The microstructure of and charge transfer in thin films based on metal-polymer nanocomposites

Abstract

Charge transfer in nanostructured metal-polymer composites was studied. The frequency dependences of film conductance and susceptance were obtained at various metal concentrations. The susceptance of samples above the percolation threshold was negligibly small, which corresponded to the purely metallic conductivity type. For samples below the percolation threshold, susceptance and conductance were comparable in magnitude, which was evidence of an important role played by susceptance mechanisms. At low frequencies, the samples behaved as quasi-linear RC circuits and both the active and reactive impedance components increased linearly as the frequency grew. At high frequencies, the dispersion of susceptance, which was inversely proportional to frequency, was observed. The conclusion was drawn that the hopping conductivity mechanism through polymeric matrix surface states prevailed in films below the percolation threshold. At high frequencies, when the applied voltage period was shorter than the characteristic time of surface state recharging, these states began to be eliminated from charge transfer processes. It was suggested that a decrease in the reactive impedance component with an increase in frequency might be the reason for the dispersion observed experimentally.