Reversible and non-reversible photo-enhanced luminescence in CdSe/ZnS quantum dots

Korsunska, N.; Dybiec, M.; Zhukov, Leonid; Ostapenko, S.; Zhukov, Tatyana

doi:10.1088/0268-1242/20/8/044

Cited by 57 publications

(50 citation statements)

References 15 publications

(23 reference statements)

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“…However, the authors notice that, if extensive QD degradation takes place in lysosomes, a blue-shift in QD fluorescence should be observed, which was not the case. 40 Such photo-activation (photo-enhancement) of fluorescence has been observed in solutions of free QDs after exposure to sunlight, 41 UV radiation, 42 and blue light 43 or QDs embedded in silica colloids under UV radiation. 44 Normally, a decrease in QD fluorescence intensity occurs due to oxidative decay of the CdSe lattice in the presence of oxygen, while in nitrogen, photobleaching is absent.…”

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confidence: 99%

Entrapment in phospholipid vesicles quenches photoactivity of quantum dots

Generalov

Kavaliauskiene²,

Westrøm³

et al. 2011

IJN

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Quantum dots have emerged with great promise for biological applications as fluorescent markers for immunostaining, labels for intracellular trafficking, and photosensitizers for photodynamic therapy. However, upon entry into a cell, quantum dots are trapped and their fluorescence is quenched in endocytic vesicles such as endosomes and lysosomes. In this study, the photophysical properties of quantum dots were investigated in liposomes as an in vitro vesicle model. Entrapment of quantum dots in liposomes decreases their fluorescence lifetime and intensity. Generation of free radicals by liposomal quantum dots is inhibited compared to that of free quantum dots. Nevertheless, quantum dot fluorescence lifetime and intensity increases due to photolysis of liposomes during irradiation. In addition, protein adsorption on the quantum dot surface and the acidic environment of vesicles also lead to quenching of quantum dot fluorescence, which reappears during irradiation. In conclusion, the in vitro model of phospholipid vesicles has demonstrated that those quantum dots that are fated to be entrapped in endocytic vesicles lose their fluorescence and ability to act as photosensitizers.

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mentioning

confidence: 99%

Entrapment in phospholipid vesicles quenches photoactivity of quantum dots

Generalov

Kavaliauskiene²,

Westrøm³

et al. 2011

IJN

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“…Moreover, the more carriers are bound together as excitons, the less they contribute to photoconductivity. If these rates are comparable, the PL intensity (180-200 K) will show a slow increase [20]. At higher temperatures (above 200 K), the reduction of the observed PL intensity is considered to be due to the increase of the nonradiative-decay rate, which changes slightly.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the integrated PL intensity as a function of temperature should be related to the recombination and the capture rate during radiative and non-radiative processes. The temperature dependence of the integrated PL intensity can be explained in terms of a three-level model shown in Figure 5: a ground state, a lower-lying bound exciton state and a higher-lying free exciton state which is called dark-exciton state [20][21][22]. Assume a Boltzmann distribution of exciton between two exciton levels of E 1 and E 2 .…”

Section: Resultsmentioning

confidence: 99%

Anomalous temperature dependent photoluminescence properties of CdS x Se1−x quantum dots

Chen

Zhang

et al. 2010

Sci. China Phys. Mech. Astron.

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CdS x Se 1−x quantum dots were fabricated by a simple spin-coating heat volatilization method on InP wafer. Temperature dependent photoluminescence of CdS x Se 1−x quantum dots was carried out in a range of 10-300 K. The integrated photoluminescence intensity revealed an anomalous behavior with increasing temperature in the range of 180-200 K. The band gap energy showed a redshift of 61.34 meV when the temperature increased from 10 to 300 K. The component ratio of S to Se in the CdS x Se 1−x quantum dots was valued by both the X-ray diffraction data and photoluminescence peak energy at room temperature according to Vegard Law. Moreover, the parameters of the Varshni relation for CdS 0.9 Se 0.1 materials were also obtained using photoluminescence peak energy as a function of temperature and the best-fit curve: α = (3.5 ± 0.1)10 −4 eV/K, and β = 210 ± 10 K (close to the Debye temperature θ D of the material). CdS x Se 1−x , quantum dots, temperature dependent photoluminescence

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“…В одних случаях на-блюдают эффект разгорания фотолюминесценции КТ. В других имеет место ее обратимая или необратимая деградация [9][10][11][12][13]. В работах [11,12] показан процесс фотоактивации люминесценции КТ CdSe при длитель-ном освещении естественным (окружающим) светом и лазерным излучением.…”

Section: Introductionunclassified