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Ultrathin films of metallofullerenes : preparation, characterization and photoelectrochemical applications

Authors Yang, Shangfeng
Issue Date 2003
Summary Langmuir-Blodgett (LB) films of metallofullerenes and their mixtures with various molecular matrices have been successfully constructed at the N2/water or air/water interface. In this way, the metallofullerene balls are dispersed uniformly in the matrices of the molecules. For the LB films of Dy@C82-AA, an anodic photocurrent was observed, which increased with increases in the positive bias voltage and light intensity and with the presence of the electron donor AsA. As a result, Dy@C82-AA exhibits a higher anodic photocurrent quantum yield ∅ (~3.9%) than the pure Dy@C82 and the C60-AA films on ITO under appropriate conditions. The di-metallofullerene La2@C80 demonstrates very similar film formation behaviors and comparable PEC properties. The assembly of Dy@C82-MPc (MPc = 1-3, see Scheme 4.1) in the Langmuir films is found to be dependent on the substituents and the central metal ion. Ground state CT is observed between 2(3) and Dy@C82. Stable anodic photocurrent responses for the Dy@C82-MPc films have been demonstrated with enhanced quantum yields compared to those of pure Dy@C82 and pure MPc. The highest anodic photocurrent ∅ of Dy@C82-2 (or 3) reaches up to 7-8% under appropriate conditions. For the P3HT-Dy@C82 Langmuir films, the assembly seems to be in such a way that the Dy@C82 molecules are sitting on the chain matrix of P3HT with the polymer backbones taking an edge-on arrangement. A dramatic enhancement of the stable cathodic photocurrent has been demonstrated, which is attributed to the facile photoinduced electron transfer between P3HT and Dy@C82 (C60) as supported by the PL measurements. We have synthesized a host-guest supramolecular complex of [Dy@C82-C8A], the Langmuir films of this complex and [C60-C8A] complex are found to be sensitively dependent on the initial concentration of the spreading solution. Steady-state PL results strongly support the complex formation between Dy@C82(C60) and C8A. A cathodic photocurrent for the straight and isolated Cu2S nanowires arrayed on a copper foil is observed, which increases with the increasing negative bias of the film electrode, conforming to the p-type semiconducting nature of Cu2S. PEC studies on the core/sheath nanowires of Cu2S (Cu2S/CdS, Cu2S/PPy, and Cu2S/Au) indicate distinct differences for different nanowire structures.
Note Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2003
Language English
Format Thesis
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