KR20150100890A - Material for organic electroluminescent elements and organic electroluminescent element using same - Google Patents

Abstract

An organic electroluminescent element (organic EL element) having a simple structure and a material for an organic EL element to be used therefor are disclosed while improving the luminous efficiency of the element and ensuring sufficient driving stability. The material for the organic EL device is composed of a carboranic compound having a structure in which a silyl group is bonded to a carboran ring through an aromatic group. This carbene compound is represented by [Si (R) ₃ ] _p -L- (A) _r -L- [Si (R) ₃ ] _q . Wherein A is a carboran ring, L is an aromatic group, p is 1 to 5, q is 0 to 5, and r is 1 to 4. Further, the organic EL device has a plurality of organic layers including a light emitting layer between an anode and a cathode stacked on a substrate, and one of the organic layers contains a carboran compound.

Description

TECHNICAL FIELD [0001] The present invention relates to a material for an organic electroluminescent device and an organic electroluminescent device using the same. BACKGROUND ART [0002]

The present invention relates to an organic electroluminescent device containing a carboranic compound, and more particularly, to a thin film type device which 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 opposing electrodes sandwiching the above layer as its simplest structure. That is, in the organic EL device, electrons are injected from the cathode when an electric field is applied between both electrodes, holes are injected from the anode, and they are recombined in the light emitting layer to emit light.

Recently, organic EL devices using organic thin films have been developed. In particular, in order to enhance the luminous efficiency, the optimization of the exemplary electrode type for the purpose of improving efficiency of carrier injection from the electrode, consisting of (hereinafter referred to, Alq ₃₎ a hole transport layer made of an aromatic diamine and a light-emitting layer of 8-hydroxyquinoline aluminum complex Has been developed as a thin film between electrodes, it has been remarkably improved in luminous efficiency as compared with a device using a single crystal such as an anthracene of the related art, so that a high-performance flat panel having characteristics such as self- It has been aimed at practical use.

It has also been studied to use phosphorescence, not fluorescence, as an attempt to increase the luminous efficiency of the device. Many devices, including a device having a hole transport layer made of the above aromatic diamine and a light emitting layer made of Alq ₃ , use fluorescence emission. However, it is also possible to use phosphorescence, that is, to emit light from a triplet excitation state It is expected to improve the efficiency by about 3 to 4 times as compared with 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 extremely low luminance has been obtained. It has also been investigated to use europium complexes as an attempt to use triplet states, but this has not been achieved with high efficiency luminescence. Recently, as shown in Patent Document 1, many studies have been conducted mainly on organometallic complexes such as iridium complexes for the purpose of high efficiency of light emission and longevity.

WO01 / 041512A Japanese Patent Application Laid-Open No. 2001-313178 Japanese Patent Application Laid-Open No. 2005-162709 Japanese Patent Application Laid-Open No. 2005-166574

In order to obtain a high luminescence efficiency, a host material which is used simultaneously with the dopant material is important. Representative examples proposed as a host material include 4,4'-bis (9-carbazolyl) biphenyl (hereinafter referred to as CBP) of a carbazole compound introduced in Patent Document 2. When CBP is used as a host material of a green phosphorescent material represented by tris (2-phenylpyridine) iridium complex (hereinafter referred to as Ir (ppy) ₃ ), CBP is apt to flow holes, The injection balance is disturbed and excess electrons flow out to the electron transporting layer side, and as a result, the luminous efficiency from Ir (ppy) ₃ is lowered.

As described above, in order to obtain a high luminescence efficiency in an organic EL device, a host material balanced in both charge (hole and electron) injection transporting properties and high triplet excitation energy is required. Further, there is a demand for a compound that is electrochemically stable, has excellent heat resistance and excellent amorphous stability, and further improvement is required.

Patent Documents 3 and 4 disclose carboranes compounds as shown below.

However, the above compound does not disclose a compound in which a phenyl group, a fluorenyl group, or a carbazolylphenyl group is bonded to a carbon atom of a carboran skeleton, and a silyl group is bonded to a carbon atom of the carboran skeleton through a linking group.

In order to apply the organic EL device to a display device such as a flat panel display, it is necessary to improve the luminous efficiency of the device and secure sufficient stability at the time of driving. SUMMARY OF THE INVENTION It is an object of the present invention to provide a practically useful organic EL device having high efficiency and high driving stability in consideration of the present situation and a compound suitable therefor.

As a result of intensive studies, the present inventors have found that a carbene compound having a silyl group bonded thereto through an aromatic hydrocarbon group or an aromatic heterocyclic group is used for an organic EL device, thereby exhibiting excellent characteristics.

The present invention relates to a material for an organic electroluminescence device comprising a carbene compound represented by the general formula (1).

Here, ring A represents a tetravalent carbazole group of C ₂ B ₁₀ H ₈ represented by any one of the formulas (1a) and (1b), and may be the same or different when a plurality of ring A is present in the molecule. L ¹ is a group of p + 1, L ² is a group of q + 1, L ¹ and L ² each independently represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted 3-carbon group Or an aromatic heterocyclic group of 1 to 30 carbon atoms or an aromatic group having 2 to 6 aromatic groups selected from the aromatic heterocyclic group and the aromatic heterocyclic group, and the connecting aromatic group may be linear or branched, The aromatic rings may be the same or different. R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ independently represent 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 3-carbon group R ⁷ and R ⁸ are independently selected from the group consisting of 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 aromatic hydrocarbon group having 3 to 18 carbon atoms, Aromatic heterocyclic group having 1 to 17 carbon atoms. p represents an integer of 1 to 5, q represents an integer of 0 to 5, and r represents an integer of 1 to 4.

Among the carbene compounds represented by the general formula (1), the following general formula (2) is preferable, and the carboran compounds represented by the general formulas (3) and (4) are more preferable compounds.

In formula (2), L ¹ , L ² , R ¹ to R ⁸ , p, q and r have the same meanings as in formula (1). Ring A represents a tetravalent carbazole group of C ₂ B ₁₀ H ₈ represented by any one of the formulas (2a) and (2b), and may be the same or different when a plurality of ring A is present in the molecule.

In the general formulas (3) and (4), L ¹ , L ² , R ¹ to R ⁸ and p to r have the same meanings as those of the general formula (1).

In the general formulas (3) and (4), L ¹ and L ² each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, A heterocyclic group, and an aromatic heterocyclic group, and the aromatic heterocyclic group is preferably a connecting aromatic group formed by connecting 2 to 5 aromatic groups selected from the aromatic heterocyclic group.

In the general formulas (3) and (4), it is preferable that R ¹ to R ⁶ are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms.

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

Further, in the present invention, it is preferable that the organic layer containing the organic electroluminescence device material contains a phosphorescent dopant. It is preferable that the phosphorescence-emitting dopant has an emission maximum wavelength of 550 nm or less.

The carboran compound used in the present invention has a structure in which a silyl group is bonded to a carboran skeleton through an aromatic hydrocarbon group or an aromatic heterocyclic group. A carboran skeleton having an aromatic hydrocarbon group or an aromatic heterocyclic group bonded thereto has a high charge injection transport capability. However, in order to further improve the device characteristics, it is necessary to optimize the charge injection transportability. However, it is difficult to control the distribution of the molecular orbital, which is highly related to charge injection transport, merely by introducing other substituents on the aromatic hydrocarbon group, the aromatic heterocyclic group or the carboran ring. Therefore, by introducing a substituent group containing a silicon atom capable of dividing the widening of the molecular orbital, the injection transportability of both charges can be controlled within a more preferable range. By using the organic EL element with the above-described effects, the element driving voltage is reduced.

In addition, when the carbene compound is contained in the light emitting layer, the charge balance is improved and the recombination probability is improved. In addition, the carbene compound has a broad band gap due to the effect of suppressing the conjugate widening of silicon atoms. Having a broad bandgap implies that the T1 energy is high enough to confine the T1 energy of the dopant, as it correlates with the width of the bandgap and the size of the lowest triplet excitation energy (T1 energy). For this reason, migration of T1 energy from the dopant to the host molecule can be effectively suppressed. From this point of view, it has become possible to achieve high luminous efficiency.

This carboran compound can control the molecular orbital distribution on each substituent from the effect of dividing the molecular orbital broadening of the silicon atom by connecting the carboran skeleton and the silyl group through an aromatic hydrocarbon group or an aromatic heterocyclic group. The electrochemical stability (oxidation resistance and reduction stability) is related to the molecular orbitals contributing to them (the highest point orbit (HOMO) in oxidation and the lowest lumen (LUMO) in reduction) It is indispensable to design the molecule such that the LUMO is distributed in the HOMO and the high reduction stability region in the high oxidation stability region. It is considered that this carboran compound can distribute the molecular orbitals to the parts having high durability against oxidation and reduction by controlling the widening of the molecular orbits and can have good charge-proof stability. In addition, since the groups connecting to the silicon atom are not on the same plane, they are difficult to be packed or interacted with each other, and the crystallinity is low, so that the material for the phosphor element exhibits good amorphous characteristics and high thermal stability. That is, the device using the material for the phosphorescent device enabled to realize an organic EL device having a long driving life and high durability.

1 is a cross-sectional view showing an example of the structure of an organic EL device.
Fig. 2 is an NMR chart of the carboran compound 1. Fig.
3 is an NMR chart of the carboran compound 4. FIG.

The material for an organic electroluminescence device of the present invention is a carbene compound represented by the above general formula (1). It is thought that this carbene compound has a structure in which an aromatic hydrocarbon group or aromatic heterocycle bonded with a silyl group is substituted, and thus the above-mentioned excellent effect is obtained.

In the general formula (1), L ¹ or L ² each independently 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 or an aromatic hydrocarbon group and aromatic And the aromatic ring of the aromatic group selected from the heterocyclic group is connected to form 2 to 6 aromatic rings, and when connected, the aromatic rings may be linear or branched, and the aromatic rings to be connected may be the same or different. Preferably a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or an aromatic ring group having 2 to 5 aromatic rings and aromatic heterocyclic groups, Lt; / RTI > On the other hand, L ¹ is a group of p + 1 and L ² is a group of q + 1.

Specific examples of the unsubstituted aromatic hydrocarbon group include aromatic hydrocarbon compounds such as benzene, naphthalene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, chrysene and triphenylene, or aromatic hydrocarbon compounds , And is preferably a group formed by removing hydrogen from benzene, naphthalene, anthracene, phenanthrene, and triphenylene.

Specific examples of the unsubstituted aromatic heterocyclic group include pyridine, pyrimidine, triazine, quinoline, isoquinoline, quinoxaline, naphthyridine, carbazole, dibenzofuran, dibenzothiophene, acridine, An aromatic heterocyclic compound such as a pin, a phenazine, a phenoxazine, a phenothiazine, a dibenzofuspol, a dibenzoborol, etc., or a linking group formed by removing hydrogen from an aromatic heterocyclic compound to which a plurality of them are connected, , Pyrimidine, triazine, carbazole, dibenzofuran, and dibenzothiophene.

A group formed by removing hydrogen from an aromatic compound having a structure in which a plurality of aromatic rings of an aromatic hydrocarbon compound or aromatic heterocyclic compound are linked is referred to as a connecting aromatic group. The connecting aromatic group is a group formed by connecting two to six aromatic rings, and the aromatic rings to be connected may be the same or different, and both of the aromatic hydrocarbon group and the aromatic heterocyclic group may be included. The number of aromatic rings connected is preferably 2 to 5, more preferably 2 or 3.

Specific examples of the linking aromatic group include biphenyl, terphenyl, phenylnaphthalene, diphenylnaphthalene, phenylanthracene, diphenylanthracene, diphenylfluorene, bipyridine, bipyrimidine, bitriazine, biscarbazole, There may be mentioned benzoic acid derivatives such as benzofuran, bisdibenzothiophene, phenylpyridine, phenylpyrimidine, phenyltriazine, phenylcarbazole, phenyldibenzofuran, phenyldibenzothiophene, diphenylpyridine, diphenyltriazine, Bisdibenzofuranylbenzene, bisdibenzothiophenylbenzene, and the like.

The aromatic hydrocarbon group, aromatic heterocyclic group or linking aromatic group may have a substituent. When the substituent is present, the substituent is preferably an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a cyano group or an acetyl group. More preferably an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, or an acetyl group.

When the connecting aromatic group is a divalent group, for example, it is represented by the following formula and may be connected in a linear or branched form.

(Ar ¹ to Ar ⁶ represent an unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring)

In the general formula (1), p represents an integer of 1 to 5, preferably 1 to 2. q is an integer of 0 to 5, preferably 0 to 2. r is an integer of 1 to 4, preferably 1 to 2;

In the general formula (1), R ¹ to R ⁶ each independently represent an aliphatic hydrocarbon group having 1 to 12 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or an aromatic heterocyclic group having 3 to 17 carbon atoms. Preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms. The aliphatic hydrocarbon group may be saturated or unsaturated, and may be linear, branched or cyclic.

Specific examples of R ¹ to R ⁶ include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group, hexyl group and octyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, Aromatic groups such as a pyridyl group, a pyrimidyl group, a triazyl group, a naphthyl group, a quinolyl group, an isoquinolyl group, a quinazolyl group, a phthalazinyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranoyl group, A hydrocarbon group or an aromatic heterocyclic group. Preferably a phenyl group, a pyridyl group, a pyrimidyl group, a triazyl group, a naphthyl group, a quinolyl group, an isoquinolyl group, a fluorenyl group or a carbazolyl group.

These substituents may further have a substituent. Preferred substituents include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, an acetyl group, a cyano group, an aromatic hydrocarbon group having 6 to 12 carbon atoms and an aromatic heterocyclic group having 3 to 12 carbon atoms , And specific examples thereof include a methyl group, ethyl group, isopropyl group, butyl group, methoxy group, ethoxy group, acetyl group, phenyl group, pyridyl group, pyrimidyl group, , A carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and a cyano group.

In the general formula (1), R ⁷ and R ⁸ each independently represent hydrogen, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or an aromatic heterocyclic group having 3 to 17 carbon atoms. Preferred examples of R ¹ to R ⁶ are the same as those described with respect to R ¹ to R ⁶ , except that they contain hydrogen, an aliphatic hydrocarbon group of 1 to 8 carbon atoms, an aromatic hydrocarbon group of 6 to 12 carbon atoms, or an aromatic heterocyclic group of 3 to 12 carbon atoms, same.

In Formula (1), Ring A represents a tetravalent carbazole group of C ₂ B ₁₀ H ₈ represented by any one of Formula (1a) or Formula (1b), and may be the same or different when a plurality of ring A is present in the molecule . The four bonding sites of the formula (1a) or (1b) may be formed from C or from B, but it is preferable that the number of bonds bonded to L ¹ or L ² is derived from C .

Among the carbene compounds represented by the general formula (1), the carboran compounds represented by the general formula (2) can be mentioned as preferred compounds, and the compounds represented by the general formula (3) or (4) Include carbene compounds represented by the above general formula (3).

Except for ring A in the general formulas (1) to (4), the same symbols and expressions, respectively, are interpreted to have the same meaning unless otherwise specified. Ring A differs in that the meaning in general formula (2) is more limited than in general formula (1).

The carboran compounds represented by the general formulas (1) to (4) can be synthesized by selecting raw materials according to the structure of the object compound and using known methods.

(A-1) can be synthesized by the following reaction formula with reference to the synthesis example shown in Journal of Organometallic Chemistry, 1993, 462, p19-29.

(A-2) can be synthesized by the following reaction formula with reference to the synthesis example shown in Journal of Organic Chemistry, 2007, 72, p6241-6246.

(A-3) can be synthesized by the following reaction scheme with reference to the synthesis example shown in European Journal of Inorganic Chemistry, 2010, p2012-2024 and Inorganic Chemistry, 1995, 34, p2095-2100.

(A-4) can be synthesized by the following reaction formula with reference to the synthesis example shown in Inorganica Chimica Acta, 1995, 240, p371-378.

Specific examples of the carbene compounds represented by the general formulas (1) to (4) are shown below, but the material for the organic electroluminescence device of the present invention is not limited thereto.

The material for an organic electroluminescence device of the present invention is contained in at least one organic layer of an organic EL element in which a positive electrode, a plurality of organic layers and a negative electrode are laminated on a substrate, thereby giving an excellent organic electroluminescence element. As the organic layer to be contained, a light emitting layer, an electron transporting layer or a hole blocking layer is suitable. When it is used in the light emitting layer, it can be used as a host material of a light emitting layer containing fluorescent dopant, delayed fluorescence light emitting or phosphorescent dopant, and the compound of the present invention can be used as an organic light emitting material for emitting fluorescence and delayed fluorescence . When used as an organic light emitting material that emits fluorescence and retardation fluorescence, it is preferable to use another organic compound having at least one of excited triplet energy and excited triplet energy higher than the compound of the present invention as a host material. It is particularly preferable that the compound of the present invention is contained as a host material of a light emitting layer containing a phosphorescent dopant.

Next, an organic EL device using the material for an organic electroluminescence device 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 stacked on a substrate, and at least one organic layer includes the material for an organic electroluminescence device of the present invention. The material for the organic electroluminescence device of the present invention is advantageously included in the light emitting layer together with the phosphorescent dopant.

Next, the structure of the organic EL device of the present invention will be described with reference to the drawings, but the structure of the organic EL device of the present invention is not limited to the drawings.

1 is a cross-sectional view showing an example of the structure of a general organic EL element used in the present invention, wherein 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transporting layer, 5 is a light emitting layer, 6 is an electron transporting layer, Respectively. In the organic EL device of the present invention, an exciton blocking layer may be provided adjacent to the light emitting layer, and an electron blocking layer may be provided between the light emitting layer and the hole injection layer. The exciton-blocking layer can be inserted into both the anode side and the cathode side of the light-emitting layer, and both of them can be inserted at the same time. In the organic EL device of the present invention, a substrate, an anode, a luminescent layer, and a cathode are essential layers, but it is preferable that the layer includes a hole injecting and transporting layer and an electron injecting and transporting layer in layers other than the essential layer. . On the other hand, the hole injecting and transporting layer means either or both of the hole injecting layer and the hole transporting layer, and the electron injecting and transporting layer means either or both of the electron injecting layer and the electron transporting layer.

The cathode 7, the electron transport layer 6, the light emitting layer 5, the hole transport layer 4 and the anode 2 can be stacked in this order on the substrate 1, In this case, it is also possible to add or omit layers as required.

-Board-

The organic EL device of the present invention is preferably supported on a substrate. The substrate is not particularly limited and may be any material conventionally used in organic EL devices. For example, glass, transparent plastic, quartz, or the like may be used.

-anode-

As the anode in the organic EL device, it is preferable to use an electrode material having a large work function (4 eV or more), an alloy, an electrically conductive compound, or a mixture thereof. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, a material capable of forming a transparent conductive film with an amorphous state, such as IDIXO (In ₂ O ₃ -ZnO), may be used. The anode may be formed by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering and then forming a pattern of a desired shape by a photolithography method or if the pattern precision is not required to be small ), A pattern may be formed through a mask having a desired shape at the time of depositing or sputtering the electrode material. Or a material capable of being applied, such as an organic conductive compound, may be used, a wet film formation method such as a printing method, a coating method, or the like may be used. When light emission is extracted from this anode, the transmittance is preferably set to be larger than 10%, and the sheet resistance of the anode is preferably several hundreds? /? Or less. Though the film thickness varies depending 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 metal having a small work function (4 eV or less) (called an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof is used as an electrode material. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, a magnesium / copper mixture, a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) , A lithium / aluminum mixture, a rare earth metal, and the like. Among them, a mixture of an electron-injecting metal and a second metal, which is a metal having a larger work function value than that of a stable metal, such as a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / Indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like are suitable. The negative electrode can be formed by forming a thin film by a method such as vapor deposition or sputtering. The sheet resistance as a cathode is preferably several hundreds? /? Or less, and the film thickness is usually selected within the range of 10 nm to 5 占 퐉, preferably 50 to 200 nm. Further, if either the anode or the cathode of the organic EL element is transparent or semitransparent in order to transmit the emitted light, the light emission luminance is improved and is advantageous.

A transparent or semitransparent negative electrode can be manufactured by fabricating the above metal with a film thickness of 1 to 20 nm on the negative electrode and then forming a conductive transparent material on the positive electrode as described above. A device having transparency can be manufactured.

- luminescent layer -

The light emitting layer is a layer in which excitons are generated by recombination of holes and electrons injected from the anode and the cathode, respectively, and 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, at least one kind of fluorescent light emitting material may be used singly as the fluorescent light emitting material, but it is preferable that the fluorescent light emitting material is used as a fluorescent light emitting dopant and includes a host material.

As the fluorescent light emitting material in the light emitting layer, a carboran compound represented by the general formula (1) can be used, but since it is known from many patent documents, it can be selected from among them. For example, there can be mentioned a benzoxazole derivative, a benzothiazole derivative, a benzoimidazole derivative, a styrylbenzene derivative, a polyphenyl derivative, a diphenylbutadiene derivative, a tetraphenylbutadiene derivative, a naphthalimide derivative, a coumarin derivative, , Pyridine derivatives, oxadiazole derivatives, oxazine derivatives, aldazine derivatives, pyrrolidine derivatives, cyclopentadiene derivatives, bisstyryl anthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolopyridine derivatives, Various metal complexes represented by metal complexes of 8-quinolinol derivatives, metal complexes of pyromethene derivatives, rare earth complexes and transition metal complexes, and the like, polythiophenes such as polythiophene , Polymer compounds such as polyphenylene and polyphenylene vinylene, organic silane derivatives, and the like. Preferred examples thereof include a condensed aromatic compound, a styryl compound, a diketopyrrolopyrrole compound, an oxazine compound, a pyrromethene metal complex, a transition metal complex and a lanthanoide complex. More preferred examples thereof include naphthacene, pyrene, A] anthracene, pentacene, perylene, fluoranthene, acenaphthofluoranthene, dibenzo [a, j] anthracene, dibenzo [a , h] anthracene, benzo [a] naphthacene, hexacene, anthanthrene, naphtho [2,1-f] isoquinoline,? -naphthaphenanthridine, phenanthroxazole, quinolino [ ] Quinoline, benzothiophenthrene, 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, a carboran compound represented by the general formula (1) can be used, but since it is known as a large number of patent documents, it can be selected from among them. Examples of the compound having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, Aromatic amine derivatives such as dinaphthyl-N, N'-diphenyl-4,4'-diphenyl-1,1'-diamine, metal chelates including tris (8-quinolinato) aluminum (III) A chelated oxinoid compound, a bisstyryl derivative such as a distyrylbenzene derivative, a tetraphenylbutadiene derivative, an indene derivative, a coumarin derivative, an oxadiazole derivative, a pyrrolopyridine derivative, a perinone derivative, a cyclopentadiene derivative, A thiadiazole derivative, a thiadiazole derivative, a thiadiazole derivative, a thiadiazole derivative, a thiadiazolopyridine derivative, a dibenzofuran derivative, a carbazole derivative, an indolocarbazole derivative, a triazine derivative, Polyvinyl Le carbazole, but it can use the derivatives, and polythiophene derivatives, and are not particularly limited.

When the fluorescent light-emitting material is used as a fluorescent light-emitting dopant and includes a host material, the amount of the fluorescent light-emitting dopant contained in the light-emitting layer is preferably in the range of 0.01 to 20 wt%, more preferably 0.1 to 10 wt%.

Generally, an organic EL element injects a charge from a positive electrode and a negative electrode into a light emitting material, and generates a light emitting material in an excited state to emit light. In the case of the charge injecting type organic EL device, it is known that excited excitons are excited to singlet excited states by 25% and the remaining 75% excited by triplet excited states. As shown in Advanced Materials 2009, 21, 4802-4806., A specific fluorescent light-emitting material is energetically transferred to a triplet excited state by inter- It is known that fluorescent light is emitted by crossing the opposite term to the singlet excited state due to absorption, and it expresses a thermally activated delayed fluorescence. The organic EL device of the present invention can also exhibit delayed fluorescence. In this case, it may include both fluorescence emission and retardation fluorescence emission. However, light emission from the host material may be partly or partially emitted.

When the light-emitting layer is a retardation light-emitting layer, at least one retardation light-emitting material may be used alone, but it is preferable that the retardation light-emitting material is used as a retardation light-emitting dopant and includes a host material.

As the retarded fluorescent light emitting material in the light emitting layer, a carboran compound represented by the general formula (1) may be used, but it may be selected from known retarded fluorescent light emitting materials. Examples thereof include tin complexes, indolocarbazole derivatives, copper complexes, and carbazole derivatives. Specifically, the compounds described in the following Non-Patent Documents and Patent Documents can be mentioned, but the present invention is not limited to these compounds.

1) Adv. Mater. 2009, 21, 4802-4806, 2) Appl. Phys. Lett. 98, 083302 (2011), 3) JP-A-2011-213643, 4) J. Am. Chem. Soc. 2012, 134, 14706-14709.

Specific examples of the retardation luminescent material are shown, but the present invention is not limited to the following compounds.

When the delayed fluorescent light emitting material is used as a retardation fluorescent light emitting dopant and the host material is included, the amount of retarded fluorescent light emitting dopant contained in the light emitting layer is 0.01 to 50% by weight, preferably 0.1 to 20% by weight, more preferably 0.01 To 10%.

As the retarded fluorescent host material in the light emitting layer, a carboran compound represented by the general formula (1) may be used, but it may be selected from compounds other than carboran. Examples of the compound having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, Aromatic amine derivatives such as dinaphthyl-N, N'-diphenyl-4,4'-diphenyl-1,1'-diamine, metal chelates including tris (8-quinolinato) aluminum (III) A bispyridine derivative, a bisphenol derivative, a bisphenol derivative, a bisphenol derivative, a bisphenol derivative, a bisphenol derivative, a bisphenol derivative, a bisphenol derivative, , Thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, polymeric polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives A polythiophene derivative, an arylsilane derivative, and the like can be used, but it is not particularly limited.

When the light emitting layer is a phosphorescent light emitting layer, the light emitting layer includes a phosphorescent 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. Specifically, the compounds described in the following Patent Literature can be mentioned, but they are not limited to these compounds.

WO2009 / 073245, WO2009 / 046266, WO2007 / 095118, WO2008 / 156879, WO2008 / 140657, US2008 / 261076, etc.

Preferred phosphorescent dopants, can be given a complex retention, such as Ir (ppy) ₃ having a noble metal element such as Ir as a center metal, Ir (bt) ₂ · mounting stay in such acac _3, PtOEt ₃ including mounting stay. Specific examples of such complex flows are shown below, but are not limited to the following compounds.

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

When the light emitting layer is a phosphorescent light emitting layer, it is preferable to use the carboran compound represented by the above general formula (1) according to the present invention as the host material in the light emitting layer. However, when the carboran compound is used for 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 carboran compound. Carbonyl compounds and other host materials may also be used in combination. A plurality of known host materials may be used in combination.

A known host compound which can be used is preferably a compound having a hole transporting ability and an electron transporting ability while preventing a long wavelength of luminescence and further having a high glass transition temperature.

These other host materials are known from a number of patent documents and so can be selected from them. Specific examples of the host material include, but not limited to, indole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenyl There can be mentioned a compound represented by the general formula (1) or a salt thereof, such as a diamine derivative, an arylamine derivative, an amino substituted chalcone derivative, a styrylanthracene derivative, a fluorenone derivative, a hydrazone derivative, a stilbene derivative, a silazane derivative, an aromatic tertiary amine compound, , Porphyrin compounds, anthraquinodimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, heterocyclic tetracarboxylic acid anhydrides such as naphthalene perylene, phthalocyanine derivatives, metal complexes of 8-quinolinol derivatives Metal phthalocyanine, benzoxazole or a benzothiazole derivative (N-vinylcarbazole) derivatives, aniline-based copolymers, thiophene oligomers, polythiophene derivatives, polyphenylene derivatives, polyphenylene vinylene derivatives, polyphenylenevinylene derivatives, And polymer compounds such as polyfluorene derivatives.

The light-emitting layer may be either a fluorescent light-emitting layer, a retardation fluorescent light-emitting layer, or a phosphorescent light-emitting layer, but is preferably a phosphorescent light-emitting layer.

- injection layer -

The injection layer is a layer provided between the electrode and the organic layer for the purpose of lowering the driving voltage or improving the light emission luminance and includes a hole injection layer and an electron injection layer and exists between the anode and the light emitting layer or the hole transporting layer and between the cathode and the light emitting layer or electron transporting layer . The injection layer can be provided as needed.

- Hole blocking layer -

The hole blocking layer is composed of a hole blocking material having a function of an electron transporting layer in a broad sense, a function of transporting electrons and a capability of transporting holes, and transporting electrons and blocking holes, It is possible to improve the recombination probability.

It is preferable to use the carbene compound represented by the formula (1) according to the present invention in the hole blocking layer, but in the case of using the carboran compound in any other organic layer, a well-known hole blocking layer material may be used. As the hole blocking layer material, a material of an electron transporting layer described later can be used as needed.

- Electronic stop layer -

The electron blocking layer is made of a material having a function of transporting holes and having a remarkably small capacity to transport electrons, and it is possible to improve the probability that electrons and holes recombine by transporting holes and blocking electrons.

As the material of the electron blocking layer, materials of the hole transporting layer described later can be used as needed. The film thickness of the electron blocking layer is preferably 3 to 100 nm, more preferably 5 to 30 nm.

- The exciting jersey floor -

The exciton retardation layer is a layer for preventing excitons generated by the recombination of holes and electrons in the light emitting layer from diffusing into the charge transport layer. It is possible to efficiently trap excitons in the light emitting layer by inserting this layer, The efficiency can be improved. The exciton-blocking layer can be inserted into both the anode side and the cathode side adjacent to the light-emitting layer, and both the layers can be inserted at the same time.

As the material of the exciton retardation layer, a carboran compound represented by the general formula (1) can be used, but other materials such as 1,3-dicarbazolylbenzene (mCP), bis (2-methyl- Quinolinolato) -4-phenylphenolatoaluminum (III) (BAlq).

- Hole transport layer -

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

As the hole transporting material, either hole injection or transport, or electron barrier property, either organic or inorganic, may be used. As a known hole transporting material that can be used, it is preferable to use a carbene compound represented by the general formula (1), but it can be arbitrarily selected from conventionally known compounds. Examples of known hole transporting materials which can be used include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino There may be mentioned a conductive polymer oligomer, particularly, a thiophene oligomer, and the like. However, a porphyrin compound such as a porphyrin compound, a styryl anthracene derivative, a fluorenone derivative, a hydrazone derivative, a stilbene derivative, a silazane derivative, , An aromatic tertiary amine compound and a styrylamine compound are preferably used, and it is more preferable to use an aromatic tertiary amine compound.

- Electron transport layer -

The electron transporting layer is made of a material having a function of transporting electrons, and the electron transporting layer may be a single layer or a plurality of layers.

The electron transporting material (which may also serve as a hole blocking material) may have a function of transferring electrons injected from the cathode to the light emitting layer. The electron transporting layer is preferably a carbene derivative represented by the general formula (1) according to the present invention. However, it can be selected from among conventionally known compounds, and examples thereof include nitro-substituted fluorene derivatives, diphenylquinone derivatives , Thiopyran dioxide derivatives, carbodiimides, fluorenylidene methane derivatives, anthraquinodimethane and anthrone derivatives, and oxadiazole derivatives. Also, thiadiazole derivatives in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom in the oxadiazole derivative, and quinoxaline derivatives having a quinoxaline ring, which is known as an electron-withdrawing group, can also be used as an electron transporting material. In addition, such a material may be introduced into the polymer chain, or a polymer material having such a material as a main chain of the polymer may be used.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is of course not limited to these Examples, and can be carried out in various forms without departing from the gist thereof.

Also, the value of T1 energy as used herein is a value obtained by using Gaussian 09, a molecular calculation software product of Gaussian, USA, and is a value calculated by structural optimization calculation of B3LYP / 6-31G * level.

A carboran compound serving as a material for an organic electroluminescence device was synthesized by the route shown below. The compound number corresponds to the number attached to the above formula.

Example 1

Compound 1 is synthesized according to the following scheme.

In a nitrogen atmosphere, 6.92 g (0.0480 mol) of m-carboran and 183 mL of 1,2-dimethoxyethane (DME) were added, and the DME solution was cooled to 0 占 폚. 61.1 mL of 1.65 M n-butyllithium hexane solution was added dropwise, and the mixture was stirred at room temperature for 15 minutes. 9.5 g (0.0960 mol) of copper (I) chloride was added and stirred at room temperature for 15 minutes, and then 28.7 mL of pyridine was added. After stirring at room temperature for 5 minutes, 28.5 g (0.101 mol) of p-bromoiodobenzene was added, and the mixture was stirred at 95 DEG C overnight. Dichloromethane (500 mL) and 1N hydrochloric acid (500 mL) were added to the reaction solution with stirring, and the organic layer was washed with distilled water (3 x 500 mL). The organic layer was dried over anhydrous magnesium sulfate, and then 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 13.7 g (30.2 mmol, yield 63%) of Intermediate A.

8.6 g (0.0189 mol) of Intermediate A, 17 mL of tetrahydrofuran (THF) and 60 mL of diethyl ether were dissolved in a nitrogen atmosphere and cooled to -30 캜. Thereafter, 25 mL of 1.65 M n-butyllithium hexane solution was added dropwise, and the mixture was stirred at room temperature for 1 hour. 11.6 g (0.0393 mol) of triphenylchlorosilane dissolved in 34 ml of THF and 24 ml of diethyl ether was added dropwise to the obtained white solution. Then, the mixture was stirred overnight while being slowly warmed to room temperature, and dichloromethane (300 mL) and 1N hydrochloric acid (200 mL) were added to the reaction solution with stirring, and the organic layer was washed with distilled water (3 x 500 mL). The organic layer was dried over anhydrous magnesium sulfate, and then magnesium sulfate was filtered off and the solvent was distilled off under reduced pressure. The obtained residue was purified by crystallization to obtain 3.56 g (4.38 mmol, yield: 23%) of Compound 1 as a white solid. FD-MS, m / z 813 [M] ⁺ , and ¹ H-NMR measurement results (measurement solvent: CDCl ₃ ) are shown in FIG.

Example 2

Compound 4 is synthesized according to the following scheme.

63.6 g (0.268 mol) of 2,6-dibromopyridine and 1080 mL of THF were added in a nitrogen atmosphere, and the mixture was cooled to -50 占 폚. Thereafter, a 2.69 M n-butyllithium hexane solution was added dropwise, and the mixture was stirred at -50 캜 for 2 hours. To the resulting black solution was added dropwise 78.4 g (0.266 mol) of triphenylchlorosilane dissolved in 240 ml of THF and 160 ml of diethyl ether. Then, the mixture was stirred overnight while slowly raising the temperature to room temperature. Ethyl acetate (1000 mL) and 1N hydrochloric acid (1000 mL) were added to the reaction solution with stirring, and the organic layer was washed with distilled water (3 x 500 mL). The organic layer was dried over anhydrous magnesium sulfate, and then 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 18.5 g (44.4 mmol, yield: 17%) of Intermediate B as a white solid.

Under nitrogen atmosphere, 2.6 g (0.0185 mol) of m-carboran and 80 mL of 1,2-dimethoxyethane (DME) were added and the mixture was stirred at room temperature for 5 minutes. 27.4 mL of 1.59 M n-butyllithium hexane solution was added dropwise, and the mixture was stirred at room temperature for 5 minutes. Thereafter, 11 mL of pyridine and 5.9 g (0.0592 mol) of copper (I) chloride were added and the mixture was stirred at 60 ° C for 1 hour. 17.0 g (0.0408 mol) of Intermediate B dissolved in 40 mL of DME was added dropwise to the resulting black solution, and the mixture was stirred at 90 캜 overnight. Dichloromethane (500 mL) and 1N hydrochloric acid (500 mL) were added to the reaction solution with stirring, and the organic layer was washed with distilled water (3 x 500 mL). The organic layer was dried over anhydrous magnesium sulfate, and then magnesium sulfate was filtered off and the solvent was distilled off under reduced pressure. The obtained residue was purified by crystallization and silica gel column chromatography to obtain 1.9 g (2.33 mmol, 13% yield) of Compound 4. [ 3 shows the results of APCI-TOFMS, m / z 816 [M + H] ⁺ , and ¹ H-NMR measurement (measurement solvent: CDCl ₃ ).

Reference Example 1

Table 1 shows the results of calculating the T1 energy of the carbene compound using Gaussian09.

The chemical formulas of the compounds H-1 to H-3 for comparison are shown below.

In Table 1, it was confirmed that the T1 energy value was increased by bonding a silyl group to the carboran skeleton through an aromatic hydrocarbon group or an aromatic heterocyclic group.

Organic EL devices were also produced using the compounds 1, 2, 4, 5, 6, 8, 13, 32 and H-1, H-2 and H-3.

Example 3

Each thin film was laminated with a vacuum degree of 2.0 x 10 < ^-5 > Pa on a glass substrate on which an anode made of indium tin oxide (ITO) with a film thickness of 70 nm was formed. First, copper phthalocyanine (CuPC) was formed as a hole injection layer on ITO to a thickness of 30 nm. Next, N, N'-di (1-naphthyl) -N, N'-diphenylbenzidine (? -NPD) was formed to a thickness of 15 nm as a hole transporting layer. Next, a compound 1 as a host material of the light emitting layer and an iridium complex [iridium (III) bis [(4,6-di-fluorophenyl) -pyridinate-N, C2 '] which is a blue phosphorescent material of a dopant) Picolinate] (FIrpic) was co-deposited from another evaporation source to form a light emitting layer with a thickness of 30 nm. The concentration of FIrpic was 10%. Next, Alq ₃ was formed by 25㎚ thickness as the electron transporting layer. Further, lithium fluoride (LiF) was formed as an electron injection layer to a thickness of 1.0 nm on the electron transporting layer. Finally, aluminum (Al) was formed as an electrode on the electron injection layer to a thickness of 70 nm. The resulting organic EL device had a layer structure in which an electron injection layer was added between the cathode and the electron transport layer in the organic EL device shown in Fig.

The obtained organic EL device was connected to an external power supply, and a direct current voltage was applied. As a result, it was confirmed that the organic EL device had luminescence characteristics as shown in Table 2. In Table 2, the luminance, voltage and luminous efficiency exhibit a value (initial characteristic) of 2.5 mA / cm 2. It was also found that the maximum wavelength of the element luminescence spectrum was 475 nm and light emission from FIrpic was obtained.

Examples 4 to 9

An organic EL device was prepared in the same manner as in Example 3 except that the compounds 2, 4, 5, 6, 8, and 32 were used instead of the compound 1 as the host material of the light emitting layer in Example 3.

Comparative Example 1

An organic EL device was fabricated in the same manner as in Example 3 except that mCP was used as the host material of the light emitting layer in Example 3.

Comparative Examples 2 to 4

An organic EL device was prepared in the same manner as in Example 3 except that the compound H-1, H-2 or H-3 was used as the host material of the light emitting layer in Example 3.

The organic EL devices obtained in Examples 4 to 9 and Comparative Examples 1 to 4 were evaluated in the same manner as in Example 3, and as a result, it was confirmed that the organic EL devices had the luminescence properties as shown in Table 2. It was also confirmed that the maximum wavelength of the luminescence spectrum of the organic EL devices obtained in Examples 4 to 9 and Comparative Examples 1 to 4 was 475 nm and light emission from FIrpic was obtained.

In Table 2, when the carboran compounds of the present invention were used in the light emitting layers in Examples 3 to 9, the light emitting efficiency showed better characteristics than those of Comparative Examples 1 to 4.

Example 10

Each thin film was laminated by a vacuum deposition method at a degree of vacuum of 2.0 x 10 < ^-5 > Pa on a glass substrate on which a positive electrode made of ITO having a thickness of 70 nm was formed. First, CuPC was formed as a hole injection layer on ITO to a thickness of 30 nm. Next,? -NPD was formed to a thickness of 15 nm as a hole transporting layer. Next, Compound 1 as a host material of the light emitting layer and Ir (ppy) ₃ as a dopant were co-deposited on the hole transport layer from another evaporation source to form a light emitting layer with a thickness of 30 nm. The concentration of Ir (ppy) ₃ was 10%. Next, Alq ₃ was formed as the electron transporting layer to a thickness of 25㎚. Further, LiF as an electron injecting layer was formed on the electron transporting layer to a thickness of 1 nm. Finally, Al was formed as an electrode on the electron injection layer to a thickness of 70 nm to prepare an organic EL device.

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

Examples 11 to 17

An organic EL device was prepared in the same manner as in Example 10 except that the compounds 2, 4, 5, 6, 8, 13, and 32 were used instead of the compound 1 as the host material of the light emitting layer in Example 10.

Comparative Examples 5 to 8

An organic EL device was prepared in the same manner as in Example 10 except that CBP, H-1, H-2 or H-3 was used as the host material of the light emitting layer in Example 10.

The organic EL devices obtained in Examples 11 to 17 and Comparative Examples 5 to 8 were evaluated in the same manner as in Example 10. As a result, it was confirmed that the organic EL devices had the luminescence properties as shown in Table 3. It was also confirmed that the maximum wavelength of the luminescence spectrum of the organic EL devices obtained in Examples 11 to 17 and Comparative Examples 5 to 8 was 530 nm and light emission from Ir (ppy) ₃ was obtained.

In Table 3, when the carboran compound of the present invention was used in the light emitting layer (Examples 10 to 17), good light emission efficiency was shown compared with the other cases (Comparative Examples 5 to 8).

Example 18

Each thin film was laminated with a vacuum degree of 2.0 x 10 < ^-5 > Pa by vacuum evaporation on a glass substrate on which an anode made of ITO having a thickness of 70 nm was formed. First, CuPC was formed as a hole injection layer on ITO to a thickness of 30 nm. Next,? -NPD was formed to a thickness of 15 nm as a hole transporting layer. Next, CBP and Ir (ppy) ₃ as a host material of the light emitting layer and Ir (ppy) ₃ as a dopant were deposited on the hole transport layer from other evaporation sources to form a light emitting layer with a thickness of 30 nm. The concentration of Ir (ppy) ₃ was 10%. Next, Compound 1 as a hole blocking layer was formed on the light emitting layer to a thickness of 5 nm. Next, to form an Alq ₃ as the electron transporting layer to a thickness 20㎚. Further, LiF as an electron injection layer was formed to a thickness of 1.0 nm on the electron transporting layer. Finally, Al was formed as an electrode on the electron injection layer to a thickness of 70 nm. The resulting organic EL device had a layer structure in which an electron injection layer was provided between the cathode and the electron transport layer in the organic EL device shown in Fig. 1, and a hole blocking layer was added between the luminescent layer and the electron transport layer.

The obtained organic EL device was connected to an external power source and a direct current voltage was applied. As a result, it was confirmed that the organic EL device had luminescence characteristics as shown in Table 4. [ In Table 4, the luminance, voltage and luminous efficiency show values (initial characteristics) at the time of driving at 20 mA / cm 2. It was found that the maximum wavelength of the element luminescence spectrum was 530 nm, and light emission from Ir (ppy) ₃ was obtained.

Examples 19-25

An organic EL device was fabricated in the same manner as in Example 18 except that the compounds 2, 4, 5, 6, 8, 13, and 32 were used instead of the compound 1 as the hole blocking material in Example 18.

Comparative Example 9

An organic EL device was prepared in the same manner as in Example 18 except that Alq ₃ as the electron transporting layer in Example 18 had a thickness of 25 nm and the hole blocking layer was not provided.

Comparative Examples 10 to 12

An organic EL device was prepared in the same manner as in Example 18 except that the compound H-1, H-2 or H-3 was used as the hole blocking material in Example 18.

The organic EL devices obtained in Examples 19 to 25 and Comparative Examples 9 to 12 were evaluated in the same manner as in Example 18. As a result, it was confirmed that the organic EL devices had the luminescence properties as shown in Table 4. It was also confirmed that the maximum wavelength of the luminescence spectrum of the organic EL devices obtained in Examples 19 to 25 and Comparative Examples 9 to 12 was 530 nm and light emission from Ir (ppy) ₃ was obtained. The host materials of the light emitting layers used in Examples 19 to 25 and Comparative Examples 9 to 12 were all CBP.

In Table 4, the initial characteristics were improved in all systems except for Comparative Example 9 (when the hole blocking material was not used). In particular, when the carbazole compound of the present invention is used in the hole blocking layer, it exhibits better characteristics than the other cases (Comparative Examples 10 to 12).

The organic EL device according to the present invention is a level that can be practically satisfactory in terms of light emission characteristics, driving life and durability, and can be used as a flat panel display (cellular phone display device, vehicle display device, OA computer display device, (Light source of a light source, a light source of a copying machine, a backlight light source of a liquid crystal display or a meter), a signboard, a cover, and the like.

Claims (9)

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

The ring A represents a tetravalent carbazole group of C ₂ B ₁₀ H ₈ represented by any one of the formulas (1a) and (1b), and may be the same or different when a plurality of ring A is present in the molecule. L ¹ is a group of p + 1, L ² is a group of q + 1, L ¹ and L ² each independently represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted 3-carbon group Or an aromatic heterocyclic group having 1 to 30 carbon atoms or an aromatic heterocyclic group and the aromatic heterocyclic group, and the connecting aromatic group may be linear or branched, The orientation rings may be the same or different. R ¹ , R ² , R ³ , R ⁴ , R ⁵ and 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 carbon number R ⁷ and R ⁸ independently represent 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 number Represents an aromatic heterocyclic group having 3 to 17 carbon atoms. p represents an integer of 1 to 5, q represents an integer of 0 to 5, and r represents an integer of 1 to 4. The method according to claim 1,
Wherein the carboran compound is a carbene compound represented by the general formula (2)

Here, L ¹ , L ² , R ¹ to R ⁸ , p, q and r have the same meanings as in formula (1). Ring A represents a tetravalent carbazole group of C ₂ B ₁₀ H ₈ represented by any one of the formulas (2a) and (2b), and may be the same or different when a plurality of ring A is present in the molecule. The method according to claim 1,
Wherein the carboran compound is a carbene compound represented by the general formula (3) or (4).

Here, L ¹ , L ² , R ¹ to R ⁸ , p, q and r have the same meanings as in formula (1). The method of claim 3,
In the general formula (3) or (4), L ¹ and L ² each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, A heterocyclic group, and an aromatic heterocyclic group, wherein the aromatic group is formed by connecting 2 to 5 aromatic groups. The method of claim 3,
In the general formula (3) or (4), R ¹ to R ⁶ are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms. An organic electroluminescent device comprising an organic electroluminescent device comprising an anode, an organic layer and a cathode stacked on a substrate, wherein the organic electroluminescent device has an organic layer comprising the material for an organic electroluminescent device according to any one of claims 1 to 5. The method according to claim 6,
Wherein the organic layer including the material for the organic electroluminescence device is at least one layer selected from the group consisting of a light emitting layer, an electron transporting layer and a hole blocking layer. 8. The method of claim 7,
Wherein the organic layer comprising the material for the organic electroluminescence element is a light emitting layer containing a phosphorescent luminescent dopant. 9. The method of claim 8,
Wherein the phosphorescent luminescent dopant has an emission maximum wavelength of 550 nm or less.

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