Dresden 2014 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 50: Organic semiconductors: Material properties (jointly with HL, CPP)
DS 50.9: Vortrag
Freitag, 4. April 2014, 12:15–12:30, POT 051
Polymer aggregation control in polymer: PCBM bulk heterojunctions adapted from solution — •Christian Kästner1, Daniel Egbe2, and Harald Hoppe1 — 1Ilmenau University of Technology, Ilmenau, Germany — 2Linz Institute for Organic Solar Cells, Linz, Austria
It is common knowledge that the polymer conformation and its phase separation with fullerene derivatives are delicate issues crucially impacting on the photovoltaic parameters of polymer based solar cells. Whereas strongly intermixed polymer:fullerene phases provide large interfacial area and consequently a high quantum efficiency of exciton dissociation, pristine and primarily ordered polymer and fullerene domains support efficient charge transport and percolation. To study the aggregation and phase separation in polymer solar cells we investigated counterbalancing influences of polymer solution concentration and PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) blending ratio on the basis of a semi-crystalline anthracene-containing poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene) (PPE-PPV) copolymer statistically bearing either branched 2-ethylhexyloxy or linear octyloxy side-chains (AnE-PVstat). The polymer aggregation varied with both, solution and PCBM concentrations, yielding a specific maximum within the parameter range. We explicitly demonstrate the counterbalancing effect on charge generation and transport for increasing polymer aggregation. Furthermore the influence of polymer aggregation on fundamental optoelectronic properties is discussed, providing detailed understanding of resulting photovoltaic parameters.