Darstellung von Photosensibilisatoren und elektrochemische Abscheidung von sensibilisierten nanostrukturierten Zinkoxidelektroden

Abstract

The major topic of this thesis was the preparation of a photosensitization cell, like the Grätzel-cell. Instead of titaniumdioxid also ZnO can be used for this kind of cells. The great advantage of ZnO is that it can be electrodeposited from aqueous zinc salt solutions at 70 °C. The sensitizer can be added directly to the deposition solution and will be incorporated to the growing ZnO One-step method.One task in this Thesis was the parallel incorporation of different dyes at the same time, so that addition of the absorption regions of different dyes in one film could be achieved. The following panchromatic effect should lead to a better efficiency of the electrode.On the other hand the morphology of the growing ZnO films should be influenced by the addition of detergents to the deposition mixture. Detergents are well known as structure directing agents, for example in the synthesis of porous molecular sieves. Therefore their use in electrodeposition of porous ZnO electrodes seems to be promising, although this is a total new approach in the electrodeposition of ZnO.Sodium lauryl sulphate (SDS) turned out to be a good candidate for the pre-structuring of the electrode material. After desorption of SDS, dyes should be re-adsorbed to the semi conducting material in a sufficient high concentration. Different methods for desorption of the detergent have been investigated and afterwards different dyes and their mixtures have been re-adsorbed. The final goal was to achieve the highest possible load of monomeric dye molecules to a highly porous ZnO surface and therefore an efficient absorption of light in the visible ranch and a good contact with an electrolyte in a photovoltaic cell.