Single atomic-layer graphene visible to bare eye. Left: A 4-inch monolayer graphene film grown by chemical vapor deposition (CVD) floating on an aqueous solution. Right: Two monolayer graphene films transferred to glass substrates. Such graphene films can be used as transparent electrodes.
H. Cao et al., Appl. Phys. Lett. 96, 122106 (2010)
Image courtesy: Dr. Y. P. Chen, Purdue University.