Single layer graphene is of great interest for electronic applications as an atomically thin, zero band gap semiconductor. Experimental results so far have been limited due to the difficulty of creating large, single layer samples. Here we report a competitive approach to the large-scale production of single layer chemically converted graphene (CCG). By dispersing graphite oxide paper in pure hydrazine, we are able to remove oxygen functionalities while preserving the integrity and restoring the planar geometry of single sheets. The CCG sheets produced with this method have among the largest areas of any yet reported (up to 20 x 40 m), making them relatively straightforward to process. Field effect devices have been fabricated by conventional photolithography and display currents that are three orders of magnitude higher than those previously reported for CCG. The versatility of solution processing also enables single layer graphene sheets to be registered using a PDMS stamping technique. Through surface energy manipulation, large-scale registration of graphene is now possible. Raman spectroscopy has been used to confirm uniform registration across large areas. Due to the large size of these sheets, comprehensive studies including optical microscopy, AFM, SEM and FET device characterization can all be performed on the same specimen. By combining graphene and carbon nanotubes, flexible, conducting, transparent windows can be made. This solution processing of carbon-based materials thus holds great promise for nanoelectronic applications.
