JP2012167147A - Phosphor and light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphor, which is efficiently excited by excitation light in a wide wavelength region to emit red fluorescence and can be produced safely.SOLUTION: The phosphor consists of a metal oxide solid solution having a structure wherein LiTiO:Mnis doped with at least one of Ge and A (A is at least one selected from Na, K and Rb).

Description

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

  In recent years, with the improvement of the light emission efficiency of light emitting diodes (LEDs), light emitting devices using LEDs are becoming popular and expanding. In particular, a light-emitting device including an LED and a phosphor that converts the wavelength of light emitted from the LED can be highly efficient, small, thin, and power-saving, and can be arbitrarily selected depending on the application such as white color or light bulb color. Features such as the ability to emit light in color. For this reason, this type of light-emitting device can be used for indoor and outdoor lighting fixtures, liquid crystal displays, backlight light sources for mobile phones and personal digital assistants, display devices used for indoor and outdoor advertisements, in-vehicle light sources, and the like. Expected and being developed.

Conventionally, various configurations have been proposed as a configuration of a light emitting device that emits white light. For example, Patent Document 1 discloses a phosphor that emits red fluorescence having a wavelength of 600 nm to 680 nm or less when Eu is dissolved in a CaAlSiN ₃ crystal phase and irradiated with light of 550 nm or less. Patent Document 1 discloses a phosphor that emits this red tendency, a blue phosphor having an emission peak at a wavelength of 420 nm to 500 nm by excitation light of 330 to 420 nm, and a wavelength of 500 nm to 570 nm by excitation light of 330 to 420 nm. There is also disclosed a lighting fixture that includes a green phosphor having an emission peak at the following wavelength and further includes an LED that emits light having a wavelength of 330 to 420 nm as a light source.

In Patent Document 2, M ¹ ₂ M ⁴ F ₆ : R (M ¹ contains one or more elements selected from the group consisting of K and Na, M ⁴ is a metal element containing Si, R represents an activating element containing at least Mn.), And the ratio of Mn to the total number of moles of M ⁴ and Mn is 0.1 mol% or more 40 A phosphor that emits red light (for example, K ₂ SiF ₆ : Mn ⁴⁺ ) having a mol% or less and a specific surface area of 1.3 m ² / g or less is disclosed. Patent Document 2 also discloses a light emitting device including a phosphor that emits red light and a phosphor that includes one or more phosphors having different emission peak wavelengths from the phosphor.

  Light emitting devices including such light emitting elements such as LEDs and phosphors are rapidly spreading. The white light emitted from the light emitting device is required to have basic characteristics such as high luminous efficiency, high luminous flux, and good color rendering. Furthermore, in recent years, the spectral intensity of this white light has been finely designed and controlled for each wavelength range of light in order to enhance its effects, appearance, and stunning effects depending on the object irradiated with light. It has become desirable to have an emission spectrum.

Japanese Patent No. 3837588 JP 2010-209111 A

However, in the red phosphor in which Eu is dissolved in the CaAlSiN ₃ crystal phase as described in Patent Document 1, since the emission center is Eu ²⁺ , the emission spectrum has a broad waveform. . In such a case, when designing a light-emitting device that emits white light by combining a plurality of types of phosphors, the emission wavelength ranges from two or more types of phosphors overlap. It becomes difficult to design and control in detail for each wavelength range of light. Furthermore, since this red phosphor is a nitride, a special production facility for firing the raw material at a high temperature in a nitrogen atmosphere is required, and the production process becomes very complicated and the production cost increases. There is also a problem.

On the other hand, in the red phosphor described in Patent Document 2, the emission spectrum is sharp because the emission ions are Mn ⁴⁺ . In such a case, the emission spectrum of white light can be easily designed and controlled. However, since the red phosphor crystal contains fluorine, it is necessary to use a fluorine compound such as hydrofluoric acid (HF) when producing the red phosphor. There is a problem with safety.

  The present invention has been made in view of the above-mentioned reasons, and has a sharp emission spectrum waveform, a red phosphor that can be manufactured by a safer and simple method, and a light emission including the red phosphor. An object is to provide an apparatus.

The phosphor according to the present invention has a structure in which Li ₂ TiO ₃ : Mn ⁴⁺ is doped with at least one of Ge and A (A is at least one selected from Na, K, and Rb).

In the first aspect of the phosphor according to the present invention,
The phosphor according to the first aspect of the present invention includes Li, Ti, and Mn, and at least one metal oxide solid solution of Ge and A (A is at least one selected from Na, K, and Rb). The ions of Li, A, Ti, Ge, and Mn are expressed in a molar ratio of (2-2x): 2x: (1-ya): y: a (x is 0 ≦ x ≦ 0.2). And y is a number that satisfies 0 ≦ y ≦ 0.5, a is a number that satisfies 0.001 ≦ a ≦ 0.3, and x and y satisfy x + y ≠ 0.

  The phosphor according to the second aspect of the present invention comprises a metal oxide solid solution of Li, Ti, Mn, and A (A is at least one selected from Na, K, and Rb), and Li, A, Ti , And Mn ions, (2-2x): 2x: (1-a): a molar ratio (x is a number satisfying 0.005 ≦ x ≦ 0.2, a is 0.001 ≦ a ≦ 0) .3))).

  The phosphor according to the third aspect of the present invention is composed of a metal oxide solid solution of Li, Ti, Ge, and Mn, and the ions of Li, Ti, Ge, and Mn are 2: (1-ya). : Y: a molar ratio (y is a number satisfying 0.01 ≦ y ≦ 0.5, a is a number satisfying 0.001 ≦ a ≦ 0.3).

  The light emitting device according to the present invention includes a light emitting element and a wavelength conversion member that emits light by absorbing light emitted from the light emitting element, and the wavelength conversion member includes the phosphor.

  The phosphor according to the present invention emits red light, has a sharp emission spectrum waveform, and is safer and can be manufactured by a simple method.

  The light emitting device according to the present invention exhibits high luminous efficiency and wavelength conversion efficiency by including the phosphor.

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. It is a schematic diagram which shows the internal structure of the wavelength conversion member with which the said light-emitting device is provided. Samples obtained in Examples 1 to 3 and Comparative Example 1, as well as for the Li ₂ TiO _3, is a graph showing the diffraction intensity curve obtained by powder X-ray diffraction measurement. Samples obtained in Examples 4-7 and Comparative Example 1, as well as for the Li ₂ TiO _3, is a graph showing the diffraction intensity curve obtained by powder X-ray diffraction measurement. Samples obtained in Examples 8-11 and Comparative Example 1, as well as for the Li ₂ TiO _3, is a graph showing the diffraction intensity curve obtained by powder X-ray diffraction measurement. Samples obtained in Examples 12 to 15 and Comparative Example 1, as well as for the _Li 2 TiO _3, is a graph showing the diffraction intensity curve obtained by powder X-ray diffraction measurement. It is a graph which shows the measurement result of an excitation spectrum and an emission spectrum about the sample obtained in Example 10. It is a graph which shows the emitted light intensity in the emission peak wavelength in the emission spectrum about Examples 1-3 and the comparative example 1. FIG. It is a graph which shows the emitted light intensity in the emission peak wavelength in the emission spectrum about Examples 4-7 and the comparative example 1. FIG. It is a graph which shows the emitted light intensity in the emission peak wavelength in the emission spectrum about Examples 8-11 and the comparative example 1. FIG. It is a graph which shows the emitted light intensity in the emission peak wavelength in the emission spectrum about Examples 12-15 and the comparative example 1. FIG.

[Phosphor]
The phosphor according to the present embodiment is a metal having a structure in which Li ₂ TiO ₃ : Mn ⁴⁺ is doped with at least one of Ge and A (A is at least one selected from Na, K, and Rb). Consists of oxide solid solution.

Li ₂ TiO ₃ : Mn ⁴⁺ is a phosphor having a structure in which Mn ^4+, which is the emission center, is doped into a crystal of Li ₂ TiO ₃ , and this is already known (Effect of crystal structure upon the luminescence). ofmanganese-activated lithium titanate Lorenz, MR; Prener, JSJ Chem. Phys. (1956), 25, 1013-15.). However, Li ₂ TiO ₃ : Mn ⁴⁺ has low luminous efficiency and has a practical problem.

On the other hand, as described above, in the phosphor according to the present embodiment, Li ₂ TiO ₃ : Mn ⁴⁺ is further doped with at least one of Ge and A (A is at least one selected from Na, K, and Rb). It consists of a metal oxide solid solution having the structure In this metal oxide solid solution, Ge ions substitute for Ti ions at a part of the site occupied by Ti ions in the crystal. Na, K, and Rb ions substitute for Li ions in a part of the site occupied by Li ions in the crystal. The phosphor according to the present embodiment has higher luminous efficiency than Li ₂ TiO ₃ : Mn ⁴⁺ .

  The emission spectrum of the phosphor according to this embodiment has a very sharp peak in the red region. For this reason, when combined with a phosphor other than the phosphor according to the present embodiment, the overall emission color can be easily controlled by adjusting the ratio of these phosphors. The excitation spectrum of the phosphor according to the present embodiment has a broad waveform ranging from near ultraviolet light to green light. Therefore, this phosphor is excited by efficiently absorbing excitation light in a wide wavelength range from near ultraviolet light to green light. Furthermore, as described above, the luminous efficiency of this phosphor is very high. The reason why this phosphor has such characteristics is not yet elucidated, but a part of Ti in the crystal is replaced by Ge, or a part of Li in the crystal is Na, K, and Rb. It is surmised that this is due to the improvement in crystallinity of the phosphor due to substitution with an alkali metal selected from the above.

  In the first aspect of the phosphor according to the present embodiment, the phosphor is at least one of Li, Ti, and Mn, and Ge and A (A is at least one selected from Na, K, and Rb). It consists of one metal oxide solid solution and contains Li, A, Ti, Ge, and Mn ions in a molar ratio of (2-2x): 2x: (1-ya): y: a. x is a number that satisfies 0 ≦ x ≦ 0.2, y is a number that satisfies 0 ≦ y ≦ 0.5, and a is a number that satisfies 0.001 ≦ a ≦ 0.3. Furthermore, x and y satisfy x + y ≠ 0.

  The composition of the phosphor according to this embodiment is represented by the following general formula (1).

_{(Li 1-x A x)} 2 (Ti 1-y-a Ge y Mn a) O 3 ... (1)
When the phosphor according to this embodiment contains A, the value x indicating the ratio of A preferably satisfies 0.005 ≦ x ≦ 0.2. In this range, the emission intensity of the phosphor is sufficiently improved by doping of A. However, since the ion radius of A is larger than that of Li ion, if the ratio of A is too large, A is difficult to be dissolved in the phosphor. The luminous efficiency of the phosphor is particularly high when A is composed of at least one of K and Rb. The value of x preferably further satisfies 0.01 ≦ x ≦ 0.1.

  When the phosphor according to this embodiment contains Ge, it is preferable that the y value indicating the Ge ratio satisfies 0.01 ≦ y ≦ 0.5. In this range, the emission intensity of the phosphor is sufficiently improved by doping with Ge. If the ratio of Ge is too large, it is difficult to form a solid solution in the Ge phosphor, and a by-product may be produced during the production of the phosphor. The value of y preferably further satisfies 0.1 ≦ y ≦ 0.3.

  a represents the ratio of Mn, and when this a satisfies 0.001 ≦ a ≦ 0.3, the luminous efficiency of the phosphor becomes particularly high. When the ratio of Mn is small, the Mn ion concentration in the phosphor is lowered, so that the luminous efficiency of the phosphor is lowered. When this value is large, concentration quenching becomes remarkable. The value of a is particularly preferably in the range of 0.01 to 0.2.

In the second aspect of the present embodiment, in the first aspect, the phosphor has a structure in which Li ₂ TiO ₃ : Mn ⁴⁺ is doped with A and is not doped with Ge. That is, the phosphor is composed of a metal oxide solid solution of Li, Ti, Mn, and A (A is at least one selected from Na, K, and Rb), and ions of Li, A, Ti, and Mn are obtained. It is contained in a molar ratio of (2-2x): 2x: (1-a): a.

  The composition of the phosphor according to this embodiment is represented by the following general formula (2).

_{(Li 1-x A x)} 2 (Ti 1-a Mn a) O 3 ... (2)
In this embodiment, x is a number that satisfies 0.005 ≦ x ≦ 0.2, and a is a number that satisfies 0.001 ≦ a ≦ 0.3.

In a third aspect of the present embodiment, in the first aspect, the phosphor has a structure in which Li ₂ TiO ₃ : Mn ⁴⁺ is doped with Ge and A is not doped. That is, the phosphor is composed of a metal oxide solid solution of Li, Ti, Mn, and A (A is at least one selected from Na, K, and Rb), and ions of Li, A, Ti, and Mn are obtained. It is contained in a molar ratio of (2-2x): 2x: (1-a): a.

  The composition of the phosphor according to this embodiment is represented by the following general formula (3).

_{Li 2 (Ti 1-y-} a Ge y Mn a) O 3 ... (3)
In this embodiment, y is a number that satisfies 0.01 ≦ y ≦ 0.5, and a is a number that satisfies 0.001 ≦ a ≦ 0.3.

An example of the manufacturing method of the phosphor according to the present embodiment will be described. First, a raw material containing Li, Ti, and Mn is prepared, and further selected from a raw material containing Na, a raw material containing K, a raw material containing Rb, and a raw material containing Ge according to the composition of the target phosphor. At least one kind of raw material is prepared. Examples of raw materials containing these metals include simple substances of these metals and metal compounds such as oxides and salts of these metals. Specifically, for example, Li ₂ CO ₃ as a raw material containing Li, TiO ₂ as a raw material containing Ti, MnO ₂ as a raw material containing Mn, Na ₂ CO ₃ as a raw material containing Na, and a raw material containing K as is _K 2 CO _3, it is _Rb 2 CO ₃ as a raw material containing Rb, GeO ₂ as a raw material containing Ge is used. A mixture is prepared by blending these raw materials.

  By firing this mixture, a solid solution reaction proceeds, whereby a material containing a phosphor according to the present embodiment (hereinafter referred to as a fluorescent material) is obtained.

  In firing the mixture, for example, the mixture is placed in a container formed of a material such as alumina or quartz. Subsequently, the mixture in the container is fired at a temperature of 1000 to 1300 ° C. in an air atmosphere. Since the atmosphere during firing is doped with Mn tetravalent, it may be an air atmosphere and does not need to be a reducing atmosphere. The heating time is appropriately set so that the solid solution reaction of the mixture proceeds sufficiently. Prior to the main firing of the mixture under such conditions, the mixture may be pre-fired in an air atmosphere in advance, and in this case, the crystallinity of the phosphor is particularly high. When the mixture is temporarily fired, the firing temperature during the temporary firing is preferably equal to or lower than the firing temperature during the main firing.

  The fluorescent material according to the present embodiment is pulverized and pulverized as necessary, and further powdered by removing unnecessary components by washing with water or acid as necessary.

  Most preferably, at the time of manufacturing the fluorescent material, the mixing ratio of the raw materials is adjusted so that the ratio of metal elements in the mixture matches the ratio of metal ions in the target phosphor. Furthermore, it is preferable that the solid solution reaction proceeds sufficiently during the firing of the mixture. In this case, a fluorescent material substantially consisting only of the phosphor according to the present embodiment is obtained. However, in this case, the fluorescent material may contain unreacted raw materials, by-products, other impurities, etc. that remain slightly.

  Thus, when the phosphor according to the present embodiment is manufactured, the phosphor according to the present embodiment is made of a metal oxide solid solution that does not contain nitrogen, fluorine, or the like, and therefore can be fired at a relatively low temperature. In addition, no special atmosphere adjustment is required. For this reason, the phosphor according to the present embodiment can be easily manufactured. Further, since it is not necessary to use a highly toxic substance such as hydrofluoric acid (HF) at the time of production, the safety at the time of production is increased.

  The phosphor according to the present embodiment can be applied to a light emitting device including a light emitting element such as an LED. The light emitting element is not particularly limited, and an appropriate light emitting element that emits light that can excite the phosphor according to the present embodiment may be used. Since the wavelength range in which the phosphor according to the present embodiment can be excited is wide, the emission wavelength range of the light emitting element can be selected from a wide range from the near ultraviolet range to the green range. For this reason, the versatility of the phosphor according to the present embodiment is very high.

A nitride semiconductor LED is mentioned as an example of a light emitting element. The nitride semiconductor in the nitride semiconductor LED is a compound semiconductor having a composition of, for example, In _x Ga _y Al _z N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, x + y + z = 1). Examples of important nitride semiconductors include AlN, GaN, AlGaN, InGaN, and AlInGaN.

[Light emitting device]
The light emitting device according to this embodiment will be described. As shown in FIGS. 1 and 2, 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 portion 50, and a wavelength conversion member (color conversion member) 70. As will be described later, the wavelength conversion member (color conversion member) 70 includes phosphor particles formed from the phosphor 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 phosphor particles 71 in the wavelength conversion member 70 are excited by the light emitted from the LED chip 10 (excitation light), and fluorescent light having a longer wavelength than the excitation light (the emission color of the LED chip 10 and 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 emitted from the light emitting device 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 goes out of the wavelength conversion member 70 through the light emission surface (surface opposite to the LED chip 10) 702 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 in the wavelength conversion member 70. Thereby, light of a color corresponding to the combination of the light emitted from the LED chip 10 and the type of phosphor particles in the wavelength conversion member 70 is emitted from the light emitting device 1.

  As shown in FIG. 3, the wavelength conversion member 70 includes a translucent medium 72 and a plurality of phosphor particles 71 dispersed in the translucent medium 72. At least a part of the phosphor particles 71 is formed from the phosphor according to the present embodiment.

  The wavelength conversion member 70, as the phosphor particles 71, is a powdered phosphor material containing the phosphor according to the present embodiment (hereinafter referred to as phosphor particles according to the present embodiment), and other than the phosphor particles according to the present embodiment. The phosphor particles may be contained.

In the case where 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, for example, the wavelength conversion member 70 is used as the phosphor particle 71 and the fluorescence according to the present embodiment. Together with the body particles, phosphor particles that emit green fluorescence (green phosphor particles) are contained. In this case, the blue light emitted from the LED chip 10 without wavelength conversion, the red light emitted from the phosphor particles according to this embodiment in the wavelength conversion member 70, and the green light emitted from the green phosphor particles Is emitted from the wavelength conversion member 70. Thereby, white light is emitted from the light emitting device 1. Specific examples of phosphors constituting the green phosphor particles that can be used in this case include (Ba, Sr) ₂ SiO ₄ : Eu ²⁺ , Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , (Ba, Sr, Ca) Si. Examples include phosphors having compositions such as ₂ O ₂ N ₂ : Eu ²⁺ , (Ca, Mg) ₃ Sc ₂ Si ₃ O ₁₂ : Ce ³⁺ , and CaSc ₂ O ₄ : Ce ³⁺ . If necessary, a red phosphor other than the phosphor particles according to the present embodiment may be used in combination with the phosphor particles according to the present embodiment. Specific examples of the phosphor constituting the red phosphor particles include fluorescence having a composition such as (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ , (Ca, Sr) AlSiN ₃ : Eu ²⁺ , CaS: Eu ^2+. The body is mentioned. The method of selecting the phosphor particles 71 for emitting white light from the light emitting device 1 is not limited to the above example.

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, the wavelength conversion member 70 is used as the phosphor particle 71, for example, according to the present embodiment. Along with the phosphor particles, phosphor particles that emit green fluorescence (green phosphor particles) and phosphor particles that emit blue fluorescence (blue phosphor particles) are contained. Specific examples of phosphors constituting the green phosphor particles that can be used in this case include (Ba, Sr) ₂ SiO ₄ : Eu ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ , (Ba, Sr, Ca). Examples thereof include phosphors having a composition such as Si ₂ O ₂ N ₂ : Eu ²⁺ . Specific examples of the phosphor constituting the blue phosphor particles include, for example, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , (Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ , Sr ₃ MgSi ₂ O ₈ : A phosphor having a composition such as Eu ²⁺ may be mentioned. If necessary, a red phosphor other than the phosphor particles according to the present embodiment may be used in combination with the phosphor particles according to the present embodiment. Specific examples of the phosphor constituting the red phosphor particles include La ₂ O ₂ S: Eu ³⁺ , (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ , (Ca, Sr) AlSiN ₃ : Eu ^{2+, and the} like. A phosphor having a composition may be mentioned.

  The particle diameter of the phosphor particles 71 is not particularly limited, but the larger the average particle diameter of the phosphor particles 71, the smaller the defect density in the phosphor particles 71, the less energy loss during light emission, and the light emission efficiency. Get higher. For this reason, from the viewpoint of improving luminous efficiency, the average particle diameter of the phosphor particles 71 is preferably 1 μm or more, and more preferably 5 μm or more. This average particle diameter is a value measured by a laser diffraction / scattering particle size distribution measuring apparatus.

  The phosphor particles 71 may be subjected to an appropriate surface treatment such as coating in order to suppress reflection of excitation light and fluorescence at the interface between the phosphor particles 71 and the translucent medium 72.

  The refractive index of the translucent medium 72 is preferably close to the refractive index of the phosphor particles 71, but is not limited thereto. 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 phosphor particles 71. 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 phosphor particles 71 in the wavelength conversion member 70 takes into consideration the types of the phosphor particles 71 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 phosphor particles 71, the phosphor particles 71 absorb the excitation light and emit 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 phosphor particles 71.

[Examples 1 to 18, Comparative Example 1]
(Production of fluorescent material)
First, Li ₂ CO ₃ powder as a raw material containing Li, Na ₂ CO ₃ powder as a raw material containing Na, K ₂ CO ₃ powder as a raw material containing K, Rb ₂ CO ₃ powder as a raw material containing Rb, TiO ₂ powder was prepared as a raw material containing Ti, GeO ₂ powder was prepared as a raw material containing Ge, and MnO ₂ powder was prepared as a raw material containing Mn.

  These raw materials were blended and mixed to prepare a mixture. At this time, the molar ratio of Li, A (at least one selected from Na, K, and Rb), Ti, Ge, and Mn in the mixture is (2-2x): 2x: (1-ya). : Y: The raw materials were blended so as to be a. Table 1 shows specific molar ratios of metal elements and values of x, y, and a in each Example.

  This mixture was placed in an alumina crucible and baked by heating at 1000 ° C. for 12 hours in the air. The sintered body thus formed was pulverized to obtain a powder sample.

[X-ray diffraction measurement]
Powder X-ray diffraction measurement using CuKα rays of the samples obtained in Examples 1 to 15 was performed. The results for Examples 1 to 3 are shown in FIG. 4, the results for Examples 4 to 7 are shown in FIG. 5, the results for Examples 8 to 11 are shown in FIG. 6, and the results for Examples 12 to 15 are shown in FIG. Shown in Furthermore, for reference, FIGS. 4 to 7 also show diffraction intensity curves obtained for Comparative Example 1 and Li ₂ TiO ₃ .

[Light emission characteristic evaluation]
Excitation spectra and emission spectra of the samples obtained in Examples 1 to 18 and Comparative Example 1 were measured. As a measuring device, a spectrofluorometer FP-6500 manufactured by JASCO Corporation was used.

  In measuring the emission spectrum, the wavelength of the excitation light was set to 450 nm. In the measurement of the excitation spectrum, the monitor wavelength was the wavelength at which the emission intensity of the emission spectrum was the maximum value in each example.

  As a result, in the samples obtained in Examples 1 to 18 and Comparative Example 1, it was confirmed that the main peak wavelength of the emission spectrum was around 680 nm. Visual observation confirmed that the emission from these samples was red. Further, in the excitation spectra of these samples, it was confirmed that the emission intensity was high in a wide wavelength range on the short wavelength side near the wavelength of 600 nm, and the emission intensity was low on the longer wavelength side.

  FIG. 8 shows the measurement results of the excitation spectrum and emission spectrum of the sample obtained in Example 10. In FIG. 8, the emission spectrum is indicated by a solid line, and the excitation spectrum is indicated by a broken line. The emission intensity is a value normalized by setting the emission intensity at the peak wavelength to 100.

  FIG. 9 shows the emission intensity at the emission peak wavelength in the emission spectrum for Comparative Example 1 and Examples 1 to 3. FIG. 10 shows the emission intensity at the emission peak wavelength in the emission spectrum for Comparative Example 1 and Examples 4-7. FIG. 11 shows the emission intensity at the emission peak wavelength in the emission spectrum for Comparative Example 1 and Examples 8 to 11. FIG. 12 shows the emission intensity at the emission peak wavelength in the emission spectrum for Comparative Example 1 and Examples 12-15. These emission intensities are values (relative emission intensity) normalized by setting the emission intensity in the case of Comparative Example 1 (x = 0, y = 0) to 100. According to these, it is confirmed that in any of the examples, the emission intensity is improved as compared with Comparative Example 1.

  Table 2 below shows the emission intensity at the emission peak wavelength in the emission spectrum for Comparative Example 1 and Examples 16 to 18. This emission intensity is also a value (relative emission intensity) normalized by setting the emission intensity in the case of Comparative Example 1 to 100. According to this, it is confirmed that in any of the examples, the emission intensity is improved as compared with Comparative Example 1.

1 Light Emitting Device 70 Wavelength Conversion Member

Claims (5)

Li ₂ TiO ₃ : A phosphor made of a metal oxide solid solution having a structure in which at least one of Ge and A (A is at least one selected from Na, K, and Rb) is doped into Mn ⁴⁺ .   Li, Ti, and Mn, and Ge and A (A is at least one selected from Na, K, and Rb) at least one metal oxide solid solution, Li, A, Ti, Ge, and Mn (2-2x): 2x: (1-ya): y: a molar ratio (x is a number satisfying 0 ≦ x ≦ 0.2, y is 0 ≦ y ≦ 0.5) The number to be satisfied, a is a number that satisfies 0.001 ≦ a ≦ 0.3, and x and y satisfy x + y ≠ 0.   It is composed of a metal oxide solid solution of Li, Ti, Mn, and A (A is at least one selected from Na, K, and Rb), and ions of Li, A, Ti, and Mn are (2-2x): 2x: (1-a): Fluorescence contained in a molar ratio (x is a number satisfying 0.005 ≦ x ≦ 0.2, and a is a number satisfying 0.001 ≦ a ≦ 0.3). body.   It is made of a metal oxide solid solution of Li, Ti, Ge, and Mn, and the ions of Li, Ti, Ge, and Mn are converted into a molar ratio of 2: (1-ya): y: a (y is 0.01 ≦ y ≦ 0.5 and a is a number satisfying 0.001 ≦ a ≦ 0.3.   A light emitting device comprising: a light emitting element; and a wavelength converting member that emits light by absorbing light emitted from the light emitting element, wherein the wavelength converting member includes the phosphor according to claim 1. .

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