Gain dynamics in oriented thin films of an oligo(para-phenylene vinylene)

Summary form only given. Numerous factors which govern the efficiency of the stimulated emission process in thin films of electroluminescent conjugated oligomers are related to the structural properties of the materials. Among them the effects of molecular orientation are of major interest. It is indeed fundamental to know whether an ordered phase of oligomers is necessary to walkover the threshold of the stimulated emission. We study the role of the molecular orientation by investigating the photo-excited states dynamics of crystalline thin films of the 5-ring n-octyloxy-substituted oligo(p-phenylene vinylene) (Ooct-OPV5) with femtosecond pump-probe spectroscopy. In particular we compare the emission properties and gain dynamics of two categories of crystalline films characterized by different degrees of structural disorder.