• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1133-1137
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• 2005

In this paper, a renovated approach in the fabrication of red organic light-emitting diodes (OLEDs) is described. The hard-to-control doping process required for dopant-based red OLEDs can be avoided due to the novel red fluorophores that are not concentration quenching in solid state. Doping is in general a must for phosphorescence OLEDs because of the triplet-triplet annihilation, a common problem for phosphorophore dopants. However, we have recently found that extraordinary red iridium complex showing relatively short emission lifetime render the non-doped phosphorescence red OLED possible.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.71-72
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• 2006

We report on plasma damage free chemical vapor deposition technique for the thin film passivation of organic light emitting diodes (OLEDs), organic thin film transistor (OTFT) and flexible displays using catalyzer enhanced chemical vapor deposition (CECVD). Specially designed CECVD system has a ladder-shaped tungsten catalyzer and movable electrostatic chuck for low temperature deposition process. The top emitting OLED with thin film $SiN_x$ passivation layer shows electrical and optical characteristics comparable to those of the OLED with glass encapsulation. This indicates that the CECVD technique is a promising candidate to grow high-quality thin film passivation layer on OLED, OTFT, and flexible displays.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.446-449
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• 2008

Organic light emitting diodes (OLEDs) with multiple organic layers were fabricated to obtain and to evaluate an equivalent resistance and an equivalent capacitance of OLED device. The staircase voltage with an increasing period and a constant period was designed and applied to the OLED. The resistance of OLED was found to decrease from $270\;k{\Omega}$ to $2\;K{\Omega}$ as applied voltage increased after turn on. The equivalent capacitance of OLED maintained unchanged at low voltage level and deceased after showing peak value as the applied voltage increased.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.741-744
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• 2007

The research applied the processes of spin-coating and thermal-evaporating in proper order to deposit the hole transport material N,N'-Bis(naphthalen-1-yl)- N,N'-bis(phenyl)-benzidine (NPB) on the ITO substrate to make flexible organic light emitting diodes (FOLED) with double hole transport layer.

• Journal of Information Display
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• v.8 no.3
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• pp.11-16
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• 2007

Theoretical simulations of spatial distribution of charge carriers and recombination rate, and J-V characteristics of the multi-layer organic light emitting diodes are carried out. Drift-diffusion current transport, field-dependent carrier mobility, exponential and Gaussian trap distribution, and Langevin recombination models are included in this computer model. The simulated results show good agreement with the experimental data confirming the validity of the physical models for organic light emitting diodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.475-476
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• 2005

Efficient electron injection is essential to achieve bright and efficient organic light-emitting diodes (OLEDs). In spite of high work function of Al, it is a common cathode because of its stability. In this paper, to overcome the poor electron injection in OLEDs with Al cathode, OLEDs with various composite cathodes were fabricated and investigated using a conventional OLEDs structure of indium tin oxide ITO/NPB(40 nm)/$Alq_3$(50 nm)/Al. composite cathodes were composed of alkaline materials such as Ca and Li, Al deposition or codeposited with AI. We showed best performance at the device with composite cathode (LiF/Al).

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.374-374
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• 2012

Nowadays, Active Matrix Organic Light-Emitting Diodes (AM-OLEDs) are the superior display device due to their vivid full color, perfect video capability, light weight, low driving power, and potential flexibility. One of the advantages of AM-OLED over Liquid Crystal Display (LCD) lies in its flexibility. The potential flexibility of AM-OLED is not fully explored due to its sensitivity to moisture and oxygen which are readily present in atmosphere, and there are no flexible encapsulation layers available to protect these. Therefore, we come up with a new concept of Inorganic-Organic hybrid thin film as the encapsulation layer. Our Inorganic layer is Al2O3 and Organic layer is F-Alucone. We deposited these layers in vacuum state using Atomic Layer Deposition (ALD) and Molecular Layer Deposition (MLD) techniques. We found the results are comparable to commercial requirement of 10-6 g/m2 day for Water Vapor Transmission Rate (WVTR). Using ALD and MLD, we can control the exact thin film thickness and fabricate more dense films than chemical or physical vapor deposition methods. Moreover, this hybrid encapsulation layer potentially has both the flexibility of organic layers and superior protection properties of inorganic layer.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.1
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• pp.49-55
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• 2015

This paper reports solution-processed, high-efficiency organic light-emitting diodes (OLEDs) fabricated by a knife coating method under ambient air conditions. In addition, indium tin oxide (ITO), traditionally used as the anode, was substituted by optimizing the conductivity enhancement treatment of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films on a polyethylene terephthalate (PET) substrate. The transmittance and sheet resistance of the optimized PEDOT:PSS anode were 83.4% and $27.8{\Omega}/sq$., respectively. The root mean square surface roughness of the PEDOT:PSS anode, measured by atomic force microscopy, was only 2.95 nm. The optimized OLED device showed a maximum current efficiency and maximum luminous density of 5.44 cd/A and $8,356cd/m^2$, respectively. As a result, the OLEDs created using the PEDOT:PSS anode possessed highly comparable characteristics to those created using ITO anodes.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.659-662
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• 2007

The characteristics of a $SiN_x$ passivation layer grown by a specially designed catalyzer enhanced chemical vapor deposition (CECVD) system and electrical and optical properties of OLEDs passivated with the $SiN_x$ layer are described. Despite the low substrate temperature, the single $SiN_x$ passivation layer, grown on the PC substrate, exhibited a low water vapor transmission rate of $2{\sim}6{\times}10^{-2}\;g/m^2/day$ and a high transmittance of 87 %. In addition, current-voltage-luminescence results of an OLED passivated with a 150 nm-thick $SiN_x$ film compared to nonpassivated sample were identical indicating that the performance of an OLED is not critically affected by radiation from tungsten catalyzer during the $SiN_x$ deposition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.399-400
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• 2007

In this work, we have investigated the characteristics of the phosphorescent OLED and flexible OLED fabricated on IZTO/glass and IZTO/PET anode film grown by magnetron sputtering, respectively. Electrical and optical characteristics of amorphous IZTO/glass anode exhibited similar to commercial ITO anode even though it was deposited at room temperature. In addition, the amorphous IZTO anode showed higher work function than that of the commercial ITO anode after ozone treatment for 10 minutes. Furthermore, a phosphorescent OLED fabricated on amorphous IZTO anode film showed improved current-voltage-luminance characteristics, external quantum efficiency and power efficiency in contrast with phosphorescent OLED fabricated on commercial ITO anode film. This indicates that IZTO anode is promising alternative anode materials for anode in OLEDs and flexible OLEDs.