Ferroelectric liq. crystal medium - has 3-component achiral base and chiral dopant and use in electro=optical device esp. switch or LCD with fast switching and good tilt

摘要

Ferroelectric liquid crystal (LC) medium (I), with improved tilt angle and a phase sequence including isotropic, cholesteric, smectic A and chiral smectic C phases, consists of an achiral base material (II) with a wide smectic C phase and chiral dopant(s) (III), which induces a spontaneous polarisation of 15-40 nC/cm2 in (II). The novelty is that (II) contains 3 components, A, B and C, which are (A) 4-(5-18C alkyl- or alkoxy)- phenyl 4-(5-18C alkyl- or alkoxy)- 2,3-difluorobenzoate(s) (IV) and/or 4-(5-18C alkyl- or alkoxy)- 2,3-difluorophenyl 4-(5-18C alkyl- or alkoxy)-benzoate(s) (V); (B) 4-(5-18C alkyl- or alkoxy)-phenyl 4-(5-18C alkyl- or alkoxy-benzoate(s) (VI); and (C) 4-(5-18C alkyl- or alkoxy)-3-fluorophenyl 4-(5-18C alkyl- or alkoxy)-benzoate(s) (VII) of the formulae (IV)-(VII), where R1-R8 are 5-18C alkyl or alkoxy. USE - (I) is used as ferroelectric medium in electro-optical devices and LC medium in electro-optical switches and LCD's (claimed).