Enhancing the conductivity of transparent graphene films via doping

Abstract

We report chemical doping (p-type) to reduce the sheet resistance of graphenefilms for the application of high-performance transparent conducting films.The graphene film synthesized by chemical vapor deposition was transferredto silicon oxide and quartz substrates using poly(methyl methacrylate).AuCl3 in nitromethane was used to dope the graphene films and the sheet resistance was reducedby up to 77% depending on the doping concentration. The p-type doping behavior wasconfirmed by characterizing the Raman G-band of the doped graphene film. Atomic forcemicroscope and scanning electron microscope images reveal the deposition ofAu particles on the film. The sizes of the Au particles are 10–100 nm. The effectof doping was also investigated by transferring the graphene films onto quartzand poly(ethylene terephthalate) substrates. The sheet resistance reached 150 Ω/sq at 87% transmittance, which is comparable to those of indium tin oxide conducting film.The doping effect was manifested only with 1–2 layer graphene but not with multi-layergraphene. This approach advances the numerous applications of graphene films astransparent conducting electrodes.