Vectorial Multistep Electron Transfer at the Gold Electrodes Modified with Self-Assembled Monolayers of Ferrocene−Porphyrin−Fullerene Triads

• DOI: 10.1021/jp993784f
• Publication Date: 2002-07-26T06:02:40Z
• Authors: Hiroshi Imahori; Hiroko Yamada; Yoshinobu Nishimura; Iwao Yamazaki; Yoshiteru Sakata
• Keywords: Photoinduced electron transfer; Viologen

Self-assembled monolayers of ferrocene−porphyrin−C60 triads on gold electrodes were prepared to mimic photosynthetic electron transfer events where efficient conversion light chemical energy takes place via the long-lived, charge-separated state with a high quantum yield. Adsorbed amounts electrodes, estimated from charge anodic peak ferrocene, are comparable those well-ordered porphyrin−alkanethiols and C60−alkanethiols electrodes. The results, together blocking experiments using redox probe, indicate that triad molecules well-packed an almost perpendicular orientation surface. monolayer thickness obtained X-ray reflectivity analysis is consistent structural model monolayer. Photoelectrochemical studies carried out in standard three-electrode system modified self-assembled triads. Stable cathodic photocurrents observed presence carriers such as oxygen and/or methyl viologen electrolyte when illuminated monochromic light. A photoinduced multistep electron-transfer mechanism proposed for photoelectrochemical cells. Thus, vectorial or partial occurs excited singlet porphyrin C60, followed by successive shift ferrocene cation radical, produce radical C60 anion radical. gives counter electrode solution, whereas resulting recovery initial generation overall flow. artificial cells show highest efficiency (20−25%) ever reported at monolayer-modified metal across membranes donor−acceptor linked molecules. result indicates clearly acts excellent acceptor well mediator membranes. molecule-based methodology will provide new direction development solar molecular devices.