Exciton Delocalization Counteracts the Energy Gap: A New Pathway toward NIR-Emissive Dyes
Artikel i vetenskaplig tidskrift, 2021

Exciton coupling between the transition dipole moments of ordered dyes in supramolecular assemblies, so-called J/H-aggregates, leads to shifted electronic transitions. This can lower the excited state energy, allowing for emission well into the near-infrared regime. However, as we show here, it is not only the excited state energy modifications that J-aggregates can provide. A bay-alkylated quaterrylene was synthesized, which was found to form J-aggregates in 1,1,2,2-tetrachloroethane. A combination of superradiance and a decreased nonradiative relaxation rate made the J-aggregate four times more emissive than the monomeric counterpart. A reduced nonradiative relaxation rate is a nonintuitive consequence following the 180 nm (3300 cm-1) red-shift of the J-aggregate in comparison to the monomeric absorption. However, the energy gap law, which is commonly invoked to rationalize increased nonradiative relaxation rates with increasing emission wavelength, also contains a reorganization energy term. The reorganization energy is highly suppressed in J-aggregates due to exciton delocalization, and the framework of the energy gap law could therefore reproduce our experimental observations. J-Aggregates can thus circumvent the common belief that lowering the excited state energies results in large nonradiative relaxation rates and are thus a pathway toward highly emissive organic dyes in the NIR regime.


Alexei Cravcenco

Göteborgs universitet

Yi Yu

Göteborgs universitet

Fredrik Edhborg

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Jonas F. Goebel

Göteborgs universitet

Zoltan Takacs

Göteborgs universitet

Yizhou Yang

Göteborgs universitet

Bo Albinsson

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Karl Börjesson

Göteborgs universitet

Journal of the American Chemical Society

0002-7863 (ISSN) 1520-5126 (eISSN)

Vol. 143 45 19232-19239


Nanovetenskap och nanoteknik



Fysikalisk kemi




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