WO2017210080A1 - Substances luminescentes émettant de la lumière rouge et dispositifs associés - Google Patents

Substances luminescentes émettant de la lumière rouge et dispositifs associés Download PDF

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Publication number
WO2017210080A1
WO2017210080A1 PCT/US2017/034477 US2017034477W WO2017210080A1 WO 2017210080 A1 WO2017210080 A1 WO 2017210080A1 US 2017034477 W US2017034477 W US 2017034477W WO 2017210080 A1 WO2017210080 A1 WO 2017210080A1
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Prior art keywords
particles
phosphor
milling
precursor
manganese
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PCT/US2017/034477
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English (en)
Inventor
William Winder Beers
Jianmin He
Fangming Du
James Edward Murphy
William Erwin COHEN
Clark David NELSON
Cynthia Susan LINK
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General Electric Company
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Priority claimed from US15/171,098 external-priority patent/US10563121B2/en
Application filed by General Electric Company filed Critical General Electric Company
Priority to CA3037852A priority Critical patent/CA3037852A1/fr
Priority to CN201780034265.5A priority patent/CN109219646B/zh
Priority to JP2018562551A priority patent/JP7036745B2/ja
Publication of WO2017210080A1 publication Critical patent/WO2017210080A1/fr

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    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09KMATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/61Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing fluorine, chlorine, bromine, iodine or unspecified halogen elements
    • C09K11/615Halogenides
    • C09K11/616Halogenides with alkali or alkaline earth metals
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09KMATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/61Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing fluorine, chlorine, bromine, iodine or unspecified halogen elements
    • C09K11/617Silicates
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Definitions

  • Red-emitting phosphors based on complex fluoride materials activated by Mn 4+ can be utilized in combination with yellow/green emitting phosphors such as YAG:Ce or other garnet compositions to achieve warm white light (CCTs ⁇ 5000 K on the blackbody locus, color rendering index (CRI) >80) from a blue light emitting diode (LED), equivalent to that produced by current fluorescent, incandescent and halogen lamps.
  • These materials absorb blue light strongly and efficiently emit between about 610-635 nm with little deep red/NIR emission. Therefore, luminous efficacy is maximized compared to red phosphors that have significant emission in the deeper red where eye sensitivity is poor. Quantum efficiency can exceed 85% under blue (440-460 nm) excitation.
  • a process for synthesizing a manganese (Mn 4+ ) doped phosphor is provided.
  • a phosphor precursor of formula I (below) is milled to a desired or designated particle size and then contacted with a fluorine-containing oxidizing agent at an elevated temperature to form the Mn4+ doped phosphor
  • A represents Li, Na, K, Rb, Cs, or a combination thereof
  • M represents Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof
  • x has a value of the absolute value of the charge of the [MF y ] ion
  • y has a value of 5, 6 or 7.
  • Mn 4+ doped phosphors that may be produced by the process are provided, and lighting apparatuses and backlight devices that include the Mn 4+ doped phosphors are provided.
  • a method for synthesizing a manganese (Mn 4+ ) doped phosphor includes milling particles of a phosphor precursor of formula A x [MF y ]:Mn 4+ , where A includes one or more of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), or cesium (Cs), M includes one or more of silicon (Si), germanium (Ge), tin (Sn), titanium (Ti), zirconium (Zr), aluminum (Al), gallium (Ga), indium (In), scandium (Sc), hafnium (Hf), yttrium (Y), lanthanum (La), niobium (Nb), tantalum (Ta), bismuth (Bi), or gadolinium (Gd), x has a value of an absolute value of a charge on an ion of [MF y ], and y has a value of at least five and no greater than seven.
  • A includes one or more of
  • the method also can include annealing the particles that are milled by contacting the particles with a fluorine-containing oxidizing agent and treating surfaces of the particles that are annealed by contacting the particles with a saturated solution of a compound of formula B x [M'F y ] in aqueous hydrofluoric acid, where B includes one or more of Na, K, Rb, or Cs and M' includes one or more of Si, Ge, or Ti.
  • the method also can include annealing the particles subsequent to treating the surfaces of the particles by contacting the particles with the fluorine-containing oxidizing agent.
  • a manganese doped complex fluoride phosphor prepared by this process, a lighting apparatus and/or a backlight device including such a phosphor are provided.
  • a method includes obtaining particles of a phosphor precursor of formula A x [MF y ]:Mn 4+ , where A includes one or more of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), or cesium (Cs), wherein M includes one or more of silicon (Si), germanium (Ge), tin (Sn), titanium (Ti), zirconium (Zr), aluminum (Al), gallium (Ga), indium (In), scandium (Sc), hafnium (Hf), yttrium (Y), lanthanum (La), niobium (Nb), tantalum (Ta), bismuth (Bi), or gadolinium (Gd), x has a value of an absolute value of a charge on an ion of [MF y ], and y has a value of at least five and no greater than seven.
  • A includes one or more of lithium (Li), sodium (Na), potassium (K), rubidium (Rb
  • the method also includes reducing sizes of the particles of the phosphor precursor by wet milling the particles and annealing the particles that are wet milled by contacting the particles with a fluorine-containing oxidizing agent. Additionally, a manganese doped complex fluoride phosphor prepared by this method is provided. A lighting apparatus and backlight device that include manganese-doped phosphor prepared by this method also are provided.
  • a method includes obtaining particles of a K2SiF 6 :Mn 4+ phosphor precursor, reducing sizes of the particles of the phosphor precursor by wet milling the particles, and annealing the particles that are wet milled by contacting the particles with a fluorine- containing oxidizing agent. Additionally, a manganese doped complex fluoride phosphor prepared by this method is provided. A lighting apparatus and backlight device that include manganese- doped phosphor prepared by this method also are provided.
  • Figure 1 is a schematic cross-sectional view of a lighting apparatus in accordance with one embodiment of the inventive subject matter
  • Figure 2 is a schematic cross-sectional view of a lighting apparatus in accordance with another embodiment of the inventive subject matter
  • Figure 3 is a schematic cross-sectional view of a lighting apparatus in accordance with another embodiment of the inventive subject matter
  • FIG. 5 is a schematic perspective view of a surface-mounted device (SMD) backlight LED
  • Figure 6 illustrates a flowchart of one embodiment of a method for providing phosphor particles
  • Figure 7 schematically illustrates another example of milling the phosphor precursor powders or particles
  • Figure 8 illustrates a flowchart of yet another embodiment of a method for providing phosphor particles
  • Figures 9-12 are scanning electron microscope (SEM) images of various samples of phosphor particles using a secondary electron mode.
  • Approximating language may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” is not limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value.
  • the singular forms "a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
  • a phosphor precursor is milled into particles followed by treating the milled particles to enhance performance and stability (e.g., quantum efficiency, thermal stability, humidity stability, and/or light flux stability) of a resulting Mn 4+ doped phosphor.
  • the phosphor precursor is milled (or ground) to reduce particle size for desired properties. For example, as the particle size of the phosphor is reduced, the sedimentation rate (or settling rate) of the particles in an encapsulant material (for example, silicone) decreases.
  • the sedimentation rate of the particles can be tuned to match, be slower or be faster than other phosphors in a blend, and thus enables control over the separation of phosphors.
  • the separation of phosphors can be beneficial to protect the Mn 4+ doped phosphors from damage caused by the excitation flux.
  • the amount and the location (closer or farther from an LED chip) of the phosphor particles can be controlled in order to achieve a desired color point.
  • small particle size D50 particle size less than 30 microns
  • the particle size may represent the largest outer dimension of a particle measured along a straight line (e.g., not a circumference or perimeter).
  • the phosphor precursor is a manganese (Mn 4+ )-doped complex fluoride material of formula I.
  • a complex fluoride material or phosphor includes a coordination compound, including at least one coordination center, surrounded by fluoride ions acting as ligands, and charge- compensated by counter ions as necessary.
  • the coordination center is Si and the counter ion is K.
  • Complex fluorides are occasionally written down as a combination of simple, binary fluorides but such a representation does not indicate the coordination number for the ligands around the coordination center.
  • the phosphor precursor can be synthesized by adding a first solution that includes one or more sources of potassium and a second solution that includes one or more sources of silicon to a container with a third solution that includes one or more sources of manganese.
  • the combined liquid formed by these solutions is stirred, and K2SiF 6 :Mn 4+ particles precipitate from the stirred mixture of the solutions as the phosphor precursor.
  • Particle size distribution of the formed K2SiF 6 :Mn 4+ particles are typically affected by processing factors like concentration of feedstock solutions, flow rates, stirring rate, surface condition of reactor and so on.
  • the precipitated particles of the phosphor precursor and remaining mixture of the solutions are discharged from the container and then filtered to separate the solid particles of the phosphor precursor from the liquid. These particles can then be rinsed in acetone and dried.
  • the coordination center of the precursor that is, M in formula I
  • the coordination center is Si, Ge, Sn, Ti, Zr, or a combination thereof. More particularly, the coordination center is Si, Ge, Ti, or a combination thereof, and the counter ion, or A in formula I, is Na, K, Rb, Cs, or a combination thereof, and y is 6.
  • precursors of formula I include K2[SiF 6 ]:Mn 4+ , K 2 [TiF 6 ]:Mn 4+ , K 2 [SnF 6 ]:Mn 4+ , Cs 2 [TiF 6 ]:Mn 4+ , Rb 2 [TiF 6 ]:Mn 4+ , Cs 2 [SiF 6 ]:Mn 4+ , Rb 2 [SiF 6 ]:Mn 4+ , Na 2 [TiF 6 ]:Mn 4+ , Na 2 [ZrF 6 ]:Mn 4+ , K 3 [ZrF 7 ]:Mn 4+ , K 3 [BiF 6 ]:Mn 4+ , K 3 [YF 6 ]:Mn 4+ , K 3 [LaF 6 ]:Mn 4+ , K 3 [GdF 6 ]:Mn 4+ , K 3 [NbF 7 ]:Mn 4+ , and/or K 3
  • the phosphor precursor can be milled by milling techniques such as planetary milling, attrition milling, ball milling, air jet milling, pulveriser techniques, or a combination thereof.
  • the phosphor precursor is ball milled.
  • Other milling (or grinding) techniques may be used, which provide reduced particle size (for example, a D50 particle size less than about 25 microns).
  • the milling is performed in a vacuum or in an inert environment.
  • the phosphor precursor can be also milled using a wet ball milling process using a saturated K 2 SiF 6 dissolved in HF solution in one embodiment to increase the reliability of phosphors created from the milled precursor (relative to using other milling or grinding techniques).
  • Milling or grinding particles of the phosphor precursor of formula I can be carried out for a selected period of time with a rotational speed that depends, in part, on the size of the particles before milling, along with the desired size of the resulting particles after milling.
  • the particles have a particle size distribution with a D50 value (or a D50 particle size) of less than about 30 microns after milling.
  • the D50 particle size of the milled particles ranges from about 10 microns to about 20 microns, and more particularly from about 12 microns to about 18 microns.
  • a liquid medium can be used for milling.
  • the liquid medium may include ketones, such as acetone, alcohols, esters, such as t-butyl acetate, water, acids, or mixtures thereof.
  • ketones such as acetone
  • alcohols such as t-butyl acetate
  • water such as water
  • acids such as acetone
  • Table 1 shows the drop in quantum efficiency of K2[SiF 6 ]:Mn 4+ (PFS) with time when milled with acetone.
  • the liquid medium that is used for milling the phosphor precursor can be formed from saturated K2S1F6 dissolved in a HF solution at room temperature, as described below.
  • the breaking of phosphor particles increases the susceptibility of these particles to hydrolysis and oxidation- reduction reactions with moisture in the air. This also can lower the performance of the phosphor.
  • the particles after milling, the particles are treated to enhance performance and stability (quantum efficiency, thermal stability, humidity stability, flux stability, and color stability) of the resulting Mn 4+ doped phosphor.
  • the milled particles are contacted with a fluorine-containing oxidizing agent in gaseous form at an elevated temperature.
  • the temperature at which the particles are contacted with the fluorine-containing oxidizing agent is any temperature in the range from about 200°C to about 700°C, particularly from about 350°C to about 600°C during contact, and in some embodiments from about 200°C to about 700°C. In various embodiments of the present invention, the temperature is at least 100°C, particularly at least 225°C, and more particularly at least 350°C.
  • the phosphor precursor particles are contacted with the oxidizing agent for a period of time sufficient to increase its performance and stability of the resulting phosphor. Time and temperature are interrelated, and may be adjusted together, for example, increasing time while reducing temperature, or increasing temperature while reducing time. In particular embodiments, the time is at least one hour, particularly for at least four hours, more particularly at least six hours, and most particularly at least eight hours.
  • the temperature may be reduced at a controlled rate while maintaining the oxidizing atmosphere for an initial cooling period.
  • the cooling rate may be controlled at the same or a different rate, or may be uncontrolled.
  • the cooling rate is controlled at least until a temperature of 200°C is reached.
  • the cooling rate is controlled at least until a temperature at which it is safe to purge the atmosphere is reached.
  • the temperature may be reduced to about 50°C before a purge of the fluorine atmosphere begins.
  • Reducing the temperature at a controlled rate of ⁇ 5°C per minute may yield a phosphor product having superior properties compared to reducing the temperature at a rate of 10°C/minute.
  • the rate may be controlled at ⁇ 5°C per minute, particularly at ⁇ 3°C per minute, more particularly at a rate of ⁇ 1°C per minute.
  • the fluorine-containing oxidizing agent may be A1F 3 , SbFs, CIF3, BrF 3 , KrF, XeF 2 ,
  • the fluorine-containing oxidizing agent is F 2 .
  • the amount of oxidizing agent in the atmosphere may be varied to obtain the stable phosphor particles, particularly in conjunction with variation of time and temperature.
  • the atmosphere may include at least 0.5% F 2 , although a lower concentration may be effective in some embodiments.
  • the atmosphere may include at least 5% F 2 and more particularly at least 20% F 2 .
  • the atmosphere may additionally include nitrogen, helium, neon, argon, krypton, xenon, in any combination with the fluorine- containing oxidizing agent.
  • the atmosphere is composed of about 20% F 2 and about 80% nitrogen.
  • the milled particles are further treated with a saturated solution of a composition of formula II in aqueous hydrofluoric acid, as described in US 8,252,613, after contacting the particles with the fluorine-containing oxidizing agent.
  • the temperature at which the phosphor is contacted with the solution ranges from about 20°C to about 50°C.
  • the period of time required to treat the phosphor ranges from about one minute to about five hours, particularly from about five minutes to about one hour.
  • Concentration of hydrofluoric acid in the aqueous HF solutions ranges from about 20% w/w to about 70% w/w, particularly about 40% w/w to about 70% w/w. Less concentrated solutions may result in lower yields of the phosphor.
  • any numerical values recited herein include all values from the lower value to the upper value in increments of one unit provided that there is a separation of at least 2 units between any lower value and any higher value.
  • the amount of a component or a value of a process variable such as, for example, temperature, pressure, time and the like is, for example, from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, it is intended that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 etc. are expressly enumerated in this specification.
  • one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 as appropriate.
  • the inventive subject matter provides a process that includes milling particles of a phosphor precursor, and then contacting the milled precursor particles at an elevated temperature with a fluorine-containing oxidizing agent to form the Mn 4+ doped phosphor.
  • the precursor is selected from the group consisting of:
  • A A 2 [MF 5 ] :Mn 4+ (where A is selected from Li, Na, K, Rb, Cs, and combinations thereof, and M is selected from Al, Ga, In, and combinations thereof),
  • the amount of manganese ranges from about 0.3 wt% to about
  • the amount of manganese ranges from about 0.75 wt%-2.5 wt% (about 3 mol% to about 10 mol%), particularly from about 0.9 wt% to 1.5 wt% (from about 3.5 mol% to about 6 mol%), more particularly from about 0.9 wt% to about 1.4 wt% (about 3.0 mol% to about 5.5 mol%), and even more particularly from about 0.9 wt% to about 1.3 wt% (about 3.5 mol% to about 5.1 mol%).
  • the Mn is at between 0.7 wt% and 0.9 wt%.
  • a lighting apparatus 10 (optionally referred to as a light emitting assembly or lamp) according to one embodiment of the inventive subject matter is shown in Figure 1.
  • the lighting apparatus 10 includes a semiconductor radiation source, shown as an LED chip 12, and leads 14 electrically attached to the LED chip 12.
  • the leads 14 may be thin wires supported by a thicker lead frame(s) 16 or the leads may be self-supported electrodes and the lead frame may be omitted.
  • the leads 14 provide current to LED chip 12 and thus cause the chip to emit radiation.
  • the chip is a near-UV or blue emitting LED having a peak emission wavelength from about 400 to about 500 nm.
  • the radiation source is described herein as an LED for convenience.
  • the radiation source may encompass other semiconductor radiation sources including, e.g., semiconductor laser diodes.
  • a phosphor material or composition 22 is radiationally coupled to the LED chip 12.
  • the phosphor material or composition 22 may be radiationally coupled with the LED chip 12 such that radiation from one (e.g., of the composition 22 and/or LED chip 12) is transmitted to the other.
  • the phosphor composition 22 is deposited on the LED 12 by any appropriate method, such as a water based suspension of the phosphor(s) being formed and applied as a phosphor layer to the LED surface. In one such method, a silicone slurry in which the phosphor particles are randomly suspended is placed around the LED. This method is merely one example of possible positions of phosphor composition 22 and LED 12.
  • the phosphor composition 22 is interspersed within the encapsulant material 20, instead of being formed directly on the LED chip 12.
  • the phosphor (in the form of a powder) may be interspersed within a single region of the encapsulant material 20 or throughout the entire volume of the encapsulant material. Blue light emitted by the LED chip 12 mixes with the light emitted by phosphor composition 22, and the mixed light appears as white light.
  • a phosphor powder may be added to a polymer or silicone precursor, and then the mixture may be cured to solidify the polymer or silicone material after or before loading the mixture on the LED chip 12.
  • polymer precursors include thermoplastic or thermoset polymers or a resin, for example epoxy resin. Other phosphor interspersion methods may also be used, such as transfer loading.
  • the encapsulant material 20 has an index of refraction R, and, in addition to phosphor composition 22, contains a diluent material having less than about 5% absorbance and index of refraction of R ⁇ 0.1.
  • the diluent material has an index of refraction of ⁇ 1.7, particularly ⁇ 1.6, and more particularly ⁇ 1.5.
  • the diluent material is of formula II, A x [MF y ], and has an index of refraction of about 1.4. Adding an optically inactive material to the phosphor/silicone mixture may produce a more gradual distribution of light flux through the phosphor/encapsulant mixture and can result in less damage to the phosphor.
  • Suitable materials for the diluent include fluoride compounds such as LiF, MgF 2 , CaF 2 , SrF 2 , A1F 3 , K 2 NaAlF 6 , KMgF 3 , CaLiAlF 6 , K 2 LiAlF 6 , and K 2 SiF 6 , which have index of refraction ranging from about 1.38 (A1F 3 and K 2 NaAlF 6 ) to about 1.43 (CaF 2 ), and polymers having index of refraction ranging from about 1.254 to about 1.7.
  • fluoride compounds such as LiF, MgF 2 , CaF 2 , SrF 2 , A1F 3 , K 2 NaAlF 6 , KMgF 3 , CaLiAlF 6 , K 2 LiAlF 6 , and K 2 SiF 6 , which have index of refraction ranging from about 1.38 (A1F 3 and K 2 NaAlF 6 ) to about 1.43 (
  • Non-limiting examples of polymers suitable for use as a diluent include polycarbonates, polyesters, nylons, polyetherimides, polyetherketones, and polymers derived from styrene, acrylate, methacrylate, vinyl, vinyl acetate, ethylene, propylene oxide, and ethylene oxide monomers, and copolymers thereof, including halogenated and unhalogenated derivatives. These polymer powders can be directly incorporated into silicone encapsulants before silicone curing.
  • the phosphor composition 22 is coated onto a surface of the shell 18, instead of being formed over the LED chip 12.
  • the phosphor composition is preferably coated on the inside surface of the shell 18, although the phosphor may be coated on the outside surface of the shell, if desired.
  • the phosphor composition 22 may be coated on the entire surface of the shell or only a top portion of the surface of the shell.
  • the UV/blue light emitted by the LED chip 12 mixes with the light emitted by phosphor composition 22, and the mixed light appears as white light.
  • the phosphor may be located in any two or all three locations or in any other suitable location, such as separately from the shell or integrated into the LED.
  • Figure 2 illustrates a second structure of the system according to the inventive subject matter described herein.
  • Corresponding numbers from Figures 1 through 4 relate to corresponding structures in each of the figures, unless otherwise stated.
  • the structure of the embodiment of Figure 2 is similar to that of Figure 1, except that the phosphor composition 122 is interspersed within the encapsulant material 120, instead of being formed directly on the LED chip 112.
  • the phosphor in the form of a powder
  • Radiation (indicated by arrow 126) emitted by the LED chip 112 mixes with the light emitted by the phosphor 122, and the mixed light appears as white light 124. If the phosphor is to be interspersed within the encapsulant material 120, then a phosphor powder may be added to a polymer precursor, and loaded around the LED chip 112. The polymer or silicone precursor may then be cured to solidify the polymer or silicone. Other known phosphor interspersion methods may also be used, such as transfer molding.
  • Figure 3 illustrates a third possible structure of the system according to the inventive subject matter described herein.
  • the structure of the embodiment shown in Figure 3 is similar to that of Figure 1, except that the phosphor composition 222 is coated onto a surface of the envelope
  • the phosphor composition 222 is preferably coated on the inside surface of the envelope 218, although the phosphor may be coated on the outside surface of the envelope, if desired.
  • the phosphor composition 222 may be coated on the entire surface of the envelope, or only a top portion of the surface of the envelope.
  • the radiation 226 emitted by the LED chip 212 mixes with the light emitted by the phosphor composition 222, and the mixed light appears as white light 224.
  • the structures of FIGS. 1-3 may be combined, and the phosphor may be located in any two or all three locations, or in any other suitable location, such as separately from the envelope, or integrated into the LED.
  • the lamp may also include a plurality of scattering particles (not shown), which are embedded in the encapsulant material.
  • the scattering particles may comprise, for example, alumina or titania. The scattering particles effectively scatter the directional light emitted from the LED chip, preferably with a negligible amount of absorption.
  • SMD surface mounted device
  • This SMD is a "side- emitting type” and has a light-emitting window 552 on a protruding portion of a light guiding member 554.
  • An SMD package may comprise an LED chip as defined above, and a phosphor material that is excited by the light emitted from the LED chip.
  • Other backlight devices include, but are not limited to, TVs, computers, monitors, smartphones, tablet computers and other handheld devices that have a display including a semiconductor light source; and a Mn 4+ doped phosphor according to the inventive subject matter.
  • Lamp 10 When used with an LED emitting at from 350 to 550 nm and one or more other appropriate phosphors, the resulting lighting system will produce a light having a white color.
  • Lamp 10 may also include scattering particles (not shown), which are embedded in the encapsulant material.
  • the scattering particles may comprise, for example, alumina or titania. The scattering particles effectively scatter the directional light emitted from the LED chip, preferably with a negligible amount of absorption.
  • phosphor composition 22 may include one or more other phosphors.
  • the resultant light emitted by the assembly will be a white light.
  • Other phosphors such as green, blue, yellow, red, orange, or other color phosphors may be used in the blend to customize the white color of the resulting light and produce specific spectral power distributions.
  • phosphor composition 22 materials suitable for use in phosphor composition 22 include electroluminescent polymers such as polyfluorenes, preferably poly(9,9- dioctyl fluorene) and copolymers thereof, such as poly(9,9'-dioctylfluorene- co-bis-N,N'-(4- butylphenyl)diphenylamine) (F8-TFB); poly(vinylcarbazole) and polyphenylenevinylene and their derivatives.
  • the light emitting layer may include a blue, yellow, orange, green or red phosphorescent dye or metal complex, or a combination thereof.
  • ADS blue dyes include ADS064BE, ADS065BE, and ADS070BE.
  • ADS red dyes include ADS067RE, ADS068RE, ADS069RE, ADS075RE, ADS076RE, ADS067RE, and ADS077RE.
  • Suitable phosphors for use in phosphor composition 22 include, but are not limited to:
  • the ratio of each of the individual phosphors in the phosphor blend may vary depending on the characteristics of the desired light output.
  • the relative proportions of individual phosphors in the various embodiment phosphor blends may be adjusted such that when their emissions are blended and employed in an LED lighting device, there is produced visible light of predetermined x and y values on the CIE chromaticity diagram.
  • a white light is preferably produced. This white light may, for instance, may possess an x value in the range of about 0.20 to about 0.55, and a y value in the range of about 0.20 to about 0.55.
  • the exact identity and amounts of each phosphor in the phosphor composition can be varied according to the needs of the end user.
  • the Mn 4+ doped phosphors of the inventive subject matter described herein may be used in applications other than those described above.
  • the material may be used as a phosphor in a fluorescent lamp, in a cathode ray tube, in a plasma display device or in a liquid crystal display (LCD).
  • the material may also be used as a scintillator in an electromagnetic calorimeter, in a gamma ray camera, in a computed tomography scanner or in a laser.
  • Manganese (Mn 4+ ) doped K 2 SiF 6 were synthesized according to a procedure described in the referenced U.S. Patent 7,497,973, in a FIF solution with a drying temperature of about 70 degrees Celsius.
  • Example 1 15g of manganese-doped potassium fluorosilicate (PFS:Mn) precursor,
  • K2SiF 6 :Mn 4+ having particles of D50 particle size of 46 microns and containing 0.76 wt% Mn based on total weight of the precursor material was added to 250 milliliters NALGENE bottle containing dry milling media and sealed in the bottle.
  • the bottle was placed on a roller mill for 15 minutes.
  • the milled precursor was removed from the bottle, which had D50 particles of 16 microns.
  • the milled precursor particles were then placed in a furnace chamber.
  • the furnace chamber was evacuated and was filled with an atmosphere containing 20% F 2 / 80% N 2 .
  • the chamber was then heated up to 540°C. After annealing the precursor for 8 hours, the chamber was cooled to room temperature.
  • Example 2 15g of manganese-doped potassium fluorosilicate (PFS:Mn) precursor,
  • the chamber was cooled to room temperature.
  • the fluorine nitrogen mixture was evacuated; the chamber was filled and purged several times with nitrogen to ensure the complete removal of fluorine gas before opening the chamber.
  • the annealed PFS powder was then treated (wet treatment) with a saturated solution of K 2 SiF 6 by placing the powder (-10 g) in a Teflon beaker containing 100 mL of a saturated solution of K 2 SiF 6 (initially made by adding ⁇ 5 g of K 2 SiF 6 in 40% ELF at room temperature, stirring, and filtering the solution). The suspension was stirred slowly, filtered, washed in acetone 3-5 times and the filtrate was dried under vacuum.
  • Table 2 shows quantum efficiency (QE) and stability (tested under conditions of high flux) of the PFS samples of example 1 and example 2 along with a commercially available phosphor of K2SiF 6 :Mn (Comparative example).
  • the milled and post-treated sample showed increased quantum efficiency (QE) and lifetime, and experienced significantly less damage compared to the PFS of the comparative example as well as as-synthesized PFS sample. It was also observed for example 2 that annealing improved the QE of the PFS powder by 23% - 28%, decreased the absorbance at 300nm, and increased the lifetime.
  • the wet treatment improved the HTFIH stability. HTFIH damage or loss was improved from more than 45% to less than 10%.
  • One or more embodiments of the inventive subject matter described above involve manufacturing processes for PFS that involve synthesizing phosphor powders or particles, followed by milling the powders or particles, followed by annealing the milled powders or particles, and then followed by treating surfaces of the annealed powders or particles.
  • this process can be modified as described below to provide phosphors that are able to withstand HTFIH or other environmental conditions better than the process described above, while also providing the same, better, or approximately the same QE as the process described above.
  • a phosphor precursor may be obtained (e.g., synthesized, such as using formula I) and milled into particles (e.g., using ball milling with or without a liquid medium).
  • the milled particles can then be annealed by contacting the milled particles with an oxidizing agent that includes fluorine at an elevated temperature.
  • the annealed particles may then be treated with a solution (e.g., a saturated solution of formula II). This treatment can reduce surface defects on the annealed particles.
  • a solution e.g., a saturated solution of formula II
  • FIG. 6 illustrates a flowchart of another embodiment of a method 600 for providing phosphor particles.
  • the method 600 may be used to manufacture phosphor particles that can be embedded in an encapsulant or otherwise used to create a phosphor for use in one or more light assemblies or lamps described herein.
  • a phosphor precursor is synthesized.
  • a phosphor precursor for a tetravalent manganese doped phosphor may be created using the formula I.
  • the phosphor precursor particles can be synthesized by mixing solutions that include sources of potassium, silicon, and manganese, and then precipitating K2SiF 6 :Mn particles from the mixture. These particles and remaining mixture are filtered to separate the solid particles from the liquid.
  • the precursor may be synthesized as powders or particles of various sizes.
  • at least some of the particles of the phosphor precursor have a D50 of 30 microns or larger (e.g., medium value of particle size distribution being equal to or bigger than thirty microns).
  • the particles are wet milled to reduce the sizes of the particles to a designated size or designated range of sizes.
  • the particles may be milled using wet ball milling or another milling technique.
  • Wet ball milling can involve mixing the phosphor precursor particles with a solution, including saturated K2S1F6 in HF solution, placing the mixture into a container with milling balls which are inert to the solution, and rotating the container to mill or grind the particles down to specified smaller sizes.
  • FIG. 7 schematically illustrates one example of milling the phosphor precursor powders or particles.
  • Phosphor precursor particles 700 are mixed with a solution that is placed inside a rolling container 702, which is prefilled with milling balls 704 which occupy the container by about one third to one half of the total volume.
  • saturated K2S1F6 solution is prepared at room temperature (initially made by adding K2S1F6 in 40% HF at room temperature, stirring, and filtering the solution) to form a milling solution.
  • An amount of the phosphor precursor particles (e.g., eighty milligrams or another amount) is mixed with the milling balls 704 (e.g., sixty grams of the milling balls or another amount) and the saturated milling solution (e.g., 240 milliliters of the saturated K2S1F6/HF solution or another amount) in the container 702 (e.g., a 250 milliliter capacity NALGE E bottle or another type of container).
  • the milling balls 704 may be formed from a material that does not react with the precursor particles 700, such a polytetrafluoroethylene (PTFE) balls.
  • the container 702 is rotated to cause the balls 704 to move within the container 702 and grind or mill the particles 700.
  • the container 702 is placed onto a lab roller manufactured by U.S. Stoneware Corp. with the rolling speed set to 70% or another speed.
  • the rotating of the container 702 changes the sizes of the particles 700 to a designated size or within a designated range, such as D50 particle size less than 30 microns, such as from 10 microns to 20 microns, or from 12 microns to 18 microns.
  • the particles 700 are wet milled until the particles are no larger than 22 microns. Alternatively, the particles 700 are milled to another size.
  • the rolling of the container 702 may continue for a period of time needed to reduce the particles 700 to no larger than the designated size or within the designated range, such as four hours or another length of time.
  • the milled particles are annealed.
  • the particles can be annealed by placing the particles into contact with a fluorine-containing oxidizing agent in gaseous form at an elevated temperature.
  • the fluorine-containing oxidizing agent may be F 2 , AIF3, SbFs, CIF3, BrF 3 , KrF, XeF 2 , XeF 4 , F 3 , SiF 4 , PbF 2 , ZnF 2 , SnF 2 , CdF 2 , or a combination thereof.
  • the particles can be placed into contact with the fluorine-containing oxidizing agent at temperatures of at least 200 degrees Celsius to 700 degrees Celsius, or another temperature.
  • the particles can be placed into contact with the fluorine-containing oxidizing agent at temperatures of at least 350 degrees Celsius to 600 degrees Celsius, or another temperature, such as at least 100 degrees Celsius, at least 225 degrees Celsius, or at least 350 degrees Celsius.
  • the time period during which the particles are placed into contact with the fluorine-containing oxidizing agent at the elevated temperatures can vary based on the temperature. For example, for hotter temperatures, the annealing time may decrease while, for cooler temperatures, the annealing time may increase.
  • the sample labeled JH-BM-A5 (control) is formed by synthesizing the particles (e.g., 602), then dry milling the particles, then annealing the particles (e.g., 606), and then treating the surfaces of the particles.
  • the dry milling of the control sample was performed by mixing the K2SiF 6 :Mn phosphor precursor powders and cesium-stabilized ZrCh milling stones in a ratio of 90 grams of the precursor powders to four hundred grams of the milling stones and capping this mixture in a 250 milliliter NALGE E bottle. The bottle was then placed on a lab roller manufactured by U.S. Stoneware Corp., with speed dial set at 70%.
  • the remaining samples (JH-BM-C2 (test) in Table 3) were prepared using the method 600, namely wet milling in saturated K2SiF6/HF solution using PTFE balls in a capped NALGENE bottle.
  • the HTHH exposure of the samples involved incorporating the particles of the different samples into a two-part silicone, which could be RTV615 from Momentive Performance Materials Inc., with 50 to 75% phosphor loading to create silicone/phosphor particle composite samples. These samples were then poured into Al plaque holders with a small indentation. Emission and reflectance (versus a BaS0 4 standard) under 450 nm excitation were measured for each sample. Some of the plaques are reserved and stored under dry nitrogen as control samples. The other plaques are aged at about 80° C and at about 80% relative humidity, and after a fixed time, spectra of the exposed and control plaque intensities are re-measured. The QE is calculated and compared to a standard sample, with relative values reported herein. The comparison of the QE before and after aging is a measure of the degradation of the sample which indicates HTHH reliability of the phosphor during product application. The less the decrease in QE, the better is the HTHH reliability.
  • Figure 9 is a scanning electron microscope (SEM) image of the JH-BM-A5
  • FIG. 10 is an SEM image of the JH-MN-C2 (test) sample.
  • Table 3 the normalized QE of all samples decreased after the exposure of the powders to HTHH for 47 hours, but the samples that were wet milled (e.g., JH-BM-C2) decreased by significantly less.
  • the largest decrease in QE of all of the powders prepared by wet milling the powders according to the method 600 is 9.10% while the smallest decrease in QE of the powders prepared using the method 600 is 8.00%).
  • the wet milling operation of 604 may be performed for a longer time period (e.g., ten hours instead of four hours) to further reduce the sizes of the phosphor precursor particles.
  • Performing the wet milling for longer can reduce the particle sizes of the phosphor precursor to no larger than fifteen microns.
  • the longer wet milling process also further increases the reliability of the phosphor precursor relative to other methods for manufacturing the phosphor precursor.
  • Table 4 illustrates normalized QE for several different samples of phosphor precursor particles prior to exposure to HTHH, after exposure to HTHH for forty-seven hours, and the difference in normalized QE before and after this HTHH exposure.
  • the samples BM Test Cell F were prepared using the method 600, but with wet milling the particles for ten hours to result in a smaller particle size of D50 being 15 microns.
  • Figure 11 is an SEM image of the BM Test Cell F sample. As shown in Table 4, the largest decrease in QE of the sample, prepared by wet milling the powders according to the method 600, but for a longer period of time, is about 4.6%> on average. As described above, the powders prepared without wet milling or with wet milling for a shorter time period experienced larger decreases in QE.
  • the wet milling of the phosphor precursor particles may increase the reliability and performance of the particles over time due to removal of manganese from exterior surfaces of the particles.
  • the manganese used to dope the phosphor particles may be present both inside the particles and on exterior surfaces of the particles as synthesized. During exposure of the phosphor particles to moisture, the manganese may degrade and decrease the QE of the particles.
  • the wet milling in saturated K2SiF6/HF solution may both remove the exterior manganese and decrease the sizes of the particles, and the manganese located inside the particles may be protected from the moisture.
  • the wet milling process as described herein can manufacture phosphors of small particle size, remove manganese from the exterior particle surface leaving manganese inside the particles core, allow the particles to operate as a phosphor and improve its HTHH reliability.
  • FIG. 8 illustrates a flowchart of another embodiment of a method 800 for providing phosphor particles.
  • the method 800 may be used to manufacture phosphor particles that can be embedded in an encapsulant or otherwise used to create a phosphor for use in one or more light assemblies or lamps described herein.
  • a phosphor precursor is synthesized.
  • a phosphor precursor for a tetravalent manganese doped phosphor may be created using the formula I.
  • the phosphor precursor particles can be synthesized by mixing solutions that include sources of potassium, silicon, and manganese, and then precipitating K2SiF 6 :Mn particles from the mixture. These particles and remaining mixture are filtered to separate the solid particles from the liquid.
  • the precursor may be synthesized as powders or particles of various sizes. In one embodiment, at least some of the particles of the phosphor precursor have a of 30 microns or larger (e.g., medium value of particle size distribution being equal to or bigger than thirty microns)
  • the particles are wet milled to reduce the sizes of the particles to a designated size or designated range of sizes.
  • the particles may be milled using wet ball milling or another milling technique.
  • Wet ball milling can involve mixing the phosphor precursor particles with a saturated K2S1F6/HF solution, placing the mixture into a container with milling balls inert to FIF solution, and rotating the container to mill or grind the particles down to smaller sizes.
  • the particles may be wet milled as described above in connection with the method 600.
  • the milled particles are annealed.
  • the particles can be annealed by placing the particles into contact with a fluorine-containing oxidizing agent in gaseous form at an elevated temperature.
  • the fluorine-containing oxidizing agent may be F 2 , AIF3, SbFs, CIF3, BrF 3 , KrF,
  • the particles can be placed into contact with the fluorine-containing oxidizing agent at temperatures of at least 200 degrees Celsius to 700 degrees Celsius, or another temperature.
  • the particles can be placed into contact with the fluorine-containing oxidizing agent at temperatures of at least 350 degrees Celsius to 600 degrees Celsius, or another temperature, such as at least 100 degrees Celsius, at least 225 degrees Celsius, or at least 350 degrees Celsius.
  • the time period during which the particles are placed into contact with the fluorine-containing oxidizing agent at the elevated temperatures can vary based on the temperature. For example, for hotter temperatures, the annealing time may decrease while, for cooler temperatures, the annealing time may increase.
  • the particles are annealed again.
  • the particles can be annealed again by placing the particles back into contact with a fluorine-containing oxidizing agent in gaseous form at an elevated temperature.
  • the agent and temperature used for the annealing may be the same as was used at 806, or a different agent and/or temperature may be used.
  • Wet milling the particles and using an additional annealing operation may increase the durability of the phosphors created from the particles obtained using the method 800 relative to particles formed without wet milling the phosphor precursor particles or relative to particles formed without wet milling and using the additional annealing operation.
  • Table 5 illustrates normalized QE for several different samples of phosphor precursor particles prior to exposure to HTHH, after exposure to HTHH for forty-seven hours, and the difference in normalized QE before and after this HTHH exposure.
  • the samples labeled JH-BM-A5 are formed by synthesizing the particles (e.g., 602), then dry milling the particles (as described above in connection with Table 3), then annealing the particles (e.g., 606) a single time.
  • the remaining samples (JH-BM-C5 (test) in Table 5) were prepared using the method 800. Both samples are milled down to the same particle size of D50 being 22 microns, starting from a same batch of synthesized precursors
  • Figure 12 is an SEM image of the JH-BM-C5 (test) sample. As shown in Table 5, the normalized QE of all samples decreased after the exposure of the powders to HTHH for 47 hours, but the samples that were wet milled and annealed multiple times (e.g., JH-BM-C5) decreased by significantly less. The largest decrease in QE of all of the powders prepared by wet milling the particles and annealing the particles multiple times according to the method 800 is 9.70% while the smallest decrease in QE of the particles prepared using the method 800 is 8.60%. The powders prepared without wet milling and without the multiple anneals, however, experienced a decrease in QE of 13.2% or 14.0%.

Abstract

L'invention concerne un procédé consistant à obtenir des particules d'un précurseur de substance luminescente de formule Ax[MFy]:Mn4+, à réduire les grosseurs des particules du précurseur de substance luminescente par broyage humide des particules et à recuire les particules qui ont été broyées par voie humide par mise en contact des particules avec un agent oxydant contenant du fluor. De plus, l'invention concerne une substance luminescente à base d'un fluorure complexe dopé au manganèse préparée par ce procédé. L'invention porte également sur un appareil d'éclairage et sur un dispositif de rétroéclairage qui comprennent la substance luminescente dopée au manganèse préparée par ce procédé.
PCT/US2017/034477 2016-06-02 2017-05-25 Substances luminescentes émettant de la lumière rouge et dispositifs associés WO2017210080A1 (fr)

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CN201780034265.5A CN109219646B (zh) 2016-06-02 2017-05-25 发射红光的磷光体及相关装置
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US15/171,098 US10563121B2 (en) 2014-06-12 2016-06-02 Red-emitting phosphors and associated devices

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