Conductivity scaling with bundle length and diameter in single walled carbon nanotube networks

Hecht, David S.; Hu, Liangbing; Grüner, G.

doi:10.1063/1.2356999

Cited by 304 publications

(289 citation statements)

References 17 publications

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“…Moreover, it is also clear that higher network conductance values are achieved when the film is composed of nanotubes with larger aspect ratios. The dependence of the film conductance on the aspect ratio of individual nanotubes is in agreement with previous experimental studies [31,32]. One possible way to account for this trend is to consider that, on average, a longer nanotube will have a larger distance between its junctions with other tubes.…”

Section: Multiscale Model Of Cnt Networksupporting

confidence: 77%

Electronic transport on carbon nanotube networks: A multiscale computational approach

Pereira

Ferreira

2011

Nano Communication Networks

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Carbon nanotube networks are one of the candidate materials to function as malleable, transparent, conducting films, with the technologically promising application of being used as flexible electronic displays. Nanotubes disorderly distributed in a film offers many possible paths for charge carriers to travel across the entire system, but the theoretical description of how this charge transport occurs is rather challenging for involving a combination of intrinsic nanotube properties with network morphology aspects. Here we attempt to describe the transport properties of such films in two different length scales. Firstly, from a purely macroscopic point of view we carry out a geometrical analysis that shows how the network connectivity depends on the nanotube concentration and on their respective aspect ratio. Once this is done, we are able to calculate the resistivity of a heavily disordered networked film. Comparison with experiment offers us a way to infer about the junction resistance between neighbouring nanotubes. Furthermore, in order to guide the frantic search for high-conductivity films of nanotube networks, we turn to the microscopic scale where we have developed a computationally efficient way for calculating the ballistic transport across these networks. While the ballistic transport is probably not capable of describing the observed transport properties of these films, it is undoubtedly useful in establishing an upper value for their conductivity. This can serve as a guideline in how much room there is for improving the conductivity of such networks.

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Section: Multiscale Model Of Cnt Networksupporting

confidence: 77%

Electronic transport on carbon nanotube networks: A multiscale computational approach

Pereira

Ferreira

2011

Nano Communication Networks

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“…This latter phenomenon is not unexpected. Hecht et al 21 recently predicted that the conductivity of thin NT film should scale approximately as 1 / D 2 , a result based on an analysis of the dependence of the number of junctions in a system on the level of bundling.…”

Section: A Film Characterizationmentioning

confidence: 99%

The relationship between network morphology and conductivity in nanotube films

Lyons

Blighe

et al. 2008

Journal of Applied Physics

127

121

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We have characterized both the direct current conductivity and morphology of a wide range of films made from bundled nanotubes, produced by a selection of commercial suppliers. The conductivity increases with increasing nanotube graphitization but decreases with increasing film porosity P and mean bundle diameter ͗D͘. Computational studies show that the network conductivity is expected to scale linearly with the number density of interbundle junctions. A simple expression is derived to relate the junction number density to the porosity and mean bundle diameter. Plotting the experimental network conductivities versus the junction number density calculated from porosity and bundle diameter shows an approximate linear relationship. Such a linear relationship implies that the conductivity scales quadratically with the nanotube volume fraction, reminiscent of percolation theory. More importantly it shows the conductivity to scale with ͗D͘ −3 . Well-defined scaling with diameter and porosity allows the calculation of a specific conductivity expected for films with porosity of 50% and mean bundle diameter of 2 nm. This predicted specific conductivity scales well with the level of nanotube graphitization, reaching values as high as 1.5ϫ 10 7 S / m for well graphitized HiPCO single walled nanotubes.

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“…The use of enriched metallic SWNT populations and purification through ultracentrifugation inevitably result in good electrical performance of SWNT networks through minimising both the semiconductor-metal junction density and disorder [7]. The high inter-bundle contact resistance is the main obstacle to enhancement of the electrical performance of SWNT networks [5,6]. Inter-bundle contact resistances can be minimised by careful removal of residual surfactant [11].…”

Section: Introductionmentioning

confidence: 99%

“…Consequently there are large energy barriers at metal-semiconductor interfaces and disorder is introduced by the impurities and processing. Therefore, both the electrical transport within the bundle and the inter-bundle contact resistance has greatest influence on the electrical transport within the network as a whole [5,6]. Solution processing typically requires the use of surfactants which can adversely impact on inter-tube resistance.…”

Section: Introductionmentioning

confidence: 99%

High electrical conductance enhancement in Au-nanoparticle decorated sparse single-wall carbon nanotube networks

McAndrew

Baxendale

2013

Nanotechnology

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We report high electrical conductivity enhancement in sparse single-walled carbon nanotube networks by decoration with Au nanoparticles. The optimised hybrid network exhibited a sheet resistance of 650 /sq: 1/1500 of the resistance of the host undecorated network, with a negligible optical transmission penalty (>90% transmittance at 550 nm wavelength). The electrical transport at room temperature in host and decorated networks was dominated by 2-dimensional variable range hopping.The high conductance enhancement was due to positive charge transfer from the decorating Au nanoparticles in intimate contact with the host network causing a Fermi energy shift into the high density of states at a van Hove singularity and enhanced electron delocalisation relative to the host network which beneficially modifies the hopping parameters in such a way that the network behaves as an integral whole. The effect is most pronounced when the nanoparticle diameter is comparable to the electron mean free path in the bulk material at room temperature and there is minimum nanoparticle agglomeration. For higher than optimal values of nanoparticles per unit area or nanoparticle diameter, the conductivity enhancement is countered by metallic inclusions in the current pathways that are of higher resistance than the VRH-controlled elements.

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Conductivity scaling with bundle length and diameter in single walled carbon nanotube networks

Cited by 304 publications

References 17 publications

Electronic transport on carbon nanotube networks: A multiscale computational approach

Electronic transport on carbon nanotube networks: A multiscale computational approach

The relationship between network morphology and conductivity in nanotube films

High electrical conductance enhancement in Au-nanoparticle decorated sparse single-wall carbon nanotube networks

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