Chromatic Properties of Dye Guest-Host Ferroelectric Liquid Crystals

Abstract

This paper describes the operation of a single polarizer for Dye Guest-Host Ferroelectric Liquid Crystals (DGHFLC). The electrooptical and chromatic properties have been studied for a FLC doped with two dichroic dyes in black and red coloration. The results shows that the increase of dye concentration improves the contrast ratio, color difference δE* and chroma C*_uv of the DGHFLC cell, but decrease lightness L* Therefore, a distinct difference location is observed on the chromaticity diagram of the coloured and colourless state while voltage is applied. For DGHFLC cell, the color difference δE* and contrast ratio continue to increase with the increase of applied voltage and reach saturation finally, but the threshold voltage almost remain the same as those of the FLC host. The rotational viscosity and response time of the mixture increase with the increase of dye concentration, especially at low temperatures. The response time of the DGHFLC cell also increases due to the increase of rotational viscosity of the FLC host. The increase of rotational viscosity leads to a good memory effect and an excellent bistable state.