Date

6-2014

Degree Name

BS in Physics

Department

Physics Department

Advisor(s)

Karl Saunders

Abstract

Chiral, smectic liquid crystal molecules align in layers and can be controlled by the application of an electric field, yielding a variety of implications for the quality of liquid crystal (LC) displays. Both the bulk electroclinic effect (BECE) and surface electroclinic effect (SECE) impact the angle at which the molecules tilt with respect to the layer normal in different areas of a LC cell due to dipole interactions. Certain LC’s exhibit a continuous Sm-A* to Sm-C* transition, where the angles of the surface and bulk molecules change continuously with electric field strength. Other LC’s exhibit first order transitions where we see jumps in the tilt magnitude and hysteresis at different values of the applied electric field. The difference in angle of the bulk and surface molecules in both of these situations causes discrepancies in the layer spacing within the LC cell. These discrepancies lead to frustrations within the cell that can be quantified by strain. These frustrations can be relieved in a number of ways, however the method of relief may lead to negative impacts on the alignment quality of the display itself. Here, we first investigate the BECE and SECE separately and then later consider the effects simultaneously. We then present qualitative representations of this phenomenon and aim to explain significant decreases in alignment quality seen experimentally for particular values of applied electric field.

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