Photoelectrochemical response of Langmuir-Blodgett monolayer films containing donor-π-acceptor azomethine dyes

Three amphiphilic azomethine dyes, (E)-N-octadecyl-2-[2-(4-N,N-dimethylaminophenyl)azomethinyl]quinolinium iodide, (E)N-octadecyl-4-[2-(4-N,N-dimethylaminophenyl)azomethinyl]quinolinium iodide, and (E)-N-octadecyl-6- [2-(4-N,N-dimethylaminophenyl)azomethinyl]quinolinium iodide, have been prepared by changing different relative positions of electron-accepting groups. They were successfully transferred onto indium-tin oxide slides by the Langmiur-Blodgett (LR) technique. Photoelectrochemical studies on these dyes' LB monolayer-modified ITO electrode were carried out. In 0.5 M KI solution containing 0.05 M I-2, the photocurrent generation quantum yield for these dyes varied from 7.2 to 15.9%, depending on the linking positions. Dependence of the photocurrent on the applied potential and the redox couple suggests that they undergo the photoinduced electron transfer mechanism of photoelectric conversion. (C) 2000 Academic Press.