Regensburg 2010 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 27: Poster: Organic Electronics and Photovoltaics

CPP 27.16: Poster

Mittwoch, 24. März 2010, 17:30–19:00, Poster C

Substituted Perylene Diimides as Electron Acceptors in Organic Solar Cells: Suppressing aggregate and formation to increase device efficiency — •Valentin Kamm, Ian A. Howard, Chen Li, Klaus Müllen, and Frédéric Laquai — Max-Planck-Institut für Polymerforschung, Mainz, Deutschland

Perylene diimide (PDI) is a promising candidate as electron acceptor material for high open circuit voltage organic solar cells. Its strong absorption in the visible region combined with high electron mobility in the solid state renders it a potential alternative to the weakly absorbing PCBM that is typically used in state-of-the-art organic solar cells. However, PDI molecules tend to aggregate and form intermolecular excited states that can act as exciton traps. These traps effectively limit the diffusion of excitons to the interface where charge separation occurs and thus strongly reduce the charge generation efficiency in bulk heterojunction solar cells.

We investigate the effect of different bulky side groups attached to the terminal and to the bay positions of PDI molecules on the formation of aggregates by time-resolved optical spectroscopy. In particular transient photoluminescence and transient absorption spectroscopy are used to study, whether the increased spacing between the PDI molecules, caused by the bulky side groups, can prevent aggregation and intermolecular excited state formation leading to more efficient exciton transport. Furthermore, we correlate the photophysical properties of these materials with the efficiency of bulk heterojunction organic solar cells.