Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 55: Focus Session: Functionalized semiconductor nanowires II (DS, jointly with HL)
HL 55.3: Talk
Wednesday, March 13, 2013, 12:15–12:30, H8
Oxygen-controlled electron-transfer dynamics under optical exitation in hybrid ZnO nano-/CdSe quantum dot structures — •Stephanie Bley1, Dongchao Hou1, Michael Diez1, Sebastian Resch2, Siegfried Waldvogel2, Jürgen Gutowski1, and Tobias Voss1 — 1Institute of Solid State Physics, Semiconductor Optics, University of Bremen, 28359 Bremen, Germany — 2Institute of Organic Chemistry, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
Due to their optoelectronic properties hybrid ZnO nano-/CdSe quantum dot structures possess a high potential for applications in photovoltaics and sensing. For this, the use of organic linker molecules to selectively attach the quantum dots to specific surfaces is a very versatile technique. We chemically synthesize colloidal CdSe quantum dots and attach them to the surface of ZnO nanostructures via different ω-mercapto alkanoic acids. The electron transfer dynamics of this hybrid systems are studied under illumination with a photon energy below the bandgap of ZnO (argon ion laser: λ=458 nm, E=2.7 eV). A strong enhancement of the photoconductivity has been found, and the experimental results demonstrate efficient electron tunneling from excited states of the quantum dots into the conduction band of the nanostructures. We discuss the influence of the length and electronic structure of the linker molecules on the electron transfer dynamics in the hybrid structures. Furthermore, we analyse the passivation of the ZnO nanostructure surfaces to reduce the influence of oxygen desorption for further studies of luminescence decay dynamics.