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Interplay of Hopping and Percolation in Organic Conducting Blends
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2000
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EngineeringOrganic ElectronicsChemistryThermal ConductivityConducting PolymerPolymer PhysicTransport PhenomenaThermodynamicsThermal ConductionScaling LawCharge Carrier TransportPolymer ChemistryMaterials SciencePhysicsOrganic SemiconductorPhysical ChemistryContinuous Percolation ModelElectrical PercolationElectronic MaterialsNatural SciencesPolymer ScienceApplied PhysicsOrganic Conducting Blends
Electronic transport properties of organic conductive blends made of doped poly(aniline) and poly(methyl methacrylate) are studied as a function of the conductive phase fraction p and the temperature T. As p is varied, the scaling law of electrical percolation, σ ∝ (p — pc)t, is obeyed by the dc conductivity σ with a single value of pc = 0.07% for a wide range of temperatures. Conversely, the conductivity exponent t increases monotonically from 1.4 to 4.3 as T decreases. At constant p, the thermal dependence of σ is described by the superposition of a metallic part and a hopping part. In the hopping law, ln σ ∝ —(T0/T)γ, the exponent is p dependent. Considering a wide and T dependent distribution of local conductances, we may explain the non-canonical behavior of exponents t (continuous percolation model) and γ.