JP2012229373A - Coated fluorescent substance and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated fluorescent substance particle capable of further improving incident efficiency of exciting light into a fluorescent particle and luminous efficiency of the fluorescent particle by a simple configuration.SOLUTION: The coated fluorescent substance includes a fluorescent particle and a coating layer for covering the outside the fluorescent particle. The coating layer includes a parent phase formed by metal oxide and a metal oxide particle whose refractive index is higher than that in the parent phase. The metal oxide particle is dispersed in the parent phase and exists while the metal oxide particle concentration of the coating layer decreases as separating from the fluorescent particle.

Description

  The present invention relates to a coated phosphor and a light emitting device including the coated phosphor.

  A light-emitting device including a light-emitting element such as a light-emitting diode (LED) and a phosphor that converts the wavelength of light emitted from the light-emitting element is small in size, consumes less power than an incandescent bulb, and is intended for use in white It is possible to emit light of an appropriate color according to. For this reason, such a light-emitting device includes a liquid crystal display, a backlight light source in a liquid crystal display device such as a mobile phone or a portable information terminal, a display device used for indoor / outdoor advertisements, indicators of various portable devices, and an illumination switch. It can be used as a light source for OA (office automation) equipment.

  When converting the wavelength of light emitted from the light emitting element with a phosphor, a wavelength conversion member including a translucent medium and phosphor particles dispersed in the translucent medium is often used. When light emitted from the light emitting element enters the wavelength conversion member, the light travels through the translucent medium and enters the phosphor particles. Thereby, the phosphor particles are excited, and the phosphor particles emit fluorescence having a wavelength longer than that of the incident light (excitation light). Thereby, wavelength conversion of light is performed.

  However, since the refractive index of the translucent medium formed from glass, silicone resin, or the like is lower than the refractive index of the phosphor particles, a part of the light directed to the phosphor particles in the translucent medium is translucent medium. And total reflection at the interface between the phosphor particles. For this reason, the incident efficiency of the excitation light to the phosphor particles is lowered, and accordingly, the extraction efficiency of the converted light from the phosphor particles (the luminous efficiency of the phosphor particles) is also lowered.

  Therefore, in Patent Document 1, in order to realize a light emitting device with improved wavelength conversion efficiency by improving the incident efficiency of excitation light to the phosphor and the extraction efficiency of the fluorescence from the phosphor, oxynitride and / or Alternatively, the wavelength conversion is made of a phosphor made of nitride having a refractive index n1 and a phosphor covering the phosphor particle and a film having a refractive index n2, and a medium having a refractive index n3 in which the phosphor is dispersed. In the member, a wavelength conversion member is disclosed in which the refractive index n2 of the film is a value between n3 and n1.

  However, even in the technique described in Patent Document 1, since the refractive index is discontinuously changed at the interface between the medium and the coating film and at the interface between the coating film and the phosphor particles, the light traveling toward the phosphor particles Some of the light is reflected at the interface between the medium and the coating or at the interface between the coating and the phosphor particles. Therefore, the incident efficiency of the excitation light to the phosphor particles and the luminous efficiency of the phosphor particles are not sufficiently high.

JP 2007-324475 A

  The present invention has been made in view of the above reasons, and it is possible to further improve the incident efficiency of excitation light to the phosphor particles and further improve the light emission efficiency of the phosphor particles with a simple configuration. An object of the present invention is to provide coated phosphor particles.

  The coated phosphor according to the present invention includes phosphor particles and a coating layer that covers the outside of the phosphor particles, and the coating layer is formed of a metal oxide and is refracted more than the matrix phase. The metal oxide particles are dispersed in the matrix and the concentration of the metal oxide particles in the coating layer decreases as the distance from the phosphor particles increases. ing.

  In the coated phosphor according to the present invention, it is preferable that the matrix is formed of silicon oxide formed from at least one selected from silicon alkoxide, silicon alkoxide derivatives, and partial hydrolysis condensates thereof.

  In the coated phosphor according to the present invention, it is also preferable that the matrix is formed of silica formed by converting polysilazane.

  In the present invention, the material of the metal oxide particles is at least one selected from aluminum oxide, titanium dioxide, zirconium oxide, niobium oxide, tin oxide, germanium oxide, and yttrium oxide, and the particles of the metal oxide particles It is also preferable that the diameter is 1 nm or more and 100 nm or less.

  The light emitting device according to the present invention includes the coated phosphor.

  According to the present invention, it is possible to further improve the incident efficiency of the excitation light to the phosphor particles and the luminous efficiency of the phosphor particles with a simple configuration.

It is the schematic which shows the cross-section of the coated fluorescent substance in one Embodiment of this invention, and a wavelength conversion member provided with this coated fluorescent substance. It is a graph which shows the image of the ideal refractive index change of the covering fluorescent substance and translucent medium in one Embodiment of this invention. It is a partially broken disassembled perspective view which shows the light-emitting device in one Embodiment of this invention. It is sectional drawing of the said light-emitting device.

  In the present embodiment, as shown in FIG. 1, the coated phosphor 100 includes phosphor particles 101 and a coating layer 102 that covers the outside of the phosphor particles 101. FIG. 1 schematically shows a cross-sectional structure of the wavelength conversion member 70 with the coated phosphor 100 and the translucent medium 72.

There is no particular limitation on the phosphors of the phosphor particles 101, for example, _{^{CaAlSiN 3: Eu 2+, (Ca}} , Sr) AlSiN 3: Eu 2+, CaS: Eu 2+, (Ca, Sr) 2 Si 5 N 8 : Red phosphor having a composition such as Eu ²⁺ ; CaSc ₂ O ₄ : Ce ³⁺ , Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce ³⁺ , (Ca, Sr, Ba) Al ₂ O ₄ : Eu ²⁺ , SrGa ₂ S ₄ : a green phosphor having a composition such as Eu ²⁺ ; a yellow phosphor having a composition such as Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , (Ca, Sr, Ba, Zn) ₂ SiO ₄ : Eu ²⁺ ; _Sr) 2 _SiO 4: yellow-green phosphor having a composition of ^{Eu 2+} and the _{^{like; Sr 3 SiO 5: Eu 2+}} , Ca 0.7 Sr 0.3 AlSiN 3: orange having a composition of ^{Eu 2+} and the like Such as phosphor, and the like.

  There is no particular limitation on the particle size of the phosphor particles 101. However, the larger the particle size of the phosphor particles 101, the lower the defect density in the phosphor particles 101. Therefore, the energy loss during light emission is reduced and the light emission efficiency is increased. In particular, the median diameter (D50) of the phosphor particles 101 is preferably in the range of 4 to 30 μm. This median diameter (D50) is a volume-based median diameter and is measured by a laser diffraction type scattering particle size distribution measuring instrument.

  The covering layer 102 includes a parent phase 104 formed from a metal oxide and metal oxide particles 103. The metal oxide particles 103 are dispersed in the matrix phase 104.

  The metal oxide particles 103 have a refractive index higher than that of the parent phase 104. Furthermore, the concentration of the metal oxide particles 103 in the coating layer 102 decreases as the distance from the phosphor particles 101 increases (that is, as the outer surface side of the coating layer 102 is approached). For this reason, the refractive index of the coating layer 102 gradually decreases (ideally continuously) as it moves away from the phosphor particles 101 (that is, as it approaches the outer surface side of the coating layer 102).

  When the coated phosphor 100 includes such a coating layer 102, between the interface between the coating layer 102 and the translucent medium 72 when the coated phosphor 100 is disposed in the translucent medium 72. And reflection of light at the interface between the coating layer 102 and the phosphor particles 101 can be suppressed. That is, since the refractive index of the coating layer 102 gradually decreases as the distance from the phosphor particle 101 increases, the refractive index of the outer surface side portion of the coating layer 102 approaches the refractive index of the translucent medium 72, and the fluorescence of the coating layer 102. The refractive index of the coating layer 102 can be controlled such that the refractive index of the body particle 101 side portion is close to the refractive index of the phosphor particles 101 and the refractive index gradually changes in the coating layer 102. For this reason, the reflection of light at the interface between the translucent medium 72 and the coating layer 102 is suppressed, the reflection of light at the interface between the coating layer 102 and the phosphor particles 101 is also suppressed, and the reflection in the coating layer 102 is further suppressed. Light reflection is also suppressed. Thereby, the incident efficiency of the excitation light to the phosphor particles 101 is increased, and the luminous efficiency of the phosphor particles 101 is improved accordingly.

  Ideally, the refractive index of the coating layer 102 matches the refractive index of the phosphor particles 101 at the interface with the phosphor particles 101 as shown in FIG. The refractive index of the conductive medium 72 is adjusted so that the refractive index continuously changes inside the coating layer 102. In this case, there is no discontinuous change in the refractive index at the interface between the coated phosphor 100 and the translucent medium 72 and the inside of the coated phosphor 100, and therefore, the excitation light to the phosphor particles 101 does not exist. The incident efficiency is significantly increased, and the luminous efficiency of the phosphor particles 101 is significantly improved.

  The material of the metal oxide particles 103 is preferably a metal oxide that can transmit excitation light to the phosphor particles 101 and fluorescence emitted from the phosphor particles 101. Although the refractive index of the metal oxide particles 103 needs to be larger than the refractive index of the parent phase 104, the refractive index of the metal oxide particles 103 is preferably equal to or higher than the refractive index of the phosphor particles 101. In this case, the refractive index of the phosphor layer 101 side portion of the coating layer 102 can be easily adjusted so as to approximate the refractive index of the phosphor particle 101.

  In particular, the difference in refractive index between the metal oxide particles 103 and the phosphor particles 101 is preferably in the range of 0.1 to 0.7.

  The difference between the refractive index of the coating layer 102 at the interface with the phosphor particles 101 and the refractive index of the phosphor particles 101 is preferably in the range of 0 to 0.2.

  Preferable materials for the metal oxide particles 103 include aluminum oxide (refractive index 1.65 to 1.76), titanium dioxide (refractive index 2.1 to 2.7), and zirconium oxide (refractive index 1.9 to 2.76). 5) at least selected from niobium oxide (refractive index 1.9 to 2.4), tin oxide (refractive index 1.8 to 1.99), and yttrium oxide (refractive index 1.8 to 1.91). One kind is mentioned. The refractive index of the metal oxide particles 103 varies depending on the crystallinity of the metal oxide particles 103 and the like.

  Furthermore, the average particle diameter of the metal oxide particles 103 is preferably 1 nm or more and 100 nm or less. In this case, since the average particle diameter of the metal oxide particles 103 is 1 nm or more, sufficiently high crystallinity of the metal oxide particles 103 is ensured, and deterioration of the refractive index of the metal oxide particles 103 is suppressed. When the average particle size is 100 nm or less, light scattering by the metal oxide particles 103 is suppressed, and the light transmittance of the coating layer 102 is sufficiently increased. The average particle diameter of the metal oxide particles 103 is an average particle diameter on a volume basis measured by a dynamic light scattering method.

The ratio of the metal oxide particles 103 to the entire coating layer 102 is appropriately set, but in order to sufficiently adjust the refractive index of the coating layer 102 and sufficiently ensure the high light transmittance of the coating layer 1, It is preferably 10% by volume or more, and more preferably 30% by volume or more. This ratio is preferably 80% by volume or less, more preferably 70% by volume or less, and further preferably 50% by volume or less. In particular, the ratio of the metal oxide particles 103 to the entire coating layer 102 is preferably in the range of 10 to 80% by volume, more preferably in the range of 30 to 70% by volume, and in the range of 30 to 50% by volume. The material of the mother phase 104 is preferably a material that transmits excitation light to the phosphor particles 101 and fluorescence emitted from the phosphor particles 101. Further, the parent phase 104 is preferably formed of a material having a refractive index lower than the refractive index of the phosphor particles 101 and approximate to the refractive index of the translucent medium 72 in the wavelength conversion member 70. In this case, reflection of light at the interface between the coating layer 102 and the translucent medium 72 is particularly suppressed. The parent phase 104 is preferably formed from, for example, a metal oxide generated from at least one selected from metal alkoxides, metal alkoxide derivatives, and partial hydrolysis condensates thereof.

  In particular, the parent phase 104 is preferably formed from silicon oxide produced from at least one selected from silicon alkoxides, derivatives of silicon alkoxides, and partial hydrolysis condensates thereof. In this case, the refractive index of the parent phase 104 is very close to that of a silicon compound or glass that is suitable as a material for the translucent medium 72.

  In particular, the difference in refractive index between the parent phase 104 and the translucent medium 72 is preferably in the range of 0 to 0.02.

  Moreover, it is preferable that the difference between the refractive index of the coating layer 102 at the interface with the translucent medium 72 and the refractive index of the translucent medium 72 is in the range of 0 to 0.04.

  As the metal alkoxide for forming the parent phase 104, a compound having a structure represented by the following chemical formula (1) (hereinafter referred to as a first metal alkoxide; for example, when the metal is silicon, the first silicon alkoxide Said). In the first metal alkoxide, only the alkoxide group is bonded to the metal atom. In the metal oxide produced from at least one selected from the first metal alkoxide, the derivative of the first metal alkoxide, and the partial hydrolysis condensate thereof (hereinafter referred to as the first metal alkoxide, etc.) The crosslink density becomes higher. For this reason, the mother phase 104 becomes very dense.

M ¹ (OR ¹ ) _m (1)
In the chemical formula (1), M ¹ is a metal atom selected from Si, Ti, Al, Zr, Ge, and Y. m is a number equal to the valence of the metal atom M ^1.

R ¹ is selected from an alkyl group and hydrogen. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. When a plurality of R ¹ are present in one molecule, the plurality of R ¹ may be the same as or different from each other. For example, R ¹ may be all alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group, R ¹ may be all hydrogen, or some of the plurality of R ¹ are alkyl groups. And the remainder may be all hydrogen.

As a specific example of the first metal alkoxide,
Substituted or unsubstituted alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetrakis (2-methoxyethoxy) silane;
Aluminum triethoxide, aluminum tri-n-propoxide, aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum triisobutoxide, aluminum tri-sec-butoxide, aluminum tri-tert-butoxide, aluminum tris (hexyl oxide) ), Aluminum tris (2-ethylhexyl oxide), aluminum tris (2-methoxyethoxide), aluminum tris (2-ethoxyethoxide), aluminum tris (2-butoxyethoxide), etc., substituted or unsubstituted aluminum alkoxides Kind;
Titanium alkoxides such as titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetraisopropoxide, titanium tetra-n-butoxide, titanium tetra-sec-butoxide, titanium tetrakis (2-ethylhexyl oxide);
Zirconium alkoxides such as zirconium tetraethoxide, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra-sec-butoxide, zirconium tetrakis (2-ethylhexyl oxide);
Germanium alkoxides such as germanium tetraethoxide, germanium tetra-n-propoxide, germanium tetraisopropoxide, germanium tetra-n-butoxide, germanium tetra-sec-butoxide, germanium tetrakis (2-ethylhexyl oxide);
Yttrium hexaethoxide, yttrium hexaethoxide-n-propoxide, yttrium hexaethoxide isopropoxide, yttrium hexaethoxide-n-butoxide, yttrium hexaethoxide-sec-butoxide, yttrium hexaethoxide (2-ethylhexyl) Yttrium alkoxides, such as oxide);
Is mentioned.

  Examples of silicon alkoxide and silicon alkoxide derivatives include hydrolyzable organosilane compounds represented by the following general formula (2).

R ² _p SiX _4-p (2)
(In Formula (1), p is an integer of 0 to 3)
In the above formula (1), R ² represents a substituted or unsubstituted hydrocarbon group which is bonded to the Si atom with a single bond (monovalent hydrocarbon group). A thing or a different kind of thing may be sufficient. X in formula (1) represents a hydrolyzable group, and when there are a plurality of groups, they may be the same or different groups. For example, in addition to a tetrafunctional compound, a trifunctional or less functional compound may be used in combination.

The R ² is not particularly limited, but a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms is preferably used.

Specific examples of R ² include, for example, methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, heptyl groups, octyl groups and other alkyl groups; cyclopentyl groups and other cycloalkyl groups; 2-phenylethyl groups Aralkyl groups such as 2-phenylpropyl group and 3-phenylpropyl group; aryl groups such as phenyl group and tolyl group; alkenyl groups such as vinyl group and allyl group; chloromethyl group, γ-chloropropyl group, 3, 3 , 3-trifluoropropyl group and halogen-substituted hydrocarbon group; substituted hydrocarbon groups such as γ-glycidoxypropyl group, 3,4-epoxycyclohexylethyl group, γ-mercaptopropyl group, and the like can be exemplified. . Among these, an alkyl group having 1 to 4 carbon atoms and a phenyl group are preferable from the viewpoint of ease of synthesis or availability. Of the alkyl groups, those having 3 or more carbon atoms may be linear such as n-propyl group, n-butyl group, etc., isopropyl group, isobutyl group, t-butyl group. It may have a branch such as a group.

  In the general formula (1), X is not particularly limited as long as it is the same or different hydrolyzable group, and examples thereof include an alkoxy group, an oxime group, an enoxy group, an amino group, an aminoxy group, and an amide group. It is done. That is, specific examples include mono-, di-, tri-, and tetra-functional alkoxy metals, acetoxy metals, oximes in which the value of p in the general formula (1) is an integer of 0 to 3. Metals, enoxy metals, amino metals, aminoxy metals, amide metals and the like can be mentioned.

  Among these, X is preferably an alkoxysilane in which X is an alkoxy group (OR) from the viewpoint of ease of synthesis or availability. Among the alkoxy groups, the alkyl group (R) preferably has 1 to 8 carbon atoms.

  Specific examples of the alkyl group having 1 to 8 carbon atoms in the alkoxy group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. Among the alkyl groups in the alkoxy group, those having 3 or more carbon atoms may be linear such as n-propyl group, n-butyl group, etc., or isopropyl group, isobutyl group. , T-butyl group or the like may be used. Organosilanes generally called coupling agents are also included in the above alkoxysilanes.

  As the metal alkoxide for forming the parent phase 104, a compound having a structure represented by the following chemical formula (3) (hereinafter referred to as a second metal alkoxide; for example, when the metal is silicon, the second silicon alkoxide Also). The metal oxide produced from at least one selected from the second metal alkoxide, the derivative of the second metal alkoxide, and the partial hydrolysis condensate thereof (hereinafter referred to as the second metal alkoxide) is a water-repellent group. By providing the water repellency is increased.

M ² (R ³ ) _nx (R ⁴ ) _x (3)
In chemical formula (3), M ² is a metal atom selected from Si, Ti, Al, Zr, Ge, and Y.

R ³ is a functional group involved in the hydrolysis-condensation reaction, and when there are a plurality of R ³ in one molecule, they may be the same as or different from each other. This functional group is preferably a functional group selected from an alkoxide group, a hydroxyl group and a chloro group.

R ⁴ is a substituent having hydrophobicity (water repellency), and when a plurality of R ⁴ are present in one molecule, they may be the same as or different from each other. This substituent is preferably a substituent selected from a long-chain hydrocarbon group and a fluorine-containing hydrocarbon group, and in particular, — (CH ₂ ) _y —CH ₃ and — (CH ₂ ) ₂ — (CF ₂ ) _z. A substituent selected from —CF ₃ is preferred.

— (CH ₂ ) _y —CH ₃ is a long-chain hydrocarbon group composed of a C atom and an H atom. In order to improve the water repellency of the coated phosphor 100, y in the long-chain hydrocarbon group is particularly preferably an integer of 2 or more.

— (CH ₂ ) ₂ — (CF ₂ ) _z —CF ₃ is a fluorine-containing hydrocarbon group having a —CH ₂ —CH ₂ — bond interposed between the metal atom M ² and the —CF— group as a linker. is there. Z in the fluorine-containing hydrocarbon group is particularly preferably an integer of 1 or more in order to improve the water repellency of the coated phosphor 100.

In the chemical formula (3), n is a number equal to the valence of the metal element M ^2. x is an integer of 1 or more and satisfies the relationship of n> x. That is, the second metal alkoxide includes at least one functional group involved in the hydrolysis condensation reaction in one molecule and at least one substituent having hydrophobicity in one molecule.

  Specific examples of the second metal alkoxide having a long-chain hydrocarbon group include propyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, propyltriethoxysilane, butyltriethoxysilane, hexyltri Examples thereof include ethoxysilane and decyltriethoxysilane. Specific examples of the second metal alkoxide having a fluorine-containing hydrocarbon group include trifluoropropyltrimethoxysilane and heptadecafluorodecyltrimethoxysilane.

  When the above metal alkoxide or the like is subjected to condensation polymerization on the surface of the phosphor particle 101 in the presence of the metal oxide particle 103, a condensation polymer (metal oxide) such as metal alkoxide is formed on the phosphor particle 101. The matrix phase 104 is deposited and the phosphor particles 101 are taken into the matrix phase 104, whereby the coating layer 102 is formed. When the coating layer 102 is formed in this way, the surface of the metal oxide particles 103 is highly hydrophilic, so that the metal oxide particles 103 are likely to be present near the surface of the phosphor particles 101 in the coating layer 102. For this reason, a concentration distribution is generated in the coating layer 102 such that the concentration of the metal oxide particles 103 decreases as the distance from the phosphor particles 101 increases.

  In particular, the mother phase 104 is preferably formed from a mixture containing the first metal alkoxide, etc. and the second metal alkoxide, etc., and further from the mixture containing the first silicon alkoxide, etc., the second silicon alkoxide, etc. It is preferred that a parent phase 104 is formed. In the parent phase 104 formed by the condensation reaction of these metal alkoxides and the like on the surface of the phosphor particles 101, the hydrophobic substituent derived from the second metal alkoxide and the like is separated from the phosphor particles 101. The distribution is unevenly distributed at different positions. This is considered to be because the surface energy of the substituent having hydrophobicity is high. On the other hand, since hydrophilic groups such as OH groups are usually present on the surface of the phosphor particle 101, the hydrophilicity of the surface of the phosphor particle 101 is high. For this reason, in the coating layer 102, the hydrophilicity is higher on the surface side of the phosphor particles 101, and the hydrophobicity is higher on the outer surface side. On the other hand, the surface of the metal oxide particle 103 is highly hydrophilic. Therefore, the metal oxide particles 103 are likely to be present near the surface of the phosphor particle 101 in the coating layer 102, and conversely, are not likely to be present near the outer surface of the coating layer 102. For this reason, a concentration distribution in which the concentration of the metal oxide particles 103 becomes lower in the coating layer 102 as the distance from the phosphor particles 101 becomes more likely to occur. Furthermore, the distribution state (concentration distribution) of the metal oxide particles 103 in the coating layer 102 can be controlled by appropriately adjusting the ratio of the second metal alkoxide or the like to the entire metal alkoxide or the like.

  When the matrix 104 is formed from a condensate of a mixture of the first metal alkoxide and the like and the second metal alkoxide and the like, these metal alkoxides supplied onto the surface of the phosphor particles 101 during the condensation reaction It is preferable that the ratio of the second metal alkoxide and the like with respect to the total amount is in the range of 10 to 40 mol%. This mole fraction is a value based on the number of moles of metal atoms constituting the metal alkoxide or the like.

  As a specific example of the method of forming the coating layer 102 in the case of forming the parent phase 104 from a metal alkoxide, the following sol-gel coating method can be given.

  In the sol-gel coating method, phosphor particles 101 are first added to a liquid medium. Subsequently, the metal alkoxide and the metal oxide particles 103 or a solution containing them is added to the medium while the medium is stirred. As a result, hydrolysis condensation reaction of metal alkoxide proceeds, and hydrolysis condensate such as metal alkoxide is deposited on the surface of phosphor particle 101 while taking in metal oxide particles 103, thereby forming coating layer 102. Is done.

  Specific examples of the liquid medium used in the sol-gel coating method include alcohol solvents such as methanol, ethanol, propanol, isopropanol, and butanol; toluene, xylene, cyclohexane, methylcyclohexane, petroleum ether, petroleum benzine, gasoline, naphtha, and the like. Hydrocarbon solvents such as: ether solvents such as diethyl ether and tetrahydrofuran; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone and methyl ethyl ketone. Of these liquid media, only one kind may be used alone, or two or more kinds may be used in combination.

  In the sol-gel coating method, it is preferable that a stoichiometric amount or an excessive amount of water required for the progress of the hydrolysis condensation reaction is added to the liquid medium. Water is added to the liquid medium at an appropriate timing. For example, whether water is added to the liquid medium in which the phosphor particles 101 are dispersed or added to the liquid medium together with the metal alkoxide having a relatively low hydrolysis rate, the liquid medium is separated from the metal alkoxide. May be added. Alternatively, after the metal alkoxide is adhered to the surface of the phosphor particle 101, the solvent is distilled off or the phosphor particle 101 to which the metal alkoxide is adhered is recovered by filtration, and then the phosphor particle 101 is vapor phase or When contacted with liquid phase water, the hydrolysis condensation reaction of the metal alkoxide proceeds on the surface of the phosphor particles 101, whereby the first layer 102 is formed.

  It is also preferable that the parent phase 104 is formed from silicon oxide (silica) produced by conversion of polysilazane. In this case, the refractive index of the parent phase 104 is very close to that of a silicon compound or glass that is suitable as a material for the translucent medium 72. Furthermore, such a mother phase 104 is dense and extremely excellent in moisture barrier properties. Moreover, such a parent phase 104 can be formed from polysilazane at a relatively low temperature. Further, such a parent phase 104 does not absorb light in the light emission wavelength region of the LED, or has a small light absorption amount in the light emission wavelength region of the LED. Therefore, such a parent phase 104 is suitable for the water vapor gas barrier of the phosphor particles 101.

Polysilazane includes, for example, a structural unit represented by the following general formula. R ¹ , R ² and R ³ in the general formula are each independently a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group in which a group directly connected to silicon other than these groups is carbon. Represents an alkylsilyl group, an alkyl group, an amino group, an alkoxy group, or a metal atom.

In order to improve the heat resistance and light resistance of the coating layer 102, the polysilazane is preferably perhydropolysilazane in which R ¹ , R ² and R ³ in the general formula are all hydrogen.

  The average molecular weight of polysilazane is not particularly limited, but is, for example, in the range of 100 to 50000, and particularly preferably in the range of 500 to 20000. This average molecular weight is a value of a weight average molecular weight measured by GPC (gel permeation chromatography). If the average molecular weight of the polysilazane is too small, the polysilazane tends to evaporate together with the solvent when the coating layer 102 is formed, and the amount of polysilazane used for forming the coating layer 102 may be reduced. On the other hand, when the average molecular weight of the polysilazane is too large, the polysilazane is easily gelled, the handleability of the polysilazane is deteriorated, and the densification of the coating layer 102 is difficult.

  When the polysilazane as described above is converted to silica on the surface of the phosphor particles 101 in the presence of the metal oxide particles 103, silica is deposited on the phosphor particles 101 to form a parent phase 104, When the phosphor particles 101 are taken into the matrix phase 104, the coating layer 102 is formed. When the coating layer 102 is formed in this way, the surface of the metal oxide particles 103 is highly hydrophilic, so that the metal oxide particles 103 are likely to be present near the surface of the phosphor particles 101 in the coating layer 102. For this reason, a concentration distribution is generated in the coating layer 102 such that the concentration of the metal oxide particles 103 decreases as the distance from the phosphor particles 101 increases.

  When the coating layer 102 is formed, for example, first, a dispersion is prepared by dispersing polysilazane and metal oxide particles 103 in a solvent. The dispersion liquid is adhered onto the surface of the phosphor particles 101, and the solvent is volatilized from the dispersion liquid, and the polysilazane remaining on the surface of the phosphor particles 101 is converted into silica. As a result, silica is deposited on the surface of the phosphor particles 101 while taking in the metal oxide particles 103, thereby forming the coating layer 102 containing the matrix 104 and the phosphor particles 101 formed of silica.

  Examples of the solvent used for forming the coating layer 102 include hydrocarbon solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons; halogenated carbons such as halogenated methane, halogenated ethane, and halogenated benzene. Hydrogen; Ethers such as aliphatic ethers and alicyclic ethers are included. Specific examples of preferred solvents include halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, ethylidene chloride, trichloroethane, tetrachloroethane, ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1 , 2-dioxyethane, dioxane, dimethyldioxane, tetrahydrofuran, tetrahydropyran and other ethers; pentane hexane, isohexane, methylpentane, heptane, isoheptane, octane, isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene And hydrocarbons such as xylene and ethylbenzene. Particularly preferred solvents are butyl ether and xylene because of their ease of handling and solution stability.

  These solvents are used alone or in combination of two or more for adjusting the solubility of polysilazane and the evaporation rate of the solvent.

  The solid content concentration of polysilazane in the dispersion is determined in consideration of improvement in workability and the like according to the type of coating method employed for forming the coating layer 102. The optimal solid content concentration of polysilazane varies depending on the average molecular weight, molecular weight distribution, structure, etc. of polysilazane, and is thus determined as appropriate. It is recommended that the solid content concentration of polysilazane is adjusted in the range of 0.5 to 30% by mass.

  During the conversion of polysilazane to silica, a catalyst that promotes this conversion may be used. As this catalyst, a basic catalyst, a metal ion catalyst and the like are preferable.

  Specific examples of basic catalysts include amines such as triethylamine, diethylamine, monoethanolamine, diethanolamine, triethanolamine, n-exylamine, n-butylamine, di-n-butylamine, tri-n-butylamine; sodium hydroxide And alkalis such as potassium hydroxide, lithium hydroxide, pyridine, and aqueous ammonia. Of these, from the viewpoints of reactivity and handleability, triethylamine and aqueous ammonia are preferred. The basic catalyst may be added in advance to a dispersion containing the polysilazane solution before being coated with the phosphor particles 101. The phosphor particles 101 coated with polysilazane may be immersed in an aqueous solution in which a basic catalyst is dispersed. The phosphor particles 101 coated with polysilazane may be exposed to an aqueous vapor containing a basic catalyst.

  Specific examples of the metal ion catalyst include late transition metal ions such as Pt, Ni, and Pd. Of these, Pd ions are particularly preferable from the viewpoints of reactivity and handleability. The metal ion catalyst may be added in advance to a dispersion containing the polysilazane solution before being coated with the phosphor particles 101. The phosphor particles 101 coated with polysilazane may be immersed in an aqueous solution in which a metal ion catalyst is dispersed.

  After the coating layer 102 is formed, it is preferable that the conversion from polysilazane in the coating layer 102 to silica is further advanced by subjecting the coating layer 102 to heat treatment or humidification heat treatment. In this case, the coating layer 102 is further densified, thereby improving the moisture resistance of the coated phosphor 100. Although the heating temperature in heat processing is not specifically limited, The range of 60-600 degreeC is preferable. The conversion from polysilazane to silica usually proceeds at 400 ° C. or higher, but when a catalyst is used, the heating temperature may be 130 to 250 ° C. or lower. The heating time is not particularly limited, but is preferably in the range of 0.5 to 3 hours. By this heat treatment, conversion of polysilazane to silica in the coating layer 102 further proceeds. The atmosphere during the heat treatment may be any of oxygen, air, inert gas, and the like. In particular, heat treatment is preferably performed in air. In this case, oxidation of polysilazane or hydrolysis with water vapor coexisting in the air proceeds, and mainly Si—O bonds or Si—N bonds are formed at a low heating temperature. The tough matrix phase 104 can be formed.

  Since the parent phase 104 in the coating layer 102 formed in this way is formed from silane derived from polysilazane, it usually contains 0.05% or more of nitrogen in atomic percent. In order for the parent phase 104 to be sufficiently dense, the atomic percentage of nitrogen in the parent phase 104 is preferably 5% or less, particularly preferably 3% or less.

  The thickness of the covering layer 102 is preferably in the range of 100 to 10,000 nm. In this case, when the thickness of the coating layer 102 is 100 nm or more, it becomes easy to cause the gradient of the refractive index in the coating layer 102, and when the thickness is 10,000 nm or less, the high comparative transmittance of the coating layer 102 is high. Secured. The thickness of the covering layer 102 is more preferably 100 to 1000, and particularly preferably 100 to 500.

[Wavelength conversion member]
The wavelength conversion member 70 includes a coated phosphor 100 and a translucent medium 72 as shown in FIG. The coated phosphor 100 is dispersed in the translucent medium 72.

  The refractive index of the translucent medium 72 is preferably approximated to the refractive index of the parent phase 104 in the coated phosphor 100 as described above.

  Examples of the material of the translucent medium 72 include a silicon compound having a siloxane bond and glass. Since these materials are excellent in heat resistance and light resistance (durability against light having a short wavelength such as blue to ultraviolet), the light is transmitted by light in a wavelength range from blue light to ultraviolet light which is excitation light of the coated phosphor 100. Deterioration of the medium 72 is suppressed. Examples of silicon compounds include composites formed by crosslinking a silicone resin, a hydrolyzed condensate of organosiloxane, a condensate of organosiloxane, etc. by a known polymerization method (addition polymerization such as hydrosilylation, radical polymerization, etc.). Resin. As the translucent medium 72, for example, an acrylic resin or an organic / inorganic hybrid material formed by mixing and bonding an organic component and an inorganic component at the nm level or molecular level may be employed.

  The content of the coated phosphor 100 in the wavelength conversion member 70 takes into account the types of the coated phosphor 100 and the translucent medium 72, the dimensions of the wavelength conversion member 70, the wavelength conversion capability required for the wavelength conversion member 70, and the like. For example, it is in the range of 5% by mass to 30% by mass.

  When the wavelength conversion member 70 is irradiated with the excitation light of the coated phosphor 100, the coated phosphor 100 absorbs the excitation light and emits fluorescence having a wavelength longer than that of the excitation light. Thereby, when light passes through the wavelength conversion member 70, the wavelength of this light is converted by the coated phosphor 100.

  In the wavelength conversion member 70 configured as described above, the provision of the coated phosphor 100 according to the present embodiment increases the incident efficiency of excitation light to the coated phosphor 100, and thus the light from the coated phosphor 100. Extraction efficiency (the luminous efficiency of the coated phosphor 100) is increased. For this reason, the luminous efficiency of the wavelength conversion member 70 is also increased.

[Light emitting device]
The light emitting device according to the present embodiment will be described. As shown in FIGS. 3 and 4, the light emitting device 1 includes an LED chip 10 that is a light emitting element, a mounting substrate 20, an optical member 60, a sealing unit 50, and a wavelength conversion member (color conversion member) 70. As described above, the wavelength conversion member (color conversion member) 70 includes the coated phosphor 100 according to the present embodiment.

  The LED chip 10 is mounted on the mounting substrate 20. The shape of the mounting substrate 20 is a rectangular plate shape in plan view. A pair of conductor patterns 23 for supplying power to the LED chip 10 are formed on the first surface facing the thickness direction of the mounting substrate 20, and the LED chip 10 is further mounted on the first surface. The LED chip 10 and the conductor pattern 23 are electrically connected by a bonding wire 14. The optical member 60 is a dome-shaped member and is fixed on the first surface of the mounting substrate 20. The LED chip 10 is accommodated between the optical member 60 and the mounting substrate 20. The optical member 60 has a function of controlling the orientation of light emitted from the LED chip 10. The sealing part 50 is formed from a translucent sealing material. The sealing portion 50 is filled in a space surrounded by the optical member 60 and the mounting substrate 20. The sealing portion 50 seals the LED chip 10 and a plurality of (in this embodiment, two) bonding wires 14. The wavelength conversion member 70 is formed in a dome shape so as to surround the optical member 60. When the LED chip 10 emits light, the coated phosphor 100 in the wavelength conversion member 70 is excited by the light emitted from the LED chip 10 (excitation light), and fluorescent light having a wavelength longer than that of the excitation light (the emission color of the LED chip 10). Emits converted light consisting of light of different colors. Between the optical member 60 and the wavelength conversion member 70, a gap 80 in which a gas such as air is enriched is interposed. On the first surface of the mounting substrate 20, an annular weir 27 that surrounds the outer periphery of the optical member 60 is formed. The dam portion 27 is formed so as to protrude from the first surface. Therefore, when the optical member 60 is fixed to the mounting substrate 20, even if the sealing material overflows from the space surrounded by the optical member 60 and the mounting substrate 20, the sealing material is blocked by the dam portion 27. I can be dammed up.

  The main light emission peak of the LED chip 10 is preferably in the range of 350 nm to 470 nm. Examples of such an LED chip 10 include a GaN-based blue LED chip that emits blue light and a near-ultraviolet LED chip that emits near-ultraviolet light.

  In a GaN blue LED chip, an n-type SiC substrate having a lattice constant or crystal structure closer to that of GaN than a sapphire substrate and having conductivity is used as a crystal growth substrate. On the SiC substrate, for example, a light-emitting portion having a double hetero structure is formed. The light emitting portion is formed by, for example, an epitaxial growth method (for example, MOVPE method) using a GaN-based compound semiconductor material or the like as a raw material. The LED chip 10 includes a cathode electrode on the surface facing the first surface of the mounting substrate 20 and an anode electrode on the opposite surface. The cathode electrode and the anode electrode are constituted by, for example, a laminated film of a Ni film and an Au film. The material for the cathode electrode and the anode electrode is not particularly limited, and may be any material as long as good ohmic characteristics can be obtained. For example, Al may be used.

  The structure of the LED chip 10 is not limited to the above structure. For example, after a light emitting part or the like is formed by epitaxial growth on a crystal growth substrate, a support substrate such as an Si substrate that supports the light emitting part is fixed to the light emitting part, and then the crystal growth substrate is removed. The LED chip 10 may be formed.

  The mounting board 20 includes a rectangular heat transfer plate 21 and a wiring board 22. The heat transfer plate 21 is formed from a heat conductive material. The LED chip 10 is mounted on the heat transfer plate 21. The wiring board 22 is, for example, a rectangular flexible printed wiring board. The wiring board 22 is fixed on the heat transfer plate 21 via, for example, a polyolefin-based fixing sheet 29. A rectangular window hole 24 that exposes the mounting position of the LED chip 10 on the heat transfer plate 21 is formed at the center of the wiring board 22. Inside this window hole 24, the LED chip 10 is mounted on the heat transfer plate 21 via a submount member 30 described later. Therefore, the heat generated in the LED chip 10 is conducted to the submount member 30 and the heat transfer plate 21 without passing through the wiring board 22.

  The wiring substrate 22 includes an insulating base material 221 made of a polyimide film and a pair of conductor patterns 23 for supplying power to the LED chip 10 formed on the insulating base material 221. Furthermore, the wiring board 22 includes a protective layer 26 that covers each conductor pattern 23 and covers a portion on the insulating base material 221 where the conductor pattern 23 is not formed. The protective layer 26 is formed of, for example, a white resist (resin) having light reflectivity. In this case, even if light is radiated from the LED chip 10 toward the wiring substrate 22, the light is reflected by the protective layer 26, thereby suppressing light absorption in the wiring substrate 22. Thereby, the light extraction efficiency from the LED chip 10 to the outside is improved, and the light output of the light emitting device is improved. Each conductor pattern 23 is formed in an outer peripheral shape slightly smaller than half of the outer peripheral shape of the insulating base material 221. The insulating base material 221 may be formed of an FR4 substrate, an FR5 substrate, a paper phenol resin substrate, or the like.

  Each conductor pattern 23 includes two terminal portions 231 each having a rectangular shape in plan view. The terminal portion 231 is located in the vicinity of the window hole 24 of the wiring board 22, and the bonding wire 14 is connected to the terminal portion 231. Each conductor pattern 23 further includes one external connection electrode portion 232 having a circular shape in plan view. The external connection electrode portion 232 is located near the outer periphery of the wiring board 22. The conductor pattern 23 is composed of, for example, a laminated film of a Cu film, a Ni film, and an Au film.

  The protective layer 26 is patterned so that each conductor pattern 23 is partially exposed from the protective layer 26. In the vicinity of the window hole 24 of the wiring board 22, the terminal portion 231 in each conductor pattern 23 is exposed from the protective layer 26. Further, the external connection electrode portions 232 in each conductor pattern 23 are exposed from the protective layer 26 near the outer periphery of the wiring board 22.

  The LED chip 10 is mounted on the heat transfer plate 21 via the submount member 30 as described above. The submount member 30 relieves stress acting on the LED chip 10 due to a difference in linear expansion coefficient between the LED chip 10 and the heat transfer plate 21. The submount member 30 is formed in a rectangular plate shape having a size larger than the chip size of the LED chip 10.

  The submount member 30 has not only a function of relieving the stress but also a heat conduction function of conducting heat generated in the LED chip 10 in a wider range than the chip size of the LED chip 10 in the heat transfer plate 21. Yes. In the light emitting device 1 according to the present embodiment, the LED chip 10 is mounted on the heat transfer plate 21 via the submount member 30, so that the heat generated by the LED chip 10 passes through the submount member 30 and the heat transfer plate 21. In addition, the heat acting on the LED chip 10 due to the difference in linear expansion coefficient between the LED chip 10 and the heat transfer plate 21 is relieved.

  The submount member 30 is made of, for example, AlN having a relatively high thermal conductivity and an insulating property.

  The cathode electrode of the LED chip 10 is superposed on the submount member 30, and the cathode electrode is bonded with an electrode pattern (not shown) connected to the cathode electrode and a metal fine wire (for example, a gold fine wire, an aluminum fine wire, etc.). It is electrically connected to one of the two conductor patterns 23 through the wire 14. The LED chip 10 is electrically connected through a bonding wire 14 to a conductor pattern 23 that is not connected to the cathode electrode.

  For joining the LED chip 10 and the submount member 30, for example, solder such as SnPb, AuSn, SnAgCu, silver paste, or the like is used. It is particularly preferable to use lead-free solder such as AuSn or SnAgCu. When the submount member 30 is made of Cu and AuSn is used for bonding the LED chip 10 and the submount member 30, Au or Ag is previously formed on the surfaces of the submount member 30 and the LED chip 10 to be bonded to each other. It is preferable to perform a pretreatment for forming a metal layer made of For joining the submount member 30 and the heat transfer plate 21, for example, lead-free solder such as AuSn or SnAgCu is preferably used. When AuSn is used for joining the submount member 30 and the heat transfer plate 21, a pretreatment for forming a metal layer made of Au or Ag in advance on the surface of the heat transfer plate 21 to be joined with the submount member 30. Is preferably applied.

  The material of the submount member 30 is not limited to AlN, and any material may be used as long as the linear expansion coefficient is relatively close to 6H—SiC, which is the material for the crystal growth substrate, and the thermal conductivity is relatively high. For example, composite SiC, Si, Cu, CuW, or the like may be employed as the material of the submount member 30. Since the submount member 30 has the above-described heat conduction function, the area of the surface of the heat transfer plate 21 facing the LED chip 10 is the area of the surface of the LED chip 10 facing the heat transfer plate 21. It is desirable that it be sufficiently large.

  In the light emitting device 1 according to this embodiment, the heat transfer is larger than the dimension from the surface on the LED chip 10 side facing the thickness direction of the heat transfer plate 21 to the surface on the LED chip 10 side facing the thickness direction of the protective layer 26. The dimension from the surface of the plate 21 to the surface on the LED chip 10 side facing the thickness direction of the submount member 30 is larger. The thickness dimension of the submount member 30 is set so as to have such a positional relationship. For this reason, the light emitted from the LED chip 10 is suppressed from being absorbed by the wiring board 22 through the inside of the window hole 24 of the wiring board 22. Thereby, the light extraction efficiency from the LED chip 10 to the outside is further improved, and the light output of the light emitting device is further improved.

  Note that a reflective film that reflects light emitted from the LED chip 10 is formed around the position where the LED chip 10 is disposed on the surface of the submount member 30 facing the thickness direction of the LED chip 10. Good. In this case, the light emitted from the LED chip 10 is prevented from being absorbed by the submount member 30. Thereby, the light extraction efficiency from the LED chip 10 to the outside is further improved, and the light output of the light emitting device is further improved. The reflective film is composed of a laminated film of a Ni film and an Ag film, for example.

  A silicone resin is mentioned as a sealing material which is a material for forming the above-mentioned sealing part 50. For example, an acrylic resin, glass, or the like may be used instead of the silicone resin.

  The optical member 60 is formed from a light transmissive material (eg, silicone resin, glass, etc.). In particular, when the optical member 60 is formed of a silicone resin, a difference in refractive index and a difference in linear expansion coefficient between the optical member 60 and the sealing portion 50 can be reduced.

  The light emission surface 602 (surface facing the side opposite to the LED chip 10) of the optical member 60 is light emitted from the light incident surface 601 (surface facing the LED chip 10 side) into the optical member 60. A convex curved surface is formed so as not to be totally reflected at the boundary between the surface 602 and the gap 80. The optical member 60 is disposed so that the optical axis of the LED chip 10 coincides. Therefore, the light emitted from the LED chip 10 and incident on the light incident surface 601 of the optical member 60 can easily reach the wavelength conversion member 70 without being totally reflected at the boundary between the light emitting surface 602 and the gap layer 80. The total luminous flux from the light emitting device 1 increases. The optical member 60 is formed to have a uniform thickness along the normal direction regardless of the position.

  The wavelength conversion member 70 has a light incident surface 701 (a surface facing the LED chip 10) formed in a shape along the light emitting surface 602 of the optical member 60. Therefore, regardless of the position of the light emitting surface 602 of the optical member 60, the distance between the light emitting surface 602 of the optical member 60 and the wavelength conversion member 70 in the normal direction is a substantially constant value. The wavelength conversion member 70 is formed so that the thickness along the normal direction is uniform regardless of the position. The wavelength conversion member 70 is fixed to the mounting substrate 20 with, for example, an adhesive (for example, silicone resin, epoxy resin).

  Light emitted from the LED chip 10 enters the wavelength conversion member 70 from the light incident surface 701, and out of the wavelength conversion member 70 through the light emission surface (surface opposite to the LED chip 10) 701 of the wavelength conversion member 70. Emitted. When light passes through the wavelength conversion member 70, a part of this light is wavelength-converted by the phosphor particles 101 in the wavelength conversion member 70. As a result, light of a color corresponding to the combination of the light emitted from the LED chip 10 and the type of the phosphor particles 101 in the wavelength conversion member 70 is emitted from the light emitting device 1.

  As described above, the wavelength conversion member 70 includes the translucent medium 72 and the coated phosphor 100 according to the present embodiment dispersed in the translucent medium 72. The wavelength conversion member 70 may further include wavelength conversion particles other than the coated phosphor 100 according to the present embodiment. As the wavelength conversion particle, an appropriate phosphor particle 101 is exemplified.

  When the light emitting device 1 emits white light and the LED chip 10 in the light emitting device 1 is a blue LED chip that emits blue light, as the phosphor particles 101 in the coated phosphor 100 in the wavelength conversion member 70, for example, Particles formed from a red phosphor and particles formed from a green phosphor are used in combination. Or only the particle | grains formed from yellow fluorescent substance as the fluorescent substance particle 101 may be used. Alternatively, as the phosphor particles 101, particles formed from a green phosphor and particles formed from an orange phosphor may be used in combination. Alternatively, as the phosphor particles 101, particles formed from a yellow-green phosphor and particles formed from an orange phosphor may be used in combination. In these cases, the blue light emitted from the LED chip 10 without being wavelength-converted and the light wavelength-converted by the coated phosphor 100 of the wavelength conversion member 70 are the light emission surface (outer surface) of the wavelength conversion member 70. 702 will be emitted, thereby emitting white light.

  When the light emitting device 1 emits white light and the LED chip 10 in the light emitting device 1 is an ultraviolet LED chip that emits ultraviolet light, for example, the phosphor particles 101 in the coated phosphor 100 are formed from a red phosphor. Particles, particles formed from a green phosphor and particles formed from a blue phosphor are used in combination. In this case, the ultraviolet light emitted from the LED chip 10 without wavelength conversion and the light that has been wavelength-converted by the coated phosphor 100 of the wavelength conversion member 70 are the light emission surface (outer surface) 702 of the wavelength conversion member 70. Through which white light is emitted.

[Example 1]
(1-1) Preparation of green wavelength conversion particles In a reaction container, phosphor particles (green phosphor particles, CaSc ₂ O ₄ : Ce ³⁺ , median diameter) were added to 250 parts by mass of 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.). (D50) 10 μm, refractive index 1.9) was added to prepare a suspension.
Next, while immersing another reaction vessel in an ice bath and keeping the temperature around 5 ° C., 5 parts by mass of an isopropanol dispersion of zirconium oxide (primary particle size 10 nm) in terms of solid content, C ₄ H ₉ Si ( 10 parts by mass of OCH ₃ ) ₃ , 50 parts by mass of Si (OCH ₂ CH ₃ ) ₄ and 250 parts by mass of 2-propanol were prepared, and these were mixed and stirred to prepare a mixed solution. This mixed solution was added dropwise to the suspension.

  Thereafter, the suspension was stirred for 12 hours, and then the solid content was separated and collected by centrifugal filtration. This solid content was dried under reduced pressure at 80 ° C. for 4 hours, and further heated and dried at 250 ° C. for 1 hour. As a result, a coated phosphor emitting green fluorescence was obtained.

  When the X-ray photoelectron spectroscopy (ESCA) depth direction analysis was performed on the coating layer of the coated phosphor, a composition mainly composed of Zr and O was detected on the inner back side and a composition mainly composed of Si and O on the outer layer side. Was detected.

  For the X-ray photoelectron spectroscopic analysis of this coating layer, a model phosphor ESCALAB220-XL manufactured by Thermo Fisher Scientific Co., Ltd. was used, and the coated phosphor was spread on a plane, and the plane was fractionated into a 1 mm square analysis area. Measured. The element concentration (atm.%) At a specific depth of the coating layer was calculated by cutting the coating layer of the coating phosphor by sputtering with argon ion irradiation.

(1-2) Preparation of red wavelength conversion particles Example 1 except that CaAlSiN ₃ : Eu ²⁺ (red phosphor particles, refractive index 2.0, center particle diameter d50 is 10 μm) was used as the phosphor particles. The coated phosphor emitting red fluorescence was obtained by the same method as -1.

  When the depth direction analysis of the X-ray photoelectron spectroscopic analysis (ESCA) was performed on the coating layer of the coated phosphor under the same conditions as described above, a composition mainly composed of Zr and O was detected on the inner side, and Si, A composition mainly composed of O was detected.

[Example 2]
In Example 1, a 2-isopropanol dispersion of titanium oxide (primary particle size 12 nm) was used instead of the 2-propanol dispersion of zirconium oxide. Other than that, a coated phosphor emitting yellow-green fluorescence and a coated phosphor emitting orange fluorescence were obtained in the same manner and under the same conditions as in Example 1.

[Example 3]
(3-1) Production of Green Wavelength Conversion Particles In a reaction vessel, 100 parts by mass of xylene (manufactured by Wako Pure Chemical Industries, Ltd.) was added to phosphor particles (green phosphor particles, CaSc ₂ O ₄ : Ce ³⁺ , median diameter ( D50) 10 μm, refractive index 1.9) 10 parts by mass were added to prepare a suspension.

  Next, while immersing another reaction vessel in an ice bath and keeping it at around 5 ° C., 5 parts by mass of a xylene dispersion of zirconia oxide (primary particle size 10 nm) in terms of solid content, perhydropolysilazane (AZ Material) Product number NL-110-2; 20 parts by mass of xylene solution containing 20% by mass of perhydropolysilazane in terms of oxide) and 50 parts by mass of dehydrated xylene (manufactured by Wako Pure Chemical Industries, Ltd.) Was prepared. This mixed solution was added dropwise to the suspension.

  Thereafter, the suspension was stirred for 12 hours, and then the solid content was separated and collected by centrifugal filtration. This solid content was dried under reduced pressure at 80 ° C. for 4 hours, and further heated and dried at 250 ° C. for 1 hour. As a result, a coated phosphor emitting green fluorescence was obtained.

  When the depth direction analysis of the X-ray photoelectron spectroscopic analysis (ESCA) was performed on the coating layer of the coated phosphor under the same conditions as described above, a composition mainly composed of Zr and O was detected on the inner side, and Si, A composition mainly composed of O was detected.

(3-2) Production of red wavelength conversion particles Example 3 except that CaAlSiN ₃ : Eu ²⁺ (red phosphor particles, refractive index 2.0, center particle diameter d50 is 10 μm) was used as the phosphor particles. The coated phosphor emitting red fluorescence was obtained by the same method as -1.

  When the depth direction analysis of the X-ray photoelectron spectroscopic analysis (ESCA) was performed on the coating layer of the coated phosphor under the same conditions as described above, a composition mainly composed of Zr and O was detected on the inner side, and Si, A composition mainly composed of O was detected.

[Comparative example]
Green phosphor particles (CaSc ₂ O ₄ : Ce ³⁺ , median diameter (D50) 10 μm, refractive index 1.9) are used as wavelength conversion particles emitting green fluorescence as they are, and red phosphor particles (CaAlSiN ₃ : Eu ²⁺ (red The phosphor particles having a center particle diameter d50 of 10 μm and a refractive index of 2.0) were used as wavelength conversion particles emitting red fluorescence.

[Production and Evaluation of Wavelength Conversion Member and Light-Emitting Device]
13 parts by mass of the coated phosphor obtained in each of Examples 1 to 3 (a mixture of a coated phosphor emitting green fluorescence and a coated phosphor emitting red fluorescence in a mass ratio of 6: 7), refraction A composition was prepared by mixing 87 parts by mass of a silicone resin having a rate of 1.4, and a dome-shaped wavelength conversion member having a thickness of 2 mm was produced by pressing the composition.

  Further, 13 parts by mass of the wavelength conversion particles (a mixture of the wavelength conversion particles emitting green fluorescence and the wavelength conversion particles emitting red fluorescence having a mass ratio of 6: 7) obtained in the comparative example, and the refractive index is 1 The composition was prepared by mixing 87 parts by mass of a silicone resin of .4, and this composition was pressed to prepare a dome-shaped wavelength conversion member having a thickness of 2 mm.

  Using the wavelength conversion member obtained in each of Examples 1 to 3 and Comparative Example, a light emitting device having the structure shown in FIGS. A blue LED chip having an emission peak wavelength of 460 nm was used as the LED chip.

  The total luminous flux of light emitted immediately after energization from this light emitting device was measured. As a result, the total luminous flux in Example 1 was 105, the total luminous flux in Example 2 was 102, and the total luminous flux in Example 3 was 103 with respect to the total luminous flux value 100 in the comparative example. Note that these values of the total luminous flux are relative values normalized with the case of Comparative Example 1 as 100.

DESCRIPTION OF SYMBOLS 100 Coated fluorescent substance 101 Phosphor particle 102 Coating layer 103 Metal oxide particle 104 Mother phase 1 Light-emitting device 70 Wavelength conversion member

Claims (5)

Comprising phosphor particles and a coating layer covering the outside of the phosphor particles;
The matrix comprises a matrix phase formed from a metal oxide, and metal oxide particles having a higher refractive index than the matrix phase,
The coated phosphor in which the metal oxide particles are dispersed in the matrix and the concentration of the metal oxide particles in the coating layer decreases as the distance from the phosphor particles increases. 2. The coated phosphor according to claim 1, wherein the matrix phase is formed from silicon oxide generated from at least one selected from silicon alkoxides, silicon alkoxide derivatives, and partial hydrolysis condensates thereof. The coated phosphor according to claim 1, wherein the matrix is formed from silica produced by conversion of polysilazane. The material of the metal oxide particles is at least one selected from aluminum oxide, titanium dioxide, zirconium oxide, niobium oxide, tin oxide, germanium oxide, and yttrium oxide,
The coated phosphor according to at least one of claims 1 to 3, wherein a particle diameter of the metal oxide particles is 1 nm or more and 100 nm or less. A light-emitting device provided with the covering fluorescent substance as described in any one of Claims 1 thru | or 4.

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