Berlin 2005 – wissenschaftliches Programm
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SYOO: Organic Optoelectronics and Photonics
SYOO 6: Poster
SYOO 6.21: Poster
Montag, 7. März 2005, 18:00–20:00, Poster TU A
Organic thin-film photovoltaic cells based on low gap thiophene oligomers — •Christian Uhrich1, Rico Schüppel1, Anette Petrich1, Dr. Martin Pfeiffer1, Prof. Dr. Karl Leo1 und Prof. Dr. Peter Bäuerle2 — 1Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden — 2Abteilung Organische Chemie II und Sektion Massenspektrometrie, Universität Ulm, 89081 Ulm
The best polymeric solar cells reported so far are based on a so called bulk heterojunction of polythiophene as a donor and a soluble fullerene derivative as an acceptor. However, these cells still suffer from an unsatisfying photovoltage typically below 0.6V. Here, we show that we can achieve higher photovoltages using a new thiophene based oligomer comprising electron withdrawing groups that increase both the ionization energy and even more strongly the electron affinity of the compound. The new material is tested in MIP-type cells using a photoactive heterojunction to separate the excitons generated in the oligomer and a p-doped wide-gap transport layer. First solar cells show an open-circuit-voltage of above 0.8 V, fill factors around 50 % and a broad spectral sensitivity band starting at 650nm. The dynamics of excitons and photogenerated charge carriers in the photoactive layers is studied by photoinduced absorption spectroscopy (PIA) and time-resolved fluorescence spectroscopy. Solar cells based on such thiophene oligomers have the potential of high power efficiencies up to 3 % and are promising candidates for stacked PIN-type organic solar cells tailored to the sun-spectrum.