Controlling droplet dynamics in inkjet printing through hydrophilic/hydrophobic patterning for organic thin-film formation

Abstract Local hydrophilic patterning on hydrophobic substrates is proposed as a strategy to control inkjet-dispensed droplets for solution-based organic thin-film formation. The hydrophilic regions act as pinning sites during evaporation, influencing droplet dynamics. By designing appropriate hydrophilic/hydrophobic surface patterns, a pinned hexagonal droplet shape was achieved. The hexagonal droplet exhibited small contact angles at the pinned locations and was used to form 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C 8 -BTBT) organic thin films on the surrounding hydrophobic areas. The resulting films were integrated into organic thin-film transistors, which displayed typical p -channel characteristics with a maximum field-effect mobility of 2.9 cm 2 V −1 s −1 . This approach enables droplet control solely through solution dispensing, eliminating the need for mechanical guidance such as blades or bars, and offers a scalable, high-speed route for organic thin-film formation in printed electronics.