Roll-to-Roll Transfer of Conductive Graphene Sheets

Graphene technology has been widely explored to produce large sheets of conductive film to facilitate the manufacturing of flexible transparent photovoltaics. Monolayer-thick graphene has 97% transmittance in the visible regime and outstanding mechanical and electricalproperties:thatmakesgraphenesuitablefor transparent electrodes in order to replace the current state-of-the-art ITO electrodes, which are less flexible and are limited by the low indium supply on earth. However, scaling up the graphene manufacturing is tricky since it is typically grown on copper foils by chemical vapor deposition (CVD), and therefore, an ad- ditional transfer step is required to insert the graphene sheet into practical devices. The success of the transfer process is critical for the performances and the scalability of the graphene film.

Given the compatibility with the manufacturing processes in organic and flexible electronics, we explore roll-to-roll (R2R) to enable the deployment of large area graphene on plastic substrates. We investigate how to avoid defects and fractures in the graphene film upon transfer. We scan over several options in order to figure out how the interplay of adhesion forces between the graphene and the host substrate works out. These investigations will advance the progress of the application of graphene in future flexible electronics.