Interlayer non-coupled optical properties for determining the number of layers in arbitrarily stacked multilayer graphenes

We demonstrate a simple and easy technique to reliably count the number of layers in graphenes with stacking faults. Using lasers with wavelengths of 514 and 633 nm, the optical transmittances of multilayer graphene with Bernal, rhombohedral and artificial stacking orders were systematically measured depending on the number of layers. It was found that the optical transmittance of the multilayer graphene is linearly proportional to the number of layers up to 7 regardless of its stacking order. Measurement of optical transmittance can be a useful approach to reliably determine the number of layers in multilayer graphene, thus aiding investigation of its layer-dependent properties and applications.