Facile synthesis of multicolor tunable ultrasmall LiYF 4 :Yb,Tm,Er/LiGdF 4  core/shell upconversion nanophosphors with sub-10 nm size

Hong, A-Ra; Kim, Su Yeon; Cho, So-Hye; Lee, Kwangyeol; Jang, Ho Seong

doi:10.1016/j.dyepig.2016.12.048

Cited by 36 publications

(30 citation statements)

References 39 publications

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“…Lanthanide-doped LiYF4 can also be prepared in the form of nanocrystals with very narrow size distribution . This is usually done in high boiling oleic acid-based solvent mixtures, similar to the synthesis of NaYF4 upconversion nanocrystals [62][63][64][65][66]. Since the particles have a small size and display a relatively strong luminescence, they have been proposed for a variety of biomedical and bioimaging applications [79,80,83,87], as well as for transparent displays [70,74] and chemosensing [86].…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the lattice mismatch between an undoped LiYF4 shell and the doped LiYF4 core particle is low which reduces the risk of forming defect states at the core-shell interface. Other shell materials were nevertheless also investigated such as LiGdF4 [65,69], LiLuF4 [71], LiYbF4 [73], SiO2 [63,80], doped LiYF4 [76,77] as well as more complicated particle architectures involving multiple shells [69,74].…”

Section: Introductionmentioning

confidence: 99%

“…Core particle synthesisHOA-based synthesis procedures for nanocrystalline LiYF4 are usually based on the thermal decomposition of trifluoro acetates[63,64,66,67,[78][79][80][81][82][83][84][85][86][87][88][89] or on the reaction of yttrium oleate with either ammonium fluoride and lithium oleate[77] or ammonium fluoride and lithium hydroxide[62,65,[68][69][70][71][72][73][74][75][76]. Here, we prepared the LiYF4 nanoparticles at temperatures above 200 °C via the reaction of ammonium fluoride with rare earth oleates and lithium oleate dissolved in oleic acid/octadecene[62,65,[68][69][70][71][72][73][74][75][76][77]. As usual, an excess of lithium oleate was used corresponding to twice the stoichiometric amount.…”

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confidence: 99%

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LiYF4:Yb/LiYF4 and LiYF4:Yb,Er/LiYF4 core/shell nanocrystals with luminescence decay times similar to YLF laser crystals and the upconversion quantum yield of the Yb,Er doped nanocrystals

et al. 2020

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We developed a procedure to prepare luminescent LiYF4:Yb/LiYF4 and LiYF4:Yb,Er/LiYF4 core/shell nanocrystals with a size of approximately 40 nm revealing luminescence decay times of the dopant ions that approach those of high-quality laser crystals of LiYF4:Yb (Yb:YLF) and LiYF4:Yb,Er (Yb,Er:YLF) with identical doping concentrations. As the luminescence decay times of Yb3+ and Er3+ are known to be very sensitive to the presence of quenchers, the long decay times of the core/shell nanocrystals indicate a very low number of defects in the core particles and at the core/shell interfaces. This improvement in the performance was achieved by introducing two important modifications in the commonly used oleic acid based synthesis. First, the shell was prepared via a newly developed method characterized by a very low nucleation rate for particles of pure LiYF4 shell material. Second, anhydrous acetates were used as precursors and additional drying steps were applied to reduce the incorporation of OH− in the crystal lattice, known to quench the emission of Yb3+ ions. Excitation power density (P)-dependent absolute measurements of the upconversion luminescence quantum yield (ΦUC) of LiYF4:Yb,Er/LiYF4 core/shell particles reveal a maximum value of 1.25% at P of 180 Wcm−2. Although lower than the values reported for NaYF4:18%Yb,2%Er core/shell nanocrystals with comparable sizes, these ΦUC values are the highest reported so far for LiYF4:18%Yb,2%Er/LiYF4 nanocrystals without additional dopants. Further improvements may nevertheless be possible by optimizing the dopant concentrations in the LiYF4 nanocrystals.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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LiYF4:Yb/LiYF4 and LiYF4:Yb,Er/LiYF4 core/shell nanocrystals with luminescence decay times similar to YLF laser crystals and the upconversion quantum yield of the Yb,Er doped nanocrystals

et al. 2020

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“…The lithium-fluoride-based UCNPs (YLiF 4 :Yb,Er) were synthesized by following a solvent thermal protocol reported in [44] and detailed in the Material and Methods section. To visualize the size and morphology of the synthesized UCNPs, a few drops of the sample were placed on a carbon-coated copper grid of a transmission electron microscope (TEM).…”

Section: Resultsmentioning

confidence: 99%

Lithium-Based Upconversion Nanoparticles for High Performance Perovskite Solar Cells

et al. 2021

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In this work, we report an easy, efficient method to synthesize high quality lithium-based upconversion nanoparticles (UCNPs) which combine two promising materials (UCNPs and lithium ions) known to enhance the photovoltaic performance of perovskite solar cells (PSCs). Incorporating the synthesized YLiF4:Yb,Er nanoparticles into the mesoporous layer of the PSCs cells, at a certain doping level, demonstrated a higher power conversion efficiency (PCE) of 19%, additional photocurrent, and a better fill factor (FF) of 82% in comparison to undoped PSCs (PCE = ~16.5%; FF = 71%). The reported results open a new avenue toward efficient PSCs for renewable energy applications.

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“…For instance, in the case of NaYF 4 nanocrystals doped with Yb, Tm, and Er (Figure 8), for a concentration ratio Yb 3+ /Tm 3+ set to 20/0.2 mol %, the color output can be changed from blue to white by means of Er 3+ content increased from 0.2 to 1.5 mol % [80]. Under excitation with a 980 nm wavelength, LiYF 4 nanocrystals co-doped with Yb 3+ , Tm 3+ (0.5%), and Er 3+ (0.1%, 0.2%, 0.3%, 0.5%) exhibit blue and green emission with green-to-blue ratio of the photoluminescence intensity dependent on the Er 3+ concentrations [85]. Yttrium oxide nanoparticles co-doped with Er 3+ , Tm 3+ , and Ho 3+ ions, show red-to-green emission ratio changing versus particle size and up-conversion output color tunable from blue to red upon changes of the dopant amount [86].…”

Section: Spectroscopy Of Nanophosphorsmentioning

confidence: 99%

Nanophosphors-Based White Light Sources

Cesaria

Bartolo

2019

Nanomaterials

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Miniaturization requests and progress in nanofabrication are prompting worldwide interest in nanophosphors as white-emission mercury-free lighting sources. By comparison with their bulk counterparts, nanophosphors exhibit reduced concentration quenching effects and a great potential to enhance luminescence efficiency and tunability. In this paper, the physics of the nanophoshors is overviewed with a focus on the impact of spatial confinement and surface-to-volume ratio on the luminescence issue, as well as rare earth-activated multicolor emission for white light (WL) output. In this respect, the prominently practiced strategies to achieve WL emission are single nanophosphors directly yielding WL by means of co-doping and superposition of the individual red, green, and blue emissions from different nanophosphors. Recently, a new class of efficient broadband WL emitting nanophosphors has been proposed, i.e., nominally un-doped rare earth free oxide (yttrium oxide, Y2O3) nanopowders and Cr transition metal-doped garnet nanocrystals. In regard to this unconventional WL emission, the main points are: it is strictly a nanoscale phenomenon, the presence of an emitting center may favor WL emission without being necessary for observing it, and, its inherent origin is still unknown. A comparison between such an unconventional WL emission and the existing literature is presented to point out its novelty and superior lighting performances.

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Facile synthesis of multicolor tunable ultrasmall LiYF 4 :Yb,Tm,Er/LiGdF 4 core/shell upconversion nanophosphors with sub-10 nm size

Cited by 36 publications

References 39 publications

LiYF4:Yb/LiYF4 and LiYF4:Yb,Er/LiYF4 core/shell nanocrystals with luminescence decay times similar to YLF laser crystals and the upconversion quantum yield of the Yb,Er doped nanocrystals

LiYF4:Yb/LiYF4 and LiYF4:Yb,Er/LiYF4 core/shell nanocrystals with luminescence decay times similar to YLF laser crystals and the upconversion quantum yield of the Yb,Er doped nanocrystals

Lithium-Based Upconversion Nanoparticles for High Performance Perovskite Solar Cells

Nanophosphors-Based White Light Sources

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