On the role of spectral diffusion of excitons in sensitized photoconduction in conjugated polymers

An analytical model describing the kinetics of relaxed exciton dissociation into charge carriers is developed. It is based on the assumption that the dissociation of relaxed excitons occurs only on charge transfer centers and the dissociation rate is controlled by the probability for an exciton to encounter a charge transfer center in the course of spectral diffusion. Since the exciton jump rate decreases faster than the exciton density the characteristic time of the carrier photogeneration turns out to be shorter than the exciton lifetime. The developed model is used in order to fit experimental data on the kinetics of charge photogeneration.