Preparation and optical properties of silica gel–glass doped with ZnSe nanoparticles

Wang, Minqiang; Xue, Yaohui; Lin, Zhonghai; Huo, Xiao; Li, Jianping; Yao, Xi

doi:10.1016/j.matlet.2007.06.018

Cited by 11 publications

(9 citation statements)

References 8 publications

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“…[13][14][15][16][17][18] HCl is generally used as a catalyst to promote gelation in the sol-gel technique. However, gelation under basic conditions is preferable for QDs because they are degraded by strong acid.…”

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confidence: 99%

Preparation of Photostable Fluorescent InP/ZnS Quantum Dots Embedded in TMAS-Derived Silica

Watanabe

Wada

Iso

et al. 2017

ECS J. Solid State Sci. Technol.

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Cd-free fluorescent InP/ZnS quantum dots (QDs) have attracted attention for use as color converters of liquid crystal displays. To protect InP/ZnS QDs from oxygen, which degrades them by photo-oxidation during excitation, we fabricated a transparent monolithic silica composite containing the QDs using an aqueous solution of tetramethylammonium silicate (TMAS) as a silica source. The TMAS solution was basic and readily dispersed the negatively charged QDs obtained by ligand exchange of 1-dodecanethiol for 3-mercaptopropionic acid (MPA). A highly transparent monolithic TMAS-derived silica composite containing the MPA-modified QDs (InP/ZnS-MPA@TMAS) was obtained from the aqueous QD dispersion through a sol-gel process. The photoluminescence (PL) quantum yield of InP/ZnS-MPA@TMAS was 21.7%. Changes in PL intensity under continuous 400-nm excitation were measured to evaluate the photostability of the QDs in InP/ZnS-MPA@TMAS. The PL intensity of InP/ZnS-MPA@TMAS was over 90% of the initial value after 180 min, while that of a reference polymethylmethacrylate film containing hydrophobic QDs decreased to 69%. The higher photostability of InP/ZnS-MPA@TMAS than that of the reference film was explained by the TMAS-derived silica acting as a gas barrier to protect the embedded QDs from photo-oxidation by oxygen in air. A quantum dot (QD) is a semiconductor nanocrystal. As the size of a QD decreases, its bandgap widens because of the quantum size effect. The fluorescent wavelength of a QD therefore depends on its size.1 The tunable fluorescent wavelength of QDs means they are applicable to white light-emitting diodes (LEDs) 2 and bioimaging. 3 CdS and CdSe QDs have been frequently studied because their fluorescent wavelength is tunable in the visible range. 4 InP QDs have recently attracted attention because they are Cd-free with low toxicity. InP QDs have been synthesized via hot injection 5 and thermal 6 methods. Yang et al. 6 coated an InP core prepared by the latter method with a ZnS shell to passivate dangling bonds on the QD surface. The obtained InP/ZnS core/shell QDs displayed a high quantum yield (QY) of up to 60%, tunable fluorescent wavelength, and narrow emission peak. The color reproduction range of liquid crystal displays could be improved by using such InP/ZnS QDs as a color converter in the LED backlight.For practical optoelectronic applications, QDs have to retain their photoluminescence (PL) intensity during continuous excitation. However, the PL intensity of QDs decreases over time because of the photooxidation of the QD surface by oxygen.7 One method used to improve the photostability of QDs is formation of a core/shell structure. However, the PL intensity of InP/ZnS core/shell QDs deteriorated to 40% of the initial PL intensity after continuous excitation by 365-nm light for 10 h. 6 Thus, it is difficult to completely avoid PL deterioration even for QDs with a core/shell structure. 6 Incorporation of well-dispersed QDs into a matrix to protect them from oxygen is another way to avoid PL deterioration of ...

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mentioning

confidence: 99%

Preparation of Photostable Fluorescent InP/ZnS Quantum Dots Embedded in TMAS-Derived Silica

Watanabe

Wada

Iso

et al. 2017

ECS J. Solid State Sci. Technol.

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“…Most composites of nanocrystals and silica are prepared by sol-gel methods involving alkoxysilanes. [10][11][12][13][14][15] One problem with these approaches is that HCl is generally used as a catalyst to promote gelation in the sol-gel technique; however, QDs are damaged by strong acid. Moreover, it is technically difficult to maintain the dispersion of QDs and avoid aggregation in the sol, which is a mixture of a hydrophilic liquid, lipophilic liquid, and an amphiphilic liquid with the desired composition.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence color stability of green-emitting InP/ZnS core/shell quantum dots embedded in silica prepared via hydrophobic routes

et al. 2018

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“…The sol–gel chemistry has been shown to provide a means of entrapping a great variety of (bio)chemical species, from small organic molecules, − to enzymes, , living cells and other microorganisms, , and also nanoparticles , in a solid matrix while preserving their functionality. Thus, a large variety of doped hybrid organic–inorganic materials have been applied for different purposes, including the fabrication of sensor and biosensor devices ,− and the development of commercially available products, such as smart drug delivery carriers for bone tissue regeneration…”

Section: Introductionmentioning

confidence: 99%

One-Step Patterning of Hybrid Xerogel Materials for the Fabrication of Disposable Solid-State Light Emitters

Carregal-Romero

Llobera

Cadarso

et al. 2012

ACS Appl. Mater. Interfaces

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The one-step room-temperature micropatterning of a fluorophore-doped xerogel material on silicon oxide substrates is reported. The organo-alkoxysilane precursors and organic fluorescent dyes, as well as the polymerization experimental conditions, were tailored in order to obtain a highly homogeneous transparent material suitable for photonic applications. A thorough structural characterization was carried out by Fourier transform infrared (FT-IR) spectroscopy, (29)Si nuclear magnetic resonance ((29)Si NMR), thermogravimetric analysis (TGA), N(2) adsorption Brunauer-Emmett-Teller (BET) porosimetry, and confocal microscopy. These studies revealed a stable nonporous highly cross-linked polymer network containing evenly dispersed fluorescent molecules. Xerogel microstructures having thicknesses between 4 and 80 μm and height-to-width ratios between 0.04 and 4, as well as showing different geometries, from well arrays to waveguides, were patterned in a single step by micromolding in capillaries (MIMIC) soft lithographic technique. The reliability of the replication process was tested by bright-field optical microscopy and scanning electron microscopy (SEM) that show the close fidelity of the microstructures to the applied mold. The optical performance of the developed material was demonstrated by fabricating waveguides and evaluating their corresponding spectral response, obtaining absorption bands, at the expected excitation wavelengths of the corresponding fluorescent dyes and gain due to photonic re-emission (fluorescence) at their corresponding dye emission wavelengths. The hybrid xerogel material and the application of the simple fabrication technology presented herein can be directly applied to the development of cost-effective photonic components, as could be light emitters, to be readily integrated in single-use lab-on-chip devices and other polymeric microsystems.

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Preparation and optical properties of silica gel–glass doped with ZnSe nanoparticles

Cited by 11 publications

References 8 publications

Preparation of Photostable Fluorescent InP/ZnS Quantum Dots Embedded in TMAS-Derived Silica

Preparation of Photostable Fluorescent InP/ZnS Quantum Dots Embedded in TMAS-Derived Silica

Photoluminescence color stability of green-emitting InP/ZnS core/shell quantum dots embedded in silica prepared via hydrophobic routes

One-Step Patterning of Hybrid Xerogel Materials for the Fabrication of Disposable Solid-State Light Emitters

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