JP2020033264A - Triazine compounds having a naphthylene group - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a triazine compound which remarkably improves the life characteristics and luminous efficiency of an organic electroluminescent element. SOLUTION: The triazine compound of the formula (1). (In the formula, Ar1 may be independently substituted with a phenyl group, a naphthyl group or the like; Ar2 may be a pyridyl group or the like; Ar3 may be substituted with a phenyl group or a pyridyl group 3-4. Represents a ring-condensed aromatic hydrocarbon group.) [Selection diagram] FIG.

Description

  The present invention relates to a novel triazine compound useful as a component of an organic electroluminescent device, a material for an organic electroluminescent device containing the same, and an organic electroluminescent device.

  The organic electroluminescent element has a light-emitting layer containing a light-emitting material sandwiched between a hole-transport layer and an electron-transport layer, and furthermore, an anode and a cathode are mounted on the outside of the light-emitting layer. This element uses light emission (fluorescence or phosphorescence) when the generated excitons are deactivated, and is applied to not only small displays but also large televisions and lightings. The hole transport layer is divided into a hole transport layer and a hole injection layer, the light emitting layer is divided into an electron block layer, a light emitting layer and a hole block layer, and the electron transport layer is divided into an electron transport layer and an electron injection layer. It may be configured. In some cases, a co-evaporated film doped with a metal, an organometallic compound, or another organic compound is used as the electron transporting layer or the hole transporting layer of the organic electroluminescent element.

  Conventional organic electroluminescent devices have a higher driving voltage, lower luminous brightness and luminous efficiency, and a significantly shorter device life than inorganic light emitting diodes, and have not been put to practical use in a wide range of fields. In recent organic electroluminescent devices, the above-mentioned drawbacks have been gradually improved, and practical use has begun mainly for mobile applications. However, performance improvement is indispensable for further application expansion, and there is a demand for a material having higher luminous efficiency and longer life. In addition, when used for in-vehicle applications, use at high temperatures is assumed, and the material is required to have a high glass transition temperature.

  Materials for organic electroluminescent devices include the triazine compounds disclosed in Patent Documents 1 and 2. However, further improvements have been demanded in terms of improving the glass transition temperature, the luminous efficiency, and the long life characteristics.

JP 2008-280330 A JP-A-2017-178931

  An object of the present invention is to provide a specific triazine compound that significantly improves the luminous efficiency and lifetime characteristics of an organic electroluminescent device as compared with a conventionally known triazine compound.

  Another object of the present invention is to provide a material for an organic electroluminescent device having excellent luminous efficiency and long life characteristics using the specific triazine compound.

  The present inventors have conducted intensive studies to solve the above problems, and as a result, have used a novel triazine compound represented by the following general formula (1) and having a naphthylene group as an electron transport layer. Organic electroluminescent device, which has a higher glass transition temperature than when a conventionally known material is used, has a remarkably high luminous efficiency, and exhibits a long life, was found to complete the present invention. Reached.

  That is, the present invention relates to a triazine compound represented by the following general formula (1) (hereinafter sometimes referred to as a triazine compound (1)), a material for an organic electroluminescent device containing the same, and an organic electroluminescent device. is there.

(Wherein, Ar ¹ is each independently a phenyl group, a naphthyl group, or a biphenylyl group (these groups may be substituted with a fluorine atom, a methyl group, a phenyl group, a naphthyl group, or a pyridyl group) Ar ² represents a pyridyl group, a quinolyl group, an isoquinolyl group, a pyrazyl group, or a pyrimidyl group, and Ar ³ is a condensed tricyclic ring which may be substituted with a phenyl group or a pyridyl group. Represents a ring aromatic hydrocarbon group.)

  The triazine compound (1) of the present invention can provide an organic electroluminescent device that, when used as an electron transporting layer, has remarkably excellent luminous efficiency and long life characteristics as compared with conventionally known triazine compounds. Furthermore, since the triazine compound (1) of the present invention has a high electron mobility, a reduction in the driving voltage of the organic electroluminescent device can be expected. Therefore, effects such as improvement in driving stability of the organic electroluminescent element and improvement in luminous efficiency are expected. Further, the triazine compound (1) of the present invention has an effect that the glass transition temperature is high due to the contribution of the naphthylene group, and the chemical stability is improved by conjugation expansion.

  Hereinafter, the present invention will be described in detail.

  The present invention relates to a triazine compound represented by the general formula (1).

In the triazine compound represented by the general formula (1) of the present invention, Ar ¹ independently represents a phenyl group, a naphthyl group, or a biphenylyl group, and these groups include a fluorine atom, a methyl group, a phenyl group, It may be substituted with a naphthyl group or a pyridyl group.

  The naphthyl group is not particularly limited, but includes, for example, a 1-naphthyl group and a 2-naphthyl group. Among these, a 2-naphthyl group is preferable in terms of easy synthesis.

  The biphenylyl group is not particularly limited, but examples include a 2-biphenylyl group, a 3-biphenylyl group, and a 4-biphenylyl group. Among them, a 4-biphenylyl group is preferable because the triazine compound represented by the general formula (1) of the present invention has excellent performance in an organic electroluminescent device.

Ar ¹ is preferably independently an unsubstituted phenyl group, an unsubstituted naphthyl group, or an unsubstituted biphenylyl group from the viewpoint that the life of the organic electroluminescent element is excellent. It is more preferably an unsubstituted phenyl group, 2-naphthyl group or 4-biphenylyl group, and more preferably an unsubstituted phenyl group in terms of easy synthesis.

Note that Ar ¹ may be independent as described above. That is, two Ar ¹ may be the same group or different groups. However, it is preferable that the two Ar ¹ be the same group in that the life of the organic electroluminescent element is excellent.

In the triazine compound represented by the general formula (1) of the present invention, Ar ² represents a pyridyl group, a quinolyl group, an isoquinolyl group, a pyrazyl group, or a pyrimidyl group.

Although it is not particularly limited as Ar ² , for example, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-quinolyl group, 3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 6-isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group, Examples thereof include a 2-pyrazyl group, a 2-pyrimidyl group, a 4-pyrimidyl group, and a 5-pyrimidyl group.

Ar ² is preferably a pyridyl group from the viewpoint that the triazine compound represented by the general formula (1) of the present invention has excellent performance in an organic electroluminescent device, and is preferably a 2-pyridyl group, a 3-pyridyl group, or a 4-pyridyl group. And more preferably a pyridyl group.

In the triazine compound represented by the general formula (1) of the present invention, the naphthylene group to which Ar ² is bonded includes a 1,2-naphthylene group, a 1,3-naphthylene group, a 1,4-naphthylene group, a 1,5-naphthylene group. Naphthylene group, 1,6-naphthylene group, 1,7-naphthylene group, 1,8-naphthylene group, 2,3-naphthylene group, 2,6-naphthylene group, any of 2,7-naphthylene group, A 1,4-naphthylene group or a 2,6-naphthylene group is preferable because the triazine compound represented by the general formula (1) of the present invention has excellent performance in an organic electroluminescent device. These are represented by the following chemical structural formulas (I) to (X). As described above, of these, Formula (III) or Formula (IX) is preferable.

(In the formula, * represents a bond to another group in the general formula (1).)
In the triazine compound represented by the general formula (1) of the present invention, Ar ³ represents a condensed aromatic hydrocarbon group having 3 to 4 rings which may be substituted with a phenyl group or a pyridyl group.

  Examples of the condensed aromatic hydrocarbon group having 3 to 4 rings include, but are not particularly limited to, for example, a phenanthryl group, an anthryl group, a pyrenyl group, a triphenylenyl group, or a fluoranthenyl group (these groups are Phenyl group or pyridyl group).

  Among these, unsubstituted phenanthryl group, unsubstituted anthryl group, unsubstituted pyrenyl group, and unsubstituted triphenylenyl group, in that the triazine compound represented by the general formula (1) of the present invention has excellent performance in an organic electroluminescent device. Or an unsubstituted fluoranthenyl group, and more preferably an unsubstituted phenanthryl group.

  Specific examples of the triazine compound represented by the general formula (1) of the present invention include the following (A-1) to (A-36), but the present invention is not limited thereto.

  The triazine compound (1) of the present invention is not particularly limited, but can be used for organic electronic devices such as organic electroluminescent devices and photoelectric devices.

  Hereinafter, an organic electroluminescent device containing the triazine compound (1) of the present invention (hereinafter, sometimes referred to as an organic electroluminescent device of the present invention) will be described.

  The light emitting layer in the organic electroluminescent element refers to a layer which emits light when a current is applied to an electrode composed of a cathode and an anode in a broad sense. Specifically, it refers to a layer containing a fluorescent compound that emits light when an electric current is applied to an electrode composed of a cathode and an anode. Usually, an organic electroluminescent element has a structure in which a light emitting layer is sandwiched between a pair of electrodes.

The organic electroluminescent device of the present invention has a hole transport layer, an electron transport layer, an anode buffer layer, a cathode buffer layer, and the like in addition to the light emitting layer, if necessary, and has a structure sandwiched between a cathode and an anode. Specifically, the structure shown below is mentioned.
(I) anode / light-emitting layer / cathode (ii) anode / hole transport layer / light-emitting layer / cathode (iii) anode / light-emitting layer / electron transport layer / cathode (iv) anode / hole-transport layer / light-emitting layer / electron Transport layer / cathode (v) anode / anode buffer layer / hole transport layer / emission layer / electron transport layer / cathode buffer layer / cathode The triazine compound (1) of the present invention is contained in any of the above-mentioned layers. It may be included in a layer such as a light-emitting layer, an electron transport layer, an electron injection layer, or an electron buffer layer, from the viewpoint of excellent light emission characteristics of the organic electroluminescent device.

  For the light emitting layer in the organic electroluminescent device of the present invention, a conventionally known light emitting material can be used. As a method of forming the light emitting layer, there is a method of forming a thin film by a known method such as an evaporation method, a spin coating method, a casting method, and an LB method.

  The light-emitting layer can be obtained by dissolving a light-emitting material in a solvent together with a binder such as a resin to form a solution, and applying the solution by spin coating or the like to form a thin film. The thickness of the light emitting layer formed in this way is not particularly limited and can be appropriately selected depending on the situation, but is usually in the range of 5 nm to 5 μm.

  Next, other layers constituting an organic electroluminescent device in combination with a light emitting layer, such as a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer, will be described.

  The hole injection layer and the hole transport layer have a function of transmitting holes injected from the anode to the light emitting layer, and the hole injection layer and the hole transport layer are interposed between the anode and the light emitting layer. Thereby, many holes are injected into the light emitting layer at a lower electric field.

  Further, electrons injected from the cathode and transported from the electron injection layer and / or the electron transport layer to the light emitting layer are caused by holes at the interface between the light emitting layer and the hole injection layer or the hole transport layer. The element is accumulated at the interface in the light emitting layer without leaking to the injection layer or the hole transport layer, and becomes an element having excellent light emitting performance such as improved light emitting efficiency.

  The hole injection material and the hole transport material have any of hole injection or transport and electron barrier properties, and may be any of an organic substance and an inorganic substance. Examples of the hole injection material and the hole transport material include a triazole derivative, an oxadiazole derivative, an imidazole derivative, a polyarylalkane derivative, a pyrazoline derivative and a pyrazolone derivative, a phenylenediamine derivative, an arylamine derivative, an amino-substituted chalcone derivative, and oxazole. Derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, conductive polymer oligomers, especially thiophene oligomers, and the like. As the hole injecting material and the hole transporting material, those described above can be used, and porphyrin compounds, aromatic tertiary amine compounds and styrylamine compounds, particularly aromatic tertiary amine compounds may be used. preferable.

  Representative examples of the aromatic tertiary amine compound and styrylamine compound include N, N, N ', N'-tetraphenyl-4,4'-diaminophenyl and N, N'-diphenyl-N, N'. -Bis (m-tolyl)-[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 ′ - -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, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD ), 4,4 ′, 4 ″ -tris [N- (m-tolyl) -N-phenylamino] triphenylamine (MTDATA).

  Further, 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. The hole injection layer and the hole transport layer are formed by thinning the hole injection material and the hole transport material by a known method such as a vacuum evaporation method, a spin coating method, a casting method, and an LB method. Can be formed. The thickness of the hole injection layer and the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm. The hole injecting layer and the hole transporting layer may have a single-layer structure composed of one or more of the above materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

  In the organic electroluminescent device of the present invention, the electron transport layer preferably contains the triazine compound (1) of the present invention.

  The electron transport layer is formed by forming the triazine compound (1) of the present invention and / or another appropriate material by a known thin film forming method such as a vacuum evaporation method, a spin coating method, a casting method, and an LB method. Can be formed. The thickness of the electron transport layer is not particularly limited, but is usually selected in the range of 5 nm to 5 μm. The electron transporting layer preferably contains the triazine compound (1) of the present invention, and may contain a conventionally known electron transporting material, and has a one- or two- or more-layer structure. Alternatively, a laminated structure composed of a plurality of layers having the same composition or different compositions may be used.

  Examples of the electron transporting material include an alkali metal complex, an alkaline earth metal complex, and an earth metal complex. Examples of the alkali metal complex, alkaline earth metal complex, or earth metal complex include lithium 8-hydroxyquinolinato (Liq), zinc bis (8-hydroxyquinolinato), and bis (8-hydroxyquinolinate). Copper, bis (8-hydroxyquinolinato) manganese, tris (8-hydroxyquinolinato) aluminum, tris (2-methyl-8-hydroxyquinolinato) aluminum, tris (8-hydroxyquinolinato) gallium, Bis (10-hydroxybenzo [h] quinolinato) beryllium, bis (10-hydroxybenzo [h] quinolinato) zinc, bis (2-methyl-8-quinolinato) chlorogallium, bis (2-methyl-8-quinolinate) ( o-cresolate) gallium, bis (2-methyl-8-quinolinate) 1-naphthyl Trat aluminum, bis (2-methyl-8-quinolinato) -2-naphthoquinone Trad gallium, and the like.

  In the organic electroluminescent device of the present invention, an electron injecting layer may be provided for the purpose of improving electron injecting property and improving device characteristics (for example, luminous efficiency, constant voltage driving, or high durability).

Preferred compounds for the electron injecting layer include fluorenone, anthraquinodimethane, diphenoquinone, thiopyrandioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane, anthrone and the like. Is mentioned. In addition, the above-mentioned metal complexes, alkali metal oxides, alkaline earth oxides, rare earth oxides, alkali metal halides, alkaline earth halides, rare earth halides, SiO ₂ , AlO, SiN, SiON, AlON, Various oxides such as GeO, LiO, LiON, TiO, TiON, TaO, TaON, TaN, and C, nitrides, and inorganic compounds such as oxynitrides can also be used.

  The triazine compound (1) of the present invention can be used together with the above-mentioned electron transporting material to form an organic layer by co-evaporation or lamination.

  Further, in the organic electroluminescent device of the present invention, the light-emitting material is not limited to the light-emitting layer alone, and may be contained alone in the hole transport layer adjacent to the light-emitting layer, or in the electron transport layer. Further, the luminous efficiency of the organic electroluminescent device can be increased.

  The substrate preferably used for the organic electroluminescent device of the present invention is not particularly limited in the type of glass, plastic, and the like, and is not particularly limited as long as it is transparent. Substrates preferably used for the organic electroluminescent device of the present invention include, for example, glass, quartz, and light-transmitting plastic films.

  Examples of the light-transmitting plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, and polycarbonate (PC). , Cellulose triacetate (TAC), cellulose acetate propionate (CAP) and the like.

  A preferred example for producing the organic electroluminescent device of the present invention will be described. As an example, a method for manufacturing an organic electroluminescent device including the above-described anode / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / cathode will be described.

  First, a thin film made of a desired electrode material, for example, an anode material, is formed on a suitable substrate by a method such as evaporation or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 10 to 200 nm. Make an anode. Next, a thin film composed of a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer / electron injection layer, which are element materials, is formed thereon.

  Note that a buffer layer (electrode interface layer) may be present between the anode and the light emitting layer or the hole injection layer, and between the cathode and the light emitting layer or the electron injection layer.

  Further, a layer having another function may be laminated in addition to the above-mentioned basic constituent layer, if necessary. For example, a functional layer such as a hole blocking layer or an electron blocking layer may be provided.

Next, the electrodes of the organic electroluminescent device of the present invention will be described. As the anode in the organic electroluminescent device, a metal, an alloy, an electrically conductive compound, or a mixture thereof having a large work function (4 eV or more) as an electrode material is preferably used. Specific examples of such an electrode material include metals such as Au, and conductive transparent materials such as CuI, indium-tin oxide (ITO), SnO ₂ , and ZnO.

  The above-mentioned anode may form a thin film of these electrode substances by a method such as evaporation or sputtering, and may form a pattern of a desired shape by a photolithography method, or may be patterned through a mask of a desired shape at the time of evaporation or sputtering. May be formed.

On the other hand, as the cathode, those using a metal having a small work function (4 eV or less) (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material are preferably used. Specific examples of such an electrode material 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 them, a mixture of an electron-injecting metal and a second metal, which is a metal having a large work function and a stable work function, such as a magnesium / silver mixture, magnesium, / Aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, lithium / aluminum mixture and the like are suitable. The cathode can be produced by forming a thin film from these electrode substances by a method such as vapor deposition or sputtering.

  As described above, a thin film made of a desired electrode material, for example, an anode material, is formed on a suitable substrate by a method such as evaporation or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 10 to 200 nm. After forming an anode, a layer thin film composed of a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer / electron injection layer is formed on the anode as described above, and then a cathode film is formed thereon. A cathode is provided by forming a thin film made of a substance so as to have a thickness of 1 μm or less, preferably 50 to 200 nm, for example, by a method such as vapor deposition or sputtering, and a desired organic electroluminescent device is obtained.

  The organic electroluminescent device of the present invention may be used as a kind of lamp such as an illumination or exposure light source, a projection device of a type for projecting an image, and a display of a type for directly recognizing a still image or a moving image. It may be used as a device (display). When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. In addition, a full-color display device can be manufactured by using two or more kinds of the organic electroluminescent elements of the present invention having different emission colors.

It is sectional drawing of the single-layer element produced in an Example.

1. 1. Glass substrate with ITO transparent electrode 2. hole injection layer 3. Hole transport layer Light emitting layer 5. Hole blocking layer 6. 6. electron transport layer 7. electron injection layer Cathode layer

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention should not be construed as being limited by these Examples.

¹ H-NMR measurement was performed using Gemini200 (manufactured by Varian).

The measurement of the glass transition temperature, the crystallization temperature, and the melting point was performed using a DSC device (manufactured by Hitachi High-Tech Science, DSC7020). Aluminum oxide (Al ₂ O ₃ ) was used as a reference in the DSC measurement, and measurement was performed with a measurement sample of 10 mg. As a pretreatment for the measurement, the sample was melted by increasing the temperature at a rate of 15 ° C./min from 30 ° C. to a temperature equal to or higher than the melting point, and then rapidly cooled with liquid nitrogen. Subsequently, the temperature of the pretreated sample was increased at a rate of 5 ° C./min from 30 ° C., and the glass transition temperature, the crystallization temperature, and the melting point were measured.

  The luminescence characteristics of the organic electroluminescent device were evaluated at room temperature by applying a direct current to the fabricated device and using a luminance meter of LUMINANCEMETER (BM-9) (manufactured by TOPCON).

  Synthesis Example-1

Under an argon atmosphere, 2,4-diphenyl-6- [3- (9-phenanthryl) -5- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) phenyl]- 1,3,5-triazine (9.00 g), 2- (4-pyridyl) -6- (trifluoromethanesulfonyloxy) naphthalene (6.77 g), palladium acetate (165 mg) and 2-dicyclohexylphosphino-2 ' , 4 ′, 6′-Triisopropylbiphenyl (700 mg) was suspended in THF (150 mL). A 2.0 M aqueous solution of potassium carbonate (23 mL) was added to the suspension, and the mixture was heated under reflux for 16 hours. After cooling, water and methanol were added to the reaction mixture, and the precipitated solid was collected by filtration. The obtained solid is purified by recrystallization (toluene) to obtain the desired 2,4-diphenyl-6- {3- (9-phenanthryl) -5- [6- (4-pyridyl) naphthalen-2-yl. ] Phenyl} -1,3,5-triazine (Compound A-1) was obtained (5.04 g, 49%).
¹ H NMR (CDCl ₃ ) δ 7.54-7.64 (m, 7H), 7.66-7.70 (m, 3H), 7.74 (dt, J = 1.4, 6.8 Hz, 2H). , 7.82 (dd, J = 1.8, 8.6 Hz, 1H), 7.92 (s, 1H), 7.99 (dd, J = 1.3, 7.8 Hz, 1H), 8. 04-8.07 (m, 2H), 8.10 (t, J = 7.4 Hz, 2H), 8.17 (t, J = 1.6 Hz, 1H), 8.20 (s, 1H), 8.32 (s, 1H), 8.73 (dd, J = 1.6, 4.5 Hz, 2H), 8.78-8.81 (m, 5H), 8.86 (d, J = 8) .1 Hz, 1H), 8.98 (t, J = 1.6 Hz, 1H), 9.24 (t, J = 1.6 Hz, 1H).
The glass transition temperature of the obtained compound A-1 was 146 ° C, the crystallization temperature was 215 ° C, and the melting point was 301 ° C.

Reference Example-1
2,4-diphenyl-6- [4,4 ″ -bis (2-pyridyl)-[1,1 ′: 3 ′, 1 which is a compound described in Example 6 of JP-A-2008-280330. ″] -Terphenyl-5′-yl] -1,3,5-triazine (ETL-1 described below) was synthesized, and its DSC measurement was performed. This compound had a glass transition temperature of 108 ° C, a crystallization temperature of 135 ° C, and a melting point of 282 ° C. In addition, this compound was synthesized by the method described in JP-A-2008-280330, and the DSC measurement was performed under the same conditions as in Synthesis Example-1 of the present application.

  From the above results, it was found that the compound of the present invention has a higher glass transition temperature and a higher crystallization temperature than conventionally known compounds. In particular, by having a high crystallization temperature, a high amorphous property can be expected at the time of forming a thin film, and a high driving stability and a high luminous efficiency can be expected when an organic electroluminescent device using the compound of the present invention is manufactured.

Element Example-1
As the substrate, a glass substrate with an ITO transparent electrode in which a 2 mm-width indium-tin oxide (ITO) film (film thickness 110 nm) was patterned in a stripe shape was used. After the substrate was washed with isopropyl alcohol, a surface treatment was performed by ozone ultraviolet ray cleaning. Vacuum deposition of each layer was performed on the washed substrate by a vacuum deposition method to produce an organic electroluminescent device having a light-emitting area of 4 mm ² as shown in a sectional view of FIG. Each organic material was formed by a resistance heating method.

First, the glass substrate was introduced into a vacuum evaporation tank, and the pressure was reduced to 1.0 × 10 ⁻⁴ Pa.

  Then, as an organic compound layer, a hole injection layer 2, a hole transport layer 3, a light emitting layer 4, a hole blocking layer 5, an electron transport layer 6, and an electron injection layer are formed on the glass substrate with an ITO transparent electrode shown in FIG. The layer 7 and the cathode layer 8 were formed by vacuum evaporation while being laminated in this order.

  As the hole injection layer 2, N- [1,1′-biphenyl] -4-yl-9,9-dimethyl-N- [4- (9-phenyl-9H-carbazol-3-yl) purified by sublimation is used. Phenyl] -9H-fluoren-2-amine and 1,2,3-tris [(cyano) (4-cyano-2,3,5,6-toterafluorophenyl) methylene] cyclopropane at 99: 1 (weight ratio) ) At a rate of 0.1 nm / sec.

  As the hole transport layer 3, N- [1,1′-biphenyl] -4-yl-9,9-dimethyl-N- [4- (9-phenyl-9H-carbazol-3-yl) purified by sublimation is used. [Phenyl] -9H-fluoren-2-amine was deposited at a rate of 0.2 nm / sec to a thickness of 85 nm.

  As the light emitting layer 4, 3- (10-phenyl-9-anthryl) -dibenzofuran and 2,7-bis [N, N-di- (4-tertbutylphenyl)] amino-bisbenzofurano-9,9 ′ -Spirofluorene was deposited at a ratio of 95: 5 (weight ratio) to a thickness of 20 nm (a deposition rate of 0.1 nm / sec).

  As the hole blocking layer 5, 2- [3 ′-(9,9-dimethyl-9H-fluoren-2-yl) [1,1′-biphenyl] -3-yl] -4,6-diphenyl-1 , 3,5-Triazine was deposited to a thickness of 6 nm at a rate of 0.05 nm / sec.

  As the electron transport layer 6, 2,4-diphenyl-6- {3- (9-phenanthryl) -5- [6- (4-pyridyl) naphthalen-2-yl synthesized in Synthesis Example 1 of the present invention. ] Phenyl} -1,3,5-triazine (A-1) and Liq were formed at a ratio of 50:50 (weight ratio) to a thickness of 25 nm (film formation rate: 0.1 nm / sec).

  As the electron injection layer 7, 8-hydroxyquinolinolate lithium (hereinafter, Liq) was formed to a thickness of 1 nm at a rate of 0.02 nm / sec.

  Finally, a metal mask was arranged so as to be perpendicular to the ITO stripe, and the cathode layer 8 was formed. The cathode layer 8 is formed of silver / magnesium (weight ratio 1/10) and silver in this order at 80 nm (film formation rate 0.5 nm / sec) and 20 nm (film formation rate 0.2 nm / sec), respectively. And a two-layer structure.

  Each film thickness was measured with a stylus-type film thickness meter (DEKTAK).

  Further, the device was sealed in a glove box under a nitrogen atmosphere having an oxygen and moisture concentration of 1 ppm or less. For sealing, a glass sealing cap and the above-mentioned film-forming substrate epoxy type ultraviolet curing resin (manufactured by Nagase ChemteX Corporation) were used.

Element Reference Example-1
In the device example 1, 2,4-diphenyl-6- {3- (9-phenanthryl) -5- [6- (4-pyridyl) naphthalen-2-yl] phenyl} -1 was added to the electron transport layer 6. , 3,5-triazine (A-1) and Liq in a ratio of 50:50 (weight ratio) to form a 25 nm film (film formation rate: 0.15 nm / sec), instead of the above compounds ETL-1 and Liq An organic electroluminescent device was prepared in the same manner as in Device Example 1, except that a film was formed at a ratio of 50:50 (weight ratio) of 25 nm (film formation rate: 0.15 nm / sec).

A direct current was applied to the produced organic electroluminescent device, and the light emission characteristics were evaluated using a luminance meter of LUMINANCE METER (BM-9) manufactured by TOPCON. As emission characteristics, a voltage (V) and a current efficiency (cd / A) when a current density of 10 mA / cm ² was passed were measured, and an element lifetime during continuous lighting was measured. Note that the element lifetime, after which the initial luminance and the luminance was measured decay time at the time of continuous lighting when driven at 1000 cd / m ^2, to measure the time required until the luminance (cd / m ²⁾ is reduced 3% In Example 1, the time required for the luminance (cd / m ² ) to decrease by 3% was expressed as a relative value with respect to 100. Table 1 shows the results.

  From Table 1, it was found that the organic electroluminescent device using the azine compound of the present invention was remarkably superior in driving voltage, luminous efficiency and device life as compared with Reference Example.

  The present invention provides a triazine compound having a novel structure that enables low-voltage operation, high efficiency, and long life of the device by using the compound as an electron transport layer of an organic electroluminescent device. An object of the present invention is to provide an organic electroluminescent device provided with a voltage.

Claims (6)

A triazine compound represented by the general formula (1).

(Wherein, Ar ¹ is each independently a phenyl group, a naphthyl group, or a biphenylyl group (these groups may be substituted with a fluorine atom, a methyl group, a phenyl group, a naphthyl group, or a pyridyl group) Ar ² represents a pyridyl group, a quinolyl group, an isoquinolyl group, a pyrazyl group, or a pyrimidyl group, and Ar ³ is a condensed tricyclic ring which may be substituted with a phenyl group or a pyridyl group. Represents a ring aromatic hydrocarbon group.) The triazine compound according to claim 1, wherein Ar ¹ is independently an unsubstituted phenyl group, an unsubstituted naphthyl group, or an unsubstituted biphenylyl group. ^{3. The method according} to claim 1, wherein Ar ³ is a phenanthryl group, an anthryl group, a pyrenyl group, a triphenylenyl group, or a fluoranthenyl group (these groups may be substituted with a phenyl group or a pyridyl group). Triazine compounds. The triazine compound according to any one of claims 1 to 3, wherein Ar ² is a pyridyl group.   An electron transporting material for an organic electroluminescent device, comprising the triazine compound according to claim 1.   An organic electroluminescent device comprising the triazine compound according to claim 1 as a constituent.

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