Ultrafast Dynamics of Polythiophene with Phenyl Vinylene Branches Studied by Femtosecond Fluorescence Spectroscopy in Solution

Two polythiophene based polymers, poly(3-2-4-(2-ethyl-hexyloxy)-phenyl-vinyl-thiophene)-co-thiophene (PT1) and poly(3-2-4-(2-ethyl-hexyloxy)-phenyl-vinyl-thiophene) (PT2), are synthesized and investigated by static, picosecond fluorescence spectroscopies and the femtosecond up-conversion technique in solution. Compared with pristine poly(3-hexylthiophene) (P3HT), PT1 and PT2, in which the main chains are decorated with phenyl vinylene present a 'camel back' structure in the absorption spectra. Phenyl vinylene side chains induce a new process of charge transfer, chain twisting motion and defect-induced fluorescence quenching at time scales of 1 ps, 10 ps and 150 ps, respectively.