A general method for transferring graphene onto soft surfaces

• Jie Song,
• Fong-Yu Kam

Recent advances in chemical vapour deposition have led to the fabrication of large graphene sheets on metal foils for use in research and development.

However, further breakthroughs are required in the way these graphenes are transferred from their growth substrates onto the final substrate because they normally break or conjugate in this process. Although various methods have been developed, as yet there is no general way to reliably transfer graphene onto arbitrary surfaces, such as ‘soft’ ones, like polymers or textiles. Here, they reported a method that allows the graphene to be transferred with high fidelity at the desired location on almost all surfaces, including fragile polymer thin films and hydrophobic surfaces.

The method consisted on a sacrificial ‘self-releasing’ polymer layer placed between a conventional polydimethylsiloxane elastomer stamp and the graphene that is to be transferred. This self-releasing layer provides a low work of adhesion on the stamp, which facilitates delamination of the graphene and its placement on the new substrate regardless of its nature. This method synthesized the graphene by CVD over a metal (Cu or Ni) as it has been reported previously. This makes easier to change the normal process that has been used to adapted to this one.

 To demonstrate that the method can be done with any surface, they fabricate high field-strength polymer capacitors using graphene as the top contact over a polymer dielectric thin film.

These capacitors showed superior dielectric breakdown characteristics compared with those made with evaporated metal top contactsby CVD.

 So they take it to a new level by fabricating low-operation-voltage organic field-effect transistors using graphene as the gate electrode placed over a thin polymer gate dielectric layer.

So they finally made artificial graphite by alternating layers of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). This compound, which comprises graphene sheets p-doped by partial hole transfer from the F4TCNQ, shows a high and remarkably stable hole conductivity, even when heated in the presence of moisture.