Size-Dependent Electron Injection from Excited CdSe Quantum Dots into TiO2 Nanoparticles

J. Am. Chem. Soc., 129 (14), 4136 -4137, 2007. 10.1021/ja070099a S0002-7863(07)00099-6
Web Release Date: March 21, 2007

Size-Dependent Electron Injection from Excited CdSe Quantum Dots into TiO₂ Nanoparticles

Istvn Robel, Masaru Kuno,* and Prashant V. Kamat*

Radiation Laboratory, Department of Chemistry and Biochemistry, Department of Chemical and Biomolecular Engineering, and Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556

pkamat@nd.edu

Received January 5, 2007

Abstract:

Electron injection from excited CdSe quantum dots into TiO₂ nanoparticles can be easily modulated by controlling the particle size. Femtosecond transient absorption studies indicate that the rate constant for electron transfer from the thermalized s-state of CdSe quantum dots increases with decreasing particle size. The energy difference between the conduction bands of the two semiconductor systems acts as a driving force for the electron transfer in the normal Marcus region. An increase in the interparticle electron transfer rate constant by 3 orders of magnitude (from ~10⁷ to 10¹⁰ s^-1) has been achieved by decreasing the CdSe particle diameter from 7.5 to 2.4 nm.

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