CHARGE TRANSPORT, CHARGE INJECTION AND BREAKDOWN IN POLYMERIC INSULATORS

A molecular approach is taken to describe charge transport and charge injection in insulating polymers. Localized acceptor and donor states are shown to develop from the energy bands of a regular polymer chain when polymer morphology is taken into account. Charge transport then requires resonance tunnelling between reduced and oxidized states and an important factor is the reorganization energy accompanying localization. The same processes, which are of an electrochemical nature, are used to describe electron transfer across electrode-polymer interfaces. The approach satisfactorily predicts low- and high-field conductivities and is compatible with electrostatic contact-charging phenomena. It also illuminates the likely initiatory stages of electrical and water tree formations at breakdown fields. A satisfying result is that similar models may be used to describe both insulating and ’synthetic metal ’ polymers at opposite ends of the conductivity spectrum. © 1990 IOP Publishing Ltd.