Fluorescence and anisotropy dynamics of a CHO substituted terthiophene

We report steady-state spectroscopic and femtosecond time resolved fluorescence and anisotropy measurements on a CHO substituted terthiophene in order to study the effect of aggregates on its properties. Aggregates are formed in concentrated solutions causing a broadening and a red-shift of the absorption and fluorescence spectra. Terthiophene molecules exhibit a fluorescence lifetime of 250 ps while in the presence of aggregates the fluorescence dynamics are governed by rapid energy transfer from the isolated terthiophene molecules to the aggregates within 10 ps. Finally, anisotropy dynamics in concentrated solution exhibit a slower decay than in dilute solution, which is related to the existence of aggregates.