First Principles Calculations of Nanoplatelet Heterostructures: Optoelectronic Properties

ORAL

Abstract

Two-dimensional, atomically precise core-shell nanoplatelets (NPLs) have recently been synthesized with no sample inhomogeneity, leading to remarkable photoluminescence quantum efficiencies and tunable electronic properties dependent on NPL thickness [1]. Here we use Density Functional Theory and the Qbox code [2] to investigate the unique optoelectronic properties of CdS/CdSe core-shell NPLs. We show that, compared to a pure CdSe NPL of the same thickness, the band gap and dielectric constant of the core-shell NPLs decrease consistent with experimental results, corresponding to a larger exciton binding energy by approximately 30%. We attribute our findings to an expansion of the lattice constant of the core-shell NPLs in the axial direction, leading to a strain-induced modification of the electronic properties of the system. In contrast to nanoparticles, where the optoelectronic properties are governed by quantum confinement, we find that the properties of NPLs depend on a subtle interplay between quantum confinement and strain induced in the NPLs by the heterostructured interfaces.

[1] Hazarika, Fedin, Hong, Guo, Srivastava, Cho, Coropceanu, Portner, Diroll, Greenwood, Mazzotti, Galli, Klie, Talapin, Submitted.
[2] www.qboxcode.org

*Supported by DOE grant No. DE-FG02-06ER46262.

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Presenters

  • Arin R Greenwood

    • Institute for Molecular Engineering, University of Chicago

Authors

  • Arin R Greenwood

    • Institute for Molecular Engineering, University of Chicago

  • Sergio Mazzotti

    • Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich

  • Abhijit Hazarika

    • Department of Chemistry and James Franck Institute, University of Chicago

  • Igor Coropceanu

    • Department of Chemistry and James Franck Institute, University of Chicago

  • Dmitri Talapin

    • Department of Chemistry and James Franck Institute, University of Chicago

  • Giulia Galli

    • Institute for Molecular Engineering, University of Chicago
    • Institute for Molecular Engineering and Materials Science Division, University of Chicago and Argonne National Laboratory
    • University of Chicago, Argonne National Lab
    • Institute for Molecular Engineering and Department of Chemistry, University of Chicago
    • University of Chicago and Argonne National Laboratory
    • The Institute for Molecular Engineering, University of Chicago
    • University of Chicago
    • Institute for Molecular Engineering, Univ. of Chicago; Department of Chemistry, Univ. of Chicago; Materials Science Division, Argonne National Laboratory