• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.997-999
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• 1999

We fabricated white light-emitting organic electroluminescent device which have a mixed single emitting layer containing poly(N-vinylcarbazole)[PVK], tris(8-hydroxyquinoline)aluminum[Alq3] and poly(3-hexylthiophene)[P3HT] and investigated the emission properties of it. We expect to obtain a blue light from PVK, green light from Alq3 and red light from P3HT The fabricated device emits white light over 18V with slight orange light. We think that the energy transfer in a mixed layer occurred from PVK to $Alq_3$ and P3HT resulted in decreasing the blue light intensity from PVK. With mixing of N, N'-diphenyl-N, N'-(3-methylphenyl)-[1,1'-biphenyl]-4, 4'-diamine[TPD], hole transport material, to the emitting layer, the luminance intensity of device was increased 50 times than that of the device which not contain TPD. We find that the efficiency of the white light electroluminescent device can be improved by injecting electron more effectively and blue light need to improve the color purity of white light.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.613-616
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• 2001

The effect of codopants on the electroluminescent properties for SrS-Ce based thin films was studied. The active layer was deposited by electron beam with sulfur The wavelength of eletroluminecence shifted with codopants and their concentrations. The intensity ratio of blue to green were found In the CeP-doped device, but the highest total intensity of luminance showed about 850cd/$m^2$ in the CeCl$_3$+KCL-doped device, which indicates that codopants are playing an important role of luminance. At any device, the luminance was the strongest at 0.2 mol% concentration among the concentration studied, suggesting the existence of optimum concentration. By post-annealing Luminance of most devices was improved, but the shift of wavelength was not observed.

• Proceedings of the Materials Research Society of Korea Conference
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• 2000.05a
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• pp.53-76
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• 2000

Multi-color organic electroluminescent (EL) displays have already been commercialized, and the simple extensions of present technologies on organic EL can not be a target for basic research anymore. Future prospect of research on organic electroluminescent devices are described from the view point of possible future break-through. Three aspects, perspective for further increase of device efficiencies, possibility of simplified device structures and possible use of thick organic layers, are discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.27-32
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• 2006

The present status and prospects for further development of thin-film electroluminescent (TFEL) devices using oxide phosphors are described. High-luminance oxide TFEL devices have been recently developed using a new combinatorial deposition technique featuring rf magnetron sputtering with a subdivided powder target. In addition, new flexible oxide TFEL devices have been fabricated on an oxide ceramic sheet and operated stably in air above $200^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.428-430
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• 2000

In this paper, the Flexible information display was implemented using AC powder electroluminescent device. ZnS:Cu and $BaTiO_3$ was used as a phosphor and dielectric respectively. The preparation of phosphor and dielectric layer was performed with screen printing. The implemented system of the Flexible information display was divided as following; EL display, driving circuit, software for driving. The properties of fabricated devices was measured with EL spectrum and brightness.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.88-91
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• 2008

Electroluminescent(EL) devices based on organic thin films are considered to be one of the next generation of flat-panel displays. In this paper, we have investigated electro-luminescent(EL) characteristics of organic EL device using $Alq_3$, PBD as emitting material. Current and luminance can be seen that express a similar relativity in voltage and could know that luminance is expressing current relativity.

• Journal of Information Display
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• v.4 no.2
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• pp.7-12
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• 2003

We discuss main techniques to improve legibility of electroluminescent displays. Emphasis is placed on use of destructive optical interference to cancel ambient light reflected from the back electrode of the device. Basic optical principles and material composition of the optical interference contrast-enhancing stack (CES) are presented. We also describe the improved human factors of electroluminescent devices assisted with a CES. Achromatic contrast is the most important contributor to display's legibility. In some conditions color contrast may also be important. Contributing to both luminance and color contrast enhancement, the contrast-enhancing stack may play an important role in various display applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.332-335
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• 2000

We fabricated organic electroluminescent (EL) devices with single layer of poly(3-dodeoylthiophene) (P3DoDT) hlended with different amounts of poly(N-vinylcarbazole) (PVK) as a emitting layer. The molar ratio between P3DoDT and PVK changed with 1:0, 2:1 and 1:1. To improve the external quantum efficiency of EL devices, we applied insulating layer, LiF layer, between polymer emitting layer and Al electrode. All of the devices emit orange-red light and it's can be explained that the energy transfer occurs from PVK to P3DoDT. In the voltage-current and voltage-brightness characteristics of devices applied LiF layer, current and brightness increased with increasing applied voltage. The brightness of the device have a molar ratio 1:1 with LiF layer was about 10 times larger than that of the device without PVK at 6V. Electrical impedance properties of ITO/emitting layer/LiF/Al devices were investigated. In the Cole-Cole plots of impedance data, one semicircle was observed. Therefore, the equivalent circuit for the devices can be designed as a single parallel resistor and capacitor network with series resistor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.7
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• pp.539-544
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• 2010

We have synthesized new blue electroluminescent polyalkylfluorene-based copolymers [poly(F-co-Py)x:y, where x:y = 99:1 or 95:5 mole ratios] containing the hole-injecting pyrazole derivative [3,3'-(4,6-bis(octyloxy)-1,3-phenylene)bis(1,5-diphenyl-4,5-dihydro-1H-pyrazole] through Ni(0) mediated polymerization, and their electroluminescent properties were investigated. Electroluminescent (EL) devices were fabricated with ITO / PEDOT:PSS (110 nm) / copolymers or PF homopolymer (80 nm) / Ca (50 nm) / Al (200 nm) configuration. Each EL device constructed from the copolymer exhibited significantly enhanced brightness and efficiency compared with a device constructed from the PF homopolymer. The EL device constructed with poly(F-co-Py)99:1 exhibited the highest luminous efficiency and brightness (0.95 cd/A and $2,907\;cd/m^2$, respectively). The achieved luminous efficiency was an excellent result, providing almost a 4-fold improvement on the efficiency obtainable with the a PF homopolymer device. This enhanced efficiency of the copolymer devices results from their improved hole injection and more efficient charge carrier balance, which arises from the HOMO level (~5.83 eV) of the poly(F-co-Py)99:1 copolymer, which is higher than that of the PF homopolyme (~5.90 eV).

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1998.11a
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• pp.9-11
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• 1998

A phenomenon of electroluminescent radiate as electric field applied in the phosphor, in this paper, we produced the Powder Electroluminescent Device(PELD) which was changing the structure and the thickness of phosphor and insulator for realization of the PELD with high brightness. We made PELD with structure that is WK-1(ITO film/Phosphor/Insulator/Electrode), WK-2(ITO film/Phosphor/Insulator/Electro de), WK-3(ITO film/Phosphor/Insulator/Electrode), WK-4(ITO film/Phosphor+Insulator/ Electrode). The property of the produced PELD are analyzed by measuring the spectrum which electrical and optical property, the brightness and the transferred charge density. In this result, the structure of WK-4 have good luminescence property than others, it's effective thickness is 60${\mu}{\textrm}{m}$. At 100V 400Hz, High brightness of 2700cd/m2 was performed.