Damage mitigation in roll-to-roll transfer of CVD-graphene to flexible substrates

Roll-to-roll (R2R) transfer of a chemical vapor deposition (CVD) graphene is an inevitable step for large scale and high throughput manufacturing of graphene transparent electrodes on flexible substrates. The damages on graphene induced by high contact pressure of nip rolls during the roll transfer degrade the electrical properties of the transferred graphene on flexible substrates. In this study, we developed a damage mitigation method for the roll transfer of graphene. By analyzing scanning electron microscope (SEM) images of the damages on the transferred graphene, three types of failure modes were classified, and the corresponding failure mechanisms were revealed using the surface morphology and the finite element analyses. Based on the understanding of the failure mechanisms, the graphene transfer with a width of 400 mm was realized at a speed of 1000 mm min^-1 using an R2R transfer machine with the capability of nip force control. The high electrical conductivity and uniformity of the roll-transferred graphene demonstrates the scalability and the productivity of the developed roll transfer technology.