Photoenhancement of Luminescence in Colloidal CdSe Quantum Dot Solutions

Marcus Jones, Jovan Nedeljkovic, Randy J. Ellingson, Arthur J. Nozik, Garry Rumbles

Research output: Contribution to journalArticlepeer-review

347 Scopus Citations


Enhancement of the photoluminescence (PL) of colloidal CdSe and (core)shell (CdSe)ZnS quantum dots has been observed when the dots are illuminated above the band-gap energy. The effect occurs in dots suspended in a variety of organic or aqueous environments. During periods of constant illumination, the exciton PL quantum yield was found to reach a value of up to 60 times that of the solution of as-prepared quantum dots and, if illumination continued, subsequently declined slowly because of photooxidation. When returned to the dark, the PL reverted to near its original value. The rate and magnitude of photoenhancement are found to depend on the illumination wavelength, the presence of a ZnS shell, the solvent environment, and the concentration of surfactant molecules. Time-resolved measurements of the fluorescence decay reveal multiexponential kinetics and an average lifetime that lengthens during the illumination period and shortens when quantum dots are returned to darkness. It is postulated that the stabilization of surface trap states, lengthening their average lifetime, could occur by a light-activated rearrangement of surfactant molecules, thus increasing the probability of thermalization back to the lowest emitting exciton state and enhancing the quantum dot PL.

Original languageAmerican English
Pages (from-to)11346-11352
Number of pages7
JournalJournal of Physical Chemistry B
Issue number41
StatePublished - 2003

NREL Publication Number

  • NREL/JA-590-35460


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