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O: Fachverband Oberflächenphysik

O 38: Organic-Inorganic Hybrid Systems and Organic Films V

O 38.4: Vortrag

Dienstag, 21. März 2017, 15:00–15:15, WIL A317

Adsorbate-induced restructuring of crystalline and amorphous ZnO surfaces upon formation of phosphonic acid self-assembled monolayers — •Tobias Klöffel¹, Hannah Schlott¹, Alexandra Ostapenko², Gregor Witte², and Bernd Meyer¹ — ¹Interdisciplinary Center for Molecular Materials and Computer-Chemistry-Center, FAU Erlangen-Nürnberg — ²Fachbereich Physik, Philipps-Universität Marburg

Among the inorganic oxides, ZnO is of special interest for hybrid organic–inorganic interfaces in molecular electronics due to its high charge carrier mobility. Phenyl phosphonic acids (PPAs) are commonly used linker groups and functional organic units for creating such interfaces. Recent experiments and DFT calculations showed, however, that self-assembled PPA monolayers are only metastable and etch the ZnO substrate [1,2].

DFT calculations were performed to explore systematically the possible PPA monolayer structures on crystalline and amorphous ZnO model surfaces. In addition to regular PPA adsorbate structures on unmodified substrates we find that the PPA molecules can induce strong structural changes in the ZnO surfaces. Configurations with additional Zn and O ions between PPA molecules show a similar thermodynamic stability, which might be the origin of the observed structural instability of the PPA monolayers.

[1] A. Ostapenko, et al., ACS Appl. Mater. Interfaces 8, 13472 (2016).
[2] A. Ostapenko, et al., Langmuir 32, 5029 (2016).