Quantum dot solar cells. harvesting light energy with CdSe nanocrystals molecularly linked to mesoscopic TiO2 films

István Robel; Vaidyanathan Subramanian; Masaru Kuno; Prashant V Kamat

doi:10.1021/ja056494n

Quantum dot solar cells. harvesting light energy with CdSe nanocrystals molecularly linked to mesoscopic TiO2 films

J Am Chem Soc. 2006 Feb 22;128(7):2385-93. doi: 10.1021/ja056494n.

Authors

István Robel¹, Vaidyanathan Subramanian, Masaru Kuno, Prashant V Kamat

Affiliation

¹ Notre Dame Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556-5674, USA.

PMID: 16478194
DOI: 10.1021/ja056494n

Abstract

By using bifunctional surface modifiers (SH-R-COOH), CdSe quantum dots (QDs) have been assembled onto mesoscopic TiO(2) films. Upon visible light excitation, CdSe QDs inject electrons into TiO(2) nanocrystallites. Femtosecond transient absorption as well as emission quenching experiments confirm the injection from the excited state of CdSe QDs into TiO(2) nanoparticles. Electron transfer from the thermally relaxed s-state occurs over a wide range of rate constant values between 7.3 x 10(9) and 1.95 x 10(11) s(-1). The injected charge carriers in a CdSe-modified TiO(2) film can be collected at a conducting electrode to generate a photocurrent. The TiO(2)-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 TiO(2)/CdSe interfaces and internal TiO(2) grain boundaries.