Negative electrical tunability of chitosan-graphene oxide nanocomposites

Herein, we report negative anomalous electrical tunability of the nanocomposite chitosan and graphene oxide (CS-GO) films based upon the dependence of dielectric constant and resistivity on DC bias. The origin of such anomalous tunability can be traceable to the reversible transformation of GO to reduced graphene oxide. In this transformation, H+ ions are released from water or GO side groups and those of NH3+ from CS; both ions participate in the reversible reduction process. Here, the capacitance exhibits negative tunability such that the dielectric constant increases and the resistivity decreases with increasing of DC bias. To probe this new phenomenon, we studied GO concentrations from 0 to 15 wt.% and water contents from 0 to 25 wt.%. Our results suggest that chitosan-GO nanocomposites can be readily prepared for the development of novel devices required in flexible organic electronics.