Browsing by Author "Chen, Chin H."

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A morphologically stable host material for efficient phosphorescent green and red organic light emitting devices
(2008-11-28)
Ho, Meng-Huan
;
Balaganesan, Banumathy
;
Chu, Ta-Ya
;
Chen, Teng-Ming
;
Chen, Chin H.
A carbazole-based host material, 4,4'-N,N'-[di(3, 6-di(t-butyl)carbazole]biphenyl (ttbCBP), with four t-butyl steric spacers on peripheral carbazole moieties was effectively synthesized through Friedel-Crafts Alkylation. Owing to the presence of sterically hindered t-butyl groups, ttbCBP exhibits a high glass transition temperature (175 degrees C) and is morphologically stable. This host material also preserves the characteristics of wide band-gap of 3.2 eV and high triplet energy of 2.64 eV. In addition, ttbCBP has been shown to be effective hosts for green and red phosphorescent emitters in organic electrophosphorescent devices. (C) 2008 Elsevier B.V. All rights reserved.
Ab initio molecular orbital calculation of 1,3,5-triazine derivatives as hosts for phosphorescent organic light emitting devices
(2005)
Chu, Ta-Ya
;
Ho, Meng-Huan
;
Chen, Jenn-Fang
;
Chen, Chin H.
;
電子物理學系
Novel triplet host materials 2,4,6-tris (diarylamino)-1,3,5-triazine derivatives (TRZ1-TRZ4) have been reported and from which TRZ2 as a host for Ir(ppy)(3) was particularly useful in producing high efficiency phosphorescent organic light emitting diodes (OLEDs). This paper reports the molecular orbital and energy level of these derivatives determined by ab initio calculation. The calculated triplet bandgap energy of TRZ1 has been found to be larger than that of TRZ2.
An organic p-type dopant with high thermal stability for an organic semiconductor
(2008)
Gao, Zhi Qiang
;
Mi, Bao Xiu
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Xu, Gui Zhen
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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.
Comparative study of single and multiemissive layers in inverted white organic light-emitting devices
(2006-09-11)
Chu, Ta-Ya
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Chen, Jenn-Fang
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Chen, Szu-Yi
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Chen, Chin H.
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電子物理學系
The authors have fabricated and compared highly efficient inverted white organic light-emitting devices (WOLEDs) with a single emission layer (SEL) and with a multiemission layer (MEL). The efficiency levels of the WOLEDs with a SEL and a MEL achieved 13.0 cd/A, 10.6 lm/W and 11.3 cd/A, 7.3 lm/W, respectively. The projected half lifetime of a SEL device under an initial luminance of 400 cd/m(2) is expected to be over 34 000 h, which is five times better than that of a MEL device of 6350 h. The Commission International de l'Eclairage coordinates of a SEL device are not affected by aging. (c) 2006 American Institute of Physics.
Efficient and Color-saturated Inverted Bottom-emitting Organic Light-emitting Devices with a Semi-transparent Metal-assisted Electron Injection Layer
(2009)
Wu, Chang-Yen
;
Ho, Meng-Huan
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Gao, Sin-Min
;
Su, Shang-Yu
;
Lin, Kuan-Hung
We report the development of highly efficient and color-saturated green fluorescent C545T dye-doped inverted bottom-emitting organic light emitting diode (IBOLED) by the insertion of a semi-transparent metal-assisted electron injection layer (SM-EIL) based on silver between the ITO and the n-doped electron injection layer (EIL). This n-i-p device with its synergistic microcavity effect achieved maximum efficiencies of 24 cd/A and 12.9 lm/ W and an external quantum efficiency of 6.2% with a saturated CIE(x,y) (0.24,0.71) which are twice better than those of the conventional OLED and over 60% improvement on IBOLED without the SM-EIL.
Efficient and color-saturated inverted bottom-emitting organic light-emitting devices with a semi-transparent metal-assisted electron injection layer
(2011-01-01)
Ho, Meng-Huan
;
Wu, Chang-Yen
;
Chen, Teng-Ming
;
Chen, Chin H.
;
應用化學系
We report the development of highly efficient and color-saturated green fluorescent 10-(2-benzothiazolyl)-1 1 7 7-tetramethyl-2 36 7-tetrahydro-l H 5H 11H-benzo[l]pyrano-[6 7 ij]quinolizin-11-one dye-doped inverted bottom-emitting organic light-emitting diode (IBOLED) This was enabled by the insertion of a silver (Ag) based semi-transparent metal-assisted electron injection layer between the ITO cathode and n-doped electron transporting layer This IBOLED with ITO/Ag bilayer cathode with its synergistic microcavity effect achieved luminous efficiencies of 207 cd/A and 124 1m/W and a saturated ClE(x,y) of (0 22 0 72) at 20 mA/cm(2) which are twice better than those of the conventional OLED and have over 60% improvement on IBOLED without ITO/Ag Mayer cathode (c) 2010 Elsevier B V All rights reserved
Efficient deep blue emitters for organic electroluminescent devices
(2007-08-20)
Ho, Meng-Huan
;
Wu, Yao-Shan
;
Wen, Shih-Wen
;
Chen, Teng-Ming
;
Chen, Chin H.
Highly efficient deep blue organic light emitting devices have been fabricated with a 4-(styryl)biphenyl-core based fluorescent dopant (SK-1) in the wide band gap 2-methyl-9,10-di(1-naphthyl)anthracene (alpha,alpha-MADN) host system which achieved an electroluminescence efficiency of 5.0 cd/A and an external quantum efficiency of 4.2% at 20 mA/cm(2) with a saturated blue Commission Internationale de l'Eclairage coordinates of (0.15, 0.14) and a half-decay lifetime of 8000 h at an initial brightness of 100 cd/m(2). The current efficiency and electroluminescent color of SK-1 doped devices have been shown to be essentially immune to drive current density. (C) 2007 American Institute of Physics.
Efficient deep-blue organic light-emitting diodes: Arylamine-substituted oligofluorenes
(2007-11-05)
Gao, Zhi Qiang
;
Li, Zhong Hui
;
Xia, Ping Fan
;
Wong, Man Shing
;
Cheah, Kok Wai
Novel deep-blue-light-emitting diphenylamino and triphenylamino end-capped oligofluorenes were synthesized by double palladium-catalyzed Suzuki cross- coupling of dibromo-oligofluorene with the corresponding boronic acid as a key step. These oligofluorenes exhibit deep-blue emission (lambda(em)(max) = 429-432 nm), low and reversible electrochemical oxidation (highest occupied molecular orbital = 5.15-5.20 eV), high fluorescence quantum yield (Phi(FL) = 0.61-0.93), and good thermal properties (glass-transition temperature, T-g = 99-195 degrees C and decomposition temperature, T-dec > 450 degrees C). Remarkably, saturated deep-blue organic light-emitting diodes, made from these oligofluorenes as dopant emitters, have been achieved with excellent performance and maximum efficiencies up to 2.9 cd A(-1) at 2 mA cm(-2) (external quantum efficiency of 4.1 %) and with Commission Internationale de l'Eclairage (x,y) coordinates of (0.152,0.08), which is very close to the National Television System Committee standard blue.
Efficient electron injection in organic light-emitting diodes using dipotassium phthalate as n-type dopant
(2008)
Ho, Meng-Huan
;
Hsieh, Ming-Ta
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Chen, Jenn-Fang
;
Hwang, Shiao-Wen
;
Chen, Chin H.
An efficient n-doped electron transport layer composed of 4,7-diphenyl- 1, 10-phenanthroline (BPhen) and dipotassium phthalate (PAK2) has been developed. By temperature-dependent admittance spectroscopy, the incorporation of PAK2 into BPhen is found to increase electron concentration in BPhen laYer, resulting in raising the Fermi-level to similar to 0.5 eV below its LUMO which further enhances the efficiency of electron injection from Al cathode. When this n-doped layer is adopted in OLED device, the green Alq(3) device can achieve a current efficiency of 3.6 cd/A and a power efficiency of 2.1 lm/W at 20 mA/cm(2) and lower drive voltage of 5.3 V.
Efficient p-i-n Top-emitting Flexible Organic Light Emitting Diodes on Planarized Stainless Steel Foil
(2009)
Su, Shang-Yu
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Ho, Meng-Huan
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Kao, Pei-Yi
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Wu, Chang-Yen
;
Peng, Yi-Hao
A high-efficiency p-i-n top-emitting flexible organic light emitting diode (TFOLED) employing highly reflective Ag as anode and semitransparent Ca/Ag as cathode was fabricated on SS substrate which was insulated and planarized with a specially formulated photoresist coating. By incorporating p-dopant (WO(3)) and a new n-dopant (PAK2) in hole and electron transparent layers, respectively, along with an optimized microcavity structure, a green fluorescent C545T doped Alq(3) TOLED on SS substrate achieved one of the highest efficiencies of 26.7 cd/A and 19.8 lm/W at 20 mA/cm(2) reported for flexible OLEDs.
Electrical characterization of bathophenanthroline doped with dipotassium phthalate
(2007)
Hsieh, Ming-Ta
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Chang, Chan-Ching
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Chen, Jenn-Fang
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Ho, Meng-Huan
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Chen, Teng-Ming
Bathophenanthroline (BPhen) doped with dipotassium phthalate (PAK2) was electrically characterized using current-voltage (I-V) and temperature-dependent admittance spectroscopy measurements which demonstrates that the incorporation of PAK2 into BPhen can increase the electron concentration of the BPhen layer resulting in the transformation of the Fermi-level from deep to shallow (around 0.5 eV below LUMO band) and Accordingly, PAK2 is an alternative n-type organic dopant for n-type doping device.
Electrical characterization of organic light-emitting diodes using dipotassium phthalate as n-type dopant
(2008-08-25)
Ho, Meng-Huan
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Hsieh, Ming-Ta
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Chen, Teng-Ming
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Chen, Jenn-Fang
;
Hwang, Shiao-Wen
An efficient n-doped electron transport layer composed of 4,7-diphenyl-1,10-phenanthroline (BPhen) and dipotassium phthalate (PAK2) has been developed. By temperature-dependent admittance spectroscopy, the incorporation of PAK2 into BPhen is found to raise the Fermi level from 1.7 eV to only around 0.5 eV below BPhen's lowest unoccupied molecular orbital, which further enhances the efficiency of electron injection from an A1 cathode. When this n-doped layer is adopted in an organic light-emitting diode device, the green fluorescent 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 device can achieve a current efficiency of 16 cd/A and a power efficiency of 10.9 lm/W at 1000 cd/m(2). (C) 2008 American Institute of Physics.
Flexible inverted bottom-emitting organic light-emitting devices with a semi-transparent metal-assisted electron-injection layer
(2010-01-01)
Wu, Chang-Yen
;
Ho, Meng-Huan
;
Su, Shang-Yu
;
Chen, Chin H.
;
應用化學系
The development of highly efficient and color-saturated green-fluorescent C545T dye-doped flexible inverted bottom-emitting organic light-emitting diode (IBOLED) is reported. This was enabled by the insertion of a silver (Ag) based semi-transparent metal-assisted electron-injection layer between the ITO cathode and n-doped electron-transporting layer on a flexible polyethersulphone substrate. This flexible IBOLED with an ITO/Ag bilayer cathode with its synergistic microcavity effect achieved luminous efficiencies of 20.4 cd/A and 12 lm/W and a saturated CIE(x,y) of (0.28, 0.68) at 20 mA/cm(2), which are 1.5 times higher than those of a conventional OLED.
High contrast ratio emi-flective LCD with nano-particle transflector
(2007)
Yang, Bo-Ru
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Lin, Kun-Yueh
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Shieh, Han-Ping D.
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Lee, Shih-Nan
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Chen, Chin H.
A novel emi-flective display that integrates a reflective liquid crystal display (R-LCD) and an organic light emitting diode (OLED) display was demonstrated. Under the light ambience (if 30 nits, the OLED achieved a gain factor of 8 in contrast ratio (CR) compared with the conventional non-integrated OLED: besides, the OLED was fully operational and the system's CR of 5000:1 at the viewing cone of 50 degrees could be achieved. Moreover, the R-LCD retained a CR of 10:1 at the viewing cone of 55 degrees in the bright ambience. To enhance the image quality of both R-LCD and OLED, we laid a nano-particle film (NPF) in the intermediate section of the hybrid device. The NPF was demonstrated to enhance the light extraction in transmission mode of the integrated device to 103% and the haze function of the reflection mode to a factor of 15 compared with the freestanding mirror.
High-color-temperature p-i-n white organic light-emitting devices based on the fluorescent RGB system
(2007)
Chen, Chao-Jung
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Hwang, Shiao-Wen
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Chen, Chin H.
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光電工程學系
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Department of Photonics
P-i-n devices with 5% Cs doped Men as the n-type transporting layer and WO3 doped NPB as the p-type transporting layer are investigated for controlling the recombination zone (RZ) of carriers in WOLED based on three adjacent fluorescent red, green and blue emitters. Variation in while CIEx,y color-coordinates are closely related to the proportion of deep blue emission which serves as an indicator for the position of the RZ. By optimizing the concentration of the deep blue dopant, it is possible to enhance the color temperature of WOLED and boost the efficiency to 8 cd/A at 5.5 V (20 mA/cm2) with CIEx,y of (0.33, 0.34) which is among the best reported for the fluorescent RGB 3-emission WOLEDs.
High-Efficiency Inverted Transparent Blue Organic Light-Emitting Devices
(2006)
Chen, Szu-Yi
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Chu, Ta-Ya
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Chen, Chao-Jung
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Chen, Jenn-Fang
;
Chen, Chin H.
We report efficient inverted transparent blue OLEDs (ITOED) with an hole injection layer prepared by co-evaporation of WO3 with NPB, which achieved a total current efficiency 0 10.7 cd/A at 20 mA/cm(2) with light emits from both ITO bottom cathode and Au top anode in about 3:1 ratio.
Highly efficient and stable inverted bottom-emission organic light emitting devices
(2006-07-31)
Chu, Ta-Ya
;
Chen, Jenn-Fang
;
Chen, Szu-Yi
;
Chen, Chao-Jung
;
Chen, Chin H.
The authors report the development of highly efficient and stable C545T doped green fluorescent Alq(3) inverted bottom-emission organic light emitting device (OLED), with a device configuration of ITO/Mg/Cs(2)O:Bphen/Alq(3)/C545T:Alq(3)/NPB/WO(3)/Al, that achieved a maximum current efficiency of 23.7 cd/A and a power efficiency of 12.4 lm/W which are two times better than those of the conventional OLED. At a brightness level of 100 cd/m(2), the device required driving current density only as low as 0.5 mA/cm(2) at a driving voltage of only 5.0 V and its half-lifetime T(1/2) in excess of 104 000 h. (c) 2006 American Institute of Physics.
Highly efficient and stable sky blue organic light-emitting devices
(2006-09-18)
Lin, Mei-Fang
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Wang, Lei
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Wong, Wai-Kwok
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Cheah, Kwok-Wai
;
Tam, Hoi-Lam
A highly efficient and stable sky blue organic light-emitting device doped with a sky blue dopant BUBD-1 has been fabricated, achieving an electroluminescence efficiency of 13.2 cd/A and 6.1 lm/W at 20 mA/cm(2) and 6.7 V, with Commission Internationale del'Eclairage coordinates of (0.16, 0.30) and a half-decay lifetime of 1815 h at an initial brightness of 2640 cd/m(2). This performance is one of the best blue devices ever reported without using hole blocking layer or any p or n dopant in hole or electron transport layer. (c) 2006 American Institute of Physics.
Highly efficient and stable white light organic light-emitting devices
(2007-08-13)
Lin, Mei-Fang
;
Wang, Lei
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Wong, Wai-Kwok
;
Cheah, Kok-Wai
;
Tam, Hoi-Lam
A highly efficient two-element white light organic light-emitting device with a sky blue dopant BUBD-1 and a yellow dopant TBRb was fabricated. The device achieved an electroluminescence efficiency of 17.1 cd/A and 7.9 lm/W at 20 mA/cm(2). From 112 to 32 010 nits, the CIEx,y coordinates variation was Delta(x,y)<+/-(0.01,0.01), which is superior to common white light organic light-emitting devices (OLEDs) that tend to change color with drive conditions. Moreover, the device reached a half-decay t(1/2) lifetime over 40 000 h at an initial luminance of 300 cd/m(2). This result is among the best records of fluorescent white light OLEDs. (C) 2007 American Institute of Physics.
Highly efficient blue organic electroluminescent devices
(2005)
Chang, Chia-Ming
;
Lee, Meng-Ting
;
Chen, Chin H.
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應用化學系
;
Department of Applied Chemistry
We have synthesized a highly efficient blue dopant based on the amino-substituted distyrylarylene (DSA-amine) fluorescent dye. Doped in the stable diphenyanthracene type of blue host material 2-(methyl)-9,10-di(2-naphthyl)anthrace (MADN), it achieved a luminance yield of 9.1 cd/A at 20 mA/cm(2) with a CIEx,y color coordinate of [0.16, 0.28] and a maximum external quantum efficiency of 4.7%.