Investigation of applicability of some amino and chloro antraquinone structured dyes in G-H liquid crystal displays

Importance of liquid crystals used in display technology has been accelerately increased by technological developments in recents years. Wide viewing angle, low cost, excellent color, clear image characteristics and especially high performance of Guest-Host (G-H) system of liquid crystals have attracted intensive interests of researchers. Selection of dye that can be adapted to the liquid crystal is important in G-H systems.The aim of this study is to provide molecular orientation in G-H systems using chloro and amino antraquinone based dyes. Firstly, solubilities of five different dyes (2-chloro-; 1,5 and 1,8-dichloro-; 1,2 and 2,6-diaminoantraquinone) in liquid crystal E63 were determined. Later, order parameters of liquid crystal-dye solutions prepared according to their solubility characteristics were determined spectrophotometrically. Finally, phase transition temperatures were determined and texture were observed.As a result of comparison of order parameters of dyes, it was found that 1,8-DKA dye has the highest order parameter value (S=0,86) beside of its low solubility. It was concluded that type, number of position of functional groups placed in dye stucture were efficient on obtained results. Additionally, polarized microscope results demonstrated that no dye showed negative effect on temperature range of nematic phase.