Quantum Dot Solar Cells. Harvesting Light Energy with CdSe Nanocrystals Molecularly Linked to Mesoscopic TiO2 Films

István Robel,† Vaidyanathan Subramanian,†§ Masaru Kuno,*†‡ and Prashant V. Kamat*†‡§;
Contribution from the Notre Dame Radiation Laboratory, Department of Chemistry and Biochemistry, Department of Chemical and Biomolecular Engineering, and Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556-5674
J. Am. Chem. Soc., 2006, 128 (7), pp 2385–2393
DOI: 10.1021/ja056494n
Publication Date (Web): January 31, 2006
Copyright © 2006 American Chemical Society
†

 Notre Dame Radiation Laboratory.

,

 Department of Physics.

,
§

 Department of Chemical and Biomolecular Engineering.

,
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

,
‡

 Department of Chemistry and Biochemistry.

, pkamat@nd.edu, ; , mkuno@nd.edu

Abstract

Abstract Image

By using bifunctional surface modifiers (SH−R−COOH), CdSe quantum dots (QDs) have been assembled onto mesoscopic TiO2 films. Upon visible light excitation, CdSe QDs inject electrons into TiO2 nanocrystallites. Femtosecond transient absorption as well as emission quenching experiments confirm the injection from the excited state of CdSe QDs into TiO2 nanoparticles. Electron transfer from the thermally relaxed s-state occurs over a wide range of rate constant values between 7.3 × 109 and 1.95 × 1011 s-1. The injected charge carriers in a CdSe-modified TiO2 film can be collected at a conducting electrode to generate a photocurrent. The TiO2−CdSe composite, when employed as a photoanode in a photoelectrochemical cell, exhibits a photon-to-charge carrier generation efficiency of 12%. Significant loss of electrons occurs due to scattering as well as charge recombination at TiO2/CdSe interfaces and internal TiO2 grain boundaries.

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History

  • Published In Issue February 22, 2006
  • Received September 21, 2005

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