Photovoltaic properties of supramolecular assemblies obtained by incorporation of Preysler's type polyoxometalate in a polycationic copolymer of porphyrin

Poly-zinc-octaethylporphyrin/P5W30 films have been obtained through incorporation of Preyssler-type polyoxometalate ions, namely [NaP5W30O110]14- (P5W30) into zinc octaethylporphyrin/viologen-based polymers (poly-ZnOEP) films. The latter has been achieved through a metathesis reaction involving exchange of the initial counter ions (PF6−) of the positively charged poly-ZnOEP by P5W30. The investigated polymers involve ZnOEP units covalently linked either through a dicationic mono-viologen or through a tetracationic bis-viologen spacer. These copolymers have been characterized by UV/Vis absorption spectroscopy, X-ray photoelectron spectroscopy, electrochemistry, AFM and by electrochemical impedance spectroscopy. Formation of the polymers through electropolymerization of viologen and porphyrin building blocks has also been monitored by EQCM. QCM measurements have been carried out to study the exchange of PF6− by [NaP5W30O110]14−. Finally, the photovoltaic performances of these polymers have been assessed by photocurrent transient measurements carried out under visible illumination.