JP2013105694A - Organic electroluminescent element and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element having an organic luminescent layer formed by a letterpress printing method, which is designed to prevent the ink supplied to before and after a barrier between first electrodes from flowing in and substantially equalize the film thickness of an organic luminescent layer near the barrier and that of an organic luminescent layer at center of the electrode, thereby realizing high optical characteristics free of emission unevenness and color mixture within a pixel and emission unevenness between pixels.SOLUTION: In an organic electroluminescent element, pixels composed of successively laminated first electrodes (pixel electrodes) and organic luminescent layers are partitioned by barriers on a substrate, and further a second electrode is provided on the organic luminescent layer side so as to face the first electrodes. The organic electroluminescent element includes a second barrier provided in the middle between the pixels portioned by the barriers.

Description

  The present invention relates to an organic electroluminescence element (hereinafter referred to as an organic EL element) expected to be used for a display such as an information display terminal, and a method for producing the same.

  An organic EL element is one in which an organic light emitting layer made of an organic light emitting material is formed between two opposing electrodes, and light is emitted by passing a current through the organic light emitting layer. The film thickness is important, and it is necessary to form a thin film of about 100 nm. Furthermore, in order to make this a display, it is necessary to pattern the organic light emitting layer with high definition so that each pixel becomes red (R), green (G), and blue (B).

  Organic light-emitting materials that form the organic light-emitting layer include low-molecular materials and high-molecular materials. Generally, low-molecular materials are formed into a thin film by a dry film-forming method such as resistance heating vapor deposition, and a fine pattern mask is used at this time. However, this method has a problem that the patterning accuracy is less likely as the substrate becomes larger.

  Therefore, recently, a method of forming a thin film by a wet film forming method using a polymer material as an organic light emitting material and dispersing or dissolving the organic light emitting material in a solvent to form a coating liquid has been tried. . As a wet film forming method for forming a thin film, there are a spin coating method, a bar coating method, a protruding coating method, a dip coating method, and the like. These wet coating methods are difficult, and it is thought that thin film formation by a printing method that is good at coating and patterning is most effective.

  Further, among various printing methods, in organic EL elements and displays using glass as a substrate, a method using a hard plate such as a metal printing plate such as a gravure printing method is unsuitable, and an elastic rubber blanket. An offset printing method using, and a relief printing method using an elastic rubber plate or resin plate are also suitable. Actually, as an attempt by these printing methods, a method by offset printing (Patent Document 1), a method by letterpress printing (Patent Document 2), and the like have been proposed.

  The organic light-emitting material, which is a material for forming the organic light-emitting layer, has poor solubility in water and alcohol solvents, and it is necessary to dissolve and disperse using an organic solvent in order to form a coating liquid (hereinafter referred to as ink). Among them, organic solvents such as toluene and xylene are preferable. Therefore, the ink of organic light emitting material (hereinafter referred to as organic light emitting ink) is an ink of organic solvent.

  However, the rubber blanket used for offset printing has a problem that it is easily swelled or deformed by toluene or xylene organic solvent. The types of rubber used in blankets vary from olefin rubber to silicon rubber, but none of these rubbers are resistant to toluene, xylene or other solvents, and are prone to swelling and deformation, so organic It is not suitable for printing luminescent ink.

  In addition, the relief printing method using an elastic relief plate includes a flexographic printing method using a rubber plate and a resin relief plate method using a resinous plate. Among these, a method using a water development type resin relief plate is used. If present, it has high resistance to organic solvents such as toluene and xylene, and can be used for printing organic light-emitting inks.

JP 2001-93668 A JP 2001-155858 A

  In general, when an organic light-emitting layer is formed on an active matrix substrate using a relief printing method, the convex portion of a resin relief plate having a line pattern is continuously applied with ink so as to straddle the partition between the first electrodes. Supplied and printed. Accordingly, the organic light emitting ink is supplied to both the patterned first electrode and the partition between the first electrodes. Even in such a case, the thickness of the organic light emitting layer in the vicinity of the partition becomes thicker than the thickness of the organic light emitting layer in the center of the electrode due to the flow of ink supplied before and after the partition between the first electrodes. And variations in the amount of ink supplied for each first electrode surrounded by the partition wall, uneven light emission within the pixels (e.g., uneven light emission region), uneven light emission between pixels (pixels) There was a problem in that there was a variation in the light emission area between them.

  The present invention is an organic EL element in which an organic light emitting layer is formed by a relief printing method, and prevents the flow of ink supplied before and after the partition between the first electrodes, and the thickness of the organic light emitting layer in the vicinity of the partition It is an object of the present invention to provide an organic EL element having high optical characteristics free from uneven light emission and color mixing within a pixel, and uneven light emission between pixels.

  In the invention according to claim 1 of the present invention, a pixel formed by sequentially laminating a first electrode (pixel electrode) and an organic light emitter layer is partitioned on a substrate by a partition wall, and further on the organic light emitter layer side An organic electroluminescence element having a second electrode provided so as to face the first electrode, wherein a second partition is provided at a central portion between pixels partitioned by the partition. is there.

  In the invention according to claim 2 of the present invention, the height of the partition wall is a reverse taper shape of 1.0 μm or less, the height of the second partition wall is 1.0 to 2.0 μm, and is adjacent. 2. The organic electroluminescence device according to claim 1, wherein the second partition wall is discontinuous.

  Moreover, the invention according to claim 3 of the present invention is the method for producing an organic electroluminescent element according to claim 1 or 2, wherein at least one layer of the organic light emitter layer composition constituting the organic light emitter layer comprises: An organic electroluminescent element manufacturing method comprising forming an ink by dissolving or dispersing in a solvent and forming an organic light-emitting layer by a wet film forming method using the ink.

  The invention according to claim 4 of the present invention is the method for producing an organic electroluminescent element according to claim 3, wherein the wet film forming method is a relief printing method.

  According to the present invention, the flow of ink supplied before and after the partition between the first electrodes is prevented by the relief printing method, and the film thickness of the organic light emitting layer in the vicinity of the partition is substantially equal to the film thickness of the organic light emitting layer in the center of the electrode. Accordingly, it is possible to provide an organic EL element having high optical characteristics free from uneven light emission and color mixing within the pixel and uneven light emission between pixels.

Explanatory sectional drawing of the organic EL element of this invention. Explanatory sectional drawing before the positive hole transport layer and organic light emitting layer printing of the organic EL element of this invention. The schematic diagram of the example of arrangement | positioning of the partition of this invention. The arrangement figure of the partition of the present invention, and the mimetic diagram seen from the side. 1 is a schematic view of a relief printing apparatus of the present invention. The schematic of the partition formation of this invention.

  Hereinafter, the organic EL element of the present invention will be described more specifically with reference to the drawings.

  FIG. 1 is an explanatory sectional view of an organic EL device of the present invention. As shown in FIG. 1, the organic EL element of the present invention has a first electrode 2 on a glass substrate 1. In the case of the passive matrix system, the first electrode 2 has a stripe pattern. In the case of the active matrix method, the first electrode 2 has a pattern for each pixel. The present invention is applicable to both passive matrix type organic EL elements and active matrix type organic EL elements.

  The organic EL element of the present invention has an organic light emitting medium layer on the first electrode 2 and in a region (pixel) partitioned by the partition walls 51. The organic light emitting medium layer may be composed of an organic light emitting layer alone, or may be composed of a laminated structure of an organic light emitting layer and a light emission auxiliary layer. FIG. 1 shows an organic light emitting medium layer composed of a laminated structure of a hole transport layer 3 which is a light emission auxiliary layer and organic light emitting layers (41, 42, 43). A hole transport layer 3 is provided on the first electrode 2, and an organic light emitting layer 41 (red), an organic light emitting layer 42 (green), and an organic light emitting layer 43 (blue) are provided on the hole transport layer 3. Yes. An ink reservoir 44 is provided between the partition wall 51 and the second partition wall 52 provided at the center.

  Moreover, the state before apply | coating the positive hole transport layer 3 and the organic light emitting layers 41, 42, and 43 is introduced as FIG.

  Further, the second electrode 6 is disposed on the organic light emitting layer. In the case of the passive matrix system, the second electrode 6 is provided in a stripe shape so as to be orthogonal to the first electrode 2 having a stripe shape. In the case of the active matrix method, the second electrode 6 is formed on the entire surface of the organic EL element.

  Moreover, the example of arrangement | positioning of the partition of this invention was shown to FIG. In the active matrix organic EL element, the first electrode 2 is formed for each pixel. When an organic light emitting layer is formed by a relief printing method using organic light emitting inks having different emission colors such as red (R), green (G), and blue (B), the resin plate used in the relief printing method is striped. Ink is also supplied between the first electrodes. The printing direction in the relief printing method is indicated by an arrow Y. At this time, as shown in FIGS. 3 and 4 with respect to the printing direction Y, by providing the second partition 52 at the center between the pixels partitioned by the partition 51, unnecessary ink flows to the ink reservoir 44.

  Next, the manufacturing method of the organic EL element according to the present invention will be described.

  As the substrate according to the present invention, any substrate can be used as long as it has an insulating property. In the case of a bottom emission type organic EL element that emits light from the substrate side, it is necessary to use a transparent substrate.

  For example, a glass substrate or a quartz substrate can be used. Further, it may be a plastic film or sheet such as polypropylene, polyethersulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate. Metal oxide thin film, metal fluoride thin film, metal nitride thin film, metal oxynitride thin film, or polymer resin film for the purpose of preventing moisture from entering the organic light emitting medium layer in these plastic films and sheets You may utilize what laminated | stacked these as a board | substrate.

  In addition, it is more preferable to reduce the moisture adsorbed on the inside or the surface of the substrate as much as possible by performing a heat treatment on these substrates in advance. 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.

  Further, a thin film transistor (TFT) can be formed on these to form a substrate for an active matrix organic EL element. A known thin film transistor can be used as the thin film transistor. Specifically, a thin film transistor mainly including an active layer in which a source / drain region and a channel region are formed, a gate insulating film, and a gate electrode can be given. The structure of the thin film transistor is not particularly limited, and examples thereof include a staggered type, an inverted staggered type, a top gate type, and a coplanar type.

  The active layer is not particularly limited, and examples thereof include inorganic semiconductor materials such as amorphous silicon, polycrystalline silicon, microcrystalline silicon, cadmium selenide, thiophene oligomers, poly (p-ferylene vinylene), and the like. It can be formed of an organic semiconductor material.

  These active layers are formed by, for example, depositing amorphous silicon by plasma CVD, ion doping, forming amorphous silicon by LPCVD using SiH4 gas, and crystallizing amorphous silicon by solid phase growth to form polysilicon. Then, an amorphous silicon is formed by an ion implantation method using an ion implantation method, an LPCVD method using Si2H6 gas, or a PECVD method using SiH4 gas, and then annealed by a laser such as an excimer laser, to form amorphous silicon. After polysilicon is obtained by crystallization, polysilicon is deposited by ion doping (low temperature process), low pressure CVD or LPCVD, and thermally oxidized at 1000 ° C. or higher to form a gate insulating film Formed, the gate electrode of the n + polysilicon is formed thereon, then, a method of ion doping (high temperature process), and the like by an ion implantation method.

  As the gate insulating film, those normally used as the gate insulating film can be used. For example, SiO2 formed by PECVD method, LPCVD method, etc .; SiO2 obtained by thermally oxidizing the polysilicon film, etc. Can be used.

  As a gate electrode, what is normally used as a gate electrode can be used, for example, metals, such as aluminum and copper, refractory metals, such as titanium, tantalum, and tungsten, polysilicon, silicide of a refractory metal, Polycide etc. are mentioned.

  The thin film transistor may have a single gate structure, a double gate structure, or a multi-gate structure having three or more gate electrodes. Moreover, you may have a LDD structure and an offset structure. Further, two or more thin film transistors may be arranged in one pixel. The organic EL element of the present invention needs to be connected so that the thin film transistor functions as a switching element of the organic EL element, and the drain electrode of the transistor and the first electrode 2 of the organic EL element are electrically connected. The thin film transistor, the drain electrode, and the first electrode 2 of the organic EL element are connected through a connection wiring formed in a contact hole that penetrates the planarization film.

  A first electrode 2 is provided on the substrate. When the first electrode 2 is used as an anode, the material is a metal such as ITO (indium tin composite oxide), IZO (indium zinc composite oxide), tin oxide, zinc oxide, indium oxide, zinc aluminum composite oxide, etc. A single layer or laminated layer of metal materials such as composite oxide, gold, platinum, and chromium can be used. The first electrode 2 can be formed by a dry film forming method such as 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 depending on the material.

  In addition, ITO is preferably used because of its low resistance, solvent resistance, and high transparency when the bottom mission method is adopted. ITO is formed on the glass substrate 1 by a sputtering method, and is patterned by the photolithography method to form the first electrode 2.

After the first electrode 2 is formed, a second partition 52 is formed at the center between the partition 51 and the pixel partitioned by the partition 51 so as to cover the edge of the first electrode. The partition wall 51 and the second partition wall 52 at the center between the pixels partitioned by the partition wall 51 need to have insulating properties, and a photosensitive material or the like can be used. The photosensitive material may be a positive type or a negative type, a photo-curing resin of a photo radical polymerization system, a photo cationic polymerization system, or a copolymer containing an acrylonitrile component, polyvinyl phenol, polyvinyl alcohol. , Novolac resin, polyimide resin, cyanoethyl pullulan, and the like can be used. Further, as a partition wall forming _material, it is also possible to use SiO 2, TiO ₂ or the like.

When the partition wall forming material is a photosensitive material, the entire surface of the forming material solution is coated by a slit coating method or a spin coating method, and then patterning is performed by a photolithography method such as exposure and development. In the case of the spin coating method, the height of the partition wall can be controlled by conditions such as the number of rotations when spin coating, but there is a limit height in one coating, and if it is higher than that, multiple spin coatings are performed. Use an iterative approach. Further, when the partition wall forming material is SiO ₂ or TiO ₂ , it can be formed by a dry film forming method such as a sputtering method or a CVD method. The patterning of the partition walls can be performed by a mask or a photolithography method.

  At this time, the height and shape of each of the pixel partition 51 and the second partition 52 in the center between the pixels are important points. First, a method for forming a partition wall will be described below, but this is an example and is not limited to the following. First, a photosensitive material is applied to the substrate by the above-described spin coating method to form the partition wall 51, and then prebaked on a hot plate, and the substrate is exposed after a photomask on which a pattern is drawn is overlaid thereon. Irradiated by the machine. The photosensitive material irradiated here is developed with an alkaline developer, and the developer is washed with water, and then the substrate is post-baked in an oven. A patterned partition wall can be formed by the above steps. The height of the partition wall 51 formed here should be low in order to improve the flatness of the organic light emitting layers 41, 42, 43, and is preferably 1.0 μm or less. In addition, the central partition 52 formed by the same method should be as high as possible to prevent color mixing. However, if it is too high, defects may occur in the transfer of ink from the plate to the pixels, or the second electrode 6 may be disconnected. And there is a limit to the height. The height is preferably in the range of 1.0 to 2.0 μm. Further, when the value is less than 1.0 μm set as the lower limit, color mixture tends to occur. In addition, since the shape of the second partition 52 at the center between the pixels is a reverse taper, it is possible to reinforce the difficulty of getting over the ink. Further, the ink reservoir 44 secures a sufficient area of about 10 to 15 μm in width. The process of forming the partition is shown in FIG.

  Next, an organic light emitting medium layer is formed. The organic light emitting medium layer may be composed of the organic light emitting layers 41, 42, 43 alone, or the organic light emitting layers 41, 42, 43 and the hole transport layer 3, other hole injection layers, electron transport layers, electrons. A laminated structure with a light emission auxiliary layer for assisting light emission such as an injection layer may be used. The hole transport layer, hole injection layer, electron transport layer, and electron injection layer are appropriately selected as necessary.

  The organic light emitting layers 41, 42, and 43 are layers that emit light when a current is applied. Organic light-emitting materials formed by the organic light-emitting layers 41, 42, and 43 include 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolate). ) Aluminum complex, tris (4-methyl-8-quinolato) aluminum complex, bis (8-quinolato) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolato) aluminum complex, tris (4-methyl) -5-cyano-8-quinolato) 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] a Minium complex, tris (8-quinolinolato) scandium complex, bis [8- (paratosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, 2,5-diheptyloxy-para -A low molecular weight light emitting material such as phenylene vinylene can be used.

  In addition, coumarin phosphors, perylene phosphors, pyran phosphors, anthrone phosphors, polyphyrin 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 pair or a phosphorescent light emitter such as an Ir complex in a polymer can be used. As the polymer, polystyrene, polymethyl methacrylate, polyvinyl carbazole and the like can be used.

  Also, poly (2-decyloxy-1,4-phenylene) (DO-PPP), poly [2,5-bis- [2- (N, N, N-triethylammonium) ethoxy] -1,4-phenyl- Alt-1,4-phenyllene] dibromide (PPP-NEt3) poly [2- (2′-ethylhexyloxy) -5-methoxy-1,4-phenylenevinylene] (MEH-PPV), poly [5-methoxy -(2-propanoxysulfonide) -1,4-phenylenevinylene] (MPS-PPV), poly [2,5-bis- (hexyloxy) -1,4-phenylene- (1-cyanovinylene)] ( CN-PPV) and poly (9,9-dioctylfluorene) (PDAF) may be used. Examples thereof include polymer precursors such as PPV precursor, PNV precursor, and PPP precursor. Further, a material obtained by dispersing or copolymerizing the low-molecular light-emitting material in these polymer materials, or other existing light-emitting materials can also be used.

  As a material for the hole transport layer, metal phthalocyanines such as copper phthalocyanine and 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, Aromatic amine low molecular hole injection and transport materials such as N′-diphenyl-1,1′-biphenyl-4,4′-diamine, polyaniline, polythiophene, polyvinylcarbazole, poly (3,4-ethylenedioxythiophene) ) And polystyrene sulfonic acid and other polymer hole transport materials, polythiophene oligomer materials, and other existing hole transport materials You can choose.

  As a material for the electron transport layer, 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.

Solvents that dissolve or disperse the organic light emitting material include toluene, xylene, acetone, hexane, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate, 2-methyl- (t-butyl) Benzene, 1,2,3,4-tetramethylbenzene, pentylbenzene, 1,3,5-triethylbenzene, cyclohexylbenzene, 1,3,5-tri-isopropylbenzene and the like can be used alone or in combination. . Moreover, surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. may be added to organic luminescent ink as needed.

  Solvents that dissolve or disperse the hole transport material and electron transport material include, for example, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate, water, etc. Alternatively, a mixed solvent thereof can be used. In particular, water or alcohols are suitable when forming a hole transport material into an ink.

  The organic light emitting medium layer is formed by a wet film forming method. In the case where the organic light emitting medium layer has a laminated structure, it is not necessary to form all of the layers by a wet film formation method. As the wet film forming method, spin coating method, die coating method, dip coating method, discharge coating method, pre-coating method, roll coating method, bar coating method and the like, relief printing method, inkjet printing method, offset printing method, Examples of the printing method include a gravure printing method. In particular, when forming the organic light emitting layers 41, 42, and 43, it can be selectively applied to the pixel portion by a printing method. For this reason, it becomes possible to manufacture the organic EL element which can perform a color display by printing to each pixel the light emitting layer which light-emits in a mutually different color.

  In particular, the method for forming the organic light emitting layers 41, 42, 43 is preferably formed by letterpress printing. The relief printing method is different from the ink jet method, and the ink is transferred so that the plate and the substrate are in direct contact. In the present invention, the letterpress used in the letterpress printing method is preferably a water development type resin letterpress. Examples of the water-developable photosensitive resin constituting the resin plate in the present invention include a type having a hydrophilic polymer and a monomer containing an unsaturated bond, a so-called crosslinkable monomer and a photopolymerization initiator as constituent elements. In this type, polyamide, polyvinyl alcohol, cellulose derivatives and the like are used as hydrophilic polymers. Examples of the crosslinkable monomer include methacrylates having a vinyl bond, and examples of the photopolymerization initiator include aromatic carbonyl compounds. Among these, a polyamide-based water-developable photosensitive resin is preferable from the viewpoint of printability.

  The printing apparatus used to form the organic light emitting layers 41, 42, and 43 can be any relief printing apparatus that prints on a flat plate, but the following printing apparatus is desirable. FIG. 6 shows a schematic diagram of the relief printing apparatus of the present invention. This manufacturing apparatus has a plate cylinder 17 to which an ink tank 13, an ink chamber 14, an anilox roll 15, and a resin relief plate 16 are attached. The ink tank 13 contains organic luminescent ink diluted with a solvent, and the organic luminescent ink is fed into the ink chamber 14 from the ink tank 13. The anilox roll 15 rotates in contact with the ink supply unit of the ink chamber 14 and the plate cylinder 17.

  As the anilox roll 15 rotates, the organic light-emitting ink supplied from the ink chamber 14 is uniformly held on the surface of the anilox roll 15 and then has a uniform film thickness on the convex portions of the resin relief plate 16 attached to the plate cylinder 17. It will transfer at. Further, the substrate 18 to be printed is fixed on a slidable substrate fixing base and moved to the printing start position while adjusting the position by the position adjustment mechanism of the plate pattern and the substrate pattern, and the plate cylinder 17 is rotated. At the same time, the convex portion of the resin relief plate 16 further moves while being in contact with the substrate, and the ink is transferred by patterning to a predetermined position of the substrate 18 to be printed on the stage 19.

Next, the second electrode 6 is formed. When the second electrode 6 is a cathode, a material 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. Or, 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, Yb, etc., which have 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. Further, in the case of a top emission type organic EL device, the cathode needs to have transparency, and for example, transparency can be achieved by a combination of these metals and a transparent conductive layer such as ITO.

  As a method for forming the second electrode 6, a dry film forming method such as 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. The thickness is preferably about 10 nm to 1 μm. In the present invention, the first electrode can be a cathode and the second electrode can be an anode.

  And it seals through an adhesive agent with a glass plate, a glass cap, etc., prevents deterioration of the luminescent medium layer etc. by a water | moisture content or oxygen, and becomes an organic EL element.

  Hereinafter, based on an Example, this invention is demonstrated more concretely.

<Example 1>
In order for the thin film transistor to function as a switching element, a top emission backplane formed so as to be connected to the first electrode 2 through a contact hole formed in the planarization film is used, and the number of pixels is 240 × 320 dots. The number of subpixels was 720 × 320 dots. Then, chromium (Cr) was patterned by a sputtering method so that the space between the sub-pixels was 40 μm in length and 100 μm in width at a pitch of 120 μm × 360 μm, thereby forming the first electrode 2.

  Next, 40 ml of TELR series (manufactured by Tokyo Ohka Kogyo Co., Ltd.), a negative photosensitive material, was applied to the entire effective surface at 20 rpm and 450 rpm by spin coating, and pre-baked at 120 degrees for 60 seconds. Then, after exposure of 300 mJ accumulated, development processing for 75 sec, and water washing for 90 sec, 230 ° C. post-baking was performed to form partition walls 51 having the arrangement shown in FIG. The height of the obtained partition wall is 0.5 μm, and the vertical partition wall width is 10 μm. The horizontal partition wall width was 10 μm. In each partition wall, the overlapping portion with the first electrode 2 is 5 μm, covers the edge of the first electrode 2, and surrounds the four sides of the first electrode 2. Further, 50 ml of NPR9700T (manufactured by Nagase ChemteX) was applied to the entire effective surface by spin coating for 15 sec and 450 rpm, and prebaked at 90 ° C. for 60 sec. Then, after the exposure of 200 mJ integrated, the development process for 60 sec and the water washing for 90 sec, post baking was performed at 200 ° C. to form the second partition wall 52. At this time, the height of the second partition wall 52 is 1.0 μm, and the vertical partition wall width is 10 μm. Moreover, the horizontal partition wall width was 3.0 μm. As a result, the ink reservoir 44 was provided with a width of 5.0 μm.

  Next, a 0.1 μm-thick poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid mixture (hereinafter referred to as PEDOT / PSS) is dispersed in water as the hole transport layer 3 on the first electrode 2. Then, a film was formed by a spin coating method. Thereafter, the hole transport ink in unnecessary portions around the effective pixels was removed by wiping with methanol.

  Next, polyphenylene vinylene derivatives, which are organic light emitting materials having red, green, and blue emission colors, are performed for each color by a relief printing method using a water-developable photosensitive resin relief plate, and the organic light emitting layers 41, 42, 43 was formed. At this time, the film thickness of the obtained organic light emitting layers 41, 42, and 43 using an anilox roll of 150 lines / inch was 80 nm.

  Next, as the second electrode 6, Ba was deposited with a thickness of 5 nm by vacuum deposition, and Al was deposited thereon with a thickness of 20 nm. After that, an ITO film is formed using a sputtering method, and sealing is performed by sticking a glass plate with a thermosetting adhesive under nitrogen with a dew point of −80 degrees and an oxygen concentration of 1 ppm without exposure to the atmosphere. An EL element was produced.

<Comparative Example 1>
The second partition wall 52 is not provided, but the partition wall pattern has a height of 0.5 μm, a vertical partition wall width of 10 μm, a horizontal partition wall width of 10 μm, and a partition wall 51 that overlaps with the first electrode 2 is formed by 5 μm. Produced an organic EL device in the same manner as in Example 1.

<Comparative example 2>
The pixel partition pattern has a height of 0.5 μm, a vertical partition wall width of 10 μm, a horizontal partition wall width of 10 μm, an overlapping portion with the first electrode 2 of 5 μm, and a grid pattern of one column between the first electrodes 2. A partition wall 51 having the following structure was formed. Further, the second partition 52 was formed by the same method and conditions as the partition 51. At this time, the height of the second partition wall 52 is 0.5 μm, and the vertical partition wall width is 10 μm. Moreover, the horizontal partition wall width was 3.0 μm. As a result, the ink reservoir 44 was provided with a width of 5.0 μm. Subsequent steps were performed in the same manner as in Example 1 to produce an organic EL device.

<Comparative Example 3>
The pixel partition pattern has a height of 0.5 μm, a vertical partition wall width of 10 μm, a horizontal partition wall width of 10 μm, an overlapping portion with the first electrode 2 of 5 μm, and a grid pattern of one column between the first electrodes 2. A partition wall 51 having the following structure was formed. Further, the second partition 52 was formed by the same method and conditions as the partition 51. At this time, the height of the second partition 52 is 2.5 μm, and the vertical partition width is 10 μm. Moreover, the horizontal partition wall width was 3.0 μm. As a result, the ink reservoir 44 was provided with a width of 5.0 μm. Subsequent steps were performed in the same manner as in Example 1 to produce an organic EL device.

<Comparative example 4>
The partition wall 51 pattern has a height of 1.5 μm, a vertical partition wall width of 10 μm, a horizontal partition wall width of 10 μm, an overlapping portion with the first electrode 2 of 5 μm, and a grid pattern in one row between the first electrodes 2. A partition wall 51 having the following structure was formed. Furthermore, the 2nd partition 52 connected to the vertical direction by the method similar to Example 1 was formed. At this time, the height of the second partition wall 52 is 1.0 μm, and the vertical partition wall width is 10 μm. Moreover, the horizontal partition wall width was 3.0 μm. Subsequent steps were performed in the same manner as in Example 1 to produce an organic EL device.

<Evaluation>
The display confirmation of the panel was performed with respect to the organic EL elements obtained in Example 1 and Comparative Examples 1 to 4, and the light emission state was evaluated.

<Comparison result>
The product of the present invention obtained in Example 1 had no abnormalities such as light emission unevenness and color mixture (color unevenness), and good results were obtained. On the other hand, in the comparative example product obtained in Comparative Example 1, there was no abnormality such as a deviation of the light emission area in the pixel, but a color unevenness abnormality called color mixing occurred. Further, in Comparative Example 2, a mixed color (color unevenness) abnormality occurred. Further, in Comparative Example 3, disconnection of the second electrode (deposition failure) and ink transfer failure due to the central partition being too high occurred, and pixel omission was confirmed. Further, in Comparative Example 4, the presence of the central partition wall in the non-opening portion caused the poor deposition of the second electrode, and it was confirmed that the pixel was missing due to the disconnection. As described above, none of the comparative examples was able to obtain a high-quality light emission state at a practical level.

  According to the present invention, the central partition between the first electrodes prevents color mixing and improves the flatness of the organic light emitting layer surrounded by the lower partition on the edge of the first electrode. An organic EL element having high optical characteristics free from uneven light emission and color mixing and free from uneven light emission between pixels can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... 1st electrode, 3 ... Hole transport layer, 41 ... Red organic light emitting layer, 42 ... Green organic light emitting layer, 43 ... Blue organic light emitting layer, 44 ... Ink reservoir, 51 ... Partition, 52 ... Second partition, 6 ... Second electrode, 7 ... Sealing resin, 8 ... Sealing substrate, 9 ... Organic EL element, 10 ... Mask 11, photosensitive material 12, incident light direction 13 ink tank 14 ink chamber 15 anilox roll 16 resin relief plate 17 plate cylinder 18 ... Printed substrate, 19 ... Stage

Claims (4)

  A pixel is formed by sequentially laminating a first electrode (pixel electrode) and an organic light emitter layer on a substrate, and a second electrode is formed on the organic light emitter layer side so as to face the first electrode. An organic electroluminescence element provided with a second partition in the center between pixels partitioned by the partition.   The partition wall has a reverse taper shape with a height of 1.0 μm or less, the height of the second partition wall is 1.0 to 2.0 μm, and is discontinuous with the adjacent second partition wall. The organic electroluminescent element according to claim 1.   3. The method of manufacturing an organic electroluminescent element according to claim 1, wherein at least one layer of the organic light emitting layer composition constituting the organic light emitting layer is converted into an ink by being dissolved or dispersed in a solvent, and the ink is used. And forming an organic light-emitting layer by a wet film formation method.   The method for producing an organic electroluminescent element according to claim 3, wherein the wet film-forming method is a relief printing method.