Anisotropy of exciton migration in poly(p-phenylene vinylene)

The dynamics of the exciton transport in poly(p-phenylene vinylene) (PPV) blended with a low concentration of fullerene molecules is monitored by time-resolved photoluminescence measurements. The diffusion driven motion of excitons toward these scavengers is modeled using a theory based on a random walk of a particle on lattice sites with traps. From this analysis an exciton diffusion constant of (4 +/- 0.5)x10(-4) cm(2)/s and a diffusion length of 7 nm are obtained. These exciton transport parameters are equivalent to results obtained in bilayer polymer/fullerene heterostructures, demonstrating that the exciton dynamics in PPV are dominated by a one-dimensional migration perpendicular to the film.