Concentration and size dependence of peak wavelength shift on quantum dots in colloidal suspension

Benjamin S. Rinehart, Caroline G.L. Cao

Research output: Contribution to journalArticlepeer-review


Quantum dots (QDs) are semiconductor nanocrystals that have significant advantages over organic fluorophores, including their extremely narrow Gaussian emission bands and broad absorption bands. Thus, QDs have a wide range of potential applications, such as in quantum computing, photovoltaic cells, biological sensing, and electronics. For these applications, aliasing provides a detrimental effect on signal identification efficiency. This can be avoided through characterization of the QD fluorescence signals. Characterization of the emissivity of CdTe QDs as a function of concentration (1 to 10 mg/ml aqueous) was conducted on 12 commercially available CdTe QDs (emission peaks 550 to 730 nm). The samples were excited by a 50-mW 405-nm laser with emission collected via a free-space CCD spectrometer. All QDs showed a redshift effect as concentration increased. On average, the CdTe QDs exhibited a maximum shift of +35.6 nm at 10 mg/ml and a minimum shift of +27.24 nm at 1 mg/ml, indicating a concentration dependence for shift magnitude. The concentration-dependent redshift function can be used to predict emission response as QD concentration is changed in a complex system.

Original languageEnglish (US)
Article number087106
JournalOptical Engineering
Issue number8
StatePublished - Aug 1 2016
Externally publishedYes


  • fluorescence
  • Forster resonance energy transfer
  • quantum dots
  • redshift
  • spectroscopy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • General Engineering


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