SPECTRAL NARROWING PHENOMENA IN THE EMISSION FROM A CONJUGATED POLYMER

We report a study of the morphology dependent emission properties of a liquid crystalline polyfluorene in solid thin films. Spectral narrowi ng (SN) is observed in spin coated films, but after thermal treatment of the same films the SN is no longer observed. For films which are sp in coated on a rubbed polyimide alignment layer, the situation is diff erent. There is then no influence of thermal treatment on the observat ion of SN. However, specific combinations of the pump polarization dir ection, film alignment direction and the long axis of the rectangular excitation res now play an important role. The spectral location of SN peaks also varies with film morphology and for different regions of t he same sample. The occurrence of SN is strongly dependent on film mor phology and the excitation configuration. (C) 1998 Elsevier Science B. V.