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Film morphology and photophysics of polyfluorene
Journal article   Peer reviewed

Film morphology and photophysics of polyfluorene

A J Cadby, P A Lane, H Mellor, S J Martin, M Grell, C Giebeler, DDC Bradley, M Wohlgenannt, C An and Z V Vardeny
Physical review. B, Condensed matter and materials physics, Vol.62(23), pp.15604-15609
12/15/2000
DOI: 10.1103/PhysRevB.62.15604

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Abstract

We have studied the interplay between photophysics and film morphology of poly(9,9-dioctyl)fluorene (PFO) using a variety of optical probes. Upon slowly warming a spin-cast PFO film from 80 to 300 K, a fraction of the sample is transformed into a different solid phase, the beta phase. Absorption and electroabsorption measurements show that the beta phase has more extended conjugation than the glassy phase. As a consequence, excited states of the beta phase are redshifted and have higher polarizability. The photoinduced absorption spectrum of a glassy PFO film is dominated by tripler excitons, whereas both polarons and triplet excitons are seen in a sample containing a fraction of the beta phase. The dependence of the photoinduced absorption and photocurrent upon the excitation wavelength shows that there is a clear link between polaron and triplet photogeneration.
Materials Science Materials Science, Multidisciplinary Physical Sciences Physics Physics, Applied Physics, Condensed Matter Science & Technology Technology

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