Structural and chemical characterization of fluorinated amorphous carbon films (a-C:F) as a liquid crystal alignment layer

Han Jin Ahn, Jong Bok Kim, Byoung Har Hwang, Hong Koo Baik, Jin Seol Park, Daeseung Kang

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

a-C:F thin films with varying fluorine content were prepared by plasma CVD and the sputtering method as inorganic alignment layers for overcoming the disadvantages of conventional liquid crystal (LC) alignment layers. The material and structural properties were investigated by X-ray photoelectron spectroscopy, Fourier transform infrared absorption, and contact angle measurement. For elucidation of the liquid crystal alignment layers, LC cells with a-C:F films were fabricated, followed by examination of the textures of the LC and electro-optical characteristics. The fluorine concentrations of a-C:F films were controlled by changing the mixture gas ratio (RG) in CVD and applied power ratio (RP) in the sputter system. An increase in RG and RP led to increase fluorine incorporation, and the film microstructure changed from a diamond-like to a polymer-like structure. In addition, the sputtered a-C:F films showed a higher fluorination than the CVD sample since the PTFE target was only composed of CF2 functional groups. Surface composition influenced the surface energy of thin films and an extremely hydrophobic property was obtained in the case of fluorine-rich a-C:F films. LC orientations were observed in various compositions of a-C:F films, and the vertically self-aligned LC textures confirmed that a sputtered a-C:F film is a good candidate for an alignment layer without any post-treatment.

Original languageEnglish
Pages (from-to)2019-2024
Number of pages6
JournalDiamond and Related Materials
Volume17
Issue number12
DOIs
Publication statusPublished - 2008 Dec 1

Fingerprint

Liquid Crystals
Carbon films
Amorphous carbon
Amorphous films
Liquid crystals
Fluorine
Chemical vapor deposition
Textures
Plasma CVD
Thin films
Fluorination
Diamond
Polytetrafluoroethylene
Infrared absorption
Angle measurement
Polytetrafluoroethylenes
Interfacial energy
Gas mixtures
Surface structure
Crystal orientation

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Chemistry(all)
  • Mechanical Engineering
  • Materials Chemistry
  • Electrical and Electronic Engineering

Cite this

Ahn, Han Jin ; Kim, Jong Bok ; Hwang, Byoung Har ; Baik, Hong Koo ; Park, Jin Seol ; Kang, Daeseung. / Structural and chemical characterization of fluorinated amorphous carbon films (a-C:F) as a liquid crystal alignment layer. In: Diamond and Related Materials. 2008 ; Vol. 17, No. 12. pp. 2019-2024.
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Structural and chemical characterization of fluorinated amorphous carbon films (a-C:F) as a liquid crystal alignment layer. / Ahn, Han Jin; Kim, Jong Bok; Hwang, Byoung Har; Baik, Hong Koo; Park, Jin Seol; Kang, Daeseung.

In: Diamond and Related Materials, Vol. 17, No. 12, 01.12.2008, p. 2019-2024.

Research output: Contribution to journalArticle

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