Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 16: Interfaces and Thin Films II (joint session with DECHEMA and VDI)

CPP 16.4: Vortrag

Dienstag, 12. März 2013, 10:30–10:45, H40

Determination of the inner morphology of organic solar cells with grazing incidence small angle neutron scattering — Matthias A. Ruderer¹, Robert Meier¹, Lionel Porcar², Robert Cubitt², and •Peter Müller-Buschbaum¹ — ¹TU München, Physik Department, LS Funktionelle Materialien, James-Franck-Str. 1, 85748 Garching, Germany — ²Institut Laue Langevin (ILL), 6 Jules Horowitz, 38042 Grenoble, France

Organic photovoltaic devices based on conducting polymers are of increasing interest. The device efficiency of an organic solar cell is determined by the inner morphology of the active layer. However, such inner morphologies are not easily detectable by real space imaging methods such as electron microscopy. In contrast, grazing incidence small angle neutron scattering (GISANS) is a unique tool for the characterization of the active layer morphology, in particular for donor-acceptor systems with polymer donor and small molecule acceptor blends. The scattering length density contrast in such blends is typically large, which makes special deuteration dispensable and real systems can be studied. For the example of P3HT:PCBM bulk heterojunction thin films the inner morphology is determined with GISANS. The phase separation structure and the amount of molecular intermixing are investigated as a function of the overall PCBM content. For the symmetric P3HT:PCBM ratio, which is typically highly efficient in photovoltaic devices, a structure size in the range of the exciton diffusion length, the largest PCBM phases and 18 vol% dispersed PCBM in the amorphous P3HT phase are found.