Dresden 2009 – scientific programme
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SYOP: Symposium Organic Photovoltaics: From Single Molecules to Devices
SYOP 4: Organic Photovoltaics: from Single Molecules to Devices
SYOP 4.20: Poster
Thursday, March 26, 2009, 16:30–19:00, P1A
Electronic properties of doped CuPc layers — •Johanna Härter, Eric Mankel, Corinna Hein, Thomas Mayer, and Wolfram Jaegermann — Technische Universität Darmstadt, Materials Science Institute, Surface Science Division, Petersenstraße 23, 64287 Darmstadt
Doping of molecular organic materials is important for the functionality of organic electronic devices as e.g solar cells. We investigated the doping behaviour of the acceptor molecules Cl2-DCNQI and F16CuPc incorporated into a CuPc matrix. In-situ XPS/UPS measurements were performed on coevaporated films. Doping by Cl2-DCNQI was not successful. The molecule lost its chlorine atoms during thermal evaporation. For pristine F16CuPc layers we observe a strong broadening of the photoemission features with increasing deposition rate indicating different domains probably of different molecular structure of differing electric interface potential. F16CuPc incorporated into CuPc shows sharp photoemission features. With increasing F16CuPc content Fermi level shifts are observed in both phases. In CuPc the maximum shift is about 0.45eV towards the HOMO level indicating p-doping. Simultaneously the Fermi level in F16CuPc shifts 0.15eV towards the LUMO level. The opposite Fermi energy shifts can be explained by charge transfer between separate CuPc and F16CuPc phases. The HOMO offset is 1.23eV. Compared to the electron affinity rule this offset differs by approximately 100meV indicating an interfacial dipole between CuPc and F16CuPc in the same order of magnitude.