JP2006156358A - Distributed electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distributed EL element emitting white light and having an excellent color rendering property, especially a red color rendering property. <P>SOLUTION: This electroluminescent element comprises a transparent electrode, a phosphor layer, a dielectric layer and a rear face electrode in this order. The dielectric layer comprises dielectric particles and a color conversion material, and (1) the color conversion material has a specific content ratio and the dielectric layer has a specific thickness or (2) an emission maximum wave length of the color conversion material is 600-750 nm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dispersive electroluminescent element having a light emitting particle layer formed by dispersing and applying electroluminescent phosphor particles.

  Electroluminescence (hereinafter, also referred to as “EL”) phosphors are voltage-excited phosphors, and are known to be used as distributed EL elements in which phosphor particles are sandwiched between electrodes and used as light-emitting elements. Yes. The general shape of a dispersion-type EL device is a structure in which phosphor particles are dispersed in a binder with a high dielectric constant, and at least one is sandwiched between two transparent electrodes. Light is emitted by applying an electric field. The dispersive EL element having such a structure can have a thickness of 1 mm or less, and can form a flexible and lightweight element using a plastic substrate without using a high-temperature process in the manufacturing process. It has many advantages such as being able to be manufactured at a low cost with a relatively simple process without using a vacuum device, and it can be applied to backlights and display elements such as LCDs. Specifically, there are uses as road signs, illumination for various interiors and exteriors, light sources for flat panel displays such as liquid crystal displays, illumination light sources for large-area advertisements, and the like.

  Although the emission color is desirably white for use as a light source of the dispersion type EL element, since there is no phosphor that emits white light alone, various techniques have been proposed for obtaining white light in the dispersion type EL element. Dispersion EL elements that have been proposed to emit white light have emission waveforms in which the emission intensity is concentrated mainly in two wavelength regions around blue-green and orange to red. As described above, these dispersive EL elements that emit white light have various advantages as a flexible planar light source, but color rendering properties, particularly red color rendering properties, compared to other white light sources such as fluorescent lamps. There was a serious problem in that it was greatly inferior. For example, when a transmissive medium such as a transparent positive image is placed on an EL element and observed, the color reproducibility of red is greatly inferior to the case where a conventional fluorescent lamp or the like is used as a flat light source, and almost expresses red. Was not possible.

  For example, many of conventional dispersion-type ELs have been made white light-emitting EL elements by putting a rhodamine-based compound in a light-emitting particle layer (for example, Patent Documents 1 to 3). In these EL elements, orange light emission derived from light emission of a rhodamine compound is used as red light emission. However, although these EL devices emit white light, red cannot be reproduced when a transparent medium such as a transparent positive image is placed thereon.

  Further, a technique has been proposed in which a color conversion layer and a pigment layer are provided above the phosphor layer (transparent electrode side: viewing side) to obtain EL elements having different emission colors (for example, Patent Documents 4 and 5). Furthermore, a technique for obtaining a red light emitting EL element by laminating a color conversion layer having a complementary color relationship with a light emitting particle layer and a red filter that passes only a wavelength near 600 nm above the light emitting particle layer is proposed. (Patent Document 6). However, even with these techniques, sufficient red reproducibility (red color rendering) could not be obtained.

On the other hand, Patent Document 7 proposes an EL element containing a photoexcitation material in any layer constituting the EL element.
JP-A-60-25195 JP 60-170194 A Japanese Patent Laid-Open No. 2-78188 JP-A-6-163159 Japanese Patent Laid-Open No. 3-15191 JP-A-11-67456 JP-A-11-67458

  An object of the present invention is to obtain a dispersion type EL element that emits white light and has excellent color rendering properties, particularly red color rendering properties.

  Conventional dispersion-type EL elements emit white light, but in all cases, the wavelength of red light emission is shortwave (orange light emission), and red color reproducibility (red The color rendering properties) were extremely poor. The present inventors have noticed that the red color reproducibility is poor in the prior art because the conventional dispersion type EL element hardly contains the wavelength of the original red light. In order to improve the property, it was considered necessary to increase the emission wavelength of the red light component during white light emission from orange to red.

  In the dispersion-type EL element, a color conversion material that emits red light is used in addition to phosphor particles that emit blue-green light to produce white light emission. In a conventional dispersion-type EL element, a pigment obtained by dispersing an organic dye in a polymer and pulverized in a particulate form is used as a red color conversion material dispersed in a light emitting particle layer (hereinafter also referred to as a phosphor layer). However, when the emission wavelength of the pigment is measured in such a state that the pigment is dispersed in the medium, the emission wavelength shifts to a shorter wavelength side as compared with the emission wavelength measured in the pigment powder. This shift toward the short wavelength side lowers the red color reproducibility.

  In order to prevent the shift to the short wavelength side described above, the present inventors added a pigment to the dielectric layer, and made use of the light scattering of the dielectric particles occurring in the dielectric layer, thereby preventing the self-absorption of the pigment. It has been found that the apparent emission wavelength can be increased by increasing the wavelength. This long wave is (1) particularly large when the content ratio of the pigment in the dielectric layer is in a specific range and the thickness of the dielectric layer is in a specific range, and high red reproducibility is obtained. I found out. Similar findings were obtained for other color conversion materials such as dyes. Furthermore, it was found that (2) high red reproducibility can be obtained even when the emission maximum wavelength of the color conversion material contained in the dielectric layer is 600 nm or more and 750 nm or less. Furthermore, it has also been found that by providing a dielectric layer containing a color conversion material below the phosphor layer, it is possible to obtain an EL element that maintains the luminance while minimizing light absorption from EL emission. Based on these findings, the present inventors have found that an EL element having the following constitution can achieve the above object, and have completed the present invention.

  On the other hand, the conventional EL elements have insufficient durability, and the present situation is that there is a demand for the development of EL elements that are excellent in durability because there is little decrease in light emission luminance due to deterioration of phosphor particles. As one of the measures for improving the durability of the EL device, by preventing moisture from touching the phosphor particles, an EL device that maintains white and good color rendering for a long time and can maintain luminance is obtained. It came to.

That is, the present invention has the following configuration.
(1) In an electroluminescence device containing a transparent electrode, a phosphor layer, a dielectric layer, and a back electrode in this order,
The dielectric layer includes dielectric particles and a color conversion material, the content ratio of the color conversion material is 0.1% by mass or more and 20% by mass or less with respect to the dielectric particles, and the thickness of the dielectric layer is 1. An electroluminescent element characterized by being 1 μm or more and 20 μm or less.
(2) In an electroluminescent device containing a transparent electrode, a phosphor layer, a dielectric layer, and a back electrode in this order,
The electroluminescent device, wherein the dielectric layer contains dielectric particles and a color conversion material, and the emission maximum wavelength of the color conversion material is 600 nm or more and 750 nm or less.
(3) In an electroluminescence device containing a transparent electrode, a phosphor layer, a dielectric layer, and a back electrode in this order, the dielectric layer includes dielectric particles and a color conversion material, and the emission maximum of the color conversion material The wavelength is from 600 nm to 750 nm, the content of the color conversion material is from 0.1% by mass to 20% by mass with respect to the dielectric particles, and the thickness of the dielectric layer is from 1 μm to 20 μm. An electroluminescence element characterized by the above.
(4) The electroluminescence device according to (3), wherein the color conversion material is a material in which an organic compound is dispersed in a polymer.
(5) In the electroluminescence device containing the transparent electrode, the phosphor layer, the dielectric layer, and the back electrode in this order, the phosphor layer includes phosphor particles having a coating layer (1) To (4). The electroluminescence device according to any one of (4) to (4).
(6) The electroluminescent device according to (5), wherein the coating layer includes a material having an absorption edge at a wavelength of 280 nm to 420 nm.
(7) It has two emission maxima in the visible region, and among these two emission maxima, it has a short wave side emission maximum in the range of 480 nm to 510 nm, and has a long wave side emission maximum in the range of 590 nm to 625 nm, The electroluminescence device according to any one of (1) to (6), wherein the emission minimum is in the range of 571 nm to 583 nm.
(8) The phosphor particles have an average particle size of 0.1 to 20 μm, a variation coefficient of the particle size distribution of less than 35%, and fluorescent particles containing 10 or more layers of stacking faults with a spacing of 5 nm or less. The electroluminescent element according to any one of (5) to (7), which is a ZnS-based electroluminescent phosphor having 30% by volume or more of the whole body particles.

  According to the EL element of the present invention, it is possible to obtain a dispersion type EL element that emits white light and has excellent color rendering properties, particularly red color rendering properties.

Hereinafter, the EL element of the present invention will be described in detail.
The EL device of the present invention contains a transparent electrode, a phosphor layer, a dielectric layer, and a back electrode in this order.

<Dielectric layer>
The dielectric layer includes dielectric particles and a color conversion material.
And (1) The content rate of this color conversion material is 0.1 mass% or more and 20 mass% or less with respect to dielectric particle, and the thickness of this dielectric material layer is 1 micrometer or more and 20 micrometers or less.
Alternatively, (2) the dielectric layer includes dielectric particles and a color conversion material, and the emission maximum wavelength of the color conversion material is 600 nm or more and 750 nm or less.
With the above-described configuration, a dispersion type EL element that emits white light and has excellent color rendering properties, particularly red color rendering properties, can be obtained.
In the above (1), the content ratio of the color conversion material contained in the dielectric layer is mass% with respect to the dielectric particles, and is 0.1 mass% or more and 20 mass% or less as described above, preferably 0.8%. It is the range of 5 mass% or more and 10 mass% or less.
The thickness of the dielectric layer containing the color conversion material is 1 μm or more and 20 μm or less as described above, and preferably 3 μm or more and 18 μm or less.
By setting the content ratio of the color conversion material contained in the dielectric layer and the thickness of the dielectric layer within the above ranges, the EL element can achieve white color emission and high color rendering.
In (2) above, the emission maximum wavelength of the color conversion material is 600 nm or more and 750 nm or less as described above, preferably 610 nm or more and 650 nm or less, and more preferably 610 nm or more and 630 nm or less.
By setting the light emission maximum wavelength of the color conversion material contained in the dielectric layer within the above range, the EL element can achieve high color rendering with white light emission.
In addition, as described above, the EL element of the present invention contains a transparent electrode, a phosphor layer, a dielectric layer, and a back electrode in this order, and the color conversion material is below the phosphor layer (back electrode side). By providing the light source, the light absorption from EL light emission can be minimized and the luminance can be maintained.

  With the above-described configuration, the peak wavelength of red light emission during white light emission of the dispersion type EL element can be within a preferable range of 590 nm to 625 nm, and the peak wavelength of blue-green light emission is 480 to 510 nm. I can do it. Further, at this time, the minimum value between the blue-green light emission band and the red light emission band can be set in the range of 571 nm to 583 nm. The red emission peak wavelength is more preferably in the range of 595 nm to 620 nm, most preferably 600 nm to 615 nm. The emission peak wavelength of blue-green light emission is more preferably 483 nm to 505 nm, and further preferably 485 nm to 503 nm.

If the EL element of the present invention has layers in the above order, other layers described later can be provided.
In the present invention, in addition to the above-described dielectric layer containing the color conversion material (hereinafter also referred to as color conversion material-containing dielectric layer or dielectric layer A), the dielectric layer further does not contain the color conversion material. (Hereinafter, it is also referred to as a dielectric layer B. The number “dielectric layer B-number” represents the position of the dielectric layer B in the EL element.). For example, a dielectric layer A and a dielectric layer B are stacked to form an EL element having an order of a transparent electrode, a phosphor layer, a dielectric layer A, a dielectric layer B, and a back electrode. Furthermore, the dielectric layer B is provided on both sides of the dielectric layer A, and has the order of transparent electrode, phosphor layer, dielectric layer B-1, dielectric layer A, dielectric layer B-2, and back electrode. It can be an EL element. Furthermore, the dielectric layer B is provided on the side opposite to the dielectric layer A (transparent electrode side) across the phosphor layer, and the transparent electrode, dielectric layer B-3, phosphor layer, dielectric layer A, and It can be set as the EL element which has the order of a back electrode.
When the dielectric layer B is included in addition to the dielectric layer A, the total thickness of the entire dielectric layer is preferably 5 μm or more and 40 μm or less, and more preferably 5 μm or more and 35 μm or less. When the dielectric layer B is provided on both sides of the dielectric layer A, the thickness of the dielectric layer B-1 provided on the phosphor layer side is preferably 1 μm or more and 10 μm or less, more preferably 1 μm or more and 7 μm or less.

  The color conversion material-containing dielectric layer A includes dielectric particles and a color conversion material. In the present invention, the color conversion material is substantially contained only in the color conversion material-containing dielectric layer A. The phrase “substantially contained only in the color conversion material-containing dielectric layer A” means that 70% by mass or more of the color conversion material contained in the EL element is contained in the dielectric layer A. When the fluorescent pigment used as the color conversion material has a low resistance to the dispersion solvent, 1/2 or more of the dye contained in the fluorescent pigment before being added to the dispersion solvent is contained in the dielectric layer A This also means that the color conversion material is substantially contained in the dielectric layer A. The color conversion material is substantially uniformly contained in the color conversion material-containing dielectric layer A. “Substantially uniformly contained” means that there is no density gradient when viewed as the whole layer, and the molecules and pigment particles of the color conversion material are contained in a state where the distribution is not biased as a whole layer. At this time, the color conversion material molecules and particles may exist in a state where a plurality of molecules and particles are gathered as long as they are contained substantially uniformly as a whole layer.

[Dielectric particles]
The color conversion material-containing dielectric layer A is formed including dielectric particles.
The dielectric particles can be formed using any material as long as it has a high dielectric constant and insulation, is a dielectric material having a high dielectric breakdown voltage, and has a high reflectance. Such a material is selected from metal oxides and nitrides. For example, TiO ₂ , BaTiO ₃ , SrTiO ₃ , PbTiO ₃ , KNbO ₃ , PbNbO ₃ , Ta ₂ O ₃ , BaTa ₂ O ₆ , LiTaO ₃ , Y ₂ Examples include O ₃ , Al ₂ O ₃ , ZrO ₂ , AlON, ZnS, and the like. The average size of the dielectric particles is preferably an average particle diameter of 2.0 μm or less, more preferably 0.01 μm or more and 1.0 μm or less, and most preferably 0.05 μm or more and 0.5 μm or less. Similarly to the color conversion material-containing dielectric layer A, the dielectric layer B not containing the color conversion material can be formed including dielectric particles. As the dielectric particles, the same particles or different particles may be used for the color conversion material-containing dielectric layer A and the dielectric layer B not containing the color conversion material.

[Color conversion material]
As the color conversion material used in the color conversion material-containing dielectric layer A, a fluorescent pigment or a fluorescent dye can be preferably used. These may be used in combination. Compounds having these luminescence centers are preferably compounds having rhodamine, lactone, xanthene, quinoline, benzothiazole, triethylindoline, perylene, triphenine, dicyanomethylene as the skeleton, and other cyanine dyes, azo dyes, polyphenylene vinylenes. It is also preferable to use a polymer, a disilane oligothienylene polymer, a ruthenium complex, a europium complex, or an erbium complex. These compounds may be used alone or in combination.
In the embodiment of (1), it is also preferable to use a color conversion material having a light emission maximum wavelength of 600 nm or more and 750 nm or less. Such a configuration is preferable because the color rendering property of red is further improved.
Further, these compounds may be used after further being dispersed in a polymer or the like.

[Binder]
The dielectric particles are preferably dispersed in a binder. The binder is preferably a polymer having a relatively high dielectric constant such as a cyanoethyl cellulose resin, or a resin such as polyethylene, polypropylene, polystyrene resin, silicone resin, epoxy resin, or vinylidene fluoride. As a method for dispersing the dielectric particles, it is preferable to disperse using a homogenizer, a planetary kneader, a roll kneader, an ultrasonic disperser or the like.

  The dielectric layer B that does not contain a color conversion material can also be formed as a uniform film. Further, as described above, it can also be formed including dielectric particles. Alternatively, a combination thereof may be used. “The film is uniform” means that the dielectric layer itself is an amorphous layer or a layer having a crystal structure. Examples of the uniform film include a layer made of only a high dielectric constant binder and a thin film crystal layer. When the dielectric layer B is formed as a uniform film, the thickness is preferably in the range of 0.1 μm to 10 μm.

  When the dielectric layer is formed by coating, it is preferable to use a slide coater or an extrusion coater. In the case of a thin film crystal layer, it may be a thin film formed on a substrate by a vapor phase method such as sputtering or vacuum deposition, or a sol-gel film using an alkoxide such as Ba or Sr.

  When forming the dielectric layer A and when forming the dielectric layer B including dielectric particles, it is preferable to form the dielectric layer by applying a coating liquid for forming a dielectric layer. The dielectric layer forming coating solution is a coating solution containing at least dielectric particles, a binder, and a solvent for dissolving the binder. The coating liquid for forming the dielectric layer A further contains a color conversion material. Here, the solvent may be the same as that used for the phosphor layer.

  The viscosity of the dielectric layer forming coating solution is preferably in the range of 0.1 Pa · s to 5 Pa · s, particularly preferably in the range of 0.3 Pa · s to 1.0 Pa · s. If the viscosity of the coating liquid for forming the dielectric layer is within the above range, the film thickness unevenness of the coating film is difficult to occur, and the dielectric particles do not separate and settle with the passage of time after dispersion. Application is also possible and preferable. The viscosity is a value measured at 16 ° C. which is the same as the coating temperature.

<Phosphor layer>
The phosphor layer is formed including phosphor particles.
[Phosphor particles]
As the phosphor particles preferably used in the present invention, particles prepared by various preparation methods such as firing by mixing a base material, an activator, and, if necessary, a coactivator are used.
Specifically, the base material used in this case is one or more elements selected from the group consisting of Group II elements and Group VI elements, and a group consisting of Group III elements and Group V elements. Semiconductor fine particles composed of one or a plurality of selected elements, which are arbitrarily selected according to a necessary emission wavelength region. Examples thereof include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, CaS, MgS, SrS, GaP, GaAs, and mixed crystals thereof. ZnS, CdS, CaS, and the like can be preferably used. Furthermore, as the base material of the _{particles, BaAl 2 S 4, CaGa 2} S 4, Ga 2 O 3, Zn 2 SiO 4, Zn 2 GaO 4, ZnGa 2 O 4, ZnGeO 3, ZnGeO 4, ZnAl 2 O 4, _{CaGa 2 O 4, CaGeO 3,} Ca 2 Ge 2 O 7, CaO, Ga 2 O 3, GeO 2, SrAl 2 O 4, SrGa 2 O 4, srP 2 O 7, MgGa 2 O 4, Mg 2 GeO 4, _{MgGeO 3, BaAl 2 O 4,} Ga 2 Ge 2 O 7, BeGa 2 O 4, Y 2 SiO 5, Y 2 GeO 5, Y 2 Ge 2 O 7, Y 4 GeO 8, Y 2 O 3, Y 2 O ₂ S, SnO ₂ and mixed crystals thereof can also be preferably used.
Moreover, as an activator, metal ions, such as Mn and Cu, rare earth elements, etc. can be used preferably.
Moreover, as a coactivator added as needed, halogen elements, such as Cl, Br, I, Al, etc. can be used preferably.

Furthermore, in the present invention, it is more preferable to use the following phosphor particles.
(A) Phosphor particles having an average particle size (sphere equivalent diameter) in a range of 0.1 μm or more and 20 μm or less and a variation coefficient of the particle size of less than 35%.
(B) Phosphor particles having an average particle size in the range of 0.1 μm or more and 20 μm or less and containing 10 or more layers of stacking faults with a spacing of 5 nm or less inside the particles.
(C) The phosphor particles according to any one of (a) and (b), which are coated with a non-light emitting shell layer having a thickness of 0.01 μm or more.
(D) The phosphor particles according to any one of (a) to (c), wherein the activator is at least one ion selected from copper, manganese, silver, gold, and a rare earth element.
(E) The phosphor particles according to any one of (a) to (d), wherein the coactivator is at least one ion selected from chlorine, bromine, iodine, and aluminum.
(F) The phosphor particles according to any one of (a) to (e), wherein the activator is a copper ion and the coactivator is a chlorine ion.

In particular, in the present invention, it is preferable to use the following phosphor particles.
The phosphor particles preferably have an average particle size in the range of 0.1 to 20 μm and more preferably 1 to 15 μm in order to reduce the thickness of the phosphor layer and increase the electric field strength. In order to increase the uniformity of light emission and the filling rate of the phosphor particles in the phosphor layer, the particle size variation coefficient is preferably less than 35%, more preferably less than 30%. Since the inside of the particle has a higher EL emission efficiency when it has a structure with many planar stacking faults, the number of particles having stacking faults of 10 layers or more with an interplanar spacing of stacking faults of 5 nm or less is all. It is preferable that 30% or more of the number of phosphor particles is present, more preferably 50% or more, and still more preferably 70% or more.
The phosphor particles are preferably a ZnS-based electroluminescent phosphor. Use of the phosphor particles as described above is preferable because deterioration due to ultraviolet rays can be further reduced and durability can be improved.

The phosphor particles usable in the present invention can be formed by a firing method (solid phase method) widely used in the industry. For example, in the case of zinc sulfide, a fine particle powder (usually referred to as raw powder) having a crystallite size in the range of 10 nm to 50 nm is prepared by a liquid phase method, and this is used as a primary particle, to which an impurity called an activator is added. The particles are mixed by first baking in the crucible together with the flux at a high temperature in the range of 900 ° C. to 1300 ° C. for 30 minutes to 10 hours. The intermediate phosphor particles obtained by the first firing are repeatedly washed with ion exchange water to remove alkali metal or alkaline earth metal, excess activator and coactivator. Next, second baking is performed on the obtained intermediate phosphor particles. In the second baking, heating (annealing) is performed in a range of 500 to 800 ° C., which is lower than that of the first baking, and in a range of 30 minutes to 3 hours for a short time. These firings cause many stacking faults in the phosphor particles, but the conditions of the first firing and the second firing are appropriately set so that fine particles and more stacking faults are included in the phosphor particles. It is preferable to select. Further, by applying an impact force in a certain range to the intermediate phosphor particles, the density of stacking faults can be greatly increased without destroying the particles. As a method of applying impact force, a method of contacting and mixing intermediate phosphor particles, a method of mixing and mixing spheres such as alumina (ball mill), a method of accelerating and colliding particles, a method of irradiating ultrasonic waves, etc. It can be preferably used. Thereafter, etching with an acid such as HCl removes the metal oxide adhering to the surface, and the copper sulfide adhering to the surface is removed by washing with KCN and dried to obtain phosphor particles.
In addition, as a method for forming phosphor particles that can be used in the present invention, it is also preferable to use a hydrothermal synthesis method, a urea melting method, or a spray pyrolysis method, and further, laser ablation method, CVD method, plasma CVD. Gas phase methods such as methods combining sputtering, resistance heating, electron beam methods, fluid oil surface deposition, etc., metathesis methods, methods based on precursor thermal decomposition reactions, reverse micelle methods and these methods combined with high-temperature firing It can also be formed by using a liquid phase method such as a method or a freeze-drying method.

[Coating layer]
The phosphor particles used in the present invention preferably include phosphor particles having a coating layer formed by forming a coating layer on the surface of the core particle as the phosphor particles. The average film thickness of the coating layer is preferably 0.01 to 1 μm, and more preferably 0.05 to 0.5 μm. Here, the average film thickness of the coating layer is measured from three cross-sectional SEM photographs of the phosphor particles on which the coating layer is formed, and the coating layer film thickness is measured at any three points per particle for 10 or more particles. The average value.
When the average film thickness of the coating layer is within the above range, good moisture resistance and ion barrier properties can be obtained, and it is difficult to cause a decrease in luminance and an increase in the emission threshold voltage without decreasing the electric field strength to the phosphor particles. Therefore, it is preferable.
The coating layer preferably has a film thickness suitable for the average size of the particles. For example, when a 1 μm coating layer is formed on 1 μm particles, the electric field strength on the particles tends to be reduced. Accordingly, the ratio of the average film thickness of the coating layer to the average particle size of the particles is preferably in the range of 0.001 to 0.1, and more preferably in the range of 0.002 to 0.05.

The composition of the coating layer is not particularly limited, but oxides, nitrides, hydroxides, fluorides, phosphates, diamond-like carbon and organic compounds can be used, and their mixtures, mixed crystals, multilayer films, etc. Use is also preferred. _{Specifically, SiO 2, Al 2 O 3} , TiO 2, ZrO 2, HfO 2, Ta 2 O 5, Y 2 O 3, La 2 O 3, CeO 2, BaTiO 3, SrTiO 3, PZT, Si 3 N ₄ , AlN, Al (OH) ₃ , MgF ₂ , CaF ₂ , Mg ₃ (PO ₄ ) ₂ , Ca ₃ (PO ₄ ) ₂ , Sr ₃ (PO ₄ ) ₂ , Ba ₃ (PO ₄ ) ₂ , fluorine Resins are preferred.

The coating layer improves the luminous efficiency of the phosphor particles and reduces deterioration over time. Also, moisture resistance and ion barrier properties are imparted. Furthermore, it is preferable to provide an action for ultraviolet absorption by providing a coating layer. As a result, deterioration with time can be further reduced, and further, color deviation can be reduced. From the viewpoint of ultraviolet absorption, the coating layer preferably includes a material having an absorption edge at a wavelength of 280 nm to 420 nm.
Examples of such a material include the following materials.
i) that the coating material itself absorbs ultraviolet _{(TiO 2, ZnO, CeO 2} , ZrO 2, mica, kaolin, in the case of forming a coating layer by parsley, etc. site), obtained ultraviolet absorbing effect by simply coating It is done.
ii) Even if the coating material itself does not absorb ultraviolet rays (Al ₂ O ₃ , SiO _2, etc.), the organic, cinnamic acid, paraaminobenzoic acid, camphor, benzophenone, and benzoylmethane ultraviolet absorption An ultraviolet absorption effect can be obtained by further laminating substances and the like.

  Further, the coating layer is preferably continuous without pinholes or cracks in order to obtain sufficient moisture resistance and ion barrier properties. Such a coating layer can be formed by using a liquid phase synthesis method such as a sol-gel method, a precipitation method, etc., but a CVD method using a fluidized bed, a stirring bed, a vibrating bed, a rolling bed, etc., plasma More preferably, it is formed by a CVD method, a sputtering method, a mechanofusion method, or the like.

The coating layer in the present invention can be formed by the following method, for example.
As a first method of forming the coating layer, there is a method of forming the coating layer by supplying the raw material of the coating layer and depositing or reacting on the particle surface in a state where the phosphor particle core particles are fluidized.

The fluidization of the phosphor particle core particles can be performed by appropriately adopting a known method, and examples thereof include a method using a fluidized bed, a stirring bed, a vibrating bed, and a rolling bed. For example, as shown in FIG. 1, the fluidized bed fills a cylindrical container with phosphor particle core particles, and floats and fluidizes the phosphor particle core particles filled with the carrier gas introduced through the perforated plate from the bottom of the container. The stirring bed is a method of directly fluidizing the filled phosphor particle core particles with an impeller stirrer, etc. as shown in FIG. 2, for example. The vibrating bed is a container as shown in FIG. Is a method of mechanically or electrically oscillating the phosphor particles core particles filled in the container, and the rolling bed is an EL filled in a cylindrical container installed in a horizontal or inclined position, for example, as shown in FIG.
In this method, phosphor core particles are fluidized by rotating a cylindrical container.

In particular, in order to obtain a uniform and continuous coating layer, it is preferable to use a fluidized bed. Here, when the phosphor particle size becomes small, the tendency to aggregate becomes strong and fluidization becomes difficult. Therefore, a fluidization accelerator having a particle size larger than that of the phosphor particle core particle is added to the phosphor particle core particle. It is preferable to do. The particle size of the fluidization accelerator is preferably about 2 to 5 times the average particle size of the phosphor particle core particles. The fluidization accelerator is preferably a substance that is inactive at the reaction temperature with the phosphor particles. For example, SiO ₂ , Al ₂ O ₃ , ZrO ₂ , etc. can be preferably used.
The shape of the fluidization accelerator is preferably a spherical shape having the best fluidity.

  The supply and reaction of the coating layer material to the surface of the fluidized phosphor particle core particle is performed by, for example, containing the gaseous coating layer raw material in the carrier gas and introducing the reaction gas and the particle surface introduced by the same route or another route. A reaction method can be used. At this time, the coating layer can also be formed by pyrolyzing the gaseous coating layer raw material without using the reaction gas. As the raw material for the coating layer, alkoxides, alkyl compounds, chlorides, hydrides, hydrocarbons, and the like can be used. The temperature of each reactor is usually in the range of about 100 to 500 ° C., but in order to reduce thermal damage to the phosphor particles, the temperature is preferably 300 ° C. or lower. It is also preferable to supply the liquid coating layer raw material to the fluidized bed by spraying or the like.

A coating layer of oxide, nitride, hydroxide, diamond-like carbon, or the like can be formed by the above method. For example, vaporized by bubbling TiCl ₄ solution with N ₂ gas, it is possible to form a TiO ₂ precursor coating layer by reacting with N ₂ gas and a phosphor grain nuclei particle surfaces containing water vapor, alkyl An AlN coating layer can be formed by a reaction between aluminum and anhydrous ammonia gas.

As a second method of forming the coating layer, there is a method of forming the coating layer by supplying the raw material of the coating layer and depositing or reacting on the particle surface in a state where the phosphor particle core particles are dispersed in the solvent. It is done.
In this method, phosphor particle core particles can be introduced into a reaction vessel together with a solvent and dispersed using an impeller stirrer or the like. The reaction vessel is preferably cylindrical and the bottom of the vessel is preferably conical or hemispherical. As the shape of the stirring blade, a screw type, a twisted blade type, a paddle type, or the like can be used, but it is more preferable to use a screw-paddle composite type that can form a stirring flow in a direction perpendicular to the circumferential direction of the stirring shaft. As shown in FIG. 5, it is preferable to provide a strainer around the stirring blade to form a stronger stirring flow in the vertical direction. Moreover, as a solvent, water, an organic solvent, or mixtures thereof can be used preferably. As a special solvent, urea melted by heating to the melting point or higher can also be used. Furthermore, it is also preferable to add a dispersing agent such as a surfactant in the solvent.

  The formation of the coating layer in the solvent is a method of forming the coating layer on the particle surface by dissolving the coating layer raw material in the solvent in which the phosphor particle core particles are dispersed and adding the reaction solution therein, or A method of simultaneously adding the coating layer raw material solution and the reaction solution to the solvent in which the phosphor particle core particles are dispersed can be preferably used. At this time, it is preferable to add the coating layer raw material solution and the reaction solution to a region where stirring is most intensely performed. As a method for adding the coating layer raw material solution and the reaction solution, known metering pumps and orifice additions can be used, but it is preferable to use a syringe pump with little pulsation of liquid feeding. In addition of the coating layer raw material solution and the reaction solution, it is preferable to individually control the addition rate of each solution by detecting the ion concentration in the reaction vessel. When the solvent is urea, the reactant is not limited to a solution, and can be added as a solid.

  The reaction temperature can be controlled by directly heating the reaction vessel with a mantle heater or the like. However, it is preferable to control the reaction temperature by providing a jacket around the reaction vessel and supplying hot water or cold water. . The reaction temperature is preferably in the range of 40 to 80 ° C. when the solvent is water or an organic solvent, and is preferably in the range of 130 to 150 ° C. in the case of urea. These are all reactions under normal pressure, but it is also preferable to react under pressure by using an autoclave from the viewpoint of densification of the coating layer and promotion of decomposition / condensation reaction. In this case, the reaction temperature can exceed 100 ° C. up to the critical temperature. The addition of the solution into the autoclave is preferably performed using a liquid feed pump having a pressure resistance equal to or higher than the autoclave internal pressure.

A coating layer of oxide, hydroxide, phosphate, fluoride, or the like can be formed by the above method. For example, phosphor particles are dispersed in an alcohol solution of titanium alkoxide, and water diluted with alcohol as a reaction solution is added about 10 times as much as titanium alkoxide, so that the TiO ₂ precursor coating layer is formed on the phosphor particle core particle surface. Can be formed. Further, by dispersing phosphor particles in an aqueous Na ₃ (PO ₄ ) solution and adding an aqueous MgCl ₂ solution as a reaction solution, an Mg ₃ (PO ₄ ) ₂ coating layer can be formed on the surface of the phosphor particle core particles, and Mg ( By dispersing phosphor particles in a CH ₃ COO) ₂ alcohol solution and adding CF ₃ COOH diluted with alcohol as a reaction solution, an MgF ₂ coating layer can be formed on the surface of the phosphor particle core particles.

  In the two coating layer forming methods, it is also preferable to anneal after the forming process. When the hydroxide is partially formed, it can be almost completely converted to the oxide by annealing, and the denseness of the coating layer is improved, so that the moisture resistance and the ion barrier property are improved.

As a third method of forming the coating layer, there is a method of forming a coating layer by applying mechanical thermal energy in a state where the phosphor particle core particles and the coating layer material are mixed.
The coating layer material can be solidified on the surface of the phosphor particle core particle by receiving mechanical thermal energy due to impact or friction. As a device for applying such mechanical thermal energy, a hybridizer, a sheeter composer, or the like can be preferably used. The coating material is preferably an organic compound such as a polymer resin, but can also be an inorganic compound. It is also preferable to form a coating layer of an organic compound and then to multilayer the coating layer of an inorganic compound or to coat with a mixture of an organic compound and an inorganic compound.

The phosphor layer can be formed by applying a phosphor particle-containing coating solution. The phosphor particle-containing coating solution is a coating solution containing at least phosphor particles, a binder, and a solvent that dissolves the binder. As the binder, it is preferable to use a polymer having a relatively high dielectric constant, such as a cyanoethyl cellulose resin, or a resin such as polyethylene, polypropylene, polystyrene resin, silicone resin, epoxy resin, or vinylidene fluoride. The dielectric constant can be adjusted by mixing fine particles having a high dielectric constant such as BaTiO ₃ or SrTiO _{3 in} these binders in an amount of 5 to 50 parts by mass with respect to 100 parts by mass of the binder. As a dispersion method, a homogenizer, a planetary kneader, a roll kneader, an ultrasonic disperser, or the like can be used. As the solvent, any solvent having high polarity can be used without limitation, and alcohols, ketones, esters, polyhydric alcohols and derivatives thereof, plasticizers, and the like can be preferably used.

  The viscosity of the phosphor particle-containing coating solution is preferably in the range of 0.1 Pa · s to 5 Pa · s, particularly preferably in the range of 0.3 Pa · s to 1.0 Pa · s. If the viscosity of the phosphor particle-containing coating solution is within the above-mentioned range, coating film thickness unevenness is unlikely to occur, and phosphor particles do not separate and settle over time after dispersion. Is also possible and preferred. The viscosity is a value measured at 16 ° C. which is the same as the coating temperature.

Using a slide coater or an extrusion coater, the phosphor layer is continuously formed on a plastic support provided with a transparent electrode so that the dry film thickness of the coating film is in the range of 0.5 μm to 30 μm. It is preferable to apply to. At this time, the film thickness variation of the phosphor layer is preferably 12.5% or less, particularly preferably 5% or less.
When the phosphor layer is thinned, the voltage applied to the phosphor layer is higher than that in the case where the phosphor layer is thick like a conventional EL element under the same driving conditions, and thus the luminance is increased. In the case of driving with a luminance comparable to that of a conventional EL element, the driving voltage and frequency can be lowered, so that power consumption is reduced and vibration and noise can be further improved. In order to obtain such an effect, the thickness of the phosphor layer is preferably in the range of 0.5 to 70 μm, more preferably 10 to 60 μm.

  As described above, the phosphor particles used in the present invention are preferably particles having an average particle size in the range of 0.1 μm to 20 μm. Within this range, even when the phosphor layer is 30 μm or less, the layer can be formed uniformly, which is preferable. Moreover, although there is no restriction | limiting in the filling rate of the fluorescent substance particle in a fluorescent substance layer, Preferably it is the range of 60 to 95 mass%, More preferably, it is the range of 70 to 90 mass%. In one embodiment of the present invention, by setting the particle size of the phosphor particles to 20 μm or less, the uniformity of the coating film thickness of the phosphor layer is improved, and the smoothness of the coating film surface is simultaneously improved. Furthermore, when the number of particles per unit area is greatly increased, fine light emission unevenness can be remarkably improved. Furthermore, the decrease in the particle size leads to an increase in the voltage applied to the phosphor particles, which is preferable for improving the luminance of the EL element in combination with an increase in the electric field strength to the phosphor layer due to the thin phosphor layer. It is also preferable for suppressing causative vibrations.

<Electrode>
As the transparent electrode used in the EL device of the present invention, an electrode formed using any commonly used transparent electrode material is used. Examples of transparent electrode materials include oxides such as tin-doped tin oxide, antimony-doped tin oxide and zinc-doped tin oxide, multilayer structures in which a silver thin film is sandwiched between high refractive index layers, and π-conjugated polymers such as polyaniline and polypyrrole. Etc. It is also preferable to improve the conductivity by arranging a comb-shaped or grid-shaped fine metal wire on the transparent electrode.
The specific resistivity of the transparent electrode is preferably in the range of 0.01Ω / □ to 30Ω / □.
The back electrode is the side from which light is not extracted, and any conductive material can be used. For example, it can be selected from metal such as gold, silver, platinum, copper, iron, aluminum, graphite, and the like according to the form of the element to be created, the temperature of the creation process, and the like. A transparent electrode such as ITO may be used as long as it is conductive.
Further, both the transparent electrode and the back electrode can be prepared by preparing a conductive material-containing coating solution in which the conductive fine particle material is dispersed together with a binder, and applying the coating solution using a slide coater or an extrusion coater.

<Others>
In addition, in the element configuration of the present invention, various protective layers, filter layers, light scattering reflection layers, and the like can be provided as necessary.
In the EL device of the present invention, it is preferable to dispose a transparent electrode on a support. As a support that can be used in this case, any support that is flexible and highly transparent can be used without limitation. Preferred are plastic films such as PET (polyethylene terephthalate), PES (polyethersulfone), PAr (polyarylate), PC (polycarbonate), and PEN (polyethylene naphthalate).

  Each functional layer coated on the support is preferably formed as a continuous process from at least the coating to the drying process. The drying process is divided into a constant rate drying process until the coating film is dried and solidified, and a decreasing rate drying process for reducing the residual solvent of the coating film. In the present invention, since the binder ratio of each functional layer is high, when rapidly dried, only the surface is dried and convection occurs in the coating film, so-called Benard cell is likely to occur, and blister failure is caused by rapid solvent expansion. It tends to occur and remarkably impairs the uniformity of the coating film. On the other hand, if the final drying temperature is low, the solvent remains in each functional layer, which affects the subsequent process of forming EL elements such as a moisture-proof film laminating process. Therefore, it is preferable that the drying step is performed slowly at a constant rate drying step and performed at a temperature sufficient for the solvent to dry. As a method for slowly performing the constant rate drying step, it is preferable to divide the drying chamber in which the support travels into several zones and increase the drying temperature after the coating step in a stepwise manner.

  In the manufacture of the EL device of the present invention, the phosphor layer may be subjected to a calendar process using a calendar processor. The smoothness of both main surfaces of the phosphor layer formed by calendering is preferably in the range of 0.5 μm or less, and more preferably 0.2 μm or less. The calendar processing machine to be used is not particularly limited, and can be appropriately selected from known apparatuses. A smoothing treatment is performed by passing a phosphor layer in which phosphor particles are dispersed in a binder while applying pressure between a pair of rolls heated at least one of, for example, 50 ° C to 200 ° C. is there. In the calendering process, it is preferable that the heating temperature of the calender roll is equal to or higher than the softening temperature of the binder contained in the phosphor layer. In addition, the calender pressure and the conveyance speed are not limited to the necessary smoothness, taking into account the calender temperature and the coating width of the phosphor layer so as not to destroy the phosphor particles or extend the phosphor layer more than necessary. It is preferable to select appropriately so that it may be obtained.

  The conductive material described above can also be used when a compensation electrode is provided to suppress vibration of the EL element. For example, when a compensation electrode is provided outside the transparent electrode from which light is extracted, an oxide such as tin-doped tin oxide, antimony-doped tin oxide, or zinc-doped tin oxide, and a multilayer structure in which a thin film of silver is sandwiched between high refractive index layers It is preferable to use transparent electrode materials such as π-conjugated polymers such as polyaniline and polypyrrole.

  In addition, when a compensation electrode is provided outside the back electrode from which light is not extracted, any conductive material such as metal such as gold, silver, platinum, copper, iron, aluminum, graphite, etc. can be used. A transparent electrode such as ITO may be used as long as it has the property. The compensation electrode is attached to the transparent electrode or the back electrode via an insulating layer. The insulating layer material is an insulating inorganic material or polymer material, a dispersion liquid in which inorganic material powder is dispersed in a polymer material, or the like. Can be formed by vapor deposition, coating, or the like. Alternatively, a conductive material-containing coating solution in which the conductive fine particle material is dispersed together with a binder can be prepared and applied using a slide coater or an extrusion coater. Furthermore, an insulating material-containing coating solution in which the insulating material is dispersed together with a binder can be prepared and applied simultaneously with the conductive material-containing coating solution. A voltage is applied to the compensation electrode provided from the drive power supply. At this time, the vibration generated in the phosphor layer can be canceled by setting the phase opposite to the voltage applied to the phosphor layer. The compensation electrode has the same effect even if it is attached to either the outside of the transparent electrode or the outside of the back electrode with an insulating layer sandwiched between them. It is preferable because it is possible. In order to effectively suppress vibration, it is preferable to adjust the dielectric constant of the phosphor layer (and the dielectric layer) and the dielectric constant of the insulating layer inside the compensation electrode to be substantially equal.

  As another method for suppressing vibration of the EL element, when a buffer material layer used for the EL element is provided, a polymer material having a high shock absorbing capacity or a polymer material foamed by adding a foaming agent as the buffer material layer Is preferably used. Examples of polymer materials with high impact absorption include natural rubber, styrene butadiene rubber, polyisoprene rubber, polybutadiene rubber, nitrile rubber, chloroprene rubber, butyl rubber, hyperon, silicon rubber, urethane rubber, ethylene propylene rubber, and fluorine rubber. Can be used. The hardness of these polymer materials is preferably 50 or less, more preferably 30 or less, from the viewpoint of vibration absorption ability. In addition, butyl rubber, silicon rubber, fluorine rubber, and the like are more preferable because they have low water absorption and function as a protective film that protects the EL element from moisture. It is also preferable to use as a buffer material a material obtained by adding a foaming agent to the above rubber material, polypropylene, polystyrene, or polyethylene resin. The buffer material layer using these buffer materials can be attached by adhering the buffer material layer to the EL element with an adhesive, but the buffer material is dissolved in a solvent to prepare a buffer material-containing coating solution, It can also apply | coat using a slide coater or an extrusion coater. Although the thickness of the buffer material layer depends on the hardness of the polymer material, it needs to be 20 μm or more and preferably 50 μm or more in order to sufficiently absorb vibration. When the thickness is 200 μm or more, the thickness of the element is greatly increased, which is not preferable in terms of mass and flexibility. Further, the combined use of the compensation electrode and the buffer material layer is preferable because vibration can be further suppressed.

It is preferable that the dispersion type EL element of the present invention is finally processed using a sealing film so as to eliminate the influence of humidity and oxygen from the external environment. Sealing film for sealing the EL element is preferably not more than the water vapor transmission rate of 0.05g ^/ m 2 ^/ day at 40 ° C. -90% RH, more preferably at most 0.01g ^/ m 2 ^/ day. Further, the oxygen permeability at 40 ° C. to 90% RH is preferably 0.1 cm ³ / m ² / day / atm or less, more preferably 0.01 cm ³ / m ² / day / atm or less. As such a sealing film, a laminated film of an organic film and an inorganic film is preferably used.
As the material for forming the organic film, polyethylene resins, polypropylene resins, polycarbonate resins, polyvinyl alcohol resins and the like are preferably used, and polyvinyl alcohol resins can be more preferably used. Since polyvinyl alcohol resins and the like have water absorption properties, it is more preferable to use a resin that has been dried in advance by a treatment such as vacuum heating. An inorganic film is deposited by vapor deposition, sputtering, CVD, or the like on these resins processed into a sheet by a method such as coating. As the inorganic film to be deposited, silicon oxide, silicon nitride, silicon oxynitride, silicon oxide / aluminum oxide, aluminum nitride, or the like is preferably used, and silicon oxide is particularly preferably used. In order to obtain a lower water vapor transmission rate and oxygen transmission rate, and to prevent the inorganic film from cracking due to bending, etc., the formation of the organic film and the inorganic film is repeated, or the organic film on which the inorganic film is deposited is attached to the adhesive layer. It is preferable that a plurality of sheets are laminated to form a multilayer film. The film thickness of the organic film is preferably in the range of 5 μm to 300 μm, more preferably in the range of 10 μm to 200 μm. The thickness of the inorganic film is preferably in the range of 10 nm to 300 nm, and more preferably in the range of 20 nm to 200 nm. The thickness of the laminated sealing film is preferably in the range of 30 μm to 1000 μm, and more preferably in the range of 50 μm to 300 μm. For example, in order to obtain a sealing film having a water vapor transmission rate of 0.05 g / m ² / day or less at 40 ° C.-90% RH, the structure in which the organic film and the inorganic film are stacked in two layers is 50. A film thickness of ˜100 μm is sufficient, but polychlorinated ethylene trifluoride conventionally used as a sealing film requires a film thickness of 200 μm or more. The thinner the sealing film, the better in terms of light transmission and device flexibility.

  When sealing an EL cell with this sealing film, even if the EL cell is sandwiched between two sealing films and the periphery is adhesively sealed, the sealing film overlaps by folding one sealing film in half The part may be adhesively sealed. As the EL cell sealed with the sealing film, only the EL cell may be separately prepared, or the EL cell may be directly formed on the sealing film. In this case, the support can be replaced. The sealing step is preferably performed in a dry atmosphere with vacuum or dew point management.

  Even when an advanced sealing process is performed, it is preferable to dispose a desiccant layer around the EL cell. As the desiccant used in the desiccant layer, alkaline earth metal oxides such as CaO, SrO and BaO, aluminum oxide, zeolite, activated carbon, silica gel, paper and highly hygroscopic resin are preferably used. An earth metal oxide is more preferable in terms of moisture absorption performance. These hygroscopic agents can also be used in the form of powder, but for example, a material that is mixed with a resin material and processed into a sheet by application or molding, or a coating liquid mixed with a resin material is dispensed It is preferable to dispose the desiccant layer by applying it around the EL element. Furthermore, it is more preferable to cover not only the periphery of the EL cell but also the lower and upper surfaces of the EL cell with a desiccant. In this case, it is preferable to select a highly transparent desiccant layer for the light extraction surface. As the highly transparent desiccant layer, a polyamide-based resin or the like can be used.

  Hereinafter, the EL element of the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

“Preparation of EL device by conventional technology” (Comparative Example 1-1)
A solution obtained by dispersing fine particles of BaTiO ₃ having an average particle size of 0.2 μm in a 30% by mass cyanoethyl cellulose solution was applied onto an aluminum sheet having a thickness of 30 μm and dried at 110 ° C. for 5 hours. An aluminum sheet on which a dielectric layer was formed was obtained. Subsequently, zinc sulfide particles activated with copper and chlorine having an average particle size of 15 μm and a 30% by mass cyanoethyl cellulose solution were mixed and dispersed at a ratio of 1.2: 1, and further, a red pigment (Sinloi FA) -001) is added and dispersed in 3% by mass with respect to zinc sulfide particles, and is applied on the aluminum sheet on which the above-mentioned dielectric layer is formed so that the final layer thickness is 45 μm. The pigment-containing phosphor layer was formed by drying at 110 ° C. for 5 hours.
A film in which ITO is uniformly attached to a thickness of 40 nm by sputtering on polyethylene terephthalate having a thickness of 100 microns is produced, and this ITO surface and the surface on which the pigment-containing phosphor layer of the aluminum sheet is formed are thermocompression bonded. A lead piece was placed and sealed with a moisture-proof film to obtain an EL element of Comparative Example 1-1.

“Creation of EL device by conventional technology” (Comparative Example 1-2)
An EL device of Comparative Example 1-2 was obtained in the same manner as Comparative Example 1 except that the red pigment was changed to Sinloich FA-007.

“Preparation of EL element by conventional technology” (Comparative Example 1-3)
A solution obtained by dispersing fine particles of BaTiO ₃ having an average particle size of 0.2 μm in a 30% by mass cyanoethyl cellulose solution was applied onto an aluminum sheet having a thickness of 20 μm and dried at 110 ° C. for 5 hours. An aluminum sheet on which a dielectric layer was formed was obtained. Subsequently, fine particles of BaTiO ₃ having an average particle size of 0.2 μm were dispersed in a 30% by mass cyanoethyl cellulose solution, and a red pigment (Sinloi FA-007) manufactured by Sinloi Co. was added to this dispersion to 8% of the mass of BaTiO _3. Then, it was applied to the aluminum sheet on which the above-mentioned dielectric layer was formed so that the final layer thickness was 10 μm, and dried again at 110 ° C. for 5 hours to form a pigment-containing dielectric layer. Subsequently, zinc sulfide particles activated with copper and chlorine having an average particle size of 15 μm and 30% by mass of cyanoethyl cellulose solution were mixed and dispersed at a ratio of 1.2: 1, and a red pigment (FA-007) was further added. 3% by mass is added to and dispersed in the zinc sulfide particles, applied onto the aluminum sheet on which the above-mentioned pigment-containing dielectric layer is formed so that the final layer thickness is 45 μm, and 110 mm using a hot air dryer. The pigment-containing phosphor layer was formed by drying at 5 ° C. for 5 hours.
A film in which ITO is uniformly attached to a thickness of 40 nm by sputtering on polyethylene terephthalate having a thickness of 100 microns is produced, and this ITO surface and the surface on which the pigment-containing phosphor layer of the aluminum sheet is formed are thermocompression bonded. Then, the lead piece was placed and sealed with a moisture-proof film to obtain an EL element of Comparative Example 1-3.

“Creation of EL device according to the present invention (1-I)”
A solution obtained by dispersing fine particles of BaTiO ₃ having an average particle size of 0.2 μm in a 30% by mass cyanoethyl cellulose solution was applied onto an aluminum sheet having a thickness of 20 μm and dried at 110 ° C. for 5 hours. An aluminum sheet on which a dielectric layer was formed was obtained. Subsequently, fine particles of BaTiO ₃ having an average particle size of 0.2 μm were dispersed in a 30% by mass cyanoethyl cellulose solution, and a red pigment (Sinloi FA-007) manufactured by Sinloi Co. was added to this dispersion to 8% of the mass of BaTiO _3. Then, it was applied to the aluminum sheet on which the above-mentioned dielectric layer was formed so that the final layer thickness was 10 μm, and dried again at 110 ° C. for 5 hours to form a pigment-containing dielectric layer. Further, after mixing and dispersing zinc sulfide particles activated with copper and chlorine having an average particle size of 15 μm and a 30% by mass cyanoethyl cellulose solution in a ratio of 1.2: 1, a pigment-containing dielectric layer is formed. The phosphor layer was applied to an aluminum sheet so that the thickness of the phosphor layer became 45 μm, and dried at 110 ° C. for 5 hours using a hot air dryer to form a phosphor layer.
A film in which ITO is uniformly adhered to a thickness of 40 nm on a polyethylene terephthalate having a thickness of 100 microns is produced by sputtering, and the ITO surface and the surface on which the phosphor layer of the aluminum sheet is formed are thermocompression bonded. The piece was placed and sealed with a moisture-proof film to obtain an EL element (1-I) according to the present invention.

“Preparation of EL device according to the present invention (1-II)”
A solution obtained by dispersing fine particles of BaTiO ₃ having an average particle size of 0.2 μm in a 30% by mass cyanoethyl cellulose solution was applied onto an aluminum sheet having a thickness of 20 μm and dried at 110 ° C. for 5 hours. An aluminum sheet on which a dielectric layer was formed was obtained. Subsequently, BaTiO ₃ fine particles having an average particle size of 0.2 μm are dispersed in a 30% by mass cyanoethyl cellulose solution, and a red pigment having an emission at 620 nm is further dispersed in this dispersion so that the mass becomes 6% of the mass of BaTiO ₃ . Addition and dispersion were applied to the aluminum sheet on which the above-mentioned dielectric layer was formed so that the final layer thickness was 10 μm and dried again at 110 ° C. for 5 hours to form a pigment-containing dielectric layer. Further, after mixing and dispersing zinc sulfide particles activated with copper and chlorine having an average particle size of 15 μm and a 30% by mass of cyanoethyl cellulose solution in a ratio of 1.2: 1, aluminum having a pigment-containing dielectric layer formed thereon. It was applied to the sheet so that the finished layer thickness was 45 μm, and dried at 110 ° C. for 5 hours using a hot air dryer to form a phosphor layer.
A film in which ITO is uniformly adhered to a thickness of 40 nm on a polyethylene terephthalate having a thickness of 100 microns is produced by sputtering, and the ITO surface and the surface on which the phosphor layer of the aluminum sheet is formed are thermocompression bonded. The piece was placed and sealed with a moisture-proof film to obtain an EL element (1-II) according to the present invention.

“Preparation of EL device according to the present invention (1-III)”
Except that Lumogen F Red 200 (manufactured by BASF) was used as a red light emitting material instead of the red pigment so as to be 5% of the mass of BaTiO ₃ , it was the same as the production of the EL device of the present invention (1-II). Thus, an EL device (1-III) according to the present invention was obtained.

“Production of EL device according to the present invention (1-IV)”
BaTiO ₃ fine particles having an average particle size of 0.2 μm are dispersed in a 30% by mass cyanoethyl cellulose solution, and a red pigment having a light emission at 620 nm is added to and dispersed in this dispersion so as to be 6% of the mass of BaTiO _3. The solution was coated on a 75 μm thick aluminum sheet so that the layer thickness was 15 μm, and dried at 110 ° C. for 5 hours to obtain an aluminum sheet on which a pigment-containing dielectric layer was formed. Further, after mixing and dispersing zinc sulfide particles activated with copper and chlorine having an average particle size of 15 μm and a 30% by mass of cyanoethyl cellulose solution in a ratio of 1.2: 1, aluminum having a pigment-containing dielectric layer formed thereon. It was applied to the sheet so that the finished layer thickness was 45 μm, and dried at 110 ° C. for 5 hours using a hot air dryer to form a phosphor layer.
A film in which ITO is uniformly adhered to a thickness of 40 nm on a polyethylene terephthalate having a thickness of 100 microns is produced by sputtering, and the ITO surface and the surface on which the phosphor layer of the aluminum sheet is formed are thermocompression bonded. The EL element (1-IV) according to the present invention was obtained by mounting the piece and sealing it with a moisture-proof film.

“Creation of EL device according to the present invention (1-V)”
A solution obtained by dispersing fine particles of BaTiO ₃ having an average particle size of 0.5 μm in a 30% by mass cyanoethyl cellulose solution was applied on an aluminum sheet having a thickness of 15 μm and dried at 110 ° C. for 5 hours. An aluminum sheet on which a dielectric layer was formed was obtained. Subsequently, BaTiO ₃ fine particles having an average particle size of 0.5 μm are dispersed in a 30% by mass cyanoethyl cellulose solution, and a red pigment having light emission at 610 nm is 2.8% of the mass of BaTiO ₃ in this dispersion. Then, it was applied to the aluminum sheet on which the above-mentioned dielectric layer was formed so as to have a finished layer thickness of 15 μm and dried again at 110 ° C. for 5 hours to form a pigment-containing dielectric layer. Further, after mixing and dispersing zinc sulfide particles activated with copper and chlorine having an average particle size of 15 μm and a 30% by mass of cyanoethyl cellulose solution in a ratio of 1.2: 1, aluminum having a pigment-containing dielectric layer formed thereon. It was applied to the sheet so that the finished layer thickness was 45 μm, and dried at 110 ° C. for 5 hours using a hot air dryer to form a phosphor layer.
A film in which ITO is uniformly adhered to a thickness of 40 nm on a polyethylene terephthalate having a thickness of 100 microns is produced by sputtering, and the ITO surface and the surface on which the phosphor layer of the aluminum sheet is formed are thermocompression bonded. The piece was placed and sealed with a moisture-proof film to obtain an EL element (1-V) according to the present invention.

“Creation of EL device according to the present invention (1-VI)”
A solution obtained by dispersing fine particles of BaTiO ₃ having an average particle size of 0.5 μm in a 30% by mass cyanoethyl cellulose solution was applied onto an aluminum sheet having a thickness of 10 μm and dried at 110 ° C. for 5 hours. An aluminum sheet on which a dielectric layer was formed was obtained. Subsequently, BaTiO ₃ fine particles having an average particle size of 0.5 μm are dispersed in a 30% by mass cyanoethyl cellulose solution, and a red pigment having light emission at 610 nm is further added to this dispersion to 0.8% of the mass of BaTiO _3. Then, the mixture was applied and dispersed in such a manner that it was applied to the aluminum sheet on which the above-mentioned dielectric layer was formed so that the final layer thickness was 20 μm, and dried again at 110 ° C. for 5 hours to form a pigment-containing dielectric layer. Further, after mixing and dispersing zinc sulfide particles activated with copper and chlorine having an average particle size of 15 μm and a 30% by mass of cyanoethyl cellulose solution in a ratio of 1.2: 1, aluminum having a pigment-containing dielectric layer formed thereon. It was applied to the sheet so that the finished layer thickness was 45 μm, and dried at 110 ° C. for 5 hours using a hot air dryer to form a phosphor layer.
A film in which ITO is uniformly adhered to a thickness of 40 nm on a polyethylene terephthalate having a thickness of 100 microns is produced by sputtering, and the ITO surface and the surface on which the phosphor layer of the aluminum sheet is formed are thermocompression bonded. The EL element (1-VI) according to the present invention was obtained by mounting the piece and sealing it with a moisture-proof film.

“Preparation of EL device according to the present invention (1-VII)”
A solution obtained by dispersing fine particles of BaTiO ₃ having an average particle size of 0.5 μm in a 30% by mass cyanoethyl cellulose solution was applied on an aluminum sheet having a thickness of 15 μm and dried at 110 ° C. for 5 hours. An aluminum sheet on which a dielectric layer was formed was obtained. Subsequently, fine particles of BaTiO ₃ having an average particle size of 0.5 μm are dispersed in a 30% by mass cyanoethyl cellulose solution, and a red pigment having light emission at 630 nm is further dispersed in this dispersion to 6% of the mass of BaTiO ₃ . Addition and dispersion were applied to the aluminum sheet on which the above-mentioned dielectric layer was formed so that the final layer thickness was 15 μm and dried again at 110 ° C. for 5 hours to form a pigment-containing dielectric layer. Further, after mixing and dispersing zinc sulfide particles activated with copper and chlorine having an average particle size of 15 μm and a 30% by mass of cyanoethyl cellulose solution in a ratio of 1.2: 1, aluminum having a pigment-containing dielectric layer formed thereon. It was applied to the sheet so that the finished layer thickness was 45 μm, and dried at 110 ° C. for 5 hours using a hot air dryer to form a phosphor layer.
A film in which ITO is uniformly adhered to a thickness of 40 nm on a polyethylene terephthalate having a thickness of 100 microns is produced by sputtering, and the ITO surface and the surface on which the phosphor layer of the aluminum sheet is formed are thermocompression bonded. The piece was placed and sealed with a moisture-proof film to obtain an EL element (1-VII) according to the present invention.

  Table 1 shows the color rendering properties of the EL element of the present invention prepared as described above and the EL element of the comparative example when light is emitted at 100 V and 1 kHz.

  In Comparative Examples 1-1 to 1-3 and EL elements (1-I) to (1-VII) of the present invention, the emission color was white. It can be seen that the average color rendering index Ra of the EL element of the present invention is superior to the EL element of the comparative example, which is a conventional type, and particularly excellent in red color rendering R9. It can also be seen that the skin color rendering R15 is greatly improved in the EL device of the present invention. R15 cannot be expressed well if the color rendering property R9 of red is poor, and is an important factor when observing a transmission medium such as a transparent positive image on an EL element.

Each phosphor particle of Example 1 was provided with a coating layer of Al ₂ O ₃ using a fluidized bed reactor using trimethylaluminum as a raw material and O ₂ as a reaction gas. The layer thickness of the coating layer was 170 nm. Except for using the particles as the phosphor layer particles, each element of Example 2 was prepared in the same manner as Example 1, and the EL elements of the comparative example and the present invention were obtained.
For these EL devices, an alternating electric field of 1 kHz was applied, the voltage was adjusted so that the initial luminance was 300 cd / m ^{2 at} 25 ° C. and a relative humidity of 60%. The time was 15-20% longer. As for the change in the color rendering index, the change in the average color rendering index was about 5 in the comparative example, which was about 5, and in the present invention, about 6 was improved to 2-3.

  As described above, the electroluminescent device according to the present invention emits white light and has excellent color rendering properties, particularly red color rendering properties, and is suitable for use as a backlight or a display device.

FIG. 1 is a schematic explanatory diagram of a fluidized bed reactor for forming a coating layer on phosphor particles. FIG. 2 is a schematic explanatory diagram of a stirred bed reaction apparatus for forming a coating layer on phosphor particles. FIG. 3 is a schematic explanatory view of a vibrating bed reaction apparatus for forming a coating layer on phosphor particles. FIG. 4 is a schematic explanatory diagram of a rolling bed reactor for forming a coating layer on phosphor particles. FIG. 5 is a schematic explanatory diagram of a liquid phase reaction apparatus for forming a coating layer on phosphor particles.

Claims (6)

In an electroluminescent device containing a transparent electrode, a phosphor layer, a dielectric layer and a back electrode in this order,
The dielectric layer includes dielectric particles and a color conversion material, the content ratio of the color conversion material is 0.1% by mass or more and 20% by mass or less with respect to the dielectric particles, and the thickness of the dielectric layer is 1. An electroluminescent element characterized by being 1 μm or more and 20 μm or less. In an electroluminescent device containing a transparent electrode, a phosphor layer, a dielectric layer and a back electrode in this order,
The electroluminescent device, wherein the dielectric layer contains dielectric particles and a color conversion material, and the emission maximum wavelength of the color conversion material is 600 nm or more and 750 nm or less.   The electroluminescent device comprising a transparent electrode, a phosphor layer, a dielectric layer and a back electrode in this order, wherein the phosphor layer includes phosphor particles having a coating layer. The electroluminescent element as described.   The electroluminescent device according to claim 3, wherein the coating layer includes a material having an absorption edge at a wavelength of 280 nm to 420 nm.   It has two emission maxima in the visible range, and of these two emission maxima, it has a short wave side emission maximum in the range of 480 nm to 510 nm, a long wave side emission maximum in the range of 590 nm to 625 nm, and an emission minimum. The electroluminescent element according to claim 1, wherein the electroluminescent element has a range of 571 nm to 583 nm.   The phosphor particles include particles having an average particle size of 0.1 to 20 μm, a coefficient of variation of particle size distribution of less than 35%, and containing 10 or more layers of stacking faults with a spacing of 5 nm or less. The electroluminescent element according to claim 3, wherein the electroluminescent element is a ZnS-based electroluminescent phosphor having 30% by volume or more.

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