Dispersive relaxation of photoexcited defects in bipyridine-PPV derivatives measured by photoinduced absorption

We have measured the dynamics of the electronic absorptions of the photoinduced defects in bipyridine-PPV derivatives. Their dependence on the laser pump intensity and modulation frequency reveal evolution in time which can be described by dispersive relaxation behavior. This behavior can be quantified as a mono-molecular recombination process combined with an asymmetric lifetime distribution.