WO2014050588A1

WO2014050588A1 - Organic electroluminescent element material and organic electroluminescent element using same

Info

Publication number: WO2014050588A1
Application number: PCT/JP2013/074657
Authority: WO
Inventors: 淳也小川; 孝弘甲斐; 正樹古森; 山本　敏浩
Original assignee: 新日鉄住金化学株式会社
Priority date: 2012-09-28
Filing date: 2013-09-12
Publication date: 2014-04-03
Also published as: JPWO2014050588A1; TW201412764A; JP6310850B2

Abstract

Disclosed is an organic EL element that improves element luminous efficiency, sufficiently secures drive stability, and has a simple constitution; and an organic EL element material that is used in the organic EL element. This organic EL element has a light-emitting layer between a positive electrode and a negative electrode stacked on a substrate, and the light-emitting layer contains, as a host material, an organic EL element material comprising an indolocarbazole compound that has a phosphorescent dopant and a silyl group. The organic EL element material is an indolocarbazole compound having a structure in which the silyl group is replaced by a nitrogen atom of an indolocarbazole ring with a nitrogen-containing aromatic heterocyclic compound interposed therebetween.

Description

Material for organic electroluminescence device and organic electroluminescence device using the same

The present invention relates to an organic electroluminescent element containing an indolocarbazole compound, and more particularly to a thin film device that emits light by applying an electric field to a light emitting layer made of an organic compound.

In general, an organic electroluminescent element (hereinafter referred to as an organic EL element) is composed of a light emitting layer and a pair of counter electrodes sandwiching the layer as the simplest structure. That is, in an organic EL element, when an electric field is applied between both electrodes, electrons are injected from the cathode, holes are injected from the anode, and these are recombined in the light emitting layer to emit light. .

In recent years, organic EL elements using organic thin films have been developed. In particular, in order to increase luminous efficiency, the type of electrode was optimized for the purpose of improving the efficiency of carrier injection from the electrode. From the hole transport layer made of aromatic diamine and 8-hydroxyquinoline aluminum complex (hereinafter referred to as Alq3) As a result of the development of a device with a light emitting layer as a thin film between the electrodes, the luminous efficiency has been greatly improved compared to conventional devices using single crystals such as anthracene. It has been promoted with the aim of putting it into practical use for high-performance flat panels with these characteristics.

In addition, as an attempt to increase the luminous efficiency of the device, it has been studied to use phosphorescence instead of fluorescence. Many devices, including those provided with the hole transport layer composed of the above aromatic diamine and the light emitting layer composed of Alq3, used fluorescence emission, but use phosphorescence emission, that is, triplet. By using the light emitted from the excited state, the efficiency is expected to be improved by about 3 to 4 times compared to the conventional device using fluorescence (singlet). For this purpose, it has been studied to use a coumarin derivative or a benzophenone derivative as a light emitting layer, but only an extremely low luminance was obtained. Further, as an attempt to use the triplet state, use of a europium complex has been studied, but this has not led to highly efficient light emission. In recent years, as described in Patent Document 1, many studies have been conducted focusing on organometallic complexes such as iridium complexes for the purpose of increasing the efficiency of light emission and extending the lifetime.

WO2001 / 041512 A JP 2001-313178 A WO2011 / 125020 A WO2010 / 126234A WO2011 / 025018A

In order to obtain high luminous efficiency, the host material to be used is important simultaneously with the dopant material. A representative example of a host material proposed is 4,4′-bis (9-carbazolyl) biphenyl (hereinafter referred to as CBP), which is a carbazole compound introduced in Patent Document 2. When CBP is used as a host material for a green phosphorescent material typified by tris (2-phenylpyridine) iridium complex (hereinafter referred to as Ir (ppy) 3), CBP is easy to flow holes and not easily flow electrons. The charge injection balance is lost, and excess holes flow out to the electron transport layer side. As a result, the light emission efficiency from Ir (ppy) 3 decreases.

As described above, in order to obtain high luminous efficiency in an organic EL element, a host material having high triplet excitation energy and balanced in both charge (hole / electron) injection and transport characteristics is required. Further, a compound that is electrochemically stable and has high heat resistance and excellent amorphous stability is desired, and further improvement is required.

Patent Document 3 discloses indolocarbazole compounds as shown below.

However, the above compound is a compound in which a silyl group is directly bonded to the indolocarbazole skeleton, and a compound in which a silyl group is bonded to the nitrogen atom of the indolocarbazole skeleton through a nitrogen-containing aromatic heterocyclic group is not disclosed. Absent.

Patent Document 4 discloses an indolocarbazole compound as shown below.

However, in the above compound, a silyl group is bonded to the nitrogen atom of the indolocarbazole skeleton via two aromatic ring groups (or aromatic heterocyclic groups), and the nitrogen atom is contained on the nitrogen atom of the indolocarbazole skeleton. It does not disclose a compound in which a silyl group is bonded via one aromatic heterocyclic group.

Patent Document 5 discloses an indolocarbazole compound as shown below.

However, in the above compound, a silyl group is bonded to the nitrogen atom of the indolocarbazole skeleton via an aromatic hydrocarbon group, and the silyl group is bonded to the nitrogen atom of the indolocarbazole skeleton via a nitrogen-containing aromatic heterocyclic group. It does not disclose compounds in which is bound.

In order to apply an organic EL element to a display element such as a flat panel display, it is necessary to improve the light emission efficiency of the element and at the same time sufficiently ensure stability during driving with a low driving voltage. An object of this invention is to provide a practically useful organic electroluminescent element which has high efficiency and high brightness stability at the time of a drive, and a compound suitable for it in view of the said present condition.

As a result of intensive studies, the present inventors have found that an indolocarbazole compound in which a silyl group is linked by a nitrogen-containing aromatic heterocycle exhibits excellent characteristics by using it as an organic EL device, and completes the present invention. It came to.

The present invention relates to an organic electroluminescent element material comprising an indolocarbazole compound represented by the general formula (1).

In general formula (1), ring A represents an aromatic ring represented by formula (1a) that is condensed at an arbitrary position of the adjacent ring, and ring B is a formula (1b) that is condensed at an arbitrary position of the adjacent ring. Represents the represented heterocycle. In the general formulas (1), (1a) and (1b), L ₁ represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic ring having 3 to 30 carbon atoms. Represents a group constituted by connecting 2 to 6 substituted or unsubstituted aromatic hydrocarbons or substituted or unsubstituted aromatic heterocycles, and L ₂ represents a substituted or unsubstituted S + 1 valent carbon number. 3 to 12 nitrogen-containing aromatic heterocyclic groups are represented. X ₁ and X ₂ represent methine or nitrogen, R ₁ , R ₂ and R ₃ represent hydrogen, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon having 6 to 18 carbon atoms A group or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, wherein R ₄ , R ₅ and R ₆ are an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon group having 6 carbon atoms; Or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms. p and q are integers of 1 to 4, r is 1 to 2, and s is an integer of 1 to 4. Hydrogen in the general formulas (1), (1a), and (1b) may be replaced with deuterium.

Among the indolocarbazole compounds represented by the general formula (1), indolocarbazole compounds represented by any one of the following general formulas (2) to (6) are preferable compounds.

In the general formulas (2) to (6), L ₁ , L ₂ , R ₁ to R ₆ , and p to s are the same as those in the general formula (1).

The present invention also relates to an organic electroluminescent device comprising an anode, an organic layer, and a cathode laminated on a substrate, the organic electroluminescent device having an organic layer containing the above-mentioned organic electroluminescent device material.

Furthermore, it is preferable that the organic layer containing the material for an organic electroluminescent element contains a phosphorescent dopant.

The indolocarbazole skeleton to which a nitrogen-containing aromatic heterocycle is bonded has high charge injection / transport capability, but it is necessary to optimize charge injection / transport properties to further improve device characteristics. However, it is difficult to control the distribution of molecular orbitals that are deeply related to charge injection / transport properties by simply introducing other substituents onto the nitrogen-containing aromatic heterocycle. Therefore, by introducing a substituent through a silicon atom as a spacer that can break the spread of molecular orbitals, the injection and transport properties of both charges can be controlled in a more preferable range. Due to the above effects, the element driving voltage is reduced by using this for the organic EL element. In addition, when the light emitting element material is included in the light emitting layer of the phosphorescent light emitting element, the charge balance is improved, so that the recombination probability is improved. In addition, this light-emitting device material has the lowest excited triplet state energy high enough to confine the dopant's lowest excited triplet state energy, thus reducing the triplet excitation energy transfer from the dopant to the host molecule. It can be effectively suppressed. From the above points, high luminous efficiency can be achieved.

Furthermore, this indolocarbazole compound is distributed on each substituent due to the effect of dividing the expansion of molecular orbitals by connecting the indolocarbazole skeleton and the silyl group via a nitrogen-containing aromatic heterocycle. Control the spread of molecular orbitals. Electrochemical stability (anti-oxidation and anti-reduction stability) is closely related to the molecular orbitals that contribute to them (highest occupied orbitals (HOMO) for oxidation, lowest orbitals (LUMO) for reduction). In order to improve the stability against both charges, it is essential to design a molecule so that HOMO is distributed at sites with high oxidation resistance and LUMO is distributed at sites with high reduction resistance. This indolocarbazole compound is considered to be able to distribute molecular orbitals to sites with high oxidation / reduction stability by controlling the spread of molecular orbitals as described above, and to have good charge stability. In addition, since the phosphorescent light emitting element material exhibits good amorphous characteristics and high thermal stability, it is possible to realize a highly durable organic EL element with a low driving voltage.

It is sectional drawing which shows one structural example of an organic EL element. 2 shows an NMR chart of indolocarbazole compound 6 of the present invention.

The organic electroluminescent element material of the present invention is an indolocarbazole compound represented by the general formula (1). By having one of the two nitrogens of the indolocarbazole compound substituted with a nitrogen-containing aromatic heterocycle to which a silicon group is bonded, it is considered that the excellent effects as described above are brought about. Moreover, since the indolocarbazole compound for organic electroluminescent elements of this invention is used suitably as a material for phosphorescent light emitting elements, it is also called a material for phosphorescent light emitting elements.

In general formula (1), ring A represents an aromatic ring represented by formula (1a) that is condensed at an arbitrary position of the adjacent ring, and ring B is a formula (1b) that is condensed at an arbitrary position of the adjacent ring. Represents the represented heterocycle. In the formula (1a), X ₁ and X ₂ independently represent methine or nitrogen. When both are methine, they are aromatic hydrocarbon rings, and when one or both are nitrogen, aromatic heteroelements It is a ring. The aromatic ring may have a substituent represented by R ₃ . The heterocyclic ring has a substituent represented by -L _2- (SiR ₄ R ₅ R ₆ ) _s .

In the general formula (1), L ₁ represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 30 carbon atoms, the substituted or unsubstituted It represents a group constituted by connecting 2 to 6 aromatic hydrocarbons or substituted or unsubstituted aromatic heterocycles. Preferably, the substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, the substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, the substituted or unsubstituted aromatic hydrocarbon group, or the substituted or unsubstituted This is a group constituted by connecting 2 to 5 substituted aromatic heterocycles.

Specific examples of the unsubstituted aromatic hydrocarbon group include groups generated by removing one hydrogen from an aromatic hydrocarbon compound such as benzene, naphthalene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, chrysene. Preferable examples include groups generated by removing one hydrogen from benzene, naphthalene, anthracene, and phenanthrene.

Specific examples of the unsubstituted aromatic heterocyclic group include pyridine, pyrimidine, triazine, quinoline, isoquinoline, quinoxaline, naphthyridine, carbazole, dibenzofuran, dibenzothiophene, acridine, azepine, tribenzoazepine, phenazine, phenoxazine, phenothiazine, And a group formed by removing one hydrogen from an aromatic heterocyclic compound such as dibenzophosphole or dibenzoborol. Preferable examples include groups formed by removing one hydrogen from pyridine, pyrimidine, triazine, carbazole, dibenzofuran, and dibenzothiophene.

In the case of a group constituted by connecting 2 to 6 substituted or unsubstituted aromatic hydrocarbon compounds or substituted or unsubstituted aromatic heterocyclic compounds, the connected aromatic compounds may be the same or different. Also good. The number to be linked is preferably 2 to 5, more preferably 2 or 3.

Specific examples of the group constituted by connecting 2 to 6 unsubstituted aromatic compounds include biphenyl, terphenyl, phenylnaphthalene, diphenylnaphthalene, phenylanthracene, diphenylfluorene, bipyridine, bipyrimidine, vitriazine, Biscarbazole, bisdibenzofuran, bisdibenzothiophene, phenylpyridine, phenylpyrimidine, phenyltriazine, phenylcarbazole, phenyldibenzofuran, phenyldibenzothiophene, diphenylpyridine, diphenyltriazine, biscarbazolylbenzene, bisdibenzofuranylbenzene, bisdibenzothio And a group formed by removing one hydrogen from phenylbenzene or the like.

Note that the aromatic hydrocarbon group, the aromatic heterocyclic group, and the group constituted by connecting two to six aromatic hydrocarbons or aromatic heterocyclic rings may have a substituent. When it has, a preferable substituent is an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an acetyl group. More preferably, it is an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, or an acetyl group. However, silicon-containing groups do not become substituents.

Here, as an example in the case of unsubstituted, a group constituted by connecting 2 to 6 aromatic hydrocarbons or aromatic heterocycles is represented by the following formula, for example, linear or branched It may be connected.

(Ar ₁ to Ar ₆ are unsubstituted aromatic hydrocarbons or aromatic heterocyclic rings.)

In the general formula (1), L ₂ represents a substituted or unsubstituted s + 1 valent nitrogen-containing aromatic heterocyclic group having 3 to 12 carbon atoms. Preferred is a substituted or unsubstituted nitrogen-containing aromatic heterocyclic group having 3 to 10 carbon atoms.
Specific examples of the unsubstituted nitrogen-containing aromatic heterocyclic group include pyridine, pyrimidine, triazine, quinoline, isoquinoline, quinolidine, phthalazine, quinazoline, quinoxaline, naphthyridine, carbazole, acridine, azepine, tribenzazepine, phenazine, phenoxazine, S + 1 groups generated by removing S + 1 hydrogen from a nitrogen-containing aromatic heterocyclic compound such as phenothiazine. Preferably, an S + 1 valent group derived from pyridine, pyrimidine, or triazine is used. The nitrogen-containing aromatic heterocyclic compound preferably has a monocyclic structure or a structure in which 2 to 3 rings are condensed.

The nitrogen-containing aromatic heterocyclic ring may have a substituent, and when it has a substituent, preferred substituents include an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and a carbon number. An alkoxy group having 1 to 12 carbon atoms, an acetyl group, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or an aromatic heterocyclic group having 3 to 17 carbon atoms. More preferably, it is an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, an acetyl group, an aromatic hydrocarbon group having 6 to 12 carbon atoms, or an aromatic heterocyclic group having 3 to 12 carbon atoms. . However, silicon-containing groups do not become substituents.

Specific examples of the substituent include methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group, hexyl group, octyl group, cyclopentyl group, cyclohexyl group, methoxy group, ethoxy group, propoxy group, butoxy group, Acetyl group, phenyl group, pyridyl group, pyrimidyl group, triazyl group, naphthyl group, quinolyl group, isoquinolyl group, quinazolyl group, phthalazyl group, fluorenyl group, carbazolyl group, dibenzofuranyl group, dibenzothiophenyl group, and more Preferable examples include phenyl group, pyridyl group, pyrimidyl group, triazyl group, naphthyl group, quinolyl group, isoquinolyl group, fluorenyl group, and carbazolyl group.

These substituents may further have a substituent, preferably an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, an acetyl group, an aromatic hydrocarbon group having 6 to 12 carbon atoms, carbon Examples of the aromatic heterocyclic group of formula 3 to 12 include methyl group, ethyl group, isopropyl group, butyl group, methoxy group, ethoxy group, acetyl group, phenyl group, pyridyl group, pyrimidyl group, triazyl group. Naphthyl group, quinolyl group, isoquinolyl group, fluorenyl group, carbazolyl group, dibenzofuranyl group, dibenzothiophenyl group. However, silicon-containing groups do not become this substituent.

In the general formula (1), p is an integer of 1 to 4, preferably an integer of 1 to 2. q is an integer of 1 to 4, preferably an integer of 1 to 2. r represents an integer of 1 to 2. s is an integer of 1 to 4, preferably an integer of 1 to 2.

In the general formula (1), R ₁ to R ₃ are each independently hydrogen, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, An unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms is shown. Preferably, hydrogen, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, or a substituted or unsubstituted carbon group having 3 to 12 carbon atoms. An aromatic heterocyclic group.

Specific examples of R ₁ to R ₃ include hydrogen, methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group, hexyl group, octyl group, cyclopentyl group, cyclohexyl group, methoxy group, ethoxy group, propoxy Group, butoxy group, acetyl group, phenyl group, pyridyl group, pyrimidyl group, triazyl group, naphthyl group, quinolyl group, isoquinolyl group, quinazolyl group, phthalazyl group, fluorenyl group, carbazolyl group, dibenzofuranyl group, dibenzothiophenyl group More preferred are hydrogen, phenyl group, pyridyl group, pyrimidyl group, triazyl group, naphthyl group, quinolyl group, isoquinolyl group, fluorenyl group, and carbazolyl group.

These may further have a substituent, preferably an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, an acetyl group, an aromatic hydrocarbon group having 6 to 12 carbon atoms, or a carbon number of 3 -12 aromatic heterocyclic groups, and specific examples include methyl, ethyl, isopropyl, butyl, methoxy, ethoxy, acetyl, phenyl, pyridyl, pyrimidyl, triazyl, naphthyl Group, quinolyl group, isoquinolyl group, fluorenyl group, carbazolyl group, dibenzofuranyl group, or dibenzothiophenyl group. However, silicon-containing groups do not become this substituent.

In the general formula (1), R ₄ to R ₆ are each independently an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted group. And an aromatic heterocyclic group having 3 to 17 carbon atoms. These aliphatic hydrocarbon group, aromatic hydrocarbon group or aromatic heterocyclic group are the same as described for R ₁ to R ₃ .

Among the indolocarbazole compounds represented by the general formula (1), the indolocarbazole compounds represented by the above general formulas (2) to (6) may be mentioned as preferred compounds, and the above general formulas (2), (4 ), (5) or indolocarbazole compounds represented by (6) are more preferred compounds.

In general formulas (1) to (6), the same symbols and formulas are understood to have the same meaning unless otherwise specified.

The total number of carbon atoms of the indolocarbazole compounds represented by the general formulas (1) to (6) is preferably 150 or less, more preferably 100 or less.

The indolocarbazole compounds represented by the general formulas (1) to (6) can be synthesized by selecting a raw material according to the structure of the target compound and using a known method.

For example, the parent skeleton of indolocarbazole is Synlett, 2005, No. 1; 1, skeleton (A-1) can be synthesized by the following reaction formula with reference to the synthesis example shown in p42-48.

The skeleton (A-2) can be synthesized by the following reaction formula with reference to the synthesis example shown in Journal of Heterocyclic Chemistry, 1992, 29, p1237.

With reference to the synthesis example shown in Tetrahedron, 2000, 56, p1911, the skeleton (A-3) can be synthesized by the following reaction formula.

The skeleton (A-4) can be synthesized by the following reaction formula with reference to synthesis examples shown in The Journal of Organic Chemistry, 2007, 72 (15) 5886 and Tetrahedron, 1999, 55, p2371.

The skeleton (A-5) can be synthesized by the following reaction formula with reference to the synthesis example shown in Archiv der Pharmazie (Weinheim, Germany), 1987, 320 (3), p280-2.

Indolocarbazole compounds represented by the general formulas (1) to (6) are obtained by substituting hydrogen on nitrogen of each indolocarbazole skeleton obtained by the above reaction formula with a corresponding aromatic group according to a conventional method. Groups can be synthesized.

Specific examples of the indolocarbazole compounds represented by the general formulas (1) to (6) are shown below, but the organic electroluminescent element material of the present invention is not limited thereto.

The organic electroluminescent element material of the present invention contains an excellent organic electroluminescent element by containing it in at least one organic layer of an organic EL element in which an anode, a plurality of organic layers and a cathode are laminated on a substrate. give. As the organic layer to be contained, a light emitting layer, an electron transport layer or a hole blocking layer is suitable. Here, when used in a light emitting layer, it can be used as a host material of a light emitting layer containing a fluorescent, delayed fluorescent or phosphorescent dopant, and the compound of the present invention emits fluorescence and delayed fluorescence. It can be used as an organic light emitting material. The compound of the present invention is particularly preferably contained as a host material for a light emitting layer containing a phosphorescent dopant.

Next, an organic EL element using the organic electroluminescent element material of the present invention will be described.

The organic EL device of the present invention has an organic layer having at least one light emitting layer between an anode and a cathode laminated on a substrate, and the at least one organic layer is for the organic electroluminescent device of the present invention. Contains materials. Advantageously, the organic electroluminescent device material of the present invention is included in the light emitting layer together with a phosphorescent dopant.

Next, the structure of the organic EL element of the present invention will be described with reference to the drawings. However, the structure of the organic EL element of the present invention is not limited to the illustrated one.

FIG. 1 is a cross-sectional view showing a structural example of a general organic EL device used in the present invention, wherein 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, and 5 is a light emitting layer. , 6 represents an electron transport layer, and 7 represents a cathode. The organic EL device of the present invention may have an exciton blocking layer adjacent to the light emitting layer, and may have an electron blocking layer between the light emitting layer and the hole injection layer. The exciton blocking layer can be inserted on either the anode side or the cathode side of the light emitting layer, or both can be inserted simultaneously. The organic EL device of the present invention has a substrate, an anode, a light emitting layer and a cathode as essential layers, but it is preferable to have a hole injecting and transporting layer and an electron injecting and transporting layer in layers other than the essential layers, and further emitting It is preferable to have a hole blocking layer between the layer and the electron injecting and transporting layer. The hole injection / transport layer means either or both of a hole injection layer and a hole transport layer, and the electron injection / transport layer means either or both of an electron injection layer and an electron transport layer.

In addition, it is also possible to laminate | stack the cathode 7, the electron carrying layer 6, the light emitting layer 5, the positive hole transport layer 4, and the anode 2 in order on the board | substrate 1 in the reverse structure, FIG. Layers can be added or omitted as necessary.

-substrate-
The organic EL element of the present invention is preferably supported on a substrate. The substrate is not particularly limited as long as it is conventionally used for an organic EL element. For example, a substrate made of glass, transparent plastic, quartz, or the like can be used.

-anode-
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such an electrode substance include conductive transparent materials such as metals such as Au, CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not required (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

-cathode-
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

In addition, a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode after producing the metal with a thickness of 1 to 20 nm on the cathode. By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

-Light emitting layer-
The light emitting layer is a layer that emits light after excitons are generated by recombination of holes and electrons injected from the anode and the cathode, respectively. The light emitting layer includes an organic light emitting material and a host material.

When the light emitting layer is a fluorescent light emitting layer, a fluorescent light emitting material can be used alone for the light emitting layer, but it is preferable to use a fluorescent light emitting material as a fluorescent light emitting dopant and to mix a host material.

As the fluorescent light emitting material in the light emitting layer, an indolocarbazole compound represented by the general formula (1) can be used. However, since it is known from many patent documents, it can be selected from them. For example, benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives, condensed aromatic compounds, perinone derivatives, oxadiazole derivatives , Oxazine derivatives, aldazine derivatives, pyralidine derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolopyridine derivatives, styrylamine derivatives, diketopyrrolopyrrole derivatives, aromatic dimethylolidine compounds, 8-quinolinol Polythiophene such as metal complexes of derivatives, metal complexes of pyromethene derivatives, various metal complexes represented by rare earth complexes, transition metal complexes, etc. , Polyphenylene, polyphenylene vinylene polymer compounds such as, organic silane derivatives, and the like. Preferred examples include condensed aromatic compounds, styryl compounds, diketopyrrolopyrrole compounds, oxazine compounds, pyromethene metal complexes, transition metal complexes, and lanthanoid complexes, more preferably naphthacene, pyrene, chrysene, triphenylene, benzo [c] phenanthrene, Benzo [a] anthracene, pentacene, perylene, fluoranthene, acenaphthofluoranthene, dibenzo [a, j] anthracene, dibenzo [a, h] anthracene, benzo [a] naphthacene, hexacene, anthanthrene, naphtho [2,1 -f] isoquinoline, α-naphthaphenanthridine, phenanthrooxazole, quinolino [6,5-f] quinoline, benzothiophanthrene and the like. These may have an alkyl group, an aryl group, an aromatic heterocyclic group, or a diarylamino group as a substituent.

As the fluorescent host material in the light emitting layer, an indolocarbazole compound represented by the general formula (1) can be used, but since it is known from a large number of patent documents, it can be selected from them. For example, a compound having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, indene or a derivative thereof, N, N′-dinaphthyl-N, N′-diphenyl-4 Aromatic amine derivatives such as 4,4'-diphenyl-1,1'-diamine, metal chelated oxinoid compounds such as tris (8-quinolinato) aluminum (III), bisstyryl derivatives such as distyrylbenzene derivatives, tetraphenyl Butadiene 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, in polymer systems, a polyphenylene vinylene derivative, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, polythiophene derivatives can be used, but is not particularly limited.

When the fluorescent light emitting material is used as a fluorescent light emitting dopant and a host material is included, the amount of the fluorescent light emitting dopant contained in the light emitting layer is 0.01 to 20% by weight, preferably 0.1 to 10% by weight. It should be in range.

Usually, an organic EL element injects electric charges into a luminescent material from both an anode and a cathode, generates an excited luminescent material, and emits light. In the case of a charge injection type organic EL device, it is said that 25% of the generated excitons are excited to a singlet excited state and the remaining 75% are excited to a triplet excited state. As shown in Advanced Materials 2009, 21, 4802-4806, certain fluorescent materials emit triplet-triplet annihilation or heat after energy transition to triplet excited state due to intersystem crossing etc. It is known that, due to the absorption of energy, the singlet excited state is crossed back to back and emits fluorescence, thereby expressing thermally activated delayed fluorescence. The organic EL device of the present invention can also exhibit delayed fluorescence. In this case, both fluorescence emission and delayed fluorescence emission can be included. However, light emission from the host material may be partly or partly emitted.

When the light emitting layer is a delayed fluorescent light emitting layer, a delayed light emitting material can be used alone in the light emitting layer, but it is preferable to use a delayed fluorescent material as a delayed fluorescent light emitting dopant and mix a host material.

As the delayed fluorescent light emitting material in the light emitting layer, an indolocarbazole compound represented by the general formula (1) can be used, but it can also be selected from known delayed fluorescent light emitting materials. For example, a tin complex, an indolocarbazole derivative, a copper complex, a carbazole derivative, and the like can be given. Specific examples include compounds described in the following non-patent documents and patent publications, but are not limited to these compounds.

DvAdv. Mater. 2009, 21,24802-4806, Appl. Phys. Lett. 98, 083302 (2011), JP2011-213643, and J. Am. Chem. Soc. 2012, 134, 14706-14709.

Specific examples of delayed luminescent materials are shown, but are not limited to the following compounds.

When the delayed fluorescent material is used as a delayed fluorescent material and includes a host material, the amount of the delayed fluorescent material contained in the light emitting layer is 0.01 to 50% by weight, preferably 0.1 to 20%. It is good to be in the range of wt%, more preferably 0.01 to 10%.

As the delayed fluorescent host material in the light emitting layer, an indolocarbazole compound represented by the general formula (1) can be used, but it can also be selected from compounds other than indolocarbazole. For example, a compound having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, indene or a derivative thereof, N, N′-dinaphthyl-N, N′-diphenyl-4 Aromatic amine derivatives such as 4,4'-diphenyl-1,1'-diamine, metal chelated oxinoid compounds such as tris (8-quinolinato) aluminum (III), bisstyryl derivatives such as distyrylbenzene derivatives, tetraphenyl Butadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, pyrrolopyrrole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, In the rubazole derivative, indolocarbazole derivative, triazine derivative, and polymer system, polyphenylene vinylene derivative, polyparaphenylene derivative, polyfluorene derivative, polyvinylcarbazole derivative, polythiophene derivative, arylsilane derivative, and the like can be used, but are not particularly limited. .

When the light emitting layer is a phosphorescent light emitting layer, the light emitting layer contains a phosphorescent light emitting dopant and a host material. The phosphorescent dopant material preferably contains an organometallic complex containing at least one metal selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and gold. Specific examples include compounds described in the following patent publications, but are not limited to these compounds.

WO2009 / 073245 Publication, WO2009 / 046266 Publication, WO2007 / 095118 Publication, WO2008 / 156879 Publication, WO2008 / 140657 Publication, US2008 / 261076 Publication, Special Table 2008-542203 Publication, WO2008 / 054584 Publication, Special Table 2008-505925, Special Table 2007-522126, Special Table 2004-506305, Special Table 2006-513278, Special 2006-50596, WO2006 / 046980, WO2005 / 113704 Publication, US2005 / 260449 publication, US2005 / 2260448 publication, US2005 / 214576 publication, WO2005 / 076380 publication, US2005 / 119485 publication, WO2004 / 045001 publication, WO2004 / 045000 publication, WO2006 / 100888 publication, WO2007 / 004380, WO2007 / 023659, WO2008 / 035664, JP2003-272861, JP2004-111193, JP2004-319438, JP2007-2080, JP 2007-9009, JP 2007-227948, JP 2008-91906, JP 2008-311607, JP 2009-19121, JP 2009-46601, JP No. 2009-114369, JP 2003- JP 253128, JP 2003-253129, JP 2003-253145, JP 2005-38847, JP 2005-82598, JP 2005-139185, JP 2005-187473 JP, JP 2005/220136, JP 2006-63080, JP 2006-104201, JP 2006-111623, JP 2006-213720, JP 2006-290891, JP 2006-298899, JP 2006-298900, WO 2007/018067, WO 2007/058080, WO 2007/058104, JP 2006-131561, JP 2008-239565, JP 2008-266163, JP 2009-57367, JP 2002-117978, JP 2003-123982, JP 2003-133074, JP 2006-93542, JP JP 2006-131524, JP 2006-261623, JP 2006-303383, JP 2006-303394, JP 2006-310479, JP 2007-88105, JP 2007- JP 258550, JP 2007-324309, JP 2008-270737, JP 2009-968 00, JP 2009-161524, WO 2008/050733, JP 2003-73387, JP 2004-59433, JP 2004-155709, JP 2006-104132, JP 2008-37848, JP 2008-133212, JP 2009-57304, JP 2009-286716, JP 2010-83852, Special 2009-532546, Special No. 2009-536681, No. 2009-542026, etc.

Preferable phosphorescent dopants include complexes such as Ir (ppy) 3 having a noble metal element such as Ir as a central metal, complexes such as Ir (bt) 2 · acac3, and complexes such as PtOEt3. Specific examples of these complexes are shown below, but are not limited to the following compounds.

The amount of the phosphorescent dopant contained in the light emitting layer is 2 to 40% by weight, preferably 5 to 30% by weight.

When the emissive layer is a phosphorescent light-emitting layer, it is preferable to use an indolocarbazole compound represented by the general formula (1) as a host material in the light-emitting layer. However, when the indolocarbazole compound is used in any organic layer other than the light emitting layer, the material used for the light emitting layer may be a host material other than the indolocarbazole compound. An indolocarbazole compound and another host material may be used in combination. Furthermore, a plurality of known host materials may be used in combination.

A known host compound that can be used is preferably a compound that has a hole transporting ability and an electron transporting ability, prevents a long wavelength of light emission, and has a high glass transition temperature.

Such other host materials are known from a large number of patent documents and can be selected from them. Specific examples of the host material are not particularly limited, but include indole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine. Derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidene compounds, porphyrin compounds, anthraquino Heterocyclic tetracarboxylic acid anhydrides such as dimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, naphthalene perylene, Various metal complexes represented by metal complexes of Russianin derivatives, 8-quinolinol derivatives, metal phthalocyanines, metal complexes of benzoxazole and benzothiazole derivatives, polysilane compounds, poly (N-vinylcarbazole) derivatives, aniline copolymers, Examples thereof include polymer compounds such as thiophene oligomers, polythiophene derivatives, polyphenylene derivatives, polyphenylene vinylene derivatives, polyfluorene derivatives, and the like.

The light emitting layer may be any one of a fluorescent light emitting layer, a delayed fluorescent light emitting layer and a phosphorescent light emitting layer, but is preferably a phosphorescent light emitting layer.

-Hole blocking layer-
The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking.

It is preferable to use the indolocarbazole compound represented by the general formula (1) according to the present invention for the hole blocking layer. However, when the indolocarbazole compound is used in any other organic layer, it is known. A hole blocking layer material may be used. Moreover, as a hole-blocking layer material, the material of the electron carrying layer mentioned later can be used as needed.

-Electron blocking layer-
The electron blocking layer is made of a material that has a function of transporting holes and has a very small ability to transport electrons. The electron blocking layer blocks the electrons while transporting holes, and the probability of recombination of electrons and holes. Can be improved.

As the material for the electron blocking layer, the material for the hole transport layer described later can be used as necessary. The thickness of the electron blocking layer is preferably 3 to 100 nm, more preferably 5 to 30 nm.

-Exciton blocking layer-
The exciton blocking layer is a layer for preventing excitons generated by recombination of holes and electrons in the light emitting layer from diffusing into the charge transport layer. It becomes possible to efficiently confine in the light emitting layer, and the light emission efficiency of the device can be improved. The exciton blocking layer can be inserted on either the anode side or the cathode side adjacent to the light emitting layer, or both can be inserted simultaneously.

As the material for the exciton blocking layer, an indolocarbazole compound represented by the general formula (1) can be used. As other materials, for example, 1,3-dicarbazolylbenzene (mCP), Bis (2-methyl-8-quinolinolato) -4-phenylphenolato aluminum (III) (BAlq).

-Hole transport layer-
The hole transport layer is made of a hole transport material having a function of transporting holes, and the hole transport layer can be provided as a single layer or a plurality of layers.

The hole transport material has either hole injection or transport or electron barrier properties, and may be either organic or inorganic. As the known hole transporting material that can be used, an indolocarbazole compound represented by the general formula (1) is preferably used, but any conventionally known compound can be selected and used. Known hole transporting materials that can be used include, for example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives. , Styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers, particularly thiophene oligomers, etc., but porphyrin compounds, aromatic tertiary amine compounds and It is preferable to use a styrylamine compound, and it is more preferable to use an aromatic tertiary amine compound.

-Electron transport layer-
The electron transport layer is made of a material having a function of transporting electrons, and the electron transport layer can be provided as a single layer or a plurality of layers.

As an electron transport material (which may also serve as a hole blocking material), it is sufficient if it has a function of transmitting electrons injected from the cathode to the light emitting layer. For the electron transport layer, it is preferable to use an indolocarbazole derivative represented by the general formula (1) according to the present invention, and any one of conventionally known compounds can be selected and used. Examples thereof include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, and oxadiazole derivatives. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is of course not limited to these examples, and can be implemented in various forms as long as the gist thereof is not exceeded. .

An indolocarbazole compound as a material for an organic electroluminescent element was synthesized by the route shown below. The compound number corresponds to the number assigned to the above chemical formula.

Synthesis example 1
Synthesis of Compound 6 The reaction formula is shown below.

20.0 g (0.171 mol) of indole and 300 ml of dehydrated diethyl ether were added to a nitrogen-substituted 2000 ml three-necked flask and dissolved, and hydrogen chloride gas was blown into the liquid. Thereafter, the mixture was stirred at room temperature for 15 hours, and then 121.0 g of ethyl acetate was added dropwise, followed by 303.2 g of a saturated sodium hydrogen carbonate solution. The whole was transferred to a separatory funnel and separated into an organic layer and an aqueous layer. The aqueous layer was washed twice with 100 ml of ethyl acetate, and the organic layer obtained in the first fraction and the ethyl acetate layer from which the aqueous layer was washed were combined. The organic layer was washed again with 100 ml of a saturated sodium bicarbonate solution and washed twice with 100 ml of water. The obtained organic layer was dehydrated with magnesium sulfate, and magnesium sulfate was filtered off. Then, the solvent was distilled off under reduced pressure to obtain a viscous liquid. Thereafter, 2.5 g of palladium carbon and 150 ml of toluene were added and refluxed for 3 hours. After cooling to room temperature, palladium carbon was filtered off, and the filtrate was concentrated under reduced pressure. Thereafter, reslurry purification was carried out, followed by drying under reduced pressure to obtain 14.7 g (57.35 mmol, yield 37.0 mol%) of Intermediate A in the form of white powder.

In a 200 ml three-necked flask purged with degassed nitrogen, 14.1 g (61.0 mmol) of Intermediate I, 11.4 g (71.0 mmol) of N, N-dimethylacetaldehyde diethyl acetal and 110.0 g of acetic acid were added and stirred. Heating was started and stirred for 8 hours under reflux. After cooling to room temperature, the resulting white crystals were collected by filtration and rinsed with 30 ml of acetic acid. This was purified by reslurry to obtain 10.4 g (40.6 mmol, yield 66.6%) of intermediate powder B of white powder.

In a nitrogen atmosphere, 28.4 g (0.120 mol) of 2,6-dibromopyridine and 500 mL of tetrahydrofuran (THF) were added and cooled to -50 ° C. Thereafter, 72.7 mL of a 1.65 μM normal butyl hexane solution was dropped, and the mixture was stirred at −50 ° C. for 3 hours. To the obtained black solution, 36.8 g (0.125 mol) of triphenylchlorosilane dissolved in 113 mL of THF and 70 mL of diethyl ether was added dropwise. Then, the mixture was stirred overnight while gradually warming to room temperature. Ethyl acetate (1000 mL) and 1N hydrochloric acid (500 mL) were added to the resulting reaction mixture with stirring, and the organic layer was distilled water (3 mL x 500 mL). ). After the organic layer was dried over anhydrous magnesium sulfate, magnesium sulfate was filtered off and the solvent was distilled off under reduced pressure. The obtained residue was purified by silica gel column chromatography to obtain 10.1 g (24.3 mmol, yield 20.3%) of Intermediate C as a white solid.

In a nitrogen atmosphere, intermediate B 7.40 g (0.0289 mol), intermediate C 10.0 g (0.0241 mol), copper iodide 0.46 g (2.41 mol), tripotassium phosphate 20.5 g (0.0964 mol), trans-1,2 -Cyclohexanediamine 3.47 ml (0.0289 mol) and 1,4-dioxane 241 ml were added and stirred at 120 ° C overnight. After the reaction solution was cooled to room temperature, the solvent was distilled off under reduced pressure. The obtained residue was purified by silica gel column chromatography to obtain 4.0 g6.7 (6.77 mmol, yield 28.1%) of intermediate D as a white solid.

Under a nitrogen atmosphere, Intermediate D 4.0 g (0.00677 mol), iodobenzene 165 g (0.812 mol), copper powder 2.80 g (0.0440 mol), potassium carbonate 10.3 g (0.0745 mol) were added, and the mixture was stirred at 190 ° C. overnight. After the reaction solution was cooled to room temperature, the solvent was distilled off under reduced pressure. The obtained residue was crystallized and purified by silica gel column chromatography to obtain 1.40 g (2.10 mmol, yield 31.0%) of compound 6 as a white solid. FD / MS, m / z = 667, ¹ H-NMR measurement results (measuring solvent: CDCl ₃ ) are shown in FIG.

Further, according to the synthesis examples and the synthesis methods described in the specification, compounds 1, 3, 4, 5, 13, 14, 16, 23, and 35 were synthesized and used for production of an organic EL device.

Example 1
Each thin film was laminated at a vacuum degree of 2.0 × 10 ⁻⁵ Pa by a vacuum deposition method on a glass substrate on which an anode made of an ITO substrate having a thickness of 110 nm was formed. First, copper phthalocyanine (CuPC) was formed to a thickness of 25 nm on ITO as a hole injection layer. Next, NPB was formed to a thickness of 40 nm as a hole transport layer. Next, Compound 1 as a host material and Ir (ppy) ₃ as a dopant were co-deposited from different vapor deposition sources on the hole transport layer to form a light emitting layer having a thickness of 40 nm. At this time, the concentration of Ir (ppy) ₃ was 10 wt%. Next, Alq3 was formed to a thickness of 20 nm as an electron transport layer. Further, on the electron transport layer, lithium fluoride (LiF) was formed to a thickness of 1 nm as an electron injection layer. Finally, on the electron injection layer, aluminum (Al) was formed as an electrode to a thickness of 70 nm to produce an organic EL element.

When an external power source was connected to the obtained organic EL element and a DC voltage was applied, it was confirmed that the organic EL element had the light emission characteristics as shown in Table 3. In Table 3, the luminance, voltage, and luminous efficiency show values at the time of driving at 20 mA / cm ² . The maximum wavelength of the device emission spectrum was 530 nm, and it was found that light emission from Ir (ppy) ₃ was obtained.

Examples 2 to 10
An organic EL device in the same manner as in Example 1 except that

Compound

3, 4, 5, 6, 13, 14, 16, 23, or 35 was used in place of Compound 1 as the host material of the light emitting layer in Example 1. It was created.

Comparative Example 1
An organic EL device was produced in the same manner as in Example 1 except that CBP was used as the host material of the light emitting layer in Example 1.

Comparative Example 2
An organic EL device was produced in the same manner as in Example 1 except that Compound H-1 was used as the host material for the light emitting layer in Example 1.

Comparative Example 3
An organic EL device was produced in the same manner as in Example 1 except that Compound H-2 was used as the host material for the light emitting layer in Example 1.

Comparative Example 4
An organic EL device was produced in the same manner as in Example 1 except that Compound H-3 was used as the host material for the light emitting layer in Example 1.

When the organic EL devices obtained in Examples 2 to 10 and Comparative Examples 1 to 4 were evaluated in the same manner as in Example 1, the light emission characteristics (initial characteristics; @ ^2.5 mA / cm ² ) as shown in Table 3 were obtained. It was confirmed to have. The maximum wavelength of the emission spectra of the organic EL devices obtained in Examples 2 to 10 and Comparative Examples 1 to 4 was 530 nm, and it was identified that light emission from Ir (ppy) ₃ was obtained.

From Table 3, in Examples 1 to 10, when the indolocarbazole compound of the present invention was used for the light emitting layer, it was driven at a lower voltage than the other cases (Comparative Examples 1, 2 and 4). I understand. This is an effect of bonding a nitrogen-containing 6-membered ring on the nitrogen atom of indolocarbazole. For the same reason, Comparative Example 3 also shows low voltage driving. However, the luminous efficiency characteristics of the indolocarbazole compound of the present invention are better than those of Comparative Examples 1, 2, 3 and 4. This is achieved by binding a nitrogen-containing 6-membered ring on the nitrogen atom of indolocarbazole and then introducing an aromatic substituent with a silicon atom as a spacer to control the spread of molecular orbitals and balance the charge. This is an optimized effect and shows the superiority of the indolocarbazole derivative of the present invention. From these results, it is clear that a high-efficiency organic EL phosphorescent device is realized by using the indolocarbazole compound in the light emitting layer.

Industrial applicability

The organic EL device according to the present invention has practically satisfactory levels of light emission characteristics, driving voltage and durability, and is a flat panel display (mobile phone display device, vehicle-mounted display device, OA computer display device, television, etc.), surface light emission. Its technical value is great in applications to light sources (lighting, light sources for copying machines, backlight light sources for liquid crystal displays and instruments), display boards, and sign lamps that make use of the characteristics of the body.

Claims

A material for an organic electroluminescence device comprising an indolocarbazole compound represented by the general formula (1).

Here, ring A represents an aromatic ring represented by the formula (1a) fused at an arbitrary position of the adjacent ring, and ring B represents a complex represented by formula (1b) fused at an arbitrary position of the adjacent ring. Represents a ring,
L 1 represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 30 carbon atoms, the substituted or unsubstituted aromatic hydrocarbon, or substituted or unsubstituted Represents a group composed of 2 to 6 unsubstituted aromatic heterocycles linked together,
L 2 represents a substituted or unsubstituted s + 1-valent nitrogen-containing aromatic heterocyclic group having 3 to 12 carbon atoms, X 1 and X 2 represent methine or nitrogen,
R 1 , R 2 and R 3 are hydrogen, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted carbon group having 3 to 17 carbon atoms. An aromatic heterocyclic group of
R 4 , R 5 and R 6 are each an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted aromatic group having 3 to 17 carbon atoms. A group heterocyclic group,
p and q are integers of 1 to 4, r is 1 to 2, and s is an integer of 1 to 4.
The material for an organic electroluminescence device according to claim 1, wherein the indolocarbazole compound represented by the general formula (1) is any one of the general formulas (2) to (6).

(In the general formulas (2) to (6), L 1 , L 2 , R 1 to R 6 , and p to s are the same as those in the general formula (1).)
The organic electroluminescent element material according to claim 1, wherein part or all of hydrogen in the indolocarbazole compound represented by the general formula (1) is substituted with deuterium.
An organic electroluminescent device comprising an anode, an organic layer and a cathode laminated on a substrate, wherein the organic electroluminescent device comprises the organic electroluminescent device material according to any one of claims 1 to 3. Electroluminescent device.
The organic electroluminescent element according to claim 4, wherein the organic layer containing the material for an organic electroluminescent element is at least one layer selected from the group consisting of a light emitting layer, an electron transport layer, and a hole blocking layer.
The organic electroluminescent device according to claim 4, wherein the organic layer containing the material for an organic electroluminescent device is a luminescent layer containing a phosphorescent dopant.