Effect of liquid conductivity on optical and electric performances of the electrowetting display system with a thick dielectric layer

Abstract

The effect of liquid conductivity on both the optical and electric performances of the electrowetting display system with a thick fluoropolymer insulating layer was investigated in this study. Low-conductivity deionized water and aqueous ionic solutions with different conductivities were used as the conducting liquids and tested in both the open electrowetting systems and the electrowetting display devices. The sessile droplet test was used to study the electrowetting performance of liquid droplets with different conductivities on fluoropolymer coated electrode and an experimental platform was designed to measure the leakage current of the liquid/fluoropolymer/electrode contact. 2.7-inch EWD specimens were also prepared for the experiments. The on-switching response time, the maximum aperture ratio of pixels and the current-voltage characteristic on device level were studied experimentally. We focused on the influence of liquid conductivity on the optical performance of the electrowetting displays. The test showed that, with deionized water, the leakage current value of the EWD cell was lower than 10 nA/cm2 at 30 V, while the average on-switching time and maximum aperture ratio water were 37.8 ms and 46.7%, respectively. The using of low-conductivity water as conducting liquid in electrowetting displays with a thick fluoropolymer insulating layer was discussed.