Excitation energy migration assisted processes in conjugated polymers

An important characteristic of thin films of state-of-the-art conjugated polymers and small molecule materials is energetic and morphological disorder. For the photophysics in these electroactive thin films, the disorder has an important consequence: a single and multi-step (migration) excitation energy transfer processes of the charge-neutral states, such as singlet and triplet excitons (TEs) towards lower energetic sites can be observed prior to radiative recombination. Yet as found migration assisted processes, which are rather pronounced in the solid state of organic molecules and conjugated polymers can be held responsible for a large number of nonradiative deactivation channels as they enable quenching at chemical defects or other excited states such as polarons. Furthermore, the ability to migrate enlarges the action radius of singlet excitons (SEs) up to 20nm in the solid state which makes it necessary to include the migration process for describing the overall energy transfer behaviour of conjugated polymers.