Multiexciton dynamics in infrared-emitting colloidal nanostructures probed by a superconducting nanowire single-photon detector

Richard L. Sandberg, Lazaro A. Padilha, Muhammad M. Qazilbash, Wan Ki Bae, Richard D. Schaller, Jeffrey M. Pietryga, Martin J. Stevens, Burm Baek, Sae Woo Nam, Victor I. Klimov

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40 Citations (Scopus)

Abstract

Carrier multiplication (CM) is the process in which absorption of a single photon produces multiple electron-hole pairs. Here, we evaluate the effect of particle shape on CM efficiency by conducting a comparative study of spherical nanocrystal quantum dots (NQDs) and elongated nanorods (NRs) of PbSe using a time-resolved technique that is based on photon counting in the infrared using a superconducting nanowire single-photon photodetector (SNSPD). Due to its high sensitivity and low noise levels, this technique allows for accurate determination of CM yields, even with the small excitation intensities required for quantitative measurements, and the fairly low emission quantum yields of elongated NR samples. Our measurements indicate an up to ∼60% increase in multiexciton yields in NRs versus NQDs, which is attributed primarily to a decrease in the electron-hole pair creation energy. These findings suggest that shape control is a promising approach for enhancing the CM process. Further, our work demonstrates the effectiveness of the SNSPD technique for the rapid screening of CM performance in infrared nanomaterials.

Original languageEnglish
Pages (from-to)9532-9540
Number of pages9
JournalACS nano
Volume6
Issue number11
DOIs
Publication statusPublished - Nov 27 2012

Keywords

  • Auger recombination
  • carrier multiplication
  • multiexciton
  • nanocrystal quantum dot
  • nanorod
  • photoluminesence
  • superconducting nanowire single-photon detector

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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    Sandberg, R. L., Padilha, L. A., Qazilbash, M. M., Bae, W. K., Schaller, R. D., Pietryga, J. M., Stevens, M. J., Baek, B., Nam, S. W., & Klimov, V. I. (2012). Multiexciton dynamics in infrared-emitting colloidal nanostructures probed by a superconducting nanowire single-photon detector. ACS nano, 6(11), 9532-9540. https://doi.org/10.1021/nn3043226