Low-voltage solution-processed graphene transistors based on chemically and solvothermally reduced graphene oxide

We have developed solution-processed reduced graphene oxide (RGO) transistors with ion gel gate dielectrics. The combination of solution-processed high-capacitance ion gel gate dielectrics and spray-coated RGO films yielded high-performance RGO transistors that operated below 4 V. Two reduction processes were applied to GO: (i) chemical reduction by hydrazine and (ii) solvothermal reduction in N-methyl-2-pyrrolidone. Chemical reduction provided a more efficient route to reduce GO than solvothermal reduction, and the resulting RGO films yielded higher electron and hole mobilities than films based on solvothermal methods. Temperature-dependent transport studies revealed that higher mobilities in RGO films based on chemical reduction result from (i) more effective delocalization of the charge carriers, (ii) more numerous localized states near the Fermi energy, and (iii) a longer optimum hopping distance, compared to those for films based on solvothermal reduction.