Berlin 2018 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 58: Organic Thin Films, Organic-Inorganic Interfaces: Session I (joint session DS/CPP)

CPP 58.3: Talk

Wednesday, March 14, 2018, 17:00–17:15, H 0111

photochromic phosphonic-acid diarylethene self-assembled monolayer switches on polar ZnO surfaces — •Qiankun Wang¹, Giovanni Ligorio¹, Valentin Diez-Cabanes², David Cornil², Björn Kobin³, Stefan Hecht³, Jérôme Conil², Emil J.W. List-Kratochvil¹, and Norbert Koch¹ — ¹Institut für Physik, Humboldt-Universität zu Berlin — ²Laboratory for Chemistry of Novel Materials, University of Mons — ³Department of Chemistry, Humboldt-Universität zu Berlin

Here, we investigate the interfacial chemical and switching properties of the phosphonic-acid diarylethene (PA-DAE) switch in form of a self-assembled monolayer (SAM) on ZnO(0001) and ZnO(000-1) surfaces by photoelectron spectroscopy and density functional theory calculations. The observed work function increase is attributed to the introduction of a surface dipole; the binding modes of the phosphonic-acid linker were retrieved from the deconvolution of O 1s core level spectra, indicating the formation of mixed bidentate and tridentate binding. The quantification of core level spectra supports the picture of a densely packed SAM on both ZnO surfaces. Upon illumination with ultraviolet and visible light, respectively, we observe a 0.7 eV energy level shift at the onset of the highest occupied molecular orbital (HOMO) level of the PA-DAE molecules. This can further on be used to reversibly switch the energy level alignment at the ZnO/PA-DAE interface in device structures.