Liquid crystal medium for electro-optical displays with active matrix address based on the ECB effect contains 1,8-difluorophenanthrene compounds with substituents such as alkoxy groups at positions 2 and 7

摘要

A liquid crystal medium based on a mixture of polar compounds with negative dielectric anisotropy contains at least one 1,8-difluoro-phenanthrene compound with substituents at positions 2 and 7. A liquid crystal (LC) medium based on a mixture of polar compounds with negative dielectric anisotropy contains at least one compound of formula (I). R11, R12 = 1-15C alkyl or alkenyl (optionally substituted with one CN or CF3 group or with at least one halogen atom and optionally with one or more CH2 groups replaced by -O-, -S-, cyclobutane-1,3-diyl, -C equivalent to C-, -CO-, -COO-, -OCO- or -OCOO- but with no direct link between O atoms); L1, L2 = H or F; (A) = trans-1,4-cyclohexylene, 3,5-dioxolane-1,4-diyl, 1,4-cyclohex-3-enylene, 3-fluoro-1,4-cyclohex-3-enylene, 1,4-phenylene, 2- or 3-fluoro-1,4-phenylene or 2,3-difluoro-1,4-phenylene; Z' = -CF2O-, -OCF2-, -C equivalent to C-, -CF=CF-, -C2F4-, -COO-, -OCO- or a single bond; a = 0 or 1. An Independent claim is also included for electro-optical displays with active matrix address based on the ECB effect, containing the LC medium as dielectric.