Ligand-controlled rates of photoinduced electron transfer in hybrid CdSe nanocrystal/poly(viologen) films

Mario Tagliazucchi, Daniel B. Tice, Christina M. Sweeney, Adam J. Morris-Cohen, Emily A. Weiss

Research output: Contribution to journalArticle

78 Citations (Scopus)

Abstract

This paper describes a study of the rates of photoinduced electron transfer (PET) from CdSe quantum dots (QDs) to poly(viologen) within thin films, as a function of the length of the ligands passivating the QDs. Ultrafast (<10 ps), quantitative PET occurs from CdSe QDs coated with HS-(CH 2) n-COOH for n = 1, 2, 5, and 7 to viologen units. The observed decrease in the magnitude of the PET rate constant with n is weaker than that expected from the decay of the electron tunneling probability across extended all-trans mercaptocarboxylic acids but well-described by electron tunneling across a collapsed ligand shell. The PET rate constants for films with n = 10 and 15 are much slower than those expected based on the trend for n = 1-7; this deviation is ascribed to the formation of bundles of ligands on the surface of the QD that make the tunneling process prohibitively slow by limiting access of the viologen units to the surfaces of the QDs. This study highlights the importance of molecular-level morphology of donor and acceptor materials in determining the rate and yield of interfacial photoinduced electron transfer in thin films.

Original languageEnglish
Pages (from-to)9907-9917
Number of pages11
JournalACS nano
Volume5
Issue number12
DOIs
Publication statusPublished - Dec 27 2011

Keywords

  • CdSe quantum dot
  • intermolecular structure
  • layer-by-layer deposition
  • photoinduced electron transfer
  • poly(viologen)
  • transient absorption

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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