Abstract
Supramolecular assemblies from organic dyes forming J‐aggregates are known to exhibit narrowband photoluminescence with full‐width at half maximum of ≈9 nm (260 cm−1). Applications of these high color purity emitters, however, are hampered by the rather low photoluminescence quantum yields reported for cyanine J‐aggregates, even when formed in solution. Here, it is demonstrated that cyanine J‐aggregates can reach an order of magnitude higher photoluminescence quantum yield (increase from 5% to 60%) in blend solutions of water and alkylamines at room temperature. By means of time‐resolved photoluminescence studies, an increase in the exciton lifetime as a result of the suppression of non‐radiative processes is shown. Small‐angle neutron scattering studies suggest a necessary condition for the formation of such highly emissive J‐aggregates: the presence of a sharp water/amine interface for J‐aggregate assembly and the coexistence of nanoscale‐sized water and amine domains to restrict the J‐aggregate size and solubilize monomers, respectively.
Highlights
This page was generated automatically upon download from the ETH Zurich Research Collection
We investigated solutions of Jaggregates in water, J-aggregates in water after adding HA following the experiments of Section 2.1, and solutions made with a different sequence: dye was added to a D2O/HA/dye for one composition (D2O/HA) blend after the microemulsion had formed
To link the formation of emissive J-aggregates to the microemulsion morphology, it is most instructive to look at the water/HA blend as this blend shows a large variety of morphologies which we probed with small-angle neutron scattering (SANS) (Figure 3b)
Summary
This page was generated automatically upon download from the ETH Zurich Research Collection. Supramolecular assemblies from organic dyes forming J-aggregates are a long history in science and technology[1] and have recently attracted interest in known to exhibit narrowband photoluminescence with full-width at half the field of polariton lasers,[2] organic maximum of ≈9 nm (260 cm−1). Applications of these high color purity emitters, are hampered by the rather low photoluminescence quantum yields reported for cyanine J-aggregates, even when formed in solution. It can be recognized though that many applications of J-aggregate forming dyes are not making use of their PL properties, which may explain why sharp water/amine interface for J-aggregate assembly and the coexistence of only a limited number of research deals nanoscale-sized water and amine domains to restrict the J-aggregate size and solubilize monomers, respectively
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