Structural Integrity Preserving and Residue-Free Transfer of Large-Area Wrinkled Graphene onto Polymeric Substrates.

Wrinkled graphene offers many advantageous features resulting from modifying the structural and physical properties as well as the chemical reactivity of graphene. However, its inadequate transferability to other substrates has limited its usability. This paper reports a roll-based clean transfer approach that enables the damage-free and contamination-free transfer of large-area wrinkled graphene onto polymeric substrates without compromising the integrity of wrinkle structures. The method implements the simultaneous imidazole-assisted etching and doping of chemical vapor-deposited graphene to fabricate multilayer graphene on a thermoplastic polystyrene (PS) substrate coated with a water-soluble poly(4-styrenesulfonic acid) (PSS) sacrificial layer via a roll-based transfer process. The compliant PSS layer affords the conformal contact between the PS substrate and graphene during the wrinkle formation process, enabling the controllable fabrication of graphene wrinkle structures on a large area. The water-soluble properties of PSS simplify the typically difficult separation of wrinkled graphene from the PS substrate after its transfer onto a target substrate. This improves the transferability of wrinkled graphene, rendering the transfer process solvent-free and residue-free. This work demonstrates the feasibility of the formulated method by transferring centimeter-scale wrinkled graphene onto currently used transparent flexible substrates (i.e., polyethylene terephthalate and polydimethylsiloxane). The results indicate that the transferred wrinkled graphene possesses the desirable combination of superior stretchability, optical transmittance, sheet resistance, and electromechanical stability, rendering its suitable application to transparent flexible and stretchable electronics.