JP2007220402A - Method of encapsulating organic electroluminescent element and organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encapsulating method free from degrading performance of an organic EL element, and an organic EL element manufactured by the method, at the time of firm fixing of a thin and lightweight organic EL element with an encapsulating material by an adhesive. <P>SOLUTION: In the encapsulating method of the organic EL element encapsulating an organic EL element having a first electrode, at least one organic compound layer containing a light-emitting layer, and a second electrode on a substrate with a flexible encapsulating member with a barrier property through an adhesive, the adhesive is arranged an a whole surface including the outer periphery face of a light-emitting part of the organic EL element with the light-emitting part and a tip part of an outside fetching electrode in an exposed state, the flexible encapsulating member is overlapped on the adhesive, and only an adhesive part on the outer periphery face of the flexible encapsulating member is crimped to be put under a curing treatment afterwards. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for sealing an organic electroluminescence element (hereinafter also referred to as an organic EL element) and an organic EL element produced by this method.

  In recent years, organic EL elements using organic substances have been promising for use as solid light-emitting inexpensive, large-area full-color display elements and writing light source arrays, and active research and development have been promoted. The organic EL element includes a first electrode (anode or cathode) formed on a substrate, an organic compound layer (single layer portion or multilayer portion) containing an organic light emitting material laminated thereon, that is, a light emitting layer, It is a thin film type element having a second electrode (cathode or anode) laminated on the light emitting layer. When a voltage is applied to such an organic EL element, electrons are injected from the cathode and holes are injected from the anode into the organic compound layer. It is known that light is obtained by releasing energy as light when the electrons and holes recombine in the light emitting layer and the energy level returns from the conduction band to the valence band.

  As described above, since the organic EL element is a thin film type element, when an organic EL panel in which one or a plurality of organic EL elements are formed on a substrate is used as a surface light source such as a backlight, a surface light source. It is possible to easily make a device equipped with In addition, when a display device is configured using an organic EL panel in which a predetermined number of organic EL elements as pixels are formed on a substrate as a display panel, the liquid crystal display device has high visibility and no viewing angle dependency. There are benefits that cannot be obtained.

  By the way, organic substances such as organic light emitting materials used in organic EL elements are weak against moisture and oxygen, and their performance deteriorates. Also, the characteristics of electrodes deteriorate rapidly in the atmosphere due to oxidation. In general, a method has been proposed in which a sealing cap can formed of a metal can, digging glass, or the like is bonded and sealed to an element substrate with an adhesive. This has a hermetically sealed space, is filled with an inert gas, and is further provided with a hygroscopic material. For this reason, since there is a space on the element surface cathode, the element is not deteriorated by external stress. However, although the organic EL element itself is thin, it has a thickness of the sealing member and a space for arranging the hygroscopic material, so that the light emitting element is thick as a whole.

  On the other hand, a close-contact type sealing form in which a thin EL element can be formed and a sealing material is bonded without providing a space on the element surface has been proposed.

As a sealing method of the adhesion type adhesive, for example, Japanese Unexamined 4-212284 discloses, GeO as described in JP-A-5-182759 Patent Publication, on the protective film made of an inorganic compound such as SiO _2, Light A method of fixing a glass substrate via a curable resin or the like is known.

However, in these methods, when the adhesive and the photo-curing resin are cured, the volume shrinks and thus a residual stress is generated. This residual stress is caused by the organic EL element to be sealed and the adhesive or photo-curing resin. Even if there is a film of GeO, SiO ₂ or the like between them, if the film thickness is as small as μm, it is transmitted to the organic EL. Since the residual stress is particularly strong at a portion having a small radius of curvature, the residual stress propagated to the organic EL element is concentrated on the end portion of the organic EL element. As a result, it is known that the electrode end of the element is crushed, and the anode and cathode come into contact with each other, causing a short circuit. This is a close-contact type sealing method using an adhesive and a photocurable resin. Measures for mitigating residual stress when an adhesive or a photocurable resin is cured have been studied. For example, a method is known in which a stress relaxation layer is provided between an organic EL element and an adhesive, and a sealing material is fixed with the adhesive. This has a problem that the electrode end portion is crushed and short-circuited due to the effect of residual stress due to volume shrinkage when the adhesive is cured, and is intended to alleviate this (see, for example, Patent Document 1). . As an adhesive layer on the organic EL element, the adhesive shrinkage of the adhesive on the organic EL element side is set to two layers by using an adhesive smaller than the shrinkage ratio of the adhesive on the sealing material side to cure the adhesive. A method is known in which a sealing material is fixed with an adhesive so that the light emitting element is not affected by stress due to shrinkage (see, for example, Patent Document 2).

  However, the methods described in Patent Document 1 and Patent Document 2 provide stress relaxation means by curing shrinkage of the adhesive on the organic EL element, which increases the number of processes, does not increase productivity, and increases costs. However, there are still issues that require some countermeasures.

From such a situation, in order to obtain a thin and lightweight organic EL element using a glass substrate, when fixing a sealing material with an adhesive by an adhesion type sealing method, the organic EL element can be manufactured without increasing the number of steps. Development of a sealing method and an organic EL element that do not cause performance deterioration is desired.
Japanese Patent Laid-Open No. 8-124777 JP 2003-109750 A

  The present invention has been made in view of the above circumstances, and its purpose is to reduce the performance of an organic EL element when a thin and lightweight organic EL element is fixed with an adhesive using an adhesion type sealing method. It is providing the sealing method which does not produce and the organic EL element manufactured with this sealing method.

  The above object of the present invention has been achieved by the following constitution.

  1. An organic electroluminescence element having a first electrode, at least one organic compound layer including a light emitting layer, and a second electrode on a substrate is sealed with a flexible sealing member having a barrier property through an adhesive. In the sealing method of the organic electroluminescent element to be stopped, the adhesive is disposed on the entire surface including the outer peripheral surface of the light emitting part in a state where the light emitting part of the organic electroluminescent element and the tip of the external extraction electrode are exposed, An organic electroluminescence element sealing comprising: stacking the flexible sealing member on an adhesive; pressing only the adhesive portion of the outer peripheral surface of the flexible sealing member; Method.

  2. 2. The method for sealing an organic electroluminescence element according to 1 above, wherein the adhesive is a photo-curing type or a thermo-curing type.

3. Pressing force when crimping the bonding portion of the outer peripheral surface, 0.5 × 10 ⁴ Pa~20 sealing method of an organic electroluminescent device according to the 1 or 2, wherein the × a 10 ⁴ Pa .

  4). 4. The organic electroluminescent element according to any one of 1 to 3, wherein the flexible sealing member is made of a resin base material, has a moisture-proof layer, and has a thickness of 30 to 300 μm. Sealing method.

  5. An organic electroluminescence element manufactured by the sealing method according to any one of 1 to 4 above.

  A sealing method that does not cause deterioration in performance of an organic EL element when a thin and lightweight organic EL element is fixed with an adhesive by an adhesion type sealing method, and an organic EL element manufactured by this sealing method It was possible to provide high-quality organic EL elements without increasing the number of processes and without reducing the production efficiency.

  Embodiments of the present invention will be described with reference to FIGS. 1 to 6, but the present invention is not limited thereto.

  FIG. 1 is a schematic cross-sectional view showing an example of a layer structure of an organic EL element.

  In the figure, 1 indicates an organic EL element. The organic EL element 1 includes a first electrode 102, a hole transport layer (hole injection layer) 103, an organic compound layer (light emitting layer) 104, an electron injection layer 105, and a second electrode on a glass substrate 101. The electrode 106, the adhesive 107, and the sealing member 108 are provided in this order. Reference numeral 102 a denotes an external extraction electrode of the first electrode 102, and reference numeral 106 a denotes an external extraction electrode of the second electrode 106. The organic EL element 1 shown in this figure is in close contact with the sealing member 108 via the adhesive layer 107 except for the external extraction electrode 102a of the first electrode 102 and the tip of the external extraction electrode 106a of the second electrode 106. It has a sealed structure.

  In the organic EL element shown in this figure, a hole injection layer (not shown) may be provided between the first electrode 102 and the hole transport layer 103. Further, an electron transport layer (not shown) may be provided between the second electrode 106, the organic compound layer (light emitting layer) 104, and the electron injection layer 105.

  The layer configuration of the organic EL element shown in this figure shows an example, but the following configuration can be given as a layer configuration of another typical organic EL element.

(1) Glass substrate / first electrode (anode) / light emitting layer / electron transport layer / second electrode (cathode) / sealing member (2) glass substrate / first electrode (anode) / hole transport layer / light emitting layer / Hole blocking layer / electron transport layer / second electrode (cathode) / sealing member (3) glass substrate / first electrode (anode) / hole transport layer (hole injection layer) / light emitting layer / hole blocking Layer / electron transport layer / cathode buffer layer (electron injection layer) / second electrode (cathode) / sealing member (4) glass substrate / first electrode (anode) / anode buffer layer (hole injection layer) / hole Transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer (electron injection layer) / second electrode (cathode) / sealing member In the case of an organic EL device, the first electrode (anode) 102 side is usually On the observation side, the first electrode (anode) 102 includes ITO (mixture of tin oxide and indium oxide), IZO (zinc oxide and Indium oxide mixture), ZnO, SnO ₂ , In ₂ O _{3 and the} like are known. Among them, the ITO electrode has a high light transmittance of 90% or more and a low sheet resistance value of 10Ω / □ or less, and is also used as a transparent electrode for liquid crystal displays and solar cells. Further, the IZO electrode has an advantage that a predetermined low resistance value can be obtained without heating the substrate at the time of formation, and the film surface is smoother than the ITO electrode.

  FIG. 2 is an enlarged schematic sectional view of a portion indicated by T in FIG.

  The sealing member 108 is composed of a flexible sealing member having a resin base material 108a and a moisture-proof layer 108b. Note that a protective layer (not shown) may be provided on the moisture-proof layer 108b (in this figure, between the moisture-proof layer 108b and the adhesive layer). The resin base material 108a may be a single body or a laminate, and can be appropriately selected as necessary. The moisture-proof layer 108b may be a single body or a laminated body, and can be appropriately selected as necessary. The flexible sealing member 108 is bonded onto the second electrode via an adhesive.

  The resin base material 108a constituting the flexible sealing member used in the present invention is not particularly limited. For example, ethylene tetrafluoroethyl copolymer (ETFE), high density polyethylene (HDPE), oriented polypropylene (OPP) ), Polystyrene (PS), polymethyl methacrylate (PMMA), stretched nylon (ONy), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polyimide (PI), polyether styrene (PES), etc. A thermoplastic resin film material can be used. As these thermoplastic resin films, a multilayer film produced by coextrusion with a different film, a multilayer film produced by bonding with different stretching angles, etc. can be used as required. Further, it is naturally possible to combine the density and molecular weight distribution of the film used to obtain the required physical properties.

Examples of the moisture-proof layer include inorganic vapor-deposited films and metal foils. As inorganic vapor deposition films, thin film handbooks p879-p901 (Japan Society for the Promotion of Science), vacuum technology handbooks p502-p509, p612, p810 (Nikkan Kogyo Shimbun), vacuum handbook revised editions p132-p134 (ULVAC Japan Vacuum Technology KK) Inorganic films as described in (1). For example, In, Sn, Pb, Au , Cu, Ag, Al, Ti, a metal such as _{Ni, MgO, SiO, SiO 2,} Al 2 O 3, GeO, NiO, CaO, BaO, Fe 2 O 3, Y 2 O ₃ , TiO ₂ , Cr ₂ O ₃ , Si _x O _y (x = 1, y = 1.5 to 2.0), Ta ₂ O ₃ , ZrN, SiC, TiC, PSG, Si ₃ N ₄ , SiN Single crystal Si, amorphous Si, W, or the like is used.

  Moreover, as a material of the metal foil, for example, a metal material such as aluminum, copper, or nickel, or an alloy material such as stainless steel or an aluminum alloy can be used, but aluminum is preferable in terms of workability and cost. The film thickness is about 1 to 100 μm, preferably about 10 to 50 μm.

  In the present invention, when the organic EL element having the configuration shown in FIG. 1 is tightly sealed using the flexible sealing member shown in FIG. The present invention relates to the manufactured organic EL element.

  FIG. 3 is a schematic plan view of the organic EL element shown in FIG. 1 before sealing with a flexible sealing member.

  In the figure, reference numeral 109 denotes a light emitting portion where the first electrode 102 and the second electrode 106 overlap, and reference numeral 110 denotes the external extraction electrode 102a and the external extraction electrode 102a in a state where the tip of the external extraction electrode 106a is exposed. An outer peripheral surface of the light emitting portion including a part of the external extraction electrode 106a (a portion indicated by hatching in the drawing) is shown. It becomes a part to be done. Other reference numerals are the same as those in FIG.

  This figure shows a passive surface emitting organic EL element, but the organic EL element according to the present invention is not particularly limited, and examples thereof include a passive full color system and an active full color system.

  FIG. 4 is a schematic view of the organic EL element in a state where a flexible sealing member is superimposed on the organic EL element shown in FIG. FIG. 4A is a schematic plan view of the organic EL element in a state where a flexible sealing member is superimposed on the organic EL element shown in FIG. FIG. 4B is a schematic cross-sectional view taken along line AA ′ of FIG.

  This figure shows a state where the flexible sealing member 108 on which the adhesive 107 is disposed is overlaid on the organic EL element. The adhesive 107 disposed on the flexible sealing member 108 is flexible including the light emitting portion 109 and the outer peripheral surface 110 with the external extraction electrode 102a and the external extraction electrode 106a of the organic EL element exposed. It arrange | positions so that the sealing member 108 may be bonded. Reference numeral 107 a denotes an adhesive disposed on the flexible sealing member corresponding to the outer peripheral surface 110 of the light emitting unit 109. The adhesive 107 a on the outer peripheral surface 110 is pressure-bonded via the sealing member 108. The ear width of the adhesive 107a is preferably 0.5 mm to 3 mm in consideration of end sealability and panel size reduction.

  Adhesives include photo-curing and thermosetting adhesives with reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and epoxy and other heat and chemical curing (two-component mixed) adhesives, cations An ultraviolet curable epoxy resin adhesive of a curing type or the like can be exemplified. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned.

  The thickness of the adhesive to be arranged is preferably 5 to 100 μm in consideration of the curing reaction time, the influence on the organic layer, the moisture penetration from the edge, etc. for both the liquid type and the sheet type. As a method of arranging the adhesive, since the adhesive to be used may be a liquid type or a sheet type, it is possible to cope with the type of the adhesive. For example, when the adhesive is a liquid type, the flexible extraction member 108 is screen-printed in consideration of production efficiency and film thickness stability in order to expose the leading ends of the external extraction electrode 102a and the external extraction electrode 106a. It is preferable to coat. In the case of a sheet type, a sheet-like adhesive having a required size is disposed on the flexible sealing member 108 at a position where the leading ends of the external extraction electrode 102a and the external extraction electrode 106a are exposed. Is possible. In addition, in order to avoid adhesion of foreign substances, it is preferable to clean the place where the adhesive is disposed before placing the adhesive on the sealing member, for example, with an adhesive roll cleaner or UV ozone cleaning.

  Although this figure shows the case where the adhesive is disposed on the flexible sealing member 108, the location where the adhesive is disposed is not particularly limited, and the distal ends of the external extraction electrode 102a and the external extraction electrode 106a are arranged. It is also possible to arrange them in organic EL elements.

  5 presses the flexible sealing member at a position corresponding to the outer peripheral surface of the light emitting portion of the organic EL element in a state where the flexible sealing members shown in FIG. It is a schematic flowchart which shows the state to paste.

  In the figure, 2 indicates a pressing member. The pressing surface of the pressing member 2 is dug in a concave shape so that the pressing force is not transmitted to the light emitting portion when the pressing member 2 presses and presses on the flexible sealing member 108. And a pressing portion 202 for pressing the position of the flexible sealing member 108 corresponding to the outer peripheral surface 110 (see FIG. 4) of the light emitting portion 109 (see FIG. 4). The shape is around the portion 201.

The flexible sealing member 108 superimposed on the light emitting portion 109 (see FIG. 4) of the organic EL element corresponds to the outer peripheral surface 110 (see FIG. 4) of the light emitting portion 109 (see FIG. 4). Only the adhesive surface of the flexible sealing member 108 at the position is pressed by the pressure-bonding member 2 (in the direction of the arrow in the figure) and pressure-bonded, whereby the flexible sealing member 108 is attached to the light emitting portion 109 and the outer peripheral surface 110. The match ends. The pressure bonding is preferably performed simultaneously with a uniform pressing force on the peripheral surface of the light emitting portion 109. The pressing force is 0 in consideration of poor adhesion at the end due to insufficient load, protrusion of adhesive due to overload, damage to external electrodes, and the like. 5 × 10 ⁴ Pa to 20 × 10 ⁴ Pa are preferable. In general, the pressing force is, for example, a method in which a compressed air pressure applied to a pneumatic cylinder is controlled by a regulator. The desired thrust is set by converting the cylinder thrust corresponding to the regulator pressure from the thrust area. At the time of pasting, according to the kind of used adhesive agent, it carries out together with hardening processes, such as heat processing and ultraviolet irradiation.

  The thickness of the flexible sealing member 108 is preferably 30 to 300 μm in consideration of deformation relaxation property, handling property, separation means forming property, cutting property and the like due to curing shrinkage of the adhesive.

The moisture permeability of the flexible sealing member is 0.01 g / m ² · day or less in consideration of the generation of dark spots accompanying the crystallization of the organic layer and the long life of the organic EL element. preferable. The moisture permeability is a value measured mainly by the MOCON method by a method based on JIS K7129B method (1992).

The oxygen permeability is preferably 0.01 ml / m ² · day · atm or less in consideration of the generation of dark spots accompanying crystallization of the organic layer and the extension of the lifetime of the organic EL device. The oxygen permeability is a value measured mainly by the MOCON method by a method based on JIS K7126B method (1987).

  From the arrangement of the adhesive shown in FIG. 4 to the curing treatment of the adhesive, it is important that the water concentration and the oxygen concentration are low from the viewpoint of reducing the lifetime due to the deterioration of the organic EL element, preferably the water concentration is 10 ppm or less, oxygen It is preferable to carry out in an environment with a concentration of 10 ppm or less. Bonding is preferably performed in a reduced pressure environment of 1 Pa to 30 kPa in consideration of air bubbles.

The following effect was acquired by the sealing method of the organic EL element by a flexible sealing member through the adhesive agent shown in FIGS.
1. When bonding flexible sealing members, only the peripheral surface of the light emitting part is crimped, so damage due to external pressure during bonding can be prevented, and it is thin and lightweight using a stable quality glass substrate. An organic EL element can be obtained.
2. Since the flexible sealing member relieves the stress caused by the shrinkage of the adhesive generated by the curing process of the light emitting part, the performance of the light emitting part can be prevented from being deteriorated, and a stable quality glass substrate is used. It became possible to obtain a thin and lightweight organic EL element.
3. When the flexible sealing member is bonded, only the peripheral surface of the light emitting part is pressure-bonded, so that the uniform height of the adhesion between the organic EL element and the sealing member can be achieved on the peripheral surface. It was possible to make the thickness of the film uniform.
4). Since it is not necessary to provide a separate functional layer to relieve the stress caused by the shrinkage of the adhesive generated by the curing process, glass with stable quality without increasing the number of processes, reducing productivity, or increasing costs It has become possible to obtain a thin and lightweight organic EL element using a substrate.

Hereinafter, the main layers constituting the organic EL element according to the present invention will be described.
<Light emitting layer>
The light emitting layer of the organic EL device according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is a layer of the light emitting layer. It may be the interface between the light emitting layer and the adjacent layer. For the production of the light-emitting layer, a light-emitting dopant or a host compound, which will be described later, is formed and formed by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink-jet method. I can do it. It is preferable that the light-emitting layer contains a host compound and a light-emitting dopant (also referred to as a light-emitting dopant compound) and emits light from the dopant.

  As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of light emission dopants mentioned later, and, thereby, arbitrary light emission colors can be obtained.

  The light emitting host may be a conventionally known low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light emitting host). Specific examples of known host compounds include compounds described in the following documents. For example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787 gazette, 2002-15871 gazette, 2002-334788 gazette, 2002-43056 gazette, 2002-334789 gazette, 2002-75645 gazette, 2002-338579 gazette. No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. 2002-302516, 2002-305083, 2002-305084, 2002-308837, and the like.

  Next, the light emission dopant used for an organic EL element is demonstrated. As the light-emitting dopant, a fluorescent compound or a phosphorescent material (also referred to as a phosphorescent compound or a phosphorescent compound) can be used. The phosphorescent emitter is preferably a complex compound containing a group 8-10 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, a platinum compound (platinum complex compound), or a rare earth complex. Among them, the most preferable is an iridium compound.

  Specific examples of the compound used as the phosphorescent emitter are shown below, but the present invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704 to 1711, and the like.

  Representative examples of fluorescent emitters (fluorescent dopants) include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes. Examples thereof include dyes, perylene dyes, stilbene dyes, polythiophene dyes, and rare earth complex phosphors.

  Conventionally known dopants can also be used in the present invention. For example, WO 00/70655 pamphlet, JP 2002-280178 A, 2001-181616, 2002-280179, 2001 181617, 2002-280180, 2001-247859, 2002-299060, 2001-313178, 2002-302671, 2001-345183, 2002. No. 324679, International Publication No. 02/15645, JP 2002-332291 A, 2002-50484, 2002-332292, 2002-83684, JP 2002-540572, JP 20 2-117978, 2002-338588, 2002-170684, 2002-352960, WO01 / 93642, JP2002-50483, 2002-1000047 No. 2002-173684, No. 2002-359082, No. 2002-17584, No. 2002-363552, No. 2002-184582, No. 2003-7469, No. 2002-525808. JP, 2003-7471, JP, 2002-525833, JP, 2003-31366, JP, 2002-226495, JP, 2002-234894, JP, 2002-235076, JP, 2002-241751. Gazettes, 2001-319779, 2001-319780, 2002-62824, 2002-1000047, 2002-203679, 2002-343572, 2002-203678 Etc.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and may exist between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer. .

  An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
As described above, the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

  The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. By blocking this, the recombination probability of electrons and holes can be improved. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer as needed. In general, the hole blocking layer of the organic EL device is preferably provided adjacent to the light emitting layer.

  On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material having a function of transporting holes while having a very small ability to transport electrons, and transporting electrons while transporting holes. By blocking, the probability of recombination of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed. In general, the thickness of the hole blocking layer and the electron transporting layer is preferably 3 to 100 nm, and more preferably 5 to 30 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

  The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

  The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ', N'-tetraphenyl-4,4'-diaminophenyl; N, N'-diphenyl-N, N'- Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' − (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two more described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

  JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used.

  The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. I can do it. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. This hole transport layer may have a single layer structure composed of one or more of the above materials.

  A hole transport layer having a high p property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

  Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material can be selected and used from the conventionally known compounds, such as nitro-substituted fluorene derivatives and diphenylquinone derivatives. Thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like. Furthermore, in the above oxadiazole derivatives, thiadiazole derivatives in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and quinoxaline derivatives having a quinoxaline ring known as an electron-withdrawing group can also be used as the electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  Also, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum. Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. Further, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and, like the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC. A semiconductor can also be used as an electron transport material.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  An electron transport layer having a high n property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

<< First electrode: Anode >>
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such an electrode substance include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) that can form a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not required (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, the transmittance is desirably greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

<< Second electrode: Cathode >>
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Suitable are a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

  Moreover, after producing the above metal with a film thickness of 1 to 20 nm on the cathode, a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode thereon. By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

EXAMPLES Hereinafter, although an Example is given and the specific effect of this invention is shown, the aspect of this invention is not limited to this Example 1
<< Production of organic EL element >>
After patterning a substrate having a 150 nm ITO film formed on a glass plate as an anode (NH Techno Glass, NA-45), the transparent support substrate provided with the ITO transparent electrode was ultrasonicated with iso-propyl alcohol. Washed, dried with dry nitrogen gas, and UV ozone washed for 5 minutes.

This transparent support substrate is fixed to a substrate holder of a commercially available vacuum deposition apparatus, while α-NPD, CBP, Ir (ppy) ₃ , BCP, and Alq ₃ are placed in five tantalum resistance heating boats, respectively, and vacuum It attached to the vapor deposition apparatus (1st vacuum tank). Further, lithium fluoride was put into a resistance heating boat made of tantalum, and aluminum was put into a resistance heating boat made of tungsten, respectively, and attached to the second vacuum tank of the vacuum evaporation apparatus.

First, after reducing the pressure of the first vacuum tank to 4 × 10 ⁻⁴ Pa, the tantalum resistance heating boat containing α-NPD is energized and heated, and transparent at a deposition rate of 0.1 nm to 0.2 nm / sec. It vapor-deposited so that it might become a film thickness of 25 nm on the support substrate, and provided the positive hole injection / transport layer.

Further, the tantalum resistance heating boat containing CBP and the tantalum resistance boat containing Ir (ppy) ₃ are energized independently, and the deposition rate of CBP as a light emitting host and Ir (ppy) _{3 as} a light emitting dopant is increased. The light emitting layer was provided by adjusting the film thickness to 100: 7 and depositing the film to a thickness of 30 nm.

Subsequently, the resistance heating boat made of tantalum containing BCP was energized and heated to provide a hole blocking layer electron transport layer having a thickness of 10 nm at a deposition rate of 0.1 to 0.2 nm / second. Further, a resistance heating boat made of tantalum containing Alq ₃ was energized and heated to provide an electron transport layer electron injection layer having a film thickness of 40 nm at a deposition rate of 0.1 nm to 0.2 nm / second.

Next, the element formed up to the electron transport layer and the electron injection layer as described above was transferred to the second vacuum chamber while maintaining a vacuum, and the second vacuum chamber was depressurized to 2 × 10 ⁻⁴ Pa, and then made of tantalum containing lithium fluoride. A resistance heating boat is energized to provide a cathode buffer layer with a film thickness of 0.5 nm at a deposition rate of 0.01 nm / sec to 0.02 nm / sec, and then a tantalum resistance heating boat containing aluminum is energized to a deposition rate of 1 nm. An organic EL device having a layer structure shown in FIG. 5 was obtained by attaching a cathode having a film thickness of 150 nm at a rate of 2 / second to 2 nm / second. Further, the organic EL element was transferred to a nitrogen atmosphere (under a high purity nitrogen gas having a purity of 99.999% or more) without being brought into contact with the air.

《Sealing work》
<Preparation of gas barrier flexible film (sealing film)>
As a base material, an inorganic gas barrier film made of SiOx was formed on a polyethylene terephthalate film (a film made by Teijin DuPont, hereinafter abbreviated as PET) by an atmospheric pressure plasma discharge treatment apparatus, and an oxygen permeability of 0.01 ml / A high gas barrier film having a m ² / day or less and a water vapor permeability of 0.01 g / m ² / day or less was produced.

<Sealing of organic EL element by flexible sealing member>
Using the prepared organic EL element, except for the external extraction electrode of the organic EL element shown in FIG. 3, the adhesive shown below was applied to the sealing member surface corresponding to the light emitting portion and the outer peripheral surface by a screen printing method to achieve a thickness of 0. Placed at 1 mm. As the adhesive, UV resin XNR5516 manufactured by Nagase Chemtech Co., Ltd. was used.
Thereafter, the flexible sealing member with an adhesive is overlaid on the organic EL element as shown in FIG. 5, and the pressing force of the adhesive portion on the outer peripheral surface is changed as shown in Table 1 below. A flexible sealing member is bonded by pressure bonding, and an organic EL element is produced by applying an irradiation energy of 6000 mJ / cm ² or more with a handy high-pressure mercury lamp (OHD-110M-ST) manufactured by Oak Manufacturing Co. Sample No. 101-110. In addition, when bonding a flexible sealing member, the organic EL element surface formed on the glass is faced to the barrier film side so as to face the sealing member to which the adhesive is applied, and alignment is performed. Then, after reducing the pressure to 100 Pa around the periphery, pressure is applied on the sealing member via the pressing member. As the pressing member, flat glass was used. As shown in FIG. 5, the pressing surface of the flat glass was provided with a 1 mm deep digging portion at a portion corresponding to the light emitting portion, and a crimping portion was disposed around the digging portion. The pressing member is pressed from above the sealing member, and in a state where only the crimping portion is crimped with a desired load, a high-pressure mercury lamp is irradiated from above the glass to cure the pressing surface and the element surface of the organic EL element. went. In addition, an organic EL element was produced by sealing the light emitting portion and the outer peripheral surface with a pressing force of 2 × 10 ⁴ Pa with a flat glass not provided with a 0.7 mm digging portion (full surface pressure bonding). . 111. The adhesive may be a thermosetting type.

(Evaluation)
Each prepared sample No. Table 1 shows the results obtained by testing leak current values and non-luminous failures (dark spots) by the following test methods according to the evaluation ranks shown below.

Test Method for Leakage Current Value The current value in positive polarity and reverse polarity at constant voltage driving was obtained and calculated from the following formula.

Leakage current value = current value (positive) / current value (reverse)
Evaluation rank of leakage current value ○: 1000 or more Δ: 1000 to 500
×: 500 measures three numbers visually by magnifier follows non emission fault (dark spot) Test method Not emitting black spot failure to emit non-light-emitting element (dark spots), non per area 2 mm ² area The number of light emission failures was calculated as the average of three locations.

Evaluation rank of non-luminous failure (dark spot) ○: 0 △: 1 to 3 ×: 4 or more

  The effectiveness of the present invention was confirmed.

It is a schematic sectional drawing which shows an example of the laminated constitution of an organic EL element. It is an expansion schematic sectional drawing of the part shown by T of FIG. It is a schematic plan view of the organic EL element shown in FIG. 1 before sealing with a flexible sealing member. It is the schematic of the organic EL element of the state which accumulated the flexible sealing member on the organic EL element shown by FIG. The flexible sealing member in a position corresponding to the outer peripheral surface of the light emitting portion of the organic EL element in a state where the flexible sealing members shown in FIG. 4 are overlapped is pressed, and the flexible sealing member is bonded. It is a schematic flowchart which shows a state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic EL element 101 Glass base material 102 1st electrode 102a, 106a External extraction electrode 103 Hole transport layer (hole injection layer)
104 Organic compound layer (light emitting layer)
DESCRIPTION OF SYMBOLS 105 Electron injection layer 106 2nd electrode 107, 107a Adhesive 108 Sealing member 108a Resin base material 108b Moisture-proof layer 109 Light emission part 110 Outer peripheral surface 2 Pressing member 201 Digging part 202 Pressing part

Claims (5)

An organic electroluminescence element having a first electrode, at least one organic compound layer including a light emitting layer, and a second electrode on a substrate is sealed with a flexible sealing member having a barrier property through an adhesive. In the sealing method of the organic electroluminescence element to be stopped,
The adhesive is disposed on the entire surface including the outer peripheral surface of the light emitting part in a state where the light emitting part of the organic electroluminescence element and the tip of the external extraction electrode are exposed,
Overlaying the flexible sealing member on the adhesive,
A method for sealing an organic electroluminescent element, wherein only a bonding portion of the outer peripheral surface of the flexible sealing member is pressure-bonded and then cured. The method for sealing an organic electroluminescence element according to claim 1, wherein the adhesive is a photo-curing type or a thermosetting type. Sealing of the pressing force to an organic electroluminescent device according to claim 1 or 2, characterized in that it is ^{0.5 × 10 4 Pa~20 × 10 4} Pa at the time of crimping the bonding portion of the outer peripheral surface Method. The organic electroluminescent element according to claim 1, wherein the flexible sealing member is made of a resin base material, has a moisture-proof layer, and has a thickness of 30 to 300 μm. Sealing method. An organic electroluminescence element manufactured by the sealing method according to claim 1.

Images