Antiferroelectric liquid crystals with 45° tilt: new electro-optic effects in liquid crystals

Abstract

Antiferroelectric liquid crystal materials are very promising for high-resolution displays but so far suffer from two serious problems, both of which reduce the achievable contrast. These materials are first of all very hard to align to a high quality dark state. Most often this has been attributed to the fact that antiferroelectric materials lack a nematic phase. We believe, however, that there are other reasons behind the bad dark state as well, and that these reasons may be even more important. In addition antiferroelectric materials show a thresholdless linear electro-optic effect, conventionally called the 'pretransitional effect,' which gives a dynamic contribution to light leakage under addressing conditions. We have synthesized and now describe a new type of antiferroelectric material which gives an unprecedented black state due to a high static extinction as well as to the absence of a pretransitional effect. The performance of conventional antiferroelectric liquid crystal displays will be considerably enhanced with this kind of material. Among the numerous non- conventional electro-optic applications of the new material several polarizer-free display modes are described together with fast photonic modulation devices.