Conclusion: Biomimetic Light-Harvesting

Abstract

It could be shown that the biomimetic self-assembling P2 aggregates have suitable properties for applications in solar cells. They self-assemble to J-aggregates, which have a highly ordered crystalline structure, what could be inferred from XRD and TEM investigations, their exciton coupling in the UV-Vis-NIR absorption spectra and also their ability to fluoresce in the solid-state. A high mean exciton lifetime in the J-aggregates of 40 ps, could be measured by time-resolved fluorescence spectroscopy in cooperation with the group of Prof. Heinz Kalt at the KIT. With the dielectrophoresis technique new possibilities for the manipulation and alignment of P2 aggregates were demonstrated which can be used for characterizations like photoconductivity measurements, for sorting or for the deposition of such structures on solar cell substrates for example. The photoconductivity measurements showed promising optoelectronic properties, which might be useful also for other applications beside solar cells, like sensors, or for energy or data storage for example, as the aggregates seem to have a high capacity. The HOMO and LUMO levels could be successfully determined, proving a suitable fit to the conduction band edge of TiO₂ and to the common hole transport material spiro-MeOTAD, which will be described in the next section.