Many layers of graphene make up graphite, or pencil lead.
By cooling the foil quickly, just a few layers of graphene are obtained.
"The method allows you to deposit single layers of graphene," Chhowalla says.
Single layers of graphene absorb 2.5percentnt of available light; as layers pile up, they begin to appear black.
Like graphite, graphene is entirely composed of carbon atoms and 1mm of graphite contains some 3 million layers of graphene.
Carbon technology is advancing rapidly, with even greater performance characteristics claimed for single-atom-thick layers of graphene.
The result is multiple layers of graphene sheets, measuring five nanometres (millionths of a metre) long and two nanometres wide.
Then carbon is deposited on the surface, where it forms layers of graphene above and beneath the SiO2.
Billions of layers of graphene stacked on top of each other make up crystals of the more familiar graphite, used in pencil leads.
The solar cells were created from atomically thin layers of metal dichalcogenides – optically active materials that can absorb light – sandwiched between conducting layers of graphene.
The most probable number of layers of graphene was determined according to specific surface area.
