Berlin 2008 – wissenschaftliches Programm

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.48: Poster

Dienstag, 26. Februar 2008, 14:30–20:00, Poster A

Optimization of organic thin film photovoltaic cells based on the oligothiophene derivative DCV6T — •David Wynands, Kerstin Schulze, Christian Uhrig, Moritz Riede, and Karl Leo — Institut für angewandte Photophysik, Technische Universität, 01096 Dresden, Germany

We have recently reported on a series of oligothiophene derivatives featuring dicyanovinylene end groups that can be used in combination with C-1ex60 as acceptor material in organic thin film solar cells. The introduction of such electron-accepting groups provides a reduced bandgap and increased ionisation energy compared to the unsubstituted molecule. This allows solar cells with high photovoltages. DCV6T thin films absorb between 450nm and 680nm with an absorption coefficient of α=1.89*101ex5 cm1ex-1 at the maximum (580nm). Using ITO coated glass as substrate and p-doped α-NPD as hole transport layer, we prepare solar cells with flat and bulk heterjunctions between DCV6T and C-1ex60. A Voc of 0.9V is achieved in both cases. We show that by increasing the concentration of DCV6T in the bulk layers currents up to 10 mA/cm1ex2 under 100mW/cm1ex2 simulated sunlight can be reached. However, the fillfactor of 0.45 remains low and has to be improved further. To overcome restrictions of the single cells we also prepared tandem cells that reach efficiencies of 3.4% under 100mW/cm1ex2 simulated sunlight.