Electrical and optical properties of layer-stacked graphene transparent electrodes using self-supporting transfer method

We present a systemic investigation on electrical and optical properties of layer-stacked graphene transparent electrodes using a self-supporting method (SSM). As is expected, SSM-stacked films appear smoother surface morphologies (roughness of 4.60 nm for 5-layer sample) than the traditional layer stacking method. The non-contact electrical measurement demonstrates that sheet resistances of layer-stacked samples obviously diminish after the layer stacking process, which is only 20.16 Ω/□ for the 5-layer-SSM-stacked sample. All the SSM samples show high white light transparency (∼88% for 5-layer sample). The ultraviolet–visible–infrared absorption spectra indicate that there are two main absorption peaks, which are related to the inter-band emission with resonant exciton effect and intra-band absorption decoupled stacked multilayer graphene, respectively. And after nitric acid doping, these peaks show obvious red-shifts because of p-type doping and coupling effects arising from the layer-stacking process. All these results reveal that there are both strong coupled and decoupled multilayer graphene in the SSM-stacked samples; and the coupling effect can be enhanced after the acid treatment.