Abstract
We have studied the interplay between photophysics and film morphology in poly(9,9-dioctyl fluorene) using a variety of optical probes, including absorption, photoluminescence, and photoinduced absorption. Upon slowly warming a glassy PFD film from 80K to 300K, a fraction of the sample is transformed into a new solid phase, the ß phase. The ß phase has more extended conjugation than the glassy phase. As a consequence, the ß phase excitons are red-shifted and dissociate more easily into long-lived charged polarons.