JP2012079486A - Organic el element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element with fewer defects and less deterioration by suppressing damage on an organic light-emitting medium layer owing to less bleed out and out gas from a barrier rib with the minimum number of steps, and a manufacturing method therefor.SOLUTION: An organic EL element comprises: a substrate; a first electrode layer formed on the substrate; a barrier rib whose surface at least includes an organic material and which partitions the first electrode layer; an organic light-emitting medium layer including at least a light-emitting layer formed on the first electrode layer; and a second electrode layer formed on the organic light-emitting medium layer. The number of double bonds of carbon on the surface of the barrier rib is larger than that of carbon inside the barrier rib.

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. . Examples of wet film forming methods for forming a thin film include spin coating, bar coating, protruding coating, and dip coating. In addition, it is difficult to separate the three colors of RGB by these wet coating methods, and it is considered that thin film formation by a printing method, which is good at coating and patterning, is most effective. Among various printing methods, a method using inkjet printing, a method using offset printing, a method using letterpress printing, and the like have been proposed.

In general, when patterning is performed by a wet film forming method such as a printing method, a partition pattern is provided as a convex partition member that separates the pixels from each other in order to prevent the coating liquid of the light emitting material from being mixed. The barrier rib pattern is formed by applying a photoresist to the substrate and using a normal photolithography process including exposure and development.

In general, a small amount of a surfactant is contained in a photoresist in order to improve coatability and film formability and prevent unevenness. These surfactants are generally hydrophobic, and in particular, the surface of the surfactant called bleed-out increases by heat treatment.

In addition, a panel including barrier ribs made of an organic material deteriorates the light emitting molecules of the organic light emitting layer by the outgas containing residual solvent from the barrier ribs, thereby reducing the occurrence of non-light emitting spots, electricity, efficiency and lifetime. cause.

Therefore, a configuration has been proposed in which an insulating material made of an inorganic material is formed on the resin partition wall to suppress them. (Patent Document 1)

However, when the insulating material is formed on the partition walls, if the first electrode layer is already formed, the insulating material is formed on the first electrode layer, so it is necessary to remove them after forming the insulating material. There is a problem that the manufacturing process increases.

JP 2008-130410 A

The present invention has been made to solve the above-described problems, and the problem is that an organic EL element in which an organic light emitting medium layer is formed in a pixel partitioned by a partition and a method for manufacturing the same. Provided are an organic EL device and a method for manufacturing the organic EL device in which there are few bleed-outs and outgases from barrier ribs in a minimum number of steps, and damage to an organic light-emitting medium layer is suppressed.

According to the study of the present inventor, it is possible to isolate a partition without an opening by applying a photosensitive resin composition to be a partition on a substrate, pattern exposure and development, and then forming an ion implantation layer. For this reason, the bleed-out and outgas from the partition walls are small, and the damage to the organic light emitting layer can be suppressed.

This invention is made | formed based on such knowledge, As an invention which concerns on Claim 1, at least the surface which divides a board | substrate, the 1st electrode layer formed on the said board | substrate, and a 1st electrode layer is An organic EL device comprising a partition made of an organic material, an organic light emitting medium layer including at least a light emitting layer formed on the first electrode layer, and a second electrode layer formed on the organic light emitting medium layer. There,
The organic EL device is characterized in that the number of carbon double bonds on the partition wall surface is larger than the number of carbon double bonds inside the partition wall.

In the invention according to claim 2, the ratio of the carbon double bond (Bc = c) to the carbon single bond (Bc-c) on the partition wall surface, Bc = c / Bc-c is 0.1 or more. The organic EL device according to claim 1, wherein the organic EL device is 0.3 or less.

The invention according to claim 3 is the organic EL element according to claim 1, wherein the partition wall has a forward tapered shape.

According to a fourth aspect of the present invention, there is provided a method for manufacturing an organic EL element according to any one of the first to third aspects, wherein a step of forming a forward tapered partition made of a photosensitive resin, and a partition surface The method of manufacturing an organic EL device, comprising: a step of treating a partition wall surface by an ion implantation method; and a step of forming an organic light emitting medium layer by a wet film formation method.

The invention according to claim 5 is the method of manufacturing an organic EL element according to claim 1, wherein the ion implantation method is a method of implanting rare gas ions.

The invention according to claim 6 is the method for producing an organic EL element according to claim 1 or 2, wherein the wet film forming method is a printing method.

In a method for manufacturing an organic EL element including a step of forming at least one organic light emitting medium layer in pixels separated by partition walls made of an organic substance, outgas and bleed-out from the portion are caused by the presence of an opening. An organic EL device having fewer defects and no defects was obtained.

It is a schematic cross section of the structure of the organic EL element in the organic EL display panel of the present invention. It is a schematic sectional drawing of an example of the board | substrate of the active matrix system in this invention. It is a schematic sectional drawing of the relief printing apparatus in this invention.

Hereinafter, the organic EL element and the manufacturing method thereof according to the present invention will be described with reference to the drawings.

The organic EL element of the present invention has an organic light emitting medium layer on the first electrode 2 and in a region (light emitting region L, pixel portion) partitioned by the partition walls 7. 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. Examples of the light emission auxiliary layer include a hole transport layer, a hole injection layer, an electron transport layer, and an electron injection 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 a red (R) organic light-emitting layer 41, a green (G) organic light-emitting layer 42, and a blue (B) organic light-emitting layer 43 are provided on the hole transport layer 3. Is provided.

Next, an embodiment of an organic EL device according to the present invention and a manufacturing method thereof 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 extracts 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. FIG. 2 is an explanatory cross-sectional view of an example of the active matrix substrate of the present invention. In the case of the organic EL element substrate of the present invention, the planarization layer 117 is formed on the TFT 120, and the lower electrode (first electrode 12) of the organic EL element is provided on the planarization layer 117. In addition, the TFT and the lower electrode are preferably electrically connected through a contact hole 118 provided in the planarization layer 117. By comprising in this way, the outstanding electrical insulation can be obtained between TFT and an organic EL element.

The TFT 120 and the organic EL element formed above the TFT 120 are supported by a support 111. The support is preferably excellent in mechanical strength and dimensional stability. Specifically, the materials described above as the substrate can be used.

As the thin film transistor 120 provided over the support, a known thin film transistor can be used. 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, a bottom gate type, and a coplanar type.

The active layer 112 is not particularly limited, and examples thereof include amorphous semiconductor materials such as amorphous silicon, polycrystalline silicon, microcrystalline silicon, cadmium selenide, thiophene oligomers, poly (p-ferylene vinylene), and the like. The organic semiconductor material can be used. These active layers are formed by, for example, laminating amorphous silicon by plasma CVD, ion doping, forming amorphous silicon by LPCVD using SiH ₄ gas, and crystallizing amorphous silicon by solid phase growth. After obtaining silicon, ion doping is performed by ion implantation, LPCVD using Si ₂ H ₆ gas, and amorphous silicon is formed by PECVD using SiH ₄ gas, and laser such as excimer laser is used. After annealing and crystallizing amorphous silicon to obtain polysilicon, polysilicon is laminated by ion doping (low temperature process), low pressure CVD or LPCVD, and thermally oxidized at 1000 ° C. or higher. Gate break Film is formed, an n ⁺ polysilicon gate electrode 114 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 113, a film normally used as a gate insulating film can be used. For example, SiO ₂ formed by PECVD, LPCVD, etc., SiO obtained by thermally oxidizing a polysilicon film ₂ etc. can be used.

As the gate electrode 114, those normally used as the gate electrode can be used. For example, metals such as aluminum and copper, refractory metals such as titanium, tantalum and tungsten, polysilicon, silicide of refractory metals And polycide.

The thin film transistor 120 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 display device 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 116 of the transistor and the pixel electrode (first electrode 2) of the organic EL element are electrically connected. Has been. Further, it is generally necessary to use a metal that reflects light as a pixel electrode for taking a top emission structure.

The thin film transistor 120, the drain electrode 116, and the pixel electrode (first electrode 2) of the organic EL element are connected through a connection wiring formed in a contact hole 118 that penetrates the planarization film 117.

Regarding the material of the planarizing film 117, inorganic materials such as SiO ₂ , spin-on glass, SiN (Si ₃ N ₄ ), TaO (Ta ₂ O ₅ ), organic materials such as polyimide resin, acrylic resin, photoresist material, and black matrix material are used. Materials and the like can be used. Spin coating, CVD, vapor deposition, etc. can be selected according to these materials. If necessary, a contact hole 118 is formed by dry etching, wet etching, or the like at a position corresponding to the lower layer thin film transistor 120 by photolithography using a photosensitive resin as the planarizing layer, or once the planarizing layer is formed on the entire surface. Form. The contact hole is then filled with a conductive material to establish conduction with the pixel electrode formed in the upper layer of the planarization layer. The thickness of the planarizing layer is not limited as long as it can cover the lower TFT, capacitor, wiring, etc., and the thickness may be several μm, for example, about 3 μm.

In addition, as a driving method of the organic EL element, there are a passive matrix system and an active matrix system using the substrate on which the TFT is formed, but the organic EL element of the present invention is a passive matrix system organic EL element, an active matrix system. It is applicable to both of the organic EL elements. The passive matrix method is a method in which stripe-shaped electrodes are opposed to each other so as to be orthogonal to each other, and light is emitted at the intersection, whereas the active matrix method uses a so-called thin film transistor (TFT) substrate in which a transistor is formed for each pixel. Thus, the light is emitted independently for each pixel.

A first electrode is provided on the substrate. When the first electrode is used as an anode, the material is a metal composite such as ITO (indium tin composite oxide), IZO (indium zinc composite oxide), tin oxide, zinc oxide, indium oxide, zinc aluminum composite oxide. A single layer or a stacked layer of metal materials such as oxide, gold, platinum, and chromium can be used. As a method for forming the first electrode, 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.

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 a glass substrate by a sputtering method, and is patterned by a photolithography method to form a first electrode.

Next, the partition wall 7 is formed. On the surface of the partition wall 7 of the present invention, an ion implantation layer 8 having a larger number of carbon-carbon double bonds than the inside of the partition wall is formed. The film thickness of the ion-implanted layer is not particularly limited, but is preferably 10 nm or more so that sufficient bleed-out and outgas suppression effects can be obtained, and is preferably 100 nm or less from the viewpoint of ease of production.
Moreover, it is desirable that the partition wall end portion of the present invention has a forward taper shape for ease of ion implantation. The forward tapered shape is a structure in which the height gradually increases from the partition wall end to the partition wall center.
The height of the partition wall is 0.1 μm to 10 μm, more preferably 0.5 μm to 2.0 μm. If it is too high, the formation and sealing of the second electrode may be hindered. If it is too low, the end of the first electrode may not be covered, or the light emitting medium layer formed in the barrier ribs may spread to adjacent barrier ribs and mix colors. .

As a material for the partition wall, it is necessary to have at least insulation, 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. In the present invention, an organic material is used for at least the partition wall surface in order to form a double bond ion-implanted layer between carbons on the partition wall surface, but the lower part of the partition wall and the inside of the partition wall may be made of an inorganic material.

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.

A forward-tapered partition is formed by a photolithography method using a photosensitive material. For example, when a negative photosensitive resin is applied, exposed and developed, and then post-baked to obtain partition walls, the type, concentration, temperature, or development time of the developer, which are the development conditions, can be controlled. A desired shape can be formed.

Here, before the formation of the organic light-emitting medium layer, an ion implantation layer is formed on the surface of the manufactured partition wall 7 using an ion implantation method. The ion implantation method is not particularly limited as long as ions are implanted, but the plasma ion implantation method is preferable because ions can be implanted in a large area. The element of the implanted ions needs to be a rare gas element (Group 18 element in the periodic table). When ions of other elements are used, there is a risk that a defect such as a change in resistance value due to bonding with the electrode material when ions are implanted into the electrode. For example, when an ion implantation layer is formed using Ar ions by a plasma ion implantation method, a partition wall substrate is placed on a substrate holder in a vacuum chamber, and Ar plasma is generated in the vacuum chamber. In this state, Ar ions can be implanted into the entire substrate by applying a high voltage to the substrate holder.

The voltage is not particularly limited as long as a desired injection layer thickness can be obtained, but is preferably 5.0 kV or more and 20 kV or less. At this time, Ar ions are also implanted into the electrode, but the electrode is only slightly etched, and Ar ions are not bonded to the electrode material, so that the electrical resistance is not affected. The partition wall of the present invention should have at least the number of carbon-carbon double bonds on the surface larger than the number of carbon-carbon double bonds inside the partition wall. In order to increase the number of carbon-carbon double bonds more than the number of carbon-carbon double bonds inside the partition walls, for example, by implanting Ar ions, which are rare gas elements, into the partition surface, the bonds between the partition wall materials are cut by Ar ions. Then, the carbon double bond increases by recombination. By increasing the number of carbon double bonds, the density of the partition wall surface is increased, and bleeding out and outgas from the interior of the partition wall can be prevented from oozing out into each layer inside the organic EL element such as an organic light emitting medium layer. Here, the ratio of carbon double bond (Bc = c) to single bond (Bc-c), Bc = c / Bc-c on the partition wall surface is preferably 0.1 or more and 0.3 or less. If it is less than 0.1, bleed-out and outgas from the inside of the partition wall may not be suppressed. If it is more than 0.3, the proportion of double bonds is too large, and a large number of double bonds are conjugated due to conjugation. There is a risk that the electrical resistance of the surface is lowered and the insulation required for the partition cannot be maintained.

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, or a light emitting auxiliary layer for assisting light emission, such as an organic light emitting layer and a hole transport layer, a hole injection layer, an electron transport layer, or an electron injection layer. It is good also as a laminated structure. The hole transport layer, hole injection layer, electron transport layer, and electron injection layer are appropriately selected as necessary.

The organic light emitting layer is a layer that emits light when an electric current is passed. Organic light-emitting materials formed by the organic light-emitting layer include 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolato) 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] aluminum complex, Lis (8-quinolinolato) scandium complex, bis [8- (paratosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, poly-2,5-diheptyloxy-paraphenylene 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, 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- Alto-1,4-phenylylene] 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)] Polymer light-emitting materials such as (CN-PPV), poly (9,9-dioctylfluorene) (PDAF), and polyspiro may be used. Examples thereof include polymer precursors such as a PPV precursor and a PPP precursor. Other existing light emitting materials can also be used.

Examples of the organic material for the hole transport layer include 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 , N′-diphenyl-1,1′-biphenyl-4,4′-diamine and other aromatic amine-based low-molecular hole injection / transport materials, polyaniline, polythiophene, polyvinylcarbazole, poly (3,4-ethylenedioxy) Polymeric hole transport materials such as a mixture of thiophene and polystyrene sulfonic acid, polythiophene oligomer materials, and other existing hole transport materials It can be selected from among.

In inorganic materials, alkaline metal elements such as Li, Na, K, Rb, Ce, and Fr, alkaline earth metal elements such as Mg, Ca, Sr, and Ba, La, Ce, Sm, Eu, Gd, Yb, etc. Lanthanoid elements, Au, Cu, Al, Fe, Ni, Ru, Sn, Pb, Cr, Ir, Nb, Pt, W, Mo, Ta, Pa, Co, and other metal elements, Si, Ge, or these There are compounds such as oxides, carbides, nitrides and borides.

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.

Examples of the solvent for dissolving or dispersing the hole transport material and the 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 and the like 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 of the present invention is formed by a wet film forming method that requires a partition wall. 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 patterning organic light emitting layers of three colors of RGB, it can be selectively formed on the pixel portion by a printing method, and an organic EL element capable of color display can be manufactured. The film thickness of the organic light emitting medium layer is 1000 nm or less, preferably 50 nm to 150 nm, even when formed by a single layer or stacked layers.

In particular, the organic light emitting layer can be suitably formed by a relief printing method. For example, in ink jet printing, ink is ejected from a nozzle, which is an ink supply body, toward the substrate, that is, there is a distance between the nozzle and the substrate, and the ink ejected on the substrate is scattered by rebounding on the substrate. Resulting in. On the other hand, in the relief printing method, since the ink is transferred so that the plate as the ink supply and the printing substrate are in contact with each other, the predetermined ink can be arranged at a predetermined position without being scattered.

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 for forming the organic light emitting layer can be any relief printing apparatus that prints on a flat plate, but the following printing apparatus is desirable. FIG. 7 shows a schematic diagram of the relief printing apparatus of the present invention. This manufacturing apparatus has a plate cylinder 18 to which an ink tank 10, an ink chamber 12, an anilox roll 14, and a resin relief plate 16 are attached. The ink tank 10 contains organic light-emitting ink diluted with a solvent, and the organic light-emitting ink is fed into the ink chamber 12 from the ink tank 10. The anilox roll 14 rotates in contact with the ink supply section of the ink chamber 12 and the plate cylinder 18.

As the anilox roll 14 rotates, the organic light emitting ink 14a supplied from the ink chamber 12 is uniformly held on the surface of the anilox roll 14 and then has a uniform film thickness on the convex portions of the resin relief plate 16 attached to the plate cylinder. It will transfer at. Furthermore, the substrate to be printed is fixed on a slidable substrate fixing base, moved to the printing start position while adjusting the position by the position adjustment mechanism of the plate pattern and the substrate pattern, and in accordance with the rotation of the plate cylinder. The convex portion of the resin relief plate 16 further moves while contacting the substrate, and the ink is transferred by patterning to a predetermined position of the substrate 24 to be printed on the stage 20.

Next, a second electrode is formed. When the second electrode is a cathode, a material having high electron injection efficiency is used as the material. 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, a dry film formation 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. Moreover, when it is necessary to make a 2nd electrode into a pattern, it can pattern by a mask etc. The thickness of the second electrode is preferably 10 nm to 1000 nm. In the present invention, the first electrode can be a cathode and the second electrode can be an anode.

An organic EL element can emit light by sandwiching a light emitting material between electrodes and passing an electric current. However, some of the organic light emitting material, the organic light emitting medium layer forming material, Since it is easily deteriorated by oxygen, a sealing body is usually provided for shielding from the outside.

For example, a sealing body is provided with a resin layer on a sealing material on a substrate on which a first electrode, an organic light emitting medium layer including an organic light emitting layer, and a second electrode are formed. This is done by bonding the substrates together.

The sealing material needs to be a base material having low moisture and oxygen permeability. Examples of the material include ceramics such as alumina, silicon nitride, and boron nitride, glass such as alkali-free glass and alkali glass, metal foil such as quartz, aluminum, and stainless steel, and moisture-resistant film. Examples of moisture-resistant films include films formed by CVD of SiOx on both sides of plastic substrates, films with low permeability and water-absorbing films, or polymer films coated with a water-absorbing agent. The water vapor transmission rate is preferably 10 −6 g / m 2 / day or less.

Examples of the resin layer include a photo-adhesive adhesive resin made of an epoxy resin, an acrylic resin, a silicone resin, a thermosetting adhesive resin, a two-component curable adhesive resin, an ethylene ethyl acrylate (EEA) polymer, and the like. Examples thereof include acrylic resins, vinyl resins such as ethylene vinyl acetate (EVA), thermoplastic resins such as polyamide and synthetic rubber, and thermoplastic adhesive resins such as acid-modified products of polyethylene and polypropylene. Examples of methods for forming a resin layer on a sealing material include solvent solution method, extrusion lamination method, melting / hot melt method, calendar method, nozzle coating method, screen printing method, vacuum laminating method, hot roll laminating method, etc. Can be mentioned. A material having a hygroscopic property or an oxygen absorbing property may be contained as necessary. Although the thickness of the resin layer formed on a sealing material is arbitrarily determined by the magnitude | size and shape of the organic EL element to seal, about 5-500 micrometers is desirable.

The first electrode, the organic light emitting medium layer including the organic light emitting layer, and the substrate on which the second electrode is formed and the sealing body are bonded together in a sealing chamber. When the sealing body has a two-layer structure of a sealing material and a resin layer, and a thermoplastic resin is used for the resin layer, it is preferable to perform only pressure bonding with a heated roll. When a thermosetting adhesive resin is used, it is preferable to perform heat curing at a curing temperature after pressure bonding with a heated roll. In the case where a photocurable adhesive resin is used, curing can be performed by further irradiating light after pressure bonding with a roll. Note that although the resin layer is formed over the sealing material here, the resin layer can be formed over the substrate and bonded to the sealing material.

Before or instead of sealing with a sealing body, for example, as a passivation film, it is also possible to form a sealing body with an inorganic thin film, such as a silicon nitride film having a thickness of 150 nm using a CVD method. It is also possible to combine these. In addition, using a glass cap or metal cap having a recess, the first electrode, the organic light emitting medium layer, and the second electrode are exposed to the recess, and the cap and the substrate are adhered to the periphery thereof to seal the seal. It is also possible to do it.

Examples of the present invention will be specifically described below. In this example (comparative example), a production example of a passive matrix type organic EL element will be described.

Example 1
An ITO (indium-tin oxide) thin film was formed on a 300 mm square glass substrate by sputtering, and the ITO film was patterned by photolithography and etching with an acid solution to form a first electrode. As shown in FIG. 8, the ITO pattern, that is, the pattern of the first electrode has a pixel width of 30 μm, a width of 10 μm, and a space between pixels of 5 μm.

Next, TELR series (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a positive photosensitive material, was applied to the entire effective surface by a spin coating method so as to have a film thickness of 1.2 μm. Then, exposure and development processes were performed, and a partition was formed between the first electrodes so as to cover the first electrode end. The developer used at this time is NMD-W (manufactured by Tokyo Ohka Kogyo Co., Ltd.). The width of the obtained partition wall is 7 μm, and the height of the partition wall is 1.1 μm. Further, as a result of cross-sectional observation, it was confirmed that the partition wall end had a trapezoidal shape as shown in FIG. 2, and the partition wall end had a forward tapered shape.

Next, an ion implantation layer was formed using a plasma ion implantation method as follows. The substrate was placed on the substrate holder in the vacuum chamber, and while generating Ar plasma, a voltage of 10 kV was applied to the substrate holder, and Ar ions were implanted for 5 minutes. Under the present circumstances, the injection | pouring film thickness was 20 nm and the composition analysis was performed for the polyimide partition wall surface using XPS (JPS9010 by JEOL), Bc = c / Bc-c was 0.2.

Next, letterpress printing using a water-developable photosensitive resin letterpress using an organic light emitting ink with a concentration of 1 wt% in which a polyfluorene derivative, which is an organic light emitting material having red, green and blue emission colors, is dissolved in toluene. The method was carried out for each color to form an organic light emitting layer. At this time, an anilox roll of 150 lines / inch was used, and after formation, drying was performed by vacuum heating. The film thickness of the obtained organic light emitting layer was 80 nm.

A second electrode made of Ca and Al was deposited on the entire surface of the substrate by electron beam evaporation. Finally, in order to protect from external oxygen and moisture, it was hermetically sealed using a glass cap and an adhesive to produce an organic EL element. At the periphery of the obtained organic EL element, there are anode-side and cathode-side extraction electrodes connected to the respective pixel electrodes. By connecting these to a power source, it is possible to confirm the lighting display of the panel.

In the periphery of the display portion of the organic EL display panel obtained in the present embodiment, there are an extraction electrode on the anode side connected to each pixel electrode and an extraction electrode on the cathode side, and by connecting these to a power source, The lighting display of the organic EL display panel which is the obtained display device was confirmed, and the light emission state and the light emission characteristics were checked.

As a result, the difference in luminance between the vicinity of the partition on the light emitting surface and the midpoint between the partitions was a film thickness within 5%. The addition 160 cd / ^{m 2,} the luminance is 6V, luminance half-life at an initial luminance 400 cd / ^{m 2} is 1600 hours, high luminous efficiency, high emission luminance, the resulting display characteristics of long life. Furthermore, as a result of an accelerated test in a constant temperature and high humidity environment with a temperature of 50 ° C. and a humidity of 90%, dark spots were generated on the light emitting surface in 5000 hours.

(Example 2)
It was fabricated in the same manner as in Example 1 except that the ion implantation voltage was 20 kV, the treatment time was 5 minutes, and the layer thickness was 40 nm. Bc = c / Bc-c on the polyimide partition wall surface was 0.3.

As a result, the difference in luminance between the vicinity of the partition on the light emitting surface and the midpoint between the partitions was a film thickness within 5%. With a luminance of 6 V, 160 cd / m ² , and an initial luminance of 400 cd / m ^{2 with} a luminance half-life of 2000 hours, it is possible to obtain good display characteristics with a uniform light emitting surface with high luminous efficiency, high luminous luminance and long life. It was. In addition, as a result of an accelerated test in a constant temperature and high humidity environment with a temperature of 50 ° C. and a humidity of 90%, dark spots were generated on the light emitting surface in 8000 hours.

(Example 3)
It was produced in the same manner except that the treatment time of Example 1 was 3 minutes and the layer thickness was 25 nm. Bc = c / Bc-c on the polyimide partition wall surface was 0.1.

As a result, the difference in luminance between the vicinity of the partition on the light emitting surface and the midpoint between the partitions was a film thickness within 5%. With a luminance of 6 V, 160 cd / m ² , and an initial luminance of 400 cd / m ^{2 with} a luminance half-life of 1400 hours, it is possible to obtain good display characteristics with a uniform light emitting surface with high luminous efficiency, high luminous luminance and long life. It was. Further, as a result of an accelerated test in a constant temperature and high humidity environment with a temperature of 50 ° C. and a humidity of 90%, dark spots were generated on the light emitting surface in 3500 hours.

<Comparative Example 1>
It was produced in the same manner as in Example 1 except that no ion implantation layer was provided.

As a result, the luminance difference between the vicinity of the partition on the light emitting surface and the midpoint between the partitions was 20% and non-uniform. A display characteristic of 100 cd / m ² at a luminance of 6 V and a luminance half time of 1200 hours at an initial luminance of 400 cd / m ² was obtained. Further, as a result of an accelerated test in a constant temperature and high humidity environment with a temperature of 50 ° C. and a humidity of 90%, dark spots were generated in 1000 hours.

<Comparative example 2>
An organic EL device was produced in the same manner as in Example 1 except that the ion implantation treatment time was 20 minutes. Bc = c / Bc-c on the partition wall surface of the produced organic EL element was 0.4, and current flowed through the ion implantation layer, so that the luminance was reduced to 50 cd / m ² at 6V.

As described above, by providing an ion implantation layer on the partition wall surface and setting Bc = c / Bc-c of the ion implantation layer to be 0.1 or more and 0.3 or less, generation of dark spots can be suppressed, and high light emission efficiency and high light emission can be achieved. It was found that good display characteristics with a uniform light emitting surface with brightness and long life can be obtained.

1: Substrate 2: First electrode 3: Hole transport layer 41: Red (R) organic light emitting layer 42: Green (G) organic light emitting layer 43: Blue (B) organic light emitting layer 5: Second electrode 6: Passivation layer 7: partition wall 8: ion implantation layer 111: support 112: active layer 113: gate insulating film 114: gate electrode 115: interlayer insulating film 116: drain electrode 117: planarization layer 118: contact hole 119: data line 120: thin film transistor 10: ink tank 12: ink chamber 14: anilox roll 14a: ink 16: letterpress 18: plate cylinder 20: stage 24: substrate to be printed

Claims (6)

Organic light emission including a substrate, a first electrode layer formed on the substrate, a partition made of an organic material at least on a surface partitioning the first electrode layer, and at least a light emitting layer formed on the first electrode layer An organic EL element comprising a medium layer and a second electrode layer formed on the organic light emitting medium layer,
The organic EL element, wherein the number of carbon double bonds on the partition wall surface is larger than the number of carbon double bonds inside the partition wall. Ratio of carbon double bond (Bc = c) and carbon single bond (Bc-c) on the partition wall surface, Bc = c / Bc-c is 0.1 or more and 0.3 or less. The organic EL element according to claim 1. The organic EL device according to claim 1, wherein the partition wall has a forward tapered shape. It is a manufacturing method of the organic EL element in any one of Claims 1 thru | or 3, Comprising:
Forming a forward-tapered partition made of a photosensitive resin;
A step of treating the partition wall surface with an ion implantation method;
Forming an organic light emitting medium layer by a wet film formation method;
The manufacturing method of the organic EL element characterized by including. 2. The method of manufacturing an organic EL element according to claim 1, wherein the ion implantation method is a method of implanting rare gas ions. The method for manufacturing an organic EL element according to claim 1, wherein the wet film forming method is a printing method.

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