Reversible Switching of the Dirac Point in Graphene Field-Effect Transistors Functionalized with Responsive Polymer Brushes

JUAN MARTÍN GIUSSI; ESTEBAN PICCININI; ESTEBAN PICCININI; WOLFGANG KNOLL; CHRISTINA BLIEM; WOLFGANG KNOLL; OMAR AZZARONI; CHRISTINA BLIEM; OMAR AZZARONI; JUAN MARTÍN GIUSSI

LANGMUIR

AMER CHEMICAL SOC

Lugar: Washington; Año: 2019 vol. 35 p. 8038 - 8044

0743-7463

The reversible control of the graphene Dirac point using external chemical stimuli is of major interest in the development of advanced electronic devices such as sensors and smart logic gates. Here, we report the coupling of chemoresponsive polymer brushes to reduced graphene oxide (rGO)-based field-effect transistors to modulate the graphene Dirac point in the presence of specific divalent cations. Poly[2-(methacryloyloxy)ethyl] phosphate (PMEP) brushes were grown on the transistor channel by atom transfer radical polymerization initiated from amine-pyrene linkers noncovalently attached to rGO surfaces. Our results show an increase in the Dirac point voltage due to electrostatic gating effects upon the specific binding of Ca2+ and Mg2+ to the PMEP brushes. We demonstrate that the electrostatic gating is reversibly controlled by the charge density of the polymer brushes, which depends on the divalent cation concentration. Moreover, a theoretical formalism based on the Grahame equation and a Langmuir-type binding isotherm is presented to obtain the PMEP−cation association constant from the experimental data.