Dresden 2009 – wissenschaftliches Programm

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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

Donnerstag, 26. März 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.