WO2013015198A1

WO2013015198A1 - Method for producing organic semiconductor element and vacuum drying device

Info

Publication number: WO2013015198A1
Application number: PCT/JP2012/068359
Authority: WO
Inventors: 直井　太郎; 田中　洋平; 拓也畠山
Original assignee: パイオニア株式会社; 三菱化学株式会社
Priority date: 2011-07-26
Filing date: 2012-07-19
Publication date: 2013-01-31
Also published as: JPWO2013015198A1

Abstract

The present invention is a method for producing an organic semiconductor element having plurality of organic semiconductor layers layered between a pair of a positive electrode and a negative electrode facing each other on a substrate. The production method includes a coating step for forming an organic semiconductor coating liquid film by wet deposition from an organic semiconductor coating liquid including a solute as an organic semiconductor layer and a solvent for dispersing the solute, and a drying step for drying the organic semiconductor coating liquid film inside a vacuum chamber. In the drying step, the interior of the vacuum chamber is exhausted from atmosphere pressure to a pressure of 60 Pa at an exhausting speed of 0.5 seconds to 10 seconds inclusive.

Description

Organic semiconductor device manufacturing method and vacuum drying apparatus

The present invention relates to a method for manufacturing an organic semiconductor element and a vacuum drying apparatus.

In the manufacturing method of an organic electroluminescence (EL) device including a plurality of organic semiconductor layers made of an organic compound having a charge transporting property and including a light emitting layer in the organic semiconductor layer, establishment and maintenance of a production method with lower cost is achieved. In order to improve the property, the use of forming a film by wet coating is increasing. In addition to organic EL displays and organic EL lighting using organic EL elements, in the field of organic TFTs and organic solar cells using organic semiconductor layers, a coating solution such as a resist solution is applied to a transparent substrate such as glass and then dried. However, there is an increasing use of a coating process for forming a desired pattern by photolithography or the like.

Examples of wet coating methods for organic coating solutions for organic semiconductor layers include spin, dip, roll, and ink jet methods. Before the pattern formation process after coating, it is necessary to execute a drying process for drying the coating film on the substrate. In the drying process, the substrate coated with the coating liquid is heated and dried using an oven or a hot plate.

Since the time required for heat drying is long, in recent years, a vacuum drying apparatus has been used in a method for manufacturing an organic EL element in order to shorten the process time. (See Patent Documents 1 to 12)

Japanese Patent Laid-Open No. 11-54272 International Publication WO2000 / 059267 JP 2002-289352 A JP 2004-1227897 A JP 2004-223354 A JP 2005-259720 A JP 2006-68598 A JP 2008-84566 A JP 2008-226685 A JP 2005-310709 A JP 2009-181932 A JP 2010-80167 A

In the conventional vacuum drying apparatus, the evaporation rate and the coating film are exhausted to about the vapor pressure at which the evaporation rate of the solvent of the organic semiconductor coating liquid is increased, and thereafter, the evaporation rate is reduced and gradually evaporated. Many of them aim to improve both the flatness and smoothness.

However, in a conventional vacuum drying apparatus, for example, when forming a light emitting layer of an organic EL element made of a low molecular weight host material and a guest material each having different solubility in a coating solvent, if the light emitting layer is slowly dried in vacuum, a plurality of low molecular weight materials are obtained. There is a problem that a plurality of low molecules cannot be uniformly dispersed in a solid content film in which precipitation starts from molecules that are more likely to precipitate, and the solvent is eliminated after drying. Further, when the exhaust speed for vacuum drying of the coating liquid film is slow, there is a problem that convection is generated on the film and the drying unevenness in the finish cannot be sufficiently suppressed, such as partial drying.

Furthermore, when a bank section is formed for a low molecular weight material coating solution with low viscosity and the vacuum drying method is applied to wet film formation, a meniscus remains on the outermost peripheral edge of the coating film, resulting in a flat coating film. There was also a problem that the degree decreased.

The present invention has been made in view of such circumstances, and a method for manufacturing an organic semiconductor element capable of improving the state after drying of an organic film by a wet coating method film forming method and maintaining the luminous efficiency after manufacturing, and An object is to provide a vacuum drying apparatus.

The method for producing an organic semiconductor element according to claim 1 is a method for producing an organic semiconductor element having a plurality of organic semiconductor layers laminated on a substrate between a pair of opposing anodes and cathodes. The manufacturing method includes a coating step of forming an organic semiconductor coating liquid film by a wet film-forming method from an organic semiconductor coating liquid containing a solute to be the organic semiconductor layer and a solvent for dispersing the solute, and the organic semiconductor A drying step of drying the coating liquid film in a vacuum chamber; and a baking step of baking the organic semiconductor coating liquid film. This method for producing an organic semiconductor element is characterized in that, in the drying step in the method, the inside of the vacuum chamber is evacuated from an atmospheric pressure to an atmospheric pressure of 60 Pa at an evacuation speed of 0.5 seconds or more and 10 seconds or less.

The vacuum drying apparatus according to claim 8, wherein an organic semiconductor coating liquid film formed from an organic semiconductor coating liquid containing a solute serving as an organic semiconductor layer and a solvent for dispersing the solute is dried in vacuum. Device. Such a vacuum drying apparatus includes a vacuum chamber that houses a substrate carrying the organic semiconductor coating liquid film in an internal space, an exhaust device that exhausts gas from the internal space of the vacuum chamber to the outside, and controls the exhaust device. And an exhaust controller that exhausts the interior of the vacuum chamber from atmospheric pressure to 60 Pa at an exhaust speed of 0.5 seconds to 10 seconds, and dries the organic semiconductor coating liquid film.

According to the present invention, by utilizing rapid decompression by rapid exhaust, for example, even when a light emitting layer composed of a low molecular weight host material and a guest material having different solubility in a coating solution solvent is formed, the low molecular weight material is uniform. It is possible to form a film dispersed in an amorphous state, and it can be dried as a flat film having a narrow meniscus width without causing aggregation of contained particles and the like, so that the luminous efficiency of the obtained organic EL element can be increased. . In addition, since an optimal dry state can be automatically realized, for example, it is possible to suppress the occurrence of a defective phenomenon such as an organic semiconductor device that increases due to a residual solvent.

It is a schematic block diagram which shows the laminated structure of an organic EL element. It is process drawing which shows the manufacturing method of the organic EL element of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process in this embodiment. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic structure sectional view showing a vacuum drying device of an embodiment by the present invention. It is a graph which shows the pressure time-dependent change in the vacuum chamber of the vacuum dryer of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. It is a schematic sectional drawing which shows the board | substrate in the organic EL element manufacturing process of embodiment by this invention. The graph (a) which shows the film thickness change of the light emitting layer of the organic EL element after the drying process of the organic EL element manufacturing method of embodiment by this invention, The microscope picture which shows the light emission state of the organic EL element obtained by the said method ( It is a top view (b) which shows the light emission state of c) and the said organic EL element. The graph (a) which shows the film thickness change of the light emitting layer of the organic EL element after the drying process of the organic EL element manufacturing method for a comparison, The microscope picture (c) which shows the light emission state of the organic EL element obtained by the said method It is a top view (b) which shows the light emission state of the said organic EL element.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

--- Organic EL device--
As shown in FIG. 1, an example of the organic EL element of the present embodiment includes a transparent anode 2, a hole injection layer 3, a hole transport layer 4, and a light emitting layer 5 in this order on a transparent substrate 1 such as glass. , A hole blocking layer 6, an electron transport layer 7, an electron injection layer 8, and a cathode 9 made of a metal are laminated. The hole injection layer 3, the hole transport layer 4, the light emitting layer 5, the hole blocking layer 6, and the electron transport layer 7 are organic semiconductor layers. That is, in the organic EL element, a plurality of organic semiconductor layers stacked between a pair of opposing anodes and cathodes are formed as a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, Includes an electron injection layer. Components such as the organic semiconductor layer will be described later.

In addition to the structure of anode 2 / hole injection layer 3 / hole transport layer 4 / light emitting layer 5 / hole blocking layer 6 / electron transport layer 7 / electron injection layer 8 / cathode 9 / shown in FIG. However, the anode 2 / hole injection layer 3 / light emitting layer 5 / electron transport layer 7 / electron injection layer 8 / cathode 9 / hole transport layer 4 and hole blocking layer 6 are omitted, although not shown, The anode 2 / hole transport layer 4 / light emitting layer 5 / electron transport layer 7 / electron injection layer 8 / cathode 9 / hole injection layer 3 and hole blocking layer 6 are omitted, and although not shown, the anode 2 A configuration in which the hole injection layer 3, the hole transport layer 4, and the hole blocking layer 6 of / light emitting layer 5 / electron transport layer 7 / electron injection layer 8 / cathode 9 / is omitted is also included in the present invention. Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. In any case, the present invention is not limited to these stacked structures, and includes a structure including at least a light-emitting layer or a charge transport layer that can also be used.

--substrate--
As the substrate 1, a quartz or glass plate, a metal plate or a metal foil, a resin substrate to be bent, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic EL element may be deteriorated by the outside air that has passed through the substrate. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

--Anode and cathode--
The anode 2 that supplies holes to the layers up to the light emitting layer is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, or a metal such as indium and / or tin or zinc oxide (ITO or IZO). It is composed of an oxide, a metal halide such as copper iodide, carbon black, or a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.

The anode is usually formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming an anode using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, or conductive polymer fine powder, an appropriate binder resin solution is used. The anode can also be formed by dispersing and coating the substrate. Further, in the case of a conductive polymer, a thin film can be directly formed on the substrate by electrolytic polymerization, or the anode can be formed by applying a conductive polymer on the substrate.

The anode usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.

The thickness of the anode depends on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. If it may be opaque, the thickness of the anode is arbitrary, and the anode may be integrated with the substrate 1. Furthermore, different conductive materials may be laminated.

The surface of the anode is treated with ultraviolet (UV) / ozone, oxygen plasma, or argon plasma for the purpose of removing impurities adhering to the anode and adjusting the ionization potential to improve hole injection. Is preferred.

As a material of the cathode 9 for supplying electrons to the layers up to the light emitting layer, a material used for the anode can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable. A suitable metal such as tin, magnesium, indium, calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

In addition, only 1 type may be used for the material of the

cathode

9, and 2 or more types may be used together by arbitrary combinations and a ratio. The thickness of the cathode is usually the same as that of the anode.

Further, for the purpose of protecting the cathode made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

Furthermore, when the anode and the cathode are on the light emission extraction side, the material and film thickness are selected so as to be transparent or translucent. In particular, it is preferable to select a material in which either one or both of the anode and the cathode has a transmittance of at least 10% at the emission wavelength obtained from the organic light emitting material. These electrodes may be patterned as necessary.

--- Organic semiconductor layer--
* Hole injection layer *
The hole injection layer 3 is preferably a layer containing an electron accepting compound.

The film thickness of the hole injection layer is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less. The hole injection layer is preferably formed by a wet film formation method from the viewpoint of reducing dark spots.

When forming a hole injection layer by a wet film formation method, the material for forming the hole injection layer is usually mixed with an appropriate solvent (a solvent for the hole injection layer) to form a composition for film formation (hole An injection layer forming composition) is prepared, and this hole injection layer forming composition is coated on the anode by an appropriate technique to form a film and dried to form a hole injection layer.

The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as a constituent material of the hole injection layer. Examples of the solvent include, but are not limited to, ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents, and the like.
Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether acetate (PGMEA), 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2 -Aromatic toluene such as methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and the like.

Examples of ester solvents include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.

Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylpropylphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene. Can be mentioned.

Examples of the amide solvent include N, N-dimethylformamide and N, N-dimethylacetamide. In addition, dimethyl sulfoxide and the like can also be used. These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.

As long as the hole transporting compound is a compound having a hole transporting property that is usually used in a hole injection layer of an organic EL element, a polymer or the like may be a monomer or the like. Although it may be a low molecular compound, it is preferably a low molecular compound.

The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode to the hole injection layer. Examples of hole transporting compounds include aromatic amine derivatives, phthalocyanine derivatives typified by phthalocyanine copper (CuPc), porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, and tertiary amines linked by fluorene groups. Examples thereof include compounds, hydrazone derivatives, silazane derivatives, silanamine derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, and carbon.

Here, the derivative includes, for example, an aromatic amine derivative, and includes an aromatic amine itself and a compound having an aromatic amine as a main skeleton. It may be a body.

The hole transporting compound used as the material for the hole injection layer may contain any one of these compounds alone, or may contain two or more. In the case of containing two or more kinds of hole transporting compounds, the combination is arbitrary, but one or more kinds of aromatic tertiary amine polymer compounds and one or two kinds of other hole transporting compounds. The above can also be used together. From the viewpoints of amorphousness and visible light transmittance, an aromatic amine compound is preferable for the hole injection layer, and an aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine. Specific examples include those described in the pamphlet of International Publication No. 2005/089024.

As the hole transporting compound, a conductive polymer (PEDOT / PSS) obtained by polymerizing 3,4-ethylenedioxythiophene, which is a derivative of polythiophene, in high molecular weight polystyrene sulfonic acid is also preferable. Moreover, the end of this polymer may be capped with methacrylate or the like.

The concentration of the hole transporting compound in the composition for forming a hole injection layer is usually 0.01% by weight or more, preferably 0.1% by weight or more, and more preferably 0.00% by weight in terms of film thickness uniformity. 5% by weight or more, usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If this concentration is too high, film thickness unevenness may occur, and if it is too low, defects may occur in the formed hole injection layer.

The composition for forming a hole injection layer preferably contains an electron-accepting compound, and may further contain other components in addition to the hole-transporting compound and the electron-accepting compound. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, and coating property improving agents. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and ratios.

* Hole transport layer *
The material of the hole transport layer 4 may be any material that has been conventionally used as a constituent material of the hole transport layer. For example, the hole transport layer is exemplified as the hole transport compound used in the above-described hole injection layer. Things. In addition, arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silole derivatives, oligothiophene derivatives, condensed polycyclic aromatics Group derivatives, metal complexes and the like. Also, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophenes Derivatives, poly (p-phenylene vinylene) derivatives, and the like. These may be any of an alternating copolymer, a random polymer, a block polymer, or a graft copolymer. Further, it may be a polymer having a branched main chain and three or more terminal portions, or a so-called dendrimer.

Specific examples of the material for the hole transport layer 4 include polyarylene derivatives described in JP-A-2008-98619.

When the hole transport layer is formed by a wet film formation method, a composition for forming a hole transport layer is prepared in the same manner as the formation of the hole injection layer, followed by drying after the wet film formation.

In addition to the hole transporting compound, the hole transporting layer forming composition contains a solvent. The solvent used is the same as that used for the composition for forming the hole injection layer. The film forming conditions, the drying conditions, and the like are the same as in the case of forming the hole injection layer.

The hole transport layer may contain various light emitting materials, electron transport compounds, binder resins, coatability improvers and the like in addition to the hole transport compound.

The film thickness of the hole transport layer is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less.

The hole transport layer may be formed by a vacuum deposition method or a wet film formation method, but is preferably formed by a wet film formation method from the viewpoint of reducing dark spots.

The hole transport layer 4 may be a layer containing a polymer obtained by crosslinking an amine-based crosslinking compound.

* Light emitting layer *
The light emitting layer 5 contains at least a material having a light emitting property (light emitting material) as a constituent material, and preferably a compound having a hole transporting property (hole transporting compound) or an electron transport. A compound (electron transporting compound) having the following properties: A light emitting material may be used as a dopant material, and a hole transporting compound, an electron transporting compound, or the like may be used as a host material. There is no particular limitation on the light-emitting material, and a material that emits light at a desired light emission wavelength and has favorable light emission efficiency may be used. In addition, when forming a light emitting layer with a wet film-forming method, it is preferable to use a low molecular weight material in any case.

Any known material can be applied as the light emitting material. For example, a fluorescent material or a phosphorescent material may be used, but a phosphorescent material is preferred from the viewpoint of internal quantum efficiency. Alternatively, blue may be used in combination, such as using a fluorescent material, and green and red using a phosphorescent material.

For the purpose of improving the solubility in a solvent, it is preferable to reduce the symmetry and rigidity of the molecule of the luminescent material, or to introduce a lipophilic substituent such as an alkyl group.

Examples of fluorescent light emitting materials (blue fluorescent dyes) that emit blue light include naphthalene, perylene, pyrene, chrysene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof.

Examples of the fluorescent light-emitting material (green fluorescent dye) that emits green light include aluminum complexes such as quinacridone derivatives, coumarin derivatives, and Alq3 (tris (8-hydroxy-quinoline) aluminum).

Examples of the fluorescent light emitting material (yellow fluorescent dye) that emits yellow light include rubrene and perimidone derivatives.

Examples of fluorescent materials that emit red light (red fluorescent dyes) include DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, Examples include benzothioxanthene derivatives and azabenzothioxanthene.

As the phosphorescent material, for example, a long-period type periodic table (hereinafter, unless otherwise specified, the term “periodic table” refers to a long-period type periodic table) selected from Group 7 to 11 And an organometallic complex containing a metal. Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. As the ligand of the complex, a ligand in which a (hetero) aryl group such as a (hetero) arylpyridine ligand or a (hetero) arylpyrazole ligand and a pyridine, pyrazole, phenanthroline, or the like is connected is preferable. A pyridine ligand and a phenylpyrazole ligand are preferable. Here, (hetero) aryl represents an aryl group or a heteroaryl group.

Specific examples of phosphorescent materials include tris (2-phenylpyridine) iridium (Ir (ppy) 3), tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, and bis (2-phenylpyridine). ) Platinum, tris (2-phenylpyridine) osmium, tris (2-phenylpyridine) rhenium, octaethylplatinum porphyrin, octaphenylplatinum porphyrin, octaethylpalladium porphyrin, octaphenylpalladium porphyrin, and the like.

The molecular weight of the compound used as the light emitting material is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, preferably 200 or more, more preferably 300 or more, still more preferably. The range is 400 or more. If the molecular weight of the light-emitting material is too small, the heat resistance is significantly reduced, gas is generated, the film quality is deteriorated when the film is formed, or the morphology of the organic EL element is changed due to migration or the like. There is a case to do. On the other hand, if the molecular weight of the luminescent material is too large, it tends to be difficult to purify the organic compound, or it may take time to dissolve in the solvent.

In addition, any 1 type may be used for a luminescent material, and 2 or more types may be used together by arbitrary combinations and a ratio. The ratio of the light emitting material in the light emitting layer is usually 0.05% by weight or more and usually 35% by weight or less. If the amount of the light emitting material is too small, uneven light emission may occur. If the amount is too large, the light emission efficiency may be reduced. In addition, when using together 2 or more types of luminescent material, it is made for the total content of these to be contained in the said range. The component having the highest content in the light emitting layer is called a host material, and the component having a smaller content is called a guest material. Therefore, at least two kinds of solid contents (host material and guest material) to be the light emitting layer can be prepared by being dispersed or dissolved in a solvent as a solute in the light emitting layer coating liquid.

The light emitting layer may contain a hole transporting compound as a constituent material. Here, among the hole transporting compounds, examples of the low molecular weight hole transporting compound include various compounds exemplified as the hole transporting compound in the hole injection layer 3 described above, for example, Two or more condensed aromatic rings containing two or more tertiary amines represented by 4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) are attached to the nitrogen atom. Aromatic amine compounds having a starburst structure (Journal ジアミン of ジアミン Luminescence, such as substituted aromatic diamines (Japanese Patent Laid-open No. Hei 5-234681), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine) 1997, Vol.72-74, pp.985), aromatic amine compounds consisting of tetramers of triphenylamine (Chemical Communications, 1996, pp.2175), 2,2 ′, 7,7′-tetrakis- ( Diphenylamino) Examples include spiro compounds such as -9,9'-spirobifluorene (Synthetic Metals, 1997, Vol. 91, pp. 209).

In addition, in a light emitting layer, only 1 type may be used for a hole transportable compound, and it may use 2 or more types together by arbitrary combinations and a ratio.

The proportion of the hole transporting compound in the light emitting layer is usually 0.1% by weight or more and usually 65% by weight or less. If the amount of the hole transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of hole transportable compounds, it is made for the total content of these to be contained in the said range.

The light emitting layer may contain an electron transporting compound as a constituent material. Here, among the electron transporting compounds, examples of low molecular weight electron transporting compounds include 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND), 2,5, -Bis (6 '-(2', 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), bathophenanthroline (BPhen), 2,9-dimethyl-4,7 Diphenyl-1,10-phenanthroline (BCP, bathocuproin), 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 4 , 4′-bis (9H-carbazol-9-yl) biphenyl (CBP), etc. In the light emitting layer, only one kind of electron transporting compound may be used, or two or more kinds. It may be used together in any combination and in any ratio.

The proportion of the electron transporting compound in the light emitting layer is usually 0.1% by weight or more and usually 65% by weight or less. If the amount of the electron transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of electron transport compounds, it is made for the total content of these to be contained in the said range.

The light emitting layer is preferably formed in the bank partition region, particularly by an ink jet method. In this case, the light emitting layer material is dissolved in an appropriate solvent to prepare a light emitting layer forming composition, and a film is formed using the composition.

As the solvent for the light emitting layer to be contained in the composition for forming a light emitting layer for forming the light emitting layer by a wet film forming method, any solvent can be used as long as the light emitting layer can be formed. Suitable examples of the solvent for the light emitting layer are the same as those described for the composition for forming a hole injection layer.

The ratio of the light emitting layer solvent to the light emitting layer forming composition for forming the light emitting layer is usually 0.01% by weight or more and usually 70% by weight or less. In addition, when using 2 or more types of solvents mixed as a solvent for light emitting layers, it is made for the sum total of these solvents to satisfy | fill this range.

After forming the light emitting layer forming composition into a wet film, the obtained coating film is dried and the solvent is removed to form a light emitting layer. The light emitting layer is similar to the coating method described in the formation of the hole injection layer, but is preferably formed by a wet film forming method from the viewpoint of reducing dark spots.

The film thickness of the light emitting layer is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. If the light emitting layer is too thin, defects may occur in the film, and if it is too thick, the driving voltage may increase.

* Hole blocking layer *
The hole blocking layer 6 is a layer laminated on the light emitting layer so as to be in contact with the cathode side interface of the light emitting layer. The hole blocking layer has a role of blocking holes moving from the anode from reaching the cathode and a role of efficiently transporting electrons injected from the cathode toward the light emitting layer.

The physical properties required for the material constituting the hole blocking layer include high electron mobility, low hole mobility, large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). It is expensive. Examples of the material of the hole blocking layer satisfying such conditions include bis (2-methyl-8-quinolinolato) (4-phenolato) aluminum (PAlq) and bis (2-methyl-8-quinolinolato) (tri Mixed ligand complexes such as phenylsilanolato) aluminum (SAlq), bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, etc. Stylyl compounds such as metal complexes and distyrylbiphenyl derivatives (Japanese Patent Laid-Open No. 11-242996), 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4- Triazole derivatives such as triazole (JP-A-7-41759), phenanthroyl such as bathocuproine (BCP) And the like derivatives (JP-A-10-79297). Furthermore, compounds having at least one pyridine ring substituted at the 2,4,6-positions described in International Publication No. 2005-022962 are also preferable as the material for the hole blocking layer.

In addition, only 1 type may be used for the material of a hole-blocking layer, and 2 or more types may be used together by arbitrary combinations and a ratio. Although there is no restriction | limiting in the formation method of a hole-blocking layer, It is preferable to form by the wet film-forming method from a viewpoint of dark spot reduction.

The film thickness of the hole blocking layer is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

* Electron transport layer *
The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the device, and can efficiently transport electrons injected from the cathode between the electrodes to which an electric field is applied in the direction of the light emitting layer. Formed from compounds.

As the electron transporting compound used for the electron transport layer, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons having high electron mobility can be efficiently transported. Use possible compounds. Examples of the compound satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline such as Alq3 (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadi Azole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline Compound (JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinonediimine, n-type hydrogenated amorphous Silicon carbide, n-type sulfur Zinc, such as n-type zinc selenide.

In addition, only 1 type may be used for the material of an electron carrying layer, and 2 or more types may be used together by arbitrary combinations and a ratio.

The formation method of the electron transport layer is not limited, but it is preferably formed by a wet film formation method from the viewpoint of reducing dark spots.

The film thickness of the electron transport layer is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

* Electron injection layer *
The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode into the light emitting layer. In order to perform electron injection efficiently, the material for forming the electron injection layer is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and their compounds (CsF, Cs ₂ CO ₃ , Li ₂ O, LiF) and the like. .1 nm or more and 5 nm or less are preferable.

Furthermore, an organic electron transport compound typified by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium or rubidium ( As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, and the like, it is possible to improve the electron injection / transport property and achieve excellent film quality. preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.

In addition, only 1 type may be used for the material of an electron injection layer, and 2 or more types may be used together by arbitrary combinations and a ratio. There is no restriction | limiting in the formation method of an electron injection layer. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.
--- Method of manufacturing organic EL element--
As shown in FIG. 2, an example of a method for manufacturing an organic EL element according to this embodiment includes a bank plate-making process (S1) for patterning an insulating layer, that is, a bank to define a light emitting area of each organic EL element. From a predetermined organic semiconductor coating liquid containing a predetermined solute that becomes each organic semiconductor layer such as a hole injection layer, a hole transport layer, and a light emitting layer and a solvent that disperses the solute, a wet film-forming method such as an inkjet process Thus, a coating step (S2) for forming a predetermined coating liquid film, a drying step (S3) for drying the coating liquid film in a vacuum chamber of a vacuum drying apparatus, and a firing step (sintering the dried predetermined coating liquid film) S4). The coating process (S2), the drying process (S3), and the baking process (S4) are repeated for each organic semiconductor layer to form a plurality of layers.

Note that the hole blocking layer, the electron transport layer, the electron injection layer, and the cathode of the organic EL element can be sequentially formed in the formation step (S5) using a vapor deposition process. The deposition process (S5) is also repeated for each layer to form a plurality of layers.

The bank plate making process (S1), the coating process (S2), the drying process (S3), the firing process (S4), and the vapor deposition process (S5) will be described later.

(Bank making process)
As a pretreatment of the method for manufacturing an organic semiconductor element, a transparent substrate 1 such as glass in which an anode 2 is formed in a predetermined pattern in advance and washed as shown in FIG. 3 is prepared. In the bank plate making process (S1), a partition bank is formed on the pattern of the substrate 1 and the anode 2.

The bank formation method is preferably formed by photolithography, and the bank is formed by forming a photosensitive composition on the substrate 1, exposing and developing.

Therefore, after development, if a residue of the photosensitive composition remains in the area partitioned by the bank, it may affect light emission when the organic EL device is formed. Therefore, before forming the photosensitive composition, Then, after forming a hydrophilic compound-containing composition on the substrate 1 to form an undercoat layer, a photosensitive composition is formed thereon, exposed and developed.

First, as shown in FIG. 4, an undercoat layer B1 is formed on the entire surface of the substrate 1 and the anode 2, and a photosensitive composition is applied on the entire surface of the undercoat layer and dried to thereby form a bank resist. Layer B2 is formed. Thereafter, although not shown, the bank pattern is exposed using an exposure mask, and the non-exposed portion is removed together with the undercoat layer by development processing to form a bank. The bank pattern may be a stripe, a cross-girder shape or a ladder shape. The bank pitch is generally about 100 μm to 1000 μm. Here, the layer formed of the photosensitive composition before exposure and development is referred to as a bank resist layer, and the bank resist layer cured by exposure and development to form a bank is referred to as a resin layer.

By the above photolithography method, as shown in FIG. 5, the bank BK has a laminated structure of an undercoat layer B1 formed of a hydrophilic compound-containing composition and a resin layer B3 formed of a photosensitive composition.

As the method of forming the undercoat layer B1, it is preferable to form by applying a hydrophilic compound-containing composition containing a hydrophilic compound on the hole transport layer and drying it. The hydrophilic compound-containing composition is a hydrophilic compound containing a photosensitive composition (so-called negative photoresist) that is polymerized or cured after exposure and obtains insoluble or hardly soluble properties in the developer in the subsequent development process. It may be a compound-containing composition, or a photosensitive composition (so-called positive photoresist) containing a composition in which an exposed portion changes due to light exposure and acquires a readily soluble property in a developing solution in a subsequent development step. ) -Containing hydrophilic compound-containing composition. In particular, an inorganic negative photosensitive composition may be employed. When the undercoat layer has photosensitivity, the bank resist layer and its photosensitive type (negative type or positive type) are usually matched.

A hydrophilic compound is a compound that dissolves or swells in water. Specifically, a compound having a functional group such as a carboxy group, a hydroxyl group, a sulfonic acid (salt) group, a phosphonic acid (salt) group, an amino group, an amide group, or a quaternary ammonium base in the molecule is preferable. . In particular, the hydrophilic compound is preferably an organic compound, and is preferably a hydrophilic resin in order to ensure resistance. Here, the hydrophilic resin is a resin having the above functional group, and usually refers to a resin obtained by polymerizing or condensing a unit (monomer or polymer) containing the above functional group, and has a weight average molecular weight (Mw). ) Refers to a polymer material having about 1000 to 2,000,000. Examples of hydrophilic resins include polyvinyl alcohol, polysaccharides, polyvinyl pyrrolidone, polyethylene glycol, gelatin, glue, casein, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, hydroxyethyl starch, sucrose octaacetate, ammonium alginate, sodium alginate, polyvinyl Amine, polyallylamine, polystyrene sulfonic acid, polyacrylic acid, water-soluble polyamide, maleic anhydride copolymer, gum arabic, water-soluble soybean polysaccharide, white dextrin, pullulan, curdlan, chitosan, alginic acid, enzymatically degraded etherified dextrin In addition to the above, (co) polymer (co) polymerized using a hydrophilic monomer, and the like can be mentioned.

The hydrophilic compound-containing composition may contain one kind of these hydrophilic compounds or may contain two or more kinds. The hydrophilic compound is preferably contained in the total solid content of the hydrophilic compound-containing composition in an amount of preferably 10% by weight or more, more preferably 20% by weight or more and 100% by weight or less. The hydrophilic compound-containing composition according to the present embodiment may contain other components as necessary in addition to the hydrophilic compound.

The solvent contained in the hydrophilic compound-containing composition is not particularly limited as long as the solid content of the hydrophilic compound-containing composition can be dissolved or dispersed and enables uniform coating. Water and / or alcohol solvents Is preferably used. The solvent contained in the hydrophilic compound-containing composition may be only one selected from water, alcohol solvents, and other solvents, or may be a mixed solvent of two or more. The total solid concentration in the hydrophilic compound-containing composition is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, preferably 10% by weight or less, more preferably 5% by weight or less. is there.

As a method for forming the undercoat layer of the hydrophilic compound-containing composition, a wet film forming method may be mentioned. Further, as a drying method after film formation, a method of drying using a hot plate, a clean oven, an IR oven, or a convection oven is preferable. The drying temperature is usually 40 ° C. or higher, preferably 50 ° C. or higher, usually 200 ° C. or lower, preferably 130 ° C. or lower. Further, the drying time is preferably 15 seconds or more, preferably 30 seconds or more, preferably 5 minutes or less, and preferably 3 minutes or less.

The thickness of the undercoat layer obtained after drying is preferably 1/3 or less of the completed bank height including the undercoat layer, particularly preferably 1/4 or less, and 1/200 or more. It is particularly preferable that the ratio is 1/50 or more. The specific thickness of the undercoat layer is preferably 5 nm or more, more preferably 7 nm or more, particularly preferably 10 nm or more, preferably 4 μm or less, more preferably 1 μm or less, and particularly preferably 0.5 μm or less. If the thickness of the undercoat layer is less than this lower limit, the effect of the undercoat layer is difficult to obtain, and if it exceeds the upper limit, the organic semiconductor coating film is hardly formed uniformly in the region partitioned by the bank. Further, when the undercoat layer is not photosensitive, it is difficult to hold the upper bank resist layer.

Next, the photosensitive composition is made of a material that can be patterned by exposure and development using, for example, photosensitive polyimide or novolac resin. The photosensitive composition usually contains an ethylenically unsaturated compound, a photopolymerization initiator and a solvent, and preferably further contains a binder resin, a crosslinking agent, a surface modifier, a liquid repellent component, and the like. Moreover, a coloring agent, a coating property improving agent, an ultraviolet absorber, a polymerization inhibitor, an antioxidant, a silane coupling agent, an epoxy compound, other resins, and the like can be appropriately blended. The liquid repellent component is a component having a property of repelling the coating liquid for forming the organic semiconductor coating film formed in the region partitioned by the bank. By containing the liquid repellent component, the bank of the coating liquid is included. The contact angle with respect to is 20 °, more preferably 30 ° or more, and particularly preferably 45 ° or more. The liquid repellent component may be any component having an effect of imparting liquid repellency to the bank, and includes a fluorine-containing compound and a silicon-containing compound, and a fluorine-containing compound is preferable. When a fluorine-based liquid repellent component is not mixed with the photosensitive composition, plasma treatment with a reactive gas such as CF ₄ may be performed after the bank is formed.

Examples of the coating method for applying the photosensitive composition on the undercoat layer to form the bank resist layer include the above-described wet film forming method.

The coating amount of the photosensitive composition is, as a dry film thickness, the height of the bank including the undercoat layer is usually 0.5 μm or more, preferably 1 μm or more, more preferably 1 μm or more, usually 10 μm or less, preferably 9 μm or less. More preferably, the amount is such that the film thickness is 7 μm or less. At this time, it is assumed that the dry film thickness or the height of the finally formed bank is uniform over the entire area of the substrate.

(Coating process)
In the coating step (S2) of the manufacturing method of the organic semiconductor element, in order to form the organic semiconductor coating film in the region partitioned by the bank on the substrate, the component of the organic semiconductor layer (solid content remaining after drying) is usually used. Etc.) is applied to the bank partition region by dissolving or dispersing it in a solvent (component exhausted after drying).

In addition to the relief printing method, the dispenser method, and the slit coating method, this coating liquid can be supplied into the bank partition region by an ink discharge type such as an ink jet method (droplet discharge method) or a nozzle print method (liquid flow discharge method). A coating method is preferable, and an inkjet method is particularly preferable.

As a solvent of the coating solution used in the ink jet method, it is generally known to prevent nozzle drying and clogging by adding a relatively large amount of a high-boiling solvent component. It is preferable to select an optimal solvent in consideration. In particular, in the case of the ink jet method, it is preferable to use a solvent having a droplet diameter of 100 to 400 μm after 1 minute has elapsed when the droplet is deposited on the surface to be coated with a droplet size of 20 pl. More preferably, the droplet diameter is 150 to 300 μm. Thereby, the occurrence of film thickness unevenness and pinholes can be prevented.

In the organic semiconductor coating liquid, at least two kinds of solid contents (for example, a low-molecular host material and a guest material to be a light emitting layer) may be dispersed and dissolved as a solute. The concentration of the solid content of the predetermined coating solution in the coating step is preferably 0.1% by weight to 10% by weight, and more preferably 3% by weight to 10% by weight. If the concentration of the solid content is below this lower limit, the amount of evaporation of the solvent increases, which is inconvenient for vacuum drying. If the concentration exceeds the upper limit, nozzle drying and clogging are likely to occur. The solid content of the predetermined coating solution in the coating step is preferably a low molecular weight compound having a molecular weight of 100 or more and 10,000 or less. If the molecular weight of the low molecular weight compound is below this lower limit, the amount of solvent evaporation increases, which is inconvenient for vacuum drying, and if it exceeds the upper limit, nozzle drying and clogging are likely to occur. The solvent of the predetermined coating solution is a solvent having a vapor pressure at room temperature of 1 Pa to 70 Pa from the above-mentioned solvent (used in the composition for forming a hole injection layer), such as ketone solvents and esters shown in Table 1 below. It is preferable to select from a system solvent, a halogen-free aromatic solvent, and the like. This is because if the vapor pressure of the solvent deviates from the lower limit and the upper limit, it becomes inconvenient for vacuum drying. Further, the solvent for the predetermined coating solution is preferably selected from those having the normal boiling point of 200 ° C. to 300 ° C. from the same solvent. If the standard boiling point of the solvent is below this lower limit, nozzle drying and clogging are likely to occur, and if it exceeds the upper limit, it is inconvenient for vacuum drying.

(Drying process)
In the drying step (S3) of the method for manufacturing an organic semiconductor element, after supplying the coating liquid into the bank partition region, a vacuum drying method is performed in which drying is performed in a vacuum chamber. When vacuum drying, it is not always necessary to heat.

An example of a vacuum drying apparatus used in the vacuum drying method is shown in FIG. FIG. 6 is a schematic configuration diagram showing a cross section of the vacuum drying apparatus of the embodiment.

6 includes a vacuum chamber 11, a vacuum gauge 12 connected to the vacuum chamber 11 via a pipe, a vacuum pump 14 connected to an exhaust port of the vacuum chamber 11 via a pipe 13, The proportional control valve 15 is provided in the vacuum chamber 11 and the vacuum pump 14 to adjust the exhaust speed, and the exhaust control unit 16 is electrically connected to the vacuum gauge 12 and the proportional control valve 15. The exhaust control unit 16 controls the exhaust speed of the proportional control valve 15.

The vacuum chamber 11 is configured such that a bottom portion 11a and a lid portion 11b are airtightly detachably joined via an O-ring 11c, and an exhaust port is formed on the bottom portion 11a side. A stage 17 is provided on the exhaust port of the bottom portion 11a inside the vacuum chamber, and the stage 17 is supported on the bottom portion 11a at a predetermined distance via a plurality of support legs 18. On the stage 17, the board | substrate 1 with which the predetermined coating liquid which is a to-be-dried body was apply | coated is mounted. On the bottom 11a side of the vacuum chamber 11, a second proportional control valve 19 on a pipe connected to the intake port is provided and communicated with the atmosphere via a filter (not shown). The second proportional control valve 19 is subjected to intake air control by an electrically connected exhaust control unit 16. During the exhaust operation, the second proportional control valve 19 is closed.

The exhaust port provided in the bottom 11a of the vacuum chamber 11 is connected to a vacuum pump 14 via a pipe 13, and the gas in the vacuum chamber 11 is exhausted to the outside via the vacuum pump 14 from this exhaust port. The inside of the chamber 11 can be in a predetermined vacuum state. The exhaust port may be formed at a position where the gas can be uniformly exhausted in the vacuum chamber 11, and the number and position thereof are not limited. The vacuum pump 14 can be a dry pump or a rotary pump. In the present embodiment, the vacuum pump 14 is capable of exhibiting an exhaust speed capable of reducing the pressure in the vacuum chamber 11 from the atmosphere to 60 Pa within 10 seconds, preferably within 0.5 seconds. The vacuum pump 14 of the vacuum drying apparatus determines the maximum exhaust speed, and the exhaust speed is controlled by the proportional control valve 15 provided in the preceding stage. That is, the exhaust control unit 16 performs control to exhaust the gas around the predetermined coating liquid film in the vacuum chamber 11 at a high speed within a period of 10 seconds or less. The predetermined exhaust speed is a speed from 0.5 to 10 seconds from atmospheric pressure to 60 Pa.

As shown in the graph of FIG. 7, the exhaust control unit 16 controls the proportional control valve 15 to show the ideal pressure change with time in the vacuum chamber of the vacuum drying apparatus of the embodiment. The gas exhaust speed is adjusted so that the exhaust time in the range of t _L = 0.5 seconds to t _H = 10 seconds from the atmospheric pressure P ₀ to the atmospheric pressure P ₁ = 60 Pa is t.

The vacuum chamber 11, the stage 17 and the like constituting the vacuum drying apparatus are each formed of a material such as SUS and iron capable of maintaining appropriate strength, and the area of the main surface of the stage 17 is larger than that of the substrate 1 disposed in the center. The range of 70 to 99% of the bottom area of the vacuum chamber 11 is preferable. Further, the distance between the upper lid portion 11b of the stage 17 and the peripheral portion of the stage 17 and the side wall portion of the bottom portion 11a is equal and uniform so that the gas flow does not affect the coating liquid film on the substrate 1. It is preferable that

Further, in the vacuum drying apparatus, the exhaust control unit 16 can also control the exhaust speed by controlling the opening and closing of the proportional control valve 15 based on the pressure measurement output of the vacuum gauge 12. For example, when the vacuum chamber 11 is evacuated within a period of 10 seconds or less, there is a solvent having a high or low vapor pressure in the solvent or a mixed solvent thereof, or there is a fluctuation in atmospheric pressure. The differential value of the pressure change with time is calculated from the pressure measurement output of the vacuum gauge 12 in accordance with the pressure fluctuation, and the exhaust control unit 16 controls the proportional control valve 15 to stop the exhaust operation even within 10 seconds. The proportional control valve 19 can return the inside of the vacuum chamber 11 to a predetermined atmospheric pressure such as atmospheric pressure at a predetermined intake speed.

As described above, the vacuum drying apparatus according to the embodiment for drying a predetermined coating liquid film in a vacuum includes a vacuum chamber 11 that accommodates a substrate carrying the predetermined coating liquid film in the internal space, and gas from the internal space of the vacuum chamber to the outside. And an exhaust controller (vacuum gauge 12, pipe 13, vacuum pump 14, proportional control valve 15) and an exhaust controller 16 for maintaining the exhaust device at an exhaust speed for exhausting the inside of the vacuum chamber 11.

In the vacuum drying apparatus of the embodiment, the components of the organic semiconductor layer (remaining after drying) are exhausted within a short period of 10 seconds or less regardless of the evaporation rate of the solvent of the predetermined coating liquid film, and the solvent is rapidly evaporated. Since the state in which the solid content is dispersed is maintained, both the processing speed and the planar smoothness of the coating film can be improved.

It goes without saying that the vacuum drying method of this embodiment can be applied not only to a single solvent coating solution but also to a mixed solvent coating solution.

Vacuum drying is performed at an exhaust rate of 10 seconds or less up to 60 Pa, and then the residual solvent can be removed by exhausting in about 5 minutes in a vacuum at or above the respective vapor pressure.

(Baking process)
In the baking step (S4) of the method for manufacturing an organic semiconductor element, the organic semiconductor layer is baked, for example, using a hot plate, a clean oven, an IR furnace, etc., at a temperature of 200 ° C. for about 30 minutes. Can be carried out by heating.

(Deposition process)
In the vapor deposition step (S5) of the manufacturing method of the organic semiconductor element, the substrate after firing is held on a substrate holder provided on the inner surface of, for example, a semicircular dome treatment chamber of a vacuum vapor deposition apparatus, and the vapor deposition located at the center position of the semicircular dome A planned organic semiconductor or inorganic material is placed on the source boat, and the dome is slowly rotated around the center during film formation, for example, the film formation starting pressure is set to a high vacuum to about 10 ⁻⁴ Pa, and the vapor deposition film Improves adhesion and film quality. In the vapor deposition of inorganic materials, the film forming temperature can be increased (300 ° C. to 400 ° C.), but plastic substrates and the like are deposited at a low temperature. The evaporation source evaporation method includes resistance evaporation (dissolves and evaporates the organic semiconductor or inorganic material by electric resistance heating of the boat) and electron beam evaporation (dissolves the focused semiconductor beam or organic semiconductor or inorganic material of the boat using an electron gun). Evaporate).

An anode is formed by patterning into a transparent stripe of indium tin oxide (ITO) having a thickness of 100 μm and a thickness of 120 nm on a glass substrate by photolithography, and an undercoat layer B1 of polyvinyl alcohol on the ITO substrate shown in FIG. And a polyimide resin layer B3 stacked bank BK (width 10 μm) formed in a cross-beam shape (100 μm × 100 μm), and the anode / hole injection layer / hole transport layer / light emitting layer in the recess of the bank An organic EL element having a film structure of / hole blocking layer / electron transport layer / electron injection layer / cathode / is produced.

First, the above-described coating process (S2), drying process (S3), and firing process (S4) are repeated for each of the hole injection layer, the hole transport layer, and the light emitting layer to laminate each layer.

As shown in FIG. 8, the hole injection layer coating liquid 3 is applied onto the anode 2 in each partition region of the bank BK by an ink jet method, vacuum dried, and baked as shown in FIG. The injection layer 3 is formed.

As shown in FIG. 10, the coating solution 4 for the hole transport layer is applied onto the hole injection layer 3 in each partition region of the bank BK by an ink jet method, vacuum dried, and baked as shown in FIG. Thus, the hole transport layer 4 is formed.

As shown in FIG. 12, the coating solution 5 for the light emitting layer is applied onto the hole transport layer 4 in each partition region of the bank BK by the ink jet method, vacuum dried, and fired to emit light as shown in FIG. Layer 5 is formed.

Next, the vapor blocking step (S5) is repeated together with the hole blocking layer, the electron transport layer, the electron injection layer, and the cathode to laminate each layer.

A hole blocking layer material is loaded into a vapor deposition source boat of a vacuum vapor deposition apparatus and vapor deposition is performed to form a hole blocking layer 6 on the light emitting layer 5 as shown in FIG.

Next, the electron transport layer material is loaded into the vapor deposition source boat of the vacuum vapor deposition apparatus, and the vapor deposition is performed to form the electron transport layer 7 on the hole blocking layer 6 as shown in FIG.

Next, the electron injection layer material is loaded into the vapor deposition source boat of the vacuum vapor deposition apparatus, and the vapor deposition is performed to form the electron injection layer 8 on the electron transport layer 7 as shown in FIG.

Next, a cathode material is loaded into a vapor deposition source boat of a vacuum vapor deposition apparatus and vapor deposition is performed to form a cathode 9 on the electron injection layer 8 as shown in FIG.

[Experimental Example 1]
Specifically, in the experiment, except that the hole blocking layer, the electron transport layer, the electron injection layer, and the cathode were formed by vapor deposition, 100 μm was formed on the glass substrate by the above-described process including the drying step by the vacuum drying apparatus of the embodiment. Anode (ITO) / hole injection layer (CuPc) / hole transport layer (α-NPD) / light emitting layer ((Ir (ppy) 3) + (CBP)) / hole blocking layer comprising bank sections of 100 μm An organic EL device having a film configuration of (BCP) / electron transport layer (Alq3) / electron injection layer (LiF) / cathode (Al) / was fabricated and evaluated.

Table 2 shows the composition of the low molecular weight material coating solution for the hole injection layer, hole transport layer and light emitting layer by the inkjet method (the solvent is common to each layer). Two kinds of solid contents (guest material: Ir (ppy) 3) and (host material: CBP) were dispersed or dissolved in the solvent in the light emitting layer coating solution.

When the inside of the vacuum chamber is evacuated from atmospheric pressure to 60 Pa at a evacuation rate of 1 second (60 Pa-1 second) in the vacuum drying process of each coating layer of the hole injection layer, the hole transport layer, and the light emitting layer, from the atmospheric pressure When exhausting to 60 Pa as a 10-second exhaust speed (60 Pa-10 seconds) and exhausting from atmospheric pressure to 60 Pa as a 200-second exhaust speed (60 Pa-200 seconds), changing the exhaust speed in three patterns, An organic EL element was formed. In the film formation of each organic EL element, the film formation conditions of the anode (ITO), the hole blocking layer (BCP), the electron transport layer (Alq3), the electron injection layer (LiF), and the cathode (Al) were the same.

The meniscus at the outermost peripheral edge of the coating film of the light emitting layer in the bank compartment, which was applied and vacuum-dried by the ink jet method, and the light emission of the obtained organic EL element were observed. 18 and 19 show the measurement of the meniscus width of the light-emitting layer in each bank section of the organic EL element at an exhaust speed of 10 seconds and 200 seconds from atmospheric pressure to 60 Pa during vacuum drying (60 Pa-10 seconds, 60 Pa-200 seconds). And the result of having performed the microscope observation of the light emission state of the element is shown. FIG. 7 also shows changes with time in the pressure in the vacuum chamber in the case of the exhaust speed (60 Pa-10 seconds, 60 Pa-200 seconds).

From the experimental results, when the exhaust speed (60 Pa-10 seconds), the width of the non-light emitting portion due to the meniscus at the periphery of the light emitting layer was about 5 μm. The part width was 10 μm or more, and the reduction of the flat surface and the light emitting part was found.

In the drying process, the organic EL device has a luminous efficiency of 106% when the exhaust speed is 60 Pa-1 sec, and the organic EL device has a luminous efficiency of 100% when the exhaust speed is 60 Pa-10 sec. The luminous efficiency of the organic EL device in the case of (−200 seconds) was lower than these.

[Experimental Examples 2 to 26]
Instead of diethylene glycol-n-butyl ether acetate, which is a common solvent for the hole injection layer, hole transport layer, and light emitting layer used in Experimental Example 1, the solvents in Table 3 below were used as the solvent for the coating liquid composition for each layer. Experimental examples 2 to 26 of organic EL elements having the same film configuration were produced and evaluated under the same conditions as in experimental example 1. In each case, similarly to Experimental Example 1, the vacuum chamber was evacuated from the atmospheric pressure to 60 Pa at a evacuation rate of 1 second in the vacuum drying process of the coating layers of the hole injection layer, the hole transport layer, and the light emitting layer. When exhausting from atmospheric pressure to 60 Pa as an exhaust rate of 10 seconds (60 Pa-10 seconds) When exhausting from atmospheric pressure to 60 Pa as an exhaust rate of 200 seconds (60 Pa-200 seconds) The organic EL element was formed by changing the exhaust speed in three patterns.

[Experimental result]
As a result of performing microscopic observation of the surface and light emission state of the devices prepared in Experimental Examples 2 to 26, in Experimental Examples 2 to 22, the coating layer had a uniform film thickness and uniform light emission was obtained. In the experimental example where the standard boiling point of the solvent is lower than 200 ° C., nozzle drying and clogging were observed in the process, and in the experimental example where the standard boiling point of the solvent was higher than 300 ° C., the coating film was not completely dried even by vacuum drying. In some cases, it was inconvenient.

Therefore, the solvent for the coating solution for each layer by the ink jet method is preferably selected from those having a vapor pressure at room temperature of 1 Pa to 70 Pa, and further selected from those having a normal boiling point of 200 ° C. to 300 ° C. It can be seen that this is preferable.

Although the organic EL element has been described in the present embodiment, the organic semiconductor element manufacturing method and the vacuum drying apparatus according to the present invention include an organic semiconductor layer in addition to an organic EL display and an organic EL illumination that form a film by wet coating. Needless to say, the present invention can also be applied to organic TFTs, organic solar cells, and color filters to be used.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 11 Vacuum chamber 11a Vacuum chamber bottom 11b Vacuum chamber lid 11c O-ring 12 Vacuum gauge 13 Piping 14 Vacuum pump 15 Proportional control valve 16 Exhaust controller 17 Stage 18 Support leg B1 Undercoat layer B2 Resist layer B3 Resin layer BK Bank

Claims

A method of manufacturing an organic semiconductor element having an organic semiconductor layer disposed between a pair of opposing anodes and cathodes on a substrate,
A coating step of forming an organic semiconductor coating liquid film by a wet film-forming method from an organic semiconductor coating liquid containing a solute to be the organic semiconductor layer and a solvent for dispersing the solute;
Drying the organic semiconductor coating liquid film in a vacuum chamber, and
In the drying step, the vacuum chamber is evacuated from an atmospheric pressure to an atmospheric pressure of 60 Pa at an evacuation speed of 0.5 seconds or more and 10 seconds or less.
The method for producing an organic semiconductor element according to claim 1, wherein the organic semiconductor coating liquid contains at least two kinds of solids to be an organic semiconductor layer dispersed or dissolved as the solute.
The method for producing an organic semiconductor element according to claim 2, wherein the concentration of the solid content of the organic semiconductor coating liquid in the coating step is 0.1 wt% to 10 wt%.
The method for producing an organic semiconductor element according to claim 2, wherein the solid content of the organic semiconductor coating liquid in the coating step is a compound having a molecular weight of 100 or more and 10,000 or less.
The method for producing an organic semiconductor element according to claim 4, wherein the compound is a part of a component of the light emitting layer.
The method for producing an organic semiconductor element according to claim 1, wherein the organic semiconductor coating solution has a solvent having a vapor pressure of 1 Pa to 70 Pa at room temperature.
The method for producing an organic semiconductor element according to claim 6, wherein a normal boiling point of the solvent of the organic semiconductor coating solution is 200 ° C to 300 ° C.
A vacuum drying apparatus for drying an organic semiconductor coating liquid film formed from an organic semiconductor coating liquid containing a solute to be an organic semiconductor layer and a solvent for dispersing the solute in vacuum, the organic semiconductor coating liquid film A vacuum chamber that accommodates a substrate carrying the substrate in an internal space, an exhaust device that exhausts gas from the internal space of the vacuum chamber to the outside, and the exhaust device is controlled to control the inside of the vacuum chamber from atmospheric pressure to an atmospheric pressure of 60 Pa An evacuation control unit that evacuates at an evacuation speed of 0.5 seconds or more and 10 seconds or less to dry the organic semiconductor coating liquid film.