AC properties of poly(paraphenylene-vinylene) thin films

We present the results of the dielectric measurements performed in polyphenylene-vinylene thin films in sandwich structures between two metallic electrodes. Analysis of the data shows that two relaxation mechanisms occurs in these structures: a bulk mechanism at middle and high frequency ranges and a contact mechanism at low frquencies. The strong dispersion due to polymer-metal contact suggests that a simple representation of the potential barrier cannot be applied to these structures.