Novel photo-vertical alignment materials for low pre-tilt angle and low-temperature cure process application

Abstract

Photo-alignment materials are widely used for liquid crystal displays (LCDs) due to dustless and easy to realize fine patternings. In 2009, the Sharp UV2A (Ultra violet induced multi-domain Vertical Alignment) technology was applied to LCDs for the first time in the world. In order to commercialize ultra-high definition displays such as 8K in UV2A display, there are two challenges in photo-vertical alignment materials. The first is lowering pre-tilt angle for improvement of panel transmittance, and the second is application of low temperature cure process with NMP-less alignment materials for wide color gamut. While The transmittance of 8K displays is much lower than full-high definition or 4K because the ratio of disclination region (dark line) and black matrix increases as the pixel size decreases, the low pre-tilt angle property enables to narrow dark line width. The low temperature cure process with NMP-less alignment material may realize to apply high performance color filter (CF) materials (e.g.: dye-based CFs). In this paper, we developed novel low pre-tilt angle material (New-AL) with excellent propeties of alternating current image sticking and a wide range of pretilt angle between 84 degrees and 90 degrees by polarized ultra-violet exposure dose. Furthermore, not only New-AL can be applied to low temperature cure process even at 120 °C, but also New-AL is prospective NMP-less material which enables to apply dye-based CFs due to better solubility than the conventional materials.