Detecting Electric Dipoles Interaction at the Interface of Ferroelectric and Electrolyte Using Graphene Field Effect...

Graphene was inserted into the interface between electric dipole layers from DEME-TFSI ionic liquid (top-gate) and ferroelectric Pb_0.92La_0.08Zr_0.52Ti_0.48O₃ (PLZT, back-gate) to probe the interface dipole-dipole interaction in response to DC and pulsed gate voltages. A highly complicated behavior of the interface dipole-dipole interaction has been revealed as a combination of electrostatic and electrochemical effects. The interfacial polar molecules in the DEME-TFSI electrical double layer are pinned with assistance from the PLZT back-gate in response to a DC top-gate pump, leading to strong nonlinear electrochemical behavior. In contrast, depinning of these molecules can be facilitated by a faster pulsed top-gate pump, which results in a characteristic linear electrostatic behavior. This result not only sheds light on the dynamic dipole-dipole interactions on the interface between functional materials but also prototypes a unique pump and probe approach using graphene field effect transistors to detect the interface dipole-dipole interaction.