Author:

Keywords:

layer alternate assemblies, mixed j-aggregate, cyanine dyes, excited-state, optical-properties, energy-transfer, thiacarbocyanine dyes, charged surfaces, sensitizing dyes, frenkel exciton, Science & Technology, Life Sciences & Biomedicine, Physical Sciences, Biochemistry & Molecular Biology, Biophysics, Chemistry, Physical, Chemistry, MIXED J-AGGREGATE, CYANINE DYES, OPTICAL-PROPERTIES, EXCITED-STATE, ENERGY-TRANSFER, THIACARBOCYANINE DYES, SENSITIZING DYES, 2 KINDS, FLUORESCENCE, FILMS, 0299 Other Physical Sciences, 0306 Physical Chemistry (incl. Structural), 0601 Biochemistry and Cell Biology, Organic Chemistry, 3406 Physical chemistry, 4004 Chemical engineering

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.