Wearable and Flexible devices

Project Description

the current semiconductor manufacturing relies heavily on sophisticated fabrication processes such as lithography, vacuum deposition, etc., which may be prohibitively costly and time consuming to adapt to TMDC-based devices. Fortunately, printing technology designed for solution-based low-temperature processing can eliminate the needs for high-cost lithography and vacuum systems. Up to now, printing approaches have been reported for a number of devices including field-effect transistors (FETs), logic gates, and solar cells using carbon nanotubes (CNTs), metal oxides, organic films, or inorganic nanoparticles, which demonstrate the great potential of using printing technology for low-cost and large-scale electronic applications.

We report a three-step “flood-dike” self-aligned printing method which can reliably produce sub-micron channels on 2D TMDC flakes. In this study, we chose CVD-synthesized monolayer WSe2 as the channel materials for demonstration. This printing strategy is highly compatible with other CVD-synthesized, mechanically exfoliated and liquid exfoliated 2D TMDC materials. This “flood-dike” printing method is highly reliable with ~90% yields. The as-printed WSe2 FETs show dramatically improved on-state current densities of ~ 0.64 μA/μm (average), high on/off current ratios of ~ 3x105 (average), and good field-effect mobilities of ~ 1.0 cm2/Vs (average). Compared to previously reported printed 2D TMDC FETs, we have successfully downscaled the channel length to sub-micron scale and promoted the on-state current density by several orders of magnitude. Furthermore, with these superior printed WSe2 transistors, our work offers a lithography-free low-cost platform to produce high-performance 2D TMDC electronics and paves the way for display backplane, sensing and many other potential applications.

Team Members

List of Publications

  • Cao, Xuan, Christian Lau, Yihang Liu, Fanqi Wu, Hui Gui, Qingzhou Liu, Yuqiang Ma, Haochuan Wan, Moh R. Amer, and Chongwu Zhou. "Fully screen-printed, large-area, and flexible active-matrix electrochromic displays using carbon nanotube thin-film transistors." ACS nano 10, no. 11 (2016): 9816-9822.
  • Cao, Xuan, Yu Cao, and Chongwu Zhou. "Imperceptible and ultraflexible p-type transistors and macroelectronics based on carbon nanotubes." ACS nano 10, no. 1 (2015): 199-206.
  • Wu, Fanqi, Liang Chen, Anyi Zhang, Yi-Lun Hong, Nai-Yun Shih, Seong-Yong Cho, Gryphon A. Drake et al. "High-Performance Sub-Micrometer Channel WSe2 Field-Effect Transistors Prepared Using a Flood–Dike Printing Method." ACS nano (2017).