Electrophoretic deposition of nanocomposites formed from polythiophene and metal oxides

The properties of the composite layers were studied by electrochemical methods (cyclic voltammetry, impedance spectroscopy) and photocurrent measurements. The reversible redox potential of polythiophene films was about 0.75 VSCE. The p-type semiconducting behaviour of the reduced polythiophene was studied by photocurrent measurements. In the case of using TiO2 (n-type semiconductor) as a core material, an n/p heterojunction was observed. In the photocurrent spectra the maximum of the cathodic peak of polythiophene was found around λ = 500 nm (2.5 eV), depending on the applied potential. It is in agreement with the results of UV-vis optical spectra of deposited layers and of pressed pellets. The flatband potential of polythiophene in the heterojunction with TiO2, obtained from photocurrent measurements, was 0.53 VSCE.