Chiral Liquid Crystals (CLCs) can selectively reflect light of a specific wavelength when the period of its helically twisted structure is appropriately chosen and white light propagates along the helical axis. This phenomenon makes CLCs attractive for reflective-color display, without the needs of backlighting, polarizers, or color filters. Polymer Dispersed Chiral Liquid Crystals (PDCLC) have been developed for reflective switchable, bistable color display. However they suffer from high external driving voltage, low reflectivity, and high cost in pretreatment of the substrates. The key to solve these problems is to understand and control the anchoring behavior of CLC at a polymer surface. This research has two purposes: to develop PDCLC films with high reflectivity and to investigate the factors affecting the anchoring behavior of CLC at the polymer surface of the film. Specifically, commercially available chiral dopant and nematic liquid crystals were carefully chosen to formulate the CLCs reflecting different color. These CLCs are mixed with various acrylate and methacrylate monomers respectively, and UV cured at varied conditions to obtain PDCLC films. The anchoring behavior of these films is characterized using polarized optical microscopy, confocal microscopy, and microscopic-spectrophotometer. The factors influencing the anchoring behavior include chemical structure of the monomers, effective diameter of individual cells in PDCLC, thickness of individual cells in PDCLC, and the pitch of CLC, among which the chemical structure of the monomers is the most important. The PDCLC film made with n-hexyl methacrylate is found to selectively reflect light with the reflectivity larger than that of pure CLC with the same pitch.

Perylene-based materials, including charge-transport discotic liquid crystals and charge-transfer long-wavelength absorbing chromophores, for potential organic electronic and optoelectronic applications, were designed, synthesized and characterized. Two types of discotic liquid crystals, perylene diimides and coronene diimides, can form columnar liquid crystalline phases over a wide temperature range; many of them can have room-temperature liquid crystalline phases after cooling from isotropic liquid. Their charge transport properties were studied by space-charge limited current method; high charge carrier mobilities, with the highest being up to 6.6 cm2/Vs, were found in liquid crystalline phases of these materials under ambient conditions. Structural variables, including aromatic cores and side groups, were examined to get a certain degree of understanding of charge transport properties in these discotic liquid crystals. It was found that mesophase order can have an important effect on charge carrier mobilities. The discotic liquid crystals with high charge carrier mobilities are serious candidates for use in large-area low-cost applications such as solar cells. Long-wavelength, highly absorbing chromophores, featuring donor-substituted perylene diimides, were generated by a combination of charge-transfer process and conjugation extension. The charge-transfer chromophores are expected to lead to further investigation on their potentials as sensitizers in Grtzel solar cells.

Chemical vapor deposition technology is often by using in the one of Wafer panel Foundry process, the heat transfer coefficient on the top substrate surface is the very important influence parameter in the manufacturing process. For this reason, the main object of this thesis is apply liquid crystals heat transfer measurement technique to set up a temperature measurement experiment system of transient thermochromatic liquid crystals and application simulating CVD process technique. Furthermore, an experimental is carried out in the present study to investigate the characteristics of heat transfer experiment study analysis resulting from a low speed air jet through the nozzle eccentric disc outlet impinging onto a rectangular acclivitous angles substrate confined in a vertical rectangular chamber. Finally, heat transfer coefficient empirical equations of the three relationship are proposed to Nusselt number correlate the effect of Reynolds number¡BSeparation distances are Ratio of outlet and acclivitous substrate surface¡BAngles of rectangular acclivitous substrate.

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Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [89]-102).

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High birefringence (Δn > 0.4) nematic liquid crystals are particularly attractive for infrared applications because they enable a thinner cell gap to be used for achieving fast response time and improved diffraction efficiency. In this thesis, the mesomorphic and electro‐optic properties of several new fluorinated isothiocyanate (NCS) terphenyl and phenyl tolane single compounds and mixtures are reported. The single compounds demonstrated Δn~0.35‐0.52 in the visible spectral region at room temperature and exhibit relatively low viscosity. It was found that lateral fluorine substitutions and short alkyl chains eliminate smectic phase and lower the melting temperature of the single compounds. However, the consequence of using highly conjugated compounds to improve electro‐optic properties is that the nematic phase is exhibited at high temperatures, over 100°C, and therefore single compounds cannot be used for device applications. Therefore, several mixtures based on the terphenyl and phenyl‐tolane compounds were formulated and evaluated. The purpose of mixtures is to find the optimum balance between electro‐optic performance and the mesomorphic properties that determine the operating temperature range. It was found that mixture formulations greatly improved mesomorphic properties to produce nematic phase at or near room temperature and suppressed smectic phase to below 0°C or eliminating completely. The analysis presented evaluates the benefits of lowering the operating temperature versus the consequence of degrading the electro‐optic properties.

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