Blinking Statistics and Excitation-Dependent Luminescence Yield in Si and CdSe Nanocrystals
2014 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 4, 2202-2208 p.Article in journal (Refereed) Published
ON-OFF intermittency or blinking is a phenomenon observed in single quantum emitters, which reduces their overall light emission. Even though it seems to be a fundamental property of quantum dots (QDs), substantial differences can be found in the blinking statistics of different nanocrystals. This work compares the blinking of numerous single, oxide-capped Si nanocrystals with that of CdSe/ZnS core-shell nanocrystals, measured under the same conditions in the same experimental system and over a broad range of excitation power densities. We find that ON- and OFF-times can be described by exponential statistics in Si QDs, as opposed to power-law statistics for the CdSe nanocrystals. The type of blinking (power-law or monoexponential) does not depend on excitation but seems to be an intrinsic property of the material system. Upon increasing excitation power, the duty cycle of Si quantum dots remains constant, whereas it decreases for CdSe nanocrystals, which is readily explained by blinking statistics. Both ON-OFF and OFF-ON transitions can be regarded as light-induced in Si/SiO2 QDs, while the OFF-ON transition in CdSe/ZnS nanocrystals is not stimulated by photons. The differences in blinking behavior in these systems will be discussed.
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2014. Vol. 118, no 4, 2202-2208 p.
Single Quantum-Dot, Fluorescence Intermittency, Photoluminescence, Photoionization, Spectroscopy
IdentifiersURN: urn:nbn:se:kth:diva-142507DOI: 10.1021/jp4100685ISI: 000330610200053ScopusID: 2-s2.0-84893243869OAI: oai:DiVA.org:kth-142507DiVA: diva2:703523
FunderSwedish Research Council
QC 201403072014-03-072014-03-062015-03-25Bibliographically approved