Synthesis and Spectroscopy of Silver-Doped PbSe Quantum Dots

Matthew Beard, Elisa Link, Arthur Nozik, David Moore, Daniel Kroupa, Barbara Hughes, Boris Chernomordik, Nicholas Anderson

Research output: Contribution to journalArticlepeer-review

55 Scopus Citations

Abstract

Electronic impurity doping of bulk semiconductors is an essential component of semiconductor science and technology. Yet there are only a handful of studies demonstrating control of electronic impurities in semiconductor nanocrystals. Here, we studied electronic impurity doping of colloidal PbSe quantum dots (QDs) using a postsynthetic cation exchange reaction in which Pb is exchanged for Ag. We found that varying the concentration of dopants exposed to the as-synthesized PbSe QDs controls the extent of exchange. The electronic impurity doped QDs exhibit the fundamental spectroscopic signatures associated with injecting a free charge carrier into a QD under equilibrium conditions, including a bleach of the first exciton transition and the appearance of a quantum-confined, low-energy intraband absorption feature. Photoelectron spectroscopy confirms that Ag acts as a p-type dopant for PbSe QDs and infrared spectroscopy is consistent with k·p calculations of the size-dependent intraband transition energy. We find that to bleach the first exciton transition by an average of 1 carrier per QD requires that approximately 10% of the Pb be replaced by Ag. We hypothesize that the majority of incorporated Ag remains at the QD surface and does not interact with the core electronic states of the QD. Instead, the excess Ag at the surface promotes the incorporation of <1% Ag into the QD core where it causes p-type doping behavior.

Original languageAmerican English
Pages (from-to)10382-10394
Number of pages13
JournalJournal of the American Chemical Society
Volume139
Issue number30
DOIs
StatePublished - 2 Aug 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-67594

Keywords

  • doping
  • PbSe
  • quantum dots
  • solar-photochemistry

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