Exciton-exciton annihilation in poly (p-phenylenevinylene) films

We have measured the saturation of fluorescence intensity with increasing excitation intensity and the time dependence of fluorescence intensity decay at high excitation intensities in poly (p-phenylenevinylene) films. The experimental results are consistent with the hypothesis that exciton-exciton annihilation reduces the exciton lifetime at high exciton concentrations and that the exciton diffusion coefficient is quite high. We conclude that the lowest energy electronic transition creates a Frenkel exciton rather than a free-carrier pair in a band-to-band transition.