Near-term aging and thermal behavior of polyfluorene in various aggregation states
Steady-stage photoluminescence and photoabsorption have been used to characterize the impact of
aggregation in various poly( di- n - alkylﬂuorene) thin ﬁlms. Highly aggregated ﬁlms exhibit
systematic changes in the photoluminescence while aging. These are indicative of a gradual increase
in interchain interactions. Nonaggregated ﬁlms do not exhibit this behavior. However the
mesomorphic properties are altered and these ﬁlms undergo irreversible changes on thermal cycling.
All these properties appear to be correlated with changes in the local short-range molecular