Browsing by Author "Liao, CH"

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Efficient green coumarin dopants for organic light-emitting devices
(2004-04-15)
Lee, MT
;
Yen, CK
;
Yang, WP
;
Chen, HH
;
Liao, CH
[GRAPHICS] We have synthesized a new green fluorescent dopant C-545P having incorporated five strategically placed "methyl" steric spacers on the julolidyl ring system. C-545P has good thermal properties and photostability, and when fabricated as a dopant in an Alq(3)-hosted OLED device, it shows notable improvement in luminance efficiency and is more resistant to concentration quenching than C-545T, particularly in the doping concentration range between 1 and 2% v/v, while achieving comparable device stability.
Highly efficient blue organic light-emitting devices incorporating a composite hole transport layer
(2005-05-16)
Liao, CH
;
Lee, MT
;
Tsai, CH
;
Chen, CH
;
應用化學系
Organic light-emitting devices (OLEDs) incorporating the copper phthalocyanine (CuPc)/N,N-'-bis-(1-naphthyl)-N,N-'-diphenyl-1,1(')-biphenyl-4,4(')-diamine composite hole transport layer have been fabricated. Under optimal condition, the highly efficient sky-blue OLED based on the aminosubstituted distyrylarylene fluorescent dye, doped in the stable diphenyanthracene blue host achieved a luminance efficiency of 16.2 cd/A with a Commission Internationale d' Eclairage (CIE)(x,y) color coordinate of [0.15, 0.29] at 6.4 V (20 mA/cm(2)) and an external quantum efficiency of 8.7%. (c) 2005 American Institute of Physics.
Highly efficient blue organic light-emitting devices incorporating a composite hole transport layer
(2005-05-16)
Liao, CH
;
Lee, MT
;
Tsai, CH
;
Chen, CH
;
應用化學系
Organic light-emitting devices (OLEDs) incorporating the copper phthalocyanine (CuPc)/N,N-'-bis-(1-naphthyl)-N,N-'-diphenyl-1,1(')-biphenyl-4,4(')-diamine composite hole transport layer have been fabricated. Under optimal condition, the highly efficient sky-blue OLED based on the aminosubstituted distyrylarylene fluorescent dye, doped in the stable diphenyanthracene blue host achieved a luminance efficiency of 16.2 cd/A with a Commission Internationale d' Eclairage (CIE)(x,y) color coordinate of [0.15, 0.29] at 6.4 V (20 mA/cm(2)) and an external quantum efficiency of 8.7%. (c) 2005 American Institute of Physics.
Highly efficient deep-blue organic light-emitting devices
(2006-01-01)
Lee, MT
;
Liao, CH
;
Tsai, CH
;
Chen, CH
;
應用化學系
A highly efficient deep-blue organic light-emitting device (OLED) incorporating a novel composite hole-transport layer (c-HTL) and an emitter based on the new non-symmetrical mono(styryl) amine fluorescent dopant in the stable host MADN, which achieved a luminance efficiency of 5.4 cd/A with a Commission Internationale d'Eclairage (CIEx,y) of (0.14, 0.13) and an external quantum efficiency of 5.1% at 20 mA/cm(2) and 6.8 V, is reported. The increased device efficiency is attributed to an improved balance between hole and electron currents in the recombination zone.
Highly efficient yellow and white organic electroluminescent devices doped with 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene
(2004-11-08)
Liu, TH
;
Wu, YS
;
Lee, MT
;
Chen, HH
;
Liao, CH
We describe the applications of a sterically-hindered yellow dopant, 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene (TBRb) which, when compared to 5,6,11,12-tetraphenylnaphthacene (Rb) in either tris(8-hydroxyquinolinato)aluminum or 1,4-bis[N-(1-naphthyl)-N-'-phenylamino]-4,4(') diamine (NPB) as host emitter, shows a 50%-34% increase in luminance efficiency over that of Rb device without significantly affecting its color. In addition, we have incorporated the TBRb doped yellow NPB emitter into the two-element white organic light-emitting diodes based on p-bis(p-N,N-di-phenyl-aminostyryl)benzene doped 2-methyl-9,10-di(2-naphthyl) anthracene sky-blue emitter which improved the luminance efficiency by 44% over that of Rb to 12.8 cd/A and 4.3 lm/W at 20 mA/cm(2) with CIEx,y=[0.31,0.38]. (C) 2004 American Institute of Physics.
Highly efficient, deep-blue doped organic light-emitting devices
(2005-10-17)
Lee, MT
;
Liao, CH
;
Tsai, CH
;
Chen, CH
;
應用化學系
All the attributes necessary for good OLED performance (see Figure), namely, high electroluminescence efficiency (5.4 cd A(-1)), long operational lifetime (10 000 h at an initial luminance of 100 cd m(-2)), and deep-blue color (color saturation: (0.14, 0.13)) are demonstrated by an OLED incorporating a novel, composite hole-transport layer and an emitter based on a new mono(styryl)amine dopant in the stable, anthracene-based blue host material, 2-methyl-9,10-di(2-naphthyl)anthracene.
Highly stable organic light-emitting devices with a uniformly mixed hole transport layer
(2005-12-12)
Tsai, CH
;
Liao, CH
;
Lee, MT
;
Chen, CH
;
應用化學系
Highly stable organic light-emitting devices were made by using a uniformly mixed hole transport layer (UM-HTL) composed of a mixture of 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) and N,N-bis(1-naphthyl)-N,N-'-diphenyl,1,1(')-biphenyl-4,4(')-diamine (NPB) in a 3:7 (MADN:NPB) ratio. The lifetime of 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo[l]-pyrano[6,7,8-ij]quinolizin-11-one doped green device with UM-HTL can be greatly improved to 2.7 times longer than that of the conventional device (NPB based HTL) without impacting on its driving voltage and emissive color significantly. This improvement in stability can be attributed to the fact that the unstable [Alq(3)(+)] species formed by electro-oxidation have been effectively suppressed.
Improved stability of organic electroluminescent devices by doping styrylamines in hole or electron transporting layer
(2005-03-07)
Lee, MT
;
Liao, CH
;
Tsai, CH
;
Chen, CH
;
應用化學系
The stability of green organic electroluminescent devices has been improved by doping styrylamine derivate, p-bis(p-N,N-diphenyl-aminostyryl)benzene (DSA-Ph) in hole or electron transporting layer. Compared with the undoped device, the stability of the electron transporting layer has increased by a factor of 1.8 without affecting the electroluminescence efficiency of 11 cd/A and color (CIEx,y=0.34, 0.62). The enhanced stability is believed to derive from the hole trapping nature of DSA-Ph which can reduce the residual hole carriers in tris(8-hydroquinolinato)aluminum (Alq(3)) and suppress the formation of fluorescent quencher of Alq(3) cationic species. (c) 2005 American Institute of Physics.
Optimum design for a thermally stable multifinger power transistor
(2002-05-01)
Liao, CH
;
Lee, CP
;
Wang, NL
;
Lin, B
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電子工程學系及電子研究所
The thermal stability of multifinger bipolar transistors has been analyzed theoretically. Coupled equations are solved to study the onset of instability and its dependence on the distributions of ballasting resistors. Analytical expressions were derived for the emitter ballasting distribution for optimum stable operation. Compared to conventional methods with uniform ballasting, the optimized design can significantly increase the stable operating current of the transistor. An absolutely stable operating condition is also derived. At this condition, the device never becomes unstable.
Optimum design for a thermally stable multifinger power transistor with temperature-dependent thermal conductivity
(2002-05-01)
Liao, CH
;
Lee, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The thermal stability of multifinger bipolar transistors has been analyzed theoretically. Coupled equations are solved to study the onset of instability and its dependence on the distributions of ballasting resistors. We extended our previous work on the multiple-finger transistor thermal stability from the simple coupled thermal-electrical feedback equation to the more accurate I-V equation and taking the temperature dependence of the thermal conductivity into consideration. Transistors with three-fingers and N-fingers have been analyzed. Two design procedures, uniform current design and uniform temperature design, of the best ballasting resistor distribution for optimum thermal stability operation were developed. Using these design flows, we can design the best ballasting resistor needed for thermal stable operation under the specified current level or specified junction temperature.
Phosphorescence of red Os(fptz)(2)(PPh2Me)(2) doped organic light-emitting devices with n and p hosts
(2006-02-06)
Liu, TH
;
Hsu, SF
;
Ho, MH
;
Liao, CH
;
Wu, YS
We have applied a stericly-hindered red phosphorescent dopant Os(fptz)(2)(PPh2Me)(2) [fptz=3-trifluoromethyl-5-(2-pyridyl)-1,2,4-triazole, PPh2Me=phosphine ligand] in p-type 4,4(')-N,N-'-dicarbazole-biphenyl or n-type bis(2-methyl-8-quinolinolato)(p-phenylphenolato) aluminum host and found that the latter produced higher luminance efficiency at lower doping concentration. We present a model to rationalize this phenomenon in which the n-type host impedes hole transport, which leads to narrower recombination zone near the hole transport layer/emission layer interface than the p-type host, hence, more effective recombination.
Solution-processible small molecular organic light-emitting diode material and devices based on the substituted aluminum quinolate
(2004-07-27)
Cheng, JA
;
Chen, CH
;
Liao, CH
;
友訊交大聯合研發中心
;
D Link NCTU Joint Res Ctr
We have discovered a new type of small molecular host material based on aluminum(III) 8-hydroxyquinolates, Al(Saq)(3), which was synthesized with three 5-(N-ethylanilinesulfonamide)-8-quinolinoline as bidentate ligands. By X-ray diffraction crystallographic analysis, the crystals of meridional Al(Saq)(3) are monoclinic, space group P2(1)/c, a = 17.952(3) Angstrom, b = 17.7160 Angstrom, c = 17.080(3) Angstrom, beta = 99.895(4)degrees. Its peak photoluminescence in solid phase appears at 488 nm. Its LUMO/HOMO (-3.13/-6.04 eV) and optical band gap (E-g 2.91 eV) were determined by cyclic voltammetry. In solid thin film morphological investigation, it shows good thermal properties and high quantum efficiency. When doped with 0.7 wt % of the high fluorescent green dopant 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo-[l]pyrano[6,7,8-ij]quinolizin-11-one (C-545T), energy transfer from Al-(Saq)(3) to dopant will occur and high green light emission can be achieved. For fabrication of OLEDs using spin-coating techniques, its electroluminescence is at 1931 CIEx,y (0.21, 0.41).
Stable styrylamine-doped blue organic electroluminescent device based on 2-methyl-9,10-di(2-naphthyl)anthracene
(2004-10-11)
Lee, MT
;
Chen, HH
;
Liao, CH
;
Tsai, CH
;
Chen, CH
We have developed a highly efficient and stable blue organic electroluminescent (EL) device based on. a blue fluorescent styrylamine dopant, p-bis(p-N,N-diphenyl-aminostyryl)benzene, in a morphologically stable high band-gap host material, 2-methyl-9, 10-di(2-naphthyl)anthracene, which achieved an EL efficiency of 9.7 cd/A and 5.5 lm/W at 20 mA/cm(2) and 5.7 V,with Commission Internationale d'Eclairage coordinates of (x=0.16, y=0.32). The blue-doped device achieved a half-decay lifetime (t(1/2)) of 46000 h at an initial brightness of 100 cd/m(2). (C) 2004 American Institute of Physics.