Berlin 2008 – wissenschaftliches Programm

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.71: Poster

Dienstag, 26. Februar 2008, 14:30–20:00, Poster A

Electronic coupling of organic dyes with inorganic van der Waals semiconductors — Eric Mankel, Johanna Härter, •Thomas Mayer, and Wolfram Jaegermann — FG Oberflächenforschung, FB Materialwissenschaft, Technische Universität Darmstadt

A prerequisite for tailoring organic/organic and organic/inorganic interfaces is the understanding of the electronic coupling processes. Inert van der Waals surfaces of layered chalcogenide semiconductors are free of surface states and allow to monitor free of chemical interaction charge transfer and interface dipole formation by synchrotron induced photoelectron spectroscopy. Copper phthalocyanine, CuPc and a perylene derivate, PTCDA were adsorbed in situ on UHV-cleaved n- and p-WSe2. For both molecules the HOMO position below the valence band maximum is independent of the substrate Fermi level position, SFLP, (n or p-type) and amounts to 0,64eV and 1,63eV for CuPc and PTCDA. The constancy of the HOMO position versus substrate orbitals for varied SFLP and coverages indicates the absence of an interface dipole. Both molecules induce band bending on n and on p substrates but in opposite directions in dependency of doping indicating the position of the molecule charge neutrality level between the n and p SFLP. The surface SFLP of n- and p-WSe2 for higher dye coverage do not converge to the same value. A difference of about 0,45eV is measured for both dyes indicating a shift of the dye charge neutrality level due to charge transfer.