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CPP: Chemische Physik und Polymerphysik
CPP 21: SYMPOSIUM Functional Organic Thin Films II
CPP 21.9: Talk
Thursday, March 30, 2006, 16:30–16:45, ZEU Lich
Impedance spectroscopy on organic semiconductors for solar cell application — •Martin Knipper1, Jürgen Parisi1, and Vladimir Dyakonov2 — 1Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg, 26111 Oldenburg, Germany — 2Faculty of Physics and Astronomy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
Impedance spectroscopy is a powerful tool for studying the electrical transport properties of bulk heterojunction solar cells. The photovoltaic absorber consist of a mixture of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), sandwiched between a transparent indium tin oxide (ITO) front electrode and a metal (Au or Al) back electrode as well as a polymer buffer layer (PEDOT:PSS). We look at the individual material components as well as the composites with and without the PEDOT:PSS interfacial layer. It allows us to investigate the internal device structure, the behaviour of the interfacial layer and the metal/P3HT junction. For the various devices we find different equivalent circuit diagrams. Upon varying the thickness of the semiconductor layer, it is aimed to discriminate bulk and surface effects, in order to improve the preparation process of the composite absorber. From this measurements we found an єr of 3 for the P3HT and one of 3.4 for the PCBM:P3HT bulk heterojunction.