KR20080105871A - Red phosphorescence compound and organic electroluminescence device using the same - Google Patents

Abstract

A red phosphor compound is provided to improve the chromatic purity, luminous efficiency and lifetime by using the chemical formula 1 used as a dopant of a light-emitting layer. A red phosphorus compound is indicated as the chemical formula 1. In the chemical formula 1, the formula (a) is the formula (b); R1, R2, R3, R4, R5 and R6 are independently substituted or non-substituted C1 - C6 alkyl group, wherein the C1 - C6 alkyl group is selected from a group consisting of methyl, ethyl, n-propyl, i- propyl, n-butyl, i- butyl and t-butyl; R1, R2, R3, R4.

Description

Red phosphorescence compound and organic electroluminescence device using the same

1 is a graph showing that the visibility decreases as the color purity of a conventional organic light emitting display device increases

Figure 2 is a graph showing the structural formula of the compounds used in the examples of the present invention

The present invention relates to a red phosphorescent compound and an organic electroluminescent device using the same.

In general, when an electric charge is injected into an organic film formed between a cathode for electron injection and an anode for hole injection, the organic electroluminescent device emits light while pairing with electrons and holes.

Not only can the device be formed on a flexible transparent substrate such as plastic, but it can also be driven at a lower voltage (about 10V or less) than plasma display panels or inorganic EL displays, and it also consumes power. Is relatively small, and the color is excellent.

In addition, the organic electroluminescent device can display three colors of green, blue, and red, and thus, has become a subject of much interest as a next generation full color display device.

Here, the process of manufacturing the organic EL device will be briefly described as follows.

First, an anode is formed on a transparent substrate.

Here, indium tin oxide (ITO) is often used as the anode material.

Next, a hole injecting layer (HIL) is formed on the anode 2.

Here, the hole injection layer is mainly formed of copper phthalocyanine (CuPc), and is formed to a thickness of about 10 ~ 30nm.

Next, a hole transport layer (HTL) is formed on the hole injection layer.

Here, the hole transport layer is 4,4'-bis [N- (1-naphthyl) -N-phenylamino] -biphenyl (4,4'-bis [N- (1-naphthyl) -N-phenylamino]- biphenyl (NPB)) is used to form a thickness of about 30 ~ 60nm.

In addition, an organic light emitting layer is formed on the hole transport layer.

At this time, a dopant is added as needed.

In the case of phosphorescent red light emission, the organic light emitting layer often has 4,4'-N, N'-dicarbazole-biphenyl (4,4'-N, N'-dicarbazole-biphenyl (CBP)) in a thickness of about 30 to 60 nm. The iridium complex is used a lot as the dopant.

Subsequently, an electron transport layer (ETL) and an electron injecting layer (EIL) are continuously formed on the organic light emitting layer, or an electron injection transport layer is formed.

Here, the electron transport layer mainly uses tris (8-hydroxy-quinolate) aluminum (Alq3).

Next, a cathode is formed on the electron injection layer, and a protective film is formed thereon.

The devices formed as described above may implement blue, green, and red light emitting devices, respectively, according to a method of forming the light emitting layer.

In the light emitting layer of the device, excitons are formed by recombination of electrons and holes injected from both electrodes.

The excitons have a ratio of 1: 3 to singlet and triplet, and in the case of fluorescence, only singlet excitons are used, and in the case of phosphorescence, both singlet and triplet can be used to obtain more excellent luminous efficiency.

As such, the phosphorescent material may have a very high quantum efficiency compared to the fluorescent material, and thus, much research has been conducted as an important method for increasing the efficiency of the organic EL device.

External luminance efficiency (η _le ) can be expressed as follows.

η _le = k η _int η _out

Where k is the sensitivity of the human eye according to color, η _int is the internal quantum efficiency, and η _out is the outcoupling efficiency.

The internal quantum efficiency should be excellent in order to obtain a high external light emission efficiency, but in the case of high purity red (the CIE color coordinate X value is large), as shown in FIG. It is difficult to obtain external quantum efficiency.

Accordingly, there is a demand for the development of a red phosphorescent compound having high color purity (CIE color purity X = 0.65 or more) while having high light emission efficiency and long light emission life.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, by synthesizing the general formula (1) used as the dopant of the light emitting layer to increase the color purity, red phosphorescent compound that can have a high luminous efficiency and long emission life and an organic electroluminescent device using the same To provide.

The red phosphorescent compound according to the present invention may be a red phosphorescent compound represented by Formula 1 below.

[Formula 1]

는

이다).(In Chemical Formula 1)

Is

to be).

Here, R1, R2, R3, R4, R5 and R6 may each independently be a substituted or unsubstituted C1 to C6 alkyl group, each independently may be a substituted or unsubstituted C1 to C6 alkoxy group, each independently It may be a halogen element of any one of F, Cl, and Br substituted or unsubstituted.

The organic light emitting device according to the present invention may include a light emitting layer between an anode and a cathode, and the compound of Formula 1 may be used as a dopant of the light emitting layer.

Here, the light emitting layer may use any one of Al, Zn metal complex and carbazole derivatives as a host.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention improves the color purity by increasing the conjugation length of ligand by substituting a naphthyl group with a quinoline group, and replacing a methyl group at the 6 position with a quinoline group to provide a red phosphorescent compound having high luminous efficiency and long emission life. Developed.

The present invention provides a red phosphorescent compound represented by the following formula (1).

[Formula 1]

는

이다.Where, in Formula 1

Is

to be.

In addition, R1, R2, R3, R4, R5 and R6 may each independently be a substituted or unsubstituted C1 to C6 alkyl group.

At this time, the alkyl group of C1 to C6 may be selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl and t-butyl.

In addition, R1, R2, R3, R4, R5 and R6 may each independently be a substituted or unsubstituted C1 to C6 alkoxy group.

At this time, the alkoxy group of C1 to C6 may be selected from the group consisting of methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy and t-butoxy.

In addition, R1, R2, R3, R4, R5 and R6 may each independently be a halogen element of any one of F, Cl and Br which is substituted or unsubstituted.

는 2,4-펜테인다이온(

), 2,2,6,6,-테트라메틸헵테인-3,5-다이온(

), 1,3-프로페인다이온(

), 1,3-부테인다이온(

), 3,5-헵테인다이온(

), 1,1,1-트라이플루오로-2,4-펜테인다이온(

), 1,1,1,5,5,5-헥사플루오로-2,4-펜테인다이온(

) 및 2,2-다이메틸- 3,5-헥세인다이온(

) 중 어느 하나일 수도 있다.In Chemical Formula 1 of the present invention,

Is 2,4-pentane ion (

), 2,2,6,6, -tetramethylheptane-3,5-dione (

), 1,3-propane ion (

), 1,3-butanedione (

), 3,5-heptanedionate (

), 1,1,1-trifluoro-2,4-pentaneionate (

), 1,1,1,5,5,5-hexafluoro-2,4-pentaneionate (

) And 2,2-dimethyl-3,5-hexanedione (

) May be any one.

는 하기 화합물들,Next, in Chemical Formula 1 of the present invention,

Are the following compounds,

It may be any one of.

And, the compound of Formula 1 is the following compounds,

It may be any one of.

On the other hand, the organic light emitting device according to the invention is made of a structure including a light emitting layer between the anode and the cathode, the compound of Formula 1 can be used as a dopant of the light emitting layer.

Here, the light emitting layer may use any one of Al, Zn metal complex and carbazole derivatives as a host.

At this time, the ligand of the Al, Zn metal complex is made of any one of the quinolyl, biphenylyl, isoquinolyl, phenylyl, methylquinolyl, methylquinolyl, dimethylquinolyl, dimethylisoquinolyl group, carbazole It is preferable that a derivative consists of CBP.

In the present invention, the amount of dopant used in the light emitting layer is preferably about 0.1% by weight to 50% by weight.

Hereinafter, a synthesis method for some of the red phosphorescent compounds used in the organic light emitting device according to the present invention will be described.

Synthesis Example

(1) Synthesis method of 2- (1-naphthyl) -6-methylquinoline

1-naphthylboric acid (12 mmol), 2-chloro-6-methylquinoline (10 mmol), tetrakis (triphenylphosphine) palladium (0) (0.5) in a dried two-neck round bottom flask (two-neck-rbf) mmol) and potassium carbonate (30 mmol) were dissolved in tetrahydrofuran (60 ml) and distilled water (20 ml), stirred at about 100 degrees for about 6 hours, and after the reaction was completed, tetrahydrofuran was removed.

Subsequently, the mixture was extracted using dichloromethane and water, and then distilled under reduced pressure to perform silica gel column.

Then, the solvent was distilled off under reduced pressure and recrystallized using dichloromethane and petroleum ether to obtain 2- (1-naphthyl) -6-methylquinoline as a product.

(2) Synthesis method of chloro-crosslinked iridium dimer complex

Iridium (III) chloride (5 mmol) and 2- (1-naphthyl) -6-methylquinoline (12 mmol) were added to a solution (40 ml) mixed with 2-ethoxyethanol: distilled water 3: 1, and about 24 Reflux for time.

Next, the solid formed by adding water was filtered and then washed with methanol and petroleum ether to obtain a chloro crosslinked iridium dimer complex.

(3) Synthesis method of iridium (III) bis (2- (1-naphthyl) -6-methylquinolinato-N, C ^{2 '} ) (2,4-pentanedionate-O, O)

Chloro-crosslinked iridium dimer complex (2 mmol), 2,4-pentanedione (6 mmol) and sodium carbonate (6 mmol) were added to 2-ethoxyethanol (30 ml) and refluxed for about 8 hours.

Then, after cooling to room temperature, distilled water was added to give a solid after filtration.

Thus, the formed solid was dissolved in ichloromethane and filtered using silica gel, and dichloromethane was removed under reduced pressure and washed with methanol and petroleum ether to obtain a compound.

Example

Example 1

The light emitting area of the ITO glass substrate was patterned to be 3 mm × 3 mm in size, and then washed.

Subsequently, after mounting the substrate in a vacuum chamber, the base pressure is 1 × 10 ⁻⁶ torr.

 Next, an organic material was formed on an ITO glass substrate in the order of CuPC (200 kPa), NPD (400 kPa), BAlq + A-1 (7%) (200 kPa), Alq3 (300 kPa), LiF (5 kPa), Al (1000 kPa). .

The device manufactured as described above exhibited about 1186 cd / m ² (5.8 V) at about 0.9 mA, where CIE x = 0.682 and y = 0.294.

In addition, the lifetime (half the initial luminance) was about 5000 hours at about 2000 cd / m ² .

Example 2

The light emitting area of the ITO glass substrate was patterned to be 3 mm × 3 mm in size, and then washed.

Subsequently, after mounting the substrate in a vacuum chamber, the base pressure is about 1 × 10 ⁻⁶ torr.

Next, an organic material was formed on an ITO glass substrate in the order of CuPC (200 Pa), NPD (400 Pa), BAlq + A-3 (7%) (200 Pa), Alq3 (300 Pa), LiF (5 Pa), Al (1000 Pa). .

The device manufactured as described above exhibited about 1027 cd / m ² (5.9 V) at about 0.9 mA, where CIE x = 0.687 and y = 0.294.

In addition, the lifetime (half of the initial luminance) was about 4800 hours at about 2000 cd / m ² .

Example 3

The light emitting area of the ITO glass substrate was patterned to be 3 mm × 3 mm in size, and then washed.

Subsequently, after mounting the substrate in a vacuum chamber, the base pressure is 1 × 10 ⁻⁶ torr.

Next, an organic material was formed on an ITO glass substrate in the order of CuPC (200 kPa), NPD (400 kPa), Balq + A-34 (7%) (200 kPa), Alq3 (300 kPa), LiF (5 kPa), Al (1000 kPa). .

The device manufactured as described above exhibited about 1450 cd / m ² (6.3 V) at about 0.9 mA, where CIE x = 0.620 and y = 0.302.

In addition, the lifetime (half the initial luminance) was about 5300 hours at about 2000 cd / m ² .

Example 4

The light emitting area of the ITO glass substrate was patterned to be 3 mm × 3 mm in size, and then washed.

Subsequently, after mounting the substrate in a vacuum chamber, the base pressure is 1 × 10 ⁻⁶ torr.

Next, an organic material was formed on an ITO glass substrate in the order of CuPC (200 kPa), NPD (400 kPa), Balq + A-45 (7%) (200 kPa), Alq3 (300 kPa), LiF (5 kPa), Al (1000 kPa). .

The device manufactured as described above exhibited about 980 cd / m ² (6.2 V) at about 0.9 mA, where CIE x = 0.693 and y = 0.295.

In addition, the lifetime (half the initial luminance) was about 4500 hours at about 2000 cd / m ² .

Comparative example

The light emitting area of the ITO glass substrate was patterned to be 3 mm × 3 mm in size, and then washed.

Subsequently, after mounting the substrate in a vacuum chamber, the base pressure is 1 × 10 ⁻⁶ torr.

Next, the organic material was deposited on an ITO glass substrate of CuPC (200 kPa), NPD (400 kPa), BAlq + (btp) 2Ir (acac) (7%) (200 kPa), Alq3 (300 kPa), LiF (5 kPa), Al (1000 kPa). The tabernacle was in order.

The device manufactured as described above exhibited about 780 cd / m ² (7.5 V) at about 0.9 mA, where CIE x = 0.659 and y = 0.329.

In addition, the lifetime (half of the initial luminance) was about 2500 hours at about 2000 cd / m ² .

According to the above Examples and Comparative Examples, the efficiency characteristics, color coordinates, luminance characteristics, and lifetime characteristics of the fabricated organic light emitting display device are summarized in Table 1 below.

device Voltage (V) Current (mA) Brightness (cd / m2) Current efficiency (cd / A) Power Efficiency (lm / W) Quantum Efficiency (%) CIE (X) CIE (Y) Life (h) Example 1 5.8 0.9 1186 11.86 6.4 18% 0.682 0.294 5000 Example 2 5.9 0.9 1027 10.27 5.5 17% 0.687 0.294 4800 Example 3 6.3 0.9 1450 14.50 7.2 15% 0.620 0.302 5300 Example 4 6.2 0.9 980 9.80 5.0 17% 0.693 0.295 4500 Comparative Example 1 7.5 0.9 780 7.80 3.3 10% 0.659 0.329 2500

As such, the organic light emitting display device of the present invention may have a driving voltage of at least about 6.5 V or less, a luminance of at least about 950 cd / m ² or more, and a lifetime of about 4500 hours or more.

By producing a red phosphorescent compound according to the present invention to a compound having the structure of formula (1), and using the compound in the light emitting layer of the organic light emitting device, there is an effect of obtaining an organic electroluminescent device of high color purity, high brightness, long life have.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (14)

Red phosphorescent compound represented by the following formula (1): [Formula 1]

(In Chemical Formula 1)

Is

to be). The red phosphorescent compound of claim 1, wherein R 1, R 2, R 3, R 4, R 5, and R 6 are each independently a substituted or unsubstituted C 1 to C 6 alkyl group. 3. The red phosphorescent compound of claim 2, wherein the C1 to C6 alkyl group is selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl and t-butyl. . The red phosphorescent compound of claim 1, wherein R 1, R 2, R 3, R 4, R 5, and R 6 are each independently a substituted or unsubstituted C 1 to C 6 alkoxy group. The compound of claim 4, wherein the alkoxy group of C 1 to C 6 is selected from the group consisting of methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy and t-butoxy. Characterized by a red phosphorescent compound. The red phosphorescent compound of claim 1, wherein R 1, R 2, R 3, R 4, R 5, and R 6 are each independently a halogen element of any one of F, Cl, and Br, which is substituted or unsubstituted. The method of claim 1, wherein

Is 2,4-pentane ion (

), 2,2,6,6, -tetramethylheptane-3,5-dione (

), 1,3-propane ion (

), 1,3-butanedione (

), 3,5-heptanedionate (

), 1,1,1-trifluoro-2,4-pentaneionate (

), 1,1,1,5,5,5-hexafluoro-2,4-pentaneionate (

) And 2,2-dimethyl-3,5-hexane ions (

Red phosphorescent compound, characterized in that any one of). The method of claim 1, wherein

Is a red phosphorescent compound, characterized in that any one of the following compounds:

The red phosphorescent compound of claim 1, wherein the compound of Formula 1 is any one of the following compounds:

In the organic light emitting device comprising a light emitting layer between the anode and the cathode, An organic electroluminescent device comprising the compound of any one of claims 1 to 9 as a dopant of the light emitting layer. The organic light emitting device of claim 10, wherein the light emitting layer uses any one of Al, Zn metal complex, and carbazole derivative as a host. The ligand of the Al and Zn metal complexes according to claim 11, wherein the ligand of the Al, Zn metal complex is any one of a quinolyl, biphenylyl, isoquinolyl, phenylyl, methylquinolyl, methylquinolyl, dimethylquinolyl, dimethylisoquinolyl group And, the carbazole derivative is an organic light emitting device, characterized in that consisting of CBP. The organic light emitting device of claim 10, wherein the dopant is used in an amount of 0.1 wt% to 50 wt%. 11. The organic light emitting device of claim 10, wherein the organic light emitting device has a driving voltage of at least 6.5 V, a luminance of at least 950 cd / m ² , and a lifetime of at least 4500 hours.

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