Dresden 2020 – wissenschaftliches Programm
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CPP 73.7: Vortrag
Mittwoch, 18. März 2020, 18:00–18:15, ZEU 260
Barrierless free charge generation in the high-performance PM6:Y6 bulk heterojunction non-fullerene solar cell — •Lorena Perdigón-Toro1, Huotian Zhang2, Anastasia Markina3, Feng Gao2, Denis Andrienko3, Safa Shoaee1, and Dieter Neher1 — 1Institute of Physics and Astronomy, University of Potsdam, Germany — 2Department of Physics, Chemistry and Biology (IFM), Linköping University, Sweden — 3Max Planck Institute for Polymer Research, Mainz, Germany
Organic solar cells are currently experiencing a second golden age thanks to the development of novel non-fullerene acceptors (NFAs). Surprisingly, some of these blends exhibit high efficiencies despite a low energy offset at the heterojunction. In this work, we investigate photocurrent generation in the high-performance blend of the donor polymer PM6 with the NFA Y6 as a function of internal field and excitation energy by means of time-delayed collection field (TDCF). Results show that generation is essentially barrierless with near-unity efficiency, regardless of excitation energy. Complementary temperature-dependent external quantum efficiency and open-circuit voltage measurements reveal that efficient generation is maintained over a wide temperature range, down to 100 K, despite the small driving force for charge generation. Studies on a blend with a low concentration of the NFA, measurements of the energetic disorder, and theoretical modelling suggest that charge generation is assisted by the electrostatic interfacial field which for Y6 is large enough to compensate the Coulomb dissociation barrier.