Novel highly conductive and transparent graphene-based conductors.
Novel highly conductive and transparent graphene-based conductors.
复制标题
DOI：
10.1002/adma.201200489
复制
发表时间：
2012-06-05
影响因子：
29.4
通讯作者：
Craciun, Monica F.
中科院分区：
文献类型：
--
作者：
Khrapach, Ivan;Withers, Freddie;Bointon, Thomas H.;Polyushkin, Dmitry K.;Barnes, William L.;Russo, Saverio;Craciun, Monica F.
未来的可穿戴电子设备、显示器和光伏器件除了需要导电和光学透明之外，还需要机械柔性、轻质和低成本的材料。[1-3]如今，氧化铟锡（ITO）是光电应用中最广泛的透明导体，然而这种材料的机械刚性限制了其在未来柔性器件中的应用。在寻找新型透明导体的竞赛中，石墨烯单层和多层是领先的候选者，因为它们有潜力满足所有未来的需求。石墨烯，一个原子厚的碳原子层，是透明的，[4]导电，[5，6]可弯曲[7]，也是已知最强的材料之一。[8]然而，使用石墨烯作为真正的透明导体仍然是一个巨大的挑战，因为迄今为止证明的其薄层电阻（Rs）的最低值高于市售ITO的值（即在光学透射率Tr= 85%时为10 Ω/□ [9]）。目前，许多努力集中在降低石墨烯基材料的Rs，同时保持高Tr，这将允许它们的潜力在光电应用中得到利用。迄今为止，在石墨烯基材料中发现的薄层电阻和透射率的最佳值仍然远未达到ITO的性能，对于石墨烯多层[7，12]，在Tr= 90%时的典型值为Rs = 30 Ω/□，对于化学掺杂的石墨烯，在Tr= 97.7%时的典型值为Rs = 125 Ω/□。[7，10，11]在这里，我们报告了新型石墨烯基透明导体，其在Tr= 84%时的薄层电阻为8.8 Ω/□，载流子密度高达8.9× 1014 cm − 2，室温载流子平均自由程高达10.6 μm。这些材料是通过用氯化铁（FeCl 3）插入少层石墨烯（FLG）而获得的。[13通过电传输和光传输测量的组合研究，我们证明了FeCl 3增强了FLG的电导率，同时使这些石墨烯基材料高度透明。我们还表明，FeCl 3-FLG在空气中稳定长达一年，这表明了这些材料用于工业生产透明导体的潜力。迄今为止，在任何其他掺杂石墨烯系统中还没有证明创纪录的低薄层电阻、高光学透明度和宏观室温平均自由程的独特组合，并且为石墨烯基光电子学开辟了新的途径。通过在玻璃或SiO2/Si上对天然石墨进行微机械裂解[5]，获得了从2层到5层（2L到5L）的原始FLG。通过光学对比度和拉曼光谱法确定组成每个FLG的层数（参见支持信息）。采用双区气相传输法在真空中进行了FeCl 3的插层过程。[15]FeCl 3在最低温度区升华，并扩散到发生FLG插层的较高温度区（见实验部分）。的结构，电学和光学特性进行了三个互补的实验技术：低温电荷传输，光学传输和拉曼光谱。
Future wearable electronics, displays and photovoltaic devices require materials which are mechanically flexible, lightweight and low-cost, in addition to being electrically conductive and optically transparent.[1–3] Nowadays indium tin oxide (ITO) is the most wide spread transparent conductor in optoelectronic applications, however the mechanical rigidity of this material limits its use for future flexible devices. In the race to find novel transparent conductors, graphene monolayers and multilayers are the leading candidates as they have the potential to satisfy all future requirements. Graphene, one-atom-thick layer of carbon atoms, is transparent,[4] conducting,[5, 6] bendable [7] and yet one of the strongest known materials.[8] However, the use of graphene as a truly transparent conductor remains a great challenge because the lowest values of its sheet resistance (R s) demonstrated so far are above the values of commercially available ITO (ie 10 Ω/□ at an optical transmittance Tr= 85%[9]). Currently many efforts are concentrated on decreasing the R s of graphene-based materials while maintaining a high Tr, which will allow their potential to be harnessed in optoelectronic applications. To date, the best values of sheet resistance and transmittance found in graphene-based materials are still far from the performances of ITO, with typical values of R s= 30 Ω/□ at Tr= 90% for graphene multilayers [7, 12] and R s= 125 Ω/□ at Tr= 97.7% for chemically doped graphene.[7, 10, 11] Here we report novel graphene-based transparent conductors with a sheet resistance of 8.8 Ω/□ at Tr= 84%, a carrier density as high as 8.9× 10 14cm− 2 and a room temperature carrier mean free path as large as∼ 0.6 μm. These materials are obtained by intercalating few-layer graphene (FLG) with ferric chloride (FeCl 3).[13, 14] Through a combined study of electrical transport and optical transmission measurements we demonstrate that FeCl 3 enhances the electrical conductivity of FLG while leaving these graphene-based materials highly transparent. We also show that FeCl 3-FLGs are stable in air up to one year, which demonstrates the potential of these materials for industrial production of transparent conductors. The unique combination of record low sheet resistance, high optical transparency and macroscopic room temperature mean free path has not been demonstrated so far in any other doped graphene system, and opens new avenues for graphene-based optoelectronics.Pristine FLG ranging from two-to five-layers (2L to 5L) were obtained by micromechanical cleavage of natural graphite [5] on glass or SiO 2/Si. The number of layers composing each FLG was determined by optical contrast and Raman spectroscopy (see Supporting Information). The intercalation process with FeCl 3 was performed in vacuum with the two-zone vapor transport method.[15] FeCl 3 is sublimated in the lowest temperature zone and it diffuses to the higher temperature zone where the intercalation of FLG takes place (see Experimental Section). The structural, electrical and optical characterization is carried out by means of three complementary experimental techniques: low-temperature charge transport, optical transmission and Raman spectroscopy.
登录
查看更多内容
影响因子：
8.6
作者：
Efetov, Dmitri K.;Kim, Philip
通讯作者：
Kim, Philip
影响因子：
10.8
作者：
Kim, Namdong;Kim, Kwang S.;Kim, Philip
通讯作者：
Kim, Philip
影响因子：
56.9
作者：
Nair, R. R.;Blake, P.;Geim, A. K.
通讯作者：
Geim, A. K.
FeCl3 插层少层石墨片：费米能级的拉曼测定、逐层解耦和稳定性
影响因子：
15
作者：
Zhao, Weijie;Tan, Ping Heng;Ferrari, Andrea C.
通讯作者：
Ferrari, Andrea C.
影响因子：
3.5
作者：
Kim, Ki Kang;Reina, Alfonso;Kong, Jing
通讯作者：
Kong, Jing