Graphene suspensions for 2D printing

It is shown that, by processing a graphite suspension in ethanol or water by ultrasound and centrifuging, it is possible to obtain particles with thicknesses within 1–6 nm and, in the most interesting cases, 1–1.5 nm. Analogous treatment of a graphite suspension in organic solvent yields eventually thicker particles (up to 6–10 nm thick) even upon long-term treatment. Using the proposed ink based on graphene and aqueous ethanol with ethylcellulose and terpineol additives for 2D printing, thin ($\sim$5 nm thick) films with sheet resistance upon annealing $\sim$30 M$\Omega/\square$ were obtained. With the ink based on aqueous graphene suspension, the sheet resistance was $\sim$5–12 $k\Omega/\square$ for 6- to 15-nm-thick layers with a carrier mobility of $\sim$30–50 cm$^{2}$/(V s).