Highly conductive and transparent graphene: Synergy of covalent and non-covalent co-doping

The three values of transparency, conductivity and flexibility make graphene a valid alternative to replace traditional electrode materials such as indium tin oxide in electrical and optical devices. In recent years, research efforts have been addressed to investigate doping methodologies for reducing further the sheet resistance while maintaining high transparency. In this contribution, we explore the possibility to integrate both the covalent and non-covalent doping in order to increase the carrier charge density without affecting their mobility significantly. We present a new graphene doping methodology that combines the effect of SOCl2 covalent p-doping with a synergic p-doping effect of cationic gold nanoparticles activated by the same SOCl2 chemistry. We demonstrate that this original co-doping strategy can provide CVD graphene multilayers with record sheet resistance Rs performances, which meet the technical target required by several industrial applications.