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.

Fluorescent J-aggregates of cyanine dyes: basic research and applications review

“…The fact that individual J-aggregates can be coupled into interacting ensemble allows realizing a new attractive possibility for observing and enhancing the effects of fluorescence superquenching [153] in application of optical sensors [212] (see also section 13.3). However, in densely assembled J-aggregate systems the strong spontaneous quenching is also possible due to trapping of fast migrating exciton by a non-luminescent trap [165]. Such traps can also be introduced artificially [213].…”

“…Their formation is often facilitated by the enhanced ability of dyes to aggregate on preformed scaffolds, and this property is actively explored in the particle design. Such scaffolds could be the polymer molecules [165] and nanoparticles formed of them [166,167], semiconductor QDs [168,169], orthovandate nanocrystals [170]. The J-aggregates are readily assembled on the surface of mica [171].…”

Porphyrin nanorods-polymer composites for solar radiation harvesting applications

“…The porphyrin nanorods spectrum showed two additional Q-bands at longerwavelength region as compared to the precursor spectra which showed single absorbance peak in the region. The Soret band was red shifted whereas the Q-bands remained similar and this may be attributed to stronger exciton coupling causing a shift of the Soret band during porphyrin molecules aggregation [62]. The broadening of the J-aggregate bands is an indication that a large number of porphyrin molecules played a part in the formation of aggregates.…”

The synthesis and optical properties of novel triphenylamine containing 1,3,4-oxadiazole derivatives

“…Now, red-shift of fluorescence emission spectra, the presence of a sharp red shifted band in fluorescence excitation spectra and the emergence of a fast component in the fluorescence decay all indicate the predominance of head to tail (J-type) aggregation with increasing concentration. J-aggregation has important consequences as J-aggregates of dyes are promising candidates for various opto-electronic applications [36,37].…”