JP2007321139A - Method for producing fluorophor, the resultant fluorophor, light-emitting device, light emitter, image display, and illuminator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suitable method for producing a fluorophor having high emission efficiency when emitting red fluorescence on absorbing ultraviolet to blue light in particular. <P>SOLUTION: The fluorophor is such that an activator element such as Eu is contained in a matrix compound containing a bivalent metal element such as Sr, a trivalent metal element such as Y and sulfur. The method for producing the fluorophor comprises heating a raw material compound containing the metal elements constituting the fluorophor in the presence of sulfur simple substance or a sulfur-containing compound and carbon simple substance or a carbon-containing compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a phosphor manufacturing method and the like, and more specifically, a wavelength conversion material (second light emitting material) for wavelength-converting at least part of light from an excitation light source (first light emitting material) such as a semiconductor light emitting element. The present invention relates to a method for producing a phosphor that can be suitably used.

  In recent years, a gallium nitride (GaN) blue light-emitting diode (LED), which is a semiconductor light-emitting element, is used as an excitation light source, and a white phosphor formed by combining a phosphor that emits light by converting the wavelength of light emitted from the excitation light source. A light-emitting element attracts attention as a light-emitting source of an image display device, a lighting device, or the like by taking advantage of the feature of low power consumption and long life.

Here, what is particularly often used as a phosphor for wavelength conversion is yttrium activated by cerium represented by the general formula (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce ^3+. It is an aluminum garnet yellow light emitting phosphor (see Patent Document 1, Patent Document 2, and Patent Document 3).

  Further, a white light-emitting element in which a red light-emitting component that is insufficient in an yttrium, aluminum, and garnet-based phosphor is supplemented with another red light-emitting phosphor by mixing two kinds of phosphors has been studied (see Patent Document 4).

Here, SrY ₂ S ₄ phosphor and the like exist as the red light emitting phosphor (see Non-Patent Document 1).

Japanese Patent No. 2900928 Japanese Patent No. 2927279 Japanese Patent No. 3364229 Japanese Patent Laid-Open No. 10-163535 Journal of Electrochemical Society (J. Electrochem. Soc.), 1992, 139 (8), 2347-2352

  However, a white light emitting element composed of a blue light emitting diode element and an yttrium / aluminum / garnet phosphor has a feature that light emission is pale due to a shortage of a red light emitting component, and has a problem of low color rendering.

  In addition, there is still a problem to be improved in terms of color rendering even in a white light emitting element in which a red light emitting component that is insufficient with an yttrium, aluminum, and garnet phosphor is supplemented with another red light emitting phosphor.

On the other hand, the conventional manufacturing method of the SrY ₂ S ₄ phosphor is a method of heating in a toxic hydrogen sulfide gas stream, so that the manufacturing equipment becomes large and the manufacturing cost increases. In addition, the production method has the disadvantage that the luminous efficiency is still low and is not suitable for practical use.

  The present invention has been made in view of the above-mentioned various problems of the prior art, and the object of the present invention is to achieve high luminous efficiency, particularly red to fluorescent light by absorbing ultraviolet to blue light. Therefore, it is an object of the present invention to provide a suitable method for producing a phosphor having high luminous efficiency.

  Another object of the present invention is to provide a phosphor manufactured by the manufacturing method.

  Another object of the present invention is to provide a highly efficient light-emitting element using a phosphor having high emission efficiency manufactured using the manufacturing method.

  Another object of the present invention is to provide a white light-emitting element having a high efficiency and a high color rendering property by using a phosphor having a high light emission efficiency manufactured using the manufacturing method.

  Another object of the present invention is to provide an image display apparatus having high efficiency and high color rendering using the light emitting element or the white light emitting element.

  Another object of the present invention is to provide a lighting device having high efficiency and high color rendering using the light emitting element or the white light emitting element.

  As a result of intensive studies, the present inventors have made a compound containing a divalent metal element, a trivalent metal element and sulfur as a red light-emitting component as a base compound, and in the manufacture of a phosphor containing an activator element in the base compound. The present inventors have found a suitable production method and have completed the present invention. That is, the gist of the present invention is as follows.

  That is, according to the present invention, in the production of a phosphor containing a divalent metal element, a trivalent metal element and sulfur as a base compound, and the host compound containing an activator element, sulfur alone or a sulfur-containing compound And a raw material compound containing a metal element constituting the phosphor in the coexistence of simple carbon or a carbon-containing compound.

Moreover, it is preferable that a base compound is represented by the following general formula (I).
MLn ₂ S ₄ (I)
(In formula (I), M represents one or more divalent metal elements, and Ln represents one or more trivalent metal elements.)

  The divalent metal element is preferably one or more metal elements selected from the group consisting of alkaline earth metals and zinc.

  The trivalent metal element is preferably one or more metal elements selected from the group consisting of rare earth elements, Al, Ga and In.

  The activator element is preferably one or more metal elements selected from the group consisting of Ce, Pr, Sm, Eu, Tb, Tm, Mn, Fe, and Cr.

  It is also desirable to include a step of rapidly cooling after the heating step.

  On the other hand, according to this invention, the fluorescent substance manufactured by said manufacturing method is provided.

  Moreover, according to this invention, the light emitting element using the fluorescent substance manufactured by said manufacturing method is provided.

  According to the invention, in the light-emitting element including the first light-emitting material and the second light-emitting material that absorbs light emitted from the first light-emitting material and performs wavelength conversion, the second light-emitting element that performs wavelength conversion. There is provided a light emitting element using a phosphor manufactured by the above manufacturing method as a light emitting material.

  Moreover, according to this invention, the light-emitting device using said light emitting element is provided.

  According to the present invention, there is also provided an image display device using the above light emitting element.

  Moreover, according to this invention, the illuminating device using said light emitting element is provided.

  According to the present invention, a phosphor having highly efficient light emission can be obtained.

  Hereinafter, the best mode for carrying out the present invention (embodiment) will be described in detail. However, the present invention is not limited to the following embodiment, and various modifications may be made within the scope of the gist of the present invention. Can be implemented.

[Phosphor production method]
The phosphor manufacturing method to which the present embodiment is applied is a composite metal sulfide phosphor manufacturing method in which a raw material compound containing a metal element constituting a phosphor, carbon or a carbon compound, and sulfur or a sulfur compound coexist. It heats in the made state, It is characterized by the above-mentioned. By doing in this way, carbon or a carbon compound and sulfur or a sulfur compound react, carbon disulfide produces | generates, and a high quality composite sulfide can be manufactured by the effect | action. In other words, due to the reduction and sulfidation action of carbon disulfide, sulfidation of the raw metal compound and the mutual reaction of the sulfided metal compound occur, or when the raw material compound is sulfide, oxidation of the raw material sulfide is prevented and By promoting the solid-phase reaction, a high-quality composite sulfide phosphor can be produced. In addition, since it is not necessary to supply a toxic gas such as hydrogen sulfide, the manufacturing apparatus is not large-scale and effective in reducing the cost of the phosphor.

  There are no limitations on the raw material compound of the phosphor, but the required metal element sulfides, sulfates, oxides, carbonates, chlorides, nitrates, oxalates, and the like can be used. One raw material compound may be used alone, or two or more raw material compounds may be mixed and used. Among these, the use of sulfide is preferable in that a single phase of the composite sulfide phosphor is easily obtained. On the other hand, the use of carbonates of alkaline earth metal elements, rare earth metal elements, and oxides of Al, Ga, In, and Zn is preferable because they are high purity and stable raw materials.

The raw materials can be mixed by heating and firing a mixture (hereinafter referred to as “raw material mixture”) mixed by the following mixing method (A) or (B).
(A) Dry pulverizer such as hammer mill, roll mill, ball mill, jet mill, etc., or pulverization using mortar and pestle, etc. and mixing using ribbon blender, V-type blender, Henschel mixer, etc., or mixing using mortar and pestle And dry mixing method.
(B) A wet mixing method in which water or the like is added and mixed in a slurry state or a solution state by a pulverizer, a mortar and pestle, or an evaporating dish and a stirring bar, and then dried by spray drying, heat drying, natural drying or the like.

The raw material mixture can be mixed with a firing aid (also referred to as “flux”) as necessary, and the addition of the firing aid is expected to promote particle growth and lower the reaction temperature. This is effective for synthesizing preferred phosphors. The sintering aids, for example, _NH 4 Cl or _NH 4 ammonium halides such as F · _HF; NaCO 3, alkali metal carbonates such as LiCO _3; LiCl, NaCl, alkali halides KCl _like; CaCl 2, CaF ₂ , halides of alkaline earth metals such as BaF ₂ ; borate compounds such as B ₂ O ₃ , H ₃ BO ₃ and NaB ₄ O ₇ ; phosphoric acids such as Li ₃ PO ₄ and NH ₄ H ₂ PO ₄ 1 type, or 2 or more types, such as a salt compound, can be used.

  As carbon or a carbon compound, carbon alone is preferable, and activated carbon having a large specific surface area is preferable, but other carbons such as graphite powder can also be used. In addition, carbon compounds, such as aliphatic hydrocarbons and aromatic hydrocarbons, can be used instead of simple carbon, and those in a solid state at normal pressure are preferable for handling. Further, as the carbon compound, not only a low molecular compound but also a high molecular compound can be used. For example, a resin containing no oxygen or low oxygen content such as polyethylene, polypropylene, and nylon is preferable. .

  As the sulfur or sulfur compound, sulfur alone is preferable. Moreover, as a sulfur compound, the sulfur compound which does not contain oxygen can be used, for example, thiourea, thioacetamide, etc. can be used as a sulfur source.

  As a combination of a simple sulfur or a sulfur-containing compound and a simple carbon or a carbon-containing compound, a combination of a simple sulfur and activated carbon is particularly preferable. By using this combination, sulfur having a low melting point is melted and adsorbed on the activated carbon during the temperature raising process, and further heated to react with each other to generate carbon disulfide. In this case, the weight ratio of sulfur and activated carbon is arbitrary, but if any of them is too small, the amount of carbon disulfide produced is not preferable. The lower limit of the weight of sulfur with respect to the sum of the weight of sulfur and the weight of activated carbon is preferably 20% or more, more preferably 30% or more, and particularly preferably 40% or more. Further, the upper limit is preferably 80% or less, more preferably 70% or less, and particularly preferably 60% or less.

  Sulfur or a sulfur compound and carbon or a carbon compound are preferably mixed in advance. Further, during heating, it is preferable to dispose near the phosphor raw material mixture. As a method of arranging them close to each other, two crucibles of different sizes are nested, a raw material mixture is put in an inner crucible, sulfur or a sulfur compound and a carbon or a mixture of carbon compounds (hereinafter referred to as “sulfur source carbon” The method (hereinafter abbreviated as “double crucible method”) is most preferred. As another arrangement method, when heating in a tube electric furnace, a sulfur source carbon source mixture is arranged upstream of the tube, and a raw material mixture is arranged downstream (hereinafter referred to as “series arrangement method”). Thus, carbon disulfide can be efficiently supplied around the raw material mixture.

  The heating atmosphere is preferably an inert atmosphere or a reducing atmosphere. More preferred is an inert atmosphere such as argon or nitrogen, or a reducing atmosphere such as argon containing 1% to 10% of hydrogen or nitrogen containing 1% to 10% of hydrogen. Further, hydrogen sulfide, methane, ammonia, and the like can contain a gas component that does not contain oxygen and contains H, S, C, or N as a constituent component. The application of the above-described double crucible method is preferable because it can be manufactured in an oxidizing atmosphere, for example, an air atmosphere, and is simple.

The heat treatment is performed in a heat-resistant container such as a crucible or a tray using a material having low reactivity with the raw material mixture. A heat-resistant container made of quartz, alumina, graphite, boron nitride or the like can be used, and among them, a heat-resistant container made of alumina or quartz is preferable because it has low reactivity with the raw material mixture and is easily available.
Further, a heat-resistant container made of graphite is preferable because it also functions as carbon or a carbon compound, which is the main point of the present embodiment.

  Although the heating temperature depends on the type of the target phosphor, it cannot be generally stated, but it is preferable to heat in the range of 800 ° C. to 1800 ° C., and the lower limit is more preferably 900 ° C. or more, and particularly preferably 1000 ° C. or more. . The upper limit is more preferably 1500 ° C. or less, and particularly preferably 1300 ° C. or less.

  The heating temperature is affected by the type, mixing state, particle size, form, etc. of the raw material compound, but if the temperature is too high, the reaction between the raw material container and the raw material mixture, the volatilization of the raw material components, etc. Luminous intensity decreases. If the temperature is too low, the reaction between the raw materials is insufficient and the target crystal phase is not formed, or even if the target crystal phase is obtained, the crystallinity is low and the emission intensity decreases.

  The heat treatment may be performed a plurality of times, in which case the firing conditions may be changed each time. Particularly when a raw material compound having low reactivity is used, firing multiple times is effective. In heating, the temperature can be maintained for a certain time at a certain temperature below the maximum heating temperature. Thereby, decomposition | disassembly and reaction of a raw material compound can be performed appropriately.

  The holding time at the above-mentioned heating temperature is usually 10 minutes to 24 hours, and the lower limit is preferably 1 hour or longer, and more preferably 2 hours or longer. Moreover, as an upper limit, 12 hours or less are preferable, 6 hours or less are still more preferable, and 4 hours or less are especially preferable. If the holding time is too short, it is not preferable because necessary reactions and crystal growth are not completed, and it is not preferable that the holding time is longer than necessary because it is a waste of energy.

  When the temperature required for phosphor production is high, the serial arrangement method is preferable to the above-described double crucible method because the atmosphere can be controlled by adjusting the temperature of the sulfur source nitrogen source mixture separately from the temperature of the raw material mixture. .

  After the heat treatment, cooling to room temperature is performed. The atmosphere during cooling is preferably an inert atmosphere or a reducing atmosphere as in the case of the heat treatment. More preferred is an inert atmosphere such as argon or nitrogen, or a reducing atmosphere such as argon containing 1% to 10% of hydrogen or nitrogen containing 1% to 10% of hydrogen. Further, hydrogen sulfide, methane, ammonia, and the like can contain a gas component that does not contain oxygen and contains H, S, C, or N as a constituent component.

Moreover, it is preferable to cool rapidly. Thereby, in the cooling process after the heat treatment, oxidation by a small amount of oxygen contained in the atmospheric gas can be prevented, and a phosphor with high crystallinity and few impurity phases can be obtained.
Here, rapid cooling means cooling at a rate of 1000 ° C./h or higher until the temperature falls below 300 ° C., and for example, a method of leaving it at room temperature can be considered.

  After cooling, pulverization, washing, classification, etc. are performed as necessary. For the pulverization treatment, pulverizers listed as being usable for pulverization and mixing of raw materials can be used. Various classifiers such as various air classifiers and vibrating sieves can be used for the classification treatment.

  For the washing treatment, any of those applicable as a normal phosphor treatment process such as water, acid (hydrochloric acid, nitric acid, sulfuric acid, acetic acid, etc.), alkali (ammonia water, sodium hydroxide aqueous solution, etc.) can be used.

  Phosphors that can be produced by this method are generally those in which composite sulfides are used as a base compound. In particular, at least one of an alkaline earth metal element or zinc and at least one of a rare earth metal element, Al, Ga, and In is used. A phosphor with high characteristics can be obtained by this method in the matrix. Here, the alkaline earth metal element preferably indicates Mg, Ca, Sr or Ba, and among them, a phosphor containing Ca, Sr and Ba is suitable for this method. The rare earth metal element refers to Sc, Y, lanthanoids (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), and among them, Sc, Y Phosphors containing La, Gd or Lu are suitable for this method.

  There is no particular limitation on the activator element (also referred to as “activator” or “luminescent ion”) to be added that is responsible for light emission of the phosphor, but Ce, Pr, Sm, Eu, Tb, Tm, Mn, Fe And Cr are preferred, Ce, Eu, Mn and Tb are more preferred, Eu and Ce are particularly preferred, and Eu is most preferred. Furthermore, an activator element different from this can be added. Such another activator element is effective in adjusting the light emission color tone by increasing the light emission intensity of the phosphor or showing light emission derived from the additive.

A phosphor having a host compound represented by the following general formula (I) is one of the preferred phosphors produced by the production method of the present embodiment.
MLn ₂ S ₄ (I)
Here, M represents one or more divalent metal elements, and Ln represents one or more trivalent metal elements.
M is preferably one or more metal elements selected from the group consisting of alkaline earth metals and zinc. Among them, one or two kinds selected from the group consisting of Mg, Ca, Sr and Ba are preferable. The above is preferable, and one or both of Ca and Sr are preferable, and Sr is preferable.
Ln is preferably one or more metal elements selected from the group consisting of rare earth elements, Al, Ga and In, and among them, from Sc, Y, La, Gd, Lu, Al, Ga and In More preferably, the metal element is one or more metal elements selected from the group consisting of Y, Ln and Gd, and particularly preferably one or more metal elements selected from the group consisting of Y, Ln and Gd. Most preferably it is.

An alkaline earth thioitrate phosphor containing Y is a phosphor more suitable for this method, and a phosphor based on SrY ₂ S ₄ is a phosphor particularly suitable for this method. A preferred activator added to the phosphor is any one of Eu, Ce and Mn. When Eu is used as an activator, a highly efficient red light-emitting phosphor that can be excited by long-wave ultraviolet light. This is preferable.

The emission peak wavelength of the obtained phosphor is in the range of 400 nm to 800 nm, and the phosphor having the emission peak wavelength in the range of 500 nm to 700 nm is more preferably used for a light emitting device using a semiconductor light emitting device as an excitation light source, A phosphor having an emission peak wavelength of 500 nm to 580 nm is preferred as a green or yellow emission phosphor, and a phosphor having an emission peak wavelength of 580 nm to 700 nm is preferred as an orange emission or red emission phosphor. Incidentally, since the emission peak wavelength of the SrY ₂ S ₄ phosphor to which Eu is added is 600 nm to 650 nm, it is preferable as the red light emitting phosphor.

Furthermore, the valence of the activator element in the phosphor can be controlled to a required valence by appropriately managing the production conditions such as the type of raw material and heating conditions. For example, when Eu ²⁺ is used as an activator element, the ratio of Eu ^{2+ in} the total Eu is preferably 60% or more, more preferably 80% or more, and even more preferably 90% or more. . If the ratio of Eu ²⁺ in the total Eu in the phosphor is too low, the emission intensity cannot be increased.

The ratio of Eu ²⁺ in the phosphor can be examined, for example, by measuring an X-ray absorption fine structure (XAFS). That is, when the L3 absorption edge of Eu atom is measured, Eu ²⁺ and Eu ³⁺ show separate absorption peaks, and the ratio can be determined from the area. The ratio of Eu ²⁺ can also be determined by measuring electron spin resonance (ESR).

Similarly, when Mn ²⁺ is used as the activator element, the ratio of Mn ²⁺ in the total Mn is preferably 60% or more, more preferably 80% or more, and more preferably 90% or more. Further preferred. In the case of Ce ³⁺ , Tb ³⁺ , and Pr ³⁺ , all can take a trivalent and tetravalent state, but it is preferable that the ratio of the trivalent state is 60% or more in the total amount of ions. 80% or more, more preferably 90% or more.

  The weight median diameter of the phosphor is usually 1 μm or more, preferably 2 μm or more, more preferably 10 μm or more, and particularly preferably 15 μm or more. The weight median diameter of the phosphor is usually 50 μm or less, preferably 30 μm or less, and more preferably 25 μm or less. Within this preferable range, a thickness of about 2 μm to 10 μm is preferable in terms of handling such as dispersibility in the resin. On the other hand, in terms of light emission intensity, the weight median diameter is preferably about 10 to 30 μm.

  When the weight median diameter is excessively large, problems such as sedimentation and coating film non-uniformity increase when used in a light emitting device. On the other hand, when the weight median diameter is excessively small, luminance is lowered and handling is difficult. According to the dry classification using a nylon mesh, a phosphor with good dispersibility having a weight median diameter of 15 μm to 25 μm can be obtained. Such particle size control can be performed by the above-described pulverization treatment, but is preferably performed by various classification treatments. For example, a method such as sieving with water tank or nylon mesh is preferable.

  In addition, when manufacturing a light emitting element by the below-mentioned method using the obtained fluorescent substance, it is preferable to disperse | distribute in resin after performing well-known surface treatment, for example, calcium phosphate treatment.

  Thus, the phosphor manufactured by the manufacturing method to which the present embodiment is applied emits light also by vacuum ultraviolet rays, ultraviolet rays, visible rays, electron beams, X-rays, electric fields, etc. In addition to the light-emitting element of the present embodiment in which a semiconductor light-emitting element such as the above is used as an excitation light source, it can be effectively used as a phosphor using such excitation means.

[Light emitting element]
A light-emitting element to which this embodiment is applied includes a light-emitting element having an excitation light source (first light-emitting material) and a phosphor that converts at least part of light from the excitation light source as a second light-emitting material. In which a phosphor manufactured by the manufacturing method of the present embodiment is used as a phosphor as a wavelength conversion material, and in combination with an excitation light source as described below, white or a light emitting element of any color tone Can be configured.

  In the light emitting element to which the present embodiment is applied, the excitation light source for irradiating the phosphor with light preferably generates light having a wavelength of 360 nm to 490 nm. Specific examples of the excitation light source include a light emitting diode (LED) or a laser diode (LD), an organic electroluminescence light emitting device (OLED), a dispersion type or thin film type inorganic electroluminescence light emitting device (inorganic EL), and the like. .

  Among them, GaN-based light emitting diodes and laser diodes using GaN-based compound semiconductors are preferable. This is because GaN-based light-emitting diodes and laser diodes have significantly higher light emission output and external quantum efficiency than SiC-based light-emitting diodes that emit light in this region, and can be combined with the phosphor to achieve very low power. This is because very bright light emission can be obtained. For example, for a current load of 20 mA, the GaN system usually has a light emission intensity 100 times or more that of the SiC system.

Of the GaN-based light-emitting diodes and laser diodes, those having an Al _X Ga _Y N light-emitting layer, a GaN light-emitting layer, or an In _X Ga _Y N light-emitting layer are preferable. Among the GaN-based light emitting diodes, those having an In _X Ga _Y N light-emitting layer are particularly preferable because the emission intensity is very strong. In a GaN-based laser diode, an In _X Ga _Y N layer and a GaN layer are particularly preferable. A multi-quantum well structure is particularly preferable because the emission intensity is very strong. In the above, the value of X + Y is usually in the range of 0.8 to 1.2.

In the GaN-based light emitting diode, those in which these light emitting layers are doped with Zn or Si or those without a dopant are preferable for adjusting the light emission characteristics. A GaN-based light emitting diode has these light emitting layer, p layer, n layer, electrode, and substrate as basic constituent elements, and the light emitting layer is made of an n-type and p-type Al _X Ga _Y N layer, a GaN layer, or In Those having a heterostructure sandwiched between _X Ga _YN layers and the like are preferable because of high light emission efficiency, and those having a heterostructure of a quantum well structure are more preferable because of higher light emission efficiency.

  In addition, the light emitting element to which this embodiment is applied may contain other phosphors as the wavelength conversion material in addition to the phosphor manufactured by the manufacturing method of this embodiment. As the other phosphors, phosphors that emit blue, blue-green, green, yellow-green, yellow, or deep red light are preferable, and in particular, the phosphor of the present embodiment and green, yellow-green, or yellow A combination of a phosphor exhibiting light emission and a blue light emitting diode as an excitation light source is preferable because a white light emitting element with high color rendering can be formed.

  Furthermore, a preferred white light-emitting element can also be configured by combining a phosphor to which this embodiment is applied, a near-ultraviolet light emitting diode, a blue light emitting phosphor, and a green light emitting phosphor. These white light emitting elements are preferable because a color rendering property can be further improved by adding a phosphor that emits light from red to deep red.

Hereinafter, examples of preferred phosphors to be combined with the phosphor of the present embodiment are listed below.
Green light emitting phosphors include M ₂ SiO ₄ : Eu ²⁺ , MAl ₂ O ₄ : Eu ²⁺ , MSi ₂ N ₂ O ₂ : Eu ²⁺ , MGa ₂ S ₄ : Eu ²⁺ , MMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ (M represents at least one selected from Ca, Sr, and Ba), Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce, Ca ₃ (Sc _1-x , Mg _x ) ₂ Si ₃ O ₁₂ : Ce or the like can be used.

As red light emitting phosphors, sulfide phosphors such as CaS: Eu ²⁺ , SrS: Eu ²⁺ , M ₂ Si ₅ N ₈ : Eu ²⁺ , MAlSiN ₃ : Eu ²⁺ (M is selected from Ca, Sr, Ba) Nitride-based phosphor such as at least one or two or more) and M ″ (Si, Al) ₁₂ (O, N) ₁₆ : Eu ²⁺ (M ″ represents Li, Mg, Ca) An oxynitride phosphor such as at least one selected from Sr, Y, La, Gd, and Ly is preferred.

In addition, when trivalent Eu is used as a luminescent center ion, oxysulfide phosphors such as La ₂ O ₂ S: Eu ³⁺ and Y ₂ O ₂ S: Eu ³⁺ , and trivalent Eu with acetylacetone or Preference is given to coordination compound phosphors coordinated with tenoyltrifluoroacetone and the like.

Moreover, 3.5MgO · 0.5MgF ₂ · GeO ₂ : Mn ⁴⁺ or the like is preferable when tetravalent Mn is used as the emission center ion. Among these, 3.5MgO · 0.5MgF ₂ · GeO ₂ : Mn ⁴⁺ , La ₂ O ₂ S: Eu ³⁺ , CaAlSiN ₃ : Eu ^{2+ and the} like are preferable because light emission in the deep red region can be added.

As the blue light emitting phosphors, MMgAl ₁₀ O ₁₇ : Eu ²⁺ , M ₃ MgSi ₂ O ₈ : Eu ²⁺ , M ₂ MgSi ₂ O ₇ : Eu ²⁺ , MMgSi ₂ O ₆ : Eu ²⁺ (M is Ca, M ′ ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ (in the above, M ′ represents at least one selected from Mg, Ca, Sr, Ba) and the like. Can be used. Of these, MGgAl ₁₀ O ₁₇ : Eu ²⁺ containing Ba as the main component of M and M ′ ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ containing Sr as the main component of M ′ are preferable.

  In addition, the phosphor used in the light-emitting element to which the present embodiment is applied may contain an impurity element and an impurity phase that are involved in manufacturing the phosphor to such an extent that the performance is not impaired.

[Light emitting device, image display device, lighting device]
The phosphor as the wavelength conversion material, a semiconductor light emitting element such as a light emitting diode or a laser diode, and a light emitting element of the present embodiment having light emitted from an OLED, an inorganic EL or the like as an excitation light source emits light from the semiconductor light emitting element. It can be a light emitting device with high color rendering properties that absorbs light in the ultraviolet to visible light range and emits visible light of a longer wavelength, and is an image display device such as a color liquid crystal display using a backlight unit or a surface emitting device. It is suitable as a light source for lighting devices such as the above.

  Hereinafter, a light-emitting element, a light-emitting device, an image display device, and an illumination device according to this embodiment including such an excitation light source and a phosphor will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a light emitting device having an excitation light source (a semiconductor light emitting device that generates light having a short wavelength of 360 to 490 nm) and a phosphor.
FIG. 2 is a schematic cross-sectional view showing an embodiment of a surface emitting illumination device incorporating the light emitting element shown in FIG.
1 and 2, 1 is a light emitting element, 2 is a mount lead, 3 is an inner lead, 4 is an excitation light source, 5 is a phosphor-containing resin part, 6 is a conductive wire, 7 is a molding member, and 8 is a surface emitting light. An illuminating device, 9 is a diffusion plate, and 10 is a holding case.

  As shown in FIG. 1, the light emitting element 1 has a general bullet shape, and an excitation light source (360 nm to 490 nm excitation light source) 4 made of a GaN-based light emitting diode or the like is disposed in the upper cup of the mount lead 2. However, the phosphor is mixed and dispersed in a binder such as a silicone resin, an epoxy resin or an acrylic resin, and poured into the cup to be fixed by being covered with the phosphor-containing resin portion 5 formed. Yes. On the other hand, the excitation light source 4 and the mount lead 2, and the excitation light source 4 and the inner lead 3 are respectively connected by a conductive wire 6, and these are entirely covered and protected by a mold member 7 made of epoxy resin or the like.

  As shown in FIG. 2, the surface emitting illumination device 8 incorporating the light emitting element 1 has a large number of light emitting elements on the bottom surface of a rectangular holding case 10 whose inner surface is light-opaque such as a white smooth surface. 1 is arranged with a power supply and a circuit (not shown) for driving the light emitting element 1 outside thereof, and a milky white acrylic plate or the like is diffused at a position corresponding to the lid portion of the holding case 10 The plate 9 is fixed for uniform light emission.

  Then, the surface-emitting illumination device 8 is driven to apply a voltage to the excitation light source 4 of the light-emitting element 1 to emit short-wave light having a wavelength of 360 nm to 490 nm. The phosphor in Fig. 5 absorbs and emits visible light having a longer wavelength (wavelength of 380 nm to 780 nm). On the other hand, light emission with high color rendering properties is obtained by mixing with blue light or the like that is not absorbed by the phosphor. This light passes through the diffusion plate 9 and is emitted upward in the drawing, so that illumination light with uniform brightness can be obtained within the surface of the diffusion plate 9 of the holding case 10.

  In addition, the fluorescent substance containing resin part 5 in the said light emitting element 1 has the following effects. That is, the light from the excitation light source 4 and the light from the phosphor are usually directed in all directions, but when the phosphor powder is dispersed in the resin, a part of the light is reflected when it goes out of the resin. Therefore, since the direction of the light can be changed to some extent, the light is mixed and the light distribution tends to be made uniform. Therefore, since the light can be guided to an efficient direction to some extent, it is preferable to use the phosphor powder dispersed in a resin. Further, when the phosphor is dispersed in the resin, the total irradiation area of the light from the excitation light source 4 to the phosphor is increased, so that there is an advantage that the emission intensity from the phosphor can be increased.

As a resin that can be used for the phosphor-containing resin part, various kinds such as silicone resin, epoxy resin, polyvinyl resin, polyethylene resin, polypropylene resin, polyester resin, etc. are used alone or in combination of two or more. Can be used.
In view of good dispersibility of the phosphor powder, silicone resins and epoxy resins are preferable. When the phosphor powder is dispersed in the resin, the weight ratio of the phosphor powder to the total weight of the phosphor powder and the resin is usually 0.1% by weight to 20% by weight, preferably 0.3% by weight. -15% by weight, more preferably 0.5% by weight to 10% by weight. If the amount of the phosphor is excessively larger than this range, the luminous efficiency may be reduced due to aggregation of the phosphor powder. If the amount is too small, the luminous efficiency may be decreased due to light absorption or scattering by the resin. is there.

  In this resin, an extender or a diffusing agent may be added in order to prevent color spots (unevenness). As a specific diffusing agent, barium titanate, titanium oxide, aluminum oxide, silicon oxide or the like is preferably used. By using such a diffusing agent, a light emitting element having good directivity can be obtained. For example, a diffusing agent having a particle size of 1 nm to 1 μm has a low interference effect on the light wavelength from the semiconductor light emitting device, but can increase the resin viscosity without reducing the luminous intensity. This makes it possible to disperse the phosphor in the resin almost uniformly in the syringe and maintain the state when arranging the phosphor-containing resin by potting or the like, and the particle size is relatively difficult to handle. Even when a large phosphor is used, a highly uniform phosphor-containing resin portion can be formed with a high yield. The action of the diffusing agent varies depending on the particle size range, and can be selected or combined according to the method of use.

  As described above, the phosphor is preferably dispersed in the resin after performing a known surface treatment if necessary.

  In the present embodiment, it is particularly preferable to use a surface-emitting type illuminant, particularly a surface-emitting GaN-based laser diode, as an excitation light source, since it increases the luminous efficiency of the entire light-emitting element. A surface-emitting type illuminant is an illuminant that emits strong light in the surface direction of a film. In a surface-emitting GaN-based laser diode, the crystal growth of a light-emitting layer or the like is controlled, and a reflective layer or the like is successfully performed. By devising, the light emission in the surface direction can be made stronger than the edge direction of the light emitting layer. Compared to the type that emits light from the edge of the light emitting layer by using a surface emitting type, as a result of taking a large emission cross-sectional area per unit light emission amount, when irradiating the phosphor as a wavelength conversion material, Since the irradiation area can be made very large with the same amount of light and the irradiation efficiency can be improved, stronger light emission can be obtained from the phosphor as the wavelength conversion material.

  Thus, when using a surface emitting type as an excitation light source, it is preferable to form the phosphor as the wavelength conversion material in a film shape. Since the cross-sectional area of the light from the surface-emitting type excitation light source is sufficiently large, if the phosphor is formed in a film shape in the direction of the cross-section, the irradiation cross-sectional area per unit amount of the phosphor from the excitation light source increases. The intensity of light emitted from the body can be further increased.

  In addition, when a surface emitting type light source is used as the excitation light source and a phosphor is formed in a film shape, it is preferable to have a shape in which the film-shaped phosphor is directly in contact with the light emission surface of the excitation light source. . Contact here means creating a state in which the excitation light source and the phosphor are in close contact with each other without air or gas. As a result, it is possible to avoid a light amount loss in which light from the excitation light source is reflected by the phosphor film surface and oozes out, so that the luminous efficiency of the entire device can be improved.

  FIG. 3 is a schematic perspective view showing an example of a light emitting device to which a surface emitting type light source is used as an excitation light source and a phosphor is formed in a film shape. In FIG. 3, 11 is a phosphor-containing film having the phosphor, 12 is a surface-emitting GaN laser diode as an excitation light source, and 13 is a substrate. In order to create a state where they are in contact with each other, the surface-emitting GaN-based laser diode 12 and the phosphor-containing film 11 as excitation light sources are separately formed, and the surfaces are brought into contact with each other by an adhesive or other means. Alternatively, the phosphor-containing film 11 may be formed (molded) on the light emitting surface of the surface emitting GaN-based laser diode 12. As a result, the surface emitting GaN-based laser diode 12 and the phosphor-containing film 11 can be brought into contact with each other.

  The light-emitting device of this embodiment includes an excitation light source and a phosphor manufactured by the manufacturing method of the above-described embodiment as a wavelength conversion material, and the phosphor has a wavelength of 360 nm to 490 nm emitted from the excitation light source. It is a light-emitting device that absorbs short-wavelength light, has good color rendering properties regardless of the use environment, and can generate high-intensity visible light.

  Such a light emitting device of this embodiment is suitable for a light source such as a backlight light source, a light source such as a traffic light, an image display device such as a color liquid crystal display, and a lighting device such as a surface emitting device. Examples of the image display device include a fluorescent display tube (VFD), a field emission display (FED), a plasma display panel (PDP), a cathode ray tube (CRT), and the like. Further, the light-emitting device of this embodiment can also be used for a backlight for an image display device.

  FIG. 4 is a diagram illustrating an example of a light-emitting device (surface-mounted light-emitting device) suitable for use as a backlight light source. In FIG. 4, 21 is a light emitting diode (LED) which is an excitation light source, 22 is a phosphor-containing resin part containing a phosphor manufactured by the manufacturing method of the present invention, 23 is a frame, 24 is a conductive wire, 25 And 26 represent terminals.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

<Manufacture and evaluation of phosphors>
Table 1 shows the molar ratio of SrS, Y ₂ S ₃ , EuS constituting the phosphor, the weight of activated carbon and sulfur, the shape of activated carbon, the heat treatment temperature, and the cooling method in the production of the phosphor mentioned in the following examples. It is a table | surface which shows.
Example 1
As raw material compounds, strontium sulfide (SrS) 0.5985 g (0.005 mol), yttrium sulfide (Y ₂ S ₃ ) 1.3705 g (0.005 mol) and europium sulfide (EuS) 0.0368 g (0.0002 mol) (above, High purity chemical laboratory (99.99%) was mixed well in a mortar. The obtained raw material mixture was put in an alumina crucible (B1 size, internal volume 30 ml) and covered.

On the other hand, as a sulfur source carbon source mixture, 40 g of activated carbon (manufactured by Nippon Envirochemicals) and 10 g of sulfur (manufactured by Kojundo Chemical Laboratory Co., Ltd.) were mixed well. A B1 size crucible containing a raw material mixture was placed in an alumina crucible (B4 size, internal volume 150 ml), and the above-mentioned sulfur source carbon source mixture was placed in the remaining space and capped. This was heated at 1200 ° C. for 3 hours in an electric furnace (manufactured by ADVANTEC, model KS-1501) in an air atmosphere to obtain a SrY ₂ S ₄ : Eu phosphor. After completion of heating at 1200 ° C., the mixture was cooled to 25 ° C., which was room temperature, over about 3 hours. FIG. 5A shows the result of measuring the powder X-ray diffraction pattern of the obtained phosphor with a powder X-ray diffraction apparatus RAD-IIA manufactured by Rigaku Corporation.

  A photoluminescence (PL) spectrum of the obtained phosphor is shown in FIG. The PL spectrum is an emission spectrum under irradiation of light of 325 nm extracted by spectrally separating a xenon lamp, and an emission spectrum was obtained by detecting with a photomultiplier tube while scanning the spectroscope. As can be seen from FIG. 6A, this phosphor emitted red light with good color purity.

(Examples 2 and 3)
The SrY ₂ S ₄ : Eu phosphor of Example 2 was obtained in the same manner as in Example 1 except that the amounts of activated carbon and sulfur were changed to those shown in Table 1. The powder X-ray diffraction pattern of the obtained phosphor is shown in FIG. The PL spectrum of the obtained phosphor is shown in FIG.
Similarly, the same treatment as in Example 1 was carried out except that the amounts of activated carbon and sulfur used were those shown in Table 1, and the SrY ₂ S ₄ : Eu phosphor of Example 3 was obtained. The powder X-ray diffraction pattern of the obtained phosphor is shown in FIG. The PL spectrum of the obtained phosphor is shown in FIG.
FIG. 5B shows that a substantially single-phase phosphor crystal is obtained. As can be seen from FIGS. 6B and 6C, this phosphor has a red color with good color purity. Luminescence was shown.

(Examples 4 to 7)
Other than changing the amount of activated carbon and sulfur as shown in Table 1, pulverizing activated carbon and using it after holding at 1200 ° C. for 3 hours, then removing the crucible outside the furnace (rapid cooling treatment) Were processed in the same manner as in Example 1 to obtain SrY ₂ S ₄ : Eu phosphors in Examples 4 to 7. By taking the crucible out of the furnace, the time required for cooling from 1200 ° C. to room temperature was about 1 hour.

The powder X-ray patterns of the obtained phosphor are shown in FIGS. 7, 8, and 9 (a) to 9 (b). 7 corresponds to the fourth embodiment, FIG. 8 corresponds to the fifth embodiment, FIG. 9A corresponds to the sixth embodiment, and FIG. 9B corresponds to the seventh embodiment. As can be seen from the powder X-ray diffraction patterns of FIGS. 7, 8, and 9A, a substantially single-phase phosphor crystal was obtained.
Also it can be seen that SrY ₂ S ₄ is a parent compound by quenching tends to easily become a single phase.

Moreover, PL spectrum of the obtained fluorescent substance is shown to Fig.10 (a)-(c), Fig.11 (a)-(b), Fig.12 (a)-(b).
Here, FIGS. 10 (a) to 10 (c) and FIGS. 11 (a) to 11 (b) are emission spectra under irradiation of 325 nm light extracted by spectrally separating the xenon lamp, and FIG. 10B corresponds to the fifth embodiment, FIG. 10C and FIG. 11A correspond to the sixth embodiment, and FIG. 11B corresponds to the seventh embodiment.

FIGS. 12A to 12B are emission spectra under irradiation of 365 nm light extracted by spectrally separating a xenon lamp. FIG. 12A shows Example 6, and FIG. 12B shows Example. Corresponds to 7.
As can be seen from the above PL spectrum, this phosphor emitted red light with good color purity.

  FIGS. 13A to 13B are excitation spectra of the phosphors of Examples 6 to 7 measured at a detection wavelength of 640 nm. FIG. 13A shows the excitation spectrum of Example 6, and FIG. Corresponds to Example 7. According to the excitation spectrum described above, it can be seen that this phosphor is well excited and emits light from the ultraviolet region to the blue region.

  As described in detail above, according to the present invention, it is possible to obtain a phosphor having high efficiency light emission, in which a divalent metal element and a trivalent metal element are used as a base compound, and the base compound includes an activator element. it can.

In particular, a phosphor containing an activator element in the base compound represented by the general formula (I) is obtained, and in particular, a red light emitting fluorescence in which Eu is activated in the phosphor represented by the composition formula SrY ₂ S _4. The body is obtained. By using the phosphor manufactured by this manufacturing method, it is possible to provide a high-efficiency light-emitting element, in particular, a high-efficiency and high color rendering white light-emitting element. A light emitting device, an image display device, and a lighting device are provided.

It is typical sectional drawing which shows one Example of the light emitting element which has an excitation light source (semiconductor light emitting element which generate | occur | produces the light of a short wavelength of wavelength 360nm to 490nm) and fluorescent substance. It is typical sectional drawing which shows one Example of the surface emitting illumination device incorporating the light emitting element shown in FIG. It is a typical perspective view which shows an example of the light-emitting device to which what used the surface emission type thing as an excitation light source, and formed the fluorescent substance in the film form is applied. It is an example of the light-emitting device of this invention suitable when using as a backlight light source. It is a figure which shows the powder X-ray-diffraction pattern of the fluorescent substance manufactured by Examples 1-3. It is a figure which shows the emission spectrum (excitation light wavelength: 325 nm) of the fluorescent substance manufactured by Examples 1-3. FIG. 6 is a diagram showing a powder X-ray diffraction pattern of a phosphor manufactured according to Example 4. FIG. 6 is a diagram showing a powder X-ray diffraction pattern of a phosphor manufactured according to Example 5. It is a figure which shows the powder X-ray-diffraction pattern of the fluorescent substance manufactured by Example 6, 7. It is a figure which shows the emission spectrum (excitation light wavelength: 325 nm) of the fluorescent substance manufactured by Example 4, 5, and 6. FIG. It is a figure which shows the emission spectrum (excitation light wavelength: 325 nm) of the fluorescent substance manufactured by Example 6, 7. FIG. It is a figure which shows the emission spectrum (excitation light wavelength: 365 nm) of the fluorescent substance manufactured by Example 6, 7. FIG. It is a figure which shows the excitation spectrum (detection wavelength: 640 nm) of the fluorescent substance manufactured by Example 6, 7. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light emitting element, 2 ... Mount lead, 3 ... Inner lead, 4 ... Excitation light source, 5 ... Phosphor containing resin part, 6 ... Conductive wire, 7 ... Mold member, 8 ... Surface emitting illumination apparatus, 9 ... Diffusing plate DESCRIPTION OF SYMBOLS 10 ... Holding case, 11 ... Phosphor containing film, 12 ... Surface emitting type GaN-based laser diode, 13 ... Substrate, 21 ... Light emitting diode (LED), 22 ... Phosphor containing resin part, 23 ... Frame, 24 ... Conductive Wire, 25, 26 ... terminal

Claims (11)

In the production of a phosphor containing a divalent metal element, a trivalent metal element and sulfur as a base compound, and containing the activator element in the base compound,
A method for producing a phosphor, comprising heating a raw material compound containing a metal element constituting a phosphor in the presence of a simple sulfur or a sulfur-containing compound and a simple carbon or a carbon-containing compound. The method for producing a phosphor according to claim 1, wherein the base compound is represented by the following general formula (I).
MLn ₂ S ₄ (I)
(In formula (I), M represents one or more divalent metal elements, and Ln represents one or more trivalent metal elements.)   The method for producing a phosphor according to claim 1 or 2, wherein the divalent metal element is one or more metal elements selected from the group consisting of alkaline earth metals and zinc.   The trivalent metal element is one or more metal elements selected from the group consisting of rare earth elements, Al, Ga, and In. 4. A method for manufacturing the phosphor.   The activator element is one or more metal elements selected from the group consisting of Ce, Pr, Sm, Eu, Tb, Tm, Mn, Fe and Cr. 5. The method for producing a phosphor according to any one of 4 above.   The method for producing a phosphor according to any one of claims 1 to 5, further comprising a step of rapidly cooling after the heating step.   A phosphor manufactured by the method for manufacturing a phosphor according to claim 1. In a light-emitting element including a first light-emitting material and a second light-emitting material that performs wavelength conversion by absorbing light emitted from the first light-emitting material,
A light-emitting element using the phosphor according to claim 7 as the second light-emitting material.   A light-emitting device using the light-emitting element according to claim 8.   An image display device using the light emitting device according to claim 8.   A light-emitting element according to claim 8 is used.

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