SKM 2021 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 11: Organic Electronics and Photovoltaics, Electrical and Optical Properties (joint session CPP/KFM)
KFM 11.4: Talk
Thursday, September 30, 2021, 14:30–14:45, H3
Dynamics in polymer-fullerene blends for photovoltaic applications and the influence of performance enhancing measures — •Dominik M. Schwaiger1, Wiebke Lohstroh2, and Peter Müller-Buschbaum1,2 — 1Technische Universität München, Physik-Department, Lehrstuhl für Funktionelle Materialien James-Franck-Straße 1, 85748 Garching, Germany — 2Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstraße 1, 85748 Garching, Germany
In organic photovoltaics, donor - acceptor bulk heterojunctions are often used as active layer due to their superior performance compared to e.g. planar structured devices. In this optically active polymer layer, photons are absorbed, excitons are created, subsequently dissipated at a material interface and hence free charges are provided. A promising low-bandgap electron donor material is the conjugated polymer PTB7. Besides a large number of studies on structure and electrical properties, the level of knowledge about dynamics in this system is very limited. We investigated films of PTB7, the fullerene derivate PCBM and different blends of these two, prepared out of chlorobenzene solutions. Quasielastic neutron scattering experiments were done at the cold neutron time of flight spectrometer TOFTOF (MLZ, Garching) to determine hydrogen dynamics on a pico- to nanosecond timescale. In addition, two well established techniques for performance enhancement in organic photovoltaics, namely the addition of DIO to the casting solution and a methanol posttreatment of the active layer, are applied and their influence on the polymer dynamics is investigated.