Thin crystal film polarizers and retarders

Abstract

We developed a new technology for thin crystal film (TCF) manufacturing based on water-soluble salts of aromatic polycyclic compounds. TCF is produced by coating and subsequent drying of an aqueous solution on plastic or glass surface into molecularly oriented 100-1000 nm thick crystal nano-film. First industrial application of nano-films is TCF polarizer for liquid crystal displays (LCD). TCF polarizers are made from modified organic dyes with relatively narrow spectral absorption band. Mixing various dyes allows covering broad spectral region. Blending provides variety of combinations of background and character colors that are necessary for applications. TCF made from dichroic dyes are highly anisotropic, biaxial extraordinary polarizers. Birefringence of TCF made from some materials reaches 1.0. Several highly birefringent TCFs show specific retardation characteristics. For example, 300 nm thick TCF based on dichroic dye with narrow absorption band at 450 nm and transparent in the long-wave region, has maximum birefringence of 0.85 in the wavelength region of 500-800 nm. TCF are available for industrial application in LCD as external, internal polarizers and retarders.

Aggregation Behavior and Chromonic Liquid Crystal Phase of a Dye Derived from Naphthalenecarboxylic Acid

“…This separation is similar to the distance between planes in graphite and base pairs in DNA. X-ray measurements on a more limited number of chromonic liquid crystals have revealed that the stacking is columnar, with a cross-sectional area approximately equal to the area of a single molecule ,, or larger than the area of a single molecule. , Investigations into the nature of the aggregation process are extremely few in number. The behavior of the disodium chromoglygate system was also examined through the addition of salt to the solution, revealing some general aspects of the aggregation process .…”

“…With this in mind, polarizing microscopy, X-ray measurements, and absorption spectroscopy similar to what was done with Sunset Yellow FCF were performed on a dye with a very different structure. While Sunset Yellow FCF has a benzene and napthalene ring linked by an azo group, Bordeaux dye possesses a much larger polyaromatic ring structure with no linking groups. The difference in molecular structure reveals itself in several ways.…”

P-98: Opto-mechanical Properties of Thin Film Crystal Polarizers Coated on Polymer Substrates

“…These TCF polarizers are comprised of lyotropic liquid crystals formed from dichroic dyes. They consist of diskshaped, water-soluble molecules of organic ionic compounds, which are oriented on the substrate by shear extensional flow during the coating process [2]. A Meyer rod is traversed over the liquid phase to coat the solution on the substrate, forming highly ordered columnar structures as shown in Figure 1 In all the tests, the sample was illuminated with the coated side facing the collimated white light source.…”

“…For several reasons, including ease of processing and mechanical robustness, polarizers designed for flexible displays must meet stringent requirements. Thin crystal film (TCF) polarizers under development have a strong potential to meet some (if not all) of flexible display requirements [2]. These polarizers are based on lyotropic, discotic liquid crystalline materials.…”

“…E-type polarizers are also known to exhibit low off-angle leakage [4] and enhanced viewing angle characteristics [5], making them attractive for a number of applications. These performance enhancements coupled with the sub-micrometer layer thickness [2], in-cell implementation [6], roll-coatable processing and thermal stability [7] of TCF polarizers make them ideal candidates for flexible displays. In addition to their usefulness in many display applications [8], two recently reported flexible display technologies have implemented these new polarizer alternatives.…”