Synthesis of highly luminescent wurtzite CdSe/CdS giant-shell nanocrystals using a fast continuous injection route

S. Christodoulou, G. Vaccaro, V. Pinchetti, F. De Donato, J. Q. Grim, Alberto Casu, Alessandro Genovese, G. Vicidomini, A. Diaspro, S. Brovelli*, L. Manna, I. Moreels

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

67 Scopus citations

Abstract

We synthesized CdSe/CdS giant-shell nanocrystals, with a CdSe core diameter between 2.8 nm and 5.5 nm, and a CdS shell thickness of up to 7-8 nm (equivalent to about 20 monolayers of CdS). Both the core and shell have a wurtzite crystal structure, yielding epitaxial growth of the shell and nearly defect-free crystals. As a result, the photoluminescence (PL) quantum efficiency (QE) is as high as 90%. Quantitative PL measurements at various excitation wavelengths allow us to separate the nonradiative decay into contributions from interface and surface trapping, giving us pathways for future optimization of the structure. In addition, the NCs do not blink, and the giant shell and concurring strong electron delocalization efficiently suppress Auger recombination, yielding a biexciton lifetime of about 15 ns. The corresponding biexciton PL QE equals 11% in 5.5/18.1 nm CdSe/CdS. Variable-temperature time-resolved PL and PL under magnetic fields further reveal that the emission at cryogenic temperature originates from a negative trion-state, in agreement with other CdSe/CdS giant-shell systems reported in the literature. This journal is

Original languageEnglish (US)
Pages (from-to)3439-3447
Number of pages9
JournalJournal of Materials Chemistry C
Volume2
Issue number17
DOIs
StatePublished - May 7 2014

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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