JP2006307101A - Silicon-containing polymer, method for producing the same, polymer composition for organic electroluminescent element and organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new silicon-containing polymer having excellent solubility in solvents, readily forming a thin film and useful as a material for an organic EL (electroluminescent) element, to provide a method for producing the silicon-containing polymer, to provide a polymer composition for the organic EL element affording the organic EL element having excellent luminescent characteristics and to provide the organic EL element. <P>SOLUTION: The silicon-containing polymer is composed of a specific repeating unit and is used as the material for the organic EL element. The polymer composition for the organic EL element comprises a polymer component composed of the silicon-containing polymer and a complex component composed of a triplet luminescent metal complex compound. Furthermore, the organic EL element has a luminescent layer formed of the polymer composition for the organic EL element. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a silicon-containing polymer used as a material for an organic electroluminescent element, a method for producing the same, a polymer composition for an organic electroluminescent element, and an organic electroluminescent element.

An organic electroluminescence element (hereinafter also referred to as “organic EL element”) can be driven by a DC voltage, is a self-luminous element, has a wide viewing angle and high visibility, and a response speed. Therefore, it is expected as a next-generation display element and has been actively researched.
As such an organic EL element, one having a single layer structure in which a light emitting layer made of an organic material is formed between an anode and a cathode, one having a hole transport layer between the anode and the light emitting layer, A multilayer structure such as one having an electron transport layer between a cathode and a light emitting layer is known. Each of these organic EL devices emits light by recombination of electrons injected from the cathode and holes injected from the anode in the light emitting layer.

  In such an organic EL device, as a method for forming a functional organic material layer such as a light-emitting layer, a charge transport layer for transporting charges such as electrons or holes, a dry method in which an organic material is formed by vacuum deposition, and an organic There is known a wet method in which a solution in which a material is dissolved is applied and dried. Among these, the dry method has a complicated process and is difficult to be applied to mass production, and has a limit in forming a layer having a large area. On the other hand, in the wet method, the process is relatively simple and can be applied to mass production. For example, a functional organic material layer having a large area can be easily formed by an inkjet method. Therefore, the wet method has the advantages described above, and is advantageous compared to the dry method.

On the other hand, the light emitting layer of the organic EL element is required to have high light emission efficiency. Recently, in order to realize high luminous efficiency, attempts have been made to use energy of triplet state molecules as an excited state for light emission of the organic EL element.
Specifically, according to the organic EL element having such a configuration, it is possible to obtain an external quantum efficiency of 8% exceeding 5% which has been conventionally considered as the limit value of the external quantum efficiency of the organic EL element. (For example, refer nonpatent literature 1.).
However, this organic EL element is composed of a low molecular weight material, and is formed by a dry method such as a vapor deposition method, so that the physical durability and the thermal durability are small. There is.

“Applied Physics Letters”, 1999, vol. 75, p. 4

The present invention has been made on the basis of the circumstances as described above, and the object thereof is excellent in solubility in a solvent, can easily form a thin film, and is useful as a material for an organic electroluminescence element. The object is to provide a silicon-containing polymer.
Another object of the present invention is to provide a method for producing a silicon-containing polymer that is excellent in solubility in a solvent, can be easily formed into a thin film, and is useful as a material for an organic electroluminescence device.
Still another object of the present invention is to provide a polymer composition for an organic electroluminescence device from which an organic electroluminescence device having excellent light emission characteristics can be obtained, and an organic electroluminescence device.

  The silicon-containing polymer of the present invention comprises a repeating unit represented by the following general formula (1) and is used as a material for an organic electroluminescence element.

[Wherein, R ¹ and R ² each independently represents an optionally substituted alkyl group having 1 to 20 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. ]

  The method for producing a silicon-containing polymer of the present invention is characterized in that the above-mentioned silicon-containing polymer is obtained by polymerizing a monomer represented by the following general formula (2) in the presence of a nickel catalyst. .

Wherein, R ¹ and R ² independently represent the carbon atoms which may be have 1 to 20 substituents on the alkyl group or an optionally substituted aryl group having 6 to 20 carbon atoms, X ¹ and X ² are each independently a chlorine atom, a bromine atom, an iodine atom or R ³ —SO ₃ — (wherein R ³ represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms). Group. ]

  The polymer composition for an organic electroluminescence device of the present invention is characterized by containing a polymer component composed of the above silicon-containing polymer and a complex component composed of a triplet light-emitting metal complex compound.

  The organic electroluminescent element of this invention has the light emitting layer formed with said polymer composition for organic electroluminescent elements, It is characterized by the above-mentioned.

  The organic electroluminescent element of the present invention preferably comprises a hole block layer.

The silicon-containing polymer of the present invention is useful as a material for an organic electroluminescence device because it is excellent in solubility in a solvent and can easily form a thin film and has good carrier transportability.
Moreover, according to the manufacturing method of the silicon-containing polymer of this invention, said silicon-containing polymer can be manufactured.

  In addition, according to the polymer composition for an organic electroluminescence device of the present invention, the triplet luminescent metal complex compound is contained as the complex component, and the above silicon-containing polymer is contained as the polymer component. Therefore, an organic electroluminescence device having excellent light emission characteristics can be obtained.

  Furthermore, according to the organic electroluminescent device of the present invention, excellent light emission characteristics due to triplet light emission can be achieved by using the polymer composition for an organic electroluminescent device as a material for the light emitting layer.

  Hereinafter, embodiments of the present invention will be described in detail.

<Silicon-containing polymer>
The silicon-containing polymer of the present invention comprises a repeating unit represented by the general formula (1) (hereinafter also referred to as “specific repeating unit”), and is represented by the general formula (2). A polymer (hereinafter also referred to as “specific silicon-containing polymer”) obtained by polymerizing a monomer (hereinafter also referred to as “specific silicon-containing monomer”).

In General Formula (1), R ¹ and R ² each independently represents an optionally substituted alkyl group having 1 to 20 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms, R ¹ and R ² may be the same or different from each other, but are preferably the same.

Examples of the alkyl group having 1 to 20 carbon atoms representing the group R ¹ and the group R ² include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an s-butyl group, and a t-butyl group. Group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group Group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group and the like.

Also, an aryl group having 6 to 20 carbon atoms of the proximal R ¹ and R ² radicals may be those containing a fluorine atom as a substituent, such as phenyl group, a benzyl group, a tolyl group, a naphthyl group, a biphenyl Group, methoxyphenyl group, ethoxyphenyl group, propoxyphenyl group, butoxyphenyl group, pentyloxyphenyl group, hexyloxyphenyl group, hepsyloxyphenyl group, octyloxyphenyl group, nonyloxyphenyl group, decyloxyphenyl group, un Examples include decyloxyphenyl group, dodecyloxyphenyl group, tridecyloxyphenyl group, tetradecyloxyphenyl group, fluorophenyl group, perfluorophenyl group, trifluorophenyl group, and the like.

The groups R ¹ and R ² are preferably methyl, ethyl, phenyl or tolyl groups.

  As for the molecular weight of the specific silicon-containing polymer, the polystyrene-equivalent number average molecular weight (Mn) by gel permeation chromatography is preferably 500 to 500,000, and the same weight average molecular weight (Mw) is 800 to 1,000,000. preferable.

The specific silicon-containing polymer has an LUMO (low unoccupied molecular orbital) energy level of −3.0 to −1.5 eV, and a HOMO (high occluded molecular orbital) energy level of −7.0 to −5. 0.0eV is preferred.
When these energy levels are outside the above ranges, good luminance and luminous efficiency cannot be obtained for the organic EL element when used as a material for an organic EL element.

  The specific silicon-containing polymer can be produced by a method in which a specific silicon-containing monomer is polymerized in the presence of a nickel catalyst.

In the general formula (2) showing a specific silicon-containing monomer used as a raw material, X ¹ and X ² are each independently represented by a chlorine atom, a bromine atom, an iodine atom or R ³ —SO ₃ —. Group (hereinafter also referred to simply as “R ³ SO ₃ group”), and X ¹ and X ² may be the same as or different from each other. Preferably there is.

In the R ³ SO ₃ group, R ³ represents an optionally substituted alkyl group having 1 to 6 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms.

The alkyl group having 1 to 6 carbon atoms representing the group R ³ may contain a fluorine atom as a substituent, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl. Group, s-butyl group, t-butyl group, n-pentyl group, n-hexyl group, trifluoromethyl group and the like.

Also, an aryl group having 6 to 20 carbon atoms a group R ³ may be one containing a fluorine atom as a substituent, such as phenyl group, a benzyl group, a tolyl group, a naphthyl group, a biphenyl group, methoxyphenyl Group, ethoxyphenyl group, propoxyphenyl group, butoxyphenyl group, pentyloxyphenyl group, hexyloxyphenyl group, hepsyloxyphenyl group, octyloxyphenyl group, nonyloxyphenyl group, decyloxyphenyl group, undecyloxyphenyl group , Dodecyloxyphenyl group, tridecyloxyphenyl group, tetradecyloxyphenyl group, fluorophenyl group, perfluorophenyl group, trifluorophenyl group and the like.

Groups X ¹ and group X ² is a chlorine atom, a bromine atom, an iodine atom, R ³ is a methyl group, a trifluoromethyl group, a phenyl group, or a p- tolyl or p- fluorophenyl group R ³ SO _Three groups are preferred.

Examples of the nickel catalyst include nickel (II) dichloride, bis (triphenylphosphine) nickel (II) dichloride, {1,1′-bis (diphenylphosphino) ferrocene} nickel (II) dichloride, {1,2-bis (Diphenylphosphino) ethane} nickel (II) dichloride, {1,3-bis (diphenylphosphino) propane} nickel (II) dichloride, bis (2,4-pentanedionate) nickel (II), bis (hexa Fluoroacetylacetonato) nickel (II), bis (1,5-cyclooctadienyl) nickel (0) (NiCOD), or the like can be used.
Of these, nickel (II) dichloride, bis (triphenylphosphine) nickel (II) dichloride, and bis (1,5-cyclooctadienyl) nickel (0) (NiCOD) are preferred.

  It is preferable that the usage-amount of a nickel catalyst is 0.1-10 mass parts with respect to 100 mass parts of specific silicon containing monomers, More preferably, it is 1-6 mass parts.

An appropriate solvent is used for the polymerization reaction of the specific silicon-containing monomer.
Solvents include aromatic hydrocarbons such as benzene, toluene, xylene and mesitylene, ethers such as tetrahydrofuran, dioxane, diethyl ether, diethoxyethane and anisole, esters such as ethyl acetate, propyl acetate and butyl acetate, cyclohexanone, Ketones such as methyl ethyl ketone and methyl isobutyl ketone, amides such as N, N-dimethylformamide, N, N-dimethylacetamide and 1-methyl-2-pyrrolidone can be used. Of these, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, and 1-methyl-2-pyrrolidone are preferable.

  It is preferable that the usage-amount of a solvent is 50-10000 mass parts with respect to 100 mass parts of specific silicon containing monomers, More preferably, it is 200-2000 mass parts.

  In such a production method, the polymerization reaction of the specific silicon-containing monomer is preferably performed in an atmosphere of an inert gas such as nitrogen or argon. Specific reaction conditions include a reaction temperature of 0 It may be selected from ˜250 ° C., preferably 50 ° C. to 150 ° C., and the reaction time is 0.1 to 100 hours, preferably 1 to 30 hours.

  Moreover, a phosphine ligand, zinc, 2, 2-bipyridine, etc. can be added to the polymerization reaction of a specific silicon-containing monomer as necessary.

  Examples of the phosphine ligand include tri-n-butylphosphine, tricyclohexylphosphine, dicyclohexylphenylphosphine, cyclohexyldiphenylphosphine, ethyldiphenylphosphine, diethylphenylphosphine, methyldiphenylphosphine, diphenyl-n-propylphosphine, methoxydiphenylphosphine, Ethoxydiphenylphosphine, triphenylphosphine, tris (2-methylphenyl) phosphine, tris (3-methylphenyl) phosphine, tris (4-methylphenyl) phosphine, tris (4-methoxyphenyl) phosphine, tris (2,6- Dimethoxyphenyl) phosphine, diphenylphosphinobenzene-3-sulfonic acid sodium salt, 4- (dimethylamino) Phenyldiphenylphosphine, diphenyl-2-pyridylphosphine, tri (2-furyl) phosphine, tri (2-thienyl) phosphine, bis (diphenylphosphino) methane, 1,2-bis (dimethylphosphino) ethane, 1,2 -Bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, 1,4-bis (diphenylphosphino) butane, 1,1'-bis (diphenylphosphino) ferrocene, and the following formula ( A)-the compound represented by the following formula (I) is mentioned. Of these, triphenylphosphine is preferred.

  The specific silicon-containing polymer has excellent solubility in a solvent, and a coating solution for forming a thin film can be easily prepared. Therefore, a thin film can be easily formed with the coating solution. Can do. Therefore, the silicon-containing polymer of the present invention is useful as a material for an organic EL device.

  In addition, since the specific silicon-containing polymer has good carrier transportability, it is suitably used as a material constituting the light-emitting layer of the organic EL element by combining with a light-emitting material having phosphorescence, for example. It is done.

<Polymer composition for organic EL device>
The polymer composition for an organic EL device of the present invention comprises a polymer component composed of the specific silicon-containing polymer and a complex component composed of a triplet light-emitting metal complex compound.

  Examples of the triplet light-emitting metal complex compound constituting the complex component include iridium complex compounds, platinum complex compounds, palladium complex compounds, rubidium complex compounds, osmium complex compounds, rhenium complex compounds, etc. Among these, iridium Complex compounds are preferred.

Examples of the iridium complex compound constituting the complex component include iridium, phenylpyridine, phenylpyrimidine, bipyridyl, 1-phenylpyrazole, 2-phenylquinoline, 2-phenylbenzothiazole, 2-phenyl-2-oxazoline, 2,4- A complex compound with a nitrogen atom-containing aromatic compound such as diphenyl-1,3,4-oxadiazole, 5-phenyl-2- (4-pyridyl) -1,3,4-oxadiazole or a derivative thereof; Can be used.
Specific examples of such iridium complex compounds include compounds represented by the following general formula (3) to the following general formula (5).

In the above general formulas (3) to (5), R ⁴ and R ⁵ each represent a substituent composed of a fluorine atom, an alkyl group or an aryl group, and may be the same or different from each other. May be. x is an integer of 0 to 4, and y is an integer of 0 to 4.

In the above, specific examples of the alkyl group related to the substituents R ⁴ and R ⁵ include a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an n-butyl group, an isobutyl group, a hexyl group, and an octyl group. be able to.
Specific examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a biphenyl group, and a naphthyl group.

  Among these, it is particularly preferable to use an iridium complex compound represented by the general formula (3) (hereinafter also referred to as “specific iridium complex compound”).

  This specific iridium complex compound is usually synthesized by reacting a compound represented by the following general formula (6) and a compound represented by the following general formula (7) in the presence of a polar solvent. However, it is important that the content of the specific impurity compound represented by the following general formula (8) generated in that case is 1000 ppm or less.

In General Formula (6) to General Formula (8), R ⁴ and R ⁵ are the same as those in General Formula (3). x is an integer of 0 to 4, and y is an integer of 0 to 4.

  The specific iridium complex compound in which the content of the specific impurity compound is 1000 ppm or less can be obtained by purifying the reaction product obtained from the synthesis reaction.

  In a specific iridium complex compound, when the content of the specific impurity compound exceeds 1000 ppm, the light emission performance of the specific iridium complex compound is hindered, and thus an organic EL element having high emission luminance is obtained. It becomes difficult.

  The content ratio of the complex component in the polymer composition for an organic EL device of the present invention is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the polymer component. Part. When the content ratio of the complex component is too small, it may be difficult to obtain sufficient light emission. On the other hand, when the ratio of the complex component is excessive, a phenomenon of concentration quenching in which the brightness of light emission decreases instead may occur.

  An arbitrary additive such as a charge transporting compound can be added to the polymer composition for an organic EL device of the present invention as necessary.

  As the charge transporting compound, a compound having charge transporting property represented by the following formula (A-1) to the following formula (A-10), represented by the following formula (A-1) to the following formula (A-20). And a compound having a hole transport property represented by the following formula (U-1) to the following formula (U-34).

  Here, in the formula (A-16), Y represents any one of groups represented by the following formulas (a) to (c).

  The addition amount of the charge transporting compound in the polymer composition for organic EL devices of the present invention is preferably 0 to 70 mol% with respect to 100 mol% of the polymer component.

  The polymer composition for organic EL devices of the present invention is usually prepared as a composition solution by dissolving a polymer component composed of the specific silicon-containing polymer and the complex component in an appropriate organic solvent. The Then, the composition solution is applied to the surface of the substrate on which the light emitting layer is to be formed, and an organic solvent is removed from the obtained coating film, thereby forming a light emitting layer in the organic EL element. it can.

Here, the organic solvent for preparing the composition solution is not particularly limited as long as it can dissolve the polymer component and the complex component to be used, and specific examples thereof include toluene, xylene, mesitylene and the like. Aromatic hydrocarbon solvents, halogenated hydrocarbons such as chloroform, chlorobenzene, tetrachloroethane, amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, 1-methyl-2-pyrrolidone, cyclohexanone, lactic acid Examples include ethyl, propylene glycol methyl ether acetate, ethyl ethoxypropionate, and methyl amyl ketone. These organic solvents can be used alone or in combination of two or more.
Among these, it is preferable to use an organic solvent having an appropriate evaporation rate, specifically, an organic solvent having a boiling point of about 70 to 200 ° C. in that a thin film having a uniform thickness can be obtained.

The use ratio of the organic solvent varies depending on the types of the polymer component and the complex component, but is usually a ratio in which the total concentration of the polymer component and the complex component in the composition solution is 0.5 to 10% by mass.
As a means for applying the composition solution, for example, a spin coating method, a dipping method, a roll coating method, an ink jet method, a printing method, or the like can be used.
Although the thickness of the light emitting layer formed is not specifically limited, Usually, 10-200 nm, Preferably it selects in the range of 30-100 nm.

  According to such a polymer composition for an organic EL device, an organic electroluminescence device having a light emitting layer that emits light with sufficiently high light emission luminance can be obtained, and the light emitting layer can be obtained by a wet method such as an inkjet method. It can be formed easily.

<Organic EL device>
FIG. 1 is an explanatory cross-sectional view showing an example of the configuration of the organic EL element of the present invention.
In the organic EL element of this example, an anode 2 as an electrode for supplying holes is provided on a transparent substrate 1 by, for example, a transparent conductive film, and a hole injecting and transporting layer 3 is provided on the anode 2. A light emitting layer 4 is provided on the hole injection transport layer 3, a hole block layer 8 is provided on the light emitting layer 4, an electron injection layer 5 is provided on the hole block layer 8, and the electron injection layer 5 is provided on the hole injection layer 5. A cathode 6 which is an electrode for supplying electrons is provided. The anode 2 and the cathode 6 are electrically connected to a DC power source 7.

In this organic EL element, as the transparent substrate 1, a glass substrate, a transparent resin substrate, a quartz glass substrate, or the like can be used.
As a material constituting the anode 2, a transparent material having a high work function, for example, 4 eV or more is preferably used. Here, the work function refers to the minimum work required to extract electrons from a solid in a vacuum. For example, an ITO (Indium Tin Oxide) film, a tin oxide (SnO ₂ ) film, a copper oxide (CuO) film, or a zinc oxide (ZnO) film can be used as the anode 2.

  The hole injection transport layer 3 is provided to efficiently supply holes to the light emitting layer 4 and has a function of receiving holes from the anode 2 and transporting them to the light emitting layer 4. Is. As a material constituting the hole injecting and transporting layer 3, for example, a charge injecting and transporting material such as poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate can be suitably used. Moreover, the thickness of the hole injection transport layer 3 is, for example, 10 to 200 nm.

  The light emitting layer 4 has a function of combining electrons and holes and emitting the binding energy as light, and the light emitting layer 4 is formed of the above polymer composition for organic EL elements. . Although the thickness of the light emitting layer 4 is not specifically limited, Usually, it selects in the range of 5-200 nm.

  The hole blocking layer 8 suppresses intrusion of holes supplied to the light emitting layer 4 through the hole injecting and transporting layer 3 into the electron injecting layer 5, and recombines holes and electrons in the light emitting layer 4. It has a function of promoting and improving luminous efficiency.

Examples of the material constituting the hole blocking layer 8 include 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (basocproin: BCP) represented by the following formula (1), and the following formula (2). 1,3,5-tri (phenyl-2-benzimidazolyl) benzene (TPBI) represented by the formula can be preferably used.
Moreover, the thickness of the hole block layer 8 is 10-30 nm, for example.

  The electron injection layer 5 has a function of transporting electrons received from the cathode 6 to the light emitting layer 4 through the hole blocking layer 8. As a material constituting the electron injection layer 5, it is preferable to use a co-evaporation system (BPCs) of a bathophenanthroline-based material and cesium, and as other materials, an alkali metal and a compound thereof (for example, lithium fluoride, oxide) Lithium), alkaline earth metals and compounds thereof (eg, magnesium fluoride, strontium fluoride), and the like can be used. The thickness of this electron injection layer 5 is, for example, 0.1 to 100 nm.

As a material constituting the cathode 6, a material having a small work function, for example, 4 eV or less is used. As a specific example of the cathode 6, a metal film made of aluminum, calcium, magnesium, indium, or the like, or an alloy film of these metals can be used.
Although the thickness of the cathode 6 changes with kinds of material, it is 10-1000 nm normally, Preferably it is 50-200 nm.

In the present invention, the organic EL element is manufactured as follows, for example.
First, the anode 2 is formed on the transparent substrate 1.
As a method of forming the anode 2, a vacuum deposition method, a sputtering method, or the like can be used. A commercially available material in which a transparent conductive film such as an ITO film is formed on the surface of a transparent substrate such as a glass substrate can also be used.

A hole injection transport layer 3 is formed on the anode 2 thus formed.
As a method for forming the hole injection transport layer 3, specifically, a hole injection transport layer forming liquid is prepared by dissolving the charge injection transport material in an appropriate solvent. A method of forming the hole injection transport layer 3 by applying to the surface of the anode 2 and subjecting the obtained coating film to solvent removal treatment can be used.

Next, using the polymer composition for an organic EL device of the present invention as a light emitting layer forming liquid, this light emitting layer forming liquid is applied onto the hole injection transport layer 3, and the obtained coating film is heat-treated to emit light. Layer 4 is formed.
As a method for applying the light emitting layer forming liquid, a spin coating method, a dip method, an ink jet method, a printing method, or the like can be used.

  Then, a hole blocking layer 8 is formed on the light emitting layer 4 thus formed, an electron injection layer 5 is formed on the hole blocking layer 8, and further on the electron injection layer 5. By forming the cathode 6, an organic EL element having the configuration shown in FIG. 1 can be obtained.

  In the above, as a method of forming the hole block layer 8, the electron injection layer 5, and the cathode 6, a dry method such as a vacuum evaporation method can be used.

In the above organic EL element, when a DC voltage is applied between the anode 2 and the cathode 6 by the DC power source 7, the light emitting layer 4 emits light, and this light is emitted from the hole injection transport layer 3, the anode 2. Then, the light is emitted to the outside through the transparent substrate 1.
According to the organic EL device having such a configuration, since the light emitting layer 4 is formed of the above polymer composition for organic EL devices, high light emission luminance can be obtained.

  Further, since the hole blocking layer 8 is provided, the coupling between the holes from the anode 2 and the electrons from the cathode 2 is realized with high efficiency, and as a result, high light emission luminance and light emission efficiency can be obtained.

  Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

<Synthesis example 1 of specific silicon-containing monomer>
To a 500 ml three-necked flask, 10.00 g of 1,4-dibromobenzene was added, and after deaeration treatment and nitrogen substitution, the entire amount was dissolved in 150 ml of diethyl ether. After cooling this reaction system to 0 ° C. in an ice bath, 27.5 ml of a 1.54M n-butyllithium hexane solution was added dropwise and stirred for 2 hours, and then 2.5 ml of dichlorodimethylsilane was added dropwise to react. After returning the system to room temperature, the reaction was carried out by stirring for 6 hours. After completion of the reaction, 100 ml of water was added to the reaction solution, which was transferred to a separatory funnel and shaken vigorously to obtain an organic phase. The obtained organic phase was dried over anhydrous magnesium sulfate for 30 minutes, then the anhydrous magnesium sulfate was removed by filtration, further concentrated by an evaporator, and purified by a silica gel-hexane column to give bis (4-bromophenyl). ) 5.85 g of dimethylsilane (hereinafter also referred to as “monomer (1)”) was obtained. When the purity of this monomer (1) was confirmed by HPLC (high performance liquid chromatography), it was 100%.

<Synthesis example 2 of specific silicon-containing monomer>
To a 500 ml three-necked flask, 10.00 g of 1,4-dibromobenzene was added, and after deaeration treatment and nitrogen substitution, the entire amount was dissolved in 150 ml of diethyl ether. After cooling this reaction system to 0 ° C. in an ice bath, 27.5 ml of a 1.54M n-butyllithium hexane solution was added dropwise and stirred for 2 hours, and then 4.4 ml of dichlorodiphenylsilane was added dropwise to react. After returning the system to room temperature, the reaction was carried out by stirring for 6 hours. After completion of the reaction, 100 ml of water was added to the reaction solution, which was transferred to a separatory funnel and shaken vigorously to obtain an organic phase. The obtained organic phase was dried over anhydrous magnesium sulfate for 30 minutes, then the anhydrous magnesium sulfate was removed by filtration, further concentrated by an evaporator, and purified by a silica gel-hexane column to give bis (4-bromo 7.46 g of phenyl) diphenylsilane (hereinafter also referred to as “monomer (2)”) was obtained. When the purity of this monomer (2) was confirmed by HPLC, it was 100%.

<Example 1>
In a three-necked flask with a volume of 100 ml, 1.000 g of monomer (1), 0.088 g of dichlorobis (triphenylphosphine) nickel, 0.081 g of sodium iodide, 0.354 g of triphenylphosphine, and 0.424 g of zinc Was added, and after deaeration treatment and nitrogen substitution, 5.4 ml of N, N-dimethylacetamide was added, and the mixture was heated and stirred at 80 ° C. for 12 hours. The reaction system was cooled to room temperature, diluted with 10 ml of tetrahydrofuran, the insoluble part was removed by filtration, further concentrated with an evaporator, and then added dropwise to 250 ml of methanol to give a white precipitate in the general formula (1). 0.167 g of a polymer in which R ¹ and R ² are methyl groups (hereinafter also referred to as “polymer (1)”) was obtained. An NMR chart of this polymer (1) is shown in FIG.

  The obtained polymer (1) had a polystyrene-reduced weight average molecular weight of 3,300 as determined by gel permeation chromatography.

Further, the HOMO energy level E _H of the polymer (1) was measured by using a powdered polymer (1) as a sample and using a photoelectron spectrometer “AC-2” (manufactured by Riken Keiki Co., Ltd.). However, it was −5.79 eV.
Furthermore, when the LUMO energy level E _L of the polymer (1) was calculated by the following formula (I), it was −1.85 eV.
In the formula (I), _EG is an energy gap (unit: eV) calculated from the following formula (II).
In the formula (II), h is a Planck constant, c is the speed of light (unit: m / sec), and λ _l is a polymer (1) on a quartz substrate with a solvent (specifically, A thin film having a thickness of 20 to 50 nm is formed by applying a polymer solution dissolved in xylene) by spin coating and removing the solvent by heating the obtained coating film at 150 ° C. for 10 minutes using a hot plate. It is the absorption edge (unit: nm) of the long wavelength side of the absorption spectrum which measured the measured measurement board | substrate with the ultraviolet visible spectrophotometer "U-2010" (made by Hitachi, Ltd.).

(Formula I) E _L = E _H + E _G

(Formula II) E _G = hc / λ _l

<Example 2>
In a three-necked flask with a volume of 100 ml, 1.000 g of monomer (2), 0.088 g of dichlorobis (triphenylphosphine) nickel, 0.081 g of sodium iodide, 0.354 g of triphenylphosphine, and 0.424 g of zinc Was added, and after deaeration treatment and nitrogen substitution, 5.4 ml of N, N-dimethylacetamide was added, and the mixture was heated and stirred at 80 ° C. for 12 hours. The reaction system was cooled to room temperature, diluted with 10 ml of tetrahydrofuran, the insoluble part was removed by filtration, further concentrated with an evaporator, and then added dropwise to 250 ml of methanol to give a white precipitate in the general formula (1). 0.167 g of a polymer in which R ¹ and R ² are phenyl groups (hereinafter also referred to as “polymer (2)”) was obtained. The NMR chart of this polymer (2) is shown in FIG.

  The resulting polymer (2) had a polystyrene-reduced weight average molecular weight of 4,500 as determined by gel permeation chromatography.

  The HOMO energy level and LUMO energy level of the polymer (2) were determined by the same method as in Example 1. As a result, the HOMO energy level was -5.83 eV, and the LUMO energy level was -1. .89 eV.

<Example 3>
(Example of production of organic EL element)
An ITO substrate in which an ITO film is formed on a transparent substrate is prepared, and this ITO substrate is ultrasonically cleaned using a neutral detergent, ultrapure water, isopropyl alcohol, ultrapure water, and acetone in this order, and further UV-ozone (UV / O ₃ ) cleaning was performed.
A poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS) solution was applied onto the cleaned ITO substrate by a spin coating method, and then the obtained coating film having a thickness of 65 nm was applied to nitrogen. A hole injecting and transporting layer was formed by drying at 250 ° C. for 30 minutes in an atmosphere.

Next, 6 mol% of an iridium complex in which x is 0 and y is 0 in the polymer (1) and the general formula (3) is dissolved in xylene as a light emitting layer forming liquid on the surface of the obtained hole injecting and transporting layer. Obtained by applying a polymer composition solution for an organic EL device comprising a composition solution having a concentration of 3% by mass (hereinafter also referred to as “composition solution (1)”) by spin coating. The coating film having a thickness of 40 nm was dried at 150 ° C. for 10 minutes in a nitrogen atmosphere to form a light emitting layer.
Next, the laminate in which the hole injecting and transporting layer and the light emitting layer are laminated in this order on the ITO substrate is fixed in a vacuum device, and then the pressure in the vacuum device is reduced to 1 × 10 ⁻⁴ Pa or less. 1,3,5-tri (phenyl-2-benzimidazolyl) benzene (TPBI) was deposited in a thickness of 30 nm to form a hole blocking layer made of a TPBI film. Next, after forming an electron injection layer made of lithium fluoride film by depositing 0.5 nm of lithium fluoride, a cathode made of calcium / aluminum film is formed by depositing calcium 30 nm and aluminum 100 nm in this order. did. Then, the organic EL element (henceforth "organic EL element (1)") was manufactured by sealing with glass material.

(Characteristic evaluation of organic EL elements)
When the light emitting layer was made to emit light with the ITO film as the anode and the calcium / aluminum film as the cathode, the organic EL element (1) was derived from a specific iridium complex. Light emission with a wavelength of around 515 nm was obtained.
Moreover, about the organic EL element (1), the light emitting layer was made to light-emit, and the maximum light-emission luminance and luminous efficiency were measured. The results are shown in Table 1.

<Example 4>
(Example of production of organic EL element)
In the production example of the organic EL device of Example 3, the polymer (2) is used instead of the polymer (1) which is the material of the light emitting layer, that is, the composition solution (1) is used as the light emitting layer forming liquid. In the polymer (2) and the general formula (3), a composition solution (hereinafter referred to as 3% by mass) obtained by dissolving 6 mol% of a specific iridium complex in which x is 0 and y is 0 in xylene. The organic EL device (hereinafter referred to as “organic EL device (2)”) was prepared in the same manner as in Example 3 except that the polymer composition solution for organic EL devices comprising “Composition solution (2)” was used. Was also manufactured.

(Characteristic evaluation of organic EL elements)
When the light emitting layer was made to emit light using the ITO film as an anode and the calcium / aluminum film as a cathode, the organic EL element (2) was derived from a specific iridium complex. Light emission with a wavelength of around 515 nm was obtained.
Moreover, about the organic EL element (2), the light emitting layer was made to light-emit, and the maximum light emission luminance and luminous efficiency were measured. The results are shown in Table 1.

<Example 5>
(Example of production of organic EL element)
In the production example of the organic EL element of Example 3, the charge transporting compound (hereinafter, also referred to as “PBD”) represented by the formula (A-4) with respect to the composition solution (1) as the light emitting layer forming liquid. )) Was prepared by the same procedure as in Example 3 except that an organic EL element polymer composition solution consisting of a component added as an optional component at a ratio of 50 mol% with respect to the polymer (1) was used. An EL element (hereinafter also referred to as “organic EL element (3)”) was produced.

(Characteristic evaluation of organic EL elements)
With respect to the obtained organic EL element (3), the light emitting layer was caused to emit light using the ITO film as an anode and the calcium / aluminum film as a cathode, and the maximum light emission luminance and light emission efficiency were measured. The results are shown in Table 1.

<Example 6>
(Example of production of organic EL element)
In the production example of the organic EL device of Example 4, PBD was added as an optional component as a light emitting layer forming liquid with respect to the composition solution (2) at a ratio of 50 mol% with respect to the polymer (1). An organic EL element (hereinafter also referred to as “organic EL element (4)”) was produced in the same manner as in Example 4 except that the organic EL element polymer composition solution consisting of the above was used.

(Characteristic evaluation of organic EL elements)
With respect to the obtained organic EL element (4), the light emitting layer was caused to emit light using the ITO film as an anode and the calcium / aluminum film as a cathode, and the maximum light emission luminance and light emission efficiency were measured. The results are shown in Table 1.

It is sectional drawing for description which shows an example of a structure of the organic electroluminescent element of this invention. 1 is an NMR chart relating to the polymer obtained in Example 1. FIG. 3 is an NMR chart relating to the polymer obtained in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Anode 3 Hole injection transport layer 4 Light emitting layer 5 Electron injection layer 6 Cathode 7 DC power supply 8 Hole block layer

Claims (5)

A silicon-containing polymer comprising a repeating unit represented by the following general formula (1) and used as a material for an organic electroluminescence element.

[Wherein, R ¹ and R ² each independently represents an optionally substituted alkyl group having 1 to 20 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. ] A method for producing a silicon-containing polymer, wherein the monomer represented by the following general formula (2) is polymerized in the presence of a nickel catalyst to obtain the silicon-containing polymer according to claim 1.

Wherein, R ¹ and R ² independently represent the carbon atoms which may be have 1 to 20 substituents on the alkyl group or an optionally substituted aryl group having 6 to 20 carbon atoms, X ¹ and X ² are each independently a chlorine atom, a bromine atom, an iodine atom or R ³ —SO ₃ — (wherein R ³ represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms). Group. ]   A polymer composition for an organic electroluminescence device, comprising a polymer component comprising the silicon-containing polymer according to claim 1 and a complex component comprising a triplet light-emitting metal complex compound.   It has a light emitting layer formed with the polymer composition for organic electroluminescent elements of Claim 3, The organic electroluminescent element characterized by the above-mentioned.   The organic electroluminescence device according to claim 4, comprising a hole blocking layer.

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