KR20090016048A - Fluorescent green/blue-emitting material and organic electroluminescent device comprising same - Google Patents

Abstract

A green/blue-emitting fluorescent material is provided to form an organic electroluminescent device with excellent driving voltage, high luminous efficiency and brightness. A green/blue-emitting fluorescent material has a structure indicated as the chemical formula 1. In the chemical formula 1, R1 and R2 are independently the chemical formulae (a); and R3-R7 are independently hydrogen atom, halogen atom, cyano group, -OH, thiol group, alkoxy group, substituted or unsubstituted C1-30 alkyl group or C3-30 aryl group, and C1-30 alkyl group or C3-30 aryl group containing at least one hetero atom of S, N, O, P and Si, wherein at least two selected from R3-R7 can form a ring.

Description

Green / blue fluorescent light emitting material and organic light emitting device including the same {FLUORESCENT GREEN / BLUE-EMITTING MATERIAL AND ORGANIC ELECTROLUMINESCENT DEVICE COMPRISING SAME}

The present invention relates to a novel material having green / blue fluorescence emission characteristics and an organic light emitting device including the same in a light emitting layer.

Recently, an organic light emitting device capable of low-voltage driving with a self-luminous type has superior viewing angles, contrast ratios, and the like, and is lighter and thinner than a liquid crystal display (LCD), which is a mainstream of flat panel display devices. It is also attracting attention as a next-generation display device because it is advantageous in terms of power consumption and has a wide range of color reproduction.

In general, an organic light emitting display device has a structure including a cathode (electron injection electrode), an anode (hole injection electrode), and an organic layer between the two electrodes. In this case, the organic layer may include a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), or an electron injection layer (EIL) in addition to the light emitting layer (EML). , an electron injection layer, and may further include an electron blocking layer (EBL) or a hole blocking layer (HBL) due to light emission characteristics of the light emitting layer. 1 illustrates a structure of a general organic light emitting display device having a structure in which an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode is stacked in this order.

When an electric field is applied to the organic light emitting device having such a structure, holes are injected from the anode, electrons are injected from the cathode, and holes and electrons are recombined in the light emitting layer through the hole transport layer and the electron transport layer, respectively, thereby emitting light. form exitons). The formed light exciton emits light as it transitions to ground states. In order to increase the efficiency and stability of the light emitting state, a light emitting dye (dopant) may be doped into the light emitting layer (host).

Anthracene derivatives are variously known as light emitting materials used in the light emitting layer of the organic light emitting device (see US Patent Nos. 5,635,308, 5,972,247 and 5,935,721, and Korean Patent Publication No. 2006-0050915).

However, in the case of the organic light emitting device using a light emitting material including an anthracene derivative known so far, there are many difficulties in practical use due to the high driving voltage, low efficiency and short lifespan. Accordingly, efforts have been made to develop organic light emitting diodes having low voltage driving, high efficiency, and long lifetime using various kinds of green or blue fluorescent light emitting materials using anthracene derivatives.

Document 1 US 5635308 (TDK Corporation) June 3, 1997.

2 US 5972247 (EASTMAN KODAK COMPANY) 1999.10.26.

Document 3 US 5935721 (EASTMAN KODAK COMPANY) 1999. 8.10.

Document 4 KR 2006-0050915 A (LG CHEMICAL) 2006. 5.19.

Accordingly, it is an object of the present invention to provide a green / blue fluorescent light emitting material having excellent driving voltage, high luminous efficiency and luminous luminance, and long life, and an organic light emitting device including the same.

In order to achieve the above object, the present invention provides a compound represented by the following Chemical Formula 1:

In Chemical Formula 1,

R ₁ and R ₂ are each independently

이고,

ego,

R ₃ to R ₇ each independently represent a hydrogen atom, a halogen atom, a cyano group, a hydroxyl group, a thiol group, an alkoxy group, a substituted or unsubstituted C _{1 -30} alkyl or C _{3 -30} aryl group, S, N, C _1-30 alkyl group or C _3-30 aryl group containing one or more hetero atoms of O, P and Si, optionally two or more selected from R ₃ to R ₇ may be bonded to each other to form a ring.

In addition, the present invention provides an organic light emitting device comprising the compound of Formula 1 in the light emitting layer as a light emitting material.

Since the compound of the present invention has excellent driving voltage, high luminous efficiency and luminous luminance, and long life, it can be used as a green / blue fluorescent light emitting material of an organic light emitting device. Luminous efficiency and lifespan characteristics can be significantly improved.

Specific examples of the fluorescent light emitting material represented by Formula 1 include compounds represented by the following Compounds 1 to 89.

The compound of Formula 1 according to the present invention may be prepared by the aromatic boron compound and the aromatic halogen compound through a well-known Suzuki-coupling reaction among carbon-carbon coupling reactions. For example, as shown in Scheme 1, the compound of Formula 1 may be prepared.

Where

R ₁ to R ₇ are as defined above,

When A is a halogen atom, D is B (OH) ₂ ,

When A is B (OH) ₂ , D is a halogen atom.

The present invention also provides an organic light emitting device comprising the compound of Formula 1 in the light emitting layer as a light emitting material. In this case, the compound of Formula 1 may be used as a single light emitting material or a light emitting host (host) of the light emitting layer.

The organic light emitting display device of the present invention includes a cathode (electron injection electrode) and an anode (hole injection electrode), and an emission layer (EML) containing the compound of Formula 1 between the two electrodes, preferably, the anode and Hole injection layer (HIL), hole transport layer (HTL) or electron blocking layer (EBL) between the light emitting layer and electron transport layer (ETL), electron injection layer (EIL) or hole blocking layer (HBL) between the cathode and the light emitting layer It may further comprise.

1 illustrates a structure of an organic light emitting diode stacked on a substrate in the order of anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode.

First, a positive electrode is coated on a surface of a substrate by a conventional method to form a positive electrode. At this time, the substrate used is preferably a glass substrate or a transparent plastic substrate excellent in transparency, surface smoothness, ease of handling and waterproofness. In addition, as the material for the anode, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), zinc oxide (ZnO), and the like, which are transparent and have excellent conductivity, may be used.

Next, a hole injection layer is formed on the surface of the anode by vacuum thermal evaporation or spin coating of a hole injection layer (HIL) material in a conventional manner. At this time, the hole injection layer material used is not particularly limited, copper phthalocyanine (CuPc), 4,4 ', 4 "-tris (3-methylphenylamino) triphenylamine (m-MTDATA), 4,4', 4,4'-tris (3-methylphenylamino) phenoxybenzene (m-MTDAPB), starburst amines 4,4 ', 4 "-tri (N-carbazolyl) triphenylamine (TCTA), 4 , 4 ', 4 "-tris (N- (2-naphthyl) -N-phenylamino) -triphenylamine (2T-NATA) or IDE406 available from Idemitsu can be used as the hole injection layer material have.

A hole transport layer is formed on the surface of the hole injection layer by vacuum thermal evaporation or spin coating of a hole transport layer (HTL) material in a conventional manner. In this case, the hole transporting material used is not particularly limited, and bis (N- (1-naphthyl-n-phenyl)) benzidine (α-NPD), N, N'-di (naphthalen-1-yl)- N, N'-diphenyl-benzidine (NPB) or N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-diphenyl-4,4'-diamine ( TPD) can be used as the hole transport layer material.

The light emitting layer (EML) material on the surface of the hole transport layer by vacuum thermal evaporation or spin coating in a conventional manner to form a light emitting layer. In this case, the compound of Chemical Formula 1 is used as the sole light emitting material or the light emitting host material among the light emitting layer materials used.

The dopant used together with the light emitting host in the light emitting layer material is not particularly limited, and as the fluorescent dopant, IDE102 and IDE105, which are available from Idemitsu, and tris (2-phenylpyridine) iridium (phosphorescent dopant) III) (Ir (ppy) ₃ ), iridium (III) bis [(4,6-difluorophenyl) pyridinato-N, C-2 ′] picolinate (FIrpic) (Chihaya Adachi etc Appl. Phys. Lett ., 2001 , 79 , 3082 3084], platinum (II) octaethylporphyrin (PtOEP), TBE002 (Cobion), and the like.

An electron transport layer is formed on the surface of the light emitting layer by vacuum thermal evaporation or spin coating of an electron transport layer (ETL) material in a conventional manner. In this case, the electron transporting material used is not particularly limited, and tris (8-quinolinolato) aluminum (Alq ₃ ) may be used. Optionally, (8-quinolinolato) lithium (Liq), bis (8-hydroxy-2-methylquinolinolato) -aluminum biphenoxide (BAlq), basthocuproine (BCP) And vacuum thermal evaporation and spin coating a hole blocking layer (HBL) material such as LiF in a conventional manner to form a hole blocking layer between the light emitting layer and the electron transport layer, and using a phosphorescent dopant together in the light emitting layer, whereby triplet excitons or holes The phenomenon of diffusion into the electron transport layer can be prevented. In this case, the hole blocking layer material to be used is not particularly limited.

An electron injection layer is formed on the surface of the electron transport layer by vacuum thermal evaporation or spin coating of an electron injection layer (EIL) material in a conventional manner. In this case, the electron injection layer material to be used is not particularly limited, and materials such as LiF, Liq, Li ₂ O, BaO, NaCl, CsF, and the like may be used.

Finally, a negative electrode is formed on the surface of the electron injection layer by vacuum thermal vapor deposition in a conventional manner. At this time, the negative electrode material used is lithium (Li), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium (Mg), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag) and the like can be used. In addition, in the case of the front emission organic field device, a transparent cathode through which light may pass may be formed using ITO or IZO.

The organic light emitting device according to the present invention may be manufactured in the order described above, that is, in the order of anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode and vice versa. The electron injection layer, the electron transport layer, the hole blocking layer, the light emitting layer, the hole transport layer, the hole injection layer and the anode may be manufactured in the order.

The fluorescent light emitting material of the present invention is excellent in electrical stability, has a high luminous efficiency and luminous luminance, and can implement green or blue of high color purity, and can be usefully used as a green / blue fluorescent light emitting material of an organic light emitting device.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are not intended to limit the invention only.

Example  1: Synthesis of Compound 5 of the Present Invention

Step 1) Synthesis of 2-bromo-9,10-diphenylanthracene

2-bromoanthraquinone (104.5 mmol, 30 g) was added to a 5 L three-necked round bottom flask, completely dissolved in tetrahydrofuran (THF), and the temperature was maintained at -78 ° C, followed by phenylmagnesium bromide (313.5 mmol, 315 mL) was added and stirred. After stirring for 12 hours, the reaction solution was extracted using water and dichloromethane. The extract was dried over anhydrous magnesium sulfate, fractional distillation of dichloromethane, acetonitrile and SnCl ₂ .2H ₂ O (261.1 mmol, 59 g) were added thereto, and the mixture was stirred under reflux at 80 ° C. for 4 hours. The resulting reaction solution was extracted with dichloromethane and water, and then the extract was dried over anhydrous magnesium sulfate and distilled dichloromethane. Diethyl ether was added to the obtained mixture to form a solid, and then the solid was filtered and dried to obtain a white title compound.

Yield: 65.4%

¹ H-NMR (CDCl ₃ , 400M Hz) δ (ppm) 7.9-7.30 (m, 17H).

Step 2) Synthesis of 2- (4- (naphthalen-2-yl) phenyl) -9,10-diphenylanthracene (Compound 5)

In a 5-liter three-necked round bottom flask, 4- (naphthalen-2-yl) phenyl boronic acid (17.1 mmol, 5.0 g) obtained in step 1), 2-bromo-9,10-diphenylanthracene (20.15 mmol, 5.0 g), Pd (PPh ₃ ) ₄ (0.85 mmol, 0.99 g) and potassium carbonate (0.20 mol, 27.60 g) were added. THF (100 mL) and water (30 mL) were added thereto, and the mixture was stirred at 80 ° C. for 12 hours. After the reaction was completed, the reaction solution was extracted with dichloromethane and water, the extract was dried over anhydrous magnesium sulfate, filtered using celite and silica gel and the solvent was distilled under reduced pressure. The resulting mixture was recrystallized from dichloromethane and acetone to give the ivory title compound.

Yield: 55% (5 g)

¹ H-NMR (CDCl ₃ , 400M Hz) δ (ppm) 8.04-7.32 (m, 28H).

Example 2 Synthesis of Compound 29 of the Invention

Step 1) Synthesis of 2-bromo-9,10-di (naphthalen-2-yl) anthracene

2-bromoanthraquinone (34.83 mmol, 10 g) was added to a 5 L three-necked round bottom flask, dissolved completely in THF, and maintained at 78 ° C., followed by 2-naphthyl magnesium bromide (139.32 mmol, 28.85 g) Was added and stirred. After stirring for 12 hours, the reaction solution was extracted using water and dichloromethane. The extract was dried over anhydrous magnesium sulfate, fractional distillation of dichloromethane, acetonitrile and SnCl ₂ .2H ₂ O (87.08 mmol, 19.56 g) were added and stirred under reflux at 80 ° C. for 4 hours. The resulting reaction solution was extracted with dichloromethane and water, and then the extract was dried over anhydrous magnesium sulfate and distilled dichloromethane. The obtained mixture was recrystallized using dichloromethane and acetonitrile to obtain the title compound.

Yield: 81% (14.5 g)

¹ H-NMR (CDCl ₃ , 400M Hz) δ (ppm) 8.12-7.30 (m, 21H).

Step 2) Synthesis of 2- (4- (naphthalen-2-yl) phenyl) -9,10-di (naphthalen-3-yl) anthracene (Compound 29)

In a 5-liter three-necked round bottom flask, 4- (naphthalen-2-yl) phenyl boronic acid (18 mmol, 4.465 g), 2-bromo-9,10-di (naphthalen-2-yl) obtained in step 1) above Anthracene (15 mmol, 7.641 g), Pd (PPh ₃ ) ₄ (0.75 mmol, 0.867 g) and potassium carbonate (30 mmol, 4.146 g) were added. THF (250 mL) and water (50 mL) were added thereto, followed by stirring at 80 ° C. for 12 hours. After the reaction was completed, the reaction solution was extracted with dichloromethane and water, the extract was dried over anhydrous magnesium sulfate, filtered using celite and silica gel and the solvent was distilled under reduced pressure. The resulting mixture was recrystallized with dichloromethane and acetonitrile to give the ivory title compound.

Yield: 35% (4 g)

¹ H-NMR (CDCl ₃ , 400M Hz) δ (ppm) 8.13-7.31 (m, 32H).

Test Example: Measurement of physical properties of a compound of the present invention and an organic light emitting device comprising the same

For the compounds 5 and 29 obtained in Examples 1 and 2, respectively, nuclear magnetic resonance (NMR) spectra are shown in FIGS. 2 and 3, UV-Vis spectra in FIGS. 4 and 5, and photoluminescence (PL) spectra. 6 and 7, thermogravimetric analysis (TGA) graphs are shown in FIGS. 8 and 9, and differential scanning calorimeter (DSC) graphs are shown in FIGS. 10 and 11, respectively.

On the other hand, using each of the compounds 5 and 29 as a light emitting host material of the light emitting layer, an organic light emitting display device was manufactured according to a conventional method. First, a 60 nm thick hole injection layer (hole injection layer material: 4,4 ', 4 "-tris (N- (2-naphthyl) -N-phenylamino)-over an ITO layer (anode) formed on a glass substrate. Triphenylamine (2T-NATA), 30 nm thick hole transport layer (hole transport layer material: N, N'-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine (NPB)), 45 3% doped C-545T-doped light emitting layer, wherein C-545T is a green fluorescent dopant with "2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-10- (2-benzothiazolyl) quinolizino- [9,9a, 1gh] coumarin ", 25 nm thick electron transport layer (electron transport layer material: tris (8-quinolinolato) aluminum (Alq ₃ )), an electron injection layer (electron injection layer material: LiF) having a thickness of 1 nm, and an aluminum cathode having a thickness of 150 nm were sequentially deposited to fabricate an organic light emitting display device. ₃ is used as a light emitting host material to prepare an organic light emitting display device having the same structure as above. Was small.

For the organic light emitting device manufactured, voltage-luminance, current density-luminance, luminous efficiency-luminance, and quantum efficiency-luminance curves are shown in FIGS. 12 to 15, and X and Y color coordinate-luminance curves are shown in FIGS. 16A and 16B, respectively. Electroluminescence spectra are shown in FIG. 17.

As can be seen from the test results, the compound of the present invention has excellent electrical stability, high luminous efficiency and luminous luminance, and high color purity can be realized, compared to the existing material, and thus used as a green / blue fluorescent light emitting material of an organic light emitting device. Therefore, the luminous efficiency and lifespan of the organic light emitting display device can be significantly improved.

1 is a cross-sectional view showing the structure of a general organic light emitting display device,

2 and 3 are nuclear magnetic resonance (NMR) spectra of the compounds represented by compounds 5 and 29 of the present invention, respectively,

4 and 5 are UV-Vis spectra of the compounds represented by compounds 5 and 29 of the present invention, respectively,

6 and 7 are photoluminescence (PL) spectra of the compounds represented by compounds 5 and 29 of the present invention, respectively.

8 and 9 are thermogravimetric analysis (TGA) graphs of the compounds represented by compounds 5 and 29 of the present invention, respectively,

10 and 11 are differential scanning calorimeter (DSC) graphs of the compounds represented by compounds 5 and 29 of the present invention, respectively,

12 to 15 are voltage-luminance, current density-luminance, luminous efficiency-luminance, and quantum efficiency-luminance curves of the organic light emitting diode including each of the compounds 5 and 29 of the present invention in the light emitting layer,

16A and 16B are X and Y color coordinate-luminance curves of an organic light emitting display device including the compounds 5 and 29 of the present invention, respectively,

17 is an electroluminescence spectrum of an organic light emitting display device including each of Compounds 5 and 29 of the present invention in a light emitting layer.

Claims (5)

Compound represented by the following formula (1): [Formula 1]

In Chemical Formula 1, R ₁ and R ₂ are each independently

ego, R ₃ to R ₇ are each independently a hydrogen atom, a halogen atom, a cyano group, a hydroxy group, a thiol group, an alkoxy group, a substituted or unsubstituted C _1-30 alkyl group or C _3-30 aryl group, S, N, C _1-30 alkyl group or C _3-30 aryl group containing one or more hetero atoms of O, P and Si, optionally two or more selected from R ₃ to R ₇ may be bonded to each other to form a ring. The method of claim 1, A compound according to claim 1, wherein the compound of Formula 1 is selected from compounds 1 to 89:

An organic light emitting device comprising an anode, a cathode, and a light emitting layer containing the compound of claim 1 between two electrodes. The method of claim 3, wherein The organic light emitting device of claim 1, wherein the compound of claim 1 is a light emitting host material. The method of claim 3, wherein An organic light emitting display device comprising a structure in which an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially stacked.

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