Optical transitions in polarized CdSe, CdSe∕ZnSe, and CdSe∕CdS∕ZnS quantum dots dispersed in various polar solvents

Thuy, Ung Thi Dieu; Liem, Nguyen Quang; Thanh, Do Xuan; Protière, Myriam; Reiß, Peter

doi:10.1063/1.2822399

Cited by 38 publications

(30 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Commonly, such a blueshift is assigned to a decrease of particle size, which is in the present case very likely caused by oxidation of the particle surface 3, 22. However, spectral shifts can also occur if the polarity of the QD changes in a given electric field by the Stark effect 48. In principle, this is also possible if under photoactivation the number and charge of solvent and oxygen molecules changes in the vicinity of the QD.…”

Section: Resultsmentioning

confidence: 76%

Photoactivation of CdSe/ZnS Quantum Dots Embedded in Silica Colloids

Dembski

Gräf

Krüger

et al. 2008

Small

View full text Add to dashboard Cite

A study of the influence of the local environment on the light-induced luminescence enhancement of CdSe/ZnS quantum dots (QD) embedded in silica colloids that are dispersed in various solvents is presented. The photoluminescence of the embedded QD is enhanced up to a factor of ten upon photoactivation by ultraviolet or visible light. This enhancement is strongly dependent on the local environment. The thickness-dependent permeability of the silica shell covering the QD controls the influence of the solvent on the QD. If foreign ions are present the activation state is stabilized after termination of the activation, whereas in their absence the process is partially reversible. A new qualitative model for the photoactivation of QD in various environments is developed. It comprises light-induced passivation and subsequent oxidation processes. The embedded QD also retain their fluorescence quantum yield inside living cells. Moreover, they can be activated for many hours in living cells by laser radiation in the visible regime.

show abstract

Section: Resultsmentioning

confidence: 76%

Photoactivation of CdSe/ZnS Quantum Dots Embedded in Silica Colloids

Dembski

Gräf

Krüger

et al. 2008

Small

View full text Add to dashboard Cite

show abstract

“…It is known that spectral diffusion occurs in the temporal evolution of the fluorescence emission of individual NPs. 41 Spectral diffusion broadens the fluorescence spectra when it happens on time scales smaller than the integration time, i.e., the single-particle line shapes result from rapid spectral shifting of the emission peak. 24 When spectral diffusion occurs on time scales larger than the integration time, it is visible as jumps of the whole spectrum.…”

Section: The Very Same Nps Under Subsequent Exchange Of Ethylene Glycolsmentioning

confidence: 99%

Fluorescence spectroscopy of individual semiconductor nanoparticles in different ethylene glycols

Flessau

Wolter

Pöselt

et al. 2014

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The optical properties of single colloidal semiconductor nanoparticles (NPs) are considerably influenced by the direct environment of the NPs. Here, the influence of different liquid and solid glycol matrices on CdSe-based NPs is investigated. Since the fluorescence of individual NPs varies from one NP to another, it is highly desirable to study the very same individual NPs in different matrices. This was accomplished by immobilizing NPs in a liquid cell sample holder or in microfluidic devices. The samples have been investigated by space-resolved wide-field fluorescence microscopy and energy- and time-resolved confocal scanning fluorescence microscopy with respect to fluorescence intensities, emission energies, blinking behavior, and fluorescence decay dynamics of individual NPs. During the measurements the NPs were exposed to air, to liquid ethylene glycols H(OCH2CH2)nOH (also called EGn) with different chain lengths (1 ≤ n ≤ 7), to liquid 2-methylpentane-2,3-diol, or to solid polyethylene oxide. It was found that EG6-7 (also known as PEG 300) is very well suited as a liquid matrix or solvent for experiments that correlate chemical and physical modifications of the surface and of the immediate environment of individual NPs to their fluorescence properties since it leads to intense and stable fluorescence emission of the NPs.

show abstract

“…The absorption peak positions of these QDs were very similar while the emission peaks showed modest differences, as is commonly observed after surface modification. [17][18][19] Dynamic light scattering data indicated that QDs had comparable sizes, ranging from 7.5 to 11.7 nm, with PEG-QD having a slightly larger hydrodynamic size of 24 nm, presumably due to modest level of aggregation (see ESI † for QD physicochemical properties).…”

mentioning

confidence: 99%