KR102044720B1 - Light emitting element - Google Patents

Abstract

Provided is a light emitting device that achieves high light emission efficiency and durability.
The light emitting device of the present invention comprises at least a hole transporting layer and a light emitting layer between the anode and the cathode, the light emitting device emitting light by electric energy, the hole transporting layer comprises a compound having a specific carbazole skeleton, the light emitting layer is an electron It is characterized by containing the compound which has an aromatic heterocyclic group containing water-soluble nitrogen.

Description

Light emitting element {LIGHT EMITTING ELEMENT}

The present invention relates to a light emitting device capable of converting electrical energy into light. More specifically, the present invention relates to light emitting devices usable in fields such as display devices, flat panel displays, backlights, lighting, interiors, signs, signs, electrophotographic cameras and optical signal generators.

Recently, studies have been actively conducted on organic thin film light emitting devices in which electrons injected from the cathode and holes injected from the anode emit light upon recombination in the organic phosphor sandwiched between the anodes. This light emitting device is characterized by high brightness and ultra-luminescent light emission under low driving voltage and multicolor light emission by selecting a fluorescent material.

Since this research has shown that organic thin film elements emit light with high luminance by Kodak Tang et al., A number of practical studies have been conducted, and organic thin film light emitting elements have been steadily put into practical use, such as being employed in main displays of mobile phones. . However, there are still many technical problems, and among them, both high efficiency and long life of the device are one of the major problems.

The drive voltage of the device is largely dependent on the carrier transport material for transporting carriers such as holes and electrons to the light emitting layer. Among these, the material which has a carbazole skeleton as a material which transports a hole (hole transport material) is known (for example, refer patent document 1-2).

Moreover, since the material which has the said carbazole skeleton has a high triplet level, it is known as a host material of a light emitting layer (for example, refer patent document 3). Moreover, the organic electroluminescent element which contains an indolocarbazole derivative as a host material with a phosphorescence dopant is disclosed (for example, refer patent document 4).

Japanese Patent Laid-Open No. 8-3547 Korean Patent Application Publication No. 2010-0079458 Japanese Patent Publication No. 2003-133075 International Publication No. 2008/056746

However, in the prior art, it was difficult to sufficiently lower the drive voltage of the device. Further, even if the driving voltage of the device could be lowered, the light emission efficiency and the endurance life of the device were insufficient. As such, a technique for achieving high luminous efficiency and durable lifetime has not yet been found.

An object of the present invention is to provide an organic thin film light emitting device that solves the problems of the prior art and improves luminous efficiency and durability.

In order to solve the above problems and achieve the object, the light emitting device of the present invention is a light emitting device that has at least a hole transport layer and a light emitting layer between the anode and the cathode, and emits light by electric energy, the hole transport layer is a general formula ( It contains the compound represented by 1), The said light emitting layer is a compound which has an aromatic heterocyclic group containing an electron accepting nitrogen, and contains the compound represented by either of following General formula (2)-General formula (4). It features.

[In general formula (1), R <^1> -R <^4> may be same or different, respectively, 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, arylthioether group, aryl group, heteroaryl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, silyl group, -P (= O) R ⁵ R ⁶ . R ⁵ and R ⁶ are aryl groups or heteroaryl groups. L is a single bond or a divalent linking group.]

[In general formula (2)-general formula (4), R <^7> -R <^11> and R <^21> -R <^27> may be same or different, respectively, and hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, and a cycloalke Or an alkyl group, alkynyl group, alkoxy group, alkylthio group, arylether group, arylthioether group, aryl group, heteroaryl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group or silyl group. Ring A or Ring B represents a benzene ring having a substituent or no substituent condensing with an adjacent ring at any position. Y ¹ to Y ³ are —N (R ²⁸ ) —, —C (R ²⁹ R ³⁰ ) —, an oxygen atom, or a sulfur atom. R <^28> -R <^30> may be same or different, respectively, and is an alkyl group, an aryl group, or heteroaryl group. R ²¹ to R ³⁰ may form a ring with adjacent substituents. L ¹¹ to L ¹⁷ are a single bond or an arylene group. X ¹ to X ⁵ represent a carbon atom or a nitrogen atom, and when X ¹ to X ⁵ are a nitrogen atom, R ⁷ to R ^{11, which} are substituents on the nitrogen atom, do not exist. Provided that the number of nitrogen atoms in X ¹ to X ⁵ is 1 or 2.]

(Effects of the Invention)

According to the present invention, it is possible to provide an organic electroluminescent device having a high luminous efficiency and also having a sufficient durability life.

The present invention is a light emitting device having at least a hole transporting layer and a light emitting layer between an anode and a cathode and emitting light by electric energy, the hole transporting layer comprising a compound represented by the following general formula (1), wherein the light emitting layer is an electron A light emitting device comprising a compound having an aromatic heterocyclic group containing water-soluble nitrogen.

The compound having an aromatic heterocyclic group containing an electron-accepting nitrogen, which is used in the present invention, has a high electron injection transport ability, so that it can be used as a light emitting layer to provide an organic thin film light emitting device having high light emission efficiency and low driving voltage. However, since the light emitting layer has a very high electron injection transport ability, depending on the type of hole transporting layer used in combination, the recombination region in the light emitting layer is localized to the hole transporting layer, and triplet energy and electrons leak into the hole transporting layer. This may cause deterioration in luminous efficiency of the device and deterioration in durability.

On the other hand, the present inventors have found that the use of the compound represented by the general formula (1) as a hole transporting layer enables significant improvement in high luminous efficiency and durability. That is, the compound represented by the general formula (1) has high electron blocking property and high triplet energy, and even if the recombination region in the light emitting layer is localized on the hole transport layer side, the triplet energy and electrons can be trapped in the light emitting layer, resulting in high efficiency. And long life.

That is, the use of the compound represented by the general formula (1) in the hole transport layer and the use of the compound having an aromatic heterocyclic group containing electron-accepting nitrogen in the light emitting layer are a preferable combination in achieving both high light emission efficiency and durability.

The compound represented by General formula (1) in this invention is demonstrated in detail.

In General Formula (1), R <^1> -R <^4> may be same or different, respectively, 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, and an aryl ether Group, arylthioether group, aryl group, heteroaryl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, silyl group, -P (= O) R ⁵ R ⁶ . R ⁵ and R ⁶ are aryl groups or heteroaryl groups. L is a single bond or a divalent linking group.

Deuterium may be sufficient as hydrogen among these substituents.

In the compound represented by the general formula (1), an alkyl group is, for example, a saturated aliphatic hydrocarbon group such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group or tert-butyl group. It may or may not have a substituent. There is no restriction | limiting in particular in the further substituent at the time of substitution, For example, an alkyl group, an aryl group, heteroaryl group, etc. are mentioned, This point is common to the following description. Moreover, although carbon number of an alkyl group is not specifically limited, It is the range of 1 or more and 20 or less normally, More preferably, it is 1 or more and 8 or less from the point of the availability and cost.

In the compound represented by General formula (1), a cycloalkyl group shows saturated alicyclic hydrocarbon groups, such as cyclopropyl, cyclohexyl, norbornyl, and adamantyl, for example, and 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.

In the compound represented by the general formula (1), the heterocyclic group represents, for example, an aliphatic ring having an atom 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. You don't have to. Although carbon number of a heterocyclic group is not specifically limited, Usually, it is the range of 2-20.

In the compound represented by General formula (1), an alkenyl group represents the unsaturated aliphatic hydrocarbon group containing double bonds, such as a vinyl group, an allyl group, butadienyl group, for example, and it 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.

In the compound represented by the general formula (1), the cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond such as a cyclopentenyl group, a cyclopentadienyl group, a cyclohexenyl group, for example, and has a substituent You may or may not have it. Although carbon number of a cycloalkenyl group is not specifically limited, Usually, it is the range of 2-20.

In the compound represented by General formula (1), an alkynyl group represents the unsaturated aliphatic hydrocarbon group containing triple bonds, such as an ethynyl group, for example, and it 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.

In the compound represented by General formula (1), an alkoxy group shows the functional group which the aliphatic hydrocarbon group couple | bonded through ether bonds, such as a methoxy group, an ethoxy group, a propoxy group, for example, and this aliphatic hydrocarbon group may have a substituent You do not have to. Although carbon number of an alkoxy group is not specifically limited, Usually, it is the range of 1-20.

In the compound represented by the general formula (1), the alkylthio group is one 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.

In the compound represented by General formula (1), an arylether group represents the functional group which the aromatic hydrocarbon group couple | bonded with ether bonds, such as phenoxy group, for example, and the aromatic hydrocarbon group may have a substituent or does not need to have it. Although carbon number of an arylether group is not specifically limited, Usually, it is the range of 6-40.

In the compound represented by the general formula (1), the arylthioether group is one in which the oxygen atom of the ether bond of the arylether group is substituted with a sulfur atom. The aromatic hydrocarbon group in the arylether group may or may not have a substituent. Although carbon number of an arylether group is not specifically limited, Usually, it is the range of 6-40.

In the compound represented by General formula (1), an aryl group is aromatic, such as a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, a phenanthryl group, anthracenyl group, a triphenylenyl group, a terphenyl group, a pyrenyl group, for example. Hydrocarbon group is represented. The aryl group may or may not have a substituent. Although carbon number of an aryl group is not specifically limited, Usually, it is the range of 6-40.

In the compound represented by the general formula (1), the heteroaryl group is a flanyl group, a thiophenyl group, a pyridyl group, a pyrimidyl group, a triazyl group, a quinolinyl group, a pyrazinyl group, a naphthyridyl group, a benzofuranyl group, a benzothiophenyl group And cyclic aromatic group which has atoms other than carbon, such as an indolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a carbazolyl group, in one or more rings, and this may be unsubstituted or substituted. Although carbon number of a heteroaryl group is not specifically limited, Usually, it is the range of 2-30.

In the compound represented by the general formula (1), halogen represents fluorine, chlorine, bromine or iodine.

In the compound represented by the general formula (1), the carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group may or may not have a substituent, and examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, and the like. And these substituents may be further substituted.

In the compound represented by General formula (1), the amino group may or may not have a substituent, for example, an aryl group, a heteroaryl group, etc. are mentioned, These substituents may further be substituted.

In the compound represented by General formula (1), a silyl group shows the functional group which has a bond to silicon atoms, such as a trimethylsilyl group, for example, and it 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. In addition, silicon number is the range of 1-6 normally.

In the compound represented by the formula (1), L is a single bond or a divalent linking group, and examples of the divalent linking group include a phenylene group, a naphthylene group, a biphenylene group, a fluorenylene group, a phenanthrene group and a terminator. Arylene groups such as phenylene group, anthracenylene group and pyrenylene group, furanylene group, thiophenylene group, pyridylene group, quinolinyl group, isoquinolinyl group, pyrazinylene group, pyrimidylene group, naphthyridylene group, Heteroarylene groups, such as a benzofuranylene group, a benzothiophenylene group, an indoleylene group, a dibenzofuranylene group, a dibenzothiophenylene group, and a carbazolene group, are illustrated. These may or may not have a substituent.

Moreover, the light emitting element of this invention is a compound in which a light emitting layer has an aromatic heterocyclic group containing electron accepting nitrogen, and contains the compound represented by either of following General formula (2)-General formula (4). When the light emitting layer contains a compound represented by any one of the following general formulas (2) to (4) which is a compound having an aromatic heterocyclic group containing an electron-accepting nitrogen, the light emitting efficiency is improved because of its high electron injection transport properties. Moreover, since it can lead to the improvement of durability since a stable thin film can be formed, it is preferable.

The compound which has an aromatic heterocyclic group containing electron-accepting nitrogen in this invention is demonstrated in detail.

The electron-accepting nitrogen here refers to a nitrogen atom which forms a multiple bond with adjacent atoms. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron accepting property. Therefore, the aromatic heterocycle containing electron accepting nitrogen has high electron affinity. Since the compound of the present invention having electron-accepting nitrogen exhibits high electron injection transportability, the probability of recombination is increased, so that the luminous efficiency is improved.

Aromatic heterocyclic group containing an electron-accepting nitrogen means pyridyl group, quinolinyl group, isoquinolinyl group, quinoxanyl group, pyrazinyl group, pyrimidyl group, pyridazinyl group, phenanthrolinyl group, imidazopyridyl group, and acuri At least one electron-accepting nitrogen atom as an atom other than carbon in the heteroaryl group, such as a diyl group, a benzoimidazolyl group, a benzooxazolyl group, a benzothiazolyl group, a bipyridyl group, and a terpyridyl group, in one or a plurality of rings The aromatic heterocyclic group which has is shown. In the compound having an aromatic heterocyclic group containing an electron-accepting nitrogen used in the present invention, the number of electron-accepting nitrogens contained in the aromatic heterocycle of 1 is 1 or 2. However, when the compound which has an aromatic heterocyclic group containing an electron-accepting nitrogen has two or more aromatic heterocycles containing an electron-accepting nitrogen, you may have three or more electron-accepting nitrogen. In addition, the aromatic heterocyclic group containing electron-accepting nitrogen may have an alkyl group or a cycloalkyl group as a substituent.

In general, it is preferable that the difference between the decomposition temperature and the sublimation temperature is larger in order to deposit the organic material at a high temperature for a long time. In a compound having an aromatic heterocyclic group containing an electron-accepting nitrogen, when the number of the electron-accepting nitrogens contained in the aromatic heterocycle of 1 is 3 or more, the heat load applied to the compound itself becomes large, if the deposition is required at a high temperature. There is a possibility of being deposited by pyrolysis. Incorporation of such decomposition products may greatly affect device characteristics, particularly lifespan. In order to prevent the concern, the number of the electron-accepting nitrogens contained in the aromatic heterocycle of 1 is preferably 2 or less.

If the compound having an aromatic heterocyclic group containing an electron-accepting nitrogen is a monoazine compound or diazine compound in which the number of electron-accepting nitrogens contained in the aromatic heterocycle of 1 is 2 or less, reception of electrons from the electron transporting layer is facilitated, and Since electron injection property becomes high, the recombination probability becomes high and light emission efficiency improves, and it is preferable.

If the compound which has an aromatic heterocyclic group containing electron accepting nitrogen is a compound represented by following General formula (2)-(4), since high electron injection transport property is shown, luminous efficiency will improve. Moreover, since it can lead to the improvement of durability since a stable thin film can be formed, it is preferable.

In general formula (2)-general formula (4), R <^7> -R <^11> and R <^21> -R <^27> may be same or different, respectively, and a single bond, hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, Cycloalkenyl, alkynyl, alkoxy, alkylthio, arylether, arylthioether, aryl, heteroaryl, halogen, carbonyl, carboxyl, oxycarbonyl, carbamoyl, amino, or silyl groups. In addition, R ⁷ to R ¹¹ may form a ring with adjacent substituents. Ring A or Ring B represents a benzene ring having a substituent or no substituent condensing with an adjacent ring at any position. Y ¹ to Y ³ are —N (R ²⁸ ) —, —C (R ²⁹ R ³⁰ ) —, an oxygen atom, or a sulfur atom. R <^28> -R <^30> may be same or different, respectively, and is an alkyl group, an aryl group, or heteroaryl group. R ²¹ to R ³⁰ may form a ring with adjacent substituents. L ¹¹ to L ¹⁷ are a single bond or an arylene group. X ¹ to X ⁵ represent a carbon atom or a nitrogen atom, and when X ¹ to X ⁵ are a nitrogen atom, R ⁷ to R ^{11, which} are substituents on the nitrogen atom, do not exist. Provided that the number of nitrogen atoms in X ¹ to X ⁵ is 1 or 2.

In the general formulas (2) to (4), the arylene group of L ¹¹ to L ¹⁷ refers to a divalent group produced by removing one hydrogen atom from each of two ring carbon atoms of an aromatic compound (arene), For example, a phenylene group, a naphthylene group, a biphenylene group, a fluorenylene group, a phenanthryl group, a terphenylene group, anthracenylene group, a pyrenylene group, etc. are illustrated. These may or may not have a substituent.

The description of the other substituent is the same as that of the compound represented by General formula (1).

In the general formulas (2) to (4), the number of nitrogen atoms in X ¹ to X ⁵ is 1 or 2, and two adjacent ones of X ¹ to X ⁵ do not become nitrogen atoms at the same time. Since two adjacent X ¹ to X ⁵ do not become nitrogen atoms at the same time, thermally weak nitrogen-nitrogen double bonds are eliminated, and the thermal stability of the entire molecule is improved. Also, X ¹ to X ⁵ Since the number of nitrogen atoms in 1 is 1 or 2, electrons are easily received from the electron transporting layer, and the electron injectability into the light emitting layer is increased, so that the probability of recombination is increased and the luminous efficiency is improved.

Especially, it is more preferable that X <^1> and X <^5> , X <^3> and X <^5> , or X <^1> and X <^3> are nitrogen atoms from the viewpoint of thermal stability and electron injection / transportation compatibility.

Moreover, it is preferable that at least 2 of R <^7> -R <^11> is an aryl group. Since at least two of R ⁷ to R ¹¹ are aryl groups, the planar height of the ring structure composed of X ¹ to X ⁵ and carbon atoms can be suppressed and stacking can be suppressed, thereby forming a stable thin film and efficiently saving energy to the dopant. It is possible to provide high efficiency light emission.

Among them, from the ease of synthesis, at least two of R ⁷ to R ¹¹ are a phenyl group having no substituent, a phenyl group having an alkyl group as a substituent, a phenyl group having a halogen as a substituent, or a phenyl group having a phenyl group as a substituent to form a stable thin film. It is preferable because it can.

Since the indolocarbazole skeleton has a high triplet level, the compound having an indolocarbazole skeleton represented by the general formulas (2) to (4) can also maintain a high triplet level and is easy Since deactivation can be suppressed, high luminous efficiency is achieved.

Especially, the compound whose L <^11> -L <^17> is a single bond and R <^21> -R <^26> is hydrogen is preferable from the ease of synthesis | combination.

In addition, R ²⁷ is preferably an aryl group from the ease of synthesis. Especially, since R ²⁷ can form a stable thin film because it is a phenyl group, it is preferable.

As a compound having an aromatic heterocyclic group containing an electron-accepting nitrogen, International Publication No. 2011/148909, International Publication No. 2011/132683, International Publication No. 2011/132684, International Publication No. 2008/056746, and International Publication No. 2009/084546 Pamphlet, Publication No. 2010/136109 Pamphlet, Publication No. 2011/019156, Publication No. 2011/139055 Pamphlet, Publication No. 2011/055934 Pamphlet, Korean Patent Publication No. 2011- Although the compound of Unexamined-Japanese-Patent No. 120075, international publication 2011/136755 pamphlet, international publication 2011/136520 pamphlet, international publication 2011/132865 pamphlet, international publication 2012/023947 pamphlet is mentioned, The following compounds are mentioned.

It is preferable that carbazoles are connected to the compound represented by General formula (1) as shown by following General formula (5) from a viewpoint of the ease of synthesis and hole transport property.

Moreover, it is preferable that it is an asymmetric carbazole dimer from a viewpoint of the durability improvement of a light emitting element. This is because in the symmetrical structure, the crystallinity is high and the stability of the thin film is insufficient and the durability of the device is reduced.

In addition, in view of heat resistance, R ¹ in General Formula (1), R ² is more preferably an aryl group having a substituent or no substituent.

As a compound represented by such general formula (1), International Publication 2011/122132, International Publication 2011/125680, International Publication 2011/48821, International Publication 2011/48822, International Publication 2011/24451 Although the compound which has the carbazole skeleton of Unexamined-Japanese-Patent No. 2012/1986 and Korea Patent Publication No. 2010-79458 is mentioned, Specifically, the following compounds are mentioned.

The compound represented by General formula (1) can be manufactured by a well-known method. That is, although it can synthesize | combine easily by the Suzuki coupling reaction of the bromomer of carbazole substituted by 9-position, and the monoboronic acid of carbazole substituted by 9-position, a manufacturing method is not limited to this.

Next, embodiment of the light emitting element of this invention is described in detail. The light emitting device of the present invention has an anode and a cathode, and a hole transport layer and a light emitting layer interposed between the anode and the cathode, and the light emitting layer emits light by electrical energy.

The layer structure between the anode and the cathode in such a light emitting element is, in addition to the structure consisting of a hole transporting layer and a light emitting layer,

1) hole transport layer / light emitting layer / electron transport layer

2) hole injection layer / hole transport layer / light emitting layer / electron transport layer

3) hole transport layer / light emitting layer / electron transport layer / electron injection layer

4) Hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer

The laminated structure like this is mentioned. Each of the above layers may be either a single layer or a plurality of layers, or may be doped.

In the light emitting device of the present invention, the anode and the cathode have a role for supplying sufficient current for light emission of the device, and at least one of the anode and the cathode is preferably transparent or translucent in order to extract light. Usually, the anode formed on a board | substrate is made into a transparent electrode.

In the light emitting device of the present invention, the material used for the anode is a material capable of efficiently injecting holes into the organic layer, and zinc oxide, tin oxide, indium oxide, indium oxide (ITO) as long as it is transparent or translucent to extract light. ), Conductive metal oxides such as zinc indium oxide (IZO), metals such as gold, silver, and chromium, inorganic conductive materials such as copper iodide and copper sulfide, and conductive polymers such as polythiophene, polypyrrole, and polyaniline. Although it is not, it is especially preferable to use ITO glass or nesa glass. These electrode materials may be used alone, or a plurality of materials may be laminated or mixed. The resistance of the transparent electrode is not limited as long as it can supply a sufficient current for light emission of the device, but is preferably low resistance from the viewpoint of power consumption of the device. For example, an ITO substrate of 300 Ω / square or less functions as an element electrode, but since it is possible to supply a substrate of about 10 Ω / square, it is particularly preferable to use a substrate having a low resistance of 20 Ω / square or less. Although the thickness of ITO can be arbitrarily selected according to a resistance value, it is usually used between 50-300 nm.

Moreover, in order to maintain the mechanical strength of a light emitting element, it is preferable to form a light emitting element on a board | substrate. As a board | substrate, glass substrates, such as a soda glass and an alkali free glass, are used suitably. Since the thickness of a glass substrate should just be enough thickness to maintain mechanical strength, 0.5 mm or more is enough. As for the material of glass, since it is better to have less elution ion from glass, it is more preferable that it is an alkali free glass. Alternatively, soda subjected to barrier coating such as SiO ₂ also lime glass because it is commercially available may be used. In addition, if a 1st electrode functions stably, a board | substrate does not need to be glass, For example, you may form an anode on a plastic substrate. The method for forming an ITO film is not particularly limited such as electron beam beam method, sputtering method and chemical reaction method.

In the light emitting device of the present invention, the material used for the cathode is not particularly limited as long as it is a substance capable of injecting electrons into the light emitting layer efficiently. Generally, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys of these metals and low work function metals such as lithium, sodium, potassium, calcium and magnesium, and multilayer lamination are preferable. Among them, aluminum, silver and magnesium are preferred as main components in terms of electrical resistance value, ease of film formation, film stability, luminous efficiency and the like. In particular, it is preferable to comprise magnesium and silver because electron injection into the electron transport layer and the electron injection layer in the present invention can be facilitated and low voltage driving can be performed.

In addition, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, inorganic materials such as silica, titania and silicon nitride, polyvinyl alcohol, polyvinyl chloride and hydrocarbons for protecting the cathode Laminating | stacking organic high molecular compounds, such as a high molecular compound, on a negative electrode as a protective film layer is mentioned as a preferable example. However, in the case of the element structure (top emission structure) which extracts light from a cathode side, a protective film layer is selected from the material which has light transmittance in visible region. The manufacturing method of these electrodes is not specifically limited, such as resistance heating, an electron beam beam, sputtering, ion plating, and a coating.

In the light emitting device of the present invention, the hole injection layer is a layer inserted between the anode and the hole transport layer. One hole injection layer may be sufficient, a some layer may be laminated | stacked, or any may be sufficient as it. The presence of the hole injection layer between the hole transport layer and the anode is preferable because it not only drives lower voltage, improves the endurance life, but also improves the carrier balance of the device to improve the luminous efficiency.

Although the material used for a hole injection layer is not specifically limited, For example, 4,4'-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl (TPD) and 4,4'-bis (N -(1-naphthyl) -N-phenylamino) biphenyl (NPD), 4,4'-bis (N, N-bis (4-biphenylyl) amino) biphenyl (TBDB), bis (N, Benzidine derivatives such as N'-diphenyl-4-aminophenyl) -N, N-diphenyl-4,4'-diamino-1,1'-biphenyl (TPD232), 4,4 ', 4' ' -Tris (3-methylphenyl (phenyl) amino) triphenylamine (m-MTDATA), 4,4 ', 4' '-tris (1-naphthyl (phenyl) amino) triphenylamine (1-TNATA) A group of materials called starburst arylamine, biscarbazole derivatives such as bis (N-arylcarbazole) or bis (N-alkylcarbazole), pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives, Heterocyclic compounds such as thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives, and the like Polycarbonate, styrene derivative, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, polysilane and the like having a side chain thereof. Compounds represented by the general formula (1) or (5) can also be used in the hole injection layer in the same manner, and among them, those having a shallow HOMO level are more preferable from the viewpoint of smoothly injecting and transporting holes from the anode to the hole transport layer. Used.

These materials may be used independently, or may mix and use 2 or more types of materials. Alternatively, a plurality of materials may be laminated to form a hole injection layer. It is more preferable that the hole injection layer is composed of the acceptor material alone, or that the above-described effect is more remarkably obtained when the acceptor material is doped into the above-described hole injection material. The acceptor material is a material for forming a charge transfer complex and a material constituting a hole transporting layer in contact with a single layer film, and a material constituting a hole injecting layer in a dope-using manner. The use of such a material improves the conductivity of the hole injection layer, contributing to lowering of the driving voltage of the device, and achieving effects such as improvement in luminous efficiency and durability improvement.

Examples of acceptor materials include iron (III) chloride, aluminum chloride, gallium chloride, indium chloride, metal chlorides such as antimony chloride, metal oxides such as molybdenum oxide, vanadium oxide, tungsten oxide, ruthenium oxide, tris (4-bromo And a charge transfer complex such as phenyl) aluminum hexachloro antimonate (TBPAH). Moreover, the organic compound which has a nitro group, a cyano group, a halogen, or a trifluoromethyl group in a molecule | numerator, a quinone type compound, an acid anhydride type compound, fullerene, etc. are also used suitably. Specific examples of these compounds include hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane (TCNQ), tetrafluorotetracyanoquinodimethane (F4-TCNQ), and radiene derivatives, p -Fluoranyl, p-chloranyl, p-bromanyl, p-benzoquinone, 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone, tetramethylbenzoquinone, 1,2,4,5- Tetracyanobenzene, o-dicyanobenzene, p-dicyanobenzene, 1,4-dicyanotetrafluorobenzene, 2,3-dichloro-5,6-dicyanobenzoquinone, p-dinitrobenzene, m -Dinitrobenzene, o-dinitrobenzene, p-cyanonitrobenzene, m-cyanonitrobenzene, o-cyanonitrobenzene, 1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1 -Nitronaphthalene, 2-nitronaphthalene, 1,3-dinitronaphthalene, 1,5-dinitronaphthalene, 9-cyanoanthracene, 9-nitroanthracene, 9,10-anthraquinone, 1,3,6,8 Tetranitroca Carbazole, 2,4,7- trinitro-9-fluorenone, 2,3,5,6-dicyano pyridine, maleic anhydride, phthalic anhydride, and the like C60, and C70.

Among these, since a metal oxide and a cyano group containing compound are easy to handle, and also easy to deposit, since the above-mentioned effect is acquired easily, it is preferable. In either case where the hole injection layer is composed of the acceptor material alone, or when the acceptor material is doped in the hole injection layer, the hole injection layer may be one layer or a plurality of layers may be laminated. do.

Although an acceptor material is not specifically limited, It is preferable to use in 0.1-50 mass parts with respect to the compound represented by General formula (1) or (5), More preferably, it is 0.5-20 mass parts. .

In the light emitting device of the present invention, the hole transport layer is a layer for transporting holes injected from the anode to the light emitting layer. The compound represented by the general formula (1) or (5) is suitably used for the hole transport layer of the light emitting device because it has a high triplet level, high hole transport characteristics and thin film stability. The hole transport layer may be a single layer, or may be configured by stacking a plurality of layers, or may be either.

In the case of a plurality of hole transport layers, the hole transport layer containing the compound represented by the general formula (1) or (5) is preferably in direct contact with the light emitting layer. It is because the compound represented by General formula (1) or (5) has high electron blocking property, and can prevent the invasion of the electron which flows out from a light emitting layer. Moreover, since the compound represented by General formula (1) or General formula (5) has a high triplet level, it also has the effect of trapping the excitation energy of triplet luminescent material. Therefore, even when the triplet light emitting material is contained in the light emitting layer, the hole transport layer containing the compound represented by the general formula (1) or (5) is preferably in direct contact with the light emitting layer.

The hole transport layer may be composed only of a compound represented by the general formula (1) or (5), or other materials may be mixed in a range that does not impair the effects of the present invention. In this case, although the same material group as the material used for the said hole injection layer can be mentioned as a preferable example, when using for a hole transport layer, the material of HOMO level equivalent to or deeper than the material used for a hole injection layer is used. It is more preferable to choose. In this case, as other materials used, for example, 4,4'-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl (TPD), 4,4'-bis (N- (1-naph) Tyl) -N-phenylamino) biphenyl (NPD), 4,4'-bis (N, N-bis (4-biphenylyl) amino) biphenyl (TBDB), bis (N, N'-diphenyl Benzidine derivatives such as 4-aminophenyl) -N, N-diphenyl-4,4'-diamino-1,1'-biphenyl (TPD232), 4,4 ', 4' '-tris (3- Starburst arylamines such as methylphenyl (phenyl) amino) triphenylamine (m-MTDATA), 4,4 ', 4' '-tris (1-naphthyl (phenyl) amino) triphenylamine (1-TNATA) Biscarbazole derivatives such as bis (N-arylcarbazole) or bis (N-alkylcarbazole), pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxa Heterocyclic compounds, such as a diazole derivative, a phthalocyanine derivative, and a porphyrin derivative, and a polymer which has the said monomer in a side chain in a polymer system Licarbonate, styrene derivatives, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, polysilane, etc. are mentioned.

In the light emitting device of the present invention, the light emitting layer may be either a single layer or a plurality of layers. When there are multiple light emitting layers, each light emitting layer is formed by a light emitting material (host material, a dopant material), and each light emitting layer may be a mixture of a host material and a dopant material, may be a host material alone, two types of host materials, and one type. A mixture of dopant materials may be used, or any may be used. That is, in the light emitting device of the present invention, only the host material or the dopant material may emit light in each light emitting layer, and the host material and the dopant material may emit light together. It is preferable that a light emitting layer consists of a mixture of a host material and a dopant material from a viewpoint of obtaining high color purity light emission by using electrical energy efficiently. In addition, one type of host material and dopant material may respectively be sufficient, and a plurality of combinations may be sufficient, and any may be sufficient as it. The dopant material may be contained in the whole host material, may be included partially, and any may be sufficient as it. The dopant material may be laminated, may be dispersed, or any of them. The dopant material can control the emission color. If the amount of the dopant material is too large, concentration quenching occurs, so it is preferably used at 30% by mass or less with respect to the host material, more preferably 20% by mass or less. Although the doping method can be formed by the co-deposition method with a host material, you may vapor-deposit simultaneously after mixing previously with a host material.

Compounds having an aromatic heterocyclic group containing an electron-accepting nitrogen have high electron transport properties and thin film stability, and thus are suitably used for the light emitting layer of the light emitting device. Moreover, since the compound which has the aromatic heterocyclic group containing electron accepting nitrogen has high electron transport property and thin film stability, it is preferable to use for a host material.

Moreover, since the compound which has an aromatic heterocyclic group containing an electron accepting nitrogen has a high triplet level in many cases, it is preferable to use it as a host material of the element using a triplet light emitting material. What is especially suitable as a compound which has an aromatic heterocyclic group containing an electron-accepting nitrogen is a compound represented by General formula (2)-general formula (4).

In the light emitting device of the present invention, the light emitting material is, in addition to a compound having an aromatic heterocyclic group containing electron-accepting nitrogen, condensed ring derivatives such as anthracene and pyrene, which are known as light emitters, and tris (8-quinolinolato) aluminum. Metal chelated oxynoid compounds, including bisstyryl derivatives such as bisstyrylanthracene derivatives or distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, and perinone derivatives , Cyclopentadiene derivatives, oxadiazole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, polyphenylenevinylene derivatives, polyparaphenylene derivatives, and poly Although thiophene derivative etc. can be used, it is not specifically limited. .

The host material contained in the luminescent material need not be limited to only one compound, and a plurality of compounds represented by General Formulas (2) to (4) may be used in combination, or General Formulas (2) to (4). You may mix and use the compound represented by) and other host material. Moreover, you may laminate | stack and use the compound represented by General formula (2)-General formula (4), or the compound and other host material represented by General formula (2)-General formula (4). Although it does not specifically limit as another host material, The compound and its derivative which have condensed aryl rings, such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, indene, etc. , Aromatic amine derivatives such as N, N'-dinaphthyl-N, N'-diphenyl-4,4'-diphenyl-1,1'-diamine, tris (8-quinolinate) aluminum (III) Bisstyryl derivatives such as metal chelated oxynoid compounds, distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, Pyrrolopyrrole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, polyphenylenevinylene derivatives, polyparaphenylene derivatives, Polyfluorene derivatives, polyvinylcarbazole derivatives, polythiophene derivatives and the like can be used, but are not limited to these. Especially, as a host used when a light emitting layer performs triplet light emission (phosphorescence light emission), a metal chelation oxynoid compound, a dibenzofuran derivative, a dibenzothiophene derivative, a carbazole derivative, an indolocarbazole derivative, a triazine derivative , Triphenylene derivatives and the like 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- ( Benzothiazol-2-yl) -9,10-diphenylanthracene or 5,6,11,12-tetraphenylnaphthacene), furan, pyrrole, thiophene, silol, 9-silafluorene, 9,9 '-Spirobisililafluorene, benzothiophene, benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, thioxanthene, etc. Compound having a heteroaryl ring, derivative thereof, distyrylbenzene derivative, 4,4'-bis (2- (4-diphenylaminophenyl) ethenyl) biphenyl, 4,4'-bis (N- (steel Aminostyryl derivatives such as ben-4-yl) -N-phenylamino) stilbene, aromatic acetylene derivatives, tetraphenylbutadiene derivatives, stilbene derivatives, al Gin derivatives, pyrromethene derivatives, diketopyrrolo [3,4-c] pyrrole derivatives, 2,3,5,6-1H, 4H-tetrahydro-9- (2'-benzothiazolyl) quinolizino [9 Coumarin derivatives such as, 9a, 1-gh] coumarin, azole derivatives such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, triazole and metal complexes thereof and N, N'-di And aromatic amine derivatives represented by phenyl-N, N'-di (3-methylphenyl) -4,4'-diphenyl-1,1'-diamine.

Among them, the dopants used when the light emitting layer performs triplet emission (phosphorescence emission) include iridium (Ir), ruthenium (Ru), palladium (Pd), platinum (Pt), osmium (Os), and rhenium (Re). It is preferable that it is a metal complex compound containing at least 1 metal chosen from the group which consists of. The ligand preferably has a nitrogen-containing aromatic heterocycle such as a phenylpyridine skeleton, a phenylquinoline skeleton, or an N-heterocyclic carbene skeleton. However, the present invention is not limited to these, and an appropriate complex is selected from the relationship between the required emission color, device performance, and host compound. Specifically, tris (2-phenylpyridyl) iridium complex, tris {2- (2-thiophenyl) pyridyl} iridium complex, tris {2- (2-benzothiophenyl) pyridyl} iridium complex, tris ( 2-phenylbenzothiazole) iridium complex, tris (2-phenylbenzooxazole) iridium complex, trisbenzoquinolineiridium complex, bis (2-phenylpyridyl) (acetylacetonate) iridium complex, bis {2- (2 -Thiophenyl) pyridyl} iridium complex, bis {2- (2-benzothiophenyl) pyridyl} (acetylacetonate) iridium complex, bis (2-phenylbenzothiazole) (acetylacetonate) iridium complex, bis (2-phenylbenzooxazole) (acetylacetonate) iridium complex, bisbenzoquinoline (acetylacetonate) iridium complex, bis {2- (2,4-difluorophenyl) pyridyl} (acetylacetonate) iridium Complex, tetraethylporphyrin platinum complex, {tris (cenoyltrifluoroacetone) mono (1,10-phenanthroline)} europium complex, { Lis (cenoyltrifluoroacetone) mono (4,7-diphenyl-1,10-phenanthroline)} europium complex, {tris (1,3-diphenyl-1,3-propanedione) mono (1 , 10-phenanthroline)} europium complex, trisacetylacetone terbium complex, and the like. Moreover, the phosphorescent dopant described in Unexamined-Japanese-Patent No. 2009-130141 is also used suitably. Although not limited to these, an iridium complex or a platinum complex is used preferably because high efficiency light emission is easy to be obtained.

As for the said triplet light emitting material used as a dopant material, only 1 type may respectively be included in a light emitting layer, and 2 or more types may be mixed and used for it. When using 2 or more types of triplet light emitting materials, it is preferable that the total mass of a dopant material is 30 mass% or less with respect to a host material, More preferably, it is 20 mass% or less. The following examples are mentioned as a preferable dopant.

In addition, the light emitting layer may include a third component for the purpose of adjusting the carrier balance in the light emitting layer or stabilizing the layer structure of the light emitting layer in addition to the host material and the triplet light emitting material. Specifically, the following examples are mentioned.

In the light emitting device of the present invention, the electron transport layer is a layer in which electrons are injected from the cathode and transport electrons. The electron injection layer has high electron injection efficiency and it is desired to transport the injected electrons efficiently. For this reason, the electron transporting layer is required to be a substance having a high electron affinity, a high electron mobility, excellent stability, and impurities that are trapped, which are unlikely to occur during manufacture and use. Particularly, when the film thickness is laminated thickly, a compound having a molecular weight of 400 or more that maintains stable film quality is preferable because the low molecular weight compound tends to deteriorate due to crystallization. However, in consideration of the balance of transport of holes and electrons, if the electron transport layer mainly achieves the role of effectively preventing the holes from the anode from flowing back to the cathode side without being recombined, it is composed of a material having a very low electron transport capacity. Even if it is, the effect which improves luminous efficiency becomes equivalent to the case comprised with the material with high electron transport ability. Therefore, the electron blocking layer in the present invention also includes a hole blocking layer that can effectively inhibit the movement of holes.

Examples of the electron transporting material used in the electron transporting layer include condensed polycyclic aromatic derivatives such as naphthalene and anthracene, styryl-based aromatic ring derivatives represented by 4,4'-bis (diphenylethenyl) biphenyl, anthraquinone and diphenoquinone, and the like. Quinone derivatives, phosphoxide derivatives, quinolinol complexes such as tris (8-quinolinolato) aluminum (III), benzoquinolinol complexes, hydroxyazole complexes, azomethine complexes, tropolone metal complexes and flavonol metals Various metal complexes, such as a complex, are mentioned. As the electron transporting material used in the electron transporting layer of the present invention, an aromatic compound composed of an electron-accepting nitrogen and an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus in view of reducing the driving voltage and obtaining high efficiency light emission. Preference is given to using compounds having a summoning structure.

The electron-accepting nitrogen here refers to a nitrogen atom which forms a multiple bond with adjacent atoms. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron accepting property. Therefore, the aromatic heterocycle containing electron accepting nitrogen has high electron affinity. The electron transporting material having electron-accepting nitrogen makes it easier to receive electrons from the cathode having high electron affinity, thereby enabling lower voltage driving. In addition, since the supply of electrons to the light emitting layer is increased and the recombination probability is increased, the light emission efficiency is improved.

Examples of the heteroaryl ring containing an electron-accepting nitrogen include a pyridine ring, a pyrazine ring, a pyrimidine ring, a quinoline ring, a quinoxaline ring, a naphthyridine ring, a pyrimidopyrimidine ring, a benzoquinoline ring, a phenanthroline ring, and the like. A diazole ring, an oxazole ring, an oxadiazole ring, a triazole ring, a thiazole ring, a thiadiazole ring, a benzoxazole ring, a benzothiazole ring, a benzoimidazole ring, a phenanthromidazole ring, etc. are mentioned.

Examples of the compound having a heteroaryl ring structure include a benzoimidazole derivative, a benzoxazole derivative, a benzothiazole derivative, an oxadiazole derivative, a thiadiazole derivative, a triazole derivative, a pyrazine derivative, a phenanthroline derivative, Quinoxaline derivatives, quinoline derivatives, benzoquinoline derivatives, oligopyridine derivatives such as bipyridine and terpyridine, quinoxaline derivatives and naphthyridine derivatives and the like can be given as preferred compounds. Among them, imidazole derivatives such as tris (N-phenylbenzimidazol-2-yl) benzene, 1,3-bis [(4-tert-butylphenyl) -1,3,4-oxadiazolyl] phenylene Triazole derivatives such as oxadiazole derivatives such as N-naphthyl-2,5-diphenyl-1,3,4-triazole, bathocuproine and 1,3-bis (1,10) Phenanthroline derivatives such as phenanthroline-9-yl) benzene, and benzoquinoline derivatives such as 2,2'-bis (benzo [h] quinolin-2-yl) -9,9'-spirobifluorene; Bipyridine derivatives such as 2,5-bis (6 '-(2', 2 ''-bipyridyl))-1,1-dimethyl-3,4-diphenylsilol, and 1,3-bis (4 ' Terpyridine derivatives such as-(2,2 ': 6'2' '-terpyridinyl)) benzene, and bis (1-naphthyl) -4- (1,8-naphthyridin-2-yl) phenylphosphine Naphthyridine derivatives such as oxides are preferably used in view of electron transporting ability. Moreover, when these derivatives have a condensed polycyclic aromatic skeleton, since glass transition temperature improves and electron mobility becomes large, the effect of the low voltage of a light emitting element is more preferable. In addition, when the durability of the device is improved, and the ease of synthesis and the availability of raw materials are taken into consideration, the condensed polycyclic aromatic skeleton is particularly preferably an anthracene skeleton, a pyrene skeleton or a phenanthroline skeleton. Although the said electron carrying material is used independently, you may mix and use 2 or more types of the said electron carrying materials, or you may mix and use 1 or more types of other electron carrying materials to the said electron carrying material.

Although it does not specifically limit as a preferable electron carrying material, Specifically, the following examples are mentioned.

Although the said electron carrying material is used individually, you may mix and use donor material. Here, the donor material is a compound which facilitates electron injection from the cathode or the electron injection layer to the electron transport layer by improving the electron injection barrier, and also improves the electrical conductivity of the electron transport layer.

Preferred examples of the donor material include alkali metals, inorganic salts containing alkali metals, complexes of alkali metals and organic matters, alkaline earth metals, complexes of inorganic earths containing alkaline earth metals or alkaline earth metals and organic matters. . Preferred types of alkali metals and alkaline earth metals include alkali metals such as lithium, sodium, potassium, rubidium and cesium having low work function and high effect of improving electron transport ability, and alkaline earth metals such as magnesium, calcium, cerium and barium. Can be.

Moreover, since vapor deposition in a vacuum is easy and handling is excellent, it is preferable that it is a state of a complex with an inorganic salt or an organic substance rather than a metal single body. Moreover, it is more preferable to be in the state of a complex with organic substance from the point of the handling in air | atmosphere, and the addition concentration control being easy. Examples of the inorganic salts include oxides such as LiO and Li ₂ O, nitrides, fluorides such as LiF, NaF, KF, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Rb ₂ CO ₃ , Cs ₂ CO _3, and the like. Carbonates and the like. Moreover, lithium and cesium are mentioned as a preferable example of an alkali metal or alkaline earth metal from a viewpoint that a large low voltage drive effect is acquired. Moreover, as a preferable example of the organic substance in a complex with an organic substance, quinolinol, benzoquinolinol, pyridylphenol, flavonol, hydroxy imidazopyridine, hydroxybenzazole, hydroxytriazole, etc. are mentioned. Among them, a complex of an alkali metal and an organic substance is preferable from the viewpoint of the effect of lowering the voltage of the light emitting device more, and a complex of lithium and an organic substance is more preferable from the viewpoint of ease of synthesis and thermal stability, and is relatively inexpensive to obtain. Lithium quinolinol is particularly preferred.

Although the ionization potential of an electron carrying layer is not specifically limited, Preferably it is 5.6 eV or more and 8.0 eV or less, More preferably, they are 6.0 eV or more and 7.5 eV or less.

The method of forming each of the layers constituting the light emitting device is not particularly limited, such as resistive heating deposition, electron beam deposition, sputtering, molecular lamination, coating, etc., but usually, resistive heating deposition or electron beam deposition is preferable in view of device characteristics.

In the light emitting device of the present invention, the thickness of the organic layer, which is the sum of the respective layers, depends on the resistance value of the light emitting material, but can not be limited, but is preferably 1 to 1000 nm. The film thickness of a light emitting layer, an electron carrying layer, and a positive hole transport layer becomes like this. Preferably they are 1 nm or more and 200 nm or less, More preferably, they are 5 nm or more and 100 nm or less.

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

The light emitting element of this invention is used suitably as a display which displays, for example by a matrix and / or a segment system.

In the light emitting device of the present invention, a matrix system displays pixels for display in two dimensions, such as a lattice shape or a mosaic shape, to display characters and images in a set of pixels. The shape and size of the pixel is determined by the use. For example, a square pixel of 300 mu m or less on one side is usually used for image and character display of a personal computer, a monitor, and a television. In the case of a large display such as a display panel, one side uses a pixel of mm order. In the case of black and white display, pixels of the same color may be arranged. In the case of color display, the pixels of red, green, and blue are aligned and displayed. In this case, there are typically delta types and stripe types. The matrix driving method may be either a linear sequential driving method or an active matrix. The linear sequential drive has a simple structure, but the active matrix may be superior when the operation characteristics are taken into consideration.

In the light emitting device of the present invention, the segment system is a system in which a pattern is formed to display predetermined information, and the region determined by the arrangement of the pattern emits light. For example, the time and temperature display in a digital clock and a thermometer, operation state display of an audio device, an electronic cooker, etc., a panel display of an automobile, etc. are mentioned. The matrix display and the segment display may coexist in the same panel.

The light emitting element of this invention is used suitably also as backlight of various apparatuses. The backlight is mainly used for the purpose of improving the visibility of a display device that does not emit light, and is used for a liquid crystal display, a clock, an audio device, an automobile panel, a display panel, and a cover. In particular, the light emitting element of the present invention is preferably used for a liquid crystal display device, and a backlight for personal computer use, particularly in thinning, and can provide a lighter backlight which is ultra thinner than the conventional one.

Example

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Example 1

The glass substrate (Geomatech Co., Ltd. product, 11 ohms / square, the sputter | spatter goods) which deposited 50 nm of ITO transparent conductive films was cut | disconnected to 38 x 46 mm, and the etching was performed. The obtained board | substrate was ultrasonically wash | cleaned for 15 minutes with "Semico Clean 56" (brand name, the product made by Furuuchi Kagaku Co., Ltd.), and it wash | cleaned with ultrapure water. This board | substrate was UV-ozone-processed for 1 hour, just before manufacturing an element, was installed in the vacuum evaporation apparatus, and it exhausted until the vacuum degree in an apparatus became 5 * 10 <^-4> Pa or less. Thereafter, 10 nm of HI-1 was deposited on the substrate as a hole injection layer by a resistance heating method. Next, 100 nm of NPD was deposited as a 1st hole transport layer. Next, 20 nm of HT-1 was deposited as a second hole transport layer. Subsequently, compound H-1 was used as a light emitting layer and compound D-1 was used as a dopant material, and it deposited in thickness of 40 nm so that the dope concentration of a dopant material might be 5 mass%. Subsequently, compound E-1 was laminated | stacked in thickness of 20 nm as an electron carrying layer.

Subsequently, 0.5 nm of lithium fluoride and 60 nm of aluminum were vapor-deposited as a cathode, and the 5 x 5 mm square element was produced. The film thickness here is a crystal oscillation film thickness monitor display value. When the direct current | flow drive of this light emitting element was carried out at 10 mA / cm <2>, green light emission of luminous efficiency 25.0 lm / W was obtained. This light emitting element was continuously driven at a DC current of 10 mA / cm 2, and the luminance was reduced by half for 2500 hours. In addition, compounds NPD, HI-1, HT-1, H-1, D-1, and E-1 are compounds shown below.

Examples 2-11

A light emitting device was constructed in exactly the same way as in Example 1 except that the materials shown in Table 1 were used as the second hole transporting layer, the host material, and the dopant material. The results are shown in Table 1. In addition, HT-2 to HT-6, H-2 to H-4, D-2, and D-3 are compounds shown below.

Comparative Examples 1-9

The light emitting element was produced like Example 1 except having used the material of Table 1 as a 2nd hole transport layer and a host material. The results are shown in Table 1. In addition, HT-7 and H-5-H-7 are compounds shown below.

Example 12

A material shown in Table 1 was used as the electron transporting material, and a deposition rate ratio of 100: 1 (= 0.2 nm / s: A light emitting device was constructed in exactly the same way as in Example 1 except that there was used at 0.002 nm / s). The results are shown in Table 1.

Example 13

The electron transport layer was formed in a two-layer laminated structure, and the compound E-2 was deposited to a thickness of 10 nm as the first electron transport layer, and the co-deposited film of the compound E-1 and the donor metal (Li: lithium) was used as the second electron transport layer. A light emitting device was constructed in exactly the same way as in Example 1 except that the layer was deposited with a thickness of 25 nm and deposited at a deposition rate ratio of 100: 1 (= 0.2 nm / s: 0.002 nm / s). The results are shown in Table 1. In addition, E-2 is a compound shown below.

Example 14

The electron transport layer was formed in a two-layer laminated structure, and the compound E-2 was deposited to a thickness of 10 nm as the first electron transport layer, and the compound E-1 and the donor material (Cs ₂ CO ₃ : cesium carbonate) as the second electron transport layer. A light emitting device was constructed in exactly the same way as in Example 1 except that the co-deposited film was deposited and deposited at a deposition rate ratio of 100: 1 (= 0.2 nm / s: 0.002 nm / s) at a thickness of 25 nm. The results are shown in Table 1.

Example 15

Using the materials shown in Table 1 as the electron transporting layer, a co-deposition film of compound E-3 and a donor material (Liq: lithium quinolinol) was used instead of compound E-1, and a deposition rate ratio of 1: 1 (= 0.05 nm / A light emitting device was constructed in exactly the same way as in Example 1 except that there was used at s: 0.05 nm / s). The results are shown in Table 1. In addition, E-3 is a compound shown below.

Examples 16-17

A light emitting device was constructed in exactly the same way as in Example 15 except that the materials shown in Table 1 were used as the electron transporting layer. The results are shown in Table 1. In addition, E-4 and E-5 are compounds shown below.

Examples 18-19

The light emitting element was produced like Example 1 except having used the material of Table 1 as an electron carrying layer. The results are shown in Table 1.

Example 20

The glass substrate (Geomatech Co., Ltd. product, 11 ohms / square, the sputter | spatter goods) which deposited 50 nm of ITO transparent conductive films was cut | disconnected to 38 x 46 mm, and the etching was performed. The obtained board | substrate was ultrasonically wash | cleaned for 15 minutes with "Semico Clean 56" (brand name, the product made by Furuuchi Kagaku Co., Ltd.), and it wash | cleaned with ultrapure water. This board | substrate was UV-ozone-processed for 1 hour, just before manufacturing an element, was installed in the vacuum evaporation apparatus, and it exhausted until the vacuum degree in an apparatus became 5 * 10 <^-4> Pa or less. Thereafter, 10 nm of compound HI-1 was deposited on the substrate as a hole injection layer by a resistance heating method. Next, 100 nm of NPD was deposited as a 1st hole transport layer. Subsequently, 50 nm of HT-1 was deposited as a 2nd hole transport layer. Subsequently, compound H-8 was used as a light emitting layer and compound D-4 was used as a dopant material, and it deposited in thickness of 30 nm so that dope concentration of a dopant material might be 5 mass%. Subsequently, compound E-1 was laminated | stacked in thickness of 35 nm as an electron carrying layer.

Subsequently, after depositing 0.5 nm of lithium fluoride, 1000 nm of aluminum were vapor-deposited as a cathode, and the 5 x 5 mm square element was produced. The film thickness here is a crystal oscillation film thickness monitor display value. When the direct current | flow drive of this light emitting element was carried out at 10 mA / cm <2>, highly efficient red light emission of luminous efficiency 14.0 lm / W was obtained. When this light emitting element was continuously driven by 10 mA / cm <2> direct current | flow, the brightness was halved in 3000 hours. In addition, compound H-8 is a compound shown below.

Examples 21-25

A light emitting device was constructed and evaluated in the same manner as in Example 20 except that the materials shown in Table 2 were used as the second hole transport layer. The results are shown in Table 2. In addition, compounds HT-8 and HT-9 are compounds shown below.

Comparative Examples 10-13

The light emitting element was produced and evaluated similarly to Example 20 except having used the compound of Table 2 as a 2nd hole transport layer and a host material. The results are shown in Table 2. In addition, compounds HT-10 and H-9 are compounds shown below.

Examples 26-27

A light emitting device was constructed and evaluated in the same manner as in Example 20 except that the materials shown in Table 2 were used as the second hole transporting layer and the electron transporting material. The results are shown in Table 2.

Examples 28-36

The light emitting element was produced and evaluated similarly to Example 20 except having used the compound of Table 2 as a 2nd hole transport layer and a host material. The results are shown in Table 2. In addition, compound H-10-H-18 are compounds shown below.

Claims (11)

A light emitting device comprising at least a hole transporting layer and a light emitting layer between an anode and a cathode and emitting light by electric energy,
The hole transporting layer contains a compound represented by the following general formula (1), and the light emitting layer is a compound having an aromatic heterocyclic group containing an electron-accepting nitrogen, and any one of the following general formulas (2) to (4) A light emitting device comprising the compound shown and a triplet light emitting material.

[In general formula (1), R <^1> -R <^4> may be same or different, respectively, 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, arylthioether group, aryl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, silyl group, -P (= O) R ⁵ R ^{6 It} is selected. R ⁵ and R ⁶ are aryl groups or heteroaryl groups. L is a single bond or a divalent linking group. Provided that R ¹ and R ² are different groups.]

[In general formula (2)-general formula (4), R <^7> -R <^11> and R <^21> -R <^27> may be same or different, respectively, and hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, and a cycloalke Or an alkyl group, alkynyl group, alkoxy group, alkylthio group, arylether group, arylthioether group, aryl group, heteroaryl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group or silyl group. In addition, R ⁷ to R ¹¹ may form a ring with adjacent substituents. Ring A or Ring B represents a benzene ring having a substituent or no substituent condensing with an adjacent ring at any position. Y ¹ to Y ³ are —N (R ²⁸ ) —, —C (R ²⁹ R ³⁰ ) —, an oxygen atom, or a sulfur atom. R <^28> -R <^30> may be same or different, respectively, and is an alkyl group, an aryl group, or heteroaryl group. R ²¹ to R ³⁰ may form a ring with adjacent substituents. L ¹¹ to L ¹⁷ are a single bond or an arylene group. X ¹ to X ⁵ represent a carbon atom or a nitrogen atom, and when X ¹ to X ⁵ are a nitrogen atom, R ⁷ to R ^{11, which} are substituents on the nitrogen atom, do not exist. Provided that the number of nitrogen atoms in X ¹ to X ⁵ is 1 or 2.] A light emitting device comprising at least a hole transporting layer and a light emitting layer between an anode and a cathode and emitting light by electric energy,
The hole transport layer contains a compound represented by the following general formula (1), and the light emitting layer is a compound having an aromatic heterocyclic group containing an electron-accepting nitrogen, and any of the following general formulas (2) to (4) A light emitting device comprising a compound represented by one.

[In General formula (1), R <^1> is a phenyl group. R ² is a diphenylphenyl group, triphenylphenyl group, tetraphenylphenyl group or pentaphenylphenyl group. R ³ and R ⁴ may be the same as or different from each other, and each hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, arylether group, arylthioether group, Aryl group, heteroaryl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, silyl group, -P (= O) R ⁵ R ^{6 It} is selected from the group consisting of. R ⁵ and R ⁶ are aryl groups or heteroaryl groups. L is a single bond or a divalent linking group. Provided that R ¹ and R ² are different groups.]

[In general formula (2)-general formula (4), R <^7> -R <^11> and R <^21> -R <^27> may be same or different, respectively, and hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, and a cycloalke Or an alkyl group, alkynyl group, alkoxy group, alkylthio group, arylether group, arylthioether group, aryl group, heteroaryl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group or silyl group. In addition, R ⁷ to R ¹¹ may form a ring with adjacent substituents. Ring A or Ring B represents a benzene ring having a substituent or no substituent condensing with an adjacent ring at any position. Y ¹ to Y ³ are —N (R ²⁸ ) —, —C (R ²⁹ R ³⁰ ) —, an oxygen atom, or a sulfur atom. R <^28> -R <^30> may be same or different, respectively, and is an alkyl group, an aryl group, or heteroaryl group. R ²¹ to R ³⁰ may form a ring with adjacent substituents. L ¹¹ to L ¹⁷ are a single bond or an arylene group. X ¹ to X ⁵ represent a carbon atom or a nitrogen atom, and when X ¹ to X ⁵ are a nitrogen atom, R ⁷ to R ^{11, which} are substituents on the nitrogen atom, do not exist. Provided that the number of nitrogen atoms in X ¹ to X ⁵ is 1 or 2.] The method according to claim 1 or 2,
The hole transport layer is a light emitting device, characterized in that the compound represented by the general formula (5).

[In formula (5), R <^1> -R <^4> is the same as the above.] delete The method of claim 1,
In said general formula (1), R <^1> and R <^2> is an aryl group which has a substituent or does not have a substituent together. delete The method of claim 1,
In General Formula (1), R ¹ is a phenyl group, and R ² is a diphenylphenyl group, triphenylphenyl group, tetraphenylphenyl group, or pentaphenylphenyl group. delete The method according to any one of claims 1, 2, 5 and 7,
In the general formulas (2) to (4), X ¹ and X ⁵ , or X ³ and X ⁵ , or X ¹ and X ³ are nitrogen atoms. The method according to any one of claims 1, 2, 5 and 7,
At least an electron transport layer is provided between the anode and the cathode, the electron transport layer is a compound having a heteroaryl ring structure composed of an electron-accepting nitrogen, and an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus Light-emitting element characterized by containing. The method of claim 9,
At least an electron transport layer is provided between the anode and the cathode, the electron transport layer is a compound having a heteroaryl ring structure composed of an electron-accepting nitrogen, and an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus Light-emitting element characterized by containing.