• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1255-1257
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• 1998

In this study,$ 5{\times}5$ dot-matrix display was implemented with powder electroluminescent device (PELD). Generally PELD which have a luminance from powder phosphor with electric field, inserted phosphor and dielectric layer between electrodes is basic structure. To make high brightness PELD compared to conventional device, new type of PELD was proposed as follows. New PELD had only one layer, which was mixed phosphor (ZnS:Cu) and dielectric (BaTiO3) material appropriately between electrodes. To compare and estimate the conventional and new type of PELD, the EL spectrum, transferred charge density, brightness and decay time was measured. As above result, we fabricated a hish brightness $ 5{\times}5$ dot-matrix display with new type of PELD. Its brightness was 6400 $cd/m^2$ at 200 V, 400Hz.

• Electrical & Electronic Materials
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• v.7 no.2
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• pp.117-122
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• 1994

The role of ZnS buffer layer not only suppresses chemical reactions between emission material and insulating material but also alters the luminescence and the crystallinity of the emission layer, if ZnS buffer layer was sandwiched between emission layer and insulating layer of electroluminescent device. In this research, we fabricated ZnS thin film with rf magnetron sputter system by varying rf power 100, 200W, substrate temperature 100, 150, 200, 250.deg. C and post-annealing temperature 200, 300, 400, 500.deg. C and analysed X-ray diffraction pattern, transmission spectra and cross section by SEM photograph for seeking the optimal crystallization condition of ZnS buffer layer. As a result, increasing the rf power, the crystallinity of ZnS thin film was improved. It was found that the ZnS thin film had better properties than anything else when fabricated with the following conditions ; rf power 200W, substrate temperature 150.deg. C, and post-annealing temperature 400.deg. C. ZnS thin film had the transmittance more than 80% in visible range. So it is suitable to use as a buffer layer of electroluminescent devices.

• Journal of Information Display
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• v.4 no.2
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• pp.19-24
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• 2003

In order to improve the device performances of organic electroluminescent devices (OELDs), the efficiency of carrier injections into the organic layers from electrodes and the balance of injected carrier densities in the emission region are critical factors. Especially, energy barriers, which exist at the interfaces between electrodes and organic layers, interrupt carrier injections, which lead to unbalanced carrier densities. In this study, ${\alpha}-septithiophene$ (${\alpha}$-7T), as a buffer layer, and composite cathode composed of Al and CsF were formed to improve hole and electron injections, respectively. The orientations of ${\alpha}$-7T molecules were adjusted using the simple rubbing method and the mass ratio of CsF was varied from 1 to 10 wt%. Upon investigation of we believe that the 3 wt% mass ratio of CsF and the horizontal orientation of ${\alpha}$-7T molecules are the optimized conditions for achieving better the performance of OELDs. Device with the horizontally oriented 20 nm thick ${\alpha}$-7T layer and composite cathode shows a turn-on voltage of 7V and luminance of 172 cd/$m^2$ at 4 mA/$cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.90-93
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• 2002

In the surface pressure-area isotherms of mixed monolayers, mixtures containing as much as 30 mol% of AA form stable condensed monolayer while the monolayer without AA is in the expanded state because PVK take on 3D collapsed. All of the mixed monolayers with 0, 10, 20 and 30 mol% of AA could be readily transferred onto ITO substrate at 16, 17, 24 and 26 mN/m, respectively. The monolayer containing 30 mol% of AA, however, showed a roughness value of 28A and became homogeneous decreasing with the phase separation. We fabricated organic EL device of ITO/CuPc/MEL/BBOT/iLiF/Al using mixed monolayer of 13, 19 and 25 layer deposited by LB method as a emitting layer. In the voltage-current characteristics of EL device, current density was much smaller than that of the spin-coated devices. It may due to the large contact resistance existed at the interface of LB layer/organic layer inhibit carrier injection to the emitting layer. EL spectra of device showed peaks at 450. 470, 505, 555 and 650 nm and the white light emission indicate the CIE coordinate x=0.306, y=0.353.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.331-334
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• 2000

The organic electroluminescent(EL) device has gathered much interest because of its large potential in materials and simple device fabrication. We fabricated EL devices which have a blended single emitting layer containg poly(Nvinylcarbazole)[PVK] and poly(3-dodecylthiophene)[P3DoDT]. 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 AI electrode. All of the devices emit orange-red light and it's can be explained that the energy transfer occurs from PVK to P3DoDT. Within the molar ratio 1:0, 2:1 and 1:1, the energy transfer was not saturated, which results in the not appearance of PVK emission in the blue region. In the voltage-current and voltage-light power characteristics of devices applied LiF layer, current and light power drastically increased with increasing with applied voltage. In the consequence of the result, the light power 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.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1075-1080
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• 2003

Design and fabrication process of a full inorganic electroluminescent microdislay based on aluminum / nanostructured porous silicon reverse biased light emitting Schottky diodes are discussing. Being of a solid state construction. this micro-display is cost-effective, thin and light in weight due to very simple device architecture. Its benefits include also super high resolution, wide viewing angles, fast response time and wide operating temperature range. The advantages of full integration of a LED-array and driving circuitry onto a Si-chip will be also discussed.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.743-745
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• 2002

We reported the possibility of color filtering of white method for achieving full-color displays using OELDs. Here, we fabricated white organic electroluminescent devices (OELDs) and drove moving images with a 384${/times}$160 pixel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.2
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• pp.178-182
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• 2007

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.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.211-212
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• 2000

Organic electroluminescent devices (OELDs) have received a great deal of attention due to their potential application as full-color displays. Europium complexes are known as excellent red light-emitting materials for OELDs since they show intense photoluminescence at around 612 nm with a narrow spectral bandwidth. In this study, a novel europium complex, $Eu(TTA)_3(TPPO)$ was synthesized and its photoluminescent and electroluminescent characteristics were investigated with a device structure of ITO/TPD/$Eu(TTA)_3(TPPO)$/ $Alq_3$/Al, where sharp emission at the wavelength of 615 nm has been observed. Details on the electrical properties of these structures was also discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.103-106
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• 1999

Organic electroluminescent devices (OELDs) have received a great deal of attention due to their potential application as full-color displays. Europium complexes are known as excellent red light-emitting materials for OELDs since they show intense photoluminescence at around 612 nm with a narrow spectral bandwidth. In this study, a novel curopium complex, Eu(TTA)$_3$(TPPO) was synthcsizcd and its photoluminescent and electroluminescent characteristics were investigated with a device structure of ITO/TPD/Eu(TTA)3(TPPO)/A1q$_{3}$ Al, where sharp emission at the wavelength of 615 nm has been observed. Details on the electrical properties of these structures will be also discussed.