Molecular mixtures based on porphyrins and phthalocyanines for application in photovoltaics

Abstract
This paper presents a study of the photophysical properties of mixtures of magnesium or zinc porphyrins and phthalocyanines dissolved in dimethyl sulfoxide in order to follow deactivation pathways of radiative and non-radiative processes of excited states of molecules in the mixtures and their photocurrent generation when embedded in a photoelectrochemical cell. Interactions between dyes in the mixtures were examined by means of absorption, photoacoustics and laser induced optoacoustic spectroscopy. The changes of the spectral parameters (thermal deactivation, quantum yield of triplet state population, lifetime of the triplet states) for the dyes in the mixtures, when compared to those for the individual dyes, evidently indicate the strong interaction between the dye molecules. The alteration of photocurrent generated in the photoelectrochemical cell based on the dye mixture was observed (when compared to that for the individual dyes) and it was discussed in terms of interaction and energy transfer between dyes. The Forster radia were estimated and their values are found to be typical for the resonance energy transfer. Energy transfer between dyes can cause the increase of photocurrent in the photoelectrochemical cell.