Studies of the photocurrent generation performances from a series of amphiphilic bis-chromophore zinc complexes and correlation between photocurrent generation performance and molecular structure

A systematic study of the photocurrent generation (PCG) performances from seven analogues of bis-hemicyanine dye chromophore cations ionically combined with a bivalent zinc anion, bis-(2-thione-1,3-dithiol-4,5-dimerapto) zinc, has been made under the same conditions in order to discuss the influence of molecular structure on PCG performance. The coincidence of the action spectra of the PCG with the absorption spectra of the monolayer LB films on indium-tin oxide (ITO) electrodes indicate that the hemicyanine analogue chromophore cations in the bis-chromophore complex are the photoelectric active moieties which is responsible for the PCG for each analogue. The results also demonstrate that these bis-chromophore zinc complexes have larger quantum yield than their corresponding iodide salts. The correlation between PCG capability and the molecular structure of hemicyanine dye chromophore cation has been established. This correlation is valuable in leading to systematic improvement in performance and new molecule design with high quantum efficiency. (C) 1999 Elsevier Science S.A. All rights reserved.