been investigated. The device showed white emission with a high-luminous yield of 9.75 cd/A at 20 mA/cm(2), but its Commission Internationale de l'Eclairage chromaticity coordinates appeared to change from (0.34, 0.42) at 6 mA/cm(2) to (0.27, 0.37) at 200 mA/cm(2) due to the shift of recombination zone. The change of color with drive current was suppressed by introduction of an electron-blocking layer of NPB along with a hole-blocking layer of aluminum (III) bis(2-methyl-8-quinolinato)4-phenylphenolato to the white OLED which successfully confined the recombination site and achieved a luminous yield of 9.9 cd/A at 20 mA/cm(2). (c) 2005 Elsevier B.V All rights reserved.
Spirobifluorene-linked bisanthracene: An efficient blue emitter with pronounced thermal stability
(2004-03-09)
Shen, WJ
;
Dodda, R
;
Wu, CC
;
Wu, FI
;
Liu, TH
Spiro-FPA, a novel blue emitter, in which two identical anthracene luminophores are linked orthogonally around a spirobifluorene core, has been synthesized and characterized. The introduction of a spiro linkage into the structure of spiro-FPA leads to a reduction in crystallization tendency and an increase in glass transition temperature relative to the monomeric units. In addition, the tetrahedral nature of the carbon atom at the spiro center preserves the optical and electrochemical characteristics of the pristine anthracene units. As demonstrated by AFM measurements, high-quality amorphous films of spiro-FPA with good morphological stability can be prepared by vapor deposition. Organic EL devices constructed using a 1.0-wt % TBP-doped spiro-FPA emitting layer produce bright blue emissions with a high luminescence efficiency of 4.9 cd/A (2.07 lm/W).
Synthesis and characterization of spiro(adamantane-2,9 '-fluorene)-based triaryldiamines: thermally stable hole-transporting materials
(2004-06-03)
Chen, CH
;
Shen, WJ
;
Jakka, K
;
Shu, CF
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應用化學系
New triaryldiamines. Adm-TPD and Adm-NPD, which contain a spiro(adamantane-2,9-fluorene) core, have been synthesized and characterized. We believe that because of the presence of the rigid spiro-fluorene core, these triaryldiamines exhibit higher glass transition temperatures and have a less tendency to crystallize relative to their biphenyl analogs. Additionally, electrochemical studies showed that the planarity of the fluorene core leads to lower ionization potentials and greater degrees of pi conjugation between the two amino groups. AFM measurements demonstrated that high-quality amorphous films of Adm-NPD with good morphological stability were prepared by vapor deposition. Electroluminescent devices using Adm-NPD as a hole-transporting layer-i.e., having the configuration ITO/Adm-NPD/Alq(3)/LiF/Al-emit a bright green light that is characteristic of Alq(3). (C) 2003 Elsevier B.V. All rights reserved.
Synthesis of t-butylated diphenylanthracene derivatives as blue host materials for OLED applications
(2003-07-21)
Balaganesan, B
;
Shen, WJ
;
Chen, CH
;
應用化學系
;
資訊工程學系
This paper describes the cost-effective synthesis and the photoluminescence of diphenylanthracene derivatives, which are found to be potential blue host materials for organic light emitting diode (OLED) technology. (C) 2003 Elsevier Ltd. All rights reserved.