Percolation-dominated conductivity in a conjugated-polymer-carbon-nanotube composite

Abstract

We have made electrical measurements on a system using carbon nanotubes as the dopant material. A semiconjugated, organic polymer was mixed with carbon nanotubes to form a wholly organic composite. Composite formation from low to high nanotube concentration increases the conductivity dramatically by ten orders of magnitude, indicative of percolative behavior. Effective mobilities were calculated from the spacecharge regions of the current-voltage characteristics for the 0-8 % mass fractions. After an initial rise these were seen to fall from 1-8 % doping levels as predicted by theory. From the values for conductivity and mobility, an effective carrier density was calculated. This was seen to decrease between 0% and 1%, before rising steadily. ͓S0163-1829͑98͒51536-6͔

Electrical transport measurements of highly conductive carbon nanotube/poly(bisphenol A carbonate) composite

“…͑1͒ gives percolation threshold p c = 0.20 wt %, t = 1.39, and 0.19 wt %, t = 0.97 for both acidtreated and pristine nanotubes, respectively, in which the exponent t is related to sample dimensionality, i.e., t Ϸ 1, t Ϸ 1.33, or 2.0 for one, two, or three dimensions, respectively. [31][32][33][34][35][36] The percolation threshold depends not only on polymer/ filler interaction but also on the particles shape of conductive filler, 36,37 particle spatial distribution, and polymer matrix morphology. 36,37 Furthermore, particles shape in conductive fillers depends on what so called packing factor, where the packing factor is defined as the maximum content of filler material in the volume of polymer matrix.…”

Modelling percolation in fibre and sphere mixtures: Routes to more efficient network formation

“…During each Monte Carlo step, the "electron" is displaced randomly to an adjacent fibre, with the acceptance probability of such a move given by equation (6). If the fibres form a percolating network, the virtual "electron" will travel a large distance during its Monte Carlo walk; if not, the "electron" will tend to become trapped in the local pocket of fibres.…”

“…The formation of extended networks of particles dispersed in a fluid gives rise to a discontinuous change in the rheological [1][2][3][4][5] and electrical [6][7][8][9] properties of the dispersion at concentrations around the so-called percolation threshold. Historically, percolation theory was first used by Flory [10] to explain the phenomenon of gelation in thermosetting polymers.…”

Low electrical percolation threshold and PL quenching in solution-blended MWNT–MEH PPV nanocomposites

“…Composites of conducting polymers with carbon nanotubes (CNTs) [1][2][3] have attracted considerable attention in the past few years because of their potential applications in polymer light emitting diodes [4,5], photovoltaic cells and photodiodes [6], field effect transistors [7], optical limiting devices [8], supercapacitors [9], sensors [10], etc. In fact, the extensive and exhaustive applications of CNTs in the field of polymer composites has perhaps exhilarated the scientific community to consider nanotubes as a part of the polymer family [11] rather than as a novel nanotechnology product.…”