Balance of surface energy difference between wetting and dewetting regions for patterning solution-processed organic light-emitting diode

Abstract

Solution-processed organic light-emitting diodes (S-OLEDs) are potential candidates for next-generation wearable electronics due to the simple processing capability, high scalability, and mechanical flexibility. As a demand for the high-resolution OLEDs is given rise to realize the natural images in the eyewear displays, developing efficient methods for producing solution-processed organic patterns has been vital to achieve the practical S-OLEDs. Despite considerable effort to develop the fine organic patterns, an incomplete understanding of the effect of the surface wetting nature on the precise pattern formation inevitably restricts the resolution of the S-OLEDs. Herein, we present the physical picture of forming solution-processed high-resolution organic patterns using wetting phenomena. For macroscale patterns larger than 50 μm, the surface energy difference between the wetting and dewetting regions are critical for governing the pattern fidelity. In contrast, the microscale patterns with a feature size lower than 10 μm are produced by the subtle interplay between the surface energy difference and wettability following the Cassie state of the substrate. High-resolution line patterns with a width of 5 μm of the S-OLED are fabricated by balancing the surface energy difference and wettability of the substrate. The patterned S-OLED exhibits a high-pattern fidelity and stable electro-optical performance without any detrimental effects.