Blue Phase Liquid Crystals

Investigation of chirality in liquid crystals is an exciting area of science of mesophases. Many frustrated phases are induced by chirality including the chiral nematic blue phases (N*BPs). Initially, they were observed in a very narrow temperature range in between the isotropic liquid phase and chiral nematic phase oh high chirality. However, in recent years their stability region was increased up to 220 0C by using newly developed methods. Three kinds of blue phases (BPs) occur: BPI, BPII and BPIII. The BPI and BPII possess cubic symmetry, whereas BPIII has amorphous symmetry. From the applications point of view BPLCs show evolutionary characteristic features: sub-millisecond gray-to-gray response time, alignment layer free process, optically isotropic dark state and insensitivity to cell gap. In this chapter 2, brief discussion on their characteristic features, overview of experimental work, phase diagrams, properties and how their behavior are influenced by the applied external fields and other parameters.