Response of semiconductor nanocrystals to extremely energetic excitation

Lazaro A. Padilha, Wan K. Bae, Victor I. Klimov, Jeffrey M. Pietryga, Richard D. Schaller

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Using a combination of transient photoluminescence and transient cathodoluminescence (trCL) we, for the first time, identify and quantify the distribution of electronic excitations in colloidal semiconductor nanocrystals (NCs) under high-energy excitation. Specifically, we compare the temporally and spectrally resolved radiative recombination produced following excitation with 3.1 eV, subpicosecond photon pulses, or with ionizing radiation in the form of 20 keV picosecond electron pulses. Using this approach, we derive excitation branching ratios produced in the scenario of energetic excitation of NCs typical of X-ray, neutron, or gamma-ray detectors. Resultant trCL spectra and dynamics for CdSe NCs indicate that all observable emission can be attributed to recombination between states within the quantum-confined nanostructure with particularly significant yields of trions and multiexcitons produced by carrier multiplication. Our observations offer direct insight into the transduction of atomic excitation into quantum-confined states within NCs, explain that the root cause of poor performance in previous scintillation studies arises from efficient nonradiative Auger recombination, and suggest routes for improved detector materials.

Original languageEnglish
Pages (from-to)925-932
Number of pages8
JournalNano letters
Volume13
Issue number3
DOIs
Publication statusPublished - Mar 13 2013

Keywords

  • Nanocrystal
  • cathodoluminescence
  • charged nanocrystal
  • multiexciton
  • quantum dot
  • radiation detection

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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