All inkjet-printed electronics based on electrochemically exfoliated two-dimensional metal, semiconductor, and dielectric

Abstract

Abstract Inkjet printing is a cost-effective and scalable way to assemble colloidal materials into desired patterns in a vacuum- and lithography-free manner. Two-dimensional (2D) nanosheets are a promising material category for printed electronics because of their compatibility with solution processing for stable ink formulations as well as a wide range of electronic types from metal, semiconductor to insulator. Furthermore, their dangling bond-free surface enables atomically thin, electronically-active thin films with van der Waals contacts which significantly reduce the junction resistance. Here, we demonstrate all inkjet-printed thin-film transistors consisting of electrochemically exfoliated graphene, MoS 2 , and HfO 2 as metallic electrodes, a semiconducting channel, and a high- k dielectric layer, respectively. In particular, the HfO 2 dielectric layer is prepared via two-step; electrochemical exfoliation of semiconducting HfS 2 followed by a thermal oxidation process to overcome the incompatibility of electrochemical exfoliation with insulating crystals. Consequently, all inkjet-printed 2D nanosheets with various electronic types enable high-performance, thin-film transistors which demonstrate field-effect mobilities and current on/off ratios of ~10 cm 2 V −1 s −1 and >10 5 , respectively, at low operating voltage.