Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 790-784, Republic of Korea.
Nano Carbon Materials Research Group, Korea Electrotechnology Research Institute , Changwon 641-120, Republic of Korea.
ACS Appl Mater Interfaces. 2016 Feb 10;8(5):3193-9. doi: 10.1021/acsami.5b10704. Epub 2016 Jan 29.
The size of chemically modified graphene nanosheets is a critical parameter that affects their performance and applications. Here, we show that the lateral size of graphene oxide (GO) nanosheets is strongly correlated with the concentration of graphite oxide present in the suspension as graphite oxide is exfoliated by sonication. The size of the GO nanosheets increased from less than 100 nm to several micrometers as the concentration of graphite oxide in the suspension was increased up to a critical concentration. An investigation of the evaporation behavior of the GO nanosheet solution using inkjet printing revealed that the critical temperature of formation of a uniform film, T(c), was lower for the large GO nanosheets than for the small GO nanosheets. This difference was attributed to the interactions between the two-dimensional structures of GO nanosheets and the substrate as well as the interactions among the GO nanosheets. Furthermore, we fabricated organic thin film transistors (OTFTs) using line-patterned reduced GO as electrodes. The OTFTs displayed different electrical performances, depending on the graphene sheet size. We believe that our new strategy to control the size of GO nanosheets and our findings about the colloidal and electrical properties of size-controlled GO nanosheets will be very effective to fabricate graphene based printed electronics.
化学修饰石墨烯纳米片的尺寸是一个关键参数，它会影响其性能和应用。在这里，我们表明氧化石墨烯（GO）纳米片的尺寸与悬浮液中存在的氧化石墨浓度密切相关，因为氧化石墨在超声作用下会被剥离。随着悬浮液中氧化石墨浓度的增加，GO 纳米片的尺寸从小于 100nm 增加到几微米，直至达到一个临界浓度。通过喷墨打印研究 GO 纳米片溶液的蒸发行为，我们发现大的 GO 纳米片形成均匀薄膜的临界温度 T(c)比小的 GO 纳米片低。这种差异归因于 GO 纳米片的二维结构与基底之间的相互作用以及 GO 纳米片之间的相互作用。此外，我们使用线图案化的还原氧化石墨烯作为电极来制造有机薄膜晶体管（OTFT）。OTFT 的电性能取决于石墨烯片的尺寸。我们相信，我们控制 GO 纳米片尺寸的新策略以及我们对尺寸控制的 GO 纳米片胶体和电学性质的发现，将非常有效地制造基于石墨烯的印刷电子产品。
