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Three xanthene dyes with different anchoring groups, eosin Y (EY), dicarboxy-eosin Y (CEY) and sulfonated eosin Y (SEY) were employed to electrodeposit ZnO/dye hybrid thin films to study the effect of anchoring groups on the electrochemical self-assembly (ESA) of hybrid thin films. The adsorption stabilities of the dyes in oxidized form were in the order, CEY >> EY > SEY, as evaluated by Langmuir isothermal adsorption experiments. The reduction potential of dyes, the dependence on Zn(2+) concentration that reflects stabilities of complexes between reduced dyes and Zn(2+) ion, and the diffusion coefficients of dyes were determined by electrochemical measurements. These properties of the dyes were considered as the key parameters to dominate ESA of hybrid thin films which were actually prepared with these dyes by potentiostatic electrolysis at -0.8 and -1.0 V (vs. SCE) representing ESA with dyes in oxidized and reduced forms, respectively, and were analyzed for their chemical composition and structural features.

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1 Introduction Nanostructured thin films of inorganic wide-bandgap semiconductors are an interesting field of research due to the numerous applications e.g. in photocatalysis [1] and optoelectronic devices [2,3]. Fabrication of semiconductor thin films presently often relies on gas phase methods like vacuum evaporation, sputtering and chemical vapour deposition, which are of high cost because of the need for high energy, high temperatures or expensive vacuum facilities. Our approach is the electrochemical deposition of porous semiconductor thin films, a method which promises to be cost-effective and convenient since usually no high temperatures, vacuum conditions or other expensive equipment is needed. Moreover, nanostructuring of the films and the formation of inorganic/organic hybrid films can easily be achieved in situ just by the presence of the organic substances to be codeposited in the electrodeposition bath.