Department of Applied Physics, 'Gleb Wataghin' Institute of Physics, University of Campinas-UNICAMP, 13083-970, Campinas, SP, Brazil.
Nanotechnology. 2017 Dec 8;28(49):495711. doi: 10.1088/1361-6528/aa91c2.
Graphene is a breakthrough 2D material due to its unique mechanical, electrical, and thermal properties, with considerable responsiveness in real applications. However, the coverage of large areas with pristine graphene is a challenge and graphene derivatives have been alternatively exploited to produce hybrid and composite materials that allow for new developments, considering also the handling of large areas using distinct methodologies. For electronic applications there is significant interest in the investigation of the electrical properties of graphene derivatives and related composites to determine whether the characteristic 2D charge transport of pristine graphene is preserved. Here, we report a systematic study of the charge transport mechanisms of reduced graphene oxide chemically functionalized with sodium polystyrene sulfonate (PSS), named as GPSS. GPSS was produced either as quantum dots (QDs) or nanoplatelets (NPLs), being further nanostructured with poly(diallyldimethylammonium chloride) through the layer-by-layer (LbL) assembly to produce graphene nanocomposites with molecular level control. Current-voltage (I-V) measurements indicated a meticulous growth of the LbL nanostructures onto gold interdigitated electrodes (IDEs), with a space-charge-limited current dominated by a Mott-variable range hopping mechanism. A 2D intra-planar conduction within the GPSS nanostructure was observed, which resulted in effective charge carrier mobility (μ) of 4.7 cm V s for the QDs and 34.7 cm V s for the NPLs. The LbL assemblies together with the dimension of the materials (QDs or NPLs) were favorably used for the fine tuning and control of the charge carrier mobility inside the LbL nanostructures. Such 2D charge conduction mechanism and high μ values inside an interlocked multilayered assembly containing graphene-based nanocomposites are of great interest for organic devices and functionalization of interfaces.
石墨烯是一种突破性的二维材料，具有独特的机械、电气和热性能，在实际应用中具有相当大的响应能力。然而，大面积覆盖纯净石墨烯是一个挑战，因此人们转而利用石墨烯衍生物来制备允许新发展的混合和复合材料，同时考虑使用不同方法处理大面积。对于电子应用，人们对研究石墨烯衍生物和相关复合材料的电学性质非常感兴趣，以确定纯净石墨烯的特征二维电荷输运是否得到保留。在这里，我们报告了对经过化学功能化的氧化石墨烯（即 GPSS）的电荷输运机制的系统研究，该氧化石墨烯与聚苯乙烯磺酸钠（PSS）发生反应。GPSS 可以制成量子点（QDs）或纳米片（NPLs），然后通过层层自组装（LbL）进一步与聚二烯丙基二甲基氯化铵（PDDA）纳米结构化，以生产具有分子水平控制的石墨烯纳米复合材料。电流-电压（I-V）测量表明，LbL 纳米结构在金叉指电极（IDE）上精细生长，受 Mott 变程跳跃机制控制的空间电荷限制电流占主导地位。在 GPSS 纳米结构内观察到二维层内传导，导致 QDs 的有效载流子迁移率（μ）为 4.7 cm V s，而 NPLs 的μ为 34.7 cm V s。LbL 组装以及材料的尺寸（QDs 或 NPLs）可用于微调和控制 LbL 纳米结构内的载流子迁移率。这种 2D 电荷传导机制和高μ值在含有基于石墨烯的纳米复合材料的互锁多层组装体中非常有趣，可用于有机器件和界面功能化。
