JP4844256B2 - Organic electroluminescence device - Google Patents

Description

  The present invention relates to an organic electroluminescence element (hereinafter, referred to as organic EL element) substrate that is expected to be widely used as a display such as an information display terminal, and a method for manufacturing the same. In particular, the present invention relates to a top emission type organic EL element having a light extraction direction opposite to a substrate and a manufacturing method thereof.

  An organic EL device has a structure in which a thin film containing a luminescent material is sandwiched between a cathode and an anode, and excitons (excitons) are generated by injecting electrons and holes into the thin film and recombining them. The device emits light by utilizing light emission (fluorescence / phosphorescence) when the exciton is deactivated.

The characteristics of this organic EL element are that it can emit surface light with a high luminance of about 100 to 100,000 cd / m ² at a low voltage of 10 V or less, and can emit light from blue to red by selecting the type of luminescent material. It is a thing.

  Organic EL elements are attracting attention as a means for realizing inexpensive large-area full-color display elements (Non-Patent Document 1). According to reports, organic dyes that emit strong fluorescence are used in the light emitting layer, and bright red (R), green (G), and blue (B) light emission is obtained. This is considered to have realized a high-luminance full-color display by using an organic dye that emits strong fluorescence in a thin film state and has few pinhole defects.

  Further, Patent Document 1 provides a thin film layer in which a component of the organic light emitting layer is a mixture of an organic charge material and an organic light emitting material, prevents concentration quenching, widens the selection range of the light emitting material, and provides a high-luminance full-color element. The effect is proposed.

  Organic EL materials can be broadly divided into two types: low molecular weight materials and high molecular weight materials. Low molecular weight materials are generally deposited by vapor deposition, but the vapor deposition equipment and alignment accuracy for large substrates are used. In terms of size, it is difficult to increase the size.

  Therefore, recently, a method of using a polymer material as an organic light emitting material, dissolving the organic light emitting material in a solvent to form an ink, and forming a thin film by a wet coating method has been tried. As the wet coating method for forming a thin film, there are a spin coating method, a bar coating method, a protruding coating method, a dip coating method, etc., but in order to use an organic EL element as a display, it is patterned with high definition or RGB three colors. In order to paint differently, these wet coating methods are difficult, and it is considered most effective to form a thin film by a printing method that is good at painting patterning. Actually, as a trial of these printing methods, a method using ink jet printing (Patent Document 2), a method using letterpress printing (Patent Document 3), and the like have been proposed.

The organic EL element is classified into a bottom emission type and a top emission type depending on the light extraction direction. The bottom emission type takes out light from the substrate side, whereas the top emission type takes out light from the side opposite to the substrate.
Japanese Patent Application Laid-Open No. 5-78655 JP-A-10-012377 JP 2001-155858 A IEICE Technical Report, Volume 89, NO. 106, 49 pages, 1989

  When organic light-emitting materials are converted into ink and organic light-emitting layers that emit light in different colors are formed for each pixel, the purpose is to prevent inks of different colors from mixing with each other and to cover the anode end to prevent short circuits. It is necessary to provide a partition between the pixel electrodes. Generally, the organic light emitting material has poor solubility in a solvent, and the concentration of the organic light emitting ink obtained by dissolving or dispersing the organic light emitting material in the solvent is as low as about 1 to 5 wt%. In order to supply the necessary amount of organic light-emitting material to each pixel, when the ink is arranged in the pixel area partitioned by the partition using such a low concentration organic light-emitting ink, the pixel area partitioned by the ink is used. It is necessary to supply a large amount inside. Therefore, when the partition walls are lowered, ink enters pixel regions having different emission colors across the partition walls, color mixing occurs, and the quality of the organic EL element as a display is degraded. Even when a large amount of ink is supplied to the partitioned pixel area, it is necessary to sufficiently increase the height of the partition wall in order to prevent ink from entering the adjacent pixels.

  Further, in an organic EL element substrate in which a substrate, an organic light emitting medium layer including at least a pixel electrode, an organic light emitting layer, and a counter electrode are formed on the substrate, moisture and oxygen inside the element substrate, in particular, the organic light emitting layer Sealing is performed to prevent intrusion. In the case of a bottom emission type organic EL element in which the light extraction direction is the substrate side, an organic EL element substrate using a glass or metal cap (sealing cap) provided with a recess in accordance with an effective pixel portion used for display as a display The organic EL element was formed by sealing by bonding the peripheral portion of the effective pixel formed in the above through an adhesive. In addition, a desiccant, an oxygen absorbent, and the like were provided inside the sealing cap.

  On the other hand, in the case of the top emission method in which the light extraction direction is opposite to the substrate, sealing is performed using a sealing base material having translucency. In this case, if a light-transmitting adhesive is used, the light-transmitting sealing substrate and the entire surface of the organic EL element substrate on which the counter electrode is formed can be bonded together, and sealing is more reliably performed. Can be done. In addition, if necessary, an inorganic thin film is deposited as a water vapor barrier layer on the entire surface of the organic EL element substrate on which the counter electrode is formed or on the entire surface of the sealing substrate for the purpose of preventing moisture from entering the element substrate. The vacuum film forming method can be used.

  As described above, when the sealing base material is bonded to the entire surface of the counter electrode forming surface of the organic EL element substrate through an adhesive, there is a problem that air is mixed during bonding due to the unevenness of the surface of the organic EL element substrate. . This problem has occurred particularly when the organic EL element substrate has a structure including partition walls. Furthermore, since the partition walls are usually formed to partition the pixels, air contamination is likely to occur in the vicinity of the pixels that contribute to display as a display, affecting the visibility, and improving the light emission characteristics over time. The problem of dropping will occur. Such a problem can be prevented to some extent from air mixing by increasing the thickness of the adhesive or the water vapor barrier layer. However, in order to improve the brightness of top emission type organic EL elements, there is a demand to make the adhesive and the water vapor barrier layer as thin as possible and to prevent the light transmittance from being reduced by these layers as much as possible. This solution is against that requirement.

  Further, when the water vapor barrier layer is formed on the entire surface of the counter electrode of the organic EL element substrate so as to cover the unevenness of the organic EL element substrate, when the thickness of the water vapor barrier layer is large, the water vapor barrier layer is formed at the step portion of the unevenness. There is a problem that cracks are easily generated. When a crack occurs in the water vapor barrier layer, moisture enters from the cracked portion, thereby reducing the lifetime of the organic EL element.

  As described above, the present invention provides an organic EL element that exhibits good display characteristics without air mixing when the sealing substrate is bonded to the entire surface of the effective pixel through an adhesive to the organic EL element substrate. For the purpose.

In order to solve the above-mentioned problems, an invention according to claim 1 is provided with an organic light emitting medium layer including a substrate, a pixel electrode provided on the substrate, and an organic light emitting layer having different emission colors on the pixel electrode. An organic electroluminescent element substrate comprising a counter electrode facing the pixel electrode across the organic light emitting medium layer, a water vapor barrier layer formed on the organic electroluminescent element substrate, and the organic electroluminescent element substrate, In an organic electroluminescence element formed by bonding a sealing base material via an adhesive , the organic electroluminescence element substrate has a partition wall, and the inside of the effective pixel of the organic electroluminescence element substrate on which the counter electrode is formed And the height of the partition wall is 1.5 μm or less from the pixel electrode. The organic electroluminescence element substrate further includes a water vapor barrier layer formed on the counter electrode on the entire surface of the effective pixel, the water vapor barrier layer formed on the counter electrode, and the water vapor barrier layer on the surface of the effective pixel. an adhesive layer formed on, and the organic electroluminescent element, characterized in that it comprises a sealing base material formed on the adhesive layer, the.

The invention according to claim 2 is the organic electroluminescence device according to claim 1 , wherein the water vapor barrier layer is made of silicon nitride or silicon oxynitride .

The invention according to claim 3 provides the organic electroluminescent element according to claim 2 , wherein the water vapor barrier layer has a thickness of 0.02 μm to 0.3 μm .

The invention according to claim 4 is the organic electroluminescent element according to any one of claims 1 to 3 , wherein the substrate and the sealing material are made of a flexible film material.

  According to the present invention, when the height difference of the organic EL element substrate is set to 1 μm or less, the organic EL element in which air is not mixed when the sealing substrate is bonded to the entire effective pixel of the organic EL element substrate through the adhesive. Could get. Since the organic EL element using the organic EL element substrate of the present invention is sealed without forming air around the pixels that contribute to display as a display without forming an adhesive layer or a water vapor barrier layer thickly. When the top emission type organic EL element is used, particularly good display characteristics can be exhibited. Moreover, even if it seals under atmospheric pressure, since it can seal without entering air, the manufacturing process of an organic EL element can be simplified and cost can be reduced. Furthermore, since air does not enter the display element, it is possible to suppress deterioration of the light emission characteristics of the organic EL element.

  The organic EL element of the present invention will be described. In addition, the organic EL element which concerns on this invention, and its manufacturing method are not limited to implementation demonstrated below. Hereinafter, an example in which the present embodiment is applied to a passive matrix driving type organic EL display panel will be described. As a driving method of the organic EL element, there are a passive matrix and an active matrix. However, the organic EL element in this embodiment can be applied to either a passive matrix type or an active matrix type organic EL element.

  Moreover, the organic EL element of the present invention can be applied to both the substrate side and the sealing side in the light extraction direction. That is, the organic EL element of the present invention can be applied to both a bottom emission type organic EL element that extracts light emitted from the substrate side and a top emission type organic EL element that extracts light emitted from the opposite side of the substrate. is there. Furthermore, the organic EL element of the present invention can also be applied to a transparent organic EL element that extracts light emitted from both sides.

  In the present invention, an organic EL element substrate is provided with a substrate, a pixel electrode, an organic light emitting medium layer including an organic light emitting layer, and a counter electrode on the substrate. Moreover, what was sealed by providing a water vapor | steam barrier layer etc. on this organic EL element board | substrate as needed, and sticking the sealing base material and the organic EL element board | substrate through the adhesive agent with an organic EL element. To do. FIG. 1 shows an explanatory cross-sectional view of the organic EL element substrate of the present invention.

  In the present invention, an effective pixel means an opposing electrode on an organic EL element substrate, and an organic light emitting medium layer sandwiched between both electrodes (this organic light emitting medium layer includes at least an organic light emitting layer). Refers to a region in which a barrier rib is formed, and a region that contributes to information display and light emission as a display device after being manufactured as an organic EL element.

  The organic EL element of the present invention has a pixel electrode 2 on a substrate 1, and a partition wall 6 is provided between the pixel electrodes. An organic light emitting medium layer including organic light emitting layers (41, 42, 43) is formed in the pixel electrode partitioned by the partition walls 6. A counter electrode 5 is formed on the organic light emitting medium layer. In FIG. 1, since the counter electrode is laminated on the entire surface of the organic light emitting medium layer forming layer without being patterned, it is also formed on the partition wall. However, the counter electrode is patterned on the partition wall as necessary. May not be formed.

  The organic light emitting medium layer may be composed of a single layer of an organic light emitting layer, but in addition to the organic light emitting layer, for the purpose of assisting light emission in the organic light emitting layer, a hole transport layer, a hole injection layer, an electron transport A layer and an electron injection layer are provided as appropriate. In FIG. 1, the organic light emitting medium layer has a two-layer structure of a hole transport layer 3 and organic light emitting layers (41, 42, 43). An organic light emitting layer including an organic light emitting material that emits light of different colors such as RGB is disposed for each pixel. In FIG. 1, an organic EL element substrate in which three colors of a red organic light emitting layer (41), a green organic light emitting layer (42), and a blue organic light emitting layer (43) are formed in a stripe shape is cut so as to cross the stripe. It is sectional drawing.

  In the present invention, the organic EL element substrate refers to a substrate including a pixel electrode, a partition, an organic light emitting medium layer including at least an organic light emitting layer, and a counter electrode. In the present invention, the difference in height within the effective pixels of the organic EL element substrate refers to the difference in height of the portion of the organic EL element substrate that has pixels that will contribute to the display of information as a display device. Specifically, the difference between the height (H1) of the portion where the partition is provided and the height (H2) in the pixel electrode partitioned by the partition (that is, the height in each pixel region (pixel electrode formation portion)). It is. In the organic EL element substrate of the present invention, the height of the partition wall that partitions each pixel and prevents color mixing of inks is equal to the height obtained by adding the thicknesses of the pixel electrode and the organic light emitting medium layer. The difference is 1 μm or less. Note that the height difference in the effective pixel is preferably 0.3 μm or less. When the height difference in the effective pixel of the organic EL element substrate exceeds 1 μm, there arises a problem that air is mixed into the organic EL element due to the unevenness of the organic EL element substrate when bonded to the sealing substrate.

  FIG. 2 shows an explanatory cross-sectional view of the organic EL device of the present invention. A water vapor barrier layer is provided on an organic EL element substrate in which a pixel electrode, an organic light emitting medium layer, and a counter electrode are formed on a substrate. At this time, at least the entire surface of the effective pixels included in the organic EL element substrate is covered with the water vapor barrier layer and bonded to the sealing base material. Then, the sealing substrate and the organic EL element substrate are pasted together with an adhesive. At this time, at least the entire surface of the effective pixels included in the organic EL element substrate is covered with the adhesive and is bonded to the sealing substrate. In addition, when a plastic base material etc. are used for the sealing base material, you may provide a water vapor | steam barrier layer in the sealing base material side. The water vapor barrier layer preferably has an oxygen barrier function, and the water vapor barrier layer may have a multilayer structure.

  Next, an organic EL element substrate and an organic EL element manufacturing method of the present invention will be described.

  As the substrate in the present invention, any substrate can be used as long as it is an insulating substrate. Moreover, it is preferable to have a strength that can support the pixel electrode, the organic light emitting medium layer, and the counter electrode provided on the substrate. When used in a bottom emission type organic EL element that extracts light from the substrate side, it is necessary to use a transparent substrate. For example, a glass substrate or a plastic film or sheet can be used. If a flexible plastic film is used, an organic EL element can be manufactured by a winding method, and the element can be provided at low cost. Examples of the plastic that can be used as the film-like substrate include polyethylene terephthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, and polycarbonate.

  Moreover, it is preferable to reduce the water | moisture content adsorb | sucked in the board | substrate inside or the surface as much as possible by heat-processing these board | substrates beforehand. Further, in order to improve the adhesion depending on the material to be laminated on the substrate, it is preferable to use after performing surface treatment such as ultrasonic cleaning treatment, corona discharge treatment, plasma treatment, UV ozone treatment. In addition, a thin film transistor (TFT) may be formed on these substrates to form an active matrix driving substrate. The TFT material may be an organic TFT such as polythiophene, polyaniline, copper phthalocyanine or perylene derivative, or may be amorphous silicon or polysilicon TFT.

  The present invention can be applied to both an organic EL display element of a passive matrix type organic EL display element and an active matrix type organic EL display element. The passive matrix method is a method in which pixel electrodes and counter electrodes are formed in stripes, the opposing electrodes are arranged so as to be orthogonal, and light is emitted from each intersection. The active matrix method is a method in which light is emitted independently for each pixel by using a so-called thin film transistor (TFT) substrate in which a transistor is formed for each pixel electrode. In addition, it can be applied to a specific delta arrangement in the active matrix system.

  A pixel electrode is formed on this substrate. When the pixel electrode is used as an anode, this material may be a metal composite oxide such as ITO (indium tin composite oxide), IZO (indium zinc composite oxide), zinc aluminum composite oxide, chromium, gold, platinum, etc. Either a single layer or a laminate of a metal material or a fine particle dispersion film in which fine particles of these metal oxides or metal materials are dispersed in an epoxy resin or an acrylic resin can be used. When the organic EL element is a top emission type, a material that reflects light is mainly used. A dry coating method can be used as a method for forming the pixel electrode. For example, resistance heating vapor deposition, electron beam vapor deposition, reactive vapor deposition, ion plating, and sputtering.

  For example, it is possible to form a pixel electrode by applying a photoresist to a vacuum-formed metal oxide film, exposing / developing, processing by wet etching or dry etching, and processing into a pattern. In order to lower the electric resistance, a metal such as copper, chromium, aluminum, titanium, or a laminate thereof can be partially provided on the pixel electrode as an auxiliary electrode. When manufacturing a passive matrix type organic EL element, the pixel electrode is formed in a stripe shape, and when manufacturing an active matrix type organic EL element, the pixel electrode corresponds to a transistor provided on the substrate. Each is formed.

Next, a partition is formed between the pixel electrodes. Examples of the partition wall forming material include a photosensitive resin, which may be either a positive type resist or a negative type resist, and may be a commercially available one, but must have insulating properties. In the case where the partition has no insulating property, a current flows through the partition to the adjacent pixel electrode, resulting in a display defect. Specific examples include polyimide, acrylic resin, and novolac resin. Further, for the purpose of improving the display quality of the organic EL element, a light shielding material such as carbon particles may be contained.
The height of the partition wall is a factor that determines the height difference in the effective pixels of the organic EL element substrate of the present invention. In order to set the difference between the highest portion and the lowest portion in the effective pixel of the organic EL element substrate to 1 μm or less, it is necessary to set the height of the partition wall low and not to stack unnecessary layers on the partition wall. In addition, it is preferable that the layer formed on each pixel partitioned by the partition wall is also formed thinly and uniformly. Therefore, the difference between each pixel electrode and the height of the partition wall is preferably 1.5 μm or less in consideration of the thickness of the organic light emitting medium layer and the counter electrode to be formed later.

  Next, an organic light emitting medium layer is formed. The organic light emitting medium layer may be composed of an organic light emitting layer alone, an organic light emitting layer, and a layer for assisting light emission such as a hole transport layer, a hole injection layer, an electron transport layer, and an electron injection layer. May be combined to form a laminated structure. Note that a layer that assists light emission, such as a hole transport layer, a hole injection layer, an electron transport layer, and an electron injection layer, is appropriately selected.

  The organic light emitting layer is a layer containing an organic light emitting material that emits light when a current flows. As organic light-emitting materials, 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolato) aluminum complex, tris (4-methyl-8) -Quinolate) aluminum complex, bis (8-quinolate) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolate) aluminum complex, tris (4-methyl-5-cyano-8-quinolate) aluminum complex Bis (2-methyl-5-trifluoromethyl-8-quinolinolato) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolato) [4- (4 -Cyanophenyl) phenolate] aluminum complex, tris (8-quinolino) ) Scandium complex, bis [8- (paratosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, poly-2,5-diheptyloxy-para-phenylene vinylene, etc. The low molecular weight light emitting material can be used.

  Also, coumarin phosphors, perylene phosphors, pyran phosphors, anthrone phosphors, porphyrin phosphors, quinacridone phosphors, N, N′-dialkyl-substituted quinacridone phosphors, naphthalimide phosphors, A material obtained by dispersing a low molecular weight light emitting material such as an N, N′-diaryl-substituted pyrrolopyrrole fluorescent material or a phosphorescent light emitting material such as an Ir complex in a polymer can be used. As the polymer used for dispersing the light emitting material, polystyrene, polymethyl methacrylate, polyvinyl carbazole, or the like can be used. Further, it may be a polymer light emitting material such as polyarylene, polyarylene vinylene, polyfluorene, polyphenylene vinylene, polyparaphenylene vinylene, polythiophene or polyspiro. In addition, a material obtained by dispersing or copolymerizing the low molecular material in these high molecular materials, or other existing light emitting materials can be used.

  The hole transport layer is a layer containing a hole transport material that transports holes to the organic light emitting layer. As a hole transport material, copper phthalocyanine, metal phthalocyanines such as tetra (t-butyl) copper phthalocyanine and metal-free phthalocyanines, quinacridone compounds, 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine, N, N′-di (1-naphthyl) -N, N ′ -Aromatic amine-based low molecular hole injection and transport materials such as diphenyl-1,1'-biphenyl-4,4'-diamine, polyaniline, polythiophene, polyvinylcarbazole, poly (3,4-ethylenedioxythiophene) Among polymer hole transport materials such as blends with polystyrene sulfonic acid, polythiophene oligomer materials, and other existing hole transport materials It can be selected.

  The electron transport layer is a layer containing an electron transport material that transports electrons to the organic light emitting layer. As an electron transport material, 2- (4-bifinylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (1-naphthyl) -1,3, 4-oxadiazole, an oxadiazole derivative, a bis (10-hydroxybenzo [h] quinolinolato) beryllium complex, a triazole compound, or the like can be used.

  An ink can be obtained by adding a solvent and necessary additives to the functional material contained in each layer. Examples of the solvent for dispersing or dissolving the functional material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, dichloromethane dichloroethane, chloroform, ethyl acetate, ethanol, methanol, 2-methoxyethanol, 2-ethoxy. Ethanol, 2-butoxyethanol, 2-ethylethoxyacetate, 2-butoxyethyl acetate, 2-methoxyethyl ether, 2-ethoxyethyl ether, 2- (2-ethoxyethoxy) ethanol, 2- (2-butoxyethoxy) ethanol , 2- (2′ethoxyethoxy) ethyl acetate, 2- (2-butoxyethoxy) ethyl acetate, glycol, ethylene glycol, propylene glycol monomethyl acetate Le, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, tetrahydrofuran, and water. These solvents may be used alone or in combination. In particular, when the light emitting material is ink, an aromatic organic solvent such as toluene, xylene, and anisole is preferable from the viewpoint of solubility of the light emitting material.

  In the organic EL element substrate of the present invention, the height difference in the effective pixel is suppressed to within 1 μm in order to prevent air from being mixed during sealing. When such an organic EL element substrate includes a partition wall, the height of the partition wall is preferably 1.5 μm or less from the pixel electrode. If it is formed at a height higher than this, it is difficult to reduce the height difference from the upper part of the partition wall to within 1 μm even if an organic light emitting layer and a counter electrode are subsequently formed in each pixel.

  The height of the partition required here is considerably lower than the height of the partition defining the pixel electrode when the organic light emitting layer is formed by, for example, an ink jet method. Therefore, since the ink jet method is a process in which ink is ejected from the head and dropped onto the substrate, ink spreading, positional accuracy error, ink rebound, and the like may occur. Therefore, when an organic light emitting layer is formed in each pixel region, the ink jumps over the partition wall and color mixing with adjacent pixels occurs.

  Therefore, in order to form the organic light emitting layer on the organic EL element substrate of the present invention, it is preferable to use a printing method. As a method for forming the organic light emitting layer, an offset printing method or a relief printing method can be suitably used.

In the offset printing method, an ink pattern is once formed on a transfer support composed of an easily peelable rubber called a blanket, and the ink pattern is transferred to a substrate to be printed. The ink pattern formed on the blanket has an advantage that the ink pattern shape and film thickness can be easily controlled because a part of the ink solvent is absorbed by the blanket and becomes a semi-dry state. Examples of such an offset printing method include an intaglio offset printing method and a relief reversal offset printing method depending on the difference in the method of forming an ink pattern on a blanket.

  In the relief printing method, ink is supplied from an ink chamber to an anilox roll, excess ink is removed by a doctor, and then an anilox and a relief plate made of a rubber plate or a resin plate are brought into contact with each other. In this case, a desired amount of ink is transferred from the anilox roll to the relief plate, and then transferred from the relief plate to the printing substrate. At this time, by adjusting the printing pressure between the relief plate and the printing substrate to be small, it is possible to prevent the ink from jumping across the partition even if the partition is lowered, and to prevent color mixing with adjacent pixels. .

  In this way, even if the height of the partition provided on the organic EL element substrate is set very low, the ink spreads when the ink is transferred to the substrate to be printed by the offset printing method and the relief printing method. Therefore, color mixing with adjacent pixels can be prevented.

As a first example of a printing method that can be used in the present invention, a printing method using an intaglio offset printing apparatus will be described in detail with reference to FIG.
FIGS. 3A to 3D are schematic views showing the intaglio offset printing apparatus and the intaglio offset printing process of the present invention. In FIG. 3, a blanket 13 is mounted around a blanket cylinder 12 above the main body frame 11. Reference numeral 14 denotes a printing stage, which fixes a printing substrate 16 on which an intaglio 15 serving as an original plate or a pixel electrode is formed during printing. The blank cylinder 12 is rotatably installed, and the blanket 13 and the intaglio 15 and the blanket 13 and the substrate to be printed 16 can be brought into contact with each other with a constant pressure. Further, the printing stage 14 is movable in the uniaxial direction. 3 is an organic light-emitting ink (hereinafter referred to as ink), and 18 is a doctor blade that scrapes off excess ink from the intaglio plate 15.

  An intaglio 15 is fixed on the printing stage 14. Ink 17 is supplied onto the intaglio 15 by an ink supply means (not shown), excess ink is removed by the doctor blade as the printing stage 14 moves, and the ink 17 is filled in the pattern portion of the intaglio 15 (FIG. 3A). ). Further, the printing stage 14 is moved and the blank cylinder 12 is rotated, whereby the ink filled in the pattern portion of the intaglio 15 is received on the blanket 13 and an ink pattern is obtained on the blanket (FIG. 3B). Next, when the printing stage 14 is moved and the blanket cylinder 12 is rotated, the ink pattern on the blanket is transferred onto the substrate 16 to be printed, and the printing process is finished (FIGS. 3C and 3D).

  Next, as a second example of a printing method that can be used in the present invention, a printing method by an offset printing apparatus using a relief reversing method will be described in detail with reference to FIG.

  4 (a) to 4 (d) are schematic views showing the relief reversal offset printing apparatus and relief reversal offset printing process of the present invention. In FIG. 4, a blanket 13 is mounted around a blanket cylinder 12 above the main body frame 11. Reference numeral 14 denotes a printing stage, which fixes a printing substrate 16 on which a relief plate 19 that is an original plate or a pixel electrode is formed during printing. The blanket cylinder 12 is rotatably installed, and the blanket 13 and the relief plate 19, and the blanket 13 and the substrate to be printed 16 can be brought into contact with each other with a constant pressure. Further, the printing stage 14 is movable in the uniaxial direction. Also, 17 shown in FIG. 4 is ink.

  A relief plate 19 is fixed on the printing stage 14, and a film of ink 17 is previously coated on the blanket 13 by an ink supply means (not shown) such as a curtain coating method, a bar coating method, a wire coating method, and a slit coating method. Applied uniformly. (FIG. 4A) When the printing stage 14 moves and rotates the blanket cylinder, the pattern portion of the relief plate 19 which is a negative pattern of the desired pattern comes into contact with the ink film on the blanket 13 and corresponds to the pattern portion. Unnecessary portions are removed, and the ink patterned in a desired pattern is left on the blanket (FIG. 4B). Next, the printing stage 14 is moved and the blanket cylinder is rotated, whereby the ink pattern left on the blanket is transferred onto the substrate 16 to be printed, and the printing process is completed (FIGS. 4C and 4D). .

  Next, as a third example of a printing method that can be used in the present invention, a printing method using a relief printing apparatus will be described in detail with reference to FIG.

  FIGS. 5A to 5D are schematic views showing the relief printing apparatus and relief printing process of the present invention. In FIG. 5, an anilox roll 21 and a plate cylinder 22 are provided above the main body frame 11. A printing plate 23 (convex printing plate) having a convex pattern is mounted around the plate cylinder 22. A certain amount of ink is supplied to the anilox roll 21 by the ink supply means 24. The anilox roll 21 is installed so as to be able to come into contact with the plate cylinder 23 while rotating, and can supply the printing plate 23 with a certain amount of ink. Reference numeral 14 denotes a printing stage, which fixes a printed substrate 16 on which pixel electrodes and the like are formed during printing. The plate cylinder 22 is rotatably installed so that the printing plate 23 and the substrate 16 to be printed can contact with each other with a constant pressure. Further, the printing stage 14 is movable in the uniaxial direction.

  The ink 17 is supplied from the ink supply means 24 to the anilox roll 21. Unnecessary ink is scraped off by a doctor blade (not shown), and a certain amount of ink remains on the anilox roll (FIG. 5A). When the anilox roll 21 supplied with the ink 17 and the plate cylinder 22 are in contact with each other while rotating, the ink is transferred onto the convex portion which is the pattern portion of the printing plate 23 (FIG. 5B). Next, when the printing stage 14 moves and the plate cylinder 22 is rotated, the ink pattern is transferred from the convex portion of the printing plate 23 onto the substrate 16 to be printed, and the printing process is completed (FIGS. 5C and 5D). )).

  The above steps are repeated as many times as necessary. An organic light emitting layer can be formed on the organic EL element substrate of the present invention by forming a necessary type of organic light emitting layer by a printing method.

  In addition, as a method for forming a layer that assists light emission, such as a hole transport layer and an electron transport layer, a wet coating method may be used. Examples of the wet coating method include spin coating method, die coating method, dip coating method, discharge coating method, pre-coating method, roll coating method, bar coating method and the like, as well as letterpress printing method and inkjet printing method printing method. . Moreover, you may use the offset printing method of this invention.

  However, in a method of forming a film on the entire surface of the substrate, such as a spin coating method or a die coating method, there is a possibility that the region partitioned by the partition wall is filled and formed to be thicker than necessary. Further, in the organic EL element substrate of the present invention, the height of the partition wall is low, so that the layer for assisting light emission is not partitioned by the partition wall, and it is also formed on the partition wall, shorting adjacent pixels and causing crosstalk. There is a risk of waking up. Accordingly, it is desirable to form layers other than the organic light emitting layer constituting the organic light emitting medium layer, such as a hole transport layer, by a patterning printing method or an offset printing method.

  Next, a counter electrode is formed. When the counter electrode is a cathode, a substance having a high electron injection efficiency is used. Specifically, a single metal such as Mg, AL, or Yb is used, or a compound such as Li, oxidized Li, or LiF is sandwiched by about 1 nm at the interface in contact with the light emitting medium, and Al or Cu having high stability and conductivity is laminated. And use. Alternatively, in order to achieve both electron injection efficiency and stability, one or more metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function and stable Ag, Al An alloy system with a metal element such as Cu is used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used. In the case of the top emission method in which light is extracted from the counter electrode forming side of the organic EL element, the counter electrode needs to have transparency. For example, transparency can be obtained by a combination of a layer made of these metals or metal alloy materials and a transparent conductive material such as ITO.

  As a method for forming the counter electrode, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on the material. The thickness of the counter electrode is preferably about 10 nm to 1 μm. Patterning can also be performed as necessary. For example, when manufacturing a passive matrix organic EL element, the counter electrode is formed in a stripe shape together with the pixel electrode so as to be orthogonal to the pixel electrode. In the case of manufacturing an active matrix organic EL element, the counter electrode is formed on the entire effective pixel. In the present invention, the pixel electrode is an anode and the counter electrode is a cathode. However, the pixel electrode may be a cathode and the counter electrode may be an anode.

  Next, a water vapor barrier layer is provided. As these forming materials, metal oxides such as silicon oxide, silicon nitride, silicon oxynitride, aluminum nitride, and aluminum oxide, and metal nitrides can be used. These materials have an oxygen barrier function in addition to a water vapor barrier function. In particular, silicon nitride and silicon oxynitride having favorable barrier properties, solvent resistance, and transparency are preferable. In order to make the organic EL element of the present invention a top emission type organic EL element, it is necessary to make the water vapor barrier layer, the adhesive layer and the sealing substrate transparent together with the counter electrode. In addition, the barrier layer may have a multilayer structure as necessary. As a method for forming the water vapor barrier layer, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on the material.

  Since the organic EL element substrate of the present invention has an elevation difference of 1 μm or less in the effective pixel, it is not necessary to cover the unevenness by the barrier layer when the water vapor barrier layer is provided, and the film thickness of the barrier layer is 0.3 μm. It can be: In the organic EL device of the present invention, the water vapor barrier layer preferably has a thickness of 0.02 μm or more and 0.3 μm or less. When the water vapor barrier layer is 0.02 μm or less, the water vapor barrier function cannot be sufficiently achieved. Moreover, when the water vapor barrier layer exceeds 0.3 μm, the film peels off or cracks in the water vapor barrier layer.

  Normally, when the barrier layer is made thicker, the water vapor barrier property is improved. On the other hand, the stress inside the film is integrated and increased. As a result, the barrier layer is peeled off and cracks are generated. It penetrates and causes deterioration of the organic light emitting medium layer and shortening of the life of the device. However, since the stress can be relieved by reducing the thickness of the barrier layer to 150 nm or less according to the present invention, deterioration of the organic light-emitting medium layer due to peeling or cracking of the barrier layer, which has been a problem, and the element Can be reduced.

  Next, the sealing base material and the organic EL element substrate are bonded to the entire surface of the effective pixel through an adhesive. As the sealing substrate used, the laminated surface of the organic EL element substrate can be protected and has only to be transparent. For example, a glass substrate, a glass film, a plastic film or a sheet can be used. In the case where a plastic film is used and winding is used, the device can be provided at low cost. As the plastic, for example, polyethylene terephthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate and the like can be used. A barrier layer that prevents permeation of water vapor or oxygen may be formed on the sealing substrate side. In particular, when a sealing material is a plastic material that transmits water vapor or oxygen, it is preferable to form a barrier layer.

  In the case of a bottom emission type organic EL element, the sealing substrate does not necessarily require translucency, but the adhesive used for bonding to the organic EL element substrate is a photosensitive type that is cured by light irradiation. In that case, a light-transmitting material is selected.

  The adhesive that bonds the sealing substrate and the organic EL element substrate may be a known one as long as it has transparency, and examples thereof include a thermosetting resin and a photocurable resin. For example, as the thermosetting resin, melamine type, acrylic type, O-cresol novolac type, bisphenol type epoxy type, urethane type and the like can be used. Further, the adhesive of the present invention may be liquid or sheet-like, and if it is liquid, the organic EL element substrate is effective by spin coating, bar coating, protruding coating, dip coating, etc. It is applied to the entire surface of the pixel and pasted with a sealing substrate. Moreover, if an adhesive agent is a sheet form, it will be pasted with a sealing base material with a laminator. The adhesive can be selected from either a thermosetting type or a photocurable type, but it is preferable to select a photocurable adhesive in order to prevent deterioration of the organic light emitting layer. Further, in order to prevent moisture from entering from the adhesive layer, the adhesive may contain a moisture-proofing agent or a hygroscopic agent.

  Moreover, the organic EL element of this invention can be made into a flexible substrate by using the film material which has flexibility for a board | substrate and a sealing base material. In the organic EL element of the present invention, since the thickness of the adhesive layer can be reduced, a flexible organic EL element having sufficient flexibility can be obtained. In addition, since the thickness of the water vapor barrier layer can be reduced, the water vapor barrier layer is cracked when the obtained flexible organic EL element is bent as compared with the case where the water vapor barrier layer is formed thick. Since it becomes difficult, the locality limit of a flexible organic EL element can be enlarged. In addition, as a film material used for a board | substrate and a sealing base material, the plastic film as shown previously can be used conveniently.

First, a glass substrate on which a thin film transistor corresponding to each pixel was formed was prepared.
ITO was formed to a thickness of 0.1 μm on the thin film transistor forming side of this glass substrate by sputtering. A photoresist was applied on the ITO formed on the entire surface, exposed and developed through a predetermined mask, and then wet-etched to form a pixel electrode corresponding to the thin film transistor.

  Next, a partition wall having a height of 1.0 μm was formed between the pixel electrodes. The partition wall divides adjacent pixels and is formed so as to cover the end of each pixel electrode patterned corresponding to the thin film transistor. As a partition wall material, a novolak resin, which is a photosensitive resin, was used. After coating on one surface of the pixel electrode, patterning was performed by exposing through a predetermined mask and then developing.

An organic light emitting medium layer was formed on the pixel electrode partitioned by the partition walls. Here, the organic light emitting medium layer includes a hole transport layer common to all pixels and an organic light emitting layer that emits light of a predetermined color.
Polytetrahydrothiophenylphenylene, which is a polymer precursor, was used as the hole injection material, and an aqueous solution of the polymer precursor was applied on the entire surface of the pixel electrode partitioned by the partition by spin coating. By heating, the precursor became polyphenylene vinylene, and a hole injection layer having a thickness of 0.05 μm was formed on each pixel electrode.

  Next, cyanopolyphenylene vinylene was used as a red light emitting material, polyphenylene vinylene was used as a green light emitting material, polyphenylene vinylene was used as a blue light emitting material, and these organic light emitting materials were dissolved in toluene to obtain light emitting material inks of respective colors. Subsequently, red, green, and blue light emitting material inks were printed on the hole transport layer by a letterpress reverse offset printing method to form an organic light emitting layer having a thickness of 0.05 μm. The pixel array formed here is a stripe array in which pixels emitting light of the same color are arranged in a straight line.

  Next, MgAg was formed as a counter electrode with a thickness of 0.01 μm on the entire surface of the organic light-emitting medium layer by vapor deposition, and ITO was further formed with a thickness of 0.1 μm by sputtering to form an organic EL element substrate. . The unevenness in the effective pixels of the organic EL element substrate thus obtained was about 0.7 μm.

  Next, silicon oxide was formed on the organic EL element substrate as a water vapor barrier layer with a thickness of 1.0 μm by a vapor deposition method. On top of that, a sheet-like epoxy adhesive having a thickness of 30 μm was attached to a glass plate using a laminator and heated to obtain an active matrix top emission type organic EL device. When the obtained organic EL element was observed with a microscope, it was not confirmed that air was mixed in the effective pixel region of the organic EL element. Further, no color mixture with adjacent pixels was observed.

  On the surface of the silicon oxide film on the polyethylene terephthalate (PET) film on which a silicon oxide film is laminated in advance, ITO is formed with a thickness of 0.1 μm by sputtering, a photoresist is applied, exposure and development are performed, Subsequently, stripe-like pixel electrodes were formed by performing wet etching. At this time, the line pattern of ITO which is the pixel electrode was a pattern in which the line width was 100 μm, the space was 50 μm, and the line was formed with 192 lines.

  Next, a partition wall was formed between the pixel electrodes in a line shape parallel to the first electrode so as to cover an end portion of the line-shaped pixel electrode. At this time, the height of the partition wall was 0.8 μm, and a novolac resin, which is a photosensitive resin, was used as the partition wall material, and pattern formation was performed by exposure and development.

  Next, polytetrahydrothiophenylphenylene, which is a polymer precursor, was formed by a spin coating method as a hole injection material. By heating, the precursor became polyphenylene vinylene, and a hole injection layer having a thickness of 0.05 μm was formed.

  Next, cyanopolyphenylene vinylene was used as the red light-emitting material, polyphenylene vinylene was used as the green light-emitting material, polyphenylene vinylene and polyalkylphenylene were used as the blue light-emitting materials, and these organic light-emitting materials were dissolved in toluene to obtain inks of various colors. Subsequently, red, green and blue inks were printed on the line-shaped pixel electrodes by a relief printing method to form an organic light emitting layer having a thickness of 0.05 μm.

  Next, MgAg was patterned as a counter electrode with a thickness of 0.01 μm by a vapor deposition method using a mask, and ITO was patterned on the MgAg with a thickness of 0.1 μm by a sputtering method. The counter electrode made of MgAg and ITO at this time was formed to be orthogonal to the line-shaped pixel electrode. The unevenness in the effective pixel was about 0.5 μm.

  Next, silicon oxide was formed as a water vapor barrier layer with a thickness of 0.1 μm on the organic EL element substrate by a vapor deposition method. On top of that, a sheet-like epoxy adhesive having a thickness of 30 μm was laminated with a polyethylene terephthalate (PET) form using a laminator and heated to obtain a passive matrix top emission type flexible organic EL element. When the obtained organic EL element was observed with a microscope, it was not confirmed that air was mixed in the organic EL element. Moreover, when the obtained organic EL element was made to light-emit, favorable light emission was obtained, and the obtained organic EL element was flexible.

(Comparative example)
When the height of the partition wall was 2.0 μm and the device was fabricated in the same manner as in Example 2, the height difference in the pixel was about 1.7 μm. When the obtained organic EL element was observed with a microscope, it was confirmed that bubbles were mixed in the organic EL element.

It is sectional explanatory drawing of the organic EL element of this invention. It is a section explanatory view of the organic EL element substrate of the present invention. It is the schematic diagram which showed the intaglio offset printing apparatus and intaglio offset printing process of this invention. It is the schematic diagram which showed the letterpress reverse offset printing apparatus and letterpress reverse offset printing process of this invention. It is the schematic diagram which showed the relief printing apparatus and relief printing process of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Pixel electrode 3 Hole transport layer 41 Red organic light emitting layer 42 Green organic light emitting layer 43 Blue organic light emitting layer 5 Counter electrode 6 Barrier layer 7 Adhesive 8 Sealing base material 11 Main body frame 12 Blanket cylinder 13 Blanket 14 Printing stage 15 Intaglio 16 Printed substrate 17 Ink 18 Doctor blade 19 Top plate 21 Anilox roll 22 Plate cylinder 23 Plate 24 Ink supply means

Claims (4)

A substrate, a pixel electrode provided on the substrate, and an organic light-emitting medium layer including an organic light-emitting layer having a different emission color are provided on the pixel electrode, and face the pixel electrode with the organic light-emitting medium layer interposed therebetween An organic electroluminescence element substrate comprising a counter electrode ;
In the organic electroluminescence element formed by bonding the water vapor barrier layer formed on the organic electroluminescence element substrate, the organic electroluminescence element substrate and the sealing base material through an adhesive ,
The organic electroluminescence element substrate has a partition, and the height difference in the effective pixel of the organic electroluminescence element substrate on which the counter electrode is formed is 1 μm or less, and the height of the partition is from the pixel electrode. Within 1.5 μm,
The organic electroluminescence element substrate further includes:
On the counter electrode, a water vapor barrier layer formed by laminating the counter electrode over the entire effective pixel;
An adhesive layer formed on the entire surface of the effective pixel on the water vapor barrier layer;
The organic electroluminescence element of the sealing base material formed on the adhesive layer, characterized in that it comprises a.
The organic electroluminescence element according to claim 1, wherein the water vapor barrier layer is made of silicon nitride or silicon oxynitride. The organic electroluminescence device according to claim 2 , wherein the water vapor barrier layer has a thickness of 0.02 µm to 0.3 µm. The organic electroluminescent device according to any one of claims 1 to 3, characterized in that it consists of a film material the sealing material and the substrate has flexibility.

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