A convenient process for generating large-scale, horizontally aligned arrays of pristine, single-walled carbon nanotubes (SWNTs) is described. The approach uses guided growth, by chemical vapor deposition (CVD), of SWNTs on miscut single-crystal quartz substrates. Studies of the growth reveal important relationships between the density and alignment of the tubes, the CVD conditions, and the morphology of the quartz. Electrodes and dielectrics patterned on top of these arrays yield thin-film transistors that use the SWNTs as effective thin-film semiconductors. The ability to build high-performance devices of this type suggests significant promise for large-scale aligned arrays of SWNTs in electronics, sensors, and other applications.

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This paper demonstrates the use of arrays of networks of single wall carbon nanotubes (SWNTs) and electrical breakdown procedures for building thin film transistors (TFTs) that have good, reproducible performance and high current output. Channel length scaling analysis of these TFTs indicates that the resistance at the source/drain contacts is a small fraction of the device resistance, in the linear regime. When measured with the channel exposed to air or coated by poly(methyl methacrylate) (PMMA), these transistors operate in the unipolar p mode. By spin-coating the polymer polyethylenimine (PEI) on the channel region, these transistors can be switched to operate in the unipolar n mode. Patterning the exposure of a single channel to PMMA and PEI yields p−n diodes. These results indicate that SWNT-TFTs can provide the building blocks of complex complementary circuits for a range of applications in macroelectronics, sensors, and other systems.

We report the use of networks of single-walled carbon nanotubes (SWNTs) with high and moderate coverages (measured as number of tubes per unit area) for all of the conducting (i.e., source, drain, and gate electrodes) and semiconducting layers, respectively, of a type of transparent, mechanically flexible, thin-film transistor (TFT). The devices are fabricated on plastic substrates using layer-by-layer transfer printing of SWNT networks grown using optimized chemical vapor deposition (CVD) procedures. The unique properties of the SWNT networks lead to electrical (e.g., good performance on plastic), optical (e.g., transparent at visible wavelengths), and mechanical (e.g., extremely bendable) characteristics in this "all-tube" TFT that would be difficult, or impossible, to achieve with conventional materials.Invisible circuits based on transparent transistors have broad potential applications in consumer, military, and industrial electronic systems. [1,2] In backlit display devices, for example, transparent active-matrix circuits can increase the aperture ratio and battery life. Transparent electronic materials that can be printed on low-cost, flexible, plastic substrates are potentially important for new applications, such as bendable heads-up display devices, see-through structural health monitors, sensors, and steerable antennas. [3][4][5] More advanced systems, such as electronic artificial skins [6] and canopy window displays, will require materials that can also tolerate the high degrees of mechanical flexing (i.e., high strains) needed for integration with complex curvilinear surfaces. Most examples of transparent TFTs (TTFTs) use thin films of inorganic oxides as the semiconducting and conducting layers. [7][8][9] Although the electrical properties of these oxides can be good (mobilities and conductivities as high as 20 cm 2 V -1 s -1[10] and 4.8 × 10 3 X -1 cm -1 , [11] respectively), their mechanical characteristics are not optimally suited for use in flexible and mechanically robust devices. For example, the tensile fracture strains for ZnO and indium tin oxide (ITO) thin films are less than 0.03 % [12] and 1 %, [13] respectively.Aligned arrays [14] or random networks [15,16] of individual SWNTs represent alternative classes of transparent semiconducting and conducting materials. In networks with high coverages of SWNTs, especially when in the form of small bundles, the metallic tubes (normally present with semiconducting tubes in a 1:2 ratio) form a percolating network that behaves like a conducting "film". [17,18] At moderate coverages, only the semiconducting tubes form such a percolating network and the film shows semiconducting properties. [19] Unlike the oxides, the SWNT films have excellent mechanical properties due to their high elastic moduli (1.36-1.76 TP nm/tube diameter nm) [20] and fracture stresses (100-150 GPa) [21] of the tubes. SWNT-based semiconductors have been used in flexible TFTs. [15,[22][23][24] In one case, solution-deposited SWNT networks also formed the gate electrodes. [25] A...

The development of high-performance shielding materials against electromagnetic pollution requires mobile charge carriers and magnetic dipoles. Herein, we meet the challenge by building a three-dimensional (3D) nanostructure consisting of chemically modified graphene/Fe3O4(GF) incorporated polyaniline. Intercalated GF was synthesized by the in situ generation of Fe3O4 nanoparticles in a graphene oxide suspension followed by hydrazine reduction, and further in situ polymerization with aniline to form a polyaniline composite. Spectroscopic analysis demonstrates that the presence of GF hybrid structures facilitates strong polarization due to the formation of a solid-state charge-transfer complex between graphene and polyaniline. This provides proper impedance matching and higher dipole interaction, which leads to the high microwave absorption properties. The higher dielectric loss (ε'' = 30) and magnetic loss (μ'' = 0.2) contribute to the microwave absorption value of 26 dB (>99.7% attenuation), which was found to depend on the concentration of GF in the polyaniline matrix. Moreover, the interactions between Fe3O4, graphene and polyaniline are responsible for superior material characteristics, such as excellent environmental (chemical and thermal) degradation stability and good electric conductivity (as high as 260 S m(-1)).