Photosensitized electron injection in colloidal semiconductors
Journal Article
·
· J. Am. Chem. Soc.; (United States)
Photosensitized electron injection in semiconductor particles was studied by using aqueous eosin (EO)/colloidal TiO/sub 2/ as the model system. Adsorption of EO onto the surface of TiO/sub 2/ occurs quantitatively at pH <6 and leads to red-shifted absorption and emission spectra. Electron injection in the conduction band of the TiO/sub 2/ particles takes place from the S/sub 1/ state of adsorbed eosin and occurs with a rate constant of 8.5 x 10/sup 8/ s/sup -1/ and a quantum yield of 38% (pH 3). The quantum yield decreases at high eosin occupancy of the particles due to concentration quenching. Back-electron transfer occurs via a rapid intraparticle reaction between EO/sup +/ e/sub CB//sup -/ pairs associated with the same TiO/sub 2/ host aggregate and via a slower process involving bulk diffusion. The rate constant for intraparticle recombination is 2 x 10/sup 5/ s/sup -1/, i.e., 4 x 10/sup 3/ times slower than that for electron injection. This enables slight-induced charge separation to be sustained on a colloidal TiO/sub 2/ particle for several microseconds, which is sufficient to trap the electron by a noble metal deposit. Implications for light energy conversion devices are discussed.
- Research Organization:
- Ecole Polytechnique Federale, Lausanne, Switzerland
- OSTI ID:
- 5954409
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 106:22; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
36 MATERIALS SCIENCE
360600 -- Other Materials
CARBOXYLIC ACIDS
CHALCOGENIDES
COLLOIDS
CONVERSION
DATA
DISPERSIONS
DYES
ELECTRON TRANSFER
ENERGY CONVERSION
EOSIN
EXPERIMENTAL DATA
HYDROXY ACIDS
INDICATORS
INFORMATION
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SEMICONDUCTOR DEVICES
SOLAR ENERGY CONVERSION
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
36 MATERIALS SCIENCE
360600 -- Other Materials
CARBOXYLIC ACIDS
CHALCOGENIDES
COLLOIDS
CONVERSION
DATA
DISPERSIONS
DYES
ELECTRON TRANSFER
ENERGY CONVERSION
EOSIN
EXPERIMENTAL DATA
HYDROXY ACIDS
INDICATORS
INFORMATION
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SEMICONDUCTOR DEVICES
SOLAR ENERGY CONVERSION
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS