Colloids and Surfaces A: Physicochemical and Engineering Aspects, 20 April 2013, Vol.423, pp.162-169
Three electrostatically self-assembled films made of [P W Zn (H O) O ] (P W Zn ) and a hemicyanine dimer linked by varied alkyl chain lengths, were uniformly prepared with large bathochromic shifts compared to the hemicyanine aqueous solutions. A 3-layer film gave stable, large cathodic photocurrent densities of 13.7 μA/cm at an applied potential of −0.3 V vs. saturated calomel electrode. ► Electrostatically self-assembled films from tetrazinc tungstophosphorate and hemicyanines were prepared. ► Alkyl chain lengths in hemicyanines strongly affected cathodic photocurrents. ► A maximum photocurrent density of 1.33 μA/cm was achieved at zero bias voltage. Three inorganic/organic hybrid films consisting of sandwich-type tetrazinc(II) tungstophosphorate [P W Zn (H O) O ] (P W Zn ) and three hemicyanines of ( )-1,1′-(propane-1,3-diyl) bis (4-(( )-2-(4-(dimethylamino) naphthalen-1-yl) vinyl)-pyridinium) bromide (N ), ( )-1,1′-(hexane-1,6-diyl) bis (4-(( )-2-(4-(dimethylamino) naphthalen-1-yl) vinyl) pyridinium) bromide (N ), and ( )-1,1′-(decane-1,10-diyl) bis (4-(( )-2-4-(dimethylamino) naphthalen-1-yl) vinyl) pyridinium) bromide (N ), were prepared by electrostatic self-assembly technique. The UV–visible spectra showed that three inorganic–organic hybrid films of P W Zn /N ( = 3, 6, 10) were uniformly deposited and the hemicyanine molecules formed -aggregations in the films. The monolayer (P W Zn /N ) films exhibited stable, large cathodic photocurrent densities of 1.41–4.62 μA/cm that strongly depended on the alkyl chain lengths, while irradiated with 100 mW/cm polychromatic light of 730 nm 〉 〉 325 nm at an applied potential of −0.3 V vs. saturated calomel electrode. The photocurrent action spectra indicated that the cathodic photocurrents were generated by the charge transfer excitation of the hemicyanines in the films. The effects of applied bias voltages, electron acceptor added into the electrolyte solution, and layer numbers of the (P W Zn /N ) films on photocurrent generation of (P W Zn /N ) film were also examined.
Engineering ; Chemistry
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