Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 27: Photovoltaics: Innovative Material Systems

HL 27.2: Talk

Tuesday, March 27, 2012, 09:45–10:00, ER 270

Colloidal zinc oxide nanoparticles in organic and hybrid photovoltaic applications — •Sebastian Wilken, Dorothea Scheunemann, Verena Wilkens, Holger Borchert, and Jürgen Parisi — University of Oldenburg, Department of Physics, Energy and Semiconductor Research Laboratory, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg, Germany

In recent years, zinc oxide (ZnO) reached much interest in photovoltaics as a low cost, non-toxic and easy to process n-type semiconductor with a large band-gap of about 3.3 eV. Here, we present a detailed study of wet chemically derived colloidal ZnO nanorods (NRs) with a length and width of about 20 nm and 8 nm, respectively. Homogeneous nanoparticular films, deposited by solution-based techniques, were widely characterized using electron microscopy, X-ray diffraction, optical spectroscopy, and cyclic voltammetry.

As one possible application, we present inverted indium tin oxide-free polymer/fullerene solar cells based on poly(3-hexylthiophene) with an electron-selective interlayer of ZnO NRs, incorporated between the cathode and absorber layer. In the case of an aluminum/chromium cathode a strong increase in power conversion efficiency was achieved compared to cells without interlayer. We attribute this result to optimized contact properties and an enhanced symmetry breaking. Furthermore, we show that our ZnO NRs are also suitable as acceptor material in hybrid polymer/nanoparticle solar cells.