Photoluminescence of colloidal CdSe/ZnS quantum dots under oxygen atmosphere

The effects of oxygen versus vacuum ambients on colloidal CdSe/ZnS quantum dots (QDs) were studied using both continuous and time-resolved photoluminescence (PL) measurements. The PL intensities were found to be an order of magnitude higher in an oxygen atmosphere, which is explained by the passivat...

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Bibliographic Details
Published in:IEEE transactions on nanotechnology 2005-09, Vol.4 (5), p.632-636
Main Authors: Gia-Wei Shu, Wan-Zhen Lee, Shu, I.-J., Ji-Lin Shen, James Cheng-An Lin, Chang, W.H., Ruoh-Chyu Ruaan, Wu Ching Chou
Format: Article
Language:English
Subjects:
Absorption
Atmosphere
Atmospheric measurements
Cadmium selenides
Carriers
Charge carrier lifetime
Colloids
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Decay rate
Elementary particle vacuum
Exact sciences and technology
Intermetallics
Optical properties
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
Passivation
Photoluminescence
Physics
Quantum dots
quantum dots (QDs)
Radiative recombination
Zinc compounds
Zinc sulfides
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Summary:The effects of oxygen versus vacuum ambients on colloidal CdSe/ZnS quantum dots (QDs) were studied using both continuous and time-resolved photoluminescence (PL) measurements. The PL intensities were found to be an order of magnitude higher in an oxygen atmosphere, which is explained by the passivation of surface defects by oxygen absorption. The decay of PL intensities can be best fitted by a biexponential function with lifetimes of approximately 1 ns for the fast decay and approximately 10 ns for the slow decay. Based on the emission-energy dependence of carrier lifetimes and of the amplitude ratio of the fast-decay component to the slow-decay component, we suggest that the fast and slow PL decay of colloidal CdSe/ZnS QDs is caused by the recombination of delocalized carriers in the internal core states and the localized carriers in the surface states, respectively.
ISSN:1536-125X
1941-0085
DOI:10.1109/TNANO.2005.851445