Full Two-Dimensional Ambipolar Field-Effect Transistors for Transparent and Flexible Electronics

The unique features of two-dimensional (2D) materials provide significant opportunities for the development of transparent and flexible electronics. Recently, ambipolar 2D semiconductors have advanced innovative applications such as CMOS-like circuits, reconfigurable circuits, and ultrafast neuromorphic image sensors. Here, we report on the fabrication of full 2D ambipolar field-effect transistors (FETs), in which graphene serves as the source/drain/gate electrodes, WSe₂ is for the channel, and h-BN is for the dielectric. The produced ambipolar FETs exhibit comparable on-currents in the n-branch and p-branch with on/off ratios up to 10⁸. By using two ambipolar FETs in series, a CMOS-like inverter is demonstrated with a maximum gain of up to 147, which can work in both the first and third quadrants by controlling the supply voltages and input voltages. The full 2D ambipolar FETs yield a transmittance of over 70% for visible light on transparent glass and achieve a curvature radius of less than 0.5 cm for bending on polyethylene terephthalate (PET) substrate. The work is helpful for the application of ambipolar 2D materials-based devices in transparent and flexible electronics.