Bi- and Tri- Layer Graphene Solutions

Wednesday, October 19, 2011: 4:17 PM
205 D (Minneapolis Convention Center)
Chih-Jen Shih1, Zhong Jin1, Shangchao Lin2, Geraldine LC Paulus3, Nigel Forest Reuel3, Qing Hua Wang3, Daniel Blankschtein3 and Michael Strano1, (1)Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, (2)Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, (3)Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA

Many applications of pristine, AB-stacked bilayer and trilayer graphene require synthesis methods to control the number of stacked layers. Solution dispersion is promising for printable electronics and nanocomposites. However, no method is currently available for the predetermined exfoliation of AB-stacked or large area flakes such that conventional photolithography is possible.  Here, we demonstrate that graphite intercalation with ionic, non-covalent intercalants to yield Stage-2 and Stage-3 compounds results in bilayer- and trilayer-enriched graphene dispersions, respectively. The intercalation and subsequent expansion of graphite allows mild sonication to yield stable dispersions, decreasing flake size reduction while maintaining AB stacking as confirmed by Raman spectroscopy.  An on-chip micro-hydrodynamic separation method localizes large area graphene flakes (up to 50 μm2). This constitutes the only viable route at this time for the mass-production of AB stacked bi- and tri- layer graphene. Unannealed bilayer flakes exhibit low resistivity (~1 kΩ) and mobilities which are higher (~400 cm2V-1s-1) than those attained utilizing other solution methods.

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