Solution-processed organic light-emitting diode in high-resolution line patterns by scalable wetting modification

We report a simple and cost-effective method of producing high-resolution line patterns of a solution-processed organic light-emitting diode (S-OLED) in the bank structures through the scalable wetting modification. The pattern resolution depends primarily on the subtle interplay between the geometric capillary action and the wetting property of the OLED solution. According to the Cassie-Baxter model, the air-pockets in the bank structures (BSs) on the substrate serve as the dewetting regions, repelling the hydrophilic solution, so that the nature of the BS surface should be precisely tuned for constructing high-resolution patterns. The wettability of the BS surface is predominantly modified by the amount of the functional group under ultraviolet ozone to achieve the Cassie penetrating wetting state which is rather hydrophilic. The OLED solution is then uniformly filled in the groove between two adjacent BSs to reach a feature size of 5 μm in line pattern. Our patterned S-OLED, fabricated using the scalable wettability modification, exhibits the good stability and uniformity without any degradation in electroluminescent performance in relative to the non-patterned device during the operation.