Hydrophilic semiconductor quantum dots

Бричкин, С. Б.; Chernykh, E. V.

doi:10.1134/s0018143911010061

Cited by 22 publications

(25 citation statements)

References 77 publications

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“…11,[24][25][26][27][28] Ligand exchange changes the chemical and physical states of atoms on the QD surface, and causes QYs to decrease. 29 The QY of InP/ZnS-MPA@TMAS was similar to that of the InP/ZnS-MPA QD dispersion, while the QY of InP/ZnS-DDT@PMMA was much lower than that of the dispersion of InP/ZnS-DDT QDs. The reason for the low QY of InP/ZnS-DDT@PMMA is QD aggregation.…”

Section: Resultsmentioning

confidence: 86%

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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Section: Resultsmentioning

confidence: 86%

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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“…Summing up, it should be noted that ideal biocompatible QDs should have a high size homogeneity and colloidal stability in aqueous solutions, exhibit pH stability, and have a high fluorescence quantum yield [22]. These conditions are difficult to enforce simultaneously, but extreme relevance of QDs with such properties is stimulating for further investigations.…”

Section: Physical Methods Of Synthesis Of Qdsmentioning

confidence: 99%

“…For example, utilizing a glutathione, the component that eliminates heavy metals in plant cells, ensured successful coating and high levels of the photoluminescence during the synthesis of CdTe nanoparticles [21]. It is important that in order to obtain QDs with the high fluorescence efficiency, it is necessary to maintain a high pH level (11.2-11.8) during the synthesis in an aqueous phase [22].…”

Section: Chemical Methods Of Synthesis Of Qdsmentioning

confidence: 99%

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Biosynthesis of Quantum Dots and Their Potential Applications in Biology and Biomedicine

Borovaya

Burlaka

Yemets

et al. 2015

Springer Proceedings in Physics

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“…In the early 1980s, syntheses of QDs in aqueous solutions resulted in broad size distributions of the particles, often characterized by poor luminescence efficiencies. [59][60][61] In 1993, Murray and co-workers for the first time…”

Section: -54mentioning

confidence: 99%

Quantum dots as liquid crystal dopants

2012

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Liquid crystal nanoscience, a field exploring the mutually beneficial combination of the unique properties of nanoscale materials and fluid, yet ordered liquid crystalline phases, is increasingly focusing on semiconductor quantum dots. In one major research thrust, the anisotropic properties of the liquid crystal host are sought to facilitate the assembly of quantum dots into arrays, in another, both size-and shape-dependent optical and electronic properties of quantum dots are used to manipulate optical, electro-optical and alignment properties of liquid crystalline materials. This feature article reviews recent accomplishments and new insights in this fascinating area of soft matter nanocomposites including work from our laboratory on a series of CdSe and CdTe quantum dots as additives in nematic liquid crystal hosts.

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Hydrophilic semiconductor quantum dots

Cited by 22 publications

References 77 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

Biosynthesis of Quantum Dots and Their Potential Applications in Biology and Biomedicine

Quantum dots as liquid crystal dopants

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