Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 30: Poster: Organic Electronics and Photovoltaics

CPP 30.32: Poster

Dienstag, 8. März 2016, 18:15–21:00, Poster B2

The effect of the fullerene LUMO position on the CT properties in polymer:fullerene blends — •Tobias Thiede, Jona Kurpiers, and Dieter Neher — Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Germany

In bulk heterojunction organic solar cells, one of the key parameters in solar cell efficiency, the open circuit voltage, has been shown to depend on the properties of the charge transfer (CT) state. These properties are again related to the energy gap between the highest occupied molecular orbital (HOMO) of the polymer and the lowest unoccupied molecular orbital (LUMO) of the fullerene acceptor. We present sensitive electroluminescence (EL) and external quantum efficiency (EQE) experiments on binary blends made of fluorinated copolymer 1F-PCPDTBT combined with the fullerene of different LUMO energy. By moving the LUMO of the fullerene we observe distinct changes in the absorption and emission properties. In particular, a significant increase of the EL efficiency accompanied by the appearance of emission from singlet excitons is seen when increasing the LUMO energy, as in blends with ICBA and ICTA. At the same time, the Voc loss due to non-radiative recombination is largely reduced. These findings help to understand the fundamental role of the energy landscape at the donor:acceptor interface and have important implications for designing future materials systems.