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

TLDR

Roll‑to‑roll transfer of CVD graphene is essential for large‑scale production of flexible transparent electrodes, but the high contact pressure of nip rolls damages the graphene and degrades its electrical performance. The study aimed to develop a damage‑mitigation method for roll‑transfer of graphene. By SEM imaging and finite‑element analysis, the authors classified three failure modes, identified their mechanisms, and used this knowledge to design a nip‑force‑controlled R2R machine that transferred 400‑mm‑wide graphene at 1,000 mm min⁻¹. The resulting roll‑transferred graphene exhibited high conductivity and uniformity, confirming the scalability and productivity of the developed technology.

Abstract

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.