New evidence of long-lived photoexcited charged states in thin films of PDA-4BCMU

We report results of steady-state photoinduced absorption experiments on PDA-4BCMU grown on silica substrate. We observe three photoinduced absorption bands at 0.82, 0.95 and 1.39 eV whose relaxation dynamics indicate that the first two are due to charged states while the third is originated by triplet excitons. The photogeneration of both charged and neutral states in PDA-4BCMU previously observed in polycarbazolyldiacetylenes, indicates that this is a general feature of polydiacetylenes. The relative weight of one excited species over the other one is influenced by the molecular and supramolecular organization of the polymer