Exciton Delocalization Counteracts the Energy Gap: A New Pathway toward NIR-Emissive Dyes
Alexei Cravcenco, Yi Yu, Fredrik Edhborg, Jonas F. Goebel, Zoltan Takacs, Yizhou Yang, Bo Albinsson, Karl Börjesson
Abstract
) 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.