Percolation threshold and electrical conductivity of graphene-based nanocomposites with filler agglomeration and interfacial tunneling

Abstract

The dispersion state or degree of agglomeration of graphene is known to have a significant influence on the percolation threshold and electrical conductivity of graphene-based polymer nanocomposites. In addition, an imperfectly conducting interface and tunneling-assisted interfacial conductivity can also affect the overall conductivity. In this paper, a continuum theory is developed that considers all these factors. We first present a two-scale composite model consisting of graphene-rich regions serving as the agglomerates and a graphene-poor region as the matrix. We then introduce the effective-medium theory to determine the percolation threshold and electrical conductivity of the agglomerate and the composite. To account for the effect of imperfect interfaces, a thin layer of interphase with low conductivity is introduced to build a thinly coated graphene, while to account for the contribution of electron hopping from one graphene to another, Cauchy's statistical function which can reflect the increased tunneling activity near the percolation threshold is introduced. It is shown that the percolation threshold of the nanocomposite is controlled by two dispersion parameters, a and b, and the aspect ratio of agglomerates, αR. It is also shown that the overall conductivity of the nanocomposite mainly depends on the intrinsic conductivity of graphene and polymer matrix, the intrinsic interfacial resistivity, and the tunneling-assisted hopping process. We highlight the conceived theory by demonstrating that a set of recently measured data on the percolation threshold and electrical conductivity of graphene/polystyrene nanocomposites can be well captured by it.

Enhancement of Charge Transport in Polythiophene Semiconducting Polymer by Blending with Graphene Nanoparticles

“…V TH could also potentially increase because at higher density GNPs start to form interconnected percolation pathways, as reported previously . For a random distribution of a semimetallic GNPs in a polymer matrix, a conducting network could be formed with relatively small polymer regions between adjacent GNPs.…”

“…V TH could also potentially increase because at higher density GNPs start to form interconnected percolation pathways, as reported previously. [29,30] For a random distribution of a semimetallic GNPs in a polymer matrix, a conducting network could be formed with relatively small polymer regions between adjacent GNPs. In such polymer interfaces, the transconductivity is still modulated by V GS , presumably with modified V TH , although semimetallic GNPs exhibit no V GS modulation.…”

Fabrication of SiC‐Treated P(VDF‐HFP)‐(BFO‐SO3H) Composite Films for High Performance Energy Storage Device (HPESD) Applications

“…When we move to a higher frequency range, the dielectric values will be significantly different as compared to starting frequency range (100 Hz), hence we choose an intermediate frequency range 1000 Hz for percolation study in reference to Bhadra et al It can be observed from Figure (a) that the dielectric constant of the composite is about 37 when the filler content is 15 wt.% but reaches to maximum i.e., 54 when the SiC loading is 20 wt.% and this sudden increase in the constant value from 15 wt.% is the value for percolation threshold. Actually, the minimum volume wt.% of the conducting filler at which there is a significant change in dielectric constant/electrical conductivity of the sample occurred is referred to as the percolation threshold …”

Modeling and Simulation of Graphene Based Polymer Nanocomposites: Advances in the Last Decade

“…The percolation threshold should be as low as possible in order to decrease the use of graphene. The dispersion state or degree of agglomeration of graphene is known to have a significant influence on the percolation threshold and electrical conductivity of GBPNCs [190]. The key factors influencing the percolation threshold include, dispersion state, physicochemical interactions between the matrix and the reinforcement, shape of the reinforcement, and method to produce nanocomposite.…”