Electro-optical properties of high birefringence liquid crystal compounds with isothiocyanate and naphthyl group ^*

Abstract

Liquid crystal (LC) compound with isothiocyanate and naphthyl group is an attractive high birefringence LC material, and can be used in optical devices. In this paper, the electro-optical properties of a series of this type of LC compounds were investigated. The melting points and enthalpy values of these LC compounds were higher than those of corresponding compounds with the phenyl group. These compounds exhibited high birefringence with a maximum value of 0.66. Fluorine substitution in the molecular almost does not affect the birefringence value. When these LC compounds with the naphthyl group were dissolved in a commercial LC mixture, the electro-optical properties depending on temperature were investigated. In the low-temperature region, LC mixtures with the naphthyl-group LC compounds exhibited higher viscosity than pure commercial LCs. In the high-temperature region, viscosity values very closely approached each other. When response performance was investigated, figure-of-merit (FoM) values were measured. The FoM values of LC mixtures containing LC compounds with naphthyl group were lower than those of reference benzene LCs in the low-temperature region. However, in the high-temperature region, the results were reversed. These isothiocyanate LC compounds with naphthyl group can be applied in special fast-response LC device, particularly the ones used under high-temperature conditions.

A high birefringence liquid crystal for lenses with large aperture

“…Higher values (0.66) have also been demonstrated in LC compounds with isothiocyanate and naphthyl groups. The melting points and enthalpy values of these LC compounds were higher than those of corresponding compounds with the phenyl group 20 . Finally, ultrahigh birefringence has been demonstrated in some isothiocyanato biphenylbistolane compounds (0.7–0.8) 14 .…”

Comprehensive studies on dielectric properties of p-methoxy benzylidene p-decyl aniline with function of temperature and frequency in planar geometry: A potential nematic liquid crystal for display devices

“…It is found that the interaction becomes larger when the incident intensity increases at particular pretilt angle. Peng et al [17] studied the electro-optical properties of a series of LC compounds with isothiocyanate and naphthyl group for the application of optical devices. They have found that the enthalpy and birefringence values of these LC compounds are higher than those of corresponding compounds with the phenyl group.…”