JP2013206631A - Organic electroluminescent element manufacturing method and organic electroluminescent device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element manufacturing method which can manufacture a high efficiency and long-life organic EL element simply, as well as provide an organic EL device.SOLUTION: In a manufacturing method for an organic EL element comprising a first electrode 201 formed on a substrate 200, a luminescent medium layer formed on the first electrode 201, and a second electrode 207 opposed via the luminescent medium layer to the first electrode 201, the luminescent medium layer including an organic luminescent layer 205 and an organic layer (hole transport layer 203) formed between the organic luminescent layer 205 and the first electrode 201. A poor solvent 204 which exhibits low solubility against an organic material forming the organic layer is coated on the organic layer and then, before the poor solvent 204 evaporates, an organic luminescent material 205a is coated on the organic layer to form the organic luminescent layer 205.

Description

  The present invention relates to a method for manufacturing an organic electroluminescence element utilizing an electroluminescence phenomenon and an organic electroluminescence device.

An organic electroluminescence element (hereinafter referred to as 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.
Such an organic EL element is used, for example, as a sub-pixel 102 constituting the pixel 101 of the organic EL display panel 100 shown in FIG. One pixel 101 includes three sub-pixels 102 that emit three primary colors of R (red), G (green), and B (blue). In the case of active driving, a thin film transistor (hereinafter also referred to as a TFT) is organic. It is formed on the substrate of the EL element.
In general, a display substrate is used in which an insulating material such as patterned photosensitive polyimide is formed in a partition shape so as to partition subpixels. At this time, the barrier rib pattern is formed so as to cover the edge portion of the transparent electrode formed as an anode, and the barrier rib pattern defines the subpixel region.

Then, a hole injection layer is formed on the transparent electrode and the barrier rib pattern. There are two methods for forming a hole injection layer for injecting hole carriers, dry film formation and wet film formation. In the case of using a wet film formation method, a polythiophene derivative dispersed in water is generally used. A hole transport layer may be formed on the hole injection layer.
Similarly, there are two methods for forming the organic light emitting layer: dry film formation and wet film formation. However, when using the vacuum evaporation method, which is dry film formation that facilitates uniform film formation, a fine pattern mask is used. Therefore, it is necessary to perform patterning, and large substrates and fine patterning are very difficult.

  On the other hand, it is possible to use a method in which a polymer material or a low molecular material is dissolved in a solvent to form a coating solution, and this is formed into a thin film by a wet film forming method. When a light emitting medium layer including an organic light emitting layer is formed by a wet film formation method using a coating material of a polymer material or a low molecular material, the layer structure is laminated with a hole transport layer and an organic light emitting layer from the anode side. A layer structure is common. At this time, the organic light emitting layer is formed by dissolving or stably dispersing organic light emitting materials having respective emission colors of red (R), green (G), and blue (B) in a solvent in order to form a color panel. It can be applied separately using organic luminescent ink (see Patent Documents 1 and 2).

When the organic layer is formed by vacuum deposition, the large area, high definition is difficult as described above, and the equipment cost is high, whereas the wet film formation method does not use vacuum equipment, so the equipment cost is relatively low, Since no mask is used, there is an advantage in increasing the area.
For the patterning film formation by the wet film formation method, pattern formation by an ink jet method, a printing method, or a nozzle printing method has been proposed. For example, the ink jet method disclosed in Patent Document 3 is a method for obtaining a desired pattern by ejecting a light emitting layer material dissolved in a solvent from an ink jet nozzle onto a substrate and drying the material on the substrate.

  Although organic EL elements have a laminated structure and are functionally separated to achieve high efficiency and long life, there is a problem that it is difficult to laminate organic films by the wet film formation method. This is because when another organic film is applied on the organic film, the lower organic film is dissolved. One method is to select a solvent in which the lower organic film does not dissolve (see Patent Documents 4 and 5), but the combination of the lower material and the organic material applied thereon is limited, and the organic Since the selection range of the material is narrowed, the device characteristics are low.

Alternatively, a crosslinkable material may be used for the lower layer, and insolubilization may be performed by crosslinking after film formation. In this case, the introduction of a highly reactive cross-linking group is likely to adversely affect the device characteristics, and material synthesis becomes difficult and expensive.
On the other hand, the method of forming into a laminated structure by forming by the wet method using the mixed solvent which consists of a good solvent and a poor solvent is disclosed (refer patent document 6). However, this method has a problem that the good solvent dissolves the lower layer, and the solubility of the ink is lowered by reducing the good solvent ratio, so that it can be formed only with a thin film thickness.

JP 2001-93668 A JP 2001-155858 A Japanese Patent Laid-Open No. 10-12377 JP 2002-299061 A JP 2002-319488 A JP 2005-259523 A

  The present invention has been made in view of the above problems, and an object thereof is to provide an organic EL device manufacturing method and an organic EL device capable of easily manufacturing a high-efficiency and long-life organic EL device. It is.

  The invention of claim 1 includes a first electrode formed on a substrate, a light emitting medium layer formed on the first electrode, and a second electrode facing the first electrode through the light emitting medium layer. A method of manufacturing an organic electroluminescence device, wherein the light emitting medium layer includes an upper organic layer, and a lower organic layer formed between the upper organic layer and the first electrode, After applying a poor solvent having low solubility with respect to the organic material forming the lower organic layer on the lower organic layer, the poor solvent is used as the organic material forming the upper organic layer on the lower organic layer. The upper organic layer is formed by coating before evaporation.

According to a second aspect of the present invention, in the method of manufacturing an organic electroluminescence element according to the first aspect, the lower organic layer is a hole transport layer.
According to a third aspect of the present invention, in the method of manufacturing an organic electroluminescent element according to the second aspect, the hole transport layer is made of an organic material containing a low molecular material.
According to a fourth aspect of the present invention, in the method of manufacturing an organic electroluminescent element according to the third aspect, the organic material forming the hole transport layer includes a polymer material.

According to a fifth aspect of the present invention, in the method for manufacturing an organic electroluminescent element according to the first aspect, the lower organic layer is an organic electron transporting layer.
Invention of Claim 6 is a manufacturing method of the organic electroluminescent element as described in any one of Claims 1-5, The organic material ink for forming the said upper organic layer contains a solvent, The boiling point of this solvent Is 160 ° C. or lower.
A seventh aspect of the present invention is the method of manufacturing an organic electroluminescent element according to any one of the first to sixth aspects, wherein the vapor pressure of the poor solvent is included in the organic material ink for forming the upper organic layer. It is characterized by being lower than the vapor pressure of the solvent.

Invention of Claim 8 is a manufacturing method of the organic electroluminescent element as described in any one of Claims 1-7, The organic material for forming the said upper organic layer on the said lower organic layer is non-contacted It is characterized by being applied by.
The invention of claim 9 is characterized by comprising an organic electroluminescence panel comprising a large number of organic electroluminescence elements manufactured by the method according to any one of claims 1 to 8.
According to a tenth aspect of the present invention, in the organic electroluminescent device according to the ninth aspect, the organic electroluminescent panel is a display panel.
The invention of claim 11 is the organic electroluminescence device according to claim 9, wherein the organic electroluminescence panel is a lighting panel.

  According to the present invention, when another organic material is applied on the organic layer, the organic material forming the lower organic layer can be prevented from eluting into the ink of the upper organic material by the poor solvent. As a result, it is possible to suppress a decrease in the thickness of the lower organic layer, so that a highly efficient and long-life organic EL element can be obtained easily.

It is a figure which shows typically the sub pixel of an organic electroluminescence display panel. It is a figure which shows one Embodiment when manufacturing an organic EL element by this invention. It is a figure which shows an example of the TFT substrate with a partition which can be used for this invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 shows an embodiment of manufacturing an organic EL device according to the present invention. When manufacturing an organic EL device by the method shown in FIG. 2, first, a first electrode 201 is formed on a substrate 200 ( FIG. 2 (a)). Next, after forming the hole injection layer 202 on the first electrode 201, the hole transport layer 203 is formed on the hole injection layer 202. (FIGS. 2B and 2C).

  If the hole transport layer 203 is formed on the hole injection layer 202, a poor solvent 204 having low solubility with respect to the hole transport layer 203 is applied on the hole transport layer 203, and then hole transport is performed. An organic light emitting material 205a is applied on the layer 203 before the poor solvent 204 evaporates (FIGS. 2D and 2E). Next, the solvent and the poor solvent 204 contained in the organic light emitting material 205a are dried to form the organic light emitting layer 205 on the hole transport layer 203 (FIG. 2 (f)). Then, as shown in FIGS. 2G and 2H, after the electron transport layer 206 is formed on the organic light emitting layer 205, the second electrode 207 is formed on the electron transport layer 206, whereby the organic EL A light emitting medium layer of the element is formed between the first electrode 201 and the second electrode 207.

  Most of the organic materials applied to the hole transport layer 203, the organic light emitting layer 205, the electron transport layer 206, and the like described above have similar solubility in solvents. For this reason, for example, when the organic light emitting material 205a is applied onto the hole transport layer 203 to form the organic light emitting layer 205, the solvent contained in the organic light emitting material 205a dissolves the hole transport layer 203, and the holes There arises a problem that the transport layer 203 is reduced in thickness.

  In this embodiment, as described above, the poor solvent 204 having low solubility with respect to the hole transport layer 203 is coated on the hole transport layer 203 before the organic light emitting layer 205 is formed. Dissolution of the hole transport layer 203 and film reduction can be suppressed. Similarly, when the electron transport layer 206 is formed on the organic light emitting layer 205, a poor solvent having low solubility with respect to the organic light emitting layer 205 is coated on the organic light emitting layer 205 to form an organic material. It is also possible to suppress dissolution of the light emitting layer 205 and film loss.

The vapor pressure of the poor solvent 204 used in the present invention is preferably lower than the vapor pressure of the solvent contained in the ink forming the upper organic material 205a applied thereon. This is because the solvent contained in the ink forming the upper organic material 205a evaporates earlier than the poor solvent 204 has less influence on the lower layer.
In order to evaporate faster than the poor solvent 204, the boiling point of the solvent contained in the upper organic material 205a is preferably 160 ° C. or lower, desirably 150 ° C. or lower, more desirably 120 ° C. or lower.

In the present embodiment, the method of applying the upper organic material 205a on the lower organic layer 203 while the poor solvent 204 is not evaporated can be appropriately selected from known techniques. For example, a spin coating method, a dipping method, a spray method, a nozzle printing method, an ink jet method, or the like can be given. A method that can apply the organic light emitting material (ink) 205a in a non-contact manner is preferable.
In the nozzle printing method, a nozzle for dropping the poor solvent 204 and a nozzle for dropping the upper organic material 205a are provided in parallel to the coating direction, so that the upper organic material 205a is applied immediately after applying the poor solvent 204. Is possible.

The light emitting medium layer is a layer including at least an organic light emitting layer, preferably a hole injection layer, a hole transport layer or an electron block layer, an organic light emitting layer, an electron transport layer or a hole block layer on the first electrode, A combination of a plurality of layers such as an electron injection layer is desirable.
The organic EL device manufactured according to this embodiment can be applied to both passive driving and active driving.
Moreover, the organic EL element manufactured by this embodiment is applicable to a display panel, an illumination panel, etc.

Hereinafter, the configuration of an organic EL display device using the organic EL element manufactured according to the present invention as a sub-pixel will be described in detail.
<Board>
The substrate used in the organic EL display device may be any substrate that can support an organic EL element, but in the case of an active matrix system, a TFT substrate on which a thin film transistor is formed is used.
FIG. 3 shows an example of a TFT-coated TFT substrate that can be used in an organic EL display device. A first electrode (pixel electrode) 301 is formed on the TFT substrate 300 shown in FIG. 3, and the first electrode (pixel electrode) 301 and the TFT are electrically connected.

  The TFT and the active matrix driving type organic EL display device disposed above the TFT are supported by a support. Any material can be used as the support as long as it has mechanical strength and insulation and is excellent in dimensional stability. For example, in addition to glass and quartz, polypropylene, polyethersulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, and other plastic films and plastic sheets are used as support materials (substrates). Material).

  Further, on the surface of the plastic film or plastic sheet, a metal oxide film made of silicon oxide, aluminum oxide, etc., a metal fluoride film made of aluminum fluoride, magnesium fluoride, etc., a metal made of silicon nitride, aluminum nitride, etc. As a support material, a transparent base material in which a polymer resin film made of a nitride film, a metal oxynitride film made of silicon oxynitride or the like, an acrylic resin, an epoxy resin, a silicone resin, a polyester resin or the like is formed of a single layer or more Can be used. Furthermore, in addition to a metal foil or sheet made of aluminum, stainless steel or the like, a non-translucent base material in which a metal film made of aluminum, copper, nickel, stainless steel or the like is laminated on the surface of a plastic film or plastic sheet. Can also be used as a support material.

  The light-transmitting property of the support may be selected according to the surface from which light is extracted, and an inorganic film is formed on the surface of the support to avoid intrusion of moisture into the organic EL display device. Or applying a moisture-proof treatment or a hydrophobic treatment by applying a fluororesin. In particular, it is preferable to reduce the moisture content and gas permeability coefficient of the support in order to prevent moisture from entering the luminescent medium layer.

As the thin film transistor provided on the support, a known thin film transistor can be used. Specifically, a thin film transistor mainly including an active layer 301 in which a source / drain region and a channel region are formed, a gate insulating film 302, and a gate electrode 305 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 301 is not particularly limited, and examples thereof include inorganic semiconductor materials such as amorphous silicon, polycrystalline silicon, microcrystalline silicon, and cadmium selenide, metal oxide semiconductor materials such as ZnO and IGZO, or thiol. It can be formed of organic semiconductor materials such as a fuen oligomer and poly (p-ferylene vinylene).

As a method for forming the active layer 301, for example, amorphous silicon is stacked by plasma CVD, ion doping, amorphous silicon is formed by LPCVD using SiH ₄ gas, and amorphous silicon is formed by solid phase growth. After polysilicon is obtained by crystallization, a method of ion doping by ion implantation can be used. Further, amorphous silicon is formed by LPCVD or PECVD using Si ₂ H ₆ gas or SiH ₄ gas, annealed by a laser such as an excimer laser, and amorphous silicon is crystallized to obtain polysilicon, and then ion doping is performed. Polysilicon is laminated by ion doping (low temperature process), low pressure CVD or LPCVD, and thermally oxidized at 1000 ° C. or higher to form a gate insulating film, and n + polysilicon gate electrode thereon Then, a method (low temperature process method) in which ion doping is performed by ion implantation may be used.

As the gate insulating film 302, a film normally used as a gate insulating film can be used. For example, the gate insulating film 302 is obtained by thermally oxidizing SiO ₂ formed by PECVD, LPCVD, or the like, or a polysilicon film. SiO ₂ or the like can be used.
As the gate electrode 305, what is usually used as a gate electrode can be used. For example, in addition to metals such as aluminum and copper, refractory metals such as titanium, tantalum, and tungsten, polysilicon, high melting point, etc. Examples thereof include metal silicide and polycide.

The thin film transistor may have a single gate structure in which the gate electrode 305 is one, a double gate structure in which the gate electrode 305 is two, and a multi-gate structure in which the gate electrode 305 is three or more. 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 drain electrode 304 and the pixel electrode 307 of the thin film transistor are electrically connected so that the thin film transistor functions as a switching element.

<Pixel electrode>
A pixel electrode (first electrode) 307 is formed on the substrate 300, and patterning is performed as necessary. Examples of the material of the pixel electrode 307 include metal composite oxides such as ITO (indium tin composite oxide), indium zinc composite oxide, and zinc aluminum composite oxide, metal materials such as gold and platinum, these metal oxides, Either a single layer or a laminate of fine particle dispersion films in which fine particles of a metal material are dispersed in an epoxy resin or an acrylic resin can be used.

When the pixel electrode 307 is used as an anode, it is preferable to select a material having a high work function such as ITO. In the case of a so-called bottom emission structure in which light is extracted from below, it is necessary to select a light-transmitting material.
As a formation method of the pixel electrode 307, depending on the material, dry film forming methods such as resistance heating vapor deposition method, electron beam vapor deposition method, reactive vapor deposition method, ion plating method, sputtering method, gravure printing method, screen printing, etc. A wet film forming method such as a method can be used.
As a patterning method of the pixel electrode 307, an existing patterning method such as a mask vapor deposition method, a photolithography method, a wet etching method, or a dry etching method can be used depending on a material or a film forming method. preferable.

<Partition wall>
The partition wall 308 is formed on the substrate 300 so as to partition the light emitting region corresponding to the pixel. The partition 308 formed over the substrate 300 forms an opening for containing a solution in which an organic material is dissolved when a light emitting medium layer is formed over the pixel electrode 307 by a coating method.
As a method for forming the partition wall 308, an inorganic film is uniformly formed on the substrate 300, masked with a resist, and then dry etching is performed. Alternatively, a photosensitive resin is stacked on the substrate 300, and a photolithography method is used. The method of setting it as a predetermined pattern is mentioned.
A preferable height of the partition wall 308 is 0.1 μm to 10 μm, and more preferably about 0.5 μm to 4 μm. This is because if the height of the partition wall 308 is too high, formation and sealing of the counter electrode is hindered, and if it is too low, the adjacent pixels are mixed in color when the light emitting medium layer is formed.

  As the partition material, a photosensitive resin can be suitably used. In this case, either a positive resist or a negative resist may be used, and specific examples include polyimide-based, acrylic resin-based, and novolak resin-based photosensitive resins. Liquid repellency can be imparted to the ink by adding a water repellent as necessary, or by irradiating with plasma or UV after the partition walls are formed.

<Organic EL device>
As the organic EL element, an organic EL element having a structure shown in FIG. 2H, that is, a hole injection layer 202, a hole transport layer 203, an organic light emitting layer 205, and an electron transport layer 206 are sequentially formed on the first electrode 201. It is possible to use a stacked layer in which the second electrode 207 is formed on the electron transport layer 206. A part of the layer formed between the electrodes 201 and 207 can be omitted, and a layer such as a hole blocking layer can be added, and is appropriately selected from known ones.

<Hole injection layer>
The hole injection layer 202 has a function of injecting holes from the first electrode 201. The physical property value of the hole injection layer 202 preferably has a work function equal to or higher than that of the pixel electrode. This is to efficiently inject holes from the pixel electrode. A material having a physical property value of 4.5 eV or more and 6.5 eV or less can be used depending on the material of the pixel electrode. When the pixel electrode is ITO or IZO, it preferably has a physical property value of 5.0 eV or more and 6.0 eV or less.

The specific resistance of the hole injection layer 202 is preferably 1 × 10 ³ to 2 × 10 ⁶ Ω · m, more preferably 5 × 10 ³ to 1 × 10 ⁶ Ω, in a state where the film thickness is 30 nm or more. -M. Further, in the bottom emission structure, emitted light is extracted from the pixel electrode side. Therefore, if the light transmittance is low, the extraction efficiency decreases. For this reason, 75% or more is preferable in the total average of visible light wavelength range, and if it is 85% or more, it can be used suitably.

As a material for forming the hole injection layer 202, for example, a polymer material such as polyaniline, polythiophene, polyvinylcarbazole, a mixture of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid can be used. In addition, a conductive polymer having a conductivity of 10 ⁻² S / cm or more and 10 ⁻⁶ S / cm or less can be preferably used. Since a polymer material can be used in a film forming process by a wet method, it is preferable to use a polymer material when forming the hole injection layer 202. Such a polymer material is dispersed or dissolved in water or a solvent and used as a dispersion or solution.

When an inorganic material is used as the hole transport material, Cu ₂ O, Cr ₂ O ₃ , Mn ₂ O ₃ , FeO _x (x˜0.1), NiO, CoO, Bi ₂ O ₃ , SnO ₂ , ThO ₂ , Nb ₂ O ₅ , Pr ₂ O ₃ , Ag ₂ O, MoO ₂ , ZnO, TiO ₂ , V ₂ O ₅ , Nb ₂ O ₅ , Ta ₂ O ₅ , MoO ₃ , WO ₃ , MnO _2, etc. are used. be able to.

  As a method for forming the hole injection layer 202, the hole injection layer 202 can be collectively formed on the entire display region on the pixel electrode by a simple method such as a slit coating method, a spin coating method, a die coating method, a dipping method, or a spray method. Existing film forming methods such as a relief printing method, a gravure printing method, and a wet film forming method such as a screen printing method can also be used. When the hole injection layer 202 is formed by the above method, ink (liquid material) in which a hole transport material is dissolved in water, an organic solvent, or a mixed solvent thereof is used. As the organic solvent, toluene, xylene, anisole, mesitylene, tetralin, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate and the like can be used. In addition, surfactants, antioxidants, viscosity modifiers, ultraviolet absorbers and the like may be added to the ink. When the hole injection layer 202 is an inorganic material, it can be formed using a dry process 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.

<Hole transport layer>
The hole transport layer 203 has a function of improving the light emission lifetime of the organic EL element by being laminated between the organic light emitting layer 205 and the hole injection layer 202. As a material of the hole transport layer 203, a low molecular or high molecular hole transport material can be preferably used. For example, polyaniline derivative, oligoaniline derivative, quinonediimine derivative, polythiophene derivative, polyvinylcarbazole (PVK) derivative, pyrrole derivative, aromatic amine, (triphenylamine) dimer derivative (TPD), (α-naphthyldiphenylamine) dimer (α- NPD), [(triphenylamine) dimer] spirodimer (Spiro-TAD), triarylamines such as TPTE, TPT1, 4,4 ′, 4 ″ -tris [3-methylphenyl (phenyl) amino] tri Starburst amines such as phenylamine (m-MTDATA), 4,4 ′, 4 ″ -tris [1-naphthyl (phenyl) amino] triphenylamine (1-TNATA) and 5,5′-α-bis -{4- [bis (4-methylphenyl) amino] phenyl} -2,2 ': 5', Oligothiophenes such as' -α terthiophene (BMA-3T), aromatic amine-containing polymers, aromatic diamine-containing polymers, fluorene-containing aromatic amine polymers can be used, but are not limited thereto. It is not a thing.
In addition, said TPTE and TPT1 can be represented by the following chemical formula 1 and chemical formula 2.

  Moreover, what mix | blended the polymer with said material can be used as a hole transport material, As a polymer, for example, a polycarbonate, a polystyrene, a polymethylmethacrylate, a polypropylene, a polyethersulfone, a cycloolefin polymer, a polyarylate, Examples thereof include polyamide, polyethylene terephthalate, and polyethylene naphthalate. By blending the polymer, the film quality of the hole transport layer 203 is stabilized and the film formability is improved.

  These organic materials are dissolved or stably dispersed in a solvent to form an organic hole transport layer ink. Examples of the solvent for dissolving or dispersing the organic hole transport layer material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, or a mixed solvent thereof. Among them, aromatic organic solvents such as toluene, xylene, and anisole are preferable from the viewpoint of solubility of the organic hole transport layer material. In addition, a surfactant, an antioxidant, a viscosity modifier, an ultraviolet absorber, and the like may be added to the organic hole transport layer ink as necessary.

As these hole transport layer materials, it is preferable to select a material having a work function equal to or higher than that of the hole injection layer 202, and it is more preferable that the work function is equal to or lower than that of the organic light emitting layer 205. This is because an unnecessary injection barrier is not formed when carriers are injected from the hole injection layer 202 to the organic light emitting layer 205. Further, in order to obtain the effect of confining charges that could not contribute to light emission from the organic light emitting layer 205, the band gap is preferably 3.0 eV or more, more preferably 3.5 eV or more.
As a method of forming the hole transport layer 203, it can be formed in a lump by a simple method such as a slit coat method, a spin coat method, a die coat method, a dipping method, or a spray method over the entire display region on the pixel electrode. Existing film forming methods such as a relief printing method, an ink jet method, a nozzle printing method, a gravure printing method, and a wet film forming method such as a screen printing method can also be used.

<Organic light emitting layer>
The organic light emitting layer 205 is a layer that emits light by passing a current. When the display light emitted from the organic light emitting layer 205 is monochromatic, it is formed so as to cover the hole transport layer 203. However, when obtaining multicolor display light, patterning is preferably performed as necessary. .
Examples of the organic light emitting material for forming the organic light emitting layer 205 include, for example, coumarin, perylene, pyran, anthrone, porphyrene, quinacridone, N, N′-dialkyl-substituted quinacridone, naphthalimide, N, N ′. -Diaryl substituted pyrrolopyrrole, iridium complex and other luminescent dyes dispersed in polymers such as polystyrene, polymethyl methacrylate, polyvinyl carbazole, polyarylene, polyarylene vinylene and polyfluorene Examples include, but are not limited to, molecular materials. These organic light emitting materials are dissolved or stably dispersed in a solvent to form an organic light emitting ink.

  Examples of the solvent for dissolving or dispersing the organic light-emitting material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or a mixed solvent thereof. Among them, aromatic organic solvents such as toluene, xylene, and anisole are preferable from the viewpoint of the solubility of the organic light emitting material. Moreover, surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. may be added to organic luminescent ink as needed.

  In addition to the polymer materials described above, 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolato) aluminum complex, tris (4-methyl) -8-quinolate) aluminum complex, bis (8-quinolate) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolate) aluminum complex, tris (4-methyl-5-cyano-8-quinolate) Aluminum complex, bis (2-methyl-5-trifluoromethyl-8-quinolinolato) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolato) [4- (4-Cyanophenyl) phenolate] aluminum complex, tris (8-quino) Norato) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, poly-2,5-diheptyloxy-para-phenylene vinylene A low molecular weight light emitting material such as can be used.

As a method for forming the organic light emitting layer 205, a wet film formation method is preferable. For patterning film formation, an existing film formation method such as an ink jet method, a nozzle printing method, a relief printing method, a gravure printing method, a screen printing method, or the like is used. A membrane method can be used.
In the case where the organic light emitting layer 205 is not required to be patterned on a monochrome display panel, lighting panel, or the like, a slit coating method, a spin coating method, a die coating method, a dipping method, or a spray method is applied to the entire display region on the pixel electrode. It is possible to form all together by a simple method such as

<Electron injection layer>
After the organic light emitting layer 205 is formed, a hole blocking layer, an electron injection layer, and the like can be formed. The material used for the hole blocking layer and the electron injection layer may be any material that is generally used as an electron transporting material, such as triazole, oxazole, oxadiazole, silole, and boron. A film can be formed by a vacuum deposition method using a material, an alkali metal such as lithium fluoride or lithium oxide, or a salt or oxide of an alkaline earth metal. In addition, these electron transport materials or those obtained by mixing these electron transport materials in polymers such as polystyrene, polymethyl methacrylate, and polyvinyl carbazole are toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl A film can be formed by a printing method by dissolving or dispersing in alcohol, ethyl acetate, butyl acetate, water or the like alone or in a mixed solvent to form an electron injection coating solution.

<Poor solvent>
The poor solvent 204 used in the present invention is a solvent having low solubility in the lower organic layer. Specifically, the solubility with respect to the organic material which forms the lower organic layer is 1 mass% or less. Furthermore, the solubility is more preferably 0.1% by mass or less. For example, when the organic light emitting layer 205 is formed on the hole transport layer 203, the solvent has low solubility in the hole transport layer material. When the hole injection layer 202 is further formed under the hole transport layer 203, the solubility to the hole injection layer 202 may need to be low.

Examples of the poor solvent used in the present invention include alcohols, fluorine-based solvents, and the like, specifically, methanol, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl. 2-propanol, cyclohexanol, cyclopentanol, 1, 1, 1, 2, 2, 3, 4, 5, 5, 5-decafluoro-3-methoxy-4- (trifluoromethyl) -pentane, ethyl Nonafluoroisobutyl ether, ethyl nonafluorobutyl ether and the like can be mentioned, but are not limited thereto.
As the process of applying the poor solvent, an existing application process can be applied, and examples thereof include a spin coat method, a dipping method, a spray method, a nozzle print method, and an ink jet method.

<Counter electrode>
Next, a counter electrode (second electrode 207) is formed. When the counter electrode is a cathode, a substance having a high electron injection efficiency into the organic light emitting layer 205 and a low work function is used. Specifically, a single metal such as Mg, Al, or Yb is used, or a compound such as Li, oxidized Li, or LiF is sandwiched by about 1 nm at the interface contacting the light emitting medium layer, and Al or Cu having high stability and conductivity is placed. You may use it, laminating | stacking. Alternatively, in order to achieve both electron injection efficiency and stability, one or more metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function and stable Ag, Al An alloy system with a metal element such as Cu or Cu may be used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used.
As a method for forming the counter electrode, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on the material.

<Sealing>
As an organic EL display device, it is possible to emit light by sandwiching a light emitting material between electrodes and passing an electric current. However, since an organic light emitting material is easily deteriorated by moisture or oxygen in the atmosphere, it is usually externally connected. Seal for blocking.
<Can sealing>
For sealing, for example, a sealing can may be bonded onto the substrate. The sealing can needs to be low in gas permeability and can be made of glass or metal such as stainless steel. As the adhesive, a UV curable adhesive is preferable.

<Passivation layer>
In order to protect the organic EL element from oxygen and moisture from the outside, a passivation layer may be formed on the counter electrode. The passivation layer includes metal oxides such as silicon oxide and aluminum oxide, metal fluorides such as aluminum fluoride and magnesium fluoride, metal nitrides such as silicon nitride, aluminum nitride and carbon nitride, and metal acids such as silicon oxynitride. A laminated film of a metal carbide such as nitride or silicon carbide, and a polymer resin film such as an acrylic resin, an epoxy resin, a silicone resin, or a polyester resin may be used as required. In view of the above, it is preferable to use silicon oxide, silicon oxynitride, or silicon nitride. Furthermore, by using a laminated film or a gradient film having a variable film density, a film having both step coverage and barrier properties can be obtained. .

As a method for forming the passivation layer, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, or a CVD method can be used depending on the material. The CVD method is preferably used because the film density and film composition can be easily varied depending on the step coverage surface and the film formation conditions.
As the CVD method, a thermal CVD method, a plasma CVD method, a catalytic CVD method, a VUV-CVD method, or the like can be used. In addition, as a reaction gas in the CVD method, a gas such as N ₂ , O ₂ , NH ₃ , H ₂ , N ₂ O is added to an organic silicon compound such as monosilane, hexamethyldisilazane (HMDS), or tetraethoxysilane. The film density may be changed by changing the gas flow rate of silane or the like, or the plasma power, if necessary. Hydrogen or carbon may be added to the film by the reactive gas used. It can also be contained.
The thickness of the passivation layer is preferably 5 μm or less, more preferably 1 μm or less.

<Sealing body>
For sealing, a resin layer may be provided on the sealing material and bonded 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, quartz, and moisture resistant film. Examples of moisture resistant films include films formed by CVD of SiOx on both sides of a plastic substrate, films with low permeability and water-absorbing films, or polymer films coated with a water-absorbing agent. The water vapor transmission rate of the film is preferably 10 −6 g / m ² / day or less.

  Examples of the material for the resin layer include a photo-curing adhesive resin, a thermosetting adhesive resin, a two-component curable adhesive resin, and an ethylene ethyl acrylate (EEA) made of epoxy resin, acrylic resin, silicone resin, etc. Examples thereof include acrylic resins such as polymers, 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.
The thickness of the resin layer formed on the sealing material is arbitrarily determined depending on the size and shape of the organic EL display device to be sealed, but is preferably about 5 to 500 μm. In addition, although formed as a resin layer on the sealing material here, it can also be formed directly on the organic EL display device side.

  Finally, the organic EL display device 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.

Examples of the present invention will be described below.
[Example 1]
As the substrate, an active matrix substrate including a thin film transistor (TFT) functioning as a switching element provided on a support and a pixel electrode formed thereabove was used. A substrate having a size of 200 mm × 200 mm, a diagonal of 5 inches, and a pixel number of 320 × 240 is arranged in the center. One pixel consists of three sub-pixels, but this time, a green monochromatic light-emitting panel was fabricated by applying a green light-emitting material to all three sub-pixels. ITO was used as the pixel electrode. Then, a partition wall was formed in such a shape as to cover the end portion of the pixel electrode provided on the active matrix substrate and partition the pixel.
The partition walls were formed using a positive resist with a thickness of 3 μm on the entire surface of the substrate by a spin coater method, and then patterned using a photolithography method to form the partition walls.

Next, after forming a mixture of poly (3,4-ethylenedioxythiophene) and polystyrene sulfonic acid with a film thickness of 60 nm by a nozzle printing method as a hole injection layer, a hole transport material is formed as a hole transport layer. It was formed with a film thickness of 20 nm by nozzle printing using an ink in which TPT1 was dissolved in toluene.
Next, after 2-methyl-1-propanol, which is a poor solvent for TPT1, was applied by a spray coating method, an organic light emitting layer was formed before 2-methyl-1-propanol was evaporated. 2,2 ', 2 "-(1,3,5-Benzenetriyl) tris (1-phenyl-1H-benzimidazole) (TPBi) as the host material and tris (2- (p-tolyl) pyridine as the doping material ) Iridium III (Ir (mppy) 3) was mixed at a ratio of 94: 6 and applied by nozzle printing using ink dissolved in toluene, and the film thickness after drying the solvent was 60 nm. .

Next, after forming TPBi with a film thickness of 20 nm by the vacuum evaporation method as an electron carrying layer, 0.5 nm of LiF was formed by vacuum evaporation as the second electrode, and then an aluminum film was formed by 300 nm. And in order to protect these organic electroluminescent structures from external oxygen and a water | moisture content, it sealed and sealed using the glass cap and the adhesive agent.
When the active matrix driving type organic EL display device thus obtained was driven, green light emission was obtained, and the driving could be performed satisfactorily. From the panel luminance measurement when this panel was made to emit light, the characteristic of the subpixel was an efficiency of 32 cd / A.

[Example 2]
The active matrix driving type organic EL display is carried out in the same manner as in Example 1 except that the hole transporting layer is TTP1, which is a hole transporting material, mixed with polystyrene in a ratio of 1: 1 and dissolved in toluene. A device was made.
When the obtained active matrix driving type organic EL display device was driven, green light emission was obtained, and the driving could be performed satisfactorily. From the panel luminance measurement when this panel was made to emit light, the characteristic of the subpixel was an efficiency of 35 cd / A.

[Comparative Example 1]
An active matrix drive type organic EL display device was produced in the same manner as in Example 1 except that the poor solvent was not applied before the organic light emitting layer was applied.
When the obtained active matrix drive type organic EL display device was driven, green light emission was obtained. From the panel brightness measurement when this panel was made to emit light, the characteristic of the subpixel was an efficiency of 15 cd / A, and the efficiency was greatly reduced as compared with Example 2. This is probably because the hole-transporting layer was dissolved and the organic light-emitting layer was mixed when the organic light-emitting layer was applied.

DESCRIPTION OF SYMBOLS 100 ... Organic EL display panel 101 ... Pixel 102 ... Subpixel 200 ... Substrate 201 ... First electrode 202 ... Hole injection layer 203 ... Hole transport layer 204 ... Poor solvent 205a ... Organic light emitting material 205 ... Organic light emitting layer 206 ... Electron Transport layer 207 ... second electrode 300 ... TFT substrate 301 ... active layer 302 ... gate insulating film 303 ... source electrode 304 ... drain electrode 305 ... gate electrode 306 ... insulating film 307 ... pixel electrode (first electrode)
308 ... partition wall 309 ... scanning line

Claims (11)

A first electrode formed on a substrate; a luminescent medium layer formed on the first electrode; and a second electrode facing the first electrode through the luminescent medium layer, the luminescent medium A method for producing an organic electroluminescence device, wherein the layer comprises an upper organic layer, and a lower organic layer formed between the upper organic layer and the first electrode,
After applying a poor solvent having low solubility with respect to the organic material forming the lower organic layer on the lower organic layer, the poor solvent is used as the organic material forming the upper organic layer on the lower organic layer. A method for producing an organic electroluminescence device, wherein the upper organic layer is formed by coating before evaporation.   The method of manufacturing an organic electroluminescence element according to claim 1, wherein the lower organic layer is a hole transport layer.   The method for producing an organic electroluminescent element according to claim 2, wherein the hole transport layer is made of an organic material containing a low molecular material.   The method for manufacturing an organic electroluminescence element according to claim 3, wherein the material forming the hole transport layer includes a polymer material.   The method for producing an organic electroluminescent element according to claim 1, wherein the lower organic layer is an organic electron transporting layer.   The organic material ink for forming the upper organic layer contains a solvent, and the boiling point of the solvent is 160 ° C. or lower. The organic electroluminescent element according to claim 1, Production method.   The organic electroluminescence according to any one of claims 1 to 6, wherein the vapor pressure of the poor solvent is lower than the vapor pressure of the solvent contained in the organic material ink for forming the upper organic layer. Device manufacturing method.   The organic material for forming the upper organic layer is applied on the lower organic layer in a non-contact manner. The method for producing an organic electroluminescent element according to claim 1, wherein the organic material is applied in a non-contact manner.   An organic electroluminescence device comprising an organic electroluminescence panel comprising a large number of organic electroluminescence elements produced by the method according to claim 1.   The organic electroluminescence device according to claim 9, wherein the organic electroluminescence panel is a display panel. The organic electroluminescence device according to claim 9, wherein the organic electroluminescence panel is a lighting panel.

Images