Fig. 1.

Solvents for LPE of graphene. a Chemical structures of common organic solvents used in LPE, along with their surface tension and boiling points. b Graphene dispersion in NMP after centrifugation at 6–4 μg/mL concentrations (a) to (e). c Dispersed graphene concentration as a function of solvent surface tension/energy. d SEM image of pristine graphite (scale bar: 500 μm). e SEM image of sediment after centrifugation (scale bar: 25 μm). (f-h) Bright field TEM images of monolayer graphene sheets deposited from GBL (f), DMEU (g) and NMP (h) (Scale bar : 500 nm). (i, j) Bright field TEM images of a folded and multilayer graphene sheets respectively, deposited from NMP (scale bar: 500 nm). k Histogram of the number of graphene layers per flakes for NMP dispersions. b-k reproduced from ref. 19 with permission, © Nature Publishing Group)