JP2013118095A - Manufacturing method for organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for an organic EL element capable of forming an organic layer having a uniform film thickness in a light-emitting region using a discharging method.SOLUTION: A manufacturing method for an organic EL element comprises the steps of: preparing an organic EL base material having a base material and a first electrode layer formed on the base material and defining a light-emitting region of the organic EL base material; and forming at least one organic layer by a discharging method among organic layers constituting an organic EL layer including a light-emitting layer in the light-emitting region. The organic layer formation step further comprises the steps of: forming a pool by applying a high-boiling-point solvent into the light-emitting region; forming a layer for organic layer formation by diffusing the organic layer material into the pool by applying a coating liquid for organic layers containing an organic layer material and a solvent into the light-emitting region in which the pool is formed by the discharging method; and forming the organic layer by drying the layer for organic layer formation.

Description

  The present invention relates to a method for manufacturing an organic electroluminescent element, in which an organic layer constituting an organic electroluminescent layer can be formed in a light emitting region with a uniform film thickness.

  An organic electroluminescence element that sandwiches an organic layer between a pair of electrodes and emits light by applying a voltage between the two electrodes (hereinafter, electroluminescence may be abbreviated as EL) has high visibility due to self-coloring. Unlike a liquid crystal device, it is an all-solid-state device, so it has advantages such as excellent impact resistance, fast response speed, little influence from temperature changes, and a large viewing angle. The use as a light-emitting element in a device or a lighting device has attracted attention.

As an organic EL element, an element in which a plurality of organic layers such as a hole injection transport layer, a light emitting layer, and an electron injection transport layer are laminated between an anode and a cathode is known.
As a method for forming such an organic layer, a vapor deposition method and a coating method are generally widely used. Of these, the coating method is more advantageous than the vapor deposition method in terms of cost, and it is easy to increase the area. It has the advantage of being. In addition, among various coating methods, the organic layer forming method using a discharge method such as an ink jet method can reduce the amount of organic layer material used, and is lower than when using a printing plate. It has been attracting attention because it has the advantage that the damage can be reduced (see, for example, Patent Documents 1 to 7).

However, the organic layer forming method using the discharge method may cause the following problems.
That is, since the discharge method is to discharge the organic layer coating liquid in the form of dots, the formed organic layer is composed of a set of dots. Therefore, there is a problem that it is difficult to form the organic layer with a uniform film thickness, resulting in uneven film thickness. Note that the film thickness unevenness causes light emission unevenness of the organic EL element.
In addition, in order to suppress the above-described film thickness unevenness, in order to improve the connection between dots of the coating liquid for organic layer, when the leveling time is increased or the ink viscosity is decreased, it is more than the desired light emitting region. There is a problem that the organic layer coating liquid is wet and spreads over a wide area, and an organic layer is formed.
Further, in the above discharge method, since the application is performed by changing the application position of the organic layer coating solution over time, the solvent in the region where the organic layer coating solution is applied first with the lapse of time. With the drying, the amount of the solvent in the organic layer forming layer changes, and as a result, there is a problem that an organic layer having a uniform film thickness cannot be obtained.
These problems are particularly likely to occur as the light emitting region of the organic EL element becomes larger.

JP 2003-31196 A JP 2003-318516 A JP 2004-298844 A JP 2005-285616 A JP 2006-260779 A Japanese Patent Laid-Open No. 2007-075719 JP 2007-076619 A

  The present invention has been made in view of the above circumstances, and it is a main object of the present invention to provide a method for manufacturing an organic EL element capable of forming an organic layer having a uniform film thickness in a light emitting region using a discharge method. And

  In order to solve the above problem, the present invention provides a substrate and an organic EL substrate having a first electrode layer formed on the substrate, and defines a light emitting region of the organic EL substrate. And an organic layer forming step of forming at least one organic layer by an ejection method among organic layers constituting an organic EL layer including a light emitting layer in the light emitting region, and the organic layer forming step includes: A high-boiling-point solvent coating step in which a high-boiling solvent is applied in the light-emitting region to form a pool, and an organic layer coating liquid containing an organic layer material and a solvent is discharged into the light-emitting region in which the pool is formed The organic layer coating liquid coating step for forming the organic layer forming layer by diffusing the organic layer material in the pool and drying the organic layer forming layer to form the organic layer And a drying process. To provide a method of manufacturing an organic EL element.

  According to the present invention, since the organic layer forming step includes a high boiling point solvent coating step and an organic layer coating liquid coating step, the organic layer material can be sufficiently diffused in the pool. Even when the organic layer coating liquid is applied in the form of dots using the discharge method, an organic layer having a uniform film thickness can be formed in the light emitting region. Therefore, it is possible to manufacture an organic EL element in which light emission unevenness due to film thickness unevenness hardly occurs.

  In this invention, it is preferable that the said definition process is a process of forming the partition which defines the said light emission area | region on the said organic EL base material. This is because the high boiling point solvent and the organic layer coating liquid can be suitably prevented from leaking outside the light emitting region in the high boiling point solvent coating process and the organic layer coating liquid coating process. Moreover, it is because the same partition can be repeatedly used when a plurality of organic layers are stacked by repeatedly performing the organic layer forming step.

  According to the present invention, there is an effect that it is possible to provide a method for manufacturing an organic EL element that can form an organic layer having a uniform film thickness in a light emitting region using a discharge method.

It is process drawing which shows an example of the manufacturing method of the organic EL element of this invention. It is a schematic sectional drawing which shows an example of the organic EL element manufactured by the manufacturing method of this invention. It is a schematic sectional drawing of the organic EL base material which has a pool formed in the manufacturing method of the organic EL element of this invention.

Hereinafter, the manufacturing method of the organic EL element of this invention is demonstrated.
The manufacturing method of the organic EL element of the present invention includes a demarcation step of preparing an organic EL substrate having a substrate and a first electrode layer formed on the substrate, and demarcating a light emitting region of the organic EL substrate. An organic layer forming step of forming at least one organic layer of the organic layers constituting the organic EL layer including a light emitting layer in the light emitting region by a discharge method, and the organic layer forming step includes A high-boiling-point solvent coating step in which a high-boiling solvent is applied in the light-emitting region to form a pool, and an organic layer coating solution containing an organic layer material and a solvent is discharged into the light-emitting region in which the pool is formed The organic layer material is diffused in the pool to form an organic layer forming layer, and the organic layer forming layer is dried to form the organic layer. And a drying step, characterized in that It is a manufacturing method that.

Here, the manufacturing method of the organic EL element of this invention is demonstrated using figures. FIG. 1 is a process diagram showing an example of a method for producing an organic EL element of the present invention. In the method for producing an organic EL device of the present invention, first, as illustrated in FIG. 1A, an organic EL substrate 3 having a substrate 1 and a first electrode layer 2 formed on the substrate 1 is prepared. Then, the partition wall 4 for defining the light emitting region is formed on the organic EL substrate 3 (defining step).
Next, at least one organic layer among the organic layers constituting the organic EL layer including the light emitting layer in the light emitting region is formed by an ejection method (organic layer forming step). Specifically, as illustrated in FIG. 1B, a pool 5 is formed by applying a high boiling point solvent in the light emitting region (high boiling point solvent application step). Next, as illustrated in FIGS. 1C and 1D, an organic layer coating solution 6 ″ containing an organic material and a solvent is applied to the light emitting region where the pool 5 is formed by the inkjet nozzle 20. Then, the organic layer material is diffused in the pool 5 to form the organic layer forming layer 6 ′ (organic layer coating liquid coating step) Next, as shown in FIG. The layer 6 ′ is dried to form the organic layer 6 (drying step), wherein an example in which the light emitting layer 61 is formed as the organic layer 6 is shown in FIG.
Although not shown, since the organic EL element has the second electrode layer on the organic EL layer, in the present invention, usually, a second electrode layer forming step of forming the second electrode layer on the organic EL layer. Have

  Next, the organic EL element manufactured by the manufacturing method of this invention is demonstrated. FIG. 2 is a schematic cross-sectional view showing an example of an organic EL element manufactured according to the present invention. As illustrated in FIG. 2, the organic EL element 10 is formed on the organic EL substrate 3 having the substrate 1 and the first electrode layer 2 formed on the substrate 1, and the organic EL substrate 3. It has an organic EL layer having at least a light emitting layer 61 and a second electrode layer 7 formed on the organic EL layer (light emitting layer 61).

  According to the present invention, since the organic layer forming step includes a high boiling point solvent coating step and an organic layer coating liquid coating step, the organic layer material can be sufficiently diffused in the pool. Even when the organic layer coating liquid is applied in the form of dots using the discharge method, an organic layer having a uniform film thickness can be formed in the light emitting region. Therefore, it is possible to manufacture an organic EL element in which light emission unevenness due to film thickness unevenness hardly occurs.

  Hereinafter, each process in the manufacturing method of the organic EL element of this invention is demonstrated.

I. Definition step The definition step in the present invention is a step of preparing an organic EL substrate having a substrate and a first electrode layer formed on the substrate, and defining a light emitting region of the organic EL substrate.

1. Light emitting region The light emitting region in the present invention is a region where an organic EL layer is formed. In addition, when the organic EL element manufactured by this invention is used for a display apparatus, the said light emission area | region contains not only the light emission area | region which comprises each pixel but the area | region in which the light emission area | region in several pixels is provided. It is a concept.

The size of the light emitting region in the present invention is not particularly limited as long as the organic layer can be formed by a discharge method, and can be appropriately selected according to the type of the organic EL element. The size of the light emitting region is preferably 1 mm × 1 mm or more, and particularly preferably in the range of 10 mm × 10 mm to 100 mm × 100 mm, particularly in the range of 30 mm × 30 mm to 60 mm × 60 mm. This is because it is difficult to form the organic layer itself by using the discharge method when the above range is not satisfied. In addition, the upper limit of the size of the light emitting region is not particularly limited, but is, for example, about 150 mm × 150 mm.
In the method for producing an organic EL element of the present invention, the light emitting region is preferably a larger area. Since the larger the light emitting area is, the more it is necessary to apply the organic layer coating liquid in the form of dots by using the discharge method. This is because the operational effects of this manufacturing method can be greatly exhibited.

2. Defining Step The defining step is not particularly limited as long as the organic EL substrate can be defined so that an organic layer can be formed in a desired light emitting region. Specifically, a contact angle between an aspect (first aspect) in which a partition that defines a light emitting region is formed on an organic EL substrate, and a high-boiling solvent and an organic layer coating liquid described later on the organic EL substrate. A mode of forming a pattern forming layer having a lyophilic region exhibiting small wettability and a liquid repellent region exhibiting a wettability greater than the lyophilic region in contact angle with the high boiling point solvent (second mode) ). In the present invention, the first aspect is particularly preferable. This is because it is possible to suitably prevent the high boiling point solvent and the organic layer coating solution from leaking outside the light emitting region in the high boiling point solvent coating step and the organic layer coating solution coating step described later. In addition, when the organic layer forming step in the present invention is performed a plurality of times to form a plurality of organic layers, the partition walls can be used repeatedly.
Hereinafter, each aspect will be described.

(1) 1st aspect The 1st aspect of the said definition process is a process of forming the partition which defines a light emitting area | region on an organic electroluminescent base material.

  The partition wall used in this embodiment is not particularly limited as long as a light emitting region having a desired size can be defined. The partition wall may not be peelable from the organic EL substrate, and may be peelable. May be.

In the case where the partition wall is non-peelable, the partition wall forming material is, for example, a photo-curing type such as photosensitive polyimide resin, acrylic resin, novolac resin, styrene resin, phenol resin, melamine resin, etc. Examples thereof include a resin, a thermosetting resin, and an inorganic material.
In this case, as a method for forming the partition wall, a general method such as a photolithography method or a printing method can be used.

On the other hand, when the partition is detachable, examples of the material for forming the partition include Teflon (registered trademark), silicon rubber, polyimide varnish, and dry film.
As a method for forming the partition wall in this case, a general method such as a lamination method, a photolithography method, or a printing method can be used. Moreover, the method of forming a partition separately using a casting_mold | template etc., and bonding together using the adhesive etc. which can be peeled on an organic electroluminescent base material can be mentioned.

  The height of the partition wall is such that the high boiling point solvent and the organic layer coating liquid applied in the high boiling point solvent coating step and the organic layer coating liquid coating step described below can be held in the light emitting region. The height is not particularly limited. Specifically, the height of the partition wall is preferably in the range of 0.5 μm to 100 μm, more preferably in the range of 0.5 μm to 30 μm, and particularly preferably in the range of 0.5 μm to 10 μm. This is because when the height of the partition wall is less than the above range, it may be difficult to keep the high boiling point solvent and the organic layer coating liquid in the light emitting region. On the other hand, when the height of the partition wall exceeds the above range, it may be difficult to apply the high boiling point solvent and the organic layer coating liquid in the high boiling point solvent coating process and the organic layer coating liquid coating process described later. This is because the partition walls may not be stably formed in the defining step. In addition, when the partition walls cannot be peeled off, it is difficult to form the organic EL element into a thin film, or the layer constituting the organic EL layer or the second electrode layer formed on the organic EL layer This is because there is a possibility of hindering the formation of.

  About the width | variety of the said partition, it is a grade which can hold | maintain the high boiling point solvent apply | coated in the high boiling point solvent application process mentioned later and the coating liquid application process for organic layers in the light emission area | region, and the coating liquid for organic layers. The width is not particularly limited.

  Moreover, the said partition may have liquid repellency with respect to the high boiling point solvent and the organic layer coating liquid which the surface mentions later. The liquid repellency can be imparted, for example, by performing a surface treatment that changes the surface energy (wettability) on the partition wall. In addition, a liquid repellent material such as a fluorine compound may be added to the partition wall material in advance to impart liquid repellency.

(2) 2nd aspect The 2nd aspect of the said definition process is a lyophilic area | region which exhibits the wettability with a small contact angle with the high boiling point solvent and organic layer coating liquid which are mentioned later on an organic EL base material, and said high This is a step of forming a pattern forming layer having a liquid repellent region exhibiting wettability with a contact angle with a boiling point solvent or the like larger than the lyophilic region. The pattern forming layer formed in this embodiment is not particularly limited as long as a pattern due to the difference in wettability is formed, but the wettability change has the property that the wettability changes due to energy irradiation from the action of the photocatalyst. It is preferably formed using a layer. Moreover, as such a wettability change layer, the wettability change layer which does not contain the photocatalyst which can be used as a pattern formation body layer may be sufficient, and the photocatalyst content layer containing a photocatalyst may be sufficient. The details of the wettability changing layer and the photocatalyst-containing layer can be the same as those described in JP-A-2007-000867.

3. Organic EL Base Material The organic EL base material used in this step has a base material and a first electrode layer.

(1) First electrode layer The first electrode layer used in the present invention may be an anode or a cathode, but is usually formed as an anode.

  The first electrode layer may or may not have transparency. The transparency of the first electrode layer is appropriately selected depending on the light extraction surface and the like. For example, when light is extracted from the first electrode layer side, the first electrode layer needs to be transparent or translucent.

  As the first electrode layer (anode), a conductive material having a high work function is preferably used so that holes can be easily injected. Specifically, a metal having a high work function, such as ITO, indium oxide, or gold. , Conductive polymers such as polyaniline, polyacetylene, polyalkylthiophene derivatives, and polysilane derivatives.

  The first electrode layer preferably has a low resistance, and generally a metal material is used, but an organic compound or an inorganic compound may be used.

  The first electrode layer may be formed in a pattern on the substrate, or may be formed on almost the entire surface of the substrate except for the region where the extraction electrode or the like is formed. When the first electrode layer is formed on almost the entire surface of the substrate except for the region where the extraction electrode or the like is formed, the light emitting region can be partitioned into a desired pattern by the partition.

  As a method for forming the first electrode layer, a general electrode forming method can be used, for example, a PVD method such as a vacuum deposition method, a sputtering method, an ion plating method, a CVD method, or the like. Can do. Further, the patterning method of the first electrode layer is not particularly limited as long as it can be accurately formed into a desired pattern, and specific examples thereof include a photolithography method.

(2) Base Material The base material used in the present invention is not particularly limited as long as it supports the above-described partition walls, the first electrode layer, and the like and has a predetermined strength. In the present invention, when the first electrode layer has a predetermined strength, the first electrode layer may also serve as the base material, but usually the first electrode layer is formed on the base material having the predetermined strength. An electrode layer is formed.

  The base material is not particularly limited as long as the above partition walls, the first electrode layer, and the like can be formed. For example, the base material is appropriately determined depending on whether light transmission is necessary depending on the light extraction surface. . In general, since the substrate side is preferably the light extraction surface, the substrate is preferably formed of a transparent material.

  As a material for forming such a base material, for example, soda lime glass, alkali glass, lead alkali glass, borosilicate glass, aluminosilicate glass, silica glass, or a resin base material that can be formed into a film shape. Etc. can be used. The resin used for the resin base material is preferably a polymer material having relatively high solvent resistance and heat resistance. Specifically, fluorine resin, polyethylene, polypropylene, polyvinyl chloride, polyvinyl fluoride, polystyrene, ABS resin, polyamide, polyacetal, polyester, polycarbonate, modified polyphenylene ether, polysulfone, polyarylate, polyetherimide, polyether mon Phon, Polyamideimide, Polyimide, Polyphenylene sulfide, Liquid crystalline polyester, Polyethylene terephthalate, Polybutylene terephthalate, Polyethylene naphthalate, Polymicroxylene dimethylene terephthalate, Polyoxymethylene, Polyethersulfone, Polyetheretherketone, Polyacrylate, Acrylonitrile -Styrene resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, Epoxy resins, polyurethanes, silicone resins, amorphous polyolefins, and the like. In addition to the above, any polymer material that satisfies a predetermined condition can be used, and two or more types of copolymers can be used. Furthermore, you may use the base material which has gas barrier property which interrupts | blocks gas, such as a water | moisture content and oxygen, as needed.

(3) Other Configurations The organic EL substrate in the present invention is not particularly limited as long as it has the above-described substrate and the first electrode layer.

  For example, when the organic EL element produced by the present invention is used for a display device, the following configuration can be formed.

  For example, when the first electrode layer is formed in a pattern on the base material, an insulating layer may be formed so as to cover the end of the pattern of the first electrode layer. The insulating layer may be formed so as to define pixels. As the insulating layer, a general organic EL element can be used.

  Further, for example, a TFT element may be formed on the substrate. As the TFT element, a common element in an organic EL element can be used.

Further, when the organic EL element is used in a full-color or multi-color display device, pixel partition walls may be formed on the substrate. In the case where pixel partition walls are formed, the cathode can be formed in a pattern without using a metal mask or the like.
The material for the partition walls for pixels can be the same as the material for the partition walls described above.
When the light emitting layer is formed in a pattern, a surface treatment for changing the surface energy (wetting property) may be performed on the pixel partition wall in advance.

  A plurality of the insulating layers, TFT elements, and pixel partition walls described above may be formed in the light emitting region.

II. Organic Layer Forming Step The organic layer forming step in the present invention is a step of forming at least one organic layer among the organic layers constituting the organic EL layer including the light emitting layer in the light emitting region by a discharge method. Moreover, the said organic layer formation process is a process which has a high boiling-point solvent application | coating process, the coating liquid application process for organic layers, and a drying process. Hereinafter, the organic layer formed by this process and each process will be described separately.

1. Organic Layer The organic layer formed in this step constitutes an organic EL layer having at least a light emitting layer. Here, the organic EL layer in the present invention is a layer including at least a light-emitting layer, and the layer configuration refers to a layer having one or more organic layers.
Specific examples of such an organic layer include a light emitting layer, a hole injection layer, an electron injection layer, a hole transport layer, and an electron transport layer. The hole transport layer may be integrated with the hole injection layer by imparting a hole transport function to the hole injection layer. In addition, the electron transport layer may be integrated with the electron injection layer by adding an electron transport function to the electron injection layer. Furthermore, as an organic layer which comprises an organic EL layer, the layer etc. for preventing the penetration of a hole or an electron like a carrier block layer, and improving recombination efficiency can be mentioned.
Hereinafter, each layer will be described.

(1) Light emitting layer As a material used for the light emitting layer in this invention, light emitting materials, such as a pigment-type material, a metal complex type material, a polymeric material, can be mentioned, for example.

  Examples of dye materials include cyclopentadiene derivatives, tetraphenylbutadiene derivatives, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, silole derivatives, thiophene ring compounds, pyridine ring compounds. Perinone derivatives, perylene derivatives, oligothiophene derivatives, trifumanylamine derivatives, oxadiazole dimers, pyrazoline dimers, and the like.

  Examples of the metal complex-based material include an aluminum quinolinol complex, a benzoquinolinol beryllium complex, a benzoxazole zinc complex, a benzothiazole zinc complex, an azomethylzinc complex, a porphyrin zinc complex, and a eurobium complex. Alternatively, a metal complex having a rare earth metal such as Tb, Eu, or Dy and having a ligand such as oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, or quinoline structure can be given.

  Furthermore, examples of the polymer material include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyvinylcarbazole, polyfluorene derivatives, polyquinoxaline derivatives, and copolymers thereof. be able to.

  A dopant may be added to the light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength. Examples of such doping agents include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazoline derivatives, decacyclene, phenoxazone, quinoxaline derivatives, carbazole derivatives, fluorene derivatives. Etc.

  The thickness of the light emitting layer is not particularly limited as long as it can provide a function of emitting light by providing a recombination field between electrons and holes, and is, for example, about 1 nm to 500 nm. can do.

(2) Hole Injection Layer As described above, the hole transport layer may be integrated with the hole injection layer by imparting a hole transport function to the hole injection layer. That is, the hole injection layer may have only a hole injection function, or may have both a hole injection function and a hole transport function.

  The material used for the hole injection layer is not particularly limited as long as it can stabilize the injection of holes into the light emitting layer, and the compounds exemplified as the light emitting material for the light emitting layer. In addition, phenylamine-based, starburst-type amine-based, phthalocyanine-based, polyaniline, polythiophene, polyphenylene vinylene derivatives, and the like can be used. Specifically, bis (N- (1-naphthyl) -N-phenyl) benzidine (α-NPD), 4,4,4-tris (3-methylphenylphenylamino) triphenylamine (MTDATA), poly-3 4,4 ethylenedioxythiophene-polystyrene sulfonic acid (PEDOT-PSS), polyvinylcarbazole (PVCz), and the like.

  Further, the thickness of the hole injection layer is not particularly limited as long as the hole injection function and the hole transport function are sufficiently exerted, but specifically, within the range of 0.5 nm to 1000 nm, Especially, it is preferable that it exists in the range of 10 nm-500 nm.

(3) Electron Injection Layer As described above, the electron transport layer may be integrated with the electron injection layer by imparting an electron transport function to the electron injection layer. That is, the electron injection layer may have only an electron injection function, or may have both an electron injection function and an electron transport function.

The material used for the electron injecting layer is not particularly limited as long as it can stabilize the injection of electrons into the light emitting layer, and compounds exemplified as the light emitting material of the light emitting layer can be used. Can be used.
Alternatively, a metal doped layer in which an alkali metal or alkaline earth metal is doped on an electron transporting organic material may be formed and used as an electron injection layer. Examples of the electron-transporting organic material include bathocuproine, bathophenanthroline, and phenanthroline derivatives. Examples of the metal to be doped include Li, Cs, Ba, and Sr.

The thickness of the electron injection layer is not particularly limited as long as the electron injection function and the electron transport function are sufficiently exhibited.

(4) Electron transport layer The material used for the electron transport layer is not particularly limited as long as it is a material capable of transporting electrons injected from the cathode into the light emitting layer. For example, bathocuproine, Examples include bathophenanthroline, phenanthroline derivatives, triazole derivatives, oxadiazole derivatives, and derivatives of tris (8-quinolinolato) aluminum complex (Alq ₃ ).

  The thickness of the electron transport layer is not particularly limited as long as the electron transport function is sufficiently thick.

2. Each process in an organic layer formation process (1) High boiling point solvent application process The high boiling point solvent application process in this invention is a process of apply | coating a high boiling point solvent in the said light emission area | region, and forming a pool. In this step, it is sufficient if a pool can be formed in the light emitting region, and the lower layer of the pool may be the first electrode layer or a layer constituting the organic EL layer.

  Here, the “high boiling point solvent” can dissolve or disperse the organic layer material described later, and emits light in the temperature and humidity conditions in the high boiling point solvent coating step and the organic layer coating liquid coating step in the present invention. It refers to a solvent having a boiling point enough to keep the inner pool at a predetermined depth.

  The high boiling point solvent is appropriately selected according to the temperature / humidity conditions in the high boiling point solvent coating step and the organic layer coating liquid coating step, the type of the organic layer material, and the like, and is not particularly limited. In the case of a polar solvent, a solvent having a boiling point in the range of 70 ° C to 300 ° C, particularly in the range of 80 ° C to 250 ° C, particularly in the range of 90 ° C to 230 ° C is preferable. On the other hand, in the case of a nonpolar solvent, a solvent having a boiling point in the range of 100 ° C to 300 ° C, particularly in the range of 130 ° C to 280 ° C, particularly in the range of 150 ° C to 270 ° C is preferable. This is because, when the boiling point is less than the above range, the temperature / humidity conditions in the high boiling point solvent coating step and the organic layer coating liquid coating step are limited, and productivity may be lowered. On the other hand, when the boiling point exceeds the above range, it may be difficult to remove the high boiling point solvent without deteriorating the organic layer in the drying step described later.

  In addition, the vapor pressure of the high boiling point solvent is not particularly limited as long as the pool can be maintained at a predetermined depth under the temperature and humidity conditions in the high boiling point solvent coating step and the organic layer coating liquid coating step. Although not limited, it is preferably in the range of 0.05 hPa to 10 hPa, in particular in the range of 0.05 hPa to 4.5 hPa, particularly preferably in the range of 0.05 hPa to 1.0 hPa.

Such a high boiling point solvent may be a polar solvent or a nonpolar solvent.
Examples of the polar solvent include monohydric alcohols such as water, propanol, butanol, pentanol, hexanol, heptanol and octanol, dihydric alcohols such as ethylene glycol and propylene glycol, and trihydric alcohols such as glycerin. Depending on how the hydroxyl group and carbon are attached, they are classified into three types of primary, secondary and tertiary series, but are not particularly limited. Other ethers such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, N, N-dimethylformamide , Dimethyl sulfoxide, N-methylpyrrolidone, cyclohexanone, and the like. These may be used alone or in combination of two or more.
On the other hand, as nonpolar solvents, toluene, xylene, mesitylene, 1,2,4-trimethylbenzene, triethylbenzene, hexylbenzene, cyclohexylbenzene, anisole, butyl benzoate, ethyl benzoate, methyl benzoate, tetralin, 1- Aromatic hydrocarbons such as methyl naphthalene, diphenyl ether, diphenylmethane, diphenylethylene, and diphenyl sulfide can be exemplified.

  In this step, a surfactant may be added to the high boiling point solvent as necessary. The surfactant can be the same as that used in a general method for manufacturing an organic EL element, and thus description thereof is omitted here.

The depth of the pool formed by this process is such a depth that the organic layer material in the organic layer coating liquid applied in the organic layer coating liquid coating process described later can be uniformly diffused. If it is, it will not specifically limit, It can select suitably by the magnitude | size of a light emission area | region, the organic material used for the coating liquid for organic layers mentioned later, a solvent, etc.
Specifically, the depth of the pool may be in the range of 0.5 μm to 50 μm, in particular in the range of 0.5 μm to 15 μm, particularly in the range of 0.5 μm to 5 μm. When the depth of the pool is less than the above range, it may be difficult to uniformly diffuse the organic layer material in the organic layer coating liquid applied in the organic layer coating liquid coating step described later. This is because, when the depth of the pool exceeds the above range, the time required for the drying process becomes long, so that the production efficiency may be lowered.
The depth of the pool in this step refers to the distance from the lower surface of the pool to the maximum depth of the pool, for example, the distance indicated by Q in FIGS. 3 (a) and 3 (b). 3A and 3B are cross-sectional views taken along line AA in FIG.
The depth of the pool can be determined by, for example, directly measuring with a wet film thickness meter or measuring with a non-contact thickness meter (optical interference, laser method).

Further, when the light emitting region is partitioned by the partition wall in this step, the depth of the pool may be smaller than the partition wall height as the relationship between the pool depth and the partition wall height (see FIG. 3A). ), The depth of the pool may be equal to the height of the partition wall (not shown), or the pool depth may be larger than the height of the partition wall (see FIG. 3B). Here, when the depth of the pool is larger than the height of the partition wall, the depth of the pool is determined by applying the organic layer coating liquid, which will be described later, by the discharge method. Is not particularly limited as long as the depth does not spread out of the light emitting region, and can be adjusted by selecting a partition wall material or a high boiling point solvent.
On the other hand, even when the light emitting region is partitioned by a pattern forming layer having a lyophilic region and a liquid repellent region, the depth of the pool is the same as when the organic layer coating liquid described later is applied by a discharge method. If the depth is such that the coating liquid for the organic layer does not spread out of the light emitting region, it is not particularly limited, and it is adjusted by selecting the degree of liquid repellency in the liquid repellent region and the high boiling point solvent. can do.

  The method for applying the high boiling point solvent used in this step is not particularly limited as long as it is a method capable of applying the high boiling point solvent in the light emitting region. In this step, a discharge method such as an inkjet method or a dispenser method can be suitably used, and the inkjet method is particularly preferable.

(2) Organic layer coating solution coating step In the organic layer coating solution coating step of the present invention, the organic layer coating solution containing the organic layer material and the solvent is formed in the light emitting region where the pool is formed. The organic layer forming layer is formed by diffusing the organic layer material in the pool and applying the layer by a discharge method.

In this step, usually, an organic layer coating solution containing an organic layer material and a solvent is prepared.
As said organic layer material, it can select suitably according to the organic layer formed. Specifically, since it was explained in the above-mentioned section “1. Organic layer”, explanation here is omitted.

The solvent is particularly a solvent that is compatible with the above-described high boiling point solvent, can dissolve or disperse the organic layer material, and can form a desired organic layer using a discharge method. It is not limited.
Here, in the present invention, “the solvent is compatible with the high-boiling solvent” means, for example, that the above-mentioned high-boiling solvent 50 ml and the above-mentioned solvent are added to a 300-ml beaker at room temperature (or a temperature at which the organic layer coating liquid coating step is performed). When 50 ml is added and the mixed solvent is allowed to stand for 1 minute after stirring at 300 rpm for 1 minute using a stirrer, it means that no separation of the mixed solvent is observed.

Moreover, as said solvent, the same kind of solvent as the high boiling point solvent mentioned above may be sufficient, and a different kind of solvent may be sufficient.
When a different solvent is used as the solvent, in the present invention, for example, even when the solvent is a solvent having a relatively low boiling point (hereinafter referred to as a low boiling point solvent), the organic layer coating solution is added to the pool. Since it is applied, the organic layer material can be uniformly diffused in the high boiling point solvent, so that a colored layer for an organic layer in which the organic layer material is uniformly dispersed in the light emitting region can be formed.
Therefore, it is possible to use a low solvent that could not be used in the organic layer forming process by the conventional discharge method without forming a pool, so that the range of material selection can be expanded.

  In addition, the low boiling point solvent in this invention points out the solvent whose boiling point is less than 70 degreeC, when it is a polar solvent, and points out the solvent whose boiling point is less than 100 degreeC in the case of a nonpolar solvent.

  In addition, when the said solvent is a high boiling point solvent and a different solvent, it is not restricted to a low boiling point solvent.

  The solvent is appropriately selected depending on the type of the organic layer material, and specifically, the same solvent as the above-described high boiling point solvent can be used. In addition to the solvents exemplified in the section of the high boiling point solvent, low boiling point solvents such as chloroform, methylene chloride, dichloroethane, and tetrahydrofuran can be used.

  For example, when the organic layer material is a light emitting material, chloroform, methylene chloride, dichloroethane, tetrahydrofuran, toluene, xylene, tetralin, mesitylene, and the like can be preferably used.

  The viscosity of the organic layer coating liquid used in this step is not particularly limited as long as it can be applied to the organic layer coating liquid using a discharge method. In addition, the viscosity of the organic layer coating liquid can be appropriately adjusted depending on the organic layer material, the type of solvent, the solid content of the organic layer coating liquid, and the like.

  The discharge method used in this step may be any method that can apply an organic layer coating solution in an amount that can form an organic layer having a desired film thickness in the light emitting region. Specific examples include an inkjet method and a dispenser method. In the present invention, the ink jet method is particularly preferable.

In this step, after applying the organic layer coating liquid, a treatment for applying ultrasonic vibration to the organic EL substrate may be performed in order to promote dispersion of the organic layer material in the organic layer forming layer.
In addition, after applying the organic layer coating liquid, the organic layer forming layer is kept for a certain period of time in order to make the thickness of the organic layer forming layer uniform or to sufficiently disperse the organic material in the organic layer forming layer. You may perform the holding process to hold | maintain. At this time, in order to prevent drying of the organic layer forming layer, a cap that covers the organic layer forming layer is placed, placed under pressure, and the temperature condition is higher than the temperature during coating of the organic layer coating liquid. It is also possible to take a dry prevention treatment such as lowering the temperature. In addition, about the pressurization conditions and temperature conditions in the said drying prevention treatment, it can adjust suitably with kinds, such as an organic layer material, a solvent, and a high boiling point solvent.

(3) Drying step The drying step in the present invention is a step of drying the organic layer forming layer to form the organic layer.

  The drying method used in this step is not particularly limited as long as it can remove the solvent and the high boiling point solvent from the organic layer forming layer. In this step, the organic EL substrate may be heated and dried, or may be dried without heating, but the organic EL substrate is preferably heated. About pressure reduction conditions and heating conditions, it can choose suitably according to a kind etc. of a solvent and a high boiling point solvent.

  When the organic EL substrate has a partition wall that can be peeled off, the partition wall may be peeled off after the organic EL layer forming layer is dried.

(4) Organic layer forming step In the organic layer forming step in the present invention, if any one of the above-described hole injection layer, hole transport layer, light emitting layer, electron injection layer, and electron transport layer can be formed. Although not particularly limited, it is particularly preferable to form a light emitting layer.

Moreover, in this invention, it is also possible to form a some organic layer by repeating the said organic layer formation process.
In the present invention, when a plurality of organic layers are formed, it is preferable that the properties of the high boiling point solvent and the solvent used when forming the two adjacent organic layers are different. More specifically, in the case of forming a laminate of two organic layers, the high-boiling solvent and the solvent used when forming the first organic layer on the first electrode layer are polar solvents. It is preferable that the high-boiling solvent and the solvent provided when the second organic layer is formed on the first organic layer are preferably nonpolar solvents.

III. Manufacturing method of organic EL element The manufacturing method of the organic EL element in this invention will not be specifically limited if it has the demarcation process and organic layer formation process which were mentioned above. Moreover, in this invention, it usually has the organic EL layer formation process containing the said organic layer formation process, and a 2nd electrode layer formation process. Hereinafter, each step will be described.

1. Organic EL layer formation process The organic EL layer formation process in this invention is a process including the organic layer formation process mentioned above.
In the organic EL layer forming step, at least one organic layer of the organic layers constituting the organic EL layer may be formed in the organic layer forming step described above, and the organic EL layer may be formed using a method other than the discharge method. You may form the other layer which comprises a layer.
In the present invention, the other layer formed by a method other than the discharge method is preferably a layer other than the light emitting layer. Examples of such a layer include a hole injection layer, an electron injection layer, and an electron transport layer.

  The material used for the hole injection layer is not particularly limited as long as it can stabilize the injection of holes into the light emitting layer. In addition, oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, aluminum oxide, and titanium oxide can be given.

The material used for the electron injection layer is not particularly limited as long as it is a material that can stabilize the injection of electrons into the light emitting layer. In addition to the materials for the electron injection layer described above, Aluminum lithium alloy, lithium fluoride, strontium, magnesium oxide, magnesium fluoride, strontium fluoride, calcium fluoride, barium fluoride, aluminum oxide, strontium oxide, calcium, polymethyl methacrylate, sodium polystyrene sulfonate, lithium, cesium, Alkali metals, alkali metal halides, alkali metal organic complexes, and the like, such as cesium fluoride, can be used.
Except for the points described above for the electron injecting and transporting layer, it can be the same as that described in the section of the organic layer forming step.

  The material for the electron transport layer may be the same as that described in the section “1. Organic layer” described above.

  As a method other than the discharge method, a wet method or a dry method may be used.

  Examples of the wet method include a method of applying a coating liquid. Examples of the coating method include a dip coating method, a roll coating method, a blade coating method, a spin coating method, a bar coating method, a wire bar coating method, a casting method, and an LB method. In addition, a transfer method such as a thermal transfer method, a printing method using a printing plate, and the like can be given.

  As the dry method, a general vapor deposition method such as a vacuum vapor deposition method can be used.

2. Second electrode layer forming step The second electrode layer forming step in the present invention is a step of forming the second electrode layer on the organic EL layer.

  The second electrode layer may be an anode or a cathode, but is usually formed as a cathode.

  The second electrode layer may or may not have transparency, and is appropriately selected depending on the light extraction surface and the like. For example, when light is extracted from the second electrode layer side, the second electrode layer needs to be transparent or translucent.

  As the second electrode layer (cathode), it is preferable to use a conductive material having a small work function so that electrons can be easily injected. For example, magnesium alloys such as MgAg, aluminum alloys such as AlLi, AlCa, and AlMg, Li, Examples thereof include alkali metals and alkaline earth metals including Ca, and alloys of alkali metals and alkaline earth metals.

  The second electrode layer preferably has a low resistance, and generally a metal material is used, but an organic compound or an inorganic compound may be used.

  In this step, it is preferable to form a second electrode layer by forming a metal material on the organic EL layer. This is because the second electrode layer may be made of a material having a low resistance, and a metal material is most suitable.

  As a method for forming a metal material, a general electrode forming method can be used. For example, a general vapor deposition method such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a method for applying a metal paste. Etc. Among these, a vacuum deposition method and a method of applying a metal paste are preferable. The vacuum evaporation method is a method that causes little damage to the organic EL layer in a dry process and is suitable for stacking. Further, the method of applying the metal paste is a wet process, and the wet process is more suitable for dealing with a larger area than the dry process. Even in the wet process, a metal paste containing a solvent that does not affect the organic EL layer can be used. That is, a wet process can be applied by devising the organic EL layer so as not to be affected by the solvent resistance of the organic EL layer.

3. Other Steps In the present invention, steps other than the above-described organic EL layer forming step and second electrode layer forming step can be performed as necessary. For example, the process etc. which form the said organic EL base material can be mentioned.

IV. Organic EL element The organic EL element manufactured by the manufacturing method of this invention is demonstrated.
The organic EL element includes an organic EL substrate having a substrate and a first electrode layer formed on the substrate, an organic EL layer having at least a light emitting layer, and a second electrode formed on the organic EL layer. And a layer. The organic EL layer only needs to have at least a light emitting layer, and may have a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer as necessary.

The organic EL device produced according to the present invention may be a bottom emission type in which light is extracted from the anode side, or may be a top emission type in which light is extracted from the cathode side, and light is extracted from both sides of the anode and the cathode. A double-sided light emitting type may be used.
The organic EL element can be suitably used for a display device and a lighting device. In the present invention, the organic EL element is particularly preferably an organic EL panel used in a lighting device.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described with reference to examples and comparative examples.

[Example 1]
(Production of organic EL panel for evaluation)
On the transparent substrate in which the transparent electrode layer made of ITO was formed in a rectangular shape, a 3 μm-thick barrier rib forming layer was formed by spin coating. The partition wall forming layer was patterned by a photolithography method, and the partition wall was patterned by exposure and development using a mask pattern having a light emitting area of 50 mm square and a partition wall width of 3 mm.

Next, a hole injection layer (PEDOT) having a thickness of 60 nm was formed in the light emitting region using a gravure printing method.
Next, a pool was formed in the light emitting region using tetralin (boiling point: 206 ° C.-208 ° C.) as a high boiling point solvent so as to be equivalent to a partition wall having a thickness of 3 μm. At this time, an inkjet apparatus DMP3000 (manufactured by Dimatix) was used as the apparatus.

Furthermore, before the pool dried, the light emitting layer coating solution was applied to the light emitting region with DMP3000. The light emitting layer coating solution diffused in the pool to form a uniform wet film.
Next, provisional drying was performed at 80 ° C. using an IR heater, followed by main drying at 180 ° C. using a hot plate to obtain a light emitting layer as a dry film.
In addition, the light emitting layer coating solution is a solution obtained by using mesitylene (boiling point: 165 ° C.) as a solvent and ADS232GE (manufactured by American Dye Source, Inc.) as an organic light emitting material at a solid content of 1.0 wt%. It was used.

  Subsequently, a 10-nm-thick metal calcium and a 500-nm-thick silver were laminated on the light-emitting layer by a vacuum deposition method to form a counter electrode layer. The organic EL panel for evaluation was obtained by the above procedure.

(Evaluation)
As a result of observing the light emitting state of the evaluation organic EL panel, it was found that the light emitting region emitted light uniformly.

[Comparative Example 1]
An organic EL panel for evaluation was produced in the same manner as in the example except that the light emitting layer coating solution was applied without forming a pool with a high boiling point solvent. When the light emission state of the obtained organic EL panel for evaluation was observed, streaky unevenness along the inkjet coating direction was observed.

[Comparative Example 2]
An organic EL panel for evaluation was produced in the same manner as in Example except that a pool was formed with tetrahydrofuran (boiling point: 66 ° C.) and the coating solution for the light emitting layer was applied. Could not hold pool until completion. Further, when the light emission state of the obtained organic EL panel for evaluation was observed, streaky unevenness along the ink jet application direction was observed.

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... 1st electrode layer 3 ... Organic EL base material 4 ... Partition wall 5 ... Pool 6 ... Organic layer (light emitting layer)
6 '... organic layer forming layer 6 "... organic layer coating solution 7 ... second electrode layer 10 ... organic EL element 20 ... inkjet nozzle

Claims (2)

Providing an organic electroluminescent substrate having a substrate and a first electrode layer formed on the substrate, and defining a light emitting region of the organic electroluminescent substrate;
An organic layer forming step of forming at least one organic layer by an ejection method among organic layers constituting an organic electroluminescence layer including a light emitting layer in the light emitting region;
The organic layer forming step includes
A high boiling point solvent application step of applying a high boiling point solvent in the light emitting region to form a pool;
An organic layer coating solution containing an organic layer material and a solvent is applied by a discharge method into the light emitting region where the pool is formed, and the organic layer material is diffused into the pool to form an organic layer forming layer. An organic layer coating liquid coating step to be formed;
A drying step of drying the organic layer forming layer to form the organic layer;
A method for producing an organic electroluminescence element, characterized by comprising:   2. The method of manufacturing an organic electroluminescent element according to claim 1, wherein the defining step is a step of forming a partition wall for defining the light emitting region on the organic electroluminescent substrate.

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