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Molecular control of quantum-dot internal electric field and its application to CdSe-based solar cells

Nature Materials volume 10, pages 974–979 (2011)Cite this article

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Abstract

Inorganic nanocrystals are attractive materials for solar-cell applications. However, the performance of such devices is often limited by an insufficient alignment of energy levels in the nanocrystals. Here, we report that by attaching two different molecules to a single quantum dot or nanocrystal one can induce electric fields large enough to significantly alter the electronic and optoelectronic properties of the quantum dot. This electric field is created within the nanocrystals owing to a mixture of amine- and thiol-anchor-group ligands. Examining the steady state as well as temporal evolution of the optical properties and the nuclear magnetic resonances of the nanocrystals we found that the first excitonic peak shifts as a function of the capping-layer composition. We also demonstrate that the use of a mixed-ligand-induced electric field markedly enhances the charge generation efficiency in layer-by-layer CdSe-nanocrystal-based solar cells, thus improving the overall cell efficiency.

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Figure 1: Chemical structure of the ligands used in this work.
Figure 2: The effect of added MTP ligands on the absorption spectrum of HDA-capped CdSe.
Figure 3: Gradual adsorption of MTP ligands to HDA-capped CdSe nanocrystals.
Figure 4: Addition of excess MTP ligand to PMA-saturated nanocrystals.
Figure 5: Addition of PMA ligands to MTP-capped CdSe nanocrystals.
Figure 6: CdSe-nanocrystal-based solar cells.

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Acknowledgements

We are grateful to U. Banin and T. Mokari for discussions. We acknowledge partial support from the Ollendorff Minerva Center.

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Authors and Affiliations

  1. Department of Electrical Engineering, Zisapel Nano-electronics Centre, Technion—Israel Institute of Technology, Technion City, Haifa 32000, Israel

    Nir Yaacobi-Gross, Michal Soreni-Harari, Marina Zimin & Nir Tessler

  2. Schulich Faculty of Chemistry and Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 32000, Israel

    Shifi Kababya & Asher Schmidt

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  1. Nir Yaacobi-Gross
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All authors contributed to the work presented in this paper.

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Correspondence to Nir Tessler.

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Yaacobi-Gross, N., Soreni-Harari, M., Zimin, M. et al. Molecular control of quantum-dot internal electric field and its application to CdSe-based solar cells. Nature Mater 10, 974–979 (2011). https://doi.org/10.1038/nmat3133

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