ECN publication
Spray deposition of oxides at ambient atmosphere, Part 2: Compact TiO2 layers as a model for the investigation of an alternative solid state concept for dye solar cells
Published by: Publication date:
ECN Solar Energy 23-11-2006
ECN report number: Document type:
ECN-M--06-099 Conference Paper
Number of pages: Full text:
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Presented at: Thüringer Grenz- und Oberflächentage, Oberhof, Germany, 13-14 september 2006.

Among the various applications of electronic processes at interfaces dye-sensitized solar cells are a fascinating example [1]. Photoinduced charge transfer interactions at the interface between TiO2 and a dye-monolayer adsorbed to it are the basis of these cells. Generally porous TiO2 layers with a high specific surface area between 50 -100 m2/g are applied in order to maximize light absorption. However, for the exploration of new materials combinations it is advantageous to investigate compact planar model interfaces. Issues specific to porous interfaces such as materials interpenetration/pore filling can thus be neglected in initial studies. Compact TiO2 layers of 100 – 300 nm were prepared by spray deposition of an ethanolic solution of titanium tetraisopropoxide stabilized by acetylacetone at 450°C similar to the description of Kavan [2]. Prepared under ambient conditions such layers typically contain pinholes. These can cause undesirable short circuits in the model interfaces in case of direct contact to metallic layers, such as Au. A posttreatment in aqueous TiCl4x2THF solution leads to the removal of the pinholes as can be concluded by the appearance of the expected rectifying contact characteristics for the TiO2/Au interface rather than the ohmic behavior observed before the post-treatment. Thanks to the quality improvement of the TiO2 layers by this post-treatment an alternative solid state concept for dye solar cells could be investigated, which is discussed briefly.

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