Intense photoluminescence of slightly doped ZnO–SiO2 matrix

Bouguerra, M. L.; Samah, M.; Belkhir, M.A.; Chergui, A.; Gerbous, L.; Nouet, G.; Chateigner, D.; Madelon, R.

doi:10.1016/j.cplett.2006.03.103

Cited by 34 publications

(33 citation statements)

References 25 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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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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“…n (1) n r < 0. For all dot radii the contribution of the third order nonlinear refractive index change n (3) n r is opposite in sign to that of the linear refractive index change n (1) n r i.e. negative and positive for below and above the resonance frequency respectively.…”

Section: Resultsmentioning

confidence: 92%

“…The change in refractive index is given by [25][26][27]29 n(ω) n r = n (1) (ω) n r + n (3) (ω) n r (9) with the linear n (1) n r and the third-order non linear n (3) n r refractive index changes given by n (1) …”

Section: -3mentioning

confidence: 99%

“…Several studies mostly experimental are reported on the optical properties of semiconductor QD's involving interband transitions in the visible and ultraviolet regions. [3][4][5][6][7][8][9] Only few studies 10,11 are reported involving intersubband transitions in the infrared regions. Studies on the intraband transitions are important because of their potential optoelectronic device applications [12][13][14][15] as in IR photodetectors.…”

Section: Introductionmentioning

confidence: 99%

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Linear and nonlinear intraband optical properties of ZnO quantum dots embedded in SiO2 matrix

2012

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In this work we investigate some optical properties of semiconductor ZnO spherical quantum dot embedded in an amorphous SiO2 dielectric matrix. Using the framework of effective mass approximation, we have studied intraband S-P, and P-D transitions in a singly charged spherical ZnO quantum dot. The optical properties are investigated in terms of the linear and nonlinear photoabsorption coefficient, the change in refractive index, and the third order nonlinear susceptibility and oscillator strengths. Using the parabolic confinement potential of electron in the dot these parameters are studied with the variation of the dot size, and the energy and intensity of incident radiation. The photoionization cross sections are also obtained for the different dot radii from the initial ground state of the dot. It is found that dot size, confinement potential, and incident radiation intensity affects intraband optical properties of the dot significantly

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“…With the development of materials technology, several physical and chemical synthesis techniques, such as: solid-state reaction, co-precipitation, sol-gel and combustion methods have been utilized to synthesize α-Zn 2 SiO 4 [6,8,1]. Using sol-gel method, L. Shastri et al have obtained ZnO -SiO 2 with the emission band at about 720 nm which could be assigned to the lattice disorder along the c-axis or transitions related to Zn i [9].…”

Section: Introductionmentioning

confidence: 99%

NEAR INFRARED – EMITTING Zn2SiO4 POWDERS PRODUCED BY HIGH-ENERGY PLANETARY BALL MILLING TECHNIQUE

Vien¹

2018

JST

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The near infrared-emitting Zn 2 SiO 4 powders were produced by high-energy planetary ball milling of ZnO and SiO 2 powders followed by annealing in air environment and at different temperatures. The surface morphology, crystal structure, chemical composition and optical properties of the obtained samples were investigated by means of field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Raman spectroscopy and photoluminescence measurements (PL) at room temperature. The analysis indicates the formation of Zn 2 SiO 4 phase with annealing temperature of 1250 C. The size of Zn 2 SiO 4 nanoparticles depends strongly on annealing temperature. Photoluminescence investigation reveals that the optimal annealing temperature for almost only near-infrared emission ( 740 nm) is 1250 o C. The origin of this peak can be attributed to the energy transfer from non-bridging oxygen hole centers (NBOHs) to zinc interstitial (Zn i ) and oxygen vacancy (V o ) states in the Zn 2 SiO 4 host lattice. These results demonstrate that we might be able to produce the Zn 2 SiO 4 powders for applications in high CRI white light emitting diodes by a simple and low-cost method.

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Intense photoluminescence of slightly doped ZnO–SiO2 matrix

Cited by 34 publications

References 25 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

Linear and nonlinear intraband optical properties of ZnO quantum dots embedded in SiO2 matrix

NEAR INFRARED – EMITTING Zn2SiO4 POWDERS PRODUCED BY HIGH-ENERGY PLANETARY BALL MILLING TECHNIQUE

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