KR100525408B1 - organic electroluminescence device - Google Patents

Abstract

The present invention relates to an organic electroluminescent device using a blue light emitting material having excellent color purity, comprising a light emitting layer between an electron injection electrode (cathode) and a hole injection electrode (anode), wherein the light emitting layer is a blue light emitting material. It provides an organic electroluminescent device comprising a substance.

Description

Organic electroluminescence device

The present invention relates to an organic electroluminescent device, and more particularly, to an organic electroluminescent device comprising a compound having a structure of Formula 1 as a blue light emitting material of the organic light emitting layer.

(Wherein A ₁ and A ₂ may be each independently selected from a substituted or unsubstituted aromatic group, heterocyclic group, aliphatic group or hydrogen)

Recently, as the size of the display device increases, the demand for a flat display device having less space is increasing. As one of the flat display devices, an organic light emitting diode (OLED), also called an organic light emitting diode (OLED), has a high speed. It has been developed and several prototypes have already been announced.

An organic electroluminescent device is a device that emits light when electrons and holes are paired and then disappear when electrons are injected into an organic film formed between an electron injection electrode (cathode) and a hole injection electrode (anode). Not only can the device be formed on a flexible transparent substrate such as plastic, but it can also be driven at a lower voltage (less than 10V) compared to a plasma display panel or an inorganic electroluminescent (EL) display. In addition, it has the advantage of relatively low power consumption and excellent color. In addition, the organic electroluminescent (EL) device can display three colors of green, blue, and red, and thus, has become a target of many people as a next-generation rich color display device. However, the blue light emitting material in the conventional organic EL device has a disadvantage in that the color purity is low and the life thereof is short.

Meanwhile, looking at the general process of manufacturing the organic EL device,

(1) First, an anode material is coated on a transparent substrate. Indium tin oxide (ITO) is commonly used as the cathode material.

(2) Apply a hole injecting layer (HIL) on it. As the hole injection layer, copper phthalocyanine (CuPC) is mainly coated with a thickness of 10 nm to 30 nm.

(3) Next, a hole transport layer (HTL) is introduced. As the hole transport layer, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (4,4'-bis [N- (1-naphthyl) -N-phenthylamino] -biphenyl (NPB) is deposited by depositing about 30 nm to 60 nm.

(4) Form an organic emitting layer thereon. At this time, a dopant is added as necessary. For example, in the case of green light emission, tris (8-hydroxyquinolate) aluminum (Alq ₃ ) is used as the host, and MQD (N- is used as the dopant). Doping 1 ~ 2% of N-Meth ylquinacridone) or coumarin derivative forms a light emitting layer of about 20nm-40nm, and in the case of blue light emission, PBD, DPVBi and The same material is used, and as a dopant, materials such as perylene, coumarine and pyrene are usually doped by 1-3%.

(5) An electron transport layer (ETL) and an electron injecting layer (EIL) are successively coated thereon.

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On the other hand, Alq ₃ in the above (4) may have an electron injection and transport capability at the same time, and may not use an electron injection layer separately.

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(6) Next, a cathode is coated. At this time, in order to make electron injection easier, Al oxide is applied after thinly coating alkali oxides such as LiF and Li ₂ O. Finally, a protective shield is added.

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However, when using the above-mentioned conventional blue light emitting material in the process of fabricating an organic EL device, it is difficult to obtain deep blue and the light emission life is shortened toward shorter wavelengths. The development of deep blue materials is urgently needed.

Accordingly, an object of the present invention is to provide an organic electroluminescent device having improved light emission characteristics by synthesizing a new material with a blue light emitting material and excellent blue color purity.

In order to achieve the above object, the present invention is a general organic electroluminescent device consisting of a cathode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / anode, the material having the structure of It is used as a blue light emitting material.

[Formula 1]

Wherein A ₁ and A ₂ may be each independently selected from a substituted or unsubstituted aromatic group, heterocyclic group, aliphatic group or hydrogen. Particularly, in Formula 1, A ₁ and A ₂ may be substituted or unsubstituted. Phenyl, biphenyl, pyridyl, naphthyl, quinolyl, isoquinolyl, fluorenyl, terphenyl and Methyl, ethyl, propyl, isopropyl, t-butyl, and the like can be selected. In addition, at this time, the substituents substituted in A ₁ and A ₂ may each be one or more, alkyl (alkyl), alkoxy (alkyl), alkylamino (alkylamino), alkylsilyl (halogen), aryl (aryl) , Aryloxy, arylamino, arylsilyl may be selected from the group. For example, substituents of A1 and A2 include methyl, ethyl, propyl, isopropyl, t-butyl, cyclohexyl and methoxy. (methoxy), ethoxy, propoxy, butoxy, dimethylamino, diethylamino, trimethylsilyl, fluorine, chlorine, phenoxy , Tolyoxy, diphenylamino, triphenylsilyl may be selected. For example, substituted or unsubstituted A1 and A2 may be selected from materials having a structure such as Can be. The substance of the formula (1) having such substituents A ₁ and A ₂ has a structure such as the following formula (4). In addition, the light emitting material of Formula 1 may be used in combination with one or more other materials, when used in combination, the material is a mass% of 0.1 to 90% by mass based on the total weight of the light emitting layer.

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The material used by mixing together into the light emitting layer preferably has the following structure. B1-X-B2

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Wherein X may be selected from fused Aromatic compounds, in particular naphthalene, anthracene phenanthrene, pyrene, perylene and quinoline ) Can be selected from the group.

In addition, B1 and B2 may be selected from the group consisting of aryl, alkylaryl, alkoxyaryl, arylaminoaryl, alkylaminoaryl, and arylallyl groups, respectively. Especially, phenyl, biphenyl, pyridyl, naphthyl, tritylphenyl, biphenylenyl, anthryl, phenanthryl ), Pyrenyl, perylenyl, quinolyl, quinolyl, isoquinolyl, fluorenyl, terphenyl, tolyl, xylyl, Methylnaphthyl group and hydrogen.

For example, the following materials may be used as the material of Chemical Formula 2.

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N, N'-Bis- (4-tert-butyl-phenyl) -N, N'-di-pyridin-2-yl-pyrene among materials that can be used as a blue light emitting material in the organic electroluminescent device according to the present invention -1,6-diamine can be obtained according to the following method.

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1) Synthesis of 1,6-Dibromopyrene

First dissolve pyrene (10 g, 0.049 mol) in CCl ₄ (300 mL) in a three neck round bottom flask. Then, Br ₂ (17.38 g, 0.108 mol) and CCl ₄ (50 mL) were added to a dropping funnel installed in the round bottom flask, and the mixture was slowly added to the round bottom flask over 4 hours, and N ₂ was injected. Remove HBr. After dropping, the mixture was stirred for 1 hour under N ₂ stream, and when the reaction was completed, the resultant precipitate was filtered as it is, and the precipitate was recrystallized again using toluene to give a green solid of 1,6-Dibromopyrene (6.05g, 34%) and 1,8-Dibromopyrene (5 g, 28%) were obtained.

2) Synthesis of N, N, N ', N'-Tetraphenyl-pyrene-1,6-diamine

In a two-necked round bottom flask, 1,6-Dibromopyrene (3g, 0.0083mol) obtained in 1), Diphenylamine (4.23g, 0.029mol) and BINAP ([2,2'-bis (diphenylphosphino) -1,1 ' -binaphthyl]) (0.052g, 1% mol), Pd (OAC) 2 [Palladium (∥) acetate] (0.019g, 1% mol) and ^{NaO t Bu [Sodium tert-butoxide} ] (2.3g, 0.029mol) Was dissolved in toluene (80 mL) and refluxed for 24 hours (reflux). At the end of the reaction, the round bottom flask was cooled, 40 mL of toluene, the reaction solvent was removed, and methanol (100 mL) was added thereto to form a precipitate. The precipitate obtained was filtered to give a yellow solid of the desired N, N, N ', N'-Tetraphenyl-pyrene-1,6-diamine (3.22 g, 72%).

3) Synthesis of (4-Bromo-phenyl) -trimethyl-silane

First, a dropping funnel is installed in a three-necked round bottom flask and dried under reduced pressure. Then, 1,4-Dibromobenzene (12,7g, 0.053mol) and dried diethylether (300mL) were dissolved in a round bottom flask. After installing a dry ice bath, n-BuLi (33,58 mL, 0.0537 mol) was added to the dropping funnel and slowly added dropwise. After that, increase the temperature from -78 ° C to 0 ° C over 1 hour, and slowly drop Chloro trimethylsilane (7,51mL, 0.059mol) to it and raise the temperature to room temperature over 1 hour. After completion of the reaction, the mixture was extracted with water and diethylether, water was removed using MgSO ₄ , solvent was removed, and then distilled under reduced pressure (4-Bromo-phenyl) -trimethyl-silane (11.3g, 92%). )

4) Synthesis of (4-tert-Butyl-phenyl)-(4-trimethylsilanyl-phenyl) -amine

In a two-neck round bottom flask, 4-tert-Butyl-phenylamine (1.2 mL, 0.0076 mol), (4-Bromo-phenyl) -trimethyl-silane (1 g, 0.0044 mol) obtained from 3), BINAP (0.03 g, 1 % mol), Pd (OAc) ₂ (0.01 g, 1% mol) and NaO ^t Bu (1.5 g, 0.016 mol) are dissolved in toluene (50 mL) and refluxed for 24 hours. After the reaction was completed, the round bottom flask was cooled, the reaction solution was removed toluene, extracted with water and methylene chloride, water was removed with MgSO ₄ , methylene chloride was removed under reduced pressure, and hexane was used for silica gel short column. When precipitation occurs using ethanol and water, this can be filtered to obtain 4- (4-tert-Butyl-phenyl)-(4-trimethylsilanyl-phenyl) -amine (1.12 g, 86%) as a white solid.

5) Synthesis of N, N'-Bis- (4-tert-butyl-phenyl) -N, N'-bis- (4-trimethylsilanyl-phenyl) -pyrene-1,6-diamine

1,6-Dibromopyrene (0.787 g, 0.0022 mol) obtained in 1) and (4-tert-Butyl-phenyl)-(4-trimethylsilanyl-phenyl) -amine (1) obtained in 4) in a two-neck round bottom flask. , 56g, 0.00525mol), BINAP (0.054g, 4% mol), Pd (OAc) ₂ (0.015g, 3% mol) and NaO ^t Bu (0.93g, 0.0096mol) dissolved in toluene (40mL) Time to reflux. After the reaction was completed, the round bottom flask was cooled, the reaction solvent toluene was removed, extracted with water and methylene chloride, the water was removed with MgSO ₄ , the methylene chloride was removed under reduced pressure, and the silica gel chromatography was subjected to solvent hexane: methylene. Separate with chloride (6: 1). Then remove the solvent and filter the solid using hexane. N, N'-Bis- (4-tert-butyl-phenyl) -N, N'-bis- (4-trimethylsilanyl-phenyl ) -pyrene-1,6-diamine (1.09 g, 63%).

6) Synthesis of N, N'-Diphenyl-N, N'-di-pyridin-2-yl-pyrene-1,6-diamine

1,6-Dibromopyrene (1.2g, 0.0033mol), Phenyl-pyridin-2-yl-amine (1,36g, 0.008mol), BINAP (0.083g, 4% mol) obtained in 1) in a two-neck round bottom flask ), Pd (OAc) ₂ (0.022 g, 3% mol) and NaO ^t Bu (1.28 g, 0.013 mol) are dissolved in toluene (50 mL) and refluxed for 24 hours. At the end of the reaction a solid is produced. First, remove 50% of toluene, and then add methanol (70mL) and filter it to yellow solid N, N'-Diphenyl-N, N'-di-pyridin-2-yl-pyrene-1,6 -diamine (0.81g, 45%) is obtained.

7) Synthesis of (4-terr-Butyl-phenyl) -pyridin-2-yl-amine

4-tert-Butyl-phenylamine (1.2 mL, 0.0076 mol), 2-Bromo pyridine (1 mL, 0.01 mol), BINAP (0.06 g, 4% mol), Pd (OAc) ₂ (0.02 g) in a ₂ -neck round bottom flask , 3% mol) and NaO ^t Bu (1.5 g, 0.016 mol) are dissolved in toluene (50 mL) and refluxed for 24 hours. After the reaction is completed, the round bottom flask is cooled, the toluene, the reaction solvent, is removed, and extracted with water and methylene chloride. Remove water with MgSO ₄ , remove methylene chloride under reduced pressure, use silica gel short column with methylene chloride, and precipitate with hexane, filter it and filter it to white solid (4-tert-Butyl-phenyl) -pyridin 2-yl-amine (1.32 g, 73%) is obtained.

8) Synthesis of N, N'-Bis- (4-tert-butyl-phenyl) -N, N'-di-pyridin-2yl-pyrene-1,6-diamine

In a two-neck round bottom flask, (4-tert-Butyl-phenyl) -pyridin-2-yl-amine (1.51 g, 0.0067 mol) obtained from 1,6-Dibromopyrene (1 g, 0.0028 mol), 7), BINAP ( after 0.07g, 4% mol), Pd (OAc) 2 (0.02g, 3% mol) and NaO ^t Bu (1.18g, 0.012mol) was dissolved in toluene (45mL) and refluxed for 24 hours. At the end of the reaction a solid is produced. Remove 50% of toluene first, filter it by adding methanol (70mL), and remove the solvent by silica gel short column using methylene chloride. N, N'-Bis- (4-tert-butyl- Phenyl) -N, N'-di-pyridin-2-yl-pyrene-1,6-diamine (0.99g, 60%) can be obtained.

Hereinafter, the preferable aspect of the organic electroluminescent element which concerns on this invention is demonstrated to an Example.

Example

The light emitting area of the Indium Tin Oxide (ITO) (glass) substrate is patterned so as to have a size of 3 mm x 3 mm and then cleaned. After mounting the substrate in a vacuum chamber, the basic pressure was 1 × 10 ⁻⁶ torr, and then organic materials were placed on ITO, CuPC (200Å), NPB (500Å), light emitting layer (300Å), Alq ₃ (200Å), and LiF (5Å). Film formation in the order of Al (1000 mW). At this time, the following material (HOST-1) was used as the first HOST of the emission layer, and the material S-28 according to Chemical Formula 1 of the present invention was used as an impurity, and the mixing ratio of HOST-1 and S-28 was set to 1: 0.01. .

3.4 cd / A was obtained when 1 mA of current was flowed through the obtained light emitting layer, and CIE was x = 0.15 and y = 0.196.

In addition, other conditions were the same, and in the case of using S-26 according to Chemical Formula 1 of the present invention instead of S-28 as an impurity, 3.2 cd / A was obtained when a current of 1 mA was applied, where CIE was x = 0.146, y = 0.205.

2. Comparative Example

The light emitting area of the ITO substrate (glass) was patterned to have a size of 3 mm x 3 mm and then washed. After mounting the substrate in a vacuum chamber, the basic pressure was 1 × 10 ⁻⁶ torr, and then organic materials were placed on ITO, CuPC (200Å), NPB (300Å), light emitting layer (host-1: 200Å), and Alq ₃ (400Å). The film was formed in the order of LiF (5 kV) and Al (1000 kV). 1.8 cd / A at 1 mA, where CIE showed x = 0.194 and y = 0.297.

The present invention can obtain an organic electroluminescent device having a high color purity of blue by using a compound having a high color purity as described above as a blue light emitting material of the organic light emitting body.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (11)

An organic electroluminescent device comprising a light emitting layer between an electron injection electrode (cathode) and a hole injection electrode (anode), the organic light emitting device comprising a material represented by the following formula (1) as a blue light emitting material of the light emitting layer : [Formula 1] Wherein A ₁ and A ₂ are each independently a substituted or unsubstituted aromatic group of C ₆ -C ₂₀ or a heterocyclic group of C ₅ -C ₁₉ comprising N, S or O. delete The method of claim 1, An organic electroluminescent device, characterized in that the light emitting layer is used by mixing the material of Formula 1 and the material of Formula 2: [Formula 2] B1-X-B2 Wherein X is selected from the group consisting of naphthalene, anthracene and phenanthrene, and B1 and B2 are each independently C ₆ -C ₂₅ aryl, C ₆ -C ₂₅ alkylaryl, C ₆ -C ₂₅ aryl Aminoaryl and C ₆ -C ₂₅ arylallyl group). delete delete The method of claim 3, wherein An organic EL device, characterized in that the material of Formula 2 is any one of the following: delete The method of claim 1, One or more substituents substituted for A1 and A2 are each C ₁ -C ₁₀ alkyl, C ₁ -C ₁₀ alkoxy, C ₁ -C ₁₀ alkylamino, C ₁ -C ₁₀ alkylsilyl, halogen , An organic electric field selected from the group consisting of C ₆ -C ₁₀ aryl, C ₆ -C ₁₀ aryloxy, C ₆ -C ₁₀ arylamino, C ₆ -C ₁₀ arylsilyl group and hydrogen Light emitting element. delete delete The method of claim 1, An organic EL device, characterized in that the material of Formula 1 is any one of the following: : .