Electric-field-induced changes in absorption and emission spectra of CdS nanoparticles doped in a polymer film

Yuhki Ohara, Takakazu Nakabayashi, Kentaro Iwasaki, Tsukasa Torimoto, Bunsho Ohtani, Takayuki Hiratani, Katsuaki Konishi, Nobuhiro Ohta

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Electric-field-induced changes in absorption and emission spectra of colloidal CdS nanoparticles ranging in size from 1.0 to 5.0 nm in diameter have been measured by using electric field modulation spectroscopy. The analysis of the electroabsorption spectra indicates that the dipole moment in the first exciton state becomes larger with increasing particle size. The presence of the large dipole moment following photoexcitation into the first exciton band suggests that the CdS nanoparticles have large CT character in the first exciton state. The quantum yields both of the exciton emission and of the trap emission are markedly reduced by application of an electric field. On the basis of the direct measurements of the field-induced change in emission decay profile, it is suggested that the field-induced de-enhancement of these emission yields results from the field-induced decreases both in lifetime and in initial population of each emitting state. It is also found that the emission intensity of CdS nanoparticles increases under the UV light irradiation in air and decreases in a vacuum condition and that fluorescence lifetime in the former case is longer than that in the latter. This enhancement and de-enhancement process in emission intensity is almost reversible at least in several cycles.

Original languageEnglish
Pages (from-to)20927-20936
Number of pages10
JournalJournal of Physical Chemistry B
Volume110
Issue number42
DOIs
Publication statusPublished - 2006 Oct 26
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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