Effect of dipole ordering on the electrical properties of the interface between two organic insulators

The “polar catastrophe” hypothesis on the mechanism of the formation of a two-dimensional conducting channel at the interface between two insulators is investigated experimentally. In particular, the influence of the concentration of dipolar groups at one of the surfaces on the electrical conductivity along the interface between two organic polymer insulators is studied. Poly(diphenylene phthalide) with phthalide side groups, possessing a relatively large dipole moment, is used as the polymer. The concentration of dipoles at the surface is varied by adding a low-molecular compound to the material. It is found that the concentration of dipolar groups has a considerable effect on the electrical conductivity along the polymer/polymer interface. A decrease in the conductivity of the interface at high concentrations of the low-molecular additive is explained on the basis of atomic-force microscopy data by the features of the supramolecular structure of the composite and the increasing imperfection of the interface.