JP5152331B2 - ORGANIC ELECTROLUMINESCENT DEVICE AND MANUFACTURING METHOD THEREOF - Google Patents

Description

  The present invention relates to an organic electroluminescence (also referred to as organic EL) element and a method for manufacturing the same. More specifically, the present invention relates to an organic electroluminescent element that can be manufactured by a wet method and has improved uniform light emission, and a method for manufacturing the same.

  There are phosphorescent light-emitting compounds and fluorescent light compounds as compounds used in organic electroluminescent elements, and it is known that phosphorescent light-emitting compounds have higher efficiency. Furthermore, it is known that high efficiency can be obtained by providing a functional layer such as a hole transport layer, a light-emitting layer, or an electron transport layer in order to efficiently emit a phosphorescent light-emitting material.

  On the other hand, due to the high utilization efficiency of materials and the like, attention has been focused on a method for producing an organic EL by a wet method.

  However, when a device is manufactured by a wet method, there is a problem that black spots or white spots having a diameter of about several tens of μm are generated on the light emitting surface.

  Although it is described that a polymer material is applied with a solvent that interacts with the material (see, for example, Patent Document 1), black spots and white spots having a diameter of about several tens of μm are formed on a light emitting surface of a low molecular material. The problem of occurring was not enough.

JP 2006-244806 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic electroluminescent element that can be stably manufactured by a wet method and does not generate black spots or white spots, and a method for manufacturing the same. is there.

  The above object of the present invention can be achieved by the following constitution.

1. A method for producing an organic electroluminescent device by a wet method, wherein a compound having a hetero atom- containing substituent of 0.10 or more and 0.60 or less with respect to one carbon atom of the mother nucleus A method for producing an organic electroluminescent element, wherein the organic electroluminescent element is dissolved in an organic solvent having the same substituent as the group and coated.

2. 2. The method for producing an organic electroluminescent element according to 1 above, wherein the layer formed with the organic solvent having a substituent is a layer adjacent to the electrode.

3. 3. The method for producing an organic electroluminescent element according to 1 or 2, wherein the organic solvent having the substituent is mixed with another solvent .

4). 4. The method for producing an organic electroluminescent element according to 3 above, wherein the content of the organic solvent having a substituent is 30% or more based on the total amount of the organic solvent.

5. An organic electroluminescence device manufactured by the manufacturing method according to any one of 1 to 4 above.

  According to the present invention, it is possible to provide an organic electroluminescent element that can be stably manufactured by a wet method and does not generate black spots or white spots, and a method for manufacturing the same.

  As a result of intensive studies by the inventors, when a compound having a specific substituent is dissolved and applied in an organic solvent having the specific substituent, a black spot or a white spot having a diameter of about 10 μm is generated on the light emitting surface. It was found that there was no problem and it could be applied uniformly.

  The reason for this is not clear, but it is presumed that the compound substituent and the solvent substituent gently interact to form a uniform amorphous film in which abnormal protrusions and the like are unlikely to occur.

  In the present invention, the compound having a substituent containing a hetero atom preferably has 0.1 or more and 0.6 or less of the substituent with respect to one carbon atom of the mother nucleus. The reason for this is not clear, but when the coating film is dried, when the number of the substituents is a specific number, it is presumed that the orientation of the molecules is preferably controlled and the film has good uniformity. . Even if the number of the substituents is too large or small, the interaction between the compound itself and the interaction between the compound and the solvent when coated with an organic solvent having the substituent is not preferable, and a uniform film is formed. It is estimated that it is difficult to fall.

  In particular, the effect of the present invention is remarkable when used in the first layer adjacent to the electrode on the substrate. Although the reason for this is not clear, it is generally estimated that the inorganic substrate or the transparent electrode and the organic compound have poor affinity. However, since the substrate is affinityd with an organic solvent having the same substituent as the substituent of the coating compound, it is estimated that the substrate or the lower layer can be coated with good adhesion. This effect is particularly effective when the organic solvent remains in the organic film at 1 ppm or more and 1000 ppm or less. The reason for this is not clear, but it is presumed that the subtle fluidity of the material increases the adhesion to the lower layer.

[Explanation of substituents]
The substituent containing a hetero atom as referred to in the present invention refers to a substituent containing a hetero atom such as nitrogen, oxygen, sulfur or phosphorus.

  That is, substituents that do not contain atoms other than carbon and hydrogen atoms are not included in the substituents referred to in the present invention.

  Further, a hetero atom-containing cyclic structure such as dioxane or pyridine is not included in the substituent in the present invention.

Specific examples of the substituent useful in the present invention include a halogen atom (—Cl, —Br, —I, —F), a hydroxy group (—OH), an amino group (—N (R) R ′), an amide group. (—C (═O) —N (R) R ′), hydroxylamino group (—NH—OH), nitro group (—NO ₂ ), alkoxy group (—OR), carbonyl group (—COR), carboxyl group (—COOR), cyano group (—CN), sulfoxide group (—SOR), sulfone group (—SO ₂ R), sulfonic acid group (—SO ₂ OH), sulfonamide group (—SO ₂ N (R) R ′), A phosphonyl group (—PO (OH) ₂ ) and the like. However, in the substituent, R and R ′ represent a hydrogen atom or a lower hydrocarbon group having 10 or less carbon atoms. Here, an alicyclic ketone compound such as cyclohexanone or cyclopentanone is defined as a kind of carbonyl compound.

  In addition, although the substituent of a compound and the substituent of an organic solvent require that it is the same kind, it is the most preferable that it is exactly the same.

[Description of compound]
The compound having a substituent containing a hetero atom of the present invention (hereinafter also referred to as the compound of the present invention) is a compound having various functionalities added to the organic layer described later, and the compound is a solute. Then, it is dissolved in the organic solvent of the present invention, which will be described later, to form a coating film.

  The compound applicable to the present invention is not particularly limited as long as it is a compound containing a substituent containing a hetero atom. As a compound to be used, a low molecular compound is preferable to a high molecular compound. As a compound to be used, a preferable molecular weight is 100,000 or less, more preferably 50,000 or less, and most preferably 10,000 or less.

  The reason why a low molecule is preferable is not clear, but in the present invention, the interrelationship between an object to be coated, a solute, and a solvent is important, and if the size of a compound that becomes a solute differs greatly from the size of a solvent molecule, Seems to be different. In the present invention, it is presumed that a form in which the entire periphery of the low molecule is solvated is required.

  The organic solvent used in the present invention is not particularly limited as long as it has a substituent containing a hetero atom. However, since an effect is not seen with an aqueous solvent, it cannot be used in the present invention. In addition, when water is used as the mixed solvent, the effect is not exhibited, so that it cannot be used in the present invention.

  It is preferable that the amount of water mixed as an impurity is small, but the effect of the present invention can be obtained if the amount is 1% or less. More preferably, it is 0.1% or less, and most preferably 0.01% or less.

  The reason why water cannot be used is not clear, but it is thought that water is strongly linked to each other by hydrogen bonds, and the way of interaction with solute molecules is different from other organic solvents.

[Definition of mother nucleus]
The mother nucleus as used in the present invention refers to a portion obtained by removing the above substituent from the compound of the present invention.

[Number of Substituents in Compound]
It is preferable that the compound of this invention has the said substituent of 0.10 or more and 0.60 or less with respect to one carbon atom of the said mother nucleus.

[Description of organic solvent]
The present invention is characterized by using an organic solvent having the same substituent as the compound (solute) of the present invention.

  Therefore, an organic solvent having the same substituent containing a hetero atom as the solute is used.

  Specific solvents include halogen-containing solvents such as dichloroethane and chlorobenzene, alcohols such as ethanol and propanol, amines such as aniline, amides such as N, N-dimethylformamide, nitro-containing solvents such as nitrobenzene, diethyl ether, and methyl Examples include ethers such as -tert-butyl ether, esters such as ethyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone, cyclopentanone and cyclohexanone, and nitriles such as acetonitrile and benzonitrile.

  A solvent having a boiling point of 70 ° C. or higher and 190 ° C. or lower is preferable from the viewpoint of good film formability when applied and dried.

  In the present invention, it is preferable that the solute is dissolved and applied by mixing with another organic solvent in addition to the organic solvent having the same substituent as the solute.

  The organic solvent to be mixed can be used without particular limitation. A solvent having a boiling point of 70 ° C. or higher and 190 ° C. or lower is preferable from the viewpoint of good film formability when applied and dried.

  From the viewpoint of good film formability, toluene, cyclopentanone, cyclohexanone, chlorobenzene and the like are preferable.

  When used in combination with another organic solvent, the content of the solvent having the same substituent as the solute of the present invention is preferably 30% or more based on the total amount of the solvent.

  Hereinafter, the organic electroluminescent element of the present invention will be described in detail.

<< Layer structure of organic EL element >>
Next, although the preferable specific example of the layer structure of the organic EL element which concerns on this invention is shown below, this invention is not limited to these.
(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode << light emitting layer >>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

  The thickness of the light emitting layer is not particularly limited, but from the viewpoint of the uniformity of the film to be formed, the application of unnecessary high voltage during light emission, and the improvement of the stability of the emission color with respect to the drive current. It is preferable to adjust to the range of 2-200 nm, More preferably, it adjusts to the range of 5-100 nm.

  The light emitting layer of the organic EL device according to the present invention preferably contains at least one kind of a light emitting host compound and a light emitting dopant as a guest material, and more preferably contains a light emitting host compound and three or more kinds of light emitting dopants. . A host compound (also referred to as a light-emitting host) and a light-emitting dopant (also referred to as a light-emitting dopant compound) included in the light-emitting layer are described below.

(Host compound)
The host compound used in the present invention will be described.

  Here, the host compound in the present invention is a phosphorescent quantum yield of phosphorescence emission at a room temperature (25 ° C.) having a mass ratio of 20% or more in the compound contained in the light emitting layer. Is defined as a compound of less than 0.1. The phosphorescence quantum yield is preferably less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.

  As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of light emission dopants mentioned later, and, thereby, arbitrary luminescent colors can be obtained.

  The light emitting host used in the present invention may be a conventionally known low molecular compound or a high molecular compound having a repeating unit, and a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (deposition polymerization property). Light emitting host).

  As the known host compound that may be used in combination, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from becoming longer, and has a high Tg (glass transition temperature) is preferable.

  Specific examples of known host compounds include compounds described in the following documents.

  JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445 gazette, 2002-343568 gazette, 2002-141173 gazette, 2002-352957 gazette, 2002-203683 gazette, 2002-363227 gazette, 2002-231453 gazette, No. 003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060, No. 2002. -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

(Luminescent dopant)
The light emitting dopant according to the present invention will be described.

  As the light-emitting dopant according to the present invention, a fluorescent dopant (also referred to as a fluorescent compound) or a phosphorescent dopant (also referred to as a phosphorescent emitter, a phosphorescent compound, a phosphorescent compound, or the like) can be used. From the viewpoint of obtaining an organic EL device having high luminous efficiency, the above-mentioned host compound is used as a light-emitting dopant (sometimes simply referred to as a light-emitting material) used in the light-emitting layer or light-emitting unit of the organic EL device according to the present invention. It is preferable to contain a phosphorescence dopant simultaneously with containing.

  The phosphorescent dopant can be appropriately selected from known materials used for the light emitting layer of the organic EL device.

  The phosphorescent dopant according to the present invention is preferably a complex compound containing a group 8-10 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex compound). Rare earth complexes, most preferably iridium compounds.

  Although the specific example of the compound used as a phosphorescence dopant below is shown, this invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

  Next, an injection layer, a blocking layer, an electron transport layer and the like used as the constituent layers of the organic EL element of the present invention will be described.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.

  A layer having both an electron injection function and an electron transport function may be used. In that case, in this invention, it calls an electron injection transport layer.

  Similarly, a layer having both a hole injection function and a hole transport function may be used, and in this case, in the present invention, it is called a hole injection transport layer.

  An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  Further, ferrocene compounds described in JP-A-6-025658, starbust type compounds described in JP-A-10-233287, JP-A-2000-068058, JP-A-2004-6321 Triarylamine type compounds described in the publication, sulfur-containing ring-containing compounds described in JP-A No. 2002-1171979, US 2002-0158242, US 2006-0251922 Hexaazatriphenylene compounds described in JP-A-2006-49393 and the like can also be used as the hole injection layer.

  The application of the present invention may be applied to any of the organic layers of the organic electroluminescence device, but is preferably applied to a layer adjacent to the electrode, and particularly an anode buffer layer (a hole injection layer or a hole injection layer). Application to the transport layer is also most preferred.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

  The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed.

  The hole blocking layer of the organic EL device according to the present invention is preferably provided adjacent to the light emitting layer.

  The hole blocking layer preferably contains the azacarbazole derivative mentioned as the host compound.

  Further, the hole blocking layer preferably has an ionization potential of 0.3 eV or more larger than the host compound of the light emitting layer. In the case of having a plurality of light emitting layers, it is preferable that the ionization potential is 0.3 eV or more larger than the host compound located on the most cathode side.

  The ionization potential is defined by the energy required to emit an electron at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level, and can be obtained by the following method, for example.

  (1) Using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), a molecular orbital calculation software manufactured by Gaussian, USA The ionization potential can be obtained as a value obtained by rounding off the second decimal place of the value (eV unit converted value) calculated by performing structural optimization using B3LYP / 6-31G *. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.

  (2) The ionization potential can also be obtained by a method of directly measuring by photoelectron spectroscopy. For example, a method known as ultraviolet photoelectron spectroscopy can be suitably used by using a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd.

  On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed. The film thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 to 100 nm, and more preferably 5 to 30 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

  The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

  The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ', N'-tetraphenyl-4,4'-diaminophenyl; N, N'-diphenyl-N, N'- Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' − (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole, as well as two of those described in US Pat. No. 5,061,569 Having a condensed aromatic ring in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

  JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material as described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, these materials are preferably used because a light-emitting element with higher efficiency can be obtained.

  The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. it can. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

  Alternatively, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.

  In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

  Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives Thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which an oxygen atom of the oxadiazole ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  Also, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu , Ca, Sn, Ga, or Pb can also be used as an electron transport material. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  Alternatively, an electron transport layer with high n property doped with impurities as a guest material can be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

  In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be manufactured.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

"cathode"
As the cathode, a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

  Moreover, after producing the said metal with a film thickness of 1-20 nm on a cathode, a transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

"substrate"
As a substrate (hereinafter also referred to as a base, a base material, a support substrate, a support, etc.) that can be used in the organic EL device according to the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. Or opaque. When extracting light from the substrate side, the substrate is preferably transparent. Examples of the transparent substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable substrate is a resin film capable of giving flexibility to the organic EL element.

  Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film, and a barrier film having a water vapor permeability of 0.01 g / m ² / day · atm or less is preferable. Further, it is preferably a high barrier film having an oxygen permeability of 10 ⁻³ g / m ² / day or less and a water vapor permeability of 10 ⁻⁵ g / m ² / day or less.

  As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

  The method for forming the barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

  Examples of the opaque substrate include a metal plate such as aluminum and stainless steel, a film, an opaque resin substrate, a ceramic substrate, and the like.

  The external extraction efficiency at room temperature of light emission of the organic EL device according to the present invention is preferably 1% or more, more preferably 5% or more.

here,
External extraction quantum efficiency (%) = (number of photons emitted to the outside of the organic EL element) / (number of electrons sent to the organic EL element) × 100
It is.

  In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<Sealing>
As a sealing means of the organic EL element used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.

  As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and concave plate shape or flat plate shape may be sufficient. Further, transparency and electrical insulation are not particularly limited.

  Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the organic EL element can be thinned. Further, the polymer film, the oxygen permeability was measured by the method based on JIS K 7126-1987 is ^{1 × 10 -3 ml / m 2} / 24h or less, as measured by the method based on JIS K 7129-1992 water vapor transmission rate (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) is preferably that of ^{1 × 10 -3 g / (m} 2 / 24h) or less.

  For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

  Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

  In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

  In addition, it is also possible to suitably form an inorganic or organic layer as a sealing film by covering the electrode and the organic layer on the outer side of the electrode facing the substrate with the organic layer interposed therebetween, and in contact with the substrate. In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can. Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

  In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.

  Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.

<< Method for producing organic EL element >>
In the method for producing an organic EL device according to the present invention, a part or all of an organic layer sandwiched between an anode and a cathode is formed by a wet method, and at least one layer uses a solvent having the same substituent as a solute. Features.

  The wet method referred to in the present invention is to form a layer by supplying a layer forming material in the form of a solution when forming a layer.

  As an example of a method for producing an organic EL device according to the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

  First, a desired electrode material, for example, a thin film made of an anode material is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm, thereby producing an anode.

  Next, an organic compound thin film (organic layer) of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which is an organic EL element material, is formed thereon.

  Examples of the method for forming each layer include a vapor deposition method and a wet method (a coating method using a die such as a spin coating method, a casting method, an extrusion method, an ink jet method, a spray method, and a printing method) as described above. Furthermore, in the present invention, a film is formed by a coating method such as a spin coating method, an extrusion method, an ink jet method, a spray method, or a printing method because a homogeneous film is easily obtained and pinholes are not easily generated. Is preferred.

  Examples of the solvent for dissolving the organic EL material according to the present invention include nitriles such as acetonitrile and propionitrile, alcohols such as methanol, ethanol and butanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, acetic acid Fatty acid esters such as ethyl, halogenated hydrocarbons such as dichlorobenzene, amides such as DMF, sulfoxides such as DMSO, and organic solvents such as nitromethane can be used.

  After these layers are formed, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm. By providing, a desired organic EL element can be obtained.

  In addition, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order. When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film on the side facing the substrate with the organic layer interposed therebetween or on the sealing film. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used, but the polymer film is light and thin. Is preferably used.

《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1) and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be extracted outside the device, This is because the light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the element side surface.

  As a method for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), A method for improving efficiency by giving light condensing property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method for forming a reflective surface on the side surface of an organic EL element (Japanese Patent Laid-Open No. 1-220394), a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (Japanese Patent Laid-Open No. 62-172691), and lowering the refractive index than the substrate between the substrate and the light emitter. A method of introducing a flat layer having a structure (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer, and a light emitting layer (including between the substrate and the outside) No. 283751) .

  In the present invention, these methods can be used in combination with the organic EL device according to the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, A method of forming a diffraction grating between any layers of the transparent electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.

  In the present invention, by combining these means, it is possible to obtain an organic EL device having further high luminance or durability.

  When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower.

  Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.

  The thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.

  The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction. Light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating in any layer or medium (in a transparent substrate or transparent electrode), and the light is removed. I want to take it out.

  The introduced diffraction grating desirably has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much. However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.

  As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated. At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.

  The arrangement of the diffraction grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condenser sheet>
The organic EL device according to the present invention can be processed on the light extraction side of the substrate, for example, by providing a microlens array-like structure, or combined with a so-called condensing sheet, for example, in a specific direction, for example, the device light emitting surface. On the other hand, the brightness | luminance in a specific direction can be raised by condensing in a front direction.

  As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

  As the condensing sheet, for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, the base material may be formed by forming a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.

  Moreover, in order to control the light emission angle from a light emitting element, you may use together a light diffusing plate and a film with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

<Application>
The organic EL element according to the present invention can be used as a display device, a display, and various light sources. For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Although the light source of a sensor etc. are mentioned, It is not limited to this, Especially, it can use effectively for the use as a backlight of a liquid crystal display device, and a light source for illumination.

  In the organic EL device according to the present invention, patterning may be performed by a metal mask, an inkjet printing method, or the like at the time of film formation as necessary. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

  The light emission color of the organic EL device according to the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (Edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with a luminance meter CS-1000 (manufactured by Konica Minolta Sensing) is applied to the CIE chromaticity coordinates.

Further, when the organic EL element according to the present invention is a white element, white means that the chromaticity in the CIE1931 color system at 1000 cd / m ² is measured when the front luminance at 2 ° viewing angle is measured by the above method. It means that it is in the region of X = 0.33 ± 0.07 and Y = 0.33 ± 0.1. The light emitting layer of the organic EL device according to the present invention preferably contains at least one of a light emitting host compound and a light emitting dopant as a guest material.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

Example 1
<< Production of Organic EL Element 101 >>
(Production of substrate 1)
On a commercially available non-alkali glass substrate, an ITO film having a thickness of 110 nm was provided as a transparent electrode by a sputtering apparatus. The substrate 1 was manufactured by patterning ITO so that a 4 mm × 4 mm light-emitting portion was obtained by photolithography.

(Preparation of organic EL element 101)
The substrate 1 was transferred to a glove box under a nitrogen atmosphere in accordance with ISO 14644-1, the measured cleanliness was class 5, the dew point temperature was −80 ° C. or lower, and the oxygen concentration was 0.8 ppm.

  In the glove box, the hole injection / transport layer coating solution was prepared as follows, and applied with a spin coater under the conditions of 2000 rpm and 30 seconds, and further heated at 80 ° C. for 30 minutes to form a hole injection / transport layer. Was provided. The film thickness was 40 nm when it apply | coated and measured on the conditions with the board | substrate prepared separately.

(Coating solution for hole injection transport layer)
Toluene 100ml
HT-A (containing a hydroxyl group at the end) 1.0 g
Next, the substrate provided up to the hole injecting and transporting layer was moved to a vapor deposition machine without being exposed to the atmosphere, and the pressure was reduced to 4 × 10 ⁻⁴ Pa.

  In addition, a resistance heating boat made of tantalum, HA as the host material for the light emitting layer, Ir-A as the dopant material for the light emitting layer, ET-A as the host material for the hole blocking layer and the electron transport layer, dopant for the electron transport layer Then, cesium fluoride was put in a resistance heating boat made of tantalum, and aluminum was put in a resistance heating boat made of tungsten, and was attached in the vapor deposition machine.

  First, energize and heat a resistance heating boat containing HA and Ir-A, and adjust the deposition rate ratio of HA and Ir to be 0.90 to 0.10. The light emitting layer made of HA and Ir-A doped with 10% of Ir-A was provided by 50 nm by vapor deposition on the substrate while maintaining the speed ratio.

  Next, a resistance heating boat containing ET-A was energized and heated to provide a 5 nm hole blocking layer of ET-A on the substrate. Subsequently, the resistance heating boat containing ET-A and cesium fluoride is heated, and the deposition rate ratio of ET-A and cesium fluoride is adjusted to 0.85 to 0.15. An electron transport layer made of ET-A and cesium fluoride, which was vapor-deposited on the substrate and doped with 15% of cesium fluoride, was provided at 45 nm.

  Subsequently, a resistance heating boat containing aluminum was heated by energization, and a cathode having a film thickness of 100 nm made of aluminum was attached at a deposition rate of 1 to 2 nm / second.

  Without exposing the substrate attached to the cathode to the atmosphere, the substrate 1 was measured in accordance with ISO 14644-1 under a nitrogen atmosphere, the measured cleanliness was class 5, the dew point temperature was −80 ° C. or less, and the oxygen concentration was 0.8 ppm. Moved to the glove box.

  Sealing was performed with a glass sealing can to which barium oxide, which is a water retentive agent, was attached, and the device 101 was manufactured.

  Barium oxide, a water replenisher, is a high-purity barium oxide powder made by Aldrich, and is attached to a glass sealing can with a fluororesin semi-permeable membrane (Microtex S-NTF8031Q made by Nitto Denko) with an adhesive. Were prepared and used in advance. An ultraviolet curable adhesive was used for bonding the sealing can and the organic EL element, and both were bonded by irradiating an ultraviolet lamp to produce a sealing element.

  Then, elements 102 to 127 were produced in the same manner as the element 101 except that HT-A or toluene used in the coating solution for the hole injection / transport layer of the element 101 was changed to the materials or solvents shown in Table 1.

  In Example 1, an element was fabricated with the layer configuration shown in Table 2.

<Evaluation method>
The element was caused to emit light using a DC power source (Techsio Corporation DC stabilized power supply PA13-B), and the light emitting surface was observed using a microscope (Mortex Co., Ltd. MS-804, lens A-1468). The number of white spots and black spots on the entire light emitting surface (4 mm square) was measured.

  As can be seen from the results in Table 3, it was found that when a compound having a substituent was applied with a solvent having the substituent, a preferable light emitting surface was obtained. Moreover, it turns out that the effect in a cyano group is high as a substituent.

Example 2
<< Production of Organic EL Element 201 >>
In the same manner as in Example 1, the substrate was cleaned, and the measured cleanliness was transferred to a clean booth of class 5 in accordance with ISO 14644-1 in the atmosphere. This substrate was attached to a commercially available spin coater, and a PEDOT dispersion (Baytron PI4083 manufactured by HC Starlk) was diluted twice with ultrapure water and applied under the conditions of 4000 rpm and 30 seconds. Further, this substrate was heated at 200 ° C. for 30 minutes in the atmosphere to provide a hole injection layer. The film thickness was 20 nm when it apply | coated and measured on the conditions with the board | substrate prepared separately.

  This substrate was transferred to a glove box under a nitrogen atmosphere in accordance with ISO 14644-1, the measured cleanliness was class 5, the dew point temperature was −80 ° C. or lower, and the oxygen concentration was 0.8 ppm.

  Hereinafter, the element No. In the same manner as in Device No. 201 was produced. Furthermore, it changed to the structure of Table 4, and changed to the solvent of Table 5, and element No. 202 was produced. In addition, element No. 203 and 204 were prepared in the same manner using HT-B as the hole injecting and transporting layer, using the structures shown in Table 4 and the solvents shown in Table 5.

  Each element was evaluated in the same manner as in Example 1. The results are shown in Table 5.

  From Table 5, the effect of applying a compound having a CN group as a substituent with an organic solvent having a CN group is significant when the layer is adjacent to the electrode on the substrate (sample No. 204). Recognize.

  Moreover, when PEDOT (which has a sulfonic acid group) is applied with water (sample No. 201), it can also be seen that no effect appears.

Example 3
(Preparation of organic EL element 301)
The substrate 1 was transferred to a glove box in a nitrogen atmosphere according to JIS B9920, with a measured cleanliness of class 100, a dew point temperature of −80 ° C. or lower, and an oxygen concentration of 0.8 ppm.

  In the glove box, prepare the hole injection layer coating solution as follows, apply it with a spin coater under conditions of 1500 rpm and 30 seconds, and further heat at 180 ° C. for 30 minutes to provide the hole injection layer It was. The film thickness was 20 nm when it apply | coated and measured on the conditions with the board | substrate prepared separately.

(Coating solution for hole injection layer)
Acetonitrile 70g
30 g of cyclohexanone
HIL-A 0.5g
Subsequently, the coating liquid for positive hole transport layers was prepared as follows, and it apply | coated on the conditions of 1500 rpm and 30 seconds with a spin coater. This substrate was heated to 150 ° C. for 10 seconds, and with heating, 30 mW / cm ² of ultraviolet light was applied for 10 seconds using a high pressure mercury lamp (OHD-110M-ST manufactured by Oak Manufacturing Co., Ltd.). Furthermore, it heated at 120 degreeC for 30 minutes, and provided the positive hole transport layer. The film thickness was 20 nm when it apply | coated and measured on the conditions with the board | substrate prepared separately.

(Coating liquid for hole transport layer)
Toluene 100g
HT-E 0.5g
Next, a light emitting layer coating solution was prepared as described below, and applied with a spin coater under the conditions of 2000 rpm and 30 seconds. Furthermore, it heated at 150 degreeC for 30 minutes, and provided the light emitting layer. The film thickness was 40 nm when it apply | coated and measured on the conditions with the board | substrate prepared separately.

(Light emitting layer coating solution)
Toluene 100g
H-B 1g
Ir-A 0.11 g
Subsequently, the coating liquid for electron carrying layers was prepared as follows, and it apply | coated on the conditions of 1500 rpm and 30 seconds with a spin coater. Furthermore, it heated at 150 degreeC for 30 minutes, and the object for electron carrying layers was provided. The film thickness was 30 nm when it apply | coated and measured on the conditions with the board | substrate prepared separately.

(Coating liquid for electron transport layer)
1-butanol 100g
ET-B 0.75g
Next, the substrate provided up to the electron transport layer was moved to a vapor deposition machine without being exposed to the atmosphere, and the pressure was reduced to 4 × 10 ⁻⁴ Pa.

  Note that cesium fluoride was placed in a tantalum resistance heating boat in a tantalum resistance heating boat, and aluminum was placed in a tungsten resistance heating boat and attached in a vapor deposition machine.

  First, a resistance heating boat containing cesium fluoride was energized and heated, and an electron injection layer made of cesium fluoride was provided with a thickness of 3 nm on the substrate.

  Subsequently, a resistance heating boat containing aluminum was heated by energization, and a cathode having a film thickness of 100 nm made of aluminum was attached at a deposition rate of 1 to 2 nm / second.

  Without exposing the substrate attached to the cathode to the atmosphere, the substrate 1 was measured in accordance with ISO 14644-1 under a nitrogen atmosphere, the measured cleanliness was class 5, the dew point temperature was −80 ° C. or less, and the oxygen concentration was 0.8 ppm. Moved to the glove box.

  Sealing is performed in the same manner as the fabrication of the element 101, and the element No. 301 was produced.

  Hereinafter, element No. In the same manner except that the compound and solvent used in the hole injection layer coating solution in the production of 301 were changed to the materials shown in Table 7, the device no. 302-308 were produced. Table 6 shows the layer structure, and Table 7 shows the materials used.

  It can be seen that excellent performance can be obtained by using the compound for a hole injection layer having a CN group as a substituent and dissolving and coating in a solvent having a CN group.

  In addition, element No. When the residual amount of the solvent remaining in the hole injection layer formed by 307 and 308 was measured, it was found that better performance can be obtained by containing acetonitrile in the range of 1 ppm to 1000 ppm, compared with toluene. I understood.

  Further, when looking at the number of substituents for the carbon atom of the mother nucleus of the compound, it is preferably 0.1 or more and 0.6 or less, and more preferably 0.1 or more and 0.2 or less. It was.

  The residual solvent can be measured by taking a sample of a certain area and measuring it by gas chromatography.

  Furthermore, element No. For the compound used in the hole injection layer coating solution in the production of 301, a ferrocene compound described in JP-A-6-025658, a starbust type compound described in JP-A-10-233287, Triarylamine type compounds described in JP-A No. 2000-068058 and JP-A No. 2004-6321, sulfur-containing ring-containing compounds described in JP-A No. 2002-1171979, US Pat. A solvent having the same substituent corresponding to each compound in place of the hexaazatriphenylene compound described in Japanese Patent No. 0158242, US 2006-0251922, JP-A-2006-49393, etc. Other than that, the device was fabricated in the same manner, and the same excellent effect was obtained. It was.

Claims (5)

A method for producing an organic electroluminescent element by a wet method,
A compound having a substituent containing a heteroatom with respect to one carbon atom of the nucleus in the range of 0.10 to 0.60 is dissolved in an organic solvent having the same substituent as the substituent and applied. A method for producing an organic electroluminescent element, comprising forming a film. The method for producing an organic electroluminescent element according to claim 1, wherein the layer formed of the organic solvent having a substituent is a layer adjacent to the electrode. 3. The method for producing an organic electroluminescent element according to claim 1, wherein the organic solvent having the substituent is mixed with another solvent. The method for producing an organic electroluminescent element according to claim 3 , wherein the content of the organic solvent having a substituent is 30% or more based on the total amount of the organic solvent. An organic electroluminescence device manufactured by the manufacturing method according to claim 1.