Browsing by Author "Hwang, Shiao-Wen"

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Efficient electron injection in organic light-emitting diodes using dipotassium phthalate as n-type dopant
(2008)
Ho, Meng-Huan
;
Hsieh, Ming-Ta
;
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.
Electrical characterization of organic light-emitting diodes using dipotassium phthalate as n-type dopant
(2008-08-25)
Ho, Meng-Huan
;
Hsieh, Ming-Ta
;
Chen, Teng-Ming
;
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.
High-color-temperature p-i-n white organic light-emitting devices based on the fluorescent RGB system
(2007)
Chen, Chao-Jung
;
Hwang, Shiao-Wen
;
Chen, Chin H.
;
光電工程學系
;
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.
Highly efficient p-i-n white organic light emitting devices with tandem structure
(2007-12-03)
Ho, Meng-Huan
;
Chen, Teng-Ming
;
Yeh, Pu-Cheng
;
Hwang, Shiao-Wen
;
Chen, Chin H.
Highly efficient tandem p-i-n white organic light emitting devices have been fabricated. Utilizing an optical transparent bilayer with doped organic p-n junction that consists of 4,7-diphenyl-1,10-phenanthroline: 2% cesium carbonate (Cs(2)CO(3))/N,N(')-bis(1-naphthyl)-N,N(')-diphenyl-1,1(')-biphenyl-4,4(')-diamine: 50% v/v tungsten oxide (WO(3)) as the connecting layer, the tandem p-i-n white device achieved an electroluminescence efficiency of 23.9 cd/A and a power efficiency of 7.8 lm/W at 20 mA/cm(2) with a Commission Internationale de l'Eclairage coordinates of (0.30, 0.43). The electroluminescent color of this tandem p-i-n white organic light-emitting diode device will not change significantly with respect to drive current variation and forward viewing angle. (c) 2007 American Institute of Physics.
Highly efficient yellowish-white phosphorescent organic light-emitting devices
(2006-09-01)
Hsu, Shih-Feng
;
Laskar, Inamur R.
;
Chen, Teng-Ming
;
Ma, Jie-Wei
;
Hwang, Shiao-Wen
We have developed highly efficient yellowish-white organic light-emitting devices (WOLEDs) with very broad emission based on a orange emitter, (2-2 '-(4-flurophenyl)benzothiozolato-N,C-2 ') platinum (acetylacetonate) [Pt(F-bt)acac]. A yellowish-white light device with one of the highest electroluminescent (EL) efficiencies of 19.68cd/A (10.94%) with Commission Internationale d'Eclairage (CIE) coordinates of (x,y) = (0.399,0.453) has been demonstrated.
Highly power efficient organic light-emitting diodes with a p-doping layer
(2006-12-18)
Chang, Chan-Ching
;
Hsieh, Ming-Ta
;
Chen, Jenn-Fang
;
Hwang, Shiao-Wen
;
Chen, Chin H.
In this letter, the authors demonstrate p-i-n organic light-emitting diodes (OLEDs) incorporating a p-doped transport layer which comprises tungsten oxide (WO3) and 4,4('),4(')-tris(N-(2-naphthyl)-N-phenyl-amino)triphenylamine (2-TNATA) to replace the volatile tetrafluro-tetracyanoquinodimethane. The authors propose the 2-TNATA:WO3 composition functions as a p-doping layer which significantly improves hole injection and conductivity of the device that leads to the fabrication of tris(8-quinolinolato)aluminum based p-i-n OLEDs with long lifetime, low driving voltage (3.1 V), and high power efficiency (3.5 lm/W) at 100 cd/m(2). (c) 2006 American Institute of Physics.
Highly-efficient tandem White Organic light emitting devices
(2007)
Yeh, Pu-Cheng
;
Hwang, Shiao-Wen
;
Ma, Jia-Wei
;
Ho, Meng-Huan
;
Hsu, Shih Feng
We demonstrate efficient tandem p-i-n White Organic Light Emitting Diodes (WOLEDs) with the transparent NPB:WO3 interconnecting layer. The CIEx,y coordinate, luminance yield and E.Q.E of the tandem OLEDs (at 20 mA/cm(2)) are (0.30, 0.43), 23.9 cd/A and 8.5%, respectively. The CIEx,y coordinates of the tandem OLEDs neither change (Delta x,y < 0.02) with driving current nor with forward viewing angle (+/- 60 degree). This performance of tandem WOLEDs represents considerable improvement over what have been known in the literature.
Thin film encapsulation of thin-cathode organic electroluminescent devices
(2006)
Lee, Shih-Nan
;
Hwang, Shiao-Wen
;
Chen, Chin H.
;
應用化學系
;
Department of Applied Chemistry
We have developed a novel thin film encapsulation method for thin-cathode OLED by introducing organic (not polymer)/inorganic multiple thin films to protect device, which is shown to slow down the permeation rate of moisture and oxygen. From the stability test of devices, the projected lifetime of thin-cathode OLED device with thin film encapsulation was similarly to that with glass lid encapsulation.
Thin-film encapsulation of thin-cathode organic light-emitting devices
(2007-11-01)
Lee, Shih-Nan
;
Hwang, Shiao-Wen
;
Chen, Chin H.
;
應用化學系
;
友訊交大聯合研發中心
We have developed a novel thin-film encapsulation method for thin-cathode organic light-emitting devices (OLEDs) by introducing organic (not polymer)/inorganic multiple thin films to protect devices, which is shown to slow down the permeation rate of moisture and oxygen. From the stability test of devices, the projected lifetime of thin-cathode OLEDs with thin-film encapsulation was similar to that of thin-cathode OLEDs with glass lid encapsulation.
Three-wavelength white electrophosphorescence with two emissive materials
(2005)
Hsu, Shih-Feng
;
Laskar, Inamur R.
;
Chen, Teng-Ming
;
Hwang, Shiao-Wen
;
Chen, Chin H.
A New phosphorescent material based on Pt complex, Pt(btOMe)acac was synthesized and its specific EL emission spectrum from green to red combined with blue phosphorescent material. Firpic, can easily achieve high-efficiency three-wavelength white light with two emitters.
Using tunneling junction to enhance hole-injection in organic light-emitting diodes
(2005)
Chang, Chan-Ching
;
Hwang, Shiao-Wen
;
Hsieh, Ming-Ta
;
Ma, Jia-Wei
;
Chen, Chin H.
We demonstrate enhanced hole-injection and lower driving voltage in vacuum-deposited organic light-emitting diodes (OLEDs) with a novel tunneling junction composed of the Mg:Alq(3)/WO3 layer. The device, ITO/Mg:Alq(3)/WO3/NPB/Alq(3)/LiFAl achieved one of the lowest driving voltages of 5.8 V at 20mA/cm(2) for conventional small molecule OLEDs. We propose the laminated Mg:Alq(3)/WO3/NPB functions as a Fowler Nordheim tunneling junction, which can improve hole-injection. It was found to also prolong device lifetime under dc driving, that is comparable to the best reported for the Alq(3) emitter.
White light top-emitting light-emitting devices
(2005)
Hsu, Shih-Feng
;
Hwang, Shiao-Wen
;
Chen, Chin H.
;
應用化學系
;
Department of Applied Chemistry
Laminated cathode with high transparency and low reflectivity was modified form Ca/Ag and applied in White light top-emitting light-emitting devices (WTOLEDs). With modified cathode, a broad emission from white emitter is obtained which means strong optical interference is alleviated in the top-emitting devices.
White p-i-n organic light-emitting devices with high power efficiency and stable color
(2007-09-10)
Ho, Meng-Huan
;
Hsu, Shih-Feng
;
Ma, Jia-Wei
;
Hwang, Shiao-Wen
;
Yeh, Pu-Cheng
Highly efficient p-i-n two-component white organic light-emitting devices have been fabricated with a thin dual emission layer system comprised of one codeposited emitting layer with blue and yellow dyes and one blue emitting layer, which gives rise to a balance white emission. The p-i-n white device achieved an electroluminescence efficiency of 10 cd/A and a power efficiency of 9.3 lm/W at 1000 cd/m(2) and a low voltage of 3.4 V with a Commission Internationale de l'Eclairage coordinates of (0.32, 0.43). The electroluminescent color of this p-i-n white organic light-emitting diode device has been shown to be immune to drive current density variations.