KR100705982B1 - Blue light-emitting compound and display device adopting blue light-emitting compound - Google Patents

Abstract

The present invention provides a blue light emitting compound that generates a spectrum of visible blue region as a trans complex of platinum (II) ions and two phosphine ligands, and a display device employing the same as a light emitting material. The light emitting compound according to the present invention is useful as a light emitting material of a display device because of excellent color purity as a blue light emitting material. In addition, the display device according to the present invention has the blue light emitting compound as a light emitting material and is superior in color purity as compared with the case where a conventional blue light emitting compound is used.

Description

Blue light-emitting compound and display device adopting blue light-emitting compound

1 is a photoluminescence spectrum of a blue light emitting compound according to the present invention.

2 is a cross-sectional view of an organic electroluminescent device employing a blue light emitting compound according to the present invention as a light emitting material.

3 and 4 are diagrams showing emission spectra of organic electroluminescent devices prepared and evaluated according to Evaluation and Preparation Examples 1 and 2;

<Explanation of symbols for the main parts of the drawings>

11 substrate 12 anode

13 hole transport layer 14 light emitting layer

15 electron transport layer 16 cathode

The present invention relates to a blue light emitting compound which is a platinum (II) trans complex having excellent color purity and a display element employing the same as a light emitting material.

Among the display elements, an electroluminescence device (EL device) is a self-luminous display element having advantages of wide viewing angle, excellent contrast and fast response speed.

EL elements are classified into inorganic EL elements and organic EL elements according to materials for forming an emitting layer. Herein, the organic EL device has an advantage of excellent luminance and driving voltage characteristics and full colorization as compared with the inorganic EL device.

In 1987, Eastman Kodak Co., Ltd. developed for the first time an organic EL device using a low molecular weight aromatic diamine and an aluminum complex as a material for forming a light emitting layer [Appl. Phys. Lett. 51, 913, 1987].

On the other hand, compounds such as diphenylanthracene, tetraphenylbutadiene, and distyrylbenzene derivatives have been developed as blue fluorescent light emitting materials for use in organic EL devices, but are known to have a tendency to crystallize easily due to poor film stability. Another blue light emitting material is a diphenyl distyryl-based compound [H. Tokailin, H. Higashi, C. Hosokawa, EP 388,768 (1990)], distyrylanthracene derivatives [Pro. SPIE, 1910, 180 (1993)], and Iridium complex (FIrpic) of Universal Display Coropration which carries out phosphorescence emission is known [Appl. Phys. Lett. Vol 79, Number 13 (2001).

However, these compounds have a lower color purity and lifespan even if the phosphors emit light in the electroluminescent device having lower luminous efficiency than those of other color light emitting compounds or phosphorescent luminous materials having high luminous efficiency. Accordingly, the development of new high efficiency, high color purity and long life blue light emitting compounds suitable for blue light emitting devices and full color light emitting devices is an urgent problem.

The technical problem to be achieved by the present invention is to provide a blue light emitting compound excellent in color purity and excellent luminous efficiency.

Another technical problem of the present invention is to provide a display device employing the blue light emitting compound as a light emitting material.

In order to achieve the above technical problem, the present invention provides a light emitting compound that generates a spectrum of the blue region of visible light as a trans complex of platinum (II) ions and two phosphine ligands.

Preferably, the blue light emitting compound according to the present invention is a compound represented by the following Chemical Formulas 1 to 3.

In the above formula, R ₁ to R ₅ are each independently hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, Secondary amine and tertiary amine, and L ₁ to L ₃ are each independently selected from an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms.

는 탄소수 6 내지 26의 방향족기이다.Wherein R ₁ to R ₅ are hydrogen or a group consisting of an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, a secondary amine and a tertiary amine, and L ₁ to L ₃ Irrespective of each other, an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms are selected.

Is an aromatic group having 6 to 26 carbon atoms.

Wherein R ₆ to R ₁₃ are each independently selected from hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, a secondary amine and a tertiary amine, and L ₄ to L ₅ are each independently selected from an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms.

The other technical problem is achieved by a display device employing a blue light emitting compound which is a trans complex of the platinum (II) ion and two phosphine ligands as a light emitting material. Preferred display elements of the present invention include organic EL elements.

Hereinafter, a blue light emitting compound and a display device using the same according to the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments, but only the embodiments are provided to make the disclosure of the present invention complete and to fully inform the person skilled in the art the scope of the present invention. Like reference numerals in the drawings denote like elements.

The light emitting compound according to the present invention is a blue light emitting compound that generates a spectrum of blue region of visible light as a trans complex of platinum (II) ions and two phosphine ligands.                     

Specifically, the platinum (II) trans complex according to the present invention is preferably a compound represented by the following formula (1).

<Formula 1>

In the above formula, R ₁ to R ₅ are each independently hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, Secondary amine and tertiary amine, and L ₁ to L ₃ are each independently selected from an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms.

Preferably R ₁ to R ₅ is any one selected from the group consisting of the following formula irrespective of each other.

Platinum (II) trans complex according to the present invention may be represented by the following formula (2).

<Formula 2>

는 탄소수 6 내지 26의 방향족기이다. 바람직하기로는 상기

는 하기 화학식들로 이루어진 군으로부터 선택된 어느 하나이다. Wherein R ₁ to R ₅ are hydrogen or a group consisting of an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, a secondary amine and a tertiary amine, and L ₁ to L ₃ Irrespective of each other, an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms are selected.

Is an aromatic group having 6 to 26 carbon atoms. Preferably the above

Is any one selected from the group consisting of

In addition, the platinum (II) trans complex according to the present invention may be represented by the following formula (3).

<Formula 3>

Wherein R ₆ to R ₁₃ are each independently selected from hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, a secondary amine and a tertiary amine, and L ₄ to L ₅ are each independently selected from an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms.

Preferably the R ₆ to R ₁₃ is any one selected from the group consisting of the following formula.

1 is a photoluminescence spectrum measured after dissolving the platinum (II) trans complex according to the present invention represented by the following formula in a chloroform diluent (10 ^-5 M).

As shown in Fig. 1, it can be seen that the wavelength at which the maximum peak appears is 438 nm, which shows blue light emission.

Hereinafter, a method of manufacturing a display device according to the present invention will be described. As a display element, the organic EL element shown in FIG. 2 is taken as an example and the manufacturing method is demonstrated.

First, an anode 12 is formed by coating an anode electrode material on the substrate 11. As the substrate 11, a substrate used in a conventional organic EL device is used. A glass substrate or a transparent plastic substrate excellent in transparency, surface smoothness, ease of handling, and waterproofness is preferable. As the anode electrode material, indium tin oxide (ITO), indium zinc oxide (IZO), etc., which are transparent and have excellent conductivity, are used.

The hole transport layer 13 is formed by vacuum deposition or spin coating a material for forming a hole transport layer on the anode 12.

The hole transport layer 13 material is not particularly limited, and N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1'-biphenyl] -4,4'-diamine (TPD), N, N'-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine {N, N'-di (naphthalene-1-yl) -N, N'-diphenyl-benzidine : α-NPB} and the like.

Subsequently, a light emitting layer 14 is deposited on the hole transport layer 13 by depositing a blue light emitting compound that generates a spectrum in the blue region of visible light with a trans complex of platinum (II) ions and two phosphine ligands according to the present invention. Form.

 The light emitting layer 14 may be formed by depositing a blue generating compound according to the present invention alone, and may be 4,4'-N, N'-dicarbazole-biphenyl (CBP) or 2,9-dimethyl-4,7. It can also be formed by doping and depositing the blue light emitting compound according to the present invention at 0.5 to 10% with diphenyl-1,10-phenanthroline (BCP) as a host.

After that, a cathode 16 is formed by vacuum depositing a metal for forming a cathode on the light emitting layer 14 to complete the organic EL device. The metal for forming the cathode may be lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver ( Mg-Ag) and the like.

The electron transport layer 15 may be formed on the emission layer 14 before the cathode is formed. This electron transporting layer uses a conventional material for forming an electron transporting layer.

Hereinafter, the present invention will be described in detail with reference to specific experimental examples, but the present invention is not limited to the following experimental examples.

Synthesis Example

<1. Compound of Formula 1>

The synthesis method of the compound of Formula 1 is as follows.

2.5 mmol (1.04 g) of potassium tetrachloroplatinate (II) and 5.5 mmol of triethylphosphine dissolved in tetrahydrofuran were refluxed in 50 mL distilled water at 100 DEG C for 2 hours. The precipitate produced was recrystallized from methylene chloride-ethanol to obtain 1.5 mmol (0.8 g) of cis-triethylphosphine platinum (II) complex. 1.0 mmol (0.50 g) of this cis complex and 2.2 mmol (0.24 mL) of phenylacetylene were heated together with 0.1 mmol copper iodide in 10 mL diethylamine at 80 to 90 ° C. for 20 minutes to obtain a product. Thus obtained product was subjected to column chromatography to give 0.52 mmol (0.17 g) of the compound of formula 1 (yield: 52%). The structure of this compound was confirmed by ¹ H-NMR spectrum and mass spectrometry (m / z = 633). The graph below shows the ¹ H-NMR spectrum.

<Compound of Formula 3>

The synthesis method of the compound of Formula 3 is as follows.

α, α '- dibromo - m - xylene, (α, α' -dibromo- m -xylene ) 5.0 mmol (1.31 g) and potassium diphenyl phosphide (potassium diphenylphosphide) to 14 mmol (3.4 mL) tetrahydro After dissolving in 20 ml of furan (Tetrahydrofuran), the mixture was stirred at room temperature for 20 hours to obtain 2.5 mmol (0.8 g) of α , α '-bis (diphenylphosphino) -m -xylene. Meanwhile, 2.2 mmol (0.913 g) of potassium tetrachloroplatinate (II) and 7.7 mmol (0.946 mL) of 1,5-cyclooctadiene were dissolved in 22 mL of acetic acid. It stirred at 90 degreeC for 30 minutes, and obtained 1.7 mmol (1.0 g) of 1, 5- cyclooctadieno dichloro platinum (II) complexes. 0.5 mmol (0.15 g) of α , α' -bis (diphenylphosphino) -m -xylene and 0.5 mmol (0.19 g) of 1,5-cyclooctadienodichloroplatinum (II) complex obtained above were prepared in 2- ( With 0.06 mL of methylamino) ethanol, it was dissolved in 30 mL of mesitylene and refluxed for 10 hours. After completely removing the solvent from the reaction mixture, 0.3 mmol (0.2 g) of α , α' -bis (diphenylphosphino) -m -xylenechloroplatin (II) complex was obtained by column chromatography. 0.25 mmol (0.15 g) of the complex and 0.6 mmol (0.07 mL) of phenylacetylene were heated together with 0.05 mmol copper iodide in 5 mL diethylamine at 80-90 ° C. for 1 hour to obtain a product. The product thus obtained was purified by column chromatography to obtain 0.04 mmol (0.10 g) of the compound of formula 3 (yield: 15%). The structure of this compound was confirmed by <^1> H-NMR spectrum. The graph below shows the ¹ H-NMR spectrum.

Fabrication and Characterization of Organic EL Devices

<Production and Evaluation Example 1>

After the ITO electrode was formed on the glass substrate, TPD was vacuum-deposited on the glass substrate to form a hole transport layer having a thickness of 400 kPa.

Subsequently, a platinum (II) trans complex according to the present invention represented by the following formula on the hole transport layer was deposited to a thickness of 300 mW, and a BCP was formed to a thickness of 300 mW to form an emission layer.

An organic EL device was fabricated by depositing an Al: Li alloy on the light emitting layer to form an aluminum lithium electrode having a thickness of 1500 mW.

The result of measuring electrophosphorescence of the manufactured organic EL device is shown in FIG. 3. The maximum luminescence peak was observed at 450 nm.

<Production and Evaluation Example 2>

An ITO electrode was formed on the glass substrate, and then NPB was vacuum deposited on the glass substrate to form a hole transport layer having a thickness of 500 kPa.

Subsequently, 8% of the platinum (II) trans complex according to the present invention represented by the following chemical formula on the BCP host was formed using a thermal codeposition method, and the light emitting layer was formed by forming a BCP layer having a thickness of 100 μs with a 300 μs doped material layer. Was completed.

Tris (8-quinolinato) aluminum (III) (Alq) was vacuum-deposited on the light emitting layer to form an electron transport layer having a thickness of 200 Å.

An organic EL device was fabricated by depositing an Al: Li alloy on the electron transport layer to form an aluminum lithium electrode having a thickness of 1500 mW.

The result of measuring electrophosphorescence of the manufactured organic EL device is shown in FIG. 4. The maximum emission peak could be observed at 452 nm, and the value of the Commission Internationale de L'Eclairage (CIE) coordinate system was measured as (x = 0.158, y = 0.150). This value is closer to the pure blue coordinates (x = 0.16, y = 0.18) than the CIE coordinate values (x = 0.16, y = 0.29) of the blue-emitting iridium complex (FIrpic) of Universal Display Coropration. It can be seen that the value.

The blue light emitting compound which generates the spectrum of the blue region of visible light with the trans complex of platinum (II) ion and two phosphine ligands according to the present invention is excellent in color purity and is useful as a light emitting material of a display device.

In addition, the display device according to the present invention uses the blue light emitting compound of the present invention as a light emitting material, and has excellent color purity and improves luminous efficiency and luminance characteristics as compared with the case of using a conventional blue light emitting compound.

Claims (17)

A blue light emitting compound that generates a spectrum of blue region of visible light as a trans complex of platinum (II) ion and two phosphine ligands. The blue light emitting compound according to claim 1, wherein the phosphine ligand is a tertiary phosphine substituted with an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms irrespective of each other. The blue light emitting compound according to claim 1 or 2, wherein the compound is represented by the following Chemical Formula 1. <Formula 1>

Wherein R ₁ to R ₅ are each independently hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, Secondary amine and tertiary amine, and L ₁ to L ₃ are independently selected from alkyl groups having 1 to 18 carbon atoms and aromatic groups having 6 to 24 carbon atoms. The blue light emitting compound of claim 3, wherein R ₁ to R ₅ are any one selected from the group consisting of the following formulas irrespective of each other.

The blue light emitting compound of claim 1 or 2, wherein the compound is represented by the following Chemical Formula 2. <Formula 2>

Wherein R ₁ to R ₅ are selected from hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, a secondary amine and a tertiary amine, and L ₁ L ₃ is selected from an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms, irrespective of each other,

Is an aromatic group having 6 to 26 carbon atoms. The method of claim 5, wherein

Is a blue light emitting compound, characterized in that any one selected from the group consisting of:

The blue light emitting compound according to claim 1 or 2, wherein the compound is represented by the following Chemical Formula 3. <Formula 3>

Wherein R ₆ to R ₁₃ are each selected from the group consisting of hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, a secondary amine and a tertiary amine irrespective of each other; L ₄ to L ₅ are each independently selected from an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms. The blue light emitting compound of claim 7, wherein R ₆ to R ₁₃ are any one selected from the group consisting of the following Chemical Formulas regardless of each other.

A display device comprising a blue luminescent compound which generates a spectrum in the blue region of visible light as a trans complex of platinum (II) ions and two phosphine ligands, as a light emitting material. The display device according to claim 9, wherein the phosphine ligand is a tertiary phosphine substituted with an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms irrespective of each other. The display device according to claim 9 or 10, wherein the compound is represented by the following Chemical Formula 1. <Formula 1>

Wherein R ₁ to R ₅ are each independently hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, Secondary amine and tertiary amine, and L ₁ to L ₃ are independently selected from alkyl groups having 1 to 18 carbon atoms and aromatic groups having 6 to 24 carbon atoms. The display device of claim 11, wherein R ₁ to R ₅ are any one selected from the group consisting of the following formulas irrespective of each other.

The display device according to claim 9 or 10, wherein the compound is represented by the following Chemical Formula 2. <Formula 2>

Wherein R ₁ to R ₅ are selected from hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, a secondary amine and a tertiary amine, and L ₁ L ₃ is selected from an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms, irrespective of each other,

Is an aromatic group having 6 to 26 carbon atoms. The method of claim 13, wherein

The display device, characterized in that any one selected from the group consisting of the following formula.

The display device according to claim 9 or 10, wherein the compound is represented by the following Chemical Formula 3. <Formula 3>

Wherein R ₆ to R ₁₃ are each independently selected from hydrogen or an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aromatic group having 6 to 24 carbon atoms, a secondary amine and a tertiary amine. L ₄ to L ₅ are each independently selected from an alkyl group having 1 to 18 carbon atoms and an aromatic group having 6 to 24 carbon atoms. The display device of claim 15, wherein R ₆ to R ₁₃ are any one selected from the group consisting of the following formulas irrespective of each other.

The display device according to claim 9 or 10, wherein the display device is an organic electroluminescent device.

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