Origin of strong red emission in Er<sup>3+</sup>-based upconversion materials: role of intermediate states and cross relaxation

Lee, Chiho; Park, Heeyeon; Kim, Woong; Park, Sungnam

doi:10.1039/c9cp04692e

Cited by 25 publications

(13 citation statements)

References 41 publications

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“…This Er 3+ doping level was chosen as a starting point for several reasons: concentrations in this range have been proposed for solar cell applications. [2,24] It has also been demonstrated that the strength of cross-relaxations is acceptable within this concentration range [25,26] and that the absorption cross-section of the particles is not limiting to the experiments. There is of course a trade-off between these two effects.…”

Section: Resultsmentioning

confidence: 88%

“…The radiative electronic transitions of the β-NaYF 4 :Er 3+ nanocrystals corresponding to distinct UC emission peaks are indicated by comparison with the literature in Figure 1b. [26,27] The luminescence emission of the β-NaYF 4 :Er 3+ NPs, from 350 to 1020 nm, in cyclohexane solution is shown in Figure 1c. The spectral data were collected for a continuous wave laser excitation with a power density of P exc = 52 W cm −2 and λ exc = 1551 nm.…”

Section: Resultsmentioning

confidence: 99%

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Metasurface‐Enhanced Photon Upconversion upon 1550 nm Excitation

Ahiboz

Andresen

Manley

et al. 2021

Advanced Optical Materials

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Photon upconversion upon 1550 nm excitation is of high relevance for applications in the third biological excitation window, for photovoltaics beyond current limitations, and enables appealing options in the field of glass fiber telecommunications. Trivalent doped erbium ions (Er3+) are the material of choice for 1550 nm excited upconversion, however, they suffer from a low absorption cross‐section and a low brightness. Therefore, the ability of silicon metasurfaces to provide greatly enhanced electrical near‐fields is employed to enable efficient photon upconversion even at low external illumination conditions. Hexagonally shaped β‐NaYF4:Er3+ nanoparticles are placed on large‐area silicon metasurfaces designed to convert near‐infrared (1550 nm) to visible light. More than 2400‐fold enhanced photon upconversion luminescence is achieved by using this metasurface instead of a planar substrate. With the aid of optical simulations based on the finite‐element method, this result is attributed to the coupling of the excitation source with metasurface resonances at appropriate incident angles. Analysis of the excitation power density dependence of upconversion luminescence and red‐to‐green‐emission ratios enables the estimation of nanoscale near‐field enhancement on the metasurface. The findings permit the significant reduction of required external excitation intensities for photon upconversion of 1550 nm light, opening perspectives in biophotonics, telecommunication, and photovoltaics.

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Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Metasurface‐Enhanced Photon Upconversion upon 1550 nm Excitation

Ahiboz

Andresen

Manley

et al. 2021

Advanced Optical Materials

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“…There would not be enough time for the nonradiation (NR) processes, which produce the 5 I 7 state Ho 3+ for the CR processes, as they are much slower than the energy processes between RE ions do. [60,74] Most Ho 3+ ions would be simply sensitized through the two-photon excitation by Yb 3+ ions and emit green light. Thus, the influence from CR processes would be "rising-falling".…”

Section: Resultsmentioning

confidence: 99%

Insight into the Luminescence Alternation of Sub‐30 nm Upconversion Nanoparticles with a Small NaHoF₄ Core and Multi‐Gd³⁺/Yb³⁺ Coexisting Shells

Kuang

Jia

et al. 2020

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With narrow luminescence peak width, reduced photobleaching, high physical and chemical stability, low toxicity, etc., [4-8] RE-doped UCNPs have been widely utilized in all sorts of fields, [9-17] especially in photoinduced therapies. [18-24] Among these UCNPs, activator (usually Er 3+ , Tm 3+ , Ho 3+) or sensitizer (usually Yb 3+) highly doped ones, provided with unique optical properties like exceptional brightness, single-band emission, lifetime tuning, and so on, [25] which are of great bioapplication potentials, have become a hot research focus recently. [25-33] However, progress has been severely limited as once the activator or sensitizer concentration goes beyond certain values, upconversion luminescence (UCL) intensities would be substantially weakened. [34-38] Take Tm 3+-activated UCL for example. As reported, the UCL intensity of blue emission fell straightly downward to less than 5% when Tm 3+ concentration rose from 2 to merely 10 mol%. [39] Energy loss pathways could easily occur under highly doped circumstances, mainly including acute cross-relaxation (CR) processes within activators, energy-back-transfer (EBT) processes between activators and sensitizers, as well as resonant energy transfer to lattice and surface defects. [40-44] Therefore, probing into these highly doped nanoparticles for the sake of effective methods to improve and finetune their luminescence performances would be urgently required for deeper theory study and wider application use. Holmium (Ho) is a commonly adopted RE element emitting both red and green characteristic upconversion peaks in visible waveband under 980 nm laser excitation, with crest values approximately located at 540 and 645 nm, respectively. [45-47] Similar to Er 3+ , an overall bright green UCL could be obtained in low activator and sensitizer doping concentration. [48-50] To reduce the green/red (G/R) ratio for purer red emission, Ce 3+ is normally employed for its CR processes with Ho 3+ , which could increase the population of excited states 5 I 7 and 5 F 5 of Ho 3+ to promote the red emission. [51-57] In addition to this, other techniques involving high excitation power [58,59] or unwonted types of laser with specific parameters [60,61] could also implement high purity of red UCL, which actually gets unsuitable or too complicated for biouse. In this sense, exploring more targeted strategies would bring out more flexibility for Hobased UCL materials to distinguish themselves. It is absolutely imperative for development of material science to adjust upconversion luminescence (UCL) properties of highly doped upconversion nanoparticles (UCNPs) with special optical properties and prominent application prospects. In this work, featuring NaHoF 4 @NaYbF 4 (Ho@Yb) structures, sub-30 nm core-multishell UCNPs are synthesized with a small NaHoF 4 core and varied Gd 3+ /Yb 3+ coexisting shells. X-ray diffraction, transmission electron microscopy, UCL spectrum, UCL lifetime, and pump power dependence are adhibited for characterization. Compared with the former work, exc...

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“…According to previous studies, there is cross-relaxation between Er 3+ ion and other rare-earth ions (such as Ce 3+ , Ho 3+ , and Yb 3+ ions). [13,14,22] Therefore, we believe that this phenomenon was caused by the crossrelaxation 4 G 11/2 (Er 3+ ) + 2 F 7/2 (Yb 3+ )→ 2 F 5/2 (Yb 3+ ) + 4 F 9/2 (Er 3+ ) in Cs 2 NaEr 1−x Yb x Cl 6 perovskites. The energy level diagram is shown in Figure 2e.…”

Section: Resultsmentioning

confidence: 92%

Er³⁺/Yb³⁺‐Based Halide Double Perovskites with Highly Efficient and Wide Ranging Antithermal Quenching Photoluminescence Behavior for Light‐Emitting Diode Applications

Zhang

Dang

Lian

et al. 2022

Laser & Photonics Reviews

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Rare-earth ion-doped halide perovskite materials have attracted considerable attention owing to their outstanding electrical and optical characteristics. However, the heavy doping of activating rare-earth ions causes severe cross-relaxation and photoluminescence intensity quenching. Herein, the challenge of designing highly efficient emission and antithermal quenching Er 3+ /Yb 3+ -based halide double perovskite single crystals based on abnormal heavy activator doping without severe concentration quenching is addressed. Cross-relaxation is proposed as a possible mechanism. Upon Yb 3+ substitution, the visible and near-infrared (NIR) emission peaks at 664 and 995 nm are greatly enhanced, and the photoluminescence quantum yield of optimized Cs 2 NaEr 0.4 Yb 0.6 Cl 6 is 62% under 379 nm ultraviolet excitation. More importantly, the cross-relaxation between Er 3+ and Yb 3+ is verified. The cross-relaxation enhances the downshifting emission and causes the visible and NIR emissions to exhibit a wide range of antithermal quenching photoluminescence behaviors. The as-prepared halide double perovskites demonstrate great potential for light-emitting diode applications in advanced night vision technology and nondestructive examination.

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Origin of strong red emission in Er³⁺-based upconversion materials: role of intermediate states and cross relaxation

Abstract: Comprehensive NIR-to-visible upconversion luminescence mechanism in Er3+-based materials is elucidated by wavelength-dependent, power-dependent, and time-resolved photoluminescence spectroscopy.

Cited by 25 publications

References 41 publications

Metasurface‐Enhanced Photon Upconversion upon 1550 nm Excitation

Metasurface‐Enhanced Photon Upconversion upon 1550 nm Excitation

Insight into the Luminescence Alternation of Sub‐30 nm Upconversion Nanoparticles with a Small NaHoF₄ Core and Multi‐Gd³⁺/Yb³⁺ Coexisting Shells

Er³⁺/Yb³⁺‐Based Halide Double Perovskites with Highly Efficient and Wide Ranging Antithermal Quenching Photoluminescence Behavior for Light‐Emitting Diode Applications

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Origin of strong red emission in Er3+-based upconversion materials: role of intermediate states and cross relaxation

Abstract: Comprehensive NIR-to-visible upconversion luminescence mechanism in Er3+-based materials is elucidated by wavelength-dependent, power-dependent, and time-resolved photoluminescence spectroscopy.

Cited by 25 publications

References 41 publications

Metasurface‐Enhanced Photon Upconversion upon 1550 nm Excitation

Metasurface‐Enhanced Photon Upconversion upon 1550 nm Excitation

Insight into the Luminescence Alternation of Sub‐30 nm Upconversion Nanoparticles with a Small NaHoF4 Core and Multi‐Gd3+/Yb3+ Coexisting Shells

Er3+/Yb3+‐Based Halide Double Perovskites with Highly Efficient and Wide Ranging Antithermal Quenching Photoluminescence Behavior for Light‐Emitting Diode Applications

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Origin of strong red emission in Er³⁺-based upconversion materials: role of intermediate states and cross relaxation

Insight into the Luminescence Alternation of Sub‐30 nm Upconversion Nanoparticles with a Small NaHoF₄ Core and Multi‐Gd³⁺/Yb³⁺ Coexisting Shells

Er³⁺/Yb³⁺‐Based Halide Double Perovskites with Highly Efficient and Wide Ranging Antithermal Quenching Photoluminescence Behavior for Light‐Emitting Diode Applications