title: Comparison between J-aggregates in a self-assembled multilayer and polymer-bound J-aggregates in solution: a steady-state and time-resolved spectroscopic study.
abstract: The self-assembly of a thiacarbocyanine dye on a charged substrate via the layer-by-layer alternate adsorption technique was studied in detail. The influence of the chemical structure of the oppositely charged polyelectrolyte (PEL) in the multilayer on J-aggregate formation was investigated by means of absorption spectroscopy and steady-state and time-resolved fluorescence spectroscopy. J-Aggregates were formed yielding a bathochromic narrow absorption band. Fine tuning of the position of the absorption band is possible by incorporating other polyelectrolytes in the multilayer. The results obtained for the dye-polyelectrolyte multilayers were compared with measurements made on the aqueous dye-polyelectrolyte mixtures. The parameters obtained by fitting the fluorescence decays to several different models allowed us to suggest a mechanism for the non-radiative decay channel. The low fluorescence quantum yields and fast non-exponential fluorescence decays obtained for both the dye-polyelectrolyte multilayers and the aqueous dye polyelectrolyte mixtures were attributed to the trapping of a fast migrating exciton by a non-luminescent trap. The results related to J-aggregate formation, decay time and dimensionality of the aggregates were compared in solution and in a self-assembled multilayer.
authors.affiliation: Katholieke Universiteit Leuven, Department of Chemistry, Laboratory for Photochemistry and Spectroscopy, Celestijnenlaan 200F, 3001-Heverlee (Leuven), Belgium.
authors.forename: Els
authors.initials: E
authors.lastname: Rousseau
authors.forename: Marc M
authors.initials: MM
authors.lastname: Koetse
authors.forename: Mark
authors.initials: M
authors.lastname: Van der Auweraer
authors.forename: Frans C
authors.initials: FC
authors.lastname: De Schryyer