Organic surfactant-controlled composition of the surfaces of CdSe quantum dots

Adam J. Morris-Cohen, Matthew T. Frederick, G. Daniel Lilly, Eric A. McArthur, Emily A. Weiss

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

The ratio of Cd to Se (Cd/Se) within colloidal CdSe quantum dots (QDs) synthesized with 90% trioctylphosphine oxide (TOPO) as the coordinating solvent increases from 1.2:1 for QDs with radius R ≥ 3.3 nm to 6.5:1 for R = 1.9 nm, as measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The highest value of Cd/Se reported previously for CdSe QDs was 1.8:1. The dependence of Cd/Se on R fits a geometric model that describes the QDs as CdSe cores with Cd/Se = 1:1 encapsulated by a shell of Cd-organic complexes. Use of 99% TOPO as the coordinating solvent produces QDs with Cd/Se = 1:1 for all values of R, and use of 99% TOPO "doped" with n-octylphosphonic acid (OPA), an impurity in 90% TOPO, produces QDs with values of Cd/Se up to 1.5:1. These results imply that Cd enrichment of the QDs is driven by tight-binding Cd2+-alkylphosphonate complexes that stabilize the interface between the polar CdSe core and the organic medium.

Original languageEnglish
Pages (from-to)1078-1081
Number of pages4
JournalJournal of Physical Chemistry Letters
Volume1
Issue number7
DOIs
Publication statusPublished - Apr 1 2010

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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