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

Abstract

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 $(4\pm 0.5)\times {10}^{-4}{\mathrm{cm}}^2∕\mathrm{s}$ and a diffusion length of $7\mathrm{nm}$ 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.