The effect of broken conjugation and aggregation on photo-induced charge separation on polyphenylenevinylene chains

Rash photoexcitation of dilute solutions of fully conjugated poly(2,5-dialkoxyphenylenevinylene)s results in a transient change in the microwave conductivity. Gel formation resulting from aggregation of polymer chains in some of the solutions leads to an increase in the photo-induced conductivity. The effects are attributed to the formation of mobile charge carriers (polaron pairs) on a single polymer chain in the case of the solutions, and on separate chains via interchain charge transfer in the gel. Mobile charge carrier formation is strongly reduced by the incorporation of even a few percent of non-conjugated ethylidene units in the polymer backbone.