Ce<sup>3+</sup>-Doped garnet phosphors: composition modification, luminescence properties and applications

Xia, Zhiguo; Meijerink, Andries

doi:10.1039/c6cs00551a

Cited by 897 publications

(476 citation statements)

References 148 publications

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“…Additionally, the band structure of the undoped host material were treated with Density Functional Theory (DFT) and evaluated with UV-reflectance spectroscopy. [1][2][3][4][5] However, this approach suffers from major shortcomings such as cold white light and a low color rendering index (CRI), which results from the lack of red light. Therefore, red phosphors with outstanding luminescent performance and strong absorption in the near UV to blue spectral range are highly demanded.…”

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confidence: 99%

Narrow Band Deep Red Photoluminescence of Y₂Mg₃Ge₃O₁₂:Mn⁴⁺,Li⁺Inverse Garnet for High Power Phosphor Converted LEDs

Jansen

Gorobez

Kirm

et al. 2017

ECS J. Solid State Sci. Technol.

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This work concerns a novel red emitting Mn 4+ doped phosphor showing an extraordinarily high thermal quenching temperature. The composition Y 2 Mg 3 Ge 3 O 12 :Mn 4+ ,Li + exhibits efficient red photoluminescence peaking at 658 nm, which can be assigned to the 2 E g → 4 A 2g intraconfigurational transition of Mn 4+ ([Ar]3d 3 configuration) located at the octahedral site in the garnet structure. Photoluminescence properties, such as temperature dependence of the luminescence intensity and luminescence lifetime are presented. Additionally, the band structure of the undoped host material were treated with Density Functional Theory (DFT) and evaluated with UV-reflectance spectroscopy. [1][2][3][4][5] However, this approach suffers from major shortcomings such as cold white light and a low color rendering index (CRI), which results from the lack of red light. Therefore, red phosphors with outstanding luminescent performance and strong absorption in the near UV to blue spectral range are highly demanded. Compared with the established commercial red phosphors, for example, (Ca,Sr)AlSiN 3 :Eu 2+ and (Ca,Sr,Ba) 2 Si 5 N 8 :Eu 2+ , which typically possess a broad emission band, Mn 4+ activated oxide and fluoride phosphors exhibit an emission spectrum consisting of narrow lines in the red region.6-14 Moreover, the preparation of nitride phosphors requires harsh conditions, i.e. high temperature and pressure, which to a tremendous extent, increase the cost and difficulty of preparation. 15,16 Additionally, rare earth elements as raw materials are too expensive for producing respective phosphors at a low cost-price. Recently, Mn 4+ doped fluoride red emitting phosphors have attracted much attention because of the simple and efficient fabrication process, i.e. they can be prepared at room temperature or slightly above (20-80• C) by cation exchange reaction. 17 However, these types of materials have a huge drawback because toxic hydrofluoric acid is needed for their synthesis. Additionally, Mn 4+ doped fluorides are rather sensitive toward high temperature, high humidity, and large excitation densities provided by LEDs. [18][19][20] In general, Mn 4+ doped oxide phosphors were prepared using conventional oxides, nitrates, and perchlorates as starting materials. All these disadvantages could be overcome by using an oxide type host material, if one is able to find a Mn 4+ doped oxide host with a rather narrow emission band peaking at approximately 630 nm. 24-26 Accordingly, research activity and commercial interest is highly focused on Mn 4+ based phosphors presently. These type of materials can emit in the desired red spectral region with a high quantum yield and thus meet the efficiency and color quality demands of the next generation warm white pcLEDs. It is well known, that the Mg 14 Ge 5 O 24 :Mn 4+ phosphor (also known as Mg-fluorogermanate due to the presence of some MgF 2 as a flux) has extraordinary good properties in terms of the thermal quenching of the luminescence (T 1/2 > 700 K).27 Due to this circumstance, the au...

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confidence: 99%

Narrow Band Deep Red Photoluminescence of Y₂Mg₃Ge₃O₁₂:Mn⁴⁺,Li⁺Inverse Garnet for High Power Phosphor Converted LEDs

Jansen

Gorobez

Kirm

et al. 2017

ECS J. Solid State Sci. Technol.

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“…1e). Absorption still occurs, but without the emission of a photon, leading to a decrease in the quantum efficiency; this behaviour is described as thermal quenching 7 and is typically onset between 100 and 200 °C. When such a phosphor material is embedded in an LED, not only will the emission intensity decrease, but the emission colour of the entire wLED will also change above a certain threshold temperature.…”

Section: News and Viewsmentioning

confidence: 99%

Stabilizing colour and intensity

Smet

Joos

2017

Nature Mater

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Thermally activated defects in a blue-emitting phosphor can enhance energy transfer to the activator, and compensate for thermal quenching.White light-emitting diodes (wLEDs) are rapidly replacing incandescent and fluorescent light sources, both in general lighting and display backlights, due to their long lifetime, small footprint, spectral tunability and most importantly their high efficiency in converting electrical to optical power [Schubert-2005][Abe-2017]. As the emission of LEDs is essentially monochromatic, wLEDs are typically composed of a blue pumping LED and one or more luminescent materials, also called phosphors, which convert part of the blue light to longer wavelengths, the mixture yielding white light (Fig. 1a, c).One of the requirements [Smet-2011] that luminescent materials for LED applications need to fulfil is maintaining their emission intensity at the elevated temperatures that can be reached in the LED device. Won Bin Im and colleagues have developed a novel phosphor, the Eu 2+ -doped phosphate Na3Sc2(PO4)3, which shows an extraordinary thermal stability of the emission intensity for a specific dopant concentration [Kim-2017].

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“…The three most popular approaches are a blue LED with a yellow phosphor; an ultraviolet LED with blue and yellow phosphors (or red, green and blue phosphors); and a device that combines red, green and blue LED chips 7,8 . Unfortunately, each of the schemes suffers some drawbacks.…”

Section: Introductionmentioning

confidence: 99%

Discovery of novel solid solution Ca3Si3−x O3+x N4−2x : Eu2+ phosphors: structural evolution and photoluminescence tuning

Wang

Liu

Huang

et al. 2017

Sci Rep

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Discovery of novel phosphors is one of the main issues for improving the color rendering index (CRI) and correlated color temperature (CCT) of white light-emitting diodes (w-LEDs). This study mainly presents a systematic research on the synthesis, crystal structure variation and photoluminescence tuning of novel (oxy)nitride solid solution Ca3Si3−xO3+xN4−2x: Eu2+ phosphors. XRD refinements show that lattice distortion occurs when x value diverges the optimum one (x = 1). The lattice distortion causes a widening of emission spectrum and an increase of Stokes shift (ΔSS), which leads to a bigger thermal quenching. With decrease of x value, the emission spectrum shows an obvious red-shift from 505.2 to 540.8 nm, which is attributed to the crystal field splitting. The enhanced crystal field splitting also broadens the excitation spectrum, making it possible to serve as the phosphor for near ultraviolet (n-UV) LEDs. A 3-phosphor-conversion w-LED lamp was fabricated with the as-prepared phosphor, which exhibits high CRI (Ra = 85.29) and suitable CCT (4903.35 K). All these results indicate that the Ca3Si3−xO3+xN4−2x: Eu2+ phosphor can serve as the green phosphor for n-UV w-LEDs, with a tunable spectrum by controlling the crystal structure and morphology.

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Ce³⁺-Doped garnet phosphors: composition modification, luminescence properties and applications

Cited by 897 publications

References 148 publications

Narrow Band Deep Red Photoluminescence of Y₂Mg₃Ge₃O₁₂:Mn⁴⁺,Li⁺Inverse Garnet for High Power Phosphor Converted LEDs

Narrow Band Deep Red Photoluminescence of Y₂Mg₃Ge₃O₁₂:Mn⁴⁺,Li⁺Inverse Garnet for High Power Phosphor Converted LEDs

Stabilizing colour and intensity

Discovery of novel solid solution Ca3Si3−x O3+x N4−2x : Eu2+ phosphors: structural evolution and photoluminescence tuning

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Ce3+-Doped garnet phosphors: composition modification, luminescence properties and applications

Cited by 897 publications

References 148 publications

Narrow Band Deep Red Photoluminescence of Y2Mg3Ge3O12:Mn4+,Li+Inverse Garnet for High Power Phosphor Converted LEDs

Narrow Band Deep Red Photoluminescence of Y2Mg3Ge3O12:Mn4+,Li+Inverse Garnet for High Power Phosphor Converted LEDs

Stabilizing colour and intensity

Discovery of novel solid solution Ca3Si3−x O3+x N4−2x : Eu2+ phosphors: structural evolution and photoluminescence tuning

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Product

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Ce³⁺-Doped garnet phosphors: composition modification, luminescence properties and applications

Narrow Band Deep Red Photoluminescence of Y₂Mg₃Ge₃O₁₂:Mn⁴⁺,Li⁺Inverse Garnet for High Power Phosphor Converted LEDs

Narrow Band Deep Red Photoluminescence of Y₂Mg₃Ge₃O₁₂:Mn⁴⁺,Li⁺Inverse Garnet for High Power Phosphor Converted LEDs