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In Advanced Energy Materials (together with the Presselt Group): Controlling Internolecular Interactions at Interfaces!

We demonstrate that a systematic and designated control of supramolecular nanostructures via interfacial engineering enables adjusting (opto)electronic C60-material properties widely. Interestingly, the LUMO energies of the same amphiphilic fullerene species is tuned up to 120 meV using supramolecular assembly, competitive to complete molecular change; cf. PC61BM to PC71BM causes a change of 200 meV. Morphology control was achieved by applying seven 2 different thin film production techniques involving molecular assembly at interfaces, including liquid-liquid interfacial precipitation (LLIP) and Langmuir-Blodgett technique utilizing the air-water interfacial. LLIP enables spatial separation of the fullerenes and extended surfaces, thus yielding the least electronically stabilized LUMO (ELUMO=-4.28 eV). After qualitatively explaining the observed electrochemical LUMO energy variation for these assemblies with varied molecular packing and aggregate dimensions, we proposed an analytical equation that connects morphological parameters with LUMO energies and has prospective application in supramolecular chemistry. To demonstrate applicability of the supramolecular structure-electronic property relations and of the supramolecular structure fabrication protocols established in this work to tailor device properties, we have chosen the example of amorphous-Si/fullerene hybrid solar cells, which were built and characterized. We found that the supramolecular structure variation could be successfully translated to the solar cells, giving rise to a prototype linear relation between LUMO energy and open-circuit voltage.

Original Article:

S. Das, J. Preiß, J. Plentz, U. Brückner, M. von der Lühe, O. Eckardt, A. Dathe, F. H. Schacher, E. Täuscher, U. Ritter, A. Csaki, G. Andrä, B. Dietzek, M. Presselt, "Controlling Intermolecular Interactions at Interfaces: Case of Supramolecular Tuning of Fullerene´s Electronic Structure", Adv. Energy Mater. 2018, in press

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