Practical FLC Mixtures with Broad Temperature Ranges and Fast Switching Speeds

Abstract

We have formulated fast-switching ferroelectric liquid crystal mixtures which exhibit S_c* phase thermal stability. In addition, these mixtures have other material parameters optimized (i.e. tilt angle, birefringence, and pitch) so that they may be suitable for device applications. Typical S_c* phase ranges are approximately 60°C (e.g. 49° to – 10°C) and switching speeds are as fast as 37 μs (25°C, 15 V/μm). All of the liquid crystal components are chiral and all but one exhibits liquid crystalline behavior. The LC components contain optically active 2-methylbutyl, 1-methylpropyl, 1-methylhexyl, and other head groups, and they also contain tails with various combinations of oxyethylene moieties and fluorine atoms. The mesogenic cores comprise three phenyl rings interconnected via a single ester linkage (i.e. -Ph-Ph-CO₂-Ph-). In one case a core contains a single fluorine substituent on one of the aromatic rings. The non-mesogenic chiral component 4-[1-methyl-1-propoxycarbonyl]phenyl-[4′-methyl]benzoate was incorporated into each mixture in order to optimize the tilt angle.

• ferroelectric liquid crystal
• eutectic
• S_c* phase