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O: Fachverband Oberflächenphysik
O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)
O 41.40: Poster
Dienstag, 23. März 2010, 18:30–21:00, Poster B1
Determination of Energy Levels in Organic Bulk-Heterojunction Systems — •Holger Wetzstein1, Stefan Krause1, Moritz Liedtke2, Julia Kern2, Achim Schöll1, Carsten Deibel2, and Friedrich Reinert1 — 1Experimental Physics VII, Julius-Maximilians-University of Würzburg, D-97074 Würzburg — 2Experimental Physics VI, Julius-Maximilians-University of Würzburg, D-97074 Würzburg
In order to improve the efficiency of electronic devices based on organic semiconducting materials the detailed knowledge about the exact position of the energy levels responsible for charge transport is crucial. The experimental determination is particularly complicated for bulk heterojunctions of p- and n-conducting materials in terms of sample preparation, film morphology and distinction of the different spectroscopic signatures. We investigated four promising materials for organic photovoltaic devices: the electron donor poly(3-hexylthiophene-2,5-diyl) (P3HT) and the three electron acceptors [6,6]-phenyl-C61 butyric acid methyl ester (PC60BM), its bisadduct analogue (bis- PC60BM) and [6,6]-phenyl-C71 butyric acid methyl ester (PC70BM). Thin films of pristine materials as well as bulk heterojuction samples of P3HT:PC60BM, P3HT:bis-PC60BM and P3HT:PC70BM were examined with respect to their valence levels using ultraviolet photoelectron spectroscopy (UPS).