Abstract

The photophysics of conjugated polymers have been intensely studied in the hope that they will provide insight into the electronic structure and dynamics of these materials. Conjugated polymers are often considered as an inhomogeneous collection of weakly-coupled chain segments, among which energy can be transferred via a Forster mechanism [1]. In this model, aggregation leads primarily to nonradiative traps for the luminescent Frenkel excitons. We have made a detailed study of the photodynamics of the prototypical conjugated polymer poly(p-phenylene vinylene) (PPV) and have found that the effects of aggregation are more complex, and not as detrimental as previously thought [2]. In the disordered environment of a polymer film, there is a mix of species, from amorphous regions of isolated molecules to aggregates consisting of hundreds of molecules. Both powder x-ray diffraction and transmission electron microscopy confirm the existence of these different domains in PPV. Our experimental data indicates that it is the nanocrystalline aggregates that are largely responsible for PPV’s luminescence properties.

© 2002 Optical Society of America