KR101027000B1 - Pyrrole derivatives and organic electroluminescent device comprising the same - Google Patents

Abstract

The present invention relates to a pyrrole derivative of Formula 1, and an organic electroluminescent device comprising the same as a hole transport layer material. The compound represented by the following Chemical Formula 1 exhibits excellent hole transport ability compared to the conventional material, and can be used as a hole transport layer material in the organic electroluminescent device to significantly improve driving voltage, luminous efficiency and lifetime characteristics of the organic electroluminescent device:

[Formula 1]

Description

Pyrrole derivatives and organic electroluminescent devices comprising same {PYRROLE DERIVATIVES AND ORGANIC ELECTROLUMINESCENT DEVICE COMPRISING THE SAME}

The present invention relates to a novel pyrrole derivative and an organic electroluminescent device comprising the same in a hole transport layer.

In recent years, organic electroluminescent devices capable of low-voltage driving with self-luminous type have superior viewing angles, contrast ratios, and the like and are lighter and thinner than the liquid crystal display (LCD), which is the 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 electroluminescent device has a structure including a cathode (electron injection electrode) and 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. A structure of a general organic electroluminescent device having a structure stacked in the order of an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode is shown in FIG. 1.

When an electric field is applied to the organic electroluminescent 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 emission 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).

As the material used in the hole transport layer of the organic electroluminescent device, various derivatives containing pyrrole are known (U.S. Pat.Nos.6979414,6670054,6660410,5591554 and 4551605, and Korean Patent No.0351234). And 0346984).

However, in the case of the organic electroluminescent device using a hole transport layer including a pyrrole 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 electroluminescent devices having low voltage driving, high efficiency, and long life using pyrrole derivatives as various kinds of hole transport layer materials.

[Document 1] US 6979414 (Idemitsu Kosan Corporation) 2005. 12. 27.

Document 2 US 6670054 (Xerox Corporation) 12 December 30, 2003.

[Document 3] US 6660410 (Idemitsu Kosan Corporation) 2003. 12. 9.

[Document 4] KR 10-0351234 (Vistrome Co., Ltd.) August 21, 2002.

[Document 5] KR 10-0346984 (Sdiai Co., Ltd.) 2002. 7. 19.

[Document 6] US 5591554 (Xerox Corporation) 1997. 1. 7.

[Document 7] US 4521605 (Hodogaya Chemical Corporation) January 4, 1985

Accordingly, it is an object of the present invention to provide a material capable of significantly improving driving voltage, luminous efficiency and lifespan characteristics of an organic electroluminescent device, and an organic electroluminescent device comprising the same, having excellent hole transporting ability.

The present invention provides a pyrrole compound represented by the following formula (1) to achieve the above object:

Where

n is 1 to 4,

m is 1 to 3,

l is 1 to 3,

Each independently the same or different,

R ₁ to R ₄ and R ' ₁ to R' ₄ are the same as or different from each other, hydrogen, nitro group, cyano group, thiol group, alkoxy group having 1 to 20 carbon atoms, unsubstituted or substituted aryl having 6 to 60 carbon atoms An unsubstituted or substituted arylene group having 6 to 60 carbon atoms, an unsubstituted or substituted heteroaryl group having 3 to 60 carbon atoms or a heteroarylene group containing heteroatoms selected from the group consisting of S, N, O and Si, Unsubstituted or substituted fluorene group, and unsubstituted or substituted carbazole group,

R ₁ to R ₄ and R ' ₁ to R' ₄ may not be linked to each other with adjacent R ₁ to R ₄ and R ' ₁ to R' ₄ or Ar to form a ring, and at least one of R ₁ to R ₄ And at least one of R ′ ₁ to R ′ ₄ independently has 3 to 60 carbon atoms containing heteroatoms selected from the group consisting of unsubstituted or substituted aryl groups having 6 to 60 carbon atoms, S, N, O and Si. Have a group selected from the group consisting of an unsubstituted or substituted heteroaryl group or heteroarylene group, an unsubstituted or substituted fluorene group and an unsubstituted or substituted carbazole group,

Ar is selected from Formula 2 to Formula 32, wherein n may be the same or different from each other when two or more,

Formulas 2 to 32 are each independently a halogen atom, a nitro group, a cyano group, a thiol group, a C 1-6 alkoxy group, a C 1-6 alkyl group, a C 6-20 aryl group, S, N, O And it may be substituted with a heteroaryl group or heteroarylene group having 3 to 60 carbon atoms containing a hetero atom selected from the group consisting of Si, an unsubstituted or substituted fluorene group, or a carbazole group,

The solid line depicted across the rings constituting the multi-membered ring in the formula below represents the bonding position, where the bonding position may be any position:

The present invention also provides an organic electroluminescent device comprising the compound of Formula 1 in the hole transport layer.

Since the compound of the present invention has excellent hole transport ability compared to the existing material, it can be used as a hole transport layer material of the organic electroluminescent device can significantly improve the driving voltage, luminous efficiency and life characteristics of the organic electroluminescent device.

Preferably, in Formula 1, R ₁ to R ₄ and R ' ₁ to R' ₄ may be the same or different from each other, hydrogen, biphenyl, cumenyl, naphthalenyl, phenyl, methylphenyl, 9H-fluorene- 9,9-dimethyl, N-phenylcarbazolyl or 9,10-dihydrophenanthrenyl.

Hereinafter, specific compounds of the compound of Formula 1 of the present invention have been described, but the present invention is not limited to these compounds.

Among the compounds 1 to 28, compounds 1 and 10 are particularly preferable as the hole transport layer material.

In the organic electroluminescent device of the present invention, an anode (hole injection electrode), a hole injection layer (HIL), a hole transport layer (HTL) containing the compound of Formula 1, an emission layer (EML) and a cathode (electron injection electrode) are sequentially It has a stacked structure, preferably, comprising an electron blocking layer (EBL) between the anode and the light emitting layer, an electron transport layer (ETL), an electron injection layer (EIL) and a hole blocking layer (HBL) between the cathode and the light emitting layer ) May further include one or more of the following.

1 illustrates a structure of an organic electroluminescent device 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, copper phthalocyanine (CuPc), 4,4 ', 4 "-tris (3-methylphenylamino) triphenylamine (m-MTDATA), 4,4', 4" -tris (3-methylphenyl) as a hole injection layer material Amino) phenoxybenzene (m-MTDAPB), starburst amines 4,4 ', 4 "-tri (N-carbazolyl) triphenylamine (TCTA) or 4,4', 4" -tris (N- (2-naphthyl) -N-phenylamino) -triphenylamine (2T-NATA) may be used as the hole injection layer material, but is not limited thereto.

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 compound of Formula 1 is used as the hole transport layer material, and bis (N- (1-naphthyl-n-phenyl)) benzidine (α-NPD), N, N'-di together with the compound of Formula 1 (Naphthalen-1-yl) -N, N'-diphenyl-benzidine (NPB) or N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-diphenyl-4 , 4'-diamine (TPD) may be used as the hole transport layer material, but is not limited thereto. The compound of formula 1 of the present invention may be included in the hole transport layer in an amount of 30 to 100 mol% based on the total 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, tris (8-quinolinolato) aluminum (Alq ₃ ) may be used as the host material among the light emitting layer materials, but is not limited thereto. The dopant used with the light emitting host in the light emitting layer material is C-545T for the fluorescent dopant ("2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H as a green fluorescent dopant"). , 5H, 11H-10- (2-benzothiazolyl) quinolizino- [9,9a, 1gh] coumarin "), and tris (2-phenylpyridine) iridium (III) (Ir (ppy) for phosphorescent dopant 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), and the like, but are not limited thereto.

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, tris (8-quinolinolato) aluminum (Alq ₃ ) may be used as the electron transport layer material, but is not limited thereto. 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 by using a phosphorescent dopant in the light emitting layer, the triplet excitons or holes The phenomenon of diffusion into the electron transport layer can be prevented. At this time, the hole blocking layer material 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 deposition on a material for a negative electrode in a conventional manner. At this time, 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 a top emission organic field device, a transparent cathode through which light may pass may be formed using ITO or IZO.

The organic electroluminescent device according to the present invention may be manufactured in the same order as 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 pyrrole derivative of the present invention has excellent hole transport ability and can be usefully used as a hole transport layer material of an organic electroluminescent device.

Although the present invention has been described in more detail based on the following examples, the following examples are only for illustrating the present invention, and thus do not limit the present invention.

Example 1 Synthesis of Compound 1 of the Invention

Step 1) Synthesis of Compound C

Compound B (50.00 g, 0.259 mol) was added to a 1000 mL two neck flask, and THF (500 mL) was added thereto. Then, after cooling the flask to -78 ℃, BuLi (2.5M in hexane, 114mL) was added and stirred for 1 hour. Then compound A (17.40 g, 0.259 mol) was added and stirred for 6 hours. Water (500 mL) and ether were added to the reaction mixture, followed by extraction. The ether was removed and distilled under reduced pressure to obtain Compound C.

Yield: 52 g (90%)

MS (FAB) m / z : 223.2 [M + H] ⁺ ; ¹ H NMR (δ, CDCl ₃ ); 1.07-1.10 (d, 18H), 1.36-1.44 (m, 3H), 6.30 (s, 2H), 7.27 (s, 2H)

Step 2) Synthesis of Compound D

NBS (15.93g, 0.089mol) and THF (350mL) were added to a 500mL two-necked flask, cooled to -78 ° C, and then Compound C (9.90g, 0.044mol) of Step 1) was stirred at low temperature for 3 hours. It was. After extraction with water (200 mL) and ether (200 mL), water and ether were removed, recrystallized with ethyl acetate / methanol (EA / Me-OH) and filtered to afford compound D.

Yield: 15 g (89%)

MS (FAB) m / z : 380.8 [M + H] ⁺ ; ¹ H NMR (δ, CDCl ₃ ); 1.07-1.10 (d, 18H), 1.36-1.44 (m, 3H), 6.72 (s, 2H)

Step 3) Synthesis of Compound F

In a 500 mL two neck flask, Compound D (5.00 g, 0.013 mol) and Compound E (5.66 g, 0.029 mol) were added, followed by Pd (PPh ₃ ) ₄ (0.75 g, 0.00065 mol) and 2N-Na ₂ CO ₃ (60 mL). After adding benzene (100 mL) and methanol (60 mL), the mixture was stirred while refluxing for 16 hours. Extraction with water and ethyl acetate (EA), followed by removal of water and ethyl acetate, reprecipitation with ether and filtration gave compound F.

Yield: 2.5 g (36%)

MS (FAB) m / z : 527.30 [M + H] ⁺ ; ¹ H NMR (δ, CDCl ₃ ); 1.07-1.10 (d, 18H), 1.36-1.44 (m, 3H), 7.23-7.28 (m, 10H), 7.41-7.21 (m, 2H), 7.50-7.53 (m. 8H)

Step 4) Synthesis of Compound G

Compound F (2.5 g, 0.0047 mol) was added to a 250 mL two-neck flask, followed by stirring with n-Bu ₄ NF (4.7 mL), followed by extraction with water and methylene chloride (MC), followed by removal of water and methylene chloride. And precipitated with hexane, followed by filtration to obtain Compound G.

Yield: 1.5 g (85%)

MS (FAB) m / z : 371.2 [M + H] ⁺ ; ¹ H NMR (δ, CDCl ₃ ); 5.0-5.1 (m, 1H), 6.6 (s, 2H), 7.23-7.28 (m, 10H), 7.41-7.42 (m, 2H), 7.50-7.53 (m. 8H)

Step 5) Synthesis of Compound 1

Compound H (0.7 g, 0.0017 mol) and compound G (1.35 g, 0.0036 mol) were placed in a 250 mL two-necked flask, followed by Pd ₂ (dba) ₃ (0.078 g, 0.000085 mol), (t-butyl) ₃ P ( 0.34 g, 0.0017 mol), t-BuONa (0.36 g, 0.0037 mol) and 150 mL of toluene were added thereto, and the mixture was stirred while refluxing at 110 ° C.

After extraction with water and methylene chloride, water and methylene chloride were removed, separated by column chromatography using methylene chloride / hexane (3: 7), recrystallized with hexane, and filtered to obtain compound 1. .

Yield: 1.1 g (72%)

MS (FAB) m / z : 892.4 [M + H] ⁺ MS (FAB) m / z : 689.5 [M + H] ⁺ ; ¹ H NMR (δ, CDCl ₃ ); 7.25 (d, 16H), 7.41-7.42 (m, 4H), 7.51-7.53 (d, 16H), 7.61 (s, 4H), 7.68 (d, 4H), 7.79 (d, 4H)

Example 2: Synthesis of Compound 10 of the Invention

Compound 10 was synthesized in the same manner as in Example 1, except that Compound E was replaced with 9,9′-dimethylfluorene boronic acid in Scheme 1.

MS (FAB) m / z : 1052.5 [M + H] ⁺ ; ¹ H NMR (δ, CDCl ₃ ); 1.72 (s, 24H), 7.28-7.38 (m, 8H), 7.55-7.93 (m, 32H)

Test Example: Measurement of physical properties of organic electroluminescent device using TPD as hole transport layer for comparison with compounds 1 and 10 of the present invention

The organic electroluminescent device was manufactured according to a conventional method using the compound 1 and 10 of this invention as a hole transport layer material. First, a hole injection layer 4,4 ', 4 "-tris (N- (2-naphthyl) -N-phenylamino) -triphenylamine (2T-NATA) having a thickness of 600 kPa on the ITO layer (anode) formed on the glass substrate. ), 300 Å thick hole transport layer (compounds 1 and 10), 450 Å thick C-545T 1% doped light emitting layer (C-545T is a green fluorescent dopant, "2,3,6,7-tetra Hydro-1,1,7,7-tetramethyl-1H, 5H, 11H-10- (2-benzothiazolyl) quinolizino- [9,9a, 1gh] coumarin "and tris ( 8-quinolinolato) aluminum (Alq ₃ )), an electron transport layer having a thickness of 250 kHz (electron transport layer material: tris (8-quinolinolato) aluminum (Alq ₃ )), an electron injection of 10 Å thick An organic electroluminescent device was fabricated by sequentially depositing a layer (electron injection layer material: LiF) and an aluminum cathode having a thickness of 1500 kHz.For comparison, N, N'-diphenyl-N, N instead of the compound of the present invention. '-Bis (3-methylphenyl) -1,1'-diphenyl-4,4'-diamine (TPD) An organic electroluminescent device having the same structure as above was fabricated using the hole transport layer material.

For the organic electroluminescent device manufactured, voltage-luminance, current density-luminance, voltage-current density, luminous efficiency-luminance, and power efficiency-luminance curves are shown in FIGS. 7 and 8, the electroluminescence spectrum is shown in Figure 9, the lifetime of the organic electroluminescent device is shown in Figure 10, these results are summarized in Table 1 below.

Hole transport material Driving voltage
(V) Current density
(mA / ㎠) efficiency
(cd / A) CIE xy Compound 1 7.89 18.57 21.55 (0.286,0.629) Compound 10 8.16 19.23 20.73 (0.287,0.629) TPD 8.28 22.52 17.75 (0.284,0.623) Measured at 4000 nit

As can be seen from the results of Table 1, the organic electroluminescent device of the test example using the compounds 1 and 10 of the compounds of the present invention as the hole transport layer material has a lower driving voltage and a luminous efficiency compared to the organic electroluminescent device of the comparative example. It was measured to be high and the lifetime was also excellent.

Therefore, when the compound according to the present invention is used as the hole transport layer material of the organic electroluminescent device, it is possible to improve the driving voltage, the luminous efficiency and the lifetime of the organic electroluminescent device.

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

2 is a voltage-luminance curve of an organic electroluminescent device using TPD as a hole transport layer material for comparison with Compounds 1 and 10 of the present invention, respectively.

3 is a current density-luminance curve of an organic electroluminescent device using TPD as a hole transport layer material for comparison with Compounds 1 and 10 of the present invention, respectively.

4 is a voltage-current density curve of an organic electroluminescent device using TPD as a hole transport layer material for comparison with Compounds 1 and 10 of the present invention, respectively.

FIG. 5 is a light emission efficiency-luminance curve of an organic electroluminescent device using TPD as a hole transport layer material for comparison with Compounds 1 and 10 of the present invention, respectively.

FIG. 6 is a power efficiency-luminance curve of an organic electroluminescent device using TPD as a hole transport layer material for comparison with Compounds 1 and 10 of the present invention, respectively.

7 and 8 are X and Y color coordinate-luminance curves of organic electroluminescent devices using TPD as a hole transporting layer material for comparison with compounds 1 and 10 of the present invention, respectively.

9 is an electroluminescence spectrum of an organic electroluminescent device using TPD as a hole transport layer material for comparison with Compounds 1 and 10 of the present invention, respectively.

Fig. 10 shows the lifespan of the organic electroluminescent device using TPD as a hole transport layer material for comparison with Compounds 1 and 10 of the present invention, respectively.

Claims (6)

A compound of formula [Formula 1]

Where n is 1 to 3, m is 1 or 2, l is 1 or 2, R ₁ , R ₄ , R ' ₁ and R' ₄ are hydrogen, R ₂ , R ₃ , R ' ₂ and R' ₃ are the same as or different from each other, and are phenyl; Phenyl substituted with C1-C6 alkyl; Biphenyl; Naphthalenyl; Fluorenyl substituted with C1-C6 alkyl; Carbazolyl substituted with phenyl; Or dihydrophenanthreneyl, Ar is selected from the group consisting of the following Chemical Formulas 2 to 4, 6, 8, 13, 25 to 27, and 32, wherein when n is 2 or more, they may be the same or different from each other, Ar may be substituted with C1-C6 alkyl or phenyl, The solid line depicted across the rings constituting the multi-membered ring in the formula represents a bonding position, where the bonding position may be any position:

The method of claim 1, R ₁ , R ₄ , R ' ₁ and R' ₄ are hydrogen, R ₂ , R ₃ , R ' ₂ and R' ₃ are the same or different from each other and are biphenyl, cumenyl, naphthalenyl, phenyl, methylphenyl, 9H-fluorene-9,9-dimethyl, N-phenylcarbazolyl Or 9,10-dihydrophenanthrenyl. An organic electroluminescent device comprising an anode, a cathode and at least one organic compound layer between the two electrodes, An organic electroluminescent device, in which all or part of the organic compound layer comprises the compound of formula 1 according to claim 1. The method of claim 3, wherein The organic electroluminescent device comprising the hole transport layer containing the compound of Formula 1 wherein the organic compound layer. The method of claim 4, wherein An organic electroluminescent device comprising the compound of formula 1 in the hole transport layer in an amount of 30 to 100 mol% based on the total hole transport layer material. Anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode are sequentially stacked, and the hole transport layer comprises an organic electroluminescence comprising the compound of formula 1 according to claim 1 device.

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