Thermally-assisted reformation of spray-printed polymer channel layer for improved transistor performance and device-to-device uniformity

초록

Bulk and surface morphology of a channel layer needs to be controlled to obtain desirable electrical performance of organic transistors and circuits based on them. Although spray coating is widely used in industry for continuous production of thin films, the microscopically rough nature of the spray-printed films makes it challenging to apply in electronics. Herein, we demonstrate a simple, scalable, and general approach by combining solvent mixing and thermal annealing to improve surface flatness, and therefore device reproducibility, without additional apparatuses attached to the spraying tools. We find that a small amount (2–5 vol%) of a high-boiling-point solvent, which can dissolve the channel material only at an elevated temperature, reduces surface roughness and rearranges the internal microstructure of the channel layer via dissolution and re-solidification during heat treatment. Thermally-assisted reformation of the channels of representative polymers (P3HT and PDPP2T-TT) results in 1.5–2.1 times enhancement of charge-carrier mobility in organic electrochemical transistors compared to as-printed films. At the same time, the device-to-device variation is significantly reduced with about 4–5 times lower coefficient of variation in electrical characteristics. © 2024

키워드