JP2010056190A - Light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element excellent in high luminous efficiency and durability. <P>SOLUTION: The light-emitting element at least includes a luminous layer between an anode and a cathode, emits light by electric energy, and includes a pyrene compound expressed by a general formula (1) and a pyrene compound having a specific structure. R<SP>1</SP>to R<SP>18</SP>may be the same or different from one another; and selection is performed from among hydrogen, an alkyl group, a cyclo alkyl group, a heterocycle group, an alkenyl group, a cyclo alkenyl group, an alkynyl group, an alkoxy group, an alkylthio group, an arylether group, an arylthioether group, an aryl group, a hetero aryl group, halogen, an amino group, a cyano group, a silyl group and -P(=O)-R<SP>19</SP>R<SP>20</SP>, and ring structures formed with adjacent substituent groups. For R<SP>19</SP>and R<SP>20</SP>, selection is performed from the aryl group and the hetero aryl group. N-pieces of R<SP>1</SP>to R<SP>10</SP>and one of R<SP>11</SP>to R<SP>18</SP>are used for a single bond where n is an integer among 1 to 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pyrene compound useful as a fluorescent dye or a charge transport agent 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 a field 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 C.D. 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: are those which sequentially provided Ag, it was capable of green light emission of 1,000 cd / ^{m 2} at about 10V driving voltage (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. In particular, research on light emitting materials of the three primary colors of red, green, and blue is the most active, and intensive research has been conducted with the aim of improving characteristics.

One of the biggest problems in organic thin film light emitting devices is the improvement of the durability and luminous efficiency of the devices. As a means for obtaining a high-efficiency light-emitting element, a method is known in which a light-emitting layer is formed by doping a host material with a dopant material (fluorescent material) of several percent (see Patent Document 1). The host material is required to have high carrier mobility and uniform film formability, and the dopant material is required to have high fluorescence quantum yield and uniform dispersibility. Examples of blue materials include styrylamine derivatives (see Patent Document 2), perylene derivatives (see Patent Document 3), tetraphenylpyrene compounds (see Patent Document 4) and oligoarylene derivatives (see Patent Document 5), bulky substitutions A technique using a pyrene derivative having a group introduced therein (see Patent Document 6) is disclosed. Examples of green materials include stilbene compounds (see Patent Document 7), quinoline derivatives and quinacridone compounds (see Patent Document 8), and examples of red materials include aminostyryl compounds (see Patent Document 9), perinone derivatives and pyromethene compounds (Patent Documents). 10), a coumarin compound and a dicyanomethylenepyran compound (see Patent Document 11), etc. have been disclosed, but none showed sufficient luminous efficiency and durability. In addition to the above, there are a large number of host materials and dopant materials that form a light emitting material, and the number of these materials becomes enormous when they are combined. In general, the degree of overlap between the fluorescence spectrum of the host material and the absorption spectrum of the dopant material and the intermolecular distance are known as guidelines for the ease of energy transfer from the host material to the dopant material (non-patented). However, not all the light emission mechanisms have been elucidated, and there are many trial and error parts. That is, in order to obtain a light-emitting element having better light-emitting characteristics, it is very important to find a combination of light-emitting element materials such as an optimal host material and dopant material.
“Applied Physics Letters”, (USA), 1987, 51, 12, p. 913-915 Japanese Patent No. 2814435 JP-A-5-17765 JP 2003-86380 A JP 2001-118682 A JP 2004-75567 A JP 2002-63988 A JP-A-2-247278 JP-A-3-255190 JP 2002-134276 A Japanese Patent Laid-Open No. 2001-223082 JP-A-5-202356 “Organic EL elements and the forefront of industrialization”, NTS, 1998, p. 66

  Accordingly, an object of the present invention is to solve the problems of the prior art and provide a light emitting device having high light emission efficiency and excellent durability.

  An element that has at least a light emitting layer between an anode and a cathode and emits light by electric energy, and the element is represented by at least a pyrene compound represented by the general formula (1) and the general formula (2). A light-emitting element containing a pyrene compound.

(R ^{1 to} R ¹⁸ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, an aryl group, selected from the cyclic structure formed between the heteroaryl group, halogen, an amino group, a cyano group, a silyl group, and ^{-P (= O) -R 19 R} 20, and adjacent substituents R ¹⁹ and R ²⁰ are selected from an aryl group and a heteroaryl group, n is an integer of 1 to 4. Any one of R ^{1 to} R ¹⁰ and any of R ^{11 to} R ¹⁸ One is used for a single bond.

(R ^{21 to} R ³⁰ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl Selected from ring structures formed between thioether groups, aryl groups, heteroaryl groups, halogens, amino groups, cyano groups, silyl groups and —P (═O) —R ³¹ R ³² , and adjacent substituents R ³¹ and R ³² are selected from an aryl group and a heteroaryl group, provided that any one of R ^{21 to} R ³⁰ is a group represented by the following general formula (3), or Any one to four are groups represented by the following general formula (4). P is a phosphorus atom.)

(R ^{33 to} R ⁴¹ may be the same as or different from each other, and may be hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl. A ring structure formed between a thioether group, an aryl group, a heteroaryl group, a halogen, an amino group, a cyano group, a silyl group, and an adjacent substituent, B is a boron atom, and X is Either a nitrogen atom or -CR ⁴² =, C is a carbon atom, R ⁴² is 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 and amino group From a group selected .R ⁴² MAY form R ³⁸ and ring structure .Y represents an oxygen atom, a sulfur atom and -NR 43 ^- In .N is a group selected from among a nitrogen atom R ⁴³ is 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 and amino And R ⁴³ may form a ring structure with R ^41. m is an integer of 1 to 4.)

  According to the present invention, a light emitting device having high luminous efficiency and excellent durability can be obtained.

  The light emitting device of the present invention comprises 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 anode materials may be used alone, or a plurality of materials may be laminated or mixed.

  The resistance of the anode is sufficient if a current sufficient for light emission of the light emitting element can be supplied, and it is desirable that the resistance be 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 can efficiently inject electrons into the organic layer, but generally platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, Examples thereof include chromium, lithium, sodium, potassium, cesium, calcium, 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, these low work function metals are generally unstable in the atmosphere. For example, the organic layer is doped with a small amount of lithium or magnesium (1 nm or less in the vacuum vapor deposition thickness gauge display) to be stable. A preferred example is a method using a high cathode. Also, an inorganic salt such as lithium fluoride can be used. Furthermore, for cathode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, and inorganic materials such as silica, titania and silicon nitride, polyvinyl alcohol, vinyl chloride Lamination of hydrocarbon polymer compounds and the like is a preferred example. The method for producing these cathodes is not particularly limited as long as conduction can be achieved, such as resistance heating, electron beam, sputtering, ion plating, and coating. The thickness of the cathode can be arbitrarily selected according to the resistance value, but is usually used in a range of 100 to 300 nm.

  The organic layer constituting the light emitting device of the present invention is composed of at least a light emitting layer. As an example of the organic layer configuration, in addition to the configuration consisting of only the light emitting layer, 1) hole transport layer / light emitting layer / electron transport layer, 2) light emitting layer / electron transport layer, 3) hole transport layer / light emitting layer And the like. Moreover, each said layer may consist of a single layer, respectively, and may consist of multiple layers. When the hole transport layer and the electron transport layer are composed of a plurality of layers, the layers in contact with the electrode may be referred to as the hole injection layer and the 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 laminating and mixing one or more hole transport materials or a mixture of the hole transport material and the polymer binder. Examples of the hole transport material include 4,4′-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl and 4,4′-bis (N- (1-naphthyl) -N-phenyl. Amino) biphenyl, triphenylamine derivatives such as 4,4 ′, 4 ″ -tris (3-methylphenyl (phenyl) amino) triphenylamine, bis (N-allylcarbazole) or bis (N-alkylcarbazole) Biscarbazole derivatives, pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives and thiophene derivatives, heterocyclic compounds such as oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives, polycarbonates having the above monomers in the side chain in polymer systems And styrene derivatives, polythiophene, polyaniline Polyfluorene, polyvinylcarbazole, polysilane, and the like are preferable, but there is no particular limitation as long as it is a compound that can form a thin film necessary for manufacturing a light-emitting element, can inject holes from the anode, and can further transport holes. .

  In the present invention, the light emitting layer may be either a single layer or a plurality of layers, each formed of a light emitting material (host material, dopant material), which may be a mixture of a host material and a dopant material, Either the material alone or the material may be used. That is, in the light emitting element of the present invention, only the host material or the dopant material may emit light in each light emitting layer, 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. As a doping method, it can be formed by a co-evaporation method with a host material, but it may be pre-mixed with the host material and then simultaneously deposited. In addition to the vapor deposition method, after the host material and the dopant material are mixed and dissolved in an organic solvent such as toluene, dichloromethane, or NMP, the light emitting layer can be formed by a wet process such as an inkjet method.

  The pyrene compound represented by the general formula (1) and the pyrene compound represented by the general formula (2) of the present invention are preferably used as a light emitting device material and particularly preferably used as a light emitting material. Further, the pyrene compound represented by the general formula (1) of the present invention can be used as a dopant material, but is used as a host material in consideration of high hole transfer characteristics obtained by substituting a dibenzofuranyl group. It is preferable. Moreover, although the pyrene compound shown by General formula (2) of this invention can be used also as a host material, when it considers that the high fluorescence quantum yield and spectrum half value width are narrow, using as a dopant material is preferable. Since both the pyrene compound represented by the general formula (1) and the pyrene compound represented by the general formula (2) of the present invention have a pyrene skeleton, it is easy to form a uniform light emitting layer film and the durability is improved. . In addition, since the energy transfer efficiency from the host material to the dopant material is increased, the device luminous efficiency is increased. In particular, the compatibility of the pyrene compound represented by the general formula (1) having a dibenzofuranyl group which is an electron-donating substituent and the pyrene compound represented by the general formula (2) having an electron-accepting substituent is various. It is particularly preferable among combinations of a certain host material and a dopant material, and superior device characteristics can be obtained as compared with a case where each material is combined with another host or dopant material.

  The dopant material used in the present invention need not be limited to only one pyrene compound represented by the general formula (2), and a mixture of pyrene compounds represented by a plurality of general formulas (2) may be used. One or more dopant materials may be mixed with the pyrene compound represented by the general formula (2). Specifically, conventionally known compounds having an aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, triphenylene, perylene, fluorene, indene and derivatives thereof, furan, pyrrole, thiophene, silole, 9-silafluorene, Compounds having a heteroaryl ring such as 9,9′-spirobisilafluorene, benzothiophene, benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, thioxanthene, and derivatives thereof; Distyrylbenzene derivative, aromatic acetylene derivative, tetraphenylbutadiene derivative, pyromethene derivative, aldazine derivative, coumarin derivative, imidazole, thiazole, thiadi Tetrazole, carbazole, oxazole, oxadiazole, although such azole derivatives such as triazole, and metal complexes thereof and the like, but is not limited thereto.

  The host material used in the present invention is not limited to one kind of pyrene compound represented by the general formula (1), and a plurality of pyrene compounds represented by the general formula (1) may be used in combination. One or more kinds of materials may be mixed with the pyrene compound represented by the general formula (1). Specifically, compounds having a condensed aryl ring, such as anthracene, which have been known as light emitters, and derivatives thereof, and aromatics such as 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl are known. Group amine derivatives, metal chelated oxinoid compounds such as tris (8-quinolinolato) aluminum (III), bisstyryl derivatives such as distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolo Pyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadiazole derivatives, carbazole derivatives, pyrrolopyrrole derivatives, in the polymer system, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinyl The tetrazole derivatives, polythiophene derivatives are suitably used. Among these, it is preferable to use an anthracene compound having an electron-donating substituent as a host material because the durability improvement effect becomes remarkable when combined with the pyrene compound represented by the general formula (1) of the present invention. Specifically, an anthracene compound having a carbazole group represented by 9- (4- (carbazol-N-yl) phenyl) -10- (4-methylphenyl) anthracene is particularly preferable.

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

R ^{1 to} R ¹⁸ may be the same or different from each other, and may be 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, halogen, amino group, cyano group, silyl group and —P (═O) —R ¹⁹ R ²⁰ , and a ring structure formed between adjacent substituents . R ¹⁹ and R ²⁰ are selected from an aryl group and a heteroaryl group. n is an integer of 1-4. Any one of R ^{1 to} R ¹⁰ and any one of R ^{11 to} R ¹⁹ are used for a single bond. P is a phosphorus atom.

  Among these substituents, the alkyl group represents, for example, a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group, or a butyl group, which may be unsubstituted or substituted. The substituent in the case of being substituted is not particularly limited, and examples thereof include an alkyl group, an aryl group, a heteroaryl group, and the like, and this point is common to the following description. Further, the number of carbon atoms of the alkyl group is not particularly limited, but is usually in the range of 1 to 20 from the viewpoint of availability and cost.

  The cycloalkyl group represents a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclohexyl, norbornyl, adamantyl, and the like, which may be unsubstituted or substituted. 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 a group consisting of an aliphatic ring having atoms other than carbon, such as a pyran ring, piperidine ring and cyclic amide, in the ring, which may be unsubstituted or substituted. . Although carbon number of a heterocyclic group is not specifically limited, Usually, it is the range of 2-20.

  Moreover, an alkenyl group shows the unsaturated aliphatic hydrocarbon group containing double bonds, such as a vinyl group, an allyl group, and a butadienyl group, for example, and this may be unsubstituted or substituted. 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 is unsubstituted or substituted. It doesn't matter.

  The alkynyl group refers to an unsaturated aliphatic hydrocarbon group containing a triple bond such as an ethynyl group, which may be unsubstituted or substituted. 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, an aliphatic hydrocarbon group via an ether bond such as a methoxy group, and the aliphatic hydrocarbon group may be unsubstituted or substituted. 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 aryl ether group refers to, for example, an aromatic hydrocarbon group via an ether bond such as a phenoxy group, and the aromatic hydrocarbon group may be unsubstituted or substituted. Although carbon number of an aryl ether group is not specifically limited, Usually, it is the range of 6-40.

  The arylthioether group is a group in which the oxygen atom of the ether bond of the arylether group is substituted with a sulfur atom.

  Moreover, an aryl group shows aromatic hydrocarbon groups, such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, a pyrenyl group, for example. The aryl group may be unsubstituted or substituted. 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 an atom other than carbon, such as a furanyl group, a thiophenyl group, an oxazolyl group, a pyridyl group, or a quinolinyl group, which is unsubstituted or substituted. It doesn't matter. Although carbon number of a heteroaryl group is not specifically limited, Usually, it is the range of 2-30.

  Halogen is fluorine, chlorine, bromine or iodine. The amino group and cyano group may or may not have a substituent, and examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and the like. May be substituted.

  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 fused ring formed between adjacent substituents, when described by the general formula (1), any two adjacent substituents (e.g. R ¹ and R ²⁾ selected from among R ¹ to R ¹⁰ is They are bonded to each other to form a conjugated or non-serving condensed ring. These condensed rings may contain nitrogen, oxygen, or sulfur atoms in the ring structure, or may be condensed with another ring, but the atoms constituting these condensed rings are only carbon atoms and hydrogen atoms. It is preferable because excellent heat resistance can be obtained.

  The pyrene compound represented by the general formula (1) of the present invention has a pyrene skeleton and 1 to 4 dibenzofuranyl groups in the molecule. Thereby, carrier mobility and carrier balance in the light emitting layer are improved, and the light emission efficiency of the device can be improved. Furthermore, since heat resistance can also be improved, element durability can be improved. Among them, the number of dibenzofuranyl groups is particularly preferably 2 or 3 from the standpoint of reducing crystallinity and remarkably exhibiting the effects of substituents.

Any ^{one of} R ^{1 to} R ¹⁰ and any one of R ^{11 to} R ¹⁸ are used for linking a pyrene skeleton and a dibenzofuran skeleton. From the availability of raw materials and ease of synthesis, R ¹ , It is preferable that at least one of R ³ , R ⁶ and R ⁸ is used for linking with R ^{11 to} R ¹⁸ .

Furthermore, when at least one of the substituents introduced into R ^{1 to} R ¹⁰ in the general formula (1) is an aryl group or a heteroaryl group, the thin film stability is improved, so that the light emission efficiency is high and the durability is high. It is preferable because a light emitting element excellent in the above can be obtained.

  Although it does not specifically limit as a pyrene compound represented by the said General formula (1), The following can be illustrated concretely.

  Next, the pyrene compound represented by the general formula (2) in the present invention will be described.

R ^{21 to} R ³⁰ may be the same as or different from each other, and 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, halogen, amino group, cyano group, silyl group and —P (═O) —R ³¹ R ³² , and a ring structure formed between adjacent substituents . R ³¹ and R ³² are selected from an aryl group and a heteroaryl group. However, any one of R ^{21 to} R ³⁰ is a group represented by the following general formula (3), or any one of them is a group represented by the following general formula (4). P is a phosphorus atom.

R ³³ to R ⁴¹ may be the same or different and each is a 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, aryl ether group, aryl thioether It is selected from a ring structure formed between a group, an aryl group, a heteroaryl group, a halogen, an amino group, a cyano group, a silyl group, and an adjacent substituent. B is a boron atom. X is a nitrogen atom or ^{-CR 42} = one of the. C is a carbon atom. R ⁴² represents 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, an aryl thioether group, an aryl group, a heteroaryl group, and an amino group. It is a group selected from the inside. R ⁴² may form a ring structure with R ³⁸ . Y is a group selected from an oxygen atom, a sulfur atom and —NR ⁴³ —. N is a nitrogen atom. R ⁴³ is 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 and amino group. It is a group selected from the inside. R ⁴³ may form a ring structure with R ⁴¹ . m is an integer of 1 to 4. The explanation for these substituents is the same as described above.

  The 1st aspect of the pyrene compound represented by General formula (2) in this invention has one said general formula (3) diarylboryl group which is a pyrene skeleton and an electron-accepting boron compound in a molecule | numerator. A light emitting device material containing such a pyrene compound has high luminous efficiency and excellent durability.

  When two or more diarylboryl groups represented by the general formula (3) are introduced, the heat resistance is lowered, and is easily decomposed when forming a film by, for example, vacuum deposition. Therefore, it is preferable that only one diarylboryl group represented by the general formula (3) is introduced into the pyrene skeleton in terms of both the fluorescence quantum yield and the heat resistance.

When any one of R ²² , R ²⁵ , R ²⁷ and R ³⁰ is a group represented by the general formula (3) and the substituent is bonded to the pyrene skeleton, the fluorescence quantum yield is improved. Therefore, it is preferable. Further, it is preferable that R ³³ , R ^35, and R ³⁷ are methyl groups because the area around the boron atom is three-dimensionally bulky, stable in the air, and excellent in heat resistance.

In the second aspect of the pyrene compound represented by the general formula (2) in the present invention, the benzofuran skeleton (X is —CR ⁴² ) of the above general formula (4) which is a pyrene skeleton and an electron-donating condensed aromatic in the molecule. -, when Y is an oxygen atom), benzothiophene skeleton (X is ^{-CR 42} -, when Y is a sulfur atom), indole structure (X is ^{-CR 42} -, Y is ^{-NR 43} - for), benzo An oxazole skeleton (when X is a nitrogen atom and Y is an oxygen atom), a benzothiazole skeleton (when X is a nitrogen atom and Y is a sulfur atom) or a benzimidazole skeleton (X is a nitrogen atom, Y is —NR ⁴³ —) 1 to 4 groups having a structure selected from It is preferable to have 1 to 4 groups represented by the general formula (4) because the fluorescence quantum yield and color purity of the pyrene compound are excellent. Especially, since the group represented by General formula (4) is the range of 1-2, since a fluorescence quantum yield and color purity are more excellent, it is further more preferable. A light-emitting element material containing such a pyrene compound has high light emission efficiency and excellent color purity.

When at least one of R ²² , R ²⁵ , R ²⁷ and R ³⁰ is a group represented by the general formula (4) and the substituent is bonded to the pyrene skeleton, the fluorescence quantum yield is excellent. preferable. When there are two or more groups represented by the general formula (4), it is more preferable that at least R ²² and R ²⁷ are groups represented by the general formula (4).

In the general formula (4), particularly when Y is an oxygen atom, higher luminous efficiency is obtained, and the Stokes shift is narrowed and the color purity is excellent compared to the case of sulfur atom and —NR ⁴¹ —. Therefore, it is particularly preferable. Furthermore, when X is a nitrogen atom, that is, when the general formula (4) is a benzoxazole skeleton, it is preferable because electron trapping property is imparted to the dopant material, thereby increasing the device luminous efficiency.

In any embodiment, when at least one of R ^{21 to} R ³⁰ is an alkyl group or an aryl group, concentration quenching due to interaction between pyrene compounds represented by the general formula (2) is suppressed, and high fluorescence quantum This is preferable because a yield is possible.

Further, when R ²² is a group represented by the general formula (4), R ³⁰ is an alkyl group or an aryl group, and R ²⁶ is an alkyl group, the effect of suppressing interaction between pyrene compounds is increased. High efficiency light emission is possible, which is preferable. Also, when R ²² is a group represented by the general formula (4) and R ²⁵ or R ²⁷ is an alkyl group, an aryl group or a heteroaryl group, the interaction between pyrene compounds is suppressed, and high efficiency is achieved. Since light emission is possible, it is preferable. In particular, it is preferable that R ²⁵ or R ²⁷ is an aryl group or a heteroaryl group, since strong fluorescence intensity is maintained in a solid or thin film state and high-efficiency light emission is possible. It is preferable that both R ²⁵ and R ³⁰ are an aryl group or a heteroaryl group because the effect is further enhanced.

  Although it does not specifically limit as a pyrene compound represented by the above General formula (2), The following specific examples can be given.

  In the present invention, the electron transport layer is a layer that administers electrons injected from the cathode and further transports electrons. It is desirable that the electron transport efficiency is high and the injected electrons are transported efficiently. For this purpose, it is required that the material has a high electron affinity, a high electron mobility, excellent stability, and a substance that does not easily generate trapping impurities during manufacturing and use. However, considering the transport balance between holes and electrons, if the role of effectively preventing the holes from the anode from flowing to the cathode side without recombination is mainly played, the electron transport capability is much higher. Even if it is not high, the effect of improving the luminous efficiency is equivalent to that of a material having 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 transporting material used for the electron transporting layer is not particularly limited, but is typically a compound having a condensed aryl ring such as naphthalene or anthracene or a derivative thereof, or 4,4′-bis (diphenylethenyl) biphenyl. Styryl aromatic 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, tris (8-quinolinolato) aluminum (III), etc. Hydroxy azole complexes such as quinolinol complexes and hydroxyphenyl oxazole complexes, azomethine complexes, tropolone metal complexes and flavonol metal complexes, compounds consisting of heteroaryl rings having electron-accepting nitrogen, etc. It is below.

  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, a heteroaryl ring having an electron-accepting nitrogen has a high electron affinity. Examples of the heteroaryl ring having an electron-accepting nitrogen include, for example, a pyridine ring, pyrazine ring, pyrimidine ring, quinoline ring, quinoxaline ring, naphthyridine ring, pyrimidopyrimidine ring, benzoquinoline ring, phenanthroline ring, imidazole ring, oxazole ring, Examples thereof include an oxadiazole ring, a triazole ring, a thiazole ring, a thiadiazole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring and a phenanthrimidazole ring.

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

  Examples of the compound composed of a heteroaryl ring having an electron-accepting nitrogen and composed of an element selected from the group consisting of carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus include, for example, benzimidazole derivatives and benzoxazole derivatives , Benzthiazole 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 As mentioned. 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 (2-phenyl-1,10-phenanthroline-9-yl) benzene, Benzoquinoline derivatives such as 2,2'-bis (benzo [h] quinolin-2-yl) -9,9'-spirobifluorene, 2,5-bis (6 '-(2', 2 "-bipyridyl) ) -1,1-dimethyl-3,4-diphenylsilole and other bipyridine derivatives, 1,3-bis (4 ′-(2,2 ′) 6′2 ″ -terpyridinyl)) terpyridine derivatives such as benzene and naphthyridine derivatives such as bis (1-naphthyl) -4- (1,8-naphthyridin-2-yl) phenylphosphine oxide are preferable from the viewpoint of electron transport ability. Used. 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.

  These electron transport materials may be used alone, but two or more of the above electron transport materials may be mixed and used, or one or more of the other electron transport materials may be mixed and used in the above 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 eV or less, more preferably 6 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 for the element. It is preferable from the viewpoint of characteristics.

  The thickness of the layer depends on the resistance value of the luminescent material and cannot be limited, 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 is a light-emitting element that can convert electrical energy into light. Here, the electric energy mainly indicates a direct current, but a pulse current or an alternating current can also be used. The current value and voltage value are not particularly limited, but in consideration of the power consumption and life of the element, the maximum luminance should be obtained with as low energy as possible.

  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.

  The matrix system in the present invention refers to a pixel in which pixels for display are two-dimensionally arranged such as a lattice shape or a mosaic shape, and displays characters and images 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. The line-sequential driving has an advantage that the structure is simple. However, the active matrix may be superior in consideration of the operation characteristics. Therefore, it is necessary to properly use the active matrix depending on the application.

  In the segment system (type) in the present invention, a pattern is formed so as to display predetermined information, and a predetermined region 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, and the like can be mentioned. 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, as a backlight for a liquid crystal display device, especially a personal computer for which thinning is a problem, considering that it is difficult to thin the conventional backlight because it is made of a fluorescent lamp or a light guide plate, the present invention The backlight using the light emitting element is characterized by being thin and light.

  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 above.

Example 1
Light emitting devices using Compound [29] and Compound [50] were produced as follows. A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which ITO transparent conductive film was deposited at 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semicocrine (registered trademark) 56” (manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. The cleaned substrate was subjected to UV-ozone treatment for 1 hour, then placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ 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, compound [29] as a host material and compound [50] as a dopant material were co-evaporated to a thickness of 35 nm so as to have a doping concentration of 1 wt% to form a light emitting layer. Next, as an electron transport material, E-1 shown below was laminated to a thickness of 35 nm. Next, lithium fluoride was deposited to a thickness of 0.5 nm, and then aluminum was deposited to a thickness of 1000 nm to prepare a device having a 5 × 5 mm square light emitting region. The film thickness referred to here is a crystal oscillation type film thickness monitor display value. From this light-emitting element, high-efficiency blue light emission with a light emission efficiency (external quantum efficiency) of 5.0% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 850 hours.

Example 2
A light emitting device was produced in the same manner as in Example 1 except that the compound [129] was used as the dopant material. From this light-emitting element, high-efficiency blue light emission with a light emission efficiency (external quantum efficiency) of 4.8% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 850 hours.

Example 3
A light emitting device was produced in the same manner as in Example 1 except that the compound [325] was used as the dopant material. From this light-emitting element, high-efficiency blue light emission with a light emission efficiency (external quantum efficiency) of 5.1% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 1200 hours.

Example 4
A light emitting device was produced in the same manner as in Example 1 except that the compound [240] was used as the dopant material. From this light-emitting element, high-efficiency blue light emission with a luminous efficiency (external quantum efficiency) of 4.2% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 700 hours.

Example 5
A light emitting device was produced in the same manner as in Example 1 except that the compound [155] was used as the dopant material. From this light-emitting element, high-efficiency blue light emission with a luminous efficiency (external quantum efficiency) of 4.0% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 650 hours.

Example 6
A light emitting device was produced in the same manner as in Example 1 except that the compound [229] was used as the dopant material. From this light-emitting element, high-efficiency blue light emission with a luminous efficiency (external quantum efficiency) of 4.2% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 750 hours.

Example 7
A light emitting device was produced in the same manner as in Example 1 except that the compound [31] was used as the host material. From this light-emitting element, high-efficiency blue light emission with a light emission efficiency (external quantum efficiency) of 5.5% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 1,500 hours.

Example 8
A light emitting device was produced in the same manner as in Example 1 except that the compound [32] was used as the host material. From this light-emitting element, high-efficiency blue light emission with a light emission efficiency (external quantum efficiency) of 5.6% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 2,000 hours.

Example 9
A light emitting device was produced in the same manner as in Example 1 except that the compound [36] was used as the host material. From this light-emitting element, high-efficiency blue light emission with a light emission efficiency (external quantum efficiency) of 5.2% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 1,100 hours.

Example 10
A light emitting device was produced in the same manner as in Example 1 except that the compound [30] was used as the host material. From this light-emitting element, high-efficiency blue light emission with a light emission efficiency (external quantum efficiency) of 4.5% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 950 hours.

Comparative Example 1
A light emitting device was produced in the same manner as in Example 1 except that the compound D-1 shown below was used as the dopant material. From this light emitting element, blue light emission with a light emission efficiency (external quantum efficiency) of 2.0% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 150 hours.

Comparative Example 2
A light emitting device was produced in the same manner as in Example 1 except that the compound D-2 shown below was used as the dopant material. From this light emitting element, blue light emission with a light emission efficiency (external quantum efficiency) of 2.5% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 300 hours.

Comparative Example 3
A light emitting device was produced in the same manner as in Example 1 except that the compound H-1 shown below was used as the host material. From this light-emitting element, blue light emission with a light emission efficiency (external quantum efficiency) of 3.0% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 300 hours.

Comparative Example 4
A light emitting device was produced in the same manner as in Example 1 except that the compound H-2 shown below was used as the host material. From this light-emitting element, blue light emission with a light emission efficiency (external quantum efficiency) of 3.0% was obtained. When this light emitting device was DC-driven at 40 mA / cm ² , the luminance half time was 300 hours.

Claims (7)

An element that has at least a light emitting layer between an anode and a cathode and emits light by electric energy, and the element is represented by at least a pyrene compound represented by the general formula (1) and the general formula (2). A light-emitting element containing a pyrene compound.

(R ^{1 to} R ¹⁸ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, an aryl group, selected from the cyclic structure formed between the heteroaryl group, halogen, an amino group, a cyano group, a silyl group, and ^{-P (= O) -R 19 R} 20, and adjacent substituents R ¹⁹ and R ²⁰ are selected from an aryl group and a heteroaryl group, n is an integer of 1 to 4. Any one of R ^{1 to} R ¹⁰ and any of R ^{11 to} R ¹⁸ One is used for a single bond.

(R ^{21 to} R ³⁰ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl Selected from ring structures formed between thioether groups, aryl groups, heteroaryl groups, halogens, amino groups, cyano groups, silyl groups and —P (═O) —R ³¹ R ³² , and adjacent substituents R ³¹ and R ³² are selected from an aryl group and a heteroaryl group, provided that any one of R ^{21 to} R ³⁰ is a group represented by the following general formula (3), or Any one to four are groups represented by the following general formula (4). P is a phosphorus atom.)

(R ^{33 to} R ⁴¹ may be the same as or different from each other, and may be hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl. A ring structure formed between a thioether group, an aryl group, a heteroaryl group, a halogen, an amino group, a cyano group, a silyl group, and an adjacent substituent, B is a boron atom, and X is Either a nitrogen atom or -CR ⁴² =, C is a carbon atom, R ⁴² is 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 and amino group From a group selected .R ⁴² MAY form R ³⁸ and ring structure .Y represents an oxygen atom, a sulfur atom and -NR 43 ^- In .N is a group selected from among a nitrogen atom R ⁴³ is 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 and amino is a group selected from among groups .R ⁴³ mAY form R ⁴¹ and ring structure .m is an integer from 1 4.) ^{R 1, R 3, R 6} , R 8 of any of n and any one light emitting device according to claim 1, wherein used for connecting the pyrene skeleton and the dibenzofuran skeleton of ^R 11 ^{to R 19. R 22, R 25, R 27} , light emitting device according to claim 1 or 2, wherein any one of ^{R 30} is represented by the general formula (3). R ^<33> , R ^<35> and R ^<37> are methyl groups, The light emitting element in any one of Claims 1-3. Light emitting device according to claim 1 or 2, wherein R ²² is represented by the general formula (4). The light-emitting device according to claim 1, wherein Y is an oxygen atom. The light emitting layer includes a host material and a dopant material, the pyrene compound represented by the general formula (1) is a host material, and the pyrene compound represented by the general formula (2) is a dopant material. 6. The light emitting device according to any one of 6.