Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Nat Nanotechnol. 2011 Jun 26;6(7):439-45. doi: 10.1038/nnano.2011.94.
Bilayer and trilayer graphene with controlled stacking is emerging as one of the most promising candidates for post-silicon nanoelectronics. However, it is not yet possible to produce large quantities of bilayer or trilayer graphene with controlled stacking, as is required for many applications. Here, we demonstrate a solution-phase technique for the production of large-area, bilayer or trilayer graphene from graphite, with controlled stacking. The ionic compounds iodine chloride (ICl) or iodine bromide (IBr) intercalate the graphite starting material at every second or third layer, creating second- or third-stage controlled graphite intercolation compounds, respectively. The resulting solution dispersions are specifically enriched with bilayer or trilayer graphene, respectively. Because the process requires only mild sonication, it produces graphene flakes with areas as large as 50 µm(2). Moreover, the electronic properties of the flakes are superior to those achieved with other solution-based methods; for example, unannealed samples have resistivities as low as ∼1 kΩ and hole mobilities as high as ∼400 cm(2) V(-1) s(-1). The solution-based process is expected to allow high-throughput production, functionalization, and the transfer of samples to arbitrary substrates.
具有可控堆叠的双层和三层石墨烯作为后硅纳米电子学最有前途的候选材料之一正在兴起。然而，目前还不可能生产出大量具有可控堆叠的双层或三层石墨烯，因为许多应用都需要这样的材料。在这里，我们展示了一种从石墨中生产大面积、具有可控堆叠的双层或三层石墨烯的溶液相技术。离子化合物碘氯化物（ICl）或碘溴化物（IBr）分别在每第二层或第三层插入石墨起始材料，从而分别形成第二阶段或第三阶段的可控石墨插层化合物。所得溶液分散体分别特别富含双层或三层石墨烯。由于该过程仅需要温和的超声处理，因此可以生成面积高达 50 µm(2) 的石墨烯薄片。此外，薄片的电子性质优于其他基于溶液的方法所达到的性质；例如，未经退火的样品的电阻率低至约 1 kΩ，空穴迁移率高达约 400 cm(2) V(-1) s(-1)。基于溶液的工艺有望实现高通量生产、功能化以及将样品转移到任意衬底上。
