Current Topics in Smectic Liquid Crystal Research

Interest in the smectic liquid‐crystalline state of matter received a substantial boost with the discovery by Meyer in the mid‐1970s that a chiral smectic C (SmC*) phase exhibits a spontaneous electric polarization, and with the subsequent demonstration by Clark and Lagerwall of the surface‐stabilized SmC* ferroelectric liquid crystal at the beginning of the 1980s. Since then, chiral smectic phases and their plethora of polar effects have dominated the research in this field, which today has reached a mature state where the first commercial microdisplay applications are now shipping in millions‐per‐year quantities. In this Review we discuss some of the topics of highest interest in current smectic liquid crystal research, and address application‐relevant research (de Vries‐type tilting transitions without defect generation and high‐tilt antiferroelectric liquid crystals with perfect dark state) as well as more curiosity‐driven research (the nature and origin of the chiral smectic C subphases and their intermediate frustrated states between ferro‐ and antiferroelectricity). Liquid assets: Ferro‐ and antiferroelectric chiral smectics (see picture) constitute a class of liquid crystals (LCs) with large potential for electro‐optic devices. This Review gives a general introduction to the field and examines three topics in detail: materials with disorder–order phase transitions, which exhibit temperature‐independent smectic layer thickness (“de Vries” smectics), high director‐tilt antiferroelectric LCs, and the polymorphism at the borderline between syn‐ and antipolarity.