Liquid Crystalline Blue Phases - Liquid Crystalline Functional Assemblies and Their Supramolecular Structures - page 99

Liquid Crystalline Blue Phases

Hirotsugu Kikuchi
Institute for Materials Chemistry and Engineering, Kyushu University,
6-1 Kasuga-Koen, 816-8580 Kasuga, Fukuoka, Japan
[e-mail]

1 I tr cti n ................................... 99

2 What are Blue Phases? ............................. 100

3 Discovery of Blue Phases ............................ 100

4 Simple and Double Twists ........................... 102

5 Structure of Blue Phases ............................ 105

6 New Materials Exhibiting Blue Phases .................... 108

7 Expanding the Stable Temperature Range of Blue Phases .......... 109

8 S ectic l e ase ............................... 111

9 Photonics of Blue Phases ............................ 114

10 Electro-optics of Blue Phases .......................... 114

11 Conclusions ................................... 116

References ....................................... 116

Abstract Blue phases are known to appear in chiral liquid crystals in a small tempera-
ture range between the chiral nematic phase and the isotropic one. They are optically
active, non-birefringent, and they show Bragg diffraction of light in the visible wave-
length, measuring several hundred nanometers. Their exotic structures and properties
result from the competition between chiral forces and packing topology. Recently, the
blue phases have attracted the attention in the field of optoelectronics and photonics. The
following article summarizes the basic properties, especially the frustration in the double
twist molecular alignment which is the origin of stabilization of the blue phase, and his-
tory of the blue phase studies, and describes significant advances that have been recently
reported.

Keywords Blue phase · Frustration · Double twist · Electrooptic effect · Photonic crystal

1
Introduction

“So, are they called 'blue phases' because they are blue?” This is a question
often asked by many. It is true that the naming might have originated from