JP5824944B2 - Dispersion type inorganic electroluminescence device - Google Patents

Description

  The present invention relates to a dispersion-type inorganic electroluminescence element.

  Electroluminescence elements (hereinafter also referred to as EL elements) are light-emitting devices using electroluminescence such as solid fluorescent materials, and are roughly classified into inorganic EL elements composed of inorganic substances and organic EL elements composed of organic substances. The Inorganic EL elements are divided into a dispersion-type inorganic EL element in which phosphor powder is dispersed in a resin and a thin-film inorganic EL element in which a phosphor thin film is sandwiched between insulator layers. The present invention relates to a dispersion-type inorganic EL element.

  A dispersion-type inorganic EL element is a fluorescent material comprising a phosphor powder in a high dielectric constant polymer such as a polymer having a fluorinated rubber or a cyano group between a pair of light-transmitting conductive electrode sheets. An element with a body layer. Further, in order to prevent dielectric breakdown, it is a normal form that an insulator layer comprising a high dielectric constant powder such as barium titanate is placed in a high dielectric constant polymer.

  Dispersion-type inorganic EL elements do not use a high-temperature process at the time of element configuration, so that a flexible material structure using a plastic substrate is possible, a relatively simple process without using a vacuum device, and low cost. It has the feature that it can be manufactured and that the emission color of the element can be easily adjusted by mixing a plurality of phosphor powders having different emission colors, and is applied to backlights and display elements. However, the light emission brightness is low and the light emission lifetime is short, so that many of them have a limited application range. Further, the luminous efficiency is low, and when the luminous brightness is increased, problems of heat generation and power consumption increase become apparent, and further improvements in luminous brightness and luminous efficiency are desired.

In addition, as a phosphor material used for an inorganic EL element, a material in which zinc sulfide (ZnS) is used as a parent phase and Cu, Ag, Mn, trivalent rare earth or the like is added as an activator is often used. In recent years, barium thioaluminate (BaAl ₂ S ₄ : Eu) is used as a blue light emitter, strontium thiogallate (SrGa ₂ S ₄ : Eu) is used as a green light emitter, and calcium sulfide (CaS: Eu) is used as a red light emitter. It has come to be used. However, since these phosphor materials use sulfide as a matrix, they are poor in moisture resistance and require moisture-proof treatment such as the formation of a surface protective layer, and are excellent in moisture resistance and durability. An inorganic EL element using a phosphor is desired.

The following efforts have been made from the element structure to improve the efficiency of the dispersion-type inorganic EL element. The dispersion-type inorganic EL element can be considered by replacing it with a plate capacitor. That is, as shown in FIG. 1, the front electrode 2, the phosphor powder 7, the resin composition 8 in the phosphor layer, the insulator layer 4, and the back electrode 5 are laminated in this order, and there is a structure with electrodes at both ends. Think. Originally, the phosphor powder 7 is dispersed in the resin composition 8 in the phosphor layer to form a phosphor layer, and applied to each of the resin composition 8 and the phosphor powder 7 in the phosphor layer. In order to calculate the electric field strength to be calculated, it is considered separately as shown in FIG. The voltage (V) applied between the front electrode 2 and the back electrode 5, the relative dielectric constant (ε ₂ ) of the phosphor powder 7, the film thickness (d ₂ ) of the phosphor powder 7, and the electric field strength of the phosphor powder 7 (E ₂ ), relative dielectric constant (ε ₃ ) of the insulator layer 4, film thickness (d ₃ ) of the insulator layer 4, electric field strength (E ₃ ) of the insulator layer 4, and resin composition in the phosphor layer 8 having a relative dielectric constant (ε ₄ ), a film thickness (d ₄ ) of the resin composition 8 in the phosphor layer, and an electric field strength (E ₄ ) of the resin composition 8 in the phosphor layer. The electric field strength applied to the phosphor powder 7 is expressed by the following formula (1).

Therefore, when the relative dielectric constant (ε ₃ ) of the insulator layer 4 and the relative dielectric constant (ε ₄ ) of the resin composition 8 in the phosphor layer are larger than the relative dielectric constant (ε ₂ ) of the phosphor powder 7. The electric field strength (E ₂ ) applied to the phosphor powder 7 increases. Based on the above principle, an insulator layer having a dielectric constant higher than that of the phosphor powder is usually provided in order to increase the luminance of the dispersion-type inorganic EL element. A polymer having a high dielectric constant is used for the resin composition used for the phosphor layer.

  In a thin-film inorganic EL device in which a phosphor thin film is sandwiched between insulator layers, a high dielectric constant insulator layer such as barium titanate or strontium titanate can be provided, so that a large electric field is applied to the phosphor layer. it can. On the other hand, in the case of a dispersion-type inorganic EL element, the insulator layer is a layer in which barium titanate or strontium titanate powder is dispersed in a high dielectric constant polymer. Although it is a polymer having a high dielectric constant, its relative dielectric constant is less than 20, and in general, the dielectric layer has a relative dielectric constant of less than 100.

  On the other hand, as in Patent Document 1, a thin-film inorganic EL element using a phosphor having a high dielectric constant perovskite crystal structure has been developed. As described above, in a thin-film inorganic EL element, an electric field can be concentrated on the phosphor layer by providing an insulating film having a high dielectric constant. However, in the case of a thin-film inorganic EL element, there is a problem that manufacturing equipment such as a film forming apparatus is complicated and expensive, and manufacturing cost is high. On the other hand, in the case of a dispersion-type inorganic EL element, when the relative permittivity of the phosphor powder is high, there is a problem that an electric field cannot be applied to the phosphor powder and the luminance is not improved. Is limited.

JP 2011-52159 A JP 2006-236924 A JP-A-8-288066 Japanese Patent Laid-Open No. 10-134963

  As a method for increasing the brightness in a dispersion-type inorganic EL element, Patent Document 2 discloses a structure in which an intermediate layer is provided between a phosphor layer and a front electrode. However, in the present invention, attention is paid to the properties of the intermediate layer to be introduced in terms of film thickness, transparency, conductivity, softening point, etc. However, the effect of improving the luminance of the dispersion-type inorganic EL element is small only by these factors. . Further, there is no description on how to combine the phosphor layer and the intermediate layer, and the luminance improvement rate when the intermediate layer is introduced is small.

  As an example of providing an intermediate layer between the phosphor layer and the front electrode, there is known an improvement in adhesion between layers (Patent Document 3), but the efficiency has not been studied at all. In addition, there is known a method in which an intermediate layer is formed using a thermoplastic resin having a softening point of 200 ° C. or lower (Patent Document 4). A sufficient effect cannot be obtained in the above driving).

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a high-intensity dispersed inorganic EL element.

  The present inventors have conducted detailed studies and have found that light emission with extremely high luminance can be obtained in a dispersion-type inorganic EL element having a specific element structure.

That is, the present invention provides a dispersion-type inorganic EL element in which a laminate of a phosphor layer in which phosphor powder is dispersed in a resin and an insulator layer is sandwiched between a front electrode and a back electrode. An intermediate layer is provided between the layer and the front electrode, and the ratio (ε ₁ / ε ₂ ) between the relative dielectric constant (ε ₁ ) of the intermediate layer and the relative dielectric constant (ε ₂ ) of the phosphor powder is The present invention relates to a dispersion-type inorganic electroluminescence element characterized by being 0.01 or less.

  In one aspect of the present invention, the intermediate layer has a relative dielectric constant of 2 or less.

  In one aspect of the present invention, at least a part of the intermediate layer is an air layer. In one embodiment of the present invention, the intermediate layer has a thickness of 10 nm to 30 μm. In one embodiment of the present invention, the phosphor layer has a thickness of 10 μm to 300 μm.

  One aspect of the present invention is characterized in that the phosphor layer has two or more layers, and an intermediate layer is formed between the phosphor layer and the front electrode in contact with each phosphor layer. It is a dispersion-type inorganic electroluminescence element.

  In one aspect of the present invention, the phosphor powder has a relative dielectric constant of 20 or more.

  In one aspect of the present invention, the phosphor powder has a relative dielectric constant of 160 or more.

  In one aspect of the present invention, the phosphor powder is a perovskite oxide phosphor.

  According to the present invention, a high-intensity dispersed inorganic EL element can be obtained.

It is a conceptual diagram at the time of considering a dispersion type inorganic EL element as a flat plate capacitor. It is typical sectional drawing which shows one Embodiment of the dispersion | distribution type inorganic EL element of this invention. It is typical sectional drawing which shows one Embodiment of the dispersion | distribution type inorganic EL element of this invention. FIG. 4 is a partial schematic cross-sectional view for manufacturing the dispersion-type inorganic EL element of FIG. 3. FIG. 5 is a plan view of the dielectric film 60 viewed from the xx plane of FIG. 4. FIG. 4 is a partial schematic cross-sectional view for manufacturing the dispersion-type inorganic EL element of FIG. 3. It is typical sectional drawing which shows one Embodiment of the dispersion | distribution type inorganic EL element of this invention. It is typical sectional drawing which shows one Embodiment of the dispersion | distribution type inorganic EL element of this invention. It is typical sectional drawing which shows one Embodiment of the dispersion | distribution type inorganic EL element of this invention. It is a conceptual diagram at the time of considering other embodiment of the dispersion | distribution type inorganic EL element of this invention as a flat plate capacitor. 6 is a schematic cross-sectional view showing one embodiment of a dispersion-type inorganic EL element of Comparative Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The present invention relates to a dispersion-type inorganic EL element having a specific element structure capable of obtaining light emission with extremely high luminance.

(Element structure)
One embodiment of the dispersion-type inorganic EL element of the present invention is shown in FIG. In the dispersion type inorganic EL element of the present invention, a front electrode 2, an intermediate layer 6, a phosphor layer 3, an insulator layer 4, and a back electrode 5 are laminated in this order on one side of a base film 1, and an EL display described later. A light emitting part in the apparatus is formed. That is, the dispersion-type inorganic EL element of the present invention comprises a laminate of a phosphor layer 3 and an insulator layer 4 in which phosphor powder is dispersed in resin between a front electrode 1 and a back electrode 5. The dispersion-type inorganic EL element has a structure having an intermediate layer at least between the phosphor layer and the front electrode. The dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the relative dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) is equal to or more than 0.2. With such a structure and configuration, an electric field concentrates on the intermediate layer, whereby a high-intensity dispersed inorganic EL element can be obtained. Here, the relative dielectric constant (ε ₂ ) of the phosphor powder is a relative dielectric constant when the phosphor powder is molded and sintered. The relative dielectric constant of the sintered body can be obtained from the capacitance obtained by applying an Ag paste to the upper and lower surfaces of the sintered body and using an LCR meter.

Further, the dispersion-type inorganic EL device of the present invention, the dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder (epsilon ₂₎ the ratio of (ε _{1 /} ε ₂₎ is 0.01 The following is preferable. Thereby, more electric fields can be concentrated on the intermediate layer, and a higher-intensity dispersed inorganic EL element can be obtained.

  In the dispersion-type inorganic EL element of the present invention, the intermediate layer may be an air layer. An embodiment of a dispersion-type inorganic EL element in which the intermediate layer is an air layer is shown in FIG. When the intermediate layer is an air layer, a support part for forming the intermediate layer made of the air layer is required.

  The dispersion-type inorganic EL element shown in FIG. 3 is formed as follows. First, a laminated body of a portion below the xx plane in FIG. 3 (that is, the dielectric film 60 side) is manufactured. The structure of the laminate is shown in FIG. The laminated body of FIG. 4 is obtained by forming the front electrode 2 and the dielectric film 60 on one side of the base film 1. FIG. 5 shows a plan view of the dielectric film 60 side as viewed from the xx plane of FIG. The front electrode 2 is formed only in a portion where the dielectric film 60 is not formed, and a portion surrounded by the dielectric film 60 becomes an air layer 63. Next, a layered body of a portion above the xx plane in FIG. 3 (that is, the phosphor layer 3 side) is produced. The structure of the laminate is shown in FIG. The laminated body of FIG. 6 has a back electrode 5, an insulator layer 4, a phosphor layer on one side of a base film 1 different from the base film used for producing a support for forming an intermediate layer composed of an air layer. 3 are laminated in this order. Then, as shown in FIG. 3, an element in which an intermediate layer made of an air layer is formed in the center can be manufactured by stacking the stacked bodies shown in FIGS. 4 and 6 so that the xx planes face each other.

  By adopting such a structure and configuration, the dispersion-type inorganic EL element of the present invention in which the intermediate layer is an air layer can be obtained. In this case, the relative dielectric constant of the intermediate layer is 1 which is the relative dielectric constant of air. With the structure in which the intermediate layer is an air layer as shown in FIG. 3, more electric field can be concentrated on the intermediate layer, and a higher-intensity dispersed inorganic EL element can be obtained.

  In the dispersion-type inorganic EL element of the present invention, the intermediate layer may be a composite of an air layer and a support for forming the air layer. FIG. 7 shows an embodiment of a dispersion-type inorganic EL element in which the intermediate layer includes an air layer and a support for forming the air layer. For example, the support portion can be made of the permanent resist 61 that leaves the photoresist itself as a permanent film. In this case, the relative dielectric constant of the intermediate layer is, for example, a permanent resist using an epoxy resin having a relative dielectric constant of 2.5 as a main raw material. When the sum of the areas and the sum of the cross-sectional areas in the plane parallel to the front electrode 2 of the permanent resist portion is 2 to 1, the combined relative dielectric constant of the intermediate layer is 1.5. By introducing a permanent resist using an air layer and an epoxy resin as the main raw material in the intermediate layer, it becomes possible to reduce the relative dielectric constant of the intermediate layer, and more electric field can be concentrated in the intermediate layer, A higher-intensity dispersion-type inorganic EL element can be obtained.

Glass beads can also be used as the support portion in the embodiment of FIG. FIG. 8 shows an embodiment of a dispersion-type inorganic EL element using glass beads 62 as the support portion of the embodiment of FIG. As a result, the intermediate layer is composed of the glass beads 62 and the air layer 63. Using glass beads having a relative dielectric constant of 3.1, the sum of the cross-sectional areas in the plane parallel to the front electrode 2 of the air layer part and the sum of the cross-sectional areas in the plane parallel to the front electrode 2 of the glass bead part is 2 In the case of 1: 1, the combined dielectric constant of the intermediate layer is 1.7. In the case of a glass bead that is a sphere, the cross-sectional area in the plane parallel to the front electrode 2 differs depending on the distance from the front electrode 2, so that the cut in the plane parallel to the front electrode 2 in the rectangular parallelepiped that has the same volume and the same volume. The area is determined as the cross-sectional area of the glass beads. Here, if the radius of the glass beads is r, the volume of the glass beads is 4 / 3πr ³ , and the height of the glass beads is 2r at this time. Therefore, the cross-sectional area in the plane parallel to the front electrode 2 of the rectangular parallelepiped having the same volume and height 2r, that is, the cross-sectional area in the plane parallel to the front electrode 2 of the glass beads can be obtained as 2 / 3πr ² . By introducing glass beads and an air layer into the intermediate layer, it becomes possible to make the relative dielectric constant of the intermediate layer smaller, more electric field can be concentrated in the intermediate layer, and a higher-intensity dispersed inorganic EL An element is obtained.

  In the dispersion-type inorganic EL device of the present invention, a structure having two or more phosphor layers and intermediate layers can be used. One embodiment of the dispersion-type inorganic EL device of the present invention having a structure having two phosphor layers and an intermediate layer is shown in FIG. In the present embodiment, an intermediate layer is formed between the phosphor layer and the front electrode in contact with each phosphor layer. In the case of a structure having two phosphor layers and an intermediate layer, in order to make the electric field strength applied to the intermediate layer equal to the electric field strength applied to the intermediate layer when the phosphor layer and the intermediate layer are each one layer. The thickness of the intermediate layer is halved. By adopting a structure having two phosphor layers and an intermediate layer as shown in FIG. 9, the area where the phosphor layer is in contact with the intermediate layer is tripled, and a higher-intensity dispersed inorganic EL element can be obtained.

In the dispersion-type inorganic EL element, when an intermediate layer is provided between the phosphor layer and the transparent electrode as in the present invention, the electric field strength of the intermediate layer becomes very large. That is, as shown in FIG. 10, the front electrode 2, the intermediate layer 6, the phosphor powder 7, the resin composition 8 in the phosphor layer, the insulator layer 4, and the back electrode 5 are laminated in this order. Think of a structure that has Originally, the phosphor powder 7 is dispersed in the resin composition 8 in the phosphor layer to form a phosphor layer, and applied to each of the resin composition 8 and the phosphor powder 7 in the phosphor layer. In order to calculate the electric field strength to be calculated, it is considered separately as shown in FIG. Here, the film thickness of the phosphor powder 7 and the film thickness of the resin composition 8 in the phosphor layer can be obtained as follows. When the film thickness of the phosphor layer is (d _{2 + 4} ), the volume fraction of the phosphor powder 7 in the phosphor layer is α, and the volume fraction of the resin composition 8 in the phosphor layer in the phosphor layer is β. The film thickness of the phosphor powder 7 is α · (d _{2 + 4} ), and the film thickness of the resin composition 8 in the phosphor layer is β · (d _{2 + 4} ). Subsequently, the voltage V applied between the front electrode and the back electrode, the relative dielectric constant (ε ₁ ) of the intermediate layer 6, the film thickness (d ₁ ) of the intermediate layer 6, the electric field strength (E ₁ ) of the intermediate layer 6, The relative dielectric constant (ε ₂ ) of the phosphor powder 2, the film thickness (d ₂ ) of the phosphor powder 2, the electric field strength (E ₂ ) of the phosphor powder 2, the relative dielectric constant (ε ₃ ) of the insulator layer 4, The film thickness (d ₃ ) of the insulator layer 4, the electric field strength (E ₃ ) of the insulator layer 4, the relative dielectric constant (ε ₄ ) of the resin composition 8 in the phosphor layer, and the resin composition in the phosphor layer 8 is a capacitor having a film thickness (d ₄ ) and an electric field strength (E ₄ ) of the resin composition 8 in the phosphor layer, the electric field strength applied to the intermediate layer is expressed by the following equation (2). The

For example, in the above formula (2), the voltage V = 500 V applied between the front electrode 2 and the back electrode 5, the relative dielectric constant ε ₁ = 2 of the intermediate layer 6, the film thickness d ₁ = 5 μm of the intermediate layer 6, fluorescence The relative dielectric constant ε ₂ = 240 of the body powder 7, the film thickness d ₂ of the phosphor powder 7 = 36 μm, the relative dielectric constant ε ₃ = 95 of the insulator layer 4, the film thickness d ₃ = 15 μm of the insulator layer 4, fluorescence When the relative dielectric constant ε ₄ = 15 of the resin composition 8 in the body layer and the film thickness d ₄ = 9 μm of the resin composition 8 in the phosphor layer, the electric field strength E ₁ of the intermediate layer 6 = 7.34. × 10 ⁷ V / m, electric field strength E ₂ of phosphor powder 7 = 6.11 × 10 ⁵ V / m, electric field strength E ₃ of insulator layer 4 = 1.54 × 10 ⁶ V / m, phosphor layer The electric field strength E ₄ of the resin composition 8 inside becomes 9.78 × 10 ⁶ V / m, and the electric field strength of the intermediate layer 6 becomes very large. The electric field concentrated on the intermediate layer causes a phenomenon that the phosphor powder at the interface between the intermediate layer and the phosphor layer emits light. Thereby, the phosphor powder in the phosphor layer emits light, and a high-intensity dispersed inorganic EL element is obtained.

(Middle layer)
In the present invention, the intermediate layer is a dispersion-type inorganic EL element in which a laminate of a phosphor layer in which phosphor powder is dispersed in a resin and an insulator layer is sandwiched between a front electrode and a back electrode. It is a layer that is located at least between the phosphor layer and the front electrode and is provided to concentrate the electric field. Examples of the material for the intermediate layer include organic polymer compounds or inorganic compounds, air, and the like.

  When the material forming the intermediate layer is an organic polymer compound, usable polymer compounds include polyethylene, polypropylene, polystyrene, polyesters, polycarbonates, polyamides, polyethersulfones, polyvinyl alcohol, pullulan and saccharose, Polysaccharides such as cellulose, vinyl chloride, fluororubber, polyacrylic acid esters, polymethacrylic acid esters, polyacrylic acid amides, polymethacrylic acid amides, silicone resin, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl saccharose, or Examples include an ultraviolet light curable resin obtained from a polyfunctional acrylic ester compound, and a thermosetting resin obtained from an epoxy compound or a cyanate compound.

  As a method of forming an intermediate layer with an organic polymer compound or a precursor thereof, it is dissolved in a suitable organic solvent and applied to the front electrode or the phosphor layer using a screen printing method, a spin coating method, or the like. The method of forming is mentioned.

  Examples of the organic solvent for dissolving the organic polymer compound or the precursor thereof include 1-methyl-2-pyrrolidone, dichloromethane, chloroform, acetone, methyl ethyl ketone, cyclohexanone, acetonitrile, dimethylformamide, dimethylacetamide, dimethylsulfoxide, toluene, xylene, Etc.

  When the material forming the intermediate layer is an inorganic compound, examples of the inorganic compound that can be used include silicon dioxide, other metal oxides, and metal nitrides. As a method for forming the intermediate layer with an inorganic compound, a sputtering method, a CVD method, or the like can be employed. Further, the intermediate layer of the dispersion-type inorganic EL element of the present invention preferably has a relative dielectric constant of 2 or less. According to this, it is possible to concentrate more electric field in the intermediate layer, and it is possible to obtain a dispersed inorganic EL element with higher luminance.

  Examples of the material of the intermediate layer having a relative dielectric constant of 2 or less include fluorine resin and air.

  Furthermore, in the intermediate layer of the dispersion-type inorganic EL element of the present invention, at least a part of the intermediate layer may be an air layer. By using at least a part of the intermediate layer as an air layer, more electric field can be concentrated on the intermediate layer, and a higher-intensity dispersed inorganic EL element can be obtained.

  Examples of the method of using the intermediate layer as an air layer include a method of forming a support portion around the air layer. Examples of a method for forming the support include a method of applying a permanent resist, glass beads, the organic polymer compound, or the like. In the case of applying an organic polymer compound or the like, it may be formed using a mask capable of forming a portion that becomes an air layer.

The relative dielectric constant of the intermediate layer in the case of being composed of a composite can be calculated from the ratio of the relative dielectric constant of each intermediate layer and the sum of the cross-sectional areas in the plane parallel to the front electrode of each intermediate layer. For example, if the ratio of the sum of the cross-sectional areas in the plane parallel to the front electrode of the intermediate layer A having a relative dielectric constant (ε _A ) and the intermediate layer B having a relative dielectric constant (ε _B ) is 1: 2. The relative dielectric constant is (1/3) ε _A + (2/3) ε _B.

  The film thickness of the intermediate layer of the dispersion-type inorganic EL element of the present invention is preferably 10 nm or more and 30 μm or less. When the film thickness of the intermediate layer is 10 nm or more and 30 μm or less, many electric fields can be concentrated on the intermediate layer, and a high-intensity dispersed inorganic EL element can be obtained. When the film thickness of the intermediate layer is less than 10 nm, it is difficult to control the film thickness, and when the film thickness of the intermediate layer is 30 μm or more, the brightness improvement effect is reduced.

(Phosphor layer)
The phosphor layer of the present invention uses a phosphor powder dispersed in a resin. As the resin, a polymer having a relatively high relative dielectric constant, such as a cyanoethyl cellulose resin, or a resin such as polyethylene, polypropylene, polystyrene resin, silicone resin, epoxy resin, or vinylidene fluoride can be used. The dielectric constant can be adjusted by appropriately mixing fine particles of high dielectric constant such as barium titanate (BaTiO ₃ ) and strontium titanate (SrTiO ₃ ) with these resins. As a dispersion method, a homogenizer, a planetary kneader, a roll kneader, an ultrasonic disperser, or the like can be used. A preferable amount of the phosphor powder used in the present invention is 4.2 to 20 by weight ratio with respect to the resin amount 1, and 4.5 to 10 is particularly preferable. Thereby, a high-intensity dispersed inorganic EL element is obtained. When the amount of resin is small, the phosphor powder is not dispersed and dielectric breakdown is likely to occur. When the amount of resin is large, the contact between the phosphor powder and the intermediate layer is reduced, and the luminance is lowered.

  Examples of the method for forming the phosphor layer include spin coating, dip coating, bar coating, spray coating, and screen printing. In particular, it is preferable to use a method that does not select a printing surface, such as a screen printing method, or a method that allows continuous application, such as a slide coating method. For example, in the screen printing method, a dispersion liquid in which fine particles of phosphor or dielectric are dispersed in a polymer solution having a high dielectric constant is applied through a screen mesh. The film thickness can be controlled by selecting the number of meshes, emulsion film thickness, printing speed, squeegee hardness, and number of coatings. By changing the dispersion liquid, not only the phosphor layer and the insulator layer but also the back electrode can be formed, and further, the area can be increased by changing the size of the screen.

  The film thickness of the phosphor layer of the dispersion-type inorganic EL element of the present invention is preferably 10 μm or more and 300 μm or less. When the film thickness of the intermediate layer is 10 μm or more and 300 μm or less, a large electric field can be concentrated on the intermediate layer, and a high-intensity dispersed inorganic EL element can be obtained. When the film thickness of the phosphor layer is less than 10 μm, dielectric breakdown is likely to occur, and when the film thickness of the intermediate layer is 300 μm or more, the brightness enhancement effect is reduced. In addition, the production time becomes longer.

(Phosphor powder)
Examples of the phosphor powder to be used include II-VI group sulfide phosphors, oxides, nitrides, fluoride phosphors and the like based on ZnS, CaS, SrS, etc .. And phosphors are preferred because they are excellent in moisture resistance and durability.

Furthermore, the phosphor powder of the present invention preferably has a relative dielectric constant of 20 or more. According to this, the dielectric constant of the intermediate layer (epsilon ₁₎ and the dielectric constant of the phosphor powder (epsilon ₂₎ and the ratio (ε _{1 /} ε ₂₎ can be reduced, often to the intermediate layer Thus, a higher-intensity dispersion-type inorganic EL element can be obtained.

The phosphor powder having a relative dielectric constant of 20 or more includes CaTiO ₃ : Pr ³⁺ , (Ca, Sr) TiO ₃ : Pr ³⁺ , BaTiO ₃ : Pr ³⁺ , SrTiO ₃ : Pr ³⁺ -Al ³⁺ , Sr ₂ SnO ₄ : ^{_{Ti 4+, CaSnO 3: Pr 3+}} , CaSnO 3: Tb 3+ -Mg 2+, CaZrO 3: Eu 3+, Sr 3 Sn 2 O 7: Sm 3+, Sr 2 SnO 4: such as ^Eu 3+ ^{-Ti 4+} may be cited.

Furthermore, the phosphor powder of the present invention preferably has a relative dielectric constant of 160 or more. When the specific dielectric constant is 160 or more, it is possible to further reduce the ratio (ε _{1 /} ε ₂₎ between the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder (epsilon ₂₎ In addition, more electric fields can be concentrated on the intermediate layer, and a higher-intensity dispersed inorganic EL element can be obtained.

Examples of the phosphor powder having a relative dielectric constant of 160 or more include CaTiO ₃ : Pr ³⁺ , (Ca, Sr) TiO ₃ : Pr ³⁺ , BaTiO ₃ : Pr ³⁺ , SrTiO ₃ : Pr ³⁺ -Al ^{3+ and the} like.

Furthermore, the phosphor powder of the present invention is preferably a perovskite oxide phosphor. Phosphor powder, by a perovskite-type oxide phosphor, the dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder (epsilon ₂₎ the ratio of (ε _{1 /} ε ₂₎ Can be made smaller, a large electric field can be concentrated on the intermediate layer, and a high-intensity dispersed inorganic EL element can be obtained.

The perovskite oxide phosphor ^{_{powder, CaTiO 3: Pr 3+, (}} Ca, Sr) TiO 3: Pr 3+, BaTiO 3: Pr 3+, SrTiO 3: Pr 3+ -Al 3+, CaSnO 3: Pr 3+, CaSnO 3 : Tb ³⁺ -Mg ²⁺ , CaZrO ₃ : Eu ^{3+ and the} like.

(electrode)
In the dispersion-type inorganic EL element of the present invention, any transparent electrode material that is generally used is used as the front electrode. For example, oxides such as tin-doped indium oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, and gallium-doped zinc oxide, multilayers in which a thin film such as silver is sandwiched between high refractive index layers, polyaniline, polypyrrole, etc. And π-conjugated polymers. It is also preferable to improve the conductivity by arranging a metal wiring such as a comb type or a grid type on the front electrodes. The surface resistance of the front electrode is preferably in the range of 0.1Ω / □ to 200Ω / □.

  As the back electrode on the side from which light is not extracted, any conductive material can be used. The material is selected from metal such as gold, silver, platinum, copper, iron, aluminum, graphite, and the like according to the form of the element to be manufactured, the temperature of the manufacturing process, and the like. Further, a transparent electrode such as ITO may be used as long as it is conductive.

  When both the front electrode and the back electrode are not transmissive, the dispersion-type inorganic EL element emits light mainly from the side surface. In this case, the number of electrode options increases, and the luminance of the phosphor layer can be increased by changing the type of electrode. On the other hand, when one of the electrodes is a transparent electrode and is laminated in the order of the back electrode, the insulator layer, the phosphor layer, and the transparent electrode, the dispersed inorganic EL element emits light mainly by light transmitted through the transparent electrode. In this configuration, loss due to reflection of light between the electrodes is reduced, so that it is easy to increase the light emission efficiency of the element. In general, the phosphor layer having a large area is preferably provided with the transparent electrode because the light utilization efficiency is high.

(Insulator layer)
The dispersion-type inorganic EL element of the present invention basically has a configuration in which a phosphor layer, an insulator layer, and an intermediate layer are sandwiched by a pair of electrodes facing each other. It is preferable to form an insulator layer between the phosphor layer and the back electrode because the light emission starting voltage becomes stable and the fabrication becomes easy.

As the insulator layer, any material can be used as long as it has a high relative dielectric constant and a high breakdown voltage. These can be obtained by dispersing dielectric particles selected from metal oxides and nitrides in a resin. As the resin, the same resin as that used in the phosphor layer can be used. Examples of dielectric particles used include TiO ₂ , BaTiO ₃ , SrTiO ₃ , PbTiO ₃ , KNbO ₃ , PbNbO ₃ , Ta ₂ O ₃ , BaTa ₂ O ₆ , LiTaO ₃ , Y ₂ O ₃ , and Al _2. O ₃ , ZrO ₂ , AlON, ZnS and the like can be mentioned. Particularly preferred is BaTiO ₃ . As a dispersion method, a homogenizer, a planetary kneader, a roll kneader, an ultrasonic disperser, or the like can be used. A preferable amount of the phosphor powder used in the present invention is 4.2 to 20 by weight ratio with respect to the binder amount 1, and 4.5 to 10 is particularly preferable. According to this, a high-intensity dispersed inorganic EL element can be obtained. If the amount of resin is small, voids are likely to be generated in the insulator layer, and dielectric breakdown is likely to occur. If the amount of resin is large, the relative dielectric constant of the insulator layer is lowered and luminance is lowered.

  The insulator layer of the present invention can be formed by applying a resin in which high dielectric particles are dispersed on the back electrode or the phosphor layer. As a forming method, it is preferable to apply using a spin coating method, a dip coating method, a bar coating method, a spray coating method, or the like. In particular, it is preferable to use a method that does not select a printing surface, such as a screen printing method, or a method that allows continuous application, such as a slide coating method. For example, in the screen printing method, a dispersion liquid in which fine particles of phosphor or dielectric are dispersed in a polymer solution having a high dielectric constant is applied through a screen mesh. The film thickness can be controlled by selecting the number of meshes, emulsion film thickness, printing speed, squeegee hardness, and number of coatings. By changing the dispersion liquid, not only the phosphor layer and the insulator layer but also the back electrode can be formed, and further, the area can be increased by changing the size of the screen.

(Comparative Example 1)
One embodiment of the dispersion-type inorganic EL element of Comparative Example 1 is shown in FIG. The element shown in FIG. 11 has a front electrode 2, a phosphor layer 3, an insulator layer 4, and a back electrode 5 laminated in this order on one side of a base film 1, and is a dispersed inorganic EL element having no intermediate layer.

  A dispersion-type inorganic EL element without an intermediate layer was produced as follows. First, ITO was formed on a glass substrate to form a front electrode. Next, ZnS: Cu, Cl phosphor powder generally used as a blue-green phosphor and cyanoethyl cellulose as a binder resin are weighed and mixed at a weight ratio of 10 to 1, and N-methyl is mixed. A phosphor layer paste was prepared using -2-pyrrolidone (NMP) as a solvent. Then, the phosphor layer paste was formed by screen printing on the ITO front electrode formed on the glass substrate and dried at 140 ° C. for 10 minutes. This printing and drying operation was repeated, and a phosphor layer was formed while controlling the number of times of printing so that the film thickness was about 45 μm. The relative dielectric constant of the phosphor in the phosphor layer was 9.

Next, BaTiO ₃ powder as dielectric particles and cyanoethyl cellulose as a resin serving as a binder were weighed and mixed at a weight ratio of 3: 1 to prepare an insulator layer paste using NMP as a solvent. Then, the insulator layer paste was printed on the phosphor layer by a screen printing method, and then dried at 140 ° C. for 10 minutes. This printing and drying operation was repeated to form an insulating layer of about 15 μm.

  Finally, a back electrode was printed on the insulator layer by a screen printing method using a commercially available graphite paste (manufactured by Nippon Ation, UN801), and then dried at 140 ° C. for 10 minutes. This printing and drying operation was repeated to form a back electrode of about 15 μm. As described above, a dispersion-type inorganic EL element having no intermediate layer was produced.

  The luminance of the obtained dispersion-type inorganic EL element was measured with a luminance meter in a dark room. Table 1 shows the luminance at a frequency of 1 kHz and an applied voltage of 350 V as 100%.

( Reference Example 1)
A dispersion-type inorganic EL element having the structure shown in FIG. 3 was produced as follows. First, an ITO film was formed on the first glass substrate so as to have the same pattern as the front electrode 2 of FIG. Thereafter, the same insulator layer paste as in Comparative Example 1 was screen-printed on a glass substrate so as to have the same pattern as that of the dielectric film 60 of FIG. 5, and then dried at 140 ° C. for 10 minutes. The operation of printing and drying the insulator layer paste was repeated, and a support portion for forming an intermediate layer composed of an air layer was formed to a thickness of about 15 μm.

  Next, in order to produce the laminated body shown in FIG. 6, ITO was formed into a film on the 2nd glass substrate. Thereafter, the same insulator layer paste as that used for the first glass substrate was screen-printed on the ITO film and then dried at 140 ° C. for 10 minutes. The operation of printing and drying the insulator layer paste was repeated to form an insulator layer of about 15 μm. On the insulator layer, the same phosphor layer paste as in Comparative Example 1 was screen-printed and then dried at 140 ° C. for 10 minutes. This printing and drying operation was repeated, and the film was formed while controlling the number of times of printing so that the phosphor layer had a thickness of about 45 μm. After the above two glass substrates are superposed as shown in FIG. 3, the dispersion type inorganic EL element having a structure in which air having a relative dielectric constant of 1 is used as an intermediate layer is thermally adhered at 140 ° C. for 10 minutes. Produced.

The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.11. As shown in Table 1, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 140% when the luminance of Comparative Example 1 was 100%. In this manner, by the dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) 0.2 or less, a large variance of the luminance A type inorganic EL element was obtained.

(Comparative Example 2)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. First, ITO was formed on a glass substrate to form a front electrode. Next, after diluting and mixing a silane coupling agent (specifically, KBE-903 made by Shin-Etsu Silicone) in a weight ratio of 2.5 to 97.5 with ethanol, it is placed on the ITO front electrode under the condition of 3000 rpm for 10 seconds. Spin coated. After drying at 80 ° C. for 10 minutes, CYTOP (registered trademark of Asahi Glass Co., Ltd.), which is an amorphous fluororesin having a relative dielectric constant of 2, was spin-coated at 3000 rpm for 10 seconds and then dried at 120 ° C. for 10 minutes. And in order to improve wettability, the amorphous fluororesin formed into a film on the ITO front electrode was plasma-cleaned. This silane coupling agent treatment to plasma cleaning was repeated until the film thickness of the amorphous fluororesin became about 15 μm.

  Subsequently, the same phosphor layer paste as in Comparative Example 1 was screen-printed and then dried at 140 ° C. for 10 minutes. This printing and drying operation was repeated, and the film was formed while controlling the number of times of printing so that the phosphor layer had a thickness of about 45 μm. Furthermore, after screen printing using the same insulator layer paste as in Comparative Example 1, it was dried at 140 ° C. for 10 minutes. This printing and drying operation was repeated to form an insulating layer of about 15 μm. Finally, after screen printing using the same graphite paste as in Comparative Example 1, it was dried at 140 ° C. for 10 minutes. This printing and drying operation was repeated to form a back electrode of about 15 μm.

The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.22. As shown in Table 1, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 65% when the luminance of Comparative Example 1 was 100%.

(Comparative Examples 3 and 4)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. A dispersion-type inorganic EL element in which the intermediate layer is made of an acrylic resin (Comparative Example 3) and cyanoethyl cellulose (Comparative Example 4) in the same manner as in Comparative Example 2 except that an acrylic resin ink or a cyanoethyl cellulose ink is applied. Was made. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) , respectively, were 0.44,1.67. As shown in Table 1, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 36% and 10%, respectively, assuming that the luminance of Comparative Example 1 was 100%.

In Comparative Example 2-4, the dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder (epsilon ₂₎ the ratio of (ε ₁ / ε ₂₎ for greater than 0.2, the intermediate layer Even when it was introduced, a dispersion-type inorganic EL element having a large luminance was not obtained.

(Comparative Example 5)
A dispersion-type inorganic EL element having the structure shown in FIG. 11 was produced as follows. A dispersion-type inorganic EL device was produced in the same manner as in Comparative Example 1 except that a CaTiO ₃ : Pr ³⁺ phosphor having a relative dielectric constant of 160 was used. The obtained dispersion-type inorganic EL element is shown in Table 2 with the luminance at a frequency of 1 kHz and an applied voltage of 350 V as 100%.

(Example 2)
A dispersion-type inorganic EL element having the structure shown in FIG. 3 was produced as follows. A dispersion-type inorganic EL device in which the intermediate layer is an air layer was produced in the same manner as in Example 1 except that a CaTiO ₃ : Pr ³⁺ phosphor having a relative dielectric constant of 160 was used. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.006. As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 1800% when the luminance of Comparative Example 5 was 100%. In this manner, by the dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder (epsilon ₂₎ the ratio of (ε _{1 /} ε ₂₎ to 0.01 or less, it size of more luminance A dispersion-type inorganic EL element was obtained.

( Reference Example 3)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. A dispersion-type inorganic EL element using CYTOP (registered trademark of Asahi Glass Co., Ltd.), which is an amorphous fluororesin, as an intermediate layer in the same manner as in Comparative Example 2, except that a CaTiO ₃ : Pr ³⁺ phosphor having a relative dielectric constant of 160 is used. Produced. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.013. As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 850% when the luminance of Comparative Example 5 was 100%. In this manner, by the dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) 0.2 or less, a large variance of the luminance A type inorganic EL element was obtained.

( Reference Example 4)
A dispersion-type inorganic EL element having the structure shown in FIG. 9 was produced as follows. First, ITO was formed on a glass substrate to form a front electrode. Next, using the same silane coupling agent diluted with ethanol as in Comparative Example 2, spin coating was performed on the ITO front electrode at 3000 rpm for 10 seconds. After drying at 80 ° C. for 10 minutes, CYTOP (registered trademark of Asahi Glass Co., Ltd.), which is the same amorphous fluororesin as in Comparative Example 2, was spin coated at 3000 rpm for 10 seconds. And in order to improve wettability, the amorphous fluororesin formed into a film on the ITO front electrode was plasma-cleaned. This silane coupling agent treatment to plasma cleaning was repeated until the film thickness of the amorphous fluororesin was about 7.5 μm.

  The ITO front electrode having the intermediate layer on which the amorphous fluororesin was formed was subjected to plasma cleaning, and then the same phosphor layer paste as that in Comparative Example 5 was screen-printed, followed by drying at 140 ° C. for 10 minutes. This printing and drying operation was repeated to form a film while controlling the number of times of printing so that the phosphor layer had a thickness of about 22.5 μm. Further, the same operation was repeated on the printed phosphor layer to form an amorphous fluororesin having a thickness of about 7.5 μm and a phosphor layer having a thickness of about 22.5 μm.

  Furthermore, after screen printing using the same insulator layer paste as in Comparative Example 1, it was dried at 140 ° C. for 10 minutes. This printing and drying operation was repeated to form an insulating layer of about 15 μm. Finally, after screen printing using the same graphite paste as in Comparative Example 1, it was dried at 140 ° C. for 10 minutes. This printing and drying operation was repeated to form a back electrode of about 15 μm.

The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.013. As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 1200% when the luminance of Comparative Example 5 was 100%. Thus, by having a structure having two layers of the phosphor layer and the intermediate layer, the area where the phosphor layer is in contact with the intermediate layer is tripled, and a dispersed inorganic EL element with higher brightness than Reference Example 3 is obtained. It was.

(Comparative Example 6)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. The same BaTiO ₃ powder and cyanoethyl cellulose as those used in the production of the insulator layer paste in Comparative Example 1 were weighed and mixed at a weight ratio of 7: 3, and the intermediate layer paste was prepared using NMP as a solvent. A dispersion-type inorganic EL element was produced in the same manner as in Comparative Example 2 except that it was prepared and coated.

The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.34. As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 42% when the luminance of Comparative Example 5 was 100%. Thus, since the dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) is greater than 0.2, by introducing an intermediate layer However, a dispersion-type inorganic EL element having high luminance could not be obtained.

( Reference Example 5)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. The same BaTiO ₃ powder and cyanoethyl cellulose as those used in the production of the insulator layer paste in Comparative Example 1 were weighed and mixed at a weight ratio of 1: 1, and the intermediate layer paste was prepared using NMP as a solvent. A dispersion-type inorganic EL element was produced in the same manner as in Comparative Example 6 except that it was prepared and coated.

The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.19. As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 106% when the luminance of Comparative Example 5 was 100%. In this manner, by the dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) 0.2 or less, a large variance of the luminance A type inorganic EL element was obtained.

( Reference Examples 6 and 7)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. A dispersion-type inorganic EL element was produced in the same manner as in Comparative Example 6 except that an acrylic resin ink and a cyanoethyl cellulose ink were coated as an intermediate layer.

The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.025,0.09. As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 450% and 130% when the luminance of Comparative Example 5 was 100%.

( Reference Examples 8 and 9)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. A dispersion-type inorganic EL element was produced in the same manner as in Comparative Example 6 except that SiO ₂ and Si ₃ N ₄ were coated as an intermediate layer. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.025, 0.05. As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 480% and 230% when the luminance of Comparative Example 5 was 100%.

As in Example 6-9, by the dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) and 0.2 or less Thus, a dispersion-type inorganic EL element having high luminance was obtained.

(Example 10)
A dispersion-type inorganic EL element having the structure shown in FIG. 3 was produced as follows. An inorganic EL element in which the intermediate layer is an air layer in the same manner as in Example 2 except that CYTOP (registered trademark of Asahi Glass Co., Ltd.), which is an amorphous fluororesin having a thickness of 0.01 μm, is used as a support for forming the intermediate layer. Produced. A 0.01 μm amorphous fluororesin was formed as follows.

  First, ITO was formed on a glass substrate so as to have a pattern similar to that of the front electrode 2 in FIG. Next, a photosensitive resist was applied on the deposited ITO so as to have the same pattern as the front electrode 2 of FIG. And it spin-coated on the glass substrate on the conditions for 10 second at 3000 rpm using the silane coupling agent diluted with ethanol similar to the comparative example 2. After drying at 80 ° C. for 10 minutes, CYTOP (registered trademark of Asahi Glass Co., Ltd.) and CYTOP diluent are diluted 1: 350 by weight, and then stirred using a solution at 3000 rpm for 10 seconds. Spin coated. And in order to improve wettability, the amorphous fluororesin formed into a film was plasma-cleaned. The operations from silane coupling agent treatment to plasma cleaning were repeated until the amorphous fluororesin had a thickness of 0.01 μm. And the photosensitive resist was removed using peeling liquid, and the support part for forming the intermediate | middle layer which consists of an air layer was formed. By using this support portion, a dispersion-type inorganic EL element having a structure in which air with a relative dielectric constant of 1 having a thickness of 0.01 μm was used as an intermediate layer was produced.

  As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 90000% when the luminance of Comparative Example 5 was 100%.

(Examples 11 and 12)
A dispersion-type inorganic EL element having the structure shown in FIG. 3 was produced as follows. The intermediate layer is an air layer in the same manner as in Example 10, except that CYTOP (registered trademark of Asahi Glass Co., Ltd.), which is an amorphous fluororesin, and CYTOP diluent are diluted 1:35 by weight and then a stirred solution is used. An inorganic EL element was produced. The film thickness of the intermediate layer made of the air layer was 0.1 μm and 1 μm, respectively.

  As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 60000% and 17500%, assuming that the luminance of Comparative Example 5 was 100%.

(Example 13)
An inorganic EL device having an air layer as an intermediate layer was produced in the same manner as in Example 10 except that a CYTOP (registered trademark of Asahi Glass Co., Ltd.) solution, which is an amorphous fluororesin, was used. The thickness of the intermediate layer made of the air layer was 5 μm. As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 6200% when the luminance of Comparative Example 5 was 100%.

(Examples 14 and 15)
A dispersion-type inorganic EL element having the structure shown in FIG. 3 was produced as follows. Except that the film thickness of the intermediate layer was 30 μm and 50 μm, respectively, the brightness at a frequency of 1 kHz and an applied voltage of 350 V, in which a dispersion-type inorganic EL element in which the intermediate layer was an air layer was prepared in the same manner as in Example 2, is shown in Table 2. As shown in FIG. 4, when the luminance of Comparative Example 5 is 100%, they are 450% and 105%.

As in Examples 10 to 15, by setting the film thickness (d ₁ ) of the intermediate layer to 10 nm or more and 50 μm or less, preferably 10 nm or more and 30 μm or less, a dispersed inorganic EL element having high luminance was obtained.

(Examples 16 to 23)
A dispersion-type inorganic EL element having the structure shown in FIG. 3 was produced as follows. A dispersion-type inorganic EL element in which the intermediate layer is an air layer was produced in the same manner as in Example 14 except that the film thickness (d ₂ ) of the phosphor layer was 10 μm to 650 μm. As shown in Table 2, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 342 to 460%, assuming that the luminance of Comparative Example 5 was 100%.

As in Examples 16 to 23, by setting the film thickness (d ₂ ) of the phosphor layer to 10 μm or more and 650 μm or less, preferably 10 μm or more and 300 μm or less, a dispersed inorganic EL element having high luminance was obtained.

(Comparative Example 7)
A dispersion-type inorganic EL element having the structure shown in FIG. 11 was produced as follows. A dispersion-type inorganic EL element having no intermediate layer was produced in the same manner as in Comparative Example 1 except that a CaZrO ₃ : Eu ³⁺ phosphor having a relative dielectric constant of 28 was used. The obtained dispersion-type inorganic EL element is shown in Table 3 with the luminance at a frequency of 1 kHz and an applied voltage of 350 V as 100%.

( Reference Example 24)
A dispersion-type inorganic EL element having the structure shown in FIG. 3 was produced as follows. A dispersion-type inorganic EL device in which the intermediate layer is an air layer was produced in the same manner as in Reference Example 1 except that a CaZrO ₃ : Eu ³⁺ phosphor having a relative dielectric constant of 28 was used. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.04. As shown in Table 3, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 400% when the luminance of Comparative Example 7 was 100%.

( Reference Example 25)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. A dispersion-type inorganic EL element using CYTOP (registered trademark of Asahi Glass Co., Ltd.), which is an amorphous fluororesin, in the intermediate layer in the same manner as in Comparative Example 2 except that a CaZrO ₃ : Eu ³⁺ phosphor having a relative dielectric constant of 28 is used. Produced. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.07. As shown in Table 3, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 180% when the luminance of Comparative Example 7 was 100%.

As in Reference Example 24 and 25, by the relative dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) and 0.2 or less Thus, a dispersion-type inorganic EL element having high luminance was obtained.

(Comparative Example 8)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. As an intermediate layer, BaTiO ₃ powder and cyanoethyl cellulose similar to those used in preparing the insulator layer paste in Comparative Example 1 were weighed and mixed at a weight ratio of 7: 3, and NMP was used as a solvent. A dispersion-type inorganic EL element was produced in the same manner as in Reference Example 25 except that a layer paste was produced and used. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 1.96. As shown in Table 3, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 7% when the luminance of Comparative Example 7 was 100%.

Thus, since the dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) is greater than 0.2, by introducing an intermediate layer However, a dispersion-type inorganic EL element having high luminance could not be obtained.

(Comparative Example 9)
A dispersion-type inorganic EL element having the structure shown in FIG. 11 was produced as follows. A dispersion-type inorganic EL element without an intermediate layer was produced in the same manner as in Comparative Example 1 except that (Ca _0.6 Sr _0.4 ) TiO ₃ : Pr ³⁺ phosphor having a relative dielectric constant of 240 was used. The obtained dispersion-type inorganic EL element is shown in Table 4 with the luminance at a frequency of 1 kHz and an applied voltage of 350 V as 100%.

(Example 26)
A dispersion-type inorganic EL element having the structure shown in FIG. 3 was produced as follows. A dispersion-type inorganic EL device in which the intermediate layer is an air layer was produced in the same manner as in Reference Example 1 except that (Ca _0.6 Sr _0.4 ) TiO ₃ : Pr ³⁺ phosphor having a relative dielectric constant of 240 was used. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.004. As shown in Table 4, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 2800% when the luminance of Comparative Example 9 was 100%.

(Example 27)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. CYTOP (registered trademark of Asahi Glass Co., Ltd.), which is an amorphous fluororesin, is used in the intermediate layer in the same manner as in Comparative Example 2 except that (Ca _0.6 Sr _0.4 ) TiO ₃ : Pr ³⁺ phosphor having a relative dielectric constant of 240 is used. A dispersion-type inorganic EL device using the above was prepared. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.008. As shown in Table 4, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 1200% when the luminance of Comparative Example 9 was 100%.

As in Example 26 and 27, by a relative dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) 0.01 or less Thus, a dispersion-type inorganic EL element with higher luminance was obtained.

(Comparative Example 10)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. As an intermediate layer, BaTiO ₃ powder and cyanoethyl cellulose similar to those used in preparing the insulator layer paste in Comparative Example 1 were weighed and mixed at a weight ratio of 7: 3, and NMP was used as a solvent. A dispersion-type inorganic EL element was produced in the same manner as in Example 27 except that a layer paste was produced and used. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.23. As shown in Table 3, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 60% when the luminance of Comparative Example 9 was 100%.

Thus, since the dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) is greater than 0.2, by introducing an intermediate layer However, a dispersion-type inorganic EL element having high luminance could not be obtained.

(Comparative Example 11)
A dispersion-type inorganic EL element having the structure shown in FIG. 11 was produced as follows. A dispersion-type inorganic EL element without an intermediate layer was produced in the same manner as in Comparative Example 1 except that SrTiO ₃ : Pr ³⁺ —Al ³⁺ phosphor having a relative dielectric constant of 260 was used. The resulting dispersion-type inorganic EL element is shown in Table 5 with the luminance at a frequency of 1 kHz and an applied voltage of 350 V being 100%.

(Example 28)
A dispersion-type inorganic EL element having the structure shown in FIG. 3 was produced as follows. A dispersion-type inorganic EL device in which the intermediate layer is an air layer was produced in the same manner as in Reference Example 1 except that SrTiO ₃ : Pr ³⁺ —Al ³⁺ phosphor having a relative dielectric constant of 260 was used. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.004. As shown in Table 5, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 3000% when the luminance of Comparative Example 11 was 100%.

(Example 29)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. A dispersed inorganic material using CYTOP (registered trademark of Asahi Glass Co., Ltd.), which is an amorphous fluororesin, in the intermediate layer in the same manner as in Comparative Example 2 except that SrTiO ₃ : Pr ³⁺ -Al ³⁺ phosphor having a relative dielectric constant of 260 is used. An EL element was produced. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.008. As shown in Table 5, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 1350% when the luminance of Comparative Example 11 was 100%.

As in Example 28 and 29, by a relative dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) 0.01 or less Thus, a dispersion-type inorganic EL element with higher luminance was obtained.

Here, as in Reference Examples 24 and 25, it can be seen that by using a phosphor powder having a relative dielectric constant (ε ₂ ) of 20 or more as a phosphor powder, a dispersed inorganic EL element with high luminance is obtained. Further, by using a phosphor powder having a relative dielectric constant (ε ₂ ) of 160 or more as in Examples 2 , 10 to 23, and Examples 26 to 29, a dispersed inorganic material having higher luminance. It turns out that it becomes an EL element.

And it turns out that it becomes a dispersion-type inorganic EL element with a big brightness | luminance by using perovskite type oxide fluorescent substance powder like Example 2 , 10-23, and 26-29 .

(Comparative Example 12)
A dispersion-type inorganic EL device having the structure shown in FIG. 2 was produced as follows. As an intermediate layer, BaTiO ₃ powder similar to that used in preparing the insulator layer paste in Comparative Example 1 and cyanoethyl cellulose were weighed and mixed at a weight ratio of 7 to 3, and the intermediate layer was made using NMP as a solvent. A dispersion-type inorganic EL device was produced in the same manner as in Example 29 except that a paste was prepared and used. The ratio of the relative dielectric constant of the intermediate layer (epsilon ₁₎ and the relative dielectric constant of the phosphor powder _{(ε 2) (ε 1 /} ε 2) was 0.21. As shown in Table 5, the luminance at a frequency of 1 kHz and an applied voltage of 350 V was 63% when the luminance of Comparative Example 11 was 100%.

Thus, since the dielectric constant of the intermediate layer (epsilon ₁₎ the ratio of the dielectric constant of the phosphor powder and _{(ε 2) (ε 1 /} ε 2) is greater than 0.2, by introducing an intermediate layer However, a dispersion-type inorganic EL element having high luminance could not be obtained.

1 Base film 2 Front electrode (transparent electrode)
3 Phosphor Layer 4 Insulator Layer 5 Back Electrode 6 Intermediate Layer 7 Phosphor Powder 8 Resin Composition 60 Dielectric Film 61 Permanent Resist 62 Glass Bead 63 Air Layer

Claims (9)

In a dispersive inorganic electroluminescent device comprising a laminate of a phosphor layer in which phosphor powder is dispersed in a resin and an insulator layer between a front electrode and a back electrode, at least the phosphor layer and the front surface An intermediate layer is provided between the electrodes, and the ratio (ε ₁ / ε ₂ ) between the relative dielectric constant (ε ₁ ) of the intermediate layer and the relative dielectric constant (ε ₂ ) of the phosphor powder is 0.01 or less. A dispersive inorganic electroluminescence device characterized in that:   2. The dispersion type inorganic electroluminescence device according to claim 1, wherein the relative dielectric constant of the intermediate layer is 2 or less.   2. The dispersed inorganic electroluminescence device according to claim 1, wherein at least a part of the intermediate layer is an air layer. The film thickness of the intermediate layer, the dispersion-type inorganic electroluminescent device according to any one of claims 1 to 3, characterized in that at 10nm or more 30μm or less. The thickness of the said fluorescent substance layer is 10 micrometers or more and 300 micrometers or less, The dispersion type inorganic electroluminescent element of any one of Claims 1-3 characterized by the above-mentioned.   2. The dispersed inorganic material according to claim 1, wherein the phosphor layer has two or more phosphor layers, and an intermediate layer is formed between the phosphor layers and the front electrode in contact with each phosphor layer. Electroluminescence element. Dispersed inorganic electroluminescent device according to claim 1, wherein the dielectric constant of the phosphor powder is characterized in that 20 or more. Dispersed inorganic electroluminescent device according to claim 1, wherein the dielectric constant of the phosphor powder is characterized in that 160 or more. Dispersed inorganic electroluminescent device according to claim 1, wherein the phosphor powder is perovskite type oxide phosphor.

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