Liquid Crystal Mixtures with Low Birefringence for Active-Matrix LCD

Abstract

The liquid crystal (LC) mixtures with fused ring systems such as Decahydronaphthalenes and Tetrahydronaphthalenes for reflective or transflective active-matrix liquid crystal display (AM-LCD) have higher durability than LC mixtures with ester-components. These LC mixtures also have some problems such as low nematic-isotropic transition temperature TNI and high driving voltage. The improvement for driving voltage was carried out by using Tetrahydronaphthalene-component with moderate birefringence Δn and large dielectric anisotropy Δ˜. However, It was difficult to obtain LC mixtures with sufficiently low driving voltage, because of low TNI and the comparatively high Δn of tetrahydronaphthalene. We have improved these problems by introducing some newly developed LC components and optimization. We obtained the LC mixtures with low Δn and low driving voltage; less than 0.075 of Δn and about 4 V or less of driving voltage. These LC mixtures have high durability with stable nematic phase at low temperature.