WO2006061778A1 - Illumination system comprising a radiation source and a blue-emitting phospor - Google Patents

Illumination system comprising a radiation source and a blue-emitting phospor Download PDF

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Publication number
WO2006061778A1
WO2006061778A1 PCT/IB2005/054077 IB2005054077W WO2006061778A1 WO 2006061778 A1 WO2006061778 A1 WO 2006061778A1 IB 2005054077 W IB2005054077 W IB 2005054077W WO 2006061778 A1 WO2006061778 A1 WO 2006061778A1
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WIPO (PCT)
Prior art keywords
phosphor
light
emitting
blue
radiation source
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PCT/IB2005/054077
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French (fr)
Inventor
Peter J. Schmidt
Baby Seriyati Schreinemacher
Wolfgang Schnick
Florian Manfred Stadler
Joerg Meyer
Original Assignee
Philips Intellectual Property & Standards Gmbh
Koninklijke Philips Electronics N.V.
Lumileds Lighting, Us, Llc
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Publication of WO2006061778A1 publication Critical patent/WO2006061778A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
    • C09K11/77348—Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/0883—Arsenides; Nitrides; Phosphides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/484—Connecting portions
    • H01L2224/48463—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
    • H01L2224/48465—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/85—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a wire connector
    • H01L2224/85909—Post-treatment of the connector or wire bonding area
    • H01L2224/8592—Applying permanent coating, e.g. protective coating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/15—Details of package parts other than the semiconductor or other solid state devices to be connected
    • H01L2924/181—Encapsulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
    • H01L33/502—Wavelength conversion materials

Definitions

  • Illumination system comprising a radiation source and a blue-emitting phosphor
  • the present invention generally relates to an illumination system comprising a radiation source and a luminescent material comprising a phosphor.
  • the invention also relates to a phosphor for use in such an illumination system.
  • the invention relates to an illumination system and a luminescent material comprising a phosphor for the generation of specific, colored light, including white light, by luminescent down conversion and additive color mixing based an ultraviolet radiation emitting radiation source.
  • a light-emitting diode as a radiation source is especially contemplated.
  • Previous white-light illumination systems have been based in particular either on the trichromatic (RGB) approach, i.e. on the mixing of three colors, i.e. red, green, and blue, in which case the components of the output light may be provided by the primary emission of colored light-emitting diodes in combination with phosphors, or in a second, simpler solution, on the dichromatic (BY) approach, i.e. on the mixing of yellow and blue colors, in which case the yellow secondary component of the output light may be provided by a yellow phosphor and the blue component may be provided by a phosphor or by the primary emission of a blue LED.
  • RGB trichromatic
  • BY dichromatic
  • the dichromatic approach uses a blue light emitting diode of InGaN-based semiconductor material combined with an Y 3 Al 5 O 12 :Ce phosphor (YAG-Ce 3+ ).
  • the YAG-Ce 3+ phosphor is coated on the InGaN LED, and a portion of the blue light emitted from the LED is converted into yellow light by the phosphor. Another portion of the blue light from the LED is transmitted through the phosphor.
  • this system emits both blue light, emitted from the LED, and yellow light emitted from the phosphor.
  • the mixture of blue and yellow emission bands is perceived as white light by an observer, with a typical CRI in the middle 70ties and a color temperature Tc that ranges from about 6000 K to about 8000 K.
  • the present invention provides an illumination system comprising a primary radiation source, preferably providing UV radiation, and a luminescent material comprising at least one phosphor capable of absorbing part of radiation emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said at least one phosphor is a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr 1-x-y Ca x Ba y )2-zAlbSi 1 2-bN 16- bO a +b :Eu z , wherein 0 ⁇ x ⁇ l; 0 ⁇ y ⁇ l;0.001 ⁇ z ⁇ 0.4, 0 ⁇ a ⁇ 2 and 0 ⁇ b ⁇ 2.
  • a radiation source is a UV radiation emitting diode providing UV radiation in the range from 370 to 400 nm.
  • An illumination system according to the present invention can provide a blue output light that is a well defined and has constant color point. In particular, the blue output light is independent of drive and temperature. This characteristic makes the device ideal for applications in which a reproducible true color rendering and a large color gamut is required.
  • a blue-light illumination system comprises a UV light emitting diode having a peak emission wavelength in the range of 370 to 400 nm as a radiation source and a luminescent material comprising at least one phosphor, which is a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr 1-x-y Ca x Ba y )2-zAlbSi 1 2-bN 16- bO a +b :Eu z , wherein 0 ⁇ x ⁇ l;0 ⁇ y ⁇ l;0.001 ⁇ z ⁇ 0.4, 0 ⁇ a ⁇ 2 and ⁇ b ⁇ 2.
  • Such an illumination system will provide blue light with a constant color point in operation.
  • the blue light emitted by the LED excites the phosphor, causing it to reemit blue light.
  • the viewer perceives the blue reemitted radiation.
  • the invention provides a white-light illumination system comprising a UV light emitting diode having a peak emission wavelength in the range of 370 to 400 nm as a radiation source and a luminescent material comprising a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula(Sr 1-x-y Ca x Ba y )2-zAlbSi 1 2-bN 16- bO a +b :Eu z , wherein 0 ⁇ x ⁇ l;0 ⁇ y ⁇ 1 ;0.001 ⁇ z ⁇ 0.4, 0 ⁇ a ⁇ 2 and 0 ⁇ b ⁇ 2 and at least one second phosphor.
  • a white-light illumination system comprising a UV light emitting diode having a peak emission wavelength in the range of 370 to 400 nm as a radiation source and a luminescent material comprising a europium(II)-activated alkaline earth oxo-nitr
  • the luminescent material of this embodiment may be a phosphor blend comprising a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr 1-x-y Ca x Ba y )2 -z AlbSi 1 2-bN 16- bO a +b :Eu z , wherein 0 ⁇ x ⁇ l;0 ⁇ y ⁇ 1 ;0.001 ⁇ z ⁇ 0.4, 0 ⁇ a ⁇ 2and0 ⁇ b ⁇ 2, and a yellow to red phosphor.
  • a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr 1-x-y Ca x Ba y )2 -z AlbSi 1 2-bN 16- bO a +b :Eu z , wherein 0 ⁇ x ⁇ l;0 ⁇ y ⁇ 1 ;0.001 ⁇ z ⁇ 0.4, 0 ⁇ a ⁇ 2and0
  • Such a yellow to red phosphor may be selected from the group of Eu(II)-activated phosphors, more particularly selected from the group defined by (Ca 1-x Sr x ) S:Eu, wherein 0 ⁇ x ⁇ 1, (Sr 1-x-y Ba x Ca y )2-zSi 5-a Al a N 8-a O a :Eu z wherein 0 ⁇ a ⁇ 5, 0 ⁇ x ⁇ l,0 ⁇ y ⁇ 1, and 0 ⁇ z ⁇ 1, and (Y 5 Gd) 3 Al 5 O 12 )Ce.
  • Eu(II)-activated phosphors more particularly selected from the group defined by (Ca 1-x Sr x ) S:Eu, wherein 0 ⁇ x ⁇ 1, (Sr 1-x-y Ba x Ca y )2-zSi 5-a Al a N 8-a O a :Eu z wherein 0 ⁇ a ⁇ 5, 0 ⁇ x ⁇ l,0 ⁇
  • Such an illumination system will provide dichromatic white light in operation.
  • Part of the UV radiation emitted by the LED excites the blue-emitting phosphor, causing it to reemit blue light.
  • Another part of the UV-radiation and/or the blue reemitted radiation is absorbed by the second phosphor and reemitted as yellow to red light. The viewer perceives the mixture of blue and yellow to red light as white light.
  • the luminescent material of this embodiment may be a phosphor blend comprising a blue light emitting europium(II)-activated alkaline earth oxo-nitridosilicate of general formula(Sr 1-x-y Ca x Ba y )2-zAlbSi 1 2-bN 16- bO a +b :Eu z , wherein 0 ⁇ x ⁇ l; 0 ⁇ y ⁇ l;0.001 ⁇ z ⁇ 0.4, 0 ⁇ a ⁇ 2 and 0 ⁇ b ⁇ 2, a yellow to red phosphor, and a green phosphor.
  • a blue light emitting europium(II)-activated alkaline earth oxo-nitridosilicate of general formula(Sr 1-x-y Ca x Ba y )2-zAlbSi 1 2-bN 16- bO a +b :Eu z , wherein 0 ⁇ x ⁇ l;
  • Part of the UV radiation emitted by the LED excites the blue light emitting phosphor according to the invention, causing it to reemit blue light.
  • Part of the UV radiation and/or the reemitted blue radiation is also absorbed by the second phosphor and reemitted as yellow to red light.
  • Another part of the UV radiation and/or the reemitted blue radiation is absorbed by the third phosphor and reemitted as green light. The viewer perceives the mixture of blue, yellow to red, and green light as white light.
  • Another aspect of the present invention provides a phosphor capable of absorbing part of the light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said phosphor is a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr 1 -x- y Ca x Ba y ) 2- zAlbSi 1 2-bN 16- bO a+ b :Eu z , wherein 0 ⁇ x ⁇ l; 0 ⁇ y ⁇ l;0.001 ⁇ z ⁇ 0.4, 0 ⁇ a ⁇ 2 and 0 ⁇ b ⁇ 2.
  • the blue phosphors of the europium(II)- activated alkaline earth oxo-nitridosilicate type have a small Stokes shift. They can therefore very efficiently be excited by primary radiation of 370 to 400 nm.
  • the luminescent material has ideal characteristics for conversion of UVA-radiation into blue light. Total conversion efficiency can be up to 90 %.
  • These phosphors are narrow-band emitters wherein the visible emission is so narrow that there is a 36-nm wavelength range where the visible emission is predominantly located. Therefore these europium(II)-activated alkaline earth oxo- nitridosilicate phosphors emit this narrow band in the blue spectral range of the visible spectrum with very high efficiency. The remaining quantum loss caused by the Stokes shift of the phosphors is compensated for by the higher internal quantum efficiency of an illumination system comprising a UV LED and a blue phosphor according to the invention as compared with a blue, directly emitting LED used as a source of blue radiation. Additional important characteristics of the phosphors include 1) resistance to thermal quenching of luminescence at typical device operating temperatures (e.g.
  • the invention relates to the specific phosphor composition SrSi 6 N 8 :Eu z , wherein 0.01 ⁇ z ⁇ 0.4, which exhibits a high quantum efficiency of 80 - 90 %, a high absorbance of 60-80% in the range from 370 nm to 400 nm, an emission spectrum with a peak wavelength of about 453nm, and low losses, below 10% of the luminescent lumen output, caused by thermal quenching from room temperature to 100 °C.
  • a specific phosphor composition of formula Sr 1-z/2 Si 6 N 8 O a :Eu z , wherein 0 ⁇ a ⁇ 1 and 0.001 ⁇ z ⁇ 0.2 ( Sr 2-z Si 12 N 16 O a :Eu z , wherein 0 ⁇ a ⁇ 2 and 0.001 ⁇ z ⁇ 0.4) is especially valuable as a phosphor in white light emitting phosphor-converted LEDs with low color temperatures and improved color rendering.
  • These phosphors may have a coating selected from the group of fluorides and orthophosphates of the elements aluminum, scandium, yttrium, lanthanum, gadolinium, and lutetium, the oxides of aluminum, yttrium, and lanthanum, and the nitride of aluminum.
  • the present invention focuses on a europium(II)-activated alkaline earth oxo- nitridosilicate as a phosphor in any configuration of an illumination system containing a radiation source, including, but not limited to discharge lamps, luminescent lamps, LEDs, LDs, and X-ray tubes.
  • a radiation source including, but not limited to discharge lamps, luminescent lamps, LEDs, LDs, and X-ray tubes.
  • the term "radiation” preferably covers radiation in the UV and visible ranges of the electromagnetic spectrum. While the use of the present phosphor is contemplated for a wide array of illumination applications, the present invention is described with particular reference to and finds particular application in illumination systems comprising light-emitting diodes, especially diodes that emit UV radiation.
  • the luminescent material according to the invention comprises as a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula
  • the three-dimensional network is built up from group units consisting of SiN 4 - and Si(SiN 3 )- tetrahedrons, sharing vertices so as to form a three-dimensional framework comprising Si-Si-bonds.
  • Fig. 5 shows the crystal structure of the basic host lattice SrSi 6 N 8 , wherein the strontium cations may be replaced by europium(II) cations as well as other alkaline earth metals. If the phosphor comprises oxygen, then Si-Si bonds are oxidized to form regular Si-O- Si. bonds as shown in Fig.6. There may be an isoelectronic substitution of Si-N-bonds by Al-O bonds.
  • the alkaline earth cations of strontium, calcium, and barium as well as europium and possibly a co-activator populate a single lattice site only, where they are coordinated exclusively by nitrogen atoms.
  • the host lattice for these materials may be a four-element (two cations) oxo-nitridosilicate such as europium(II)-activated strontium oxo-nitridosilicate SrSi 6 N 8 :Eu, or may comprise more that four elements such as europium(II)-activated strontium-barium oxo-nitridosilicate (Sr, Ba)Si 6 N 8 O a :Eu.
  • the proportion preferably lies within the range from 0.999: 0.001 to 0.8: 0.4.
  • the alkaline earth metals may be mutually substituted. If the proportion z of europium (II) is 0.001 or lower, luminance decreases because the number of excited photoluminescence emission centers constituted by europium(II)-cations decreases and density quenching occurs if z is above 0. 2. Density quenching is a decrease in emission intensity that occurs when the concen- tration of an activation agent added to increase the luminance of the luminescent material is increased beyond an optimum level.
  • the phosphors according to the invention can be especially excited by a radiation source providing UV emission with wavelengths of 370 to 400 nm, such as a UV LED.
  • a radiation source providing UV emission with wavelengths of 370 to 400 nm, such as a UV LED.
  • the luminescent material has ideal characteristics for converting UV radiation of nitride semiconductor light-emitting diodes into blue light.
  • the method of producing a europium(II)-activated alkaline earth oxo- nitridosilicate phosphor of the present invention is not particularly restricted, and it can be implemented by firing any mixture of starting materials that provide a europium(II)-activated alkaline earth oxo-nitridosilicate luminescent material.
  • Starting materials having a high purity of 99.9% or more and taking form of fine particles having an average particle size of 1 ⁇ m or less are preferably used.
  • the starting materials i.e. alkaline earth carbonates, euro- pium(III) compounds such as the oxide together with a carbon modification as a reducing agent, and a silicon-nitrogen compound such as silicon diimide or silicon nitride
  • euro- pium(III) compounds such as the oxide together with a carbon modification as a reducing agent
  • a silicon-nitrogen compound such as silicon diimide or silicon nitride
  • the obtained mixture is placed in a heat-resistant container such as an alumina crucible and a tungsten boat, and then fired in an electric furnace.
  • a preferred firing temperature lies between 1,200 and 1,500 0 C.
  • the firing atmosphere is not particularly restricted, for example, it is preferable to fire in a reducing atmosphere such as an atmosphere comprising an inert gas such as nitrogen and argon and the like, and hydrogen in a proportion of 0.1 to 10 volume%.
  • the firing period is determined subject to various conditions such as the quantity of mixture charged in the container, the firing temperature, and the temperature at which the product is removed from the furnace, but it generally lies in the range of 2 to 4 hours.
  • Luminescent material obtained by the above method may be ground by means of, for example, a ball mill, a jet mill, and the like. It may subsequently be washed and classified. Re-firing is suggested for enhancing the cristallinity of the resulting granular phosphor.
  • one of the preferred compounds represented by SrSi 6 N 8 : Eu(II) is produced by the method where europium(III) oxide Eu 2 O 3 , strontium carbonate SrCO 3 , and silicon nitride Si 3 N 4 together with microcrystalline graphite as the starting materials are weighed and compounded to give a molar ratio of by SrSi 6 N 8 : Eu whereupon they are fired in a reducing atmosphere.
  • Fig. 4 shows the X-ray diffraction data of SrSi 6 N 8 :Eu.
  • Each phosphor of the europium(II)-activated alkaline earth oxo- nitridosilicate type exhibits a bluish fluorescence when excited by radiation of the UVA range of the electromagnetic spectrum.
  • Fig. 7 of the drawings accompanying this specification gives the emission and reflection spectra of SrSi 6 N 8 :Eu2%.
  • the SrSi 6 N 8 :Eu2% phosphor When excited by radiation of 365 nm wavelength, the SrSi 6 N 8 :Eu2% phosphor is found to give a narrow band emission with a peak wavelength at 453 nm.
  • the phosphor SrSi 6 N 8 : Eu is resistant to heat, light, and moisture because of its oxo- nitridosilicate host lattice.
  • the europium(II)-activated alkaline earth oxo-nitridosilicate type phosphors according to the invention may be coated with a thin, uniform protective layer of one or more compounds selected from the group formed by the fluorides and orthophosphates of the elements aluminum, scandium, yttrium, lanthanum, gadolinium, and lutetium, the oxides of aluminum, yttrium, and lanthanum, and the nitride of aluminum.
  • the protective layer thickness customarily ranges from 0.001 to 0.2 nm and is thus so thin that it can be penetrated by the radiation of the radiation source without any substantial loss of energy.
  • the coatings of these materials on the phosphor particles may be applied, for example, by deposition from the gas phase or a wet coating process.
  • the invention also relates to an illumination system comprising a radiation source and a luminescent material comprising at least one phosphor that is a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr 1-X- y Ca x Ba y ) 2- zAlbSi 1 2-bN 16- bO a+b :Eu z , wherein 0 ⁇ x ⁇ l; 0 ⁇ y ⁇ l;0.001 ⁇ z ⁇ 0.4, 0 ⁇ a ⁇ 2 and 0 ⁇ b ⁇ 2.
  • Radiation sources include semiconductor optical radiation emitters and other devices that emit optical radiation in response to electrical excitation.
  • Semiconductor optical radiation emitters include light-emitting diode LED chips, light-emitting polymers (LEPs), organic light-emitting devices (OLEDs), polymer light-emitting devices (PLEDs), etc.
  • light-emitting components such as those found in discharge lamps and fluorescent lamps, such as mercury low and high pressure discharge lamps, sulfur discharge lamps, and discharge lamps based a molecular radiators are also contemplated for use as radiation sources with the present inventive phosphor compositions.
  • the radiation source is a light-emitting diode (LED).
  • any configuration of an illumination system which includes a light- emitting diode and a europium(II)-activated alkaline earth oxo-nitridosilicate phosphor composition is contemplated in the present invention, preferably with the addition of other well-known phosphors, which can be combined to achieve a specific color or white light when irradiated by a LED that emits primarily UV radiation as specified above.
  • a detailed construction of one embodiment of such an illumination system as shown in Fig.l, comprising a radiation source and a luminescent material, will now be described.
  • FIG. 1 is a schematic view of a chip-type light-emitting diode with a coating comprising the luminescent material.
  • the device comprises the chip-type light-emitting diode (LED) 1 as a radiation source.
  • the light-emitting diode dice is positioned in a reflector cup lead frame 2.
  • the dice 1 is connected via a bond wire 7 to a first terminal 6 and directly to a second electric terminal 6.
  • the recess of the reflector cup is filled with a coating material that contains a luminescent material according to the invention to form a coating layer that is embedded in the reflector cup.
  • the phosphors are applied either separately or in a mixture.
  • the coating material typically comprises a polymer 5 for encapsulating the phosphor or phosphor blend.
  • the phosphor or phosphor blend should exhibit high stability properties against the encapsulant.
  • the polymer is optically clear to prevent significant light scattering.
  • a variety of polymers are known in the LED industry for making LED illumination systems.
  • the polymer is preferably selected from the group consisting of epoxy and silicone resins.
  • Adding of the phosphor mixture to a liquid that is a polymer precursor can perform encapsulation.
  • the phosphor mixture may be a granular powder.
  • the introduction of phosphor particles into the polymer precursor liquid results in the formation of a slurry (i.e. a suspension of particles).
  • the phosphor mixture is fixed rigidly in place by the encapsulation.
  • both the luminescent material and the LED dice are encapsulated in the polymer.
  • the transparent coating material may comprise light-diffusing particles, advantageously so-called diffusers.
  • diffusers are mineral fillers, in particular CaF2, Ti ⁇ 2, Si ⁇ 2, CaC ⁇ 3 or BaSO4 or any other organic pigments. These materials can be added to the above-mentioned resins in a simple manner.
  • the luminescent material is provided as a coating on the light-emitting diode dice.
  • a coating may comprise a single layer comprising the blue-emitting phosphor according to the invention, as shown in Fig. 2.
  • a coating may comprise two or more layers comprising the blue-emitting phosphor according to the invention in a first layer and second phosphors in second layers, as shown in Fig. 3.
  • the dice In operation, electrical power is supplied to the dice to activate the dice.
  • the dice When activated, the dice emits the primary radiation, e.g. UV radiation.
  • the emitted primary light is absorbed by the luminescent material in the coating layer.
  • the luminescent material then emits secondary light, i.e., the converted light having a longer peak wavelength, primarily blue in a narrow band in response to absorption of the primary radiation.
  • an illumination system that emits output light having a spectral distribution such that it appears to be "blue” light is contemplated.
  • Luminescent material comprising europium(II)-activated alkaline earth oxo-nitridosilicate as a phosphor is particularly well suited as a blue component for stimulation by a primary UVA radiation source such as, for example, a UVA-emitting LED
  • a blue light emitting illumination system can advantageously be produced in that the luminescent material is selected from the luminescent materials that comprise an europium(II)-activated alkaline earth oxo-nitridosilicate phosphor, such that a UV radiation emitted by the UV light emitting diode is converted into higher wavelength ranges to form monochromatic blue light.
  • the luminescent material is selected from the luminescent materials that comprise an europium(II)-activated alkaline earth oxo-nitridosilicate phosphor, such that a UV radiation emitted by the UV light emitting diode is converted into higher wavelength ranges to form monochromatic blue light.
  • a blue light emitting illumination system can particularly preferably be realized by admixing an excess of the inorganic luminescent material SrSi 6 N 8 :Eu(2%) to a silicon resin used to produce the luminescence conversion encapsulation or layer. Part of a radiation emitted by a UV-emitting diode is shifted by the inorganic luminescent material SrSi 6 N 8 :Eu(2%) into the blue spectral region of the electromagnetic spectrum.
  • the output light of the illumination system may have a spectral distribution such that it appears to be "white” light.
  • a white light emitting illumination system can advantageously be produced in that the luminescent material is chosen such that a UV radiation emitted by a UV light emitting diode is converted into complementary wavelength ranges so as to form dichromatic white light.
  • yellow to red as well as blue light is produced by means of the luminescent materials.
  • Blue light is produced by the luminescent materials that comprise a europium(II)-activated alkaline earth oxo-nitridosilicate phosphor.
  • Yellow to red light may be preferably produced by the luminescent materials that comprise a phosphor selected from the group comprising (Ca 1-x Sr x ) S:Eu, wherein 0 ⁇ x ⁇ 1 , (Sr 1-x-y Ba x Ca y ) 2- zSi 5-a Al a N 8-a O a :Eu z , wherein 0 ⁇ a ⁇ 5, 0 ⁇ x ⁇ l, 0 ⁇ y ⁇ l, and 0 ⁇ z ⁇ 0.09, and (Y 5 Gd) 3 Al 5 O 12 )Ce.
  • a phosphor selected from the group comprising (Ca 1-x Sr x ) S:Eu, wherein 0 ⁇ x ⁇ 1 , (Sr 1-x-y Ba x Ca y ) 2- zSi 5-a Al a N 8-a O a :Eu z , wherein 0 ⁇ a ⁇ 5, 0
  • a second yellow to red emitting luminescent material may be used in addition in order to improve the color rendition of this illumination system.
  • Particularly good results are achieved in conjunction with a UVA light emitting diode whose emission maximum lies at 370 to 400 nm. An optimum was found to lie at 390 nm, taking particular account of the excitation spectrum of the europium(II)-activated alkaline earth oxo-nitridosilicate. Part of a blue radiation emitted by a UVA-emitting diode is shifted by the inorganic luminescent material, e.g.
  • the color output of an LED's phosphor system is very sensitive to the thickness of the phosphor layer. If the phosphor layer is thick and comprises an excess of a yellow phosphor, then a lesser amount of the blue light will penetrate through the thick phosphor layer. The combined LED / phosphor system will then appear yellow to red, because it is dominated by the yellow to red secondary light of the phosphor.
  • the thickness of the phosphor layers is a critical variable affecting the color output of the system.
  • the hue (color point in the CIE chromaticity diagram) of the white light thereby produced can be varied in this case by a suitable choice of the phosphors in respect of their mixing ratio, their particle sizes, and their concentrations. These arrangements also afford the possibility of using optimized phosphor blends in the luminescent material, as a result of which, advantageously, the desired hue can be set even more accurately.
  • a white light emitting illumination system can advantageously be produced by choosing the luminescent material such that a radiation emitted by the UV light emitting diode is converted into complementary wavelength ranges so as to form trichromatic white light, e.g. by means of additive color triads, for example blue, green, and red.
  • trichromatic white light is produced by means of the luminescent materials that comprise a blend of phosphors including a blue-emitting europium(II)-activated alkaline earth oxo-nitridosilicate phosphor, a second phosphor emitting in the red spectral range, and a third phosphor emitting in the green spectral range.
  • phosphors including a blue-emitting europium(II)-activated alkaline earth oxo-nitridosilicate phosphor, a second phosphor emitting in the red spectral range, and a third phosphor emitting in the green spectral range.
  • a white light emission with high color rendering can be obtained especially with the use of red and green broad-band emitter phosphors covering the entire spectral range together with a UV-emitting LED and a blue-emitting europium(II)-activated alkaline earth oxo-nitridosilicate phosphor.
  • the hue (color point in the CIE chromaticity diagram) of the white light thus produced can be varied in this case by a suitable choice of the phosphors in respect of their mixing ratio and concentrations.
  • the luminescent materials for trichromatic white light may preferably comprise besides the blue-emitting phosphor according to the invention, a red phosphor selected from the group comprising (Ca 1-x Sr x ) S:Eu, wherein 0 ⁇ x ⁇ 1, and (Sr 1-X- y Ba x Ca y ) 2-z Si 5-a Al a N 8-a O a :Eu z , wherein 0 ⁇ a ⁇ 5, 0 ⁇ x ⁇ l, 0 ⁇ y ⁇ l and 0 ⁇ z ⁇ 0.09, and (Y 5 Gd) 3 Al 5 O 12 :Ce, and a green phosphor selected from the group comprising (Bai_ x Sr x )2 SiC ⁇ : Eu, wherein 0 ⁇ x ⁇ 1, SrGa2S4 :Eu, and SrSi2N2U2:Eu.
  • a red phosphor selected from the group compris
  • a white-light emitting illumination system can particularly preferably be realized by admixing the inorganic luminescent material comprising a mixture of three phosphors to a silicon resin used to produce the luminescence conversion encapsulation or layer.
  • a first phosphor (1) is the blue-emitting alkaline earth oxo-nitridosilicate SrSi 6 N 8 : Eu
  • the second phosphor (2) is the red-emitting CaS: Eu
  • the third (3) is a green-emitting phosphor of the type SrSi2N2U2:Eu.
  • Part of a UV radiation emitted by a UV-emitting diode is shifted by the inorganic luminescent material SrSi 6 N 8 : Eu into the blue spectral region. Another part of the radiation emitted by the UV-emitting diode is shifted by the inorganic luminescent material CaS: Eu into the red spectral region. Still another part of the radiation emitted by the UV-emitting diode is shifted by the inorganic luminescent material SrSi2N2U2: Eu into the green spectral region. A human observer perceives the polychromatic secondary light of the phosphor blend as white light.
  • the hue (color point in the CIE chromaticity diagram) of the white light thus produced can be varied in this case by a suitable choice of the phosphors in respect of their mixing ratio and concentration
  • Fig. 1 is a schematic view of a dichromatic white LED lamp comprising a phosphor of the present invention together with a yellow to orange phosphor positioned in a pathway of light emitted by an UV-LED structure.
  • FIG. 2 is a schematic view of a monochromatic blue LED lamp.
  • FIG. 3 is a schematic view of a dichromatic white LED lamp.
  • FIG. 4 shows the XRD pattern of SrSi 6 N 8 : Eu(II) measured by Cu Ka radiation.
  • FIG. 5 shows the three-dimensional network structure of the host lattice SrSi 6 N 8 .
  • FIG. 6 shows the three-dimensional network structure of the host lattice SrSi 6 N 8 O.
  • FIG. 7 shows emission and reflection spectra of SrSi 6 N 8 :Eu(II).

Abstract

Illumination system comprising a radiation source and a blue-emitting phosphor. An illumination system comprising a radiation source and a luminescent material comprising at least one phosphor capable of absorbing part of the light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said at least one phosphor is a blue-emitting europium(II)- activated alkaline earth oxo-nitridosilicate of the general formula(Sr1-x-y-CaxBay)2- zAlbSi12-bN16-bOa+b :Euz, wherein 0 ≤ x ≤ l; 0 ≤ y ≤ l ;0.001 ≤ z ≤ 0.4, 0 ≤ a < 2 and 0 ≤ b < 2, can provide a light source having high luminance and color-rendering index, especially in conjunction with a light-emitting diode serving as the radiation source. The blue-emitting europium(II)-activated alkaline earth oxo- nitridosilicate of the general formula (Sr1-x-y-CaxBay)2- zAlbSi12-bN16-bOa+b :Euz, wherein 0 ≤ x ≤ 1; 0 ≤ y ≤ 1;0.001 ≤ z ≤ 0.4, 0 ≤ a < 2 and 0 ≤ b < 2 can be efficiently excited by primary radiation in the near UV range of the electromagnetic spectrum.

Description

TITLE OF THE INVENTION
Illumination system comprising a radiation source and a blue-emitting phosphor
BACKGROUND OF THE INVENTION
The present invention generally relates to an illumination system comprising a radiation source and a luminescent material comprising a phosphor. The invention also relates to a phosphor for use in such an illumination system.
More particularly, the invention relates to an illumination system and a luminescent material comprising a phosphor for the generation of specific, colored light, including white light, by luminescent down conversion and additive color mixing based an ultraviolet radiation emitting radiation source. A light-emitting diode as a radiation source is especially contemplated.
Recently, various attempts have been made to make white light emitting illumination systems by using light-emitting diodes as radiation sources. Generating white light with an arrangement of red, green and blue light-emitting diodes involves the problem that white light of the desired tone cannot be generated due to variations in the tone, luminance and other factors of the light-emitting diodes. These variations are a natural part of the manufacturing process and are caused by slight variations in the amounts of dopants that each chip receives and by slight variations in the quantum well structure. Such variations of light-emitting diodes have to be separated into "bin sorts" and to be tested to get diodes of identical or near-identical wavelength. Providing large quantities of LEDs with the same shade can therefore be a problem with some manufacturers.
In order to solve these problems, various illumination systems have been developed, which convert the color of light-emitting diodes by means of a luminescent material comprising a phosphor so as to provide visible white-light illumination.
Previous white-light illumination systems have been based in particular either on the trichromatic (RGB) approach, i.e. on the mixing of three colors, i.e. red, green, and blue, in which case the components of the output light may be provided by the primary emission of colored light-emitting diodes in combination with phosphors, or in a second, simpler solution, on the dichromatic (BY) approach, i.e. on the mixing of yellow and blue colors, in which case the yellow secondary component of the output light may be provided by a yellow phosphor and the blue component may be provided by a phosphor or by the primary emission of a blue LED.
In particular, the dichromatic approach as disclosed, for example, in U.S. Patent 5,998,925, uses a blue light emitting diode of InGaN-based semiconductor material combined with an Y3Al5O12 :Ce phosphor (YAG-Ce3+). The YAG-Ce 3+ phosphor is coated on the InGaN LED, and a portion of the blue light emitted from the LED is converted into yellow light by the phosphor. Another portion of the blue light from the LED is transmitted through the phosphor. Thus, this system emits both blue light, emitted from the LED, and yellow light emitted from the phosphor. The mixture of blue and yellow emission bands is perceived as white light by an observer, with a typical CRI in the middle 70ties and a color temperature Tc that ranges from about 6000 K to about 8000 K.
A concern with the illumination system according to US 5,998,925 is again that there are color point variations among the blue light emitting InGaN-based diodes that affect the quality control of the illumination systems based on such diodes.
BRIEF SUMMARY OF THE INVENTION
Therefore, there is a need to provide new illumination systems providing a radiation source for light in the blue range of the electromagnetic spectrum with a constant color point that is independent of drive and temperature. The present invention provides an illumination system comprising a primary radiation source, preferably providing UV radiation, and a luminescent material comprising at least one phosphor capable of absorbing part of radiation emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said at least one phosphor is a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr1-x-yCaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0 < x ≤ l; 0 ≤ y < l;0.001 < z < 0.4, 0 < a < 2 and 0 < b < 2.
Especially contemplated as a radiation source is a UV radiation emitting diode providing UV radiation in the range from 370 to 400 nm. An illumination system according to the present invention can provide a blue output light that is a well defined and has constant color point. In particular, the blue output light is independent of drive and temperature. This characteristic makes the device ideal for applications in which a reproducible true color rendering and a large color gamut is required.
Such applications of the invention include inter alia general display applications. These illumination systems are also bright enough to be seen in broad daylight and are therefore useful as high ambient panel indicators as well as general-purpose indicators, marker lights, warning lights, and backlights for cellular telephones. According to a first aspect of the invention, a blue-light illumination system comprises a UV light emitting diode having a peak emission wavelength in the range of 370 to 400 nm as a radiation source and a luminescent material comprising at least one phosphor, which is a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr1-x-yCaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0<x≤l;0≤y <l;0.001≤z<0.4, 0<a<2 andθ≤b<2.
Such an illumination system will provide blue light with a constant color point in operation. The blue light emitted by the LED excites the phosphor, causing it to reemit blue light. The viewer perceives the blue reemitted radiation.
According to a second aspect, the invention provides a white-light illumination system comprising a UV light emitting diode having a peak emission wavelength in the range of 370 to 400 nm as a radiation source and a luminescent material comprising a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula(Sr1-x-yCaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0<x≤l;0≤y< 1 ;0.001 < z < 0.4, 0 < a < 2 and 0 < b < 2 and at least one second phosphor. In particular, the luminescent material of this embodiment may be a phosphor blend comprising a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr1-x-yCaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0<x≤l;0≤y < 1 ;0.001 < z < 0.4, 0<a<2and0≤b<2, and a yellow to red phosphor.
Such a yellow to red phosphor may be selected from the group of Eu(II)-activated phosphors, more particularly selected from the group defined by (Ca1-xSrx) S:Eu, wherein 0 < x < 1, (Sr1-x-yBaxCay )2-zSi5-aAlaN8-aOa:Euz wherein 0<a<5, 0<x≤l,0< y < 1, and 0 < z < 1, and (Y5Gd)3Al5O12)Ce.
Such an illumination system will provide dichromatic white light in operation. Part of the UV radiation emitted by the LED excites the blue-emitting phosphor, causing it to reemit blue light. Another part of the UV-radiation and/or the blue reemitted radiation is absorbed by the second phosphor and reemitted as yellow to red light. The viewer perceives the mixture of blue and yellow to red light as white light. According to a further embodiment, the luminescent material of this embodiment may be a phosphor blend comprising a blue light emitting europium(II)-activated alkaline earth oxo-nitridosilicate of general formula(Sr1-x-yCaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0 < x ≤ l; 0 < y < l;0.001 < z < 0.4, 0 < a < 2 and 0 ≤ b < 2, a yellow to red phosphor, and a green phosphor. Such an illumination system will provide trichromatic white light in operation.
Part of the UV radiation emitted by the LED excites the blue light emitting phosphor according to the invention, causing it to reemit blue light. Part of the UV radiation and/or the reemitted blue radiation is also absorbed by the second phosphor and reemitted as yellow to red light. Another part of the UV radiation and/or the reemitted blue radiation is absorbed by the third phosphor and reemitted as green light. The viewer perceives the mixture of blue, yellow to red, and green light as white light.
Another aspect of the present invention provides a phosphor capable of absorbing part of the light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said phosphor is a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr1 -x- yCaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0 < x ≤ l; 0 ≤ y < l;0.001 < z < 0.4, 0 < a < 2 and 0 < b < 2.
An essential factor is that the blue phosphors of the europium(II)- activated alkaline earth oxo-nitridosilicate type have a small Stokes shift. They can therefore very efficiently be excited by primary radiation of 370 to 400 nm. Thus the luminescent material has ideal characteristics for conversion of UVA-radiation into blue light. Total conversion efficiency can be up to 90 %.
These phosphors are narrow-band emitters wherein the visible emission is so narrow that there is a 36-nm wavelength range where the visible emission is predominantly located. Therefore these europium(II)-activated alkaline earth oxo- nitridosilicate phosphors emit this narrow band in the blue spectral range of the visible spectrum with very high efficiency. The remaining quantum loss caused by the Stokes shift of the phosphors is compensated for by the higher internal quantum efficiency of an illumination system comprising a UV LED and a blue phosphor according to the invention as compared with a blue, directly emitting LED used as a source of blue radiation. Additional important characteristics of the phosphors include 1) resistance to thermal quenching of luminescence at typical device operating temperatures (e.g. 80°C); 2) lack of interfering reactivity with the encapsulating resins used in the manufacture of the device; 3) suitable absorptive profiles to minimize dead absorption within the visible spectrum; 4) a invariant luminous output over the operating lifetime of the device, and 5) the possibility of compositionally controlled tuning of the phosphors' excitation and emission properties.
In particular, the invention relates to the specific phosphor composition SrSi6N8:Euz, wherein 0.01 < z < 0.4, which exhibits a high quantum efficiency of 80 - 90 %, a high absorbance of 60-80% in the range from 370 nm to 400 nm, an emission spectrum with a peak wavelength of about 453nm, and low losses, below 10% of the luminescent lumen output, caused by thermal quenching from room temperature to 100 °C.
A specific phosphor composition of formula Sr1-z/2Si6N8Oa :Euz, wherein 0 < a < 1 and 0.001 < z < 0.2 (= Sr2-zSi12N16Oa :Euz, wherein 0 < a < 2 and 0.001 < z < 0.4) is especially valuable as a phosphor in white light emitting phosphor-converted LEDs with low color temperatures and improved color rendering.
Specific preferred phosphor compositions also comprise europium(II)- activated barium oxo-nitridosilicate of the general formula Ba1-z/2Si6N8Oa :Euz, wherein 0 < a < 1 and 0.001 < z < 0.2 (= Ba2-2Si12N16O3 :Euz, wherein 0 < a < 2 and 0.001 < z < 0.4)
These phosphors may have a coating selected from the group of fluorides and orthophosphates of the elements aluminum, scandium, yttrium, lanthanum, gadolinium, and lutetium, the oxides of aluminum, yttrium, and lanthanum, and the nitride of aluminum.
DETAILED DESCRIPTION OF THE INVENTION
The present invention focuses on a europium(II)-activated alkaline earth oxo- nitridosilicate as a phosphor in any configuration of an illumination system containing a radiation source, including, but not limited to discharge lamps, luminescent lamps, LEDs, LDs, and X-ray tubes. As used herein, the term "radiation" preferably covers radiation in the UV and visible ranges of the electromagnetic spectrum. While the use of the present phosphor is contemplated for a wide array of illumination applications, the present invention is described with particular reference to and finds particular application in illumination systems comprising light-emitting diodes, especially diodes that emit UV radiation.
The luminescent material according to the invention comprises as a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula
(Sr1-x-yCaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0 < x ≤ l; 0 < y < l;0.001 < z < 0.4, 0 < a < 2 and 0 < b < 2. This class of phosphor materials is based on an activated luminescence of a substituted alkaline earth oxo-nitridosilicate.
The phosphor of the general formula (Sr1-x-yCaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0 < x ≤ l; 0 ≤ y < l;0.001 < z < 0.4, 0 < a < 2 and 0 ≤ b < 2 comprises a host lattice with the main components of silicon, nitrogen, and possibly oxygen in a three-dimensional network, as is shown in Figs. 5 and 6. The three-dimensional network is built up from group units consisting of SiN4- and Si(SiN3)- tetrahedrons, sharing vertices so as to form a three-dimensional framework comprising Si-Si-bonds. Fig. 5 shows the crystal structure of the basic host lattice SrSi6N8, wherein the strontium cations may be replaced by europium(II) cations as well as other alkaline earth metals. If the phosphor comprises oxygen, then Si-Si bonds are oxidized to form regular Si-O- Si. bonds as shown in Fig.6. There may be an isoelectronic substitution of Si-N-bonds by Al-O bonds. The alkaline earth cations of strontium, calcium, and barium as well as europium and possibly a co-activator populate a single lattice site only, where they are coordinated exclusively by nitrogen atoms.
The host lattice for these materials may be a four-element (two cations) oxo-nitridosilicate such as europium(II)-activated strontium oxo-nitridosilicate SrSi6N8:Eu, or may comprise more that four elements such as europium(II)-activated strontium-barium oxo-nitridosilicate (Sr, Ba)Si6N8Oa:Eu.
In replacing alkaline earth metals with the rare earth metal Eu, the proportion preferably lies within the range from 0.999: 0.001 to 0.8: 0.4. Similarly, the alkaline earth metals may be mutually substituted. If the proportion z of europium (II) is 0.001 or lower, luminance decreases because the number of excited photoluminescence emission centers constituted by europium(II)-cations decreases and density quenching occurs if z is above 0. 2. Density quenching is a decrease in emission intensity that occurs when the concen- tration of an activation agent added to increase the luminance of the luminescent material is increased beyond an optimum level.
The phosphors according to the invention can be especially excited by a radiation source providing UV emission with wavelengths of 370 to 400 nm, such as a UV LED. Thus the luminescent material has ideal characteristics for converting UV radiation of nitride semiconductor light-emitting diodes into blue light.
The method of producing a europium(II)-activated alkaline earth oxo- nitridosilicate phosphor of the present invention is not particularly restricted, and it can be implemented by firing any mixture of starting materials that provide a europium(II)-activated alkaline earth oxo-nitridosilicate luminescent material. Starting materials having a high purity of 99.9% or more and taking form of fine particles having an average particle size of 1 μm or less are preferably used.
In the first place, the starting materials, i.e. alkaline earth carbonates, euro- pium(III) compounds such as the oxide together with a carbon modification as a reducing agent, and a silicon-nitrogen compound such as silicon diimide or silicon nitride, are well mixed in a dry and/or wet process utilizing any of various known mixing method such as ball mills, V-shaped mixers, stirrers, and the like.
The obtained mixture is placed in a heat-resistant container such as an alumina crucible and a tungsten boat, and then fired in an electric furnace. A preferred firing temperature lies between 1,200 and 1,5000C. The firing atmosphere is not particularly restricted, for example, it is preferable to fire in a reducing atmosphere such as an atmosphere comprising an inert gas such as nitrogen and argon and the like, and hydrogen in a proportion of 0.1 to 10 volume%. The firing period is determined subject to various conditions such as the quantity of mixture charged in the container, the firing temperature, and the temperature at which the product is removed from the furnace, but it generally lies in the range of 2 to 4 hours.
Luminescent material obtained by the above method may be ground by means of, for example, a ball mill, a jet mill, and the like. It may subsequently be washed and classified. Re-firing is suggested for enhancing the cristallinity of the resulting granular phosphor.
The resulting luminescent material is then ground, washed with water and ethanol, dried, and sieved. A bluish powder is obtained, which efficiently luminesces in the blue range of the electromagnetic spectrum under UV excitation. For example, one of the preferred compounds represented by SrSi6N8: Eu(II) is produced by the method where europium(III) oxide Eu2O3, strontium carbonate SrCO3, and silicon nitride Si3N4 together with microcrystalline graphite as the starting materials are weighed and compounded to give a molar ratio of by SrSi6N8: Eu whereupon they are fired in a reducing atmosphere. After drying and sieving, the powders were characterized by powder X- ray diffraction (Cu, Kα-line), which showed that all compounds had formed. Fig. 4 shows the X-ray diffraction data of SrSi6N8 :Eu.
Each phosphor of the europium(II)-activated alkaline earth oxo- nitridosilicate type exhibits a bluish fluorescence when excited by radiation of the UVA range of the electromagnetic spectrum. Fig. 7 of the drawings accompanying this specification gives the emission and reflection spectra of SrSi6N8 :Eu2%.
When excited by radiation of 365 nm wavelength, the SrSi6N8 :Eu2% phosphor is found to give a narrow band emission with a peak wavelength at 453 nm. The phosphor SrSi6N8: Eu is resistant to heat, light, and moisture because of its oxo- nitridosilicate host lattice.
Preferably, the europium(II)-activated alkaline earth oxo-nitridosilicate type phosphors according to the invention may be coated with a thin, uniform protective layer of one or more compounds selected from the group formed by the fluorides and orthophosphates of the elements aluminum, scandium, yttrium, lanthanum, gadolinium, and lutetium, the oxides of aluminum, yttrium, and lanthanum, and the nitride of aluminum.
The protective layer thickness customarily ranges from 0.001 to 0.2 nm and is thus so thin that it can be penetrated by the radiation of the radiation source without any substantial loss of energy. The coatings of these materials on the phosphor particles may be applied, for example, by deposition from the gas phase or a wet coating process.
The invention also relates to an illumination system comprising a radiation source and a luminescent material comprising at least one phosphor that is a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr1-X- yCaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0 < x ≤ l; 0 ≤ y < l;0.001 < z < 0.4, 0 < a < 2 and 0 < b < 2.
Radiation sources include semiconductor optical radiation emitters and other devices that emit optical radiation in response to electrical excitation. Semiconductor optical radiation emitters include light-emitting diode LED chips, light-emitting polymers (LEPs), organic light-emitting devices (OLEDs), polymer light-emitting devices (PLEDs), etc.
Moreover, light-emitting components such as those found in discharge lamps and fluorescent lamps, such as mercury low and high pressure discharge lamps, sulfur discharge lamps, and discharge lamps based a molecular radiators are also contemplated for use as radiation sources with the present inventive phosphor compositions.
In a preferred embodiment of the invention, the radiation source is a light-emitting diode (LED).
Any configuration of an illumination system which includes a light- emitting diode and a europium(II)-activated alkaline earth oxo-nitridosilicate phosphor composition is contemplated in the present invention, preferably with the addition of other well-known phosphors, which can be combined to achieve a specific color or white light when irradiated by a LED that emits primarily UV radiation as specified above. A detailed construction of one embodiment of such an illumination system as shown in Fig.l, comprising a radiation source and a luminescent material, will now be described.
FIG. 1 is a schematic view of a chip-type light-emitting diode with a coating comprising the luminescent material. The device comprises the chip-type light-emitting diode (LED) 1 as a radiation source. The light-emitting diode dice is positioned in a reflector cup lead frame 2. The dice 1 is connected via a bond wire 7 to a first terminal 6 and directly to a second electric terminal 6. The recess of the reflector cup is filled with a coating material that contains a luminescent material according to the invention to form a coating layer that is embedded in the reflector cup. The phosphors are applied either separately or in a mixture.
The coating material typically comprises a polymer 5 for encapsulating the phosphor or phosphor blend. In this embodiment, the phosphor or phosphor blend should exhibit high stability properties against the encapsulant. Preferably, the polymer is optically clear to prevent significant light scattering. A variety of polymers are known in the LED industry for making LED illumination systems.
The polymer is preferably selected from the group consisting of epoxy and silicone resins. Adding of the phosphor mixture to a liquid that is a polymer precursor can perform encapsulation. For example, the phosphor mixture may be a granular powder. The introduction of phosphor particles into the polymer precursor liquid results in the formation of a slurry (i.e. a suspension of particles). Upon polymerization, the phosphor mixture is fixed rigidly in place by the encapsulation. In one embodiment, both the luminescent material and the LED dice are encapsulated in the polymer.
The transparent coating material may comprise light-diffusing particles, advantageously so-called diffusers. Examples of such diffusers are mineral fillers, in particular CaF2, Tiθ2, Siθ2, CaCθ3 or BaSO4 or any other organic pigments. These materials can be added to the above-mentioned resins in a simple manner.
According to another embodiment of phosphor-converted light- emitting diodes, the luminescent material is provided as a coating on the light-emitting diode dice. Such a coating may comprise a single layer comprising the blue-emitting phosphor according to the invention, as shown in Fig. 2. Alternatively, such a coating may comprise two or more layers comprising the blue-emitting phosphor according to the invention in a first layer and second phosphors in second layers, as shown in Fig. 3.
In operation, electrical power is supplied to the dice to activate the dice. When activated, the dice emits the primary radiation, e.g. UV radiation. The emitted primary light is absorbed by the luminescent material in the coating layer. The luminescent material then emits secondary light, i.e., the converted light having a longer peak wavelength, primarily blue in a narrow band in response to absorption of the primary radiation.
According to a first aspect of the invention, an illumination system that emits output light having a spectral distribution such that it appears to be "blue" light is contemplated.
Luminescent material comprising europium(II)-activated alkaline earth oxo-nitridosilicate as a phosphor is particularly well suited as a blue component for stimulation by a primary UVA radiation source such as, for example, a UVA-emitting LED
In one embodiment, a blue light emitting illumination system according to the invention can advantageously be produced in that the luminescent material is selected from the luminescent materials that comprise an europium(II)-activated alkaline earth oxo-nitridosilicate phosphor, such that a UV radiation emitted by the UV light emitting diode is converted into higher wavelength ranges to form monochromatic blue light.
Particularly good results are achieved with a UV-LED whose emission maximum lies at 370 to 400 nm. An optimum was found to lie at 390 nm, taking particular account of the excitation spectrum of the oxo-nitridosilicate.
A blue light emitting illumination system according to the invention can particularly preferably be realized by admixing an excess of the inorganic luminescent material SrSi6N8 :Eu(2%) to a silicon resin used to produce the luminescence conversion encapsulation or layer. Part of a radiation emitted by a UV-emitting diode is shifted by the inorganic luminescent material SrSi6N8 :Eu(2%) into the blue spectral region of the electromagnetic spectrum.
According to another aspect of the invention, the output light of the illumination system may have a spectral distribution such that it appears to be "white" light.
In a preferred embodiment, a white light emitting illumination system according to the invention can advantageously be produced in that the luminescent material is chosen such that a UV radiation emitted by a UV light emitting diode is converted into complementary wavelength ranges so as to form dichromatic white light. In this embodiment, yellow to red as well as blue light is produced by means of the luminescent materials. Blue light is produced by the luminescent materials that comprise a europium(II)-activated alkaline earth oxo-nitridosilicate phosphor. Yellow to red light may be preferably produced by the luminescent materials that comprise a phosphor selected from the group comprising (Ca1-xSrx) S:Eu, wherein 0 < x < 1 , (Sr1-x-yBaxCay )2-zSi5-aAlaN8-aOa:Euz, wherein 0 < a < 5, 0 < x < l, 0 ≤ y ≤ l, and 0 < z < 0.09, and (Y5Gd)3Al5O12)Ce.
Also, a second yellow to red emitting luminescent material may be used in addition in order to improve the color rendition of this illumination system. Particularly good results are achieved in conjunction with a UVA light emitting diode whose emission maximum lies at 370 to 400 nm. An optimum was found to lie at 390 nm, taking particular account of the excitation spectrum of the europium(II)-activated alkaline earth oxo-nitridosilicate. Part of a blue radiation emitted by a UVA-emitting diode is shifted by the inorganic luminescent material, e.g. SrSi6N8 :Eu(2%), into the blue spectral region and another part is shifted into the yellow to orange spectral region, i.e. into a wavelength range which is complementarily colored with respect to the color blue. A human observer perceives the combination of blue primary light and the secondary light of the yellow to orange emitting phosphor as white light.
The color output of an LED's phosphor system is very sensitive to the thickness of the phosphor layer. If the phosphor layer is thick and comprises an excess of a yellow phosphor, then a lesser amount of the blue light will penetrate through the thick phosphor layer. The combined LED / phosphor system will then appear yellow to red, because it is dominated by the yellow to red secondary light of the phosphor.
Therefore, the thickness of the phosphor layers is a critical variable affecting the color output of the system.
The hue (color point in the CIE chromaticity diagram) of the white light thereby produced can be varied in this case by a suitable choice of the phosphors in respect of their mixing ratio, their particle sizes, and their concentrations. These arrangements also afford the possibility of using optimized phosphor blends in the luminescent material, as a result of which, advantageously, the desired hue can be set even more accurately.
In a further embodiment, a white light emitting illumination system according to the invention can advantageously be produced by choosing the luminescent material such that a radiation emitted by the UV light emitting diode is converted into complementary wavelength ranges so as to form trichromatic white light, e.g. by means of additive color triads, for example blue, green, and red.
In this case, trichromatic white light is produced by means of the luminescent materials that comprise a blend of phosphors including a blue-emitting europium(II)-activated alkaline earth oxo-nitridosilicate phosphor, a second phosphor emitting in the red spectral range, and a third phosphor emitting in the green spectral range.
A white light emission with high color rendering can be obtained especially with the use of red and green broad-band emitter phosphors covering the entire spectral range together with a UV-emitting LED and a blue-emitting europium(II)-activated alkaline earth oxo-nitridosilicate phosphor.
The hue (color point in the CIE chromaticity diagram) of the white light thus produced can be varied in this case by a suitable choice of the phosphors in respect of their mixing ratio and concentrations.
Useful second phosphors and their optical properties are summarized in the following table 2.
Table 2.
Figure imgf000015_0001
The luminescent materials for trichromatic white light may preferably comprise besides the blue-emitting phosphor according to the invention, a red phosphor selected from the group comprising (Ca1-xSrx) S:Eu, wherein 0 < x < 1, and (Sr1-X- yBaxCay )2-zSi5-aAlaN8-aOa:Euz, wherein 0 < a < 5, 0 < x < l, 0 ≤ y < l and 0 < z < 0.09, and (Y5Gd)3 Al5O12:Ce, and a green phosphor selected from the group comprising (Bai_xSrx)2 SiC^: Eu, wherein 0 < x < 1, SrGa2S4 :Eu, and SrSi2N2U2:Eu.
In a preferred embodiment, a white-light emitting illumination system according to the invention can particularly preferably be realized by admixing the inorganic luminescent material comprising a mixture of three phosphors to a silicon resin used to produce the luminescence conversion encapsulation or layer. A first phosphor (1) is the blue-emitting alkaline earth oxo-nitridosilicate SrSi6N8: Eu, the second phosphor (2) is the red-emitting CaS: Eu, and the third (3) is a green-emitting phosphor of the type SrSi2N2U2:Eu.
Part of a UV radiation emitted by a UV-emitting diode is shifted by the inorganic luminescent material SrSi6N8: Eu into the blue spectral region. Another part of the radiation emitted by the UV-emitting diode is shifted by the inorganic luminescent material CaS: Eu into the red spectral region. Still another part of the radiation emitted by the UV-emitting diode is shifted by the inorganic luminescent material SrSi2N2U2: Eu into the green spectral region. A human observer perceives the polychromatic secondary light of the phosphor blend as white light.
The hue (color point in the CIE chromaticity diagram) of the white light thus produced can be varied in this case by a suitable choice of the phosphors in respect of their mixing ratio and concentration
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic view of a dichromatic white LED lamp comprising a phosphor of the present invention together with a yellow to orange phosphor positioned in a pathway of light emitted by an UV-LED structure. FIG. 2 is a schematic view of a monochromatic blue LED lamp.
FIG. 3 is a schematic view of a dichromatic white LED lamp.
FIG. 4 shows the XRD pattern of SrSi6N8 : Eu(II) measured by Cu Ka radiation.
FIG. 5 shows the three-dimensional network structure of the host lattice SrSi6N8.
FIG. 6 shows the three-dimensional network structure of the host lattice SrSi6N8O. FIG. 7 shows emission and reflection spectra of SrSi6N8 :Eu(II).

Claims

CLAIMS:
1. Illumination system comprising a radiation source and a luminescent material comprising at least one phosphor capable of absorbing part of the light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said at least one phosphor is a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr1-x-y-CaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein0<x<l;0<y≤l;0.001 <z<0.4, 0 <a<2 andO <b<2.
2. Illumination system according to claim 1, wherein the radiation source is a light-emitting diode.
3. Illumination system according to claim 1, wherein the radiation source is selected from the light-emitting diodes having an emission with a peak emission wavelength in a range of 370 to 400 nm.
4. Illumination system according to claim 1, wherein the radiation source is selected from the light-emitting diodes having an emission with a peak emission wavelength in a range of 370 to 400 nm, and the luminescent material comprises a europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr1-x-y- CaxBay)2-zAlbSi12-bN16-bOa+b :Euz, wherein 0≤x≤l;0≤y≤ l;0.001 < z < 0.4, 0 < a < 2 and 0 < b < 2 and a second phosphor.
5. Illumination system according to claim 4, wherein the second phosphor is a yellow to red emitting phosphor selected from the group of (Ca1-xSrx) S:Eu, wherein 0 < x < 1, (Sr1-x-yBaxCay )2-zSi5-aAlaN8-aOa:Euz, wherein 0<a<5, 0<x≤l,0≤y≤l, and 0 < z < 0.09, and (Y5Gd)3Al5O12)Ce.
6. Illumination system according to claim 4, wherein the second phosphor is a green-emitting phosphor selected from the group comprising (Ba1-X Srx)2 SiO^Eu, wherein 0 < x < 1, and SrGa2S4 :Eu.
7. Phosphor capable of absorbing a part of the light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said phosphor is an europium(II)-activated alkaline earth oxo-nitridosilicate of the general formula (Sr1-x-yCaxBay)2-zAlbSi12-bN16-bOa+b ^Eu2, wherein 0 < x ≤ l; 0 < y < l;0.001 < z < 0.4, 0 < a < 2 and O < b < 2.
8. Phosphor according to claim 12, wherein said phosphor additionally comprises a co-activator.
9. Phosphor according to claim 7, wherein said phosphor is a europium(II)- activated alkaline earth oxo-nitridosilicate of the general formula Sr1-z/2Si6N8Oa :Euz, wherein 0 < a < 1 and 0.001 < z < 0.2.
10. Phosphor according to claim 7, wherein said phosphor is a europium(II)- activated alkaline earth oxo-nitridosilicate of the general formula Ba1-z/2Si6N8Oa :Euz, wherein 0 < a < 1 and 0.001 < z < 0.2.
11. Phosphor according to claim 7, wherein the phosphor has a coating selected from the group of fluorides and orthophosphates of the elements aluminum, scandium, yttrium, lanthanum, gadolinium, and lutetium, the oxides of aluminum, yttrium, and lanthanum, and the nitride of aluminum.
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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008010498A1 (en) * 2006-07-18 2008-01-24 Showa Denko K.K. Phosphor, method for production thereof, and light-emitting apparatus
WO2008052772A1 (en) 2006-11-02 2008-05-08 Max-Planck-Gesellschaft Zur Förderung Der Wiessenschaften E.V. Light source
EP2308946A3 (en) * 2006-03-10 2011-08-31 Kabushiki Kaisha Toshiba Luminescent material and light-emitting device
WO2012012041A1 (en) * 2010-07-22 2012-01-26 General Electric Company Oxynitride phosphors, method of preparation, and light emitting instrument
US8329484B2 (en) 2010-11-02 2012-12-11 Tsmc Solid State Lighting Ltd. Phosphor with Ce3+/Ce3+, Li+ doped luminescent materials
US8343785B2 (en) 2010-11-30 2013-01-01 Taiwan Semiconductor Manufacturing Company, Ltd. Nitridosilicate phosphor tunable light-emitting diodes by using UV and blue chips
CN103045257A (en) * 2011-10-17 2013-04-17 北京有色金属研究总院 Nitride luminescent material and luminescent device prepared from same
WO2013108782A1 (en) * 2012-01-17 2013-07-25 三菱化学株式会社 Oxynitride-based phosphor and light emitting device using same
CN103484110A (en) * 2013-09-06 2014-01-01 北京科技大学 Red silicon-aluminum oxynitride fluorescent material and preparation method thereof
US8716731B2 (en) 2011-04-11 2014-05-06 Tsmc Solid State Lighting Ltd. Tunable phosphor for luminescent
EP3133135A1 (en) * 2011-01-18 2017-02-22 Sharp Kabushiki Kaisha Semiconductor light-emitting device

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1264873A2 (en) * 2001-06-07 2002-12-11 National Institute for Materials Science Oxynitride phosphor activated by a rare earth element, and sialon type phosphor
US6717353B1 (en) * 2002-10-14 2004-04-06 Lumileds Lighting U.S., Llc Phosphor converted light emitting device
WO2004036962A1 (en) * 2002-10-14 2004-04-29 Philips Intellectual Property & Standards Gmbh Light-emitting device comprising an eu(ii)-activated phosphor
WO2004084261A2 (en) * 2003-03-17 2004-09-30 Philips Intellectual Property & Standards Gmbh Illumination system comprising a radiation source and a fluorescent material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1264873A2 (en) * 2001-06-07 2002-12-11 National Institute for Materials Science Oxynitride phosphor activated by a rare earth element, and sialon type phosphor
US6717353B1 (en) * 2002-10-14 2004-04-06 Lumileds Lighting U.S., Llc Phosphor converted light emitting device
WO2004036962A1 (en) * 2002-10-14 2004-04-29 Philips Intellectual Property & Standards Gmbh Light-emitting device comprising an eu(ii)-activated phosphor
WO2004084261A2 (en) * 2003-03-17 2004-09-30 Philips Intellectual Property & Standards Gmbh Illumination system comprising a radiation source and a fluorescent material

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SHEN Z ET AL: "PREPARATION AND CRYSTAL STRUCTURE OF A NEW SR CONTAINING SIALON PHASE SR2AIXSI12-XN16-XO2+X (X=2)", JOURNAL OF MATERIALS CHEMISTRY, THE ROYAL SOCIETY OF CHEMISTRY, CAMBRIDGE, GB, vol. 9, no. 4, April 1999 (1999-04-01), pages 1019 - 1022, XP000849099, ISSN: 0959-9428 *

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8450923B2 (en) 2006-03-10 2013-05-28 Kabushiki Kaisha Toshiba Luminescent material and light-emitting device
US8491817B2 (en) 2006-03-10 2013-07-23 Kabushiki Kaisha Toshiba Luminescent material and light-emitting device
US8482192B2 (en) 2006-03-10 2013-07-09 Kabushiki Kaisha Toshiba Luminescent material and light-emitting device
EP2308946A3 (en) * 2006-03-10 2011-08-31 Kabushiki Kaisha Toshiba Luminescent material and light-emitting device
US8475680B2 (en) 2006-03-10 2013-07-02 Kabushiki Kaisha Toshiba Luminescent material and light-emitting device
US8153023B2 (en) 2006-07-18 2012-04-10 Showa Denko K.K. Phosphor, method for production thereof, and light-emitting apparatus
WO2008010498A1 (en) * 2006-07-18 2008-01-24 Showa Denko K.K. Phosphor, method for production thereof, and light-emitting apparatus
JP2008024741A (en) * 2006-07-18 2008-02-07 Showa Denko Kk Phosphor, its manufacturing method and light emitting device
US8339032B2 (en) 2006-11-02 2012-12-25 MAX-PLANCK-Gesellschaft zur Förderung der Wissenschaften e.V. Light source with luminophore layer
WO2008052772A1 (en) 2006-11-02 2008-05-08 Max-Planck-Gesellschaft Zur Förderung Der Wiessenschaften E.V. Light source
WO2012012041A1 (en) * 2010-07-22 2012-01-26 General Electric Company Oxynitride phosphors, method of preparation, and light emitting instrument
US8329484B2 (en) 2010-11-02 2012-12-11 Tsmc Solid State Lighting Ltd. Phosphor with Ce3+/Ce3+, Li+ doped luminescent materials
US8343785B2 (en) 2010-11-30 2013-01-01 Taiwan Semiconductor Manufacturing Company, Ltd. Nitridosilicate phosphor tunable light-emitting diodes by using UV and blue chips
US9711686B2 (en) 2011-01-18 2017-07-18 Sharp Kabushiki Kaisha Lighting device with plural fluorescent materials
EP3133135A1 (en) * 2011-01-18 2017-02-22 Sharp Kabushiki Kaisha Semiconductor light-emitting device
US8716731B2 (en) 2011-04-11 2014-05-06 Tsmc Solid State Lighting Ltd. Tunable phosphor for luminescent
CN103045257A (en) * 2011-10-17 2013-04-17 北京有色金属研究总院 Nitride luminescent material and luminescent device prepared from same
CN103045257B (en) * 2011-10-17 2015-09-23 有研稀土新材料股份有限公司 A kind of nitride luminescent material and the luminescent device adopting this luminescent material to make
WO2013108782A1 (en) * 2012-01-17 2013-07-25 三菱化学株式会社 Oxynitride-based phosphor and light emitting device using same
CN103484110A (en) * 2013-09-06 2014-01-01 北京科技大学 Red silicon-aluminum oxynitride fluorescent material and preparation method thereof

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