WO2015029284A1

WO2015029284A1 - Phosphor and light-emitting device using same

Info

Publication number: WO2015029284A1
Application number: PCT/JP2014/002508
Authority: WO
Inventors: 山崎　圭一; 大塩　祥三; 惠美宮崎; 真治柴本
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2013-08-28
Filing date: 2014-05-13
Publication date: 2015-03-05
Also published as: JP2016188263A

Abstract

A phosphor containing a luminescent center and light-absorbing ions in a matrix. The light-absorbing ions have a wavelength range over which fluorescent components emitted by the luminescent center can be partially absorbed and have a light-emitting spectrum that has a depression over said wavelength range. Light emission that is color controlled and that has a desired and specific light-emitting spectrum shape can thereby be achieved, even without using a member that has an optical filtering function.

Description

Phosphor and light emitting device using the same

The present invention relates to a phosphor and a light emitting device using the phosphor. More specifically, the present invention relates to a phosphor whose color tone is controlled to obtain preferable illumination light and a light emitting device using the same.

Conventionally, yttrium aluminum garnet (YAG; Y ₃ Al ₂ (AlO ₄ ) ₃ ) including a light emission center is known as a phosphor. In particular, the YAG: Ce phosphor activated with Ce ³⁺ is known as a high-efficiency phosphor and is used in many light emitting devices. A YAG: Ce phosphor is excited when irradiated with a particle beam or an electromagnetic wave, and has a characteristic of emitting yellow to green visible light with ultrashort afterglow (see, for example, Non-Patent Document 1).

In the fluorescence emitted by the phosphor, when the intensity of the yellow light component is large, the color of the object illuminated by the fluorescence may be visually recognized as a color with a low vividness due to the conspicuous yellowing. 2. Description of the Related Art Conventionally, fluorescent lamps that reduce yellowing of an object color and show the object color vividly are known. Specifically, this is a fluorescent lamp in which a phosphor layer is formed on the inner surface of a glass tube, and a glass thin film (Nd glass frit) containing Nd ³⁺ ions is formed between the glass tube and the phosphor layer. . (For example, refer to Patent Document 1).

Japanese Patent Application Laid-Open No. 2000-11954

The phosphor of the present invention contains a luminescent center and light-absorbing ions in the matrix, and the light-absorbing ions have a wavelength region that can partially absorb the fluorescent component emitted by the luminescent center. And the emission spectrum of this fluorescent substance has a hollow in the wavelength range which can absorb light absorption ion.

With the above configuration, a desired special fluorescence spectrum shape can be obtained without using a member having an optical filter function (hereinafter referred to as an “optical filter member”) such as the glass thin film containing Nd ³⁺ ions. That is, a phosphor having a color tone controlled can be obtained.

Schematic for demonstrating the light-emitting device of embodiment of this invention. Schematic for demonstrating the light-emitting device of embodiment of this invention. Sectional drawing which shows typically the semiconductor light-emitting device which is an example of the light-emitting device in embodiment of this invention The block diagram for demonstrating an example of the light-emitting device in embodiment of this invention The block diagram for demonstrating an example of the light-emitting device in embodiment of this invention The figure of the XRD pattern of the compound (phosphor) in the embodiment of the present invention Diagram of emission spectrum of compound (phosphor) in an embodiment of the present invention Diagram of emission spectrum and average color rendering index Ra obtained from simulation performed using each emission spectrum of blue LED, compound (phosphor) in embodiment of the present invention, and red phosphor

Prior to the description of the embodiments of the present invention, problems in conventional phosphors will be described.

In general, it is difficult to obtain a desired special emission spectrum shape by reducing the intensity of a specific wavelength region without using an optical filter member (see Patent Document 1) in the emission spectrum of a phosphor. Controlling the color tone of the emission spectrum using an optical filter member increases costs and man-hours.

Hereinafter, a phosphor according to an embodiment of the present invention that emits an emission spectrum whose color tone is controlled without using an optical filter member, and a light emitting device using the phosphor will be described in detail. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

[Phosphor]
The phosphor in the embodiment of the present invention contains a luminescent center and light absorbing ions in the matrix. The light-absorbing ions can partially absorb the fluorescent component emitted by the emission center. The emission spectrum of this phosphor has a depression in a wavelength region where light absorbing ions can be absorbed.

Generally, a phosphor is a compound in which a part of an element constituting a crystalline compound is partially substituted with an element that can be an ion having a fluorescence emission property. Ions having such characteristics are called emission centers. In the phosphor of the present embodiment, ions that are the emission center are introduced into the matrix that is a crystalline compound. Thereby, this fluorescent substance is easily excited by an external stimulus and can emit fluorescence. Examples of external stimuli include irradiation with particle beams (α rays, β rays, electron beams) and electromagnetic waves (γ rays, X rays, vacuum ultraviolet rays, ultraviolet rays, visible rays).

Furthermore, in the phosphor of this embodiment, light absorbing ions capable of partially absorbing the fluorescent component emitted from the emission center are introduced into the above-described general phosphor as a base. Thereby, the light absorption ion contained in a fluorescent substance acts so that a part of fluorescent component may be absorbed. That is, the phosphor itself has the function of an optical filter member. And the shape of the emission spectrum which this fluorescent substance emits becomes the same shape as the case where an optical filter member is used. That is, the phosphor of the present embodiment can exhibit the same effects as when a general phosphor and an optical filter member are used without using an optical filter member.

More specifically, as a specific example of the present embodiment, FIG. 6 shows a case where yttrium aluminum garnet (Y ₃ Al ₂ (AlO ₄ ) ₃ ) is used as a base, Ce ³⁺ is introduced into the emission center, and light absorbing ions are further introduced. Shows the emission spectrum of the phosphor into which Nd ³⁺ is introduced. Here, X is the molar fraction of Nd ³⁺ that becomes light absorbing ions in 1 mol of the phosphor. The emission spectrum of X = 0 indicates the emission spectrum of the phosphor not having the light absorbing ion introduced therein, and the emission spectra of X = 0.001, 0.01, 0.1 are the emission of the phosphor having the light absorbing ion introduced therein. Each spectrum is shown. As shown in FIG. 6, a phosphor into which light-absorbing ions are not introduced has a broad emission spectrum distribution (component) in the visible light region, and emits fluorescence close to the spectrum distribution of black body radiation. However, when Nd ³⁺ is introduced as light absorbing ions, the intensity around 580 nm is reduced in the emission spectrum. The evaluation of the specific example shown in FIG. 6 will be described later.

In this way, by introducing light absorbing ions into the phosphor, the light absorbing ions absorb a part of the fluorescent component (fluorescence spectrum). Therefore, in the fluorescent component due to the emission center (for example, Ce ³⁺ ), the intensity of the wavelength region corresponding to the light absorption of the light absorbing ions is lowered. In other words, in this phosphor, the emission spectrum is induced by light-absorbing ions and has a partial depression. Therefore, the phosphor of this embodiment can emit an emission spectrum controlled to a desired color tone without using an optical filter member in the phosphor itself. In the present specification, the depression of the emission spectrum refers to a phenomenon in which the intensity of the emission spectrum is partially reduced or reduced due to the introduction of light-absorbing ions into the phosphor.

The phosphor of the present embodiment may be an inorganic compound or an organic compound as long as a depression is generated in the emission spectrum. However, the phosphor of the present embodiment is preferably an inorganic compound. Many inorganic compounds are relatively thermally and chemically stable as compared to organic compounds. In addition, many phosphors that have been put into practical use have a track record. Therefore, in an apparatus (for example, a light-emitting device) to which this phosphor is applied, reliability is improved by using an inorganic compound as the phosphor.

Furthermore, the phosphor of the present embodiment preferably has the maximum intensity of the fluorescent component in the wavelength region of visible light. That is, this phosphor preferably has the maximum intensity of the fluorescent component (fluorescence spectrum) in the visible light region having a wavelength of 380 nm or more and 780 nm or less. This is because, in general, many light emitting devices using phosphors use visible light, so the range of applications of the phosphors is widened.

Further, as the wavelength region having the maximum intensity, a wavelength region of 420 nm or more and less than 660 nm is preferable. This is because by selecting this region, which is a wavelength region with high visibility, it is possible to improve the efficiency of the device using this phosphor. Furthermore, the maximum intensity is preferably in any of the wavelength regions of the three primary colors of light. That is, any one of a wavelength region of 420 nm or more and less than 500 nm that is blue light, a wavelength region of 520 nm or more and less than 600 nm that is green light to orange light, or a wavelength region that is 600 nm or more and less than 660 nm that is red light . This is because, in addition to the effect of increasing the efficiency described above, it is easy to design a light color in a wide range in chromaticity coordinates.

The matrix constituting the phosphor of the present embodiment preferably has a garnet crystal structure. A phosphor using a compound having a garnet-type crystal structure as a matrix has a high practical record as can be seen from the fact that it is used in LED lighting. There are also many types of light-emitting devices that apply this phosphor. Therefore, a phosphor using a compound having a garnet-type crystal structure as a matrix is a phosphor having high industrial utility value. Here, the garnet-type compound that can be used as a base is not particularly limited as long as the above-described effects are obtained. Preferably, for example, Y ₃ Al ₂ (AlO ₄ ) ₃ , Lu ₃ Al ₂ (AlO ₄ ) ₃ , Y ₃ Ga ₂ (AlO ₄ ) ₃ , (Y, Gd) ₃ Al ₂ (AlO ₄ ) _{3 as the base material.} An aluminum garnet type compound such as can be used. Further, Ca ₃ Sc ₂ (SiO ₄ ) ₃ or the like is also preferable. Among these, Y ₃ Al ₂ (AlO ₄ ) ₃ having high luminous efficiency is particularly preferable.

In the phosphor of the present embodiment, the half width (FWHM) of the fluorescence spectrum emitted from the phosphor that does not include light-absorbing ions and includes only luminescent ions, that is, the base phosphor, is 50 nm or more and less than 150 nm. It is preferable. That is, in the example of FIG. 6, it is preferable that the half width of the fluorescence spectrum (X = 0) of the base YAG: Ce ³⁺ not containing Nd ³⁺ as light absorbing ions is 50 nm or more and less than 150 nm. In this case, since the fluorescence spectrum has a wide distribution in the visible light region, it is relatively easy to obtain light having a spectral distribution close to blackbody radiation. In addition, since the components of the fluorescence spectrum are distributed over a wide wavelength range, it is possible to easily obtain a fluorescence spectrum with conspicuous depressions. It becomes easy to demonstrate the effect by the dent.

The luminescent center constituting the phosphor of the present embodiment may be a compound that functions as the host of the phosphor. That is, the emission center may be any ion that can emit fluorescence by electron energy transition in the host crystal. As specific emission centers, at least Sn ²⁺ , Sb ³⁺ , Tl ⁺ , Pb ²⁺ and Bi ³⁺ called ns ² ion emission centers and Cr ³⁺ , Mn ⁴⁺ , Mn ²⁺ and Fe ³⁺ called transition metal ion emission centers are used. It is preferable to use one. Further, at least one of ^Ce 3+ called rare earth ions luminescence ^{^{^{^{center, Pr 3+, Sm 3+, Tb}}}} 3+, Gd 3+, Dy 3+, Ho 3+, Tm 3+, Yb 3+, Sm 2+, Eu 2+, Eu 3+ and ^{Yb 2+} It is also preferred to use Among these, the emission center is particularly preferably Ce ³⁺ . The phosphor having Ce ³⁺ as the emission center has many practical achievements in LED lighting and the like. Furthermore, there are many types of light emitting devices that apply this phosphor. By using Ce ³⁺ as the emission center, it is possible to easily realize a phosphor having high industrial utility value.

It is preferable that the wavelength region in which the light-absorbing ions can be absorbed in the phosphor of the present embodiment is in the wavelength region of 560 nm or more and less than 600 nm.

Further, in the emission spectrum of the phosphor of the present embodiment, it is preferable that the above-mentioned depression is in a wavelength region of 560 nm or more and less than 600 nm. In this case, the fluorescence spectrum has a relatively small intensity of the yellow light component that causes yellowing. Therefore, by using this fluorescence for illumination light, the illumination light can enhance the vividness of the appearance of the object, and the whiteness and cleanliness can be emphasized.

Furthermore, in the fluorescence spectrum of the phosphor of the present embodiment, the intensity at a wavelength of 580 nm is preferably less than 70% with respect to the maximum intensity. In the emission spectrum shown in FIG. 6, since the maximum intensity is shown at 550 nm, the emission intensity at 580 nm with respect to the emission intensity at 550 nm is preferably less than 70%. This is an emission spectrum in which the intensity of the yellow light component that causes yellowing is significantly suppressed. Therefore, by using this emission spectrum for the illumination light, it is possible to enhance the vividness of the appearance of the object and to emphasize the whiteness and cleanliness. Furthermore, in order to limit the decrease in the luminous efficiency of the phosphor, the intensity at a wavelength of 580 nm is preferably 60% or more with respect to the maximum intensity.

The light-absorbing ions introduced into the phosphor of this embodiment are not particularly limited as long as it partially absorbs the fluorescent component emitted by the emission center and induces a depression in the fluorescence spectrum. However, from the viewpoint of efficiently controlling the color tone, the light absorption ions are preferably trivalent rare earth element ions. Since trivalent rare earth element ions often have steep absorption characteristics, that is, specific absorption characteristics in their absorption spectrum, it is easy to obtain a specific fluorescence spectrum.

Examples of the trivalent rare earth element ion include at least one selected from the group consisting of Ce ³⁺ , Pr ³⁺ , Nd ³⁺ , Sm ^3+, and Eu ³⁺ . Examples of the trivalent rare earth element ion include at least one selected from the group consisting of Gd ³⁺ , Tb ³⁺ , Dy ³⁺ , Ho ³⁺ , Er ³⁺ , Tm ³⁺ , and Yb ³⁺ . Among these, the light absorbing ions are preferably at least one of Nd ³⁺ and Eu ³⁺ , and particularly preferably Nd ³⁺ . Since Nd ³⁺ and Eu ³⁺ have strong absorption characteristics in the visible light region, it is possible to easily control the color tone in the emission spectrum. In particular, since Nd ³⁺ has a strong absorption characteristic in the yellow wavelength region, it is possible to effectively reduce the intensity of the yellow light component.

In the fluorescence spectrum of the phosphor of this embodiment, the amount of light absorbing ions added is preferably 0.01 mol or more and less than 0.5 mol per mol of the phosphor. When the amount of light absorbing ions added is 0.01 mol or more, the fluorescent component absorbs and the phosphor itself has the function of an optical filter. Moreover, when the addition amount of light absorption ion is less than 0.5 mol, it becomes possible to suppress the fall of the emitted light intensity of fluorescent substance. In addition, from the viewpoint of obtaining a phosphor with high emission intensity and high color tone control, the amount of light absorbing ions added is more preferably 0.01 mol or more and 0.1 mol or less per mol of the phosphor. , 0.03 mol or more and 0.1 mol or less is particularly preferable.

It should be noted that the phosphor of this embodiment can be used in the form of a slurry, paste, sol, or gel by appropriately mixing with a solvent such as water, an organic solvent, a resin, or water glass.

As described above, in the phosphor of the present embodiment, the light absorbing ions absorb a part of the fluorescent component by introducing the light absorbing ions. Therefore, the emission spectrum is induced by light absorbing ions and has a partial depression. As a result, this phosphor has an unprecedented characteristic that it can emit light whose color tone is controlled without using an optical filter member.

[Light emitting device]
Next, the light emitting device in the embodiment of the present invention will be described. The light emitting device of the present embodiment includes the phosphor described above. As described above, the phosphor of this embodiment emits light having a desired special spectral shape and color tone control. For this reason, the light emitting device of the present embodiment has a configuration in which the phosphor and an excitation source for exciting the phosphor are combined. With this configuration, it is possible to output light whose color tone is effectively controlled.

Hereinafter, the light emitting device of this embodiment will be described with reference to the drawings. 1A and 1B are schematic views of a light emitting device according to this embodiment. In FIG. 1A and FIG. 1B, the excitation source 1 is a light source that generates primary light for exciting the phosphor 2. As an excitation source 1 that emits primary light, particle beams such as α-rays, β-rays, electron beams, γ-rays, X-rays, vacuum ultraviolet rays, ultraviolet rays, visible light (especially short-wavelength visible light such as violet light and blue light). A radiation device that emits electromagnetic waves such as can be used. As the excitation source 1, various radiation generators, electron beam emitters, discharge light generators, solid state light emitting elements, solid state light emitters, and the like can be used. Typical examples of the excitation source 1 include an electron gun, an X-ray tube, a rare gas discharge device, a mercury discharge device, a light emitting diode, a laser light generator including a semiconductor laser, and an inorganic or organic electroluminescence element. Can do.

1A and 1B, the output light 4 is fluorescence emitted by the phosphor 2 excited by an excitation line or excitation light (hereinafter referred to as “excitation light”) 3 emitted by the excitation source 1. The output light 4 is used as illumination light or display light in the light emitting device.

FIG. 1A shows a light emitting device having a structure in which output light 4 from the phosphor 2 is emitted in a direction in which the phosphor 2 is irradiated with excitation rays or excitation light 3. Note that examples of the light-emitting device illustrated in FIG. 1A include a white LED light source, a fluorescent lamp, and an electron tube. On the other hand, FIG. 1B shows a light emitting device having a structure in which output light 4 from the phosphor 2 is emitted in a direction opposite to the direction in which the phosphor 2 is irradiated with excitation rays or excitation light 3. As the light emitting device shown in FIG. 1B, a plasma display device, a light source device using a phosphor wheel with a reflector, a projector, and the like can be given.

In the arrangement of the phosphor 2 and the excitation source 1, the phosphor 2 may be arranged in the optical path of the primary light emitted from the excitation source 1.

Preferred examples of the light emitting device of this embodiment are a semiconductor light emitting device, an illumination light source, an illumination device, a liquid crystal panel with an LED backlight, an LED projector, a laser projector, and the like configured using a phosphor. A particularly preferred light-emitting device has a structure that excites a phosphor with short-wavelength visible light, and the short-wavelength visible light has a structure that a solid-state light emitting element emits.

The light emitting device of the present embodiment widely includes electronic devices having a function of emitting light, and is not particularly limited as long as it is an electronic device that emits some light. That is, the light emitting device of the present embodiment is a light emitting device that uses at least the phosphor of the present embodiment and further uses light emitted from the phosphor as at least output light.

As described above, the light-emitting device of this embodiment combines a phosphor and an excitation source that excites the phosphor. And this fluorescent substance absorbs the energy which an excitation source emits, and converts the absorbed energy into the fluorescence by which the color tone was controlled. The excitation source can be appropriately selected from a discharge device, an electron gun, a solid light emitting element, etc. according to the excitation characteristics of the phosphor.

There are many light emitting devices that use phosphors. For example, a fluorescent lamp, an electron tube, a plasma display panel (PDP), a white LED, and a detection device using a phosphor correspond to this. In a broad sense, an illumination light source and an illumination device using a phosphor, a display device, and the like are also light emitting devices, and a projector including a laser diode, a liquid crystal display including an LED backlight, and the like can be regarded as the light emitting device. Here, since the light-emitting device of this embodiment can be classified according to the type of fluorescence emitted by the phosphor, this classification will be described.

Fluorescence phenomena used in electronic devices are academically divided into several categories, and are distinguished by terms such as photoluminescence, cathodoluminescence, and electroluminescence. “Photoluminescence” refers to fluorescence emitted by a phosphor when the phosphor is irradiated with an electromagnetic wave. Note that the term “electromagnetic wave” collectively refers to X-rays, ultraviolet rays, visible light, infrared rays, and the like. “Cathodeluminescence” refers to fluorescence emitted by a phosphor when the phosphor is irradiated with an electron beam. Electroluminescence refers to fluorescence emitted when electrons are injected into a phosphor or an electric field is applied. In principle, there is also a term “thermoluminescence” as fluorescence close to photoluminescence. This refers to the fluorescence emitted by the phosphor when heat is applied to the phosphor. In addition, there is also a term of radioluminescence (radioluminescence) as fluorescence close to cathodoluminescence in principle. This refers to the fluorescence emitted by the phosphor when the phosphor is irradiated with radiation.

As described above, the light emitting device according to the present embodiment uses at least the fluorescence emitted from the above-described phosphor as output light. Since the fluorescence here can be classified at least as described above, the fluorescence can be replaced with at least one fluorescence phenomenon selected from the luminescence.

Typical examples of the light emitting device that uses the photoluminescence of the phosphor as output light include an X-ray image intensifier, a fluorescent lamp, a white LED, a semiconductor laser projector using a phosphor and a laser diode, and a PDP. . Typical examples of a light emitting device that uses cathodoluminescence as output light include an electron tube, a fluorescent display tube, and a field emission display (FED). Furthermore, typical examples of a light-emitting device that uses electroluminescence as output light include inorganic electroluminescence displays (inorganic EL), light-emitting diodes (LED), semiconductor lasers (LD), and organic electroluminescence elements (OLED).

2 will be described as an example of a specific light emitting device. FIG. 2 is a cross-sectional view schematically showing the semiconductor light emitting device 12. FIG. 2 is a cross-sectional view, and hatching indicating a cross section of the translucent resin 10 is omitted in consideration of easy viewing of the drawing. The semiconductor light emitting device 12 has a wavelength conversion layer 9 including a solid light emitting element 6 as an excitation source and the phosphor 2.

In FIG. 2, the solid light emitting element 6 is fixed to the substrate 5. The substrate 5 is made of ceramics such as Al ₂ O ₃ and AlN, metals such as Al and Cu, glass, silicone resin, and resin such as filler-filled silicone resin.

In addition, a wiring conductor 7 is provided on the substrate 5. The solid state light emitting device 6 has a feeding electrode 8. Power is supplied to the solid state light emitting element 6 by electrically connecting the power supply electrode 8 and the wiring conductor 7 using a gold wire or the like.

The solid state light emitting device 6 that is a light source that generates primary light converts electrical energy into light energy such as near ultraviolet light, purple light, or blue light. The electrical energy is supplied to the solid state light emitting device 6 as at least one power selected from direct current, alternating current, and pulse. As the solid light-emitting element 6, an LED, a laser diode (LD), an inorganic electroluminescence (EL) element, an organic EL element, or the like can be used. In particular, in order to obtain primary light having a high output and a narrow spectral half width, the solid-state light emitting element 6 is preferably an LED or an LD. FIG. 2 shows a configuration in which an LED having an InGaN-based compound as a light emitting layer is used as the solid light emitting element 6.

The wavelength conversion layer 9 includes the phosphor 2 and covers the solid light emitting element 6. The phosphor 2 converts the wavelength of the primary light emitted from the solid light emitting element 6 into secondary light having a relatively long wavelength. As shown in FIG. 2, the wavelength conversion layer 9 is surrounded by the side wall 11. Furthermore, the particles of the phosphor 2 described in the present embodiment are dispersed in the translucent resin 10 constituting the wavelength conversion layer 9. In FIG. 2, the wavelength conversion layer 9 covers the upper surface and side surfaces of the solid light emitting element 6. However, the arrangement of the wavelength conversion layer 9 is not limited to this form. The wavelength conversion layer 9 should just be arrange | positioned in the optical path of the light which the solid light emitting element 6 emits. For example, it is also possible to dispose only on the upper surface of the solid light emitting element 6 or to dispose it above the solid light emitting element 6 without directly contacting it. You may arrange | position under the solid light emitting element 6. FIG. The wavelength conversion layer 9 may be configured such that the phosphor 2 is contained in a light-transmitting light-emitting material such as fluorescent resin, fluorescent ceramics, or fluorescent glass.

In the wavelength conversion layer 9, the phosphor 2 of the present embodiment can be used alone as a phosphor. If necessary, a phosphor different from the phosphor 2 of this embodiment may be added. Moreover, you may use combining the fluorescent substance 2 from which at least any one of luminescent color or a composition differs in multiple types.

The phosphor that is different from the phosphor 2 of the present embodiment and that can be used for the wavelength conversion layer 9 absorbs the primary light emitted from the solid-state light emitting element 6 and has a relatively long wavelength. Wavelength conversion to secondary light. Such a phosphor does not contain light absorbing ions. By appropriately selecting from various phosphors that emit blue light, green blue light, blue green light, green light, yellow light, orange light, and red light, the semiconductor light emitting device 12 emits output light of a desired color. can do.

As described above, as the phosphor of the semiconductor light emitting device 12 when the solid state light emitting element 6 is an LED or LD, the phosphor 2 into which the light absorbing ions of this embodiment are introduced can be used. Examples of the phosphor that can be used in combination with the phosphor 2 include the following existing phosphors. For example, an oxide phosphor such as an oxide or acid halide activated by at least one of Eu ²⁺ , Ce ³⁺ , Tb ³⁺ , and Mn ²⁺ can be used. Further, nitride phosphors such as nitrides and oxynitrides activated by at least one of Eu ²⁺ , Ce ³⁺ , Tb ³⁺ and Mn ²⁺ , and sulfide phosphors such as sulfides and oxysulfides are also included. Can be used.

Specifically, as the blue phosphor, for example, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , CaMgSi ₂ O ₆ : Eu ²⁺ , Ba ₃ MgSi ₂ O ₈ : Eu ²⁺ , Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ Etc. can be used. For example, Sr ₄ Si ₃ O ₈ Cl ₄ : Eu ²⁺ , Sr ₄ Al ₁₄ O ₂₄ : Eu ²⁺ , BaAl ₈ O ₁₃ : Eu ²⁺ , Ba ₂ SiO ₄ : Eu ²⁺ is used as the green-blue or blue-green phosphor. Can do. Further, as a green-blue or blue-green phosphor, for example, BaZrSi ₃ O ₉ : Eu ²⁺ , Ca ₂ YZr ₂ (AlO ₄ ) ₃ : Ce ³⁺ , Ca ₂ YHf ₂ (AlO ₄ ) ₃ : Ce ³⁺ , Ca ₂ YZr ₂ ( AlO ₄ ) ₃ : Ce ³⁺ , Tb ³⁺ can be used. As the green phosphor, for example, (Ba, Sr) ₂ SiO ₄ : Eu ²⁺ , Ca ₈ Mg (SiO ₄ ) ₄ Cl ₂ : Eu ²⁺ , Ca ₈ Mg (SiO ₄ ) ₄ Cl ₂ : Eu ²⁺ , Mn ²⁺ are used. Can be used. Further, as the green phosphor, for example, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ , CeMgAl ₁₁ O ₁₉ : Mn ²⁺ , Y ₃ Al ₂ (AlO ₄ ) ₃ : Ce ³⁺ , Lu ₃ Al ₂ (AlO ₄ ) ₃ : Ce ³⁺ can be used. Also, as the green phosphor, for _{_{_{_{example, Y 3 Ga 2 (AlO 4}}}} ) 3: Ce 3+, Ca 3 Sc 2 Si 3 O 12: Ce 3+, CaSc 2 O 4: Ce 3+, β-Si 3 N 4: Eu ²⁺ , SrSi ₂ O ₂ N ₂ : Eu ²⁺ can be used. Examples of green phosphors include Ba ₃ Si ₆ O ₁₂ N ₂ : Eu ²⁺ , Sr ₃ Si ₁₃ Al ₃ O ₂ N ₂₁ : Eu ²⁺ , YTbSi ₄ N ₆ C: Ce ³⁺ , SrGa ₂ S ₄ : Eu ²⁺ . Can be used. As a green phosphor, for _{_{_{_{example, Ca 2 LaZr 2 (AlO 4}}}} ) 3: Ce 3+, Ca 2 TbZr 2 (AlO 4) 3: Ce 3+, Ca 2 TbZr 2 (AlO 4) 3: Ce 3+, using ^{Pr 3+} be able to. For example, Zn ₂ SiO ₄ : Mn ²⁺ , MgGa ₂ O ₄ : Mn ²⁺ can be used as the green phosphor. As the green phosphor, for example, LaPO ₄ : Ce ³⁺ , Tb ³⁺ , Y ₂ SiO ₄ : Ce ³⁺ , CeMgAl ₁₁ O ₁₉ : Tb ³⁺ , GdMgB ₅ O ₁₀ : Ce ³⁺ , Tb ³⁺ can be used. As the yellow or orange phosphor, for example, (Sr, Ba) ₂ SiO ₄ : Eu ²⁺ , (Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ , α-Ca—SiAlON: Eu ²⁺ can be used. As the yellow or orange phosphor, for example, Y ₂ Si ₄ N ₆ C: Ce ³⁺ , La ₃ Si ₆ N ₁₁ : Ce ³⁺ , Y ₃ MgAl (AlO ₄ ) ₂ (SiO ₄ ): Ce ³⁺ can be used. . Examples of the red phosphor include Sr ₂ Si ₅ N ₈ : Eu ²⁺ , CaAlSiN ₃ : Eu ²⁺ , SrAlSi ₄ N ₇ : Eu ²⁺ , CaS: Eu ²⁺ , La ₂ O ₂ S: Eu ³⁺ , Y ₃ Mg ₂ (AlO ₄ ) (SiO ₄ ) ₂ : Ce ³⁺ can be used. Further, as the red phosphor, for example, Y ₂ O ₃ : Eu ³⁺ , Y ₂ O ₂ S: Eu ³⁺ , Y (P, V) O ₄ : Eu ³⁺ , YVO ₄ : Eu ³⁺ can be used. As the red phosphor, for example, 3.5 MgO.0.5 MgF ₂ .GeO ₂ : Mn ⁴⁺ , K ₂ SiF ₆ : Mn ⁴⁺ , GdMgB ₅ O ₁₀ : Ce ³⁺ , Mn ²⁺ can be used.

In addition, the low-cost semiconductor light-emitting device 12 is realizable by making all the fluorescent substance to use an oxide.

Here, an example of a manufacturing method of the semiconductor light emitting device 12 shown in FIG. 2 will be described. First, the solid state light emitting element 6 is fixed on the substrate 5 on which the wiring conductor 7 is formed by using a mounting technique. Next, the power supply electrode 8 of the solid light emitting element 6 and the wiring conductor 7 are electrically connected using a wire bonding technique or the like. On the other hand, a light-transmitting resin 10 such as an uncured silicone resin and the phosphor 2 are sufficiently mixed to produce a phosphor paste adjusted to have a predetermined viscosity. The weight ratio of the phosphor 2 in the phosphor paste is set to several% to several tens%. The light extraction surface of the solid light emitting element 6 is covered by dropping the phosphor paste onto the solid light emitting element 6 that is electrically connected with the phosphor paste. Then, the phosphor paste is solidified. Thereby, the semiconductor light emitting device 12 having the wavelength conversion layer 9 can be obtained.

When a predetermined power is supplied to the solid state light emitting device 6 in the semiconductor light emitting device 12, the solid state light emitting device 6 emits primary light. This primary light is, for example, violet light having an emission peak in a wavelength range of 380 nm or more and less than 420 nm, or blue light having an emission peak in a wavelength range of 420 nm or more and less than 470 nm. This primary light is converted into secondary light whose color tone is controlled by the wavelength conversion layer 9 including the phosphor 2.

The primary light is irradiated to the phosphor 2 included in the wavelength conversion layer 9 and part of the light is absorbed by the phosphor 2. The primary light absorbed by the phosphor 2 is wavelength-converted by the phosphor 2 into secondary light having a relatively long wavelength. Then, the secondary light passes through the translucent resin 10 and is emitted from the semiconductor light emitting device 12. At the same time, the primary light that has not been absorbed by the phosphor 2 passes through the translucent resin 10 and is emitted from the semiconductor light emitting device. As a result, both the primary light and the secondary light are emitted from the semiconductor light emitting device 12. That is, the semiconductor light emitting device 12 outputs both of them in an additive color mixed state.

It should be noted that the thickness and light transmittance of the wavelength conversion layer 9, the type and mixing ratio of the phosphors 2 contained in the wavelength conversion layer 9, the wavelength of the primary light emitted from the solid light emitting element 6 and the like can be adjusted as appropriate. That is, the semiconductor light emitting device 12 can be designed to output light of a desired light color. In some cases, all of the primary light is absorbed by the phosphor 2 and wavelength-converted. In this case, the emitted light from the semiconductor light emitting device 12 is only the secondary light wavelength-converted by the phosphor.

As described above, the semiconductor light emitting device 12 is configured by a combination of the solid light emitting element 6 and the phosphor 2 that absorbs light emitted from the solid light emitting element 6 and emits fluorescence whose color tone is controlled. In particular, the semiconductor light emitting device 12 can emit fluorescence with a relatively small intensity of the yellow light component that causes yellowing. Therefore, by using the emitted light from the semiconductor light emitting device 12 as illumination light, the object looks like a color with little yellowing or a color without yellowing. That is, the vividness of the object color can be enhanced. By using the semiconductor light emitting device 12 for an illumination light source or an illumination device, it is possible to easily obtain illumination light that makes whiteness and cleanliness stand out.

In the semiconductor light emitting device 12, the same operational effects as when the optical filter member is used can be obtained without using the optical filter member. With this configuration, it is possible to reduce the number of components of the semiconductor light emitting device 12 and the number of manufacturing steps thereof.

The semiconductor light emitting device 12 can be widely used as an illumination light source, a backlight of a liquid crystal display, a light source of a display device, and the like. The semiconductor light emitting device 12 can emit light that enhances the vividness of an object and highlights a sense of whiteness and cleanliness. Therefore, when the semiconductor light emitting device 12 is used as an illumination light source or the like, it is possible to provide an illumination light source with high color rendering properties and high efficiency, and a display device capable of displaying a wide color gamut on a high luminance screen.

A block diagram of the illumination light source is shown in FIG. The illumination light source is an example of the light-emitting device of the present embodiment, and includes a semiconductor light-emitting device 12, a lighting circuit 13 that operates and lights the semiconductor light-emitting device 12, and a base part 14 that connects the illumination light source such as a base to a lighting fixture. is doing. The lighting circuit has a function of supplying a constant current to the semiconductor light emitting device 12, for example. Electric power is supplied to the lighting circuit 13 from the outside of the illumination light source via the base part 14.

The block of the lighting device is shown in FIG. The lighting device is an example of the light emitting device of the present embodiment, and includes a semiconductor light emitting device 12 and a control circuit 15 that controls power supplied to the semiconductor light emitting device 12. The control circuit has a function of controlling supply power based on a signal from the outside of the lighting device, for example. Power is supplied to the control circuit from the outside of the lighting device.

An illumination system is a system having a function of controlling a plurality of illumination light sources and illumination devices.

The display device is a modification of the light emitting device, and includes a plurality of semiconductor light emitting devices 12 arranged in a matrix and a signal circuit for turning the semiconductor light emitting devices 12 on and off. As a display device, a liquid crystal panel with an LED backlight can be given. In the backlight, a plurality of semiconductor light emitting devices 12 are arranged in a line shape or a matrix shape. A liquid crystal panel backlight with LED backlight, a lighting circuit for turning on the backlight or a control circuit for ON / OFF control of the backlight, and a liquid crystal panel are combined.

Thus, since the light emitting device has good characteristics in terms of visibility and visibility, it can be widely used for the above-described illumination light source, illumination device, display device, and the like.

Hereinafter, the present embodiment will be described in more detail with specific examples. However, the present invention is not limited to this.

[material]
Using a preparation method that utilizes a solid-phase reaction, phosphors are synthesized and their characteristics are evaluated. The compound powder used as a raw material and its purity are as follows.

Yttrium oxide (Y ₂ O ₃ ): purity 3N,
Aluminum oxide (θ-Al ₂ O ₃ ): purity 4N5,
Neodymium oxide (Nd ₂ O ₃ ): purity 3N,
Cerium oxide (CeO ₂ ): purity 4N.

Note that AKP-G008 manufactured by Sumitomo Chemical Co., Ltd. is used for the above aluminum oxide for the purpose of increasing the reactivity between the raw materials. However, the present invention is not limited to this.

Also, the compound powder used as a flux (reaction accelerator) and its purity are as follows.

Aluminum fluoride (AlF ₃ ): purity 3N,
Potassium carbonate (K ₂ CO ₃ ): purity 2N5.

[Sample preparation]
First, each raw material and reaction accelerator are weighed so as to have the ratio shown in Table 1. Next, these raw materials and reaction accelerator are mixed with an appropriate amount of solvent, and stirred for 1 hour using a ball mill. And the raw material after mixing is moved to a container, and it dries at 150 degreeC for 2 hours using a dryer. The mixed raw material after drying is pulverized using a mortar and pestle. This pulverized mixed raw material is a calcined raw material. Thereafter, the firing raw material is transferred to an alumina crucible with a lid, and fired in an atmosphere at 1600 ° C. for 2 hours using a box-type electric furnace.

In this way, the composition formula is (Y _1-0.02-x Ce _0.02 Nd _x ) ₃ Al ₅ O ₁₂ (X = 0, 0.001, 0.01, 0.03, 0.1, 0.5) can be prepared. These compounds are used for the following evaluation. X represents the molar fraction of Nd.

[Crystal structure analysis]
The crystal structure analysis of each compound will be described. FIG. 5 shows the X-ray diffraction (XRD) patterns of these compounds. The XRD patterns of the compounds of X = 0, 0.001, 0.01, and 0.1 are almost the same in terms of the shape and strength ratio. This indicates that these compounds each have the same garnet-type crystal structure as Y ₃ Al ₂ (AlO ₄ ) ₃ .

[Light emission characteristic evaluation]
Next, the light emission characteristics of each compound will be described. The light emission characteristics are evaluated using a spectrophotometer. FIG. 6 shows each fluorescence spectrum of the compound (X = 0, 0.001, 0.01, 0.1). The excitation wavelength when measuring these emission spectra is 250 nm. Each emission spectrum is shown with the maximum intensity normalized to 1.

Comparing the emission spectra of X = 0.001, 0.01, and 0.1 in FIG. 6 with the emission spectrum of X = 0, the emission intensity in the vicinity of 580 nm is obtained by introducing Nd ³⁺ as a light absorbing ion. It can be seen that is decreasing. Further, it can be seen that as the value of X increases, that is, as the molar fraction of Nd ³⁺ increases, the emission intensity near 580 nm decreases. That is, it can be seen from FIG. 6 that Nd ³⁺ that is a light-absorbing ion partially absorbs the fluorescent component emitted by Ce ³⁺ that is the emission center and induces a depression in the emission spectrum. Furthermore, in the emission spectrum of X = 0.01, the intensity at a wavelength of 580 nm is about 70% of the maximum intensity. That is, it can be seen that the intensity of the yellow light component can be greatly suppressed.

[Spectral distribution evaluation by simulation]
Next, a simulation performed using each emission spectrum shown in FIG. 6 will be described. Here, in the semiconductor light emitting device 12, an emission spectrum that can be obtained by combining the emission spectra of the solid state light emitting element 6 and two types of phosphors will be considered. An InGaN blue LED having a peak wavelength of 450 nm is used as the solid state light emitting device 6, and each compound of X = 0, 0.001, 0.01, 0.1 is used as the phosphor 2, and further a red phosphor (including light absorption ions) Not used). The red phosphor uses a nitride phosphor CaAlSiN ₃ : Eu (CASN). The mixing ratio of each emission spectrum is appropriately adjusted so as to obtain white light having a correlated color temperature of 5000K. FIG. 7 shows an emission spectrum obtained by simulation and an average color rendering index Ra in the spectrum. In the emission spectrum of FIG. 7, the maximum value near 550 nm is normalized to 1. The color rendering index is an index for evaluating the color appearance defined in JIS (Japanese Industrial Standards). It is measured using black body radiation, which is natural light, as reference light, and is measured using 15 types of evaluation color charts. It is indicated by 15 indices (R1 to R15) corresponding to each color chart. The average color rendering index Ra indicates an average value of eight indexes R1 to R8. The maximum value is 100, and the closer to 100, the better. Generally, Ra of 80 or more is used as a measure of high color rendering properties. For reference, the Ra of a three-wavelength fluorescent lamp that is an existing light source is 80 or more.

In FIG. 7, Ra of X = 0.001 is 78, and no significant difference is seen compared to 77 which is Ra of X = 0. When the emission spectrum of X = 0.01 is compared with that of X = 0, a decrease in intensity can be confirmed near X = 0.01 in the vicinity of 580 nm. That is, it can be seen that the intensity of the yellow light component is suppressed. Ra is also sufficiently high as 84. This indicates that the emission spectrum of X = 0.01 can be used as illumination light close to natural light.

In the intensity of the emission spectrum near 580 nm, the intensity at X = 0.1 is further reduced compared to the intensity at X = 0.01. And Ra of X = 0.1 is an extremely high value of 90. An emission spectrum of X = 0.1 can be said to have high color rendering properties. As an existing light source with high color rendering properties, there is a three-wavelength fluorescent lamp. According to this embodiment, it is possible to obtain illumination light that is comparable to a three-wavelength fluorescent lamp.

In addition, in the emission spectrum of X = 0.5 or more, a further decrease in intensity near 580 nm and an improvement in Ra can be expected. When X is 0.5 or more, X is preferably 0.1 or less in consideration of an increase in the amount of expensive neodymium used compared to yttrium and a decrease in light emission efficiency.

As mentioned above, the present invention is not limited to these, and various modifications are possible within the scope of the gist of the present invention.

In some of the fluorescent components at the emission center, phosphors with partial depressions in the emission spectrum due to absorption of light-absorbing ions may emit light that makes an object look vivid even without using an optical filter member. it can.

DESCRIPTION OF SYMBOLS 1 Excitation source 2 Phosphor 3 Excitation light 4 Output light 5 Substrate 6 Solid light emitting element 7 Wiring conductor 8 Feed electrode 9 Wavelength conversion layer 10 Translucent resin 11 Side wall 12 Semiconductor light emitting device

Claims

The matrix contains a luminescent center and light absorbing ions,
The light absorbing ion is a phosphor capable of partially absorbing a fluorescent component emitted by the emission center.
The phosphor according to claim 1, which is an inorganic compound.
3. The phosphor according to claim 1, wherein the phosphor has a maximum intensity of the fluorescent component in a visible light region having a wavelength of 380 nm or more and 780 nm or less.
The phosphor according to any one of claims 1 to 3, wherein the matrix has a garnet-type crystal structure.
The phosphor according to any one of claims 1 to 4, wherein a half width of a fluorescence spectrum when the base includes only the emission center is 50 nm or more and less than 150 nm.
The phosphor according to claim 1, wherein the emission center is Ce 3+ .
The phosphor according to any one of claims 1 to 6, wherein a wavelength region in which the light-absorbing ions can be absorbed is in a wavelength region of 560 nm or more and less than 600 nm.
The phosphor according to any one of claims 1 to 7, wherein the phosphor has a depression in an emission spectrum in a wavelength region where the light absorption ions can be absorbed.
The phosphor according to claim 8, wherein the intensity of the emission spectrum at a wavelength of 580 nm is less than 70% with respect to the maximum intensity of the emission spectrum.
The phosphor according to any one of claims 1 to 9, wherein the light absorption ion is a trivalent rare earth element ion.
The phosphor according to claim 10, wherein the light absorption ion is Nd 3+ .
The phosphor according to any one of claims 1 to 11, wherein an addition amount of the light absorbing ions is 0.01 mol or more and 0.1 mol or less per mol of the phosphor.
The phosphor according to any one of claims 1 to 12,
A light emitting device comprising an excitation source for exciting the phosphor.
A solid state light emitting device as the excitation source;
A wavelength conversion layer containing the phosphor;
A substrate on which the solid state light emitting element is fixed,
The solid state light emitting device has a power supply terminal,
The substrate has a wiring conductor;
The feeding electrode and the wiring conductor are electrically connected,
The light emitting device according to claim 13, wherein the wavelength conversion layer is disposed in an optical path of light emitted from the solid state light emitting device.
A lighting circuit for lighting the solid-state light-emitting element;
The light-emitting device according to claim 14, further comprising a base member.
The light-emitting device according to claim 14, further comprising a control circuit that controls power supply to the solid-state light-emitting element.