Fully inkjet-printed device fabrication is a crucial goal to enable large-area printed electronics. The limited number of two-dimensional (2D) material inks, the bottom-gated structures, and the low current on/off ratio of thin-film transistors (TFTs) has impeded the practical applications of the printed 2D material TFTs. In the search for TFTs with high current ratios, we introduce a stable and efficient method of nitrogen-doped graphene (NDG) ink preparation for inkjet printing by liquid-phase exfoliation. The NDG thin film is print-stacked with molybdenum disulfide (MoS2) by multiple printing passes to construct a MoS2-NDG stack. We demonstrate top-gated fully inkjet-printed MoS2-NDG transistors with silver drain, source, and gate electrodes, and a barium titanate (BaTiO3) dielectric. A 100% inkjet-printed MoS2-NDG vertical 2D active heterostructure layer transistor with a current on/off ratio of 1200 is exhibited. The results may lead towards the development of all-printed 2D material-based transistor switches.
Keywords: Raman; cross-section; graphene; inkjet printing; molybdenum disulfide; nanosheets; on/off ratio; thin-films; transistor.