Percolation and conductivity: A computer study. I

Pike, G. E.; Seager, C. H.

doi:10.1103/physrevb.10.1421

Cited by 963 publications

(466 citation statements)

References 23 publications

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“…The calculated values of V c are inversely proportional to ℓ/D, which is an intuitive result and is in agreement with previous theoretical predictions [14,16,17].…”

Section: Applicationsupporting

confidence: 79%

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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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“…The calculated values of V c are inversely proportional to ℓ/D, which is an intuitive result and is in agreement with previous theoretical predictions [14,16,17].…”

Section: Applicationsupporting

confidence: 79%

“…for networks with a volume fraction considerably larger than the critical value V c , the conductance is found to increase linearly with V f [14,15].…”

Section: Applicationmentioning

confidence: 92%

Electronic transport on carbon nanotube networks: A multiscale computational approach

Pereira

Ferreira

2011

Nano Communication Networks

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“…5 For B c , a value of 2.8 was used. 15 In Fig. 6, the experimental J-V measurements for the MEH-PPV hole-only diodes with different thicknesses are shown ͑symbols͒.…”

Section: ͑1͒mentioning

confidence: 99%

Diffusion-enhanced hole transport in thin polymer light-emitting diodes

2008

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Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The transport of holes in polymer light-emitting diodes ͑PLEDs͒ based on poly͑2-methoxy, 5-͑2Ј ethylhexyloxy͒-p-phenylene vinylene͒ ͑MEH-PPV͒ is investigated as a function of layer thickness. For thicknesses smaller than 100 nm, the current in these thin PLEDs is strongly enhanced as compared to the expected space-charge limited ͑SCL͒ current. Applying the standard SCL model to measurements on a PLED with a thickness of only 40 nm results in an apparent increase of the hole mobility of a factor of 40. We show that this strong increase of the hole transport properties in these thin devices originates from the presence of an Ohmic hole contact. For Fermi-level alignment, holes diffuse from the contact into the MEH-PPV, forming an accumulation layer with a width of a few tens of nanometers. Due to the density dependence of the mobility, the hole transport in this accumulation region is strongly enhanced. For the analysis of thin PLEDs, it is therefore essential that both drift and diffusion of charge carriers are taken into account.

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“…52,65,66 For all these models, φ c ∝ 1/λ for long slender rods, both in and out of equilibrium and independent of spatial dimension. 61 Equilibrium statistical mechanics predicts an exponential decrease in φ c at moderate attraction. 63,64,67 For strong attraction (w p ≃ 20-40k B T ) and large aspect ratio (λ ≃ 500-1000) such theories predict unphysical values for φ c , many orders of magnitude too small.…”

Section: B Scaling Electronic Type and Film Durabilitymentioning

confidence: 99%

Empirical evaluation of attractive van der Waals potentials for type-purified single-walled carbon nanotubes

et al. 2012

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Van der Waals forces play a critical role in the structure and stability of single-wall carbon nanotube (SWCNT) materials. Thin films assembled from SWCNTs purified by electronic type show particular promise for flexible electronics applications, but mechanical durability remains an unresolved issue. Using transition resonances determined from spectroscopic measurements of typepurified SWCNTs deposited on quartz, coupled with analogous spectroscopic characterization of polydimethylsiloxane (PDMS) substrates, we use the Lifshitz theory of van der Waals dispersion interactions developed by Rajter and co-workers [R. F. Rajter et. al., Phys. Rev. B 76, 045417 (2007)] to examine the influence of electronic type on van der Waals contact potentials in polymer supported nanotube networks. Our results suggest a significantly stronger nanotube-nanotube and nanotube-polymer attraction for the semiconducting SWCNT fractions, consistent with recent measurements of the electronic durability of flexible transparent SWCNT coatings.PACS numbers: 61.48. De, 78.67.Ch, 82.35.Np, 78.20.Bh 2 I. INTRODUCTIONVan der Waals (vdW) forces play a significant role in the structural stability of matter across a broad range of chemistry, physics, and biology. 1-6 They also play a particularly important role in nanotechnology, where they dominate the short-range attraction between nanoparticles and can hinder their dispersion and manipulation. [7][8][9][10][11] For particles lacking a permanent dipole moment, vdW dispersion forces arise solely from small fluctuations in the electromagnetic field -or more precisely, the dielectric permittivity -across the space between the particles, 12,13 which is dominated by the zero-point energy of quantum vacuum fluctuations. The quantum-field nature of such a mundane, ubiquitous and sometimes macroscopic force is quite remarkable, if on occasion not fully appreciated.Single-wall carbon nanotubes (SWCNTs) are nanometer thick tubes of graphene 100 nm to 100 µm in length. They can be either metallic or semiconducting, depending on the chiral vector (n, m) that characterizes the symmetry of rolling a 2D graphene sheet into a hollow tube. 14 They are one of the most studied materials within the realm of modern nanotechnology, with exceptional physical properties that herald the possibility of significant technological potential. 15 The importance of vdW forces in SWCNT materials cannot be overstated. The high aspect ratio and strong anisotropy create potential wells thousands of k B T in depth, but SWCNTs have yet to realize their full potential as mechanical reinforcing agents. This is primarily due to the mechanical failure of interfacial contacts, which are largely governed by vdW forces. Although chemical crosslinking can help mitigate such effects, this often occurs at the expense of the intrinsic SWCNT properties of interest, 16 which can limit the potential impact of applications.Raw nanotube materials typically contain a broad distribution of lengths and a mixture of the two distinct electronic species...

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Percolation and conductivity: A computer study. I

Cited by 963 publications

References 23 publications

Electronic transport on carbon nanotube networks: A multiscale computational approach

Electronic transport on carbon nanotube networks: A multiscale computational approach

Diffusion-enhanced hole transport in thin polymer light-emitting diodes

Empirical evaluation of attractive van der Waals potentials for type-purified single-walled carbon nanotubes

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