Origin of the High Upconversion Green Luminescence Efficiency in β-NaYF4:2%Er3+,20%Yb3+

Renero-Lecuna, Carlos; Martín-Rodríguez, Rosa; Valiente, Rafael; González, J.; Rodrı́guez, F.; Krämer, Karl; Güdel, Hans U.

doi:10.1021/cm2004227

Cited by 228 publications

(157 citation statements)

References 20 publications

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“…797.9 cm −1 can be observed. The peaks at ∼146.7, 266.5, 396.1, and 518.9 cm −1 of NaYF 4 are similar to those of the NaYF 4 :Yb 3+ /Er 3+ reported by Güdel and co-workers [30]. For the peaks at ∼639.8 and 797.9 cm −1 , it is noted that the NaYF 4 was coated by oleic acid.…”

Section: Crystal Structure and Morphologysupporting

confidence: 84%

Controlled synthesis and luminescence properties of NaLnW2O8 nanocrystals

Liu

Zhou

Wang

et al. 2012

Journal of Alloys and Compounds

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Section: Crystal Structure and Morphologysupporting

confidence: 84%

Controlled synthesis and luminescence properties of NaLnW2O8 nanocrystals

Liu

Zhou

Wang

et al. 2012

Journal of Alloys and Compounds

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“…The spectral positions observed for the Er 3+ emission lines at 22 and 50 K are in good agreement with previous results on the Er 3+ emission in NaYF 4 :Er 3+ . 33 …”

Section: Resultsmentioning

confidence: 99%

The Role of a Phonon Bottleneck in Relaxation Processes for Ln-Doped NaYF₄ Nanocrystals

et al. 2018

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The localized inner 4f shell transitions of lanthanide ions are largely independent of the local surroundings. The luminescence properties of Ln3+ ions doped into nanocrystals (NCs) are therefore similar to those in bulk crystals. Quantum size effects, responsible for the unique size-dependent luminescence of semiconductor NCs, are generally assumed not to influence the optical properties of Ln3+-doped insulator NCs. However, phonon confinement effects have been reported to hamper relaxation between closely spaced Stark levels in Ln3+-doped NCs. At cryogenic temperatures emission and excitation from higher Stark levels was observed for Ln3+ ions in NCs only and were explained by a cutoff in the acoustic phonon spectrum. Relaxation would be inhibited as no resonant low energy (long wavelength) acoustic phonon modes can exist in nanometer sized crystals, and this prevents relaxation by direct phonon emission between closely spaced Stark levels. This phenomenon is known as a phonon bottleneck. Here, we investigate the role of phonon confinement in Ln-doped NCs. High resolution emission spectra at temperatures down to 2.2 K are reported for various Ln3+ ions (Er3+, Yb3+, Eu3+) doped into monodisperse 10 nm NaYF4 NCs and compared with spectra for bulk (microcrystalline) material. Contrary to previous reports, we find no evidence for phonon bottleneck effects in the emission spectra. Emission from closely spaced higher Stark levels is observed only at high excitation powers and is explained by laser heating. The present results indicate that previously reported effects in NCs may not be caused by phonon confinement.

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“…Renero-Lecuna et al concluded that low-symmetry hosts offer a more highly disorder structures to the emitting ions resulting in a large site distribution. This favors the electronic coupling between the 4f energy levels and higher electronic configurations, thus increasing the probabilities of the f-f transitions [39]. Therefore, low-symmetry hosts, such as hexagonal phase of NaGdF 4 or NaYF 4 , exhibit higher upconversion efficiency relative to their cubic counterparts.…”

Section: Lanthanide-doped Upconverting Nanomaterials (Ln-ucnps)mentioning

confidence: 99%

Photoluminescent nanoplatforms in biomedical applications

Ibarra-Ruiz

Rodríguez

Capobianco

2016

Advances in Physics: X

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Origin of the High Upconversion Green Luminescence Efficiency in β-NaYF₄:2%Er³⁺,20%Yb³⁺

Cited by 228 publications

References 20 publications

Controlled synthesis and luminescence properties of NaLnW2O8 nanocrystals

Controlled synthesis and luminescence properties of NaLnW2O8 nanocrystals

The Role of a Phonon Bottleneck in Relaxation Processes for Ln-Doped NaYF₄ Nanocrystals

Photoluminescent nanoplatforms in biomedical applications

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Origin of the High Upconversion Green Luminescence Efficiency in β-NaYF4:2%Er3+,20%Yb3+

Cited by 228 publications

References 20 publications

Controlled synthesis and luminescence properties of NaLnW2O8 nanocrystals

Controlled synthesis and luminescence properties of NaLnW2O8 nanocrystals

The Role of a Phonon Bottleneck in Relaxation Processes for Ln-Doped NaYF4 Nanocrystals

Photoluminescent nanoplatforms in biomedical applications

Contact Info

Product

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Origin of the High Upconversion Green Luminescence Efficiency in β-NaYF₄:2%Er³⁺,20%Yb³⁺

The Role of a Phonon Bottleneck in Relaxation Processes for Ln-Doped NaYF₄ Nanocrystals