Ultrafast photo-induced electron-transfer from coumarin dyes adsorbed on semiconductor nanoclusters surfaces

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:560430

Castner, Jr, E W ^[1]; Murakoshi, Kei; Yanagida, Shozo ^[2]

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1. Brookhaven National Lab., Upton, NY (United States)
2. Osaka Univ. (Japan)

Photosensitizers adsorbed directly on semiconductor surfaces provide the basis for solar photoelectrochemical devices. Semiconductor nanoclusters in solution allow for simple preparation of the photosensitized surface, with very large surface area. To optimize the efficiency of the photoelectrochemical cycle, one must know the rates of forward and reverse electron-transfer from the excited state dye to the semiconductor conduction band. We present measurements of the ultrafast forward electron-transfer rates for three coumarin dyes (Coumarins 343, D-1421, and D-126) bound by the carboxylic acid group to the metal cationic sites of TiO{sub 2} and ZnO semiconductor nanocluster surfaces. These rates are obtained directly from the ultrafast fluorescence dynamics, measured using the femotosecond upconversion technique. Coumarins 343 and D-1421 on TiO{sub 2} nanoclusters in aqueous solution display very rapid forward electron-transfer with rate constants exceeding 10{sup 13} s{sup -1}. Substantially slower rates are observed for the same coumarin TiO{sub 2} systems in methanol solution.

• OSTI ID: 560430
• Report Number(s): CONF-970443--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
66 PHYSICS
COUMARIN
DYES
ELECTRON TRANSFER
FLUORESCENCE
SURFACE AREA
TITANIUM OXIDES
ZINC OXIDES