Thin crystalline film retarders for LCD

Abstract

We have studied a new class of materials for LCD retarders produced by Cascade crystallization method. Advanced materials comprise the amphiphilic compounds and include salts of carboxylic and sulfonic acids with conjugated aromatic cores, which do not absorb light in visible range of light spectra. The Cascade crystallization method of manufacturing of the thin crystalline films (TCF) is based on printing from aqueous solution of lyotropic liquid crystal phase. We have produced and examined a series of retardation films that exhibit properties of negative A-plates. As compared to conventional retardation materials, new retardation films produced with the Cascade crystallization method are strikingly thinner (thickness range is 100 - 1000 nm), whereas birefringence is typically much higher (delta n varies from 0.05 to 0.40). Such a broad range of available thickness and retardation values makes feasible tailoring of LCD designs for customer needs. Viewing angle performance of the crossed polarizers is significantly improved in the presence of TCF retardation films, so that the light leakage at oblique incidence decreases several times. Formation of the new coatable stretchless retardation coatings by a roll-to-roll process can be easily incorporated into the techniques widely used in the LCD industry. The TCF retarders are aimed for LCD HTV application and open up opportunities for the manufacturing cost reduction.