Radiative exciton recombination dynamics in QD-tagged polystyrene microspheres |
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Authors: | Gospodinka Gicheva Anna-Maria Panniello Michela Corricelli Angela Agostiano Ceco Dushkin Georgi Yordanov |
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Affiliation: | (1) Faculty of Chemistry, Sofia University “St. Kliment Ohridski”, 1 James Bourchier Blvd, 1164 Sofia, Bulgaria;(2) Department of Chemistry, Faculty of Science, University of Bari and CNR-IPCF (Bari), 4-70125 Bari, Italy;(3) Present address: Department of Chemistry, University of Mining and Geology “St. Ivan Rilski”, Studentski Grad, “Hristo Botev” Str, Sofia, Bulgaria; |
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Abstract: | Fluorescent polystyrene microspheres are prepared by the incorporation of fluorescent CdSe/CdS core/shell semiconductor nanocrystals
(quantum dots, QDs) using the emulsification/solvent evaporation method. The radiative exciton recombination dynamics is investigated
by nanosecond time-resolved fluorescence spectroscopy at ambient conditions. The time constants of fast and slow fluorescence
decay in QDs, dispersed in toluene, were 3.5 and 17.8 ns, respectively. For the QD-tagged microspheres, the time constants
of fast and slow processes were ~2–3 and ~11–12 ns, respectively, and did not depend significantly on the QD-content of the
microspheres. The fast decay component could be attributed to the recombination of delocalized exciton in the internal core
states, and the slow component was attributed to the localized exciton in the surface states. It was found that the ratio
of amplitudes of the fast and slow processes also changed after incorporation of QDs in microspheres. The observed differences
in fluorescence decay between non-entrapped QDs and QD-tagged microspheres were probably due to energy transfer between the
nanocrystals, which were in close proximity inside the microspheres. The obtained fluorescent QD-tagged microspheres are characterized
by the other methods as well, which makes them of value for various applications as optical materials. |
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