High-performance organic field-effect transistors with dielectric and active layers printed sequentially by ultrasonic spraying

High-performance organic field-effect transistors (OFETs) are reported with dielectric and active layers sequentially deposited by ultrasonic spray-printing. A cross-linkable insulator and a soluble small molecule semiconductor are developed which are both printable and highly robust. Using plastic with pre-patterned indium tin oxide gate contacts as required for display applications, two different layers are sequentially spray-printed: the semiconductor 6,13-bis(trisopropylsilylethynyl)pentacene (TIPS-PEN), and the insulator poly-4-vinylphenol (PVP). OFETs printed in ambient air with a bottom-gate/top-contact geometry are shown to achieve on/off ratios of >10⁴ and mobilities up to 0.35 cm² V^-1 s^-1. These rival the characteristics of the best solution-processable small molecule FETs fabricated by other processing methods such as drop casting and ink-jet printing.