Preparation and photoelectrochemical properties of an electrostatically self-assembled film based on [BW11Zn(H2O)O39]7- and a bipolar hemicyanine.

A new electrostatically self-assembled film has successfully been prepared on quartz and indium-tin-oxide (ITO) substrates by alternating adsorption of BW11Zn(H2O)O39 (BW11Zn) and a hemicyanine of (E)-1,1'-(hexane-1,6-diyl)bis(4-(4-(dimethylamino)styryl)pyridinium) bromide (H6Br2). The UV-visible absorption spectra showed that the film was uniformly deposited and the interaction between the two film-forming components occurred in the film. The (BW11Zn/H6)n film exhibited stable cathodic photocurrent as irradiated with white light. The photocurrents were found to increase linearly with increasing the deposited bilayers increased up to 3 layers. The photocurrent action spectrum indicated that the cathodic photocurrents were generated from charge transfer excitation of H6 in the (BW11Zn/H6)n film. The effects of applied bias voltages, electron donor and acceptor added in the electrolyte, and layer number n of (BW11Zn/H6)n film on the photocurrent generation have also been examined.