title: Organic semiconductor/gold interface interactions: from physisorption on planar surfaces to chemical reactions with metal nanoparticles.
abstract: The interaction of gold nanoparticles (AuNPs) with prototypical organic semiconductors used in optoelectronics, namely, tris(8-hydroxyquinoline)aluminium (Alq3 ) and 4,4-bis[N-(1-naphthyl)-N-phenylamino]diphenyl (α-NPD), is investigated in situ by X-ray photoelectron spectroscopy (XPS). These AuNPs-on-molecule experiments are compared with the reversed molecule-on-Au cases. The molecules-on-Au systems show only weak interactions, and the evolution of the XP spectra is dominated by final-state effects. In contrast, in the AuNPs-on-molecules cases, both initial-state effects and final-state effects occur. Spectral features arising for both molecules and metal indicate charge transfer and the formation of organometallic complexes (initial-state effects). The energy shift in the metal emission underlines the size-induced nanometric nature of the molecule/Au interaction (final-state effects). Consequently, the chemical interaction between metals and organic semiconductors likely depends strongly on the deposition sequence in general.
authors.affiliation: Humboldt-Universität zu Berlin, Institut für Physik, Brook-Taylor Strasse 6, 12489 Berlin (Germany).
authors.forename: Giovanni
authors.initials: G
authors.lastname: Ligorio
authors.affiliation: Humboldt-Universität zu Berlin, Institut für Physik, Brook-Taylor Strasse 6, 12489 Berlin (Germany).
authors.forename: Marco Vittorio
authors.initials: MV
authors.lastname: Nardi
authors.affiliation: Humboldt-Universität zu Berlin, Institut für Physik, Brook-Taylor Strasse 6, 12489 Berlin (Germany).
authors.forename: Christos
authors.initials: C
authors.lastname: Christodoulou
authors.affiliation: Humboldt-Universität zu Berlin, Institut für Physik, Brook-Taylor Strasse 6, 12489 Berlin (Germany). norbert.koch@physik.hu-berlin.de.|Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein Strasse 15, 12489 Berlin (Germany). norbert.koch@physik.hu-berlin.de.
authors.forename: Norbert
authors.initials: N
authors.lastname: Koch
keywords: gold; interfaces; nanoparticles; photoelectron spectroscopy; semiconductors