• 한국위성정보통신학회논문지
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• 제10권3호
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• pp.89-93
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• 2015

본 연구에서는 이온빔 처리된 $HfO_2$ 박막을 이용한 액정디스플레이의 프리틸트각을 제어함으로써, 작은 구동전압에서도 안정적으로 구동할 수 있는 디스플레이 소자에 응용할 수 있는 특성을 연구하였다. $HfO_2$ 박막의 원자 수준의 증착을 통해서 높은 유전율의 박막을 제조할 수 있었으며, 이는 저전력 구동을 위해서 필수적인 요소라고 생각한다. 또한 이러한 $HfO_2$ 박막의 액정배향성을 확인하여 균일한 액정배향을 통해서 디스플레이 소자로의 응용가능성을 확인하였다. 특히 $HfO_2$ 박막에서의 액정배향성에 대해서 액정배향의 대표적인 특성인 프리틸트각의 제어를 실험을 통해서 확인하였다. 실험결과 이온빔처리를 한 $HfO_2$ 박막에서의 액정배향의 특성을 접촉각특성을 대표화하여 정량화 할 수 있었다. 본 연구의 결과 액정의 배향성 확보 및 프리틸트각을 제어할 수 있는 고유전율 $HfO_2$ 박막의 제조가 가능한 것을 확인할 수 있었으며, 고유전율 특성에서 기인하는 저전력 구동의 가능성을 확인할 수 있었다.

• 한국전기전자재료학회논문지
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• 제17권10호
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• pp.1100-1106
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• 2004

In this paper, we intend to make fringe-field switching (FFS) mode cell by the ion beam (IB) alignment method on the a-C：H thin film, to analyze electro-optical characteristics in this cell. We studied on the suitable inorganic thin film for fringe-field switching (FFS) cell and the aligning capabilities of nematic liquid crystal (NLC) using the alignment material of a-C：H thin film as working gas at 30 W rf bias condition. A high pretilt angle of about 5 $^{\circ}C$ by ion beam (IB) exposure on the a-C：H thin film surface was measured. Consequently, the high pretilt angle and the good thermal stability of LC alignment by the IB alignment method on the a-C：H thin film surface as working gas at 30 W rf bias condition can be achieved. An excellent voltage-transmittance (V -T) and response time curve of the IE-aligned FFS-LCD was observed with oblique IB exposure on the a-C：H thin films. Also, AC V-T hysteresis characteristics of the IB-aligned FFS-LCD with IE exposure on the a-C：H thin films is almost the same as that of the rubbing-aligned FFS cell on a polyimide (PI) surface.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.370-370
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• 2007

The liquid crystal (LC) aligning capabilities treated on the Organic overcoat thin film surfaces by ion beam irradiation and rubbing method was successfully studied for the first time. The Organic overcoat layer was coated by spin-coating. In order to characterize the LC alignment, the microscope, pretilt angle, thermal stress, and atomic force microscopy (AFM) image was used. The good LC aligning capabilities treated on the Organic overcoat thin film surfaces with ion beam exposure of $45^{\circ}$ above ion beam energy density of 1200 eV can be achieved. But, the alignment of defect of NLC on the Organicovercoat surface at low energy density of 600 eV was measured. The pretilt angle of NLC on the Organic overcoat thin film surface with ion beam exposure of $45^{\circ}$ for 1 min at energy density of 1800eV was measured about 1.13 degree. But, low pretilt angles of NLC on the Organic overcoat thin film surface with ion beam exposure at energy density of 600, 1200, 2400, and 3000 eV was measured. Also, the pretilt angle of NLC on the rubbed Organic overcoat thin film surfaces was measured about 0.04 degrees. Finally, the good thermal stability of LC alignment on the Organic overcoat thin film surface with ion beam exposure of $45^{\circ}$ for 1 min can be measured.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.766-768
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• 2004

Rubbed films of a series of poly(p-phenylene 3,6-bis(4-(n-alkyloxy)phenyloxy)pyromellitimide)s (Cn-PMDA-PDA PIs), which are well-defined brush PIs composed of two aromatic-aliphatic bristles per repeat unit of a fully rodlike backbone, were investigated in detail using atomic force microscopy (AFM), optical retardation analysis and linearly polarized infrared (IR) spectroscopy in order to elucidate their surface morphology and molecular orientation. The liquid crystal (LC) alignment behavior and the anchoring energy of LC molecules on the rubbed films were also determined.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.430-430
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• 2007

In this study, the nematic liquid crystal (NLC) alignment effects treated on the ZnO thin film layers using ion beam irradiation were successfully studied for the first time. The ZnO thin films were deposited on indium-tin-oxide (ITO) coated glass substrates by rf-sputter and The ZnO thin films were deposited at the three kinds of rf power. The used DuoPIGatron type ion beam system, which can be advantageous in a large area with high density plasma generation. The ion beam parameters were as follows: energy of 1800 eV, exposure time of 1 min and ion beam current of $4\;mA/cm^2$ at exposure angles of $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$. The homogeneous and homeotropic LC aligning capabilities treated on the ZnO thin film surface with ion beam exposure of $45^{\circ}$ for 1 min can be achieved. The low pretilt angle for a NLC treated on the ZnO thin film surface with ion beam irradiation for all incident angles was measured. The good LC alignment treated on the ZnO thin film with ion beam exposure at rf power of 150 W can be measure. For identifying surfaces topography of the ZnO thin films, atomic force microscopy (AFM) was introduced. After ion beam irradiation, test samples were fabricated in an anti-parallel configuration with a cell gap of $60{\mu}m$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1765-1767
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• 1999

We synthesised a photo-alignment material of PM4Ch (poly(4-methacryloylloxychalcone)). The electro-optical (EO) characteristics of photo-aligned twisted nematic (TN)-liquid crystal display (LCD) with linearly polarized ultraviolet (UV) light irradiation on PM4Ch surface were investigated. The uniform alignment of NLC with polarized UV light irradiation on PM4Ch surface was measured. Also, We had The excellent voltage-transmittance characteristics of photo-aligned TN-LCD. The low threshold voltage of photo-aligned TN-LCD was measured. Moreover, the fast response time of photo-aligned TN-LCD on PM4Ch was successfully achieved. Finally The reduction DC voltage of photo-aligned TN-LCD decreases with increasing the UV light irradiation time on photo-dimerized PM4Ch surface.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.271-272
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• 2009

We fabricated a hybrid aligned film using reactive rod-like mesogen to reduce light leakage of twisted nematic(TN) cell in off-axis of the dark state. We proved that the fabricated compensation film has hybrid alignment by changing phase retardation according to polar angle. In this paper, we confirmed characteristics of compensation film through simulation results and found the matching factor of simulation results and experimental result. In result, the maximum pretilt angle of hybrid compensated film is $19^{\circ}$ which has phase retardation 0.1445.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1258-1260
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• 1998

In this study, we investigated the generation of pretilt angle for nematic liquid crystal (NLC) in a cell with oblique non-polarized ultraviolet (UV) light irradiation on polyimide (PI) surfaces. It was found that the monodomain alignment of the NLC is obtained with an angle of incidence of $70{\sim}85^{\circ}$ on PI surface. We consider that the monodomain alignment of NLC is attributed to anisotropic dispersion force due to photo-depolymerization of polymer on PI surfaces. Also, pretilt angle of NLC is generated about $3^{\circ}$ with an angle of incidence of $70{\sim}75^{\circ}$. It is considered that the pretilt angle generation in NLC is attributed to interaction between the LC molecules and the polymer surfaces.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1261-1263
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• 1998

In this paper, we obtained that the monodomain alignment of nematic liquid crystal (NLC) increases with increasing irradiation time with linearly polarized ultraviolet (LPUV) light irradiation on polyimide (PI) surfaces. It was found that the monodomain alignment of NLC is obtained in a cell with normally LPUV light irradiated on PI surface at 30 min. and then oblique LPUV is secondly irradiated on PI surfaces rotated by $90^{\circ}$. The pretilt angle of NLC is generated about $2.5^{\circ}$ with oblique angle of $60^{\circ}$ and then decreased with increasing the oblique angle of IN light irradiation. It is considered that the pretilt angle of NLC is attributed to the photo-depolymerization of polymer with the oblique angle of UV light. The voltage-transmittance and response time characteristics of photo-aligned twisted nematic (TN)-LCD with UV light irradiation time of 60 min. were almost same in comparison with rubbing treated TN-LCD.

• Macromolecular Research
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• 제14권1호
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• pp.1-33
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• 2006

Polyimides (PIs) exhibit excellent thermal stability, mechanical, dielectric, and chemical resistance properties due to their heterocyclic imide rings and aromatic rings on the backbone. Due to these advantageous properties, PIs have found diverse applications in industry. Most PIs are insoluble because of the nature of the high chemical resistance. Thus, they are generally used as a soluble precursor polymer, which forms complexes with solvent molecules, and then finally converts to the corresponding polyimides via imidization reaction. This complexation with solvent has caused severe difficulty in the characterization of the precursor polymers. However, significant progress has recently been made on the detailed characterization of PI precursors and their imidization reaction. On the other hand, much research effort has been exerted to reduce the dielectric constant of PIs, as demanded in the microelectronics industry, through chemical modifications, as well as to develop high performance, light-emitting PIs and liquid crystal (LC) alignment layer PIs with both rubbing and rubbing-free processibility, which are desired in the flat-panel display industry. This article reviews this recent research progresses in characterizing PIs and their precursors and in developing low dielectric constant, light-emitting, and LC alignment layer PIs.