Thermal-assisted direct transfer of graphene onto flexible substrates

We explored an easy technique to transfer directly large-area graphene grown by chemical vapor deposition (CVD) onto flexible substrates through substrate heating at appropriate temperatures. Polyethylene (PE) films were selected as the flexible substrate. The critical factor to ensure successful transfer was the good contact between the substrate and graphene. By heating the PE films merely approaching their glass-transition temperature, film morphology did not change. The stickiness of PE films further enabled the van der Waal forces to ensure close interaction between the viscoelastic substrate and graphene. This method did not require an intermediate transfer membrane such as polymethylmethacrylate (PMMA) that needs removal afterwards. Though this transfer method, monolayer and multilayer graphene films were transferred onto PE substrates with sheet resistance as low as 158 Ω/sq. All these results can be applied in existing and new graphene CVD applications on flexible substrates.