New Liquid Crystal Materials; Physical Properties and Performance in Displays for Automobile, High Information Density and Guest-host Applications

Abstract

Four novel liquid crystal classes are presented, namely bi-, tri-, and tetracyclic ethanes, pyridazines, and tetracyclic chloro-diesters. Each class exhibits distinct physical characteristics, such as low viscosities η − 12 cP, low elastic ratios k₃₃/k₁₁ ∼ 1, large mesomorphic ranges −40°C. 250°C, large negative dielectric anisotropies δ ε − 9 and/or low dielectric relaxation frequencies f _e ∼ 1 kHz. It is shown that the dielectric Debye relaxation time τ characterizing the hindered rotation of polar nematic molecules around their short axes is much more affected by molecular structural factors than by their rotational viscosity γ₁. The material and electro-optical properties of mixtures for twisted nematic and guest-host LCDs comprising the new compounds are presented. The mixtures cover a wide range of applications such as high contrast, fast and multiplexable automotive TN-LCDs; positive and negative contrast guest-host LCDs; high-information density matrix, and dual-frequency addressable LCDs.