Photovoltage generation and fluorescence of charged tetraphenylporphyrins with dopa melanin

Abstract

AbstractPositively charged tetra(4‐N,N,N,N‐ trimethylanilinium) porphyrin (TAP) and negatively charged tetrakis(4‐sulphonatophenyl) porphyrin (TPPS4) and their mixtures with dopa melanin in polyvinyl alcohol have been investigated. On the basis of the absorption and fluorescence spectra it has been established the formation of TAP–dopa melanin complex which fluorescence is quenched whereas TPPS4 fluorescence behaviour is only slightly changed in the presence of dopa melanin. Photovoltaic effects and photocurrent generation in a photoelectrochemical cell consisting of a layer dye solutions sandwiched between the semiconducting and gold electrodes have been investigated. The dependence of photovoltage signal on excitation wavelength (photovoltage action spectrum), kinetics of photocurrent rise and decay in the second time scale have been presented. Electric parameters of the photoelectrochemical cell (conductivity and capacitance) with porphyrin dyes, dopa melanin and their mixtures in the dark and upon illumination have been estimated. It was shown that all investigated dyes are able to generate photosignal but the values of photocurrent generated depend on the dye used in the experiment and the presence or absence of dopa melanin.