Chemical vapor deposition (CVD)-grown graphene and graphene oxide (GO) have been the main starting materials to produce graphene-based transparent conductors (TCs) [1,2]. For the CVD-grown graphene, the underlying substrates need to be removed so that the graphene sheets can be transferred onto the device substrates. Several strategies have been developed to transfer graphene sheets and they include the etching and stamping method [3,4], thermal release method [5], photoresist method [6], roll-to-roll transfer method [7], and general method [8]. Another lowcost route to produce graphene-based TCs on a large scale is to synthesize GO thin films and then reduce them. The ease of solution process of GO sheets due to their high solubility in aqueous solutions has made it a more viable and favorable approach [2]. Once a GO dispersion is produced, GO films can be formed on a substrate using different deposition techniques, including electrophoretic deposition (EPD), spin coating, spray coating, dip coating, transfer printing, LangmuirBlodgett (L-B) assembly, rod coating, and inkjet coating [1].
CVD-Grown Graphene-Based TCs
Etching MethodAfter graphene is grown on a metal substrate as described in Sect. 2.2, graphene needs to be transferred to the device substrate via a post-transfer process, which usually involves two main steps: (i) etching of the metal substrate and (ii) transfer of graphene onto the target substrate. The removal of growth substrate, such as Cu and Ni, is usually performed by immersing the substrate with the graphene film into the etching bath until a free-standing graphene membrane floating on the solution can be readily observed [9][10][11]