• Title/Summary/Keyword: Self Assembled Monolayers

Search Result 221, Processing Time 0.031 seconds

Liquid crystal alignment on rubbed self-assembled monolayers with fluorinated alkyl chain

  • Oh, Chan-Woo;Hwang, Seok-Gon;Park, Sang-Geon;Park, Hong-Gyu
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
    • /
    • v.11 no.6
    • /
    • pp.671-677
    • /
    • 2018

  • In this paper, we investigated the vertical alignment characteristics of liquid crystals (LCs) on fluorinated self-assembled monolayers (FSAMs). For comparison, a commercialized homeotropic polyimide (PI) layer was used as an LC alignment layer. We confirmed the successful deposition of FSAMs and the change of FSAMs before and after rubbing treatment through contact angle measurement and atomic force microscopy. The optical transmittance spectrum of the FSAMs is similar to that of the homeotropic PI layer, which is a superior optical characteristic applicable to LC devices. When FSAMs were applied to the vertically aligned (VA) LC cell, uniform and vertical LC alignments were achieved. In addition, the voltage-transmittance characteristic of VA LC cell with FSAMs was superior to that of VA LC cell with the conventional homeotropic PI layers. These results indicate that the FSAMs are suitable as the homeotropic LC alignment layer for enhanced LC devices.

  • https://doi.org/10.17661/jkiiect.2018.11.6.671 인용 PDF KSCI HTML

Surface-Enhanced Raman Spectroscopic Studies of Oriented Monolayers on Electrode Surfaces

  • Yoon, Wan-Shik;Im, Jung-Hyuk;Kim, Jae-Ho
    • Analytical Science and Technology
    • /
    • v.8 no.4
    • /
    • pp.699-705
    • /
    • 1995

  • Monolayers of hypericin, a photodynamic polycyclic quinoidal compound, were prepared at the air-water interface, and were transferred to metal substrates to form Langmuir-Blodgett (LB) monolayers. The structural characteristics of hypericin LB monolayers and self-assembled (SA) monolayers were investigated using surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Both the spectroscopic data and the surface pressure - area (${\pi}-A$) isotherms suggest that hypericin forms ${\pi}-{\pi}$ aggregates that orient vertically to the subphase surface. Whereas the ordering and orientation of control was less effective in SA monolayers, a higher structural regularity was attained in LB systems. The effect of subphase on the structural integrity of the monolayer was also investigated.

  • PDF

Fabrication of Graphene p-n Junction Field Effect Transistors on Patterned Self-Assembled Monolayers/Substrate

  • Cho, Jumi;Jung, Daesung;Kim, Yooseok;Song, Wooseok;Adhikari, Prashanta Dhoj;An, Ki-Seok;Park, Chong-Yun
    • Applied Science and Convergence Technology
    • /
    • v.24 no.3
    • /
    • pp.53-59
    • /
    • 2015

  • The field-effect transistors (FETs) with a graphene-based p-n junction channel were fabricated using the patterned self-assembled monolayers (SAMs). The self-assembled 3-aminopropyltriethoxysilane (APTES) monolayer deposited on $SiO_2$/Si substrate was patterned by hydrogen plasma using selective coating poly-methylmethacrylate (PMMA) as mask. The APTES-SAMS on the $SiO_2$ surface were patterned using selective coating of PMMA. The APTES-SAMs of the region uncovered with PMMA was removed by hydrogen plasma. The graphene synthesized by thermal chemical vapor deposition was transferred onto the patterned APTES-SAM/$SiO_2$ substrate. Both p-type and n-type graphene on the patterned SAM/$SiO_2$ substrate were fabricated. The graphene-based p-n junction was studied using Raman spectroscopy and X-ray photoelectron spectroscopy. To implement low voltage operation device, via ionic liquid ($BmimPF_6$) gate dielectric material, graphene-based p-n junction field effect transistors was fabricated, showing two significant separated Dirac points as a signature for formation of a p-n junction in the graphene channel.

  • https://doi.org/10.5757/ASCT.2015.24.3.53 인용 PDF KSCI

Liquid crystal alignment on rubbed self-assembled monolayers according to alkyl chain length (알킬 사슬 길이에 따른 러빙 처리된 자기 조립 단분자막의 액정 배향 연구)

  • Park, Hong-Gyu;Park, Mu-Hun
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
    • /
    • v.14 no.5
    • /
    • pp.362-368
    • /
    • 2021

  • A homeotropic liquid crystal (LC) alignment state on rubbed fluorinated self-assembled monolayers (FSAMs) is described according to alkyl chain length. A simple procedure, gas-phase method, for the preparation of FSAM was used. The average optical transmittance in the visible light range of FSAMs were 76.63% to 78.21%, which were superior to the conventional polyimide layer having a transmittance of 75.89%. In addition, the excellent homeotropic LC alignment characteristics of FSAMs were observed through pretilt angle measurement and polarized optical microscope images. By measuring the contact angles and the surface energies of FSAMs, it was confirmed that pretilt angles of LC molecules increased according to the alkyl chain length. High optical transparency and uniform homeotropic LC alignment characteristics of FSAMs showed the possibility of FSAMs as an LC alignment layers.

  • https://doi.org/10.17661/jkiiect.2021.14.5.362 인용 PDF KSCI