Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 55: Focussed Session: Towards a Quantitative Understanding of Complex Adsorption Structures: Surface Science goes Organic I

O 55.8: Talk

Wednesday, April 2, 2014, 18:15–18:30, TRE Phy

Adsorption height alignment at heteromolecular hybrid interfaces — •Benjamin Stadtmüller, Sonja Schröder, Francois C. Bocquet, Caroline Henneke, Christoph Kleimann, Serguei Soubatch, Martin Willenbockel, F. Stefan Tautz, and Christian Kumpf — Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Germany and Jülich Aachen Research Alliance (JARA-FIT)

The future success of organic electronic devices strongly depends on the ability to control the properties of the active organic materials and their interfaces. In this context the formation of the first organic layer adsorbing on a metal surface plays an important role, which in turn is dominated by the interplay between different interaction mechanisms between the molecules and with the surface.

Here, we report on a systematic investigation of metal-heteromolecular interfaces consisting of two different molecules, both in contact with a metal surface: PTCDA or NTCDA act as the charge accepting, CuPc or SnPc as the charge donating molecular species. We concentrate on structural properties like the adsorption heights, and their interplay with charge donation and acceptance. Most importantly, when comparing homo- and heteromolecular layers of these molecules, we have found a systematic trend of adsorption height adjustment between donor and acceptor molecules. This self alignment goes along with a substrate-mediated charge transfer from the donors to acceptors and a mutual enhancement of the respective characters of the molecules. We propose that this effect is of general validity for π-conjugated molecules adsorbing on noble metal surfaces.