Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 22: Organic-Inorganic Hybrid Systems and Organic Films
O 22.13: Poster
Monday, March 7, 2016, 18:15–20:30, Poster E
DFT calculations on the etching of crystalline ZnO surfaces upon formation of phosphonic acid self-assembled monolayers — •Tobias Klöffel1, Alexandra Ostapenko2, Gregor Witte2, and Bernd Meyer1 — 1Interdisziplinäres Zentrum für Molekulare Materialien und Computer-Chemie-Centrum, Universität 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. However, in recent experiments it was observed that self-assembled monolayers of phenylphosphonic acids (PPAs), a typical representative for commonly used linker groups and functional organic units, are not stable but etch the ZnO substrate. Using density-functional theory (DFT) calculations we show that the origin of this instability is the unusual strength of the PPA–ZnO interaction together with a geometric misfit between the pi-stacking of the phenyl rings and the ZnO lattice constant. As a result, the transformation of PPA layers on ZnO to ZnPPA crystals becomes a thermodynamically favorable reaction. Our DFT calculations provide a first simplified reaction pathway for this transformation process.