A new generation of ferroelectric liquid crystals with homogeneous and shock-stable orientation

Abstract

ABSTRACT This research is focused on ferroelectric liquid crystal compositions with a wide temperature range of the SmC* phase and the design of mechanically stable, fast switching surface-stabilised ferroelectric liquid crystal display with improved electro-optical properties. The work involves the synthesis of high-viscosity achiral compounds and the creation of mixtures based on them that are resistant to mechanical shocks. For this reason, the viscosity of the compositions and the length of achiral molecules were investigated for their impact on mechanical stability of the alignment. For our investigation we synthesised new achiral 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 FLCs 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 optimised parameters have been devised. This work demonstrated that surface-stabilised ferroelectric liquid crystal display could be developed that had switching times less than 10 μs, was stable against mechanical deformations and was independent of alignment material and pre-tilt angle.