Dielectric and Electro-Optical Characterization of Dyed Ferroelectric Liquid Crystals

Abstract

The ferroelectric liquid crystal displays normally suffers from less contrast ratio and vision angle. To produce high optical contrast and colours in FLC displays, Guest-host mode is widely used. Addition of small amount of dichroic dye in pure FLCs results in considerable change in its dielectric and electro-optical properties. In the present paper we have investigated the effect of two dichroic Anthraquinone dyes (D37 and D5) on the ferroelectric liquid crystal materials (Felix 17/100). Dye doped FLC mixtures have been prepared by the dispersion of each dye at five different concentrations about 1, 2, 3, 4 and 5%wt/wt in pure FLC. The planar aligned cells have been used to study dielectric and electro-optical properties in SmC* phase of all pure and the dye doped mixtures. Considerable change in various properties like Goldstone mode relaxation frequency and dielectric strength have been noticed for both the sets of dye doped mixtures. These effects have been discussed in the light of changes produced in the different material parameters like spontaneous polarization, rotational viscosity and tilt angle.

Keywords:

• dielectric properties etc.
• ferroelectric liquid crystals
• guest–host mode

Acknowledgments

The authors are sincerely thankful to DST, New Delhi for the financial assistance in the form of project for the present work.