Effects of Low Viscosity Liquid on the Electro-Optical Properties of Inverse Twisted Nematic Liquid Crystal Display

The optimized electrooptical (EO) properties of inverse twisted nematic (ITN) liquid crystals (LCs) were demonstrated by utilizing liquid doping technique. ITN LC display is a driving system containing 90° twisted structure on homeotropic polyimide with negative dielectric anisotropic LCs. Toluene was chosen as dopant and the doped ITN LCs show improved driving voltage and response time while maintaining a very good dark state as undoped ITN LCs. Driving voltage was 1.1 V lower and the total response time was reduced by 49% after toluene doped into LCs. The main reason of these EO properties enhancement is that toluene molecules penetrate between LC molecules, and hence, the dielectric anisotropy and the visco-elastic coefficient of LCs are changed. The simplicity of liquid doping technique shows that it could be applied to a wide range of LC systems.