KR100683659B1 - Carbazole ring-containing compound and organic electroluminescent device using same - Google Patents

Abstract

The carbazole ring-containing compound according to the present invention has excellent blue light emitting property or hole transporting property, which can be used as a blue light emitting material or as a host for various phosphorescent or fluorescent dopants such as red, green, blue, white and the like. . The organic electroluminescent device employing such a carbazole ring-containing compound can emit light with high efficiency and has low power consumption.

Description

Carbazole ring containing compound and organic electroluminescence display device using the same

1 is a cross-sectional view showing the structure of a general organic electroluminescent device,

Figure 2 shows the UV spectrum of the compound of formula 3 obtained according to Synthesis Example 1 of the present invention,

3 shows the PL spectrum of the compound of Formula 3 obtained according to Synthesis Example 1 of the present invention,

Figure 4 shows the PL spectrum of the compound of formula 3 and CBP obtained according to Synthesis Example 1 of the present invention.

The present invention relates to a carbazole ring-containing compound and an organic electroluminescent device using the same, and more particularly, to a blue light emitting host compound and an organic electroluminescent device using the same.

The light emitting material of the organic electroluminescent device is classified into a fluorescent material using excitons in a singlet state and a phosphorescent material using a triplet state according to its light emitting mechanism. Phosphorescent materials generally have a structure of organometallic compounds containing heavy atoms, and the heavy atoms cause excitons in the triplet state, which were originally forbidden transitions, to emit light through an allowable transition. Phosphorescent materials can use triplet excitons with 75% probability of production and can have much higher luminous efficiency than fluorescent materials using 25% singlet excitons.

A light emitting layer using a phosphorescent material is composed of a host material and a dopant material which emits light by transferring energy therefrom. Various materials using an iridium metal compound have been reported as dopant materials. In particular, blue light emitting materials have been developed based on (4,6-F ₂ ppy) ₂ Irpic or fluorinated ppy ligand structure, and the host material of these materials is CBP (4,4'-N, N '-dicarbazole-biphenyl) materials are used a lot. CBP molecules have sufficient energy transfer in the triplet energy band gap for green and red materials but are less than the energy gap for blue materials, so materials such as skyblue (4,6-F2ppy) ₂ Irpic with PL = 475 nm In addition, it is reported that very inefficient exothermic transition occurs rather than exothermic energy transition. As a result, the CBP host is pointed out as a cause of problems of low blue light emission efficiency and short lifespan due to insufficient energy transfer to the blue dopant. Recently, mCP (m-CarbazolePhenyl) compounds having a triplet energy gap larger than CBP have been used, but this molecule has problems such as low molecular weight and poor stability. Therefore, in order to obtain high-efficiency long-life blue light emission characteristics, it is very important and urgent to secure a host material with a triplet energy gap larger than that of CBP, which enables efficient energy transfer to a blue dopant.

The technical problem to be achieved by the present invention is to analyze the problems of the existing blue phosphorescent host material in order to solve the problems presented above, having a triplet energy gap larger than CBP and efficient energy transfer to the blue dopant is effective blue phosphorescence To provide a host.

Another object of the present invention is to provide an organic electroluminescent device employing the blue phosphorescent host.

[화학식 2A]

상기식중, R₁, R₂, R₃ 및 R₄는 서로 독립적으로 C1-C30의 알킬기, 할로겐 원자, C1-C30의 알콕시기, C1-C30의 알킬카르보닐기, C2-C30의 알킬카르복실기, C6-C30의 아릴기, C6-C30의 치환 또는 비치환된 아릴알킬기, C6-C30의 아릴카르보닐기, C7-C30의 아릴카르복실기, C2-C30의 헤테로아릴기, C2-C30의 헤테로아릴알킬기, C2-C30의 헤테로아릴카르보닐기, C4-C30의 사이클로알킬기, 시아노기, 아미노기, C1-C30의 알킬아미노기로 이루어진 군으로부터 선택되고,
R'과 R"은 서로 독립적으로 일치환(mono-sybstituted) 또는 다치환(multi-substituted) 작용기로서, 수소, 탄소수 1 내지 30의 알킬기, 탄소수 1 내지 30의 알콕시기, 탄소수 4 내지 30의 사이클로알킬기, 탄소수 6 내지 30의 아릴기, C6-C30의 아릴알킬기, 탄소수 6 내지 30의 치환 또는 비치환된 아릴옥시기, 탄소수 2 내지 30의 헤테로아릴기, 탄소수 3 내지 30의 헤테로아릴알킬기, 탄소수 2 내지 30의 헤테로아릴옥시기, 탄소수 6 내지 30의 축합 다환기, 아미노기, 탄소수 1 내지 30의 알킬아미노기, 탄소수 6 내지 30의 아릴아미노기, 시아노기, 니트로기, 하이드록시기, 할로겐 원자, 탄소수 6 내지 30의 아릴 술포닐기 또는 탄소수 1 내지 30의 알킬 술포닐기를 나타낸다. In order to achieve the first technical problem, the present invention provides a carbazole ring-containing compound represented by Formula 2 or Formula 2A.
[Formula 2]

[Formula 2A]

In the above formula, R ₁ , R ₂ , R ₃ and R ₄ are each independently of the C 1 -C 30 alkyl group, halogen atom, C 1 -C 30 alkoxy group, C 1 -C 30 alkylcarbonyl group, C 2 -C 30 alkylcarboxyl group, C 6 -C30 aryl group, C6-C30 substituted or unsubstituted arylalkyl group, C6-C30 arylcarbonyl group, C7-C30 arylcarboxyl group, C2-C30 heteroaryl group, C2-C30 heteroarylalkyl group, C2- C30 heteroarylcarbonyl group, C4-C30 cycloalkyl group, cyano group, amino group, C1-C30 alkylamino group,
R 'and R "are independently mono-sybstituted or multi-substituted functional groups, hydrogen, an alkyl group of 1 to 30 carbon atoms, an alkoxy group of 1 to 30 carbon atoms, a cycloalkyl of 4 to 30 An alkyl group, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a heteroaryl group having 2 to 30 carbon atoms, a heteroarylalkyl group having 3 to 30 carbon atoms, and carbon atoms Heteroaryloxy group having 2 to 30 carbon atoms, condensed polycyclic group having 6 to 30 carbon atoms, amino group, alkylamino group having 1 to 30 carbon atoms, arylamino group having 6 to 30 carbon atoms, cyano group, nitro group, hydroxy group, halogen atom, carbon number 6-30 aryl sulfonyl group or C1-C30 alkyl sulfonyl group is shown.

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Another technical problem of the present invention is an organic electroluminescent device comprising an organic film between a pair of electrodes,

The organic film is made of an organic electroluminescent device comprising the carbazole ring-containing compound described above.

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The carbazole ring-containing compound according to the present invention is particularly preferably a compound represented by the formula (2).

[Formula 2]

Wherein R ₁ , R ₂ , R ₃ , R ₄ , R 'and R "are as described above.
In Formula 2 or Formula 2A, R ₁ , R ₂ , R _3, and R ₄ are the same as or different from each other, and preferably an alkyl group of C 1 -C 12.

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Carbazole ring-containing compounds represented by the above-described formula (2) or (2A) complement the problems of energy transfer due to the low sublimation point of the conventional mCP structure and the low energy bandgap, which is a disadvantage of the CBP structure. By introducing a substituent having a bulky structure in the phenylene group to prevent stacking, it is possible to reduce the exciton interaction, thereby suppressing crystallization and increasing the film stability. For example, the compound represented by Formula 2 increases the energy gap of triplet discharging by opening a torsion angle between biphenyls by introducing a substituent such as a methyl group at an ortho position in a biphenyl group of CBP. This increased triplet energy gap has a larger energy value than that of a conventional blue dopant, so that energy transition from the host to the dopant occurs efficiently. As such, when the energy transfer between the host and the dopant occurs efficiently, the luminous efficiency is improved. The carbazole ring-containing compound of the above formula is useful as a phosphorescent and fluorescent host material as a blue light emitting material.

As an example of the compound of Formula 2 or 2A, R ₁ , R ₂ , R ₃ and R ₄ are all -CH ₃ , and R 'and R "are all hydrogen, -CH ₃ , -CF ₃ or a phenyl group , The compounds represented by the following Chemical Formulas 3 to 6, the compounds represented by the Chemical Formulas 9, 10, or 12, and the like.

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CBP

본 발명은 또한 하기 화학식 7, 8, 11, 13 또는 15로 표시되는 카바졸 화합물을 제공한다

The present invention also provides a carbazole compound represented by the following Chemical Formula 7, 8, 11, 13 or 15

Specific examples of the unsubstituted C1-C30 alkyl group used in the chemical formula of the present invention include methyl, ethyl, propyl, isobutyl, sec-butyl, pentyl, iso-amyl, hexyl and the like, and at least one of the alkyl groups The hydrogen atom is a halogen atom, hydroxy group, nitro group, cyano group, amino group, amidino group, hydrazine, hydrazone, carboxyl group or salt thereof, sulfonic acid group or salt thereof, phosphoric acid or salt thereof, alkyl group of C1-C30, C1-C30 Alkenyl group, C1-C30 alkynyl group, C6-C30 aryl group, C7-C30 arylalkyl group, C2-C20 heteroaryl group, or C3-C30 heteroarylalkyl group can be substituted.

Specific examples of the unsubstituted C1-C30 alkylcarbonyl group used in the chemical formula of the present invention include acetyl, ethylcarbonyl, isopropylcarbonyl, phenylcarbonyl, naphthalenecarbonyl, diphenylcarbonyl, cyclohexylcarbonyl and the like. And at least one hydrogen atom of these alkylcarbonyl groups can be substituted with the same substituent as in the alkyl group described above.

Specific examples of the unsubstituted C1-C30 arylcarbonyl group used in the chemical formula of the present invention include phenylcarbonyl, naphthalenecarbonyl, diphenylcarbonyl, and the like, and at least one hydrogen atom among these arylcarbonyl groups may be Substituents similar to those of the alkyl group can be substituted.

Specific examples of the unsubstituted C1-C30 alkoxy group used in the chemical formula of the present invention include methoxy, ethoxy, phenyloxy, cyclohexyloxy, naphthyloxy, isopropyloxy, diphenyloxy, and the like. At least one hydrogen atom of these alkoxy groups may be substituted with the same substituent as in the alkyl group described above.

Unsubstituted aryl groups used in the formulas of the present invention may be used alone or in combination to mean 6 to 30 aromatic carbon rings containing one or more rings, which rings may be attached or fused together in a pendant manner. Can be. Examples of aryl include phenyl, naphthyl, tetrahydronaphthyl and the like. At least one hydrogen atom in the aryl group may be substituted with the same substituent as in the alkyl group described above.

Examples of the unsubstituted aryloxy group used in the chemical formula of the present invention include phenyloxy, naphthyleneoxy, diphenyloxy and the like. At least one hydrogen atom of the aryloxy group may be substituted with the same substituent as in the alkyl group described above.

The unsubstituted arylalkyl group used in the formula of the present invention means that some of the hydrogen atoms in the aryl group as defined above are substituted with lower alkyl groups such as methyl, ethyl, propyl and the like. For example benzyl, phenylethyl and the like. At least one hydrogen atom of the arylalkyl group may be substituted with the same substituent as in the alkyl group described above.

The unsubstituted heteroaryl group used in the present invention includes 1, 2 or 3 heteroatoms selected from N, O, P or S, and the remaining ring atoms are C 1 to monovalent monocyclic monocyclic or 6 to 30 ring atoms or By bicyclic aromatic divalent organic compound is meant. Examples of heteroaryl groups include thienyl, pyridyl, furyl and the like. At least one hydrogen atom of the heteroaryl group may be substituted with the same substituent as in the alkyl group described above.

The unsubstituted heteroaryloxy group used in the present invention means that oxygen is bonded to the heteroaryl group as defined above. For example benzyloxy, phenylethyloxy and the like. At least one hydrogen atom of the heteroaryloxy group may be substituted with the same substituent as in the alkyl group described above.

Examples of the unsubstituted arylalkyloxy group used in the present invention include a benzyloxy group and the like, and at least one hydrogen atom of the aralkyloxy group may be substituted with the same substituent as in the alkyl group described above.

The unsubstituted heteroarylalkyl group used in the present invention means that a part of the hydrogen atoms of the heteroaryl group is substituted with an alkyl group. At least one hydrogen atom of the heteroarylalkyl group may be substituted with the same substituent as in the alkyl group described above.

Examples of the unsubstituted cycloalkyl group used in the present invention include a cyclohexyl group, a cyclopentyl group, and the like, and at least one hydrogen atom of the cycloalkyl group may be substituted with the same substituent as in the alkyl group described above.

Examples of the dialkylamino group used in the present invention include a dimethylamino group and the like, and at least one hydrogen atom of the dialkylamino group may be substituted with the same substituent as in the case of the alkyl group described above.

Hereinafter, a method of manufacturing an organic EL device employing an organic film using a carbazole ring-containing compound represented by Formula 2 or 2A of the present invention will be described.

1 is a cross-sectional view showing the structure of a general organic EL device.

First, an anode electrode is formed by coating an anode electrode material on the substrate. Herein, a substrate used in a conventional organic EL device is used, and an organic substrate or a transparent plastic substrate having excellent transparency, surface smoothness, ease of handling, and waterproofness is preferable. In addition, transparent indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), and zinc oxide (ZnO) are used as the anode electrode material.

The hole injection layer (HIL) is formed by vacuum-heat deposition or spin coating the hole injection layer material on the anode electrode. The hole injection layer material is not particularly limited and CuPc or Starburst type amines TCTA, m-MTDATA, and m-MTDAPB may be used as the hole injection layer.

A hole transport layer (HTL) is formed by vacuum-heat deposition or spin coating of the hole transport layer material on the hole injection layer. The hole transport layer material is not particularly limited, and N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1-biphenyl] -4,4'-diamine (TPD), N, N'-di (naphthalen-1-yl) -N, N'-diphenyl benzidine, N, N'-di (naphthalene-1-yl) -N, N'-diphenyl-benxidine: α-NPD) Etc. are used.

Subsequently, an emission layer (EML) is introduced over the hole transport layer, and the emission layer material is not particularly limited, and the compound of Formula 1 may be used alone or as a host. In the case of the dopant used as the light emitting host, as the fluorescent dopant, IDE102 and IDE105, which are available from Idemitsu, are used. The phosphorescent dopant is Ir (ppy) ₃ (ppy is a phenylpyridine compound). (Green), (4,6-F2ppy) ₂ Irpic (reference: Chihaya Adachi etc. Appl. Phys. Lett ., 79, 2082-2084, 2001), PtOEP (platinum (II) octaethylporphyrin), etc. use.

The light emitting layer forming method may vary depending on the light emitting layer material, and for example, a co-thermal deposition method is used.

The content of the dopant is preferably 0.1 to 20 parts by weight, particularly 0.5 to 12 parts by weight, based on 100 parts by weight of the light emitting layer forming material (ie, 100 parts by weight of the total weight of the compound of Formula 2 or 2A as a host and dopant). If the content of the dopant is less than 0.1 parts by weight, the effect of addition is insignificant, and if it exceeds 20 parts by weight, concentration phosphorescence or fluorescence, such as concentration quenching (quenching) is not preferable because it occurs.

An electron transport layer (ETL) is formed on the light emitting layer by vacuum deposition or spin coating. It does not restrict | limit especially as an electron carrying layer material, Alq3 can be used. In addition, in the case of using the phosphorescent dopant in the light emitting layer, the hole blocking material is further vacuum-heat-deposited to form a hole blocking layer in order to prevent the triplet excitons or holes from diffusing into the electron transport layer. At this time, the hole blocking material is not particularly limited, but should have ionization potential higher than that of the light emitting compound while having electron transport ability, and typically, Balq and BCP are used. In addition, an electron injection layer (EIL) may be selectively stacked on the electron transport layer, which does not particularly limit the material. As the electron injection layer forming material, materials such as LiF, NaCl, CsF, Li ₂ O, and BaO may be used. Then, the organic EL device is completed by forming a cathode electrode by vacuum-heat-depositing a cathode forming metal on the electron injection layer. The metal for forming the cathode may be lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lidium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver ( Mg-Ag) and the like are used. In addition, a transmissive cathode using ITO and IZO may be used to obtain a front light emitting device.

In the organic electroluminescent device of the present invention, one or two intermediate layers may be further formed on the anode electrode, the hole injection layer, the hole transport layer, the light emitting layer, the hole blocking layer, the electron transport layer, the electron injection layer, and the cathode electrode as necessary. .

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited only to the following examples.

If possible, it is preferable to describe the synthesis examples of the compounds of the formulas (4) to (6) and these structural confirmation data.

Synthesis Example 1 Synthesis of Compound of Formula 3

1) Synthesis of Compound (A)

CuI (0.02 mmol), K ₃ PO ₄ (potassium phosphate tribasic monohydrate) (2.1 mmol), carbazole (2.2 mmol), and 1,4-dioxane (15 mL) were added to the sealed tube, followed by stirring for 30 minutes. Then, 3,5-dibromo toluene, (+,-)-trans-1,2-diaminocyclohexane (0.2 mmol) was added. Subsequently, the cap of the sealing tube was closed and stirred at 110 ° C. for about 24 hours.

After confirming that the reaction of the reaction mixture was completed by TLC, the solvent was removed by high vacuum distillation. Then, the reaction product was extracted with methylene chloride, and the extracted methylene chloride layer was washed with saturated aqueous NaCl solution. The extracted methylene chloride solution was removed with water with MgSO ₄ and subjected to a fresh column (hexane) to give a solid material. The solid material thus obtained was dried for about 3 hours under a vacuum pump to obtain compound (A). (Yield: 90%)

1) Synthesis of Compound (B)

To compound (A) (1 mmol) was added n-butyllithium (1.2 mmol) at −78 ° C. and 20 minutes later trimethylborate (2 mmol) was added.

After confirming the reaction by TLC, the solvent was removed by high vacuum distillation and extracted with 100 ml of methylene chloride. The extracted methylene chloride layer was washed with saturated aqueous NaCl solution. The extracted methylene chloride solution was removed with water with MgSO _{4 and} then subjected to a fresh column (fresh column) to obtain a solid material and dried for about 3 hours under a vacuum pump to obtain a compound (B). Yield is 50%.

1) Preparation of the compound of Formula 3

Compound (A) and compound (B) were added with Pd (PPh ₃ ) ₄ and sodium carbonate, and heated at 180 (C for 24 hours.

After confirming the reaction by TLC, the reaction was completed, the solvent was removed by high vacuum distillation and extracted with methylene chloride. The extracted methylene chloride layer was washed with a saturated aqueous NaCl solution, and then water was removed with a MgSO ₄ desiccant, followed by a fresh column to obtain a solid material. The compound was then dried under a vacuum pump for about 3 hours. (Yield: 50%)

¹ H-NMR (CDCl ₃ , 300 MHz): δ (ppm) 2.27 (d, J = 7.71, 4H) 7.50 to 7.39 (m, 8H) 7.34 to 7.22 (m, 4H), 7.125 (d, J = 21, 4H) 2.28 (s, 6H), 1.98 (s, 6H)

UV spectra and PL spectra of the compound of Formula 1 obtained according to Synthesis Example 1 are shown in FIGS. 2 and 3, respectively.

2 and 3 show the PL wavelength of blue wavelength showing the high energy level that the blue phosphorescent organic electroluminescent host should have. From the above facts, it can be seen that the blue phosphorescent host exhibits an appropriate absorption and emission wavelength.

Example 1

Corning's 10 Ω / cm 2 ITO substrate was used as an anode, and an IDE406 (Idemitsu Corp.) was vacuum deposited on the substrate to form a hole injection layer having a thickness of 600 mm 3. Subsequently, the IDE320 (Idemitsu Co., Ltd.) was vacuum deposited to a thickness of 300 kPa on the hole injection layer to form a hole transport layer. The light emitting layer was formed on the hole transport layer by vacuum deposition of a compound represented by the formula (3) in a 90:10 mixed weight ratio and (4,6-F2ppy) ₂ Irpic by vacuum deposition.

Thereafter, BAlq was vacuum-deposited on the emission layer to form an HBL layer having a thickness of 50 kHz. Thereafter, Alq3 was vacuum deposited on the emission layer to form an electron transport layer having a thickness of 200 kHz. An organic electroluminescent device was completed by forming a cathode by vacuum evaporation of LiF 10kV and Al 3000kV sequentially on the electron transport layer.

In the organic EL device manufactured according to Example 1, luminance, efficiency, driving voltage, and color purity characteristics were investigated.

Comparative Example 1

Corning's 10 Ω / cm 2 ITO substrate was used as an anode, and CuPc was vacuum deposited on the substrate to form a hole injection layer having a thickness of 600 μs. Subsequently, the NPB was vacuum deposited on the hole injection layer to a thickness of 300 GPa to form a hole transport layer. Compound (4,6-F2ppy) ₂ Irpic and the compound represented by the conventional CBP of 90:10 mixed weight ratio on the hole transport layer by vacuum deposition to form a light emitting layer with a thickness of 300Å.

Thereafter, BAlq was vacuum-deposited on the emission layer to form an HBL layer having a thickness of 50 kHz. Thereafter, Alq3 was vacuum deposited on the emission layer to form an electron transport layer having a thickness of 200 kHz. An organic electroluminescent device was completed by forming a cathode by vacuum evaporation of LiF 10kV and Al 3000kV sequentially on the electron transport layer.

In the organic electroluminescent devices of Example 1 and Comparative Example 1, the driving voltage, brightness, efficiency and color purity characteristics were examined and shown in Table 1 below.

TABLE 1

division Driving voltage (V) Luminance (cd / m ² ) Efficiency (cd / A) Color purity Example 1 6 450 5.0 (0.15, 0.22) Comparative Example 1 6 400 4.5 (0.15, 0.32)

From Table 1, it was confirmed that the organic EL device of Example 1 had the same driving voltage as in Comparative Example 1, but improved luminance, efficiency, and color purity characteristics.

The carbazole ring-containing compound according to the present invention has excellent blue light emitting property or hole transporting property, which can be used as a blue light emitting material or as a host for various phosphorescent or fluorescent dopants such as red, green, blue, white and the like. . The organic electroluminescent device employing such a carbazole ring-containing compound can emit light with high efficiency and has low power consumption.

Claims (14)

delete delete delete delete Carbazole ring-containing compound, characterized in that the compound of formula (9), compound of formula (10) or compound represented by formula (12). [Formula 9]

[Formula 10]

[Formula 12]

In an organic electroluminescent device comprising an organic film between a pair of electrodes, The organic electroluminescent device comprising the carbazole ring-containing compound according to claim 5. The organic electroluminescent device according to claim 6, wherein the organic film is a light emitting layer. The organic electroluminescent device according to claim 6, wherein the light emitting layer further comprises phosphorescent or fluorescent dopants in the visible region. 7. The method of claim 6, wherein the organic film is a hole injection layer or a hole transport layer. Organic electroluminescent element made with gong. delete delete delete delete delete

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