All inkjet-printed electronics based on electrochemically exfoliated two-dimensional metal, semiconductor, and dielectric
Okin Song, Dongjoon Rhee, Jihyun Kim, Youngseo Jeon, Vlastimil Mazánek, Aljoscha Söll, Yonghyun Albert Kwon, Jeong Ho Cho, Yong‐Hoon Kim, Zdeněk Sofer, Joohoon Kang
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.