KR100681472B1 - Polyphenylbenzenes for organic electroluminescent materials - Google Patents

Abstract

Provided is a novel blue fluorescence material, which has excellent stability, and is used in an organic electroluminescence device as a hole injection, hole transport or light emitting material to improve the light emitting efficiency. The blue fluorescence material is represented by the following formula (I), wherein Ar1 and Ar2 which are the same or different represent a substituted or non-substituted phenyl, naphthyl or anthracenyl group, and R1 and R2 which are the same or different represent a hydrogen atom, a C1-C4 alkyl or an aryl-substituted tertiary amine.

Description

Polyphenylbenzenes for organic electroluminescent materials

1 is a view showing the structure of the organic electroluminescent device manufactured in the present invention,

2 and 3 show the absorption and fluorescence spectra of the representative compounds synthesized in the present invention,

4 and 5 are cyclic voltammetry (CV) spectra,

6 and 7 show a current density-voltage characteristic curve comparing the conventional compound and device characteristics by applying the compound synthesized in the present invention to the hole transport layer and the hole injection layer of the device.

An organic electroluminescent display device (OLED) is one of a kind of electronic device that places an organic semiconductor material between an electrode plate of an anode and a cathode and emits light of a specific color according to an applied current. An anode on a glass substrate is usually laminated with a transparent electrode called ITO and laminated in the order of a hole injection layer (HIL), a hole transport layer (HTL), a light emitting layer (EML), an electron transport layer (ETL), and a metal cathode. Tang et al., 1987, published in Applied Physics Letters, Vol. 51, pp. 913, described an organic electroluminescent device with good multi-layer structure.

In order for the organic electroluminescent display device (OLED) to have a higher efficiency, it is necessary to achieve more balanced recombination of holes and electrons in the light emitting layer. Efforts have been made to obtain efficient light emission from organic electroluminescent display devices (OLEDs). First, novel electron transfer materials having higher electron mobility and efforts to lower the electron injection barrier by modifying the cathode material are described in US Pat. Nos. 4,885,211 and 5,059,862 and 5,766,779, respectively. Meanwhile, US Pat. No. 6,603,150 to Tang et al. Has pursued a technical purpose of achieving more balanced recombination by stacking an interface layer between a hole transport layer and a light emitting layer.

SUMMARY OF THE INVENTION An object of the present invention is to provide novel compounds having blue luminescence properties to make organic electroluminescent display devices (OLEDs) with improved efficiency, and to prepare these compounds and to inject these compounds into hole injection materials or hole transport materials. Or to provide an organic electroluminescent device comprising a light emitting material.

The purpose of the above

a) glass substrate;

b) ITO transparent anode;

c) a hole injection layer to a hole transport layer;

d) a light emitting layer;

e) an electron transport layer;

d) It is achieved by using a new material represented by the following general structural formula (I), including the cathode in order, as the hole injection material of the hole injection layer, the hole transport material of the hole transport layer, or the light emitting material of the light emitting layer.

Wherein Ar ₁ and Ar ₂ represent a phenyl, naphthyl or anthracenyl group which is the same as or differently substituted or unsubstituted, and R ₁ and R ₂ are hydrogen or C1 to C4 alkyl or aryl-substituted tertiary Amines.

-NPD등이 소자구동중의 안정성 측면에서 미흡할정도의 정공주입능력 및 정공전달 특성으로 인해 발광층에서 효과적인 정공,전자 재결합이 일어나기 어려울뿐만 아니라 그 자체의 열안정성도 만족스럽지 못한점에 착안하여 본 발명자들은 유기전기발광디스플레이소자(OLED)물질로서 열안정성이 우수하고 정공주입 및 정공전달 특성과 발광특성이 우수한 신규물질을 사용함으로써 발광층에서의 정공,전자 재결합의 균형을 추구하여 안정성이 우수하면서도 높은 효율의 유기전기발광디스플레이소자(OLED)를 제공하고자한다.CuPc or 2-TNATA used as the hole injection layer in the previous technologies, and TPD used mainly as the hole transport layer.

Due to the hole injection ability and hole transfer characteristics that NPD does not have in terms of stability during device driving, effective hole and electron recombination is difficult to occur in the light emitting layer, and its thermal stability is not satisfactory. The inventors pursued a balance of hole and electron recombination in the light emitting layer by using a novel material having excellent thermal stability, excellent hole injection, hole transporting characteristics, and luminescent properties as an organic electroluminescent display device (OLED) material. An organic electroluminescent display device (OLED) of efficiency is provided.

In order to achieve the above object, the present invention provides a novel blue fluorescent substance of the general formula (I).

Wherein Ar ₁ and Ar ₂ represent a phenyl, naphthyl or anthracenyl group which is the same as or differently substituted or unsubstituted, and R ₁ and R ₂ are hydrogen or C1 to C4 alkyl or aryl-substituted tertiary Amines.

The present invention also provides a method for preparing the compound of Formula (I) and an organic electroluminescent device comprising the compound in a hole injection layer or a hole transport layer and a light emitting layer.

Hereinafter, the present invention will be described in more detail.

The synthesis process of the novel blue fluorescent substance of the general formula (I) according to the present invention is represented by the following reaction scheme.

or,

In the formula, Ar, Ar ₁ and Ar ₂ represent a substituted or unsubstituted phenyl, naphthyl or anthracenyl group, and R, R ₁ and R ₂ represent hydrogen or an alkyl or arylsubstituted tertiary amine of C1 to C4. .

The general formula (I) compound provided in the present invention has a glass transition temperature (Tg) of 150 ^° C. or higher, which significantly improves thermal stability compared to conventional materials and has good film characteristics. It is judged to be a compound with great applicability to electronic device materials. The specific example represented by general formula (I) is as follows. However, the present invention is not limited to the structure shown below.

Meanwhile, the brominated substituted nuxaphenylbenzene compound of formula (II), which is used as a starting material for synthesizing the present invention, was described by Mulen et al. In 1999 in Angew. Chem., Int. Ed. Publications on pages 38, 3039 and 111, 3224, and 2004, Chem. Commun. Apply the same method as presented on page 336 and synthesize as follows.

The compound of general formula (I) of the present invention exhibits excellent properties as a hole injection layer or a hole transport layer and a blue light emitting layer material of the organic electroluminescent device. When the compound of the present invention is used as the hole injection layer, the organic electroluminescent device After forming the compound of the general formula (I) of the present invention on the ITO glass substrate as a hole injection layer, the hole transporting layer, the light emitting layer and the electron transporting layer are sequentially laminated in the usual manner, and then the cathode metal electrode is laminated. Can be. After forming a hole injection layer with another hole injection material in the same manner, the compound of the general formula (I) of the present invention can be laminated with a hole transport layer, and then laminated with a light emitting layer, an electron transport layer, a cathode layer in order to manufacture a device, When the material of the present invention is used as a light emitting layer, a light blue light can be obtained by forming a layer of a compound of the general formula (I) in the light emitting layer in the same multilayer structure. Expression is possible.

The hole transport layer, the light emitting layer and the electron transport layer of the organic electroluminescent device may be deposited by wet coating or vacuum deposition such as spin coating, doctor blading, roll printing or screen printing, and the metal electrode may be coated by vacuum deposition. The material used to form the electron transport layer may be any known material, and examples of the metal electrode for the cathode may include magnesium, silver, calcium, aluminum, lithium, and alloys thereof.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the method presented in the Examples.

Preparation Example: Preparation of Dibromohexaphenylbenzene Derivative Compound of Formula (II)

50 g (0.177 mol) of 1-bromo-4-iodobenzene was dissolved in 150 mL of triethylamine with 4.08 g (3.5 mmol) of Pd (PPh ₃ ) ₄ and 1.68 g (8.84 mmol) of CuI, and the mixture was stirred at room temperature for 5 minutes under nitrogen stream. After that, 25 mL (0.177 mol) of trimethylsilylacetylene is injected for 30 minutes and stirred at room temperature for 30 minutes. After confirming that all reactions were lost by TLC, 1L of hexane was added to the mixture to remove some impurities, passed through silica gel to remove the by-products of the origin, and the solvent was removed under reduced pressure to give trimethylsilyl-substituted bromoeti as a white solid. Obtain nielbenzene. (43.5g, yield 97.2%)

40 g (0.158 mol) of the compound obtained above are stirred at room temperature with 43.7 g of K ₂ CO ₃ under a mixed solvent of 50 mL of dichloromethane and 150 mL of methyl alcohol. After filtration to remove insoluble salts, the filtrate was extracted with dichloromethane and distilled under reduced pressure to give 1-Bromo-4-ethynylbenzene as a white solid (28g, yield 98.2%).

45 g (0.249 mol) of 1-Bromo-4-ethynylbenzene obtained above was dissolved in 180 mL of triethylamine with 5.73 g (4.98 mmol) of Pd (PPh ₃ ) ₄ and 2.367 g (12.43 mmol) of CuI, and the mixture was cooled to 5 After stirring, 77.4 g (0.273 mol) of 1-bromo-4-iodobenzene was added thereto, followed by stirring at room temperature for 2 hours. After confirming the reaction by TLC, 500 mL of dichloromethane was added, stirred for 10 minutes, filtered and washed with methyl alcohol and acetone to obtain dibromodiphenylacethylene as a pale yellow solid. (75.2 g, 90% yield)

15 g (44.6 mmol) of dibromodiphenylacethylene and 17.16 g (44.6 mmol) of tetraphenylcyclopentadienone were added to 30 ml of phenyl ether and refluxed for 3 hours. After confirming the reaction ona wash by TLC, the reaction solution was cooled to 60 ^o C, 60 mL of THF was added and refluxed for 10 minutes. After cooling to room temperature, 300 mL of methyl alcohol was slowly added to solidify and filtered to obtain a compound of formula (II) as a pale yellow solid. (19 g, yield 30.9%)

Example 1

9.487 g (13.7 mmol) of the compound of formula (II), 5.21 g (30.8 mmol) of diphenylamine, 31 mg (0.137 mmole) of Pd (OAc) ₂ , 56 mg (0,276 mmol) of P (t-Bu) ₃ , and 3.26 g (32.9 mmol) of NaOt-Bu was added to 20 mL of Xylene, and the temperature was raised to 120 ^° C. under a nitrogen stream, followed by stirring at that temperature for 3 hours. After confirming the completion of the reaction by TLC, the reaction mixture was cooled to 60 ^o C, 10 mL of THF was added and stirred for 5 minutes. The mixed solution thus obtained was gradually added to 200 mL of methyl alcohol, solidified, filtered, washed and dried to obtain the compound of formula (1) in the form of a pale yellow solid. (6.1 g, yield 51%)

Example 2

Except for using 6.75 g (30.8 mmol) of naphthale-2-ylphenylamine instead of diphenylamine in Example 1, the same procedure was followed to obtain a compound of formula (2) in light yellow solid form. (5.9 g, yield 42%)

Example 3

The same procedure was followed as in Example 1, except that 6.75 g (30.8 mmol) of naphthale-1-ylphenylamine was used instead of diphenylamine to obtain a compound of formula (3) in a pale yellow solid form. (6.6 g, yield 45%)

Example 4

18.0 g (26.0 mmol) of compound of formula (II), 7.44 g (52.0 mmol) of 2-aminonaphthalene, 596 mg (0.65 mmole) of Pd ₂ (dba) ₃ , 300 mg (1.48 mmol) of P (t-Bu) ₃ and NaOt- 6.0 g (62.4 mmol) of Bu is added to 40 mL of Xylene, and the temperature is raised to 120 ^° C. under a nitrogen stream, followed by stirring at that temperature for 12 hours. After completion of the reaction by TLC, the reaction mixture was cooled to 60 ^o C and 10 mL of THF was added and stirred for 5 minutes. The mixed solution was gradually added to 200 mL of methyl alcohol, solidified, filtered, washed and dried to give a gray solid. Get The gray solid thus obtained was 16,2 g (50.0 mmol) of (4-bromophenyl) diphenylamine, 49.6 mg (0.219 mmole) of Pd (OAc) ₂ , 90 mg (0,442 mmol) of P (t-Bu) ₃ and 5.22 g of NaOt-Bu. (54.3 mmol) was added to 40 mL of Xylene, and the temperature was raised to 120 ^o C under a nitrogen stream and stirred at that temperature for 3 hours. After confirming the completion of the reaction by TLC, the reaction mixture was cooled to 60 ^o C, 10 mL of THF was added and stirred for 5 minutes. The mixed solution thus obtained was gradually added to 200 mL of methyl alcohol, and then solidified, filtered, washed and dried to obtain the compound of formula (9) in the form of a pale yellow solid. (13.0 g, yield 38%)

Example 5

In Example 4, except that 1-aminonaphthalene 7.44g (52.0 mmol) instead of 2-aminonaphthalene was carried out in the same manner as in Example 4, the compound of formula (10) was obtained in a pale yellow solid form. (14.7g, Yield 43.4%)

Example 6 Fabrication of Organic Electroluminescent Device

-NPD를 사용하여 동일하게 제작한 유기전기발광소자와 특성을 비교하였다.Using the compound (2) obtained in Example 2 as a hole transport layer material, an organic electroluminescent device was manufactured according to a conventional method and used as a conventional hole transport layer material.

The characteristics were compared with the organic electroluminescent device fabricated using -NPD.

First, a hole transport layer having a thickness of 50 nm was formed on the ITO layer formed on the glass substrate under the vacuum of 10 ^-6 Torr using the compound (2) obtained in Example 2, and the deposition rate of Alq3 as a light emitting layer was 0.3 mW / sec. To a thickness of 300 kPa to form a light emitting layer. An organic electroluminescent device was fabricated by depositing a thickness of 1500 kW at a rate of 10 kW / sec under a vacuum of 10 ^-6 Torr so that aluminum and lithium were 10 to 1 as cathode metals on the light emitting layer.

-NPD를 사용하여 50 nm 두께의 정공수송층을 형성시키고, 그 위에 발광층으로서 Alq3를 그리고 캐쏘드 금속으로 알루미늄과 리튬이 10대 1이 되도록 증착시켜 비교할 유기전기발광소자를 제작하였다In the same way, it has been used as a conventional hole transport material

A 50 nm-thick hole transport layer was formed using -NPD, and Alq3 was formed as a light emitting layer and aluminum and lithium were deposited to 10 to 1 by a cathode metal, thereby fabricating an organic electroluminescent device to be compared.

The structure of the device is shown in FIG. 1 and the applied voltage and current density characteristic curves are shown in FIG. The device of the present invention emits light stably and can implement a device having better characteristics than the existing hole transport layer.

Example 7

Using the compound (10) obtained in Example 5 as a hole injection layer material, an organic electroluminescence device was manufactured according to a conventional method, and an organic electroluminescence was produced in the same manner using 2-TNATA used as a conventional hole injection layer material. The device and characteristics were compared.

-NPD를 사용하여 30 nm 두께의 정공수송층을 형성시켰다.그 위에 발광층으로서 Alq3를 0.3Å/초의 증착속도로 300Å의 두께로 증착시켜 발광층을 형성시켰다. 이 발광층 위에 캐쏘드 금속으로서 알루미늄과 리튬이 10대 1이 되도록 10^-6 토르의 진공하에 10Å/초 의 속도로 1500Å의 두께로 증착시켜 유기전기발광소자를 제작하였다.First, a hole injection layer having a thickness of 40 nm was formed on the ITO layer formed on the glass substrate by using the compound (10) obtained in Example 5 under a vacuum of 10 ⁻⁶ Torr, and as a hole transport layer thereon.

-NPD was used to form a hole transport layer having a thickness of 30 nm. On top of this, Alq3 was deposited as a light emitting layer to a thickness of 300 mW at a deposition rate of 0.3 mW / sec to form a light emitting layer. An organic electroluminescent device was fabricated by depositing a thickness of 1500 kW at a rate of 10 kW / sec under a vacuum of 10 ^-6 Torr so that aluminum and lithium were 10 to 1 as cathode metals on the light emitting layer.

-NPD를 정공수송층을, 발광층으로서 Alq3를 그리고 캐쏘드 금속으로 알루미늄과 리튬을 증착시켜 비교할 유기전기발광소자를 제작하였다In the same manner, a hole injection layer is formed using 2-TNATA, which has been used as a conventional hole injection layer material, and then

The organic electroluminescent device to be compared was fabricated by depositing -NPD as a hole transport layer, Alq3 as a light emitting layer, and aluminum and lithium as a cathode metal.

The current density-voltage characteristic curves of the devices are shown in FIG. The device of the present invention emits light stably and can implement a device having better characteristics than the existing hole injection layer.

The blue fluorescent dye for organic electroluminescence of the present invention is a useful material for producing an organic electroluminescent device having excellent stability as a hole injection material and a hole transport material, and when used as a light emitting layer, the emission color is blue to green depending on the type of dopant to be used together. It is a useful light emitting material that can be expressed up to the region, and may be applied to the development of organic photoconductors, solar cells, etc., including organic electroluminescent devices.

Claims (3)

The novel blue fluorescent substance represented by the following general formula (I).

Wherein Ar ₁ and Ar ₂ represent a phenyl, naphthyl or anthracenyl group which is the same as or differently substituted or unsubstituted, and R ₁ and R ₂ are hydrogen or C1 to C4 alkyl or aryl-substituted tertiary Amines. The blue fluorescent substance according to claim 1, which has a structure of any one of the following structural formulas.

An organic electroluminescent device using the blue fluorescent material according to claim 1 as a hole injection layer, a hole transport layer or a light emitting layer.

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