Inhibiting Oil Overflow in Electrowetting Display through Selectively Hydrophilic Modification of the Pixel Wall Based on Polydopamine and Polydopamine/Polyvinylpyrrolidone via Regional Protection Strategy

Abstract Due to the advantages of low power consumption, visual health, flexibility, and the potential of color dynamics, Electrowetting Display (EWD) has obtained rapid development in recent decades. One issue that affects the display effect and the lifetime of EWD devices is the overflow of oil across the pixel wall when a high electric field is applied. This paper adopts a method through selectively hydrophilic modification of the pixel wall based on dopamine self‐polymerization via a regional protection strategy by liquid. The static contact angle decreases from 75.4° for the original surface to 48.8° for the modified surface. Due to the limited hydrophilicity of dopamine itself, it is difficult to further improve the surface hydrophilicity of the pixel wall. Taking polydopamine as the intermediate layer, the pixel wall is further modified with polyvinylpyrrolidone (PVP) through multiple hydrogen bonds. The results show that the static contact angle decreased from 48.8° to 29.2° again, resulting in a larger wettability gradient between the pixel wall and the hydrophobic area. In addition, the phenomenon of oil overflow is significantly prevented. When the EWD device is operated at a high voltage (60 V), no oil flows over the pixel wall.