  A simple solvent exchange method is introduced to prepare high-concentration
and surfactant-free graphene liquid dispersion. Natural graphite flakes are
first exfoliated into graphene in dimethylformamide (DMF). DMF is then
exchanged by terpineol through distillation, relying on their large difference
in boiling points. Graphene can then be concentrated thanks to the volume
difference between DMF and terpineol. The concentrated graphene dispersions are
used to fabricate transparent conductive thin films, which possess comparable
properties to those prepared by more complex methods.
