Investigation of applicability of nematic liquid crystals doped with disperse orange dye in guest-host systems

With recent improvements in technology, liquid crystals, which are considered as the basic structure material in screens, became a main topic of interest for many scientific investigations. In G-H (Guest-Host) liquid crystal display systems, dyes are used with liquid crystals and it is well known that dyes have very high efficiency on screens. Structures of dyes used and their concurrency with liquid crystals are very important because they affect the quality and the contrast of display, angle of sight and acutance of color tones.In this study, applicability of one antraquinone dye and two azo dyes in liquid crystal systems are investigated. Thus, this study includes the determination of the solubility of dispers orange 11, 13, 37 dyes in E63 liquid crystal; the calculation of order parameters of liquid crystal-dye mixtures, which have been prepared with known solubility rate, by using a UV spectrophotometer and the investigation of the texture of pure liquid crystal and mixtures under polarized microscope.As a result of the investigations conducted within this context, solubility rates of DO-11, DO-13 and DO-37 dyes are determined as 0,49%, %1,92, %0,23 (w/w) respectively. By basing on these parameters, 0,2% dye solutions for three dyes and an additional 1% dye solution for DO-13 which has higher solubility rate, have been prepared and order parameter values have been determined. The maximal value has been obtained as 0,79 for DO-37 dye. Solvatochromic behaviors of liquid crystal mixtures has been observed. When the textures of the samples have been examined, it has been found that dyes increase the liquid crystal phase transition temperature except for DO-13.Keywords : Nematic liquid crystal, order parameter, texture, dispers dye, guest-host type systems, phase transition