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Suppressing the Fluorescence Blinking of Single Quantum Dots Encased in N-type Semiconductor Nanoparticles

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ABSTRACT

N-type semiconductor indium tin oxide (ITO) nanoparticles are used to effectively suppress the fluorescence blinking of single near-infrared-emitting CdSeTe/ZnS core/shell quantum dots (QDs), where the ITO could block the electron transfer from excited QDs to trap states and facilitate more rapid regeneration of neutral QDs by back electron transfer. The average blinking rate of QDs is significantly reduced by more than an order of magnitude and the largest proportion of on-state is 98%, while the lifetime is not considerably reduced. Furthermore, an external electron transfer model is proposed to analyze the possible effect of radiative, nonradiative, and electron transfer pathways on fluorescence blinking. Theoretical analysis based on the model combined with measured results gives a quantitative insight into the blinking mechanism.

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Normalized probability density of on-states (Pon(t)) and off-states (Poff(t)) for single QDs on glass coverslips and encased in ITO, respectively.The solid lines are best fits by a truncated power law. Fitting parameters for QDs on glass coverslips: αon = 0.447, αoff = 0.435, 1/μon = 0.163, and 1/μoff = 1.175; fitting parameters for QDs encased in ITO: αon = 0.529, αoff = 0.965, 1/μon = 1.639, and 1/μoff = 0.264.
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f2: Normalized probability density of on-states (Pon(t)) and off-states (Poff(t)) for single QDs on glass coverslips and encased in ITO, respectively.The solid lines are best fits by a truncated power law. Fitting parameters for QDs on glass coverslips: αon = 0.447, αoff = 0.435, 1/μon = 0.163, and 1/μoff = 1.175; fitting parameters for QDs encased in ITO: αon = 0.529, αoff = 0.965, 1/μon = 1.639, and 1/μoff = 0.264.

Mentions: The on and off states probability densities Pon(t) and Poff(t) of single QDs are used to compare the blinking activity of QDs on glass coverslips and encased in ITO, which have been calculated according to the method of Kuno et al., 11. Where Ni(t) is the statistics of on- or off-state events in duration time of t, Ni,total is the total number of on- or off- state events and is the average of the time intervals to the preceding and following events. Pon(t) and Poff(t) of single QDs in the two cases show a power law distribution at short time but deviate from this distribution at long time tails, as shown in Fig. 2. These Pon(t) and Poff(t) distributions can be fitted by a truncated power law103940: , where A is the amplitude, α is the power law exponent, and μ is the saturation rate. In Fig. 2, the probability density of on-state at the duration time of 1s for single QDs in ITO is two orders of magnitude higher than that on glass coverslips. The fitting parameters for α and μ have been obtained by the fitting of ~110 single QDs on glass coverslips and encased in ITO respectively, as showed in Table 1. Single QDs encased in ITO have a larger 1/μon and a smaller 1/μoff than that of QDs on glass coverslips, which suggests increased probability densities of on-state events and decreased probability densities of off-state events.


Suppressing the Fluorescence Blinking of Single Quantum Dots Encased in N-type Semiconductor Nanoparticles
Normalized probability density of on-states (Pon(t)) and off-states (Poff(t)) for single QDs on glass coverslips and encased in ITO, respectively.The solid lines are best fits by a truncated power law. Fitting parameters for QDs on glass coverslips: αon = 0.447, αoff = 0.435, 1/μon = 0.163, and 1/μoff = 1.175; fitting parameters for QDs encased in ITO: αon = 0.529, αoff = 0.965, 1/μon = 1.639, and 1/μoff = 0.264.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015025&req=5

f2: Normalized probability density of on-states (Pon(t)) and off-states (Poff(t)) for single QDs on glass coverslips and encased in ITO, respectively.The solid lines are best fits by a truncated power law. Fitting parameters for QDs on glass coverslips: αon = 0.447, αoff = 0.435, 1/μon = 0.163, and 1/μoff = 1.175; fitting parameters for QDs encased in ITO: αon = 0.529, αoff = 0.965, 1/μon = 1.639, and 1/μoff = 0.264.
Mentions: The on and off states probability densities Pon(t) and Poff(t) of single QDs are used to compare the blinking activity of QDs on glass coverslips and encased in ITO, which have been calculated according to the method of Kuno et al., 11. Where Ni(t) is the statistics of on- or off-state events in duration time of t, Ni,total is the total number of on- or off- state events and is the average of the time intervals to the preceding and following events. Pon(t) and Poff(t) of single QDs in the two cases show a power law distribution at short time but deviate from this distribution at long time tails, as shown in Fig. 2. These Pon(t) and Poff(t) distributions can be fitted by a truncated power law103940: , where A is the amplitude, α is the power law exponent, and μ is the saturation rate. In Fig. 2, the probability density of on-state at the duration time of 1s for single QDs in ITO is two orders of magnitude higher than that on glass coverslips. The fitting parameters for α and μ have been obtained by the fitting of ~110 single QDs on glass coverslips and encased in ITO respectively, as showed in Table 1. Single QDs encased in ITO have a larger 1/μon and a smaller 1/μoff than that of QDs on glass coverslips, which suggests increased probability densities of on-state events and decreased probability densities of off-state events.

View Article: PubMed Central - PubMed

ABSTRACT

N-type semiconductor indium tin oxide (ITO) nanoparticles are used to effectively suppress the fluorescence blinking of single near-infrared-emitting CdSeTe/ZnS core/shell quantum dots (QDs), where the ITO could block the electron transfer from excited QDs to trap states and facilitate more rapid regeneration of neutral QDs by back electron transfer. The average blinking rate of QDs is significantly reduced by more than an order of magnitude and the largest proportion of on-state is 98%, while the lifetime is not considerably reduced. Furthermore, an external electron transfer model is proposed to analyze the possible effect of radiative, nonradiative, and electron transfer pathways on fluorescence blinking. Theoretical analysis based on the model combined with measured results gives a quantitative insight into the blinking mechanism.

No MeSH data available.


Related in: MedlinePlus