Controllable photo-brightening/photo-darkening of semiconductor quantum dots under laser irradiation

Victor Krivenkov; Anna Tretyachenko; Pavel S. Samokhvalov; Alexander A. Chistyakov; Igor Nabiev

doi:10.1117/12.2228815

21 April 2016 Controllable photo-brightening/photo-darkening of semiconductor quantum dots under laser irradiation

Victor Krivenkov, Anna Tretyachenko, Pavel S. Samokhvalov, Alexander A. Chistyakov, Igor Nabiev

Proceedings Volume 9884, Nanophotonics VI; 98843L (2016) https://doi.org/10.1117/12.2228815
Event: SPIE Photonics Europe, 2016, Brussels, Belgium

Abstract

It has been demonstrated that photo-induced changes in the optical properties of semiconductor quantum dots (QDs) can be controlled by tuning the parameters of their laser irradiation to vary the relative contributions of photo-brightening and photo-darkening of QDs. For this purpose, the effects of the QD size, photon energy, and intensity of irradiation of QDs on the competing processes of photo-darkening and photo-brightening have been investigated. We have found that photo-brightening of QDs is not accompanied by detectable growth of their photoluminescence (PL) decay time, this process being most pronounced for QDs with an originally low PL quantum yield (QY). In this case, an increase in the PL QY is assumed to be caused by transition of some QDs from the dark (non-emissive) state to the bright (emissive) state. On the other hand, the photo-darkening effect, which was observed only under UV irradiation at 266 nm, was accompanied by simultaneous drop of both the QD QY and their PL decay time. We have also found that, at a constant dose of absorbed energy, the photo-brightening and photo-darkening processes do not depend on the excitation intensity. Thus, the photo-induced changes in the optical properties of QDs are one-photon processes. These data may help to optimize the QD operational conditions in practical applications requiring their intense excitation and add to understanding the fundamental mechanisms of the irreversible photo-induced changes that occur in colloidal QDs under illumination.

Citation Download Citation

Victor Krivenkov, Anna Tretyachenko, Pavel S. Samokhvalov, Alexander A. Chistyakov, and Igor Nabiev "Controllable photo-brightening/photo-darkening of semiconductor quantum dots under laser irradiation", Proc. SPIE 9884, Nanophotonics VI, 98843L (21 April 2016); https://doi.org/10.1117/12.2228815

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