JP2005216636A - Sealing cover and electroluminescence apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing cover for an electroluminescence apparatus having desiccant means possible to be thinned and excellent in absorptivity. <P>SOLUTION: In this sealing cover, an electroluminescent element 14 is arranged on a surface of a substrate 13, a cover body 11 is attached to enclose the electroluminescent element 14, and a porous layer 12 is formed on a surface of the cover body 11 on the side of the electroluminescent element 14. Since the porous layer 12 has a large surface area contacting with an atmosphere comparing with a mere layer, it is excellent in depletion of water caused by suction of water molecule and chemical action, i.e. absorptivity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sealing cover suitable for sealing an electroluminescent element of an electroluminescent device used for displays, light emitting elements and the like of various information industrial equipment, and particularly to maintain good light emitting characteristics over a long period of time. The present invention relates to a sealing cover for an electroluminescent device that can be used and an electroluminescent device using the same.

  Composed of a pair of electrodes and a light-emitting layer sandwiched between the electrodes, the electroluminescence element that emits light by applying a voltage between the electrodes is compared to a liquid crystal display that is currently widely used as a thin display, It is attracting attention as a next-generation display light-emitting device that has advantages such as high brightness, high contrast, wide viewing angle, thinness, and small number of parts.

The electroluminescence element is roughly classified into an inorganic electroluminescence element whose light emitting layer is made of an inorganic material and an organic electroluminescence element whose light emitting layer is made of an organic material. As an inorganic electroluminescent element using an inorganic material as a light emitter, a transparent electrode made of ITO (Indium Tin Oxide: hereinafter referred to as ITO) on the surface of a transparent insulating substrate, a _second electrode such as SiO ₂ and Si ₃ N _4, etc. 1) Dielectric layer and elements that are the emission center in II-VI group compound semiconductors such as zinc sulfide, calcium sulfide, strontium sulfide, zinc selenide, strontium selenide, etc. Manganese, terbium, samarium, thulium, thulium, europium, cerium, etc. In which a light emitting layer to which a rare earth element is added, a second dielectric layer made of Al ₂ O ₃ or the like, and a back electrode made of aluminum or the like are formed. The inorganic electroluminescent element having such a configuration is such that a light emitting layer sandwiched between two electrodes emits light by applying an AC voltage of about 100 V or more between the transparent electrode and the back electrode. .

  In recent years, organic electroluminescence devices have been put into practical use because they have improved luminous efficiency and lifetime. The organic electroluminescence element is manufactured by providing a first electrode on the surface of a substrate such as glass or plastic, and depositing an organic electroluminescence layer and a second electrode thin film on the first electrode. At least one of the first electrode and the second electrode is a transparent electrode. When a voltage is applied between the first and second electrodes to supply a current, holes are injected from the anode side and electrons are injected from the cathode side into the organic electroluminescence layer. Thereby, the luminescent molecule is excited by recombination of holes and electrons in the organic electroluminescence layer, and the light generated when the excited luminescent molecule is deactivated is extracted from the transparent electrode side to the outside.

  Since these electroluminescent elements deteriorate in characteristics due to moisture and oxygen, in order to obtain a practical light emitting lifetime for use in displays, the electroluminescent elements are shielded from an atmosphere harmful to the electroluminescent elements such as moisture and oxygen. A sealing technique is essential.

  Next, an example of an electroluminescence device using a conventional sealing method will be described.

  In the electroluminescence device proposed in Patent Document 1, as shown in a cross-sectional view in FIG. 5, the organic EL element 51 includes an ITO electrode 53, an organic light emitting material layer 54, and a cathode 55 in this order on a glass substrate 52. A laminated body 56 is formed, and a drying means 58 is disposed so as to be isolated from the laminated body 56. The laminated body 56 and the drying means 58 include a glass substrate 52 and a glass sealing can 57 as a sealing material 59. It is sealed in an airtight container formed by being hermetically bonded. And in this airtight container, the dry inert gas is enclosed. In the organic EL element 51, the drying means 58 is formed of a compound that chemically adsorbs moisture and maintains a solid state even when moisture is absorbed. In addition, a chemical compound consisting of alkali metal oxides, alkaline earth metal oxides, sulfates, metal halides, perchlorates, organic substances, etc. that absorbs moisture and maintains a solid state even when it absorbs moisture is used. The drying means 58 and the drying means 58 are isolated from the laminated body 56 in which the organic light emitting material layer 54 is sandwiched between a pair of electrodes 53 and 55 facing each other and sealed in an airtight container. Therefore, even after the drying means 58 absorbs moisture, the element 51 is not adversely affected, and it is easy to handle at the time of encapsulation, and further, no leakage current or crosstalk is caused. In the element 51, stable light emission characteristics are maintained over a long period of time.

  In this Patent Document 1, sodium oxide / potassium oxide is listed as the alkali metal oxide, and calcium oxide / barium oxide / magnesium oxide is listed as the alkaline earth metal oxide. . Examples of the sulfate include lithium sulfate, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate, gallium sulfate, titanium sulfate, and nickel sulfate. Metal halides include calcium chloride, magnesium chloride, strontium chloride, yttrium chloride, copper chloride, cesium fluoride, tantalum fluoride, niobium fluoride, calcium bromide, cerium bromide, selenium bromide, and vanadium bromide. -Magnesium bromide, barium iodide, magnesium iodide, etc. are mentioned. Furthermore, examples of perchlorate include barium perchlorate and magnesium perchlorate.

  On the other hand, as a method for enclosing the drying means 58, for example, the above compound is solidified to form a molded body, and this molded body is fixed to the glass sealing can 57, or the above compound is placed in a breathable bag. The glass sealing can 57 is fixed to the glass sealing can 57, a partition is provided in the glass sealing can 57, and the above compound is put into the partition, and further, a vacuum deposition method, a sputtering method, a spin coating method, or the like is used. Various methods such as a method of forming a film in the glass sealing can 57 can be adopted. In recent years, attention has been paid to film formation that can be made thinner than fixing a molded body because of a demand for thinner thickness.

  As a sealing cover for sealing the electroluminescence element, a metal can is used in addition to the glass can described in Patent Document 1. Moreover, plate-like things, such as a glass plate, a polymer film, etc. are used for a sealing cover instead of a can shape.

Next, an example of an electroluminescence device using a plate-shaped sealing cover is shown. Patent Document 2 proposes an organic EL element having a desiccant that can suppress the growth of dark spots by providing a water capturing agent layer 67a for chemically capturing water in the water capturing agent retaining layer 67b. Yes. This is a light emitting part having a structure in which an organic EL material layer (hole injection layer 64a, hole transport layer 64b, light emitting layer / electron transport layer 64c) is laminated between a pair of electrodes (anode 65, cathode 66) facing each other. An organic EL element having an airtight container comprising a glass substrate 62 on which the light emitting part is disposed, a sealing cap 63 covering the light emitting part and sealing the glass substrate 62, and water capturing means provided in the airtight container The water collecting means is an organic EL element composed of a water catching agent holding layer 67b provided on the inner surface of the airtight container and a water catching agent layer 67a provided on the surface of the water catching agent holding layer 67b.
Japanese Patent Laid-Open No. 9-148066 JP 2003-240661 A

  Drying means such as water-absorbing agents, water-retaining agents, desiccants, and moisture-absorbing agents reduce the amount of water in the sealed atmosphere by physical water molecule adsorption or water consumption by chemical reaction. The larger the reaction area, the more efficient. However, some desiccants are granulated and fixed in a sealed container to increase the effective area. However, it is not easy to reduce the thickness while sufficiently functioning as a water-absorbing agent. There is a problem that it is difficult to be fixed in the sealed container so as not to be a generation source.

  Further, when the drying means 58 is formed in the glass sealing can 57 by using a vacuum deposition method, a sputtering method, a spin coating method, or the like as proposed in Patent Document 1, it becomes a dense film and has a large effective area. There is a problem that it can not be said. Furthermore, when an alkaline earth metal oxide or the like is used, a hydroxide is generated due to moisture absorption, resulting in volume expansion, and in the case of a dense film, the film is destroyed and dust generation and There is also a problem that it may cause a decrease in transparency.

  The present invention has been made in view of the problems in the conventional technology as described above, and an object of the present invention is to provide a sealing cover having a drying means that can be thinned and has excellent water absorption, and It is an object of the present invention to provide an electroluminescent device that can be used and maintain good light emission characteristics over a long period of time.

  In the sealing cover of the present invention, a porous layer is formed on the surface of the cover body attached on the surface of the cover body which covers the electroluminescence element on the substrate on which the electroluminescence element is disposed. It is characterized by being.

  The sealing cover of the present invention is characterized in that, in the above configuration, the porous layer is made of a metal oxide.

  Moreover, the sealing cover of the present invention is characterized in that, in the above structure, the porous layer is made of an oxide of an alkaline earth metal.

  The sealing cover according to the present invention is characterized in that, in the above configuration, the porous layer is formed by supercritical drying of a wet gel layer.

  Moreover, the sealing cover of the present invention is characterized in that, in the above configuration, the wet gel layer contains a metal alkoxide or chloride.

  The sealing cover of the present invention is characterized in that, in the above configuration, the cover main body and the porous layer are translucent with respect to light emitted from the electroluminescence element.

  The electroluminescent device of the present invention is characterized in that the sealing cover of the present invention having the above-described configuration is attached to a substrate having an electroluminescent element disposed on the surface thereof.

  According to the sealing cover of the present invention, since the porous layer is formed on the surface of the cover body attached to cover the electroluminescent element on the electroluminescent element side, the porous layer is compared with a simple layer. In addition, since the surface area in contact with the atmosphere increases, water consumption due to water molecule adsorption and chemical reaction, that is, high water absorption efficiency, and excellent water absorption without causing dust generation or reduced transparency, etc. Since it functions as a means (water-absorbing agent), the electroluminescent device to be sealed can maintain good light emission characteristics over a long period of time.

  Further, according to the sealing cover of the present invention, when the porous layer is made of a metal oxide, it causes a chemical reaction to generate a metal hydroxide by hydrolysis by contact with water, Even if the reaction rate is slow, it becomes a hydrophilic surface and has good water adsorption, and is almost irreversible in the operating temperature range of a normal electroluminescence device of about 80 ° C. or less. It can be used as an effective moisture adsorbent.

  According to the sealing cover of the present invention, when the porous layer is made of an alkaline earth metal oxide, the alkaline earth metal oxide generates a hydroxide by reaction with water. As a result, moisture is irreversibly adsorbed and a solid state is maintained even when moisture is absorbed, so that it functions as a better water-absorbing agent. Furthermore, by being porous, the surface area is increased and the water absorption efficiency is higher. Moreover, since the volume increase accompanying a water absorption reaction is relieved by the infinite number of pores in the porous layer, it is possible to suppress dust generation and a decrease in translucency.

  Furthermore, according to the sealing cover of the present invention, when the porous layer is formed by supercritical drying of the wet gel layer, the wet gel layer is supercritically dried to be porous. As a result, a porous layer having a high porosity and a small amount of residual moisture at the time of formation can be easily formed, and a better water absorption effect can be obtained.

  Further, according to the sealing cover of the present invention, when the cover main body and the porous layer are translucent, the electroluminescent element is sealed by using the sealing cover. When the device is manufactured, the light emitted from the electroluminescence element can be taken out from the sealing cover side, which is effective as a sealing cover for sealing a so-called top emission type electroluminescence element. .

  Furthermore, according to the electroluminescence device in which the electroluminescence element disposed on the surface of the substrate is sealed with the sealing cover of the present invention as described above, the electroluminescence device can be made thin and efficiently absorb water by the porous layer. In addition, the reduction of dust generation and translucency can be suppressed, and the light emission characteristics of the electroluminescence element can be favorably maintained over a long period of time.

  Hereinafter, a sealing cover of the present invention and an electroluminescence device using the same will be described in detail with reference to the drawings.

  1 and 2 are cross-sectional views showing an example of an embodiment of the sealing cover of the present invention and another example, respectively. 1 and 2, reference numerals 11 and 21 denote cover bodies, and reference numerals 12 and 22 denote porous layers formed on the surfaces of the cover bodies 11 and 21, respectively.

  FIGS. 3 and 4 are cross-sectional views showing an example of the electroluminescent device according to the present invention and another example, respectively. 3 and 4, reference numerals 13 and 23 denote substrates, reference numerals 14 and 24 denote electroluminescence elements disposed on the surfaces of the substrates 13 and 23, and reference numerals 15 and 25 denote sealing materials. Further, a sealing cover is attached to the substrates 13 and 23 so as to cover the electroluminescence elements 14 and 24, 11 and 21 are cover bodies of the sealing cover, and 12 and 22 are cover bodies 11 and 21, respectively. This is a porous layer formed on the electroluminescence elements 14 and 24 side.

  Cover bodies 11 and 21 are made of glass such as alkali glass / non-alkali glass / quartz glass, metal such as SUS / aluminum, resin such as polycarbonate / polyethylene / acrylic / polyolefin, and ceramics such as alumina / zirconia / aluminum nitride. Is used.

  Further, the shape of the cover main bodies 11 and 21 may be a desired shape such as a plate shape as shown in FIG. 1 or a concave shape as shown in FIG. As shown in FIG. 4, the concave shape of the cover main body 21 shown in FIG. 2 is the electroluminescence housed when the sealing cover is attached to the substrate 23 and the electroluminescent element 24 is sealed. This is for avoiding contact with the element 24 and destruction. For example, when the concave portion is attached to the substrate 23 having a flat surface, the depth of the concave portion is set sufficiently larger than the thickness of the electroluminescence element 24 accommodated therein. Further, the size (width, length) of the concave recess is set so that the electroluminescence element 24 is accommodated inside without contacting. In that case, it is necessary to consider the positional deviation of the cover body 21 that occurs during the sealing process.

  The porous layers 12 and 22 formed on the surface of the cover bodies 11 and 21 on the side covering the electroluminescent elements 14 and 24 have a low density and a high porosity compared to the bulk state, and there are gaps between the atoms. In many cases, water molecules easily pass through or come into contact with water molecules. Further, in a portion where the distance between the atoms is large, the bonds between the atoms are weak or the bonds are dangling, so that a chemical reaction is likely to occur. In the case where the porous layers 12 and 22 are chemically stable materials, water molecules are adsorbed by van der Waals force, hydrogen bonds, or the like. Moreover, when it is a material which is easy to raise | generate a chemical reaction such as hydrolysis by contact with water, more water can be consumed and absorbed.

  When the porous layers 12 and 22 are made of metal oxides, they may cause chemical reactions that generate metal hydroxides by contact with water, or the chemical reaction rate is slow. Even so, it can be used as an effective moisture adsorbent because it has a hydrophilic surface and adsorbs water well and is almost irreversible in the operating temperature range of ordinary electroluminescent devices of about 80 ° C or lower. It becomes.

  In particular, when the porous layers 12 and 22 are made of an oxide of an alkaline earth metal, the alkaline earth metal oxide irreversibly adsorbs moisture by generating a hydroxide by reaction with water. At the same time, since the solid state is maintained even when moisture is absorbed, the porous structure increases the surface area and the water absorption efficiency, and there are innumerable pores in the porous layers 12 and 22. Since the volume increase accompanying a water absorption reaction is relieved by this, it can function as a better water-absorbing agent since it can suppress a dust generation and a translucency fall.

  The porous layers 12 and 22 are preferably formed by forming a wet gel layer on the surfaces of the cover bodies 11 and 21 and then supercritically drying the layer.

  Here, supercritical drying will be described.

  There are three types of supercritical fluid functional substances, the three states, gas phase (gas), liquid phase (liquid), and solid phase (solid). The phase diagram showing the phase state of a substance with temperature on the horizontal axis and pressure on the vertical axis is a vapor pressure curve showing the boundary between the gas phase and the liquid phase, a sublimation curve showing the boundary between the gas phase and the solid phase, It consists of a dissolution curve indicating the boundary between the liquid phase and the liquid phase. The triple point is where these three phases overlap. When the vapor pressure curve extends from this triple point to the high temperature side, it reaches a critical point where the gas phase and the liquid phase coexist. At this critical point, the gas phase and liquid phase densities are equal, and the gas-liquid coexistence interface disappears. Above the critical point, it is called supercritical fluid because there is no distinction between gas phase and liquid phase. A supercritical fluid is a fluid compressed at a high density above this critical temperature. It is similar to gas in that the diffusion force of solvent molecules is dominant, but it is similar to liquid in that the influence of molecular cohesion cannot be ignored, so it has the property of dissolving various substances. ing. Moreover, since the density can be continuously changed by temperature and pressure, the density can be arbitrarily adjusted from the ideal gas state to a size comparable to the liquid. In particular, the density can be adjusted with a slight change in temperature and pressure near the critical point. A supercritical fluid has a very high infiltration property compared to a liquid and has a feature of easily penetrating a fine structure. In addition, by drying so as to transfer directly from the critical state to the gas layer, it is possible to dry without destroying the fine structure by preventing the capillary force from acting so that there is no gas-liquid interface. . It can also be used to extract and remove specific substances from the microstructure.

  Supercritical drying is drying using a supercritical fluid using such a supercritical fluid. In this method, there are a method in which the solvent is brought into a supercritical state and then dried, and a method in which the solvent is replaced with a supercritical fluid in a supercritical state and then dried.

  Carbon dioxide, ethanol, methanol, propanol, butanol, methane, ethane, propane, water, ammonia, methane, ethane, ethylene, fluoromethane, and the like can be used as the supercritical fluid for supercritical drying. Among them, carbon dioxide has a critical point of 31.1 ° C. and a pressure of 7.38 MPa.

  As a method for forming the porous layers 12 and 22 on the surfaces of the cover main bodies 11 and 21 using such supercritical drying, a wet gel layer is formed on the cover main bodies 11 and 21, and then the wet layers are formed. If the gel layer is dried using supercritical drying, it can be dried without destroying the structure of the wet wet gel, and the porous layers 12 and 22 made of aerogel can be obtained.

  In order to form a wet gel layer on the surface of the cover body 11, 21, after dissolving a metal alkoxide or metal chloride in an organic solvent, this is sprayed, spin coated, dip coated, roll coated, inkjet Apply to the surface of the cover body 11, 21 by the method or screen printing method. Among these, the spray method, dip coating method, roll coating method, ink jet method, and screen printing method are preferable because they can be applied in a desired shape to predetermined positions of the cover main bodies 11 and 21. When the spin coat method or dip coat method is used, it is applied to the entire surface of the cover body 11, 21, so that the porous layer 12, 22 formed in an unnecessary portion such as a sealing joint, 22 needs to be removed later.

  Next, the applied layer is gelled by hydrolysis and dehydration polymerization under a steam of a catalyst such as ammonia and water to form a wet gel layer. As a catalyst for hydrolysis and dehydration polymerization, an alkali catalyst such as ammonia or sodium hydroxide or an acid catalyst such as hydrochloric acid, nitric acid or phosphoric acid may be used. However, when an acid catalyst is used, the degree of polymerization is relatively high. In contrast, a linear polymer having a low degree of polymerization can be obtained, and when an alkali catalyst is used, a three-dimensional polymer having a relatively high degree of polymerization is obtained. In order to obtain a porous aerogel, This is preferable.

  After forming the wet gel layer, supercritical drying is performed. For example, the cover main bodies 11 and 21 are immersed in ethanol having a relatively low supercritical point, and the catalyst such as ammonia in the wet gel layer and water are all replaced with ethanol, and are kept in the high pressure vessel as they are. Of supercritical fluid. In this case, a two-phase state of ethanol and carbon dioxide is obtained, but the treatment is performed under conditions that are sufficiently higher than the critical point, for example, a temperature of 80 ° C. and a pressure of 16 MPa. Since supercritical carbon dioxide and ethanol are compatible with each other, ethanol in the wet gel layer can be almost completely extracted and removed by continuously circulating supercritical carbon dioxide. Ammonia can be removed by substituting with ethanol, and then ethanol can be almost completely removed with supercritical carbon dioxide, whereby porous layers 12 and 22 having excellent water absorption are obtained.

  The larger the area in which the porous layers 12 and 22 are formed, the better. However, it is preferable that the porous layers 12 and 22 be at least larger than the arrangement area of the electroluminescent elements 14 and 24 that are sealed and accommodated by the sealing cover. Usually, the cathode electrode used in the electroluminescence elements 14 and 24 is a light metal, and contains alkali or alkaline earth metal to improve electron injection efficiency, and is easily deteriorated by water or oxygen. In order for the porous layers 12 and 22 to sufficiently play a role of suppressing the reaction of such metal electrodes with water and oxygen, the area where the porous layers 12 and 22 are formed is equal to or greater than the area of the electrodes. It is desirable that Preferably, it is attached to the surface of the cover body 11, 21 attached to the substrate 13, 23 on which the electroluminescence elements 14, 24 are formed so as to cover the electroluminescence elements 14, 24, on the side of the electroluminescence elements 14, 24. In this case, the porous layers 12 and 22 may be formed on the entire surface excluding the portion to be joined.

  The metal alkoxide and metal chloride used to form the wet gel layer include aluminum, barium, calcium, selenium, copper, chromium, erbium, iron, indium, magnesium, niobium, manganese, tin, silicon, titanium, tantalum, An alkoxide or chloride of a metal such as zinc, vanadium, or zirconia may be used. Further, chelates of these metals can be used. These may be single or a multicomponent system composed of a plurality of metals. What is soluble in an organic solvent and that can be gelled by a reaction such as hydrolysis and dehydration polymerization after coating on the cover main bodies 11 and 21 may be used.

  Organic solvents used as solvents for metal alkoxides and metal chlorides are those that are soluble in metal alkoxides and metal chlorides, such as alcohols, ethers, glycols, and amines, and can easily adjust the viscosity of the mixed solution. Use it. Further, when a polymer such as polyethylene glycol monomethyl ether, polyvinyl acetate, or hydroxypropyl cellulose is added, the viscosity can be easily adjusted and a gel having a thick layer can be easily obtained.

  An acid catalyst or an alkali catalyst for promoting the hydrolysis / dehydration polymerization reaction, water, a surfactant for improving the wettability to the cover main bodies 11 and 21, and the like may be added.

  In particular, when alkoxides and chlorides of alkaline earth metals such as calcium, magnesium, and barium are used, porous layers 12 and 22 that are excellent in water absorption and can maintain a solid state even when water is absorbed can be obtained. Is preferred.

  Another method for forming the porous layers 12 and 22 is to form a resin layer on the surfaces of the cover bodies 11 and 21, dissolve the carbon dioxide supercritical fluid, and then rapidly apply pressure. By lowering, bubbles can be generated in the resin to form the porous layers 12 and 22. As such resin, acrylic resin, polyester, epoxy resin, etc. can be used, and after these are dissolved in an organic solvent, spray method, spin coating method, dip coating method, roll coating method, ink jet method, screen It is applied to the surfaces of the cover bodies 11 and 21 by a printing method or the like, and a layer made of resin is formed on the surfaces of the cover bodies 11 and 21. In that case, precursors such as monomers and oligomers of these resins may be used.

The pores in the porous layers 12 and 22 obtained by supercritical drying have a diameter of 0.1 to 10 μm and a number density of 10 ⁹ to 10 ¹⁵ / cm ³ , and are excellent in water absorption It becomes. Furthermore, by appropriately setting the supercritical drying treatment conditions, light scattering by the pores is reduced when the pore size is equal to or less than the wavelength of visible light. When the thickness is sufficiently thin or the material of the porous layers 12 and 22 is inherently transparent, the light emission of the electroluminescent elements 14 and 24 even if the porous layers 12 and 22 have many pores. Can be made almost transparent and translucent. Therefore, if the cover main bodies 11 and 21 are made of a transparent material transparent to the light emission of the electroluminescence elements 14 and 24, and the porous layers 12 and 22 also have the same translucency, the cover body 11 and 21 are sealed. The light emission of the electroluminescence elements 14 and 24 can be taken out from the cover side, and the so-called top emission type electroluminescence elements 14 and 24 are used as a sealing cover having a drying means with excellent water absorption for sealing. be able to.

  The thickness of the porous layers 12 and 22 may be about 1 to 200 μm. If the material of the porous layers 12 and 22 has a slightly low reaction rate with water such as silica, water absorption is caused by surface adsorption. Therefore, the thickness should be about 20 μm or more to obtain sufficient water absorption capability. desirable. In the case where the reaction rate with water such as an alkaline earth metal oxide is high, sufficient water absorption ability can be obtained with a thickness of 20 μm or less.

  Next, the electroluminescence device of the present invention will be described. As shown in FIGS. 3 and 4, the electroluminescence device of the present invention has the above-described electroluminescence of the cover main bodies 11 and 21 on the substrates 13 and 23 on the surfaces of which the electroluminescence elements 14 and 24 are disposed. The sealing cover of the present invention in which the porous layers 12 and 22 are formed on the surface on the element 14 and 24 side is attached.

  The substrates 13 and 23 are substrates for disposing the electroluminescence elements 14 and 24 on the surfaces thereof, and examples of the material include glass such as alkali glass, non-alkali glass and quartz glass, metal such as SUS and aluminum, Resins such as polycarbonate, polyethylene, acrylic, and polyolefin, and ceramics such as alumina, zirconia, and aluminum nitride are used. In the case of an electroluminescence device for display, a substrate on which a drive circuit composed of TFT elements or the like for forming an active matrix display device is suitably used for the substrates 13 and 23.

  The electroluminescent elements 14, 24 disposed on the surfaces of the substrates 13, 23 have a light emitting function configured as a light emitter having a structure in which an organic electroluminescent material layer or an inorganic electroluminescent material layer is laminated between a pair of electrodes. It is what you have. Although not shown in FIGS. 3 and 4, the electrodes of the electroluminescence elements 14 and 24 are electrically connected to an external drive circuit, respectively.

  Further, the sealing materials 15 and 25 join the substrates 13 and 23 and the cover main bodies 11 and 21 of the sealing cover, and are sealing members made of a material that can ensure sufficient adhesion and airtightness. . The sealing materials 15 and 25 are formed in a frame shape having a thickness capable of accommodating the porous layer 12 and the electroluminescence element 14 on the inner side, for example, as shown in FIG. 3 according to the shapes of the cover main bodies 11 and 21 and the substrates 13 and 23. 4 is used, or as shown in FIG. 4, it is arranged in layers between the frame portion of the cover main body 21 having a recess capable of accommodating the porous layer 22 and the electroluminescence element 24 in the center portion and the substrate 23. The sealing material 25 to be used may be used. For the sealing materials 15 and 25, for example, a thermosetting or photo-curing type epoxy resin or acrylic resin adhesive, solder, or the like may be used. In addition, a glass or the like for securing an appropriate gap between the substrates 13 and 23 and the cover main bodies 11 and 21 and adjusting a thermal expansion coefficient between the substrates 13 and 23 and the cover main bodies 11 and 21. You may contain the particle | grains (filler) which consist of metals etc.

  The substrates 13 and 23 on which the electroluminescent elements 24 and 25 are disposed are the cover bodies 11 and 21 having the porous layers 12 and 22 formed on the surface thereof, the porous layers 12 and 22 and the electroluminescent elements 14 and 24, respectively. Are joined by the sealing materials 15 and 25 so as to be housed inside, the electroluminescence elements 14 and 24 are sealed inside, and an electroluminescence device is obtained. This sealing operation is performed under a dry atmosphere or under vacuum, and the internal space where the electroluminescent elements 14 and 24 and the porous layers 12 and 22 are sealed is filled with a dry rare gas or resin, or is evacuated. To do. Here, when a rare gas having a pressure equal to or higher than atmospheric pressure is sealed in the internal space, entry of moisture, oxygen, and the like from the outside can be effectively suppressed.

  Next, specific examples of the present invention will be described.

  A solution obtained by mixing tetramethoxysilane, polyethylene glycol, and ethanol so as to obtain an appropriate viscosity was applied to the surface of a flat alkali-free glass substrate by a screen printing method. Subsequently, this substrate was left in a container filled with ammonia water vapor to carry out gelation by hydrolysis and dehydration polymerization reaction to form a wet gel layer on the surface of the substrate. Thereafter, this substrate was immersed in ethanol, and ammonia and water in the wet gel layer were all replaced with ethanol. The thin film immersed in ethanol is dried after the ethanol in the wet gel layer is completely extracted and removed by circulating a supercritical fluid of carbon dioxide in a high-pressure vessel at a temperature of 80 ° C and a pressure of 16 MPa. Thus, a sealing cover as shown in FIG. 1 having a porous layer made of silica airgel having a thickness of 2 μm was prepared.

On the other hand, an anode made of ITO (Indium Tin Oxide), a hole injection layer made of a copper phthalocyanine (CuPc) organic film, α-NPD (Bis (N- (1-naphtyl-N -Phneyl) benzidine) organic electroluminescent device in which a hole transport layer composed of an organic film, a light-emitting / electron transport layer composed of a tris (8-quinolinolato) aluminum (Alq ₃ ) organic film, and a cathode composed of AlLi were sequentially formed. Arranged.

  Next, an ultraviolet curable epoxy adhesive is applied as a sealing material to a thickness of about 20 μm around the organic electroluminescence element on the surface of the alkali-free glass substrate, and the sealing previously prepared in a dry nitrogen atmosphere. The stopper cover was placed so that the porous layer was on the inside, and the epoxy adhesive portion was irradiated with ultraviolet rays and cured to produce the electroluminescence device of the present invention as shown in FIG. Note that external lead wires connected to the anode and the cathode of the electroluminescence element are led out through a seal portion made of an epoxy adhesive.

  With respect to the electroluminescent device of the present invention thus produced, the state of light emission after the electroluminescent element was made to emit light for 100 hours at a temperature of 85 ° C. was observed. Since moisture is adsorbed, the dry state in the sealed space is maintained and the organic film and electrode layer of the electroluminescence element are suppressed from being deteriorated by water. Few new outbreaks and expansions were seen.

  On the other hand, in a similar test conducted by producing a comparative electroluminescence device that does not form a porous layer, electroluminescence is caused by moisture contained in an insulating material or the like or moisture entering from the outside during the production process of the electroluminescence element. Since the organic film and the electrode layer of the device were deteriorated, the dark spot was greatly enlarged.

  In addition, this invention is not limited to the example of the above embodiment, A various change may be added in the range which does not deviate from the summary of this invention. For example, to suppress the reflection of external light or to suppress the viewing angle dependency, to use a sealing cover with minute irregularities on the surface, or to seal an electroluminescent element using an inorganic material You may use it.

It is sectional drawing which shows an example of embodiment of the cover for sealing of this invention. It is sectional drawing which shows the other example of embodiment of the cover for sealing of this invention. It is sectional drawing which shows an example of embodiment of the electroluminescent apparatus of this invention. It is sectional drawing which shows the other example of embodiment of the electroluminescent apparatus of this invention. It is sectional drawing which shows the example of the conventional electroluminescent apparatus. It is sectional drawing which shows the other example of the conventional electroluminescent apparatus.

Explanation of symbols

11, 21 ... Cover body
12, 22 ... porous layer
13, 23 ... Substrate
14, 24 ... Electroluminescence element
15, 25 ... Sealing material

Claims (7)

A sealing layer characterized in that a porous layer is formed on the surface of the cover body, which is attached to the substrate having the electroluminescence element disposed on the surface thereof so as to cover the electroluminescence element. cover. The sealing cover according to claim 1, wherein the porous layer is made of a metal oxide. The sealing cover according to claim 2, wherein the porous layer is made of an oxide of an alkaline earth metal. The sealing cover according to claim 1, wherein the porous layer is formed by supercritical drying of a wet gel layer. The sealing cover according to claim 4, wherein the wet gel layer contains a metal alkoxide or chloride. The sealing cover according to claim 1, wherein the cover main body and the porous layer are translucent to light emitted from the electroluminescence element. An electroluminescence device comprising the sealing cover according to any one of claims 1 to 6 attached to a substrate having an electroluminescence element disposed on a surface thereof.

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