JP2018145152A - Triazine compound and organic electroluminescent element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron transport material which achieves a long life of an organic electroluminescent element utilizing thermally activated delayed fluorescence (TADF).SOLUTION: A triazine compound is represented by formula (1), and an organic electroluminescent element contains the compound as a constituent. (Aris a phenyl group substituted with a group selected from a phenyl group, a naphthyl group, and a phenanthryl group; Aris a phenyl group or a phenyl group substituted with a group selected from a phenyl group, a naphthyl group, and a phenanthryl group; and Aris a terphenylyl group.)SELECTED DRAWING: None

Description

  An organic electroluminescent element has a light emitting layer containing an organic or organometallic compound that emits fluorescence, phosphorescence, or the like, sandwiched between layers made of a charge transport material, and further has an anode and a cathode attached to the outside, and holes and electrons are attached to the light emitting layer. It is a light emitting element that utilizes the emission of light from excitons generated upon recombination by injecting. In recent years, organic electroluminescent elements obtained by forming these light emitting layers and charge transporting layers by vapor deposition have been used and put into practical use in mobile phones, smartphones, thin televisions and the like. 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 blocking layer, a light emitting layer and a hole blocking layer, and the electron transport layer is divided into an electron transport layer and an electron injection layer. May be configured.

  In recent years, an example in which a triazine derivative (see, for example, Non-Patent Document 1) is used for an electron transport layer or the like in an organic electroluminescent element utilizing thermally activated delayed fluorescence (hereinafter also referred to as “TADF”) has been reported. It cannot be said that the life characteristics are sufficient, and improvement of the characteristics of the material is demanded.

Scientific Report, Vol. 3, 2127-2132, 2013

  The subject of this invention is providing the electron transport material which implement | achieves lifetime improvement in the organic electroluminescent element using TADF.

  As a result of intensive studies to solve the above problems, the present inventors have found that the triazine compound described in the present invention represented by the following general formula (1) is useful as an electron transport material, and uses an organic electric field utilizing TADF. It has been found that the lifetime characteristics of the device can be improved by using it in a light emitting device, and the present invention has been completed.

That is, the present invention
[1]
General formula (1)

(In the formula, Ar ¹ represents a phenyl group substituted with a group selected from the group consisting of a phenyl group, a naphthyl group, and a phenanthryl group. Ar ² represents a phenyl group, or a phenyl group, a naphthyl group, and a phenanthryl group. Represents a phenyl group substituted with a group selected from the group consisting of: Ar ³ represents a terphenylyl group.
A triazine compound represented by:
[2]
The triazine compound according to [1], wherein Ar ¹ is a biphenylyl group, a naphthylphenyl group, or a phenanthrylphenyl group;
[3]
The triazine compound according to [1] or [2], wherein Ar ¹ is a 4-biphenylyl group;
[4]
The triazine compound according to claim 1, wherein Ar ² is a phenyl group;
[5]
The triazine compound according to [1], wherein Ar ³ is a 1,1 ′: 3 ′, 1 ″ -terphenyl-5′-yl group;
[6]
An organic electroluminescent device comprising the triazine compound according to [1];
[7]
A thermally delayed fluorescent organic electroluminescent device comprising the triazine compound according to [1];
[8]
The organic electroluminescent device according to [6] or [7], wherein a triazine compound is used as an electron transporting material.

  The present invention is described in detail below.

The definitions of Ar ¹ , Ar ² and Ar ³ in the triazine compound of the present invention will be described.

Ar ¹ represents a phenyl group substituted with a group selected from the group consisting of a phenyl group, a naphthyl group, and a phenanthryl group. The Ar ¹ is preferably a biphenylyl group, a naphthylphenyl group, or a phenanthrylphenyl group, and more preferably a 4-biphenylyl group, from the viewpoint of good performance as an organic EL material.

The phenyl group substituted with a group selected from the group consisting of a phenyl group, a naphthyl group, and a phenanthryl group represented by Ar ¹ is not particularly limited, and examples thereof include a biphenylyl group (2-biphenylyl group, 3 -Biphenylyl group, 4-biphenylyl group), 2- (1-naphthyl) phenyl group, 3- (1-naphthyl) phenyl group, 4- (1-naphthyl) phenyl group, 2- (2-naphthyl) phenyl group, 3- (2-naphthyl) phenyl group, 4- (2-naphthyl) phenyl group, 2- (1-phenanthryl) phenyl group, 3- (1-phenanthryl) phenyl group, 4- (1-phenanthryl) phenyl group, 2- (2-phenanthryl) phenyl group, 3- (2-phenanthryl) phenyl group, 4- (2-phenanthryl) phenyl group, 2- (3-phena Enthryl) phenyl group, 3- (3-phenanthryl) phenyl group, 4- (3-phenanthryl) phenyl group, 2- (4-phenanthryl) phenyl group, 3- (4-phenanthryl) phenyl group, 4- (4- Examples thereof include a phenanthryl) phenyl group, a 2- (5-phenanthryl) phenyl group, a 3- (5-phenanthryl) phenyl group, and a 4- (5-phenanthryl) phenyl group.

Ar ² represents a phenyl group or a phenyl group substituted with a group selected from the group consisting of a phenyl group, a naphthyl group, and a phenanthryl group.

The phenyl group substituted with a group selected from the group consisting of a phenyl group, a naphthyl group, and a phenanthryl group represented by Ar ² is not particularly limited, but includes the same groups as those exemplified for Ar ^1. It can be illustrated. As the Ar ² , a phenyl group is preferable in terms of good performance as an organic EL material.

The terphenylyl group represented by Ar ³ is not particularly limited. For example, 1,1 ′: 4 ′, 1 ″ -terphenyl-2′-yl group, 1,1 ′: 3 ′, 1 “-Terphenyl-2′-yl group, 1,1 ′: 3 ′, 1” -terphenyl-4′-yl group, 1,1 ′: 3 ′, 1 ”-terphenyl-5′-yl group 1,1 ′: 2 ′, 1 ″ -terphenyl-3′-yl group, or 1,1 ′: 2 ′, 1 ″ -terphenyl-4′-yl group, Of these, a 1,1 ′: 3 ′, 1 ″ -terphenyl-5′-yl group is preferable in terms of good performance as an organic EL material.

  Specific examples of the triazine compound (1) of the present invention include the structures shown in the following 1-1 to 1-24, but the present invention is not limited thereto.

  Among the compounds represented by 1-1 to 1-24, the compound represented by 1-1 is preferable as the triazine compound (1) of the present invention.

  Next, the manufacturing method of the triazine compound of this invention is demonstrated.

  The method for producing the triazine compound of the present invention is shown in the following step 1. That is, a compound represented by the general formula (2) (hereinafter also referred to as “compound (2)”) and a boron compound represented by the general formula (3) (hereinafter also referred to as “boron compound (3)”). By reacting, the triazine compound represented by the general formula (1) can be produced.

(In the formula, Ar ¹ , Ar ² and Ar ³ represent the same meaning as described above. X ¹ represents a halogen atom. R ¹ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group. represents, B (oR ¹⁾ two R ¹ ₂ may be the same or different. Furthermore, two of R ¹ can also form a ring containing an oxygen atom and a boron atom together.)
B (OR ¹ ) ₂ in the boron compound (3) is not particularly limited. For example, B (OH) ₂ , B (OMe) ₂ , B (O ⁱ Pr) ₂ , B (OBu) ₂ Or B (OPh) ₂ or the like. In addition, as an example of B (OR ¹ ) ₂ in the case where two R ¹ are combined to form a ring containing an oxygen atom and a boron atom, there is no particular limitation, but from the following (I) The group represented by (VI) can be exemplified, and the group represented by (II) is preferred in terms of good yield.

  Step 1 is a step of reacting the boron compound (3) and the compound (2) in the presence of a palladium catalyst and a base to produce the triazine compound (1) of the present invention, and is a reaction of a general Suzuki-Miyaura reaction. By applying the conditions, the triazine compound (1) of the present invention can be obtained in good yield.

  The boron compound (3) used in Step 1 can be produced by a general-purpose method well known to those skilled in the art, or a commercially available product may be used. Although there is no restriction | limiting in particular in the molar equivalent of the boron compound (3) to be used, It is preferable to use 0.5-3.0 molar equivalent with respect to a compound (2) at the point with a sufficient reaction yield.

  Although it does not specifically limit as a palladium catalyst used for the process 1, Specifically, salts, such as palladium chloride, palladium acetate, trifluoroacetate palladium, palladium nitrate, can be illustrated. Further, complex compounds such as π-allyl palladium chloride dimer, palladium acetylacetonate, tris (dibenzylideneacetone) dipalladium, dichlorobis (triphenylphosphine) palladium, tetrakis (triphenylphosphine) palladium, dichloro (1,1 Tertiary phosphines such as' -bis (diphenylphosphino) ferrocene) palladium, bis (tri-tert-butylphosphine) palladium, bis (tricyclohexylphosphine) palladium, bis (tricyclohexylphosphine) palladium chloride and the like as ligands Examples thereof include palladium complexes having a tertiary phosphine added to a palladium salt or complex compound, and can also be prepared in a reaction system. The tertiary phosphine that can be used in this case is not particularly limited. For example, triphenylphosphine, trimethylphosphine, tributylphosphine, tri (tert-butyl) phosphine, tricyclohexylphosphine, tert-butyldiphenyl. Phosphine, 9,9-dimethyl-4,5-bis (diphenylphosphino) xanthene, 2- (diphenylphosphino) -2 ′-(N, N-dimethylamino) biphenyl, 2- (di-tert-butylphosphine) Fino) biphenyl, 2- (dicyclohexylphosphino) biphenyl, bis (diphenylphosphino) methane, 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, 1,4-bis (Diphenylphosphino) butane, 1 1′-bis (diphenylphosphino) ferrocene, tri (2-furyl) phosphine, tri (o-tolyl) phosphine, tris (2,5-xylyl) phosphine, (±) -2,2′-bis (diphenylphosphine) Phino) -1,1′-binaphthyl, 2-dicyclohexylphosphino-2 ′, 4 ′, 6′-triisopropylbiphenyl and the like can be exemplified.

  Among them, a palladium complex having tertiary phosphine as a ligand is preferable in terms of a good yield, and a palladium complex having 2-dicyclohexylphosphino-2 ′, 4 ′, 6′-triisopropylbiphenyl as a ligand. Is more preferable. The molar ratio of the tertiary phosphine to the palladium salt or complex compound is preferably in the range of 1:10 to 10: 1, and more preferably in the range of 1: 2 to 3: 1 in terms of good yield. preferable. Although there is no restriction | limiting in the quantity of the palladium catalyst used at the process 1, The molar equivalent of a palladium catalyst exists in the range of 0.005-0.5 molar equivalent with respect to a compound (2) by the point with a sufficient yield. preferable.

  Although it does not specifically limit as a base used for the process 1, For example, metal hydroxide salts, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, etc. Metal carbonates, metal acetates such as potassium acetate and sodium acetate, metal phosphates such as potassium phosphate and sodium phosphate, metal fluoride salts such as sodium fluoride, potassium fluoride and cesium fluoride, sodium methoxide And metal alkoxides such as potassium methoxide, sodium ethoxide, potassium isopropyl oxide and potassium tert-butoxide. Of these, metal carbonates and metal phosphates are preferable, and potassium carbonate is more preferable in that the reaction yield is good. The amount of the base used is not particularly limited, but the molar ratio of the base and the boron compound (3) is preferably in the range of 1: 2 to 10: 1 in view of good reaction yield. More preferably, it is in the range of ˜4: 1.

  Step 1 can be carried out in a solvent. Although it does not specifically limit as a solvent which can be used at the process 1, For example, water, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether (CPME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,4- Ethers such as dioxane, dimethoxyethane, aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, tetralin, carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-fluoroethylene carbonate, Esters such as ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, γ-lactone, dimethyl sulfoxide (DMF), dimethylacetamide DMAc), amides such as N-methylpyrrolidone (NMP), ureas such as N, N, N ′, N′-tetramethylurea (TMU), N, N′-dimethylpropyleneurea (DMPU), or dimethyl sulfoxide (DMSO) ), Methanol, ethanol, 2-propanol, butanol, octanol, benzyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, alcohols such as 2,2,2-trifluoroethanol, and the like. May be mixed at an arbitrary ratio. There is no restriction | limiting in particular in the usage-amount of a solvent. Of these, water, ether, amide, alcohol, and a mixed solvent thereof are preferable from the viewpoint of good reaction yield, and a mixed solvent of dioxane and water is more preferable.

  Step 1 is not particularly limited, but is preferably performed at a temperature appropriately selected from 0 ° C. to 200 ° C., and at a temperature appropriately selected from 100 ° C. to 160 ° C. in terms of good reaction yield. It is preferable to carry out.

  The triazine compound (1) of the present invention can be obtained by performing a normal treatment after the completion of the step 1. If necessary, it may be purified by recrystallization, column chromatography, sublimation or preparative HPLC.

  The present invention is an organic electroluminescence device containing a triazine compound represented by the general formula (1), and preferably a thermal delayed fluorescence organic electroluminescence device containing a triazine compound represented by the general formula (1). The triazine compound is preferably used for an electron transport layer, an electron injection layer, or a light emitting layer.

  The triazine compound represented by the general formula (1) can be preferably used as an electron transporting material (electron transporting material, electron injecting material, etc.) of the organic electroluminescence device. At this time, for the anode, the hole injection layer, the hole transport layer, the electron blocking layer, the light emitting layer, the light emitting layer dopant, the light emitting layer host, the cathode, and the like used in combination, generally known materials are selected by those skilled in the art. Can be used.

  About the structure of the said organic electroluminescent element, what is necessary is just a conventionally well-known thing, and it does not specifically limit.

Although there is no limitation in particular in the manufacturing method of the thin film for organic electroluminescent elements containing the triazine compound (1) of this invention, The film-forming by a vacuum evaporation method can be mentioned as a preferable example. Film formation by the vacuum evaporation method can be performed by using a general-purpose vacuum evaporation apparatus. The vacuum degree of the vacuum chamber when forming a film by the vacuum evaporation method is such that the production tact time for producing the organic electroluminescent element is short and the production cost is superior, so that commonly used diffusion pumps, turbo molecular pumps, cryogenic pumps are used. It is preferably about 1 × 10 ⁻² to 1 × 10 ⁻⁶ Pa that can be reached by a pump or the like, and the deposition rate is preferably 0.005 to 10 nm / second, although it depends on the thickness of the film to be formed. Moreover, the thin film for organic electroluminescent elements which consists of the triazine compound (1) of this invention can also be manufactured by the solution coating method. For example, the triazine compound (1) of the present invention is dissolved in an organic solvent such as chloroform, dichloromethane, 1,2-dichloroethane, chlorobenzene, toluene, ethyl acetate or tetrahydrofuran, and a spin coating method or ink jet method using a general-purpose apparatus. Film formation by a casting method or a dip method is also possible.

  The triazine compound represented by the general formula (1) of the present invention has high solubility in chloroform, dichloromethane, 1,2-dichloroethane, chlorobenzene, toluene, ethyl acetate, tetrahydrofuran, etc. It is also possible to form a film by the GOT method, the ink jet method, the cast method, the dip method or the like.

  A typical structure of the organic electroluminescence device that can obtain the effects of the present invention includes a substrate, an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode.

  The anode and cathode of the organic electroluminescent element are connected to a power source through an electrical conductor. The organic electroluminescent device operates by applying a potential between the anode and the cathode. Holes are injected into the organic electroluminescent device from the anode, and electrons are injected into the organic electroluminescent device at the cathode.

  The organic electroluminescent device is typically placed on a substrate, and the anode or cathode can be in contact with the substrate. The electrode in contact with the substrate is called the lower electrode for convenience. Generally, the lower electrode is an anode, but the organic electroluminescence device of the present invention is not limited to such a form.

  The substrate may be light transmissive or opaque, depending on the intended emission direction. The light transmission characteristics can be confirmed by electroluminescence emission through the substrate. Generally, transparent glass or plastic is used as the substrate. The substrate may be a composite structure including multiple material layers.

  When the electroluminescent emission is confirmed through the anode, the anode is formed by passing or substantially passing through the emission.

  Common transparent anode (anode) materials used in the present invention include indium-tin oxide (ITO), indium-zinc oxide (IZO), or tin oxide. Further, other metal oxides such as aluminum or indium-doped tin oxide, magnesium-indium oxide, or nickel-tungsten oxide are also preferably used. In addition to these oxides, metal nitrides such as gallium nitride, metal selenides such as zinc selenide, or metal sulfides such as zinc sulfide can be used as the anode. The anode can be modified with plasma deposited fluorocarbon.

  If electroluminescence emission is confirmed only through the cathode, the transmission properties of the anode are not critical and any conductive material that is transparent, opaque or reflective can be used. Examples of conductors for this application include gold, iridium, molybdenum, palladium, platinum and the like.

  The hole injection layer can be provided between the anode and the hole transport layer. The material of the hole injection layer is useful for improving the film formation characteristics of an organic material layer such as a hole transport layer and a hole injection layer, and facilitating injection of holes into the hole transport layer. Examples of materials suitable for use in the hole injection layer include porphyrin compounds, plasma deposited fluorocarbon polymers, and amines having aromatic rings such as biphenyl groups, carbazole groups, such as m-MTDATA (4,4 ' , 4 ″ -tris [(3-methylphenyl) phenylamino] triphenylamine), 2T-NATA (4,4 ′, 4 ″ -tris [(N-naphthalen-2-yl) -N-phenylamino ] Triphenylamine), triphenylamine, tolylamine, tolyldiphenylamine, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine, N, N, N′N′-tetrakis (4-methylphenyl) -1,1′-biphenyl-4,4′-diamine, MeO-TPD N, N, N′N′-tetrakis (4-methoxyphenyl) -1,1′-biphenyl-4,4′-diamine), N, N′-diphenyl-N, N′-dinaphthyl-1,1 ′ -Biphenyl-4,4'-diamine, N, N'-bis (methylphenyl) -N, N'-bis (4-normalbutylphenyl) phenanthrene-9,10-diamine, N, N'-diphenyl-N , N′-bis (9-phenylcarbazol-3-yl) -1,1′-biphenyl-4,4′-diamine and the like.

  The hole transport layer of the organic electroluminescence device preferably contains one or more hole transport compounds (hole transport materials) such as aromatic tertiary amines. Aromatic tertiary amines are compounds that contain one or more trivalent nitrogen atoms that are bonded only to carbon atoms, and one or more of these carbon atoms have an aromatic ring. Forming. Specifically, the aromatic tertiary amine can be an arylamine, such as a monoarylamine, diarylamine, triarylamine, or a polymeric arylamine.

  An aromatic tertiary amine having one or more amino groups can be used as the hole transport material. Furthermore, a polymeric hole transport material can be used. For example, poly (N-vinylcarbazole) (PVK), polythiophene, polypyrrole, polyaniline and the like can be used.

  Specifically, NPD (N, N′-bis (naphthalen-1-yl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine), α-NPD (N, N '-Di (1-naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine), TPBi (1,3,5-tris (1-phenyl-1H-benzimidazole) 2-yl) benzene), TPD (N, N′-bis (3-methylphenyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine) and the like.

  Dipyrazino [2,3-f: 2 ′, 3′-h] quinoxaline-2,3,6,7,10,11-hexacarbonitrile as a charge generation layer between the hole injection layer and the hole transport layer (HAT-CN), 7,7 ', 8,8'-tetracyanoquinodimethane (TCNQ), 2,3,5,6-tetrafluoro-7,7', 8,8'-tetracyanoquinodi A layer containing methane (F4-TCNQ) or the like may be provided, and the hole transport layer may be doped with these compounds.

  The light emitting layer of the organic electroluminescent element contains a phosphorescent material or a fluorescent material, and in this case, light emission occurs as a result of recombination of electron-hole pairs in this region. The light-emitting layer may be formed from a single material that includes both small molecules and polymers, but more commonly is formed from a host material doped with a guest compound, where light emission is primarily from a dopant, Any color can be emitted.

  As the host material of the light emitting layer, the triazine compound (1) of the present invention can be used. Examples of other materials include a biphenyl group, a fluorenyl group, a triphenylsilyl group, a carbazole group, a pyrenyl group, or an anthranyl group. These materials can be used alone or in admixture with the triazine compound (1) of the present invention.

  Specifically, DPVBi (4,4′-bis (2,2-diphenylvinyl) -1,1′-biphenyl), BCzVBi (4,4′-bis (9-ethyl-3-carbazovinylene) 1,1 '-Biphenyl), TBADN (2-tert-butyl-9,10-di (2-naphthyl) anthracene), ADN (9,10-di (2-naphthyl) anthracene), CBP (4,4'-bis ( Carbazol-9-yl) biphenyl), CDBP (4,4′-bis (carbazol-9-yl) -2,2′-dimethylbiphenyl), 9,10-bis (biphenyl) anthracene and the like. In addition, a compound that expresses thermally activated delayed fluorescence (TADF) can also be used.

  The host material in the light emitting layer may be an electron transport material as defined below, a hole transport material as defined above, another material that supports hole-electron recombination, or a combination of these materials.

  Examples of fluorescent dopants include pyrene, anthracene, tetracene, xanthene, perylene, rubrene, coumarin, rhodamine and quinacridone, dicyanomethylenepyran compounds, thiopyran compounds, polymethine compounds, pyrylium or thiapyrylium compounds, fluorene derivatives, perifanthene derivatives, indeno A perylene derivative, a bis (azinyl) amine boron compound, a bis (azinyl) methane compound, a carbostyryl compound, a compound that expresses thermally activated delayed fluorescence (TADF), or the like can be given.

  Examples of useful phosphorescent dopants include organometallic complexes of transition metals such as iridium, platinum, palladium, osmium.

Examples of dopants include Alq ₃ (tris (8-hydroxyquinoline) aluminum)), DPAVBi (4,4′-bis [4- (di-p-tolylamino) styryl] biphenyl), perylene, Ir (PPy) ₃ ( Examples include tris (2-phenylpyridine) iridium (III), FlrPic (bis (3,5-difluoro-2- (2-pyridyl) phenyl- (2-carboxypyridyl) iridium), and the like.

  The triazine compound represented by the general formula (1) of the present invention can be used as the thin film forming material used for forming the electron transport layer of the organic electroluminescence device of the present invention. The electron transport layer may contain other generally known electron transport materials. Examples of other electron transporting materials include alkali metal complexes, alkaline earth metal complexes, and earth metal complexes.

  Desirable alkali metal complexes, alkaline earth metal complexes, or earth metal complexes include, for example, 8-hydroxyquinolinate lithium (Liq), bis (8-hydroxyquinolinato) zinc, 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-quinolinato) (O-cresolate) gallium, bis (2-methyl-8-quino) Inert) -1-naphthoquinone Trad aluminum, bis (2-methyl-8-quinolinato) -2-naphthoquinone Trad gallium, and the like.

  A hole blocking layer may be provided between the light emitting layer and the electron transport layer for the purpose of improving carrier balance. As the hole blocking layer, the triazine compound (1) of the present invention can be used. Other materials include BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), Bphen (4,7-diphenyl-1,10-phenanthroline), BAlq (bis (2-methyl- 8-quinolinolato) -4- (phenylphenolato) aluminum), bis (10-hydroxybenzo [h] quinolinato) beryllium) and the like.

  In the organic electroluminescent device of the present invention, an electron injection layer may be provided for the purpose of improving electron injection properties and improving device characteristics (for example, light emission efficiency, low voltage driving, or high durability).

Preferred compounds for the electron injection layer include the triazine compound (1) of the present invention, fluorenone, anthraquinodimethane, diphenoquinone, thiopyrandioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, fluorene. Examples include olenylidene methane, anthraquinodimethane, and anthrone. In addition, the metal complexes, alkali metal oxides, alkaline earth oxides, rare earth oxides, alkali metal halides, alkaline earth halides, rare earth halides, SiO _x , AlO _x , SiN _x , SiON, _{AlON, GeO X, LiO X,} LiON, TiO X, TiON, TaO X, TaON, TaN X, various oxides of C, etc. nitrides, and inorganic compounds such as oxynitride _(X is an integer) Can also be used.

If light emission is seen only through the anode, the cathode used in the present invention can be formed from almost any conductive material. Desirable cathode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, indium , Lithium / aluminum mixtures, rare earth metals and the like.

It is a cross-sectional schematic diagram of the organic electroluminescent element produced in Evaluation Example-1.

51. 52. Glass substrate with ITO transparent electrode Hole injection layer 53. First hole transport layer 54. Second hole transport layer 55. Electron blocking layer 56. Light emitting layer 57. First electron transport layer 58. Second electron transport layer 59. Cathode layer

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is limited to these and is not interpreted.

The following analysis method was used for identification of the azine compound and the boron compound obtained by the production method of the present invention. ^For measurement of ¹ H-NMR, Bruker ASCEND 400 (400 MHz) was used. ¹ H-NMR was measured using deuterated chloroform (CDCl ₃ ) as a measurement solvent and tetramethylsilane (TMS) as an internal standard substance. In addition, commercially available reagents were used.
Example-1

2- (4-Biphenylyl) -4- (5-chlorobiphenyl-3-yl) -6-phenyl-1,3,5-triazine (1.98 g) and 5′-m-terphenylboron under an argon stream The acid (3.29 g) was suspended in dioxane (60 mL). To this suspension was added a solution of palladium acetate (90 mg) and 2-dicyclohexylphosphino-2 ′, 4 ′, 6′-triisopropylbiphenyl (340 mg) in dioxane (20 mL), and a 2.0 M aqueous potassium carbonate solution (8. 0 mL) was added and stirred at 110 ° C. for 24 hours. After allowing to cool, the solvent was distilled off, methanol was added to the residue, the solid was collected by filtration, and washed with methanol, water, and hexane. The obtained solid was purified by column chromatography (developing solvent: chloroform) and then recrystallized (toluene) to give 2- (4-biphenylyl) -4-phenyl-6- (5 "-phenyl-1,1 ' : 3 ′, 1 ″: 3 ″, 1 ′ ″-quarterphenyl-5′-yl) -1,3,5-triazine (compound 1-1) was obtained as a white solid (yield 2.27 g, yield). 82%).
¹ H-NMR (CDCl ₃ ) δ (ppm): 7.41-7.61 (m, 15H), 7.72 (d, J = 7.5 Hz, 2H), 7.78 (d, J = 7 .5Hz, 4H), 7.83 (dd, J = 7.5, 6.0Hz, 4H), 7.90 (s, 1H), 7.97 (s, 2H), 8.13 (s, 1H) ), 8.83 (d, J = 6.3 Hz, 2H), 8.88 (d, J = 8.4 Hz, 2H), 9.05 (dd, J = 2.0, 1.9 Hz, 2H) .
The structural formulas and abbreviations of the compounds used for the production and performance evaluation of organic electroluminescent devices comprising the triazine compound of the present invention as structural components are shown below.

Example-2
As the substrate, a glass substrate with an ITO transparent electrode in which an indium-tin oxide (ITO) film having a width of 2 mm was patterned in a stripe shape was used. The substrate was cleaned with isopropyl alcohol and then surface-treated by oxygen plasma cleaning. Each layer was vacuum-deposited on the cleaned substrate by a vacuum deposition method, and an organic electroluminescence device having a light emission area of 4 mm ² as shown in FIG.

First, the said glass substrate was introduce | transduced in the vacuum evaporation tank and it pressure-reduced to 1.0 * 10 <^-4> Pa. Thereafter, a hole injection layer 52, a first hole transport layer 53, a second hole transport layer 54, an electron blocking layer 55, a light emitting layer are formed as an organic compound layer on the glass substrate with an ITO transparent electrode shown by 51 in FIG. 56, the first electron transport layer 57, and the second electron transport layer 58 were sequentially formed, and then the cathode layer 59 was formed.

  In addition, all the materials which comprise each layer of an organic electroluminescent element were vacuum-deposited by the resistance heating system.

  As the hole injection layer 52, HIL-1 was vacuum-deposited with a film thickness of 0.15 nm / second and a film thickness of 60 nm.

  As the first hole transport layer 53, HAT-CN was vacuum-deposited with a film thickness of 10 nm at a film formation rate of 0.025 nm / second.

  As the second hole transport layer 54, HTL-2 was vacuum-deposited at a film thickness of 0.15 nm / second to a film thickness of 10 nm.

  As the electron blocking layer 55, mCBP was vacuum-deposited with a film thickness of 0.15 nm / second and a film thickness of 5 nm.

  As the light-emitting layer 56, mCBP and 4Cz-IPN, which is a known TADF light-emitting material, have a film thickness of 30 nm at a film formation rate of 0.18 nm / second (mCBP / 4Cz-IPN = 85.0 / 15.0 (weight ratio). ) Co-evaporation).

  As the first electron transport layer 57, the compound 1-1 synthesized in Example-1 of the present invention was vacuum-deposited with a film thickness of 10 nm at a film formation rate of 0.15 nm / second.

  As the second electron transporting layer 58, ETL-2 and Liq were vacuum-deposited at a film formation rate of 0.15 nm / second with a film thickness of 40 nm (co-evaporation of ETL-2 / Liq = 50/50 (weight ratio)). .

  Finally, a metal mask was disposed so as to be orthogonal to the ITO stripe, and a cathode layer 59 was formed. For the cathode layer 59, magnesium / silver (weight ratio 80/20) and silver were vacuum-deposited in this order at a film thickness of 80 nm and 20 nm at a film formation rate of 0.5 nm / second and 0.2 nm / second, respectively. A two-layer structure was adopted.

  Each film thickness was measured with a stylus type film thickness meter (DEKTAK, manufactured by Veeco). Furthermore, this element was sealed in a nitrogen atmosphere glove box having an oxygen and moisture concentration of 1 ppm or less. For the sealing, a glass sealing cap and the above-described film-forming substrate epoxy type ultraviolet curable resin (manufactured by Nagase ChemteX Corporation) were used.

Comparative Example-1
In the first electron transport layer 57 of Example-2, an organic electroluminescent element was prepared in the same manner as in Example-2 except that ETL-1 which is a known electron transport material was used instead of the compound 1-1. Produced.

Comparative Example-2
In the second electron transport layer 58 of Comparative Example-1, an organic electroluminescent element was produced in the same manner as in Example-2 except that ETL-1 which is a known electron transport material was used instead of ETL-2. did.

A direct current was applied to the organic electroluminescent elements prepared in Example-2 and Comparative Examples-1 and 2, and the light emission characteristics were evaluated using a luminance meter of a LUMINANCE METER (BM-9) manufactured by TOPCON. As the lifetime characteristic (h), the luminance decay time during continuous lighting when a current density of 10 mA / cm ² is passed is measured, and the time when the luminance (cd / m ² ) is reduced by 15% is the element lifetime (h ). In addition, about the element lifetime of each evaluation example, the element lifetime (h) in the comparative example-1 was set to 100, and was shown by the relative value.

  Compared to Comparative Examples 1 and 2, it was found that the organic electroluminescent device using the triazine compound of the present invention was greatly superior in lifetime characteristics.

  The organic electroluminescent element using the triazine compound of the present invention can be driven for a long time compared with the organic electroluminescent element using the existing material. Further, the triazine compound of the present invention can be applied to a light emitting host layer, an electron transport layer, and the like in addition to the hole blocking layer of this example. Furthermore, it can be applied not only to an element using a TADF light emitting material but also to various organic electroluminescent elements using a fluorescent light emitting material or a phosphorescent light emitting material. Further, the triazine compound of the present invention has high solubility, and it is possible to produce an element using not only a vacuum deposition method but also a coating method. Furthermore, it is useful not only for applications such as flat panel displays but also for illumination applications that require low power consumption.

Claims (8)

General formula (1)

(In the formula, Ar ¹ represents a phenyl group substituted with a group selected from the group consisting of a phenyl group, a naphthyl group, and a phenanthryl group. Ar ² represents a phenyl group, or a phenyl group, a naphthyl group, and a phenanthryl group. Represents a phenyl group substituted with a group selected from the group consisting of: Ar ³ represents a terphenylyl group.
A triazine compound represented by: The triazine compound according to claim 1, wherein Ar ¹ is a biphenylyl group, a naphthylphenyl group, or a phenanthrylphenyl group. The triazine compound according to claim 1 or 2, wherein Ar ¹ is a 4-biphenylyl group. The triazine compound according to claim 1, wherein Ar ² is a phenyl group. The triazine compound according to claim 1, wherein Ar ³ is a 1,1 ′: 3 ′, 1 ″ -terphenyl-5′-yl group.   An organic electroluminescent device comprising the triazine compound according to claim 1.   A thermally delayed fluorescent organic electroluminescence device comprising the triazine compound according to claim 1.   The organic electroluminescent element according to claim 6 or 7, wherein a triazine compound is used as an electron transporting material.

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