Figure 5. Roll-to-roll/bubbling production of large-area flexible monolayer films and their heterostructures with graphene films.

(a) Schematic of the roll-to-roll/bubbling process. (b–e) Photographs of ∼2-inch flexible transparent films of monolayer WS₂ (b,c), double-layer WS₂ (d) and graphene/monolayer WS₂ van der Waals heterostructure (e) on PET fabricated by the roll-to-roll/bubbling method. The insets in b–e show the schematic models of the transferred films. ‘Gr' represents graphene.