KR100861121B1 - Organic metal complex for organic emitting layer and organic light emitting diode - Google Patents

Abstract

An organometallic complex and an organic light emitting diode for an organic light emitting layer are provided.

The organic light emitting diode according to the present invention has an effect of excellent current efficiency and power efficiency and lifespan when compared to a device using BAlq by using a substance in which a naphthalene derivative is introduced as a ligand as a phosphorescent host.

Description

Organic metal complex for organic light emitting layer and organic light emitting diode manufactured using the same {Organic metal complex for organic emitting layer and organic light emitting diode}

1 is a schematic diagram of an organic light emitting diode according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: substrate 20: anode

30: hole injection layer 40: hole transport layer

50: organic light emitting layer 60: electron transport layer

70: electron injection layer 80: cathode

The present invention relates to an organic metal complex for an organic light emitting layer, and more particularly, to an organic metal complex for an organic light emitting layer having excellent efficiency and lifespan, and an organic light emitting diode manufactured using the same.

Recently, as the size of the display device increases, the demand for a flat display device having a small space is increasing. A liquid crystal display, which is a typical flat display device, has an advantage of being lighter than a conventional CRT, but has a limited viewing angle. It has disadvantages such as the need for back light. In contrast, the organic light emitting diode (OLED), a new flat panel display device, is a display using a self-luminous phenomenon, and has a large viewing angle, can be thinner and shorter than a liquid crystal display, and has a fast response speed. Have.

Representative organic light-emitting diodes have been restricted to use in various applications since their performance limitations since they were announced by Gurnee in 1969 (US3,172,862, US3,173,050), but in 1987, Eastman Kodak Corporation (Eastman) Kodak Co., Ltd. after the multi-layered organic light emitting diode (CW Tang et al., Appl. Phys. Lett., 51, 913 (1987); J. Applied Phys., 65, 3610 (1989)) Overcoming the problem has been a rapid development. Currently, organic light emitting diodes have excellent characteristics such as low driving voltage (e.g., 10V or less), wide viewing angle, high-speed response, and high contrast compared to plasma display panel (PDP) or inorganic light emitting display. It can be used as a pixel of a display, as a pixel of a television image display or a surface light source, to form a device on a flexible transparent substrate, to be made very thin and light, and to have color As a result, it is emerging as a suitable device for the next generation flat panel display (FPD).

The organic light emitting diode injects electrons and holes into the organic light emitting layer formed between the first electrode (anode), which is a hole injection electrode (anode), and the second electrode (cathode), which is an electron injection electrode (cathode), respectively. Excitons, which are formed in pairs, disappear from the excited state to the ground state and extinguish and emit light. In this case, the excited state falls to the ground state through the singlet excited state and emits light. It is called (fluorescence), and it is called phosphorescence (phpsphorescence) to emit light while falling to the ground state through a triplet excited state. In the case of fluorescence, since the singlet excited state probability is 25%, there is a limit in luminous efficiency, whereas the triplet using phosphorescence can use up to 75% excited state and up to 25% singlet excited state. Up to 100% quantum efficiency is possible. As a luminescent material using triplet, phosphorescent materials using iridium or platinum metal compound were presented by Princeton University, University of Southern California, etc. [Sergey Lamansky etc. Inorg. Chem., 40, 1704-1711, 2001 and J. Am. Chem. Soc., 123, 4304-4312, 2001] Recently, due to the need for a high-efficiency, high-life material required for large screen implementation, the development of phosphorescent materials and devices using the same have been increasing.

Phosphorescent hosts commonly used include CBP (4, 4′-N, N′-dicarbazolbiphenyl), BAlq (((1,1'-biphenyl) -4-olato) bis (2-methyl-8-quinolino lato N1, O8) aluminum), BCP (2,9-dimethyl-4,7-diphenyl -1,10-phenanthroline), among which BAlq is a hole transport layer NPB (N, N'-diphenyl-NN) In the case of using -bis (1-naphthyl) -1, 1'-biphenyl) -4, 4'-diamine, and Alq ₃ as the electron transport layer, because of the appropriate energy level characteristics and the ability of charge transfer, CBP It is the most commonly used host material for phosphorescence.

U.S. Patent Publication No. US2003 / 0129452 lists aluminum complexes as phosphorescent host materials, and states that the lifetime can be improved when the ionization potential energy difference between the host material and the hole transport layer is 0.4 to 0.8 eV. There is a problem in that the efficiency is poor, and the service life can not be secured for a long time.

Accordingly, the technical problem to be achieved by the present invention is to provide an organic metal complex for an organic light emitting layer of an organic light emitting diode having high efficiency and excellent lifespan.

The second technical problem to be achieved by the present invention is to provide an organic light emitting diode comprising the organometallic complex for the organic light emitting layer.

The present invention to achieve the first technical problem,

It provides an organometallic complex for an organic light emitting layer of the formula (1).

(Wherein R ₁ to R ₁₂ are each hydrogen, amino, alkyl having 1 to 10 carbon atoms, alkenyl having 2 to 10 carbon atoms, alkynyl having 2 to 10 carbon atoms or alkoxy having 1 to 10 carbon atoms,

또는

이며,L is

or

Is,

R ₂₁ to R ₂₇ each represent hydrogen, amino, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, or a heteroaryl group containing N, S, and O having 4 to 19 carbon atoms, wherein R ₂₁ to R ₂₇ At least one of is a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or a heteroaryl group containing N, S, O having 4 to 19 carbon atoms, a substituent when at least one of R ₂₁ to R ₂₇ is substituted Is alkyl having 1 to 10 carbon atoms, alkoxy having 1 to 10 carbon atoms, cyano, alkylamino having 1 to 10 carbon atoms, alkylsilyl having 1 to 10 carbon atoms, halogen, aryl having 6 to 10 carbon atoms, and aryloxy having 6 to 10 carbon atoms. , Arylamino having 6 to 10 carbon atoms, arylsilyl having 6 to 10 carbon atoms.

According to an embodiment of the present invention, the organometallic complex for the organic light emitting layer may be any one selected from the group represented by the following formula (2).

According to a preferred embodiment of the present invention, the organometallic complex for the organic light emitting layer may be any one selected from the group represented by the following formula (3).

The present invention to achieve the second technical problem,

In an organic electroluminescent diode comprising an anode, an organic light emitting layer and a cathode, the organic light emitting layer provides an organic light emitting diode comprising an organometallic complex represented by the formula (1).

According to an embodiment of the present invention, the organic light emitting diode may include an iridium complex as a dopant of the organic light emitting layer.

The iridium complex is

또는

일 수 있다.

or

Can be.

According to another embodiment of the present invention, the amount of the dopant is preferably 0.1 to 30% by weight of the organometallic complex.

In the organic light emitting diode according to the present invention, a hole transport layer may be further stacked between the anode and the organic light emitting layer, and an electron transport layer may be further stacked between the cathode and the organic light emitting layer.

In addition, the hole injection layer may be further laminated on the lower portion of the hole transport layer.

In addition, the electron injection layer may be further stacked on top of the electron transport layer.

According to another embodiment of the present invention, the hole transport layer is N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1-biphenyl] -4,4'-diamine ( TPD) or N, N'-di (naphthalen-1-yl) -N, N'-diphenyl benzidine (α-NPD).

According to a preferred embodiment of the present invention, the hole injection layer may include CuPc, TCTA or m-MTDATA.

Hereinafter, the present invention will be described in more detail.

The organometallic complex for an organic light emitting layer according to the present invention is characterized in that it is possible to greatly improve the efficiency and lifetime of the organic light emitting diode using the bulk packing property by modifying the existing BAlq derivatives.

The organic light emitting layer used in the present invention employs a host-dopant system based on an energy transfer principle of doping a dopant to a host, and in the host-dopant system, in order to be used as an effective light emitting dopant and a charge transport host, Overall harmony of properties such as high PL efficiency, no chemical degradation during deposition, balanced energy injection and transport, adequate energy level, molecular stability, and structurally stable film Should be done. These properties are determined not only by the optical and electrical properties of the molecules, but also by the bulk packing of the molecules formed by vapor deposition. Therefore, the lifetime and efficiency of the device may be determined by optical and electrical properties of the organic light emitting layer host and the dopant and bulk packing properties of molecules formed by vapor deposition.

In the case of the conventional BAlq, the electron density of Homo is concentrated in the phenol ring of isoquinoline ligand, whereas Lumo is concentrated in the pyridylation of isoquinoline ligand. It may cause a change in the electronic structure or adversely affect the overlap between the phenol ring and pyridyl, thereby reducing the charge mobility. In addition, the possibility of aluminum reacting with oxygen and other materials cannot be excluded. In order to exclude the above problems, it is appropriate to use a ligand that can protect aluminum from the outside through the steric effect. As such ligands, ligands of various structures such as anthracene, pyrene, and perylene can be used, but it is considered that the larger the ligand size, the easier the protective effect. However, when the ligand is too large, bond formation is impossible due to steric effect or isoquinoline. It is likely to affect the binding of. Therefore, in the present invention, in order to eliminate the above problems, by introducing a naphthalene group, which is judged to be an appropriate size instead of biphenyl, without modifying the substituent of the isoquinoline ligand, life expectancy improvement by the protective effect of aluminum can be expected. have. In addition, in the case of substituting a simple naphthalene ring, the intermolecular Π-Π stacking may not be easy due to the steric effect. Thus, by introducing a separate aromatic ring in the naphthalene ring to facilitate Π-Π stacking, the Π-Π It is possible to improve the bulk packing characteristics by increasing the stacking, thereby achieving the improvement of the efficiency of the organic light emitting device.

The organic light emitting diode according to the present invention includes an organic light emitting layer including an organometallic complex represented by Formula 1, an anode and a cathode, and is characterized by excellent efficiency and lifespan due to the structural characteristics of the organometallic complex. do.

As already mentioned, the organic light emitting layer used in the present invention uses a host-dopant system, which can generally emit light using only the host material and the dopant material, but the efficiency and luminance are very low, and each molecule is brought closer to each other. Since excimers, which are not intrinsic properties of molecules, appear together, it is preferable to form a light emitting layer by doping a dopant to a host.

The dopant is not particularly limited as long as it is commonly used in the art, and may be, for example, an iridium complex, and in particular,

또는

일 수 있다.

or

Can be.

The amount of the dopant to be used is preferably 0.1 to 30% by weight of the organometallic complex. When used at less than 0.1% by weight, the effect of the dopant is hardly added, and when it exceeds 30% by weight, the triplet-triple extinction phenomenon occurs. There is a fear that the efficiency is reduced by.

In the organic light emitting diode according to the present invention, a hole transport layer (HTL) is further stacked between the anode and the organic light emitting layer, and an electron transport layer (ETL) is provided between the cathode and the organic light emitting layer. In addition, the hole transport layer may be stacked to facilitate the injection of holes from the anode. As the material of the hole transport layer, electron donating molecules having a small ionization potential are used, mainly based on triphenylamine. Diamine, triamine, or tetraamine derivative which makes a backbone many are used. The present invention is not particularly limited as long as it is commonly used in the art as a material of the hole transport layer. For example, N, N'-bis (3-methylphenyl) -N, N'-diphenyl-[1 , 1-biphenyl] -4,4'-diamine (TPD) or N, N'-di (naphthalen-1-yl) -N, N'-diphenyl benzidine (α-NPD) can be used.

A hole injection layer (HIL) may be further stacked on the lower portion of the hole transport layer. The hole injection layer material may also be used without particular limitation as long as it is commonly used in the art. For example, CuPc or Starburst type amines, such as TCTA, m-MTDATA, IDE406 (manufactured by Idemitsu Co., Ltd.) listed in the following formula (4) can be used.

In addition, the electron transport layer used in the organic light emitting diode according to the present invention provides an opportunity to recombine in the light emitting layer by smoothly transporting the electrons supplied from the cathode to the organic light emitting layer and suppressing the movement of holes not bonded in the organic light emitting layer. It acts to increase. The electron transport layer material may be used without particular limitation as long as it is commonly used in the art, for example, an oxadiazole derivative such as PBD, BMD, BND or Alq ₃ may be used. Meanwhile, an electron injection layer (EIL), which facilitates electron injection from the cathode and ultimately improves power efficiency, may be further stacked on the electron transport layer. The electron injection layer material may also be stacked. If it is conventionally used in the art can be used without particular limitation, for example, materials such as LiF, NaCl, CsF, Li ₂ O, BaO and the like can be used.

1 is a cross-sectional view showing the structure of an organic light emitting display device according to an embodiment of the present invention. The organic light emitting diode according to the present invention includes an anode 20, a hole transport layer 40, an organic light emitting layer 50, an electron transport layer 60 and a cathode 80, and if necessary, the hole injection layer 30 and the electron The injection layer 70 may be further included. In addition, an intermediate layer of one or two layers may be further formed, and in addition, a hole blocking layer or an electron blocking layer may be further formed.

Referring to Figure 1 with respect to the organic light emitting device and a method of manufacturing the present invention, as follows. First, the anode 20 is formed by coating an anode electrode material on the substrate 10. As the substrate 10, a substrate used in a conventional organic EL device is used. An organic substrate or a transparent plastic substrate excellent in transparency, surface smoothness, ease of handling, and waterproofness is preferable. In addition, transparent and conductive 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 30 is formed by vacuum-heat deposition or spin coating of the hole injection layer material on the anode 20 electrode. Next, the hole transport layer 40 is formed by vacuum thermal evaporation or spin coating of the hole transport layer material on the hole injection layer 30. Subsequently, the organic light emitting layer 50 may be stacked on the hole transport layer 40, and a hole blocking layer (not shown) may be selectively formed on the organic light emitting layer 50 as a vacuum deposition method or a spin coating method. . The hole blocking layer serves to prevent such a problem by using a material having a very low HOMO level when the hole is introduced into the cathode through the organic light emitting layer because the life and efficiency of the device is reduced. In this case, the hole blocking material used is not particularly limited, but should have an ionization potential higher than that of the light emitting compound while having electron transport ability, and typically BAlq, BCP, TPBI, and the like may be used. After the electron transport layer 60 is deposited on the hole blocking layer through a vacuum deposition method or a spin coating method, an electron injection layer 70 is formed and a cathode forming metal is vacuum-heated on the electron injection layer 70. The organic EL device is completed by vapor deposition to form a cathode 80 electrode.

The metal for forming the cathode may be lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver ( Mg-Ag), and the like, and a transmissive cathode using ITO and IZO can be used to obtain a front light emitting device.

Hereinafter, the present invention will be described in more detail with reference to preferred examples, but the present invention is not limited thereto.

Example 1

1- (1) 2- Bromo -6- Synthesis of Ethoxynaphthalene

6-bromo-2-naphthol (25 g), water (250 ml) and 1,4-dioxane (250 ml) were added to a 1000 ml three-necked round bottom flask, followed by stirring at room temperature. Sodium hydroxide was dissolved in water (100 ml) and added to the reaction solution. When all crystals were dissolved, diethylsulfate (17.3 g) was diluted in 1,4-dioxane (100 ml) and slowly added at room temperature. After the addition, the reaction proceeded under reflux for 12 hours to obtain white crystals. After completion of the reaction, EA was added to the reaction solution to separate the water layer and the organic layer. The organic layer was recovered, the organic layer was washed once more with water, and the washed organic layer was concentrated under reduced pressure to obtain a crystal. After adding a small amount of methanol to the crystals, the mixture was stirred for 10 minutes and filtered to obtain 9 g of 2-bromo-6-ethoxynaphthalene.

1- (2) 2- Phenyl -6-ethoxynaphthalene (2- Phenyl -6- ethoxynaphthalene ) Synthesis

2-bromo-6-ethoxynaphthalene (6g), phenylboronic acid (3.2g), potassium carbonate (10.9g), water (60ml) and toluene (180ml) were added to a 500ml round bottom flask. It was. Tetrakis (triphenylphosphine) palladium (0) (0.6 g) was added to the reaction solution under nitrogen atmosphere, and the temperature was raised to 90 ° C. and stirred for 6 hours. After completion of the reaction, the layers were separated, the toluene layer was taken, and the solvent was concentrated under reduced pressure to remove the solvent. The concentrate was then separated by column using MC, the MC was concentrated, and a small amount of methanol was added to the mixture, followed by filtration. 4.5 g of ethoxynaphthalene was obtained.

1- (3) 6- Phenyl 2-naphthol (6- phenyl -2- naphtol ) Synthesis

2-phenyl-6-ethoxynaphthalene (4.5 g), bromic acid (48%) (90 ml) and acetic acid (200 ml) were added to a 500 ml round bottom flask, and the temperature was raised to 110 ° C. under reflux for 24 hours. . After the reaction was terminated, the reaction solution was cooled to room temperature and dropped into 1000 ml of water to obtain white crystals. After filtering the crystals, the crystals were dissolved in MC, washed three times with water, the MC was concentrated under reduced pressure, column separated using MC, and recrystallized with hexane to obtain 3.3 g of 6-phenyl-2-naphthol.

1- (4) RPH Synthesis of -1

8-hydroxy-2-methylquinoline (2.4 g), aluminum isopropoxide (3.1 g) and anhydrous ethanol (110 ml) were added to a 250 ml round bottom flask and stirred at room temperature for 4 hours. After completion of the reaction, the insoluble material of the reaction solution was filtered using diatomaceous earth, and then the filtrate was transferred to a new 250 ml round bottom flask and 8-hydroxy-2-methylquinoline (2.4 g), 6-phenyl-2- Naphthol (3.3 g) was added to raise the temperature to 80 ° C. and refluxed for 24 hours. Finally, after completion of the reaction, the reaction solution was cooled to room temperature and the crystals were filtered and washed with anhydrous ethanol to obtain 2.8 g of RPH1. The results of elemental analysis using elemental analysis equipment (EA-1100) and comparison with theoretical values are shown in Table 1 below. Looking at Table 1 below, it is in good agreement with the theoretical value, and thus it can be confirmed that the organometallic complex for the desired organic light-emitting is synthesized.

N C H Theoretical value (%) 4.98 76.8 4.84 Found (%) 4.96 77.6 4.97

Preparation of 1- (5) Organic Light Emitting Diode

The light emitting area of the ITO glass was patterned to have a size of 3 mm × 3 mm and then washed. The substrate was mounted in a vacuum chamber and the pressure was 1 × 10 ⁻⁶ torr. Then, the organic material was placed on top of the ITO, CuPC (200 kPa), NPD (400 kPa), and RPH- prepared in Example 1- (4). An organic light emitting diode was manufactured by forming a film in the order of 1 + RD-1 (7%) (200kV), Alq3 (300kV), LiF (5kV), and Al (1000kV).

Example 2

2- (1) 1- Methoxy -4- Bromonaphthalene  synthesis

1-methoxynaphthalene (3.5 g) and acetonitrile (350 ml) were added to a 500 ml round bottom flask, followed by stirring. N-bromolysineimide (3.5 g) was added to the reaction solution three times, and the mixture was reacted at room temperature for 10 hours. After completion of the reaction, the reaction solution was concentrated under reduced pressure to remove the solvent, and the concentrate was extracted with hexane. After column separation, the hexane was concentrated to give a gel liquid (4.4 g).

2- (2) 1- Methoxy -4- Of phenylnaphthalene  synthesis

1-methoxy-4-bromonaphthalene (4.4g), phenylboronic acid (3.4g), potassium carbonate (7.7g), water (50ml), toluene (200ml), tetrahydrofuran in a 500ml round bottom flask (100 ml) was added followed by stirring. Tetrakis (triphenylphosphine) palladium (0) (0.2 g) was added to the reaction solution under a nitrogen atmosphere, and the temperature was raised to 90 ° C and stirred for 24 hours. After completion of the reaction, the layers were separated and the toluene layer was taken. The mixture was concentrated under reduced pressure to remove the solvent, and the concentrated solution was separated by MC. Finally, the MC was concentrated and a small amount of methanol was added and filtered to obtain 5.1 g of 1-methoxy-4-phenylnaphthalene.

2- (3) 4- Of phenylnaphthol  synthesis

1-methoxy-4-phenylnaphthalene (5.1 g), bromic acid (48%) (100 ml) and acetic acid (250 ml) were added to a 500 ml round bottom flask, and the temperature was raised to 110 ° C. under reflux for 24 hours. I was. After the reaction was completed, the reaction solution was cooled to room temperature and dropped into 1000 ml of water to obtain white crystals. The crystals were filtered and dissolved in MC, washed three times with water, and then concentrated under reduced pressure. Column separation using MC and recrystallization with hexane yielded 4.8 g of 4-phenylnaphthol.

2- (4) RPH14 Synthesis of

8-hydroxy-2-methylquinoline (3.2 g), aluminum isopropoxide (3.7 g) and anhydrous ethanol (150 ml) were added to a 500 ml round bottom flask, and the mixture was stirred at room temperature for 4 hours. After the reaction was completed, the insoluble material of the reaction solution was filtered using diatomaceous earth, and the remaining filtrate was transferred to a new 500 ml round bottom flask, followed by 8-hydroxy-2-methylquinoline (3.2 g) and 6-phenyl-2. -Naphthol (3.7 g) was added to raise the temperature to 80 ° C and refluxed for 24 hours. Finally, after the reaction was terminated, the reaction solution was cooled to room temperature, the crystals were filtered and washed with anhydrous ethanol to give 10.2 g of RPH14. The results of elemental analysis using elemental analysis equipment (EA-1100) and comparison with theoretical values are shown in Table 2 below. Looking at Table 2 below, it is in good agreement with the theoretical values, and thus it can be confirmed that the organometallic complex for the desired organic light-emitting is synthesized.

N C H Theoretical value (%) 4.98 76.8 4.84 Found (%) 4.99 77.6 4.99

Preparation of 2- (5) Organic Light Emitting Diode

The light emitting area of the ITO glass was patterned to have a size of 3 mm × 3 mm and then washed. The substrate was placed in a vacuum chamber and the pressure was 1 × 10 ⁻⁶ torr. Then, the organic material was placed on top of the ITO, CuPC (200 kPa), NPD (400 kPa), and RPH- prepared in Example 2- (4). An organic light emitting diode was manufactured by forming a film in order of 14 + RD-1 (7%) (200kV), Alq3 (300kV), LiF (5kV), and Al (1000kV).

Example 3

3- (1) 1- Methoxy -4- (2- Naphthyl )-Synthesis of Naphthalene

1-methoxy-4-bromo-naphthalene (10 g), 2-naphthalene boronic acid (8.7 g), potassium carbonate (17.5 g), water (100 ml) and toluene (300 ml) were added to a 500 ml round bottom flask. And then stirred. Tetrakis (triphenylphosphine) palladium (0) (1g) was added to the reaction solution under nitrogen atmosphere, and the temperature was raised to 90 ° C. and stirred for 24 hours. After completion of the reaction, the layers were separated and the toluene layer was taken, followed by concentration under reduced pressure to remove the solvent. The concentrate was then column separated with MC, and then the MC was concentrated, and then a small amount of methanol was added and filtered to form 1-methoxy-4-. 10.1 g of (2-naphthyl) -naphthalene was obtained.

3- (2) 4- (2- Naphthyl ) -Synthesis of Naphthol

1-methoxy-4- (2-naphthyl) -naphthalene (10.1 g), bromic acid (48%) (200 ml) and acetic acid (500 ml) were added to a 500 ml round bottom flask, and the temperature was raised to 110 ° C. The reaction was carried out at reflux for a time. After the reaction was terminated, the reaction solution was cooled to room temperature and dropped into 1000 ml of water to obtain white crystals. The crystals were filtered and then dissolved in MC and washed three times with water. The MC was concentrated under reduced pressure, and then separated by column using MC and recrystallized with hexane to obtain 8.2 g of 4- (2-naphthyl) -naphthol.

3- (3) RPH23 Synthesis of

8-hydroxy-2-methylquinoline (4.8 g), aluminum isopropoxide (6.2 g) and anhydrous ethanol (250 ml) were added to a 500 ml round bottom flask, and the mixture was stirred at room temperature for 4 hours. After the reaction was completed, the insoluble material of the reaction solution was filtered using diatomaceous earth, and the remaining filtrate was transferred to a new 500 ml round bottom flask, followed by 8-hydroxy-2-methylquinoline (4.8 g) and 6-phenyl. 2-naphthol (8.2 g) was added to raise the temperature to 80 ° C and refluxed for 24 hours. After the reaction was completed, the reaction solution was cooled to room temperature, the crystals were filtered and washed with anhydrous ethanol to give 15g of RPH23. The results of elemental analysis using elemental analysis equipment (EA-1100) and comparison with theoretical values are shown in Table 3 below. Looking at Table 3 below, it is in good agreement with the theoretical values, and thus it can be confirmed that the organometallic complex for the desired organic light-emitting is synthesized.

N C H Theoretical value (%) 4.57 78.4 4.78 Found (%) 4.59 79.27 4.91

Preparation of 3- (4) organic light emitting diode

The light emitting area of the ITO glass was patterned to have a size of 3 mm × 3 mm and then washed. The substrate was mounted in a vacuum chamber and the pressure was 1 × 10 ⁻⁶ torr. Then, the organic material was placed on top of the ITO, CuPC (200 kPa), NPD (400 kPa), and RPH- prepared in Example 3- (3). An organic light emitting diode was manufactured by forming a film in the order of 23 + RD-1 (7%) (200 mV), Alq3 (300 mV), LiF (5 mV), and Al (1000 mV).

Example 4

4- (1) 1,6- Dibromo -2- Of ethoxynaphthalene  synthesis

To a 500 ml round bottom flask, 1,6-dibromo-2-naphthol (25 g) and water (250 ml) were added and stirred. Sodium hydroxide (4.3 g) was dissolved in water (100 ml) and slowly added to the reaction solution. Then, the mixture was stirred until all of the crystals were dissolved. Diethylsulfate (18 ml) was slowly added thereto and refluxed for 12 hours. Proceeded. After completion of the reaction, EA was added to the reaction solution to separate the water layer and the organic layer. The organic layer was recovered, and the organic layer was washed once more with water. The organic layer thus washed was concentrated under reduced pressure to remove the solvent, and a small amount of methanol was added to the obtained crystals. The mixture was stirred for 10 minutes and filtered to obtain 20 g of 1,6-dibromo-2-ethoxynaphthalene.

4- (2) 1,6- Diphenyl -2- Ethoxynaphthalene Synthesis

1,6-dibromo-2-ethoxynaphthalene (9g), phenylboronic acid (7.3g), potassium carbonate (25g), water (90ml) and toluene (250ml) were added to a 500ml round bottom flask. After stirring, tetrakis (triphenylphosphine) palladium (0) (0.6 g) was added to the reaction solution under a nitrogen atmosphere, and the temperature was raised to 90 ° C. and stirred for 6 hours. After the reaction was completed, the layers were separated, the toluene layer was taken, and the solvent was concentrated under reduced pressure to remove the solvent. The concentrate was separated by column with MC, and then the MC was concentrated and a small amount of methanol was added to filter the resulting mixture. 8.1 g of 2-ethoxynaphthalene were obtained.

4- (3) 1,6- Diphenyl 2-naphthol synthesis

1,6-diphenyl-2-ethoxynaphthalene (8.1 g), bromic acid (48%) (80 ml) and acetic acid (400 ml) were added to a 500 ml round bottom flask, and the temperature was raised to 110 ° C and refluxed for 24 hours. And reacted. After completion of the reaction, the reaction solution was cooled to room temperature and then dropped into 1000 ml of water to obtain white crystals. The crystals were filtered and then dissolved in MC and washed three times with water. Finally, the MC was concentrated under reduced pressure, and then separated by column using MC, and recrystallized with hexane to obtain 7 g of 1,6-diphenyl-2-naphthol.

4- (4) RPH41

8-hydroxy-2-methylquinoline (2.1 g), aluminum isopropoxide (2.8 g) and ethanol anhydride (100 ml) were added to a 250 ml round bottom flask and stirred at room temperature for 4 hours. The insoluble material of the liquid was filtered using diatomaceous earth.

The filtrate was transferred to a new 250 ml round bottom flask, and 8-hydroxy-2-methylquinoline (2.1 g) and 1,6-diphenyl-2-naphthol (4 g) were added to raise the temperature to 80 ° C to reflux. After reacting for 24 hours, when the reaction was terminated, the reaction solution was cooled to room temperature, the crystals were filtered and washed with anhydrous ethanol to give 5g of RPH23. The results of elemental analysis using the elemental analysis equipment (EA-1100) and comparison with the theoretical values are shown in Table 4 below. Looking at Table 4 below, it is in good agreement with the theoretical value, and thus it can be confirmed that the organometallic complex for the desired organic light-emitting is synthesized.

N C H Theoretical value (%) 4.38 78.9 4.90 Found (%) 4.39 79.7 5.06

Preparation of 4- (5) organic light emitting diode

The light emitting area of the ITO glass was patterned to have a size of 3 mm × 3 mm and then washed. The substrate was mounted in a vacuum chamber and the pressure was 1 × 10 ⁻⁶ torr. Then, the organic material was placed on top of the ITO, CuPC (200 kPa), NPD (400 kPa), or RPH- prepared in Example 4- (5). An organic light emitting diode was manufactured by forming a film in the order of 28 + RD-1 (7%) (200 mV), Alq3 (300 mV), LiF (5 mV), and Al (1000 mV).

Comparative Example 1

The light emitting area of the ITO glass was patterned to have a size of 3 mm × 3 mm and then washed. After mounting the substrate in a vacuum chamber, the pressure is 1X10 ^-6 torr and the organic material is placed on ITO CuPC (200kPa), NPD (400kPa), BAlq + RD-1 (7%) (200kPa), Alq3 (300kPa), An organic light emitting diode was manufactured by forming a film in the order of LiF (5Å) and Al (1000Å).

Comparative Example 2

The light emitting area of the ITO glass was patterned to have a size of 3 mm × 3 mm and then washed. After mounting the substrate in a vacuum chamber and the pressure is 1X10 ^-6 torr and the organic material on the ITO CuPC (200 Pa), NPD (400 Pa), the compound of formula 5 + RD-1 (7%) (200 Pa), An organic light emitting diode was manufactured by forming a film in the order of Alq 3 (300 mW), LiF (5 mW), and Al (1000 mW).

Test Example 1

For the organic light emitting diodes prepared according to Examples 1 to 4 and Comparative Examples 1 and 2, the efficiency at the time of flowing a current of 0.9 mA / cm 2 was measured, and the half-life of the light emission versus the initial luminance in the DC purity current driving was measured. The measurement results are shown in Table 4.

Voltage (V) Current (mA) Luminance (cd / m ² ) Current efficiency (cd / A) Power Efficiency (lm / W) CIE (X) CIE (Y) Life (h) * Example 1 6.0 0.9 1198 12.0 6.26 0.641 0.337 5000 Example 2 6.3 0.9 1220 12.2 6.08 0.635 0.336 6000 Example 3 6.0 0.9 1215 12.2 6.35 0.636 0.337 5000 Example 4 6.1 0.9 1208 12.1 6.21 0.640 0.338 4000 Comparative Example 1 7.5 0.9 1170 11.7 5.48 0.636 0.338 2500 Comparative Example 2 6.7 0.9 1094 10.9 5.13 0.627 0.356 3000

Referring to Table 4, in the case of the organic light emitting diode according to the present invention, the lifespan is extended from at least 1.3 times to up to 2.4 times as compared with Comparative Examples 1 to 2, and it can be confirmed that the current efficiency and the power efficiency are excellent.

As described above, the organic light emitting diode according to the present invention uses a material in which a naphthalene derivative is introduced as a ligand as a phosphorescent host, and compared with an existing BAlq device, the current efficiency and power efficiency are excellent, and the lifetime is also excellent. Has the effect of becoming.

Claims (12)

An organometallic complex for an organic light emitting layer of Formula 1 below.

(Wherein R ₁ to R ₁₂ are each hydrogen, amino, alkyl having 1 to 10 carbon atoms, alkenyl having 2 to 10 carbon atoms, alkynyl having 2 to 10 carbon atoms or alkoxy having 1 to 10 carbon atoms, L is

or

Is, R ₂₁ to R ₂₇ each represent hydrogen, amino, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, or a heteroaryl group containing N, S, and O having 4 to 19 carbon atoms, wherein R ₂₁ to R ₂₇ At least one of is a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or a heteroaryl group containing N, S, O having 4 to 19 carbon atoms, a substituent when at least one of R ₂₁ to R ₂₇ is substituted Is alkyl having 1 to 10 carbon atoms, alkoxy having 1 to 10 carbon atoms, cyano, alkylamino having 1 to 10 carbon atoms, alkylsilyl having 1 to 10 carbon atoms, halogen, aryl having 6 to 10 carbon atoms, and aryloxy having 6 to 10 carbon atoms. , Arylamino having 6 to 10 carbon atoms, arylsilyl having 6 to 10 carbon atoms. The organometallic complex for an organic light emitting layer according to claim 1, wherein the organometallic complex for an organic light emitting layer is any one selected from the group represented by Formula 2.

The organometallic complex for an organic light emitting layer according to claim 1, wherein the organometallic complex for an organic light emitting layer is any one selected from the group represented by the following Equation 3.

An organic electroluminescent device comprising an anode, an organic light emitting layer and a cathode, wherein the organic light emitting layer comprises an organometallic complex according to any one of claims 1 to 3. The organic light emitting diode of claim 4, wherein the organic light emitting diode comprises an iridium complex as a dopant of the organic light emitting layer. The method of claim 5, wherein the iridium complex is

or

An organic light emitting diode, characterized in that. The organic light emitting diode of claim 5, wherein the amount of the dopant is 0.1 to 30% by weight of the organometallic complex. The organic light emitting diode of claim 4, wherein the organic light emitting diode further includes a hole transport layer between the anode and the organic light emitting layer, and an electron transport layer is further stacked between the cathode and the organic light emitting layer. diode. The organic light emitting diode of claim 8, wherein a hole injection layer is further stacked below the hole transport layer.        The organic light emitting diode of claim 8, wherein an electron injection layer is further stacked on the electron transport layer.        The method of claim 8, wherein the hole transport layer is N, N'-bis (3-methylphenyl) -N, N'-diphenyl-[1,1-biphenyl] -4,4'- diamine (TPD) or, An organic light emitting diode comprising N, N'-di (naphthalen-1-yl) -N, N'-diphenyl benzidine (α-NPD). The organic light emitting diode of claim 9, wherein the hole injection layer comprises CuPc, TCTA, or m-MTDATA of Formula 4 below.

(4)

Images