The effect of intensity of excitation on CdSe/ZnS quantum dots : opportunities in luminescence sensing

Sutter, Jens U. and Birch, David J. S. and Rolinski, Olaf J. (2011) The effect of intensity of excitation on CdSe/ZnS quantum dots : opportunities in luminescence sensing. Applied Physics Letters, 98 (2). 021108. ISSN 0003-6951 (https://doi.org/10.1063/1.3534784)

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Abstract

We report changes in the photophysical properties of core-shell type CdSe/ZnS quantum dots (QDs) under optical irradiation. QDs either in aqueous solution or immobilized in a silica sol gel matrix have been excited at different wavelengths and fluxes. Illumination of the sample with 140 fs 700 nm Ti:sapphire laser pulses of the peak power of the order of 4 GW/cm(2) caused gradual increase in the luminescence lifetime from an initial value of 3.5 increasing to 4.5 ns and an increase in luminescence intensity by similar to 8%. Using about 16 GW/cm(2) peak power resulted in a shortening of the luminescence lifetime to 3 ns and a decrease in intensity by similar to 75%. Both photobrightening and photodarkening were fully reversible. We discuss the kinetics of photobrightening and photodarkening and investigate the suitability of QDs as luminescence lifetime sensors with tunable parameters.

ORCID iDs

Sutter, Jens U. ORCID logoORCID: https://orcid.org/0000-0002-3782-6338, Birch, David J. S. ORCID logoORCID: https://orcid.org/0000-0001-6400-1270 and Rolinski, Olaf J. ORCID logoORCID: https://orcid.org/0000-0002-7838-779X;
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