47.2: A New Generation of LCD's Based on Ferroelectric Liquid Crystals Showing Uniform and Stable Orientation

Abstract

The object of the research is new ferroelectric liquid crystal (FLC) compositions with a wide temperature range of SmC* phase and the fabrication of a fast switching mechanically stable display with improved electro-optical properties. The aim of the work is to synthesize new highly viscous non-chiral compounds and to develop on their basis in combination with known ferroelectric compounds with a large value of spontaneous polarization of mixtures stable to mechanical deformations. As a result, the influence of the length of nonchiral molecules and the viscosity of the compositions on the mechanical stability of the alignment was investigated. The relationship between the surface anchoring energy of the alignment materials and the viscoelastic properties of ferroelectric liquid crystals is described. For our investigation we synthesized new non-chiral smectic C compounds containing four or five attached phenyl rings, so called 4,4'-di-substituted quaterphenyls 4,4'-di-substituted-pentaphenyls which have in series-connected benzene rings, but not separated by bridging fragments. We found that the switching of FLC mixtures with such compounds is much faster compared to mixtures containing compounds with the same quaterphenyl or pentaphenyl fragment in chiral molecules. New ferroelectric liquid crystal compositions with optimized parameters have been designed. The possibility to develop FLC displays with switching time less than 10 μs and stable against mechanical deformations and independent of the type of alignment material and pretilt angle was shown.