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Title: Azo dye materials for the alignment of liquid crystal
Authors: Yip, W. C.
Prudnikova, Elena K.
Kozenkov, Vladimir M.
Chigrinov, Vladimir G.
Kwok, Hoi-Sing
Keywords: Photo-induced alignment
Azo dye film
Liquid crystal display (LCD)
Twist nematic (TN) LCD
Issue Date: 2001
Citation: Society for Information Display International Symposium Digest of Technical Papers, v. 32, 2001, p. 1170-1173
Abstract: In this paper, the photo-induced alignment of liquid crystal on an azo dye film is discussed for the liquid crystal display (LCD) applications. This is a non-contact technique to align the liquid crystals so that the dust particles and static charges generated by the rubbing process can be eliminated. To prepare for the photo-alignment layer, the azo dye film is exposed to a linearly polarized or non-polarized light. As a result of the dipole absorption, the photo-induced molecular distribution is non-uniform and has an angular dependence. Consequently, since the dispersion forces between the dye and the liquid crystal molecules dominate, the induced orientation of the liquid crystal molecules is possible. The oblique incidence of the light exposure will also favour a non-zero pretilt angle. We find that the order parameter associated with the aligned liquid crystal medium is high, and very good contrast has been measured in the Twist Nematic (TN) LCD.
Rights: This paper is made available with permission of the Society for Information Display. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
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