Photoelectrochemical properties of ZnO/tetrasulfophthalocyanine hybrid thin films prepared by electrochemical self-assembly

Dye-loaded zinc oxide (ZnO) thin films prepared by a one-step electrochemic al synthesis from aqueous mixtures of zinc nitrate and water soluble tetras ulfonated metallophthalocyanines (TSPcMt), in which Mt = Zn(II), Al(III)[OH ] or Si(IV)[OH](2), have been studied photoelectrochemically. Visible light absorbed in the TSPcMt led to the sensitization of ZnO. A significantly hi gher conversion efficiency was found for monomeric as compared to aggregate d TSPcMt adsorbed on the ZnO surface. The highest photocurrents were observ ed for TSPcSi. This could be explained by a strong interaction of the TSPcS i with the ZnO, leading to a highly ordered growth of the ZnO/TSPcSi films with a large fraction of TSPcSi monomers adsorbed to the ZnO surface. The s trong adsorption also leads to a more efficient electron injection from the TSPcSi monomers into the conduction band of ZnO as compared to other TSPcM t.