• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.1089-1097
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• 2006

The market demand of display devices is drastically increasing in the information technology age. The research on OLED (Organic Light Emitting Diodes) display with the luminescence in itself is being more paid attention than LCD (Liquid Crystal display) with the light source from the back. The vapor deposition process is most essential in manufacturing OLED display. The temperature distribution of the linear cell in this process is closely related to securing the uniformity of organic materials on the substrate. This work analyzed the temperature distribution depending on the intervals between the crucible and the heating band as well as on the amount of the heat flux from the heating band. Moreover, the roles of the water jacket and the configuration of the cover within the linear cell were examined through the temperature analysis for six configurations of the linear cell. Under the above temperature analysis, the variations in the intervals and the amount of the heat flux were considered to have an effect on building the uniform temperature distribution within the crucible. It is predicted that the water jacket and the adequate configuration of the cover will prevent the blowout and clogging phenomena, respectively. The results can be used as the fundamental data for designing the optimal linear cell.

• Journal of the Semiconductor & Display Technology
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• v.6 no.1 s.18
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• pp.23-26
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• 2007

The effects of plasma treatment on the ITO/glass substrate before deposition of organic materials were investigated in the fabrication of green light emitting organic devices with $Alq_3-C545T$ fluorescent system. In our experiments, the optimum plasma treatment was obtained at the power and time of 150W and 2 minutes under the $Ar(50%)/O_2$ ambient of 1 mTorr. The green OLED with plasma treatment at 150W for 2 minutes showed the luminance and efficiency of $4700\;cd/m^2$ and 8 lm/W at 10V, respectively. On the contrary, the same structured device without plasma treatment showed much lower performance with the luminance of $2600\;cd/m^2$ and the efficiency of 3.6 lm/W at 10 V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.781-785
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• 2009

We have fabricated simple triple-layer blue-emitting phosphorescent organic light emitting diodes (OLEDs) using different thicknesses (25 and 55 nm) of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) electron transport layers. 1,1-bis[4-bis (4-methylphenyl)- aminophenyllcyclohexane (TAPC), bis[(4,6-di-fluorophenyl)-pyridinate-$N,C^{2'}$]picolinate (FIrpic) and N,N' -dicarbazolyl-3,5-benzene (mCP) were used as hole transport, blue guest and host materials, respectively. The driving voltage, electroluminescence (EL) efficiency and emission characteristics of devices were investigated. The maximum EL efficiency was 20 cd/A in the device with 55 nm BCP layer, which efficiency was about 33% higher than the device with 25 nm BCP layer. The higher efficiency in the 55 nm BCP device resulted from the enhanced electron-hole balance. In the EL spectrum of blue phosphorescent OLED with BCP layer, the relative intensity between 470 and 500 nm peaks was related to the location of emission zone.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1511-1514
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• 2009

Organic light emitting layer in OLED device was formed by gravure printing process in this work. Organic surface coated by gravure printing typically showed relatively bad uniformity. Thickness and roughness control was characterized by applying various mixed solvents in this work. Poly (N-vinyl carbazole) (PVK) and fact-tris(2-phenylpyridine)iridium($Ir(ppy)_3$) are host dopant system materials. PVK was used as a host and Ir(ppy)3 as green-emitting dopant. To luminance efficiency of the plasma treatment on etched ITO glass and then PEDOT:PSS spin coated. The device layer structure of OLED devices is as follow Glass/ITO/PEDOT:PSS/PVK+Ir(ppy)3-Active layer /LiF/Al. It was printed by gravure printing technology for polymer light emitting diode (PLED). To control the thickness multi-printing technique was applied. As the number of the printing was increased the thickness enhancement was increased. To control the roughness of organic layer film, thermal annealing process was applied. The annealing temperature was varied from room temperature, $40^{\circ}C$, $80^{\circ}C$, to $120^{\circ}C$.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.1014-1018
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• 2007

We have demonstrated the enhancement of the power efficiency and device lifetime of organic light-emitting diodes (OLEDs) by introducing the ETL 1 / ETL2 (composite ETL) structure between EML and cathode and the HIL1 (composite HIL) / HIL2 between anode and HTL. Compared to reference devices retaining conventional architecture, novel OLED structure shows an outstanding EL efficiency that is 1.6 times higher (${\sim}4.5$ lm/w versus ${\sim}$ 2.71 lm/w for the reference device) and lower driving voltage $({\bigtriangleup}V>1V)$, but also a longer lifetime and smaller operating voltage drift over time. It is suggested in this work that the device performance can be improved by in-situ ohmic contact through novel electron controlled structure and reduction of charge accumulation in the interface through composite HIL

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.943-949
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• 2000

In this paper, the single and double heterostructure organic light-emitting devices(OLEDs) were fabricated. The single heterostructure OLED(TYPE 1) is consisted of TPD as a HTL(hole transfer layer) and Alq$_3$as an EML(emitting layer). The double heterostructure OLED(TYPE 2) is consisted of TPD as a HTL, Alq$_3$as an EML and PBD as an ETL(electron transfer layer). The another double heterostructure OLED(TYPE 3) is consisted of TPD as a HTL, PBD as an EML and Alq$_3$as an ETL. We obtained a strong green emission device with maximum EL emission wavelength 500nm in TYPE 3. When the applied voltage was 12V, the emission luminescence was 120.9cd/㎡. The chromaticity index of TYPE 3 was x=0.29, y=0.50. In the characteristic plot of current-voltage, TYPE 3 device was turned on at 6.9V. This voltage was a fairly low turn-on voltage. TYPE 1 and 2 device were turned on at 10V and 8.9V respectively. These types showed no good properties over that of TYPE 3.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.22-26
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• 2021

Thin-film encapsulation (TFE) technology is most effective in preventing water vapor and oxygen permeation in the organic light emitting diodes (OLED). Of those, a laminated structure of Al₂O₃ and MgO were applied to provide efficient barrier performance for increasing the stability of devices in air. Atomic layer deposition (ALD) method is known as the most promising technology for making the laminated Al₂O₃/MgO and is used to realize a thin film encapsulation technology in organic light-emitting diodes. Atomic layer deposited inorganic films have superior barrier performance and have advantages of excellent uniformity over large scales at relatively low deposition temperatures. In this study, the control system of the MgCP₂ precursor for the atomic layer deposition of MgO was established in order to deposit the MgO layer stably by the injection time of second level and the stable heating temperature. The deposition rate was obtained stably to be from 4 to 10 Å/cycle using the injection pulse times ranging from 3 to 12 sec and a substrate temperature ranging from 80 to 150 ℃.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.36-37
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• 2009

We have studied the effect of the hole transporting layers on the device efficiencies blue phosphorescent organic light emitting diodes (PHOLED) with of iridiumIIIbis4,6-di-fluorophenyl-pyridinato-N,C2picolinate (FIrpic) doped 3,5--N,N-dicarbazole-benzene (mCP) host. The highest efficiency of blue PHOLED is strongy dependent on the hole transporting materials, exhibiting the maximum current efficiency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.305-306
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• 2009

In this study, we have invastigated the recombination zone in the blue phosphorescent organic light-emitting devices with various partially doped structures. The basic device structure of the blue PHOLED was anode / hole injection layer (HIL) / hole transport layer (HTL) / emittingvastigated the recombination zone in the blue layer (EML) / hole blocking layer (HBL) / electron transport layer (ETL) / electron injection layer (EIL) / cathode. After the preparation of the blue PHOLED, the current density (J) - voltage (V) - luminance (L) and current efficiency characteristics were measured.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.307-308
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• 2009

We have proposed an index matching film to improve the emitting efficiency of green OLED. Here, SiO2 and TiO2 were selected to coat the green OLED. The structures of index matching film were designed in G1ass/TiO2/SiO2/ITO and SiO2/TiO2/Glass/ITO. Then, these materials were deposited by ion-assisted deposition system. Transmittances of deposited devices were 86.14 and 85.07 %, respectively.