Graphene shows the great promise as a transparent conductive electrode to replace conventional indium tin oxide (ITO) for optoelectronic applications. However, the wide applications of graphene in the fields such as organic light emitting diodes (OLEDs) are restricted by the difficulty in obtaining a clean and flat graphene surface; the large residue generated during graphene transfer can lead to a large short circuit 10 current and consequently degradation of device performance.