Properties of Injected Charge Carriers at Intermittent and Permanent Polystyrene/Metal Interfaces

The electric and electrostatic properties of polymers with negligible intrinsic charge carrier concentration are determined by the ratio of injection of excess charge carriers, e.g. from a metal electrode, to the rate of charge transport. Both, injection and transport of charge carriers are affected by polymer specific interface parameters, e.g. energy level of the polymer band gap states, barrier heights between these levels, band bending situations, orientation and dipole relaxation in the bulk near the surface, as well as experimental parameters like work function of the contacting metal, contact ratio and contact frequency. The resulting space charge and dipole orientation distribution near polymer metal interfaces, which is concentrated within a region smaller than 1 ¿m near the polymer surface, is measured experimentally and calculated by simple model assumptions. Experimental results of two different experimental techniques which are intermittent contact electrification and electrical field effect are compared and commonly discussed under these viewpoints.