Perylene Bisimide Foldamer π-Stacks for Long-lived Charge Separation

• Applicant: Professor Dr. Frank Würthner
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation ; Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 566112440

Pi-stacks are important functional units as they provide percolation pathways for excitons and charges. However, owing to the synthetic challenges involved in the covalent synthesis of structurally defined pi-stacks only a very limited number of studies are available on foldamer-type pi-stacks and their functional properties. Most insights into “through-stack” charge transport accordingly originate either from three-dimensional solid materials or from inhomogeneous self-assembled pi-stacks. The objectives of this project are to develop a synthetic methodology for the formation of structurally defined pi-stacks composed of perylene bisimide (PBI) dyes, the unambiguous characterization of their structure and the evaluation of such stacks for photo-induced electron transport along the pi-stacked supramolecular wire. To realize these goals, we will synthesize a series of pi-stacked PBI oligomers from dimer up to dodecamer. End-group functionalization with electron-donor and electron-acceptor substituted PBIs will endow these oligomers with a gradient, enabling the formation of charge separated states upon photoexcitation of either donor, bridge or acceptor subunits. By means of time-resolved transient absorption spectroscopy we will elucidate the time required for the formation of charge separated states and subsequent charge carrier recombination in dependence of the number of pi-stacked PBIs as a charge-transporting bridge. The results obtained for “through-stack” charge carrier transport for the folded pi-stacks will be compared with data available for pi-conjugated molecular wires and for solid state organic semiconductor materials.

• DFG Programme: Research Grants
• International Connection: South Korea
• Cooperation Partner: Professor Dr. Dongho Kim