Synthesis and Characterizations of Bare CdS Nanocrystals Using Chemical Precipitation Method for Photoluminescence Application

Lee, Hooi Ling; Issam, A. M.; Belmahi, M.; Assouar, Badreddine; Rinnert, H.; Alnot, M.

doi:10.1155/2009/914501

Cited by 38 publications

(27 citation statements)

References 54 publications

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“…We confirmed the presence of the CdS layer by XPS (X-Ray Photoelectron Spectroscopy) measurements. We observe the S2p line at 162.0 eV, which is attributed to the CdS bond [30][31][32]. Based on the intensities of the S2p, Cd3d and Te3d lines, and considering their sensitivity factors, we estimate the thickness of this CdS layer as two or three atomic layers.…”

Section: Synthesis and Methodsmentioning

confidence: 94%

Characterization of the Dynamics of Photoluminescence Degradation in Aqueous CdTe/CdS Core-Shell Quantum Dots

Assis

et al. 2015

J Fluoresc

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We investigate the effects of the excitation power on the photoluminescence spectra of aqueous CdTe/CdS core-shell quantum dots. We have focused our efforts on nanoparticles that are drop-cast on a silicon nitride substrate and dried out. Under such conditions, the emission intensity of these nanocrystals decreases exponentially and the emission center wavelength shifts with the time under laser excitation, displaying a behavior that depends on the excitation power. In the low-power regime a blueshift occurs, which we attribute to photo-oxidation of the quantum dot core. The blueshift can be suppressed by performing the measurements in a nitrogen atmosphere. Under high-power excitation the nanoparticles thermally expand and aggregate, and a transition to a redshift regime is then observed in the photoluminescence spectra. No spectral changes are observed for nanocrystals dispersed in the solvent. Our results show a procedure that can be used to determine the optimal conditions for the use of a given set of colloidal quantum dots as light emitters for photonic crystal optical cavities.

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Section: Synthesis and Methodsmentioning

confidence: 94%

Characterization of the Dynamics of Photoluminescence Degradation in Aqueous CdTe/CdS Core-Shell Quantum Dots

Assis

et al. 2015

J Fluoresc

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“…In Figure 1 (top), the experimental and the theoretical (vertical lines) X-ray Diffractogram are shown. By analyzing XRD it can be observed that the CdS/Cd(OH) 2 QDs present cubic crystalline structure, which corresponds to the more stable crystalline form for CdS [23]. Contrast phase image obtained for the same times, 3 minutes and 7 days, are presented in Figure 5 left and right, respectively.…”

Section: -Resultsmentioning

confidence: 94%

Colloidal quantum dots suitability for long term cell imaging

Farias

Galembeck

Milani

et al. 2018

Preprint

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Fluorescent semiconductor nanoparticles in tree-dimensional quantum confinement, quantum dots (QDs), synthesized in aqueous medium, and functionalized with polyethylene glycol, were used as probes for the long-term imaging of glial cells. In vitro living healthy as well as cancer glial cells were labelled by direct insertion of a small volume of QDs contained in aqueous suspension into the culture wells. A long-term monitoring (over 7 days) of the cells was performed and no evidence of cell fixation and/or damage was observed. Two control groups, healthy and cancer glial cells, were used to compare cell viability. During the observation period, labelled and non labelled cells presented the same dynamics and no difference was observed regarding cell viability. To our knowledge, this is the first report of the viability of hydrophilic prepared quantum dots without any further surface treatment than the polyethylene-glycol coverage for the long-term imaging of living cells. Further, the study also permitted the observation of two distinct interaction mechanisms between cells and QDs. Healthy glial cells were mainly labelled at their surface, while non-healthy glial cells have shown a high rate in the uptake of QDs.

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“…Along with similarly synthesized colloidal cadmium selenide quantum dots (Q-CdSe) of 1.7 eV bandgap, both Q-CdS and Q-CdSe, with their corresponding absorption onsets of $520 and 720 nm, respectively, offer the opportunity for a range of investigations and optical technology development throughout the visible spectrum. Moreover, since Q-CdS exhibit the characteristics of multiple colors and brightness, comparable to that of fluorescent dyes and semiconductor light emitting diodes, several research groups have worked to explore their properties [11][12][13][14][15]. However, more research will be needed to convert Q-CdS from a ''promising electronic material'' to the realm of device applications.…”

Section: Discussionmentioning

confidence: 99%

A simple FBG sensor for strain–temperature discrimination

Parne

Prasad

Gupta

et al. 2011

Micro & Optical Tech Letters

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intensities. We obtained the highest FL for Q-CdS adsorbed onto GaAs for each of the three relative sizes of quantum dots. We suspect that this latter observation may be due to radiative recombination between electrons confined to the quantum dots with holes captured at the shallow acceptor level of the GaAsquantum dot interface. With an eye toward future HEM device applications, this higher FL emission would suggest further study of functionalized Q-CdS adsorbed onto GaAs. CONCLUSIONSWe have examined the FL spectra of AOT (dioctyl sulfoccinate) capped cadmium sulfide quantum dots (Q-CdS) deposited upon gold (Au), insulator (mica), and semiconductor (GaAs) substrates for their potential use in hybrid optoelectronic devices. Relative dot sizes were synthesized to increase from 1 to 5 nm with a respective increase in heptane concentration from 40 to 80 lL. Excitation and emission spectra are presented for the 200-400 nm and 400-700 nm ranges, respectively. For the smallest (40 lL heptane) quantum dots, a clear red shift in FL emission peak wavelength is observed from the Au, to mica, to GaAs substrate-based samples. For the midrange (70 lL) and largest (80 lL) Q-CdS samples, the longest emission peak wavelengths are observed for the quantum dots physisorbed to Au substrates with a subsequent decrease and then increase in emission wavelengths for the mica and GaAs substrate-based samples, respectively. Of the three types of substrates used, Q-CdS deposited upon GaAs exhibited the highest FL emission intensity, which bodes well for the possible integration of HEMs into next-generation device technology.ABSTRACT: A simple sensor using half the length of a 3-cm fiber Bragg grating embedded on a cantilever is proposed for the simultaneous measurement and discrimination of strain and temperature. The response of the sensor is linear from 30 to 200 C, and its strain and temperature sensitivities are found to be 3.38 pm/lm 19.05 pm/ C, respectively.ABSTRACT: A new silicon-based differential stacked spiral inductor (DSSI) was implemented using a standard 0.18-lm complimentary metal-oxide semiconductor technology. Based on the measured two-port S-parameter using a standard de-embedding procedure, the selfresonance frequency, f sr , and quality factor, Q, of the new DSSI were compared with a conventional DSSI. The f sr of the new DSSI was nearly twice as high as that of the conventional DSSI, and the Q value of the new DSSI was also enhanced.

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Synthesis and Characterizations of Bare CdS Nanocrystals Using Chemical Precipitation Method for Photoluminescence Application

Cited by 38 publications

References 54 publications

Characterization of the Dynamics of Photoluminescence Degradation in Aqueous CdTe/CdS Core-Shell Quantum Dots

Characterization of the Dynamics of Photoluminescence Degradation in Aqueous CdTe/CdS Core-Shell Quantum Dots

Colloidal quantum dots suitability for long term cell imaging

A simple FBG sensor for strain–temperature discrimination

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