• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.457-457
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• 2010

Flexible organic light emitting diodes (F-OLEDs) requires excellent moisture permeation barriers to minimize the degradation of the F-OLEDs device. Specifically, F-OLEDs device 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 life time of F-OLEDs, 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. Thus, $Al_2O_3/TiO_2$ multi-layer was deposited onto the polyethersulfon (PES) substrate by electron cyclotron resonance atomic layer deposition (ECR-ALD), and the water vapor transmission rates (WVTR) were measured. WVTR of moisture permeation barriers is dependent upon density of films and initial state of polymer surface. A significant reduction of WVTR was achieved by increasing density of films and by applying low plasma induced interlayer on the PES substrate. In order to minimize damage of polymer surface, a 10 nm thick $TiO_2$ was deposited on PES prior to a $Al_2O_3$ ECR-ALD process. High quality barriers were developed from $Al_2O_3$ barriers on the $TiO_2$ interlayer. WVTR of $Al_2O_3$ by introducing $TiO_2$ interlayer was recorded in the range of $10^{-3}g/m^2.day$ at $38^{\circ}C$ and 100% relative humidity using a MOCON instrument. The WVTR was two orders of magnitude smaller than $Al_2O_3$ barriers directly grown on PES substrate without the $TiO_2$ interlayer. Thus, we can consider that the $Al_2O_3/TiO_2$ multi-layer passivation can be one of the most suitable F-OLEDs passivation films.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.1933-1938
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• 2009

New $\pi$-conjugated polymer with vinylene linkage, poly((10-hexyl-3,7-phenothiazine)-alt-(4-(4-butyl-phenyl)- 3,5-diphenyl-4H-[1,2,4]triazole)-3,5-vinylene) (PTV-TAZ) was synthesized by the Heck coupling reaction. The photoluminescence (PL) maximum wavelength and the band gap energy of PTV-TAZ film were 555 nm and 2.41 eV, respectively. The HOMO energy level of PTV-TAZ was -4.99 eV, which was slightly lower than that of PTV (-4.89 eV). Electron deficient aromatic 1,2,4-triazole (TAZ) in the polymer backbone does not affect the HOMO energy level significantly. The maximum efficiency and brightness of double layer structured electroluminescent (EL) device (ITO/PEDOT (30 nm)/PTV-TAZ (60 nm)/Al) were 0.247 cd/A and 553 cd/$m^2$, respectively, which were significantly higher than those of the device based PTV (1.65 ${\times}\;10^{-4}$ cd/A and 4.3 cd/$m^2$). This is due to that TAZ unit improves electron transporting ability in the emissive layer. The turn-on voltage (defined as the voltage required to give a luminescence of 1 cd/$m^2$) of brightness of the device based on PTV-TAZ was 12.0 V, which was similar to that the based on PTV (11.5 V). This is due to that the ionization potential of PTV-TAZ is very similar to that of PTV.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.575-578
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• 2004

The charging tendency of $Zn_2SiO_4:Mn^{2+}$ phosphor surface was modified in order to improve discharging characteristic of green cell in an ac-plasma display panel (ac-PDP). The Zinc-silicate ($Zn_2SiO_4:Mn^{2+}$) green-emitting phosphor was coated with magnesium oxide(MgO), which is viable to have positive charge on the surface. After fabricating the green cell with MgO-coated $Zn_2SiO_4:Mn^{2+}$, the electrical and optical properties in the cell were examined. It was found that the dynamic voltage margin could be increased while the address time was reduced. It may be ascribed to the change of charging tendency of $Zn_2SiO_4:Mn^{2+}$ phosphor by MgO coating, which makes it possible to stable wall-charge accumulation. When $Zn_2SiO_4:Mn^{2+}$ phosphor was coated with 1.3wt%-MgO, the address time was reduced 1.2 ${\mu}s$ and the address voltage lowered 25 V without any misfiring problem, compared to those of typical $Zn_2SiO_4:Mn^{2+}$ phosphor layer. The luminescence intensity of green cell using MgO-coated phosphor layer was also improved by 10%.

• Journal of the Korea Convergence Society
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• v.6 no.3
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• pp.103-109
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• 2015

TOLED(Transparent, Organic Light Emitting Diodes) based edutainment system has been studied to solve the actual feeling training and educational experience problem of e-learning. However, edutainment system using TOLED has a problem for the non-detection of multi marker array and rotate marker array, and it has problem for the dissonance phenomena caused by Illumination Environment between real world and virtual object. It also has a do not provide services through a variety of devices problem. Therefore, in this paper, we designed a system that provides a realistic actual feeling edutainment contents by recognizes the marker array rotation and a plurality of marker arrangement via an improved marker detection technique. And to unify the real space and virtual space of the lighting environment through a nested block layer.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.95-95
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• 2014

An OLED(Organic Light-Emitting Diode) device based on the emissive electroluminescent layer a film of organic materials. OLED is used for many electronic devices such as TV, mobile phones, handheld games consoles. ULVAC's mass production systems are indispensable to the manufacturing of OLED device. ULVAC is a manufacturer and worldwide supplier of equipment and vacuum systems for the OLED, LCD, Semiconductor, Electronics, Optical device and related high technology industries. The SMD Series are single-substrate sputtering systems for deposition of films such as metal films and TCO (Transparent Conductive Oxide) films. ULVAC has delivered a large number of these systems not only Organic Evaporating systems but also LTPS CVD systems. The most important technology of thin-film encapsulation (TFE) is preventing moisture($H_2O$) and oxygen permeation into flexible OLED devices. As a polymer substrate does not offer the same barrier performance as glass substrate, the TFE should be developed on both the bottom and top side of the device layers for sufficient lifetimes. This report provides a review of promising thin-film barrier technologies as well as the WVTR(Water Vapor Transmission Rate) properties. Multilayer thin-film deposition technology of organic and inorganic layer is very effective method for increasing barrier performance of OLED device. Gases and water in the organic evaporating system is having a strong influence as impurities to OLED device. CRYO pump is one of the very useful vacuum components to reduce above impurities. There for CRYO pump is faster than conventional TMP exhaust velocity of gases and water. So, we suggest new method to make a good vacuum condition which is CRYO Trap addition on OLED evaporator. Alignment accuracy is one of the key technologies to perform high resolution OLED device. In order to reduce vibration characteristic of CRYO pump, ULVAC has developed low vibration CRYO pumps to achieve high resolution alignment performance between Metal mask and substrate. This report also includes ULVAC's approach for these issues.

• Polymer(Korea)
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• v.24 no.1
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• pp.90-96
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• 2000

Organic electroluminescent (EL) device was fabricated with Alq$_3$ as an emitting material and PDPMA ultra thin film prepared by Langmuir-Boldgett technique as a polymer hole transport layer. A stable condensed PDPMA monolayer was obtained using arachidic acid as a surface active material. The thickness and absorbance of PDPMA LB film increased line-arly with the layer numbers. The organic multilayered device consisted of ITO/PDPMA LB film (19 layers)/Alq$_3$/Al emitted green light with brightness of 2500 cd/m$^2$ at a DC 14 V Especially, the drive voltage of EL device having PDPMA LB film of 15 layers exhibited the value as low as 4 V. The effects of thickness control and molecular orientation in the PDPMA LB film on EL performance were discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.199-199
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• 2011

Recently, Thin film transistors (TFTs) with amorphous oxide semiconductors (AOSs) can offer an important aspect for next generation displays with high mobility. Several oxide semiconductor such as ZnO, $SnO_2$ and InGaZnO have been extensively researched. Especially, as a well-known binary metal oxide, tin oxide ($SnO_2$), usually acts as n-type semiconductor with a wide band gap of 3.6eV. Over the past several decades intensive research activities have been conducted on $SnO_2$ in the bulk, thin film and nanostructure forms due to its interesting electrical properties making it a promising material for applications in solar cells, flat panel displays, and light emitting devices. But, its application to the active channel of TFTs have been limited due to the difficulties in controlling the electron density and n-type of operation with depletion mode. In this study, we fabricated staggered bottom-gate structure $SnO_2$-TFTs and patterned channel layer used a shadow mask. Then we compare to the performance intrinsic $SnO_2$-TFTs and doping hafnium $SnO_2$-TFTs. As a result, we suggest that can be control the defect formation of $SnO_2$-TFTs by doping hafnium. The hafnium element into the $SnO_2$ thin-films maybe acts to control the carrier concentration by suppressing carrier generation via oxygen vacancy formation. Furthermore, it can be also control the mobility. And bias stability of $SnO_2$-TFTs is improvement using doping hafnium. Enhancement of device stability was attributed to the reduced defect in channel layer or interface. In order to verify this effect, we employed to measure activation energy that can be explained by the thermal activation process of the subthreshold drain current.

• Journal of the Semiconductor & Display Technology
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• v.5 no.3 s.16
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• pp.1-4
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• 2006

White-light-emitting ZnS:Mn, Cu, Cl phosphors with spherical shape and the size of $20\;{\mu}m$ are successfully synthesized. They have the double phases of cubic and hexagonal structures. They are applied to electroluminescent (EL) devices by silk screen method with the following structure: $electrode/BaTiO_3$ insulator layer ($50{\sim}60\;{\mu}m$)/ ZnS:Mn, Cu, Cl phosphor layer ($30{\sim}50\;{\mu}m$)/ITO glass. The EL devices are driven with the voltage of 100 V and the frequency of 400 Hz. The EL devices show the three emission peaks. The blue and green emission bands are originated from $CICu^{2+}$ transition and $ClCu^+$ transition, respectively. The yellow emission band results from $^4T^6A$ transition of $Mn^{2+}$ ion. As an increase of Cu concentrations, the blue and green emission intensities decrease whereas the yellow emission intensity increases; the quality becomes warm white. It is due to the energy transfer from the blue and green bands to the yellow band.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.87-88
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• 2008

In the structure of ITO/N,N'-diphenyl-N,N' bis (3-methylphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris (8-hydroxyquinoline)aluminum$(Alq_3)$/Al device, we studied the efficiency improvement of organic light-emitting diodes due to variation of deposition rate of TPD materials. The thickness of TPD and $Alq_3$ was manufactured 40 nm, 60 nm, respectively under a base pressure of $5\times10^{-6}$Torr using a thermal evaporation. The $Alq_3$ used for an electron-transport and emissive layer were evaporated to be at a deposition rate of 2.5 $\AA$/s. When the deposition rate of TPD increased from 1.5 to 3.0 $\AA$/s, we found that the average roughness is rather smoother, external quantum efficiency is superior to the others when the deposition rate of TPD is 2.5 $\AA$/s. Compared to the ones from the devices made with the deposition rate of TPD 3.0 $\AA$/s, the external quantum efficiency was improved by a factor of eight.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.425-430
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• 2009

$ZrO_2$ film was deposited by facing target sputtering (FTS) system on polyethylene naphthalate (PEN) substrate as a gas barrier layer for flexible organic light emitting devices (FOLEDs), In order to control the heat of the FTS system caused by the ion bombardment in the cathode compared with the conventional sputtering system, the process characteristics of the FTS apparatus are investigated under various sputtering conditions such as the distance between two targets ($d_{TT}$), the distance between the target and the substrate ($d_{TS}$), and the deposition time. The $ZrO_2$ film by the FTS system can reduce the damage on the films because the ion bombardment with high-energy particles like gamma-electrons, Moreover, the $ZrO_2$ film with optimized condition ($d_{TT}$=140 mm) as a function of the distance from center to edge showed a very uniform thickness below 5 % for a deposition time of 3 hours, which can improve the interface property between the anode and the plastics substrate for flexible displays, It is concluded that the $ZrO_2$ film prepared by the FTS system can be applied as a gas barrier layer or an interlayer between the anode and the plastic substrate with good properties of an uniform thickness and a low deposition-temperature.