|Wittmann, B.; Wenzel, F.A.; Wiesneth, S.; Haedler, A.T.; Drechsler, M.; Kreger, K.; Köhler, J.; Meijer, E.W.; Schmidt, H.-W.; Hildner, Richard: Enhancing Long-Range Energy Transport in Supramolecular Architectures by Tailoring Coherence Properties, Journal of the American Chemical Society 142(18), 8323-30 (2020) -- DOI: 10.1021/jacs.0c01392|
Efficient long-range energy transport along supramolecular architectures of functional organic molecules is a key step in nature for converting sunlight into a useful form of energy. Understanding and manipulating these transport processes on a molecular and supramolecular scale is a long-standing goal. However, the realization of a well-defined system that allows for tuning morphology and electronic properties as well as for resolution of transport in space and time is challenging. Here we show how the excited-state energy landscape and thus the coherence characteristics of electronic excitations can be modified by the hierarchical level of H-type supramolecular architectures. We visualize, at room temperature, long-range incoherent transport of delocalized singlet excitons on pico- to nanosecond time scales in single supramolecular nanofibers and bundles of nanofibers. Increasing the degree of coherence, i.e., exciton delocalization, via supramolecular architectures enhances exciton diffusivities up to 1 order of magnitude. In particular, we find that single supramolecular nanofibers exhibit the highest diffusivities reported for H-aggregates so far.