Au doping effect on chemically-exfoliated graphene and graphene grown via chemical vapor deposition

In order to assess the most suitable way for application of graphene-based flexible transparent electrodes, the effects of Au doping and subsequent annealing on graphene films produced by chemical exfoliation and chemical vapor deposition (CVD) were explored. After Au doping and subsequent annealing, uniformly-sized Au nanoparticles (NPs) were distributed on CVD-graphene films and reduced graphene oxide (rGO) films and the density of the Au NPs on rGO films was greater than that on CVD-graphene films. Interestingly, CVD-graphene films have sheet resistance behavior opposite to that of rGO films after Au doping and subsequent annealing. This can be understood by combined features including an increase in carrier concentration via p-type doping and an increase in contact resistance via the intercalation of non-conducting AuCl3 nanoparticles, as suggested by the work function measurement of CVD-graphene and rGO films before and after Au doping. This finding will shed light on an effective way to obtain large-scale and work function-tuned graphene films for applications in graphene-based flexible transparent electrodes.