JP4462016B2 - Diphenylmethane polymer and method for producing the same, polymer composition for organic electroluminescence device, and organic electroluminescence device - Google Patents

Description

  The present invention relates to a novel diphenylmethane polymer useful as a material for an organic electroluminescence device and a method for producing the same. Moreover, this invention relates to the polymer composition for organic electroluminescent elements, 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.

In addition, as an organic EL element using energy such as a triplet state molecule, for example, a composition in which a light emitting layer is formed by a wet method using a composition composed of an iridium complex compound and polyvinyl carbazole has been proposed ( For example, see Patent Document 1.)
However, this organic EL device has a problem that it is inferior in electrochemical stability due to the presence of a vinyl group in the structure of polyvinyl carbazole, and a long service life cannot be obtained.

“Applied Physics Letters”, 1999, vol. 75, p. 4 Japanese Patent Laid-Open No. 2001-257076

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 novel diphenylmethane polymer.
Another object of the present invention is to provide a method for producing a novel diphenylmethane polymer which is excellent in solubility in a solvent, can form a thin film easily, 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 excellent in light emission characteristics and durability can be obtained, and an organic electroluminescence device.

  The diphenylmethane polymer of the present invention is characterized by comprising a repeating unit represented by the following general formula (1).

[Wherein, R ¹ and R ² each independently represent a monovalent aromatic group. ]

In the diphenylmethane polymer of the present invention, R ¹ and R ² in the general formula (1) are preferably groups having a carbazole structure.

In the diphenylmethane polymer of the present invention, R ¹ and R ² in the general formula (1) are preferably groups having a structure represented by the following general formula (2).

[Wherein, R ³ represents a hydrogen atom or a monovalent organic group, and R ⁴ represents a monovalent aromatic group. ]

  The manufacturing method of the diphenylmethane polymer of this invention is characterized by obtaining the said diphenylmethane polymer by polymerizing the monomer represented by following General formula (3) in presence of a peroxide.

[Wherein, R ¹ and R ² each independently represent a monovalent aromatic group. ]

  The polymer composition for an organic electroluminescence device of the present invention is characterized by containing a polymer component composed of the diphenylmethane 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 the 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 diphenylmethane polymer of the present invention is useful as a material for an organic electroluminescence device because it is excellent in solubility in a solvent, can easily form a thin film, and has good carrier transportability.

  According to the manufacturing method of the diphenylmethane polymer of this invention, said diphenylmethane polymer can be manufactured. In this production method, since the monomer as a raw material can be polymerized without using a transition metal catalyst, the reaction product can be easily purified. Coalescence can be easily obtained.

  Further, according to the polymer composition for an organic electroluminescence device of the present invention, the triplet light-emitting metal complex compound is contained as the complex component, and the diphenylmethane polymer is contained as the polymer component. Therefore, an organic electroluminescence device having excellent light emission characteristics and durability can be obtained.

  Furthermore, according to the organic electroluminescent element of the present invention, by using the polymer composition for an organic electroluminescent element as a material of the light emitting layer, it is possible to achieve excellent light emission characteristics and durability by triplet light emission. it can.

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

<Diphenylmethane polymer>
The diphenylmethane polymer of the present invention comprises a repeating unit represented by the above general formula (1) (hereinafter also referred to as “specific repeating unit”), and is represented by a single unit represented by the above general formula (3). It is obtained by polymerizing a monomer (hereinafter also referred to as “specific diphenylmethane monomer”).

The diphenylmethane polymer of the present invention is not limited to those composed of repeating units having the same configuration, and R ¹ and R ² in each repeating unit may be partially or entirely different, but the structure It is preferable that it is a copolymer which consists of 2 or more types of specific repeating units which differ.

In the general formula (1), R ¹ and R ² each independently represent a monovalent aromatic group, and R ¹ and R ² may be the same or different from each other. Are preferably the same as each other.

Specific examples of the monovalent aromatic group representing the group R ¹ and the group R ² include a group having a carbazole structure (hereinafter, also referred to as “carbazole structure-containing group”), represented by the general formula (2). A group having a structure (hereinafter also referred to as “triazole structure-containing group”) is preferable.

In the general formula (2), R ³ represents a hydrogen atom or a monovalent organic group. Examples of the monovalent organic group representing R ³ include a methyl group, a t-butyl group, and a phenyl group. Is mentioned. The group R ³ is preferably a hydrogen atom.
In the general formula (2), R ⁴ represents a monovalent aromatic group, and examples of the monovalent aromatic group representing R ⁴ include a phenyl group and a naphthyl group.

Preferable specific examples of the specific repeating unit constituting the diphenylmethane polymer of the present invention include repeating units represented by the following formulas (1-1) to (1-4).
Here, in the repeating unit represented by the following formula (1-1) and the repeating unit represented by the following formula (1-2), R ¹ and R ² in the general formula (1) are carbazole structure-containing groups. In addition, in the repeating unit represented by the following formula (1-3) and the repeating unit represented by the formula (1-4), R ¹ and R ² in the general formula (1) are triazole structure-containing groups. It is what is.

  Moreover, as a preferable specific example of the copolymer which comprises the diphenylmethane polymer of this invention, the repeating unit represented by following formula (1-1), the repeating unit represented by following formula (1-2), and Is contained at a molar ratio of 1: 1, the repeating unit represented by the following formula (1-1) and the repeating unit represented by the following formula (1-4) are in a molar ratio of 1: 1. What is contained in the ratio is mentioned.

  As for the molecular weight of the diphenylmethane polymer of the present invention, the number average molecular weight (Mn) in terms of polystyrene by gel permeation chromatography is preferably 500 to 500,000.

In addition, the diphenylmethane polymer of the present invention has an LUMO (low unoccupied molecular orbital) energy level of −3.0 to −2.0 eV, and a HOMO (high occluded molecular orbital) energy level of −7.0 to − It is preferably 5.0 eV.
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 diphenylmethane polymer of the present invention can be produced by a method in which a specific diphenylmethane monomer is polymerized in the presence of a peroxide.

  Specific examples of the specific diphenylmethane monomer used as the raw material include compounds represented by the following formulas (3-1) to (3-4).

Further, as the peroxide, di-t-butyl peroxide, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (4,4-di-butylperoxycyclohexyl) propane, t -Hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5 -Di (m-toluoylperoxy) hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5- Di (benzoylperoxy) hexane, t-butylperoxyacetate, 2,2-bis t-butylperoxy) butane, t-butylperoxybenzoate, n-butyl-4,4-bis (t-butylperoxy) valerate, di-t-butylperoxyisophthalate, α, α′-bis ( t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, di-t-butyl peroxide, p -Mentane hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, diisopropylbenzene hydroperoxide, t-butyltrimethylsilyl peroxide, 1,1,3,3-tetra Methyl butyl hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide Side, 2,3-dimethyl-2,3-diphenylbutane, benzoyl peroxide, and the like can be used.
Among these, di-t-butyl peroxide, t-hexyl peroxyisopropyl monocarbonate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-butyl Peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, t-butyl peroxybenzoate, n-butyl-4,4-bis (t-butylperoxy) valerate, Di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, di-t-butylperoxide, 2,5-dimethyl -2,5-di (t-butylperoxy) hexyne-3,1,1 3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide is preferred.

  It is preferable that the usage-amount of a peroxide is 0.5-10 mol with respect to 1 mol of specific diphenylmethane monomers, More preferably, it is 1.0-5.0 mol.

  In such a production method, the peroxide is preferably added directly or diluted with a high boiling point solvent. The dropping of the peroxide to the specific diphenylmethane monomer is preferably performed in a nitrogen atmosphere for the purpose of preventing oxidation. Specific reaction conditions include a reaction temperature of 100 to 350 ° C., preferably 130. What is necessary is just to select from the range of -300 degreeC, More preferably, 150-250 degreeC. After completion of dropping the peroxide, the reaction may be continued for 0 to 10 hours, preferably 0.2 to 5 hours in order to further proceed the polymerization.

  Moreover, a reaction solvent can be used for the polymerization reaction of a specific diphenylmethane monomer, if necessary. As such a reaction solvent, for example, a solvent having a high boiling point such as diphenyl ether is preferably used.

Moreover, in this manufacturing method, the terminal blocker for sealing the terminal of the polymer which is a reaction product obtained by the polymerization reaction of the specific diphenylmethane monomer can also be used.
The end-capping agent may be charged into the polymerization reaction system together with a specific diphenylmethane monomer, or may be added to the reaction product obtained in a nitrogen atmosphere after completion of the polymerization reaction.

  Specifically, end-capping agents include allyl derivatives such as pentene, hexene, heptene, octene, and cyclohexene, aromatic hydrocarbons such as toluene, xylene, diphenylmethane, and triphenylmethane, 2-methylhexane, methylcyclohexane, and the like. A hydrocarbon containing tertiary carbon can be used.

  Further, in this polymerization reaction system, diphenylmethane can be used as a copolymerizable monomer for forming a copolymer together with a specific diphenylmethane monomer within a range that does not affect the light emission characteristics.

  Since the diphenylmethane polymer of the present invention has excellent solubility in a solvent and can easily prepare a coating solution for forming a thin film, it easily forms a thin film with the coating solution. be able to. Therefore, the diphenylmethane polymer of the present invention is useful as a material for an organic EL device.

  In addition, since the diphenylmethane polymer of the present invention has good carrier transportability, it can be suitably used as a material constituting the light emitting layer of an organic EL element by combining with a light emitting material having phosphorescence, for example. Can be used.

<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 above diphenylmethane 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 an iridium complex compound, a platinum complex compound, a palladium complex compound, a rubidium complex compound, an osmium complex compound, and a rhenium complex compound. 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 (4) to general formula (6).

In the above general formulas (4) to (6), R ⁵ and R ⁶ 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 relating to the substituents R ⁵ and R ⁶ 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 (4) (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 (7) and a compound represented by the following general formula (8) 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 (9) generated in that case is 1000 ppm or less.

In General Formula (7) to General Formula (9), R ⁵ and R ⁶ are the same as in General Formula (4). 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.

  Examples of the charge transporting compound include compounds having a charge transporting property represented by the following formulas (A-1) to (A-10), and electrons represented by the following formulas (A-1) to (A-20). Examples thereof include compounds having a transport property and compounds having a hole transport property represented by the following formulas (U-1) to (U-34).

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

  The polymer composition for an organic EL device of the present invention is usually prepared as a composition solution by dissolving a polymer component composed of the above diphenylmethane polymer and the above complex component in an appropriate organic solvent. 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 chloroform, chlorobenzene, tetrachloroethane and the like. Amido solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, 1-methyl-2-pyrrolidone, cyclohexanone, ethyl lactate, 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 recombination of 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 Diphenylmethane Monomer>
In a 500 ml three-necked flask, 20 g of 4,4′-dihydroxydiphenylmethane and 0.610 g of N, N-dimethylaminopyridine were dissolved in 200 ml of pyridine, and the resulting solution was cooled to 0 ° C. in an ice bath. Using a dropping funnel, 50 g of trifluoromethanesulfonyl chloride was added and stirred at room temperature for 12 hours. After completion of the reaction, the solvent was distilled off, 200 ml of chloroform and 200 ml of water were added to the residue, and the chloroform phase was separated by a liquid separation operation. After concentration, column chromatography (developing solvent: hexane / ethyl acetate = 4 / Purification by 1) gave 43 g of 4,4′-bistrifluorosulfonyloxydiphenylmethane. The purity of the 4,4′-bistrifluorosulfonyloxydiphenylmethane was confirmed by HPLC and found to be 100%.

  Subsequently, 20 g of 4,4′-bistrifluorosulfonyloxydiphenylmethane, 17.3 g of carbazole, 0.51 g of di (t-butyl) phosphinobiphenyl, and potassium phosphate 25 were added to a 500 ml three-necked flask equipped with a reflux tube. .6 g and 0.39 g of tris (dibenzylideneacetone) dipalladium were added to sufficiently purge the system with nitrogen, 170 ml of dimethoxyethane was added, and the mixture was reacted at 85 ° C. for 20 hours. After removing insolubles of the obtained reaction solution by filtration, the solvent was distilled off, the residue was dissolved in ethyl acetate, washed with water, concentrated, and then recrystallized to obtain the formula (3 11 g of a diphenylmethane monomer represented by -1) (hereinafter also referred to as “diphenylmethane monomer (1)”) was obtained.

<Synthesis Example 2 of Specific Diphenylmethane Monomer>
In a 100 ml three-necked flask with a reflux tube, 6.7 g of 4,4′-dihydroxydiphenylmethane and 30.2 g of 1-chloro-3,5-di (carbazol-9-yl) -2,4,6-triazine And 700 ml of chloroform were added and stirred, and then the solution obtained by stirring 5.0 g of sodium hydroxide and 3.0 g of benzyl cetylammonium chloride in 14 ml of water was added, and the system was purged with nitrogen. Left for 6 hours. Then, after diluting with 1000 ml of chloroform, separating and washing with water, and drying the organic phase with magnesium sulfate, the magnesium sulfate and insoluble matter were removed by filtration, and the solvent was distilled off to obtain the formula (3-2) 13.0 g of diphenylmethane monomer represented by the following (hereinafter also referred to as “diphenylmethane monomer (2)”) was obtained. When the purity of this diphenylmethane monomer (2) was confirmed by HPLC, it was 100%.

<Synthesis Example 3 of Specific Diphenylmethane Monomer>
In a 500-ml three-necked flask with a reflux tube, 20 g of 4,4′-bistrifluorosulfonyloxydiphenylmethane synthesized in Synthesis Example 1 of a specific diphenylmethane monomer, 24 g of bis (pinacolato) diboron, 1,1 ′ After introducing 1.06 g of bis (diphenylphosphino) -ferrocene palladium dichloride, 0.72 g of 1,1′-bis (diphenylphosphino) -ferrocene, and 12.7 g of potassium acetate, and replacing the system with nitrogen 200 ml of 1,4-dioxane was added and heated to 80 ° C. for 16 hours. The obtained reaction solution was diluted with 300 ml of toluene, and washed twice with 200 ml of saturated brine. The organic phase is dried over magnesium sulfate and concentrated, and then purified by column chromatography (developing solvent: hexane / ethyl acetate = 4/1) to give a compound represented by the following formula (A) (hereinafter, “ Also referred to as “boronic acid compound”). When the purity of this boronic acid compound was confirmed by HPLC, it was 100%.

  In a 300 ml three-necked flask with a reflux tube, 10 g of a boronic acid compound, 18 g of 3- (4-bromophenyl) -4,5-diphenyl-1,2,4-triazole, tetrakis (triphenylphosphine) palladium 0 Then, 50 ml of 2N sodium carbonate aqueous solution and 100 ml of toluene were added and heated at 85 ° C. for 24 hours. The obtained reaction solution was diluted by adding 100 ml of toluene, washed twice with 200 ml of saturated brine, and the organic phase obtained was dried over magnesium sulfate, and then filtered to remove magnesium sulfate and concentrated. And a column (developing solvent: hexane / ethyl acetate = 1/1) to purify the diphenylmethane monomer represented by the formula (3-4) (hereinafter also referred to as “diphenylmethane monomer (3)”). .) 15 g was obtained.

<Synthesis Example 1 of Comparative Polymer (Polyvinylcarbazole)>
A 100 ml three-necked flask equipped with a nitrogen inlet tube and a thermometer was charged with 15 g of N-vinylcarbazole, 0.0125 g of azobisisobutyronitrile and 30 g of distilled dimethylformamide, and bubbled for 15 minutes by blowing nitrogen. Then, the temperature of this system was raised to 80 ° C., and a polymerization treatment was performed for 4 hours. After the polymerization treatment, the obtained reaction product was poured into 400 ml of methanol, the precipitate was filtered off, washed with methanol, and then dried to give polyvinylcarbazole (hereinafter referred to as “Comparative Polymer (1)” as a white powder. "Also called." The weight average molecular weight of the obtained comparative polymer (1) was 30000.

<Example 1>
A three-necked flask with a capacity of 100 ml with a condenser, dropping funnel and thermometer was charged with 3.0 g of diphenylmethane monomer (1) and 3.0 g of diphenylmethane monomer (3), and the temperature was adjusted to 210 ° C. under a nitrogen atmosphere. The mixture was liquefied by heating, and 5.0 g of di (t-butyl) peroxide was added dropwise to the system, and the mixture was heated and stirred at a reaction temperature of 210 ° C. for 2 hours. The solid obtained by cooling the reaction solution to room temperature is dissolved in tetrahydrofuran and precipitated in methanol, whereby the repeating unit represented by the formula (1-1) and the formula (1-4) are represented. 1.8 g of a copolymer (hereinafter also referred to as “diphenylmethane copolymer (1)”) having a molar ratio of 1: 1 is obtained.

  The number average molecular weight of polystyrene conversion by the gel permeation chromatography method of the obtained phenylmethane copolymer (1) was 3000.

In addition, the HOMO energy level E _H of the diphenylmethane copolymer (1) was obtained by using a powder of the diphenylmethane copolymer (1) as a sample, and using a photoelectron spectrometer “AC-2” (manufactured by Riken Keiki Co., Ltd.). It was -5.73 eV when measured using.
Furthermore, when the LUMO energy level E _L of the diphenylmethane copolymer (1) was calculated by the following formula (I), it was −2.24 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 diphenylmethane copolymer (1) solvent (specifically, on a quartz substrate). Is a thin film having a thickness of 20 to 50 nm, in which a polymer solution dissolved in cyclohexanone) is applied by spin coating, and the obtained coating film is heated by a hot plate at 150 ° C. for 10 minutes to remove the solvent. Is an absorption edge (unit: nm) on the long wavelength side of an absorption spectrum measured by an ultraviolet-visible spectrophotometer “U-2010” (manufactured by Hitachi, Ltd.).

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

(Formula II) E _G = hc / λ _l

<Example 2>
In Example 1, except that 3.0 g of diphenylmethane monomer (2) was used instead of diphenylmethane monomer (1), the repetition represented by formula (1-2) was performed in the same manner as in Example 1. 2.0 g of a copolymer (hereinafter also referred to as “diphenylmethane copolymer (2)”) containing a unit and a repeating unit represented by the formula (1-4) in a molar ratio of 1: 1. Obtained.

  The number average molecular weight of polystyrene conversion by gel permeation chromatography method of the obtained diphenylmethane copolymer (2) was 4000.

  Further, the HOMO energy level and the LUMO energy level of the diphenylmethane copolymer (2) were determined in the same manner as in Example 1. As a result, the HOMO energy level was −5.75 eV, and the LUMO energy level was -2.40 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, on the surface of the obtained hole injecting and transporting layer, a diphenylmethane copolymer (1) and 6 mol% of the specific iridium complex represented by the general formula (6) are dissolved in anisole as a light emitting layer forming liquid. The obtained polymer composition solution for organic EL elements (concentration: 3 wt%) was applied by spin coating, and the obtained coating film having a thickness of 40 nm was dried at 150 ° C. for 10 minutes in a nitrogen atmosphere to obtain a light emitting layer Formed.
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. Bathocuproine was deposited to 30 nm to form a hole blocking layer. Next, after forming an electron injection layer by depositing 0.5 nm of lithium fluoride, a cathode was formed by depositing 30 nm of calcium and 100 nm of aluminum in this order. Then, the organic EL element (henceforth "organic EL element (1)") was manufactured by sealing with glass material.

  From the obtained organic EL element (1), light emission having a wavelength of about 515 nm derived from a specific iridium complex was obtained.

Further, the durability of the organic EL element (1) is determined by taking the time until the luminance becomes half of the initial luminance (hereinafter also referred to as “half-life”) as the diphenylmethane copolymer (the light emitting layer material). The organic EL element manufactured by the same method as the organic EL element (1) (hereinafter also referred to as “comparative organic EL element”) except that the comparative polymer (1) was used instead of 1). Evaluated by comparing with time. The results are shown in Table 1 below.
In Table 1, the relative value when the half-life time of the comparative organic EL element is taken as 100 is shown as a value indicating durability.

<Example 4>
In the production example of the organic EL device of Example 3, the organic material was formed by the same method as in Example 3 except that the diphenylmethane copolymer (2) was used instead of the diphenylmethane copolymer (1) as the material of the light emitting layer. An EL element (hereinafter also referred to as “organic EL element (2)”) was produced.
From the obtained organic EL element (2), light emission having a wavelength of around 515 nm derived from a specific iridium complex was obtained.
Moreover, the half-life of the organic EL element (2) was measured, and its durability was evaluated. The results are shown in Table 1.

It is sectional drawing for description which shows the structure in an example of the organic electroluminescent element of this invention.

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 (7)

A diphenylmethane polymer comprising a repeating unit represented by the following general formula (1).

[Wherein, R ¹ and R ² each independently represent a monovalent aromatic group. ] The diphenylmethane polymer according to claim 1, wherein R ¹ and R ² in the general formula (1) are groups having a carbazole structure. The diphenylmethane polymer according to claim 1, wherein R ¹ and R ² in the general formula (1) are groups having a structure represented by the following general formula (2).

[Wherein, R ³ represents a hydrogen atom or a monovalent organic group, and R ⁴ represents a monovalent aromatic group. ] The diphenylmethane polymer according to any one of claims 1 to 3 is obtained by polymerizing a monomer represented by the following general formula (3) in the presence of a peroxide. A method for producing a polymer.

[Wherein, R ¹ and R ² each independently represent a monovalent aromatic group. ]   A polymer component comprising the diphenylmethane polymer according to any one of claims 1 to 3 and a complex component comprising a triplet light-emitting metal complex compound. Polymer composition.   An organic electroluminescence device comprising a light emitting layer formed by the polymer composition for an organic electroluminescence device according to claim 5.   The organic electroluminescence device according to claim 6, comprising a hole blocking layer.

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