Effect of solvents on the electro-optical switching of graphene oxide dispersions

Abstract

The electrical manipulation of graphene oxide (GO) alignment in aqueous dispersions is a useful technique with various applications. In particular, the electrical switching of GO particles can be used to devise optical birefringent liquid crystal displays. However, the electric switching of aqueous GO dispersions with a high ionic concentration requires driving voltages with high frequencies (∼10 kHz), which is a challenging limitation. We demonstrate that stable electro-optical switching can be achieved at low frequencies (100 Hz) using GO dispersions in organic solvents instead of water. The hydrodynamic flow of the solvent and the electrophoretic drift of the GO particles are hindered in the GO dispersions in organic solvents with lower dielectric constants. Moreover, the electro-optical performance of these GO dispersions is similar to the aqueous GO dispersions, despite the lower magnitude of the ionization ratio for the GO particle functional groups. These results are crucial for developing a liquid crystal display device using GO dispersions.