Electrical percolation in graphene–polymer composites

Marsden, Alexander J.; Papageorgiou, Dimitrios G.; Vallés, Cristina; Liscio, Andrea; Palermo, Vincenzo; Bissett, Mark A.; Young, Robert J.; Kinloch, Ian A.

doi:10.1088/2053-1583/aac055

Cited by 318 publications

(260 citation statements)

References 205 publications

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“…[68] Independent follow-up studies demonstrated even larger enhancement in the thermal transport properties of composites at lower loading fractions (≈5 vol%). [87,88] A possibility of preparing composites with graphene loading exceeding the electrical percolation threshold is important for designing the EMI shielding materials. The FLG filler can perform better than SLG filler even though it has lower intrinsic thermal conductivity.…”

Section: Introductionmentioning

confidence: 99%

Dual‐Functional Graphene Composites for Electromagnetic Shielding and Thermal Management

Kargar

Barani

Balinskiy

et al. 2018

Adv Elect Materials

201

132

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and environment. [12][13][14] The current industrial and safety standards require blocking of more than 99% of the EM radiation from any electronic devices. [1,[15][16][17] From the other side, the operation of the electronic devices can be disrupted by the outside EM waves. The heat and EM radiation have an inherent connection-absorption of EM waves by any material results in its heating. The energy from EM wave transfers to electrons and then to phonons-quanta of crystal lattice vibrations. The conventional approach for handling the heat and EM radiation problems is based on utilization of the thermal interface materials (TIM), which can spread the heat, and electromagnetic interference (EMI) shielding materials, which can protect from EM waves. These two types of materials have different, and, often, opposite characteristics, e.g., excellent EMI material can be a poor heat conductor, while efficient TIM can utilize electrically nonconductive fillers, resulting in its transparency for EM waves. Here, we propose a concept of the "dual-functional" EMI shielding-TIM materials, and demonstrate it on the example of graphene composites.It is well known that EMI shielding requires interaction of the EM waves with the charge carriers inside the material so that EM radiation is reflected or absorbed. For this reason, the EMI shielding material must be electrically conductive or contain electrically conductive fillers, although a high electrical conductivity is not required. The bulk electrical resistivity on the order of 1 Ω cm is sufficient for most of EMI shielding applications. [1,3,15] Most of the polymer-based materials widely used as TIMs in electronic packaging are electrically insulating and, therefore, transmit EM waves. Conventionally, metal particles are added as fillers in high volume fractions to the base polymer matrix in order to increase the electrical conductivity and prevent EM wave propagation from the device to the environment and vice versa. [1,[18][19][20][21] However, the polymer-metal composites suffer from high weight, cost, and corrosion, which make them an undesirable choice for the state-of-the-art downscaled electronics. Several studies reported the use of carbon fibers, [22][23][24][25][26][27][28][29] carbon black, [30,31] bulk graphite, [32][33][34] carbon nanotubes (CNT), [16,17,[35][36][37][38][39] reduced graphene oxide (rGO), [2,6,[40][41][42][43][44][45][46][47][48][49][50] graphene, [51][52][53][54] and combination of carbon allotropes with orThe synthesis and characterization of epoxy-based composites with few-layer graphene fillers, which are capable of dual-functional applications, are reported. It is found that composites with certain types of few-layer graphene fillers reveal an efficient total electromagnetic interference shielding, SE tot ≈ 45 dB, in the important X-band frequency range, f = 8.2 −12.4 GHz, while simultaneously providing high thermal conductivity, K ≈ 8 W m −1 K −1 , which is a factor of ×35 larger than that of the base matrix material. The efficiency of the d...

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Section: Introductionmentioning

confidence: 99%

Dual‐Functional Graphene Composites for Electromagnetic Shielding and Thermal Management

Kargar

Barani

Balinskiy

et al. 2018

Adv Elect Materials

201

132

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“…These parameters were calculated from the transconductance curves ( I DS ‐ V GS ) (Figures a, S3 and S4) using standard transistor model in saturation regime . The mobility exhibits a characteristic S‐shape dependence on the GNP loading, with a 40x increase with the GNPs concentration, from 5.8×10 −4 cm 2 V −1 s −1 in pure polymer to a plateau of 2.3×10 −2 cm 2 V −1 s −1 when the GNP concentration ranges between 1.6 % and 3.2 %. These results are consistent with previously described studies on similar composites .…”

Section: Resultsmentioning

confidence: 99%

“…Despite such excellent transport properties, their application as semiconductor in electronics is hampered by the absence of a band gap, which is mandatory to control charge mobility, and it is essential for any logic application . However, composites of OSPs and GNPs can exhibit mutually beneficial effects, as they combine both semiconducting behavior of the polymers and enhanced charge transport characteristics of graphene . A typical demonstration of graphene/organic semiconductor heterojunction was previously realized as a highly photosensitive material due to strong absorption of organic semiconductor .…”

Section: Introductionmentioning

confidence: 99%

“…Highly conducting GNPs form a partially bridged network in a less conducting polymer matrix. Depending on the form and organization of GNPs in the polymer matrix, different concentrations of GNPs are required to achieve an efficient percolation threshold . As GNPs loading is decreased, the distance between GNPs is increasing and GNPs become disconnected.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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This paper describes a study on the charge transport in a composite of liquid‐exfoliated graphene nanoparticles (GNPs) and a polythiophene semiconducting polymer. While the former component is highly conducting, although it consists of isolated nanostructures, the latter offers an efficient charge transport path between the individual GNPs within the film, overall yielding enhanced charge transport properties of the resulting bi‐component system. The electrical characteristics of the composite layers were investigated by means of measurements of time‐of‐flight photoconductivity and transconductance in field‐effect transistors. In order to analyze both phenomena separately, charge density and charge mobility contributions to the conductivity were singled out. With the increasing GNP concentration, the charge mobility was found to increase, thereby reducing the time spent by the carriers on the polymer chains. In addition, for GNP loading above 0.2 % (wt.), an increase of free charge density was observed that highlights an additional key role played by doping. Variable‐range hopping model of a mixed two‐ and three‐dimensional transport is explained using temperature dependence of mobility and free charge density. The temperature variation of free charge density was related to the electron transfer from polythiophene to GNP, with an energy barrier of 24 meV.

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“…This has a limited effect on the capacitance but inevitably serves to increase the electrical conductivity. There are various theories to these ends including the jamming and percolation theories relevant to both magnetorheological fluids and polymer composites . The jamming theory has also been investigated specifically for shear thickening organo‐silicon oxide polymers .…”

Section: Discussionmentioning

confidence: 99%

Electrical Properties of Magnetoactive Boron‐Organo‐Silicon Oxide Polymers

Monkman

Striegl

Prem

et al. 2020

Macro Chemistry & Physics

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The electrical properties of rheopectic magnetoactive composites comprising boron‐organo‐silicon oxide dielectric matrices containing carbonyl iron microparticles are presented for the first time. The increase in interfacial magnetocapacitance is seen to greatly exceed that experienced when using conventional elastomeric matrices such as polydimethylsiloxane. In addition to the increase in capacitance, a simultaneous and sharp decrease in the parallel electrical resistance over several orders of magnitude is also observed. The effects are time dependent but repeatable. Potential applications include magnetically controlled frequency dependent devices, magnetic sensor systems, weighting elements for neural networks, etc.

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Electrical percolation in graphene–polymer composites

Cited by 318 publications

References 205 publications

Dual‐Functional Graphene Composites for Electromagnetic Shielding and Thermal Management

Dual‐Functional Graphene Composites for Electromagnetic Shielding and Thermal Management

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

Electrical Properties of Magnetoactive Boron‐Organo‐Silicon Oxide Polymers

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