White light with UV LEDs

Radkov, Emil; Bompiedi, Rebecca; Srivastava, A.M.; Setlur, Anant; Becker, Charles A.

doi:10.1117/12.512865

Cited by 85 publications

(69 citation statements)

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“…In this report, we are comparing K 2 SiF 6 :Mn 4+ phosphors made by typical co-crystallization processes versus GE TriGain phosphors whose synthesis has been modified using proprietary and/or patented processes. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Throughout this report, these phosphors are referred to as "typical" and "TriGain" phosphors, respectively. The particle sizes distribution for all phosphors in this report have a median particle size of 25-30 μm as measured by light scattering (Horiba PA-910).…”

Section: Methodsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] (CAUTION: All experimental procedures in the synthesis and processing of these phosphors involve highly corrosive, toxic, and reactive chemicals. All procedures reported here require extreme caution in handling, usage of appropriate personal protective gear, and suitable disposal procedures due to the hazardous nature of these chemicals.…”

Section: Methodsmentioning

confidence: 99%

“…Cohen, C. Nelson, and F. Du, for discussions and the motivation for this work. GE Lighting Solutions holds patent rights for the use of Mn 4+ -doped complex fluoride phosphors in LEDs systems along with the synthesis and processing of these materials described in this report [1][2][3][4][5][6][7][8][9][10][11][12][13][14] in addition to multiple patent applications in multiple jurisdictions.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…In this report, we demonstrate the effects of synthesis on concentration quenching by analyzing K 2 SiF 6 :Mn 4+ (PFS) phosphors made using proprietary synthesis and processing methods. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Through optimized synthesis and processing, it is possible to reach approximately three times higher Mn concentrations before the onset of strong concentration quenching, defined here as a >5% loss in the phosphor QE. These results for concentration quenching are analyzed using literature models for energy migration and trapping, 15 suggesting that longerrange energy migration processes (e.g.…”

mentioning

confidence: 99%

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Concentration Quenching in K₂SiF₆:Mn⁴⁺ Phosphors

García-Santamaría

Murphy

Setlur

et al. 2017

ECS J. Solid State Sci. Technol.

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In this report, we discuss the effect of synthesis on the concentration quenching of K 2 SiF 6 :Mn 4+ phosphors. Comparing two different synthesis methods, we demonstrate that Mn concentration can be increased by a factor of three before the onset of concentration quenching. These effects are analyzed using literature models for concentration quenching that show that large reductions in defect concentrations are responsible for the improvements in concentration quenching along with a possible change in the mechanism behind concentration quenching. The practical implications for LED packages using high Mn 4+ The loss of phosphor quantum efficiency (QE) at high activator concentrations, or concentration quenching, is a typical phosphor property. When concentration quenching is analyzed in either new or previously known phosphors, the "critical" concentration is defined as the point where either the QE or measured brightness begins to decrease. This concentration is then correlated to an estimate for the distances for energy transfer and possibly the microscopic mechanisms for energy transfer between activators. However, one item that is rarely noted in these studies is how synthesis parameters affect critical concentrations and possibly microscopic mechanisms for energy transfer. In principle, since improved synthesis processes eliminate quenching defects, they should also lead to higher critical concentrations. In this report, we demonstrate the effects of synthesis on concentration quenching by analyzing K 2 SiF 6 :Mn 4+ (PFS) phosphors made using proprietary synthesis and processing methods.1-14 Through optimized synthesis and processing, it is possible to reach approximately three times higher Mn concentrations before the onset of strong concentration quenching, defined here as a >5% loss in the phosphor QE. These results for concentration quenching are analyzed using literature models for energy migration and trapping, 15 suggesting that longerrange energy migration processes (e.g. dipole-dipole energy transfer between activators) are important for materials with higher defect concentrations. At lower defect concentrations, shorter-range energy transfer (e.g. exchange) becomes dominant. These results demonstrate some potential pitfalls when assigning "intrinsic" phosphor properties without accounting for phosphor synthesis. In addition, practical implications for reducing concentration quenching in K 2 SiF 6 :Mn 4+ phosphors are also discussed. Materials and MethodsAll K 2 SiF 6 :Mn 4+ phosphors in this report are synthesized using proprietary and/or patented processes.1-14 (CAUTION: All experimental procedures in the synthesis and processing of these phosphors involve highly corrosive, toxic, and reactive chemicals. All procedures reported here require extreme caution in handling, usage of appropriate personal protective gear, and suitable disposal procedures due to the hazardous nature of these chemicals. At a minimum, it is strongly = These authors contributed equally to this report. recommended to under...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Acknowledgmentsmentioning

confidence: 99%

mentioning

confidence: 99%

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Concentration Quenching in K₂SiF₆:Mn⁴⁺ Phosphors

García-Santamaría

Murphy

Setlur

et al. 2017

ECS J. Solid State Sci. Technol.

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“…LEDs are typically used as illuminators and indicators and used in displays due to low power efficiency, high brightness levels, low operating voltages and longer lifetimes. 1,2 Traditionally, the most efficient LEDs emit radiance in the red region. Recently, a LED based on GaN has been developed.…”

mentioning

confidence: 99%

Enhanced luminescence of Y3Al5O12:Ce3+ nanophosphor for white light-emitting diodes

Haranath¹,

Chander²,

Sharma³

et al. 2006

Applied Physics Letters

159

103

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Results pertaining to the development of highly dispersible stand-alone particles of Ce 3+ -doped Y 3 Al 5 O 12 nanophosphor and their luminescence are presented. The yellow light-emitting nanophosphor was produced as a result of a single-step auto-combustion process, which requires no auxiliary annealing treatments prior to any practical application. The structure, photoluminescence, and chromaticity of the powder nanophosphor samples with the compositions Y ͑3−x͒ Al 5 O 12 : xCe 3+ ͑x = 0.01-1͒ are featured in the letter. The nanophosphor absorbs light efficiently in the visible region of 400-500 nm, and shows single broadband emission peaking at ϳ560 nm. The luminescence yield is almost analogous to the samples made from other conventional methods. Hence, it could be an apt candidate for generating white light when coupled to a blue light-emitting diode ͑ em = 450 nm͒.

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