Nanoscale Detection of Interfacial Charge Mobility in BaTiO₃/Polyvinylidene Fluoride Nanocomposites

Polymer-based dielectric composites with inorganic oxide fillers could exhibit synergistic physical and chemical characteristics from both advantages, which have flexible applications in electrical and electronic technology. As composites with various substances, the interfacial structure plays a key role in the electric and dielectric properties. In this work, BaTiO3 particles were embedded in polyvinylidene fluoride (PVDF) by a solution crystallization process. The conductivity and dielectric constant of the composites increased with the increase of the BaTiO3 filler contents. The charge injection and dissipation behavior at the nanointerface of the composite is investigated by Kelvin probe force microscopy. It is found that the charges are more easily injected into the nanointerface between the particle and the polymer. The accumulation and dissipation of surface charges obey the exponential law. The space-charge polarization is also suggested to be a key factor of injection, while the charge dissipation is determined by charge tunneling. The result also demonstrates that the strong interfacial polarization between the BaTiO3 particles and the PVDF matrix plays a crucial role in the dielectric properties. This work provides significant insights into understanding the interfacial charge transport in dielectric composites.