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Synergism in binary nanocrystal superlattices leads to enhanced p-type conductivity in self-assembled PbTe/Ag2Te thin films

Nature Materials volume 6, pages 115–121 (2007)Cite this article

Abstract

The ordered cocrystallization of nanoparticles into binary superlattices enables close contact of nanocrystals with distinct physical properties, providing a route to ‘metamaterials’ design. Here we present the first electronic measurements of multicomponent nanocrystal solids composed of PbTe and Ag2Te, demonstrating synergistic effects leading to enhanced p-type conductivity. First, syntheses of size-tuneable PbTe and Ag2Te nanocrystals are presented, along with deposition as thin-film nanocrystal solids, whose electronic transport properties are characterized. Next, assembly of PbTe and Ag2Te nanocrystals into AB binary nanocrystal superlattices is demonstrated. Furthermore, binary composites of varying PbTe–Ag2Te stoichiometry (1:1 and 5:1) are prepared and electronically characterized. These composites show strongly enhanced (conductance ∼100-fold increased in 1:1 composites over the sum of individual conductances of single-component PbTe and Ag2Te films) p-type electronic conductivity. This observation, consistent with the role of Ag2Te as a p-type dopant in bulk PbTe, demonstrates that nanocrystals can behave as dopants in nanostructured assemblies.

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Figure 1: Synthesis and characterization of PbTe nanocrystals.
Figure 2: Evolution of particle size and shape in Ag2Te nanocrystals.
Figure 3: Assembly of binary nanocrystal superlattices consisting of PbTe and Ag2Te.
Figure 4: Electronic characterization of single-component nanocrystal films.
Figure 5: Characterization of binary PbTe–Ag2Te nanocrystal films.

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Acknowledgements

We gratefully thank the ONR (N00014-02-1-0867) for funding and support.

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Authors and Affiliations

  1. I.B.M. T. J. Watson Research Center, Nanoscale Materials and Devices Group, 1101 Kitchawan Road, Yorktown Heights, New York, 10598, USA

    Jeffrey J. Urban, Cherie R. Kagan & Christopher B. Murray

  2. The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA

    Dmitri V. Talapin & Elena V. Shevchenko

Authors
  1. Jeffrey J. Urban
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  2. Dmitri V. Talapin
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  3. Elena V. Shevchenko
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  4. Cherie R. Kagan
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  5. Christopher B. Murray
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Contributions

J.J.U. executed all of the materials syntheses, superlattice assembly, transport measurements and data analysis presented here. D.V.T. and E.V.S. provided general assistance and project suggestions. C.R.K. provided transport equipment and technical advice. C.B.M. provided general assistance, advice and project planning.

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Correspondence to Jeffrey J. Urban.

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Supplementary Information

Supplementary Information; Figures S1, S2, S3, S4, S5, S6 and S7 (PDF 709 kb)

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Urban, J., Talapin, D., Shevchenko, E. et al. Synergism in binary nanocrystal superlattices leads to enhanced p-type conductivity in self-assembled PbTe/Ag2Te thin films. Nature Mater 6, 115–121 (2007). https://doi.org/10.1038/nmat1826

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