JP5168787B2 - Light emitting device material and light emitting device - Google Patents

Description

  The present invention relates to a pyrene compound useful as a fluorescent dye or a charge transport material, and a light emitting device using the same, and includes a display device, a flat panel display, a backlight, illumination, an interior, a sign, a signboard, an electrophotographic machine, and an optical signal The present invention relates to a light-emitting element that can be used in fields such as a generator.

  In recent years, research on organic thin-film light-emitting devices that emit light when electrons injected from a cathode and holes injected from an anode are recombined in an organic light-emitting body sandwiched between both electrodes has been actively conducted. This light-emitting element is characterized by thin light emission with high luminance under a low driving voltage and multicolor light emission by selecting a light-emitting material.

This study was conducted by Eastman Kodak's C.I. W. Since Tang et al. Have shown that organic thin-film light-emitting elements emit light with high brightness, many research institutions have studied. The representative structure of the organic thin film light emitting device presented by the Kodak research group is a hole transporting diamine compound on an ITO glass substrate, tris (8-quinolinolato) aluminum (III) as a light emitting layer, and a cathode. Mg: Ag (alloy) was sequentially provided, and green light emission of 1000 cd / m ² was possible with a driving voltage of about 10 V (see Non-Patent Document 1).

  In addition, organic thin-film light-emitting elements can be obtained in various emission colors by using various fluorescent materials for the light-emitting layer, and therefore, researches for practical application to displays and the like are actively conducted. Among the three primary color luminescent materials, research on the green luminescent material is the most advanced, and at present, intensive research is being conducted to improve the characteristics of the red and blue luminescent materials.

One of the biggest problems in organic thin-film light emitting devices is the durability of the devices. In particular, with respect to blue, there are few blue light emitting materials that provide an element with excellent durability and high reliability. For example, although the technique (refer patent documents 1-8) using the pyrene compound substituted by the aryl group for a blue light emitting element is disclosed, all were inadequate.
JP 2001-118682 A (Claim 1) JP 2002-63988 A (Claim 1) JP 2002-324678 A (Claim 3) Japanese Patent Laying-Open No. 2004-75567 (Claims 3 and 4) JP 2004-83481 A (Claims 3 and 4) JP 2004-83483 A (Claims 2 and 4) JP 2004-204238 A (Claim 5) Japanese Patent Laying-Open No. 2005-206551 (Claim 1) Applied Physics Letters (USA) 1987, 51, 12, 913-915

  Accordingly, an object of the present invention is to provide a light emitting element material and a light emitting element that can solve the problems of the prior art and enable a light emitting element having high luminous efficiency and excellent durability.

  The present invention is a light emitting device material containing a pyrene compound represented by the general formula (1).

(R ^{1 to} R ⁹ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, alkoxy group, aryl ether group, aryl group, heteroaryl group, naphthyl group, phenanthryl group, anthracenyl group, pyrenyl group , Benzofuranyl group, dibenzofuranyl group, benzothiophenyl group, dibenzothiophenyl group, indolyl group, carbazolyl group , Ar ¹ is selected from among aryl group, naphthyl group, phenanthryl group, anthracenyl group, pyrenyl group When Ar ¹ is an aryl group, at least one of R ⁴ and R ⁶ is an aryl group, heteroaryl group, naphthyl group, phenanthryl group, anthracenyl group, pyrenyl group , benzofuranyl group, dibenzofuranyl group, benzo Thiophenyl group, dibenzothiophene Group, an indolyl group, .Ar ¹ is naphthyl group selected from carbazolyl group, phenanthryl group, anthracenyl group, when the pyrenyl ^group, at least one of R ¹ to R 9, Ar ¹ is, t- butyl group , A group selected from a dibenzofuranyl group and a carbazolyl group.)
Further, the present invention is a light-emitting element that has at least a light-emitting layer between an anode and a cathode and emits light by electric energy, and the light-emitting element contains a light-emitting element material represented by the general formula (1). A light-emitting element is characterized.

  INDUSTRIAL APPLICABILITY The present invention can provide a light emitting element material having high light emission performance that can be used for a light emitting element or the like. Furthermore, according to the present invention, by using the light emitting element material, a light emitting element having high luminous efficiency and excellent durability can be obtained.

  First, the pyrene compound represented by the general formula (1) used in the present invention will be described.

R ^{1 to} R ⁹ may be the same or different and are each hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether Group, aryl group, heteroaryl group, condensed aryl group, condensed heteroaryl group, halogen, cyano group, phosphine oxide group, and silyl group. R ^{1 to} R ⁹ may form a ring with adjacent substituents. Ar ¹ is selected from an aryl group, a heteroaryl group, a fused aryl group, and a fused heteroaryl group, and when Ar ¹ is an aryl group or a heteroaryl group, at least one of R ⁴ and R ⁶ is an alkyl group, It is selected from a cycloalkyl group, an aryl group, a heteroaryl group, a fused aryl group, and a fused heteroaryl group.

  Among these substituents, the alkyl group is, for example, a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group. This may or may not have a substituent. There is no restriction | limiting in particular in the additional substituent in the case of being substituted, For example, an alkyl group, an aryl group, heteroaryl group, an amino group etc. can be mentioned, This point is common also in the following description. The number of carbon atoms of the alkyl group is not particularly limited, but is usually in the range of 1 to 20 and more preferably 1 to 8 from the viewpoint of availability and cost.

  The cycloalkyl group represents a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclohexyl, norbornyl, adamantyl, etc., which may or may not have a substituent. Although carbon number of an alkyl group part is not specifically limited, Usually, it is the range of 3-20.

  The heterocyclic group refers to an aliphatic ring having atoms other than carbon, such as a pyran ring, a piperidine ring, and a cyclic amide, in the ring, which may or may not have a substituent. . Although carbon number of a heterocyclic group is not specifically limited, Usually, it is the range of 2-20.

  An alkenyl group shows the unsaturated aliphatic hydrocarbon group containing double bonds, such as a vinyl group, an allyl group, and a butadienyl group, and this may or may not have a substituent. Although carbon number of an alkenyl group is not specifically limited, Usually, it is the range of 2-20.

  The cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond such as a cyclopentenyl group, a cyclopentadienyl group, or a cyclohexenyl group, which may have a substituent. You don't have to.

  An alkynyl group shows the unsaturated aliphatic hydrocarbon group containing triple bonds, such as an ethynyl group, for example, and may or may not have a substituent. Although carbon number of an alkynyl group is not specifically limited, Usually, it is the range of 2-20.

  The alkoxy group refers to, for example, a functional group having an aliphatic hydrocarbon group bonded through an ether bond such as a methoxy group, an ethoxy group, or a propoxy group, and the aliphatic hydrocarbon group may have a substituent. It may not have. Although carbon number of an alkoxy group is not specifically limited, Usually, it is the range of 1-20.

  The alkylthio group is a group in which an oxygen atom of an ether bond of an alkoxy group is substituted with a sulfur atom. The hydrocarbon group of the alkylthio group may or may not have a substituent. Although carbon number of an alkylthio group is not specifically limited, Usually, it is the range of 1-20.

  An aryl ether group refers to a functional group to which an aromatic hydrocarbon group is bonded via an ether bond, such as a phenoxy group, and the aromatic hydrocarbon group may or may not have a substituent. Good. Although carbon number of an aryl ether group is not specifically limited, Usually, it is the range of 6-40.

  An aryl thioether group is one in which the oxygen atom of the ether bond of the aryl ether group is substituted with a sulfur atom. The aromatic hydrocarbon group in the aryl ether group may or may not have a substituent. Although carbon number of an aryl ether group is not specifically limited, Usually, it is the range of 6-40.

  An aryl group refers to an aromatic hydrocarbon group in which aromatic rings are not condensed with each other, such as a phenyl group, a biphenyl group, a terphenyl group, and a quarterphenyl group. It does not have to be. Although carbon number of an aryl group is not specifically limited, Usually, it is the range of 6-40.

  The heteroaryl group refers to an aromatic group having atoms other than carbon in the ring, such as furanyl group, thiophenyl group, oxazolyl group, pyridyl group, pyrazyl group, and the aromatic rings are not condensed with each other, This may or may not have a substituent. Although carbon number of heteroaryl group is not specifically limited, Usually, it is the range of 2-30.

  The condensed aryl group refers to an aromatic hydrocarbon group in which two or more aromatic rings are condensed, such as a naphthyl group, a phenanthryl group, an anthracenyl group, a pyrenyl group, and the like, which has a substituent. It does not have to be. The number of carbon atoms of the fused aryl group is not particularly limited, but is usually in the range of 10 or more and 40 or less.

  A fused heteroaryl group has, for example, a benzofuranyl group, a dibenzofuranyl group, a quinolinyl group, a phenanthrolinyl group, a carbazolyl group, and the like, and has two or more aromatic rings condensed in the ring. An aromatic hydrocarbon group, which may or may not have a substituent. The number of carbon atoms of the fused heteroaryl group is not particularly limited, but is usually in the range of 5 to 30.

The halogen atom represents fluorine, chlorine, bromine or iodine.
The phosphine oxide group may or may not have a substituent. Examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group. These substituents are further substituted. May be.

  A silyl group refers to, for example, a functional group having a bond to a silicon atom, such as a trimethylsilyl group, which may or may not have a substituent. Although carbon number of a silyl group is not specifically limited, Usually, it is the range of 3-20. The number of silicon is usually 1 or more and 6 or less.

The above substituents may form a ring with adjacent substituents. Explained by the general formula (1), any two adjacent substituents selected from R ^{1 to} R ⁹ (for example, R ¹ and R ² ) are bonded to each other to form a conjugated or non-conjugated ring. . In addition to carbon, nitrogen, oxygen, sulfur, phosphorus, and silicon atoms may be included as ring constituent elements.

The pyrene compound represented by the general formula (1) of the present invention has a group selected from an aryl group, a heteroaryl group, a condensed aryl group, and a condensed heteroaryl group at the 2-position (Ar ¹ ) of the pyrene skeleton. When Ar ¹ is an aryl group or a heteroaryl group, at least one of R ⁴ and R ⁶ is selected from an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, a condensed aryl group, and a condensed heteroaryl group Thus, an excellent light emitting device material having high thin film stability is obtained. Among them, when Ar ^{1 in the} general formula (1) is an aryl group or a heteroaryl group, when at least one of R ⁴ and R ⁶ is selected from an aryl group, a heteroaryl group, a condensed aryl group, and a condensed heteroaryl group, Thin film stability when R ⁴ and R ⁶ are both selected from an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, a condensed aryl group, and a condensed heteroaryl group. Is preferable because of further improvement.

The pyrene compound represented by the general formula (1) of the present invention has a condensed aryl or condensed heteroaryl at the 2-position (Ar ¹ ) of the pyrene skeleton, whereby it becomes an excellent light-emitting element material having high thin film stability. . In particular, when Ar ¹ is selected from naphthyl, phenanthryl, anthracenyl, pyrenyl, benzofuranyl, benzothiophenyl, indolyl, dibenzofuranyl, dibenzothiophenyl and carbazolyl, This is preferable because the rate is improved. Ar ¹ is a condensed aryl group, and at least one of R ^{1 to} R ⁹ is selected from an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, a condensed aryl group, and a condensed heteroaryl group, or Ar ^It is preferable that ¹ is a condensed heteroaryl group and at least one of R ^{1 to} R ⁹ is selected from an alkyl group, a cycloalkyl group, an aryl group, and a condensed aryl group because the thin film stability is further improved.

Further, the formula (1) R ¹ to R ⁹ and Ar ¹ of at least one of, comprise a hole-transporting group, from the viewpoint of charge transporting property and durability. The hole transporting group is an alkyl group such as methyl group or t-butyl group, an alkoxy group such as methoxy group, a heteroaryl group such as furanyl group, thiophenyl group or pyrrolyl group, benzofuranyl group, dibenzofuranyl group, benzoic group. The substituent is not particularly limited as long as it is a substituent having an electron donating property such as a condensed heteroaryl group such as a thiophenyl group, a dibenzothiophenyl group, an indolyl group, and a carbazolyl group. Among them, a dibenzofuranyl group and a carbazolyl group are particularly preferable examples. It is done.

  Among the pyrene compounds represented by the general formula (1), the pyrene compound represented by the general formula (2) is preferable.

R ^{10 to} R ²⁶ may be the same as or different from each other, and hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an alkoxy group, an alkylthio group, an aryl ether group, and an aryl thioether Group, aryl group, heteroaryl group, condensed aryl group, condensed heteroaryl group, halogen, cyano group, phosphine oxide group, and silyl group. R ^{10 to} R ²⁶ may form a ring with adjacent substituents. Ar ² is selected from an aryl group, a heteroaryl group, a fused aryl group, and a fused heteroaryl group. The explanation of these substituents is the same as that of the general formula (1).

  Since the pyrene compound represented by the general formula (1) of the present invention has high fluorescence quantum yield and thin film stability, a light emitting device having high luminous efficiency and excellent durability can be obtained by using it as a light emitting device material. It becomes possible.

  Although it does not specifically limit as the above pyrene compounds, Specifically, the following examples are given.

  A known method can be used for the synthesis of the pyrene compound. Examples of the method for introducing an aryl group into the pyrene skeleton include a method using a coupling reaction between a halogenated pyrene derivative and an aryl boronic acid or aryl boronic acid ester under a palladium or nickel catalyst. As a method for introducing an aryl group into the 2-position of the pyrene skeleton, for example, after introducing a boronic acid ester into the 2-position of pyrene under an iridium catalyst, a cup of pyreneboronic acid ester and aryl halide under a palladium or nickel catalyst is used. A method using a ring reaction may be mentioned.

  Examples of a method for introducing an alkyl group into the pyrene skeleton include a method using a Friedel-Crafts reaction with an alkyl halide using a Lewis acid and a reduction reaction of a pyrenecarboxaldehyde derivative pyrenecarboxylic acid derivative.

  Next, embodiments of the light-emitting element in the present invention will be described with examples. The light emitting device of the present invention is composed of at least an anode and a cathode, and an organic layer made of a light emitting device material interposed between the anode and the cathode.

  The anode used in the present invention is not particularly limited as long as it can efficiently inject holes into the organic layer. However, it is preferable to use a material having a relatively large work function, for example, tin oxide, indium oxide, zinc oxide. Conductive metal oxides such as indium and indium tin oxide (ITO), metals such as gold, silver and chromium, inorganic conductive materials such as copper iodide and copper sulfide, conductive polymers such as polythiophene, polypyrrole and polyaniline, etc. Is mentioned. These electrode materials may be used alone, or a plurality of materials may be laminated or mixed.

  The resistance of the anode is not limited as long as a current sufficient for light emission of the light emitting element can be supplied, and is preferably low from the viewpoint of power consumption of the light emitting element. For example, an ITO substrate of 300Ω / □ or less will function as a device electrode, but since it is now possible to supply a substrate of about 10Ω / □, use a low-resistance product of 100Ω / □ or less. Is particularly desirable. The thickness of ITO can be arbitrarily selected according to the resistance value, but is usually used in a range of 100 to 300 nm.

In order to maintain the mechanical strength of the light emitting element, the light emitting element is preferably formed over a substrate. As the substrate, a glass substrate such as soda glass or non-alkali glass is preferably used. As the thickness of the glass substrate, it is sufficient that the thickness is sufficient to maintain the mechanical strength. The glass material is preferably alkali-free glass because it is better to have less ions eluted from the glass, but soda lime glass with a barrier coat such as SiO ₂ is also available on the market. it can. Furthermore, if the anode functions stably, the substrate does not have to be glass. For example, the anode may be formed on a plastic substrate. The ITO film forming method is not particularly limited, such as an electron beam method, a sputtering method, and a chemical reaction method.

  The material used for the cathode used in the present invention is not particularly limited as long as it is a substance that can efficiently inject electrons into the organic layer, but is generally platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium. Lithium, sodium, potassium, cesium, calcium and magnesium, and alloys thereof. Lithium, sodium, potassium, cesium, calcium, magnesium, or alloys containing these low work function metals are effective for increasing the electron injection efficiency and improving device characteristics. However, since these low work function metals are generally unstable in the atmosphere, they are stable by doping or laminating a small amount of lithium or magnesium in the organic layer (1 nm or less on the thickness gauge display of vacuum deposition). A preferred example is a method for obtaining a highly conductive electrode. Also, an inorganic salt such as lithium fluoride can be used. Furthermore, for electrode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, inorganic substances such as silica, titania and silicon nitride, polyvinyl alcohol, polyvinyl chloride Lamination of organic polymer compounds such as hydrocarbon polymer compounds is a preferred example. The method for producing these electrodes is not particularly limited as long as conduction can be achieved, such as resistance heating, electron beam, sputtering, ion plating, and coating.

  The light-emitting element of the present invention is formed of a light-emitting element material in which the organic layer contains a pyrene compound represented by the general formula (1). The light-emitting element material corresponds to either a compound that emits light by itself or a compound that assists the light emission, and refers to a compound that participates in light emission. Specifically, a hole-transport material, a light-emitting material, and an electron This includes transportation materials.

  The organic layer constituting the light emitting element of the present invention is composed of a light emitting layer having at least a light emitting element material. Examples of the organic layer include, in addition to the structure consisting of only the light emitting layer, 1) a hole transport layer / light emitting layer / electron transport layer, 2) light emitting layer / electron transport layer, and 3) hole transport layer / light emitting layer. And the like. Each of the layers may be a single layer or a plurality of layers. When the hole transport layer and the electron transport layer have a plurality of layers, the layers in contact with the electrodes may be referred to as a hole injection layer and an electron injection layer, respectively. In the material, the electron injection material is included in the electron transport material.

  The hole transport layer is formed by a method of laminating or mixing one or more hole transport materials or a method using a mixture of a hole transport material and a polymer binder. Alternatively, the hole transport layer may be formed by adding an inorganic salt such as iron (III) chloride to the hole transport material. The hole transport material is not particularly limited as long as it is a compound that forms a thin film necessary for manufacturing a light emitting element, can inject holes from the anode, and can further transport holes. For example, 4,4′-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl, 4,4 Triphenylamine derivatives such as', 4 "-tris (3-methylphenyl (phenyl) amino) triphenylamine, biscarbazole derivatives such as bis (N-allylcarbazole) or bis (N-alkylcarbazole), pyrazoline derivatives, Heterocyclic compounds such as stilbene compounds, hydrazone compounds, benzofuran derivatives and thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives, and polymer systems such as polycarbonates, styrene derivatives, polythiophene, polyaniline , Polyfluorene, poly Such alkenyl carbazole and polysilane are preferred. There.

  In the present invention, the light emitting layer may be either a single layer or a plurality of layers, both of which are formed of a light emitting material mainly composed of a host material and a dopant material. The light emitting material may be a mixture of a host material and a dopant material, or may be a host material alone. That is, in the light emitting device of the present invention, in each light emitting layer, only one of the host material and the dopant material may emit light, or both the host material and the dopant material may emit light. Each of the host material and the dopant material may be one kind or a plurality of combinations. The dopant material may be included in the entire host material or may be partially included. The dopant material may be laminated or dispersed. If the amount of the dopant material is too large, a concentration quenching phenomenon occurs, so that it is preferably used at 20% by weight or less, more preferably 10% by weight or less with respect to the host material. The doping method can be formed by a co-evaporation method with a host material, but may be pre-mixed with the host material and then simultaneously deposited.

  The pyrene compound represented by the general formula (1) is suitably used as a light emitting material of the light emitting device of the present invention. In addition, the pyrene compound of the present invention exhibits strong light emission in the blue region and is therefore preferably used as a blue light emitting material, but can also be used as a material for green to red light emitting elements and white light emitting elements. Although the pyrene compound of this invention may be used as a dopant material, since it is excellent in thin film stability, it is used suitably as a host material.

  The ionization potential of the pyrene compound represented by the general formula (1) of the present invention is not particularly limited, but is preferably 4.6 eV or more and 6.0 eV or less, more preferably 4.8 eV or more and 5.8 eV or less. . Although the absolute value of the ionization potential may vary depending on the measurement method, the ionization potential of the present invention is an ITO glass substrate using an atmospheric-type ultraviolet photoelectron analyzer (AC-1, manufactured by Riken Kikai Co., Ltd.). It is the value which measured the thin film vapor-deposited on the thickness of 30 nm-100 nm on the top.

  The host material used in the present invention need not be limited to one kind of pyrene compound represented by the general formula (1) of the present invention, and a plurality of pyrene compounds of the present invention may be mixed and used. One or more kinds may be used as a mixture with the pyrene compound of the present invention. Examples of the host material that can be mixed include condensed aryl derivatives such as anthracene and pyrene as light emitters, N, N′-dinaphthyl-N, N′-diphenyl-4,4′-diphenyl-1,1′-diamine, and the like. Aromatic amine derivatives, metal chelated oxinoid compounds such as tris (8-quinolinato) aluminum (III), bisstyryl derivatives such as distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, For pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadiazole derivatives, carbazole derivatives, pyrrolopyrrole derivatives, polymers, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinyl Tetrazole derivatives, polythiophene derivatives are suitably used.

  The dopant material contained in the light-emitting material is not particularly limited, but a compound having an aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, triphenylene, perylene, fluorene, indene, or a derivative thereof (for example, 2- (benzothiazole-2- Yl) -9,10-diphenylanthracene and 5,6,11,12-tetraphenylnaphthacene), furan, pyrrole, thiophene, silole, 9-silafluorene, 9,9'-spirobisilafluorene, benzothiophene , Benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, thioxanthene, etc. Aminostyryl such as zen derivatives, 4,4′-bis (2- (4-diphenylaminophenyl) ethenyl) biphenyl, 4,4′-bis (N- (stilben-4-yl) -N-phenylamino) stilbene Derivatives, aromatic acetylene derivatives, tetraphenylbutadiene derivatives, stilbene derivatives, aldazine derivatives, pyromethene derivatives, diketopyrrolo [3,4-c] pyrrole derivatives, 2,3,5,6-1H, 4H-tetrahydro-9- (2 Coumarin derivatives such as' -benzothiazolyl) quinolidino [9,9a, 1-gh] coumarin, azole derivatives such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, triazole and metal complexes thereof, and N, N'-diphenyl -N, N'-di (3-methyl And aromatic amine derivatives typified by phenyl) -4,4'-diphenyl-1,1'-diamine. Among them, it is preferable to use a condensed aryl derivative having an electron-accepting substituent as a dopant because the effect of the thin film stability of the pyrene compound of the present invention becomes more remarkable. Specifically, pyrene compounds having a benzoazole group typified by 1- (benzoxazol-2-yl) -3,8-bis (4-methylphenyl) pyrene are particularly preferable dopants.

  In the present invention, the electron transport layer is a layer in which electrons are injected from the cathode and further transports electrons. The electron transport layer has high electron injection efficiency, and it is desired to efficiently transport injected electrons. Therefore, it is desirable that the electron transport layer is made of a material having a high electron affinity, a high electron mobility, excellent stability, and a trapping impurity that is unlikely to be generated during manufacture and use. However, considering the transport balance between holes and electrons, if the electron transport layer mainly plays a role of effectively preventing the holes from the anode from recombining and flowing to the cathode side, the electron transport Even if it is made of a material that does not have a high capability, the effect of improving the luminous efficiency is equivalent to that of a material that has a high electron transport capability. Therefore, the electron transport layer in the present invention includes a hole blocking layer that can efficiently block the movement of holes as the same meaning.

  The electron transport material used for the electron transport layer is not particularly limited, but is a compound having a condensed aryl ring such as naphthalene or anthracene or a derivative thereof, or a styryl-based fragrance represented by 4,4′-bis (diphenylethenyl) biphenyl. Ring derivatives, perylene derivatives, perinone derivatives, coumarin derivatives, naphthalimide derivatives, quinone derivatives such as anthraquinone and diphenoquinone, phosphorus oxide derivatives, carbazole derivatives and indole derivatives, quinolinol complexes such as tris (8-quinolinolato) aluminum (III) and hydroxy Examples thereof include hydroxyazole complexes such as phenyloxazole complexes, azomethine complexes, tropolone metal complexes and flavonol metal complexes, and compounds having a heteroaryl ring having electron-accepting nitrogen.

  The electron-accepting nitrogen in the present invention represents a nitrogen atom that forms a multiple bond with an adjacent atom. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron accepting property. Therefore, heteroaryl rings containing electron-accepting nitrogen have a high electron affinity. Heteroaryl rings containing electron-accepting nitrogen include, for example, pyridine ring, pyrazine ring, pyrimidine ring, quinoline ring, quinoxaline ring, naphthyridine ring, pyrimidopyrimidine ring, benzoquinoline ring, phenanthroline ring, imidazole ring, oxazole ring, oxalate ring, Examples include a diazole ring, a triazole ring, a thiazole ring, a thiadiazole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, and a phenanthrimidazole ring.

  The compound having a heteroaryl ring structure containing electron-accepting nitrogen of the present invention is preferably composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon and phosphorus. A compound having a heteroaryl ring structure containing electron-accepting nitrogen composed of these elements has a high electron transporting ability and can significantly reduce a driving voltage.

  Examples of compounds having a heteroaryl ring structure containing an electron-accepting nitrogen and composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus include benzimidazole derivatives, benzoxazole derivatives, and benzthiazoles. Preferred examples include derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoquinoline derivatives, oligopyridine derivatives such as bipyridine and terpyridine, quinoxaline derivatives, and naphthyridine derivatives. . Among them, imidazole derivatives such as tris (N-phenylbenzimidazol-2-yl) benzene, oxadiazole derivatives such as 1,3-bis [(4-tert-butylphenyl) 1,3,4-oxadiazolyl] phenylene, Triazole derivatives such as N-naphthyl-2,5-diphenyl-1,3,4-triazole, phenanthroline derivatives such as bathocuproine and 1,3-bis (1,10-phenanthroline-9-yl) benzene, 2,2 ′ A benzoquinoline derivative such as bis (benzo [h] quinolin-2-yl) -9,9′-spirobifluorene, 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1, Bipyridine derivatives such as 1-dimethyl-3,4-diphenylsilole, 1,3-bis (4 ′-(2,2 ′: 6′2 ″ -ta Terpyridine derivatives such as pyridinyl)) benzene, naphthyridine derivatives such as bis (1-naphthyl) -4- (1,8-naphthyridin-2-yl) phenylphosphine oxide are preferably used from the viewpoint of electron transporting capability. Furthermore, 1,3-bis (1,10-phenanthroline-9-yl) benzene, 2,7-bis (1,10-phenanthroline-9-yl) naphthalene, 1,3-bis (2-phenyl-1, Phenanthroline dimers such as 10-phenanthroline-9-yl) benzene, 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1,1-dimethyl-3,4-diphenylsilole, etc. This bipyridine dimer has a significantly high durability improving effect when combined with the pyrene compound represented by the general formula (1) of the present invention, and is particularly preferable.

  The electron transport material may be used alone, but two or more of the electron transport materials may be mixed and used, or one or more of the other electron transport materials may be mixed with the electron transport material. It is also possible to use a mixture with a metal such as an alkali metal or an alkaline earth metal. The ionization potential of the electron transport layer is not particularly limited, but is preferably 5.8 eV or more and 8.0 eV or less, and more preferably 6.0 eV or more and 7.5 eV or less.

  The method of forming each layer constituting the light emitting element is not particularly limited, such as resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination method, coating method, etc., but resistance heating vapor deposition or electron beam vapor deposition is usually used in terms of element characteristics. preferable.

  The thickness of the layer cannot be limited because it depends on the resistance value of the light emitting element material, but is selected from 1 to 1000 nm. The film thicknesses of the light emitting layer, the electron transport layer, and the hole transport layer are each preferably 1 nm to 200 nm, and more preferably 5 nm to 100 nm.

  The light-emitting element of the present invention has a function of converting electrical energy into light. Here, a direct current is mainly used as the electric energy, but a pulse current or an alternating current can also be used. The current value and voltage value are not particularly limited, but should be selected so that the maximum luminance can be obtained with as low energy as possible in consideration of the power consumption and lifetime of the device.

  The light emitting device of the present invention is suitably used as a display for displaying in a matrix and / or segment system, for example.

  In the matrix method, pixels for display are two-dimensionally arranged such as a lattice shape or a mosaic shape, and a character or an image is displayed by a set of pixels. The shape and size of the pixel are determined by the application. For example, a square pixel with a side of 300 μm or less is usually used for displaying images and characters on a personal computer, monitor, TV, and a pixel with a side of mm order for a large display such as a display panel. become. In monochrome display, pixels of the same color may be arranged. However, in color display, red, green, and blue pixels are displayed side by side. In this case, there are typically a delta type and a stripe type. The matrix driving method may be either a line sequential driving method or an active matrix. Although the structure of the line sequential drive is simple, the active matrix may be superior in consideration of the operation characteristics, and it is necessary to use it depending on the application.

  The segment system in the present invention is a system in which a pattern is formed so as to display predetermined information and an area determined by the arrangement of the pattern is caused to emit light. For example, the time and temperature display in a digital clock or a thermometer, the operation state display of an audio device or an electromagnetic cooker, the panel display of an automobile, etc. The matrix display and the segment display may coexist in the same panel.

  The light emitting device of the present invention is also preferably used as a backlight for various devices. The backlight is used mainly for the purpose of improving the visibility of a display device that does not emit light, and is used for a liquid crystal display device, a clock, an audio device, an automobile panel, a display panel, a sign, and the like. In particular, the light-emitting element of the present invention is preferably used for a backlight for a liquid crystal display device, particularly a personal computer for which a reduction in thickness is being considered, and a backlight that is thinner and lighter than conventional ones can be provided.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited by these Examples. In addition, the number of the compound in each following Example points out the number of the compound described in the above chemical formula.

Example 1 (Synthesis Method of Compound [23])
A mixed solution of 2 g of 1-bromopyrene, 1.90 g of 4-t-butylphenylboronic acid, 3.13 g of tripotassium phosphate, 460 mg of tetrabutylammonium bromide, 69.9 mg of palladium acetate and 70 ml of degassed dimethylformamide was streamed with nitrogen. Under stirring at 130 ° C. for 2 hours. After cooling to room temperature, it was poured into 350 ml of water, and the precipitated solid was filtered. The obtained solid was dissolved in dichloromethane, washed with water, dried over magnesium sulfate, and concentrated by evaporation. The obtained solid was purified by silica gel column chromatography to obtain 1.94 g of 1- (4-t-butylphenyl) pyrene.

1.94 g of 1- (4-t-butylphenyl) pyrene, bis (pinacolato) diboron 900 mg, [Ir (OMe) (COD)] ₂ 194 mg, 4,4′-di-t-butyl-2,2 ′ -A mixed solution of 163 mg of bipyridyl and 60 ml of degassed cyclohexane was heated and stirred at 80 ° C for 9.5 hours under a nitrogen stream. After cooling to room temperature, it was concentrated. The obtained oil was purified by silica gel column chromatography to give 2- (1- (4-t-butylphenyl) pyren-7-yl) -4,4,5,5-tetramethyl-1,3,2 -609 mg of dioxaborolane was obtained.

  609 mg of 2- (1- (4-t-butylphenyl) pyren-7-yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 280 μl of bromobenzene, tripotassium phosphate A mixed solution of 1.17 g, tetrabutylammonium bromide 175 mg, palladium acetate 14.4 mg and degassed dimethylformamide 15 ml was heated and stirred at 130 ° C. for 8 hours under a nitrogen stream. After cooling to room temperature, it was poured into 75 ml of water, and the precipitated solid was filtered. The obtained solid was dissolved in dichloromethane, washed with water, dried over magnesium sulfate, and concentrated by evaporation. The obtained solid was purified by silica gel column chromatography to obtain 494 mg of 1- (4-t-butylphenyl) -7-phenylpyrene.

  A mixed solution of 494 mg of 1- (4-tert-butylphenyl) -7-phenylpyrene, 120 ml of dichloromethane and 40 ml of methanol was cooled to 0 ° C. under a nitrogen stream. To the solution, 10 ml of a dichloromethane solution of 523 mg of benzyltrimethylammonium tribromide was added dropwise and stirred at room temperature for 6 hours. 200 ml of water was added, extracted with dichloromethane, dried over magnesium sulfate, and concentrated by evaporation. The obtained solid was purified by silica gel column chromatography to obtain 515 mg of 1- (4-t-butylphenyl) -3-bromo-7-phenylpyrene.

  515 mg of 1- (4-tert-butylphenyl) -3-bromo-7-phenylpyrene, 9- (4- (4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2- Yl) phenyl) -9H-carbazole 591 mg, tripotassium phosphate 452 mg, tetrabutylammonium bromide 72.1 mg, palladium acetate 10.3 mg and degassed dimethylformamide 20 ml in a nitrogen stream at 130 ° C. for 5 hours Stir with heating. After cooling to room temperature, it was poured into 100 ml of water, and the precipitated solid was filtered. The obtained solid was dissolved in dichloromethane, washed with water, dried over magnesium sulfate, and concentrated by evaporation. The obtained solid was purified by silica gel column chromatography to obtain 542 mg of compound [23].

Example 2
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam vapor-deposited product) on which an ITO transparent conductive film is deposited to 150 nm is cut to 30 × 40 mm, and the ITO conductive film is patterned by a photolithography method to produce a light emitting portion And the electrode extraction part was produced. The obtained substrate was ultrasonically cleaned with acetone and semicocrine 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes and dried. Immediately before the device was fabricated, this substrate was subjected to UV-ozone treatment for 1 hour, further placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁵ Pa or less. By the resistance heating method, first, copper phthalocyanine was deposited as a hole injecting material at 10 nm, and 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl was deposited as a hole transporting material at 50 nm. Next, the compound [23] as a host material and a D-1 represented by the following formula as a dopant material were vapor-deposited to a thickness of 35 nm so as to have a doping concentration of 5%. Next, as an electron transport material, E-1 represented by the following formula was laminated to a thickness of 20 nm. On the organic layer formed as described above, lithium fluoride was vapor-deposited to a thickness of 0.5 nm, and then aluminum was vapor-deposited with a thickness of 1000 nm to form a 5 × 5 mm square device. The film thickness referred to here is a display value of a crystal oscillation type film thickness monitor. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency blue light emission with a light emission efficiency of 5.0 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 4000 hours.

Comparative Example 1
A light emitting device was produced in the same manner as in Example 2 except that H-1 shown by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , blue light emission with a luminous efficiency of 2.7 lm / W was obtained. When this light emitting device was continuously driven with a direct current of 10 mA / cm ² , the luminance was reduced by half in 300 hours.

Comparative Example 2
A light emitting device was produced in the same manner as in Example 2 except that H-2 shown by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , blue light emission with a luminous efficiency of 2.5 lm / W was obtained. When this light emitting device was continuously driven with a direct current of 10 mA / cm ² , the luminance was reduced by half in 500 hours.

Comparative Example 3
A light emitting device was produced in the same manner as in Example 2 except that H-3 represented by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , blue light emission with a light emission efficiency of 2.9 lm / W was obtained. When this light emitting device was continuously driven with a direct current of 10 mA / cm ² , the luminance was reduced by half in 800 hours.

Comparative Example 4
A light emitting device was produced in the same manner as in Example 2 except that H-4 represented by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , blue light emission with a luminous efficiency of 3.0 lm / W was obtained. When this light emitting device was continuously driven with a direct current of 10 mA / cm ² , the luminance was reduced by half in 400 hours.

Example 3
A light emitting device was produced in the same manner as in Example 2 except that the compound [78] was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency blue light emission with a light emission efficiency of 5.2 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 6000 hours.

Example 4
A light emitting device was produced in the same manner as in Example 2 except that E-2 shown in the following formula was used as the electron transport material. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency blue light emission with a light emission efficiency of 5.8 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 5000 hours.

Example 5
A light emitting device was produced in the same manner as in Example 2 except that E-3 represented by the following formula was used as the electron transport material. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency blue light emission with a light emission efficiency of 3.5 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 3500 hours.

Example 6
A light emitting device was produced in the same manner as in Example 2 except that D-2 represented by the following formula was used as the dopant material and the doping concentration was 2%. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency blue light emission of 4.2 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 6500 hours.

Example 7
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam evaporation product) on which an ITO transparent conductive film is deposited to 150 nm is cut into 30 × 40 mm, and a 300 μm pitch (remaining width 270 μm) × 32 pieces is obtained by photolithography. Patterned into stripes. One side of the ITO stripe in the long side direction is expanded to a pitch of 1.27 mm (opening width 800 μm) in order to facilitate electrical connection with the outside. The obtained substrate was ultrasonically washed with acetone and semicocrine 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes, respectively, and then washed with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes and dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl was deposited as a hole transport material by a resistance heating method to a thickness of 150 nm. Next, compound [23] was deposited as a host material, and D-1 was deposited as a dopant material to a thickness of 35 nm so that the doping concentration was 5%. Next, E-1 was laminated to a thickness of 20 nm as an electron transport material. The film thickness referred to here is a crystal oscillation type film thickness monitor display value. Next, the mask provided with 16 250 μm openings (corresponding to the remaining width of 50 μm and 300 μm pitch) by wet etching on a 50 μm thick Kovar plate was replaced with a mask so as to be orthogonal to the ITO stripe in vacuum, It fixed with the magnet from the back surface so that a mask and an ITO board | substrate might closely_contact | adhere. Then, after 0.5 nm of lithium fluoride was deposited, 200 nm of aluminum was deposited to prepare a 32 × 16 dot matrix element. When this element was driven in matrix, characters could be displayed without crosstalk.

Claims (7)

A light emitting device material comprising a pyrene compound represented by the general formula (1).

(R ^{1 to} R ⁹ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, alkoxy group, aryl ether group, aryl group, heteroaryl group, naphthyl group, phenanthryl group, anthracenyl group, pyrenyl group , Benzofuranyl group, dibenzofuranyl group, benzothiophenyl group, dibenzothiophenyl group, indolyl group, carbazolyl group , Ar ¹ is selected from among aryl group, naphthyl group, phenanthryl group, anthracenyl group, pyrenyl group When Ar ¹ is an aryl group, at least one of R ⁴ and R ⁶ is an aryl group, heteroaryl group, naphthyl group, phenanthryl group, anthracenyl group, pyrenyl group , benzofuranyl group, dibenzofuranyl group, benzo Thiophenyl group, dibenzothiophene Group, an indolyl group, .Ar ¹ is naphthyl group selected from carbazolyl group, phenanthryl group, anthracenyl group, when the pyrenyl ^group, at least one of R ¹ to R 9, Ar ¹ is, t- butyl group , A group selected from a dibenzofuranyl group and a carbazolyl group.) The light emitting device material according to claim 1, wherein Ar ^{1 of the} pyrene compound represented by the general formula (1) is selected from a naphthyl group, a phenanthryl group, an anthracenyl group, and a pyrenyl group. The light emitting device material according to claim 1, wherein the pyrene compound represented by the general formula (1) is represented by the general formula (2).

(R ^{10 to} R ²⁶ may be the same as or different from each other, hydrogen, alkyl group, aryl group, heteroaryl group, naphthyl group, phenanthryl group, anthracenyl group, pyrenyl group , benzofuranyl group, dibenzofuranyl group, benzothiol. Ar ² is selected from phenyl, dibenzothiophenyl, indolyl, carbazolyl, Ar ² is aryl, heteroaryl, naphthyl, phenanthryl, anthracenyl, pyrenyl , benzofuranyl , dibenzofuranyl, benzo It is selected from among thiophenyl group, dibenzothiophenyl group, indolyl group and carbazolyl group , provided that at least one of R ^{10 to} R ²⁶ and Ar ² is a t-butyl group, dibenzofuranyl group or carbazolyl group. A group selected from: The light emitting device material according to claim 1, wherein at least one of R ^{1 to} R ⁹ and Ar ¹ contains a hole transporting group. A light-emitting element having at least a light-emitting layer between an anode and a cathode and emitting light by electric energy, wherein the light-emitting element contains the light-emitting element material according to claim 1. . 6. The light emitting device according to claim 5, wherein the light emitting layer contains a host material and a dopant material, and the light emitting device material containing the compound represented by the general formula (1) is a host material. There is at least an electron transport layer between the light-emitting layer and the cathode, and the electron transport layer contains an electron-accepting nitrogen, and is further composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus. The light emitting device according to claim 5, comprising a compound having an aryl ring structure.