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Transport in Organic Solar Cells

We intend to develop a fundamental understanding of charge transfer and charge transport in organic solar cells. For this purpose we will employ suitable EPR-based techniques. In particular, we will develop the experimental method of transient electrically detected magnetic resonance (transient EDMR). Combining the sensitivity of EDMR and the time resolution of transient EPR will provide us with the possibility to systematically investigate the interplay between charge transfer states, which are generated upon photoexcitation and subsequent charge transfer between donor and acceptor, and the photocurrent in polymer:fullerene blends.

This project is part of the DFG Schwerpunktprogramm 1601 on “New Frontiers in Sensitivity für EPR Spectroscopy: From Biological Cells to Nano Materials”.

Contact: Jan Behrends
Felix Kraffert

Charge Separation in Hybrid Solar Cells

Hybrid solar cells made from organic and inorganic semiconductors open up the opportunity for future photovoltaic devices with high efficiency and comparably low production costs. The combination of (nanostructured) inorganic and organic semiconductors is particularly promising, because the advantages of both material classes may be combined. However, the efficiencies of today’s hybrid solar cells are usually well below the efficiencies of purely inorganic solar cells and cells comprising solely inorganic absorber materials. A key point is the generally inefficient charge separation, i.e. the conversion of photogenerated excitons into separated electrons and holes at the hybrid interface.

Within the framework of a Helmholtz Energie-Allianz we collaborate with scientists from the Helmholtz-Zentrum Berlin, the Forschungszentrum Jülich, the Humboldt university and the Potsdam university to develop “inorganic/organic hybrid solar cells and techniques for photovoltaics“. Our research activities are focused on understanding the processes resulting in exciton dissociation and charge separation at the hybrid interface between inorganic semiconductors (ZnO, CIGS, Si) and polymers or small organic molecules.

Contact: Jan Behrends
Robert Steyrleuthner (AG Bittl)

EPR characterisation of organic materials for photovoltaics and optoelectronics

We aim to advance and use EPR spectroscopy for the characterisation of organic molecules and materials for application in the fields of photovoltaics and optoelectronics. By exploiting a multi-frequency continuous-wave and pulse EPR approach, we aspire to identify correlations between the molecular structure of organic semiconductors and other organic functional materials and their electronic and magnetic properties. Advanced pulse EPR will be used to identify the nature of paramagnetic species in organic materials and characterise interactions with their molecular environment.

This project is part of a Marie Skłodowska Curie fellowship financed by the EU commission through the Horizon 2020 initiative.

Contact: Jan Behrends
Claudia Tait

More detailed information will be available soon.