Capillary Flow Printing of Submicron Carbon Nanotube Transistors

Printed transistors have a wide range of applications, but the limited resolution of printing techniques (10-30 μm) has been a barrier to their utility and scalability. Previous works have relied on chemical processes or tedious post-processing to realize printed submicron channel lengths, limiting their applicability. Here, we show that capillary flow printing can create as-printed submicron carbon nanotube thin-film transistors (CNT-TFTs) without chemical modification or physical manipulation post-printing. We show that the approach can be used to print conducting, semiconducting, and insulating inks on different types of substrates (silicon, Kapton, and paper), and can be used to fabricate various TFT device architectures. Printed CNT-TFTs yielded on-currents of 1.12 mA/mm when back gated on Si/SiO₂, and 490 μA/mm when side gated through ion gel on Kapton. Mechanical bending and sweep rate resilience of devices on Kapton show the wide utility of these printed devices for flexible applications.