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Unity quantum yield of photogenerated charges and band-like transport in quantum-dot solids

Nature Nanotechnology volume 6, pages 733–739 (2011)Cite this article

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Abstract

Solid films of colloidal quantum dots show promise in the manufacture of photodetectors and solar cells. These devices require high yields of photogenerated charges and high carrier mobilities, which are difficult to achieve in quantum-dot films owing to a strong electron–hole interaction and quantum confinement. Here, we show that the quantum yield of photogenerated charges in strongly coupled PbSe quantum-dot films is unity over a large temperature range. At high photoexcitation density, a transition takes place from hopping between localized states to band-like transport. These strongly coupled quantum-dot films have electrical properties that approach those of crystalline bulk semiconductors, while retaining the size tunability and cheap processing properties of colloidal quantum dots.

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Figure 1: Characterization of PbSe QD solids.
Figure 2: Ultrafast response of QD solids to optical excitation.
Figure 3: TRMC photoconductivity of a PbSe QD solid at room temperature.
Figure 4: Temperature dependence of photoconductivity.
Figure 5: Dependence of the quantum yield of charge carrier photogeneration on temperature in the Onsager–Braun model.
Figure 6: Schematic of distribution of electronic states for a QD and its 12 nearest neighbours (as in a close-packed lattice).

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Acknowledgements

This work was supported by SenterNovem (project SELECT) and the Netherlands Organisation for Scientific Research (NWO), Division of Chemical Sciences (VICI award 700.53.443). The 3TU Centre for Sustainable Energy Technologies is acknowledged for financial support. A.J.H. acknowledges financial support through a NWO-VENI grant. The authors thank S. Patwardhan for useful discussions and M. Murra for the photograph of the film.

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Author notes

  1. Elise Talgorn and Yunan Gao: These authors contributed equally to this work

Authors and Affiliations

  1. Department of Chemical Engineering, Optoelectronic Materials Section, Delft University of Technology, Julianalaan 136, 2628, BL Delft, The Netherlands

    Elise Talgorn, Yunan Gao, Michiel Aerts, Lucas T. Kunneman, Juleon M. Schins, T. J. Savenije, Arjan J. Houtepen & Laurens D. A. Siebbeles

  2. Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628, CJ Delft, The Netherlands

    Yunan Gao, Marijn A. van Huis & Herre S. J. van der Zant

  3. EMAT, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium

    Marijn A. van Huis

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Contributions

E.T. and A.J.H. designed the experiment, analysed data and wrote the paper. E.T. performed TRMC experiments. Y.G. and M.A. synthesized the quantum dots and developed the film preparation procedure. Y.G. performed transient absorption measurements and simulations of the mobility. L.K. performed terahertz conductivity experiments. T.J.S. designed the temperature-dependent TRMC setup. J.M.S. developed the analytical deconvolution procedure. M.v.H. performed TEM experiments. H.S.J.v.d.Z. and L.D.A.S. gave conceptual advice.

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Correspondence to Arjan J. Houtepen.

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Talgorn, E., Gao, Y., Aerts, M. et al. Unity quantum yield of photogenerated charges and band-like transport in quantum-dot solids. Nature Nanotech 6, 733–739 (2011). https://doi.org/10.1038/nnano.2011.159

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