pH-Dependent Photoinduced Electron Transfer at C₆₀-EDTA Langmuir−Blodgett Film Modified ITO Electrode

Abstract

The monolayer and multilayer films of an amphiphilic C 60 -EDTA (C 60 EA) and its tetramethyl ester (C 60 EM) were fabricated on semiconducting transparent ITO electrodes by the Langmuir-Blodgett (LB) technique. The photoelectric response of the modified electrodes was measured under various conditions to explore possible mechanisms of the electron transfer in this light harvesting and conversion system. The action spectrum of photocurrent implicates the excited C 60 EA or C 60 EM as the photoactive species in the photoinduced electron transfer process. Anodic or cathodic photocurrent could be observed depending on the composition and concentration of redox agents in the solution and/or bias voltage applied. These results suggest that electron flow in either direction is energetically possible in the present photoelectric chemical cell. When the pH in the solution was changed, the photocurrent of C 60 EA changed not only in its magnitude but also in its direction. Efficient photoinduced electron transfer was observed in the anodic direction. The quantum yields for the photocurrent generation of C 60 EM and C 60 EA monolayer-ITO system are 4.80% and 3.80% under favorable conditions.

Nanostructured Thin Films of C60–Aniline Dyad Clusters: Electrodeposition, Charge Separation, and Photoelectrochemistry

“…The photocurrents observed in the present study are two to three orders of magnitude greater than the recently reported photoelectrochemical cells using functionalized fullerenes [22,24] and an order of magnitude greater than the photovoltaic cell designed with a C 60 ± oligophenylenevinylene. [39] Note that the photocurrent measurements in the present study were done with a yellow corning filter (425 nm cutoff), which only allow for long wavelength excitations.…”

Nanostructured Fullerene Films

“…Previous efforts to cast fullerene films using solvent evaporation, [1,2] Langmuir±Blodgett films, [3,4] self-assembly of monolayers, [5,6] or layer-by-layer assembly, [7] have produced polymorphous films. However, a high degree of molecular order has been achieved with the films formed on a highly oriented pyrolytic graphite (HOPG).…”

Efficient photocurrent generation through a self-assembled monolayer of C60-mercaptophenylanthrylacetylene

“…Recently, C 60 -derived self-assembled monolayers (SAMs) have been reported to exhibit a wide range of interesting properties such as charge transport, photo-conductivity, superconductivity, and biological activities [1][2][3][4][5][6][7]. Because of its electron-affinitive nature, it is possible to induce very efficient electron transfer from various photoexcited electron donors to C 60 [4]. C 60 s covalently bounded to conjugated molecules have been reported to form a long-lived charge-separated state via photoinduced electron transfer [8][9][10][11].…”