KR101420097B1 - Organic light-emitting compound and organic electroluminescent device using the same - Google Patents

Abstract

The present invention relates to a novel organic light emitting compound having excellent light emitting performance, hole transporting ability, and electron transporting ability, and an organic electroluminescent device having improved characteristics such as light emitting efficiency, driving voltage and lifetime by incorporating the organic light emitting compound into one or more organic layers.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic electroluminescent compound, and an organic electroluminescent device using the same. BACKGROUND ART [0002]

The present invention relates to a novel organic light emitting compound and an organic electroluminescent device using the same. More particularly, the present invention relates to a novel organic light emitting compound having excellent light emitting ability, hole transporting ability, and electron transporting ability, An organic electroluminescent device having improved characteristics such as efficiency, driving voltage, and lifetime.

BACKGROUND ART An organic electroluminescent device (hereinafter referred to as an organic EL element) usually has a structure including an anode and a cathode and an organic layer between them. Here, in order to increase the efficiency and stability of the organic EL device, the organic material layer has a multi-layered structure composed of different materials. For example, the organic material layer includes a hole injection layer (HIL), a hole transport layer (HTL), a light emitting layer (EML) ), An electron injection layer (EIL), and the like.

When a voltage is applied between the two electrodes of the organic EL device, holes are injected into the anode, electrons are injected into the organic layer, and excitons are formed when injected holes and electrons meet. When falling, the light comes out.

The light emitting layer forming material of the organic EL device can be classified into blue, green and red light emitting materials depending on the luminescent color. In addition, yellow and orange light emitting materials are also used as light emitting materials for realizing better color. Further, in order to increase the luminous efficiency through an increase in color purity and energy transfer, a host / dopant system can be used as a light emitting material. The principle is that when a small amount of dopant having a smaller energy band gap and higher luminous efficiency than a host mainly constituting the light emitting layer is mixed with a light emitting layer in a small amount, the excitons generated in the host are transported as a dopant to emit light with high efficiency. At this time, since the wavelength of the host is shifted to the wavelength band of the dopant, light of a desired wavelength can be obtained depending on the type of the dopant used.

In general, a carbazole-based compound such as CBP (4,4-dicarbazolylbiphenyl) is used as a phosphorescent host material, and a metal complex compound containing heavy atoms such as Ir and Pt is widely used as a phosphorescent dopant material have.

However, CBP, which is a phosphorescent host material currently used, has a low glass transition temperature (Tg) of about 110 ° C. and easily crystallizes in the device, resulting in a very short lifetime of the organic EL device to about 150 hours.

JP 2011-509247

It is an object of the present invention to provide an organic luminescent compound capable of improving characteristics such as luminescence efficiency, driving voltage, thermal stability and lifetime, and an organic EL device using the same.

In order to achieve the above object, the present invention provides a compound represented by the following general formula (1).

In this formula,

Y and Z are each independently N or CH;

Each of R ₁ to R ₃ independently represents a C ₁ to C ₄₀ alkyl group, a C ₂ to C ₄₀ alkenyl group, a C ₂ to C ₄₀ alkynyl group, a C ₆ to C ₄₀ aryl group, An aryloxy group of C ₆ to C ₄₀ , an alkyloxy group of C ₁ to C ₄₀ , a cycloalkyl group of -NR ₄ R ₅ , a C ₃ to C ₄₀ , and a heterocycloalkyl group having 3 to 40 nuclear atoms Or a group which forms an adjacent fused aliphatic ring, a condensed aromatic ring, a condensed heteroaliphatic ring or a condensed heteroaromatic ring, wherein R ₄ and R ₅ are each independently selected from the group consisting of C ₁ -C _A C ₆ to C ₄₀ aryl group, a heteroaryl group having 5 to 40 nuclear atoms, a C ₃ to C ₄₀ cycloalkyl group, and a heterocycloalkyl group having 3 to 40 nuclear atoms, Adjacent fused aliphatic rings, condensed aromatic rings, condensed heteroaliphatic rings or condensed hetero Is a group that forms a ring hyangjok.

The present invention also provides an organic EL device comprising (i) an anode, (ii) a cathode, and (iii) one or more organic layers sandwiched between the anode and the cathode, wherein at least one of the organic layers comprises An organic EL device characterized by comprising a compound represented by the formula (1).

The compound represented by the general formula (1) of the present invention has excellent light emitting ability, electron transporting ability and hole transporting ability, and the organic EL device including the compound of the present invention can greatly improve characteristics such as light emitting performance, driving voltage, Display panels and the like.

The organic luminescent compound of the present invention achieves a sufficiently high triplet energy level by connecting various substituents, especially N-containing heterocyclic rings, aromatic rings, etc., to the parent moiety of the pyrrolopyrimidine system to improve phosphorescence characteristics, ) And / or hole transport capacity, luminous efficiency, drive voltage, lifetime characteristics, and the like.

The compound of the present invention has the structure represented by the formula (1).

In formula (1), Y and Z are each independently N or CH. For example, Y may be N, Z may be CH, or Y may be CH and Z may be N. [ Y and Z may all be CH.

Each of R ₁ to R ₃ independently represents a C ₁ to C ₄₀ alkyl group, a C ₂ to C ₄₀ alkenyl group, a C ₂ to C ₄₀ alkynyl group, a C ₆ to C ₄₀ aryl group, An aryloxy group of C ₆ to C ₄₀ , an alkyloxy group of C ₁ to C ₄₀ , a cycloalkyl group of -NR ₄ R ₅ , a C ₃ to C ₄₀ , and a heterocycloalkyl group having 3 to 40 nuclear atoms ≪ / RTI > Or adjacent groups to form a fused aliphatic ring, a fused aromatic ring, a fused heteroaliphatic ring, or a fused heteroaromatic ring. R ₄ and R ₅ are each independently a C ₁ to C ₄₀ alkyl group, a C ₆ to C ₄₀ aryl group, a heteroaryl group having 5 to 40 nuclear atoms, a C ₃ to C ₄₀ cycloalkyl group, A heterocycloalkyl group having 3 to 40 nuclear atoms; Or adjacent groups to form a fused aliphatic ring, a fused aromatic ring, a fused heteroaliphatic ring, or a fused heteroaromatic ring.

Preferably, in consideration of the triplet energy level, R ₁ and R ₃ are each independently a C ₆ to C ₄₀ aryl group, a heteroaryl group having 5 to 40 nuclear atoms or -NR ₄ R ₅ , and R ₂ May be a C ₆ to C ₄₀ aryl group or a heteroaryl group having 5 to 40 nuclear atoms. These functional groups may form adjacent groups and condensed aliphatic rings, condensed aromatic rings, condensed heteroaliphatic rings or condensed heteroaromatic rings.

R ₁ is more preferred if the C ₆ ~ C ₄₀ heteroaryl group of the aryl group, the number of nuclear atoms of 5 to 40, or NR ₄ R _5, and is particularly preferable when the NR ₄ R _5.

Each of R ₁ to R ₅ independently represents a C ₁ to C ₁₀ alkyl group, a C ₂ to C ₁₀ alkenyl group, a C ₂ to C ₁₀ alkynyl group, an amino group, a C ₆ to C ₈ aryl group, of to 8 heteroaryl group, C ₃ ~ C ₁₀ cycloalkyl group, a number of nuclear atoms of 3 to 10 hetero cycloalkyl group, or a condensed formed they are bonded to each other (fused) an aliphatic ring, a condensed aromatic ring, a condensed heterocyclic aliphatic ring or condensed Lt; / RTI > may be further substituted with one or more substituents selected from heteroaromatic rings.

The compound of the formula (1) may be embodied as one of the compounds represented by the following formulas (2) to (5).

In this formula,

R ₁ 'is a C ₆ to C ₄₀ aryl group, a heteroaryl group having 5 to 40 nuclear atoms or NR ₄ R ₅ ;

R ₂ , R ₃ , R ₄ and R ₅ are as defined above.

The following compounds are representative examples of the compound of Formula 1 of the present invention, but the compound of Formula 1 of the present invention is not limited to those exemplified below.

The present invention also provides a fuel cell comprising (i) an anode; (ii) a cathode; And (iii) at least one organic layer interposed between the anode and the cathode, wherein at least one of the organic layers includes a compound represented by the formula (1) Lt; / RTI > At this time, the compound represented by the formula (1) may include one kind or two or more kinds.

Preferably, the organic compound layer containing the compound represented by the formula (1) of the present invention may be at least one of a light emitting layer, a hole injecting layer, a hole transporting layer, an electron transporting layer and an electron injecting layer, Electron transport layer.

The organic EL device structure of the present invention has a structure in which one or more organic layers are laminated between electrodes, and examples thereof include (i) an anode, a light emitting layer, a cathode, (ii) a cathode, a hole injecting layer, a hole transporting layer, Transporting layer, electron injecting layer, cathode, (iii) anode, hole injecting layer, hole transporting layer, light emitting layer, and cathode.

In addition, the organic EL device according to the present invention may have an insulating layer or an adhesive layer inserted into the interface between the electrode and the organic layer as well as the structure in which the anode, one or more organic layers and the cathode are sequentially stacked, as described above.

In the organic EL device according to the present invention, the organic material layer containing the compound represented by Formula 1 may be formed by a vacuum deposition method or a solution coating method. Examples of the solution coating method include, but are not limited to, spin coating, dip coating, doctor blading, inkjet printing, or thermal transfer.

The organic EL device according to the present invention can be formed by forming an organic layer and an electrode using materials and methods known in the art, except that one or more of the organic layers are formed so as to include the compound represented by the formula 1 of the present invention .

For example, a silicon wafer, quartz or glass plate, a metal plate, a plastic film or a sheet can be used as the substrate.

Examples of the positive electrode material include metals such as vanadium, chromium, copper, zinc, and gold, or alloys thereof; Metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); ZnO: Al or SnO _2: a combination of a metal and an oxide such as Sb; Conductive polymers such as polythiophene, poly (3-methylthiophene), poly [3,4- (ethylene-1,2-dioxy) thiophene] (PEDT), polypyrrole and polyaniline; Or carbon black, but are not limited thereto.

Examples of the negative electrode material include metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin or lead or alloys thereof; Layer structure materials such as LiF / Al or LiO ₂ / Al, but are not limited thereto.

The hole injecting layer, the hole transporting layer and the electron transporting layer are not particularly limited, and ordinary materials known in the art can be used.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[ Synthetic example  One] Compound 1 -2 (9- (5,7- 피덴 -5H- pyrrolo [3,2-d] pyrimidin-4- yl ) -9H-carbazole < / RTI >

<Step 1> 4- chloro -5- phenyl -5H- pyrrolo [3,2-d] pyrimidine &lt; / RTI &gt;

Pd ₂ (dba) ₃ (3.0 g, 3.25 mmol) was dissolved in 600 ml of toluene, followed by bromobenzene (8.2 ml, 78.13 mmol) and 4-chloro-5H-pyrrolo [ Was added under nitrogen. Then, BINAP (2.0 g, 3.25 mmol) was added, Cs ₂ CO ₃ (42.4 g, 130.22 mmol) was added, and the reaction mixture was refluxed for 12 hours.

After confirming that the reaction was terminated using TLC, the reaction solution was cooled to room temperature. Then, distilled water was added thereto and extracted with ethyl acetate. The organic layer was dried over Na ₂ SO ₄ , distilled under reduced pressure, and then purified by column chromatography to obtain the title compound (10.4 g, yield 70%). HRMS [M] &lt; ⁺ & gt ^; : 229.041

<Step 2> 7- bromo -4- chloro -5- phenyl -5H- pyrrolo [3,2-d] pyrimidine &lt; / RTI &gt;

5-phenyl-5H-pyrrolo [3,2-d] pyrimidine (10 g, 43.54 mmol) obtained in the above Step 1 was dissolved in 100 ml of DMF, and then N-bromosuccinimide (11.6 g, 65.3 mmol) And the mixture was stirred at room temperature for 2 hours.

After the reaction was completed, distilled water was added thereto and extracted with ethyl acetate. The organic layer was dried over Na ₂ SO ₄ , distilled under reduced pressure, and crystallized with diethyl ether to give the title compound (12.0 g, yield 90%). HRMS [M] &lt; ⁺ & gt ^; : 306.951

&Lt; Step 3 > 9- (7- bromo -5- phenyl -5H- pyrrolo [3,2-d] pyrimidin-4- yl ) -9H-carbazole &lt; / RTI &

100 ml of isopropyl alcohol was added to 7-bromo-4-chloro-5-phenyl-5H-pyrrolo [3,2-d] pyrimidine (10 g, 32.41 mmol) obtained in the above Step 2, 48.44 mmol), DIPEA (11.3 mL, 64.82 mmol) was added and refluxed overnight.

After completion of the reaction, distilled water was added and the mixture was extracted with ethyl acetate. The organic layer was dried over Na ₂ SO ₄ , distilled under reduced pressure, and then purified by column chromatography to obtain the title compound (9.9 g, yield 70%). HRMS [M] &lt; ⁺ & gt ^; : 438.048

<Step 4> Synthesis of 9- (5,7- 피덴 -5H- pyrrolo [3,2-d] pyrimidin-4- yl ) -9H- carbazole synthesis

9H-carbazole (9.0 g, 20.48 mmol), phenylboronic acid (3.7 mmol) obtained in the above Step 3 and 9- (7-bromo-5-phenyl-5H- pyrrolo [ (1.18 g, 1.02 mmol) Pd (PPh ₃ ) ₄ (1.18 g, 1.02 mmol) were added to a flask, and 61.4 ml of a saturated aqueous solution of 2N Na ₂ CO ₃ and 200 ml of 1,4-dioxane were added to the flask and the mixture was stirred for 13 hours.

After completion of the reaction, distilled water was added and the mixture was extracted with ethyl acetate. The organic layer is dried over Na ₂ SO ₄ and purified by distillation under a reduced pressure and then purified by column chromatography to give the final compound (7.1g, 80% yield) desired. HRMS [M] &lt; ⁺ & gt ^; : 436.169

[ Synthetic example  2] Compound 2 -2 (9- (1, 3- 피덴 -1H- pyrrolo [2,3-c] pyridin-7- yl ) -9H-carbazole &lt; / RTI &gt;

<Step 1> 7- chloro -One- phenyl -1H- pyrrolo [2,3-c] pyridine &lt; / RTI &gt;

Iodobenzene (8.8 mL, 78.63 mmol), CuI (2.5 g, 13.12 mmol), K ₂ CO ₃ (18.1 g, 130.96 mmol) and 8-quinolinol (2.4 g, 16.5 mmol) were added to 300 ml of DMF under nitrogen, and the mixture was stirred at 135 ° C for 48 hours.

After confirming that the reaction was terminated using TLC, the reaction solution was cooled to room temperature. Then, distilled water was added thereto and extracted with ethyl acetate. The organic layer is dried over Na ₂ SO ₄ and purified by distillation under a reduced pressure and then purified by column chromatography to give the title compound (12.7g, 85% yield). HRMS [M] &lt; ⁺ & gt ^; : 228.045

&Lt; Step 2 > 3- bromo -7- chloro -One- phenyl -1H- pyrrolo [2,3-c] pyridine &lt; / RTI &gt;

1-phenyl-1H-pyrrolo [2,3-c] pyridine (10 g, 43.72 mmol) obtained in the above Step 1 was dissolved in 100 ml of DMF and then N-bromosuccinimide (11.6 g, 65.3 mmol) And the mixture was stirred at room temperature for 2 hours.

After the reaction was completed, distilled water was added thereto and extracted with ethyl acetate. The organic layer was dried over Na ₂ SO ₄ , distilled under reduced pressure, and then crystallized with diethyl ether to give the title compound (12.1 g, yield 90%). HRMS [M] &lt; ⁺ & gt ^; : 305.956

&Lt; Step 3 > 9- (3- bromo -One- phenyl -1H- pyrrolo [2,3-c] pyridin-7- yl ) -9H-carbazole &lt; / RTI &

(10 g, 32.51 mmol) and carbazole (6.5 g, 39.01 mmol) obtained in the above Step 2 were dissolved in 600 ml of toluene, After dissolving, Pd ₂ (dba) ₃ (1.5 g, 1.62 mmol) was added under nitrogen. Then, BINAP (1.0 g, 1.62 mmol) was added, Cs ₂ CO ₃ (21.2 g, 65.06 mmol) was added, and the reaction mixture was refluxed for 12 hours.

After completion of the reaction, distilled water was added and the mixture was extracted with ethyl acetate. The organic layer was dried over Na ₂ SO ₄ , distilled under reduced pressure, and then purified by column chromatography to obtain the title compound (10 g, yield 70%). HRMS [M] &lt; ⁺ & gt ^; : 437.053

<Step 4> Synthesis of 9- (1,3- 피덴 -1H- pyrrolo [2,3-c] pyridin-7- yl ) -9H- carbazole  synthesis

9H-carbazole (9.0 g, 20.53 mmol), phenylboronic acid (3.7 mmol) obtained in the above Step 3 and 9- (3-bromo- (1.18 g, 1.02 mmol) Pd (PPh ₃ ) ₄ (1.18 g, 1.02 mmol) were added to a flask, and 61.4 ml of a saturated aqueous solution of 2N Na ₂ CO ₃ and 200 ml of 1,4-dioxane were added thereto and the mixture was stirred for 13 hours.

After completion of the reaction, distilled water was added and the mixture was extracted with ethyl acetate. The organic layer is dried over Na ₂ SO ₄ and purified by distillation under a reduced pressure and then purified by column chromatography to give the final compound (7.1g, 80% yield) desired. HRMS [M] &lt; ⁺ & gt ^; : 435.174

[ Synthetic example  3] Compound 3-2 (9- (1,3- 피덴 -1H- pyrrolo [3,2-b] pyridin-7- yl ) -9H-carbazole &lt; / RTI &gt;

The procedure of Synthesis Example 2 was repeated except that 7-chloro-1H-pyrrolo [3,2-b] pyridine was used in place of 7-chloro-1H-pyrrolo [ 2 (yield: 39%). HRMS [M] &lt; ⁺ & gt ^; : 435.174

[ Synthetic example  4] Compound 4-2 (9- (1,3- 피덴 -1H- indole -7- yl ) -9H- carbazole ) Synthesis of

Compound 4-2 (yield 35%) was synthesized by the same procedure as in Synthesis Example 2 except that 7-chloro-1H-indole was used instead of 7-chloro-1H-pyrrolo [ Respectively. HRMS [M] &lt; ⁺ & gt ^; : 434.178

[ Example  1 ~ 4] Green organic EL  Device fabrication

Compounds 1-2, 2-2, 3-2 and 4-2 thus synthesized were subjected to high purity sublimation purification by a known method, and then a green organic EL device was fabricated according to the following procedure.

First, a glass substrate coated with ITO (Indium Tin Oxide) with a thickness of 1500 Å was washed with distilled water ultrasonic waves. After the distilled water was washed, the substrate was ultrasonically washed with a solvent such as isopropyl alcohol, acetone, or methanol, dried and transferred to a UV OZONE cleaner (Power Sonic 405, Hoshin Tech), the substrate was cleaned using UV for 5 minutes, The substrate was transferred.

M-MTDATA (60 nm) / TCTA (80 nm) / compounds 1-2, 2-2, 3-2 and 4-2 (respectively) + 10% Ir (ppy) ₃ (300 nm) / BCP (10 nm) / Alq ₃ (30 nm) / LiF (1 nm) / Al (200 nm) were stacked in this order to fabricate an organic EL device.

The structures of m-MTDATA, TCTA, Ir (ppy) ₃ , CBP and BCP are as follows.

[ Comparative Example  1] Green organic EL  Device fabrication

A green organic EL device was fabricated in the same manner as in Example 1, except that CBP was used instead of Compound 1-2 as a luminescent host material in forming the light emitting layer.

[ Evaluation example  One]

The driving voltage, current efficiency and emission peak at the current density of 10 mA / cm 2 were measured for each of the green organic EL devices manufactured in Examples 1-4 and Comparative Example 1, and the results are shown in Table 1 below.

Sample Host Driving voltage
(V) EL peak
(nm) Current efficiency
(cd / A) Example 1 1-2 6.78 515 42.4 Example 2 2-2 6.81 518 41.1 Example 3 3-2 6.79 517 40.8 Example 4 4-2 6.85 515 41.0 Comparative Example 1 CBP 6.93 516 38.2

As shown in Table 1, when the compound according to the present invention was used as a light emitting layer of a green organic EL device (Examples 1 to 4), compared with a green organic EL device (Comparative Example 1) using conventional CBP, It can be seen that it exhibits better performance in terms of driving voltage.

[ Example  5 ~ 8] Blue organic EL  Device manufacturing

Compounds 1-2, 2-2, 3-2, and 4-2 synthesized above were subjected to high purity sublimation purification by a conventionally known method, and then a blue organic EL device was manufactured according to the following procedure.

First, a glass substrate coated with ITO (Indium Tin Oxide) with a thickness of 1500 Å was washed with distilled water ultrasonic waves. After the distilled water was washed, the substrate was ultrasonically washed with a solvent such as isopropyl alcohol, acetone, or methanol, dried and transferred to a UV OZONE cleaner (Power Sonic 405, Hoshin Tech), the substrate was cleaned using UV for 5 minutes, The substrate was transferred.

On this ITO transparent electrode, CuPc (10 nm) / TPAC (30 nm) / Compound 1-2, 2-2, 3-2 and 4-2 (respectively) + 7% Flrpic (30 nm) / Alq ₃ ) / LiF (0.2 nm) / Al (150 nm) were stacked in this order to fabricate an organic EL device.

The structures of CuPc, TPAC and Flrpic are as follows.

[ Comparative Example  2] Organic EL  Device fabrication

A blue organic EL device was fabricated in the same manner as in Example 5, except that CBP was used instead of Compound 1-2 as a luminescent host material in forming the light emitting layer.

[ Evaluation example  2]

The driving voltage, current efficiency and emission peak at current densities of 10 mA / cm 2 were measured for each of the blue organic EL devices manufactured in Examples 5 to 8 and Comparative Example 2, and the results are shown in Table 2 below.

Sample Host Driving voltage
(V) EL peak
(nm) Current efficiency
(cd / A) Example 5 1-2 7.33 471 5.99 Example 6 2-2 7.13 472 5.85 Example 7 3-2 7.12 471 6.90 Example 8 4-2 7.55 474 6.34 Comparative Example 2 CBP 7.80 474 5.80

As shown in Table 2, when the compound according to the present invention was used as a light emitting layer of a blue organic EL device (Examples 5 to 8), compared with the conventional blue organic EL device using CBP (Comparative Example 2) It can be seen that it exhibits better performance in terms of driving voltage.

Claims (6)

A compound represented by the following formula (1):
&Lt; Formula 1 >

In Formula 1,
Y and Z are each independently N or CH, wherein at least one is N,
R ₁ is a carbazole group,
R ₂ is a C ₆ to C ₄₀ aryl group,
R ₃ is a C ₆ to C ₄₀ aryl group or a heteroaryl group having 5 to 40 nuclear atoms. The method according to claim 1,
Wherein the compound of formula (1) is selected from compounds represented by the following formulas (2) to (4):
(2)

(3)

&Lt; Formula 4 >

In the above Chemical Formulas 2 to 4,
R ₁ 'is a carbazole group,
R ₂ and R ₃ are each independently a C ₆ to C ₄₀ aryl group. delete 1. An organic electroluminescent device comprising: (i) an anode, (ii) a cathode, and (iii) one or more organic layers sandwiched between the anode and the cathode,
Wherein at least one of the organic material layers comprises a compound according to any one of claims 1 to 3. The organic electroluminescent device according to claim 1, The organic electroluminescent device according to claim 4, wherein the compound is contained in at least one layer selected from the group consisting of a light emitting layer, an electron transporting layer and a hole transporting layer.
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