White Light Emitting Devices with Enhanced Color Quality

Abstract

A light emitting device comprising: an LED for generating blue light; a green phosphor for generating green light; and a manganese activated fluoride narrowband phosphor for generating red light; wherein a ratio of a maximum intensity in the red region of the spectrum to a minimum intensity in the yellow to orange region of the spectrum is from about 5.0 to about 15.0.

Claims

1. A light emitting device comprising: an LED for generating blue light; a green phosphor for generating green light; and a manganese activated fluoride narrowband phosphor for generating red light; wherein the device is for generating light having an intensity versus wavelength spectrum with a ratio of a maximum intensity in the red region of the spectrum to a minimum intensity in the yellow to orange region of the spectrum is from about 5.0 to about 15.0.

2. The device of claim 1, wherein the manganese activated fluoride narrowband phosphor is selected from the group consisting of: K.sub.2SiF.sub.6:Mn.sup.4+, K.sub.2GeF.sub.6:Mn.sup.4+, K.sub.2TiF.sub.6:Mn.sup.4+, Na.sub.2SiF.sub.6:Mn.sup.4+, Na.sub.2GeF.sub.6:Mn.sup.4+, Na.sub.2TiF.sub.6:Mn.sup.4+, NaKSiF.sub.6:Mn.sup.4+, NaKGeF.sub.6:Mn.sup.4+, and NaKTiF.sub.6:Mn.sup.4+.

3. The device of claim 1, wherein the device has a Luminous Efficacy of Radiation, LER, of at least 300 lm/W.sub.opt and is for generating light with an IES TM-30-15 Gamut Index, R.sub.g, of at least 105 or an IES TM-30-15 Gamut Index, R.sub.g, from 105 to 120.

4. The device of claim 1, wherein at least one of the following applies: the ratio of the maximum intensity in the red region of the spectrum to the minimum intensity in the yellow to orange region of the spectrum is about 11.0 to about 15.0 and the device is for generating light with a CRI Ra of at least 70; the ratio of the maximum intensity in red region of the spectrum to the minimum intensity in the yellow to orange region of the spectrum is about 8.0 to about 11.0 and the device is for generating light with a CRI Ra of at least 80; and the ratio of the maximum intensity in red region of the spectrum to the minimum intensity in the yellow to orange region of the spectrum is about 5.0 to about 8.0 and the device is for generating light with a CRI Ra of at least 90.

5. The device of claim 1, wherein at least one of the following applies: a ratio of a maximum intensity in a red region of the spectrum to a maximum intensity in a green region of the spectrum is from 6.0 to 10.0; a ratio of a maximum intensity in a green region of the spectrum to a minimum intensity in a yellow to orange region of the spectrum is about 1.0 to about 1.5; a ratio of a maximum intensity in a blue region of the spectrum to a minimum intensity in a cyan region of the spectrum is from about 4.0 to about 6.0; and a ratio of a maximum intensity in a green region of the spectrum to a maximum intensity in a blue region of the spectrum is from about 1.0 to about 1.2.

6. A light emitting device comprising: an LED for generating blue light; a green phosphor for generating green light; and a manganese activated fluoride narrowband phosphor for generating red light; wherein the device is for generating light of a selected color temperature having an intensity versus wavelength spectrum comprising: an intensity in a green region of the spectrum that is greater than an intensity of the Planckian spectrum of the selected color temperature; an intensity in a yellow to orange region of the spectrum that is less than an intensity of the Planckian spectrum of the selected color temperature; and an intensity in a red region of the spectrum that is greater than an intensity of the Planckian spectrum of the selected color temperature; and wherein at least one of following applies: a maximum intensity in the green region is 110% to 150% of the intensity of the Planckian spectrum; a minimum intensity in the yellow to orange region is 50% to 80% of the intensity of the Planckian spectrum; and a maximum intensity in the red region is 400% to 600% of the intensity of the Planckian spectrum.

7. The device of claim 6, wherein the manganese activated fluoride narrowband phosphor is selected from the group consisting of: K.sub.2SiF.sub.6:Mn.sup.4+, K.sub.2GeF.sub.6:Mn.sup.4+, K.sub.2TiF.sub.6:Mn.sup.4+, Na.sub.2SiF.sub.6:Mn.sup.4+, Na.sub.2GeF.sub.6:Mn.sup.4+, Na.sub.2TiF.sub.6:Mn.sup.4+, NaKSiF.sub.6:Mn.sup.4+, NaKGeF.sub.6:Mn.sup.4+, and NaKTiF.sub.6:Mn.sup.4+.

8. The device of claim 6, wherein the green region is from 500 nm to 565 nm; the yellow to orange region is from 550 nm to 609 nm; and the red region is from 605 nm to 640 nm.

9. The device of claim 6, wherein the device has a Luminous Efficacy of Radiation, LER, of at least 300 lm/W.sub.opt and is for generating light with an IES TM-30-15 Gamut Index, R.sub.g, of at least 105, or an IES TM-30-15 Gamut Index, R.sub.g, from 105 to 120.

10. A light emitting device comprising: an LED for generating blue light; a green phosphor for generating green light; and a manganese activated fluoride narrowband phosphor for generating red light; wherein the device has a Luminous Efficacy of Radiation, LER, of at least 300 lm/W.sub.opt and is for generating light with an IES TM-30-15 Gamut Index, R.sub.g, of at least 105.

11. The device of claim 10, wherein the manganese activated fluoride narrowband phosphor is selected from the group consisting of K.sub.2SiF.sub.6:Mn.sup.4+, K.sub.2GeF.sub.6:Mn.sup.4+, K.sub.2TiF.sub.6:Mn.sup.4+, Na.sub.2SiF.sub.6:Mn.sup.4+, Na.sub.2GeF.sub.6:Mn.sup.4+, Na.sub.2TiF.sub.6:Mn.sup.4+, NaKSiF.sub.6:Mn.sup.4+, NaKGeF.sub.6:Mn.sup.4+, and NaKTiF.sub.6:Mn.sup.4+.

12. The device of claim 10, wherein the device is for generating light with an LER from 300 lm/W.sub.opt to 330 lm/W.sub.opt, and/or an R.sub.g from 105 to 120.

13. The device of claim 10, wherein at least one of the following applies: the device has an LER from 300 lm/W.sub.opt to 305 lm/W.sub.opt and is for generating light with a CRI Ra of at least 70 and an R.sub.g of 115 to 120; the device has an LER from 305 lm/W.sub.opt to 315 lm/W.sub.opt and is for generating light with a CRI Ra of at least 80 and an R.sub.g of 115 to 120; and the device has an LER from 315 lm/W.sub.opt to 330 lm/W.sub.opt and is for generating light with a CRI Ra of at least 90 and an R.sub.g of 105 to 115.

14. The device of claim 10, wherein the manganese activated fluoride narrowband phosphor comprises from 55 wt % to 75 wt % of a total phosphor content.

15. The device of claim 10, wherein the green phosphor comprises from 25 wt % to 45 wt % of a total phosphor content.

16. The device of claim 10, comprising an orange phosphor for generating orange light.

17. The device of claim 16, wherein the orange light has a peak emission wavelength from 600 nm to 620 nm.

18. The device of claim 16, wherein the orange phosphor comprises from 25 wt % to 45 wt % of a total phosphor content.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] These and other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures, in which:

[0066] FIG. 1 is a sectional view of a packaged white light emitting device in accordance with an embodiment of the invention;

[0067] FIGS. 2A and 2B respectively show a plan view and a cross-sectional side view through A-A of COB (Chip On Board) packaged white light emitting device in accordance with an embodiment of the invention;

[0068] FIG. 3 is a view of a CSP (Chip Scale Packaged) white light emitting device in accordance with an embodiment of the invention;

[0069] FIG. 4 shows spectra, normalized intensity (a.u.) versus wavelength (nm), for light emitting device Dev.3-70 CRI (solid line) and a Planckian (blackbody) radiator (dashed line) of temperature T that is the same as the CCT of Dev.3 (2531 K);

[0070] FIG. 5 shows spectra, normalized intensity versus wavelength (nm) for light emitting device Dev.4-80 CRI (solid line) and Planckian (blackbody) radiator (dashed line) of temperature T that is the same as the CCT of Dev.3 (2531 K); and

[0071] FIG. 6 shows spectra, normalized intensity (a.u.) versus wavelength (nm), for: (i) light emitting device Dev.9-90 CRI (solid line) and Planckian (blackbody) radiator (dashed line) of temperature T that is the same as the CCT of Dev.4 (2770 K).

DETAILED DESCRIPTION OF THE INVENTION

[0072] Embodiments of the present invention will now be described in detail with reference to the drawings, which are provided as illustrative examples of the invention so as to enable those skilled in the art to practice the invention. Notably, the figures and examples below are not meant to limit the scope of the present invention to a single embodiment, but other embodiments are possible by way of interchange of some or all of the described or illustrated elements. Moreover, where certain elements of the present invention can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present invention will be described, and detailed descriptions of other portions of such known components will be omitted so as not to obscure the invention. In the present specification, an embodiment showing a singular component should not be considered limiting; rather, the invention is intended to encompass other embodiments including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present invention encompasses present and future known equivalents to the known components referred to herein by way of illustration.

[0073] Throughout this specification like reference numerals are used to denote like parts preceded by the figure number #. For example, a light emitting device is denoted 110 in FIG. 1 is denoted 210 in FIG. 2 and so forth.

[0074] A light emitting device 110 in accordance with an embodiment of the invention are now described with reference to FIG. 1 which shows a sectional side view of the device 110. The light emitting device 110 is a package-type device, for example an SMD (Surface Mount Device) 2835 LED package 112. The SMD package 112 comprises a housing comprising a rectangular base 114 and side walls 116A, 116B extending upwardly from opposing edges of the rectangular base 114. The interior surfaces of the side walls 116A, 116B slope inwardly to their vertical axis and together with interior surface of the base 114 define a rectangular cavity (cup) 118.

[0075] In this embodiment, the cavity 118 comprises one or more InGaN (indium gallium nitride) violet to blue (450 to 485 nm) LED dies 120, a first photoluminescence material layer 122 comprising a manganese-activated fluoride narrowband red phosphor that covers the one or more LED dies 120, and a second photoluminescence material layer 124 comprising a green phosphor that is disposed on and covers the first photoluminescence material layer 122. As illustrated, the first photoluminescence material layer 122 may fill approximately at least 70% of the cavity 118 and the second photoluminescence material layer 124 may fill the remainder of the cavity.

[0076] In this way, there is provided a light emitting device 110 comprising: a blue LED 120; a first photoluminescence material layer 122 comprising a manganese-activated fluoride narrowband red phosphor disposed on the LED 120 and a second photoluminescence material layer 124 comprising a green phosphor covering the first photoluminescence material layer 122.

[0077] Providing the manganese-activated fluoride narrowband red phosphor as an individual layer significantly reduces the usage amount of the narrowband red phosphor compared with known arrangements in which the photoluminescence materials are provided as a mixture in a single layer. However, it is contemplated that in other embodiments, the manganese-activated fluoride narrowband red phosphor and the green phosphor may be provided as a mixture in a single layer. The first photoluminescence material layer 122 contains a majority, for example at least 75 wt %, of manganese-activated fluoride narrowband red phosphor compared with other phosphors that may be in the layer. The first photoluminescence material layer 122 may contain other materials such as light scattering particles or light diffusive material for example. Typically, the amount of the other materials is no more than 30% weight of the manganese-activated fluoride narrowband red phosphor. Further, in this embodiment, the first photoluminescence material layer 122 may be constituted by K.sub.2SiF.sub.6:Mn.sup.4+ (but equally may be constituted by one or a combination of K.sub.2SiF.sub.6:Mn.sup.4+, K.sub.2GeF.sub.6:Mn.sup.4+, K.sub.2TiF.sub.6:Mn.sup.4+, Na.sub.2SiF.sub.6:Mn.sup.4+, Na.sub.2GeF.sub.6:Mn.sup.4+, Na.sub.2TiF.sub.6:Mn.sup.4+, NaKSiF.sub.6:Mn.sup.4+, NaKGeF.sub.6:Mn.sup.4+, and NaKTiF.sub.6:Mn.sup.4+) and may be dispersed in dimethyl silicone. The first photoluminescence material layer 122 is directly in contact with and adjacent the LED 20. There are no other photoluminescence material containing layers between the first photoluminescence material layer 122 and the LED 120.

[0078] As described, in this embodiment, the device 110 also comprises a second photoluminescence material layer 124 disposed on top of the first photoluminescence material layer 122 and which fills the cavity 118. In this embodiment, the photoluminescence material layer 124 comprises a broadband green phosphor. The second photoluminescence material layer 124 in addition to the broadband green phosphor may contain other minority orange phosphors.

[0079] In this embodiment, the light emitting device 110 thus constitutes a two-layer (multi-layer) photoluminescence structure. In this way, the light emitting device 110 is able to effectively isolate the manganese-activated fluoride narrowband red phosphor in the first photoluminescence material layer 122 from direct contact with any water/moisture in the surrounding environment. Such a multi-layer or two-layer design of the light emitting device 110 provides an effective solution to address the poor moisture reliability of manganese-activated fluoride narrowband red phosphors in known constructions. Thus, the inclusion of the manganese-activated fluoride narrowband red phosphor in a separate photoluminescence material layer 124 provides the benefit of improved moisture reliability to the light emitting device (i.e., LED package) 110.

[0080] It is to be noted that the first photoluminescence material layer 122 is in closer proximity to the LED 120 than any other photoluminescence material layer(s) including the second photoluminescence material layer 124; that is the first photoluminescence material layer 122 is proximal (i.e. a proximal layer) to the LED 120, while the second photoluminescence material layer 124 is distal (i.e., a distal layer) to the LED 120.

[0081] The described light emitting device structure comprising a photoluminescence material layer comprising substantially only manganese-activated fluoride narrowband red phosphor limited to surface mount packaged devices. For instance, it can also be applied in Chip on Board (COB), Chip Scale Packaging (CSP) applications, or LED-Filaments.

[0082] With reference to FIGS. 2A and 2B, there is shown a plan view of a COB light emitting device 210 in accordance with another embodiment of the invention, and a cross-sectional side view through A-A (of FIG. 2A). The light emitting device 210 comprises a square substrate 214, for example a Metal Core Printed Circuit Board (MCPCB). Forming a COB arrangement, 7 arrays (rows) of blue LED dies 220 are disposed on the substrate 214 as a circular array. The substrate 214 also comprises an annular wall 216 which encloses all the blue LED dies 220.

[0083] A first photoluminescence material layer 222 comprising a manganese-activated fluoride narrowband red phosphor is deposited onto the substrate 214 and, in this embodiment, completely covers the LEDs 220. Similarly, a second photoluminescence material layer 224 comprising a green phosphor is deposited onto first photoluminescence material layer 224. In this way, the first photoluminescence material layer 222 and the second photoluminescence material layer 224 are located on top of one another and also contained inside the wall 216.

[0084] The light emitting device 210 functions and exhibits the same advantages as discussed in relation the light emitting device of FIG. 1 for example. Hence, the statement made in relation to FIG. 1 apply equally to the embodiment of FIGS. 2A and 2B.

[0085] With reference to FIG. 3, there is shown a side view of a CSP light emitting device 310 in accordance with another embodiment of the invention. In this embodiment, a first photoluminescence material layer 322 comprising a manganese-activated fluoride narrowband red phosphor is disposed directly on a light emitting face of a blue LED die 320. Further, a second photoluminescence material layer 324 comprising a broadband green phosphor disposed onto the first photoluminescence material layer 322. The light emitting device 310 functions and exhibits the same advantages as discussed in relation the light emitting device of FIG. 1, for example. Hence, the statement made in relation to FIG. 1 apply equally to the embodiment of FIG. 3.

[0086] It will be understood that, in other embodiments, the light emitting device may comprise a single layer photoluminescence structure. In this way, the single layer may comprise a mixture of the manganese-activated fluoride narrowband red phosphor and the broadband green phosphor. An example of such a single layer photoluminescence structure is shown in FIGS. 2 and 3 and the accompanying text in paragraphs [0079]-[0087] of US Patent Publication Number US 2024/0120448 A1, which is hereby incorporated by way of reference.

Broadband Green Phosphor Materials

[0087] In this patent specification, a green phosphor material refers to a photoluminescence material (phosphor) which, in response to stimulation by excitation light, generates light having a peak emission wavelength (4e) from about 500 nm to about 565 nm (more typically from 520 nm to 550 nm), that is in the green region of the visible spectrum. Preferably the green phosphor has abroad emission characteristic with a FWHM (Full Width at Half Maximum) of 100 nm or wider. The green phosphor can comprise garnet-based phosphor such as YAG or LuAG phosphors. Examples of suitable green phosphors are given in Table 1.

[0088] In embodiments, the green phosphor comprises a cerium-activated yttrium aluminum garnet phosphor of general composition (Y,Ba).sub.3(Al,Ga).sub.5O.sub.12:Ce (YAG) such as, for example, a GNYAG series phosphor from Intematix Corporation, Fremont California, USA. In this patent specification, the notation YAG #represents the phosphor typeYAGbased phosphorsfollowed by the peak emission wavelength in nanometers (#). For example, YAG535 denotes a YAG phosphor with a peak emission wavelength of 535 nm.

[0089] In some embodiments, the phosphor can comprise a cerium-activated lutetium aluminum garnet (LuAG) of general composition Lu.sub.3Al.sub.5O.sub.12:Ce (GAL). Examples of such phosphors include for example the GAL series of phosphor from Intematix Corporation, Fremont California, USA which have a peak emission wavelength of 516 nm to 560 nm and a FWHM of 120 nm. In this patent specification, the notation GAL #represents the phosphor type (GAL)LuAGbased phosphorsfollowed by the peak emission wavelength in nanometers (#). For example, GAL520 denotes a GAL phosphor with a peak emission wavelength of 520 nm.

[0090] In embodiments, the green phosphor comprises a europium-activated silicate phosphor of general composition A.sub.2SiO.sub.4:Eu (Sil) where A=Mg, Ca, Sr, Ba such as, for example, EG and G series Silicate phosphor from Intematix Corporation, Fremont California, USA. In this patent specification, the notation SIL #represents the phosphor typeSILbased phosphorsfollowed by the peak emission wavelength in nanometers (#). For example, SIL525 denotes a silicate phosphor with a peak emission wavelength of 525 nm.

TABLE-US-00001 TABLE 1 Example broadband green phosphors Phosphor General Composition GNYAG (Y, Ba).sub.3x(Al.sub.1yGa.sub.y).sub.5O.sub.12:Ce.sub.x 0.01 < x < 0.2 & 0 < y < 2.5 LuAG Lu.sub.3x(Al.sub.1yM.sub.y).sub.5O.sub.12:Ce.sub.x 0.01 < x < 0.2 & 0 < y < 1.5, M = Mg, Ca, Sr, Ba, Ga LuAG Lu.sub.3x(Al.sub.1yGa.sub.y).sub.5O.sub.12:Ce.sub.x 0.01 < x < 0.2 & 0 < y < 1.5 Silicate A.sub.2SiO.sub.4:Eu A = Mg, Ca, Sr, Ba Silicate (Sr.sub.1xBa.sub.x).sub.2SiO.sub.4:Eu 0.3 < x < 0.9

Broadband Orange Phosphor Materials

[0091] In this patent specification, an orange phosphor refers to a photoluminescence material (phosphor) which, in response to stimulation by excitation light, generates light having a peak emission wavelength from 590 nm to 625 nm; that is light in the orange region of the visible spectrum. Preferably, the orange phosphor has a broad emission characteristic with a full width at half maximum (FWHM) emission intensity of at least 50 nm. The orange phosphor material can include for example a europium activated silicon nitride-based phosphor, or silicate-based phosphors. Examples of broadband orange phosphors are given in Table 2.

[0092] In some embodiments, the europium-activated silicon nitride-based phosphor comprises a Calcium Aluminum Silicon Nitride phosphor (CASN) of general composition CaAlSiN.sub.3:Eu.sup.2+. The CASN phosphor can be doped with other elements such as strontium (Sr) and have a general formula (Sr,Ca)AlSiN.sub.3:Eu.sup.2+. In this patent specification, the notation CASN #represents the phosphor type (CASN) followed by the peak emission wavelength (.sub.pe) in nanometers (#). For example, CASN615 denotes an orange to red CASN phosphor with a peak emission wavelength of 615 nm.

[0093] In some embodiments, a broadband orange phosphor can comprise a europium-activated nitride-based phosphor of general composition (Ba,Sr).sub.2Si.sub.5N.sub.8:Eu.

[0094] In embodiments, the broadband orange phosphor comprises a europium-activated silicate phosphor of general composition (Ba,Sr).sub.3SiO.sub.5:Eu (SIL) such as, for example, 0 series Silicate phosphors from Intematix Corporation, Fremont California, USA.

TABLE-US-00002 TABLE 2 Example broadband orange phosphors Phosphor General Composition CASN (Ca.sub.1xSr.sub.x)AlSiN.sub.3:Eu 0.5 < x 1 258 Nitride Ba.sub.2xSr.sub.xSi.sub.5N.sub.8:Eu 0 x 2 Silicate (Ba.sub.1xSr.sub.x).sub.3SiO.sub.5:Eu 0 x 0.5 Silicate Ba.sub.xY.sub.ySr.sub.1xy).sub.3(Al.sub.ySi.sub.1y)O.sub.5:Eu 0 x 0.2, 0 y 0.4

Narrowband Red Phosphor Materials

[0095] In this patent specification, a narrowband red phosphor material refers to a photoluminescence material which, in response to stimulation by excitation light, generates light having a peak emission wavelength from 628 nm to 640 nm; that is light in the red region of the visible spectrum and which has a narrow emission characteristic with a full width at half maximum (FWHM) emission intensity from about 5 nm to about 30 nm. As described above, the narrowband red phosphor can comprise a manganese-activated narrowband red fluoride phosphor. An example of a manganese-activated narrowband red fluoride phosphor is manganese-activated potassium hexafluorosilicate phosphor (KSF)K.sub.2SiF.sub.6:Mn.sup.4+ (KSF). An example of such a KSF phosphor is NR6931 series KSF phosphor from Intematix Corporation, Fremont California, USA which has a peak emission wavelength of about 632 nm. Other manganese-activated phosphors can include: K.sub.2GeF.sub.6:Mn.sup.4+ (KGF), K.sub.2TiF.sub.6:Mn.sup.4+ (KTF), Na.sub.2SiF.sub.6:Mn.sup.4+ (NSF), Na.sub.2GeF.sub.6:Mn.sup.4+ (NGF), Na.sub.2TiF.sub.6:Mn.sup.4+ (NTF), NaKSiF.sub.6:Mn.sup.4+ (NKSF), NaKGeF.sub.6:Mn.sup.4+ (NKGF), and NaKTiF.sub.6:Mn.sup.4+ (NKTF).

Nomenclature

[0096] In this specification, the nomenclature Dev. #denotes light emitting devices in accordance with embodiments for generating high gamut index (R.sub.g) light.

Packaged Light Emitting Device Test Method

[0097] The packaged test method involves measuring total light emission of a packaged light emitting device in an integrating sphere.

2700K White Light Emitting Devices

[0098] Packaged light emitting devices in accordance with the invention (Dev.1 to Dev.11) each comprise a 1734 package devices with a two-layer photoluminescence layer structure (FIG. 1) and contain a blue LED chip of dominant wavelength Xd (450 nm to 452.5 nm). In the case of Dev.11, this contains 3 blue LED chips connected in series. The narrowband red phosphor is provided in the first photoluminescence layer and the other phosphor(s) (green phosphor and optionally orange phosphor) in the second photoluminescence layer.

[0099] Table 3 tabulates phosphor compositions for 2700K nominal color temperature light emitting device denoted Dev.1 to Dev.11 in accordance with the invention in which: devices Dev.1 to Dev.3 are configured to generate white light with a target (minimum) general color rendering index (CRI Ra) of 70; Dev.4 and Dev.5 are configured to generate white light with a target (minimum) CRI Ra of 80; and Dev.6 to Dev.11 are configured to generate white light with a target (minimum) CRI Ra of 90.

[0100] For example, as can be seen from Table 3, in terms of phosphor composition: Dev.1 comprises 64.8 wt % KSF (narrowband red phosphore.g. KSF, but equally may be constituted by one or a combination of K.sub.2SiF.sub.6:Mn.sup.4+, K.sub.2GeF.sub.6:Mn.sup.4+, K.sub.2TiF.sub.6:Mn.sup.4+, Na.sub.2SiF.sub.6:Mn.sup.4+, Na.sub.2GeF.sub.6:Mn.sup.4+, Na.sub.2TiF.sub.6:Mn.sup.4+, NaKSiF.sub.6:Mn.sup.4+, NaKGeF.sub.6:Mn.sup.4+, and NaKTiF.sub.6:Mn.sup.4+), 34.6 wt % SIL525 (Green silicate phosphor with a peak emission wavelength .sub.pe of 525 nm), and 0.6 wt % CASN615 (Orange nitride phosphor with a peak emission wavelength .sub.pe of 615 nm). The ratio of orange phosphor (CASN615) to the sum of orange phosphor (CASN615) and narrowband red phosphor (KSF) is 0.9%.

[0101] As can be seen from Table 3, devices in accordance with the invention can, depending on the target CRI Ra, comprise from 55% to 75% narrowband red phosphor (e.g. KSF, but equally may be constituted by one or a combination of K.sub.2SiF.sub.6:Mn.sup.4+, K.sub.2GeF.sub.6:Mn.sup.4+, K.sub.2TiF.sub.6:Mn.sup.4+, Na.sub.2SiF.sub.6:Mn.sup.4+, Na.sub.2GeF.sub.6:Mn.sup.4+, Na.sub.2TiF.sub.6:Mn.sup.4+, NaKSiF.sub.6:Mn.sup.4+, NaKGeF.sub.6:Mn.sup.4+, and NaKTiF.sub.6:Mn.sup.4+), 45% to 25% green phosphor, and may additionally comprise 0.5% to 4.5% orange phosphor. Although the values are for devices that are for generating white light with a target CCT of 2700K, test data indicates that similar ranges apply to devices that are for generating white light with a CCT from 2200K to about 3000K.

TABLE-US-00003 TABLE 3 2700K White light emitting device phosphor composition Phosphor composition Target Red Orange (min.) Green (wt %) (wt %) (wt %) Ratio CASN615: Device CRI Ra SIL525 YAG535 YAG542 KSF CASN615 (KSF + CASN615) Dev. 1 70 34.6 64.8 0.6 0.9% Dev. 2 70 35.4 64.6 0.0% Dev. 3 70 25.9 71.5 2.6 3.5% Dev. 4 80 26.1 73.9 0.0% Dev. 5 80 26.1 73.9 0.0% Dev. 6 90 31.7 65.4 2.9 4.2% Dev. 7 90 30.4 67.4 2.2 3.2% Dev. 8 90 38.3 58.4 3.3 5.3% Dev. 9 90 36.2 59.6 4.2 6.6% Dev. 10 90 30.7 66.4 2.7 3.9% Dev. 11 90 37.7 64.9 3.4 5.0%

[0102] Table 4 tabulates measured test data for light emitting devices Dev.1 to Dev.11 in accordance with the invention. Rows including shading (i.e., Dev.3CRI Ra 70, Dev.4CRI Ra 80, and Dev.9CRI Ra 90) indicate that these devices have been optimized for both Gamut index (R.sub.g) and for Luminous Efficacy of Radiation (LER). These devices may be optimized by the selection of the color point (chromaticity CIE 1931 x, y) of light generated by the device which will depend on selected color temperature and by the choice of phosphor and relative quantity of phosphors.

[0103] As can be seen from Table 4, devices in accordance with the invention can, depending on the target CRI Ra, have a Luminous Efficacy of Radiation (LER) from about 300 lm/W.sub.opt to about 330 lm/W.sub.opt(300.6 to 326.2 lm/W.sub.opt), that is at least 300 lm/W.sub.opt, and generate light having: (i) a Gamut index (R.sub.g) from about 105 to about 120 (106.5 to 118.9), that is gamut index, R.sub.g, of at least 105, (ii) a General Color Rendering Index, CRI Ra, from about 70 to 95 (72.2 to 93.9), that is at least 70, (iii) a Color Rendering Index, CRI R9, from about 30 to 95 (31.1 to 95.1), that is at least 30, and (iv) a CIE 1976 D.sub.uv of 0.005 to 0.015 (0.0054 to 0.0129).

TABLE-US-00004 TABLE 4 Measured test data CRI IES TM-30-15 Device CCT (K) Ra R9 R.sub.g R.sub.f Dev. 1 2673 72.2 31.1 116.2 81.8 Dev. 2 2706 74.7 37.3 115.4 83.5 Dev. 3 2531 74.7 48.9 118.9 79.3 Dev. 4 2531 82.9 63.1 116.0 84.2 Dev. 5 2749 85.3 72.0 110.8 88.7 Dev. 6 2792 91.7 94.5 108.7 90.2 Dev. 7 2713 93.8 82.7 107.8 88.7 Dev. 8 2726 93.9 82.3 106.5 90.1 Dev. 9 2770 93.2 92.3 110.9 84.4 Dev. 10 2816 93.6 94.9 109.0 88.4 Dev. 11 2764 93.6 95.1 108.7 88.8 Chromaticity CIE 1931 CIE 1976 LER Device x y u v D.sub.uv Lm/W.sub.opt Dev. 1 0.4408 0.3734 0.2672 0.3395 0.0129 300.6 Dev. 2 0.4395 0.3747 0.2657 0.3397 0.0122 303.3 Dev. 3 0.4540 0.3796 0.2732 0.3426 0.0114 303.7 Dev. 4 0.4376 0.3762 0.2636 0.3400 0.0114 311.0 Dev. 5 0.4388 0.3789 0.2632 0.3409 0.0104 311.0 Dev. 6 0.4361 0.3781 0.2617 0.3404 0.0105 315.2 Dev. 7 0.4432 0.3822 0.2646 0.3423 0.0095 319.5 Dev. 8 0.4434 0.3829 0.2644 0.3425 0.0092 320.5 Dev. 9 0.4421 0.3888 0.2608 0.3440 0.0067 324.5 Dev. 10 0.4403 0.3888 0.2596 0.3438 0.0065 325.0 Dev. 11 0.4459 0.3931 0.2613 0.3456 0.0054 326.2

Spectral Characteristics

[0104] The spectral characteristics of light emitting devices in accordance of the invention are described with reference to FIGS. 4 to 6 which respectively show spectra, normalized intensity (a.u.) versus wavelength (nm), for light emitting devices Dev.3, Dev.4, and Dev.9 (solid line) and a Planckian (blackbody) radiator (dashed line) of temperature that is the same as the CCT of the device.

[0105] FIG. 4 shows spectra, normalized intensity (a.u.) versus wavelength (nm), for light emitting device Dev.3CRI 70 (solid line) and a Planckian (blackbody) radiator (dashed line) of temperature T that is the same as the CCT of Dev.3 (2531 K).

[0106] FIG. 5 shows spectra, normalized intensity versus wavelength (nm) for light emitting device Dev.4CRI 80 (solid line) and Planckian (blackbody) radiator (dashed line) of temperature T that is the same as the CCT of Dev.3 (2531 K).

[0107] FIG. 6 shows spectra, normalized intensity (a.u.) versus wavelength (nm), for: (i) light emitting device Dev.9CRI 90 (solid line) and Planckian (blackbody) radiator (dashed line) of temperature T that is the same as the CCT of Dev.4 (2770 K).

[0108] To enable comparison of the spectra (i.e., measured and Planckian spectra), each spectrum has been normalized such that each has a CIE 1931 XYZ relative luminance Y=100. The data are normalized using the CIE 1931 luminosity function y() of a standard observer which takes account of the photopic response of an observer. The Planckian (blackbody) spectrum for a given temperature T corresponds to a CIE General CRI (Ra), IES TM-30-15 Gamut Index Rg and Fidelity Index Rf equal to 100 for that temperature.

[0109] Referring to FIG. 4, though it will be understood that the following applies equally to FIGS. 5 and 6, the intensity versus wavelength spectrum of light generated by devices according to the invention exhibit, in order from shorter wavelengths (Blue) to longer wavelengths (Red), five spectral characteristics (features): (i) in a blue wavelength region of the spectrum (Blue region) 430 a first spectral feature (peak) 432, (ii) in a cyan wavelength region of the spectrum (Cyan region) 434 a second spectral feature (trough) 436, (iii) in a green wavelength region of the spectrum (Green region) 438 a third spectral feature (peak) 440, (iv) in a yellow to orange wavelength region of the spectrum (Yellow/Orange region) 442 a fourth spectral feature (trough) 444, and (v) in a red wavelength region of the spectrum (Red region) 446 a fifth spectral feature (multiple peaks) 448.

[0110] As shown in FIG. 4, the intensity of the spectral features 432, 440, 448 in the Blue region, Green region, and Red region respectively is greater than the intensity of the Planckian spectrum P.S. (dashed line). Conversely, as shown in FIG. 4 the intensity of the spectral features 436, 444 in the Cyan region, and Yellow/Orange region is less than the intensity of the Planckian spectrum P.S. (dashed line).

[0111] As described herein, an intensity that is greater than the intensity of the Planckian spectrum is indicative of increased color saturation in this wavelength region of the spectrum. Since the intensity in both the Green and Red wavelength regions of the spectrum is greater than the intensity of the Planckian spectrum indicates increased color saturation of both green and red light which can increase the gamut index (R.sub.g) of light generated by the device. Conversely, since the intensity in the Yellow/Orange region of the spectrum is less than intensity of the Planckian spectrum indicates decreased color saturation in this wavelength region which it is postulated enhances color contrast between red and green light leading to a perceived improvement in light quality.

Spectral Characterization

[0112] Parameters used to characterize the spectral features (characteristics) of the various wavelength regions are provided in this section.

[0113] > is a wavelength range for which the intensity of light generated by the device (I.sub.Dev) is greater than (>) the intensity of the Planckian Spectrum (I.sub.PS) and is applicable to the Blue region, Green region, and the Red region. For example, for device Dev.3, in the Green region the wavelength range > is 497 nm to 549 nm (Table 5c).

[0114] .sub.max1 is a wavelength of maximum intensity of light generated by the device (I.sub.Dev) in the wavelength range > and is applicable to the Blue region, Green region, and the Red region. For example, for device Dev.3, in the Green region the wavelength of maximum intensity .sub.max1 is 530 nm (Table 5c).

[0115] I.sub.max is an intensity of light generated by the device (I.sub.Dev) at .sub.max1 and is applicable for the Blue region, Green region, and the Red region. For example, for device Dev.3, in the Green region the maximum intensity of light generated by the device I.sub.max is 0.9135 (Table 5c). In the case of the Red region, I.sub.max is the intensity of the highest emission peak #48 (FIGS. 4 to 6).

[0116] < is a wavelength range for which the intensity of light generated by the device (I.sub.Dev) is less than (<) the intensity of the Planckian Spectrum (I.sub.PS) and is applicable to the Cyan region and Yellow/Orange region. For example, for device Dev.3, in the Yellow/Orange region the wavelength range < is 550 nm to 607 nm (Table 5d).

[0117] .sub.min1 is the wavelength of minimum intensity of light generated by the device (I.sub.Dev) in the wavelength range < and is applicable to the Cyan region, and the Yellow/Orange region. For example, for device Dev.3, in the Yellow/Orange region .sub.min1 is 578 nm (Table 5d).

[0118] I.sub.min is an intensity of light generated by the device (I.sub.Dev) at .sub.min1 and is applicable to the Cyan region, and the Yellow/Orange region. For example, for device Dev.3, in the Yellow/Orange region the minimum intensity of light generated by the device I.sub.min is 0.6837 (Table 5d).

[0119] .sub.maxI is the wavelength of maximum difference between the intensity of light generated by the device (I.sub.Dev) and the intensity of the Planckian Spectrum (I.sub.PS) within a wavelength region >, < and is applicable to the Blue region, Cyan region, Green region, Yellow/Orange and the Red region. For example, for device Dev.3, in the Green region .sub.maxI is 516 nm and in the Yellow/Orange region is 594 nm (Tables 5c and 5d).

[0120] I.sub.max is the intensity of light generated by the device (I.sub.Dev) at .sub.maxI and is applicable to the Blue region, Cyan region, Green region, Yellow/Orange region and the Red region. For example, for device Dev.3, in the Green region I.sub.max is 0.8366 and in the Yellow/orange region is 0.7073 (Table 5c and 5d).

[0121] I.sub.max is a percentage ratio of the intensity of light generated by the device (I.sub.Dev) and the intensity of the Planckian Spectrum (I.sub.PS) at .sub.maxI and is applicable to the Blue region, Cyan region, Green region, Yellow/Orange region and the Red region. For the Blue region, Green region, and Red region in which the intensity of light generated by the device is greater than the intensity of the Planckian Spectrum, I.sub.max will have a value of greater than 100%. For the Cyan region, and yellow/Orange region in which the intensity of light generated by the device is less than the intensity of the Planckian Spectrum, I.sub.max will have a value of less than 100%. For example, for device Dev.3, in the Green region I.sub.max is 146% (i.e., I.sub.Dev is 46% greater than I.sub.PS) and in the Yellow/orange region I.sub.max is 58% (i.e., I.sub.Dev is 42% less than I.sub.PS) (Table 5c and 5d). In Tables 5a to 5e the values of I.sub.max in parentheses are maximum percentage difference (deviation) of I.sub.Dev from I.sub.PS (i.e., I.sub.max100).

[0122] RI.sub.max is a maximum intensity of light generated by the device in the Red region.

[0123] GI.sub.max is a maximum intensity of light generated by the device in the Green region.

[0124] BI.sub.max is a maximum intensity of light generated by the device in the Blue region.

[0125] CI.sub.min is a minimum intensity of light generated by the device in the Cyan region.

[0126] OI.sub.min is a minimum intensity of light generated by the device in the Yellow/Orange region.

TABLE-US-00005 TABLE 5a Measured spectral characteristics Blue region #30: I.sub.Dev > I.sub.PS (Peak #32) > .sub.maxI I.sub.max .sub.maxI I.sub.max I.sub.max Device (nm) (nm) (a.u.) (nm) (a.u) (%) Dev. 3 422-462 441 0.7614 440 0.7554 398 (298) Dev. 4 423-465 447 0.8561 447 0.8561 320 (220) Dev. 9 425-465 445 0.8802 444 0.8695 333 (233)

TABLE-US-00006 TABLE 5b Measured spectral characteristics Cyan region #34: I.sub.Dev < I.sub.PS (trough #36) < .sub.minI I.sub.min .sub.maxI I.sub.max I.sub.max Device (nm) (nm) (a.u.) (nm) (a.u) (%) Dev. 3 463-496 476 0.1841 478 0.1858 53 (47) Dev. 4 466-507 482 0.1917 484 0.1978 45 (55) Dev. 9 460-510 479 0.1494 482 0.1547 36 (64)

TABLE-US-00007 TABLE 5c Measured spectral characteristics Green region #38: I.sub.Dev > I.sub.PS (Peak #40) > .sub.maxI I.sub.max .sub.maxI I.sub.max I.sub.max Device (nm) (nm) (a.u.) (nm) (a.u) (%) Dev. 3 497-549 530 0.9135 516 0.8366 146 (46) Dev. 4 508-555 542 0.9195 524 0.8532 126 (26) Dev. 9 511-564 564 0.9515 528 0.7861 111 (11)

TABLE-US-00008 TABLE 5d Measured spectral characteristics Yellow/Orange region #42: I.sub.Dev < I.sub.PS (trough #44) < .sub.minI I.sub.min .sub.maxI I.sub.max I.sub.max Device (nm) (nm) (a.u.) (nm) (a.u) (%) Dev. 3 550-607 578 0.6837 594 0.7053 58 (42) Dev. 4 556-608 595 0.7286 595 0.7286 52 (38) Dev. 9 565-607 595 0.9466 606 0.8752 79 (21)

TABLE-US-00009 TABLE 5e Measured spectral characteristics Red region #46: I.sub.Dev > I.sub.PS (Multiple Peaks #48) > .sub.maxI I.sub.max .sub.maxI I.sub.max I.sub.max Device (nm) (nm) (a.u.) (nm) (a.u) (%) Dev. 3 608-637 631 8.6325 631 8.6325 552 (452) Dev. 4 609-637 631 7.6286 631 7.6286 525 (425) Dev. 9 608-637 631 5.9346 631 5.9346 411 (311)

TABLE-US-00010 TABLE 5f Measured spectral characteristics Ratio of intensity of spectral features Device RI.sub.max:GI.sub.max RI.sub.max:OI.sub.min GI.sub.max:OI.sub.min BI.sub.max:CI.sub.min GI.sub.max:BI.sub.max Dev. 3 9.45 12.63 1.34 4.14 1.19 Dev. 4 8.30 10.47 1.26 4.47 1.07 Dev. 9 6.24 6.27 1.01 5.89 1.08

[0127] Light emitting devices in accordance with the invention can generate light with an intensity wavelength spectrum containing one or more of the five spectral features described herein.

[0128] As described herein light emitting devices according to embodiments may be for generating light of a selected color temperature having an intensity versus wavelength spectrum comprising: an intensity in a Green region of the spectrum that is greater than an intensity of the Planckian spectrum of the same selected color temperature; an intensity in a yellow to orange region of the spectrum that is less than an intensity of the Planckian spectrum of the same selected color temperature; and an intensity in a Red region of the spectrum that is greater than an intensity of the Planckian spectrum of the same selected color temperature. It is postulated that such a spectral characteristic may increase gamut index R.sub.g and increase red/green contrast which is perceived as being an improvement in light quality.

[0129] For devices generating light having such a spectral characteristic, a maximum intensity of light in the Green region may be 110% to 150% of the intensity of the Planckian spectrum (I.sub.max: 111% to 146%Table 5c); a minimum intensity of light in Yellow/Orange region may be 50% to 80% of the intensity of the Planckian spectrum (I.sub.max: 52% to 79%Table 5d); and/or a maximum intensity of light in the Red region may be 400% to 600% of the intensity of the Planckian spectrum (I.sub.max: 411% to 552%Table 5e).

[0130] The Green region may be in a wavelength range from 500 nm to 570 nm (>: 497 nm to 564 nmTable 5c); the Yellow/Orange region may be in a wavelength range (<) from 550 nm to 608 nm (<: 550 nm to 608 nmTable 5d); the Red region may be in a wavelength range from 608 nm to 640 nm (>: 608 nm to 637 nmTable 5e).

[0131] Light emitting devices in accordance with the invention can generate light with an intensity wavelength spectrum in which a ratio of a maximum intensity in Red region of the spectrum to a minimum intensity in the Yellow/Orange region of the spectrum is from about 5.0 to about 15.0 (RI.sub.max:GI.sub.max 6.27 to 12.63Table 5f).

[0132] Where the device is for generating light with a CRI Ra of at least 70 a ratio of a maximum intensity in Red region of the spectrum to a minimum intensity in the Yellow/Orange region of the spectrum may be from about 11.0 to about 15.0.

[0133] Where the device is for generating light with a CRI Ra of at least 80 a ratio of a maximum intensity in Red region of the spectrum to a minimum intensity in the Yellow/Orange region of the spectrum may be from about 8.0 to 11.0.

[0134] Where the device is for generating light with a CRI Ra of at least 90 a ratio of a maximum intensity in Red region of the spectrum to a minimum intensity in the Yellow/Orange region of the spectrum may be from about 5.0 to 8.0.

[0135] Light emitting devices according to the invention may generate light with an intensity versus wavelength spectrum in which a ratio of a maximum intensity in a Red region of the spectrum to a maximum intensity in a Green region of the spectrum is from about 6.0 to about 10.0 (RI.sub.max:GI.sub.max 6.24 to 9.45Table 5f).

[0136] Alternatively, or in addition light emitting devices according to the invention can generate light with an intensity versus wavelength spectrum in which or a ratio of a maximum intensity in Green region of the spectrum to a minimum intensity in the Yellow/Orange region of the spectrum is from about 1.0 to about 1.5 (GI.sub.max:OI.sub.min 1.01 to 1.34Table 5f).

[0137] Alternatively, or in addition light emitting devices according to the invention can generate light with an intensity versus wavelength spectrum in which or a ratio of a maximum intensity in Blue region of the spectrum to a minimum intensity in the Cyan region of the spectrum is from about 4.0 to about 6.0 (BI.sub.max:CI.sub.min 4.14 to 5.89Table 5f).

[0138] Alternatively, or in addition light emitting devices according to the invention can generate light with an intensity versus wavelength spectrum in which or a ratio of a maximum intensity in Green region of the spectrum to a maximum intensity in the Blue region of the spectrum is from about 1.0 to about 1.2 (GI.sub.max:BI.sub.max 1.07 to 1.19Table 5f).

[0139] The Blue region may be in a wavelength range from 420 nm to 470 nm (>: 422 nm to 465 nmTable 5a); and the Cyan region may be in a wavelength range (<) from 460 nm to 510 nm (<: 460 nm to 510 nmTable 5b).

[0140] In summary, it will be appreciated that light emitting devices in accordance with the invention may comprise an LED for generating blue light; a green phosphor for generating green light; and a manganese activated fluoride narrowband phosphor for generating red light, and have one or more of the following features: (i) the device is for generating light having an intensity versus wavelength spectrum with a ratio of a maximum intensity in the red region of the spectrum to a minimum intensity in the yellow to orange region of the spectrum is from about 5.0 to about 15.0; (ii) the device is for generating light having an intensity versus wavelength spectrum in which at least one of the following applies: the ratio of the maximum intensity in the red region of the spectrum to the minimum intensity in the yellow to orange region of the spectrum is about 11.0 to about 15.0 and the device is for generating light with a CRI Ra of at least 70; the ratio of the maximum intensity in red region of the spectrum to the minimum intensity in the yellow to orange region of the spectrum is about 8.0 to about 11.0 and the device is for generating light with a CRI Ra of at least 80; and the ratio of the maximum intensity in red region of the spectrum to the minimum intensity in the yellow to orange region of the spectrum is about 5.0 to about 8.0 and the device is for generating light with a CRI Ra of at least 90; (iii) the device is for generating light having an intensity versus wavelength spectrum in which at least one of the following applies: a ratio of a maximum intensity in a red region of the spectrum to a maximum intensity in a green region of the spectrum is from 6.0 to 10.0; a ratio of a maximum intensity in a green region of the spectrum to a minimum intensity in a yellow to orange region of the spectrum is about 1.0 to about 1.5; a ratio of a maximum intensity in a blue region of the spectrum to a minimum intensity in a cyan region of the spectrum is from about 4.0 to about 6.0; and a ratio of a maximum intensity in a green region of the spectrum to a maximum intensity in a blue region of the spectrum is from about 1.0 to about 1.2; (iv) the device is for generating light of a selected color temperature having an intensity versus wavelength spectrum comprising: an intensity in a green region of the spectrum that is greater than an intensity of the Planckian spectrum of the selected color temperature; an intensity in a yellow to orange region of the spectrum that is less than an intensity of the Planckian spectrum of the selected color temperature; and an intensity in a red region of the spectrum that is greater than an intensity of the Planckian spectrum of the selected color temperature; and wherein at least one of following applies: a maximum intensity in the green region is 110% to 150% of the intensity of the Planckian spectrum; a minimum intensity in the yellow to orange region is 50% to 80% of the intensity of the Planckian spectrum; and a maximum intensity in the red region is 400% to 600% of the intensity of the Planckian spectrum; (v) the device is for generating light having an intensity versus wavelength spectrum in which the green region is from 500 nm to 565 nm; the yellow to orange region is from 550 nm to 609 nm; and the red region is from 605 nm to 640 nm; (vi) the device has a Luminous Efficacy of Radiation, LER, of at least 300 lm/W.sub.opt(vii) the device has an LER from 300 lm/W.sub.opt to 330 lm/W.sub.opt; (viii) the device is for generating light with an IES TM-30-15 Gamut Index, R.sub.g, of at least 105; (ix) the device is for generating light with an R.sub.g from 105 to 120; (x) at least one of the following applies: the device has an LER from 300 lm/W.sub.opt to 305 lm/W.sub.opt and is for generating light with a CRI Ra of at least 70 and an R.sub.g of 115 to 120; the device has an LER from 305 lm/W.sub.opt to 315 lm/W.sub.opt and is for generating light with a CRI Ra of at least 80 and an R.sub.g of 115 to 120; and the device has an LER from 315 lm/W.sub.opt to 330 lm/W.sub.opt and is for generating light with a CRI Ra of at least 90 and an R.sub.g of 105 to 115; (xi) the manganese activated fluoride narrowband phosphor comprises from 55 wt % to 75 wt % of a total phosphor content; (xii) the green phosphor comprises from 25 wt % to 45 wt % of a total phosphor content; (xiii) comprises an orange phosphor for generating orange light, optionally with a peak emission wavelength from 600 nm to 620 nm, and optionally the orange phosphor comprises from 25 wt % to 45 wt % of a total phosphor content; and (xiv) the manganese activated fluoride narrowband phosphor is selected from the group consisting of: K.sub.2SiF.sub.6:Mn.sup.4+, K.sub.2GeF.sub.6:Mn.sup.4+, K.sub.2TiF.sub.6:Mn.sup.4+, Na.sub.2SiF.sub.6:Mn.sup.4+, Na.sub.2GeF.sub.6:Mn.sup.4+, Na.sub.2TiF.sub.6:Mn.sup.4+, NaKSiF.sub.6:Mn.sup.4+, NaKGeF.sub.6:Mn.sup.4+, and NaKTiF.sub.6:Mn.sup.4+. [0141] > Wavelength range for which intensity of Device (I.sub.Dev) is greater than (>) intensity of the Planckian Spectrum (I.sub.PS) [0142]

REFERENCE NUMERALS

[0156] #10 Light emitting device [0157] #12 Package [0158] #14 Base [0159] #16 Side wall [0160] #18 Cavity (cup) [0161] #20 LED [0162] #22 First photoluminescence layer [0163] #24 Second photoluminescence layer [0164] #30 Blue regionblue region of the spectrum [0165] #32 First spectral feature (peak) [0166] #34 Cyan regioncyan region of the spectrum [0167] #36 Second spectral feature (trough) [0168] #38 Green regiongreen region of the spectrum [0169] #40 Third spectral feature (peak) [0170] #42 Yellow to orange regionyellow to orange region of the spectrum [0171] #44 Fourth spectral feature (trough) [0172] #46 Red regionred region of the spectrum [0173] #48 Fifth spectral feature (maximum intensity peak)