JP2008251321A - Inorganic electroluminescent element, and illumination device equipped with this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic EL element having high productivity, capable of easily forming a film and enhancing light emission brightness, and also provide an illumination device equipped with this inorganic EL element useful for many uses and having high illumination quality. <P>SOLUTION: By providing a high dielectric buffer layer (second insulating layer) between an insulating layer and a light-emitting layer, adhesiveness between the insulating layer and the light-emitting layer can be enhanced largely, and the light emission brightness can be elevated. In other words, the EL element has the rear electrode, the insulating layer, the light-emitting layer, and a transparent electrode sequentially laminated. The insulating layer includes a first insulating layer not containing an organic binder and the second insulating layer containing the organic binder, and the light-emitting layer is laminated on the second insulating layer, thus the inorganic EL element is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inorganic EL element and a lighting device including the inorganic EL element.

  Inorganic EL elements are expected to be applied to backlights for liquid crystal displays, various interior lighting, in-vehicle display devices and the like because of their high definition, high contrast, and high response speed. Inorganic EL elements include a thin film type EL element in which the element is usually formed to a thickness of several μm by means such as vapor deposition, and a distributed EL element in which the element is usually formed to a thickness of several tens of μm by means of screen printing or the like.

  In 1974, Higuchi et al. Proposed a double-insulated device as a thin-film EL device. This element has been shown to have high brightness and long life, and has been put to practical use as an in-vehicle display. In addition, an inorganic EL using a thick dielectric layer as one insulating layer constituting a double insulating structure is known (for example, Patent Document 1). In this inorganic EL element, it is possible to reduce dielectric breakdown during driving caused by a pinhole formed due to contamination in the manufacturing process. Further, by using a thick dielectric layer, the dielectric constant of the insulating layer can be increased, thereby reducing the division of the voltage applied to the insulating layer, reducing the drive voltage and increasing the light emission luminance. .

On the other hand, a dispersion-type inorganic EL element usually has a transparent electrode in which a transparent conductive layer made of ITO (indium oxide) or the like is formed on one side of a substrate made of PET (polyethylene terephthalate) or the like, and phosphor fine particles in an organic binder. It consists of a light emitting layer that is dispersed, an insulating layer in which dielectric fine particles are dispersed in an organic binder, and a back electrode made of aluminum, silver, or the like, which are stacked in order to further improve moisture resistance and durability. A surface protective layer is provided. In recent years, there has been a report using a thick dielectric layer as an insulating layer of a distributed EL element (for example, Patent Document 2). In FIG. 1, specifically, a paste such as PbNbO ₃ , BaTiO ₃ , SrTiO ₃ , PbTiO ₃ , (Sr, Ca) TiO ₃ is used to form the insulating layer 3 on the back electrode 2 by screen printing. A fired ceramic material to be fired is used, and the dispersed light emitting layer 4 is formed on the insulating layer 3 by a screen printing method and dried.
JP-A-61-230296 JP 2005-317251 A

  In a thin-film inorganic EL device in which a light-emitting layer is fabricated using a sputtering method or vacuum deposition method on an insulating layer made of a fired ceramic material, the light-emitting layer has a thickness of about 1 μm. In order to form a film, the smoothness of the lower layer is important. For this reason, usually, measures such as polishing of the insulating layer and multilayering of the insulating layer are required, and the productivity is low.

  On the other hand, as described above, by using a sintered ceramic material as an insulating layer and screen-printing a paste in which a phosphor is dispersed in an organic binder on the insulating layer, a method for producing an EL element is effective. Although a certain solution was obtained with respect to the improvement, the emission luminance could not be sufficiently increased.

  The present invention has been made in view of the above circumstances, and provides an inorganic EL element with high productivity, easy film formation, and enhanced emission luminance, and useful for many applications including this EL element. It is to provide a lighting device with high lighting quality.

The object of the present invention is achieved by the following means.
[1] An EL device in which a back electrode, an insulating layer, a light emitting layer, and a transparent electrode are sequentially laminated, wherein the insulating layer includes a first insulating layer containing no organic binder and a second insulating containing an organic binder. An inorganic EL element, wherein a light emitting layer is laminated on the second insulating layer.
[2] The inorganic EL element according to [1], wherein the first insulating layer is a ceramic material.
[3] The first insulating layer is a dielectric selected from the group consisting of barium titanate, barium zirconate titanate, lead zirconate titanate, and combinations thereof [1] Or the inorganic EL element of [2].
[4] The inorganic EL element according to any one of [1] to [3], wherein the thickness of the first insulating layer is in a range of 5 to 200 μm.
[5] The second insulating layer includes at least dielectric fine particles and an organic binder, and the dielectric fine particles and the organic binder are included in a weight ratio of 1: 2 to 49: 1. ] To [4] Inorganic EL device according to any one of
[6] The inorganic EL device according to [5], wherein the dielectric fine particles contained in the second insulating layer have an average particle size of 50 to 500 nm.
[7] An illumination device comprising the inorganic EL element according to any one of [1] to [6].

  In the invention described in [1] above, the insulating layer includes a first insulating layer that does not contain an organic binder and a second insulating layer that contains an organic binder, and a light emitting layer is stacked on the second insulating layer. As a result, the adhesion to the light emitting layer can be enhanced while the dielectric constant of the insulating layer is increased.

In the invention described in [2] above, since the first insulating layer is made of a ceramic material, it is possible to reduce dielectric breakdown during driving caused by a pinhole.
In the invention described in [3] above, the first insulating layer is a dielectric selected from the group consisting of barium titanate, barium zirconate titanate, lead zirconate titanate, and combinations thereof. Thus, the dielectric constant of the insulating layer is increased, and the light emission luminance of the inorganic EL element is improved.

In the invention described in [4] above, when the film thickness of the first insulating layer is in the range of 5 to 200 μm, dielectric breakdown during driving can be reduced, and the device can be driven stably. it can.
In the invention described in [5] above, the second insulating layer contains at least dielectric fine particles and an organic binder, and the dielectric fine particles and the organic binder are contained in a weight ratio of 1: 2 to 49: 1. Thus, productivity can be improved.

In the invention described in [6] above, when the average particle diameter of the dielectric fine particles contained in the second insulating layer is 50 to 500 nm, the dielectric constant of the insulating layer is increased, and the emission luminance of the inorganic EL element is increased. improves.
The invention described in [7] above can provide an illumination device with uniform and bright luminance and high illumination quality by including the inorganic EL element of the present invention.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a schematic sectional view showing an example of the inorganic EL element of the present invention. The inorganic EL device of the present invention includes a back electrode 12, a first insulating layer 13 that does not contain an organic binder, a second insulating layer 14 that contains an organic binder, and an inorganic fluorescent material on the organic binder. A light emitting layer 15 in which body particles are dispersed, a transparent electrode 16, and a cover layer 17 are laminated in this order to form a light emitting portion in an EL display device described later.

<Back substrate>
The back substrate 11 must be able to withstand the firing temperature when the first insulating layer 13 provided on the back substrate 11 is formed. A glass substrate can be used if the firing temperature is about 600 ° C. or lower. Further, a quartz substrate, a ceramic substrate, or the like can be used if the firing temperature exceeds 600 ° C. and is 1,000 ° C. or less. Furthermore, when the firing temperature exceeds 1,000 ° C., a ceramic substrate such as alumina or zirconia, or a silicon wafer can be used.

<Back electrode>
The back electrode 12 on the side from which light is not extracted is required to be a material that retains conductivity even after heating and baking at the time of forming the upper insulating layer. For the back electrode 12, for example, a noble metal such as Au, Pd, or Pt, a metal such as Cr, W, Mo, or Ni, or an alloy thereof can be used. These materials are selected depending on the firing temperature, firing atmosphere, and conductivity.

<Insulating layer>
The first insulating layer 13 does not contain an organic binder and is preferably made of a ferroelectric material. By using the ferroelectric material, the capacitance of the insulating layer can be sufficiently increased, and the division of the voltage applied to the insulating layer can be reduced. The relative dielectric constant of the first insulating layer 13 is preferably 500 to 25000, and more preferably 1000 to 10,000. The basic dielectric is preferably a ceramic material having a perovskite structure in order to obtain a high dielectric constant. For example, PbNbO ₃ , BaTiO ₃ , BaTi _x Zr _1-x O ₃ , SrTiO ₃ , PbTiO ₃ , (Sr, Ca) Examples thereof include TiO ₃ and PbZr _1-x Ti _x O ₃ . More preferably, the dielectric is selected from the group consisting of BaTiO ₃ , BaTi _x Zr _1-x O ₃ , PbZr _1-x Ti _x O ₃ , and combinations thereof.

  As the thickness of the first insulating layer 13 is increased, the reliability against dielectric breakdown is improved. However, since the capacitance is reduced by increasing the thickness, the thickness is preferably 200 μm or less. On the other hand, when the film thickness is reduced, the reliability of dielectric breakdown due to the decrease in the film thickness decreases, and therefore a film thickness of 5 μm or more is preferable. This first insulating layer 13 is a method in which a dielectric material powder and an organic binder are mixed and stirred, formed into a film by coating, and then heated and fired. A dielectric material powder and an organic binder are mixed, and a green sheet is produced by casting. In addition, it can be manufactured by a technique such as a method of firing after being laminated and pressure-bonded to the electrode. The film formation is formed by a known thick film technique such as casting, doctor blade, or screen printing. After the film formation, the precursor of the dielectric material is baked at a predetermined temperature to form the first insulating layer 13 made of a dielectric. Further, the film may be formed a plurality of times in order to obtain a predetermined film thickness.

The second insulating layer 14 includes at least dielectric fine particles and an organic binder. As the dielectric fine particles, any material can be used as long as it is a material having a high dielectric constant and insulation and a high dielectric breakdown voltage. These metal oxides are selected from nitrides, for example _{TiO 2, BaTiO 3, SrTiO 3} , PbTiO 3, KNbO 3, PbNbO 3, Ta 2 O 5, BaTa 2 O 6, LiTaO 3, Y 2 O 3, Al ₂ O ₃ , ZrO ₂ , AlON, ZnS, etc. are used. In order not to reduce the capacitance of the entire insulating layer, it is more preferable to use a ferroelectric material such as BaTiO ₃ , BaTi _x Zr _1-x O ₃ , PbZr _1-x Ti _x O ₃ . The smaller the particle size of the dielectric fine particles, the smaller the film thickness of the second insulating layer and the higher the capacitance. In general, the smaller the particle size of the dielectric fine particles, the lower the dielectric constant. There is a conflicting relationship. Moreover, when the particle size of the dielectric fine particles is too small, the particles are strongly aggregated, and it tends to be difficult to prepare a paste suitable for screen printing. Accordingly, the particle diameter of the dielectric fine particles used in the present invention is preferably in the range of 50 to 500 nm.

  As the organic binder, 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 can be used. As a dispersion method, a homogenizer, a planetary kneader, a roll kneader, an ultrasonic disperser, or the like can be used.

  The dielectric constant of the second insulating layer 14 used in the present invention is preferably higher in order not to reduce the capacitance. The relative dielectric constant of the second insulating layer is preferably 300 or less. In order to improve the dielectric constant of the second insulating layer, it is necessary to reduce the amount of the organic binder added. However, if the amount of the organic binder is decreased, it becomes difficult to form a uniform film, and the adhesion to the light emitting layer is improved. A problem such as a decrease occurs, and conversely, the emission luminance decreases. Accordingly, the dielectric fine particles and the organic binder are preferably contained in a weight ratio of 1: 2 to 49: 1, and particularly preferably 1: 1 to 9: 1.

  The second insulating layer 14 is preferably applied 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 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. When the thickness of the second insulating layer 14 in the present invention is increased, it is easy to produce a homogeneous film, and sufficient adhesion to the film and the light emitting layer can be obtained. Similarly to the case where the film thickness is increased, the capacitance is reduced, which causes a problem of an increase in driving voltage. Therefore, the film thickness of the second insulating layer 14 is preferably 0.1 to 50 μm, and more preferably 0.5 to 10 μm.

<Light emitting layer>
As the light emitting layer 15, a phosphor particle dispersed in an organic binder is used. As the organic binder, like the second insulating layer, a polymer having a relatively high dielectric constant, such as cyanoethyl cellulose resin, polyethylene, polypropylene, polystyrene resin, silicone resin, epoxy resin, vinylidene fluoride, etc. Resin can be used. The dielectric constant can also be adjusted by appropriately mixing fine particles of high dielectric constant such as BaTiO ₃ and 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. The phosphor particles and the organic binder used in the present invention are preferably in a weight ratio of 4.2: 1 to 20: 1, particularly preferably 4.5: 1 to 10: 1.

  The light emitting layer 15 is preferably applied 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. The film thickness of the light emitting layer 15 used in the present invention is preferably 100 μm or less, more preferably 1 to 50 μm.

<Phosphor particles>
The method for producing phosphor fine particles used in the present invention is not particularly limited, and a firing method, a urea melting method, a spray pyrolysis method, a hydrothermal synthesis method, and the like can be used.

  When the phosphor particles usable in the present invention are formed by a solid phase method using zinc sulfide as a base material, first, a 10-50 nm fine particle powder is prepared by a liquid phase method, and this is used as a primary particle. Impurities called activators are mixed, and the first firing is performed at a high temperature of 900 to 1300 ° C. for 30 minutes to 10 hours in a crucible together with the flux to obtain particles.

The intermediate phosphor powder obtained by the first firing is repeatedly washed with ion exchange water to remove alkali metal or alkaline earth metal, excess activator and coactivator.
Next, the obtained intermediate powder is subjected to second baking. In the second baking, heating is performed at a temperature lower than that of the first baking at 500 to 800 ° C. and for a short time of 30 minutes to 3 hours.

  These firings cause many stacking faults in the phosphor particles, but the conditions of the first firing and the second firing are set so that fine particles and more stacking faults are included in the phosphor particles. It is preferable to select appropriately.

  Further, by applying an impact force in a certain range to the first fired product, 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 particles to collide, a method of irradiating ultrasonic waves, etc. It can be preferably used. By these methods, particles having 10 or more stacking faults can be formed at intervals of 5 nm or less.

  Thereafter, the intermediate phosphor is etched with an acid such as HCl to remove the metal oxide adhering to the surface, and the copper sulfide adhering to the surface is removed by washing with KCN. Subsequently, the intermediate phosphor is dried to obtain an EL phosphor.

  In addition, in the case of zinc sulfide or the like, it is also preferable to use a hydrothermal synthesis method as a method of forming phosphor particles because a multiple twin structure is introduced into the phosphor crystal. In the hydrothermal synthesis method, particles are dispersed in a well-stirred aqueous solvent, and zinc ions and / or sulfur ions that cause particle growth are determined from outside the reaction vessel at a flow rate controlled by an aqueous solution. Add for a long time. Therefore, in this system, the particles can move freely in an aqueous solvent, and the added ions can diffuse in water and cause particle growth uniformly. The concentration distribution of the agent can be changed, and monodispersed zinc sulfide particles having a narrow size distribution can be obtained. It is preferable to insert an Ostwald ripening step between the nucleation process and the growth process in order to adjust the grain size and realize multiple twins.

  It is also preferable to use a urea melting method as a method for forming a phosphor usable in the present invention. The urea melting method is a method using molten urea as a medium for synthesizing a phosphor. A substance containing an element that forms a phosphor matrix or an activator is dissolved in a liquid in which urea is maintained at a temperature equal to or higher than the melting point to be in a molten state. Add reactants as needed. For example, when a sulfide phosphor is synthesized, a sulfur source such as ammonium sulfate, thiourea or thioacetamide is added to cause a precipitation reaction. When the temperature of the melt is gradually raised to about 450 ° C., a solid in which phosphor particles and phosphor intermediates are uniformly dispersed in a resin derived from urea is obtained. After this solid is finely pulverized, it is fired while thermally decomposing the resin in an electric furnace. By selecting an inert atmosphere, an oxidizing atmosphere, a reducing atmosphere, an ammonia atmosphere, or a vacuum atmosphere as the firing atmosphere, phosphor particles can be synthesized using oxide, sulfide, or nitride as a base material.

  Further, it is also preferable to use a spray pyrolysis method as a method for forming a phosphor usable in the present invention. Phosphor precursor solution is made into fine droplets using an atomizer, and phosphor particles or phosphor intermediates are generated by condensation within the droplets, chemical reaction, or chemical reaction with the ambient gas surrounding the droplet. You can synthesize things. By making the conditions for droplet formation suitable, particles having a fine particle size, a uniform amount of impurities, a sphere shape, and a narrow particle size distribution can be obtained. As an atomizer that generates fine droplets, it is preferable to use a two-fluid nozzle, an ultrasonic atomizer, or an electrostatic atomizer. The fine droplets generated by the atomizer are introduced into an electric furnace with a carrier gas and heated to dehydrate and condense, and the chemical reaction and sintering of the substances in the droplets, or the chemistry with the atmosphere gas The target phosphor particles or phosphor intermediate product is obtained by the reaction. The obtained particles are additionally fired as necessary. For example, when synthesizing a zinc sulfide phosphor, a mixture of zinc nitrate and thiourea is atomized and pyrolyzed in an inert gas (eg, nitrogen) at about 800 ° C. to form a spherical zinc sulfide phosphor. obtain. If trace impurities such as Mn, Cu and rare earth are dissolved in the mixed solution of the starting solution, these impurities act as luminescence centers.

As an activator of the phosphor particles, at least one ion selected from copper, manganese, silver, gold and rare earth elements can be preferably used.
As the coactivator, at least one ion selected from chlorine, bromine, iodine, and aluminum can be preferably used.

<Transparent electrode>
In the EL device of the present invention, any transparent electrode material that is generally used is used as the transparent electrode. For example, conductive oxides such as tin-doped indium oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, etc., fine particles and organic binders, and silver thin films with a high refractive index. Examples include multilayer structures sandwiched between layers, and π-conjugated polymers such as polyaniline and polypyrrole. The surface resistance of the transparent electrode is preferably in the range of 0.1Ω / □ to 200Ω / □.

<EL display device>
An inorganic EL display device can be obtained using the inorganic EL element of the present invention. The inorganic EL display element includes a case where display is performed using the light emission of the inorganic EL element itself and a case where a display element is separately provided in the light emission direction of the inorganic EL element. When displaying using the light emission of the inorganic EL element itself, for example, when displaying information by controlling the light emission of the element, particularly when controlling the light emission of a plurality of elements, the light emission of a plurality of elements of different colors is further controlled. And so on. For example, it is possible to obtain a color image or the like by periodically arranging a plurality of inorganic EL elements that emit green, blue, and red light and controlling the light emission. On the other hand, when a display element is provided separately, a transmissive display device such as an LCD display device is obtained by arranging a transmissive display element such as an LCD panel in the light emitting direction. Note that the display device described here includes a device having these display capabilities, a television receiver in which various members such as an information processing device, a tuner, and a speaker are added to these devices, a monitor device, and a laptop computer.

Hereinafter, the present invention will be described in more detail. In addition, this invention is not limited to the Example demonstrated here.
(Example 1)
Zirconia (Nihon Fine Ceramics: 3Y zirconia, 0.5 mm thickness) was used for the back substrate. A Pt paste (Tanaka Kikinzoku: TR7091) was screen-printed thereon and baked at 1400 ° C. for 1 hour to form a back electrode. For the first insulating layer, a paste made of 6 g of BaTiO ₃ (average particle size 500 nm), 0.12 g of organic vehicle (ethyl cellulose) and 1.7 g of solvent (terpineol) is prepared as a dielectric material, and screen printed on the back electrode. And calcination at 1400 ° C. for 1 hour. This process was repeated three times to form a thick dielectric film A having a thickness of about 30 μm. An Au electrode was prepared on this, and the relative dielectric constant measured by an LCR meter (Agilent: E4980A) was 2000.

For the second insulating layer, BaTiO ₃ (average particle size: 500 nm) as dielectric fine particles and cyanoresin (manufactured by Shin-Etsu Chemical Co., Ltd .: CR-V) as organic binders are added to dimethylformamide (DMF) at the following composition ratio, and planets are added. The mixture was dispersed with a mold stirring and deaerator (AR-250, manufactured by Shinky Corporation), and adjusted to a viscosity suitable for screen printing.

Barium titanate: 90 parts by weight Cyanoresin: 30 parts by weight Use the screen printing to apply the above dielectric paste to a dry film thickness of 5 μm. Printing was performed on the dielectric thick film A. After printing, it was dried at 120 ° C. to obtain a dielectric thick film laminate B. Separately, this dielectric paste was formed on a zirconia substrate equipped with a Pt electrode, an Au electrode was attached, and the relative dielectric constant measured by an LCR meter (Agilent: E4980A) was 90.

  The phosphor paste was prepared as follows. Phosphor particles (GG45 manufactured by Osram Sylvania) and cyanoresin (manufactured by Shin-Etsu Chemical Co., Ltd .: CR-V) as an organic binder are added to a DMF organic solvent at the following composition ratio, and dispersed with a planetary stirring deaerator. The viscosity was adjusted to be appropriate for printing.

Phosphor particles: 60 parts by weight Cyanoresin: 10 parts by weight Using phosphor to paste the above phosphor paste to a dry film thickness of 30 μm It printed on the dielectric thick film laminated body B so that it might become. After printing, the laminate was obtained by drying at 120 ° C.

As the transparent electrode, an ITO sol paste (manufactured by Sumitomo Metal Mining: SC120) was used, printed by screen printing, and then dried at 120 ° C. to obtain an EL device.
A voltage of 100 V and 400 Hz is applied between the voltage application lead wire connected to one end of the transparent electrode of the inorganic EL element fabricated as described above and the voltage application lead wire connected to one end of the back electrode, and the EL The device was allowed to emit light, and its luminance was measured with a color luminance meter (BM7 manufactured by Topcon Corporation). As a result, the luminance was 136 cd / m ² .

(Example 2)
Example except that a paste composed of 6 g of BaTi _x Zr _1-x O ₃ (average particle size 500 nm), 0.12 g of organic vehicle (ethylcellulose), and 1.7 g of solvent (terpineol) was used as the dielectric material of the first insulating layer 1 was used to prepare an inorganic EL element. At this time, the relative dielectric constant of the first insulating layer evaluated by the same method as in Example 1 was 2300, and the light emission luminance of the EL element was 145 cd / m ² .

(Example 3)
A paste made of 10 g BaTiO ₃ (average particle size 100 nm), 1 g organic vehicle (ethyl cellulose), 0.5 g dibutyl phthalate as plasticizer and 4.5 g solvent (terpineol) is kneaded for 48 hours in a ball mill to produce a slurry for ceramic green sheets. Obtained.

  The slurry was cast on a release-treated polyester film, air-dried at room temperature for 30 minutes, and then dried at about 80 ° C. for 1 hour using a hot air dryer to produce a green sheet serving as a ceramic substrate. An Ni paste was printed on the green sheet by screen printing to produce an electrode. A green sheet for the first insulating layer is separately formed by casting using the slurry, and is laminated and pressure-bonded onto the green sheet on which the Ni electrode is laminated. A multilayer ceramic structure was produced. After firing, the thickness of the first insulating layer was 200 μm. A dielectric constant measured by preparing an Au electrode on this was 3000.

An inorganic EL element was produced in the same manner as in Example 1 except that the multilayer ceramic structure was used as the first insulating layer, and the luminance measured was 104 cd / m ² .
(Example 4)
Except for using the first insulating layer of dielectric material as _{PbZr 1-x Ti x O 3} ( average particle diameter 500 nm) 6 g, an organic vehicle (ethyl cellulose) 0.12 g, solvent (terpineol) consisting 1.7g paste, carried An inorganic EL device was produced in the same manner as in Example 1. At this time, the dielectric constant of the first insulating layer evaluated in the same manner as in Example 1 was 1450, and the light emission luminance of the EL element was 121 cd / m ² .

(Example 5)
A voltage application lead wire connected to one end of the transparent electrode of the inorganic EL element produced in the same manner as in Example 1 and a voltage connected to one end of the back electrode, except that the thickness of the first insulating layer was 300 μm. A voltage of 100V and 400Hz was applied between the lead wires for application, the EL element was allowed to emit light, and the luminance was measured with a color luminance meter (BM7 manufactured by Topcon). The emission luminance was 95 cd / m ² . there were.

(Example 6)
It was connected to one end of a transparent electrode of an inorganic EL device produced in the same manner as in Example 1 except that the dielectric paste was prepared with a weight ratio of the dielectric particles of the second insulating layer and the organic binder of 1: 3. A voltage of 100V, 400Hz is applied between the voltage application lead wire and the voltage application lead wire connected to one end of the back electrode to cause the EL element to emit light, and the luminance is measured by a color luminance meter (BM7 manufactured by Topcon). As a result, the emission luminance was 103 cd / m ² .

(Comparative Example 1)
A voltage applying lead wire connected to one end of the transparent electrode of the inorganic EL element produced in the same manner as in Example 1 except that the second insulating layer is not provided, and a voltage applying lead wire connected to one end of the back electrode In the meantime, a voltage of 100 V and 400 Hz was applied to cause the EL element to emit light, and the luminance was measured with a color luminance meter (BM7 manufactured by Topcon Corp.). The emission luminance was 82 cd / m ² .

(Comparative Example 2)
A voltage application lead wire connected to one end of the transparent electrode of the inorganic EL element produced in the same manner as in Example 3 except that the second insulating layer is not provided, and a voltage application lead wire connected to one end of the back electrode In the meantime, a voltage of 100 V and 400 Hz was applied to cause the EL element to emit light, and the luminance was measured with a color luminance meter (BM7 manufactured by Topcon Corporation), and the emission luminance was 62 cd / m ² .

FIG. 1 is a schematic view of a cross section of a conventional inorganic EL element. FIG. 2 is a schematic view of a cross section of the inorganic EL element of the present invention.

Explanation of symbols

1． Back substrate
2． Back electrode
3． Insulation layer
Four. Luminescent layer
Five. Transparent electrode
6． Cover layer
11． Back substrate
12． Back electrode
13. First insulating layer
14. Second insulating layer
15． Luminescent layer
16． Transparent electrode
17． Cover layer

Claims (7)

  An EL element in which a back electrode, an insulating layer, a light emitting layer, and a transparent electrode are sequentially laminated, and the insulating layer includes a first insulating layer containing no organic binder and a second insulating layer containing an organic binder. And an inorganic EL element, wherein a light emitting layer is laminated on the second insulating layer.   2. The inorganic EL element according to claim 1, wherein the first insulating layer is a ceramic material.   3. The dielectric according to claim 1, wherein the first insulating layer is a dielectric selected from the group consisting of barium titanate, barium zirconate titanate, lead zirconate titanate, and combinations thereof. Inorganic EL element.   4. The inorganic EL element according to claim 1, wherein the film thickness of the first insulating layer is in a range of 5 to 200 μm.   5. The second insulating layer includes at least dielectric fine particles and an organic binder, and the dielectric fine particles and the organic binder are included in a weight ratio of 1: 2 to 49: 1. The inorganic EL device according to any one of the above.   6. The inorganic EL element according to claim 5, wherein the dielectric fine particles contained in the second insulating layer have an average particle size of 50 to 500 nm.   An illumination device comprising the inorganic EL element according to any one of claims 1 to 6.