Dresden 2009 – scientific programme
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SYOP: Symposium Organic Photovoltaics: From Single Molecules to Devices
SYOP 4: Organic Photovoltaics: from Single Molecules to Devices
SYOP 4.48: Poster
Thursday, March 26, 2009, 16:30–19:00, P1A
Photophysical properties of novel small acceptor molecules and their application in hybrid small-molecular/polymeric organic solar cells — Sahika Inal1, •Mauro Castellani1, Alan Sellinger2, and Dieter Neher1 — 1Universität Potsdam, Institut für Physik und Astronomie, 14476 Potsdam-Golm — 2Institute of Materials Research & Engineering, Singapore 117602
Recent experimental investigations revealed that the photovoltaic properties of our devices are related to the balance between recombination and field-induced dissociation of interfacial excited states such as exciplexes or geminate polaron pairs. This balance was shown to be affected by the nanomorphology at the heterojunction [J. Phys. Chem. C 2008, 112, 14607]. We have analyzed the photophysical properties of a new materials couple comprising an electron-donating PPV copolymer and a vinazene-based small molecule acceptor [Chem. Mater. 2007, 19, 1892]. Steady state and time-resolved photoluminescence (PL) spectroscopy in solution and in the solid state showed the formation of excimers within the acceptor. The associated long-range diffusion promise efficient energy harvesting at the heterojunction. On the other hand, blends of the PPV-derivative and the small molecule revealed strong exciplex formation. Therefore, bilayered hybrid small-molecular/polymeric solar cells have been fabricated by consequently spin-coating the macromolecular donor and the small molecule acceptor from two different solvents. The bilayer architecture limits recombination processes enabling high FFs of around 44% and a technologically important open circuit voltage of 1Volt.