JP2005132947A - Fluorophor for inorganic electroluminescence, method for producing the same, and inorganic electroluminescent device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fluorophor for inorganic electroluminescence high in uniformity and excellent in emission luminance, service life, particle size and particle size distribution, to provide a method for producing the fluorophor, and to provide a dispersion-type inorganic electroluminescent device using the fluorophor. <P>SOLUTION: The fluorophor, which is produced by a liquid phase method, is obtained by mixing together respective raw material component solutions containing a fluorophor matrix and the constituent element of an activator or coactivator to effect coprecipitation deposition of fluorophor matrix crystal and the activator or coactivator. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a phosphor for inorganic electroluminescence, a method for producing the same, and a dispersion-type inorganic electroluminescence element using the phosphor.

  2. Description of the Related Art Conventionally, an electroluminescence (hereinafter also referred to as EL) element is known as a thin light emitting element used for, for example, a backlight of a mobile phone. The phosphor material for EL can be divided into EL phosphor particles for dispersed EL elements and single crystals and vapor deposited phosphor films for thin film EL devices, depending on the basic structure of the EL elements that emit light. Dispersed zinc sulfide EL phosphor particles that are also used in the above-mentioned elements. This dispersion type EL element emits light by dispersing particles of a dispersion type EL phosphor in a dielectric material, and applying an AC voltage between electrodes at least one of which is arranged on both sides of the dispersed phosphor. In principle, it can be used to form elements on flexible film (PET, TAC, etc.) substrates using simple methods such as screen printing and various coating methods. Has also been used. However, when viewed as a surface light emitting device, brightness and life are insufficient compared to EL thin film devices and LED + light guide plates, and there are problems such as limited use, and improvement in performance has been demanded.

  On the other hand, as a manufacturing process of the phosphor for EL, the raw material powder containing the activator element and the elements constituting the phosphor matrix including the methods disclosed in Patent Document 1 and Patent Document 2 are simply mixed, and a very small amount of flux A solid-phase method of firing together has been conventionally used. However, in the solid phase method, it is difficult to produce a uniform phosphor. For this reason, there is a problem in that it is necessary to use a large amount of rare earth elements which are generally expensive, and a high temperature reaction process (1200 ° C. or higher) is required. . In addition, the need for strong grinding multiple times in order to arrange the particles at the minimum will cause surface defects and cracks in the phosphor particles, reducing quantum efficiency (light emission energy loss), and causing a significant deterioration in brightness and lifetime. Had.

  This is because the phosphor composition needs to be as close to the stoichiometric composition as possible in order to increase the luminous efficiency and yield of the phosphor, whereas in the solid phase method, the phosphor has a pure stoichiometric composition. It is difficult to produce, and it is often difficult to obtain a high-stoichiometric phosphor with excess impurities that do not react due to the reaction between solids and by-product salt, etc. It is also connected to In addition, the phosphor obtained by the solid phase method has a relatively wide particle size distribution, and in particular, when fired using a large amount of solvent, a phosphor having a wide particle size distribution close to the normal distribution can be obtained. When such a phosphor is used to form a dense phosphor film with high brightness, it is not preferable that a large amount of fine particles and coarse particles exist. These fine particles and coarse particles are removed by classification operation as necessary, but the classification operation is poor in workability and reduces the yield, and in particular, the generation of coarse particles reduces the yield of particles having a desired particle size. It has a great influence, and cannot be surely removed, but also cracks and defects are caused by grinding during classification.

  In order to overcome such problems of the solid phase method, a method for forming a phosphor precursor by reacting raw materials in a solution state is disclosed, including the method described in JP-A-11-293239. These methods are not disclosed to be applied to zinc sulfide phosphors used as inorganic EL phosphors and to improve their performance (brightness and lifetime).

  On the other hand, when a phosphor is manufactured by a liquid phase method, first, a precipitate that is a precursor of the phosphor is generated, and then the precursor is baked to obtain a phosphor. In the liquid phase method, the reaction is caused by the element ions constituting the phosphor. Therefore, it is easy to obtain a stoichiometric high-purity phosphor, but the phosphor particle size, particle shape, particle distribution shape, emission characteristics, etc. The properties depend on the properties of the precursor. Therefore, in order to obtain a desired phosphor, it is necessary to consider the control of the particle shape and particle distribution at the time of preparing the precursor, the exclusion of impurities, and the like. Therefore, an improved method relating to a method for producing a phosphor by a liquid phase method is disclosed in JP-A-2000-67813, 2000-67814, 2000-1000037, 2000-1000038, 2000-1000038, 2000-100303, 2002. 63850, etc. have been proposed, but these methods are not intended to disclose zinc sulfide phosphors used for inorganic EL phosphors, and the yield and yield of zinc sulfide phosphors as inorganic EL phosphors are not disclosed. It does not improve brightness and life.

Furthermore, the phosphor particles for inorganic EL used in the dispersion type EL element have a sufficient dispersion of the activator in the host crystal, the shape of the precipitated CuS present in the host crystal (within one particle), the phosphor The uniformity and dispersibility of the particle size and the uniformity of the distribution of CuS including the shape and particle size between the phosphor particles are large and have the characteristic of affecting the brightness and life, and change to the solid phase method There has been a demand for a production method unique to inorganic EL phosphors.
JP-A-7-157759 JP-A-5-179241

  The present invention has been made in view of the above circumstances, and an object of the present invention is an inorganic EL phosphor excellent in light emission luminance, lifetime, particle size, and particle size distribution, a method for producing the same, and a phosphor thereof. It is an object to provide an inorganic electroluminescence device using the above-mentioned.

The above object of the present invention is achieved by the following means.
(Claim 1)
A phosphor for inorganic electroluminescence manufactured using a liquid phase method, wherein each raw material component solution containing a constituent element of a phosphor matrix, an activator or a co-activator is mixed, and the phosphor matrix crystal, activation A phosphor for inorganic electroluminescence produced by co-precipitation of an agent or a coactivator.
(Claim 2)
2. The phosphor for inorganic electroluminescence according to claim 1, which is a zinc sulfide-based phosphor.
(Claim 3)
The phosphor for inorganic electroluminescence according to claim 1 or 2, represented by the following general formula.

ZnS: Cu, X
Or ZnS: Cu, Mn, X
(Here, X is a co-activator and is at least one element selected from chlorine (Cl), bromine (Br), iodine (I), and aluminum (Al).)
(Claim 4)
The phosphor for inorganic electroluminescence according to any one of claims 1 to 3, wherein the average particle size is 4 µm or less.
(Claim 5)
A method for producing a phosphor for inorganic electroluminescence using a liquid phase method, comprising mixing a raw material component solution containing constituent elements of a phosphor matrix, an activator or a co-activator, and phosphor matrix crystals, an activator Alternatively, a method for producing a phosphor for inorganic electroluminescence, comprising coprecipitation and coprecipitation to form a phosphor precursor, and then heating the obtained phosphor precursor.
(Claim 6)
A dispersion-type inorganic electroluminescence device using the phosphor for inorganic electroluminescence according to any one of claims 1 to 4.

  According to the present invention, the luminance and lifetime of the zinc oxide phosphor for inorganic EL are improved.

  Hereinafter, the best mode for carrying out the present invention will be described, but the present invention is not limited thereto.

  As the phosphor according to the present invention, known inorganic phosphors can be used as long as they are inorganic EL phosphors. The dispersion inorganic EL phosphor intended by the present invention is a zinc sulfide-based phosphor. Represented by any one of the general formulas ZnS: Cu, X and ZnS: Cu, Mn, X, and these phosphors represent copper (Cu) or copper (Cu) and manganese (Mn). Fluorescence for zinc sulfide-based inorganic EL, which is an activator, X is a coactivator, and X is at least one element of chlorine (Cl), bromine (Br), iodine (I), or aluminum (Al) The body is preferably used.

  At this time, in particular, a phosphor using Cl or Al as a co-activator as X is particularly preferable, and these are excellent in both luminance and lifetime.

  Conventionally, in this type of inorganic EL phosphor, a zinc sulfide base material is mixed with an activator material containing Cu, Mn, or the like and a coactivator material containing Cl, Al, etc. In the present invention, these zinc sulfide phosphors are manufactured by setting the manufacturing conditions using a coprecipitation precipitation method using a liquid phase method. To do.

  The coprecipitation method is a component having a constituent element that reacts to form a phosphor matrix (for example, a salt having an element that constitutes the phosphor matrix), an activator, or a raw material that contains a constituent element of the coactivator. By coexisting the components (salt having an atom that becomes an activator or coactivator), and causing them to undergo a liquid phase reaction in a solution, the activator or coactivator is coprecipitated together with the phosphor base crystal, This is a method for obtaining a parent crystal having an element that becomes an activator or a coactivator. At this time, the activator to be doped does not have to be one kind of atom, and may be composed of a plurality of kinds of atoms.

  For example, when manufacturing ZnS: Mn which specifically uses Mn as an activator, the following liquid phase reaction is indicated.

Zn (CH ₃ COO) ₂ + Mn (CH ₃ COO) ₂ + NaS
→ ZnS: Mn + 2CH ₃ COONa
The activator is added as a salt during the liquid phase reaction. In this case, examples of the salt having an atom serving as an activator include acetate and nitrate according to the type of the atom. When the atom used as an activator is specifically Mn and Cu, it is preferable to add to a liquid phase reaction as acetate. Moreover, when the atom used as an activator is Eu, it is preferable to add to a liquid phase reaction as nitrate. Further, when using a co-activator, for example, when chlorine (Cl) is used as the co-activator, it is preferable to add a compound such as CuCl or AgCl, and when it is aluminum (AL), it is added as a nitrate.

  In the present invention, the activator preferably selected from the above copper and manganese is contained in the range of 0.0001 to 0.2 mol% with respect to the phosphor matrix made of zinc sulfide. In addition, the coactivator selected from chlorine, bromine, iodine and aluminum is preferably contained in a range of 0.0001 to 0.1 mol% with respect to the phosphor matrix made of zinc sulfide.

  In a liquid phase reaction utilizing such a coprecipitation reaction, an organic acid can be added to the reaction system. Addition of an organic acid is preferable when a product having a smaller particle size is produced. In this case, examples of the organic acid used include acrylic acid and methacrylic acid.

  The organic acid added during the liquid phase reaction is polymerized to become a high molecular organic acid, which binds to the phosphor. That is, in the above-described example, the organic acid is polymerized to become a high molecular organic acid and is bonded to zinc sulfide.

  For example, when acrylic acid is used as the organic acid, the reaction is as follows.

ZnS: Mn + CH ₂ CHCOOH → (CH ₂ CHCOOH) ZnS: Mn
Moreover, an activator can be more uniformly disperse | distributed in a base crystal by adding an organic acid in the case of a liquid phase reaction. That is, by adding an organic acid during the liquid phase reaction, the phosphor can be produced so that the molecules of the activator doped in the phosphor base crystal are independent and uniformly dispersed. . Further, after the liquid phase reaction is completed, a high molecular organic acid or polystyrene may be added. By adding after completion, the surface of the phosphor is coated with a polymer organic acid, polystyrene or the like. Thereby, since defects on the particle surface can be reduced, non-radiative relaxation can be reduced.

  The coprecipitate particles (activator or phosphor matrix containing the coactivator) obtained as described above were separated by filtration from the liquid and recovered by a method such as evaporation to dryness or centrifugation. It is preferably washed later, followed by further drying and firing. Although there is no restriction | limiting in particular about drying temperature, It is preferable that drying temperature is the temperature near the temperature which the used solvent evaporates, and it is preferable that it is specifically the range of 50-300 degreeC. Although there is no restriction | limiting in particular also about a calcination temperature, Generally the range of 600-1500 degreeC can be used preferably. When the drying temperature is high, firing may be performed simultaneously with drying. Firing may be appropriately selected under any conditions in a reducing atmosphere, an oxidizing atmosphere, or in the presence of a sulfide. Further, if necessary, reduction treatment or oxidation treatment may be performed after firing.

  In order to obtain sufficient luminance, the phosphor of the present invention can be fired at a temperature lower by 100 ° C. or more than the solid phase method, which is very advantageous from the viewpoint of cost and productivity. In addition, as in the solid phase method, the firing process is sufficiently advanced even if impurities such as a flux (flux) are not mixed, so the rate of deactivation is reduced, which is advantageous from the viewpoint of luminous efficiency.

  Since the coprecipitation method in the liquid phase method of the present invention is a solution in which metal salts, organic acid compounds, and the like as raw materials are uniformly dissolved in a solvent such as alcohol, a plurality of matrix constituent metals and activator constituent metals, In addition, the co-activator is uniformly mixed at the molecular level, and can form phosphor base crystal particles (precursor) polymerized in an arrangement close to the lattice structure of the crystal after firing. It can be made. In addition, since the activator that is the light emission center is uniformly dispersed in the base crystal and local concentration quenching is unlikely to occur, the concentration of the activator can be increased, and the light emission efficiency is improved. Furthermore, since the shape distribution between the precipitated CuS particles as the activator becomes more uniform, it greatly contributes to the improvement of luminance and life.

  The particle size of the phosphor for inorganic EL of the present invention is 4.0 μm or less. In the conventional solid phase method, the average particle diameter is 5 to 20 μm, particles having a fairly wide distribution are formed, and the dispersion of the activator is biased, and it takes a long time to diffuse and move during firing. In addition, although there was a problem from the viewpoint of production, in the present invention, the particle size distribution was well controlled at 4.0 μm or less, and it was necessary to achieve the same luminance per unit volume of the activator. There is an advantage that the amount used can be reduced. In the present invention, the particle size is preferably 3 μm to 0.5 μm.

  These particle diameters are volume average particle diameters, and the volume average particle diameter is a circle-converted average obtained from the average value of the projected area of a transmission electron microscope (TEM) photograph (obtained for at least 100 particles or more). The particle size is obtained by converting to a spherical shape. Alternatively, it can be obtained by using a laser particle size analysis system manufactured by Otsuka Electronics, a Malvern company, and a Zetasizer.

  The variation coefficient of the particle diameter is a value obtained by dividing the standard deviation of the particle diameter by the particle diameter, and the larger the value, the wider the distribution of the particle diameter.

  For the phosphor particles obtained by the method according to the present invention, the coefficient of variation of the volume average particle diameter is preferably 100% or less, more preferably 80% or less.

  In the phosphor particles for dispersion-type inorganic EL according to the present invention, the content of the activator part (composition constituting) in the host crystal, for example, a metal such as an activator metal Cu and a coactivator Al, etc. The distribution coefficient (for example, concentration) between particles is preferably 100% or less, and most preferably 60% or less.

  About the content rate (for example, Cu density | concentration) of the activator part composition contained in each particle | grain, it is individual particle | grains using the secondary ion mass spectrometry (SIMS) apparatus which has a high resolution | decomposability of a submicron-nanometer order. It can be measured by measuring the composition. It is preferable to measure by placing phosphor particles on a sample stage and depositing carbon or the like. In particular, when measuring phosphor particles of 1 μm or less, it is possible to measure by crushing a certain thickness of the particles. Further, as a method for calculating the interparticle distribution variation coefficient of the content, the composition content (for example, Cu concentration) in at least 100 phosphor particles is measured by a secondary ion mass spectrometry (SIMS) apparatus, and the composition content ( The value obtained by multiplying the value obtained by dividing the standard deviation of the Cu concentration by the average content of 100 phosphor particles (average Cu concentration) by 100.

  In the dispersed inorganic EL phosphor particles of the present invention, it is preferable that the number of particles having a uniform distribution of the composition (for example, Cu) constituting the mother nucleus and the activator part is 50% or more in terms of the number of particles. 60% or more is more preferable, and 80% or more is most preferable.

  Here, that the distribution of copper, which is an activator metal, is uniform within a particle means that a certain composition, for example, the distribution ratio of copper is microscopically constant in any region within one particle. It is to be. More specifically, in the microscopic distribution measurement method described later, a certain composition measured in each section obtained by cutting one particle into small sections, for example, the value in the maximum section and the minimum in the copper content The difference from the value in the intercept is 20% or less of the average copper content of the particles.

  As a method for measuring the microscopic distribution of the composition contained in the particles, a transmission electron microscope (TEM) is used to analyze characteristic X-rays generated from the sample when irradiated with an electron beam, one by one. The internal composition distribution of the particles can be measured. For example, the phosphor particles as a sample can be continuously cut out as a section having a thickness of, for example, about 50 nm, and the section can be placed on a mesh for electron microscope observation to perform carbon deposition, and observation can be performed by a transmission method. Furthermore, as a method of calculating the ratio of particles such as copper having a microscopically uniform composition distribution, at least 100 phosphor particles may be measured by a transmission electron microscope and the ratio calculated.

The inorganic EL phosphor particles of the present invention are used, for example, in a light emitting layer 2 of a dispersion-type inorganic EL element 1 as shown in FIG. A dispersion-type EL element 1 shown in FIG. 1 is a luminous body in which the inorganic EL phosphor particles of the present invention described above are dispersed and contained in an organic polymer binder (organic dielectric) having a high dielectric constant such as cyanoethyl cellulose. Layer 2 is included. On one main surface of the phosphor layer 2, a reflective insulating material in which a highly reflective inorganic oxide powder such as TiO ₂ or BaTiO ₃ is dispersed and contained in an organic polymer binder having a high dielectric constant such as cyanoethyl cellulose. Layer 3 is laminated. The back electrode layer 4 made of a metal foil such as an Al foil or a metal film is integrally disposed on one main surface of the light emitting layer 2 with the reflective insulating layer 3 interposed therebetween.

  A transparent electrode layer (transparent electrode sheet) 5 in which an ITO film or the like is formed on a transparent insulating film such as a polyester (PET) film is integrally disposed on the other main surface of the luminous body layer 2. Yes. The transparent electrode sheet 5 is disposed so that the electrode film (ITO film) faces the light emitter layer 2. The transparent inorganic EL element 1 is configured by, for example, thermocompression bonding the transparent electrode layer 5, the light emitting layer 2, the reflective insulating layer 3, and the back electrode layer 4. Although not shown, electrodes are drawn from the back electrode layer 4 and the transparent electrode layer 5, respectively, and an alternating voltage is applied to the light emitter layer 2 from these electrodes.

  The dispersion-type inorganic EL element 1 made of the above-described laminate (thermocompression bonded body) is covered with a transparent packaging film 6. For the packaging film 6, for example, a moisture-proof film such as a polychlorotrifluoroethylene (PCTFE) film having a low water-humidity transmittance is used. If necessary, a hygroscopic film 7 such as a 6-nylon film is disposed on the transparent electrode layer 3 side. And the electroluminescence panel (EL panel) is comprised by carrying out the thermocompression bonding of the protrusion part of these packaging films 6, and sealing the dispersion | distribution type inorganic EL element 1. FIG.

  According to such a dispersion-type inorganic EL element 1 and an EL panel using the same, it is possible to increase the luminance based on the increase in luminance and life of the inorganic EL phosphor particles according to the present invention in the phosphor layer 2. It can be achieved and such brightness can be maintained over a long period of time.

  Furthermore, when producing a dispersion-type inorganic EL element and an EL panel using the same, a moisture-proof treatment is applied to each surface of the inorganic EL phosphor particles according to the present invention without using a moisture-proof film such as a PCTFE film. May be processed. The present invention can also be applied to an electroluminescent phosphor that has been subjected to moisture-proof treatment with a metal oxide, resin, or the like. That is, the inorganic EL phosphor particles according to the present invention may have a protective film (moisture-proof film) made of at least one selected from alumina, silica and titania. Even in such a configuration, it is possible to achieve high brightness and long life.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

  In the following examples, ZnS: Cu, Cl or ZnS: Cu, Al produced by a method other than the present invention are phosphors A, B, C, D, E, and those produced by the method of the present invention are phosphors. Let F, G, H. In addition, ZnS: Cu, Cl, Mn produced by the method of the present invention is phosphor I, and the phosphor produced by a method outside the present invention is phosphor J.

<Production of comparative phosphor>
<< phosphor A >>
After mixing 0.5 g of copper chloride, 0.5 g of copper sulfate and 7 g of zinc sulfate, the mixture was placed in a quartz crucible and baked at 800 ° C. for 40 minutes. After cooling to room temperature, it was removed from the crucible and washed with 50% acetic acid. Next, after washing with distilled water, it was washed with a warmed aqueous solution of potassium cyanide having a concentration of 5% by mass. The resulting product was washed with distilled water and dried at 130 ° C.

  As a result of measuring the obtained phosphor with a transmission electron microscope TEM, ZnS: Cu, Cl having an average particle size of 20 μm and a particle size distribution variation coefficient of 300% was obtained.

<< phosphor B >>
Zinc sulfide having a particle size distribution of 15 μm to 25 μm, 0.5 mol% of copper acetate [(CH ₃ COO) ₂ Cu · 2H ₂ O] as an activator raw material, and aluminum sulfate [AL ₂ (SO ₄ as a co-activator raw material) ) ₂ ] was added in an amount of 2.0 mol%, mixed with slurry in deionized water, and dried at 120 ° C. for 16 hours. Next, this mixture was placed in a quartz Tamman furnace and baked at 1000 ° C. for 2 hours while passing hydrogen sulfide. After firing, the mixture was crushed and treated with a 10% by mass aqueous potassium cyanide solution. Excess CuS that did not dissolve in ZnS was separated by etching, washed with water, and dried to obtain a ZnS: Cu, AL phosphor. As a result of measuring the average particle size and particle size distribution with a scanning electron microscope, the average particle size was 15 μm, and the particle size distribution variation coefficient was 350%.

<< phosphor C >>
In addition, in the production of the above ZnS: Cu, AL phosphor (phosphor B), 5.0 mol% ammonium chloride (NH ₄ CI) was added instead of 2.0 mol% aluminum sulfate, and other conditions were set. A ZnS: Cu, Cl phosphor was manufactured in the same manner without change. A ZnS: Cu, Cl phosphor having an average particle size of 24 μm and a particle size distribution variation coefficient of 300% was obtained.

<< phosphor D >>
453 g of ZnS having a particle size distribution of 15 to 25 μm containing 1% of chloride, 0.97 g of copper sulfate, 2.3 g of zinc oxide (ZnO), and 3% barium chloride by mass ratio with ZnS, Mixed with 3% magnesium chloride and 2% sodium chloride.

  The mixed material is put into a crucible with a lid and heated (or burned) at 1205 ° C. for 5 hours and 15 minutes in a furnace. After heating, the cake (or solid mass) is removed from the furnace, cooled and washed with deionized (or deionized water), and then dried. The dried material is then deformed to hexagonal (or hexagonal) so that a mechanical force is applied in the mill for a specified time. The mill time was 1 hour 30 minutes.

3.9 wt% CuSO ₄ and 25.56 wt% ZnSO ₄ .7H ₂ O are added to the milled material and mixed in a plastic bottle with a mechanical stirrer for 20 minutes. The blended material was removed and all lumps were crushed. This material was put in an alumina crucible, covered with an alumina lid, and heated in an electric furnace at 700 ° C. for 2 hours and 15 minutes. After heating and removing from the crucible and cooling to room temperature, the cake is washed with deionized water at least twice. After washing, the material is washed with acid to remove excess copper and other additives such as fluxes and impurities. The acid used is a deionized aqueous solution of 20% by weight glacial acetic acid. It was then washed with deionized water until pH 6 or lower, washed with KCN aqueous solution, and allowed to settle for 30 minutes. After decanting the KCN, it is washed with deionized water to remove any KCN residue. At this point in the process, the phosphor material changes from a greenish gray body color to light green. The phosphor is then filtered, dried at 120 ° C. or lower for 4-16 hours, and sieved through a 325 mesh screen. The average particle size of the obtained ZnS: Cu, Cl phosphor particles was 25 μm, and the particle size distribution variation coefficient was 250%.

<Phosphor E>
In Comparative D, ZnS having an average particle size of 25 μm and a particle size distribution coefficient of variation of 200% was formed except that, instead of barium chloride, magnesium chloride, and sodium chloride, a molar amount of aluminum sulfate was added. Cu and AL were obtained.

<Preparation of phosphor of the present invention>
<< phosphor F >>
150 ml of a methanol solution of zinc acetate (0.133 mol / l) and 25 ml of a methanol solution of copper chloride (0.008 mol / l) were mixed and stirred for 10 minutes using a magnetic stirrer to obtain a mixed solution. Next, the above mixed solution was added to 60 ml of a sodium sulfide aqueous solution (0.4 mol / l) in a state of being stirred using a magnetic stirrer. The mixture was further stirred for 15 minutes. Furthermore, it centrifuged for 20 minutes at 4000 rpm using the centrifuge. Thereafter, the particles obtained by centrifugation were blown and dried at 50 ° C. for 24 hours. Then, it baked at 800 degreeC for 4 hours. This was washed with a 1% aqueous KCN solution, washed with distilled water, and dried.

  As a result of measuring the obtained phosphor by TEM, ZnS: Cu, Cl of the phosphor F of the present invention having an average particle size of 3 μm and a particle size distribution variation coefficient of 80% was obtained.

<< phosphor G >>
150 ml of a methanol solution of zinc acetate (0.133 mol / l), 25 ml of a copper sulfate (0.0008 mol / l) methanol solution, and 25 ml of an aluminum nitrate (0.0001 mol / l) methanol solution are mixed, and a magnetic stirrer is used for 10 minutes. Stir to obtain a mixed solution. Next, the above mixed solution was added to 60 ml of a sodium sulfide aqueous solution (0.4 mol / l) in a state of being stirred using a magnetic stirrer. The mixture was further stirred for 15 minutes. Furthermore, it centrifuged at 4000 rpm for 20 minutes using the centrifuge. Thereafter, the particles obtained by centrifugation were blown and dried at 50 ° C. for 24 hours. Then, it baked at 800 degreeC for 4 hours. This was washed with a 1% aqueous KCN solution, washed with distilled water, and dried.

  As a result of measuring the obtained phosphor by TEM, ZnS: Cu, AL of the phosphor G of the present invention having an average particle size of 2.6 μm and a particle size distribution variation coefficient of 70% was obtained.

<< phosphor H >>
150 ml of a methanol solution of zinc acetate (0.133 mol / l) and 25 ml of a methanol solution of copper chloride (0.008 mol / l) were mixed and stirred for 10 minutes using a magnetic stirrer to obtain a mixed solution. Next, the above mixed solution was added to 60 ml of a sodium sulfide aqueous solution (0.4 mol / l) in a state of being stirred using a magnetic stirrer. The mixture was further stirred for 15 minutes. Next, 50 ml of acrylic acid (0.7 mol) was added to this mixed solution and stirred vigorously for 15 minutes. Furthermore, it centrifuged for 20 minutes at 4000 rpm using the centrifuge. Thereafter, the particles obtained by centrifugation were blown and dried at 50 ° C. for 24 hours. Then, it baked at 800 degreeC for 4 hours. This was washed with a 1% aqueous KCN solution, washed with distilled water, and dried.

  As a result of measuring the obtained phosphor by TEM, ZnS: Cu, Cl of the phosphor H of the present invention having an average particle size of 2.7 μm and a particle size distribution variation coefficient of 55% was obtained.

<< phosphor I >>
A methanol solution of zinc acetate (0.133 mol / l) (150 ml), a copper chloride (0.0008 mol / l) methanol solution (25 ml) and a methanol solution of manganese acetate (0.0001 mol / l) were mixed and mixed using a magnetic stirrer. Stir for minutes to obtain a mixed solution. Next, the above-mentioned mixed solution was added to 60 ml of a sodium sulfide aqueous solution (0.4 mol / l) stirred using a magnetic stirrer. The mixture was further stirred for 15 minutes. Next, 50 ml of acrylic acid (0.7 mol) was added to this mixed solution and vigorously stirred for 15 minutes. Furthermore, it centrifuged at 4000 rpm for 20 minutes using the centrifuge. Thereafter, the particles obtained by centrifugation were blown and dried at 50 ° C. for 24 hours. Then, it baked at 800 degreeC for 4 hours. This was washed with a 1% KCN solution, washed with distilled water, and dried.

  As a result of measuring the obtained phosphor by TEM, ZnS: Cu, Mn, Cl having an average particle size of 3 μm and a particle size distribution variation coefficient of 80% was obtained.

<Phosphor J>
After mixing 0.5 g of copper chloride (total amount of 1% copper), 7 g of zinc sulfate, and 0.21 g of manganese carbonate (total amount of 0.5% manganese), the mixture was put into a quartz crucible, 800 Baked at 40 ° C. for 40 minutes. After cooling to room temperature, remove from the crucible and wash with 50% acetic acid. Next, it is washed with distilled water and dried at 130 ° C.

  As a result of measuring the obtained phosphor by TEM, Zn: Cu, Mn, Cl having an average particle diameter of 20 μm and a particle size distribution variation coefficient of 30% was obtained.

  Dispersion type EL device having a light emitting layer with a thickness of 50 μm between aluminum electrode and transparent electrode of polyethylene terephthalate film with transparent conductive film (indium oxide thin film) deposited by dispersing the prepared phosphor in cyanoethyl cellulose did.

  An alternating voltage of 100 V and 400 Hz was applied to the device, and initial light emission luminance and luminance half-life were measured.

  The results are shown in Table 1 as relative values with the initial light emission luminance and luminance half-life of the dispersion type EL element using the phosphor of Comparative A as 100, respectively.

  The measurement of the activator content rate and the ratio of the particles in which the activator was uniformly distributed were obtained by the following measurement.

<Measurement of composition (activator) content>
For each phosphor sample, using a secondary ion mass spectrometry (SIMS) apparatus, the Al and Cu content rates of 100 particles are measured, and the standard deviation of the Al and Cu content rates of each phosphor is calculated. The interparticle distribution was calculated from the value obtained by multiplying the value obtained by dividing the average content by 100.

In addition, as a content rate, the atomic concentration (atoms / cm < ³ >) by SIMS was used.

<Measurement of distribution uniform particle abundance ratio (%)>
For each sample, the distribution of the internal composition was measured for 100 particles using a transmission electron microscope (TEM), and the ratio (%) of microscopically uniform particles was calculated.

  Microscopically uniform particles, that is, particles in which the distribution of the activator metal, copper or aluminum, is uniform within the particles (for each of the 100 phosphor particles, each phosphor particle is continuously divided into 50 nm-thick sections. Then, using a transmission electron microscope (TEM), by analyzing characteristic X-rays generated from each section sample when irradiated with an electron beam, the concentration of copper or aluminum in the particles in each section is obtained. The difference between the intercept with the maximum concentration and the intercept with the minimum concentration is obtained for each particle, and the ratio (%) of the particles in which the difference is 20% or less of the average copper or aluminum concentration of the particle is calculated. is there.

  The results are shown in Table 1.

  As is apparent from Table 1, the dispersion-type inorganic EL element obtained using the phosphors F to H of the present invention has improved initial luminance and reduced luminance by half compared to the example using the comparative phosphors A to E. The period showed a remarkable improvement of 3 times.

  Furthermore, it turns out that the brightness | luminance of the fluorescent substance particle produced using the method of this invention with a narrow interparticle distribution of copper content is high with respect to a comparison particle. It was also confirmed that the phosphor particles of the present invention having a fine particle ratio with a microscopically uniform internal composition have higher luminance than the comparative particles.

It is sectional drawing which shows the principal part structure of the dispersion | distribution type inorganic EL element by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dispersion type inorganic EL element 2 Light-emitting body layer 3 Reflective insulating layer 4 Back electrode layer 5 Transparent electrode layer

Claims (6)

Phosphor for inorganic electroluminescence manufactured using a liquid phase method, wherein each raw material component solution containing constituent elements of a phosphor matrix, an activator or a co-activator is mixed, and the phosphor matrix crystal, activation A phosphor for inorganic electroluminescence produced by co-precipitation of an agent or a co-activator. 2. The phosphor for inorganic electroluminescence according to claim 1, which is a zinc sulfide-based phosphor. The phosphor for inorganic electroluminescence according to claim 1 or 2, represented by the following general formula.
ZnS: Cu, X
Or ZnS: Cu, Mn, X
(Here, X is a co-activator and is at least one element selected from chlorine (Cl), bromine (Br), iodine (I), and aluminum (Al).) The phosphor for inorganic electroluminescence according to any one of claims 1 to 3, wherein the average particle size is 4 µm or less. A method for producing a phosphor for inorganic electroluminescence using a liquid phase method, comprising mixing a raw material component solution containing constituent elements of a phosphor matrix, an activator or a coactivator, and phosphor matrix crystals, an activator Alternatively, a method for producing a phosphor for inorganic electroluminescence, comprising coprecipitation and coprecipitation to form a phosphor precursor, and then heating the obtained phosphor precursor. A dispersion-type inorganic electroluminescence device using the phosphor for inorganic electroluminescence according to any one of claims 1 to 4.

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