Photoexcitations of polycarbazolyldiacetylenes in different time domains

We report on the photoinduced absorption spectra of polycarbazolydiacetylenes polyDCHD and its soluble analogous polyDCHD-S in a broad time domain ranging from femtosecond to millisecond. Both the blue and red forms of polyDCHD-S are investigated and the results are compared with those of blue polyDCHD. In the blue form of the two polymers charged states are detected in the ms domain in addition to triplet excitons. In the red form of polyDCHD-S only triplets are detected. Femtosecond pump and probe measurements allow us to interpret the generation mechanism of the triplet states as due to singlet excitons fission.