Berlin 2008 – wissenschaftliches Programm

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.61: Poster

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

Interface energetics in highly ordered organic-organic heterosystems: Thermal induced layer swap in the system HBC on PTCDA — •Rainer Jacob, Christian Wagner, Thomas Dienel, and Torsten Fritz — Institut für Angewandte Photophysik, TU-Dresden, George Bähr Str. 1, 01069 Dresden

The structural and energetic properties of organic-organic and organic-inorganic interfaces play a crucial role in future devices based on ultra thin organic layers or single molecules. We will present results of a STM and LEED study of an organic-organic heterosystem consisting of two stacked highly ordered monolayers (ML) of hexa-peri-hexabenzocoronene (HBC) and perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA) on Au(111). While the evaporation of one ML PTCDA onto a highly ordered HBC ML creates a stable organic-organic heterosystem [1], no such observation could be made for the reversed stack order, i.e., HBC on PTCDA on Au(111). Even light annealing at approx. 60°C of such a sample leads to a swap of the stack order and the creation of large sample areas where the consecutively evaporated HBC has displaced the PTCDA as first layer, with the PTCDA now forming an epitaxial layer on top of the ordered HBC. Force field calculations [2] revealed that interface energetics can be made responsible for the process observed, as there is a considerable energy gain per surface area when changing from HBC on PTCDA on Au(111) to PTCDA on HBC on Au(111).

[1] F. Sellam et al., Surf. Sci. 478, 113 (2001).

[2] S.C.B. Mannsfeld and T. Fritz, Mod. Phys. Lett. B 20, 585 (2006).