Self-Aligned Capillary-Assisted Printing of Bottom-Gate Electrolyte-Gated Transistors on Plastic

In printed electronics, self-aligned transistors are a key technology toward scalable and low-cost electronics. However, significant misalignment between components restricts transistors to a print resolution ≈140 μm while individual components are able to demonstrate a high resolution ∼10 μm. Capillarity, that spontaneously aligns liquids in narrow spaces, offers great promise following translation into a printing method by exhibiting excellent self-alignment while high-resolution printing. Here, I utilize a capillary-assisted printing for the first time for electrolyte-gated transistors based on a bottom-gate architecture. Surprisingly, this method self-aligns pure ionic liquid electrolytes on flexible plastic with excellent stability to bending, thermal, aging, and folding degradation. Furthermore, it renders line features with narrow widths (5–38 μm) and ultralow roughnesses (30–700 nm). Leveraging this method with a bottom-gate architecture, promising for dynamic performance or sensing external stimuli, and transistor components, reliable self-aligned high-resolution transistors are produced experiencing no fabrication failure (35 devices/35 devices) and retaining a resolution (38 μm) of the highest among all-printed transistors. Despite this, the transistors were endowed with excellent electronic properties such as a low-voltage (sub-2 V) operation and operational stability to repeated bending and electrical stresses. This work holds great potential for diverse architectures and materials for flexible printed devices.