Phosphor-converted white light emitting device and photoluminescent compound for general illumination and display backlighting

Abstract

The present invention relates to phosphor-converted white light emitting devices and photoluminescent compounds for general lighting and display backlighting. The present invention relates to a phosphor-converted white light emitting device comprising: a solid-state light emitter LED operable to generate blue light with a dominant wavelength in the range of 440 nm to 470 nm; a yellow to green light emitting phosphor operable to generate light with a peak emission wavelength in the range of 500 nm to 550 nm; and a red light emitting manganese-activated fluoride phosphor, such as a manganese-activated potassium hexafluorosilicate phosphor (K2SiF6:Mn 4+ The yellow to green phosphor and the red light emitting phosphor are incorporated in a mixture and dispersed throughout a light transmitting material having a refractive index of 1.40 to 1.43.

Description

[0001] This application is a divisional application of the invention patent application filed on September 1, 2016, with application number 201680065907.3, and entitled "Phosphor-converted white light emitting device and photoluminescent compound for general lighting and display backlighting."

[0002] Cross-reference to related applications

[0003] This application claims the benefit of priority to U.S. Provisional Application No. 62 / 216,985, filed September 10, 2015, and U.S. Provisional Application No. 62 / 344,930, filed June 2, 2016, each of which is incorporated herein by reference in its entirety. Technical Field

[0004] The present disclosure relates to phosphor-converted white light emitting devices and photoluminescent compounds. In particular, but not exclusively, embodiments of the present disclosure relate to white light emitting devices and photoluminescent compounds for generating white light with a high color rendering index (CRI) of 90 or higher for general lighting applications. Furthermore, embodiments of the present disclosure relate to white light emitting devices and photoluminescent compounds for use in backlighting for high color gamut displays. Background Art

[0005] Recently, white light emitting LEDs ("white LEDs") have become more popular and more commonly used to replace conventional fluorescent, compact fluorescent, and incandescent light sources. White LEDs typically include one or more photoluminescent materials (typically inorganic phosphor materials) that absorb a portion of the radiation emitted by the LED and re-emit light of a different color (wavelength). The phosphor material can be provided as a layer on or incorporated into a wavelength conversion component located remote from the LED. Typically, the LED generates blue light and the phosphor absorbs a percentage of the blue light and re-emit yellow light, green light, or a combination of green and yellow light. The portion of the blue light generated by the LED that is not absorbed by the phosphor material combines with the light emitted by the phosphor to provide light that appears to the human eye as white in color. White LEDs have also found widespread use in backlighting for liquid crystal displays, such as televisions, computer monitors, laptop computers, tablet computer devices, and smartphones.

[0006] To produce white light with a higher CRI, for example 80 or higher, it is known to additionally include red and / or orange emitting phosphors in the wavelength conversion component.

[0007] The present invention relates to improvements in white light emitting devices and display backlights with improved luminous efficacy, color rendering and / or color gamut. Summary of the Invention

[0008] Embodiments of the present invention relate to white light emitting devices including wavelength-converting phosphors for general illumination and display backlighting.

[0009] According to an embodiment of the present invention, a white light emitting device includes: a solid-state light emitter operable to generate blue light having a dominant wavelength in the range of 440 nm to 470 nm; a yellow to green light emitting phosphor excitable by blue light and operable to generate light having a peak emission wavelength in the range of 500 nm to 575 nm; a red light emitting manganese-activated fluoride phosphor having a refractive index of approximately 1.4 (i.e., n≈1.39 to ≈1.43); and a light-transmitting material having a refractive index of 1.40 to 1.43, comprising a mixture of the yellow to green light emitting phosphor and the red light emitting manganese-activated fluoride phosphor. Typically, the mixture of the yellow to green light emitting and red light emitting manganese-activated fluoride phosphors is incorporated into (dispersed in) the light-transmitting material and is uniformly distributed throughout the light-transmitting material.

[0010] It was found that incorporating yellow- to green-emitting and red-emitting manganese-activated fluoride phosphors into a light-transmitting material having a refractive index comparable to that of the red-emitting manganese-activated fluoride phosphor resulted in a substantial increase (approximately 5% increase) in the luminous flux emitted by the device, compared to devices using other light-transmitting materials having a higher refractive index. It is hypothesized that the increase in luminous flux is caused by increased red light extraction (and / or excitation) of the red-emitting manganese-activated fluoride phosphor having a comparable refractive index of approximately 1.4 due to the refractive index of the light-transmitting material (n≈1.4). In one embodiment, the red-emitting manganese-activated fluoride phosphor comprises a red-emitting manganese-activated potassium hexafluorosilicate phosphor, the composition of which may be represented by the chemical formula K2SiF6:Mn 4+ Representative. K2SiF6:Mn 4+ It is expected that the present invention may be useful with other red-light emitting manganese-activated fluoride phosphors having a refractive index of about 1.4, and it is believed that manganese-activated fluoride phosphors having these properties may include K2TiF6:Mn 4+ 、K2SnF6:Mn 4+ 、Na2TiF6:Mn 4+ 、Na2ZrF6:Mn 4+ 、Cs2SiF6:Mn 4+ 、Cs2TiF6:Mn 4+ 、Rb2SiF6:Mn 4+ 、Rb2TiF6:Mn 4+ 、K3ZrF7:Mn 4+ 、K3NbF7:Mn 4+ 、K3TaF7:Mn 4+ 、K3GdF6:Mn 4+ 、K3LaF6:Mn 4+and K3YF6:Mn 4+ .

[0011] In some embodiments, the light transmissive material is a methyl-based silicone such as dimethylsiloxane or polydimethylsiloxane.

[0012] The yellow-to-green light-emitting phosphor includes any phosphor that can be excited by blue light and is operable to emit light having a peak wavelength of 500 nm to 575 nm. In one embodiment intended for general illumination, the yellow-to-green light-emitting phosphor includes a cerium-activated garnet phosphor such as a cerium-activated yttrium aluminate (YAG) phosphor or a cerium-activated lutetium aluminate (LuAG) phosphor. Examples of YAG phosphors can be represented by the chemical formula Y 3-x (Al 1-y Ga y )5O 12 :Ce x where 0.01 < x < 0.2 and 0 < y < 2.5. Examples of LuAG phosphors can be represented by the chemical formula Lu 3-x (Al 1-y M y )5O 12 :Ce x where M is at least one of Mg, Ca, Sr, Ba, Ga, and combinations thereof, 0.01 < x < 0.2, and 0 < y < 1.5. In one embodiment, M = Ga and the LuAG phosphor can be represented by the chemical formula Lu 3-x (Al 1-y Ga y )5O 12 :Ce x . The YAG or LuAG phosphor may further include a halogen such as F, Cl, or Br.

[0013] In another embodiment intended for general illumination, the green light-emitting phosphor includes an europium-activated silicate phosphor represented by the chemical formula A2SiO4:Eu, where A is at least one of Mg, Ca, Sr, Ba, and combinations thereof. The europium-activated silicate phosphor may further include a halogen such as F, Cl, or Br. The yellow-to-green light-emitting phosphor includes a cerium-activated garnet phosphor.

[0014] For display backlighting, the yellow-to-green light-emitting phosphor preferably includes a narrow-band green light-emitting phosphor having a peak emission wavelength that matches the green filter of the display, typically 535 nm. In this specification, a narrow-band light-emitting phosphor refers to a phosphor having an emission peak with a FWHM (full width at half maximum) of about 50 nm or less. In an embodiment, the yellow-to-green light-emitting phosphor includes an europium-activated β-SiAlON phosphor having a FWHM of 50 - 52 nm. An example of the europium-activated β-SiAlON phosphor is represented by the chemical formula Mx Si 12-(m+n) Al m+n O n N 16-n :Eu represents, where M is at least one of Mg, Ca, Sr, and combinations thereof, 0.01 < x < 0.1, 0.01 < m < 0.12, and 0.1 < n < 0.5. In another embodiment, the yellow-to-green light-emitting phosphor comprises an europium-activated sulfide phosphor represented by the general formula SrGa2S4:Eu with a FWHM of 46 - 48 nm.

[0015] For general lighting, the white light-emitting device may further comprise an orange-to-red light-emitting phosphor that can be excited by blue light and is operable to emit light having a peak emission wavelength in the range of 580 nm to 620 nm. It has been found that including a third orange-to-red light-emitting phosphor provides a significant increase in the brightness of the device (about 8%), an increase in the general CRI (Ra), an increase in CRI (R9), and an increase in the luminous efficacy (LE).

[0016] The light-transmitting material comprises a mixture of a yellow-to-green light-emitting phosphor, a red light-emitting manganese-activated fluoride phosphor, and an orange-to-red light-emitting phosphor.

[0017] In some embodiments, the orange light-emitting phosphor comprises an europium-activated silicon nitride phosphor such as CASN(1-1-1-3) or 2-5-8 silicon nitride phosphor, which has a general crystal structure of M′2Si5N8:Eu, where M is at least one of Mg, Ca, Sr, Ba, and Zn.

[0018] In an embodiment, the CASN phosphor may be represented by the chemical formula (Ca 1-x Sr x )AlSiN3:Eu, where 0.5 < x ≤ 1. In an embodiment, the 2-5-8 silicon nitride phosphor may be represented by the chemical formula Ba 2-x Sr x Si5N8:Eu, where 0 ≤ x ≤ 2. Preferably, the orange light-emitting phosphor produces light having a peak emission wavelength in the range of 590 nm to 610 nm.

[0019] The present invention finds that it is specifically applied to high CRI devices and the device can be advantageously operated to produce white light with a general CRI (Ra) of 90 or higher. In this patent specification, unless otherwise specified, CRI refers to the general CRI (Ra) that is the average of CRI (R1) to CRI (R8). In an embodiment, the white light-emitting device is operable to produce white light with a correlated color temperature (CCT) between 2700 K and 3000 K and a general CRI (Ra) of 90 or higher. In some embodiments, the white light-emitting device can additionally be operable to produce white light with a CRI (R9) of 90 or higher.

[0020] In some embodiments, the weight ratio of the red-emitting manganese-activated fluoride phosphor (e.g., potassium hexafluorosilicate phosphor) to the yellow-to-green-emitting phosphor is greater than 50% and more typically between about 70% and about 90% or about 85%.

[0021] According to another embodiment of the present invention, a white light-emitting device comprises: a solid-state light emitter operable to generate blue light having a main wavelength in the range of 440 nm to 470 nm; a yellow-to-green-emitting phosphor excited by the blue light and operable to emit light having a peak emission wavelength in the range of 500 nm to 575 nm; and a red-emitting manganese-activated potassium hexafluorosilicate phosphor (K2SiF6:Mn 4+ ), excited by the blue light and operable to emit light having a peak emission wavelength between about 631 nm and about 632 nm; and an orange-to-red-emitting phosphor excited by the blue light and operable to generate light having a peak emission wavelength in the range of 575 nm to 620 nm, wherein the device is operable to generate white light having a correlated color temperature between 2700 K and 3000 K, a general color rendering index (Ra) of 90 or higher, and a color rendering index (R9) of 90 or higher.

[0022] The white light-emitting device may further comprise a light-transmitting material having a refractive index of 1.40 to 1.43, which comprises a mixture of a yellow-to-green-emitting phosphor, a red-emitting manganese-activated potassium hexafluorosilicate phosphor, and an orange-to-red-emitting phosphor.

[0023] The yellow-to-green-emitting phosphor comprises a cerium-activated green-emitting aluminate phosphor, such as a cerium-activated yttrium aluminate (YAG) phosphor; a cerium-activated lutetium aluminate (LuAG) phosphor or a silicate phosphor. [[ID=!]]

[0024] The orange-to-red-emitting phosphor comprises any blue-light-excitable phosphor that emits phosphor light having a peak emission wavelength in the range of 580 nm to 620 nm. In some embodiments, the orange-emitting phosphor comprises an europium-activated silicon nitride phosphor such as CASN(1-1-1-3) or 2-5-8 silicon nitride phosphor, which has a general crystal structure of M′2Si5N8:Eu, where M is at least one of Mg, Ca, Sr, Ba, and Zn.

[0025] In an embodiment, the CASN phosphor may be represented by the chemical formula (Ca 1-x Sr x )AlSiN3:Eu, where 0.5 < x ≤ 1. In an embodiment, the 2-5-8 silicon nitride phosphor may be represented by the chemical formula Ba 2-x Sr xSi5N8:Eu represents, wherein 0≤x≤2. Preferably, the orange light emitting phosphor generates light with a peak emission wavelength in the range of 590nm to 610nm.

[0026] According to another embodiment of the present invention, a white light emitting device includes: a solid-state light emitter operable to generate blue light having a dominant wavelength in the range of 440 nm to 470 nm; a yellow to green light emitting phosphor excitable by blue light and operable to emit light having a peak emission wavelength in the range of 500 nm to 550 nm and selected from the group consisting of: a cerium-activated yttrium garnet phosphor and a cerium-activated lutetium garnet phosphor; a red light emitting manganese-activated potassium hexafluorosilicate phosphor (K2SiF6:Mn 4 + ), which can be excited by blue light and can be operated to emit light with a peak emission wavelength between 631 nm and 632 nm; and an orange to red luminescent europium-activated silicon nitride phosphor, which can be excited by blue light and can be operated to produce light with a peak emission wavelength in the range of 575 nm to 620 nm.

[0027] In one embodiment, the white light emitting device is operable to generate a correlated color temperature between 2700K and 3000K and a CRI (R a ) is 90 or higher. In some embodiments, the white light emitting device is further operable to generate white light with a CRI (R9) of 90 or higher.

[0028] According to yet another embodiment, a white light emitting device includes: a solid state light emitter operable to generate blue light having a dominant wavelength in the range of 440 nm to 470 nm; a yellow to green luminescent cerium-activated lutetium aluminate phosphor that can be excited by blue light and is operable to emit light having a peak emission wavelength in the range of 500 nm to 550 nm; and a red luminescent manganese-activated potassium hexafluorosilicate phosphor (K2SiF6:Mn 4+ ), which can be excited by blue light and is operable to emit light with a peak emission wavelength between 631 nm and 632 nm; and Ba 2-x Sr x An orange to red luminescent europium-activated silicon nitride phosphor represented by Si5N8:Eu (where 0≤x≤2) can be excited by blue light and can be operated to produce light with a peak emission wavelength in the range of 590nm to 620nm, and wherein the device is operable to produce white light with a correlated color temperature between 2700K and 3000K and a color rendering index (Ra) of 90 or higher.

[0029] According to yet another embodiment, a white light emitting device includes: a solid state light emitter operable to generate blue light having a dominant wavelength in the range of 440 nm to 470 nm; a yellow to green light emitting phosphor excitable by blue light and operable to emit light having a peak emission wavelength in the range of 500 nm to 575 nm; and a red light emitting manganese activated potassium hexafluorosilicate phosphor (K2SiF6:Mn 4 + ), which can be excited by blue light and is operable to emit light with a peak emission wavelength between 631 nm and 632 nm; and an orange to red emitting phosphor, which can be excited by blue light and is operable to produce light with a peak emission wavelength in the range of 575 nm to 600 nm, wherein the device is operable to produce white light with a correlated color temperature between about 2700 K and about 3000 K, and wherein within the wavelength range of 460 nm to 600 nm, the maximum deviation of the light intensity emitted by the device (normalized to CIE 1931 XYZ relative luminance Y=100) compared to the light intensity of a blackbody curve of the same correlated color temperature (normalized to CIE 1931 XYZ relative luminance Y=100) is less than 0.3.

[0030] It is possible that within the wavelength range of 460nm to 500nm, the maximum deviation of the light intensity emitted by the device (normalized to CIE 1931 XYZ relative luminance Y=100) compared to the light intensity of the blackbody curve of the same correlated color temperature (normalized to CIE 1931 XYZ relative luminance Y=100) is less than 0.2.

[0031] Furthermore, it is possible that, within the wavelength range of 500 nm to 570 nm, the maximum deviation of the light intensity emitted by the device (normalized to CIE 1931 XYZ relative luminance Y=100) compared to the light intensity of the blackbody curve of the same correlated color temperature (normalized to CIE 1931 XYZ relative luminance Y=100) is less than 0.1.

[0032] Preferably, the white light emitting device is operable to produce white light having a typical CRI (Ra) of 90 or higher and a CRI (R9) of 90 or higher.

[0033] According to another aspect of the present invention, a photoluminescent compound comprises a light-transmitting material (encapsulant) having a refractive index of 1.40 to 1.43, comprising a mixture of a yellow- to green-emitting phosphor having a peak emission wavelength in the range of 500 nm to 575 nm and a red-emitting manganese-activated fluoride phosphor having a refractive index of approximately 1.4. Typically, the mixture of the yellow- to green-emitting and red-emitting manganese-activated fluoride phosphors is incorporated (dispersed) into the light-transmitting material and is uniformly distributed throughout the light-transmitting material.

[0034] In one embodiment, the red-light emitting manganese-activated fluoride phosphor comprises a red-light emitting manganese-activated potassium hexafluorosilicate phosphor, which may be composed of the chemical formula K2SiF6:Mn 4+ Representative. K2SiF6:Mn 4+ It is expected that the present invention may be useful with other red-light emitting manganese-activated fluoride phosphors having a refractive index of about 1.4, and it is believed that manganese-activated fluoride phosphors having these properties may include K2TiF6:Mn 4+ 、K2SnF6:Mn 4+ 、Na2TiF6:Mn 4+ 、Na2ZrF6:Mn 4+ 、Cs2SiF6:Mn 4+ 、Cs2TiF6:Mn 4+ 、Rb2SiF6:Mn 4+ 、Rb2TiF6:Mn 4+ 、K3ZrF7:Mn 4+ 、K3NbF7:Mn 4+ 、K3TaF7:Mn 4 + 、K3GdF6:Mn 4+ 、K3LaF6:Mn 4+ and K3YF6:Mn 4+ .

[0035] In some embodiments, the light-transmitting material includes a methyl-based silicone, such as dimethylsiloxane or polydimethylsiloxane.

[0036] The yellow to green emitting phosphor may comprise any phosphor that can be excited by blue light and is operable to emit light with a peak wavelength of 500 nm to 575 nm. For general lighting applications, the yellow to green emitting phosphor comprises a cerium-activated garnet phosphor. Alternatively and / or in addition, the yellow to green emitting phosphor may comprise a europium-activated silicate phosphor represented by the chemical formula A2SiO4:Eu, wherein A is at least one of Mg, Ca, Sr, Ba, and combinations thereof. For display backlight applications, the yellow to green emitting phosphor comprises a narrow-band green emitting phosphor, preferably a europium-activated β-SiAlON phosphor or a europium-activated sulfide phosphor represented by the general formula SrGa2S4:Eu.

[0037] For general lighting applications, the photoluminescent compound may further comprise an orange to red emitting phosphor having a peak emission wavelength in the range of 580 nm to 620 nm, and wherein the light-transmitting material comprises a mixture of a yellow to green emitting phosphor, a red emitting manganese-activated fluoride phosphor, and an orange to red emitting phosphor.

[0038] The orange-to-red light-emitting phosphors comprise europium-activated silicon nitride-based phosphors.

[0039] The present invention has particular utility when the weight ratio of the red light-emitting manganese-activated potassium hexafluorosilicate phosphor to the yellow-to-green light-emitting phosphor is greater than 50% and more typically between 70% and 90% or about 85%.

[0040] According to an embodiment of the present invention, a display backlight comprises: a solid-state light emitter operable to produce blue light; a narrow-band green light-emitting phosphor excited by the blue light and operable to produce light having a peak emission wavelength of about 535 nm; a red light-emitting manganese-activated potassium hexafluorosilicate phosphor; and a light-transmissive material having a refractive index of 1.40 to 1.43, comprising a mixture of the narrow-band green light-emitting phosphor and the red light-emitting manganese-activated potassium hexafluorosilicate phosphor. In an embodiment, the narrow-band green light-emitting phosphor may comprise a europium-activated β-SiAlON phosphor represented by the chemical formula M x Si 12-(m+n) Al m+n O n N 16-n [[ID=], where M is at least one of Mg, Ca, Sr, and combinations thereof, 0.01 < x < 0.1, 0.01 < m < 0.12, and 0.1 < n < 0.5. In another embodiment, the narrow-band green light-emitting phosphor may comprise a europium-activated sulfide phosphor represented by the general formula SrGa2S4:Eu.

[0041] In various embodiments of the present invention, a mixture of phosphors or photoluminescent compounds may be provided as part of an LED package, typically on an LED chip or remote from the solid-state light emitter. In a remote phosphor configuration, the mixture of phosphors is provided in an optical component positioned remote from the LED, typically separated from the LED by an air gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] To better understand the present invention, the LED-based white light-emitting devices and photoluminescent compounds of the present invention will now be described by way of example only with reference to the accompanying drawings, in which like reference numerals are used to represent like parts, and in which:

[0043] Figure 1 is a schematic diagram of an LED-based white light-emitting device according to an embodiment of the present invention;

[0044] Figure 2 is a graph of the luminous flux of LED-based white light-emitting devices against CIE x, in which a) the phosphors are incorporated as a mixture into a phenyl-based silicone and b) the phosphors are incorporated as a mixture into a dimethyl-based silicone;

[0045] Figure 3is the emission spectrum of the LED-based white light emitting device according to an embodiment of the present invention;

[0046] Figure 4 is the emission spectrum of the LED-based white light emitting device (device 11) according to an embodiment of the present invention;

[0047] Figure 5 is the emission spectrum of the LED-based white light emitting device (device 12) according to an embodiment of the present invention;

[0048] Figure 6 is the emission spectrum of the LED-based white light emitting device (device 13) according to an embodiment of the present invention;

[0049] Figure 7 , Normalized intensity (normalized to CIE 1931 XYZ relative brightness Y=100) versus wavelength for (i) device 14 (solid line), (i) device 15 (dashed line), and (i) the Plankian locus at a CCT of 2700K (dashed line);

[0050] Figure 8 , for devices 14 and 15, normalized intensity deviation from the blackbody curve (2700K) (normalized to CIE 1931XYZ relative luminance Y=100) versus wavelength;

[0051] Figure 9 is the emission spectrum of the LED-based white light emitting device display backlight (device 16) of an embodiment of the present invention; and

[0052] Figure 10 is the emission spectrum of the LED-based white light emitting device display backlight (device 17) according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] Figure 1 FIG2 is a schematic diagram of a white light emitting device 10 according to an embodiment of the present invention. The device 10 is configured to generate warm white light having a CCT (correlated color temperature) of approximately 2700K and a typical CRI (color rendering index) CRI (Ra) of 90 and above.

[0054] Device 10 includes one or more blue-light-emitting GaN (gallium nitride)-based LED chips 12 housed within a package 14. The one or more LED chips are operable to generate blue light having a dominant wavelength in the range of 440 nm to 470 nm, typically 450 nm to 455 nm. The package, which may, for example, comprise a surface-mounted device (SMD), such as an SMD 5630 LED package, includes upper and lower body portions 16 and 18. Upper body portion 16 defines a recess 20 configured to receive one or more LED chips 12. The package further includes electrical connectors 22 and 24 on the base that are electrically connected to corresponding electrode contact pads 26 and 28 on the bottom layer of recess 20. The LED chips 12 can be mounted to a thermal pad 30 located on the bottom layer of recess 20 using adhesive or solder. Thermal pad 30 is thermally connected to a thermal pad 32 on the package base. The electrode pads of the LED chip are electrically connected to corresponding electrode contact pads 26 and 28 on the bottom layer of the package using bonding wires 34 and 36. The recess 20 is completely filled with transparent silicone 38, which is loaded with a mixture of yellow- to green-emitting phosphors, orange- to red-emitting phosphors, and a red-emitting manganese-activated fluoride phosphor. This covers the exposed surface of the LED chip 12 with the phosphor / silicone material mixture. To enhance the device's emission brightness, the walls of the recess 20 are sloped and have a light-reflecting surface.

[0055] The red light emitting manganese activated fluoride phosphor comprises a phosphor of the chemical formula K2SiF6:Mn 4+ Representative potassium hexafluorosilicate phosphors, which can be excited by blue excitation light and can be operated to produce a peak emission wavelength λ p The wavelength of the red light is about 631 nm to about 632 nm. An example of such a phosphor is NR6931 KSF phosphor from Intematix Corporation, Fremont, California, USA, which has a peak emission wavelength of 632 nm. For simplicity, the manganese-activated potassium hexafluorosilicate phosphor and K2SiF6:Mn 4+ The phosphor is called "KSF".

[0056] The yellow to green emitting phosphor comprises a phosphor that can be excited by blue light and can be operated to produce a peak emission wavelength λ p Any phosphor that emits light in the range of 500nm to 575nm, and may include, for example, silicate-based phosphors, garnet-based phosphors, such as YAG or LuAG phosphors. Examples of such phosphors are given in Table 1.

[0057]

[0058] In one embodiment, the yellow to green emitting phosphor comprises a green emitting LuAG-based phosphor as taught in U.S. Pat. No. 8,529,791, entitled “Green-Emitting, Garnet-Based Phosphors in General and Backlighting Applications,” which is incorporated herein by reference in its entirety. Such a green emitting phosphor comprises a cerium-activated green emitting lutetium aluminate phosphor composed of lutetium, cerium, at least one alkaline earth metal, aluminum, oxygen, and at least one halogen, wherein the phosphor is configured to absorb excitation radiation having a wavelength in the range of about 380 nm to about 480 nm and emit a peak emission wavelength λ p Light in the range of about 500 nm to about 550 nm. An example of such a phosphor is GAL540 phosphor from Intermatrix, Inc., Fremont, California, USA, which has a peak emission wavelength of 540 nm.

[0059] The orange to red emitting phosphor comprises a phosphor that can be excited by blue light and is operable to emit a peak emission wavelength λ p Any phosphor that emits light in the range of 580 nm to 620 nm and may include, for example, europium-activated silicon nitride-based silicate phosphors or α-SiAlON phosphors. Examples of such orange to red emitting phosphors are given in Table 2. In one embodiment, the orange emitting phosphor comprises a red emitting phosphor as taught in U.S. Patent No. 8,597,545, entitled "Red-Emitting Nitride-Based Calcium-Stabilized Phosphors," which is incorporated herein by reference in its entirety. Such a red emitting phosphor comprises a phosphor of formula M a Sr b Si c Al d N e Eu fRepresentative nitride-based compositions, wherein: M is Ca, and 0.1 ≤ a ≤ 0.4; 1.5 < b < 2.5; 4.0 ≤ c ≤ 5.0; 0.1 ≤ d ≤ 0.15; 7.5 < e < 8.5; and 0 < f < 0.1; wherein a + b + f > 2 + d / v and v is the valence of M. Alternatively, the red-emitting phosphor comprises a red-emitting nitride-based phosphor as taught in U.S. Patent No. 8,663,502, titled "Red-Emitting Nitride-Based Phosphors," which is hereby incorporated by reference in its entirety. This red-emitting phosphor comprises a nitride-based composition represented by the chemical formula M (x / v) M′2Si 5-x Al x N8:RE, wherein: M is at least one monovalent, divalent, or trivalent metal having a valence v; M′ is at least one of Mg, Ca, Sr, Ba, and Zn; and RE is at least one of Eu, Ce, Tb, Pr, and Mn; wherein x satisfies 0.1 ≤ x < 0.4, and wherein the red-emitting phosphor has a general crystalline structure of M′2Si5N8:RE, Al substitutes for Si within the general crystalline structure, and M is substantially located at interstitial sites within the general crystalline structure. An example of such a phosphor is the XR600 red nitride phosphor from Intematix Corporation, Fremont, California, USA, which has a peak emission wavelength of 600 nm.

[0060]

[0061]

[0062] According to an embodiment of the present invention, the materials incorporated into the phosphor material mixture include a light-transmissive material having a refractive index of n = 1.40 to 1.43. For example, the light-transmissive material includes dimethyl-based silicone, such as polydimethylsiloxane (PDMS). An example of such a suitable silicone material is the OE-6370HF optical encapsulant from Dow Corning Corporation.

[0063] Figure 2 is a graph of the luminous flux of the LED-based white light-emitting device of the present invention versus CIE x (■ designates dimethyl silicone OE-6370HF). The change in CIE x is caused by different loadings of the phosphor mixture within the silicone. For comparison, data for the same device in which the same phosphor mixture is incorporated into a phenyl-based silicone are shown (◆ designates phenyl silicone). The phenyl-based silicone used in these devices is the OE-6650 optical encapsulant from Dow Corning Corporation. Phenyl-based silicone encapsulants are commonly used to encapsulate phosphors within LED devices.

[0064] Figure 2 The use of dimethyl-based silicone as the phosphor encapsulant was shown to increase the luminous flux of the device by approximately 10% compared to the same device using phenyl-based silicone as the phosphor encapsulant. The increase in luminous flux is believed to be caused by the lower refractive index of dimethyl-based silicone (n≈1.4) compared to the refractive index of phenyl-based silicone (n≈1.54). It is believed that this lower refractive index increases the absorption of light from the phosphor particles (K2SiF6:Mn) by reducing total internal reflection at the interface of the phosphor particles and the surrounding optical medium (silicone). 4+ -n=1.3991) of a red-light emitting manganese-activated potassium hexafluorosilicate (KSF) phosphor. For comparison, the refractive index of other phosphors (including yellow to green-emitting LuAG and orange-emitting nitrides) is typically around 1.8, which may facilitate the widespread use of phenyl-based silicone encapsulants in LED-based light-emitting devices. It is expected that the use of dimethyl-based silicones will have a detrimental effect on light emission from phosphors other than red-light emitting manganese-activated potassium hexafluorosilicate phosphor (KSF) and reduce the overall performance of the device. However, as Figure 2 As shown, when a red-emitting manganese-activated fluoride phosphor is used in combination with other phosphors, the net result is an increase in luminous flux. It was found that the increase in luminous flux was greater when the majority (i.e., greater than 50% by weight) of the total phosphor was a red-emitting manganese-activated fluoride phosphor. In other embodiments, yellow- to green-emitting, orange- to red-emitting (when present), and KSF phosphors can be incorporated as a mixture into other light-transmitting materials (e.g., light-transmitting epoxy resins) having a refractive index of about 1.40 to about 1.43.

[0065] Device 1: White light emitting device with CCT 2700K and CRI (Ra) ≥ 90

[0066] Tables 3A and 3B tabulate details of a white light emitting device, designated Device 1, configured to produce white light having a nominal CCT of 2700K and a typical CRI (Ra) of 90 and higher.

[0067]

[0068] Device 1 included an SMD 5630 LED package containing a single 451 nm GaN LED chip and a mixture of two phosphors: (i) a yellow-to-green emitting phosphor (Intermatrix's NYAG4454 cerium-activated green-emitting YAG phosphor) and (ii) a red-emitting manganese-activated fluoride phosphor (Intermatrix NR6931 KSF). The phosphor mixture was incorporated into a dimethyl-based silicone (Dow Corning OE-6370HF Optical Encapsulant) and evenly distributed throughout. The proportion of KSF phosphor in the total phosphor weight was 86.5 wt%, with the remaining 13.5 wt% being NYAG4454 (Table 3B).

[0069]

[0070] Table 3C tabulates the optical characteristics of a white light emitting device (Device 1). As can be seen from the table, the device produces white light with a CCT of ≈ 2700K, a typical CRI (Ra) of 90 and above, and a CRI (R9) greater than 90. Furthermore, as can be seen from Table 3C, Device 1 has a luminous efficacy (LE) of 335 lm / W.

[0071]

[0072] Devices 2 to 10: White light emitting devices with a CCT of 2700K and a CRI (Ra) ≥ 95

[0073] Table 4A tabulates details of various white light emitting devices, designated Devices 2 through 10. Devices 2 through 10 are nominally identical devices and are each configured to produce white light with a nominal CCT of 2700K and a typical CRI (Ra) of 95 and higher.

[0074]

[0075] Each device consisted of an SMD 5630 LED package containing a single 451 nm GaN LED chip and a blend of three phosphors: (i) a yellow- to green-emitting phosphor (Intermetallic's GAL540 cerium-activated green-emitting LuAG phosphor), (ii) a red-emitting manganese-activated fluoride phosphor (Intermetallic's NR6931 KSF), and (iii) an orange- to red-emitting phosphor (Intermetallic's XR600 nitride-based phosphor). The phosphor mixture was incorporated into a dimethyl-based silicone (Dow Corning OE-6370HF optical encapsulant) and evenly distributed throughout. The proportion of red phosphor (XR600 + KSF) was 85 wt% of the total phosphor weight, with the remaining 15 wt% being GAL540 (Table 4A). The proportion of KSF was 82 wt% and the proportion of XR600 was 3 wt%.

[0076] Table 4B tabulates the optical characteristics of white light emitting devices (Devices 2-10). As can be seen from the table, each device produces white light with a CCT of ≈ 2700K, a typical CRI (Ra) of 95 and above, and a CRI (R9) greater than 92. Furthermore, as can be seen from Table 4B, the luminous efficacy (LE) of these devices ranges from 334 lm / W to 339 lm / W, with an average LE of 335 lm / W.

[0077] Figure 3 is the emission spectrum of one of the devices in Table 4B.

[0078]

[0079] Tables 5A and 5B tabulate details of various white light emitting devices designated as Devices 11 (reference), 12, and 13. Each device was configured to produce warm white light with a CCT of approximately 3000K and included an SMD 2835 LED package containing a single 451 nm GaN LED chip.

[0080]

[0081]

[0082] Device 11 (reference) contained a mixture of two phosphors: (i) a yellow-to-green emitting phosphor (Intermetallic's GAL535 cerium-activated green-emitting LuAG phosphor) and (ii) a red-emitting manganese-activated fluoride phosphor (Intermetallic's NR6931 KSF). The phosphor mixture was incorporated into a dimethyl-based silicone (Dow Corning OE-6370 HF Optical Encapsulant) and evenly distributed throughout. The proportion of KSF in the total phosphor weight was 82 wt%, with the remaining 18 wt% being GAL535 (Table 5B).

[0083]

[0084] Device 12 contained a mixture of three phosphors: (i) a yellow- to green-emitting phosphor (Intermetallic's GAL540 cerium-activated green-emitting LuAG phosphor), (ii) a red-emitting manganese-activated fluoride phosphor (Intermetallic's NR6931KSF), and (iii) an orange- to red-emitting phosphor (Intermetallic's XR600 nitride-based phosphor). The phosphor mixture was incorporated into a dimethyl-based silicone (Dow Corning OE-6370HF optical encapsulant) and uniformly distributed throughout. The proportion of red phosphor (XR600 + KSF) was 76.5 wt% of the total phosphor weight, with the remaining 23.5 wt% being GAL540 (Table 5B). The proportion of KSF was 73.5 wt% and the proportion of XR600 was 3 wt%.

[0085] Device 13 contained a mixture of three phosphors: (i) a yellow- to green-emitting phosphor (Intermetallic's GAL540 cerium-activated green-emitting LuAG phosphor), (ii) a red-emitting manganese-activated fluoride phosphor (Intermetallic's NR6931KSF), and (iii) an orange- to red-emitting phosphor (Intermetallic's XR600 nitride-based phosphor). The phosphor mixture was incorporated into a phenyl-based silicone (Dow Corning OE-6636 Optical Encapsulant) and uniformly distributed throughout. The proportion of red phosphor (XR600 + KSF) was 78 wt% of the total phosphor weight, with the remaining 22 wt% being GAL540 (Table 5B). The proportion of KSF was 75 wt% and the proportion of XR600 was 3 wt%.

[0086] Table 5C tabulates the optical characteristics of devices 11 (reference), 12, and 13, and Figure 4 、 5 6 show the emission spectra of devices 11 (reference), 12, and 13, respectively.

[0087] The benefits of including a third phosphor (i.e., an orange to red emitting phosphor) in addition to the yellow to green emitting and KSF phosphors are demonstrated by comparing the optical characteristics of devices 11 (reference) and 12 (Table 5C). It can be seen that including the third orange to red emitting phosphor increases brightness by ≈9%, increases the typical CRI (Ra) from ≈69 to ≈95, and increases the CRI (R9) from ≈7 to ≈93. In summary, the benefits of including a third phosphor (i.e., an orange to red emitting phosphor) can be an increase in brightness, an increase in the typical CRI (Ra), and an increase in the CRI (R9).

[0088]

[0089] The benefits of encapsulating the three-phosphor blend in dimethyl silicone (more specifically, a light-transmitting material with a refractive index n≈1.40 to 1.43) compared to encapsulating the three-phosphor blend in phenyl silicone can be determined by comparing the optical characteristics of Device 12 and Device 13 (Table 5C). As can be seen, the use of dimethyl silicone increases brightness by ≈2.5% (i.e., from 105.2% to 108.7%). As discussed above, the use of dimethyl silicone is believed to increase light extraction from the light generated by the KSF phosphor, which may lead to an increase in luminous efficacy (LE). While overall phosphor usage can be increased when using dimethyl silicone (110 g / 100 g silicone for Device 12 versus 83 g / 100 g silicone for Device 13), the substantial increases in brightness, general CRI (Ra), and CRI (R9) may far outweigh any additional cost increases.

[0090] Devices 14 (reference) and 15: White light emitting devices with a CCT of 2700K

[0091] To further illustrate and explain the benefits of using three phosphor solutions and a phosphor encapsulant with a refractive index of n = 1.40 to 1.43, two other devices are now discussed, namely Device 14 (reference) and Device 15. Tables 6A and 6B tabulate the details of the white light emitting devices Device 14 (reference) and Device 15. Each device is configured to produce warm white light with a CCT of 2700K and includes an SMD 5630 LED package containing a single 451nm GaN LED chip.

[0092]

[0093] Device 14 (reference) contained a mixture of two phosphors: (i) a yellow-to-green emitting phosphor (Intermetallic's GAL535 cerium-activated green-emitting LuAG phosphor) and (ii) a red-emitting manganese-activated fluoride phosphor (Intermetallic's NR6931 KSF). The phosphor mixture was incorporated into and uniformly distributed throughout a phenyl-based silicone (Dow Corning OE-6336 Optical Encapsulant). The proportion of KSF in the total phosphor weight was 82 wt%, with the remaining 18 wt% being GAL535 (Table 6B).

[0094]

[0095] Device 15 includes a mixture of three phosphors: (i) a yellow- to green-emitting phosphor (Intermetallic's GAL540 cerium-activated green-emitting LuAG phosphor), (ii) a red-emitting manganese-activated fluoride phosphor (Intermetallic's NR6931KSF), and (iii) an orange- to red-emitting phosphor (Intermetallic's XR600 nitride-based phosphor). The phosphor mixture was incorporated into a dimethyl-based silicone (Dow Corning OE-6370HF optical encapsulant) and evenly distributed throughout. The proportion of red phosphor (XR600 + KSF) was 76.5 wt% of the total phosphor weight, with the remaining 23.5 wt% being GAL540 (Table 6B). The proportion of KSF was 73.5 wt% and the proportion of XR600 was 3 wt%.

[0096] Table 6C tabulates the optical characteristics of devices 14 (reference) and 15. As can be seen, the combined effect of including the third orange-to-red-emitting phosphor and using a dimethyl silicone encapsulant resulted in a ≈12% increase in brightness, an increase in the typical CRI (Ra) from ≈70 to ≈95, an increase in the CRI (R9) from ≈17 to ≈90, and an increase in the luminous efficacy (LE) from ≈311 to ≈333.

[0097]

[0098]

[0099] Figure 7 Normalized intensity versus wavelength is shown for (i) device 14 (reference) (dashed line), (ii) device 15 (solid line), and (iii) a blackbody curve with a CCT of 2700 K (dashed line). To allow for a meaningful comparison of the spectra, each spectrum was normalized so that each had a CIE 1931 XYZ relative luminance Y = 100. The data was normalized using the CIE 1931 luminosity function y(λ) of a standard observer, which takes into account the observer's daylight visual response.

[0100] Planck curve or blackbody curve (dashed- Figure 7 ) represents a typical spectrum with a CRI (Ra) equal to 100. Therefore, in order for a white light emitting device to have the highest possible color rendering, its emission spectrum should match the blackbody spectrum as closely as possible.

[0101] refer to Figure 7 , it can be seen that the addition of an orange to red emitting phosphor and the use of an encapsulant with a refractive index closely matching that of the KSF phosphor results in an emission spectrum (solid line) that more closely matches the blackbody spectrum (dashed line) in three respects.

[0102] First, the green peak between about 500 nm and about 540 nm is reduced, causing the emission spectrum in this region (solid line) to more closely follow the blackbody curve (dashed line), as indicated by the cross-hatched region 50. It is hypothesized that the reduction in the green peak is caused by dimethyl silicone increasing light scattering and reducing light extraction from the yellow-to-green emitting phosphor.

[0103] Second, as indicated by the cross-hatched region 52, the valley between about 550 nm and about 610 nm has been filled by including the orange to red emitting phosphor so that the emission spectrum in this region (solid line) more closely follows the blackbody curve (dashed line).

[0104] Third, assuming the combined effect of including an orange to red emitting phosphor and using dimethyl silicone reduces the total amount of KSF phosphor, this reduces the KSF emission peaks 54, 56, 58, 60 (Device 14 (reference), 115g KSF / 100g silicone; Device 15, 81g KSF / 100g silicone), causing the emission spectrum in this region (solid line) to follow the blackbody curve (dashed line) more closely.

[0105] Figure 8 The intensity deviation normalized from the blackbody curve (2700K) of devices 14 (reference) and 15 (normalized to CIE 1931XYZ relative brightness Y=100) is plotted against wavelength. Figure 8It can be seen that within the wavelength range of 460 nm to 500 nm, the maximum deviation of the intensity of the light emitted by the device, normalized to the CIE 1931 XYZ relative luminance Y = 100, from the intensity of the blackbody curve is less than 0.2. Furthermore, within the wavelength range of 500 nm to 570 nm, the maximum deviation of the intensity of the light emitted by the device, normalized to the CIE 1931 XYZ relative luminance Y = 100, from the intensity of the blackbody curve is less than 0.1. Thus, it can be seen that the optimal effect is achieved within the wavelength range of 500 nm to 570 nm, where the emission spectrum of device 15 follows the blackbody curve very closely to an almost ideal state. Over the entire wavelength range of 460 nm to 600 nm, it can be seen that the maximum deviation of the intensity of the light emitted by the device, normalized to the CIE 1931 XYZ relative luminance Y = 100, from the intensity of the blackbody curve is less than 0.3.

[0106] Display backlight

[0107] Although the foregoing embodiments have been described with respect to generally high CRI white light emitting devices, embodiments of the present invention are also useful in white light emitting devices used as display backlights. More specifically, but not exclusively, embodiments of the present invention relate to display backlights for use in high color gamut liquid crystal displays (e.g., televisions, computer monitors, laptop computers, tablet computer devices, and smart phones). In the display backlight, the yellow to green light emitting phosphor includes a narrowband green phosphor having a peak emission wavelength corresponding to the green filter element of the display. Typically, in most liquid crystal displays, the peak emission wavelength is about 535 nm (± 2 nm). In this specification, a narrowband green light emitting phosphor refers to a phosphor having an emission peak with a FWHM (full width at half maximum) of about 50 nm or less. Examples of suitable narrowband phosphors are given in Table 7. In the backlight, the emission spectrum matches the color filter panel of the display, and the red, green, and blue components match the red, green, and blue filters. Therefore, there is no benefit in including an orange to red light emitting phosphor.

[0108]

[0109] Devices 16 and 17: Display backlight

[0110] Tables 8A and 8B tabulate details of various white light emitting devices, designated devices 16 and 17. Each device was configured for use as a display backlight and included an SMD 5630 LED package containing a single 452 nm GaN LED chip.

[0111]

[0112] Device 16 comprises a mixture of two phosphors: (i) a yellow to green emitting phosphor (peak emission wavelength λp The phosphors were prepared by combining (i) a narrow-band green-emitting β-SiAlON:Eu phosphor (e.g., a β-SiAlON:Eu phosphor with a wavelength of 535 nm) and (ii) a red-emitting manganese-activated fluoride phosphor (Intemet NR6931 KSF). The phosphor mixture was incorporated into a dimethyl-based silicone (Dow Corning OE-6370 HF Optical Encapsulant) and uniformly distributed throughout. The KSF ratio of the total phosphor weight was 82 wt%, with the remaining 18 wt% being β-SiAlON:Eu (Table 8B).

[0113]

[0114] Device 17 comprises a mixture of two phosphors: (i) a yellow to green emitting phosphor (narrow band green emitting sulfide phosphor: SrGa2S4:Eu, peak emission wavelength λ p =536 nm) and (ii) a red-emitting, highly activated fluoride phosphor (Intemet NR6931 KSF). The phosphor mixture was incorporated into a dimethyl-based silicone (Dow Corning OE-6370HF Optical Encapsulant) and uniformly distributed throughout. The KSF ratio of the total phosphor weight was 82 wt%, with the remaining 18 wt% being SrGa2S4:Eu (Table 8B).

[0115] Table 8C tabulates the optical characteristics of devices 16 and 17 and Figure 4 9 and 10 show the emission spectra of devices 16 and 17, respectively. As can be seen from Table 4C, devices 16 and 17 each produce light having a color gamut % of the NTSC (National Television System Committee) colorimetry 1953 (CIE 1931).

[0116]

[0117] Although the present invention has been described with particular reference to certain embodiments thereof, it will be readily apparent to those skilled in the art that changes and modifications in form and detail may be made without departing from the spirit and scope of the invention. For example, although the embodiments of the present invention have been described with respect to manganese-activated potassium hexafluorosilicate phosphor (KSF), it is contemplated that the present invention will be useful with other manganese-activated fluoride phosphors having a refractive index of about 1.4 (typically n≈1.39 to ≈1.43). Such manganese-activated fluoride phosphors having these properties are believed to include K2TiF6:Mn 4+ 、K2SnF6:Mn 4+ 、Na2TiF6:Mn 4+ 、Na2ZrF6:Mn 4+ 、Cs2SiF6:Mn 4+ 、Cs2TiF6:Mn4+ , Rb2SiF6:Mn 4+ , Rb2TiF6:Mn 4+ , K3ZrF7:Mn 4+ , K3NbF7:Mn 4+ , K3TaF7:Mn 4 + , K3GdF6:Mn 4+ , K3LaF6:Mn 4+ and K3YF6:Mn 4+ .

Claims

1. A white light emitting device comprising: A solid-state light emitter for generating blue light having a dominant wavelength in the range of 440 nm to 470 nm; A yellow to green light-emitting phosphor comprising a cerium-activated yttrium garnet phosphor or a cerium-activated lutetium garnet phosphor, wherein the yellow to green light-emitting phosphor is configured to generate light having a peak emission wavelength of 500 nm to 575 nm; an orange to red emitting phosphor for generating light having a peak emission wavelength in the range of 580 nm to 620 nm; a red-light-emitting manganese-activated complex fluoride phosphor for producing light having a peak emission wavelength between 631 nm and 632 nm; The white light emitting device is used to generate white light with a spectrum in the wavelength range of 460nm to 600nm, a correlated color temperature and a general color rendering index (Ra) of 90 or higher, and the maximum deviation between the light intensity of the light emitted by the white light emitting device normalized to CIE1931XYZ relative brightness Y=100 and the light intensity of the blackbody spectrum with the same correlated color temperature normalized to CIE1931XYZ relative brightness Y=100 is less than 0.

3.

2. The white light emitting device according to claim 1 , wherein within a wavelength range of 460 nm to 500 nm, a maximum deviation between the light intensity normalized to CIE1931XYZ relative luminance Y=100 of the light generated by the white light emitting device and the light intensity normalized to CIE1931XYZ relative luminance Y=100 of a blackbody spectrum having the same correlated color temperature is less than 0.

2.

3. The white light emitting device according to claim 1 or 2, wherein within the wavelength range of 500 nm to 570 nm, the maximum deviation between the light intensity normalized to CIE1931XYZ relative brightness Y=100 of the light generated by the white light emitting device and the light intensity normalized to CIE1931XYZ relative brightness Y=100 of a blackbody spectrum having the same correlated color temperature is less than 0.

1. 4 . The white light emitting device according to claim 1 , wherein the white light emitting device is configured to generate white light having a color rendering index (R9) of at least 90. 5 . The white light emitting device according to claim 1 , comprising a light-transmitting material comprising a yellow to green light emitting phosphor, an orange to red light emitting phosphor, and a red light emitting manganese-activated complex fluoride phosphor. 6 . The white light emitting device according to claim 1 , wherein the red light emitting manganese-activated complex fluoride phosphor comprises a manganese-activated potassium hexafluorosilicate phosphor.

7. The white light emitting device according to claim 1 or 2, wherein the orange to red light emitting phosphor comprises a pin-activated silicon nitride-based phosphor selected from (Ca 1-x Sr x )AlSiN3:Eu, where 0.5<x≤1, and Ba 2-x Sr x Si5N8:Eu, wherein at least one of 0≤x≤2. 8 . The white light emitting device according to claim 1 , wherein the orange to red light emitting phosphor is configured to generate light having a peak wavelength of 600 nm.

9. The white light emitting device according to claim 1 or 2, wherein the red light emitting manganese activated complex fluoride phosphor is selected from: K2SiF6:Mn 4+ , K2TiF6:Mn 4+ , K2SnF6:Mn 4+ , Na2TiF6:Mn 4+ , Na2ZrF6:Mn 4+ , Cs2SiF6:Mn 4 + , Cs2TiF6:Mn 4+ , Rb2SiF6:Mn 4+ , Rb2TiF6:Mn 4+ , K3ZrF7:Mn 4+ , K3NbF7:Mn 4+ , K3TaF7:Mn 4+ , K3GdF6:Mn 4+ , K3LaF6:Mn 4+ and K3YF6:Mn 4+ At least one of .

10. The white light emitting device according to claim 1 or 2, wherein the weight ratio of the red light emitting manganese activated complex fluoride phosphor to the yellow to green light emitting phosphor is greater than 50%. 11 . The white light emitting device according to claim 1 , wherein the weight ratio of the red-light emitting manganese-activated complex fluoride phosphor to the yellow to green-light emitting phosphor is between 70 wt % and 90 wt %.

Images