Coherent Energy and Charge Transport Processes in Oligothiophene Dendrimers Probed in Solution and in the Solid State with Time-Resolved Spectroscopy and Microscopy Methods

Dendritic molecules demonstrate a broad variety of transfer processes under different geometric and coupling regimes, which can be utilized in photovoltaic applications. Coherent energy and charge transfer processes were investigated in different oligothiophene dendritic systems functionalized with diketopyrrolopyrrole groups in solution and in the solid phase. For the first time, high-resolution time-resolved spectroscopy and interferometric microscopy techniques have been compared to investigate ultrafast coherent dynamics. Investigation of coherent dynamics in photovoltaic organic materials is important as related to longer exciton diffusion length in organic macromolecules. Differences in the excited-state coherent dynamics have been found in films compared to the solution phase. Interestingly, the dendron structure has shown higher charge delocalization in the solid phase compared to the dendrimer system because of stronger intra- and intermolecular couplings occurring in dendrons. These findings could be used to improve the potential of this class of organic macromolecules for light-harvesting applications.