KR20110125932A - Phosphorescent blue-emitting iridium complex organic electroluminescent device comprising same - Google Patents

Abstract

PURPOSE: A blue-emitting phosphorescent iridium complex compound has excellent electronic stability and light emitting efficiency, and is provided to realize colors which have high luminance and high purity. CONSTITUTION: A blue-emitting phosphorescent iridium complex compound comprises the chemical formula 1 and the chemical formula 2. The chemical formula 1 comprises R1, R2, R3, R4, R5, n, and L. R1, R2, R3, R4, R5 are hydrogen, a halogen, a carboxyl, an amino, a cyano, a nitro, a C1-6 linear or branched alkyl or alkoxy, and a C6-18 substituted or non-substituted hetero aryl independently, n is integer of 20 or more, m is integer of 0 or more, and the sum of n and m is 3. L is a substituted or non-substituted C6-30 aryl, or a substituted or non-substituted C2-30 hetero aryl.

Description

Blue phosphorescent iridium organic complex and organic electroluminescent device including the same {PHOSPHORESCENT BLUE-EMITTING IRIDIUM COMPLEX ORGANIC ELECTROLUMINESCENT DEVICE COMPRISING SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blue phosphorescent iridium organic complex having an improved function of an iridium organic complex having many problems, such as luminous efficiency, color purity and electrical stability, and an organic electroluminescent device including the same.

As the movement to the information society accelerates, the proportion of flat panel displays is gradually increasing. Among them, liquid crystal display (LCD) is the most widely used, but it is a method of making a screen by applying voltage to the liquid crystal and passing the light from the backlight through a color filter to obtain three primary colors. As a self-luminous device, it has excellent viewing angle, contrast ratio, etc., is light and thin, and can be used for flexible substrates.

Organic EL is an phenomenon in which electrons and holes injected through a cathode and an anode are formed into an organic thin film by recombination, and light of a specific wavelength is generated from the formed excitons. Anthracene was produced by Pope et al. In 1963. It was first discovered from the single crystals of the group and later developed by a group at Princeton and the University of Southern California.

The excited state of the former in the compound is 1: 3 of the singlet to triplet ratio, and about 3 times more triplet states are generated. Therefore, the internal quantum efficiency of fluorescence falling from the singlet state to the ground state is only 25%, while the internal quantum efficiency of phosphorescence falling from the triplet state to the ground state is 75%. In addition, the theoretical limit of the internal quantum efficiency reaches 100% in the case of a quarterly transition from singlet to triplet. Phosphorescent light emitting material is a light emitting material that improved the luminous efficiency by using this point.

As the molecular structure for easy phosphorescence emission, an organometallic compound in which a transition metal having a large atomic number is a central atom is preferable, and among these, an iridium organic complex compound is in the spotlight. In this regard, the Republic of Korea Patent 10-0851519 (Registration date August 05, 2008) of 'Iridium complex compound with improved luminescence properties and organic light emitting device comprising the same', Republic of Korea Patent Registration 10-0522784 (Registration date October 12, 2005) 'High Efficiency Red Light Emitting Material and Display Device Employing It as Dopant', 'Blue Light Emitting Compound and Display Device Employing It as Light Emitting Material' of Korean Patent No. 10-0705982 (Dec. 04, 2007) Although it has been disclosed, there are many problems in the prior art including the above-mentioned patents, such as luminous efficiency, color purity and electrical stability of the iridium organic complex compound. Improved the situation is urgent.

Republic of Korea Patent Registration 10-0851519 (Registration date August 05, 2008) Republic of Korea Patent Registration 10-0522784 (Registration Date October 12, 2005) Republic of Korea Patent Registration 10-0705982 (Registration date 04 Apr 2007)

In order to solve the above problems, the present invention is to provide a blue phosphorescent iridium organic complex compound which is excellent in electrical stability and luminous efficiency, high luminance and high color purity and an organic electroluminescent device comprising the same do.

In order to achieve the above object, the present invention has a blue phosphorescent iridium organic complex of formula (1) and a blue phosphorescent iridium organic complex of formula (2) as the main technical configuration of the invention.

In Chemical Formula 1,

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ are each independently hydrogen, halogen, carboxyl, amino, cyano, nitro, C _1-6 straight or branched alkyl or alkoxy, C _6-18 Is a substituted or unsubstituted aryl, n is at least 2 and m is an integer of at least 0 and the sum is 3.

L is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms or a substituted or unsubstituted heteroaryl group having 2 to 30 carbon atoms.

X ₁ , X ₂ , X ₃ , X ₄ in Formula 2 are each independently hydrogen, halogen, carboxyl, amino, cyano, nitro C _1-6 linear or molecular alkyl or alkoxy, C _6-18 Or a substituted or unsubstituted aryl or a C _4-6 hetero ring, or a fused ring or a multifused ring in combination with each other. n is an integer of 2 or more, m is an integer of 0 or more, and the sum is 3.

L is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms or a substituted or unsubstituted heteroaryl group having 2 to 30 carbon atoms.

Preparation of the blue phosphorescent iridium organic complex is carried out through the following process.

Synthesis of two ligands on iridium was performed by mixing 2.5 to 3 equivalents of the ligand with IrCl ₃ · nH ₂ O, and water and 2-ethoxyethanol in a 3: 1 volume ratio to 50 solvents per g of IrCl ₃ · nH ₂ O. Add ~ 60ml and reflux under nitrogen for at least 4 hours.

After cooling the reaction mixture, water was added as much as the amount of reaction solvent to obtain a precipitate, and the precipitate was water (3 to 5 times the same amount as the reaction solvent) and methanol (2 to 3 times the same amount as the reaction solvent). After washing sufficiently with dryness to obtain a dimer.

As a final termination reaction, 2 to 3 equivalents of the ligand to be bound to the synthesized dimer, and 15 to 20 ml of 2-ethoxyethanol and 10 equivalents of Bayes (Na ₂ CO ₃ ) per g of the dimer were added thereto for 12 hours under a nitrogen atmosphere. It is refluxed more than.

Next, after cooling the synthetic mixture, the water is added as much as the amount of the reaction solvent, and the precipitate is filtered. The precipitate is filtered and washed several times with the amount of the reaction solvent, and then washed with hexane and ether again, and then completely dissolved in dichloromethane, and then silica. The filtrate subjected to chromatography is recrystallized and purified to obtain a compound.

As shown in Formula 1, the two ligands of the iridium (trivalent) organic complex are composed of monocyclohexene pyridine, hydrogen, and a substituent structure thereof, and the other main auxiliary ligand is the same as or substituted or unsubstituted. A aryl group having 6 to 30 ring carbon atoms or a substituted or unsubstituted heteroaryl group having 2 to 30 carbon atoms.

Formula (2) is composed of a principal component pyrrolephenyl and hydrogen and its substituents and the auxiliary ligand is the same or substituted or unsubstituted aryl group of 6 to 30 carbon atoms or substituted or unsubstituted heteroaryl of 2 to 30 carbon atoms It is composed of groups.

In general, the luminescence properties of the iridium organic complex compound are determined by the ligand, and in order to exhibit the properties, supply of charge from the host material should be smooth.

In the present invention, as the main ligand, 1 cyclohexenepyridine, hydrogen, and a substituent (Formula 1), pyrrolephenyl, hydrogen, and a substituent thereof, the auxiliary ligand is the same or substituted or unsubstituted aryl group having 6 to 30 carbon atoms or substituted with the main ligand. Or by introducing an unsubstituted heteroaryl group having 2 to 30 carbon atoms to improve color purity and luminous efficiency.

Representative examples of the blue phosphorescent iridium organic complex compounds are shown in the following Chemical Formulas 1a and 2a.

[Formula 1a]

[Formula 2a]

The present invention provides an organic electroluminescent device including a light emitting layer using the blue phosphorescent iridium organic complex as a light emitting material, and the organic electroluminescent device includes the blue phosphorescent iridium organic complex of Formulas 1 and 2 as a light emitting material. In addition to the light emitting layer, the charge (electron, hole) injection, the charge (electron, hole) transport layer, and has a multilayer structure as shown in FIG.

The positive electrode (transparent electrode) or negative electrode (metal electrode) component of the organic electroluminescent device is an indium tin compound or tin oxide in the case of a positive electrode, and any one or two kinds selected from aluminum, lithium, magnesium, and calcium in the case of a negative electrode. It consists of the above metals or their alloys, respectively.

In addition, the light emitting layer may be included by doping the compound of Formula 1, 2 to a known compound 1,3-di-9-carbazolylbenzene (MCP) of the formula (3) as a host.

As described above, the blue phosphorescent iridium organic complex compound and the organic electroluminescent device comprising the same according to the present invention are applied to the light emitting device of Formula 1 and Formula 2 to achieve excellent color purity and excellent luminous efficiency of the organic electroluminescent device It has the advantage that it can be usefully used as a light emitting material.

1 is a cross-sectional view showing the structure of an organic electroluminescent device comprising a blue phosphorescent iridium organic complex compound according to the present invention.
Figure 2 is a cross-sectional view showing the structure of an organic electroluminescent device according to an embodiment of the present invention.
Figure 3 is a cross-sectional view showing the structure of an organic electroluminescent device according to another embodiment of the present invention.

Example 1 Formula 1a [Ir (chmpy) ₂ (pic)] 's synthesis

35 g (99.263 mmol) of IrCl ₃ nH ₂ O and 39.325 g (228.304 mmol) of 2- (1cyclohexne-1en) 4-methylpyridine were mixed with 200 mL of a mixed solvent of 2-ethoxyethanol and water 3: 1 at 5 ° C under 78 ° C under nitrogen. Reflux for hours. After the reaction mixture was cooled, 200 mL of water was added, and then the precipitate was filtered and washed three times with 150 mL of water and twice with 150 mL of methanol to obtain 60.883 g (yield 98.3%) of iridium dimer.

20 g (15.427 mmol) of iridium dimer, 11.39 g (92.561 mmol) of piclinic acid, and 16.351 g (154.269 mmol) of Na ₂ CO ₃ were mixed in 300 mL of 2-ethoxyethanol and refluxed at 135 ° C. for 18 hours under nitrogen. After cooling the reaction mixture, 300 mL of water was added, and then the precipitate was filtered and washed with water (300 mL, stirred and washed 5 times), Hexane (300 mL, 1 time), diethylether (100 mL, 3 times), and dissolved in 2 L of dichloromethane, followed by silica chromatography. The filtrate was purified by recrystallization to give 13.428 g (yield 61.2%).

[Formula 1a]

Example 2: Formula 2a [Ir (dfphpy) ₂ (pic)] 's synthesis

35 g (99.263 mmol) of IrCl ₃ nH ₂ O and 44.106 g (228.304 mmol) of 2- (2,4fluorophenyl) 3 methylpyrrole were mixed with 200 mL of a mixed solvent of 2-ethoxyethanol and water 3: 1 for 5 hours at 78 ° C. under nitrogen. It was refluxed. After the reaction mixture was cooled, 200 mL of water was added, and then the precipitate was filtered and washed three times with 150 mL of water and twice with 150 mL of methanol to obtain 62.72 g (yield 98.3%) of iridium dimer.

20 g (15.427 mmol) of iridium dimer, 11.39 g (92.561 mmol) of picolinic acid, and 16.351 g (154.269 mmol) of Na ₂ CO ₃ were mixed with 300 mL of 2-ethoxyethanol and refluxed at 135 ° C. for 18 hours under nitrogen. After cooling the reaction mixture, 300 mL of water was added, and then the precipitate was filtered and washed with water (300 mL, stirred and washed 5 times), Hexane (300 mL, 1 time), diethylether (100 mL, 3 times), and dissolved in 2 L of dichloromethane, followed by silica chromatography. The filtrate was purified by recrystallization to give 14.568 g (59.2% yield). (Formula 2a)

(2a)

Example 3 Fabrication of Organic Electroluminescent Device Using Compound of Formula 1a and Formula 2a

An organic electroluminescent device was manufactured using the organic light emitting compound obtained in Example 1 as a light emitting material.

Looking at the structure of the organic electroluminescent device of Figure 2 or 3,

After depositing 2-TNATA on ITO-coated glass substrate to form a hole injection layer 12 of 40 nm, NPB was deposited thereon to form a hole transport layer 13 of 40 nm, followed by MCP as a host. The compound of Chemical Formula 1a obtained in Example 1 was doped at 9% rate of MCP to form a light emitting layer 15 on the hole transport layer 13. 10 nm of Balq is deposited thereon to form a hole blocking layer 16 which prevents holes from moving through the light emitting layer 15 to the electron transport layer 17, and deposits Alq ₃ to form an electron transport layer 17 of 40 nm. LiF was deposited to form an electron injection layer 18 having a thickness of 1 nm. Al was deposited on the electron injection layer 18 to form a cathode 19 having a thickness of 120 nm, thereby manufacturing an organic light emitting display device.

The deposition rate of each material was 2-TNATA (Formula 4), NPB (Formula 5), CBP, Alq ₃ (Formula 6), Balq (Formula 7) at 0.1 nm / sec and LiF was 0.01 nm. / Second, aluminum was deposited at a rate of 0.5 nm / second

As a result of measuring the characteristics of the device,

Formula 1a confirms that the luminance is 100cd / m2 and the luminous efficiency is 8.9 cd / A at the initial driving voltage of 5.7V. The luminance is 1,000cd / m2 and the luminous efficiency is 7.46 cd / A at the driving voltage of 11V. Was (x, y) = (0.20, 0.21).

Formula 2a confirms that the luminance is 100 cd / m2 and the luminous efficiency is 10.9 cd / A at an initial driving voltage of 6.1V. The luminance is 1,000 cd / m2 and the luminous efficiency is 8.46 cd / A at a driving voltage of 12.5. Was (x, y) = (0.16, 0.19).

The blue phosphorescent iridium organic complex according to the present invention and the organic electroluminescent device including the same have excellent electrical stability and luminous efficiency, and have high industrial applicability since high luminance and high color purity can be realized.

1: organic electroluminescent device
11: anode
12: hole injection layer
13: hole transport layer
14: electronic blocking layer
15: light emitting layer
16: hole blocking layer
17: electron transport layer
18: electron injection layer
19: cathode

Claims (6)

Blue phosphorescent iridium organic complex of formula (1).
[Formula 1]

Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ are each independently hydrogen, halogen, carboxyl, amino, cyano, nitro, C _1-6 linear or branched alkyl or alkoxy, C _6-18 substituted or unsubstituted aryl. n is greater than or equal to 2 and m is an integer greater than or equal to 0 and the sum is 3.
L is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms or a substituted or unsubstituted heteroaryl group having 2 to 30 carbon atoms.
Blue phosphorescent iridium organic complex of formula (2).
(2)

Wherein X ₁ , X ₂ , X ₃ , X ₄ are each independently hydrogen, halogen, carboxyl, amino, cyano, nitro, C _1-6 linear or molecular alkyl or alkoxy, C _6-18 Substituted or unsubstituted aryl or a C _4-6 hetero ring, or a fused ring or a multifused ring which are mutually fused together.
n is an integer of 2 or more, m is an integer of 0 or more, and the sum is 3.
L is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms or a substituted or unsubstituted heteroaryl group having 2 to 30 carbon atoms.
Blue phosphorescent iridium complex of formula 1a or 2a.
[Formula 1a]

(2a)

In the light emitting device comprising the light emitting layer 15 between the positive electrode 11 and the positive electrode 11 of the negative electrode 19,
The light emitting layer 15 includes an organic electroluminescent device comprising a blue phosphorescent iridium complex of claim 1 or claim 2 as a dopant.
The method of claim 4,
In the light emitting device, a hole injection layer 12, a hole transport layer 13, a light emitting layer 15, an electron transport layer 17, an electron injection layer 18, and a cathode 19 are sequentially stacked on the anode 11. An organic electroluminescent device comprising a blue phosphorescent iridium complex compound, characterized in that it has a multi-layered integral structure.
The method according to claim 5,
Blue phosphorescence, characterized in that the electron blocking layer 14 or the hole blocking layer 16 is further stacked between the hole transport layer 13 and the light emitting layer 15, or between the light emitting layer 15 and the electron transport layer 17. An organic electroluminescent device comprising an iridium complex.

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