Scalable, universal and conformal direct electrodes microprinting for high-performance van der Waals-integrated two-dimensional electronics and flexible applications

Abstract: Two-dimensional (2D) materials with extraordinary electrical properties, hold promising for large-scale, flexible electronics. However, their device performance could be hindered due to the excessive defects introduced via traditional electrode integration processes. Transfer printing techniques have been developed for van der Waals contacts integration, while existing techniques encounter limitations in achieving conformal electrode transfer and compatibility with flexible devices. Here we introduce a highly conformal microprinting technique utilizing polypropylene carbonate (PPC)/Polyvinyl alcohol (PVA) copolymer, which enables successful transfer of wafer-scale, micropatterned electrodes onto diverse substrates, including those with complex geometries. This technique, implemented with 2D transition metal dichalcogenides (TMDCs), yields 2D field-effect transistors with near-ideal ohmic contacts, and a record-high carrier mobility up to 334 cm2 V-1 s-1 for a WSe2 device. Furthermore, we fabricated transistor arrays on MoS2 thin film, which show uniform device performance. We also present the flexible MoS2 transistors that not only achieve a high electron mobility of up to 111 cm2 V-1 s-1 but also exhibit outstanding mechanical robustness. Our findings represent a significant leap forward in the fabrication of flexible 2D electronics, paving the way for numerous emerging technologies.