TW201542500A - An organic electroluminescent compound and an organic electroluminescent device comprising the same - Google Patents

Abstract

The present invention relates to a novel organic electroluminescent compound and an organic electroluminescent device comprising the same. By using the organic electroluminescent compound according to the present invention, it is possible to produce an organic electroluminescent device having excellent current efficiency and lifespan characteristics.

Description

Organic electric field luminescent compound and organic electric field illuminating device comprising the same

The present invention relates to an organic electric field luminescent compound and an organic electric field illuminating device comprising the same.

The electric field illuminating device (EL device) is a self-illuminating device which has the advantages of providing a wider viewing angle, a larger contrast ratio, and a faster reaction time. The organic EL device was first developed by Eastman Kodak as a material for forming a light-emitting layer by using an aromatic diamine small molecule and an aluminum complex [Appl. Phys. Lett. 51, 913, 1987] .

The most important factor determining the luminous efficiency in an organic EL device is a luminescent material. Fluorescent materials have been widely used as luminescent materials until today. However, in view of the mechanism of electric field luminescence, since phosphorescent materials theoretically increase the luminous efficiency by 4 times compared with fluorescent materials, the development of phosphorescent materials has been extensively studied. The ruthenium (III) complex is a well-known phosphorescent material, including bis(2-(2'-benzothienyl)-pyridine-N,C3') oxime (acetoxyacetone) ((acac)Ir ( Btp) ₂ ), ginseng (2-phenylpyridinium) ruthenium (Ir(ppy) ₃ ) and bis(4,6-difluorophenylpyridine-N,C2)pyridinium (Firpic), respectively, as red, green And blue materials.

Currently, 4,4'-N,N'-dicarbazole-biphenyl (CBP) is the most widely known phosphorescent host material. Recently, Pioneer (Japan) and other companies have developed bathocuproine (BCP) and aluminum (III) bis(2-methyl-8-hydroxyquinoline) (4-phenylphenol) (BAlq) Etc. (which is a conventional hole barrier material) is a high-performance organic EL device as a host material.

Although these materials provide good luminescent properties, they still have the following disadvantages: (1) due to their lower glass transition temperature and poor thermal stability, degradation may occur during vacuum high temperature deposition processes and the life of the device may be reduced. . (2) The power efficiency of the organic EL device is obtained by the formula [(π/voltage) × current efficiency], and the power efficiency is inversely proportional to the voltage. Although an organic EL device comprising a phosphorescent host material can provide a higher current efficiency (candle (cd) / ampere (A)) than a material containing a fluorescent material, it still requires a significantly high driving voltage. Therefore, there is no advantage in terms of power efficiency (lumens (lm) / watt (W)). (3) Furthermore, the operational life of the organic EL device is short, and the luminous efficiency remains to be improved.

Meanwhile, in order to enhance the efficiency and stability thereof, the organic EL device has a multilayer structure including a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer. The choice of compounds included in the hole transport layer is known as a method of improving device characteristics including efficiency of transmission of holes to the light-emitting layer, luminous efficiency, lifetime, and the like.

Therefore, copper phthalocyanine (CuPc), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-diphenyl-N,N '-bis(3-methylbenzene) -(1,1'-biphenyl)-4,4'-diamine (TPD), 4,4',4"-parade (3-methylphenylphenylamino)triphenylamine (MTDATA) is used as a hole injection and transport material. However, an organic EL device using such materials is problematic in terms of quantum efficiency and operational life because when an organic EL device is driven at a high current Thermal stress occurs between the anode and the hole injection layer. Thermal stress significantly shortens the life of the device. Furthermore, since the organic material used in the hole injection layer has very high hole mobility, the hole - The charge balance of electrons may be destroyed and the quantum yield (cd/A) is reduced.

Therefore, there is still a need to develop a hole transport layer for improving the durability of an organic EL device.

Japanese Patent Application Laid-Open No. JP 2001-196177 discloses a compound which emits light as an organic electric field, in which two of the benzene ring systems are each substituted with a diarylamine. However, the above document does not disclose an organic electric field light-emitting device for use in a compound in which a benzene ring is substituted with two diarylamines.

It is an object of the present invention to provide an organic electroluminescent compound having excellent luminous efficiency and life characteristics.

The inventors have found that the above object can be achieved by an organic electroluminescent compound represented by the following formula (1):

Wherein, L ₁ and L ₂ each independently represent a single bond, a substituted or unsubstituted (C6-C30) extended aryl group, or a substituted or unsubstituted (3 to 30 membered) heteroaryl group; Ar ₁ To Ar ₄ each independently represents a substituted or unsubstituted (C1-C30) alkyl group, a substituted or unsubstituted (C3-C30) cycloalkyl group, substituted or unsubstituted (3 to 7 members) Heterocycloalkyl, substituted or unsubstituted (C6-C30) aryl, or substituted or unsubstituted (3 to 30 membered) heteroaryl; R ₁ and R ₂ each independently represent substituted or unsubstituted Substituted (C1-C30)alkyl, substituted or unsubstituted (C3-C30)cycloalkyl, substituted or unsubstituted (3 to 7 membered) heterocycloalkyl, substituted or unsubstituted Substituted (C6-C30) aryl, or substituted or unsubstituted (3 to 30 membered) heteroaryl; or bonded to each other to form a monocyclic or polycyclic (C3-C30) alicyclic or aromatic ring ; R ₃ represents hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3 to 30 members) Heteroaryl, substituted or unsubstituted (C3-C30) cycloalkyl, substituted or unsubstituted (3 to 7) a heterocycloalkyl group, a substituted or unsubstituted (C6-C30) aryl (C1-C30) alkyl group, -NR ₄ R ₅ , -SiR ₆ R ₇ R ₈ , a cyano group, a nitro group, or a hydroxyl group; or a linkage to one or more adjacent substituents to form a monocyclic or polycyclic (C3-C30) alicyclic or aromatic ring; R ₄ and R ₅ each independently represent hydrogen, deuterium, halogen, substituted or Unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, or substituted or unsubstituted (3 to 30 membered) heteroaryl; R ₆ to R ₈ Each independently represents hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3 to 30) a heteroaryl group, a substituted or unsubstituted (3 to 7 membered) heterocycloalkyl group, or a substituted or unsubstituted (C3-C30) cycloalkyl group; or linked to one or more phases An ortho substituent may be a monocyclic or polycyclic (C3-C30) alicyclic or aromatic ring substituted with at least one hetero atom selected from nitrogen, oxygen and sulfur to form one or more carbon atoms in the ring; a represents 1 to an integer of 4, when a system of 2 or an integer greater than 2, each R ₃ may be the same or different; and ( ) Heteroaryl group and the heterocyclic ring containing at least one group each independently selected from B, N, O, S, P (= O), Si, P, and the hetero atom.

The effect of the invention

By using the organic electroluminescent compound according to the present invention, an organic electric field light-emitting device having excellent current and luminous efficiency can be produced.

Specific embodiment of the present invention

Hereinafter, the contents of the present invention will be described in detail. However, the following description is intended to be illustrative of the invention and is not intended to limit the scope of the invention in any form.

The present invention relates to an organic electroluminescent compound of the formula (1), an organic electroluminescent material comprising the compound, and an organic electric field light-emitting device comprising the same.

The organic electroluminescent compound represented by the above formula (1) will be described in detail below.

In the present specification, "(C1-C30)alkyl" means an alkyl group having a straight or branched chain of 1 to 30 carbon atoms, wherein the number of carbon atoms is preferably from 1 to 10, more preferably from 1 to 6, and includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, etc.; "(C2-C30)alkenyl" means having 2 to 30 carbon atoms a linear or branched alkenyl group, wherein the number of carbon atoms is preferably from 2 to 20, more preferably from 2 to 10, and includes a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, and 2 -butenyl, 3-butenyl, 2-methylbut-2-enyl, etc.; "(C2-C30)alkynyl" means a straight or branched alkynyl group having 2 to 30 carbon atoms. The number of carbon atoms is preferably from 2 to 20, more preferably from 2 to 10, and includes ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3- Butynyl, 1-methylpent-2-ynyl, etc.; "(C3-C30)cycloalkyl" is a monocyclic or polycyclic hydrocarbon having 3 to 30 carbon atoms, and the number of carbon atoms is preferably 3 to 20, more preferably 3 to 7, and including cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.; "(3 to 7 membered) heterocycloalkyl" has 3 to 7 a cycloalkyl group of a ring skeleton atom, comprising at least one hetero atom selected from the group consisting of B, N, O, S, P(=O), Si, and P, preferably O, S, and N, and including tetrahydrofuran, pyrrole Pyridine, thiolan, tetrahydropyran, etc.; "(C6-C30) (extended) aryl" is a monocyclic or fused ring derived from an aromatic hydrocarbon having 6 to 30 carbon atoms, and its carbon The number of atoms is preferably from 6 to 20, more preferably from 6 to 15, and includes phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, phenylnaphthyl, naphthylphenyl. , mercapto, phenylfluorenyl, benzofluorenyl, dibenzofluorenyl, phenanthryl, phenylphenanthrenyl, anthryl, fluorenyl, triphenylenyl, fluorenyl, fused tetraphenyl Tetracenyl), fluorenyl, fluorenyl, naphthacenyl, fluoranthenyl, etc.; "(3 to 30 members) (extended) heteroaryl" has 3 to 30 ring skeletons The aryl group of the atom, comprising at least one, preferably 1 to 4, heteroatoms selected from the group consisting of B, N, O, S, P(=O), Si, and P; a fused ring of at least one benzene ring condensation; may be partially saturated; Forming at least one heteroaryl or aryl group to the heteroaryl group through one or more single bonds; and including a heterocyclic group of a monocyclic type including furyl, thienyl, pyrrolyl, imidazolyl, pyridyl Azyl, thiazolyl, thiadiazolyl, isothiazolyl, iso Azolyl, Azolyl, Diazolyl, three Base, four Base, triazolyl, tetrazolyl, furazolyl, pyridyl, pyridyl Base, pyrimidinyl, oxime a heteroaryl group of the condensed ring type, which includes a benzofuranyl group, a benzothienyl group, an isobenzofuranyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzonaphthylthiophene group, Benzimidazolyl, benzothiazolyl, benzisothiazolyl, benziso Azolyl, benzo Azolyl, isodecyl, fluorenyl, oxazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, porphyrinyl, quinazolinyl, quin Orolinyl, carbazolyl, brown Peptidyl, benzodiyl Benzodioxolyl and the like. Further, "halogen" includes F, Cl, Br, and I.

According to a specific embodiment of the present invention, the compound of the formula (1) can be represented by the following formula (2).

Wherein L ₁ , L ₂ , Ar ₁ to Ar ₄ , R ₁ to R ₃ , and a are as defined in the formula (1).

In the present specification, "substituted" in the expression "substituted or unsubstituted" means that a hydrogen atom of a specific functional group is substituted with another atom or a group (that is, a substituent). The substituted (C1-C30) alkyl group of the formula (1), L ₁ , L ₂ , Ar ₁ to Ar ₄ , and R ₁ to R ₈ , the substituted (C 3 -C 30 ) cycloalkyl group, Substituted (3 to 7 membered) heterocycloalkyl, substituted (C6-C30) (extended) aryl, substituted (3 to 30 membered) (extended) heteroaryl, and substituted The substituent of the (C6-C30) aryl (C1-C30) alkyl group is each independently at least one selected from the group consisting of hydrazine, halogen, cyano, carboxyl, nitro, hydroxy, (C1- C30) alkyl, halo(C1-C30)alkyl, (C2-C30)alkenyl, (C2-C30)alkynyl, (C1-C30)alkoxy, (C1-C30)alkylthio, (C3 -C30) cycloalkyl, (C3-C30)cycloalkenyl, (3 to 7 membered) heterocycloalkyl, (C6-C30) aryloxy, (C6-C30) arylthio, unsubstituted or via (C6-C30) aryl substituted (3 to 30 membered) heteroaryl, unsubstituted or substituted (3 to 30 membered) heteroaryl (C6-C30) aryl, tri(C1-C30) alkane Base group, tris(C6-C30) aryl fluorenyl, di(C1-C30)alkyl (C6-C30) aryl fluorenyl, (C1-C30)alkyl di(C6-C30) aryl fluorenyl Amino, mono or di(C1-C30)alkylamino, mono or di(C6-C30)arylamino, (C1-C30)alkyl(C6-C30)arylamine, (C1- C30) Alkylcarbonyl, (C1-C30) alkoxycarbonyl, (C6-C30) arylcarbonyl, bis(C6-C30) arylboryl, di(C1-C30)alkylboron, (C1-C30) An alkyl (C6-C30) aryl boron group, a (C6-C30) aryl (C1-C30) alkyl group, and a (C1-C30) alkyl (C6-C30) aryl group, and preferably each independently selected At least one of the group consisting of: (C1-C6)alkyl, (C6-C25)aryl, and (5 to 20 membered) heteroaryl.

In the above formula (1), L ₁ and L ₂ each independently represent a single bond, a substituted or unsubstituted (C6-C30) extended aryl group, or a substituted or unsubstituted (3 to 30 member) stretch. Heteroaryl, preferably each independently represents a single bond, substituted or unsubstituted (C6-C12) extended aryl, or substituted or unsubstituted (5 to 20 membered) heteroaryl, and more preferably Each independently represents a single bond, an unsubstituted (C6-C12) extended aryl group, or an unsubstituted (5 to 20 membered) heteroaryl group.

Ar ₁ to Ar ₄ each independently represent a substituted or unsubstituted (C1-C30) alkyl group, a substituted or unsubstituted (C3-C30) cycloalkyl group, substituted or unsubstituted (3 to 7) a heterocycloalkyl group, a substituted or unsubstituted (C6-C30) aryl group, or a substituted or unsubstituted (3 to 30 membered) heteroaryl group, preferably each independently represents substituted or unsubstituted Substituted (C6-C15) aryl, and more preferably each independently represents unsubstituted or substituted by (C1-C6)alkyl, (C6-C15)aryl, or (5 to 20 membered) heteroaryl ( C6-C15) aryl.

R ₁ and R ₂ each independently represent a substituted or unsubstituted (C1-C30) alkyl group, a substituted or unsubstituted (C3-C30) cycloalkyl group, substituted or unsubstituted (3 to 7). a heterocycloalkyl group, a substituted or unsubstituted (C6-C30) aryl group, or a substituted or unsubstituted (3 to 30 membered) heteroaryl group; or linked to each other to form a single ring or more The (C3-C30) alicyclic or aromatic ring, preferably each independently represents a substituted or unsubstituted (C1-C6) alkyl group, a substituted or unsubstituted (C6-C20) aryl group, or a Substituted or unsubstituted (5 to 20 membered) heteroaryl; or bonded to each other to form a monocyclic or polycyclic (C6-C20) alicyclic or aromatic ring, and more preferably each independently represents unsubstituted ( C1-C6)alkyl; unsubstituted or substituted by (C1-C6)alkyl, (C6-C25)aryl, or (5 to 20 membered)heteroaryl (C6-C20) aryl; Substituted (5 to 20 membered) heteroaryl groups substituted by (C6-C12) aryl; or bonded to each other to form a monocyclic or polycyclic (C6-C20) aromatic ring.

R ₃ represents hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3 to 30) a heteroaryl, substituted or unsubstituted (C3-C30)cycloalkyl, substituted or unsubstituted (3 to 7 membered) heterocycloalkyl, substituted or unsubstituted (C6- C30) aryl (C1-C30) alkyl, -NR ₄ R ₅ , -SiR ₆ R ₇ R ₈ , cyano, nitro, or hydroxy; or linked to one or more adjacent substituents to form a single ring Or a polycyclic (C3-C30) alicyclic or aromatic ring, preferably each independently represents hydrogen, substituted or unsubstituted (C6-C12) aryl, substituted or unsubstituted (C5-C12) ring An alkyl group, -NR ₄ R ₅ , or -SiR ₆ R ₇ R ₈ ; or linked to one or more adjacent substituents to form a monocyclic or polycyclic (C6-C12) alicyclic or aromatic ring, and more Each independently represents hydrogen, unsubstituted (C6-C12) aryl, unsubstituted (C5-C12) cycloalkyl, -NR ₄ R ₅ , or -SiR ₆ R ₇ R ₈ ; or linked to one Or a plurality of adjacent substituents to form a monocyclic (C6-C12) aromatic ring.

R ₄ and R ₅ each independently represent hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, or substituted or unsubstituted The substituted (3 to 30 membered) heteroaryl group preferably each independently represents a substituted or unsubstituted (C6-C12) aryl group, and more preferably each independently represents an unsubstituted (C6-C12) aryl group.

R ₆ to R ₈ each independently represent hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3 to 30 membered) heteroaryl, substituted or unsubstituted (3 to 7 membered) heterocycloalkyl, or substituted or unsubstituted (C3-C30) cycloalkyl; or linked to a Or a plurality of adjacent substituents to form a monocyclic or polycyclic (C3-C30) alicyclic or aromatic ring in which one or more carbon atoms in the ring may be replaced by at least one hetero atom selected from nitrogen, oxygen and sulfur. Preferably, each independently represents a substituted or unsubstituted (C1-C6)alkyl group, and more preferably each independently represents an unsubstituted (C1-C6)alkyl group.

a represents an integer of 1 to 4, preferably an integer of 1 to 2; and when a is 2 or an integer greater than 2, each R ₃ may be the same or different.

The (extended) heteroaryl group and the heterocycloalkyl group each independently contain at least one hetero atom selected from the group consisting of B, N, O, S, P(=O), Si, and P.

According to a specific embodiment of the present invention, in the above formula (1), L ₁ and L ₂ each independently represent a single bond, a substituted or unsubstituted (C6-C12) extended aryl group, or a substituted or unsubstituted group. Substituted (5 to 20 members) heteroaryl; Ar ₁ to Ar ₄ each independently represent a substituted or unsubstituted (C6-C15) aryl group; R ₁ and R ₂ each independently represent substituted or unsubstituted (C1-C6)alkyl, substituted or unsubstituted (C6-C20) aryl, or substituted or unsubstituted (5 to 20 membered) heteroaryl; or linked to each other to form a single ring Or a polycyclic (C6-C20) alicyclic or aromatic ring; R ₃ represents hydrogen, substituted or unsubstituted (C6-C12) aryl, substituted or unsubstituted (C5-C12) cycloalkyl , -NR ₄ R ₅ , or -SiR ₆ R ₇ R ₈ ; or linked to one or more adjacent substituents to form a monocyclic or polycyclic (C6-C12) alicyclic or aromatic ring; R ₄ and R ₅ independently represents a substituted or unsubstituted (C6-C12) aryl group; R ₆ to R ₈ each independently represent a substituted or unsubstituted (C1-C6) alkyl group; and a represents an integer of 1 to 2 .

According to another embodiment of the present invention, in the above formula (1), L ₁ and L ₂ each independently represent a single bond, an unsubstituted (C6-C12) extended aryl group, or an unsubstituted (5 to 20 members) heteroaryl; Ar ₁ to Ar ₄ each independently represent unsubstituted or substituted by (C1-C6)alkyl, (C6-C15)aryl, or (5 to 20 membered) heteroaryl ( C6-C15) aryl; R ₁ and R ₂ each independently represent unsubstituted (C1-C6)alkyl; unsubstituted or via (C1-C6)alkyl, (C6-C25)aryl, or 5 to 20 members) a heteroaryl substituted (C6-C20) aryl group; or an unsubstituted or substituted (5 to 20 membered) heteroaryl group substituted with a (C6-C12) aryl group; or bonded to each other to form a single a cyclic or polycyclic (C6-C20) aromatic ring; R ₃ represents hydrogen, unsubstituted (C6-C12) aryl, unsubstituted (C5-C12) cycloalkyl, -NR ₄ R ₅ , or -SiR ₆ R ₇ R ₈ ; or linked to one or more adjacent substituents to form a monocyclic (C6-C12) aromatic ring; R ₄ and R ₅ each independently represent unsubstituted (C6-C12) aromatic R ₆ to R ₈ each independently represent an unsubstituted (C1-C6)alkyl group; and a represents an integer of 1 to 2.

Specific compounds of the invention include, but are not limited to, the following:

The organic electroluminescent compound of the present invention can be prepared by a synthetic method well known to those skilled in the art. For example, it can be prepared according to the following reaction scheme.

Wherein L ₁ , L ₂ , Ar ₁ to Ar ₄ , R ₁ to R ₃ , and a are as defined in the above formula (1).

The present invention provides an organic electroluminescent material comprising an organic electroluminescent compound of the formula (1), and an organic electric field emitting device comprising the same.

The above materials may individually comprise an organic electroluminescent compound according to the present invention, or may comprise a conventional material commonly used in organic electroluminescent materials.

The organic electric field light-emitting device includes a first electrode, a second electrode, and at least one organic layer interposed between the first and second electrodes. The organic layer may comprise at least one organic electroluminescent compound of formula (1).

One of the first and second electrodes can be an anode and the other can be a cathode. The organic layer comprises a light-emitting layer, and the plurality of layers may be selected from the group consisting of At least one layer of the group: a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, an interposer, a hole barrier layer, and an electron blocking layer.

The organic electroluminescent compound according to the present invention may be contained in at least one of the light-emitting layer and the hole transport layer. When used in a hole transport layer, the organic electroluminescent compound of the present invention can be included as a hole transport material. When used in the light-emitting layer, the organic electroluminescent compound of the present invention can be contained as a host material.

The organic electroluminescent device comprising the organic electroluminescent compound of the present invention may further comprise one or more compounds different from the organic electroluminescent compound according to the present invention as a host material, and may further comprise one or more dopants.

When the organic electroluminescent compound according to the present invention is contained as a host material (first host material), other compounds may be contained as the second host material. In the present specification, the weight ratio of the first host material to the second host material ranges from 1:99 to 99:1.

The host material different from the organic electroluminescent compound according to the present invention may be derived from any conventional phosphorescent host. Specifically, a phosphorescent host selected from the group consisting of compounds of the following formulas (11) to (13) is preferred in terms of luminous efficiency.

H-(Cz-L ₄ ) _h -M----------(11)

H-(Cz) _i -L ₄ -M----------(12)

Where Cz represents the following structure;

R ₂₁ to R ₂₄ each independently represent hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3 to 30 membered) heteroaryl, or -SiR ₂₅ R ₂₆ R ₂₇ ; R ₂₅ to R ₂₇ each independently represent a substituted or unsubstituted (C1-C30) alkyl group, or substituted or unsubstituted (C6-C30) aryl; L ₄ represents a single bond, a substituted or unsubstituted (C6-C30) extended aryl group, or a substituted or unsubstituted (5 to 30 membered) heteroaryl group; M represents a substituted or unsubstituted (C6-C30) aryl group, or a substituted or unsubstituted (5 to 30 membered) heteroaryl group; Y ₁ and Y ₂ each independently represent -O-, -S- , -N(R ₃₁ )-, or -C(R ₃₂ )(R ₃₃ )-, the restriction conditions are Y ₁ and Y _{2 are} not present at the same time; R ₃₁ to R ₃₃ each independently represent substituted or unsubstituted (C1-C30)alkyl, substituted or unsubstituted (C6-C30) aryl, or substituted or unsubstituted (5 to 30 membered) heteroaryl, and R ₃₂ and R ₃₃ may be the same Or different; h and i each independently represent an integer from 1 to 3; j, k, b, and c each independently represent an integer from 0 to 4; and when h, i, j, k, b, or c is 2 or large Integer of 2, each of the (Cz-L _4), each (HCz), each of R _21, each R _22, each R _23, or each R ₂₄ may be the same or different.

Specifically, the preferred embodiment of the host material is as follows:

[where TPS represents triphenylsulfonyl]

The dopant contained in the organic electroluminescent device according to the present invention is preferably at least one phosphorescent dopant. The dopant material applied to the organic electroluminescent device according to the present invention is not limited, but may preferably be a metal compound compound selected from the group consisting of ruthenium, osmium, copper and platinum, more preferably selected from the group consisting of ruthenium, osmium, and copper. An ortho-metalated composite compound of platinum, and even more preferably an ortho-metallated ruthenium complex.

The phosphorescent dopant may preferably be selected from the compounds represented by the following formulas (101) to (103).

Wherein L is selected from the following structures,

R ₁₀₀ represents hydrogen, substituted or unsubstituted (C1-C30) alkyl, or substituted or unsubstituted (C3-C30) cycloalkyl; R ₁₀₁ to R ₁₀₉ , and R ₁₁₁ to R ₁₂₃ Independently represented by hydrogen, deuterium, halogen, unsubstituted or substituted by one or more halo (C1-C30)alkyl, cyano, substituted or unsubstituted (C1-C30) alkoxy, substituted or Unsubstituted (C6-C30) aryl, or substituted or unsubstituted (C3-C30) cycloalkyl; R ₁₀₆ to R ₁₀₉ may be bonded to one or more adjacent substituents to form substituted or Unsubstituted fused ring, such as unsubstituted or alkyl substituted fluorene, unsubstituted or alkyl substituted dibenzothiophene, or unsubstituted or alkyl substituted dibenzofuran; R ₁₂₀ to R ₁₂₃ may be bonded to one or more adjacent substituents to form a substituted or unsubstituted fused ring, such as a quinoline which is unsubstituted or substituted with a halogen, an alkyl group, or an aryl group; R ₁₂₄ And R ₁₂₇ each independently represent hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30) alkyl, or substituted or unsubstituted (C6-C30) aryl; and R ₁₂₄ to R ₁₂₇ Link to one or a plurality of adjacent substituents to form a substituted or unsubstituted fused ring, such as an unsubstituted or alkyl substituted oxime, unsubstituted or alkyl substituted dibenzothiophene, or unsubstituted or Alkyl-substituted dibenzofuran; R ₂₀₁ to R ₂₁₁ each independently represent hydrogen, deuterium, halogen, unsubstituted or substituted by one or more halogen (C1-C30) alkyl, substituted or unsubstituted a (C3-C30)cycloalkyl group, or a substituted or unsubstituted (C6-C30) aryl group, and R ₂₀₈ to R ₂₁₁ may be bonded to one or more adjacent substituents to form substituted or unsubstituted Substituted fused ring, such as unsubstituted or alkyl substituted fluorene, unsubstituted or alkyl substituted dibenzothiophene, or unsubstituted or alkyl substituted dibenzofuran; f and g Each independently represents an integer from 1 to 3; when f or g is 2 or greater than 2, each R ₁₀₀ may be the same or different; and n represents an integer from 1 to 3.

Specifically, the phosphorescent dopant material includes the following,

In another embodiment of the invention, a composition for preparing an organic electric field illuminating device is provided. The composition comprises a compound according to the invention as a host material or a hole transport material.

Further, an organic electric field light-emitting device according to the present invention includes a first electrode, a second electrode, and at least one organic layer interposed between the first and second electrodes. The organic layer comprises a light-emitting layer, and the light-emitting layer may comprise the composition for preparing an organic electric field light-emitting device according to the present invention.

The organic electroluminescence device according to the present invention may further comprise, in addition to the organic electroluminescent compound represented by the formula (1), at least one compound selected from the group consisting of an arylamine compound and a styrylarylamine compound. .

In the organic electric field light-emitting device according to the present invention, the organic layer may further comprise a first group metal selected from the periodic table, a second group metal, a fourth periodic transition metal, a fifth periodic transition metal, a lanthanide element, and a d group. At least one metal of the group consisting of transition metals of the transition element, or at least one composite compound comprising the metal. The organic layer may further comprise a light emitting layer and a charge generating layer.

Furthermore, the organic electroluminescent device according to the present invention can emit white light by further comprising at least one luminescent layer comprising a blue electric field luminescent compound, a red electric field luminescent compound, which is well known in the art other than the compound of the present invention. Or a green electric field luminescent compound. In addition, a yellow or orange luminescent layer may also be included in the device if desired.

According to the present invention, at least one layer (hereinafter referred to as "surface layer") is preferably placed on the inner surface of one or two electrodes; the surface layer is selected from the group consisting of a chalcogenide layer, a metal halide layer and a metal oxide layer. Specifically, the chalcogenide (including oxide) layer of tantalum or aluminum is preferably placed on the anode surface of the electric field luminescent medium layer, and the metal halide layer or the metal oxide layer is preferably placed in the electric field luminescent medium layer. Cathode surface. This surface layer provides operational stability of the organic electric field illuminating device. The chalcogenide preferably comprises SiO _X (1 X 2), AlO _X (1 X 1.5), SiON, SiAlON, etc.; the metal halide includes LiF, MgF ₂ , CaF ₂ , rare earth metal fluoride, etc.; and the metal oxide includes Cs ₂ O, Li ₂ O, MgO, SrO, BaO, CaO, and the like.

In the organic electric field light-emitting device according to the present invention, the mixed region of the electron transporting compound and the reducing dopant, or the mixed region of the hole transporting compound and the oxidizing dopant is preferably placed on at least one surface of the pair of electrodes. In this case, the electron transporting compound is reduced to an anion, making it easy to inject and transport electrons from the mixed region to the electric field illuminating medium. Furthermore, the hole transporting compound is oxidized to a cation, making it easy to inject and transport holes from the mixing zone to the electric field illuminating medium. Preferably, the oxidizing dopant comprises a plurality of Lewis acids and acceptor compounds; and the reducing dopant comprises an alkali metal, an alkali metal compound, an alkaline earth metal, a rare earth metal, and a mixture thereof. A reducing dopant layer can be employed as the charge generating layer to prepare an electric field light-emitting device having two or more layers of an electroluminescent layer and emitting white light.

In order to form the layers of the organic electric field light-emitting device according to the present invention, a dry film formation method (for example, vacuum evaporation, sputtering, plasma plating, and ion plating) or a wet film formation method (for example, spin coating) may be used. Cloth, dip coating, and flow coating).

When a wet film formation method is used, the film can be dissolved or dispersed in any suitable solvent (for example, ethanol, chloroform, tetrahydrofuran, two by dissolving the materials constituting each layer). Alkane, etc.) forms a film. The solvent may be any solvent as long as the materials constituting each layer are soluble or dispersible in the solvent, and it does not cause any problem in the ability to form a film.

Hereinafter, the organic electroluminescent compound, the preparation method of the compound, and the luminescent properties of the device will be described in detail with reference to the following examples.

Example 1: Preparation of Compound C-1

Preparation of Compound 1-2

2,4-Dichlorophenylboronic acid (Compound 1-1) (64 g (g), 335 mmol (mmol)), methyl 2-bromobenzoate (60 g, 279 mmol), tetrakis(triphenyl) After phosphine)palladium (9.5 g, 8.4 mmol), potassium carbonate (96 g, 698 mmol), toluene 600 ml (mL), and ethanol 300 mL were added to the reaction vessel, 300 mL of distilled water was added to the mixture, and the mixture was stirred at 120 ° C. hour. After the reaction, the mixture was washed with distilled water, and the organic layer was extracted with ethyl acetate. The extracted organic layer was dried over magnesium sulfate and the solvent was removed on a rotary evaporator. Then, the remaining material was purified by column chromatography to give Compound 1-2 (79 g, 99%).

Preparation of Compound 1-3

Compound 1-2 (79 g, 279 mmol), Eaton reagent (Eaton’s) After 110 mL of reagent and 1 L of chlorobenzene were added to the reaction vessel, the mixture was stirred under reflux overnight. After cooling the reaction solution to room temperature, the reaction was completed with water, and the organic layer was extracted with dichloromethane. The extracted organic layer was dried over magnesium sulfate and the solvent was removed on a rotary evaporator. The remaining material was purified by column chromatography to give Compound 1-3 (49 g, 71%).

Preparation of compound 1-4

After adding iodine (18 g, 71 mmol), hypophosphorous acid (35 mL, 315 mmol, 50% aqueous solution), and 1 L of acetic acid to the reaction vessel, the mixture was stirred at 100 ° C for 30 minutes. After that, Compound 1-3 was slowly added dropwise thereto, and the mixture was stirred under reflux overnight. After cooling the reaction solution to room temperature, the precipitated solid was filtered and washed with a large amount of hexane. The filtrate was diluted with ethyl acetate and washed with water. The extracted organic layer was dried over magnesium sulfate and the solvent was removed using a rotary evaporator. The remaining material was purified by column chromatography to give compound 1-4 (35.7 g, 77%).

Preparation of compound 1-5

Compound 1-4 (35.5 g, 151 mmol), potassium hydroxide (42 g, 760 mmol), potassium iodide (2.5 g, 15 mmol), benzyltriethylammonium chloride (1.7 g, 7.8 mmol), distilled water 700 mL, and After 700 mL of formazan was added to the reaction vessel, the mixture was stirred at room temperature for 15 minutes. After that, methyl iodide (25 mL, 378 mmol) was added, and the mixture was stirred at room temperature overnight. The reaction solution was diluted with ethyl acetate and washed with distilled water. The extracted organic layer was dried over magnesium sulfate and the solvent was removed using a rotary evaporator. The remaining material was purified by column chromatography to give compound 1-5 (32 g, 81%).

Preparation of Compound C-1

Compound 1-5 (7 g, 26.6 mmol), dibiphenyl-4-ylamine (17 g, 52.9 mmol), hydrazine (dibenzylideneacetone) dipalladium (0) (1.9 g, 2.1 mmol), 2- Dicyclohexylphosphine-2',6'-dimethoxybiphenyl (s-phos) (1.1 g, 2.7 mmol), sodium butoxide (6.4 g, 67 mmol), and o-xylene 150 mL were added to the reaction vessel. After that, the mixture was stirred under reflux for 1 hour. Thereafter, the reaction solution cooled to room temperature was diluted with ethyl acetate and washed with water several times. The extracted organic layer was dried over anhydrous magnesium sulfate, evaporated under reduced pressure, and purified by column chromatography to afford Compound C-1 (9.6 g, 55%).

Example 2: Preparation of Compound C-9

Preparation of Compound 2-1

After the compound 3-1 (20.5 g, 82.3 mol) and 400 mL of tetrahydrofuran were added to the reaction vessel, the reaction solution was cooled to 0 ° C, and a solution of phenylmagnesium bromide (40 mL, 123 mmol) and 3 M diethyl ether was slowly added dropwise thereto. The reaction solution was stirred at room temperature for 1 hour. Thereafter, the reaction was completed with an aqueous solution of ammonium chloride, and the reaction solution was diluted with ethyl acetate and washed with water. The extracted organic layer was dried over anhydrous magnesium sulfate, evaporated under reduced pressure, and purified by column chromatography to afford Compound 2-1 (28 g, 99%).

Preparation of Compound 2-2

After a compound 2-1 (15.8 g, 48.3 mmol), 9-phenyloxazole (17.6 g, 72.5 mmol), and dichloromethane (MC) 250 mL were added to a reaction vessel, the mixture was placed under a nitrogen atmosphere. Then, 1.5 mL of Eaton reagent was slowly added dropwise thereto, and the mixture was stirred at room temperature for 2 hours. Thereafter, the reaction was completed with distilled water, and the mixture was extracted with dichloromethane. The extracted organic layer was dried over magnesium sulfate and the solvent was removed using a rotary evaporator. The remaining material was purified by column chromatography to give Compound 2-2 (13.2 g, 49%).

Preparation of Compound C-9

Compound 2-2 (13 g, 26.6 mmol), diphenylamine (8 g, 47 mmol), bis(dibenzylideneacetone) dipalladium (0) (1.7 g, 1.9 mmol), s-phos (0.96 g, 2.35) After adding mmol, sodium tributoxide (5.6 g, 58.8 mmol), and 120 mL of o-xylene to the reaction vessel, the mixture was stirred under reflux overnight. Thereafter, the reaction solution cooled to room temperature was diluted with ethyl acetate and washed with water several times. The extracted organic layer was dried over anhydrous magnesium sulfate, distilled under reduced pressure, and purified by column chromatography to afford Compound C-9 (10 g, 52%).

Device Example 1: Fabrication of an OLED device using an organic electroluminescent compound according to the present invention

An OLED device is fabricated using an organic electroluminescent compound according to the present invention. An indium tin oxide (ITO) film (10 Ω/sq) (Geomatec, Japan) for a transparent electrode on a glass substrate of an organic light-emitting diode (OLED) device was ultrasonically washed with acetone and isopropyl alcohol in that order. It is then stored in isopropanol. Next, the ITO substrate was mounted on a substrate holder of a vacuum vapor deposition apparatus. N ⁴ ,N ^4′ -biphenyl-N ⁴ ,N ^4′ -bis(9-phenyl-9H-carbazol-3-yl)-[1,1'-biphenyl]-4,4 The '-diamine was introduced into the cell of the vacuum vapor deposition apparatus, and then the chamber pressure of the apparatus was controlled to 10 ^-6 torr. Thereafter, a current was applied to the cell to evaporate the introduced material, thereby forming a first hole injecting layer having a thickness of 80 nm on the ITO substrate. Next, 1,4,5,8,9,11-hexazatriphenylenhexacarbonitrile (HAT-CN) is introduced into another chamber of the vacuum vapor deposition apparatus, and by applying a current to the The chamber is evaporated to form a second hole injection layer having a thickness of 5 nm on the first hole injection layer. Next, the following compound T-1 is introduced into another chamber of the vacuum vapor deposition apparatus, and evaporated by applying a current to the chamber, thereby forming a thickness of 10 nm on the second hole injection layer. A hole transport layer. Next, the compound C-1 is introduced into another chamber of the vacuum vapor deposition apparatus, and evaporated by applying a current to the chamber, thereby forming a second electricity having a thickness of 60 nm on the first hole transport layer. Hole transport layer. Thereafter, the compound H-1 was introduced into one chamber of the vacuum vapor deposition apparatus as a main body, and the compound D-96 was introduced into another chamber as a dopant. The two materials were evaporated at different rates and deposited at a doping amount of 3 wt% (based on the total amount of the host and the dopant) to form a light-emitting layer having a thickness of 40 nm on the second hole transport layer. Next, introduce 2-(4-(9,10-bis(naphthalen-2-yl) onion-2-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole into a small chamber and Lithium quinolate is introduced into another chamber. The two materials were evaporated at the same rate and deposited at a doping amount of 50% by weight to form an electron transport layer having a thickness of 35 nm on the light-emitting layer. Next, after depositing lithium quinolate on the electron transport layer as an electron injection layer having a thickness of 2 nm, an Al cathode having a thickness of 80 nm was deposited on the electron injection layer by another vacuum vapor deposition apparatus. Therefore, an OLED device is manufactured. All materials used to fabricate the OLED device were purified by vacuum sublimation at 10 ^-6 Torr prior to use.

The prepared OLED device showed red light having a density of 800 candelas (cm) per square meter (m ² ) and a current density of 2.8 milliamperes (mA) per square centimeter (cm ² ). As for the life characteristics, the time period in which the brightness is reduced to 90% at 5,000 nits is 800 hours.

Device Example 2: Fabrication of an OLED device using an organic electroluminescent compound according to the present invention

An OLED device was fabricated in the same manner as in Device Example 1, except that Compound C-9 was evaporated to form a second hole transport layer having a thickness of 60 nm.

The resulting OLED device showed red light having a luminance of 1500 cd/m ² and a current density of 5.2 mA/cm ² . As for the life characteristics, the time period in which the brightness is reduced to 90% at 5,000 nits is 750 hours.

Device Example 3: Fabrication of an OLED device using an organic electroluminescent compound according to the present invention

An OLED device was fabricated in the same manner as in Device Example 1, except that the compound C-67 was evaporated to form a second hole transport layer having a thickness of 60 nm.

The resulting OLED device showed red light having a luminance of 1200 cd/m ² and a current density of 4.2 mA/cm ² . As for the life characteristics, the time period in which the brightness is reduced to 90% at 5,000 nits is 780 hours.

Comparative Example 1: Fabrication of an OLED device comprising a conventional organic electroluminescent compound

An OLED device was fabricated in the same manner as in Device Example 1, except that the following compound was evaporated to form a second hole transport layer having a thickness of 60 nm.

The resulting OLED device showed red light having a luminance of 2000 cd/m ² and a current density of 11.2 mA/cm ² . As for the life characteristics, the time period in which the brightness is reduced to 90% at 5,000 nits is 67 hours.

It has been confirmed that the luminescent properties of the organic electroluminescent compound according to the present invention are superior to those of conventional materials. Further, an organic electric field light-emitting device using the organic electroluminescent compound according to the present invention has excellent light-emitting and life characteristics.

Claims (7)

An organic electroluminescent compound represented by the following formula (1), Wherein, L ₁ and L ₂ each independently represent a single bond, a substituted or unsubstituted (C6-C30) extended aryl group, or a substituted or unsubstituted (3 to 30 membered) heteroaryl group; Ar ₁ To Ar ₄ each independently represents a substituted or unsubstituted (C1-C30) alkyl group, a substituted or unsubstituted (C3-C30) cycloalkyl group, substituted or unsubstituted (3 to 7 members) Heterocycloalkyl, substituted or unsubstituted (C6-C30) aryl, or substituted or unsubstituted (3 to 30 membered) heteroaryl; R ₁ and R ₂ each independently represent substituted or unsubstituted Substituted (C1-C30)alkyl, substituted or unsubstituted (C3-C30)cycloalkyl, substituted or unsubstituted (3 to 7 membered) heterocycloalkyl, substituted or unsubstituted Substituted (C6-C30) aryl, or substituted or unsubstituted (3 to 30 membered) heteroaryl; or bonded to each other to form a monocyclic or polycyclic (C3-C30) alicyclic or aromatic ring ; R ₃ represents hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3 to 30 members) Heteroaryl, substituted or unsubstituted (C3-C30) cycloalkyl, substituted or unsubstituted (3 to 7) a heterocycloalkyl group, a substituted or unsubstituted (C6-C30) aryl (C1-C30) alkyl group, -NR ₄ R ₅ , -SiR ₆ R ₇ R ₈ , a cyano group, a nitro group, or a hydroxyl group; or a linkage to one or more adjacent substituents to form a monocyclic or polycyclic (C3-C30) alicyclic or aromatic ring; R ₄ and R ₅ each independently represent hydrogen, deuterium, halogen, substituted or Unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, or substituted or unsubstituted (3 to 30 membered) heteroaryl; R ₆ to R ₈ Each independently represents hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3 to 30) a heteroaryl group, a substituted or unsubstituted (3 to 7 membered) heterocycloalkyl group, or a substituted or unsubstituted (C3-C30) cycloalkyl group; or linked to one or more phases An ortho substituent may be substituted with a monocyclic or polycyclic (C3-C30) alicyclic or aromatic ring substituted with one or more carbon atoms in the ring via at least one hetero atom selected from nitrogen, oxygen and sulfur; An integer representing from 1 to 4, when a is 2 or an integer greater than 2, each R ₃ may be the same or different; And the (hetero)heteroaryl group and the heterocycloalkyl group each independently contain at least one hetero atom selected from the group consisting of B, N, O, S, P(=O), Si, and P. The organic electroluminescent compound according to claim 1, wherein the compound is represented by the following formula (2), Wherein L ₁ , L ₂ , Ar ₁ to Ar ₄ , R ₁ to R ₃ , and a are as defined in the first item of the patent application. The organic electroluminescent compound according to claim 1, wherein the substituted (C1-C30) alkyl group, L ₁ , L ₂ , Ar ₁ to Ar ₄ , and R ₁ to R ₈ Substituted (C3-C30)cycloalkyl, the substituted (3 to 7 membered) heterocycloalkyl, substituted (C6-C30) (extended) aryl, substituted (3 to 30 members) The (hetero)heteroaryl group and the substituted (C6-C30)aryl(C1-C30)alkyl group are each independently at least one selected from the group consisting of hydrazine, halogen, and cyanogen. Base, carboxyl, nitro, hydroxy, (C1-C30)alkyl, halo(C1-C30)alkyl, (C2-C30)alkenyl, (C2-C30)alkynyl, (C1-C30)alkoxy (C1-C30)alkylthio, (C3-C30)cycloalkyl, (C3-C30)cycloalkenyl, (3 to 7 membered)heterocycloalkyl, (C6-C30) aryloxy, (C6 -C30) arylthio, unsubstituted or substituted by (C6-C30) aryl (3 to 30 membered) heteroaryl, unsubstituted or substituted by (3 to 30 membered) heteroaryl (C6- C30) aryl, tri(C1-C30)alkylfluorenyl, tris(C6-C30)aryldecyl, di(C1-C30)alkyl(C6-C30)aryldecyl, (C1-C30) Alkyl bis(C6-C30)aryl fluorenyl, amine, mono or di(C1-C30)alkylamino, mono or di C6-C30) arylamino group, (C1-C30)alkyl (C6-C30) arylamino group, (C1-C30) alkylcarbonyl group, (C1-C30) alkoxycarbonyl group, (C6-C30) Arylcarbonyl, bis(C6-C30)arylboryl, di(C1-C30)alkylboron, (C1-C30)alkyl(C6-C30)arylboryl,(C6-C30)aryl A group consisting of (C1-C30)alkyl and (C1-C30)alkyl (C6-C30) aryl. The organic electroluminescent compound according to claim 1, wherein L ₁ and L ₂ each independently represent a single bond, a substituted or unsubstituted (C6-C12) extended aryl group, or a substituted or unsubstituted group. Substituted (5 to 20 members) heteroaryl; Ar ₁ to Ar ₄ each independently represent a substituted or unsubstituted (C6-C15) aryl group; R ₁ and R ₂ each independently represent substituted or unsubstituted (C1-C6)alkyl, substituted or unsubstituted (C6-C20) aryl, or substituted or unsubstituted (5 to 20 membered) heteroaryl; or linked to each other to form a single ring Or a polycyclic (C6-C20) alicyclic or aromatic ring; R ₃ represents hydrogen, substituted or unsubstituted (C6-C12) aryl, substituted or unsubstituted (C5-C12) cycloalkyl , -NR ₄ R ₅ , or -SiR ₆ R ₇ R ₈ ; or is attached to one or more adjacent substituents to form a monocyclic or polycyclic (C6-C12) alicyclic or aromatic ring; R ₄ and R ₅ each independently represents a substituted or unsubstituted (C6-C12) aryl group; R ₆ to R ₈ each independently represent a substituted or unsubstituted (C1-C6) alkyl group; and a represents 1 to 2 Integer. The organic electroluminescent compound according to claim 1, wherein L ₁ and L ₂ each independently represent a single bond, an unsubstituted (C6-C12) extended aryl group, or an unsubstituted (5 to 20) a) heteroaryl; Ar ₁ to Ar ₄ each independently represent unsubstituted or substituted by (C1-C6)alkyl, (C6-C15)aryl, or (5 to 20 membered) heteroaryl (C6 -C15) aryl; R ₁ and R ₂ each independently represent unsubstituted (C1-C6)alkyl; unsubstituted or via (C1-C6)alkyl, (C6-C25)aryl, or (5) To 20 members) a heteroaryl substituted (C6-C20) aryl group; or an unsubstituted or substituted (5 to 20 membered) heteroaryl group substituted with a (C6-C12) aryl group; or bonded to each other to form a single ring Or a polycyclic (C6-C20) aromatic ring; R ₃ represents hydrogen, unsubstituted (C6-C12) aryl, unsubstituted (C5-C12) cycloalkyl, -NR ₄ R ₅ , or - SiR ₆ R ₇ R ₈ ; or is attached to one or more adjacent substituents to form a monocyclic (C6-C12) aromatic ring; R ₄ and R ₅ each independently represent unsubstituted (C6-C12) aromatic R ₆ to R ₈ each independently represent an unsubstituted (C1-C6)alkyl group; and a represents an integer of 1 to 2. The organic electroluminescent compound according to claim 1, wherein the compound represented by the formula (1) is selected from the group consisting of An organic electric field light-emitting device comprising the organic electroluminescent compound according to claim 1 of the patent application.