Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 40: Solid-Liquid Interfaces

O 40.7: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster A

Interplay of Different Reaction Pathways in the Pulsed Galvanostatic Deposition of ZnO — •Martina Stumpp, Christian Lupo, and Derck Schlettwein — Institut für Angewandte Physik, Justus-Liebig-Universität Gießen, D-35390 Gießen

Zinc oxide (ZnO) is a promising electrode material for dye-sensitized solar cells (DSCs) and transparent electronics. Electrochemical deposition serves as a low-temperature and an environmentally-friendly technique to prepare crystalline ZnO films even on temperature-sensitive substrates. Aqueous solutions of Zn(NO₃)₂ were used for electrodeposition of ZnO on Au microelectrodes of different shape under pulses of controlled current. Three significant stages were observed in potential-time curves. SEM revealed a correlation between a successively completed coverage of Au by ZnO and an abrupt transition of the deposition and rest potential to less negative values. The deposition time at which such a transition was detected depended not only on the amount of deposited ZnO but also on the current density during electrodeposition and on the electrode geometry, pointing at the influence of different diffusion profiles of the reacting ions. In order to elucidate the role of different redox reactions in the course of electrodepositions of ZnO, measurements were also carried out in various reference electrolytes. The three stages in the potential were only seen for pauses which were equal or longer than the current pulse. The significance of each stage and the corresponding reactions is discussed.