Excitons, polarons, and laser action in poly(p-phenylene vinylene) films

A multitude of optical cw spectroscopies were used to study the long-lived neutral and charged photoexcitations in PPV thin films, as well as laser action in both thin films and microcavities. It was found that the linear absorption at the main π-π* transition cannot be completely explained by involving a single CL distribution; a bimodal CL distribution better explains the shape of absorption band I. The low-energy tail of the optical absorption was shown to extend far in their region. However, the much higher absorption tail usually measured by optical transmissions is due to scattering in the PPV microcrystals.