JP2006120328A - Distributed electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distributed electroluminescent (EL) element that emits light with high efficiency and also provides long-lasting emission using a desired phosphor. <P>SOLUTION: A light emitting layer and a dielectric layer are provided between a transparent electrode and a back electrode. In the light emitting layer, at least a phosphor and a needle-like substance that is higher in conductivity than the phosphor are dispersed in an organic binder. In the present invention, since the needle-like substance is dispersed in the light emitting layer, the needle-like substance serves as a charge provider to allow high-energy electrons to collide with a desired phosphor with high efficiency. This enables the dispersed EL element to achieve a long life, high efficiency and multi-color light emission. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a distributed EL element used for an information display device, illumination, and the like.

Electroluminescent (EL) elements are classified into an electroluminescent type that emits light by exciting a phosphor by applying an alternating high electric field, and a charge injection type such as a light emitting diode. Among these, the electroluminescent type is roughly classified into a dispersion type EL element in which phosphor particles are dispersed in a binder, and a thin film type EL element in which a phosphor or an insulator is thinned by vapor deposition or the like to form an element.
The distributed EL element can be driven at a low voltage, can easily be increased in area, and can be easily made flexible. It is often used as a backlight. On the other hand, thin-film EL elements require vacuum deposition and are difficult to increase in area. However, since high-luminance light-emitting elements are obtained, application to color displays is being studied.

  FIG. 8 is a cross-sectional view of an example of a conventional dispersion type EL element.

  A back electrode 101 such as a silver or aluminum plate; a transparent substrate 102 such as a PET (Poly Ethylene Terephthalate) film; a transparent electrode 103 such as indium tin oxide (ITO) formed on the surface of the transparent substrate 102; Light emitting layer 105 interposed between transparent electrode 103 and phosphor powder 104 such as zinc sulfide dispersed in organic binder such as cyanoethyl cellulose, and high dielectric constant such as barium titanate in the same organic binder. It comprises a dielectric layer 107 in which a dielectric powder 106 is dispersed, a conductive wire 108 and a moisture-proof layer 109.

The light emission principle of the conventional dispersion type EL element is considered as follows from the report of Fisher et al.
By adding Cu to ZnS, which is a phosphor, CuxS needle crystals are deposited along the ZnS line defects. This CuxS exhibits a considerably high conductivity. When an electric field is applied to the phosphor, electric lines of force are concentrated near both ends of the line defect, and a high electric field (105 to 106 V / cm) is generated. When an AC electric field is applied, electrons and holes are emitted from both ends of the conductive defect line, and the emitted holes are trapped in the emission center and emit light, and after another half cycle, the electric field is reversed, and this time the electrons are When emitted, it recombines with the trapped holes to emit light. Therefore, the light emission of the dispersive EL starts from two spots at both ends of the defect line, and as the voltage is increased, they gradually grow and are observed as a comitated light emission facing each other.

JP 2002-266007 A J. et al. Electrochem. Soc. 109, p1043 (1962) J. et al. Electrochem. Soc. 110, p733 (1963)

However, the conventional dispersion-type EL element has a problem in that the lifetime of light emission is short because the number of line defects and CuxS needle crystals decreases slowly when an electric field is applied. In addition, when a dispersion type EL device is manufactured using a phosphor other than ZnS / CuxS, high energy electrons are not efficiently injected into the phosphor, and it is impossible to emit light with high efficiency and long life. It has become. Furthermore, for the reasons described above, there is a problem that the types of phosphors that can be used in the dispersion type EL element are limited, and the emission color is limited.

  Accordingly, an object of the present invention is to solve such a conventional problem, and to provide a dispersion type EL element that emits light with high efficiency in a desired phosphor and emits light for a long lifetime.

In the dispersion type EL device of the present invention, a light emitting layer and a dielectric layer are interposed between a transparent electrode and a back electrode, and the light emitting layer has a higher conductivity than the phosphor and the phosphor in the organic binder. It is characterized in that at least acicular substances having a rate are dispersed. In the present invention, since the acicular material is dispersed in the light emitting layer, the acicular material serves as a charge supply source, and high energy electrons can be efficiently collided with a desired phosphor. Life and high efficiency can be achieved.
In addition, it is preferable to use a nanotube or a nanowire so that the needle-like substance has a shape in which a high electric field is likely to be generated and can be added to the light emitting layer. Specifically, a carbon nanotube, a metal nanotube, a metal Examples thereof include nanowires. Among them, carbon nanotubes have a structure that easily concentrates the electric field, has a high melting point, and is a stable structure. Therefore, carbon nanotubes can function stably as a charge supply source for a long time, and can be mass-produced. Therefore, it is a suitable material for use as the acicular material of the present invention. In the present invention, the nanotube and the nanowire may be mixed and dispersed in the light emitting layer.
Here, the nanotubes are those having an inner diameter of several hundreds of nanometers to several hundreds of nanometers, an outer diameter of several hundreds of nanometers to several hundreds of nanometers, and a length of several nanometers to several millimeters. Nanowires have a diameter of several nanometers. It refers to those having nm to several hundred nm and length: several tens of nm to several mm.
As for the amount of the acicular substance added, if 10% or more of the total volume of the light emitting layer is added, the light emitted from the phosphor is absorbed or scattered by the acicular substance and cannot be efficiently extracted outside. Or the needle-like substance becomes a conductive path and the electric field is no longer applied to the light emitting layer. On the other hand, when the addition amount is 0.1% or less of the total volume of the light emitting layer, there are few acicular substances and many electric field concentration points are not formed, so that high light emission intensity cannot be obtained. Therefore, it is preferable to add the acicular substance within a range in which such a problem does not occur. Specifically, the acicular shape is such that the volume ratio is 0.1 to 10% of the total volume of the light emitting layer. It is preferable to add a substance.

  According to the present invention, it is possible to provide a dispersion type EL element capable of emitting light with a long lifetime and high efficiency by providing a needle-like charge supply source in the light emitting layer. In addition, since long-life and high-efficiency light emission is possible with a desired phosphor, according to the present invention, the dispersion-type EL element can select various phosphor materials and emit various colors.

In the present invention, a charge concentration point is generated by dispersing a needle-like substance in a light emitting layer as a charge supply source, so that high energy electrons or holes can be generated with high efficiency. The needle-shaped substance is preferably a highly conductive nanotube or nanowire in order to provide an electric field concentration point efficiently. Among them, the carbon nanotube has a structure in which an electric field is easily concentrated, and has a melting point. Since it is high and stable, it is also a substance that has been studied as an electron source for field emission display (FED). In the present invention, the acicular substance is dispersed in the light emitting layer as shown in FIG. 1, so that a high electric field is generated in a portion in contact with the acicular substance, and electrons and holes are supplied to the phosphor. It emits light.
<Embodiment>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

  As shown in FIG. 1, the dispersion type EL element of the present invention protects the back electrode 1, the dielectric layer 2, the light emitting layer 3, the transparent electrode 4, the transparent substrate 5, the conductive wire 6 and the element from moisture. The moisture-proof layer 7 is provided.

The back electrode 1 may be any conductive material, and specifically includes aluminum, vanadium, cobalt, nickel, tungsten, silver, gold and the like. In addition, when a transparent and highly conductive material such as ITO, tin oxide (SnO ₂ ), or zinc oxide (ZnO) is used, a transparent dispersed EL element can be manufactured.
Examples of the dielectric layer 2 include a dispersion type in which dielectric particles are dispersed in an organic binder, and a thin film type in which a dielectric thin film is directly formed by sputtering or the like. Examples of the dielectric used for the dielectric layer 2 include SiO ₂ , SiN _x , SiO _x N _y , TiO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , SiAlON, Ta ₂ O ₅ , Y ₂ O ₃ , and HfO _2. , BaTiO ₃ , S ₃ O ₃ , Ta _x Sn _y O _z , ZrO ₂ , BaTa ₂ O ₆ , PbNb ₂ O ₆ , SrTiO ₃ , PbTiO _3, or a solid solution in which an element other than the above constituent elements is dissolved. Is exemplified.

  Regarding the dispersion type, the dielectric particles 8 made of the above dielectric are dispersed in an organic solvent such as dimethylformamide or isopropyl alcohol in an organic binder having a high dielectric constant such as cyanoethyl cellulose or cyanoethyl saccharose, and the liquid is dispersed. It is formed by applying on the back electrode 1, the light emitting layer 3, or the transparent electrode 4 using a doctor blade method, a screen printing method, a spin coating method, or the like.

  On the other hand, in the thin film type, the dielectric thin film may be formed on the back electrode 1, the light emitting layer 3, or the transparent electrode 4 by sputtering, CVD (Chemical Vapor Deposition), vapor deposition, or the like. The dielectric thin film may be formed by directly spraying the dielectric particles having a particle size of several μm or less on the back electrode 1, the light emitting layer 3, or the transparent electrode 4 by using an aerosol deposition method. The thickness of the dielectric layer 2 is preferably 0.1 μm to 100 μm.

  The light emitting layer 3 includes at least a phosphor 9 and an acicular substance 10 in an organic binder having a high dielectric constant such as cyanoethyl cellulose and cyanoethyl saccharose. The organic binder, the acicular substance, and the like are added to an organic solvent such as dimethylformamide. The liquid in which the phosphor is dispersed is formed on the back electrode 1, the dielectric layer 2, or the transparent electrode 4 by using a doctor blade method, a screen printing method, a spin coating method, or the like. In addition, as a film thickness of a light emitting layer, it is preferable that they are 0.1 micrometer-100 micrometers.

The phosphor 9 may be any phosphor that emits EL when an electric field is applied. Examples of inorganic substances include II-VI group compound semiconductors, III-V group compound semiconductors, and IV group compound semiconductors. , Group I-VI compound semiconductor, Group I-VII compound semiconductor, Group II-V compound semiconductor, Group II-VII compound semiconductor, Group III-VI compound semiconductor, Group IV-IV compound semiconductor, etc., or Group VI can be mentioned a semiconductor or the like, _Ca 2 as a specific example of these phosphors _{(PO 4) 2 · Ca (} F, Cl) 2, BaMgAl 10 O 17, ZnSiO 4, LaPO 4, YBO 3, Y 2 O ₃ , Y ₂ O ₂ S, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, CaS, SrS, GaAs, GaN, GaAlAs, Ga _{P, InP, InN, AlN,} SiO 2, BaAl 2 S 4, Y 3 A 15 O 12, ZnO, Si, SiGe, InAs, Zn 2 SiO 4, (Y, Gd) BO 3, Zn 3 (PO 4) ₂ and ZnWO ₄ are exemplified.

Also, a so-called doped phosphor in which at least one selected from manganese, rare earth elements and other elements is added to the above compound may be used. In this case, dope ions contained in the matrix emit light with the above compound as the matrix. The type of doped ions in this case is not particularly limited, but cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, manganese, lead, titanium , Chlorine, potassium, tin, bismuth, Tl, silver, chromium, gallium, gold, indium, iron, VO43-, Yb, nickel, copper, aluminum, titanium, LnF3, TbF3, F, and the like. Also, two or more of these ions may be doped at the same time.
Further, the type of the luminescent dye is not particularly limited, and examples thereof include phthalocyanine dyes, azo dyes, and perylene dyes.

  Furthermore, the type of the conductive polymer having light emission is not particularly limited, but polyparaphenylene polymer, polyparaphenylene vinylene polymer, polythiophene polymer, polyaniline polymer, polypyrrole. Examples thereof include polymer-based polymers, polyvinylcarbazole-based polymers, and copolymers containing them.

  Further, the surface of the phosphor 9 may be coated with an organic compound / inorganic compound coordinated, adsorbed or leaf-bonded in order to suppress surface defects serving as a light emitting killer and improve carrier confinement. Examples of types of organic compounds for the coating layer include thiol compounds, amine compounds, phosphoric acid compounds, etc. Trialkyl phosphine oxides such as tributyl phosphine oxide and trialkyl phosphines such as trioctyl phosphine. And alkylamines such as dodecylamine and hexadecylamine, alkylthiols such as hexanethiol, and thiocresol. In addition, other conductive ligands such as thiophenes, phenylenes, phenylene vinylenes, pyrroles, and carbazoles may be used.

On the other hand, for the inorganic compound, the coating layer may be anything as long as it can coat the phosphor surface, but in order to efficiently confine carriers in the phosphor, it is coated with a semiconductor wider than the phosphor band gap, The doped phosphor is preferably covered with a material that is a base material. _{Further, SiO 2, SiN x, SiO} X N y, TiO 2, Al 2 O 3, Si 3 N 4, SiAlON, Ta 2 O 5, Y 2 O 3, HfO 2, BaTiO 3, S 2 O 3, Ta _x Sn _y O _z , ZrO ₂ , BaTa ₂ O ₆ , PbNb ₂ O ₆ , SrTiO ₃ , PbTiO ₃ , or a dielectric in which an element other than the above constituent elements is dissolved may be coated.

  The particle size of the phosphor is not particularly limited, but the phosphor that exhibits a quantum confinement effect by forming nanoparticles in the phosphor and improves the emission luminance is the nanoparticle size. It is preferable to use those. In addition, since the band gap is changed by using nanoparticles, the emission color can be controlled by controlling the particle size. The quantum confinement effect varies depending on the substance, but is manifested in a size of about several tens of nm or less. In addition, since the nanoparticles are transparent to visible light, by making the light emitting layer transparent, the light can be efficiently extracted outside without being scattered by the light emitting layer. Thus, a transparent light emitting element can be provided.

  Nanotubes or nanowires can be used for the needle-like material 10. The nanotubes have an inner diameter of 0.4 to 100 nm, an outer diameter of 0.4 to 100 nm, a length of 10 nm to 1 mm, and the nanowire size. The diameter is preferably 1 nm to 100 nm and the length is preferably 10 nm to 1 mm.

  When a nanotube is used, a carbon nanotube, a metal nanotube, a metal nanowire, etc. can be mentioned.

  When carbon nanotubes are used, there are metallic ones and semiconducting ones depending on the difference in structure. In the present invention, any structure having a higher conductivity than phosphors can be used. May be.

  Examples of the carbon nanotube include a single-walled carbon nanotube whose wall surface is a single wall, a multi-walled carbon nanotube whose wall surface is composed of a plurality of layers, and a graphite nanofiber in which a graphene sheet is laminated to form a cylindrical structure. However, in the present invention, any type of carbon nanotube may be used as long as it has a higher conductivity than the phosphor.

  As for the above-mentioned carbon nanotube production method, CVD method for producing carbon nanotubes from hydrocarbon gas using a metal catalyst, arc discharge method for producing carbon nanotubes by arc discharge of a carbon electrode, high-pressure carbon vapor by striking a graphite rod with a laser And a carbon ablation method in which carbon nanotubes are grown by a collecting device. The present invention can also be used for carbon nanotubes produced by any of the methods described above.

  In addition, boron nitride nanotubes, Si nanowires, and the like have a structure in which an electric field is easily concentrated, and have a high melting point and are stable, so that they can be used as the needle-like substance of the present invention.

  Also, as metal nanotubes, metal ions are attached to the hydrophilic part side of the micelle body, cooled, converted into a liquid crystal state, and then reduced to produce metal nanotubes having an outer diameter of several nanometers to several tens of nanometers. It is known that metal nanotubes produced as described above may be used in the present invention.

  Furthermore, a method for synthesizing metal nanowires such as gold, silver, and copper has been reported as a publicly known technique in Japanese Patent Application Laid-Open No. 2002-266007, but the present invention may use the metal nanowires. Note that a mixture of the nanotube and the nanowire may be used as the acicular substance 10.

The transparent electrode 6 is preferably made of a light-transmitting material in order to extract light. Specifically, the composite oxide ITO of indium and tin, tin oxide (SnO2), zinc oxide (ZnO) is used. Etc. The transparent electrode 6 is made of PET or polycarbonate (PC: Poly
Carbonate), polyolefin (PO: Poly Olefin) and polyethersulfone (PES: Poly)
Eter Sulphone) or the like or a transparent substrate 5 such as glass is formed using a vacuum deposition method, a sputtering method, or the like.

  The moisture-proof layer 7 is a substance that is difficult for moisture to permeate, and preferably has an insulating property. Specific examples thereof include a plastic film having moisture-proof properties such as glass or PET.

  As shown in FIGS. 2 to 4, the dispersion type EL device according to the present invention is formed by forming a dielectric layer 2 on the back electrode 1 (in the case of using the dispersion type, a doctor blade method, a screen printing method, a spin method, or the like). If a thin film type is used using a coating method or the like, a sputtering method, a CVD method, a vapor deposition method or the like is used.) A transparent electrode 4 and a light emitting layer 3 are formed on a transparent substrate 5, and these two are pressed by a roller. After forming the conducting wire 6 by pressure bonding or the like, it may be formed by further sealing the periphery with a moisture-proof layer 7, or forming the transparent electrode 4 directly on the light emitting layer 3 as shown in FIG. After forming the conductive wire 6, the periphery thereof may be sealed with a moisture-proof layer 7.

  Further, as an example of the form of the dispersion type EL element of the present invention other than that shown in FIG. 1, a light emitting layer 3 is formed on a back electrode 1 and a transparent dielectric layer 2 is formed thereon as shown in FIG. A structure in which a dielectric thin film is formed and a transparent electrode 4 is further formed thereon, a structure in which the light emitting layer 5 is sandwiched between the dielectric layers 2 as shown in FIG. 7, and a glass or plastic as shown in FIG. A structure in which a rear substrate 11 made of ceramic, metal, or the like is provided and the rear electrode 1 is formed thereon can be exemplified.

  Furthermore, by using the dispersion type EL element of the present invention as a display, a display that emits light with high efficiency and a long lifetime can be provided. An example of the configuration is shown in FIG.

  Dielectric layers 23 and 25 having the same structure as that of the dielectric layer 2 between the back electrode 22 formed on the back substrate 21 and the electrodes in which the transparent electrodes 25 are wired in the X direction and the Y direction perpendicular to each other, The light emitting layer 24 having the same structure as that of the light emitting layer 3 sandwiched between the dielectric layers 23 and 25 is provided, and a place where the back electrode 22 and the transparent electrode 25 intersect is one pixel. In the case of producing a full-color display, it is possible to separately coat the phosphor on one electrode at each of the RGB locations. Regarding the types of phosphors used for full color, since the present invention can emit light with a desired phosphor, R (red), G (green), and B (blue) are emitted from each of the phosphors described above. What is necessary is just to select a thing, and when using the nanoparticle from which a luminescent color changes by a quantum confinement effect, particle size control should just be performed and a luminescent color should be controlled. As a display driving method, in addition to simple matrix driving as shown in FIG. 8, active matrix driving using TFTs may be performed.

  In the present invention, a flexible substrate such as an aluminum foil is used as the back substrate 21. Although not shown, when a transparent substrate is present on the transparent electrode 22, a flexible polymer polymer such as PET is used as the transparent substrate. If a system material is used, a flexible display can be provided. Further, the dispersion type EL element of the present invention can produce a display without using a large-scale apparatus such as a vacuum apparatus, so that the screen can be easily enlarged and the display can be inexpensive.

  In addition to the above-described display, by using the present invention for illumination, it is possible to provide illumination that emits light with high efficiency and long life. Since the present invention has a wider selection of phosphor materials and can emit a variety of colors compared to conventional dispersion type EL elements, it is possible to provide illumination that emits more types of colors. Become. For example, when used as white illumination, for example, color conversion that mixes phosphor particles that emit RGB colors, or emits yellow light that is complementary to blue when excited by blue phosphor and blue light. What is necessary is just to mix the fluorescent substance which carries out. Since the dispersion type EL element of the present invention can be manufactured without using a large-scale apparatus in the manufacturing process of a vacuum apparatus or the like, it is easy to enlarge the screen and can provide inexpensive illumination. For this reason, it is possible to easily provide large-area illumination for the above reasons. For example, if the distributed EL element of the present invention is applied to a ceiling or a wall, it can be used as interior illumination, or a large-screen liquid crystal display. It can also be used as a backlight.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following.

  In this embodiment, the dispersion type EL element of the present invention is used as a lighting device.

  In this embodiment, an aluminum foil is used for the back electrode 1 in FIG. 1, and cyanoethyl cellulose (binder) and alumina powder (dielectric powder 8) are used as the dielectric layer 2 in a weight ratio binder: alumina powder = 10: 8. So that the mixture is mixed. The dielectric layer 2 is formed by dispersing a binder and alumina powder in dimethylformamide, which is an organic solvent, and applying the film to a thickness of 20 μm with a doctor blade. PET is used for the transparent substrate 5, and the transparent electrode 4 is formed on the transparent substrate 5 using ITO by sputtering. For the light emitting layer 3, cyanoethyl cellulose is used as the binder, ZnS: Mn is used as the phosphor powder, and carbon nanotubes produced by the CVD method are used as the acicular material 10. The light emitting layer 3 is mixed so that the weight ratio of the light emitting layer 3 is binder: phosphor powder: carbon nanotube = 3.0: 1.0: 0.1 (volume ratio of carbon nanotube: about 2%). The light-emitting layer 3 is formed by dispersing the binder, the phosphor powder, and the carbon nanotubes in dimethylformamide, which is an organic solvent, so as to have the mixing ratio, and forming a film on the transparent electrode 4 using a doctor blade method. The coating is performed so that the thickness becomes 60 μm.

  As shown in FIGS. 2 to 4, the dispersion type EL element of this example has a roller on the back electrode 1 side on which the dielectric layer 2 is formed and the transparent substrate 5 side on which the transparent electrode 4 and the light emitting layer 3 are formed. After using and crimping | bonding together by the pressure of about 2.0 kgf and integrally bonding and forming the conducting wire 6, it sandwiches from the upper and lower sides with the PET film used as the moisture-proof layer 7, this is hot-pressed and produced by thermocompression bonding.

  By forming an AC electric field as described above, a flexible lighting device that emits light with a long lifetime and high efficiency can be provided.

  In this example, the dispersion type EL element of the present invention is used as a display. This embodiment is a simple matrix drive display. In FIG. 9, the back substrate 21 is glass, and the dielectric layers 23 and 25 are alumina thin films. The light emitting layer 24 has the same composition as the light emitting layer of Example 1.

  The method of forming the display of this example is as follows. After forming an aluminum thin film on the back substrate 21 by vapor deposition, patterning is performed by ordinary etching using a photoresist to form the back electrode 22 having the pattern shown in FIG. Then, an alumina thin film having a thickness of about 10 μm is formed thereon as a dielectric layer 23 by a sputtering method, and a light emitting layer 24 is further formed thereon by a doctor blade method in the same manner as in the first embodiment. On the other hand, an ITO film is formed on a PET film that becomes a transparent substrate (not shown) by sputtering, and patterning is performed by normal etching using a photoresist, resulting in the pattern shown in FIG. Thus, the transparent electrode 25 is formed. Then, an alumina thin film having a thickness of about 10 μm is formed thereon by sputtering. Finally, as shown in FIG. 4, the back electrode side and the transparent electrode side are pressed and bonded together with a roller at a pressure of about 2.0 kgf, and then a conductor 6 for connection to the drive IC is formed. It is sandwiched from above and below with a moisture-proof film, and is heat-pressed and thermocompression bonded.

  A display that emits light with a long lifetime and high efficiency can be provided by forming an AC electric field as described above.

It is sectional drawing of the dispersion type EL element which concerns on this invention. It is a figure which shows the process of the manufacturing method of the dispersion type EL element which concerns on this invention. It is a figure which shows the process of the manufacturing method of the dispersion type EL element which concerns on this invention. It is a figure which shows the process of the manufacturing method of the dispersion type EL element which concerns on this invention. It is sectional drawing of the dispersion-type EL element which is an example of other embodiment of this invention. It is sectional drawing of the dispersion-type EL element which is an example of other embodiment of this invention. It is sectional drawing of the dispersion-type EL element which is an example of other embodiment of this invention. It is sectional drawing of the dispersion-type EL element which is an example of other embodiment of invention. It is a figure at the time of using the dispersion type EL element of invention as a display. It is sectional drawing of the conventional dispersion-type EL element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Back electrode 2 Dielectric layer 3 Light emitting layer 4 Transparent electrode 5 Transparent substrate 6 Conductor 7 Moisture-proof layer 8 Dielectric particle 9 Phosphor particle 10 Acicular substance 11 Back substrate 21 Back substrate 22 Back electrode 23 Dielectric layer 24 Light emitting layer 25 Dielectric layer 26 Transparent electrode 101 Back electrode 102 Transparent substrate 103 Transparent electrode 104 Phosphor particle 105 Light emitting layer 106 Dielectric particle 107 Dielectric layer 108 Conductive wire 109 Moisture-proof layer

Claims (3)

In a dispersive electroluminescent (EL) element in which a light emitting layer and a dielectric layer are interposed between a transparent electrode and a back electrode,
The light-emitting layer is a dispersion type EL device in which a phosphor and an acicular material having a higher conductivity than the phosphor are dispersed in an organic binder. The dispersive EL device according to claim 1, wherein the acicular material includes carbon nanotubes. 3. The dispersion type EL device according to claim 1, wherein a volume of the acicular substance in the light emitting layer is 0.1 to 10% of a total light emitting layer volume.

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