Doping stability and opto-electronic performance of chemical vapour deposited graphene on transparent flexible substrates

The primary barrier to wider commercial adoption of graphene lies in reducing the sheet resistance of the transferred material without compromising its high broad-band optical transparency, ideally through the use of novel transfer techniques and doping strategies. Here, chemical vapour deposited graphene was uniformly transferred to polymer supports by thermal and ultraviolet (UV) approaches and the time-dependent evolution of the opto-electronic performance was assessed following exposure to three kinds of common dopants. Doping with FeCl₃ and SnCl₂ showed minor, and notably time unstable, enhancement in the σ_opt/σ_dc figure of merit, while AuCl₃-doping markedly reduced the sheet resistance by 91.5% to 0.29 kΩ/sq for thermally transferred samples and by 34.4% to 0.62 kΩ/sq for UV-transferred samples, offering a means of realising viable transparent flexible conductors that near the indium tin oxide benchmark.