We introduce a new group of organic materials and method for the three-step nano-film crystallization of these materials on the surface of glass or plastic. Materials are based on polycyclic aromatic compounds. Chemical modification of compounds changes hydrophobic-hydrophilic balance of disk-shaped molecules and makes them water-soluble with aggregation into rod-like supramolecules in aqueous solution and subsequent formation of supramolecular lyomesophases. Coating techniques provide control of crystallographic axes direction of the final crystal film. Shear force that is applied during deposition controls alignment of supramolecules. Structure of liquid material, wet coating and resulting 100-700 nm thin crystal films has been studied optically and by X-ray diffraction. The properties of the molecular material dictate the properties of Thin Crystal Film (TCF), which exhibit the layered molecular structure with interlayer distance equal to thickness of flat molecules (0.336 nm). Molecular alignment during the shear deposition of Lyotropic Liquid Crystal (LLC) results in formation of film with a strong preferred orientation. TCF order parameter determined from both X-ray analysis and optical data is about 0.9. TCFs exhibit a high optical anisotropy and birefringence which makes them unique nano-scale polarizing films and high efficiency retarders. New submicron film retarders have high refraction coefficient anisotropy. Birefringence varies from 0.3 to 1.0 for 380-900nm wavelength range. TCF polarizers and retarders provide new options for LCD designs.
New Thin Crystal Film (TCF) polarizers and retarders are produced by deposition of water based lyotropic liquid crystals formed by supramolecules of dichroic dyes. The supramolecules have an aspect ratio of more than 100 with a "spaghetti-like" structure. The supramolecules are formed by disk-shaped aromatic molecules that self-assemble into columnar stack (or strand-like) structures. In the course of deposition, shear force is applied and the supramolecules are aligned along the shear force direction in a wet layer about 10 microns thick. While drying, the layer of lyotropic liquid crystal phase-transitions into a sub-micron TCF functional layer with the dichroic dye molecules aligned in the same fashion over the entire coated surface. Layers of TCF can be deposited on a wide variety of materials including plastic and glass. The coatings exhibit properties of an E-type polarizer in wavebands where molecules exhibit absorption and birefringence up to 0.8 in areas of spectra where absorption is minimal. Several types of TCF polarizers and retarders have been produced and tested in order to improve the performance of LCDs. These films enhance the contrast, viewing angle performance and color rendering of many types of LCDs.
We developed algorithms and full-vector mode solver as a tool for new optical components design that allows simulation of components with anisotropic optical characteristics. Algorithms are developed without assumption of weak guidance, which allows applications of the method and software in simulation of components with strong optical anisotropy. Method and software were tested by comparison with semi-analytical solutions for isotropic and anisotropic fibers. We observed reasonably good agreement (up to five non-zero digits in the effective indices) between calculated and analytical data for several low order modes. In this paper we present results of calculations for single polarization D-shaped and cylindrical fibers with anisotropic coating.
New LCD cell structure includes plastic or glass substrates with ITO layers, Thin Crystal Film (TCF) polarizers coated on the ITO and a polyamide alignment layer on the top of the TCF. The TCF polarizer is molecularly oriented nano-film with the thickness in the range 60-600nm made by crystallization from lyotropic liquid crystals. First samples produced by Tecdis have demonstrated acceptable optical performance with superior viewing cone characteristics and thickness determined by the thickness of the plastic or glass walls plus 7 microns optical management path. Birefringence of the cell wall material is now not relevant to functionality of the display. It allows manufacturing plastic LCD's with robust environmental characteristics by using high temperature stable and birefringent inexpensive plastic.
We developed new production method for thin (0.3 - 1.0 micron) crystalline film (TCF) coating. Method comprises three steps: first, deposition of solvent based liquid crystalline ink on the surface in thin (10 micron) layer, second, orientation of the liquid by laminar shear flow in desirable direction, drying/crystallization of the laser into submicron thin solid crystalline layer. Final solid crystalline layer can be chemically modified. TCF has properties that defined by properties of molecular materials that are used for liquid crystalline ink. Liquid crystalline ink is ordered media with highly none-linear dependence of viscosity upon shear stress. Application of stress produces orientation of liquid crystal and high viscosity preserves order in drying process. hear flow direction determines the direction of crystallographic axes in crystal thin film. Film has monoclinic symmetry with relatively high defect concentration. Flat molecules of aromatic organic dyes are packed in layered crystalline structure with flat plane oriented perpendicular to the surface of the substrate. In present paper we describe properties of TCF with anisotropy of absorption and birefringence. TCF is highly optically anisotropic film with refraction coefficient difference between ordinary and extraordinary directions up to (Delta) n equals 0.8 in the visible spectrum and (Delta) n equals 0.3 at 1550 nm. Dichroic dyes with narrow band absorption in different areas of UV, visible and IR spectra allow to produce polarizers and retarders with new color band design flexibility.