Rapid phosphine-free synthesis of CdSe quantum dots: promoting the generation of Se precursors using a radical initiator

Bo Hou, David Benito-Alifonso, Richard Webster, David Cherns, M. Carmen Galan, David J. Fermin*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

23 Citations (Scopus)
403 Downloads (Pure)

Abstract

The replacement of phosphine containing compounds in the synthesis of II–VI quantum dots (QDs) via the ‘hot-injection’ method has received considerable attention in recent years, in particular toward scaling-up production. A key bottleneck in current approaches is the poor solubility of elemental Se in solvents such as 1-octadecene (1-ODE) or oleylamine requiring a heating temperature of 200 °C for several hours, or the introduction of additives such as alkylthiols or NaBH4, or replacement by SeO2. In the present work, we elucidate the fundamental steps in the dissolution of elemental Se in 1-ODE and oleylamine with the view of facilitating the large-scale synthesis of CdSe QDs. The main organoselenium species generated during the solubilisation of elemental Se in 1-ODE and oleylamine were identified by 1D and 2D NMR spectroscopy (1H, 13C and 77Se). Experimental evidence suggests that the rate determining step is the formation of Se radicals, via homolytic cleavage of the Se–Se bond, that attack the allylic proton in 1-ODE and oleylamine. Plausible reaction pathways in both systems are proposed. Finally, we demonstrate that the radical-mediated solubilisation of Se can be significantly accelerated by the addition of azobisisobutyronitrile (AIBN), a common radical initiator used in the polymer industry. In this way, a highly concentrated Se precursor was prepared. The “hot-injection” of the Se precursor into CdO containing 1-ODE solution leads to the formation of highly luminescent CdSe QDs with a well-defined cubic structure.
Original languageEnglish
Pages (from-to)6879-6886
Number of pages8
JournalJournal of Materials Chemistry A
Volume2
Issue number19
Early online date19 Feb 2014
DOIs
Publication statusPublished - 21 May 2014

Keywords

  • METAL SELENIDE NANOCRYSTALS
  • SEMICONDUCTOR NANOCRYSTALS
  • CDTE NANOCRYSTALS
  • LIGHT HARVESTERS
  • HIGH-YIELD
  • SOLVENTS
  • DISSOLUTION
  • OLEYLAMINE
  • STABILITY
  • INJECTION

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