• Title/Summary/Keyword: Liquid crystal

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Direct printing of organic single crystal nanowire arrays by using Liquid-bridge-mediated nanotransfer molding

  • Oh, Hyun-S.;Baek, Jang-Mi;Sung, Myung-M.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.473-473
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    • 2011
  • In recent years, organic thin film transistors OTFTs based on conductive-conjugated molecules have received significant attention. We report a fabrication of organic single crystal nanowires that made on Si substrates by liquid bridge-mediated nanotransfer molding (LB-nTM) with polyurethane acrylate (PUA) mold. LB-nTM is based on the direct transfer of various materials from a stamp to a substrate via a liquid bridge between them. In liquid bridge-transfer process, the liquid layer serves as an adhesion layer to provide good conformal contact and form covalent bonding between the organic single crystal nanowire and the Si substrate. Pentacene is the most promising organic semiconductors. However pentacene has insolubility in organic solvents so pentacene OTFTs can be achieved with vacuum evaporation system. However 6, 13-bis (triisopropylsilylethynyl) (TIPS) pentacene has high solubility in organic solvent that reported by Anthony et al. Furthermore, the substituted rings in TIPS-pentacene interrupt the herringbone packing, which leads to cofacial ${\pi}-{\pi}$ stacking. The patterned TIPS-Pentacene single crystal nanowires have been investigated by Atomic force microscopy (AFM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and electrical properties.

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Synthesis and physical properties of 2-(4-alkylcyclohexylphenyl)5-alkyl (fluoro)-1,3,2-dioxaborinane derivatives their use in liquid crystals

  • Lee, Jae-Ho;Park, Dae-Won;Kim, Jin-Ha;Kim, Yong-Bae
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.385-388
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    • 2005
  • 2-[4-(4-alkylcyclohexyl)-phenyl]-5-alkyl-(1,3,2)-dioxaborinane and Fluoro-substituted 1,3,2-dioxaborinane vatives were synthesized and their physical properties were measured. synthesized compound were showed nematic isotropic transition.

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Development and Applications of New Thermochromism Inks used Chiral Nematic Liquid Crystal-UV Curing Resin (키랄네마틱 液晶-UV경화형 수지를 이용한 새로운 온도변색성 잉크의 개발 및 응용)

  • 김준곤;남수용;구철회;윤종태;심성보
    • Journal of the Korean Graphic Arts Communication Society
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    • v.18 no.2
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    • pp.113-124
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    • 2000
  • It is well known that the characteristics of liquid crystal polymer composite(LCPC) films are possessed of large-area and flexible display, polarizer free, high contrast, wide angle of visual filed and high responsiveness. In this study, we have investigated to the best optimal mixing rates chiral nematic liquid crystals and UV-curable resins having different properties acrylate moleculars. The purpose of this study has been the development of new functional application with liquid crystal polymer composite films. For example the films were applied a new thermal sensor. In results, best phase separation behaviors turned out liquid crystal/monomer/oilgomer mixture system.

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Dielectric and Electro-Optical Properties of Ceramic Nanoparticles Doped Liquid Crystals

  • Porov, Preeti;Chandel, Vishal Singh;Manohar, Rajiv
    • Transactions on Electrical and Electronic Materials
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    • v.17 no.2
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    • pp.69-78
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    • 2016
  • Liquid crystals are important materials because of their applications in display technology and many other scientific applications. Different mixtures of liquid crystals and their doped samples have gained interest because a single liquid crystal compound cannot fulfill all the required parameters for the display application. The doping can be accomplished with dyes, polymers, or composite nanoparticles among other substance. The addition of nanoparticles can modify the physical properties of the host liquid crystal and enhances the performance of electro-optical devices. The present study is focused on investigations of possible changes in dielectric and electro optical properties of liquid crystals caused by doping with ceramic nanoparticles. Including smaller nanoparticles were found to be better candidates for use in suppressing the unwanted ion effects in liquid crystal displays.

Chain Length Dependence of Confined Liquid Crystals Configuration

  • Finotello, Daniele;Jin, Tao
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.256-259
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    • 2003
  • The study of confined liquid crystals flourished in the decade of the nineties. Liquid crystals properties have been probed after confinement in well-defined or interconnected geometries as those available in porous media and in polymer networks. In this work we emphasized the power of the nuclear magnetic resonance technique to determine the confined liquid crystal structures. We also present unexpected results on the dependence of the confined liquid crystal configuration on the chain length.

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Chain Length Dependence of Confined Liquid Crystals Configuration

  • Finotello, Daniele;Jin, Tao
    • Journal of Information Display
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    • v.4 no.1
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    • pp.14-16
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    • 2003
  • The study of confined liquid crystals flourished in the decade of the nineties. Liquid crystals properties have been probed after confinement in well-defined or interconnected geometries as those available in porous media and in polymer networks. In this work we emphasized the power of the nuclear magnetic resonance technique to determine the confined liquid crystal structures. We also present unexpected results on the dependence of the confined liquid crystal configuration on the chain length.

Vertical alignment of liquid crystal on $a-SiO_x$film by using $Ar^+$ beam

  • Son, Phil-Kook;Park, Jeung-Hun;Cha, Sung-Su;Kim, Jae-Chang;Yoon, Tae-Hoon
    • 한국정보디스플레이학회:학술대회논문집
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    • 2006.08a
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    • pp.818-821
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    • 2006
  • We demonstrate the vertical alignment of liquid crystal on $a-SiO_x$ film surface using the ion beam exposure. Liquid crystal can be aligned vertically by the rotational oblique evaporation of $a-SiO_x$ film. However, the electro-optic switching behavior of liquid crystal along random directions results in disclination lines. We found that we can achieve highly uniform alignment of liquid crystal without disclination lines by using the ion beam exposure. We found from XRD and XPS data that the vertical alignment can be achieved when x approaches 1.5 at the $a-SiO_x$ film surface. We have shown that the pretilt angle can be controlled by changing ion beam parameters, such as the ion beam energy, the angle of incidence, and the exposure time. We found that whether liquid crystals can be aligned vertically or homogeneously on $a-SiO_x$ film can be predicted simply by measuring the change in optical transmittance by deposition of $a-SiO_x$ thin film layers. We also have shown that a liquid crystal cell aligned vertically by the ion beam exposure exhibits the voltage-transmittance curve similar to that of a rubbed polyimide cell.

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