The electro-optical characteristics of liquid crystal device in multi-component liquid crystal mixture system with non-contact photo-induced vertical alignment mode

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• 作者：Fa-Hsin Lin ; Czung-Yu Ho ; ^{ketcer2011@gmail.com} ; Jiunn-Yih Lee ^{jlee@mail.ntust.edu.tw}
• 关键词：Liquid crystal ; Negative dielectric anisotropy ; Pre-polymer ; Copolymer film ; Homeotropic texture ; Electro-optical properties
• 刊名：Optical Materials
• 出版年：2012
• 出版时间：May, 2012
• 年：2012
• 卷：34
• 期：7
• 页码：1181-1194
• 全文大小：2520 K

文摘

In previous studies, we mixed photo-curable acrylic pre-polymer into negative dielectric anisotropy nematic type liquid crystal (N-type LC, NLC) to obtain a NLC/photo-curable acrylic pre-polymer mixture solution (NLC mixture system). After irradiation with UV light of fixed intensity, we successfully fabricated copolymer films with vertical alignment effect among the LC molecules. In this study, we propose a new type of multi-component LC mixture system by mixing chiral smectic type (SmA^*) LC with homeotropic texture into NLC/photo-curable acrylic pre-polymer mixture system (NSLC mixture system). Our experimental results revealed that this SmA^* LC exhibited the vertical alignment effect associated with LC molecules in the auxiliary LC mixture system. Moreover, we also discovered that altering the main chain type biphenol acrylic pre-polymer had drastic impact on the contrast ratio (CR) of the LC mixture system, with an increase of as much as 73 % . More importantly, adding the SmA^* LC can evidently increase the anchoring energy of the alignment film surface. We also further performed measurements, analyses, and discussions of electro-optical properties of devices fabricated from the new LC mixture systems.