Screen-printing fabrication of electrowetting displays based on poly(imide siloxane) and polyimide

• Poly(imide siloxane) film demonstrated good electrowetting performance.
• Polyimide-based hydrophobic material (poly(imide siloxane)) and hydrophilic polyimide showed good compatibility.
• Hydrophilic polyimide grids could be directly built on the hydrophobic poly(imide siloxane) film by screen-printing.
• Cheaper materials and simpler fabrication method have been demonstrated for electrowetting displays.

We report a screen-printing fabrication process for large area electrowetting display (EWD) devices using polyimide-based materials. The poly(imide siloxane) was selected as hydrophobic insulator layer, and relatively hydrophilic polyimide as grids material. EWD devices that use poly(imide siloxane) as hydrophobic insulator fabricated with conventional methods showed good and reversible electrowetting performance on both single droplet level and device level, which showed its potential application in EWDs. The compatibility of polyimide-based materials (hydrophobic poly(imide siloxane) and hydrophilic polyimide) guarantee the good adhesion between two layers and the capability of printable fabrication. To this end, the hydrophilic grids have been successfully built on hydrophobic layer by screen-printing directly. The resulting EWD devices showed good switch performance and relatively high yield. Compared to conventional method, the polyimide-based materials and method offer the advantages of simple, cheap and fast fabrication, and are especially suitable for large area display fabrication.