WO2012023737A2 - Light emitting device having surface-modified silicate luminophores - Google Patents
Light emitting device having surface-modified silicate luminophores Download PDFInfo
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- WO2012023737A2 WO2012023737A2 PCT/KR2011/005842 KR2011005842W WO2012023737A2 WO 2012023737 A2 WO2012023737 A2 WO 2012023737A2 KR 2011005842 W KR2011005842 W KR 2011005842W WO 2012023737 A2 WO2012023737 A2 WO 2012023737A2
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- luminophore
- emitting device
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- emitting diode
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- 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
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- 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
- C09K11/77342—Silicates
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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
- C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
- C09K11/025—Use of particular materials as binders, particle coatings or suspension media therefor non-luminescent particle coatings or suspension media
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- 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
- H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
- H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
- H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
- H01L2224/321—Disposition
- H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
- H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
- H01L2224/32245—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
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- 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
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- 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
- H01L2224/481—Disposition
- H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
- H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
- H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
- H01L2224/48247—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
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- 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
- H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
- H01L2224/732—Location after the connecting process
- H01L2224/73251—Location after the connecting process on different surfaces
- H01L2224/73265—Layer and wire connectors
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- 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
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- 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
- H01L2924/19—Details of hybrid assemblies other than the semiconductor or other solid state devices to be connected
- H01L2924/191—Disposition
- H01L2924/19101—Disposition of discrete passive components
- H01L2924/19107—Disposition of discrete passive components off-chip wires
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- 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
Definitions
- Exemplary embodiments of the present invention relate to light emitting devices having inorganic luminophores based on doped alkaline earth metal silicate compounds which are capable of converting high-energy primary radiation, i.e., for example, ultraviolet (UV) radiation or blue light, to a longer-wavelength secondary radiation within the visible spectral region, which can be used as radiation converters in light-emitting devices such as color or white-light emitting light emitting diodes (LEDs).
- Exemplary embodiments of the present invention also relate to light emitting devices having silicatic inorganic luminophores which may have improved stability to air humidity and other environmental factors, and increased operational lifetime.
- Luminophores may be used in light sources, such as LEDs that emit colored or white light.
- luminophores which may be used in combination with other luminophores, are used to convert ultraviolet or blue primary radiation emitted from an LED into longer wavelength secondary radiation, in particular, white light.
- Alkaline earth metal silicate luminophores which include the europium-doped alkaline earth metal orthosilicates, the corresponding oxyorthosilicates and the disilicates of the Ba(Sr)3MgSi208:Eu form, have been known for some time.
- An overview of the classification of the alkaline earth metal silicate compounds is documented by Hollemann-Wiberg, "Lehrbuch der Anorganischen Chemie” Inorganic Chemistry, 102 edition, (Walter de Gruyter & Co., Berlin, 2007). The preparation and the essential luminescence properties thereof have been described in detail in various patents and publications, for example: U.S. Pat. No. 6,489,716, issued to Tews, et al.; EP Appl.
- the luminophores based on the alkaline earth metal silicates also have various disadvantageous properties. Some of the disadvantages include a comparatively low radiation stability and high sensitivity of the luminophores to water, air humidity, and other environmental factors. The sensitivity depends on the particular composition of the luminophore, structural conditions, and the nature of activator ions of the luminophores. For some of the current applications of wavelength-conversion luminophores, these properties may be problematic. In view of the high lifetime demands, this may apply to LED applications.
- One known solution is to use suitable technologies and materials to generate (on the surface of pulverulent inorganic luminophores) barrier layers for reducing the influence of water vapour.
- These processes may include encapsulation with organic polymers, coating with nanoscale oxides such as Si02 or A1203, or chemical vapour deposition (CVD) of such oxides.
- CVD chemical vapour deposition
- the protection achievable may be insufficient to improve the lifetime of corresponding LED lamps to the desired degree.
- coated luminophores it may be necessary to accept losses in brightness, shifts in the color location, and other quality losses. Processes for microencapsulation of the luminophore particles by means of gas phase processes may be inconvenient and costly.
- Exemplary embodiments of the present invention provide light emitting devices employing silicate luminophores that may provide moisture stability, stability to radiation and other environmental influences, and improved operational lifetime.
- Exemplary embodiments of the present invention also provide light emitting devices employing luminophores that have been subjected to a surface treatment with fluorinated inorganic or organic agents.
- Exemplary embodiments of the present invention also provide detectable fixing of finely dispersed fluorides or fluorine compounds on the luminophore surface or the formation of surface networks of such compounds which are capable of making the luminophore surfaces hydrophobic and may cure surface defects.
- P10-5083
- An exemplary embodiment of the present invention discloses a light emitting device including a first light emitting diode and a surface-modified luminophore configured to absorb light emitted from the first light emitting diode and configured to emit light having a different wavelength from the absorbed light, wherein the surface-modified luminophore includes a silicate luminophore and a fluorinated coating arranged on the silicate luminophore.
- Fig. 1 is a cross-sectional view of a light emitting device 100, according to an exemplary embodiment of the present invention.
- Fig. 2 is a cross-sectional view of a light emitting device 200, according to an exemplary embodiment of the present invention.
- Fig. 3 is a cross-sectional view of a light emitting device 300, according to an exemplary embodiment of the present invention.
- Fig. 4 is a cross-sectional view of a light emitting device 400, according to an exemplary embodiment of the present invention.
- Fig. 5 is a cross-sectional view of a light emitting device 500, according to an exemplary embodiment of the present invention.
- Fig. 6a is emission spectra of a reference material Sr2.9Ba0.01Ca0.05Eu0.04SiO5, a commercial Sr3Si05:Eu luminophore, and oxyorthosilicate luminophores F-103, F-202, F-202T, F-320 and F-TS-600 according to exemplary embodiments of the present invention.
- Fig. 6b is emission spectra of reference material Sr0.876Bal.024Eu0.1SiO4 and two alkaline earth metal orthosilicate luminophores F-401 and F-401TS according to exemplary embodiments of the present invention.
- Fig. 7a is electron micrographs of non-fluorinated and fluorinated alkaline earth metal oxyorthosilicate luminophores, showing untreated particles of the luminophore Sr2.9Ba0.01Ca0.05SiO on the left and fluorinated particles of the luminophore F-202 according to an exemplary embodiment of the present invention on the right.
- Fig. 7b is magnified electron micrographs of the surface of the luminophore F-202 according to an exemplary embodiment of the present invention.
- Fig. 8 are electron micrographs of uncoated, fluorinated, and Si02-coated alkaline earth metal orthosilicate luminophores of the base lattice composition Sr0.876Bal.024SiO4:Eu0.1, showing a scanning electron micrograph of the uncoated starting material on the left, the fluorinated luminophore surface in the middle, and a luminophore sample additionally coated with Si02 on the right according to an exemplary embodiment of the present invention.
- Fig. 9 is an energy-dispersive X-ray (EDX) spectroscopic image of the luminophore F- 103 with manifested fluorinated surface structure according to an exemplary embodiment of the present invention.
- EDX energy-dispersive X-ray
- Fig. 10 is an X-ray photoelectron (XPS) spectrum of the luminophore F-103 accordinging to an exemplary embodiment of the present invention.
- XPS X-ray photoelectron
- Fig. 11 is a graph showing representative fluorine XPS peaks for different luminophore samples.
- Curve 1 relates to the mechanical mixture of the luminophore having the composition Sr2.9Ba0.01Ca0.05Eu0.04SiO5 with an amount of NH4F according to working example Al
- curve 2 relates to the fluorine Is peak of the fluorinated luminophore F-103 according to an exemplary embodiment of the present invention.
- a light emitting device includes a light emitting diode that emits light in the UV or visible range, and a surface-modified luminorphore disposed around the light emitting diode to absorb at least a portion of light emitted from the light emitting diode and to emit light having a different wavelength from the absorbed light.
- the luminophores according to exemplary embodiments of the present invention may emit visible light and infrared radiation with high radiation yields and significantly improved stability to H20, air humidity, and other environmental factors compared to the prior art. For this reason, they may be used in long-life industrial products, for example in cathode ray tubes and other image- generating systems (scanning laser beam systems) in X-ray image converters, high-performance light sources, LEDs of all colors for interior and exterior illumination, backlighting of LCD displays, solar cells, greenhouse films, and glasses as radiation converters.
- Luminophores according to exemplary embodiments of the present invention may be characterized in that the surface thereof has a coating of fluorinated inorganic or organic agents for generation of hydrophobic surface sites, or of a combination of the fluorinated coating with one or more moisture barrier layers.
- Luminophores, including surface-modified silicate luminophores, according to exemplary embodiments of the present invention may include pulverulent alkaline earth metal silicate luminophores.
- the surface-modified silicate luminophores may have the general formula:
- A is an activator selected from the group of the lanthanoids or manganese; F is a surface fixed and optionally cross-linked fluorine or fluorine compounds; and S characterizes an optional additional coating with non-fluorinated layer- forming materials.
- Mel+ is a monovalent metal, Me2+ is a divalent metal and Me3+ is a trivalent metal selected from group III of the Periodic Table or from the lanthanoids.
- Some of the silicon may be replaced by P, Al, B, V, N, Ge, or C.
- the coefficients x, y, and z may have the following ranges: 0 ⁇ x ⁇ 5, 0 ⁇ y ⁇ 12, and 0 ⁇ z ⁇ 24.
- some of the alkaline earth metal ions in the surface-modified silicate luminophores may be replaced by further divalent ions, for example Mg, Zn, or, with implementation of suitable measures for balancing the charge, monovalent or trivalent cations from the group of alkali metals or of the rare earths.
- P, B, V, N, Ge, or C can be incorporated into an anion sublattice of the surface-modified silicate luminophores replacing some of the silicon.
- the surface-modified silicate luminophores according to exemplary embodiments of the present invention may be characterized by the general formula:
- the surface-modified silicate luminophores may also be characterized by the formula:
- the light emitting device may emit white light or a desired color of light through a combination of the light emitted from the light emitting diode and the luminophore.
- other luminophores may be added to the light emitting device to emit another desired color of light.
- the luminophores may be disposed on at least one of lateral, upper, and lower sides of the light emitting diode. Further, the luminophores may be mixed with an adhesive or a molding material, which may be disposed on the light emitting diode.
- the light emitting diode and the luminophores may be combined in a single package.
- the light emitting device may further include another light emitting diode in the package.
- the other light emitting diode may emit light having the same wavelength as, or a different wavelength from, the light emitted from the light emitting diode.
- the other light emitting diode may emit light having a longer wavelength than an emission peak wavelength of the luminophore.
- the package may include a substrate such as a printed circuit board or lead frame, on which the light emitting diode is mounted.
- the package may further include a reflector that reflects light emitted from the light emitting diode.
- the light emitting diode is mounted within the reflector.
- the light emitting device may further include a molding member that encapsulates the light emitting diode on the substrate.
- the luminophores may be dispersed in the molding member, but are not limited thereto.
- the package may further include a heat sink, and the light emitting diode may be mounted on the heat sink.
- the light emitting diode may be formed of (Al, Ga, In)N-based compound semiconductors.
- the light emitting diode may have, for example, a double-hetero structure, a single quantum well structure, or multi-quantum well structure, wherein a single active region is arranged between an n-type semiconductor layer and a p-type semiconductor layer.
- the light emitting diode may further include a plurality of light emitting cells that are separated from each other and disposed on a single substrate. Each of the light emitting cells may have an active region.
- the light emitting cells may be electrically connected to one another in series and/or in parallel, via wires. With these light emitting cells, it is possible to provide an alternating current (AC) light emitting diode which may be directly driven by an AC power P10-5083 supply.
- AC-light emitting diode may be driven without an additional AC/DC converter, by forming a bridge rectifier and serial arrays of light emitting cells connected to the bridge rectifier on a single substrate, or by forming serial arrays of light emitting cells connected in reverse-parallel to one another on a single substrate.
- FIG. 1 is a cross-sectional view of a light emitting device 100 according to an exemplary embodiment of the present invention.
- the light emitting device 100 may be referred to as a chip-type package.
- electrodes 5 may be formed on both sides of a substrate 1, and a light emitting diode 6 to emit primary light may be mounted on one of the electrodes 5, at one side of the substrate 1.
- the light emitting diode 6 may be mounted on the electrode 5 via an electrically conductive adhesive 9, such as Ag epoxy, and may be electrically connected to the other electrode 5 via an electrically conductive wire 2.
- the light emitting diode 6 emits light in the ultraviolet range or visible range and may be formed of gallium nitride-based compound semiconductors.
- the light emitting diode 6 may emit UV or blue light.
- Luminophores 3 may be dotted on upper and side surfaces of the light emitting diode 6.
- the luminophores 3 are dotted around the light emitting diode 3, but are not limited to any particular configuration.
- the luminophores 3 may be uniformly distributed within the molding member 10.
- the luminophores 3 absorb at least a portion of light emitted from the light emitting diode 6 and emit light having a different wavelength from the absorbed light.
- the light emitting diode 6 is electrically connected to an external power supply via the electrodes 5 and thus, may emit primary light.
- the luminophores 3 absorb at least a portion of the primary light and emit secondary light having a wavelength that is longer than that of the primary light.
- the primary light and the secondary light are mixed to form mixed light, which is emitted from the light emitting device 100.
- a desired color of light for example white light, may be realized in this manner.
- the light emitting device 100 may include one or more additional light emitting diodes. These light emitting diodes may emit light having the same emission peaks or different emission peaks. For example, the light emitting device 100 may include the same or different types of light emitting diodes, each of which can emit ultraviolet or blue light. Furthermore, the light emitting device 100 may include a light emitting diode that can emit light having a longer wavelength than the emission peak wavelength of the luminophores. Such a longer wavelength light emitting diode may be employed to improve a color rendering index of the light emitting P10-5083 device 100. Moreover, the light emitting device 100 may further include other luminophores in addition to the luminophores 3.
- Examples of the other luminophores include, but are not limited to, orthosilicate luminophores, Yttrium Aluminum Garnet (YAG) based luminophores, and thiogallate luminophores. Accordingly, a desired color of light may be achieved by the proper selection of the light emitting diodes 6 and luminophores.
- YAG Yttrium Aluminum Garnet
- FIG 2 is a cross-sectional view of a light emitting device 200, according to another exemplary embodiment of the present invention.
- the light emitting device 200 may be referred to as a top-view type package.
- the light emitting device 200 has a similar structure to the light emitting device 100 and further includes a reflector 21 on a substrate 1.
- a light emitting diode 6 is mounted in the reflector 21.
- the reflector 21 reflects light emitted from the light emitting diode 6, to increase brightness within a certain viewing angle.
- Luminophores 3 are disposed around the light emitting diode 6, absorb at least a portion of the light emitted from the light emitting diode 6, and emit light having a different wavelength than the absorbed light.
- the luminophores 3 may be dotted on the light emitting diode 6 or may be uniformly distributed within a thermosetting resin molding member 10.
- the light emitting device 200 may also include one or more additional light emitting diodes, which emit light having the same emission peaks or different emission peaks from one another, and may further include other luminophores in addition to the luminophores 3.
- the light emitting devices 100, 200 may include substrates 1 formed of a metallic material, for example a metal printed circuit board (PCB), which exhibits good thermal conductivity. Such a substrate may easily dissipate heat from the light emitting diode 6. Further, a lead frame including lead terminals may be used as the substrate 1. Such a lead frame may be surrounded and supported by the molding member 10, which encapsulates the light emitting diode 6.
- a metallic material for example a metal printed circuit board (PCB)
- PCB metal printed circuit board
- the reflector 21 may be formed of a different material from the substrate 1, although is not limited thereto.
- the reflector 21 may be formed of the same type of material as the substrate 1.
- a lead frame having lead terminals may be integrally formed with the substrate 1 and reflector 21, by insert-molding plastics such as polyphthalamide (PPA). Then, the lead terminals may be bent to form the electrodes 5.
- PPA polyphthalamide
- FIG. 3 is a cross-sectional view of a light emitting device 300, according to another exemplary embodiment of the present invention.
- the light emitting device 300 may be referred to as a light emitting diode lamp.
- the light emitting device 300 includes a P10-5083 pair of lead electrodes 31, 32 and a cup portion 33 having a cup shape, at an upper end of one lead electrode 31.
- At least one light emitting diode 6 may be mounted in the cup portion 33 via an electrically conductive adhesive 9 and electrically connected to the other lead electrode 32 via a conductive wire 2.
- the light emitting diodes may emit light having the same wavelength or different wavelengths from one another.
- Luminophores 3 are disposed around the light emitting diode 6.
- the luminophores 3 absorb at least a portion of light emitted from the light emitting diode 6 and emit light having a different wavelength from that of the absorbed light.
- the luminophores 3 may be dotted on the light emitting diode 6 in the cup portion 33, or uniformly distributed within a thermosetting resin molding member 34 formed in the cup portion 33.
- a molding member 10 encapsulates the light emitting diode 6, the luminophores, and a portion of the lead electrodes 31, 32.
- the molding member 10 may be formed of, for example, epoxy or silicone.
- the light emitting device 300 includes the pair of lead electrodes 31, 32. However, the light emitting device 300 may have more lead electrodes than the pair of lead electrodes 31, 32.
- FIG. 4 is a cross-sectional view of a light emitting device 400, according to yet another exemplary embodiment of the present invention.
- the light emitting device 400 may be referred to as a high-power light emitting diode package.
- the light emitting device 400 includes a heat sink 41 that is received in a housing 43.
- the heat sink 41 has a bottom surface that is exposed to outside.
- Lead electrodes 44 are exposed within the housing 43 and extend outside through the housing 43.
- At least one light emitting diode 6 may be mounted on an upper surface of the heat sink 41, via an electrically conductive adhesive 9.
- the light emitting diode 6 is electrically connected to one of the lead electrodes 44, via an electrically conductive wire 2.
- another electrically conductive wire 2 connects the other lead electrode 44 to the heat-sink 41, such that the light emitting diode 6 may be electrically connected to each of the two lead electrodes 44.
- Luminophores 3 are disposed around the light emitting diode 6, on the heat-sink 41.
- the luminophores 3 adsorb at least a portion of light emitted from the light emitting diode 6 and emit light having a different wavelength from that of the absorbed light.
- the luminophores 3 may be dotted on the light emitting diode 6, or uniformly distributed within a molding member (not shown), to cover the light emitting diode.
- FIG. 5 is a cross-sectional view of a light emitting device 500, according to yet another exemplary embodiment of the present invention.
- the light emitting device 500 includes a housing 53 and a plurality of heat-sinks 51, 52 that may be joined to the housing 53 and insulated from each other.
- Light emitting diodes 6, 7 are mounted on the heat-sinks 51, 52, via an electrically conductive adhesive.
- the light emitting diodes 6, 7 are electrically connected to lead electrodes 54, via respective electrically conductive wires (not shown).
- the lead electrodes 54 extend from the inside of the housing 53 to the outside.
- Each of the light emitting diodes 6, 7 is connected to two of the lead electrodes 54, but more lead electrodes may be provided thereto.
- Luminophores 3 may be disposed around at least one of the light emitting diodes 6 or 7, as described with reference to Figure 4.
- the light emitting diode 6 may be mounted on the substrate 1 or on the heat-sink 41, via the electrically conductive adhesive 9, and electrically connected to the electrode or lead electrode via the electrically conductive wire 2.
- the light emitting diode 6 is a "two-bond die", which has two electrodes on the top side thereof, the light emitting diode 6 may be electrically connected to the electrodes or lead electrodes via two electrically conductive wires, respectively.
- the adhesive need not be electrically conductive.
- the light emitting diode 6 may be formed of an (Al, Ga, In)N-based composite semiconductor.
- the light emitting diode 6 may have, for example, a double hetero-structure, single quantum well structure, or multi-quantum well structure, which may have a single active region arranged between n-type and p-type semiconductor layers.
- Luminophore powders used as the basis for the preparation of the surface-modified luminophores 3 may be synthesized by multistage high-temperature solid-state reactions at temperatures above 1000°C between the alkaline earth metal carbonates that may be used as the starting material or the corresponding metal oxides and Si02. Additionally, mineralization additives (e.g. NH4C1, NH4F, or alkali metal or alkaline earth metal halides or halides of the trivalent metals) may be added to the reaction mixture to promote reactivity and to control the particle size distribution of the resulting luminophores.
- mineralization additives e.g. NH4C1, NH4F, or alkali metal or alkaline earth metal halides or halides of the trivalent metals
- the desired compositions of the doped alkaline earth metal silicate luminophores more particularly the corresponding ortho- and oxyortho-silicate luminophores.
- the calculated amounts of the starting materials are mixed vigorously and then subjected to a multistage calcination process in an inert or reducing atmosphere within the PI 0-5083 desired temperature range.
- the main calcination process may optionally also have several calcination stages within different temperature ranges.
- the samples are cooled to room temperature and subjected to suitable aftertreatment processes that are directed, for example, to the elimination of flux residues, to the minimization of surface defects, or else to the tine adjustment of the particle size distribution.
- silicon oxide instead of the silicon oxide, it is alternatively also possible to use silicon nitride (Si3N4) or other silicon- containing precursors as reactants for the reaction with the alkaline earth metal compounds used.
- Si3N4 silicon nitride
- the synthesis of the polycrystalline luminophore powders used for the production of exemplary embodiments of the luminophores is not restricted to the preparation processes described above.
- inorganic fluorine compounds may be used such as alkali metal fluorides (e.g. LiF, NaF, KF) alkaline earth metal fluorides (MgF2, CaF2, SrF2, BaF2), A1F3 and fluorides of the rare earths (e.g. YF3, LaF3 or GdF3), NH4F and NH4HF2, and also other inorganic or organic fluorine compounds (e.g. fluoride-containing amines).
- alkali metal fluorides e.g. LiF, NaF, KF
- MgF2, CaF2, SrF2, BaF2 alkaline earth metal fluorides
- A1F3 and fluorides of the rare earths e.g. YF3, LaF3 or GdF3
- NH4F and NH4HF2 NH4F and NH4HF2
- fluoride-containing amines e.g. fluoride-containing amines
- the fluorinated luminophores are removed from the suspension, and may be washed with suitable solvents and then dried at temperatures between 80°C and 200°C. After cooling and screening, they are in a form ready for use.
- Working Example Al describes the preparation of a luminophore provided with a fluorinated surface layer and having the base lattice composition P10-5083
- Table 1 contains optical and moisture stability data of europium-activated strontium oxyorthosilicate luminophore samples which have been treated with different amounts of NH4F.
- the stoichiometric amounts of SrC03, BaC03, CaC03, Eu203, and Si02 and 0.2 mol of NH4C1 are mixed vigorously and then subjected, in corundum crucibles, to a 5-hour calcination process at 1400°C in an N2/H2 atmosphere containing 2% hydrogen. After the calcination process has ended, the calcinated material is homogenized, ground and washed with H20.
- the optical data of which are specified in Table 2 and the emission spectrum of which is designated as "4" in Fig. 6a 100 g of the luminophore matrix described in Working Example Al are mixed with 2.474 g of NH4HF2.
- Table 2 contains optical and moisture stability data of europium-activated strontium oxyorthcsilicate luminophore samples which have been treated with different amounts of NH4HF2.
- the fluorinated surface layer is applied by wet-chemical precipitation by taking the mixture in 1 L of deionized water and 400 g of glass beads on a roll mill. Treatment for one hour is followed by the removal of the coated luminophore from the solution and an after-treatment analogous to Working Example Al.
- An oxyorthosilicate luminophore with a base lattice composition Sr2.948Ba0.01Cu0.002SiO5:Eu0.04 is synthesized in the solid state according to Working Example Al and coated with an Si02 network using precursor material tetraethoxysilane (TEOS).
- TEOS precursor material tetraethoxysilane
- 50 g of the luminophore are mixed with 500 mL of a solution of 1 L of ethanol, 18.2 g of TEOS and 100 mL of 32% aqueous ammonia, and stirred in a reaction vessel for 2 hours. Thereafter, the coated luminophore is filtered with suction, washed with ethanol, and dried at 160°C for 24 hours.
- the luminophore is subjected, as in Working Example Al, to fluorination by NH4F as the fluorinating agent.
- NH4F as the fluorinating agent.
- 80 g of the precoated luminophore is reacted with 1.98 g of NH4F under the conditions of Working Example Al.
- the luminophore according to the present exemplary embodiment is thus produced, in the form of sample F-TS-600.
- the optical data of which are described in Table 6, and the emission spectrum of which is designated as "7" in Fig.
- a base lattice of the composition Sr2.9485Ba0.01Cu0.0015SiO5:Eu0.04 is synthesized.
- the stoichiometric amounts of SrC03, BaC03,CuO,Eu203, 65 g of Si02 and 0.3 mol of NH4C1 are mixed, introduced into suitable calcining crucibles and calcined in a high-temperature furnace for a period of 24 hours.
- the calcination program has two main calcination zones at 1200°C and 1350°C for 3 hours at each temperature. During the first calcination phase, calcination is effected under forming gas with hydrogen concentration 5%, and the hydrogen concentration is increased to 20% in the subsequent second phase of calcination.
- the fluorinating agent used is aluminium fluoride A1F3 instead of the NH4F or the NH4HF2.
- A1F3 aluminium fluoride A1F3
- the mixture is stirred vigorously for 1 hour.
- 100 g of the luminophore matrix synthesized are added to the suspension.
- the reaction time may be 60 minutes.
- the coated luminophore in the form of sample F-320 is after-treated similarly to Working Examples Al, A2, A3, and A4.
- the optical data are shown in Table 3, and the emission spectrum thereof is designated as "6" in Fig. la.
- Table 3 contains optical and stability data of further fluorinated Eu2+-doped strontium oxyortho silicate luminophores.
- the base material is produced by a high-temperature solid-state reaction wherein the starting mixture comprises stoichiometric amounts of SrC03, BaC03, Eu203, Si02, and 0.2 mol of NH4C1.
- the calcination process includes heating the crucible filled with the starting mixture to 1275°C in a nitrogen atmosphere, maintaining this temperature over a period of 10 hours and subsequently cooling to room temperature. On attainment of the high-temperature ramp, 20% hydrogen is added to the protective gas. After cooling, the resulting materials are subjected to washing to remove flux residues, and then dried and screened.
- the luminophore according to the present exemplary embodiment in the form of sample F-401 may be provided with an Si02 coating.
- 50 g of the fluorinated Sr0.876Bal.024SiO4:Eu0.1 luminophore powder are added to 500 mL of TEOS solution consisting of 1 L of ethanol, 25 g of TEOS and 150 mL of 32% aqueous ammonia, which has been prepared 24 hours before use. After a stirring time of 5 hours, reaction is terminated.
- the surface-coated luminophore in the form of sample F-401TS is filtered with P10-5083 suction, washed with ethanol again, and dried.
- the optical data of the sample F-401TS are specified in Table 4, F-401TS's emission spectrum is designated as "4" in Fig. lb.
- Fig. la and Fig. 6b show that the luminescence intensities of the luminophores with fluorinated surface structure according to the exemplary embodiments of the present invention differ slightly from those of the reference material. This is also confirmed by the luminescence data of the luminophore samples according to exemplary embodiments compiled in Table 1, Table 2, Table 3, Table 4, Table 5, Table 6, and Table 7 while somewhat lower luminescence intensities were measured in some cases for fluorinated and optionally additionally Si02 coated samples. There are also examples in the tables referred to for surface treatment leading to a slight increase in luminescence efficiency. The latter effect may be attributed to the somewhat better emission of light in the case of the coated materials.
- FIG. 7a and Fig. 7b electron micrographs of a fluorinated Sr3Si05:Eu luminophore according to exemplary embodiments of the present invention are compared to those of the untreated starting material. These micrographs demonstrate that the surface treatment, described in the working examples, with suitable fluorinating agents leads to the formation of specific surface structures, which can be visualized with the aid of scanning electron micrographs.
- the situation is comparable for the electron micrographs shown in Fig. 8 for green- wavelength light-emitting alkaline earth metal orthosilicate luminophores.
- the micrographs in Fig. 8 show the characteristic particle surface of an untreated luminophore sample, that of the fluorinated material produced in accordance with the exemplary embodiments of the present invention, and that of a further sample derived from the starting material, which had additionally been coated with Si02.
- Fig. 10 and Fig. 11 Further evidence for the fixing of finely dispersed fluorides or of fluorine compounds or for the formation of networks of such compounds on the surface of the luminophores according to exemplary embodiments of the present invention is documented in Fig. 10 and Fig. 11 by the results of X-ray photoelectron spectroscopy (XPS) analyses . Fixing may include adsorption and like means for chemisorption or physisorption. The XPS spectrum, shown in Fig.
- the lower intensity of the F Is peak of the sample labeled as curve 2 can be interpreted as loss of some of the added fluorine from the luminophore surface during processing.
- the shift in the F 1 s peak to lower binding energies of curve 1 may indicate formation of a chemical bond between the applied fluorinating agent and the surface of the luminophore matrix.
- Table 1 Table 2, Table 3, Table 4, Table 5, and Table 6, several luminescence parameters of different silicatic luminophores configured in accordance with exemplary embodiments of the present invention and the results of the stability tests are compiled and compared with those of the unchanged (i.e., non-fluorinated surface) luminophore powders and in some cases with those of commercial comparative luminophores.
- Table 5 contains optical and stability data of fluorinated and of fluorinated and Si02-coated Eu2+-coated strontium oxyorthosilicate luminophores.
- Table 6 contains optical and stability data of Si02-coated strontium oxyorthosilicate luminophores that have been fluorinated.
- the moisture stability of the materials was assessed by storage of the corresponding luminophore samples in a climate-controlled cabinet, which was operated at a temperature of 85°C and 85% air humidity, for seven days. Subsequently, the luminophores were dried at 150°C for 24 hours and then subjected to a comparative measurement of the luminescence yield. P10-5083
- results of the comparative luminescence measurements demonstrate that both the luminescence efficiencies of the luminophores according to exemplary embodiments of the present invention and the temperature dependencies thereof are equal to those of commercial europium-activated alkaline earth metal oxyorthosilicate or corresponding orthosilicate luminophores, or even exceed them.
- results of the stability tests show that the luminophores according to exemplary embodiments of the present invention with fluorinated surface structure and optional additional Si02 coating, as shown in Table 4, Table 5, and Table 6, have significantly improved moisture resistances compared to unchanged (i.e. non-fluorinated surface) luminophores of the same matrix composition.
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BR112013003417-3A BR112013003417B1 (en) | 2010-08-14 | 2011-08-11 | LIGHT EMITTING DEVICE HAVING SILICATE LUMINOPHORS WITH MODIFIED SURFACE |
JP2013524040A JP2013541828A (en) | 2010-08-14 | 2011-08-11 | Light emitting device having surface-modified silicate illuminant |
RU2013111293/28A RU2569167C2 (en) | 2010-08-14 | 2011-08-11 | Led with silicate luminophors with modified surface |
CN201180039661XA CN103081140A (en) | 2010-08-14 | 2011-08-11 | Light emitting device having surface-modified silicate luminophores |
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US20080135862A1 (en) | 2001-09-03 | 2008-06-12 | Matsushita Electric Industrial Co., Ltd. | Light-emitting semiconductor device, light-emitting system and method for fabricating light-emitting semiconductor device |
JP2005187797A (en) | 2003-12-05 | 2005-07-14 | Toshiba Corp | Phosphor and light emitting device using the same |
WO2011045359A1 (en) | 2009-10-15 | 2011-04-21 | Leuchtstoffwerk Breitungen Gmbh | Alkaline earth metal silicate luminophores and method for improving the long-term stability thereof |
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