• Journal of Sensor Science and Technology
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• v.29 no.1
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• pp.27-32
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• 2020

This study proposes a pixel-patterning method for organic light-emitting diodes (OLEDs) based on thermal transfer. An infrared lamp was introduced as a heat source, and glass type donor element, which absorbs infrared and generates heat and then transfers the organic layer to the substrate, was designed to selectively sublimate the organic material. A 200 nm-thick layer of molybdenum (Mo) was used as the lightto-heat conversion (LTHC) layer, and a 300 nm-thick layer of patterned silicon dioxide (SiO₂), featuring a low heat-transfer coefficient, was formed on top of the LTHC layer to selectively block heat transfer. To prevent the thermal oxidation and diffusion of the LTHC material, a 100 nm-thick layer of silicon nitride (SiN_x) was coated on the material. The fabricated donor glass exhibited appropriate temperature-increment property until 249 ℃, which is enough to evaporate the organic materials. The alpha-step thickness profiler and X-ray reflection (XRR) analysis revealed that the thickness of the transferred film decreased with increase in film density. In the patterning test, we achieved a 100 ㎛-long line and dot pattern with a high transfer accuracy and a mean deviation of ± 4.49 ㎛. By using the thermal-transfer process, we also fabricated a red phosphorescent device to confirm that the emissive layer was transferred well without the separation of the host and the dopant owing to a difference in their evaporation temperatures. Consequently, its efficiency suffered a minor decline owing to the oxidation of the material caused by the poor vacuum pressure of the process chamber; however, it exhibited an identical color property.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.755-757
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• 2009

We developed a novel patterning method of organic light emitting materials using a laser-inscribed sacrificial layer for fabricating high-resolution pixels in organic light emitting displays (OLEDs). Our patterning process is capable of achieving high spatial resolution of about 10 ${\mu}m$. Moreover, it has no detrimental effect on the electrical properties of organic materials. This patterning approach is expected to be applicable for patterning and integrating a wide range of organic materials for organic electronic and optoelectronic devices.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.826-829
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• 2006

In order to increase the transmittance of panel, in process of FFS TFT-LCD, fine patterning process which is adopted to the optimum passivation(PVX) hole was applied fine metal line patterning process and was made with optimum efficiency of liquid crystal by using space/bar size control of pixel electrode. We fabricated 2.03" mobile FFS devices with fine patterning process. Further, this technology will be applied to the basis of other process for higher PPI or higher aperture ratio technology.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.1
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• pp.79-84
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• 1999

the photolithographic patterning on an indium-tin oxide (ITO) glass and the electro-phoretic deposition were combined for preparing the screen of the full-color field emission display(FED). the patterns with a pixel of 400$\mu\textrm{m}$ on the ITO-glass were made by etching the ITO with well-prepared etchant consisting of HCL, H2O, and HNO3. Electrophoretic method was carried out in order to deposit each spherical red (R), green(G), and blue (B) phosphor on the patterned ITO-glass. The process parameters such as bias voltage, salt concentration, and deposition time were optimized to achieve clear boundaries. It was found that the etching process of ITO combined with electrophoretic method was cost-effective, provided distinct pattern, and even reduced process steps compared with conventional processes. The application of reverse bias to the dormant electrodes while depositing the phosphors on the stripe pattern was found to be very critical for preventing the cross-contamination of each phosphor in a pixel.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.299-302
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• 2007

We propose a soft-lithographic patterning method for producing a multi-domain liquid crystal (LC) alignment. The LC alignment polyimide layers are periodically patterned in the pixel boundaries by a micromolding-in-capillaries method. In our structure, the initially homeotropic LC orientations in the pixel areas are changed to axially symmetric LC domains due to the symmetric pretilt of LC molecules on the pixel boundaries.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.987-989
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• 2006

1.52" $130(RGB){\times}130$ full color PM OLED device with $70\;{\mu}m{\times}210\;{\mu}m$ of sub-pixel pitch was fabricated using shadow mask method for metal cathode deposition. Instead of conventional patterning process to form cathode separator via photolithography, regularly patterned shadow mask was applied to deposit metal cathode in this OLED display. Metal cathode was patterned via 2-step evaporation using shadow mask with shape of rectangular stripe and its alignment margin is $2.5\;{\mu}m$. Technical advantages of this method include reduction of process time according to skipping over photolithographic process for cathode separator and minimizing pixel shrinkage caused by PR cathode separator as well as improving lifetime of OLED device.

• Design & Manufacturing
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• v.14 no.3
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• pp.44-49
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• 2020

One of display trends today is development of high pixel density. To get high PPI, a small size of pixel must be developed. RGB pixel is arranged by evaporation process which determines pixel size. Normally, a fine metal mask (FMM; Invar alloy) has been used for evaporation process and it has advantages such as good strength, and low thermal expansion coefficient at low temperature. A FMM has been manufactured by chemical etching which has limitation to controlling the pattern shape and size. One of alternative method for patterning FMM is laser micromachining. Femtosecond laser is normally considered to improve those disadvantages for laser micromachining process due to such short pulse duration. In this paper, a femtosecond laser drilling for thickness of 16 ㎛ FMM is examined. Additionally, we introduce experimental results for controlling taper angle of hole by vibration module adapted in laser system. We used Ti:Sapphire based femtosecond laser with attenuating optics, co-axial illumination, vision system, 3-axis linear stage and vibration module. By controlling vibration amplitude, entrance and exit diameters are controllable. Using vibrating objective lens, we can control taper angle when femtosecond laser hole drilling by moving focusing point. The larger amplitude of vibration we control, the smaller taper angle will be carried out.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.797-798
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• 2005

We report a novel structure for a full-color AMOLED (Active Matrix Organic Light Emitting Diode) eliminating the patterning process of a blue emitting layer. The patterning of the three primary colors, RGB, is a key technology in the OLED fabrication process. Conventional full color AMOLED containing RGB layers includes the three opportunities of the defects to make an accurate position and fine resolution using various technologies such as fine metal mask, ink-jet printing and laser-induced transfer system. We can skip the blue patterning step by simply stacking the blue layer as a common layer to the whole active area after pixelizing two primary colors, RG, in the conventional small molecular OLED structure. The red and green pixel showed equivalent performances without any contribution of the blue emission.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1497-1500
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• 2006

Inkjet printing technology can reduce the LCD color filter manufacturing cost more than 50 %. Uniform color filter patterning can be achieved only with proper ink and barrier materials. We developed new ink and black matrix materials for inkjet color filter. The ink materials have low volatility while they have very high solid content. The black matrix materials have very precisely controlled surface energy so that the inks can fill the pixels evenly and completely. We controlled the ink drop volume and ink material to minimize the thickness difference between the black matrix and the color pixel. Micron-order jetting position accuracy was achieved. We successfully printed 14.1" color filters using our ink and black matrix materials.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.227-229
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• 2003

We present a process for printing active matrix displays. In this process, transistors are fabricated using soluble semi-conducting and conducting materials. Accurate definition of the transistor channel and other circuit components is achieved by direct inkjet printing combined with surface energy patterning. We present results on our 4,800 pixel, 50 dpi, active matrix displays.