JP2010244686A - Dispersion-type electroluminescence device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersion-type electroluminescence device excellent in emission luminance, improved in service life, and suitable to white light emission. <P>SOLUTION: The dispersion-type electroluminescence device includes at least a light-emitting layer provided between a pair of electrodes consisting of a back electrode and a transparent electrode, wherein the light-emitting layer contains two kinds of phosphor particles having a Cu content of 0.10 to 0.16 mol% and 0.03 to 0.08 mol%, respectively. It is preferable that an average size of the phosphor particles is ≥1 μm and <20 μm with a variation coefficient of the particle size of ≥3% and <40%. Further, a red conversion material may be included in any internal part in the device layer, or phosphor particles emitting red light other than the phosphor particles cited above may be contained in the light-emitting layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dispersion-type EL element (hereinafter also referred to as an EL element) having a light-emitting layer in which electroluminescent (EL) powder particles having high luminance and long life are dispersed and applied.

The EL phosphor is a voltage excitation type phosphor, and a dispersion type EL device and a thin film type EL device are known in which the phosphor powder is sandwiched between electrodes and used as a light emitting device. The general shape of a dispersion-type EL element consists of a structure in which phosphor powder is dispersed in a binder with a high dielectric constant, and at least one is sandwiched between two transparent electrodes. Light is emitted by applying an electric field. A light-emitting element manufactured using EL phosphor powder can have a thickness of several millimeters or less, is a surface light emitter, has a number of advantages such as low heat generation and good light emission efficiency. Applications are expected for various interior and exterior lighting, light sources for flat panel displays such as liquid crystal displays, and illumination light sources for large areas.
However, light-emitting devices manufactured using phosphor powder have the disadvantages of lower emission luminance and shorter emission lifetime than light-emitting devices based on other principles, and various improvements have been attempted in the past. I came.

In order to realize white light emission in a conventional dispersion type electroluminescence element, the following two methods are generally taken.
(1) ZnS: Cu, Cl, Mn activated phosphors emitting orange light and ZnS: Cu, Cl activated phosphors emitting blue-green light were mixed.
(2) A blue-green light emitting ZnS: Cu, Cl phosphor absorbs this light, and a rhodamine-based fluorescent dye solid dispersion that emits light near 580 nm is mixed into the phosphor layer to emit white light.
In both cases, blue-green light emitting ZnS: Cu, Cl phosphor particles are used, but the light emission has a wide light emission from the blue region to the green region, which is convenient for obtaining white light emission with high color reproducibility. In addition, when used as a blue-green EL element such as a shining license plate, its wide emission spectrum is commercially useful, such as high visibility. However, it has been regarded as a problem that its deterioration is fast.

  Furthermore, as a method for increasing the emission luminance, a method using phosphor particles having a small size is known (Patent Documents 1 and 2). When an EL device is configured using phosphor particles having a small size, the number of phosphor particles per unit volume in the light emitting layer can be increased, and as a result, the luminance of the EL device can be increased.

JP 2002-235080 A JP 2004-265866 A

However, an EL element using phosphor particles having a small size has a disadvantage that luminance is deteriorated quickly.
Accordingly, an object of the present invention is to provide a dispersive EL element having excellent light emission luminance and improved lifetime. Furthermore, another object of the present invention is to provide a dispersion type EL element suitable for white light emission.

  As a result of intensive studies by the present inventors, it has at least two types of phosphor particles each containing Cu at a concentration of 0.10 to 0.16 mol / mol Zn and 0.03 to 0.08 mol / mol Zn. The present inventors have found that it is possible to provide a dispersive electroluminescent device that can achieve a long lifetime while maintaining high luminance, and have achieved the present invention.

That is, the present invention is achieved by the following requirements.
(1) A dispersion type electroluminescent device having at least a light emitting layer between a pair of electrodes consisting of a back electrode and a transparent electrode, wherein the light emitting layer has a Cu content of 0.10 to 0.16 mol% and 0.03. A dispersion type electroluminescent device comprising two kinds of phosphor particles each contained at a concentration of ˜0.08 mol%.
(2) The dispersion type electroluminescent device according to (1), wherein the average particle size of the phosphor particles is 1 μm or more and less than 20 μm, and the variation coefficient of the particle size is 3% or more and less than 40%.
(3) The dispersion-type electroluminescence device according to (1) or (2), wherein a red conversion material is contained in any of the layers of the dispersion-type electroluminescence device.
(4) The dispersion type electroluminescent device according to any one of (1) to (3), wherein the red color conversion material layer containing the red color conversion material is located between the light emitting layer and the back electrode.
(5) The dispersive electroluminescent element as described in (1) or (2), wherein the phosphor layer contains phosphor particles that emit red light separately from the phosphor particles.
(6) The dispersion type electroluminescent device as described in (5), wherein the phosphor particles emitting red light have an average particle size of 1 μm or more and less than 20 μm, and a particle size variation coefficient of 3% or more and less than 40%.
(7) A gas barrier comprising a polymer of a monomer composition having at least one inorganic layer and at least one organic layer on the base film, wherein the organic layer contains at least one phosphate ester acrylate. The dispersive electroluminescence device according to (1), which is sealed with a conductive laminated film.
In the present invention, the phosphor particles mean those that emit light when a voltage is applied.

  The dispersion type EL element of the present invention achieves both high luminance and long life. Moreover, when trying to obtain white light emission in combination with a red material, it exhibits excellent color reproducibility (color rendering).

The present invention will be described in detail below.
<Phosphor particles>
Specifically, phosphor particles preferably used in the present invention include one or more elements selected from the group consisting of Group II elements and Group VI elements, Group III elements and Group V elements, These are semiconductor particles composed of one or more elements selected from the group consisting of, and are arbitrarily selected depending on the necessary emission wavelength region. Examples thereof include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, CaS, SrS, GaP, and GaAs. Of these, ZnS, CdS, CaS and the like are preferably used.

  The phosphor fine particles in the present invention can be formed by a firing method (solid phase method) widely used in the industry. For example, in the case of zinc sulfide, a fine particle powder (usually called raw powder) of 10 nm to 50 nm is prepared by a liquid phase method, and this is used as a primary particle, that is, a base material. There are two types of zinc sulfide, a high-temperature stable hexagonal system and a low-temperature stable cubic system, and any of them may be used or may be mixed. This is fired in a crucible at a high temperature of 900 ° C. to 1300 ° C. for 30 minutes to 10 hours with both impurities called activator and coactivator, and intermediate phosphor particles are obtained. A preferable firing temperature is 950 ° C. to 1250 ° C., more preferably 1000 ° C. to 1200 ° C., in order to obtain a phosphor particle having a suitable average particle size and low coefficient of variation in particle size. In the present invention, the average particle size is preferably 1 μm or more and less than 20 μm, and the particle size variation coefficient is preferably 3% or more and less than 40%. Moreover, preferable baking time is 30 minutes-6 hours, More preferably, it is 1 hour-4 hours. Moreover, as a flux, it is preferable to use 20 mass% or more. Furthermore, 30 mass% or more is preferable and 40 mass% or more is more preferable. The ratio of the flux here is represented by the ratio (mass%) of the flux = mass of the flux / (mass of the raw material phosphor primary particles + the mass of the flux). For example, in the case where copper, which is an activator, is mixed in the raw powder in advance, such as a copper-activated zinc sulfide phosphor described later, the activator copper is also integrated with the phosphor raw material powder. In such a case, the mass of the phosphor raw material powder including copper is measured.

The mass of the flux may differ from the mass at room temperature and the mass at the firing temperature. For example, barium chloride exists in the state of BaCl ₂ · 2H ₂ O at room temperature, but it is considered that water of hydration is lost at the firing temperature and becomes BaCl ₂ . However, the ratio of the flux here is calculated based on the mass of the flux in a stable state at room temperature.

  Cu is used as the activator in the present invention, and the Cu source is not limited, but copper sulfate, copper sulfide, copper chloride, copper bromide and the like are used. In the present invention, at least two kinds of phosphors having different Cu concentrations are used as the activator. One is a high-concentration Cu-containing phosphor having a Cu concentration of 0.10 to 0.16 mol% as an activator, and the other is a low-concentration Cu-containing phosphor having a concentration of 0.03 to 0.08 mol%. .

In the phosphor particles in the present invention, zinc sulfide is preferably used as a base material. In general, Cu in a zinc sulfide phosphor forms a blue emission center called B-Cu and a green emission center called G-Cu, and two types of emission centers exist in one zinc sulfide. Since this was formed unintentionally, it was difficult to control the generation ratio, and the emission color could not be controlled. As a result of intensive studies by the present inventors, phosphors having only B-Cu (low Cu concentration phosphors) and phosphors containing only G-Cu (high Cu concentration phosphors) are prepared, and the mixing ratio is optimized. As a result, we succeeded in realizing the same luminescent color as before. Moreover, by making and mixing the emission centers as in the present invention, not only is the deterioration significantly suppressed as compared with the conventional phosphor containing two types of emission centers in one particle, but also surprisingly It was newly found that the lifetime of each single particle can be extended. Furthermore, when there are two types of emission centers in one phosphor particle as in the past, there is a drawback that the color changes by changing the frequency at the time of driving the EL element. In some cases, the range of driving conditions must be narrowed. Since the present invention makes two types of phosphors separately, no difference in emission color due to such driving conditions is observed, and good white light emission can be obtained under any conditions.
The emission color equivalent to the conventional one means that the half width of the emission spectrum is wide and the color reproducibility is excellent. Here, the full width at half maximum means a wavelength difference at both ends of the wavelength at which the emission intensity is 0.5, assuming that the emission peak of the emission spectrum is 1. In the present invention, 82 nm or more is preferable, and 85 nm or more is more preferable. However, if the full width at half maximum is too wide, the emission intensity decreases, so that it is preferably 105 nm or less, more preferably 103 nm or less.

Regarding the high Cu concentration phosphor, when the Cu concentration is higher than 0.16 mol%, Cu that cannot be fully doped in the particles is deposited on the surface of the particles, and the surface is colored. When the amount is less than 0.10 mol%, the amount of G-Cu luminescent center produced is undesirably small. The content is preferably 0.11 to 0.15 mol%, more preferably 0.120 to 0.140 mol%.
Regarding the low Cu concentration phosphor, when the Cu concentration is less than 0.03 mol%, the emission center is difficult to be formed, and the emission luminance is greatly reduced. When the amount is more than 0.08 mol%, the amount of B-Cu emission center produced is undesirably reduced. The content is preferably 0.04 to 0.07 mol%, more preferably 0.05 to 06 mol%.

  As will be described later, when white light emission is to be obtained in combination with a red material, the mixing ratio of the low Cu concentration phosphor and the high concentration Cu concentration phosphor is preferably 5/95 to 35/65 by weight. Thereby, white light emission with high color rendering properties can be obtained. The mixing ratio is preferably 10/90 to 32/68, more preferably 12/88 to 30/70.

  About Cu content, it can adjust by adjusting the mixing amount of Cu source mixed with raw flour.

  Furthermore, in this invention, in order to remove the excess activator, coactivator, and flux which are contained in the intermediate | middle fluorescent substance powder obtained by the said baking, it is preferable to wash | clean with ion-exchange water.

  A naturally occurring planar stacking fault (twin crystal structure) exists inside the intermediate phosphor particles obtained by firing. Further, by applying an impact force in a certain range, the density of stacking faults can be greatly increased without destroying the particles. Conventionally known methods for applying an impact force include a method in which intermediate phosphor particles are brought into contact with each other, spheres such as alumina are mixed and mixed (ball mill), or particles are accelerated to collide. In particular, in the case of zinc sulfide, there are two crystal systems, a cubic system and a hexagonal system. In the former, the close-packed atomic plane ((111) plane) has a three-layer structure of ABCABC. The close-packed atomic planes perpendicular to each other form a two-layer structure of ABAB. For this reason, when an impact is applied to the zinc sulfide crystal with a ball mill or the like, slip of the close-packed atomic plane occurs in a cubic system, and when the C plane is removed, ABAB hexagonal crystals are partially formed, and edge dislocations occur. In addition, the AB plane may be reversed to form twins. In general, since impurities in the crystal are concentrated in lattice defect portions, when zinc sulfide having stacking faults is heated and an activator such as copper sulfide is diffused, it precipitates in stacking faults. Since the interface between the deposited portion of the activator and the base zinc sulfide is the center of the electroluminescent luminescent material, it is preferable in the present invention that the density of stacking faults is high in order to improve the luminance.

Next, the obtained intermediate phosphor powder is subjected to a second firing. In the second time, heating (annealing) is performed at a temperature lower than that of the first time at 500 ° C. to 800 ° C. and for a short time of 30 minutes to 3 hours. Thereby, an activator can be concentrated on a stacking fault.
Thereafter, the intermediate phosphor is etched with an acid such as hydrochloric acid to remove the metal oxide adhering to the surface, and the copper sulfide adhering to the surface is removed by washing with KCN or the like. Subsequently, drying is performed to obtain an electroluminescent phosphor.
By such a method, particles having an average particle size of 1 μm or more and less than 20 μm and a particle size variation coefficient of 3% or more and less than 35% can be obtained.

  Other phosphor formation methods include laser ablation, CVD, plasma, sputtering, resistance heating, electron beam, etc. A liquid phase method such as a method, a precursor thermal decomposition method, a reverse micelle method, a method combining these methods with high-temperature baking, a freeze-drying method, a urea melting method, a spray pyrolysis method, or the like can also be used. .

  About the measuring method of Cu content, fluorescent substance particle | grains can be melt | dissolved in hydrochloric acid, nitric acid, and aqua regia, and content can be quantified using ICP analysis (induction plasma emission analysis).

  For the measurement of the average particle size and the particle size variation coefficient of the phosphor particles of the present invention, for example, a method using laser scattering such as a laser diffraction / scattering particle size distribution measuring apparatus LA-920 manufactured by Horiba, Ltd. can be used. Here, the average particle size refers to the median diameter.

The phosphor particles of the present invention are preferably zinc sulfide containing copper as an activator, and further preferably contain at least one metal element belonging to the second transition series from Group 6 to Group 10. Of these, molybdenum, platinum, and iridium are preferable. These metals are preferably contained in zinc sulfide in the range of 1 × 10 ⁻⁷ mol to 1 × 10 ⁻³ mol with respect to 1 mol of zinc sulfide, and 1 × 10 ⁻⁶ mol to 5 × 10 ⁻⁴ mol. More preferably it is included. These metals are added to deionized water together with zinc sulfide fine powder and a predetermined amount of copper sulfate, made into a slurry, mixed well, dried, and then baked with a coactivator and flux to sulfidize. Although it is preferable to make it contain in a zinc particle, it is also preferable to mix the complex powder containing these metals with a flux, and calcinate using this coactivator and a flux, and to make it contain in a zinc sulfide particle. In any case, any compound containing a metal element to be used can be used as a raw material compound when adding a metal. More preferably, a complex in which oxygen or nitrogen is coordinated to a metal or metal ion is used. It is preferable to use it. The ligand may be an inorganic compound or an organic compound. As a result, it is possible to further improve the luminance and extend the lifetime.

  The phosphor particles may have a non-light emitting shell layer on the surface of the particles. Details of the non-light emitting shell layer are as described in JP-A-2005-283911, [0028] to [0033].

<Light emitting layer>
When an EL device is produced using these phosphor particles, these particles are dispersed in an organic dispersion medium, and the dispersion is applied to form a light emitting layer.
As the organic dispersion medium, an organic polymer material or an organic solvent having a high boiling point can be used, but an organic binder mainly composed of the organic polymer material is preferable.
The organic binder is preferably a material having a high dielectric constant, such as a fluorine-containing polymer compound (for example, a polymer compound containing ethylene fluoride, trifluoride monochloride as a polymerization unit), or a polysaccharide having a hydroxyl group cyanoethylated. (Cyanoethyl pullulan, cyanoethyl cellulose), polyvinyl alcohol (cyanoethyl polyvinyl alcohol), phenol resin, polyethylene, polypropylene, polystyrene resin, silicone resin, epoxy resin, vinylidene fluoride, and all or part of them Preferably it comprises. In addition, the dielectric constant can be adjusted by appropriately mixing fine particles having a high dielectric constant such as BaTiO ₃ and SrTiO ₃ with these binders.
As a method for dispersing the phosphor particles in the binder, a homogenizer, a planetary kneader, a roll kneader, an ultrasonic disperser, or the like can be used.
The blending ratio of the binder and the phosphor particles is preferably such that the content of the phosphor particles in the light emitting layer is 30 to 90% by mass with respect to the entire solid content, and is 60 to 85. It is still more preferable to set it as the ratio used as the mass%. Thereby, the surface of the light emitting layer can be formed smoothly.
As the binder, it is particularly preferable to use a polymer compound in which the hydroxyl group is cyanoethylated in a mass ratio of 20% or more, more preferably 50% or more, in the organic dispersion medium of the entire light emitting layer.

  The thickness of the light emitting layer thus obtained is preferably 20 μm or more and less than 80 μm, more preferably 25 μm or more and less than 75 μm. When the thickness is 20 μm or more, favorable smoothness of the surface of the light emitting layer can be obtained, and when it is less than 80 μm, an electric field can be effectively applied to the phosphor particles, which is preferable. In particular, when a blocking layer described later is provided, by reducing the thickness of the insulating layer described later and increasing the thickness of the light emitting layer, it is possible to recover the decrease in initial luminance and to achieve a sufficient durability effect. Is preferable. Furthermore, in order to obtain a good initial luminance, the thickness of the light emitting layer is preferably 70 μm or less.

<Blocking layer>
The EL element of the present invention may have a blocking layer between the transparent electrode and the light emitting layer. Details of this blocking layer are as described in JP-A 2007-12466, [0013] to [0020].

<Insulating layer>
The EL element of the present invention preferably has an insulating layer between the back electrode and the light emitting layer.
As the insulating layer, any material can be used as long as it has a high dielectric constant and insulation and has a high dielectric breakdown voltage. These are selected from metal oxides and nitrides, such as BaTiO ₃ , KNbO ₃ , LiNbO ₃ , LiTaO ₃ , Ta ₂ O ₃ , BaTa ₂ O ₆ , Y ₂ O ₃ , Al ₂ O ₃ , AlON, etc. . These may be installed as a uniform film, or may be used as a film having a particle structure containing an organic binder. For example, Mat. Res. Bull. As described in Volume 36, page 1065, a film composed of BaTiO ₃ fine particles and BaTiO ₃ sol is used.
The film thickness is desirably 10 μm or more and less than 35 μm. More preferably, they are 12 micrometers or more and less than 33 micrometers, and 15 micrometers or more and less than 31 micrometers are still more preferable. If the film thickness is too thin, dielectric breakdown tends to occur, and if it is too thick, the voltage applied to the light-emitting layer is reduced, which is not preferable because the light emission efficiency is substantially lowered.

Examples of organic binders that can be used for the insulating layer include polymers having a relatively high dielectric constant such as cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, and cyanoethyl cellulose resins, polyethylene, polypropylene, polystyrene resins, silicone resins, epoxy resins, Examples thereof include resins such as vinylidene fluoride. The dielectric constant can be adjusted by appropriately mixing fine particles having a high dielectric constant such as BaTiO ₃ or 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.

<Red material>
In the electroluminescent device of the present invention, a light emitting material that emits red light is used in addition to two types of Cu-containing phosphor particles that emit blue and green light to produce white light emission. The red light-emitting material may be either an organic material that absorbs light emitted from two types of Cu-containing phosphor particles and converts it into red, or an inorganic material that exhibits red electroluminescence. The former is particularly preferably an organic fluorescent dye or fluorescent pigment, which may be dispersed in the light emitting layer or dispersed in the insulating layer, and between the light emitting layer and the transparent electrode or the light emitting layer relative to the transparent electrode. It may be located on the opposite side. The latter can be contained in the light-emitting layer as well as two types of Cu-containing phosphor particles emitting blue and green, and two types of Cu-containing phosphor emitting blue and green between the transparent electrode and the insulating layer. In addition to the light-emitting layer containing particles, it can also be introduced as a red inorganic phosphor material layer.
As the red-emitting inorganic phosphor particles preferably used in the present invention, the host material is selected from the group consisting of Group II elements and Group VI elements, similarly to the aforementioned phosphor materials emitting blue and green. And one or a plurality of elements selected from the group consisting of Group III elements and Group V elements, which are arbitrarily selected depending on the necessary emission wavelength region. Although it does not specifically limit as an activator, For example, co-activators are group VII elements, such as F, Cl, Br, I, Al, Ga, In, from transition metals, such as Cu and Mn. And so on. Furthermore, it is desirable that rare earth such as Ce, Eu, and Sm is also doped. Specifically, ZnS: Cu, In, CaS: Eu, Ce, etc. correspond to it.

Hereinafter, the red color conversion organic material will be described in detail.
In the electroluminescence device of the present invention, the red emission wavelength during white light emission is preferably 590 nm or more and 650 nm or less. In order to obtain a red emission wavelength included in this range, a red conversion material may be contained in the light emitting layer, placed between the light emitting layer and the transparent electrode, or placed on the opposite side of the light emitting layer around the transparent electrode. However, it is most preferable to contain it in the insulating layer. The insulating layer containing the red color conversion material is preferably a layer in which all of the insulating layers in the electroluminescent element of the present invention contain the red color conversion material. However, the insulating layer in the element is divided into two or more, and one of them. More preferably, the part is a layer containing a red color conversion material. The layer containing the red color conversion material is preferably located between the insulating layer not containing the red color conversion material and the light emitting layer, so that both sides of the layer containing the red color conversion material are sandwiched by the insulation layer not containing the red color conversion material. It is also preferred to position it.

When the layer containing the red color conversion material is positioned between the insulating layer not containing the red color conversion material and the light emitting layer, the layer containing the red color light emitting material is preferably 1 μm or more and 20 μm or less, more preferably 3 μm or more and 17 μm or less. is there. The concentration of the red conversion material in the insulating layer to which the red conversion material is added is preferably 1% by mass or more and 20% by mass or less, and more preferably 3% by mass with respect to dielectric particles represented by BaTiO _3. % To 15% by mass. When the layer containing the red conversion material is positioned so as to be sandwiched between the insulating layers not containing the red conversion material from both sides, the layer containing the red conversion material is preferably 1 μm or more and 20 μm or less, more preferably 3 μm or more and 10 μm or less. It is. The concentration of the red conversion material in the insulating layer to which the red conversion material is added is preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 20% by mass or less, based on the dielectric particles. It is. When the layer containing the red conversion material is positioned so as to be sandwiched between the insulating layers not containing the red conversion material from both sides, the layer containing the red light emitting material does not contain dielectric particles, and the high dielectric constant binder and the red conversion material It is also preferable to use only a layer.

  The emission wavelength when the red conversion material used here is in a powder state is preferably 590 nm or more and 750 nm or less, more preferably 600 nm or more and 650 nm or less, and most preferably 605 nm or more and 630 nm or less. is there. This red conversion material is added to the electroluminescence element, and the red emission wavelength at the time of electroluminescence emission is preferably 590 nm or more and 650 nm or less, more preferably 595 nm or more and 630 nm or less, and most preferably Is 600 nm or more and 620 nm or less.

  As a binder for the layer containing the red conversion material, a polymer having a relatively high dielectric constant such as cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose resin, polyethylene, polypropylene, polystyrene resin, silicone resin, epoxy resin, Resins such as vinylidene fluoride are preferred.

As the red color conversion material of the present invention, a fluorescent pigment or a fluorescent dye can be preferably used. Compounds having these luminescence centers are preferably compounds having rhodamine, lactone, xanthene, quinoline, benzothiazole, triethylindoline, perylene, triphenine, dicyanomethylene as the skeleton, and other cyanine dyes, azo dyes, polyphenylene vinylenes. It is also preferable to use a polymer, a disilane oligothienylene polymer, a ruthenium complex, a europium complex, or an erbium complex. These compounds may be used alone or in combination. Further, these compounds may be used after further being dispersed in a polymer or the like. As a fluorescent pigment having a light emission maximum in the above range, “SEL-1003”, “FA007”, etc. manufactured by Sinloihi Co., Ltd. can be used.
The fluorescent pigment or fluorescent dye can adjust the maximum emission wavelength within this range by using a filter such as a band reflection filter.

<Transparent electrode>
The transparent electrode is not only a glass substrate, but also a transparent film such as polyethylene terephthalate or triacetyl cellulose base, such as indium / tin oxide (ITO), tin oxide, antimony-doped tin oxide, zinc-doped tin oxide, or zinc oxide. It can be obtained by uniformly depositing and forming a transparent conductive material by a method such as vapor deposition, coating or printing.
Alternatively, a multilayer structure in which a silver thin film is sandwiched between high refractive index layers may be used. Furthermore, a conductive polymer such as a conjugated polymer such as polyaniline or polypyrrole can be preferably used.
These transparent conductive materials are described in “Current Status and Future of Electromagnetic Shielding Materials” published by Toray Research Center, Japanese Patent Laid-Open No. 9-147639, and the like.

  As the transparent electrode, a transparent conductive sheet or conductive polymer obtained by attaching and forming the transparent conductive material to the transparent film, a uniform mesh, a comb-shaped or grid-type metal, and the like It is also preferable to use a transparent conductive sheet in which a conductive surface on which a fine wire structure part of an alloy is arranged is formed to improve the conductivity.

In the case of using the fine wires as described above, copper, silver, nickel, and aluminum are preferably used as the material for the fine wires of the metal or alloy, but depending on the purpose, the above-mentioned transparent conductive material may be used instead of the metal or alloy. It may be used. A material having high electrical conductivity and high thermal conductivity is preferable. The width of the thin line is arbitrary, but is preferably between about 0.1 μm and 1000 μm. The fine wires are preferably arranged at a pitch of 50 μm to 5 cm, and more preferably 100 μm to 1 cm.
The height (thickness) of the fine wire structure is preferably 0.1 μm or more and 10 μm or less. Particularly preferably, it is 0.5 μm or more and 5 μm or less. Either the fine wire structure portion or the transparent conductive film may be exposed on the surface, but as a result, the smoothness (unevenness) of the conductive surface is preferably 5 μm or less. From the viewpoint of adhesion, it is preferably 0.01 μm or more and 5 μm or less. Particularly preferred is 0.05 μm or more and 3 μm or less.

Here, the smoothness (unevenness) of the conductive surface indicates the average amplitude of the unevenness when measuring 5 mm square using a three-dimensional surface roughness meter (for example, manufactured by Tokyo Seimitsu Co., Ltd .; SURFCOM 575A-3DF). For a surface roughness meter that does not reach the resolution, smoothness is obtained by measurement using an STM or an electron microscope.
With regard to the relationship between the width, height, and interval of the fine lines, the width of the fine lines may be determined according to the purpose, but typically it is preferably 1 / 10,000 or more and 1/10 or less of the fine line interval.
The height of the fine line is the same, but a range of 1/100 to 10 times the width of the fine line is preferably used.

  The surface resistivity of the transparent electrode used in the present invention is preferably from 0.1Ω / □ to 100Ω / □, more preferably from 1Ω / □ to 80Ω / □. The surface resistivity of the transparent electrode is a value measured according to the measurement method described in JIS K6911.

When a metal and / or alloy fine wire structure is disposed as the transparent electrode, it is preferable to suppress a decrease in light transmittance. It is preferable to ensure a light transmittance of 90% or more by setting the interval, the width and the height of the thin lines within the above-described ranges.
In the present invention, the light transmittance of the transparent electrode is preferably 70% or more, more preferably 80% or more, and most preferably 90% or more with respect to 550 nm light.

  The transparent electrode preferably transmits 80% or more of light in the wavelength range of 420 nm to 650 nm, more preferably 90% or more, in order to improve luminance and realize white light emission. preferable. In order to realize white light emission, it is more preferable to transmit 80% or more of light in a wavelength region of 380 nm to 680 nm. The light transmittance of the transparent electrode can be measured with a spectrophotometer.

<Back electrode>
For the back electrode on the side from which light is not extracted, any conductive material can be used. It is selected from gold, silver, platinum, copper, iron, aluminum and other metals, graphite, etc. depending on the form of the element to be created, the temperature of the production process, etc. It may be used. Furthermore, from the viewpoint of improving durability, it is important that the thermal conductivity of the back electrode is high, and it is preferably 2.0 W / cm · deg or more, particularly 2.5 W / cm · deg or more.
It is also preferable to use a metal sheet or a metal mesh as the back electrode in order to ensure high heat dissipation and electrical conductivity in the periphery of the EL element.

<Manufacturing method>
The method for producing the EL device of the present invention is not particularly limited, but a method as described in detail in, for example, [0046] to [0049] of JP-A No. 2007-12466 can be appropriately employed.

<Sealing>
It is preferable that the dispersion type EL element of the present invention is finally processed using a sealing film so as to eliminate the influence of humidity and oxygen from the external environment. Details of the sealing are as described in JP-A-2007-12466, [0050] to [0055].

  A gas barrier laminate film is used as the sealing film preferably used in the present invention, and these will be described in detail below. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Gas barrier laminate film]
(Layer structure)
The structure of the gas barrier laminate film as the sealing film preferably used in the present invention preferably has at least one inorganic layer and at least one organic layer on the base film. If it has an inorganic layer and an organic layer on a base film, each layer number and lamination | stacking order will not be restrict | limited. For example, it may be formed on the base film in the order of the inorganic layer and the organic layer, or may be formed on the base film in the order of the organic layer and the inorganic layer. Preferred is one in which inorganic layers and organic layers are alternately formed. For example, what was formed in order of the inorganic layer, the organic layer, and the inorganic layer on the base film can be mentioned as a preferable example. The number of inorganic layers and organic layers is preferably 1 to 10 layers, more preferably 1 to 5 layers, and even more preferably 1 to 3 layers. The inorganic layer and the organic layer may be formed only on one side of the base film, or may be formed on both sides.

  Moreover, the functional layer may be formed between the base film and the inorganic layer, between the base film and the organic layer, and between the inorganic layer and the organic layer. Examples of functional layers include optical functional layers such as antireflection layers, polarizing layers, color filters, and light extraction efficiency improving layers; mechanical functional layers such as hard coat layers and stress relaxation layers; antistatic layers and conductive layers An electric functional layer; an antifogging layer; an antifouling layer; a printing layer and the like.

(Organic layer)
The organic layer constituting the gas barrier laminate film of the present invention is characterized by containing a polymer having a phosphate group. The polymer having a phosphate ester group can be produced by polymerizing a monomer composition containing a polymerizable monomer having at least one phosphate ester group.

  Gas barrier properties in which at least an inorganic layer, an organic layer, and an inorganic layer are laminated in this order on the substrate film surface (opposite surface) opposite to the side having an organic layer containing an inorganic layer and a polymer having a phosphate ester group A laminate layer can be provided. By providing such a gas barrier laminate layer, water molecules can be prevented from entering from the opposite surface. As a result, the dimensional change of the gas barrier laminate film can be suppressed to prevent stress concentration and destruction on the inorganic layer, and as a result, durability can be further enhanced.

  As the monomer having a phosphoric ester group used in the present invention, a compound represented by the following general formula (1) can be preferably used.

In the general formula (1), Z ¹ represents Ac ² —O—X ² —, a substituent having no polymerizable group or a hydrogen atom, and Z ² represents Ac ³ —O—X ³ —, which has a polymerizable group. And Ac ¹ , Ac ² and Ac ³ each independently represents an acryloyl group or a methacryloyl group, and X ¹ , X ² and X ³ each independently represent an alkylene group, an alkyleneoxy group, an alkyleneoxy group A carbonyl group, an alkylenecarbonyloxy group, or a combination thereof is represented.

  The general formula (1) is represented by a monofunctional monomer represented by the following general formula (2), a bifunctional monomer represented by the following general formula (3), and the following general formula (4). Trifunctional monomers are included.

The definitions of Ac ¹ , Ac ² , Ac ³ , X ¹ , X ² and X ³ are the same as those in the general formula (1). In the general formulas (2) and (3), R ¹ represents a substituent or a hydrogen atom having no polymerizable group, and R ² represents a substituent or a hydrogen atom having no polymerizable group.

In the general formula (1) ~ (4), X 1, the number of carbon atoms of X ² and X ³ is preferably 1 to 12, more preferably 1 to 6, 1 to 4 is more preferred. Specific examples of the alkylene group X ^1, X ² and X ³ may take, and, X ^1, alkyleneoxy groups X ² and X ³ can take an alkyleneoxy carbonyl group, specific examples of the alkylene moiety of the alkylene carbonyloxy group Includes a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group. The alkylene group may be linear or branched, but is preferably a linear alkylene group. X ¹ , X ² and X ³ are preferably an alkylene group.

In the general formulas (1) to (4), examples of the substituent having no polymerizable group include an alkyl group, an alkoxy group, an aryl group, an aryloxy group, or a group obtained by combining these. Preferred are an alkyl group and an alkoxy group, and more preferred is an alkoxy group.
1-12 are preferable, as for carbon number of an alkyl group, 1-9 are more preferable, and 1-6 are more preferable. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. The alkyl group may be linear, branched or cyclic, but is preferably a linear alkyl group. The alkyl group may be substituted with an alkoxy group, an aryl group, an aryloxy group, or the like.
6-14 are preferable and, as for carbon number of an aryl group, 6-10 are more preferable. Specific examples of the aryl group include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group. The aryl group may be substituted with an alkyl group, an alkoxy group, an aryloxy group, or the like.
For the alkyl part of the alkoxy group and the aryl part of the aryloxy group, the description of the alkyl group and the aryl group can be referred to.

  In the present invention, only one type of monomer represented by the general formula (1) may be used, or two or more types may be used in combination. When used in combination, the monofunctional monomer represented by the general formula (2), the bifunctional monomer represented by the general formula (3), and the trifunctional monomer represented by the general formula (4) Two or more kinds may be used in combination.

  In the present invention, commercially available compounds such as the KAYAMER series manufactured by Nippon Kayaku Co., Ltd. and the Phosmer series manufactured by Unichemical Co., Ltd. may be used as they are as the polymerizable monomers having a phosphate ester group. Well, newly synthesized compounds may be used.

  Details of the phosphate ester preferably used in the organic layer of the sealing film (gas barrier film) of the present invention are described in JP-A-2007-290369, [0020] to [0042].

<Application>
The use of the present invention is not particularly limited, but considering the use as a light source, the emission color is preferably white. In addition to the case of using a red conversion material as described above, for example, a method using phosphor particles that emit white light alone, such as zinc sulfide phosphor particles activated by copper and manganese and gradually cooled after firing, A method of mixing a plurality of phosphor particles that emit light in the three primary colors or complementary colors is preferable. (A combination of blue-green-red, a combination of blue-green-orange, etc.) Also, like the blue color described in JP-A-7-166161, JP-A-9-245511, and JP-A-2002-62530 Also preferred is a method in which light is emitted at a short wavelength, and a part of the light emission is converted into green or red by using a fluorescent pigment or a fluorescent dye (light emission) and whitened. Further, the CIE chromaticity coordinates (x, y) preferably have an x value in the range of 0.30 to 0.43 and a y value in the range of 0.27 to 0.41.

The present invention is particularly effective in an application in which an EL element is used by emitting light with high luminance (for example, 600 cd / m ² or more). Specifically, the present invention is used in a driving condition in which a voltage of 100 V or more and 500 V or less is applied between the transparent electrode and the back electrode of the EL element, or in a condition of driving with an AC power source having a frequency of 800 Hz or more and 4000 KHz or less. It is valid.

  Examples of the dispersion type EL element of the present invention are shown below, but the dispersion type EL element of the present invention is not limited thereto.

Example 1
Each layer shown below is formed on a 70 μm thick aluminum electrode (back electrode) by applying the respective layer forming coating solutions in the order of a first layer (thickness 30 μm) and a second layer (thickness 55 μm). Further, polyethylene terephthalate (thickness 75 μm) sputtered with indium-tin oxide so as to form a transparent electrode having a thickness of 40 nm is formed so that the transparent electrode side (conductive surface side) faces the aluminum electrode side. The two phosphor layer-containing layers (light-emitting layers) were adjacent to each other and pressed with a 190 ° C. heat roller in a nitrogen atmosphere.

The additive amount of each layer shown below represents the mass per square meter of the EL element.
Each layer was prepared by applying dimethylformamide to a coating solution with adjusted viscosity and then dried at 110 ° C. for 10 hours.

First layer: Insulating layer (without red conversion material)
Cyanoethyl pullulan 14.0g
Cyanoethyl polyvinyl alcohol 10.0g
Barium titanate particles (average sphere equivalent diameter 0.05 μm) 100.0 g
Second layer; light-emitting layer 18.0 g of cyanoethyl pullulan
12.0 g of cyanoethyl polyvinyl alcohol
Phosphor particles 120.0g

The production method and characteristics of the phosphor particles are shown below.
Water was added to 150 g of ZnS (Furuuchi Chemical, purity 99.999%) to form a slurry, and 0.0001 mol% sodium chloroaurate was added to an aqueous solution containing 0.538 g of CuSO ₄ .5H ₂ O and zinc. ZnS raw powder (average particle diameter of 100 nm) was obtained by adding and partially replacing Cu (Cu1.4 × 10 ⁻³ mol with respect to 1 mol of ZnS). BaCl ₂ .2H ₂ O; 2.1 g, MgCl ₂ .6H ₂ O; 4.25 g, SrCl ₂ .6H ₂ O; 1.0 g was added to 25.0 g of the obtained raw flour, and the mixture was added at 1200 ° C. for 4 hours. Firing was performed to obtain a phosphor intermediate. The particles were washed with ion exchange water 10 times and dried. The obtained intermediate was pulverized with a ball mill and then annealed at 700 ° C. for 4 hours.
The obtained phosphor particles were washed with a 10% KCN aqueous solution to remove excess copper (copper sulfide) on the surface, and then washed with water five times to obtain phosphor particles A.

Further, the phosphor particles B were prepared in the same manner as the phosphor particles A except that the amount of CuSO ₄ .5H ₂ O contained in the aqueous solution was 0.192 g.
Further, the phosphor particles C were prepared in the same manner as the phosphor particles A except that the amount of CuSO ₄ .5H ₂ O was 0.384 g.
Similarly, the phosphor particles D to I are phosphors except that the amount of CuSO ₄ .5H ₂ O is 0.437 g, 0.614 g, 0.115 g, 0.341 g, 0.652 g, and 0.0767 g, respectively. Prepared in the same manner as Particle A.

  Table 1 shows the Cu content, average particle size, and variation coefficient of particle size of each phosphor particle. Regarding the Cu content, the phosphor particles are dissolved in aqua regia and are shown as a percentage of Zn by ICP emission analysis. Further, the average particle size and the particle size variation coefficient were measured using a laser diffraction / scattering particle size distribution measuring apparatus LA-920 manufactured by Horiba.

  Each phosphor particle was mixed in the ratio shown in Table 2 below to form a coated product. Furthermore, a film with a transparent electrode is pressure-bonded, and an electrode terminal (aluminum plate having a thickness of 60 μm) is wired to each of the aluminum electrode and the transparent electrode, and then sandwiched with a GX film, a moisture-proof film manufactured by Toppan Printing Co. The EL element was sealed by thermocompression bonding with air.

  Relative luminance after 300 hours when the initial luminance is set to 100 when a voltage of 300 V is continuously applied using an AC power supply with a frequency of 1000 Hz and the half width of the spectrum of the EL element obtained as described above. Is shown in Table 2.

  The EL elements 101 and 102 have a longer light emission lifetime than the EL element 101 but have a narrow half-value width, which is outside the scope of the present invention. The EL element 103 is out of the scope of the present invention because it has a wide half-value width but a short lifetime. The EL elements 104 to 106 have a large half width and a long life. Similarly, the EL elements 107 to 110 have a wide half width and a relatively long life. The EL elements 111 and 112 had short lifetimes because the Cu concentration of the phosphor particles was outside the range of the present invention.

Example 2
In the production method of phosphor particles A to C, the amount of flux used was BaCl ₂ · 2H ₂ O; 4.2 g, MgCl ₂ · 6H ₂ O; 11.2 g, SrCl ₂ · 6H ₂ O; 9.0 g, respectively. Except having changed so that it becomes, phosphor particles J, K, and L were obtained in the same manner as in Example 1. Table 3 shows the Cu content, average particle size, and variation coefficient of the particle size of each phosphor particle.

  Further, an EL element was produced in the same manner as in Example 1, and the results shown in Table 4 below were obtained.

  Compared to Example 1, Example 2 has a smaller phosphor particle size, but as in Example 1, a half-value width was wide, and an element having a longer lifetime than Example 1 could be obtained.

Example 3
The same procedure as in EL elements 104 and 105 of Example 1 was carried out except that a red fluorescent dye (FA007 manufactured by Sinloihi) was included in the insulating layer in the EL element so as to be 3.0 g / m ² . As a result, not only a long life was achieved, but the color rendering index (Ra) was 81 and 86, respectively, of 80 or more, and white light emission equivalent to or higher than that of a general fluorescent lamp was obtained.

  From these results, it is possible to obtain an EL element that not only has a long lifetime but also exhibits excellent color rendering when white light is emitted by having phosphor particles having at least two different Cu contents in the light emitting layer. Can do.

Example 4
The phosphor particles are mixed in the ratios shown in Table 2 to form the coated product 108. A film with a transparent electrode is pressure-bonded, and an electrode terminal (a 60 μm thick aluminum plate) is wired to each of the aluminum electrode and transparent electrode. After that, it was sealed by thermocompression bonding with a polyethylene naphthalate film (manufactured by Teijin DuPont, trade name: Teonex Q65FA) under vacuum degassing to obtain an EL element 208.

On the polyethylene naphthalate film, the following compound (A) [manufactured by Nippon Kayaku Co., Ltd., KAYAMER series, PM-21] or (B) [manufactured by Kyoeisha Chemical Co., Ltd.] Light ester P-2M] or (C) [Osaka Organic Chemical Co., Ltd., V # 3PA] or the following compound (D) which is an acrylate having a hydroxyl group [Shin Nakamura Chemical Co., TOPOLEN] or a carboxylic acid A photopolymerizable acrylate that is mixed using 1 g of the following compound (E) [manufactured by Toa Gosei, M5300] that is an acrylate, or 1 g of the following compound (F) [manufactured by Aldrich, AAEMA] having an acetylacetone structure. The following photopolymerizable compound [Kyoeisha Chemical Co., Ltd. 4.5 g of the following compound (G) [manufactured by Kyoeisha Chemical Co., Ltd., light acrylate TMP-A] as a trifunctional acrylate was mixed with 4.5 g of a photopolymerization initiator [Ciba Geigy] , IRGACURE907] was prepared and dissolved in 190 g of methyl ethyl ketone to prepare a coating solution. This coating solution was applied on the smooth surface of the base film using a wire bar with a wire bar (# 6), and an air-cooled metal halide lamp (160 W / cm) under a nitrogen purge with an oxygen concentration of 0.1% or less ( An organic layer having a film thickness of about 500 nm was formed by irradiating ultraviolet rays having an illuminance of 350 mW / cm ² and an irradiation amount of 500 mJ / cm ² .

Further, an inorganic layer made of silicon oxide (AlOx) was formed on each of the organic layers. The inorganic layer was formed using a sputtering apparatus, using Al as a target, argon as a discharge gas, and oxygen as a reaction gas. The inorganic layer thickness was 50 nm, and a laminated film was formed.
On the inorganic layer of each laminated film, the same coating solution as that used for forming each organic layer was applied with a wire bar (# 6), and 160 W under a nitrogen purge with an oxygen concentration of 0.1% or less. An organic layer having a film thickness of about 500 nm is formed by irradiating ultraviolet rays with an illuminance of 350 mW / cm ² and an irradiation amount of 500 mJ / cm ² using an air-cooled metal halide lamp (produced by Eye Graphics Co., Ltd.). A laminated film composed of an organic layer / inorganic layer / organic layer / base material] is prepared, and each of the organic layers using compound A is laminated film 208A, compound B is 208B, and compound C is 208C. The compound D was 208D, the compound E was 208E, and the compound F was 208F.

  For the prepared EL samples 208 and 208A to 208F, when light emission is continued at 45 ° C. and relative humidity 85%, the intensity of light emission is the intensity at the start of light emission (after 0 hours have elapsed), after 1500 hours of continuous light emission (after 1500 hours have elapsed) The brightness of was measured. The results shown in relative values with the luminance at the start of light emission of 208 as 100 are summarized in Table 5 below. Compared to 208, all of them showed less decrease in luminance. In particular, 208A to 208F showed little decrease in luminance after 1500 hours even after continuous emission for 1500 hours.

Claims (7)

  A dispersion type electroluminescent device having at least a light emitting layer between a pair of electrodes consisting of a back electrode and a transparent electrode, wherein the light emitting layer has a Cu content of 0.10 to 0.16 mol% and 0.03 to 0.03. A dispersion type electroluminescent device comprising two kinds of phosphor particles each contained at a concentration of 08 mol%.   2. The dispersion type electroluminescent device according to claim 1, wherein the average particle size of the phosphor particles is 1 μm or more and less than 20 μm, and the variation coefficient of the particle size is 3% or more and less than 40%.   The dispersion type electroluminescence device according to claim 1, wherein a red conversion material is contained in any of the layers of the dispersion type electroluminescence device.   4. The dispersion type electroluminescent device according to claim 1, wherein the red color conversion material layer containing the red color conversion material is between the light emitting layer and the back electrode.   3. The dispersion type electroluminescent device according to claim 1, wherein the light emitting layer contains phosphor particles that emit red light separately from the phosphor particles. 4.   6. The dispersion type electroluminescent device according to claim 5, wherein the phosphor particles emitting red light have an average particle size of 1 μm or more and less than 20 μm, and a particle size variation coefficient of 3% or more and less than 40%.   A gas barrier laminate film comprising a polymer of a monomer composition having at least one inorganic layer and at least one organic layer on the base film, wherein the organic layer contains at least one phosphate ester acrylate. The dispersive electroluminescent device according to claim 1, wherein the dispersive electroluminescent device is sealed with a slag.