Fluorinated polymer alignment layers formed at low temperature for plastic-substrate-based liquid crystal devices

In this paper, we describe an alignment layer of chemically and mechanically stable fluorinated polymer for light-weight flexible liquid crystal display devices. Since the fluorinated polymer can be formed on plastic substrates at room temperature, unlike conventional polyimide, thermal distortion of the substrate does not occur. Uniform 70-nm-thick polymer thin films were obtained by spin-coating using a hydrofluoroether solvent. The orientation of the liquid crystal molecules was perpendicular to the rubbing direction of the fluorinated polymer, and the anchoring strength of the rubbed polymer was approximately 10^-4 N/m. Twisted nematic liquid crystal devices using plastic substrates coated with the polymer showed good spatial uniformity and a high contrast ratio of more than 100 : 1.