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Enhancing upconversion luminescence in rare-earth doped particles

A rare earth doping and particle technology, applied in luminescent materials, optics, light demodulation, etc., can solve problems such as difficult to achieve up-conversion luminescence

Inactive Publication Date: 2015-07-15
MACQUARIE UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Although new advances in the synthetic process have enabled precise control of upconverting nanocrystal morphology, crystalline phase, and emission color, strong upconversion luminescence remains difficult to achieve

Method used

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  • Enhancing upconversion luminescence in rare-earth doped particles
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  • Enhancing upconversion luminescence in rare-earth doped particles

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0118] Embodiment 1-Yb / Tm doped NaYF 4 Synthesis and Characterization of Nanocrystals

[0119] synthesized with Tm in the range 0.2-8 mol% 3+ concentration and is co-doped with 20mol% Yb 3+ The hexagonal NaYF 4 nanocrystals (see figure 1 b). The following reagents were used: YCl purchased from Sigma-Aldrich 3 ·6H 2 O (99.99%), YbCl 3 ·6H 2 O (99.998%), TmCl 3 ·6H 2 O (99.99%), ErCl 3 ·6H 2 O (99.9%), NaOH (98%), NH 4 F (99.99%), oleic acid (OA, 90%), 1-octadecene (ODE, 90%). All chemicals were used as received without further purification unless otherwise noted.

[0120] Using the previously described organometallic approach, upconverting NaYF was synthesized 4 : Yb, Tm nanocrystals (see A Strategy to Achieve Efficient Dual-Mode Luminescence of Eu by Liu, Y.S. et al. 3+ in Lanthanides Doped Multifunctional NaGdF 4 Nanocrystals. Adv Mater 22, 3266 (2010); and Wang, F. et al. Simultaneous phase and size control of upconversion nanocrystals through lanthanide dop...

Embodiment 2

[0122] Embodiment 2-Yb / Tm doped NaYF 4 Excitation of Nanocrystals

[0123] Launch the single-mode 980nm diode laser beam into the suspended core fiber (see figure 1 a), the fiber guides and concentrates the excitation within the core of the fiber, so that a 1.6×10 4 to 2.5×10 6 W / cm 2 Variable high-irradiance excitation over a wide range to excite suspended nanocrystals near the fiber core. According to observation, when the irradiance is 2.5×10 6 W / cm 2 8mol%Tm 3+ Nanocrystals far exceed the performance of other doping concentrations, with 0.5% Tm 3+ The infrared and blue emission bands are significantly stronger compared to nanocrystals (more than 70 times stronger 802nm emission; at figure 1 shown in c). with a low irradiance of 1.6 x 10 4W / cm 2 The inversion of the concentration-quenching enable power produced a larger cumulative up-conversion signal compared to the cumulative up-conversion signal of 0.5%, 4%, and 8% of Tm 3+ , which are 5.6, 71 and 1105 times ...

Embodiment 3

[0124] Example 3 - with varying Tm 3+ Concentration-dependent luminescence spectra of upconverting nanocrystals

[0125] In order to quantify the above analysis in Example 2, from Tm 3+ The power correlation (1.6 × 10 4 up to 2.5×10 6 W / cm 2 ) matrix of luminescence spectra. refer to in figure 2 Simplified excited state levels in a, the emission spectrum can be divided into three populations: the "two-photon excited level" (emitted at 802nm 3 h 4 energy level), "three-photon excitation level" (emitted at 650nm and 480nm 1 G 4 energy level), and "four-photon excitation level" (emitted at 455nm, 514nm, 744nm and 782nm 1 D. 2 energy level). through the figure 2 The representative example shown in b, at each wavelength the region covered by the spectrum extracted from the Gaussian curve fit provides quantitative data indicating the importance of sensitizing 980 nm photons to promote upconversion of the emission wavelength alone. Clearly, two additional sensitizing 9...

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Abstract

Disclosed is a method for enhancing upconversion luminescence of rare-earth doped particles comprising a host material, an enriched concentration of activator (emitter) and a sufficient concentration level of sensitiser, the method comprising subjecting the particles to increased irradiance. The increased irradiance is higher than presently used relatively low irradiance levels. Enhancing upconversion luminescence involves enhancing luminescence intensity, brightness and / or upconversion efficiency. Particles are preferably subjected to an irradiance power density sufficient to overcome or reverse concentration quenching. The activator preferably has an intermediate meta stable energy level which accepts resonance energy from the sensitiser excited state level. In another form, particles are designed to minimize or exclude quenchers from the upconversion system between sensitizer and activator, such as the core-shell particles wherein the core comprises the host material, sensitiser and the activator, and the shell comprises a material which prevents, retards or inhibits surface quenching.

Description

technical field [0001] The present invention generally relates to methods, systems and / or particles for enhancing upconverting luminescence, preferably in particles doped with rare earth metals. Background technique [0002] For example, up-conversion nanocrystals that convert infrared radiation into higher-energy visible luminescence hold great promise for applications in biosensing, bioimaging, solar cells, and 3-D display technologies. Lanthanide-doped upconversion nanocrystals are often doped with infrared radiation-absorbing ytterbium Yb 3+ sensitizer ion, and non-radiatively transmits the sequential excitation to the activator ion, for example, erbium (Er 3+ ), Thulium (Tm 3+ ), or holmium (Ho 3+ ). Traditionally, the relationship with Yb has been intensively studied 3+ Ionic resonance and Er with ∼0.3% quantum yield for upconversion luminescence 3+ Ion, use it for biomarkers and background-free imaging. Excitation Tm at low irradiance 3+ Under , the activator ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02F2/02C09K11/77
CPCC09K11/7773A61K49/0093C09K11/025C09D11/30A61K49/0058G02F2/02B42D25/29C09D11/50B42D2035/34B41M3/144A61K49/0013
Inventor 金大勇赵江波
Owner MACQUARIE UNIV
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