Performance of Electrowetting Cell using Liquid Crystals

Abstract

Electrowetting (EW) is composed of non-polar oil and electrolyte in general, but we study using Chiral Nematic liquid crystal with polarity. The surface of the pixel surrounded by bank is covered with hydrophobic layer and the pixels of the EW-Cell are filled with oil and electrolyte. When voltage is applied, the oil deforms into a bow shape, the contact angle of the oil increases and the pixel opens. Pixels with different sizes were prepared and their EW-Cell characteristics (on/off states and threshold voltage for the on state) were studied, optimized EW-Cell was fabricated and optical characteristics were evaluated. When voltage was applied, EW-Cell showed a gentle increase after steep increase in pixel opening and a characteristic that Vth became higher as the smaller pixel size. And unclosed pixels might occur in large pixel size after voltage removal, which could be explained by calculation. In addition, the pixel design guideline was presented.