THE EFFECT OF BROKEN CONJUGATION AND AGGREGATION ON PHOTOINDUCED 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 micro wave conductivity. Gel formation resulting from aggregation of polymer chains in some of the solutions leads to an increase in the photo-ind uced conductivity. The effects are attributed to the formation of mobi le charge carriers (polaron pairs) on a single polymer chain in the ca se of the solutions, and on separate chains via interchain charge tran sfer in the gel. Mobile charge carrier formation is strongly reduced b y the incorporation of even a few percent of non-conjugated ethylidene units in the polymer backbone.