Effects of post-synthesis processing on CdSe nanocrystals and their solids: Correlation between surface chemistry and optoelectronic properties

E. D. Goodwin, Benjamin T. Diroll, Soong Ju Oh, Taejong Paik, Christopher B. Murray, Cherie R. Kagan

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

In this work, we report the effects on CdSe nanocrystal (NC) surface chemistry of acetone and methanol when used as the antisolvents for NC washing and as the solvents for ligand exchange of NC solids with ammonium thiocyanate (NH4SCN). We find that NCs washed with methanol have significantly fewer remaining organic ligands and lower photoluminescence quantum yield than those washed with acetone. When used as the ligand exchange solvent, methanol leaves more organic ligands and introduces fewer bound thiocyanates on the NC surface than when acetone is used. We demonstrate the effect of these different surface chemistries on NC solid optoelectronic properties through photoconductivity measurements, showing a greater photocurrent in NC solids with greater organic ligand coverage. We also show that NC washing with methanol or ligand exchange with NH4SCN in methanol removes a significant number of surface Cd atoms from the NCs, creating Cd vacancies that act as traps for recombination. Independent of the wash and exchange process, the NC surface may be repaired by introducing CdCl2 to the NC surface, enhancing the measured photocurrent. (Chemical Equation Presented).

Original languageEnglish
Pages (from-to)27097-27105
Number of pages9
JournalJournal of Physical Chemistry C
Volume118
Issue number46
DOIs
Publication statusPublished - 2014 Nov 20
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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