Temperature-dependent modification is an effective way to reversibly tailor graphene's electronic properties. We present the reversible modification of a uniform monolayer nitrogen-doped graphene (NG) film by the formation and cleavage of temperature-dependent Se-N dynamic covalent bonds. The increasing binding energy in X-ray photoelectron spectroscopy (XPS) indicates that phenylselenyl bromine (PhSeBr) bonds with pyridinic N and pyrrolic N rather than graphitic N by accepting the lone pair of electrons. The temperature dependence of Raman spectra (the increasing D band and the shifts of the 2D band) and XPS spectra (Se 3d and N 1s) indicates that the Se-N dynamic covalent bond is gradually cleaved by treatment at increasing temperatures and is also recovered by the reversible modification. Field-effect transistors (FETs) based on Se-NG exhibit a temperature-dependent change from n-type to p-type conduction and tunable electron and hole mobilities owing to the reversible formation or cleavage of Se-N dynamic covalent bonds. This result opens up opportunities for reversibly controlling electrical properties of FETs by optimizing dynamic covalent bonds.
Keywords: dynamic covalent bonds; field-effect transistors; monolayer; nitrogen-doped graphene; temperature-dependent.