Influence of polymer matrices on the photoelectrochemical properties of a molecular semiconductor by structural modification

Thin films of phthalocyaninatozinc(II) (PcZn) have been prepared by physical vapor‐deposition or from solutions in organic solvents in mixture with poly(vinylidene fluoride) PVDF. The molecular order, i.e. the structure of the van der Waals bonded crystals, depends on the preparation technique and on the chosen matrix. By annealing the thin films or by embedding the phthalocyanine in a polymer environment, the structure is effected significantly. This is demonstrated by electronic spectra. The activities of the films have been investigated in the photoreduction of oxygen dissolved in an aqueous electrolyte. The highest sensitivities towards visible light are observed in matrices of polymers with a high dipole moment. Aside from the influence of a polar polymer towards a more favourable crystallization of PcZn an active role in the charge carrier generation process is derived from a discussion of the results within the model of molecular semiconductors which is appropriate for phthalocyanines.