Mechanism of conductivity in molecular systems and polymer nanocomposites

Abstract

A model is considered in which the characteristics of polymer nonocomposites based on poly(p-xylylene) are observed due to the formation of large percolation clusters consisting of semiconductor or metal nonoparticles, and to electron transfer from the surfaces of clusters on -C6H4- phenyl rings. It is assumed that an electrical double layer is formed near a cluster’s surface, accompanied by the appearance of excess electrons in the polymer matrix as components of -C6H 4 − - ion resonance. It is shown that a metallic cluster in the polymer matrix is oxidized following an increase in its electrostatic potential. This could be explained by the notable reduction in the oxidation of nanocomposite metallic clusters by atmospheric oxygen and water molecules. Upon the formation of semiconductor clusters in poly(p-xylylene) nanocomposite, conductivity is observed due to the hopping mechanism. The extra electron of the −C6H 4 − - anion resonance in the electric field jumps to another ring. The hopping character of nanocomposite conductivity is explained for the case of small nanoparticle concentrations using the Mott model. Precise equations from percolation cluster theory are used to explain the nonmonotonic dependency of nanocomposite photoconductivity on the concentration of semiconductor nanoparticles.