• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.160-160
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• 2010

Organic electronic devices require a passivation layer to ensure sufficient lifetime. Specifically, flexible organic electronic devices need a barrier layer that transmits less than $10^{-6}\;g/m^2/day$ of water and $10^{-5}\;g/m^2/day$ of oxygen. To increase the lifetime of organic electronic device, therefore, it is indispensable to protect the organic materials from water and oxygen. Severe groups have reported on multi-layerd barriers consisting inorganic thin films deposited by plasma enhenced chemical deposition (PECVD) or sputtering. However, it is difficult to control the formation of granular-type morphology and microscopic pinholes in PECVD and sputtering. On the contrary, atomic layer deoposition (ALD) is free of pinhole, highly uniform, conformal films and show good step coverage. In this study, the passivation layer was deposited using single-process PEALD. The passivation layer, in our case, was a bilayer system consisting of $Al_2O_3$ films and a $TiO_2$ buffer layer on a poly (ether sulfon) (PES) substrate. Because the deposition temperature and plasma power have a significant effect on the properties of the passivation layer, the characteristics of the $Al_2O_3$ films were investigated in terms of density under different deposition temperatures and plasma powers. The effect of the $TiO_2$ buffer layer also was also addressed. In addition, the water vapor transmission rate (WVTR) and organic light-emitting diode (OLEDs) lifetime were measured after forming a bilayer composed of $Al_2O_3/TiO_2$ on a PES substrate.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1480-1483
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• 2005

Transparent thin composite films (TCFs) were deposited on OLED devices by means of RF sputtering method and their passivation-properties were evaluated by comparing to the e-beam evaporating method. This composite film formed by mixed ratio of MgO (3wt %): $SiO_2$ (1wt %) was developed from pallet as a source of e-beam evaporator to 6-inch size target for sputtering in order to apply for large-sized organic display devices. Water Vapor Transmission Rates (WVTR) of the deposited films were measured as a function of thickness to assess the effectiveness of this film as a passivation layer and it applied to real devices. From this study, we can confirm that the passivation layer formed by TCFs using RF sputtering method sufficiently shows the potentiality of application to passivation layer for organic display devices.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.105-110
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• 2014

It is required to improve the efficiency and the reliability of the polymer solar cells (PSCs) as the energy saving optical device for the future application of the smart farm facilities. In this study, we fabricated the bulk hetero junction PSCs with organic passivation film layer for the reliability improvement of the devices. The effects of the passivation layer on the electrical properties of the PSCs were studied. The materials of passivation layer are composed of poly vinyl alcohol (PVA) and ammonium dichromate, and the passivation films were fabricated by the spin coating method on the P3HT:$PC_{61}BM$/LiF/Al substrate. The prepared structure of the device is the glass/ITO/PEDOT:PSS/P3HT:$PC_{61}BM$/LiF/Al/passivation layer. The performances of the PSCs with the organic passivation film showed better electrical properties compared with the PSCs without passivation layers. The power conversion efficiency (PCE) values of passivated PSCs decreased from 3.0 to 1.3% after air exposure for 140 hrs. In contrast, the PCE values for the devices without passivation decreased sharply from 3.5 to 0.1% under the same exposure condition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.332-333
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• 2009

In this paper, we have deposited silicon nitride films by plasma-enhanced chemical vapor deposition (PECVD). For films deposited under optimized conditions, the mechanism of plasma-enhanced vapor deposition of silicon nitride is studied by varying process parameters such as rf power, gas ratio, and chamber pressure. It was demonstrated that organic light-emitting diode(OLEDs) were fabricated with the inorganic passivation layer processing. We have been studied the inorganic film encapsulation effect for organic light-emitting diodes (OLED). To evaluate the passivation layer, we have carried out the fabrication of OLEDs and investigate with luminescence and MOCON.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.1
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• pp.11-15
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• 2016

The organic light emitting diodes (OLEDs) have been studied as large flexible displays, light source and hard wares of internet of things. However, OLEDs show some drawbacks in terms of external environments due to the low work function of the metals and the reactive organic materials. In particular, the operation functions of the OLEDs tend to deteriorate rapidly by exposing the oxygen and moisture. So as to prevent it, domestic and overseas studies underway in various method such as ALD, PVD, CVD. But it has complex process and high cost. Therefore In order to protect devices from the external environments, it is important to develop the passivation thin films of low-cost and simple process which can prevent the devices from the penetration of the oxygen and moistures. In this study, to improve the reliability, passivation thin films were coated onto the green OLEDs by spin coating method and investigated the changes of the optical properties of the prepared devices at various doping concentrations of sodium alginate (SA). The passivation solutions were synthesized by using polyvinyl alcohol (PVA) host material with a dopant of SA which were added with the amounts of 10, 20 and 40 wt% into the PVA. As a result, the best barrier properties of the OLEDs were obtained for the samples with 40 wt% SA. Finally, the passivation films can be optimized by using the mixture solution of PVA and SA materials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.1
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• pp.60-64
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• 2003

In this study, the inorganic thin-film passivation layer was newly adopted to protect the organic layer from moisture and oxygen. Using the electron beam evaporation system, the various kinds of inorganic thin-films were deposited onto the organic layer and their interface properties between organic and inorganic layer were investigated. In this investigation, the MgO layer showed the most suitable properties, and based on this result, the time dependent emission properties were estimated for the OLED with and without passivation layer. In this experiment, we can see that the time-dependent emission properties of MgO passivated OLED had longer life-time compared to non-passivated OLED. Therefore, we can consider that the MgO thin film is one of the most suitable candidates for the thin-film passivation layer of OLED.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1412-1413
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• 2006

In this research, an organic thin 13 passivation layer was newly adopted to prefect the organic layer from ambient moisture and oxygen. As the organic thin film passivation layer, poly methyl methacrylate thin films (ppMMA) were deposited using a plasma polymerization technique. In order to their passivation performance for OLEDs, water vapor transmission rate (WVTR) of the ppMMAs were analyzed and luminance-current-voltage (L-I-V)/luminance-time (L-T) characteristics of the OLEDs with and without ppMMA passivation layer were investigated. The OLEDs had a structure of ITO/TPD (HTL)/Alq3(EML&ETL)/Al. The OLED with ppMMA passivation layer showed improved L-T performance than that of without ppMMA passivation layer.

• 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.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.420-423
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• 2008

The characteristics of $Al_2O_3/Ag/Al_2O_3$ multilayer passivaton prepared by twin target sputtering (TTS) system for organic light emitting diodes. The $Al_2O_3/Ag/Al_2O_3$ multilayer thin film passivation on a PET substrate had a high transmittance of 86.44 % and low water vapor transmission rate (WVTR) of $0.011\;g/m^2$-day due to the surface plasmon resonance (SPR) effect of Ag interlayer and effective multilayer structure for preventing the intrusion of water vapor. Using synchrotron x-ray scattering and field emission scanning electron microscope (FESEM) examinations, we investigated the growth behavior of Ag layer on the $Al_2O_3$ layer to explain the SPR effect of the Ag layer. This indicates that an $Al_2O_3/Ag/Al_2O_3$ multilayer passivation is a promising thin film passivation scheme for organic based flexible optoelectronics.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.574-581
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• 2012

The relatively short lifetime is a major obstruction for the commercial applications of OLED. One of the reason for the short lifetime is that the organic materials are interacted with water or oxygen in the atmosphere. Protection of water or oxygen from diffusing into the organic material layers are necessary to increase the lifetime of OLED. Although encapsulation of OLED with glass or metal cans has been established, passivation methods of OLED by organic/inorganic thin films are still being developed. In this paper we have developed in-situ passivation system and thin film passivation method using PECVD by which deposition can be performed at room temperature. We have analyzed the characteristics of the passivated OLED device also. The WVTR (Water Vapor Transmission Rate) for the inorganic thin film mono-layer can be reached down to $1{\times}10^{-2}g/m^2{\cdot}day$ and improved lifetime can be obtained. Thin film passivation methods are expected to be applied to flexible display.