Chiral materials and cell designs for the cholesteric display technology

The focus of this dissertation is to better understand liquid crystalline cholesteric materials and cell designs for the development of the low power reflective cholesteric liquid crystal display (ChLCD) technology. Deuterium nuclear magnetic resonance (d-NMR) studies are used to gain insight into the ordering of these materials. Specially designed deuterated chiral materials, the so called TADDOLs, with high helical twisting powers (HTPs), are used in this study. This investigation demonstrates the biaxial ordering of chiral materials through d-NMR in the cholesteric phase by measurements of a non-vanishing asymmetry parameter η, the time averaged quadrupole spin interaction. The uniaxial order parameter S_0,0, for the deuterated TADDOL is measured in an untwisted state as well. The biaxial order parameter S_2.0, is also measured for the deuterated TADDOL for different pitch lengths as a function of reduced temperature. However, S _2.2 could not be measured for the TADDOL due to an unfortunate choice of the deuteration site that is insensitive to rotational freeze-out.; The dissertation also focuses on advanced additive achiral and non-liquid crystalline materials and their effects on the optics, electro-optics, and dynamics of ChLCDs. The additives are shown to improve various optical and electro-optical properties of cholesteric materials at the expense of a small drop in the cholesteric-isotropic phase transition temperature. The dynamics of various texture transitions are also studied. A new technique to dramatically enhance the reflective brightness of ChLCDs is also presented. This brightness enhancement is accomplished by altering the aligning surfaces of the LCD cell. Minimal degradation in viewing angle is observed. Finally, careful examinations of the optics and electro-optics of advanced full color ChLCDs are presented. Various studies tying advanced liquid crystalline materials, dye materials, and chiral materials to addressing and temperature compensation schemes are presented. Work presented here is used in the development of the first high resolution full color ChLCD for commercial and military applications.; In conclusion, we present a comprehensive study of ChLCDs through investigations and experiments in materials, dynamics, optics, and electro-optics of cholesteric displays. Some of the designs and techniques presented here have been patented and are currently being used in industry worldwide for the improvement and advancement of the cholesteric liquid crystal display technology.