Magnetic field effects on photoelectrochemical reactions of electrodes modified with thin films consisting of conductive polymers

The magnetic field effects (MFEs) on the photoelectrochemical reactions of electrodes modified with nanowires consisting of regioregular poly(3- hexylthiophene) (P3HT), disordered P3HT films without and with annealing treatment, and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) films were examined. In P3HT, the photocurrent increased in the presence of a magnetic field. The magnitude of the MFEs increased in the following order of modified electrodes: P3HT nanowires, P3HT films with annealing treatment, P3HT films without annealing treatment. The difference in the MFEs is most likely to be attributable to the capability of hole hopping between adjacent thiophenes. On the other hand, in MEH-PPV, the photocurrent decreased in the presence of a magnetic field. The MFEs on the photoelectrochemical reactions of electrodes modified with P3HT and MEH-PPV are explained by the polaron pair mechanism. The difference in the MFEs between P3HT and MEH-PPV is ascribed to the spin multiplicity of the polaron pairs.