Energy transfer in color-tunable water-dispersible Tb–Eu codoped CaF<sub>2</sub> nanocrystals

Back, Michele; Marin, Riccardo; Franceschin, M.; Hancha, N. Sfar; Enrichi, Francesco; Trave, Enrico; Polizzi, Stefano

doi:10.1039/c5tc03355a

Cited by 44 publications

(16 citation statements)

References 35 publications

(36 reference statements)

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“…They can be model candidates as donor and acceptor in the study of energy transfer (ET). Hence, there have been a plethora of ET research studies concerning lanthanide ions, such as between the tripositive ions Ce‐Eu, Ce‐Tb, Tb‐Eu, Pr‐Yb, Dy‐Tb, Sm‐Eu, and Ho‐Yb, with the focus upon the applied optical properties of phosphors, such as the color tunability of luminescence and optical thermometry. However, Dutra et al have pointed out that in 2015 less than 3% of published studies concerning lanthanide ions made use of theoretical tools.…”

Section: Introductionmentioning

confidence: 99%

Energy Transfer between Tb³⁺ and Eu³⁺ in LaPO₄: Pulsed versus Switched‐off Continuous Wave Excitation

et al. 2019

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The energy transfer (ET) between Tb 3+ and Eu 3+ is investigated experimentally and with available theoretical models in the regime of high Tb 3+ concentrations in ≈30 nm LaPO 4 nanoparticles at room temperature. The ET efficiency approaches 100% even for lightly Eu 3+ ‐doped materials. The major conclusion from the use of pulsed laser excitation and switched‐off continuous wave laser diode excitation is that the energy migration between Tb 3+ ions, situated on La 3+ sites with ≈4 Å separation, is not fast. The quenching of Tb 3+ emission in singly doped LaPO 4 only reduces the luminescence lifetime by ≈50% in heavily doped samples. Various theoretical models are applied to simulate the luminescence decays of Tb 3+ and Tb 3+ , Eu 3+ ‐doped LaPO 4 samples of various concentrations and the transfer mechanism is identified as forced electric dipole at each ion.

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Section: Introductionmentioning

confidence: 99%

Energy Transfer between Tb³⁺ and Eu³⁺ in LaPO₄: Pulsed versus Switched‐off Continuous Wave Excitation

et al. 2019

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“…This indicates that the Ce 3+ ions absorb UV light and transfer energy to neighboring Tb 3+ ions, resulting in the luminescence emission from Tb 3+ ions. As discussed by previous reports [19,27,28,29], the Tb 3+ and Eu 3+ ions are utilized together to achieve the tunable color and obtain bright multicolor emission. Therefore, we reported the NaYF 4 :Ce/Tb/Eu shells are grown on the UC microrods.…”

Section: Resultsmentioning

confidence: 99%

“…Ln 3+ -doped materials with tunable emission colors as security inks have been one of most commonly utilized methods for high-level anti-fake due to its difficult duplication and tunable luminescence properties [15,17,18]. The emission colors from near-ultraviolet (UV) to NIR region have been realized in Ln 3+ -doped particles by adjusting the types and concentrations of emitters and sensitizers [19,20,21]. For example, the Eu 3+ ions could emit visible color under UV illumination, which is applied to the anti-counterfeiting purpose in banks [22].…”

Section: Introductionmentioning

confidence: 99%

“…Hexagonal-phase NaYF 4 is not only considered as excellent UC host materials, but also offers efficient DS emission of Ln 3+ ions such as Tb 3+ and Eu 3+ , hence generating bright green and red DS emission in the visible region [25,26]. Thus, recently, the Tb 3+ and Eu 3+ co-doping in host has aroused many researchers’ interest due to tunable DS emission colors [19,27,28,29]. However, in these literatures, quite little attention has been paid to Tb-Eu co-doped core-shell-structured nanoparticles for dual-mode emission.…”

Section: Introductionmentioning

confidence: 99%

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Simultaneous Dual-mode Emission and Tunable Multicolor in the Time Domain from Lanthanide-doped Core-shell Microcrystals

Song

Khan

et al. 2018

Nanomaterials

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The dual-mode emission and multicolor outputs in the time domain from core-shell microcrystals are presented. The core-shell microcrystals, with NaYF4:Yb/Er as the core and NaYF4:Ce/Tb/Eu as the shell, were successfully fabricated by employing the hydrothermal method, which confines the activator ions into a separate region and minimizes the effect of surface quenching. The material is capable of both upconversion and downshifting emission, and their multicolor outputs in response to 980 nm near-infrared (NIR) excitation laser and 252 nm, and 395 nm ultraviolet (UV) excitation light have been investigated. Furthermore, the tunable color emissions by controlling the Tb3+-Eu3+ ratio in shells and the energy transfer of Ce3+→Tb3+→Eu3+ were discussed in details. In addition, color tuning of core-shell-structured microrods from green to red region in the time domain could be obtained by setting suitable delay time. Due to downshifting multicolor outputs (time-resolved and pump-wavelength-induced downshifting) coupled with the upconversion mode, the core-shell microrods can be potentially applied to displays and high-level security.

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“…Alkaline earth fluoride materials have attracted great attention due to a wide variety of applications in dielectrics, optics, optoelectronics, and photonics . In particular, calcium fluoride has been regarded as one of the most efficient hosts for upconversion (UC) or downconversion emissions, also due to its low phonon energy, which minimizes nonradiative de‐excitation processes .…”

Section: Values Of the A‐axis Parameters Of The Caf2:yb3+ Er3+ Filmsmentioning

confidence: 99%

Nanostructured CaF₂:Ln³⁺ (Ln³⁺ = Yb³⁺/Er³⁺, Yb³⁺/Tm³⁺) Thin Films: MOCVD Fabrication and Their Upconversion Properties

Pellegrino

Cortelletti

Pedroni

et al. 2017

Adv Materials Inter

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it possible to collect the radiation energy outside the absorption range of the photoactive material (usually silicon) by shifting its energy to a more suitable optical region. In addition, rare-earth doped CaF 2 compounds are promising luminescent materials as phosphors and in technological applications as micro-and nanoscale thermometry for microelectronics and for biomedical assays. [4,[16][17][18] A comment deserves the CaF 2 structure, also in view of similar ionic size of the trivalent lanthanide ions, inserted as dopants, and the Ca 2+ ion. Calcium fluoride has the typical fluorite structure, following the name (fluorite) of the mineral form of CaF 2 , which is a simple cubic arrangement of anions with 50% cubic sites filled with Ca 2+ . Thus, in this structure, calcium is eight coordinated by fluoride ions, a coordination environment suitable for the lanthanide ions, being eight one of the most common coordination number for lanthanides. [19] Most of the above-mentioned applications require the calcium fluoride material in the form of thin films. Several studies are available on the deposition of CaF 2 thin films using physical vapor deposition techniques, such as sputtering, [20,21] electron beam evaporation, [22] pulsed laser deposition, [23,24] and molecular beam epitaxy. [25,26] Calcium fluoride films have also been deposited through sol-gel chemical routes using spin coating [27] or dip coating. [28] Among the chemical vapor deposition approaches, atomic layer deposition has been applied to the deposition of CaF 2 films. [29] Nevertheless, even though various deposition methods have been applied to the fabrication of CaF 2 films, a more versatile, easily scalable, fast, and industrially appealing approach is highly desirable.The metal organic chemical vapor deposition (MOCVD) has the potential advantage of being a very reliable and reproducible method for the fast production of films with high uniformity degree in both thickness and composition over large areas. In addition, note that in the case of potential integration of these layers in photovoltaic cell production, plasma-enhanced CVD is the most common fabrication method for thin film Si-based cells. [30] Calcium fluoride represents one of the most efficient hosts for up-conversion or down-conversion emissions. A simple metal organic chemical vapor deposition approach is applied to the fabrication of CaF 2 nanostructured thin films using the fluorinated "second-generation" β-diketonate compound Ca (hfa) 2 •diglyme•H 2 O as a Ca-F single-source precursor. The versatility of the process is demonstrated for the fabrication of up-converting Yb/Er or Yb/Tm codoped CaF 2 films on Si, quartz, and glass substrates. The Ln(hfa) 3 •diglyme (Ln = Tm, Er, Yb) precursors are used as sources of the doping ions. Structural, morphological, and compositional characterization of the films shows the formation of polycrystalline CaF 2 films with a very uniform surface and suitable doping. In fact, an appropriate tuning of the mixture composition, i.e., the Ca:Ln ...

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Energy transfer in color-tunable water-dispersible Tb–Eu codoped CaF₂ nanocrystals

Abstract: The energy transfer process between Tb3+ and Eu3+ ions in water-dispersible CaF2 nanocrystals prepared using a simple process is reported. Fine colour control and long excited state lifetimes make the nanosystem suitable for biosensing applications.

Cited by 44 publications

References 35 publications

Energy Transfer between Tb³⁺ and Eu³⁺ in LaPO₄: Pulsed versus Switched‐off Continuous Wave Excitation

Energy Transfer between Tb³⁺ and Eu³⁺ in LaPO₄: Pulsed versus Switched‐off Continuous Wave Excitation

Simultaneous Dual-mode Emission and Tunable Multicolor in the Time Domain from Lanthanide-doped Core-shell Microcrystals

Nanostructured CaF₂:Ln³⁺ (Ln³⁺ = Yb³⁺/Er³⁺, Yb³⁺/Tm³⁺) Thin Films: MOCVD Fabrication and Their Upconversion Properties

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Energy transfer in color-tunable water-dispersible Tb–Eu codoped CaF2 nanocrystals

Abstract: The energy transfer process between Tb3+ and Eu3+ ions in water-dispersible CaF2 nanocrystals prepared using a simple process is reported. Fine colour control and long excited state lifetimes make the nanosystem suitable for biosensing applications.

Cited by 44 publications

References 35 publications

Energy Transfer between Tb3+ and Eu3+ in LaPO4: Pulsed versus Switched‐off Continuous Wave Excitation

Energy Transfer between Tb3+ and Eu3+ in LaPO4: Pulsed versus Switched‐off Continuous Wave Excitation

Simultaneous Dual-mode Emission and Tunable Multicolor in the Time Domain from Lanthanide-doped Core-shell Microcrystals

Nanostructured CaF2:Ln3+ (Ln3+ = Yb3+/Er3+, Yb3+/Tm3+) Thin Films: MOCVD Fabrication and Their Upconversion Properties

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Energy transfer in color-tunable water-dispersible Tb–Eu codoped CaF₂ nanocrystals

Energy Transfer between Tb³⁺ and Eu³⁺ in LaPO₄: Pulsed versus Switched‐off Continuous Wave Excitation

Energy Transfer between Tb³⁺ and Eu³⁺ in LaPO₄: Pulsed versus Switched‐off Continuous Wave Excitation

Nanostructured CaF₂:Ln³⁺ (Ln³⁺ = Yb³⁺/Er³⁺, Yb³⁺/Tm³⁺) Thin Films: MOCVD Fabrication and Their Upconversion Properties