Photocurrent generation from visible light irradiation of covalent polyoxometalate–porphyrin copolymers

Abstract Four hybrid polyoxometalate–porphyrin copolymer films were obtained by the electrooxidation of zinc-β-octaethylporphyrin (ZnOEP) or 5,15-ditolylporphyrin (H2T2P) in the presence of organosilyl functionalized Keggin-type POMs TBA3[PW11Si2O40C26H16N2] (abbreviated Py-PW11Si2-Py) and Dawson-type POMs TBA6[P2W17Si2O62C26H16N2] (abbreviated Py-P2W17Si2-Py) bearing two remote pyridyl groups. The electropolymerization process of the four copolymers was monitored by EQCM. The obtained copolymers were characterized by UV/Vis spectroscopy, X-ray photoelectron spectroscopy, electrochemistry, and AFM. Their impedance properties (EIS) were studied and their photovoltaic performances were also investigated by photocurrent transient measurements under visible light irradiation. These studies showed a correlation between impedance and photovoltaic performances, the films based on Dawson type POMs and Zn porphyrins giving the best results. This last system displayed one of the best photocurrent efficiency for a reported POM photosensitized hybrid.