Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 12: Inorganic/Organic Interfaces: Growth II

O 12.3: Talk

Monday, March 16, 2015, 15:30–15:45, MA 005

Structural and optical investigation of weakly interacting commensurate organic-organic interfaces in SnPc/PTCDA heterolayers on Ag(111) — •Marco Gruenewald, Julia Peuker, Matthias Meissner, Falko Sojka, Roman Forker, and Torsten Fritz — Friedrich Schiller University, Institute of Solid State Physics, Helmholtzweg 5, Jena 07743, Germany

We report on structural and electronic properties of highly-ordered ultrathin layers of the dye molecules 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and tin(II)-phthalocyanine (SnPc) stacked on Ag(111). The thin films have been structurally characterized by low energy electron diffraction (LEED) and low temperature scanning tunneling microscopy (LT-STM) as well as optically by in situ differential reflectance spectroscopy (DRS) [Annu. Rep. Prog. Chem., Sect. C: Phys. Chem. 108, 34-68 (2012)]. Depending on the coverage and on the substrate temperature the SnPc adlayers on top of 1 ML PTCDA/Ag(111) form either three different commensurate registries (with each unit cell different in size and number of molecules) or show a 2D-gas-like behavior. By means of DRS we found that the molecules in all phases show monomer behavior pointing to a rather weak electronic interaction at the organic-organic interface in contrast to conclusions recently drawn for a similar commensurate heterointerface with CuPc instead of SnPc [PRL 108, 106103 (2012)]. Thus, commensurism at organic-organic interfaces cannot necessarily be linked to strong electronic interaction. Additionally, for SnPc films with thicknesses beyond 1 ML we found intermediate phases prior the formation of a SnPc bulk structure.