Controlling the Dirac point voltage of graphene by mechanically bending the ferroelectric gate of a graphene field effect transistorElectronic supplementary information (ESI) available. See DOI: 10.1039/c8mh01499j

Controlling the Dirac point voltage of graphene is essential for realizing various practical applications of graphene. Here, control of the doping state is achieved in flexible graphene field effect transistors (GFETs) by applying mechanical bending stress. By gradually increasing the bending strain (the decrease of upward/downward bending radius), the Dirac point (VDirac) linearly shifts to left/right, which is induced by the flexoelectric effect of the ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3(PLZT) gate. In addition, a superior mechanical antifatigue character is obtained in the flexible GFETs, and the doping effect is recoverable. The sensitivity to strain and high bending stability not only offer an easy, controllable and nonintrusive method to obtain a specific doping level in graphene for flexible electric devices, but also highlight the enormous potential of the flexible ferroelectric PLZT-gated GFETs as wearable sensors.