Highly conducting graphene sheets and Langmuir-Blodget films

Graphene is an intriguing material with properties that are
distinct from those of other graphitic systems. The first
samples of pristine graphene were obtained by ‘peeling off ’
and epitaxial growth. Recently, the chemical reduction of
graphite oxide was used to produce covalently functionalized
single-layer graphene oxide. However, chemical approaches
for the large-scale production of highly conducting graphene
sheets remain elusive. Here, we report that the exfoliation–
reintercalation–expansion of graphite can produce highquality
single-layer graphene sheets stably suspended in
organic solvents. The graphene sheets exhibit high electrical
conductance at room and cryogenic temperatures. Large
amounts of graphene sheets in organic solvents are made into
large transparent conducting films by Langmuir–Blodgett
assembly in a layer-by-layer manner. The chemically derived,
high-quality graphene sheets could lead to future scalable
graphene devices.