Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, S117543, Singapore.
Nat Nanotechnol. 2013 May;8(5):356-62. doi: 10.1038/nnano.2013.63. Epub 2013 Apr 28.
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. Although various methods have been developed, as yet there is no general way to reliably transfer graphene onto arbitrary surfaces, such as 'soft' ones. Here, we report 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 relies 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. To demonstrate the generality and reliability of our method, we fabricate high field-strength polymer capacitors using graphene as the top contact over a polymer dielectric thin film. These capacitors show superior dielectric breakdown characteristics compared with those made with evaporated metal top contacts. Furthermore, we fabricate low-operation-voltage organic field-effect transistors using graphene as the gate electrode placed over a thin polymer gate dielectric layer. We finally demonstrate an artificial graphite intercalation compound by stacking alternate monolayers of graphene and 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.
化学气相沉积的最新进展使得在金属箔上制造大片石墨烯成为可能，从而用于研究和开发。然而，在将这些石墨烯从其生长衬底转移到最终衬底的方式上，还需要进一步的突破。尽管已经开发出各种方法，但迄今为止，还没有一种通用的方法可以可靠地将石墨烯转移到任意表面上，例如“柔软”的表面。在这里，我们报告了一种方法，可以在几乎所有表面上（包括易碎的聚合物薄膜和疏水性表面）以所需的位置高保真地转移石墨烯。该方法依赖于一种牺牲的“自释放”聚合物层，该聚合物层放置在传统的聚二甲基硅氧烷弹性体印章和要转移的石墨烯之间。这种自释放层在印章上提供了低的粘附功，这有利于石墨烯的分层和在新衬底上的放置。为了证明我们的方法的通用性和可靠性，我们使用石墨烯作为聚合物介电薄膜上的顶部接触，制造了高场强聚合物电容器。与使用蒸发金属顶接触制成的电容器相比，这些电容器表现出优异的介电击穿特性。此外，我们使用石墨烯作为栅电极，将其放置在薄聚合物栅介质层上，制造了低工作电压有机场效应晶体管。我们最后通过堆叠石墨烯和 2,3,5,6-四氟-7,7,8,8-四氰基对醌二甲烷（F4TCNQ）的交替单层来演示人工石墨插层化合物。该化合物由石墨烯片组成，通过 F4TCNQ 的部分空穴转移部分掺杂，表现出高且非常稳定的空穴电导率，即使在存在水分的情况下加热也如此。
