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Enhanced photo-conversion efficiency of CdSe–ZnS core–shell quantum dots with Aunanoparticles on TiO2electrodes
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- Authors
- Mi-Hee Jung, Man Gu Kang
- Issue Date
- 2011-02
- Citation
- Journal of Materials Chemistry, v.21, no.8, pp.2694-2700
- ISSN
- 0959-9428
- Publisher
- Royal Society of Chemistry (RSC)
- Language
- English
- Type
- Journal Article
- Abstract
- This study demonstrates that configurations that include gold nanoparticles (Au NPs) as the primary layer attached to a TiO2 electrode with quantum dots (QDs) as the secondary layer have superior photoelectrochemical properties. We found that all Au-QD nanoparticle hybrid systems reveal enhanced photocurrent generation as compared to only a QD-nanoparticle interface. The enhanced Jsc is attributed to sensitization that results indirectly from quantum dots becoming attached to Au NPs by intramolecular charge transfers. As a result of the improved performance, the overall energy conversion efficiency was increased by 100% as compared to that of a reference cell without Au NPs at 100 mW cm-2. When (CdSe)ZnS is prepared from Au-coated TiO2, incident photon-to-current efficiency values approaching 20% can be achieved by (CdSe)ZnS devices. In the electrochemical impedance spectroscopy results, the intermediate frequency region of the Au-QD cells was more significantly reduced compared to that in bare QD cells due to the enhanced charge separation that occurs in the Au-QD structure. Mott-Schottky (C-2-) analysis shows that the lowest acceptor and donor densities having a positive effect on the efficiency could be found in (CdSe)ZnS-Au/TiO2 cells. Therefore, (CdSe)ZnS-Au/TiO2 has a very thin depletion layer that is restricted to the surface of Au/TiO 2. Consequently, this system can be employed to enhance the effective efficiency in the design of the QD-sensitized solar cells. © 2011 The Royal Society of Chemistry.
- KSP Keywords
- Au nanoparticles(Au-NPs), Au/TiO 2, Charge transfer, Conversion efficiency(C.E.), Depletion Layer, Electrochemical Impedance Spectroscopy, Energy conversion efficiency, Gold Nanoparticles(GNPs), Hybrid system, Improved performance, Mott-Schottky