Exciton diffusion, annihilation and their role in the charge carrier generation in fluorene based copolymers

► Exciton annihilation in PSF-BT films starts at 10 times higher intensity than in F8BT films. ► Exciton annihilation facilitates charge carrier generation in F8BF films. ► No influence of exciton annihilation on the carrier generation was observed in PFS-BT films. ► Exciton annihilation in PSF-BT films only speeds up formation of the ICT state.