KR102397506B1 - 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 of the present invention, an organic electroluminescent device having excellent current efficiency and lifespan characteristics can be manufactured.

Description

An Organic Electroluminescent Compound and an Organic Electroluminescent Device Comprising the Same

The present invention relates to an organic electroluminescent compound and an organic electroluminescent device comprising the same.

Among display devices, an electroluminescent device (EL device) is a self-emission type display device, and has a wide viewing angle, excellent contrast, and fast response speed. In 1987, Eastman Kodak (Eastman Kodak) developed for the first time an organic EL device using a low molecular weight aromatic diamine and aluminum complex as a material for forming a light emitting layer [Appl. Phys. Lett. 51, 913, 1987].

The most important factor determining the luminous efficiency in an organic electroluminescent device is a light emitting material. Fluorescent materials have been widely used as luminescent materials so far, but research on the development of phosphorescent luminescent materials has been widely conducted in that phosphorescent luminescent materials can theoretically improve luminous efficiency up to four times compared to fluorescent luminescent materials due to the electroluminescence mechanism. is becoming Until now, the iridium (III) complex series is widely known as a phosphorescent light emitting material, and for each RGB, bis(2-(2'-benzothienyl)-pyridinato-N,C-3')iridium(acetylacetonate) ) [(acac)Ir(btp) ₂ ], tris(2-phenylpyridine)iridium [Ir(ppy) ₃ ] and bis(4,6-difluorophenylpyridinato-N,C2)picolinane Materials such as toridium (Firpic) are known.

In the prior art, 4,4'-N,N'-dicarbazole-biphenyl (CBP) was most widely known as a phosphorescent host material. Recently, Bathocuproine (BCP) and aluminum (III) bis (2-methyl-8-quinolinate) (4-phenylphenolate) ( Balq) has been used as a host material to develop high-performance organic electroluminescent devices.

However, the existing materials have advantages in terms of luminescent properties, but have the following disadvantages: (1) The glass transition temperature is low and thermal stability is low, so it is deteriorated during the high-temperature deposition process under vacuum and the lifespan of the device is reduced. (2) In an organic electroluminescent device, power efficiency = [(π/voltage)×current efficiency], so power efficiency is inversely proportional to voltage. In an organic electroluminescent device using a phosphorescent host material, an organic electroluminescent device using a fluorescent material Although the current efficiency (cd/A) is higher than that of the light emitting device, the driving voltage is also quite high, so there is no great advantage in terms of power efficiency (lm/w). (3) In addition, when used in an organic electroluminescent device, it is not satisfactory in terms of operating life, and the luminous efficiency is still required to be improved.

On the other hand, the organic electroluminescent device consists of 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 in order to increase its efficiency and stability. In this case, selection of a compound included in the hole transport layer is recognized as a means for improving device characteristics such as hole transport efficiency to the light emitting layer, luminous efficiency, and lifetime.

In this regard, copper phthalocyanine (CuPc), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N as hole injection and transport materials in organic electroluminescent devices '-Diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), 4,4',4"-tris(3-methylphenyl) Phenylamino) triphenylamine (MTDATA) has been used, but when such a material is used, the quantum efficiency and lifespan of the organic electroluminescent device are deteriorated. , because thermal stress is generated between the anode and the hole injection layer, and the lifespan of the device is rapidly reduced due to such thermal stress In addition, the organic material used for the hole injection layer has very high hole mobility. For this reason, the hole-electron charge balance is broken, and thus quantum efficiency (cd/A) is lowered.

Therefore, the development of a hole transport layer for improving the durability of the organic electroluminescent device is still required.

International Publication No. WO2013/077344 A1 discloses a compound having an indolo[3,2,1-jk]carbazole skeleton as a compound for an organic electroluminescent device. However, the above document does not specifically disclose an organic electroluminescent device using a compound having an indolo[3,2,1-jk]carbazole skeleton in which diarylamine is bonded directly or by a linker such as arylene. .

International publication WO2013/077344 A1 (published on May 30, 2013)

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

As a result of intensive research to solve the above technical problem, the present inventors have found that the organic electroluminescent compound represented by the following Chemical Formula 1 achieves the above object and completed the present invention.

[Formula 1]

In Formula 1,

L ₁ is a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (5-30 membered)heteroarylene;

X is O or S;

R ₁ and R ₂ are each independently a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (5-30 membered)heteroaryl;

R ₃ and R ₄ are each independently hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30)alkyl, substituted or unsubstituted (C6-C30)aryl, substituted or unsubstituted (5-30 membered) heteroaryl, substituted or unsubstituted (3-7 membered)heterocycloalkyl, or substituted or unsubstituted (C3-C30)cycloalkyl; It may be linked with an adjacent substituent (C3-C30) to form a monocyclic or polycyclic alicyclic or aromatic ring, wherein a carbon atom of the formed alicyclic or aromatic ring is replaced with one or more heteroatoms selected from nitrogen, oxygen and sulfur can be;

a and b are each independently an integer of 1 to 4, and when a or b is an integer of 2 or more, each R ₃ and each R ₄ may be the same or different;

said heteroaryl(ene) comprises one or more heteroatoms selected from B, N, O, S, P(=O), Si and P;

The heterocycloalkyl comprises one or more heteroatoms selected from O, S and N.

The organic electroluminescent compound according to the present invention has the advantage of being able to manufacture an organic electroluminescent device having excellent current efficiency and lifespan characteristics.

Hereinafter, the present invention will be described in more detail, but this is for illustrative purposes only and should not be construed as limiting the scope of the present invention.

The present invention relates to an organic electroluminescent compound represented by Formula 1, an organic electroluminescent material including the organic electroluminescent compound, and an organic electroluminescent device including the material.

The organic electroluminescent compound represented by Formula 1 will be described in more detail as follows.

As used herein, "(C1-C30)alkyl" means a straight-chain or branched chain alkyl having 1 to 30 carbon atoms, preferably having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms. . Specific examples of the alkyl include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl. As used herein, "(C2-C30) alkenyl" means a straight-chain or branched chain alkenyl having 2 to 30 carbon atoms, preferably 2 to 20 carbon atoms, and more preferably 2 to 10 carbon atoms. Specific examples of the alkenyl include vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, and 2-methylbut-2-enyl. As used herein, "(C2-C30) alkynyl" means a straight-chain or branched alkynyl having 2 to 30 carbon atoms, preferably 2 to 20 carbon atoms, and more preferably 2 to 10 carbon atoms. Examples of the alkynyl include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methylpent-2-ynyl, and the like. As used herein, "(C3-C30) cycloalkyl" means a monocyclic or polycyclic hydrocarbon having 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms, and more preferably 3 to 7 carbon atoms. Examples of the cycloalkyl include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like. As used herein, "(3-7 membered) heterocycloalkyl" has 3 to 7 ring skeleton atoms, and at least one heteroatom selected from the group consisting of B, N, O, S, P(=O), Si and P; Preferably it means a cycloalkyl containing one or more heteroatoms selected from O, S and N, for example, tetrahydrofuran, pyrrolidine, thiolane, tetrahydropyran and the like. As used herein, "(C6-C30) aryl (ene)" refers to a monocyclic or fused-ring radical derived from an aromatic hydrocarbon having 6 to 30 carbon atoms, wherein the ring skeleton preferably has 6 to 20 carbon atoms, and 6 It is more preferable that it is thru|or 15. Examples of the aryl include phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, phenylnaphthyl, naphthylphenyl, fluorenyl, phenylfluorenyl, benzofluorenyl, dibenzofluorenyl, phenane threnyl, phenylphenanthrenyl, anthracenyl, indenyl, triphenylenyl, pyrenyl, tetracenyl, perylenyl, chrysenyl, naphthacenyl, fluoranthenyl, and the like. As used herein, "(5-30 membered) heteroaryl (ene)" has 5 to 30 ring skeleton atoms, and at least one hetero selected from the group consisting of B, N, O, S, P(=O), Si and P It means an aryl group containing an atom. The number of hetero atoms is preferably 1 to 4, and may be a single ring system or a fused ring system condensed with one or more benzene rings, and may be partially saturated. In addition, the heteroaryl (ene) herein includes a form in which one or more heteroaryl or aryl groups are connected to a heteroaryl group by a single bond. Examples of the heteroaryl include furyl, thiophenyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetrazinyl , triazolyl, tetrazolyl, furazanyl, pyridyl, pyrazinyl, pyrimidinyl, monocyclic heteroaryl such as pyridazinyl, benzofuranyl, benzothiophenyl, isobenzofuranyl, dibenzofuranyl, di Benzothiophenyl, benzonaphthothiophenyl, benzoimidazolyl, benzothiazolyl, benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl, isoindolyl, indolyl, indazolyl, benzothiadiazolyl, quinolyl , isoquinolyl, cinnolinyl, quinazolinyl, quinoxalinyl, carbazolyl, phenoxazinyl, phenanthridinyl, fused ring heteroaryl such as benzodioxolyl. As used herein, “halogen” includes F, Cl, Br and I atoms.

In addition, in the description of "substituted or unsubstituted" in the present invention, 'substitution' means that a hydrogen atom in one functional group is replaced with another atom or another functional group (ie, a substituent). In L ₁ and R ₁ to R ₄ of Formula 1, substituted (C1-C30)alkyl, substituted (C3-C30)cycloalkyl, substituted (3-7 membered)heterocycloalkyl, substituted (C6-C30)aryl ( ren) and substituted (5-30 membered) heteroaryl (ren) substituents are each independently deuterium, 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, ( (3-30 membered)heteroaryl unsubstituted or substituted with 3-7 membered)heterocycloalkyl, (C6-C30)aryloxy, (C6-C30)arylthio, (C6-C30)aryl, (3-30 membered) member) unsubstituted or substituted with heteroaryl (C6-C30)aryl, tri(C1-C30)alkylsilyl, tri(C6-C30)arylsilyl, di(C1-C30)alkyl(C6-C30)arylsilyl, (C1-C30)alkyldi(C6-C30)arylsilyl, amino, mono- or di- (C1-C30)alkylamino, mono- or di- (C6-C30)arylamino, (C1-C30)alkyl ( C6-C30)arylamino, (C1-C30)alkylcarbonyl, (C1-C30)alkoxycarbonyl, (C6-C30)arylcarbonyl, di(C6-C30)arylboronyl, di(C1-C30) )alkylboronyl, (C1-C30)alkyl(C6-C30)arylboronyl, (C6-C30)ar(C1-C30)alkyl and (C1-C30)alkyl(C6-C30)aryl It means at least one selected from, and each independently preferably at least one selected from the group consisting of (C1-C6)alkyl, (C6-C15)aryl and (5-15 membered)heteroaryl.

In Formula 1, L ₁ is a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (5-30 membered)heteroarylene, preferably a single bond, or a substituted or An unsubstituted (C6-C12) arylene, more preferably a single bond, or an unsubstituted (C6-C12) arylene.

wherein X is O or S.

Wherein R ₁ and R ₂ are each independently a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (5-30 membered) heteroaryl, preferably each independently a substituted or unsubstituted ( C6-C20)aryl, more preferably each independently (C1-C6)alkyl, (C6-C15)aryl, or (C6-C20)aryl unsubstituted or substituted with (5-15 membered)heteroaryl.

R ₁ and R ₂ may be the same as or different from each other, preferably different from each other.

wherein R ₃ and R ₄ are each independently hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30)alkyl, substituted or unsubstituted (C6-C30)aryl, substituted or unsubstituted (5-30 membered) )heteroaryl, substituted or unsubstituted (3-7 membered)heterocycloalkyl, or substituted or unsubstituted (C3-C30)cycloalkyl; It may be linked with an adjacent substituent (C3-C30) to form a monocyclic or polycyclic alicyclic or aromatic ring, wherein a carbon atom of the formed alicyclic or aromatic ring is replaced with one or more heteroatoms selected from nitrogen, oxygen and sulfur may be, preferably each independently hydrogen, substituted or unsubstituted (C1-C6)alkyl, substituted or unsubstituted (C6-C12)aryl, or substituted or unsubstituted (5-12 membered)heteroaryl and more preferably each independently hydrogen, unsubstituted (C1-C6)alkyl, unsubstituted (C6-C12)aryl, or unsubstituted (5-12 membered)heteroaryl.

Said a is an integer of 1-4, Preferably it is 1.

b is an integer of 1 to 4, preferably an integer of 1 to 2; In the case of an integer of 2 or more, each R ₄ may be the same or different.

The heteroaryl (ene) includes one or more heteroatoms selected from B, N, O, S, P(=O), Si and P.

The heterocycloalkyl comprises one or more heteroatoms selected from O, S and N.

According to an aspect of the present invention, in Formula 1, L ₁ is a single bond, or a substituted or unsubstituted (C6-C12)arylene; X is O or S; R ₁ and R ₂ are each independently substituted or unsubstituted (C6-C20)aryl; R ₃ and R ₄ are each independently hydrogen, substituted or unsubstituted (C1-C6)alkyl, substituted or unsubstituted (C6-C12)aryl, or substituted or unsubstituted (5-12 membered)heteroaryl; ; a is 1; b is an integer of 1 to 2.

According to another embodiment of the present invention, in Formula 1, L ₁ is a single bond, or an unsubstituted (C6-C12)arylene; X is O or S; R ₁ and R ₂ are each independently (C1-C6)alkyl, (C6-C15)aryl or (C6-C20)aryl unsubstituted or substituted with (5-15 membered)heteroaryl; R ₃ and R ₄ are each independently hydrogen, unsubstituted (C1-C6)alkyl, unsubstituted (C6-C12)aryl, or unsubstituted (5-12 membered)heteroaryl; a is 1; b is an integer of 1 to 2.

The organic electroluminescent compound of Formula 1 may be more specifically exemplified as the following compound, but is not limited thereto.

The organic electroluminescent compound according to the present invention may be prepared by a synthesis method known to those skilled in the art, for example, as shown in the following reaction scheme.

[Scheme 1]

In Scheme 1, L ₁ , X, R ₁ to R ₄ , a and b are the same as defined in Formula 1.

In addition, the present invention provides an organic electroluminescent material including the organic electroluminescent compound of Formula 1 and an organic electroluminescent device including the material.

The material may be made of the organic electroluminescent compound of the present invention alone, or may further include conventional materials included in the organic electroluminescent material.

An organic electroluminescent device according to the present invention includes a first electrode; a second electrode; and at least one organic material layer interposed between the first electrode and the second electrode, wherein the organic material layer may include at least one organic electroluminescent compound of Formula 1 above.

One of the first and second electrodes may be an anode and the other may be a cathode. The organic material layer includes a light emitting layer, and may further include one or more layers selected from a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, an interlayer, a hole blocking layer, and an electron blocking layer.

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

The organic electroluminescent device including the organic electroluminescent compound of the present invention may further include one or more other compounds other than the organic electroluminescent compound of the present invention as a host material, and may further include one or more dopants.

When the organic electroluminescent compound of the present invention is included as the host material (first host material) of the light emitting layer, other compounds may be included as the second host material. In this case, the weight ratio of the first host material to the second host material is in the range of 1:99 to 99:1.

As the host material of the compound other than the organic electroluminescent compound of the present invention, any known phosphorescent host can be used. desirable.

[Formula 11]

H-(Cz-L ₄ ) _h -M

[Formula 12]

H-(Cz) _i -L ₄ -M

[Formula 13]

In Formulas 11 to 13,

Cz is the structure,

R ₂₁ to R ₂₄ are each independently hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30)alkyl, substituted or unsubstituted (C6-C30)aryl, substituted or unsubstituted (3-30 membered) heteroaryl or R ₂₅ R ₂₆ R ₂₇ Si-, and R ₂₅ to R ₂₇ are each independently substituted or unsubstituted (C1-C30)alkyl, or substituted or unsubstituted (C6-C30)aryl; L ₄ is a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (5-30 membered)heteroarylene; M is substituted or unsubstituted (C6-C30)aryl, or substituted or unsubstituted (5-30 membered)heteroaryl; Y ₁ and Y ₂ are -O-, -S-, -N(R ₃₁ )-, -C(R ₃₂ )(R ₃₃ )-, and Y ₁ and Y ₂ are not present simultaneously; R ₃₁ to R ₃₃ are each independently a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (5-30 membered)heteroaryl, and R ₃₂ and R ₃₃ may be the same or different; h and i are each independently an integer of 1 to 3, j, k, c and d are each independently an integer of 0 to 4, when h, i, j, k, c or d is an integer of 2 or more, each (Cz-L ₄ ), each (Cz), each R ₂₁ , each R ₂₂ , each R ₂₃ or each R ₂₄ may be the same or different.

Specifically, preferred examples of the host material are as follows.

[Here, TPS is triphenylsilyl]

As a dopant included in the organic electroluminescent device of the present invention, at least one phosphorescent dopant is preferable. The phosphorescent dopant material applied to the organic electroluminescent device of the present invention is not particularly limited, but a complex compound of a metal atom selected from iridium (Ir), osmium (Os), copper (Cu) and platinum (Pt) is preferable. and more preferably an ortho-metalated complex compound of a metal atom selected from iridium (Ir), osmium (Os), copper (Cu) and platinum (Pt), and even more preferably an ortho-metalated iridium complex compound.

The phosphorescent dopant is preferably selected from the group consisting of compounds represented by the following Chemical Formulas 101 to 103.

[Formula 101] [Formula 102] [Formula 103]

In Formulas 101 to 103, L is selected from the following structures;

R ₁₀₀ is 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 are each independently hydrogen, deuterium, halogen, halogen-substituted or unsubstituted (C1-C30)alkyl, substituted or unsubstituted (C3-C30)cycloalkyl, cyano, or substituted or unsubstituted ( C1-C30) alkoxy; When R ₁₀₆ to R ₁₀₉ is an aryl group, adjacent substituents are connected to each other and a substituted or unsubstituted (3-30 membered) monocyclic or polycyclic alicyclic or (hetero)aromatic ring (eg, flu unsubstituted or substituted with alkyl) orene, dibenzothiophene substituted or unsubstituted with alkyl, dibenzofuran substituted or unsubstituted with alkyl);

R ₁₂₀ to R ₁₂₃ may be connected to each other by adjacent substituents to form a substituted or unsubstituted (3-30 membered) monocyclic or polycyclic alicyclic or (hetero)aromatic ring, for example, substituted or unsubstituted with alkyl cyclic quinoline formation is possible;

R ₁₂₄ to R ₁₂₇ are each independently hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30)alkyl, or substituted or unsubstituted (C6-C30)aryl; When R ₁₂₄ to R ₁₂₇ is an aryl group, adjacent substituents may be connected to each other to form a substituted or unsubstituted (3-30 membered) monocyclic or polycyclic alicyclic or (hetero)aromatic ring, for example, an alkyl It is possible to form substituted or unsubstituted fluorene, dibenzothiophene substituted or unsubstituted with alkyl, dibenzofuran substituted or unsubstituted with alkyl;

R ₂₀₁ to R ₂₁₁ are each independently hydrogen, deuterium, halogen, halogen-substituted or unsubstituted (C1-C30)alkyl, substituted or unsubstituted (C3-C30)cycloalkyl, or (C6-30)aryl;

f and g are each independently an integer from 1 to 3; When each f or g is an integer of 2 or more, each R ₁₀₀ may be the same as or different from each other;

n is an integer from 1 to 3.

Specific examples of the phosphorescent dopant material are as follows.

.

.

The present invention provides a composition for manufacturing an organic electroluminescent device in a further aspect. The composition comprises the compound of the present invention as a host material or a hole transport layer material.

In addition, the organic electroluminescent device of the present invention includes a first electrode; a second electrode; and at least one organic material layer interposed between the first electrode and the second electrode, wherein the organic material layer includes a light emitting layer, and the light emitting layer may include the composition for an organic electroluminescent device of the present invention.

The organic electroluminescent device of the present invention may include the organic electroluminescent compound of Formula 1, and at the same time include at least one compound selected from the group consisting of an arylamine-based compound or a styrylarylamine-based compound.

In addition, in the organic electroluminescent device of the present invention, in the organic material layer, in addition to the organic electroluminescent compound of Formula 1, Group 1, Group 2, 4th period, 5th period transition metal, a lanthanide series metal, and an organometal of a d-transition element. It may further include one or more metals or complex compounds selected from the group, and further, the organic layer may further include a light emitting layer and a charge generating layer.

In addition, the organic electroluminescent device of the present invention may emit white light by further including one or more light emitting layers including a blue, red, or green light emitting compound known in the art in addition to the compound of the present invention. In addition, if necessary, it may further include a yellow or orange light emitting layer.

In the organic electroluminescent device of the present invention, on the inner surface of at least one of the pair of electrodes, one layer selected from a chalcogenide layer, a metal halide layer and a metal oxide layer (hereinafter, these are referred to as “surface layer”) It is preferable to arrange the above. Specifically, it is preferable to arrange a chalcogenide (including oxide) layer of metals of silicon and aluminum on the surface of the anode on the side of the light emitting medium layer, and a metal halide layer or metal oxide layer on the surface of the cathode on the side of the light emitting medium layer Do. Thereby, stabilization of the drive can be obtained. Preferred examples of the chalcogenide include SiO _X (1≤X≤2), AlO _X (1≤X≤1.5), SiON or SiAlON, and preferred examples of the metal halide include LiF, MgF ₂ , CaF ₂ , fluoride and rare earth metals, and preferred examples of the metal oxide include Cs ₂ O, Li ₂ O, MgO, SrO, BaO, CaO, and the like.

In addition, in the organic electroluminescent device of the present invention, it is also possible to arrange a mixed region of an electron transport compound and a reducing dopant or a mixed region of a hole transport compound and an oxidative dopant on at least one surface of the pair of electrodes thus manufactured. desirable. In this way, since the electron transport compound is reduced to an anion, it is easy to inject and transfer electrons from the mixed region to the light emitting medium. In addition, since the hole transport compound is oxidized to a cation, it is easy to inject and transport holes from the mixing region to the light emitting medium. Preferred oxidizing dopants include various Lewis acids and acceptor compounds, and preferred reducing dopants include alkali metals, alkali metal compounds, alkaline earth metals, rare earth metals, and mixtures thereof. In addition, a white organic electroluminescent device having two or more light emitting layers can be manufactured by using the reducing dopant layer as a charge generating layer.

The formation of each layer of the organic electroluminescent device of the present invention is a dry film formation method such as vacuum deposition, sputtering, plasma, ion plating, etc., or a wet film formation method such as spin coating, dip coating, flow coating, etc. Any one method can be applied.

In the case of the wet film forming method, a thin film is formed by dissolving or dispersing the material forming each layer in an appropriate solvent such as ethanol, chloroform, tetrahydrofuran, or dioxane, the solvent in which the material forming each layer is dissolved or dispersed. It can be, and any one may be used as long as there is no problem in the film-forming property.

Hereinafter, for a detailed understanding of the present invention, the organic electroluminescent compound according to the present invention, its preparation method, and the light emitting characteristics of the device will be described with reference to the representative compound of the present invention.

[ Example 1] Preparation of compound C-1

Preparation of compound 2

In a reaction vessel, 5H-benzofuro[3,2-c]carbazole (Compound 1) (30 g, 116.60 mmol), 4-bromo-1-fluoro-2-nitrobenzene (25.7 g, 116.60 mmol) ) and cesium carbonate (53.2 g, 163.24 mmol) were dissolved in 150 mL of dimethyl sulfoxide, followed by stirring at room temperature for 18 hours. After adding purified water to the mixture, the obtained solid was purified by column chromatography to obtain compound 2 (48 g, 90 %).

Preparation of compound 3

Compound 2 (30 g, 65.61 mmol) was dissolved in ethyl acetate in a reaction vessel, and tin chloride (44.4 g, 196.82 mmol) was added to the mixture. The mixture was stirred at reflux for 5 hours, washed with distilled water, extracted with ethyl acetate, and the organic layer was dried over magnesium sulfate, the solvent was removed using a rotary evaporator, and then purified by column chromatography to obtain compound 3 (20 g, 71%).

Preparation of compound 4

Compound 3 (17 g, 39.79 mmol) was dissolved in a mixed solution of 10 mL of sulfuric acid and 100 mL of acetic acid at 0° C. in a reaction vessel, and then the mixture was dissolved with ethyl acetate, and then sodium nitrite was added. After 10 minutes, the mixture was heated and stirred under reflux for 6 hours. After the reaction was completed, the mixture was washed with distilled water, extracted with ethyl acetate, and the organic layer was dried over magnesium sulfate, the solvent was removed using a rotary evaporator, and then purified by column chromatography to obtain compound 4 (2.8 g, 17%).

Preparation of compound C-1

In a reaction vessel, compound 4 (2.8 g, 6.82 mmol), (4-(diphenylamino)phenyl)boronic acid (2.4 g, 8.19 mmol), sodium carbonate (1.8 g, 17.05 mmol) and tetrakis(triphenylphosphine) Palladium (0.2 g, 0.21 mmol) was added to a mixed solution of 36 mL of toluene, 9 mL of ethanol, and 9 mL of purified water, and the mixture was stirred under reflux for 3 hours. After the reaction was completed, extraction was performed with ethyl acetate, the resulting organic layer was washed with 500 mL of distilled water, the organic layer was dried over magnesium sulfate, and the organic solvent was removed under reduced pressure. The obtained solid was separated by silica gel column chromatography and recrystallization to obtain compound C-1 (1.9 g, 49 %).

UV: 394 nm, PL: 417 nm, Mp: 334°C, mass: 574.67

[device production example 1] Organic according to the present invention electric field using luminescent compounds OLED device manufacturing

An OLED device was manufactured using the organic electroluminescent compound of the present invention. First, the transparent electrode ITO thin film (10Ω/□) obtained from glass for OLED (manufactured by Samsung-Corning) was ultrasonically cleaned using trichloroethylene, acetone, ethanol and distilled water sequentially, and then placed in isopropanol and stored. was used. Next, after mounting the ITO substrate in the substrate holder of the vacuum deposition equipment, N ⁴ ,N ^{4'-diphenyl-N 4 , N} 4'-bis(9-phenyl-9H-carbazole- 3-yl)-[1,1'-biphenyl]-4,4'-diamine (compound HI-1) was added and evacuated until the vacuum level in the chamber reached 10 ^-6 torr, and then an electric current was applied to the cell. A first hole injection layer having a thickness of 80 nm was deposited on the ITO substrate by evaporation. Then, 1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile (compound HI-2) is put into another cell in the vacuum deposition equipment, and an electric current is applied to the cell to evaporate the first hole A second hole injection layer having a thickness of 3 nm was deposited on the injection layer. Then, N-([1,1'-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazole-3- Il)phenyl)-9H-fluoren-2-amine (compound HT-1) was added, and the cell was evaporated by applying an electric current to deposit a first hole transport layer having a thickness of 10 nm on the second hole injection layer. Then, the compound C-1 was put into another cell in the vacuum deposition equipment, and the cell was evaporated by applying a current to deposit a second hole transport layer having a thickness of 30 nm on the first hole transport layer. After the hole injection layer and the hole transport layer were formed, a light emitting layer was deposited thereon as follows. After putting the following compound H-1 as a host in one cell of the vacuum deposition equipment, and putting compound D-1 as a dopant in another cell, respectively, the two materials are evaporated at different rates to form a dopant for the dopant and the host as a whole. A light emitting layer having a thickness of 40 nm was deposited on the second hole transport layer by doping at 15 wt%. Then, in two other cells, 2,4-bis(9,9-dimethyl-9H-fluoren-2-yl)-6-(naphthalen-2-yl)-1,3,5-triazine (compound ET-1) and lithium quinolate (compound EI-1) were evaporated at a rate of 5:5 to deposit an electron transport layer with a thickness of 35 nm on the light emitting layer in an amount of 50 wt%, respectively. Next, after depositing lithium quinolate (compound EI-1) to a thickness of 2 nm as an electron injection layer, an Al cathode was deposited to a thickness of 80 nm using another vacuum deposition equipment to manufacture an OLED device. For each material, each compound was purified by vacuum sublimation under 10 ^-6 torr.

As a result, a current of 1.8 mA/cm ² flowed, and green light emission of 1100 cd/m ² was confirmed.

[ comparative example 1] conventional organic electric field using luminescent compounds OLED device manufacturing

N-([1,1'-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl as the second hole transport layer )-9H-fluoren-2-amine (compound HT-1) was added and an OLED device was manufactured in the same manner as in Device Preparation Example 1 except for depositing to a thickness of 30 nm.

As a result, a current of 19.8 mA/cm ² flowed, and green light emission of 9000 cd/m ² was confirmed.

It was confirmed that the luminescent properties of the organic electroluminescent compounds developed in the present invention were superior to those of conventional materials. In addition, the device using the organic electroluminescent compound according to the present invention has good light emitting characteristics and lifespan characteristics.

Claims (6)

An organic electroluminescent compound represented by the following formula (1).
[Formula 1]

In Formula 1,
L ₁ is a single bond, a substituted or unsubstituted (C6-C30)arylene, or a substituted or unsubstituted (5-30 membered)heteroarylene;
X is O or S;
R ₁ and R ₂ are each independently a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (5-30 membered)heteroaryl;
R ₃ and R ₄ are each independently hydrogen, deuterium, halogen, substituted or unsubstituted (C1-C30)alkyl, substituted or unsubstituted (C6-C30)aryl, substituted or unsubstituted (5-30 membered) heteroaryl, substituted or unsubstituted (3-7 membered)heterocycloalkyl, or substituted or unsubstituted (C3-C30)cycloalkyl; It may be linked with an adjacent substituent (C3-C30) to form a monocyclic or polycyclic alicyclic or aromatic ring, wherein a carbon atom of the formed alicyclic or aromatic ring is replaced with one or more heteroatoms selected from nitrogen, oxygen and sulfur can be;
a and b are each independently an integer of 1 to 4, and when a or b is an integer of 2 or more, each R ₃ and each R ₄ may be the same or different;
said heteroaryl(ene) comprises one or more heteroatoms selected from B, N, O, S, P(=O), Si and P;
The heterocycloalkyl comprises one or more heteroatoms selected from O, S and N. The method according to claim 1, wherein in L ₁ and R ₁ to R ₄ , substituted (C1-C30)alkyl, substituted (C3-C30)cycloalkyl, substituted (3-7 membered)heterocycloalkyl, substituted (C6-C30) Substituents of aryl (ene) and substituted (5-30 membered) heteroaryl (ene) are each independently deuterium, 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 , (3-7 membered)heterocycloalkyl, (C6-C30)aryloxy, (C6-C30)arylthio, (C6-C30)aryl unsubstituted (3-30 membered)heteroaryl, (3 -30 member) heteroaryl-substituted or unsubstituted (C6-C30)aryl, tri(C1-C30)alkylsilyl, tri(C6-C30)arylsilyl, di(C1-C30)alkyl(C6-C30)aryl Silyl, (C1-C30)alkyldi(C6-C30)arylsilyl, amino, mono- or di- (C1-C30)alkylamino, mono- or di- (C6-C30)arylamino, (C1-C30) Alkyl(C6-C30)arylamino, (C1-C30)alkylcarbonyl, (C1-C30)alkoxycarbonyl, (C6-C30)arylcarbonyl, di(C6-C30)arylboronyl, di(C1 -C30)alkylboronyl, (C1-C30)alkyl(C6-C30)arylboronyl, (C6-C30)ar(C1-C30)alkyl and (C1-C30)alkyl(C6-C30)aryl At least one selected from the group consisting of, an organic electroluminescent compound. The method of claim 1, wherein L ₁ is a single bond, or a substituted or unsubstituted (C6-C12)arylene;
X is O or S;
R ₁ and R ₂ are each independently substituted or unsubstituted (C6-C20)aryl;
R ₃ and R ₄ are each independently hydrogen, substituted or unsubstituted (C1-C6)alkyl, substituted or unsubstituted (C6-C12)aryl, or substituted or unsubstituted (5-12 membered)heteroaryl; ;
a is 1;
b is an integer from 1 to 2; The method according to claim 1, wherein L ₁ is a single bond or an unsubstituted (C6-C12)arylene;
X is O or S;
R ₁ and R ₂ are each independently (C1-C6)alkyl, (C6-C15)aryl or (C6-C20)aryl unsubstituted or substituted with (5-15 membered)heteroaryl;
R ₃ and R ₄ are each independently hydrogen, unsubstituted (C1-C6)alkyl, unsubstituted (C6-C12)aryl, or unsubstituted (5-12 membered)heteroaryl;
a is 1;
b is an integer from 1 to 2; The organic electroluminescent compound according to claim 1, wherein the compound represented by Formula 1 is selected from the following compounds.

The organic electroluminescent device comprising the organic electroluminescent compound of claim 1 .