Chemical vapor deposition-grown graphene transparent conducting electrode for organic photovoltaics: Advances towards scalable transfer-free synthesis

Chemical vapor deposition (CVD)-grown graphene has gained significant attention as a potential alternative to indium tin oxide (ITO) transparent conducting electrode (TCE) for organic photovoltaics (OPVs). However, the high cost, complex manufacturing process, and elevated deposition temperatures limit the widespread application of CVD-graphene for TCEs. Furthermore, the transfer of CVD-graphene from the growth substrate (metal catalyst) onto the transparent target substrate (e.g. glass, PET, etc.) can result in substantial degradation of the graphene characteristics. Therefore, the direct growth of high-quality CVD-graphene on transparent substrates is an ultimate goal. Plasma-enhanced CVD facilitates graphene growth on dielectric substrates, but the resulting films often exhibit high sheet resistance and structural defects. This critical review discusses the advancements in CVD-graphene TCEs over the past decade. It investigates the synthesis of CVD-graphene on metal catalysts and explores various transfer methods in detail. The growth of CVD-graphene on dielectric substrates and the different strategies proposed to enhance its properties for TCE applications are scrutinized. More importantly, the most recent advances in single-step manufacture of CVD-graphene TCEs are discussed. This report also presents new insights and perspectives to address the current challenges of scalable production of transfer-free graphene TCEs for OPVs and other optoelectronics.