Strongly interacting organic conjugated dendrimers with enhanced two-photon absorption

We report a strongly interacting new dendrimer system with an extended spectroscopic unit (coherent domain) beyond the trimer configuration. This report focuses on the mechanism of enhancement of the two-photon absorption (TPA) response of this material as a function of the dendrimer generation number. This enhancement is strongly correlated to the size and geometry of the spectroscopic unit in a strongly interacting macromolecular system. These systems are investigated by a wide variety of time-resolved spectroscopy methods including time-resolved fluorescence, transient absorption, three-pulse photon echo peak shift measurements as well as TPA cross section measurements. The extensive combination of modern spectroscopic methods strongly indicates that the spectroscopic unit (domain) in high generations covers the G1 (nine linear building blocks) and exceeds the trimer size.