Molecular Alignment Control in Ferroelectric Liquid Crystal Cells by Combined Effects of Oblique Deposition and Electric Field Application in the Cooling Process

Abstract

A method of controlling molecular alignment in ferroelectric smectic liquid crystal (FLC) cells is described. It uses the combined effects of the following two steps of treatment : (1) oblique deposition of metal oxide, e. g., yttrium oxide, to the substrate surface, and (2) application of an electric field in the process of cooling from the isotropic liquid of the FLC to its chiral smectic C phase. With the combination of the deposition at 60° incidence and the application of a DC field with a strength of about 10MV/m in the cooling process, the FLC molecules are aligned to a uniform pretilt of about 50°. Smectic layers are inclined at 40°-50° to the electrode surface in this cell. When no electric field is applied in the cooling process, on the other hand, the pretilt angle of the molecules is about 15° and the smectic layers are nearly parallel to the substrate surface.