Berlin 2005 – wissenschaftliches Programm
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SYOO: Organic Optoelectronics and Photonics
SYOO 5: Optoelectronic Devices
SYOO 5.2: Vortrag
Montag, 7. März 2005, 17:30–17:45, TU HE101
Recent progress on the way to high efficiency organic stacked p-i-n solar cells — •M. Pfeiffer1, C. Uhrich1, R. Schüppel1, A. Petrich1, J. Drechsel1, B. Maennig1, K. Leo1, and P. Bäuerle2 — 1Institut für Angewandte Photophysik, TU Dresden, Germany — 2Abteilung Organische Chemie II und Sektion Massenspektrometrie, Universität Ulm, Germany
We have recently introduced organic solar cells based on a p-i-n heterostructure where a photoactive layer is embedded between doped organic layers with high conductivity and wide band gap. Such cells reach internal quantum efficiencies around 80%. With a tandem cell comprising two p-i-n diodes with a blend of ZnPc and C60 as active layer, we achieve an AM 1.5 power efficiency of 3.7+/-0.2%. To reach even higher values, we have to incorporate additional photoactive layers with absorption spectra complementary to ZnPc and improve the ratio of optical gap and open circuit voltage. Therefore, we developed a new class of acceptor-type oligomers with strong absorption in the green featuring excellent pi-stacking and low Stokes-shift. Heterojunctions of such an oligomer with a TPD-derivative as donor show efficient charge separation and open-circuit voltages of up to 0.9V. These results suggest that tandem cell efficiencies in excess of 5% can soon be achieved. Moreover, we present a new concept for organic solar cells based on light absorption by an oligomer, singlet transfer to C60, inter-system crossing to the triplet and back transfer of the triplet to the oligomer leading to long lived triplet excitons that can diffuse to an exciton separating interface.