Molecular Orientations and Electro-optic Properties of Ferroelectric Liquid Crystal Cells with SiO2 Films

Homogeneous alignments and electro-optic properties for ferroelectric liquid crystals are investigated. A glass substrate is coated with either SiO2 or SiO2:P doped phosphorus for the aligning film. Thealigning film on the surface of the substrate is formed by either a spinning or a dipping methods. Aligning characteristics areexamined by measurements of (1) the light transmission of the cell rotation through a cell placed between cross nicols attached to a Polarization microscope, (Ⅱ) the capacitance and DC bias voltage (C-V) relation, and (Ⅲ) the light transmittance and DC bias voltage (T-V) relation. Here, the bias voltage under the applied DC voltage is changed on going and returnig from -6 to +6 V. The electric field characteristics and the response time in electrical switching are investigated by applying a square waveform voltage (500 Hz) to the cells. Experimental results showed that the cell characteristics of the dipping method were superior to those of the spinning method in the contrast ratio by the light transmittance, the molecular alignment, and the response time. The preparation of the dipping film was easy to prepare as compared with the spinning film