On the relationship between emission color and Ce3+ concentration in garnet phosphors

Setlur, Anant; Srivastava, A.M.

doi:10.1016/j.optmat.2006.08.010

Cited by 111 publications

(78 citation statements)

References 25 publications

(34 reference statements)

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“…For these particular phosphors, with 3% activator concentration, the O values were determined to be 4.5, 1.7, and 1.1 for Lu 3 (24). concentration drastically decreases the likelihood of multipole-multipole interactions since that type of transfer relies on close proximity of one activator ion to another.…”

Section: Resultsmentioning

confidence: 97%

An Investigation of Self-Absorption and Corresponding Spectral Shift in Phosphors

2012

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Many light emitting diode (LED) phosphors have overlapping emission and absorption bands, such as Ce 3+ -doped garnets and Eu 2+ -doped silicates, nitrides, and oxynitrides. These overlapping bands inevitably lead to self-absorption effects through either nonradiative energy transfer mediated via electron-electron correlation process or actual emission and radiative energy transfer which involves emission and absorption of a photon due to spectral overlap. The first process has been often discussed in the literature. The second process has been investigated in this work through a semi-quantitative formalism. Spectral shift, changes in emission peak shape, photoluminescent conversion efficiency, and phosphor characterization are discussed in light of self-absorption. The simulated results are compared to experimental data and shown to correlate well with observed data.

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Section: Resultsmentioning

confidence: 97%

An Investigation of Self-Absorption and Corresponding Spectral Shift in Phosphors

2012

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“…Chen reported the enhancement of crystal splitting by increasing activator concentration [12]. Ce 3+ relaxes by electron-phonon interaction to lower energy sites which leads to a red-shift emission and, consequently, a lower energy [13,14]. Simulations to reproduce the physically measured LuAG emission spectra were also carried out and the performance of our simulation method to point out the influence Figure 8 PC-LED emission intensity for LuAG #2 for the following median phosphor particle sizes d 50 (in brackets): LuAG #2# 1 (4.4 μm), LuAG #2# 2 (8.5 μm), LuAG #2# 3 (17.6 μm), LuAG #2# 4 (22 μm), LuAG #2# 5 (26.9 μm), LuAG #2# 6 (31.5 μm), LuAG #2# 7 (37 μm), LuAG #2# 8 (47 μm), LuAG #2# 9 (70 μm).…”

Section: Luagmentioning

confidence: 99%

“…The deviation around the blue emission peak and at the transition range about 470 nm occurs due to similar reasons as discussed for YAG and LuAG in the previous Sections YAG and LuAg. The PC-LED configuration considered in this section is represented by a complex system of two phosphors in which the red-orange phosphor's photoluminescent properties [13] influence the emission spectra of the green phosphors. Our absorption measurements on the phosphors to provide the input parameter for the simulation program influence the multiple phosphor interactions within these PC-LED made of the mixture of two phosphor components very strongly.…”

Section: A Phosphor Systemmentioning

confidence: 99%

Measuring, simulating and optimizing current LED phosphor systems to enhance the visual quality of lighting

Bois

Bodrogi

Khanh

et al. 2014

J Solid State Light

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Lighting engineering aspects of light emitting diodes (LEDs) with down converting phosphors (phosphor converted LEDs or PC-LEDs) were investigated by building sample PC-LEDs, measuring their spectral emission physically and simulating them with a software. This article describes the influence of the phosphors' chemical, physical and technological properties on some well-established and widely used measures of visual lighting quality including luminous efficacy and the color rendering index. The dependence of these measures on YAG and LuAG phosphor particle size and activator concentration in the PC-LEDs is dealt with. Light sources of superior lighting quality can be obtained by mixing several phosphors. Hence, the mixture of a green and red phosphor system was also studied for a set of real PC-LED light sources and their simulations. Two green and two red phosphors are considered in this study. To predict and optimize the lighting quality of PC-LEDs with a reasonable accuracy, a usable input shall be provided for the simulation software assuming the understanding of the emission mechanisms. To validate our simulation results, the PC-LEDs' measured spectral emission characteristics were compared with their simulated counterparts. The measurement and simulation of spectral power distributions contribute to the understanding of new phosphor mixtures. The present simulation method turned out to be usable to optimize the target parameters of the PC-LED (luminous efficacy, white tone quality and color quality of the illuminated colored objects).

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“…Studies on compositional modifications of YAG:Ce 3+ phosphors show that it is possible to redshift the YAG:Ce 3+ emission band by 10-20 nm (2). It is also known that the Ce 3+ doping level also plays an important role in red shifting emission color of these garnets (3). This has been ascribed to inhomogeneous broadening of the Ce 3+ emission band, leading to energy transfer between intrinsic higher energy Ce 3+ sites and lower energy Ce 3+ sites (3).…”

Section: Introductionmentioning

confidence: 99%

“…The garnet structure can be represented by a general formula, {A} 3 [B] 2 (C) 3 O 12 , where {A} cations are eight coordinated in dodecahedra, the [B] cations are octahedrally coordinated, and the (C) cations are tetrahedrally coordinated. The position of the Ce 3+ 5d 1 levels is strongly influenced by the host lattice selection and hence the Ce 3+ emission could be controlled through careful substitutions in dodecahedral, octahedral and tetrahedral sites.…”

Section: Introductionmentioning

confidence: 99%

Controlling Ce3+ Emission Color in Silicate Garnet Phosphor

et al. 2009

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In this report, we discuss the crystal chemistry and luminescence properties of Ce 3+ activated Lu 2-x Ca 1+x Mg 2-x Sc x Si 3 O 12 garnets. We identify that the previously published silicate garnets, Lu 2 CaMg 2 Si 3 O 12 and Ca 3 Sc 2 Si 3 O 12 form a full solid solution with Sc 3+ primarily substituting for Mg 2+ in octahedral and Ca 2+ substitution in the dodecahedral sites. Within this solid solution, both the lowest energy Ce 3+ 4f 1 5d 1 excitation peak and the Ce 3+ 5d 1 4f 1 emission peak blueshifts as x increases with emission maximum for x = 0 at ~605nm and x =2 at ~505nm. The reasons for this blueshift in the luminescence spectra is discussed as well as the thermal quenching of these phosphors as a function of composition.

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On the relationship between emission color and Ce3+ concentration in garnet phosphors

Cited by 111 publications

References 25 publications

An Investigation of Self-Absorption and Corresponding Spectral Shift in Phosphors

An Investigation of Self-Absorption and Corresponding Spectral Shift in Phosphors

Measuring, simulating and optimizing current LED phosphor systems to enhance the visual quality of lighting

Controlling Ce3+ Emission Color in Silicate Garnet Phosphor

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