Liquid-assisted adhesion control of graphene–copper interface for damage-free mechanical transfer

Mechanical transfer of synthesized graphene has attracted considerable attention owing to its widely applicable and substrate recyclable process. Particularly, the interfacial adhesion energy between graphene and the growth Cu substrate plays an important role in the mechanical transfer of graphene without compromising its quality and properties. However, the quantitative control of adhesion for the graphene–Cu interface has remained a challenge. Here, we introduce liquid-assisted adhesion control of the graphene–Cu interface for a damage-free mechanical transfer process. It is demonstrated using environmentally assisted fracture mechanics testing that the adhesion energy of the graphene–Cu interface can be controlled by separating the interface in liquid environments. Analysis of the wetting characteristics for each surface and the thermodynamic work of adhesion calculation reveal the mechanism of liquid-assisted adhesion control. Liquid-assisted adhesion control effectively reduces structural defects in the transferred graphene layers. Finally, the applicability of the adhesion-controlled graphene transfer method to flexible and stretchable electronics is investigated.