JP2015207657A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescence-type, delayed fluorescence-type or phosphorescence-type organic EL element, high in efficiency and high in drive stability while low in voltage, and excellent in life characteristics.SOLUTION: In an organic electroluminescent element including a luminous layer between an anode and a cathode facing each other, the luminous layer contains at least two host materials and at least one luminescent dopants, and a material is used as the host materials, the material including an indolocarbazole compound having one or two indolocarbazole rings and a carborane compound having a carborane ring and a carbazole ring.

Description

  The present invention relates to an organic electroluminescent device (hereinafter referred to as an organic EL device). Specifically, a compound having a specific structure is mixed and used as a host material, so that it is highly efficient while being low in voltage and long. The present invention relates to an organic EL element that can achieve a lifetime.

  In general, the organic EL element has a light emitting layer and a pair of counter electrodes sandwiching the layer as its 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 light is emitted as energy when they are recombined in the light emitting layer. Use the phenomenon.

  In recent years, an organic EL element using an organic thin film has been developed. In particular, in order to increase the luminous efficiency, the type of the electrode is optimized for the purpose of improving the efficiency of carrier injection from the electrode, and 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 that has a light emitting layer and electron transport 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 practical application to high-performance flat panels with features such as high-speed response.

  As an attempt to increase the luminous efficiency of the device, the use of a phosphorescent material instead of a fluorescent material has been studied. Many devices, including devices provided with the hole transport layer composed of the above aromatic diamine and the light emitting layer composed of Alq3, used phosphorescence, but used phosphorescence, that is, triplet. By using the light emission from the excited state, the efficiency is expected to be improved 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 an extremely low luminance was obtained. Thereafter, the use of a europium complex has been studied as an attempt to utilize the triplet state, but this also did not lead to highly efficient light emission. In this research using phosphorescence, many studies have been conducted mainly on organometallic complexes such as iridium complexes listed in Patent Document 1 as phosphorescent dopants. Has been.

WO01 / 041512 A1 WO2008-056746A1 Japanese Unexamined Patent Publication No. 2005-162709 JP 2005-166574 A US2012 / 0319088 A1 WO2013 / 094834 A1 US2009 / 0167162 A1 WO2009-136596 No.A1 WO2010-098246 No.A1

  Patent Document 2 discloses the use of an indolocarbazole compound as a host material. Patent Documents 3 to 7 disclose the use of a carborane compound as a host material. Patent Documents 8 and 9 disclose using an indolocarbazole compound as a mixed host.

  However, there is no teaching that a special effect is manifested by mixing a specific indolocarbazole compound and a carborane compound into a host material.

  In order to apply the organic EL element to a display element such as a flat panel display, it is necessary to improve the luminous efficiency of the element and at the same time sufficiently ensure stability during driving. In view of the above situation, an object of the present invention is to provide a practically useful organic EL device having high efficiency and high driving stability while being low in voltage.

  The present invention provides an organic electroluminescence device comprising one or more light emitting layers between an anode and a cathode facing each other, wherein at least one light emitting layer contains at least two host materials and at least one light emitting dopant, Of the at least two host materials, one is a compound represented by the following general formula (1) or (2), and the other is a compound represented by the following general formula (3) The present invention relates to an organic electroluminescent element.

Here, ring a, ring c, and ring c ′ independently represent an aromatic ring or a heterocyclic ring represented by the formula (a1) that is condensed at two positions with two adjacent rings, and X ¹ represents C—R or N,
Ring b, Ring d, and Ring d ′ each independently represent a heterocyclic ring represented by Formula (b1) that is condensed with two adjacent rings at any position;
Ar ¹ represents an aromatic hydrocarbon group having 6 to 30 carbon atoms or an aromatic heterocyclic group having 3 to 16 carbon atoms,
Z represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, an aromatic heterocyclic group having 3 to 16 carbon atoms, or a linked aromatic group formed by connecting 2 to 10 thereof,
L ¹ independently represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, an aromatic heterocyclic group having 3 to 16 carbon atoms, or a linked aromatic group in which they are linked by 2 to 10;
p independently represents an integer of 0 to 7,
R and R ^{1 to} R ⁷ are independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 38 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, carbon A dialkylamino group having 2 to 40 carbon atoms, a diarylamino group having 12 to 44 carbon atoms, a diaralkylamino group having 14 to 76 carbon atoms, an acyl group having 2 to 20 carbon atoms, an acyloxy group having 2 to 20 carbon atoms, and a carbon number An alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 20 carbon atoms, an alkoxycarbonyloxy group having 2 to 20 carbon atoms, an alkylsulfonyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, Or an aromatic heterocyclic group having 3 to 18 carbon atoms, and when R ¹ , R ² , R ^{4 to} R ⁷ are aromatic hydrocarbon groups having 6 carbon atoms, a condensed aromatic ring and a condensed ring are formed. And Ar ¹ , When Z, L ¹ , R, and R ^{1 to} R ⁷ are an aromatic hydrocarbon group and an aromatic heterocyclic group, they may have a substituent.

Here, ring A independently represents a divalent carborane group of C ₂ B ₁₀ H ₁₀ represented by formula (1a) or formula (1b),
s, t, and u represent the number of substitutions, m represents the number of repetitions, s and t are integers of 0 to 10, u is an integer of 0 to 4, and m is an integer of 0 to 6. However, when u = 1, m is 0 or 1.
L ² , L ³ , and L ^{4 each} independently represent a single bond or an aromatic hydrocarbon group having 6 to 30 carbon atoms, or a linked aromatic group formed by connecting 2 to 6 thereof, provided that L ² , L ³ , and L ⁴ are an s + 1 valent group, a u + 1 valent group, and a t + 1 valent group, respectively, and when L ² , L ³ , or L ⁴ is a divalent group, it is a single bond. You can,
W independently represents N—R ⁸ or N, and when W = N, N is bonded to L ² or L ⁴ , R ⁸ is independently hydrogen, an alkyl group having 1 to 20 carbon atoms, substituted or An unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 16 carbon atoms, or 2 to 6 substituted or unsubstituted aromatic rings connected to each other; The connected aromatic group comprised is shown.

In the general formulas (1) and (2), X ¹ is C—R, or X ¹ is C—R, and at least one of Ar ^{1 in} the general formula (1) or the general formula (2) It is desirable that at least one of Ar ¹ is a substituted or unsubstituted aromatic heterocyclic group having 3 to 16 carbon atoms. Moreover, it is desirable that at least two host materials are a compound represented by the general formula (1) and a compound represented by the general formula (3). Furthermore, it is desirable that the light-emitting dopant is an organometallic complex containing at least one metal selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and gold.

  The organic EL device of the present invention uses a specific compound as a mixed host, so that the lowest excited triplet is sufficiently high to confine the lowest excited triplet energy in the case of a phosphorescent light emitting EL even at a low voltage. Since it has energy, there is no outflow of energy from the inside of the light emitting layer, and high efficiency and long life can be achieved. The organic EL element of the present invention is a flat panel display (cell phone display element, in-vehicle display element, OA computer display element, television, etc.), and a light source (illumination, light source of a copying machine, liquid crystal display) utilizing the characteristics as a surface light emitter. In addition, its technical value is great in applications to backlights for measuring instruments, display boards, indicator lamps, and the like.

It is the schematic cross section which showed an example of the organic EL element.

  The organic electroluminescent device of the present invention includes one or more light-emitting layers between an anode and a cathode facing each other, and at least one light-emitting layer includes at least two host materials and at least one light-emitting dopant. The host material includes a compound represented by the above general formula (1) or (2) and a compound represented by the following general formula (3).

In the above general formulas (1) and (2), ring a, ring c, and ring c ′ are aromatic rings (aromatic hydrocarbon rings, represented by formula (a1)) that are condensed at any positions of two adjacent rings. A heterocyclic ring or both. Here, in the formula (a1), X ¹ represents C—R or N, and is preferably C—R.

  In the above general formulas (1) and (2), ring b, ring d, and ring d ′ represent a heterocyclic ring represented by formula (b1) that is condensed at any position of two adjacent rings. Here, ring c and ring c ', and ring d and ring d' may be the same or different.

  In the compound represented by the general formula (1) or (2), the aromatic ring represented by the formula (a1) can be condensed with two adjacent rings at any position, but cannot be structurally condensed. There is. The aromatic ring represented by the formula (a1) has six sides, but does not condense with two adjacent rings at two adjacent sides. In the general formulas (1) and (2), the heterocyclic ring represented by the formula (b1) can be condensed with two adjacent rings at any position, but there is a position where it cannot be structurally condensed. That is, this heterocyclic ring has five sides, but is not condensed with two adjacent rings at two adjacent sides, and is not condensed with an adjacent ring at a side containing a nitrogen atom. Therefore, the types of isomers of the compounds represented by the general formulas (1) and (2) are limited.

In the above general formulas (1) and (2), Ar ¹ independently represents an aromatic hydrocarbon group having 6 to 30 carbon atoms or an aromatic heterocyclic group having 3 to 16 carbon atoms, preferably 6 carbon atoms. An aromatic hydrocarbon group having 2 to 22 carbon atoms or an aromatic heterocyclic group having 3 to 16 carbon atoms, more preferably an aromatic hydrocarbon group having 6 to 18 carbon atoms or an aromatic heterocyclic group having 3 to 16 carbon atoms. is there. Each of these aromatic hydrocarbon groups or aromatic heterocyclic groups may have a substituent. Ar ¹ is a p + 1 valent group.

Specific examples of Ar ¹ include benzene, pentalene, indene, naphthalene, azulene, heptalene, octalene, indacene, acenaphthylene, phenalene, phenanthrene, anthracene, tridene, fluoranthene, acephenanthrylene, acanthrylene, triphenylene, pyrene, chrysene. , Tetraphen, tetracene, pleiaden, picene, perylene, pentaphen, pentacene, tetraphenylene, cholanthrylene, helicene, hexaphene, rubicene, coronene, trinaphthylene, heptaphene, pyranthrene, furan, benzofuran, isobenzofuran, xanthene, oxatolene, dibenzofuran, peri Xanthenoxanthene, thiophene, thioxanthene, thianthrene, phenoxathiin, thionaphthene, iso Thianaphthene, thiobutene, thiophanthrene, dibenzothiophene, pyrrole, pyrazole, tellurazole, selenazole, thiazole, isothiazole, oxazole, furazane, pyridine, pyrazine, pyrimidine, pyridazine, triazine, indolizine, indole, isoindole, indazole, purine, Quinolidine, isoquinoline, carbazole, imidazole, naphthyridine, phthalazine, quinazoline, benzodiazepine, quinoxaline, cinnoline, quinoline, pteridine, phenanthridine, acridine, perimidine, phenanthroline, phenazine, carboline, phenotelrazine, phenotherazine, phenothiazine, phenoxazine, Lysine, benzothiazole, benzimidazole, benzoxazole Benzisoxazole, or a group resulting from benzisothiazol except p + 1 pieces of hydrogen. Preferred examples include groups formed by removing p + 1 hydrogen from benzene, naphthalene, anthracene, pyridine, pyrazine, pyrimidine, pyridazine, triazine, carbazole, dibenzofuran, dibenzothiophene, quinoline, isoquinoline, quinoxaline, or naphthyridine.

L ¹ each independently represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, an aromatic heterocyclic group having 3 to 16 carbon atoms, or a group formed by connecting 2 to 10 carbon atoms thereof, preferably 6 carbon atoms. An aromatic hydrocarbon group having 18 to 18 carbon atoms, an aromatic heterocyclic group having 3 to 16 carbon atoms, or a linked aromatic group formed by connecting 2 to 7 thereof. These aromatic hydrocarbon groups, aromatic heterocyclic groups, and linked aromatic groups may each have a substituent.

Specific examples of L ¹ include benzene, pentalene, indene, naphthalene, azulene, heptalene, octalene, indacene, acenaphthylene, phenalene, phenanthrene, anthracene, tridene, fluoranthene, acephenanthrylene, acanthrylene, triphenylene, pyrene, chrysene. , Tetraphen, tetracene, pleiaden, picene, perylene, pentaphen, pentacene, tetraphenylene, cholanthrylene, helicene, hexaphene, rubicene, coronene, trinaphthylene, heptaphene, pyranthrene, furan, benzofuran, isobenzofuran, xanthene, oxatolene, dibenzofuran, peri Xanthenoxanthene, thiophene, thioxanthene, thianthrene, phenoxathiin, thionaphthene, isothi Anaphten, thiobutene, thiophantrene, dibenzothiophene, pyrrole, pyrazole, tellurazole, selenazole, thiazole, isothiazole, oxazole, furazane, pyridine, pyrazine, pyrimidine, pyridazine, triazine, indolizine, indole, isoindole, indazole, purine, Quinolidine, isoquinoline, carbazole, imidazole, naphthyridine, phthalazine, quinazoline, benzodiazepine, quinoxaline, cinnoline, quinoline, pteridine, phenanthridine, acridine, perimidine, phenanthroline, phenazine, carboline, phenotelrazine, phenotherazine, phenothiazine, phenoxazine, Lysine, benzothiazole, benzimidazole, benzoxazole, Down zone isoxazole, or benzisothiazole, or aromatic rings of these aromatic compounds include groups formed by removing one hydrogen from a plurality linked aromatics.

  As used herein, a linked aromatic group refers to an aromatic group in which a plurality of aromatic rings of a plurality of aromatic compounds are linked. The linked structure of the linked aromatic group may be linear or branched, and the aromatic rings to be linked may be the same or different, and may have a substituent. The linked aromatic group can be a monovalent or divalent or higher valent group. Examples of the linked aromatic group include linked aromatic groups having a linked structure as shown below.

When the linked aromatic group is a divalent group, a linked aromatic group having a linked structure as shown below is exemplified.

In formula, Ar < ¹¹ > -Ar < ¹⁶ >, Ar < ²¹ > -Ar < ²⁶ > shows a substituted or unsubstituted aromatic ring. The aromatic ring means a ring of an aromatic hydrocarbon compound or an aromatic heterocyclic compound, and can be a monovalent or higher valent group. The term “aromatic rings are linked” means that the aromatic rings are linked by a direct bond. When the aromatic ring is a substituted aromatic ring, the substituent is not an aromatic ring.

  Specific examples of the linked aromatic group include, for example, biphenyl, terphenyl, bipyridine, bipyrimidine, vitriazine, terpyridine, phenylterphenyl, binaphthalene, phenylpyridine, diphenylpyridine, phenylpyrimidine, diphenylpyrimidine, phenyltriazine, diphenyltriazine, phenylnaphthalene. , A group formed by removing hydrogen from diphenylnaphthalene, carbazolylbenzene, biscarbazolylbenzene, biscarbazolyltriazine, dibenzofuranylbenzene, bisdibenzofuranylbenzene, dibenzothiophenylbenzene, bisdibenzothiophenylbenzene, etc. Is mentioned.

  In general formula (2), Z is a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms, an aromatic heterocyclic group having 3 to 16 carbon atoms, or a linked aromatic group formed by connecting them in an amount of 2 to 10 Indicates. Preferably, it is a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, an aromatic heterocyclic group having 3 to 16 carbon atoms, or a linked aromatic group formed by connecting them in 2 to 7, and each aromatic The ring may independently have a substituent.

Specific examples of Z include divalent groups generated by removing two hydrogens from the aromatic compound exemplified in the specific example of L ¹ or a linked aromatic compound in which a plurality of these are linked.

  In general formula (1) and formula (b1), p independently represents an integer of 0 to 7. Preferably it is 0-5, More preferably, it is 0-3.

Ar ¹ , Z, and L ^{1 each} represent an aromatic hydrocarbon group, an aromatic heterocyclic group, or a linked aromatic group to which these are linked, and these groups may have a substituent. In this case, the substituent includes an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 38 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, and an alkyl group having 2 to 40 carbon atoms. Dialkylamino group, diarylamino group having 12 to 44 carbon atoms, diaralkylamino group having 14 to 76 carbon atoms, acyl group having 2 to 20 carbon atoms, acyloxy group having 2 to 20 carbon atoms, alkoxy having 1 to 20 carbon atoms Group, an alkoxycarbonyl group having 2 to 20 carbon atoms, an alkoxycarbonyloxy group having 2 to 20 carbon atoms, or an alkylsulfonyl group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 10 carbon atoms, carbon It is an aralkyl group having 7 to 24 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a diarylamino group having 12 to 36 carbon atoms. In addition, the number of substituents is 0-5, Preferably it is 0-2.

  Specific examples of the substituent include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, phenyl Methyl, phenylethyl, phenylicosyl, naphthylmethyl, anthranylmethyl, phenanthrenylmethyl, pyrenylmethyl, vinyl, propenyl, butenyl, pentenyl, decenyl, icocenyl, ethynyl, propargyl, butynyl, pentynyl, decynyl, icosinyl, dimethylamino, Ethylmethylamino, diethylamino, dipropylamino, dibutylamino, dipentynylamino, didecylamino, diicosylamino, diphenylamino, naphthy Phenylamino, dinaphthylamino, dianthranylamino, diphenanthrenylamino, dipyrenylamino, diphenylmethylamino, diphenylethylamino, phenylmethylphenylethylamino, dinaphthylmethylamino, dianthranylmethylamino, diphenanthrenylmethyl Amino, acetyl, propionyl, butyryl, valeryl, benzoyl, acetyloxy, propionyloxy, butyryloxy, valeryloxy, benzoyloxy, methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonyloxy, deoxy, undecyloxy, dodecoxy , Trideoxy, tetradeoxy, pentadeoxy, hexadeoxy, heptadetoxy, octadeoxy, nonadetoxy, ico Si, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonyloxy, ethoxycarbonyloxy, propoxycarbonyloxy, butoxycarbonyloxy, pentoxycarbonyloxy, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl , Pentylsulfonyl and the like. Preferably, a C1-12 alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenylmethyl, phenylethyl, naphthylmethyl, anthranylmethyl, phenanthrenylmethyl, pyrenylmethyl C7-20 aralkyl groups such as methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonyloxy, deoxy and the like C1-10 alkoxy groups, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthranyl And diarylamino groups having two C6-15 aromatic hydrocarbon groups such as amino and diphenanthrenylamino.

In general formula (1), formula (a1), and general formula (2), R and R ^{1 to} R ⁷ are independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 38 carbon atoms, carbon Alkenyl group having 2 to 20 carbon atoms, alkynyl group having 2 to 20 carbon atoms, dialkylamino group having 2 to 40 carbon atoms, diarylamino group having 12 to 44 carbon atoms, diaralkylamino group having 14 to 76 carbon atoms, carbon number An acyl group having 2 to 20 carbon atoms, an acyloxy group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 20 carbon atoms, an alkoxycarbonyloxy group having 2 to 20 carbon atoms, and 1 to 1 carbon atom 20 alkylsulfonyl groups, aromatic hydrocarbon groups having 6 to 30 carbon atoms or aromatic heterocyclic groups having 3 to 18 carbon atoms, preferably hydrogen, alkyl groups having 1 to 10 carbon atoms, and 7 to 7 carbon atoms. 24 ara A kill group, an alkoxy group having 1 to 10 carbon atoms, a diarylamino group having 12 to 36 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms or an aromatic heterocyclic group having 3 to 16 carbon atoms, and more preferably. Is hydrogen, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or an aromatic heterocyclic group having 3 to 16 carbon atoms. In addition, when it is groups other than hydrogen, each group may have a substituent. Moreover, when R < ¹ > -R < ² > and R < ⁴ > -R < ⁷ > are phenyl groups, you may form the aromatic ring and condensed ring to substitute.

  An alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 38 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, a dialkylamino group having 2 to 40 carbon atoms, and 12 to 12 carbon atoms 44 diarylamino groups, C14-76 diaralkylamino groups, C2-20 acyl groups, C2-20 acyloxy groups, C1-20 alkoxy groups, C2-20 carbon atoms Specific examples of the alkoxycarbonyl group, the alkoxycarbonyloxy group having 2 to 20 carbon atoms, and the alkylsulfonyl group having 1 to 20 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, Undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, Cosyl, phenylmethyl, phenylethyl, phenylicosyl, naphthylmethyl, anthranylmethyl, phenanthrenylmethyl, pyrenylmethyl, vinyl, propenyl, butenyl, pentenyl, decenyl, icocenyl, ethynyl, propargyl, butynyl, pentynyl, decynyl, icosinyl, Dimethylamino, ethylmethylamino, diethylamino, dipropylamino, dibutylamino, dipentynylamino, didecylamino, diicosylamino, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthranylamino, diphenanthrenylamino, dipyrenylamino, diphenyl Methylamino, diphenylethylamino, phenylmethylphenylethylamino, dinaphthylmethylamino, dianthranylmethylamino , Diphenanthrenylmethylamino, acetyl, propionyl, butyryl, valeryl, benzoyl, acetyloxy, propionyloxy, butyryloxy, valeryloxy, benzoyloxy, methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonyloxy, Detoxyl, undecyloxy, dodeoxy, trideoxy, tetradeoxy, pentadeoxy, hexadeoxy, heptadetoxy, octadeoxy, nonadetoxy, icosoxy, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonyloxy, ethoxycarbonyloxy, propoxycarbonyl Oxy, butoxycarbonyloxy, pentoxycarbonyl Examples include oxy, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl and the like. Preferably, an alkyl group having 1 to 10 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenylmethyl, phenylethyl, naphthylmethyl, anthranylmethyl, phenanthrenylmethyl , Aralkyl groups having 7 to 17 carbon atoms such as pyrenylmethyl, alkoxy groups having 1 to 10 carbon atoms such as methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonyloxy, deoxy, diphenylamino, naphthylphenylamino, Examples thereof include diarylamino groups having 12 to 28 carbon atoms such as dinaphthylamino, dianthranylamino, diphenanthrenylamino and the like.

  Specific examples in the case of an aromatic hydrocarbon group having 6 to 30 carbon atoms or an aromatic heterocyclic group having 3 to 18 carbon atoms include benzene, pentalene, indene, naphthalene, azulene, indacene, acenaphthylene, phenalene, phenanthrene, Anthracene, tridene, fluoranthene, acephenanthrylene, acanthrylene, triphenylene, pyrene, chrysene, tetraphen, tetracene, pleiaden, picene, perylene, pentaphen, pentacene, tetraphenylene, cholanthrylene, furan, benzofuran, isobenzofuran, xanthene , Oxatrene, dibenzofuran, perixanthenoxanthene, thiophene, thioxanthene, thianthrene, phenoxathiin, thionaphthene, isothianaphthene, thiobutene, thiophanthrene , Dibenzothiophene, pyrrole, pyrazole, tellurazole, selenazole, thiazole, isothiazole, oxazole, furazane, thiadiazole, pyridine, pyrazine, pyrimidine, pyridazine, triazine, indolizine, indole, isoindole, indazole, purine, quinolidine, isoquinoline, carbazole , Imidazole, naphthyridine, phthalazine, quinazoline, benzodiazepine, quinoxaline, cinnoline, quinoline, pteridine, phenanthridine, acridine, perimidine, phenanthroline, phenazine, carboline, indolocarbazole, phenotelrazine, phenotherazine, phenothiazine, phenoxazine, antilysine , Benzothiazole, benzimidazole, benzoxazole, A group formed by removing hydrogen from nzoisoxazole or benzoisothiazole. Preferably benzene, naphthalene, anthracene, pyridine, pyrazine, pyrimidine, pyridazine, triazine, isoindole, indazole, purine, isoquinoline, imidazole, naphthyridine, phthalazine, quinazoline, benzodiazepine, quinoxaline, cinnoline, quinoline, pteridine, phenanthridine, acridine , Groups formed by removing hydrogen from perimidine, phenanthroline, phenazine, carboline, indole, carbazole, dibenzofuran, or dibenzothiophene.

In the general formulas (1) and (2), R and R ^{1 to} R ⁷ are groups other than hydrogen, and when the group has a substituent, the substituent is an alkyl group having 1 to 20 carbon atoms, carbon 7-38 aralkyl group, C2-C20 alkenyl group, C2-C20 alkynyl group, C2-C40 dialkylamino group, C12-44 diarylamino group, C14-C14 76 Diaralkylamino group, C2-C20 acyl group, C2-C20 acyloxy group, C1-C20 alkoxy group, C2-C20 alkoxycarbonyl group, C2-C20 An alkoxycarbonyloxy group, an alkylsulfonyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or an aromatic heterocyclic group having 3 to 18 carbon atoms. Preferably, it is an alkyl group having 1 to 10 carbon atoms, an aralkyl group having 7 to 24 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a diarylamino group having 12 to 36 carbon atoms, or an aromatic hydrocarbon having 6 to 18 carbon atoms. Group or an aromatic heterocyclic group having 3 to 18 carbon atoms, more preferably an aromatic hydrocarbon group having 6 to 18 carbon atoms and an aromatic heterocyclic group having 3 to 16 carbon atoms.

The C1-C20 alkyl group, C7-38 aralkyl group, C2-C20 alkenyl group, C2-C20 alkynyl group, C2-C40 dialkylamino group, C12 -44 diarylamino group, C14-76 diaralkylamino group, C2-20 acyl group, C2-20 acyloxy group, C1-20 alkoxy group, C2-20 An alkoxycarbonyl group having 2 to 20 carbon atoms, an alkylsulfonyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms and an aromatic heterocyclic group having 3 to 16 carbon atoms. A specific example is the same as that of carbon number among the specific examples of R and R ^{1 to} R ⁷ described above.

  Although the preferable specific example of a compound represented by General formula (1) and (2) is shown below, it is not limited to these.

In General Formula (3), Ring A represents a divalent carborane group of C ₂ B ₁₀ H ₁₀ represented by Formula (1a) or Formula (1b), and is the same when a plurality of rings A are present in the molecule. Or may be different, but is preferably represented by the formula (1a).

  In General formula (3), s, t, and u represent the number of substitutions, and m represents the number of repetitions. s and t represent an integer of 0 to 10, preferably 1 or 2. u represents an integer of 0 to 4, and m represents an integer of 0 to 6. u is preferably 0 or 1, and m is preferably 0. However, when u = 1, m is 0 or 1.

L ² , L ³ and L ^{4 each} independently represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a linked aromatic group constituted by connecting 2 to 6 thereof. L ² , L ³ , and L ⁴ are s + 1 valent, u + 1 valent, and t + 1 valent groups, respectively, and when these are divalent groups, they may be a single bond.

W represents N—R ⁸ or N, and when N, N is bonded to L ² , L ³ or L ⁴ . R ⁸ is independently hydrogen, an alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 16 carbon atoms. Or a linked aromatic group constituted by connecting 2 to 6 substituted or unsubstituted aromatic rings.

  Specific examples of the unsubstituted aromatic hydrocarbon group include aromatic hydrocarbon compounds such as benzene, naphthalene, fluorene, anthracene, anthryl, phenanthrene, triphenylene, tetraphenylene, fluoranthene, pyrene, chrysene, or aromatics in which a plurality of these are connected. And a group formed by removing hydrogen from a group hydrocarbon compound, preferably a group formed by removing hydrogen from benzene, naphthalene, fluorene, phenanthrene, or triphenylene.

  Specific examples of unsubstituted aromatic heterocyclic groups include pyridine, pyrimidine, triazine, quinoline, isoquinoline, quinoxaline, naphthyridine, carbazole, dibenzothiophene, dibenzofuran, acridine, azepine, tribenzoazepine, phenazine, diazafluorene, phenoxazine. An aromatic heterocyclic compound such as phenothiazine, dibenzophosphole, dibenzoborol, or a group formed by removing hydrogen from an aromatic heterocyclic compound in which a plurality of these are connected, preferably pyridine, pyrimidine, triazine, carbazole, A group formed by removing hydrogen from dibenzothiophene or dibenzofuran.

  The linked aromatic group is a group constituted by connecting 2 to 6 aromatic rings, and the connected aromatic rings may be the same or different, and an aromatic hydrocarbon group and an aromatic heterocyclic group Both may be included. The number of connected aromatic rings is preferably 2 to 4, more preferably 2 or 3. The explanation of the linked aromatic group is the same as the explanation of the linked aromatic group in the general formulas (1) and (2) unless otherwise specified.

  Specific examples of the linked aromatic group include biphenyl, terphenyl, phenylnaphthalene, diphenylnaphthalene, phenylanthracene, diphenylanthracene, diphenylfluorene, bipyridine, bipyrimidine, vitriazine, biscarbazole, phenylpyridine, phenylpyrimidine, phenyltriazine, phenyl Hydrogen is removed from carbazole, diphenylpyridine, diphenyltriazine, biscarbazolylbenzene, bisdibenzofuran, bisdibenzothiophene, bisfluorene, phenyldibenzofuran, phenyldibenzothiophene, bisdibenzofuranylbenzene, bisdibenzothiophenylbenzene, pyridylcarbazole, etc. And the resulting group.

In L ² , L ³ , L ⁴ , and R ^{8, when} it is an aromatic hydrocarbon group, an aromatic heterocyclic group or a linked aromatic group, it may have a substituent. In the case of having a substituent, the substituent is an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an acetyl group, and the alkyl group and the alkoxy group are linear, branched, and cyclic. May be. Preferably, it is a C1-C4 alkyl group, a C1-C2 alkoxy group, or an acetyl group.

  Here, the alkyl group includes a cyclic hydrocarbon group generated from cyclo, terpenes and the like in addition to the chain hydrocarbon group. Specific examples of the alkyl group include a chain or branched alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, and an octyl group, a cyclopentyl group, a cyclohexyl group, and the like. Examples thereof include cyclic alkyl groups such as alkyl groups. Specific examples of the alkoxy group include alkoxy groups such as a methoxy group and an ethoxy group derived from these alkyl groups such as a methyl group and an ethyl group.

  Although the preferable specific example of a compound represented by the said General formula (3) is shown below, it is not limited to these.

  When two or more kinds of host materials are used, they may be mixed and vapor-deposited using a single vapor deposition source before the device is created, or the device is created by an operation such as co-evaporation using a plurality of vapor deposition sources. You may mix at the time of doing. The mixing ratio (weight ratio) of the host material is not particularly limited, but the compound (A) represented by the general formula (1) or (2) and the compound (B) represented by the general formula (3) The ratio (A) :( B) is preferably in the range of 95: 5 to 5:95, more preferably in the range of 90:10 to 10:90.

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.

(1) Configuration of Organic EL Element FIG. 1 is a cross-sectional view schematically showing a structural example of a general organic EL element used in the present invention, where 1 is a substrate, 2 is an anode, 3 is a hole injection layer, Reference numeral 4 denotes a hole transport layer, 5 denotes a light emitting layer, 6 denotes an electron transport layer, 7 denotes an electron injection layer, and 8 denotes a cathode. The organic EL device of the present invention has an anode, a light emitting layer, an electron transport layer and a cathode as essential layers, but other layers may be provided as necessary. Examples of other layers include, but are not limited to, a hole injection transport layer, an electron blocking layer, and a hole blocking layer. In addition, a positive hole injection transport layer means either a positive hole injection layer, a positive hole transport layer, or both.

(2) Substrate The substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film or a sheet is used. In particular, glass plates and smooth and transparent synthetic resin plates such as polyester, polymethacrylate, polycarbonate and polysulfone are preferred. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

(3) Anode An anode 2 is provided on the substrate 1, and the anode plays a role of hole injection into the hole transport layer. This anode is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, an oxide of indium and / or zinc, or a halogen such as copper iodide. Metal oxide, carbon black, or a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline. In general, the anode is often formed by a sputtering method, a vacuum deposition method, or the like. Also, in the case of fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., it is dispersed in an appropriate binder resin solution and placed on the substrate. An anode can also be formed by coating. Further, in the case of a conductive polymer, a thin film can be directly formed on a substrate by electrolytic polymerization, or an anode can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett., 60). (Vol. 2711, 1992). The anode can be formed by stacking different materials. The thickness of the anode varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness is usually 5 to 1000 nm, preferably 10 to It is about 500 nm. If it may be opaque, the anode may be the same as the substrate. Furthermore, it is also possible to laminate different conductive materials on the anode.

(4) Hole Transport Layer The hole transport layer 4 is provided on the anode 2. A hole injection layer 3 can also be provided between them. As conditions required for the material of the hole transport layer, it is necessary that the material has a high hole injection efficiency from the anode and can efficiently transport the injected holes. For this purpose, the ionization potential is low, the transparency to visible light is high, the hole mobility is high, the stability is high, and impurities that become traps are unlikely to be generated during manufacturing or use. Required. Further, in order to contact the light emitting layer 5, it is required not to quench the light emitted from the light emitting layer or to form an exciplex with the light emitting layer to reduce the efficiency. In addition to the above general requirements, when the application for in-vehicle display is considered, the element is further required to have heat resistance. Therefore, a material having a Tg value of 85 ° C. or higher is desirable.

As the hole transporting material that can be used in the present invention, known compounds conventionally used in this layer can be used. For example, an aromatic diamine containing two or more tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681), 4,4 ', 4 "-tris (1- Aromatic amine compounds having a starburst structure such as naphthylphenylamino) triphenylamine (J. Lumin., 72-74, 985, 1997), aromatic amine compounds comprising a tetramer of triphenylamine ( Chem. Commun., 2175, 1996), spiro compounds such as 2,2 ', 7,7'-tetrakis- (diphenylamino) -9,9'-spirobifluorene (Synth. Metals, 91, 209) Page, 1997), etc. These compounds may be used alone or in combination as necessary.
In addition to the above compounds, polyarylene ether sulfone (Polym. Adv. Tech) containing polyvinylcarbazole, polyvinyltriphenylamine (Japanese Patent Laid-Open No. 7-53953), and tetraphenylbenzidine as a material for the hole transport layer. ., Vol. 7, p. 33, 1996).

  When forming the hole transport layer by a coating method, one or more hole transport materials and, if necessary, an additive such as a binder resin or a coating property improving agent that does not trap holes are added, Dissolve to prepare a coating solution, apply onto the anode by a method such as spin coating, and dry to form a hole transport layer. Examples of the binder resin include polycarbonate, polyarylate, and polyester. When the binder resin is added in a large amount, the hole mobility is lowered.

When forming by vacuum evaporation, put the hole transport material in a crucible installed in a vacuum vessel, evacuate the vacuum vessel to about 10 ^-4 Pa with a suitable vacuum pump, then heat the crucible The hole transport material is evaporated, and a hole transport layer is formed on the substrate on which the anode is formed, facing the crucible. The thickness of the hole transport layer is usually 1 to 300 nm, preferably 5 to 100 nm. In order to uniformly form such a thin film, a vacuum deposition method is generally used.

(5) Hole injection layer For the purpose of further improving the efficiency of hole injection and improving the adhesion of the whole organic layer to the anode, the hole injection layer is provided between the hole transport layer 4 and the anode 2. 3 is also inserted. By inserting the hole injection layer, the driving voltage of the initial element is lowered, and at the same time, an increase in voltage when the element is continuously driven with a constant current is suppressed. The conditions required for the material used for the hole injection layer are that the contact with the anode is good and a uniform thin film can be formed, which is thermally stable, that is, the glass transition temperature is high, and the glass transition temperature is 100 ° C. or higher. Is required. Furthermore, the ionization potential is low, hole injection from the anode is easy, and the hole mobility is high.

  For this purpose, phthalocyanine compounds such as copper phthalocyanine (Japanese Patent Laid-Open No. 63-295695), polyaniline (Appl. Phys. Lett., 64, 1245, 1994), polythiophene (Optical Materials, 9, 125, 1998) and other organic compounds, sputtered carbon films (Synth. Met., 91, 73, 1997), metals such as vanadium oxide, ruthenium oxide, molybdenum oxide P type such as oxide (J. Phys. D, 29, 2750, 1996), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and hexanitrile hexaazatriphenylene (HAT) Organic substances (WO2005-109542) have been reported. These compounds may be used alone or in combination as necessary. In the case of the hole injection layer, a thin film can be formed in the same manner as the hole transport layer, but in the case of an inorganic material, a sputtering method, an electron beam evaporation method, or a plasma CVD method is further used. The thickness of the hole injection layer formed as described above is usually 1 to 300 nm, preferably 5 to 100 nm.

(6) Light-Emitting Layer The light-emitting layer 5 is provided on the hole transport layer 4. The light emitting layer may be formed from a single light emitting layer, or may be formed by laminating a plurality of light emitting layers so as to be in direct contact with each other. The light emitting layer includes at least two host materials and at least one light emitting dopant. The host material includes the compound of the general formula (1) or (2) and the compound of the general formula (3), and particularly preferably includes the compound of the general formula (1) and the compound of the general formula (3). As the light-emitting dopant, there are fluorescent light-emitting materials and phosphorescent light-emitting materials. The former is used in the case of an element using fluorescent emission or delayed fluorescent emission, and the latter is used in the case of an element using phosphorescence emission. Is done.

  As the fluorescent light-emitting material used for fluorescence emission, condensed ring derivatives such as perylene and rubrene, quinacridone derivatives, phenoxazone 660, DCM1, perinone, coumarin derivatives, pyromethene (diazaindacene) derivatives, cyanine dyes and the like can be used.

  Examples of delayed fluorescence materials used for delayed fluorescence include carborane derivatives, tin complexes, indolocarbazole derivatives, copper complexes, carbazole derivatives, and the like. Specific examples include compounds described in the following non-patent documents and patent documents, but are not limited to these compounds.

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

  Specific examples of the delayed light emitting material are shown below, but are not limited to the following compounds.

  When the fluorescent light-emitting material or the delayed fluorescent light-emitting material is used as a light-emitting dopant and a host material is included, the amount of the light-emitting dopant contained in the light-emitting layer is 0.01 to 50% by weight, preferably 0.8. The content should be in the range of 1 to 20% by weight, more preferably 0.01 to 10%.

  As the phosphorescent light-emitting material used for phosphorescence, a material containing an organometallic complex containing at least one metal selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and gold is preferable. 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, 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.

  Although there is no restriction | limiting in particular about the film thickness of a light emitting layer, Usually, 1-300 nm, Preferably it is 5-100 nm, and it forms a thin film with the method similar to a hole transport layer.

(7) Electron Transport Layer An electron transport layer 6 is provided between the light emitting layer 5 and the cathode 8 for the purpose of further improving the light emission efficiency of the device. As the electron transport layer, an electron transport material capable of smoothly injecting electrons from the cathode is preferable, and any commonly used material can be used. As an electron transport material satisfying such conditions, a metal complex such as Alq3 (JP 59-194393A), a metal complex of 10-hydroxybenzo [h] quinoline, an oxadiazole derivative, a distyrylbiphenyl derivative, a silole derivative, 3 -Or 5-hydroxyflavone metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (USP 5,645,948), quinoxaline compound (JP6-207169A), phenanthroline derivative (JP5-331459A), 2-t-butyl- 9,10-N, N′-dicyanoanthraquinone diimine, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide and the like can be mentioned.

  The film thickness of the electron transport layer is usually 1 to 300 nm, preferably 5 to 100 nm. The electron transport layer is formed by laminating on the light emitting layer by a coating method or a vacuum deposition method in the same manner as the hole transport layer. Usually, a vacuum deposition method is used.

(8) Cathode The cathode 8 plays a role of injecting electrons into the electron transport layer 6. As the material used as the cathode, the material used for the anode 2 can be used. However, a metal having a low work function is preferable for efficient electron injection, and tin, magnesium, indium, calcium, aluminum A suitable metal such as silver or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.
The thickness of the cathode is usually the same as that of the anode. For the purpose of protecting the cathode made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere on the cathode increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.
Furthermore, it is also effective to improve the efficiency of the device by inserting an ultrathin insulating film (0.1-5 nm) such as LiF, MgF ₂ , Li ₂ O between the cathode 8 and the electron transport layer 6 as the electron injection layer 7. Is the method.

1, that is, a cathode 8, an electron injection layer 7, an electron transport layer 6, a light emitting layer 5, a hole transport layer 4, a hole injection layer 3, and an anode 2 are laminated on the substrate 1 in this order. It is also possible to provide the organic EL element of the present invention between two substrates, at least one of which is highly transparent as described above. Also in this case, layers can be added or omitted as necessary.
Further, on the substrate 1, the anode 2, the hole injection layer 3, the hole transport layer 4, the light emitting layer 5-1, the light emitting layer 5-2, the electron transport layer 6, the electron injection layer 7, the cathode 8 and the anode 2, Hole injection layer 3, hole transport layer 4-1, light emitting layer 5-1, electron transport layer 6-1, hole transport layer 4-2, light emitting layer 5-2, electron transport layer 6-2, electron injection It is also possible to stack a plurality of light emitting layers like the layer 7 and the cathode 8.

  The organic EL element of the present invention can be any of a single element, an element having a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an XY matrix. According to the organic EL element of the present invention, an element having high luminous efficiency and greatly improved driving stability can be obtained even at a low voltage, and exhibits excellent performance in application to a full-color or multi-color panel. it can.

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

Example 1
Each thin film was laminated at a vacuum degree of 4.0 × 10 ⁻⁴ Pa by a vacuum deposition method on a glass substrate on which an anode made of ITO having a thickness of 150 nm was formed. First, copper phthalocyanine (CuPc) having a thickness of 20 nm is formed on ITO as a hole injection layer, and then 4,4-bis [N- (1-naphthyl) -N-phenylamino] is formed as a hole transport layer. Biphenyl (NPB) was formed to a thickness of 20 nm. Next, as the light emitting layer, compound 1-4 as the first host, compound 3-21 as the second host, and tris (2-phenylpyridine) iridium (III) (Ir (PPy) ₃ ) as the light emitting layer guest, respectively. Co-deposited from different deposition sources and formed to a thickness of 30 nm. At this time, the deposition rate ratio of the first host, the second host, and Ir (PPy) ₃ (volume rate ratio of the vaporized product) was 47: 47: 6. Next, aluminum (III) bis (2-methyl-8-quinolinato) 4-phenylphenolate (BAlq) was formed to a thickness of 10 nm as a hole blocking layer. Next, tris- (8-hydroxyquinolinato) aluminum (III) (Alq ₃ ) was formed to a thickness of 40 nm as an electron transport layer. Further, on the electron transport layer, lithium fluoride (LiF) was formed to a thickness of 0.5 nm as an electron injection layer. Finally, on the electron injection layer, aluminum (Al) was formed as a cathode to a thickness of 100 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, an emission spectrum with a maximum wavelength of 517 nm was observed, and it was found that light emission from Ir (PPy) ₃ was obtained. Table 1 shows the luminance, voltage, external quantum efficiency, and luminance half time of the organic EL device produced.

Examples 2-4
In Example 1, the organic EL element was produced like Example 1 except having used the compound described in Table 1 as a light emitting layer 2nd host. When an external power source was connected to the obtained organic EL element and a DC voltage was applied, an emission spectrum with a maximum wavelength of 517 nm was observed from any organic EL element, and light emission from Ir (PPy) ₃ was obtained. I understood. Table 1 shows the luminance, voltage, luminous luminous efficiency, and luminance half time of the organic EL device produced.

Comparative Examples 1-5
In Example 1, an organic EL device was produced in the same manner as in Example 1 except that the compound described in Table 1 was used alone as the light emitting layer host. The host amount was the same as the total of the first host and the second host in Example 1, and the guest amount was the same. When a power source was connected to the obtained organic EL element and a DC voltage was applied, an emission spectrum with a maximum wavelength of 517 nm was observed from any organic EL element, and light emission from Ir (PPy) ₃ was obtained. all right. Table 1 shows the luminance, voltage, luminous luminous efficiency, and luminance half time of the organic EL device produced.

Table 1 shows the luminance, voltage, luminous luminous efficiency, and luminance half time of the organic EL device produced. In Table 1, the luminance, voltage, and light emission efficiency are values at a driving current of 20 mA / cm ² , and the luminance half time is a value at an initial luminance of 1000 cd / m ² . Compound No. is the number given to the above chemical formula.

  In Table 1, when Examples 1-4 of the present invention and Comparative Examples 1-5 are compared, it can be seen that Examples 1-4 have improved luminance and efficiency and show good life characteristics.

Example 5
Each thin film was laminated at a vacuum degree of 4.0 × 10 ⁻⁴ Pa by a vacuum deposition method on a glass substrate on which an anode made of ITO having a thickness of 150 nm was formed. First, CuPc was formed to a thickness of 20 nm on ITO as a hole injection layer, and then NPB was formed to a thickness of 20 nm as a hole transport layer. Next, as a light emitting layer, compound 2-5 as a first host, compound 3-21 as a second host, and Ir (PPy) ₃ as a light emitting layer guest were co-deposited from different deposition sources, respectively, to a thickness of 30 nm. Formed. At this time, the deposition rate ratio of the first host, the second host, and Ir (PPy) ₃ was 47: 47: 6. Next, BAlq was formed to a thickness of 10 nm as a hole blocking layer. Next, to form an Alq ₃ to a thickness of 40nm as an electron transport layer. Further, on the electron transport layer, lithium fluoride (LiF) was formed to a thickness of 0.5 nm as an electron injection layer. Finally, on the electron injection layer, aluminum (Al) was formed as a cathode to a thickness of 100 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, an emission spectrum with a maximum wavelength of 517 nm was observed, and it was found that light emission from Ir (PPy) ₃ was obtained.
Table 2 shows the luminance, external quantum efficiency, luminance half-life, and luminance half-time of the organic EL device produced.

Examples 6-7
In Example 5, the organic EL element was produced like Example 5 except having used the compound described in Table 2 as a light emitting layer 2nd host. When an external power source was connected to the obtained organic EL element and a DC voltage was applied, an emission spectrum with a maximum wavelength of 517 nm was observed from any organic EL element, and light emission from Ir (PPy) ₃ was obtained. I understood. Table 2 shows the brightness, voltage, luminous efficiency, and half-life time of the organic EL elements produced.

Comparative Examples 6-9
In Example 5, an organic EL device was produced in the same manner as in Example 5 except that the compound described in Table 2 was used alone as the light emitting layer host. The host amount was the same as the sum of the first host and the two hosts in Example 5. When an external power source was connected to the obtained organic EL element and a DC voltage was applied, an emission spectrum with a maximum wavelength of 517 nm was observed from any organic EL element, and light emission from Ir (PPy) ₃ was obtained. I understood.

Table 2 shows the luminance, external quantum efficiency, and luminance half-life of the organic EL device produced. The luminance and the external quantum efficiency are values at a driving current of 20 mA / cm ² , and the luminance half time is a value at an initial luminance of 1000 cd / m ² .

  In Table 2, when Examples 5-7 of the present invention are compared with Comparative Examples 6-9, it can be seen that Examples 5-7 have improved luminance and show good life characteristics.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode

Claims (5)

In an organic electroluminescent device including one or more light-emitting layers between an anode and a cathode facing each other, at least one light-emitting layer contains at least two host materials and at least one light-emitting dopant. An organic electroluminescent device comprising a compound represented by the general formula (1) or (2) and a compound represented by the following general formula (3).

(Here, ring a, ring c, and ring c ′ independently represent an aromatic ring represented by the formula (a1) condensed with two adjacent rings at an arbitrary position, and X ¹ represents C—R or N. Ring b, ring d, and ring d ′ each independently represent a heterocyclic ring represented by the formula (b1) fused with two adjacent rings at an arbitrary position;
Ar ¹ independently represents an aromatic hydrocarbon group having 6 to 30 carbon atoms or an aromatic heterocyclic group having 3 to 16 carbon atoms,
Z represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, an aromatic heterocyclic group having 3 to 16 carbon atoms, or a linked aromatic group formed by connecting 2 to 10 thereof,
L ¹ independently represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, an aromatic heterocyclic group having 3 to 16 carbon atoms, or a linked aromatic group in which they are linked by 2 to 10;
p independently represents an integer of 0 to 7,
R and R ^{1 to} R ⁷ are independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 38 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, carbon A dialkylamino group having 2 to 40 carbon atoms, a diarylamino group having 12 to 44 carbon atoms, a diaralkylamino group having 14 to 76 carbon atoms, an acyl group having 2 to 20 carbon atoms, an acyloxy group having 2 to 20 carbon atoms, and a carbon number An alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 20 carbon atoms, an alkoxycarbonyloxy group having 2 to 20 carbon atoms, an alkylsulfonyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, Or an aromatic heterocyclic group having 3 to 18 carbon atoms, and when R ¹ , R ² , and R ^{4 to} R ⁷ are phenyl groups, they may form a condensed ring with an aromatic ring substituted by the phenyl group, Ar ¹ , Z, L ¹ , R, R ^{1 to} R ⁷ may have a substituent when they are an aromatic hydrocarbon group or an aromatic heterocyclic group,
When Z, L ¹ , R, and R ^{1 to} R ⁷ are linked aromatic groups, they may be linear or branched, and the linked aromatic rings may be the same or different. Or may have a substituent. )

(Here, ring A independently represents a divalent carborane group of C ₂ B ₁₀ H ₁₀ represented by formula (1a) or (1b);
s, t, and u represent the number of substitutions, m represents the number of repetitions, s and t are integers of 0 to 10, u is an integer of 0 to 4, and m is an integer of 0 to 6. However, when u = 1, m is 0 or 1.
L ² , L ³ , and L ^{4 each} independently represent a single bond or an aromatic hydrocarbon group having 6 to 30 carbon atoms, or a linked aromatic group formed by connecting 2 to 6 thereof, provided that L ² , L ³ , and L ⁴ are each an s + 1 valent group, a u + 1 valent group, and a t + 1 valent group, and when L ² , L ³ , or L ⁴ is a divalent group, a single bond is formed. You can,
W independently represents N—R ⁸ or N, and when W = N, N binds to L ² or L ⁴ . R ⁸ is independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, an aromatic heterocyclic group having 3 to 16 carbon atoms, or the substituted or unsubstituted aromatic group The connection aromatic group comprised by connecting 2-6 rings is shown. When L ² , L ³ , L ⁴ and R ⁸ are an aromatic hydrocarbon group or an aromatic heterocyclic group, they may have a substituent, and L ² , L ³ , L ⁴ and R ⁸ are When it is a linked aromatic group, it may be linear or branched, and the linked aromatic rings may be the same or different, and may have a substituent. ) The organic electroluminescent element according to claim 1, wherein in the general formula (1) or (2), X ¹ is C—R. The organic electroluminescent device according to claim 2, wherein in general formula (1) or (2), at least one of Ar ¹ is a substituted or unsubstituted aromatic heterocyclic group having 3 to 16 carbon atoms.   The organic electroluminescent element according to claim 1, wherein the host material contains a compound represented by the general formula (1) and a compound represented by the general formula (3).   The luminescent dopant is an organometallic complex containing at least one metal selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and gold. The organic electroluminescent element as described.

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