Top-gate thin-film transistors (TFTs) are fabricated on plastic using a self-aligned method based on capillarity-assisted lithography and inkjet printing, offering a promising platform for high-throughput manufacturing of flexible electronic devices. Plastic substrates are imprinted with a multi-tier structure containing capillary channels and ink receivers using a precision mold. Liquid inks are sequentially delivered to the microstructured substrate by inkjet printing, and capillary action draws the inks into a multi-tier capillary channel network designed for top-gate TFTs. The combination of imprinting, inkjet printing, and capillary flow yields self-aligned multi-layered devices without requiring precise registration for inkjet printing. The printed top-gate TFTs with Ag/Cu source and drain, poly(3-hexylthiophene) semiconducting channel, ion gel dielectric, and graphene gate electrode have desirable transfer and output characteristics, with a hole mobility of 0.48 cm2 V-1 s-1, threshold voltage of -0.86 V, on/off current ratio of 104.5, and robust tolerance to bending. The top-gate geometry and careful materials selection yields devices with negligible hysteresis and sweep rate dependence, establishing the versatility and utility of this self-aligned strategy for more widespread application in printed and flexible electronics.
Bibliographical noteFunding Information:
This work was supported in part by the Multi-University Research Initiative (MURI) program (N00014-11-1-0690) sponsored by the Office of Naval Research. EBS and MCH also acknowledge support from the Air Force Research Laboratory under agreement number FA8650-15-2-5518. W J H was further supported by the MN Drive program at the University of Minnesota. LFF and CDF also acknowledge financial support through NSF-1634263 and the Xerox Research Corporation of Canada. We thank Svetlana Morozova for measuring ink viscosity. Parts of this work were performed at the Characterization Facility and the Nano-Fabrication Center of the University of Minnesota. The US Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the sponsors.
© 2018 IOP Publishing Ltd.
- capillarity-assisted lithography
- flexible electronics
- inkjet printing
- thin-film transistor
- top-gate structure