TWI614241B - Organic electroluminescent devices and material thereof - Google Patents

Abstract

The present invention provides a material of an organic electroluminescent device having a structure as shown in the following chemical formula (I):

Wherein X is S or O, Ar ₁ is a substituted or unsubstituted C ₆ to C ₁₈ aryl group, and R _{1 is} selected from H and a substituted or unsubstituted C ₃ to C ₁₂ alkyl group, a cycloalkyl group, an aromatic group. A group consisting of bases.

Description

Organic electroluminescent device and its materials

The present invention relates to an organic electroluminescent device and a material thereof, and more particularly to a material which can be used for an illuminating layer of an organic electroluminescent device.

Organic light-emitting diodes (OLEDs) are light-emitting elements fabricated using the principle of organic electroluminescence (OEL). The principle of illuminating means that after a certain electric field, the electron holes are respectively passed through a hole transport layer (HTL) and an electron transport layer (ETL), and then enter an organic substance having luminescent properties (organic Light-emitting layer). When electrons and holes recombine in the luminescent layer, an "exciton" is formed first, and then the energy is released and returned to the ground state, and the released energy will be Part of it is released in the form of light of different colors to make the OLED emit light.

Commonly used OLED elements are mixed into a single host luminescent material in a dopant luminescent material to give the elements a different color.

(玻璃轉移溫度：96.9℃)等多種藍色 客體材料，然仍無法滿足商業化要求，開發更優良的藍色客體材料為各廠商努力的目標。 At present, there are already 4,4'-Bis[4-(di-p-Fluorophenyl Amino)styryl]biphenyl on the market.

(Blue glass transition temperature: 96.9 ° C) and other blue guest materials, but still can not meet the commercial requirements, the development of better blue guest materials for the efforts of various manufacturers.

The present invention provides a novel organic electroluminescent device material having a compound structure and product characteristics that are different from the prior art.

In detail, an organic electroluminescent device using the material of the novel structure of the present invention as a light-emitting guest material has higher component efficiency than an organic electroluminescent device using a conventional light-emitting guest material. The novel material has a high glass transition temperature (Tg), has good thermal stability when applied to an industrial process, and has the advantages of easy preparation and purification. This novel material also has better luminous efficiency and power efficiency.

According to an aspect of the invention, there is provided a material for an organic electroluminescent device having a structure represented by the following chemical formula (I):

Wherein X is S or O, Ar ₁ is a substituted or unsubstituted C ₆ to C ₁₈ aryl group, and R _{1 is} selected from H and a substituted or unsubstituted C ₃ to C ₁₂ alkyl group, a cycloalkyl group, an aromatic group. A group consisting of bases.

Further, wherein Ar ₁ may be substituted or unsubstituted benzene, naphthalene or biphenyl.

Further, wherein R ₁ may be selected from the group consisting of H and substituted or unsubstituted methyl, ethyl, t-butyl, benzene, naphthalene.

Moreover, the structure of the above materials may be one of the following chemical formulas:

Further, the above material can be used as a light-emitting object of an organic electroluminescent device.

According to another aspect of the present invention, an organic electroluminescent device is provided. The device comprises a layered structure arranged in the following order: a transparent substrate, an anode layer, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode layer. The luminescent layer of this device contains the above materials.

Further, the above material can be used as a light-emitting object of the light-emitting layer.

Further, in the above device, the hole injection layer may be further included between the anode layer and the hole transport layer.

Further, in the above device, an electron injecting layer may be further included between the electron transporting layer and the cathode layer.

Further, the anode layer and the cathode layer of the device are respectively in contact with an external power source to form an electrical path.

In order to make the above and other aspects of the present invention more comprehensible, the embodiments are described in detail below.

1‧‧‧ glass substrate

10‧‧‧Organic electroluminescent device

2‧‧‧ITO (anode layer)

3‧‧‧ hole injection layer

4‧‧‧ hole transport layer

5‧‧‧Lighting layer

6‧‧‧Electronic transport layer

7‧‧‧ cathode layer

Fig. 1A is a ¹ H NMR spectrum of the compound BD1, and Fig. 1B is a mass spectrum of the compound BD1.

Fig. 2A is a ¹ H NMR spectrum of the compound BD4, and Fig. 2B is a mass spectrum of the compound BD4.

Figure 3 is a schematic diagram of an organic electroluminescent device.

The material of an organic electroluminescent device provided by the present invention has the structure shown by the following chemical formula (I):

、苯及萘

。 In the formula (I), X is S or O. Ar ₁ is a substituted or unsubstituted C ₆ to C ₁₈ aryl group including, but not limited to, substituted or unsubstituted benzene, naphthalene or biphenyl. R _{1 is} selected from the group consisting of H and substituted or unsubstituted C ₃ to C ₁₂ alkyl, cycloalkyl, aryl groups, including but not limited to substituted or unsubstituted methyl, ethyl, third Butyl

, benzene and naphthalene

.

"Substituted" means that the H on the alkyl, cycloalkyl or aryl group is replaced by another structure such as, but not limited to, methyl, F, Cl, Br and I.

The "group of substituted or unsubstituted C ₃ to C ₁₂ alkyl, cycloalkyl, aryl groups" means that the group contains: a substituted C ₃ to C ₁₂ alkyl group, a substituted cycloalkyl group. A substituted aryl group, an unsubstituted C ₃ to C ₁₂ alkyl group, an unsubstituted cycloalkyl group, and an unsubstituted aryl group.

Similarly, a group consisting of substituted or unsubstituted methyl, ethyl, tert-butyl, benzene, naphthalene means that this group contains: substituted methyl, substituted ethyl, substituted Tert-butyl, substituted benzene, substituted naphthalene, unsubstituted methyl, unsubstituted ethyl, unsubstituted tert-butyl, unsubstituted benzene, and unsubstituted naphthalene.

Similarly, "substituted or unsubstituted benzene, naphthalene or biphenyl" means: substituted benzene, substituted naphthalene, substituted biphenyl, unsubstituted benzene, unsubstituted naphthalene or unsubstituted biphenyl .

The material of the formula (I) can be used as an illuminating guest material of an organic electroluminescent device, and has a heterocyclic structure Dibenzofuran, which can effectively improve electron transporting ability. The 4 position of dibenzofuran is attached to the amine, which can adjust the displacement of its spectral color to dark blue, so it can be used for blue light-emitting objects. In addition, the material of the formula (I) also has a spiro structure, which can effectively block the conjugate in the molecule and increase the energy level width. Because the spiro ring structure has high molecular rigidity, it can effectively increase the glass transition temperature (Tg) of the material and increase its thermal stability.

The above formula (I) material can be obtained, for example, by the following synthesis method:

Step. 1

The above steps are also called Buchwald coupling reaction, and the novel material of the invention is synthesized by the method, the reaction time is short and the preparation is easy, the product conversion ratio can be effectively improved, the by-product formation is reduced, and the purification difficulty is reduced.

The invention is explained in more detail below by means of several application examples, but the invention is not limited by the scope of the embodiments.

Example 1: Synthesis of 1-Bromo-8-(4-chloro-phenyl)-naphthalene (Compound 1) of bromo-8-(4-chlorophenyl)-naphthalene

2000 ml three-necked flask was placed with 57.19 g of 1,8-Dibromo-naphthalene, 34.40 g of 4-Chlorophenylboronic acid, 55.28 g of potassium carbonate and 6.93 g of four (three) Palladium-tetrakis (triphenylphosphine), placed under a nitrogen system, added with 1000 ml of tetrahydrofuran (THF) and 500 ml of deionized water, heated to reflux, and stirred. Mix for 12 hours. After the reaction was cooled, the mixture was extracted with ethyl acetate. The organic layer was collected and concentrated, and then applied to a column column (Hex: EA = 10:1), which was collected and concentrated to give a pale yellow oil. %.

Example 2: 9-Chloro-[spiro-benzene [de]蒽-7,9'-茀] "9-Chloro-[spiro-benzo[de]anthracene-7,9'-fluorene]" (Compound 2) Synthesis:

500 ml three-necked flask was placed with 15.9 g of 1-bromo-8-(4-chlorophenyl)-naphthalene (compound 1), placed under a nitrogen system, added with 250 ml of THF, stirred and dissolved, and then cooled to -85 ° C, dripped 24 ml of n-butyllithium was stirred for 30 minutes, and 14.3 g of 9-fluorenone (Fluoren-9-one) was dissolved in 50 ml of THF, and then dropped into a three-necked flask and stirred for 1 hour. After adding water to the reaction, the mixture was extracted with ethyl acetate. The organic layer was collected and concentrated. 100 ml of acetic acid and 10 ml of hydrochloric acid were added, and the mixture was heated to reflux for 2 hr. After cooling, methanol was added, and solids were precipitated to collect solids, THF was recrystallized and filtered to give a white solid. The product was dried to obtain 13 g, and the yield was 65%.

Example 3: 3-bromo-9-chloro-[spiro-benzene [de]蒽-7,9'-茀] "3-bromo-9-chloro-[spiro-benzo[de]anthracene-7,9' Synthesis of -fluorene] (Compound 3)

A 250 ml three-necked flask was charged with 10.02 g of 9-chloro-benzene [spiro-[de]蒽-7,9'-茀] (Compound 2), placed under a nitrogen system, and 100 ml of 1,2-dichloroethane was added. The alkane (DCE) was stirred and dissolved. Then, 6.23 g of N-Bromosuccinimide was added and stirred at room temperature for 24 hr. After the reaction was quenched with water, the mixture was extracted with ethyl acetate. The organic layer was collected and concentrated. Recrystallization was carried out, and a white solid was obtained by filtration.

The ¹ H NMR (400 MHz, CDCl ₃ ) measurement of the product: δ 8.08 (dd, 2H), δ 8.03 (d, 1H), δ 7.91 (d, 1H), δ 7.82 (d, 2H), δ 7.37 (t, 2H), δ 7.29 (t, 1H), δ 7.23 (m, 1H), δ 7.13 (t, 2H), δ 6.91 (d, 2H), δ 6.64 (d , 1H), δ6.46 (m, 1H).

Example 4: Synthesis of Dibenzofuran-4-yl-phenyl-amine (Compound 4) of Dibenzofuran-4-yl-phenylamine

Under nitrogen, a 250 ml three-necked flask was charged with 4.66 g of Aniline and 13.59 g of 4-bromo-dibenzofuran, and 250 ml of toluene was stirred and dissolved to add 11.22 g of potassium tert-butoxide. ), 0.56 g of palladium acetate, 1.32 g of Tri-tert-butylphosphine, heated under reflux for 4 hours, cooled, concentrated by filtration, and subjected to column separation (Hex: EA = 10:1) ), the product was obtained in 9.4 g, and the yield was 73%.

¹ H NMR (400 MHz, CDCl ₃ ): δ 7.86 (d, 1H), δ 7.70 (m, 1H), δ 7.53 (d, 1H), δ 7.47 (d, 1H), δ 7.42 ( m, 1H), δ 7.31-7.18 (m, 4H), δ7.01 (d, 2H), δ 6.89 (t, 1H).

Example 5: [spiro-benzene [de] 蒽-7,9'-茀]-3,9-diamine, N3, N9-bis(phenyl)-N3, N9-bis(dibenzofuran-4- "[spiro-benzo[de]anthracene-7,9'-fluorene]-3,9-diamine, N3,N9-bis(phenyl)-N3,N9-bis(dibenzofuran-4-yl)" Synthesis of BD1)

2.73 g of dibenzofuran-4-yl-aniline (compound 4) and 2.40 g of 3-bromo-9-chloro-[spiro-benzene [de]蒽-7,9' were placed in a three-necked flask under nitrogen. - 茀] (Compound 3), 50 ml of toluene was stirred and dissolved to add 2.24 g of potassium t-butoxide, 0.11 g of palladium acetate, 0.26 g of tri-tert-butylphosphoric acid, and the mixture was heated under reflux for 7 hours, and concentrated by cooling to precipitate a solid. Recrystallization, filtration of the product 3.18 g, yield 72%. After purification by sublimation, 2.0 g of product was obtained.

Glass transition temperature (Tg) of BD1: 158.5 °C

¹ H NMR (400 MHz, CDCl ₃ ) measurement of BD1 (refer to Figure 1 A): δ 7.91 (t, 2H), δ 7.70-7.55 (m, 2H), δ 7.50 (d, 2H), δ 7.40-7.25 (m, 8H), δ 7.23-7.00 (m, 10H), δ 7.00-6.80 (m, 12H), δ 6.71 (t, 2H), δ 6.49 (m, 1H) , δ6.02 (m, 1H).

MS (m/z) measurement of BD1 (refer to Figure 1 B): [M ⁺ ]calcd.for C ₆₅ H ₄₀ N ₂ O ₂ , 881.0; found, 881.1

Example 6: Synthesis of (6-phenyl-dibenzofuran-4-yl)-phenyl-amine (Compound 5)

Under nitrogen, a four-necked flask of 250 ml was charged with 4.66 g of aniline and 17.71 g of 4-bromo-6-phenyl-dibenzofuran, and 250 ml of toluene was stirred and dissolved to add 11.22 g of the third. Potassium butoxide, 0.56 g of palladium acetate, 1.32 g of tri-tert-butylphosphorus, heated to reflux for 6 hours, cooled, concentrated by filtration, subjected to column separation (Hex: EA = 10:1), yielding 12.1 g of product. The rate is 73%.

¹ H NMR (400 MHz, CDCl ₃ ): δ 7.92 (dd, 1H), δ 7.85 (m, 2H), δ 7.58 (dd, 1H), δ 7.53 - 7.43 (m, 3H), Δ7.42-7.38 (m, 2H), δ 7.36-7.29 (m, 3H), δ 7.27-7.18 (m, 3H), δ7.01 (t, 1H).

Example 7: [Spiro-benzene [de]蒽-7,9'-茀]-3,9-diamine, N3,N9-bis(phenyl)-N3,N9-bis(6-benzene-dibenzo [spiro-benzo[de]anthracene-7,9'-fluorene]-3,9-diamine, N3,N9-bis(phenyl)-N3,N9-bis(6-phenyl-dibenzofuran- Synthesis of 4-yl) (Compound BD4)

3.52 g of (6-benzene-dibenzofuran-4-yl)aniline was placed in a three-necked flask under nitrogen. Compound 5) and 2.40 g of 3-bromo-9-chloro-[spiro-benzene [de]蒽-7,9'-fluorene] (Compound 3), 50 ml of toluene were stirred and dissolved to add 2.24 g of potassium t-butoxide. 0.11 g of palladium acetate and 0.26 g of tri-tert-butylphosphorus were heated and refluxed for 7 hours. After cooling and concentration, a solid was precipitated, which was recrystallized from THF and filtered to give the product 2.84 g, yield 55%. .

Glass transition temperature (Tg) of BD4: 181.9 °C

¹ H NMR (400 MHz, CDCl ₃ ) measurement of BD4 (refer to Fig. 2A): δ 8.19 - 8.01 (m, 2H), δ 7.88 (dd, 2H), δ 7.79 - 7.65 (m, 2H) ), δ7.62-7.52 (m, 4H), δ 7.49 (d, 2H), δ 7.44 - 7.35 (m, 4H), δ 7.31-7.18 (m, 6H), δ 7.14 - 7.01 ( m, 14H), δ7.00-6.91 (m, 4H), δ 6.86 (t, 2H), δ 6.77 (d, 2H), δ 6.63 (t, 2H), δ 6.42 (m, 1H) ), δ 5.97 (m, 1H).

MS (m/z) measurement of BD4 (refer to Figure 2B): [M ⁺ ]calcd.for C ₇₇ H ₄₈ N ₂ O ₂ ,1033.2;found,1033.2

In particular, although two different materials and their synthesis methods are described in the above embodiments 1-7, the material of the present invention is not limited thereto. According to the synthesis method of the above embodiment, the reactants of Steps. 1 are adjusted, and Step 2. 2 can synthesize a plurality of different materials. The combination can be as shown in Table 1 below:

Step. 2

Example 8: Organic electroluminescent device test

Please refer to FIG. 3, which illustrates the structure of the organic electroluminescent device 10 used in the embodiment. The organic electroluminescent device 10 of the present embodiment is mainly prepared by vacuum evaporation, and comprises a glass base. Plate 1, ITO 2 (anode layer), hole injection layer 3 (HIL), hole transport layer (HTL), luminescent layer 5 (including host luminescent material and guest luminescent material), An electron transport layer (ETL) and a cathode layer 7. The anode layer 2 and the cathode layer 7 are respectively in contact with an external power source to form an electrical path. This embodiment uses this device to test the characteristics of the organic electroluminescent device of the present invention.

In particular, the organic electroluminescent device of the present invention is not limited to the above aspect in practical use, and the structure can be adjusted as needed. For example, an electron injection layer (EIL) may be designed between the electron transport layer 6 and the cathode layer 7, or the hole injection layer 3 may be omitted. The present invention does not limit the structure of the organic electroluminescent device. .

The organic electroluminescent device of the present invention is characterized in that the light-emitting layer uses the material of the present invention as a light-emitting guest (the above-mentioned compounds BD1, 4), and a conventional BD material is used as a comparative example. In addition, the materials used in the other layers of the organic electroluminescent device of the embodiment and the comparative example are identical, as follows:

Substrate 1: Glass

Anode layer 2: indium tin oxide (ITO)

Hole Injection Layer (HIL) 3: CuPC 70nm

Hole Transport Layer (HTL) 4: NPB

Light-emitting layer 5: as shown in Table 2 below

Electron Transport Layer (ETL) 6: 25 nm Tris(8-hydroxyquinoline)aluminum (Alq3)

Cathode layer 7: LiF 1 nm, Al 150 nm

The test results are listed in Table 2:

It can be seen from Table 2 that the organic electroluminescent device using the material of the present invention as a luminescent material has a lower on-voltage (a reduction of about 5%) and a higher luminous efficiency than an organic electroluminescent device using the conventional luminescent material BD. (increased by up to about 25%) and power efficiency (up to about 27%). In addition, the above materials are simple to prepare, easy to synthesize and purify, and have potential for commercial application. Moreover, the glass transition temperature (Tg) of the above-mentioned luminescent material of the present invention is higher than 150 ° C, and has excellent thermal stability during processing compared to the low glass transition temperature (96.9 ° C) of the comparative luminescent material BD. .

Although the present invention has been described above by way of examples, the embodiments are not intended to limit the invention. It is to be understood by those of ordinary skill in the art that the invention may be practiced or modified without departing from the spirit and scope of the invention.

1‧‧‧ glass substrate

10‧‧‧Organic electroluminescent device

2‧‧‧ITO (anode layer)

3‧‧‧ hole injection layer

4‧‧‧ hole transport layer

5‧‧‧Lighting layer

6‧‧‧Electronic transport layer

7‧‧‧ cathode layer

Claims (10)

A material for an organic electroluminescent device having the structure shown by the following chemical formula (I): Wherein Ar ₁ is a substituted or unsubstituted C ₆ to C ₁₈ aryl group, and R _{1 is} selected from the group consisting of H and a substituted or unsubstituted C ₃ to C ₁₂ alkyl group, a cycloalkyl group, an aryl group. . The material of claim 1, wherein Ar ₁ is substituted or unsubstituted benzene, naphthalene or biphenyl. The material of claim 1, wherein R _{1 is} selected from the group consisting of H and substituted or unsubstituted methyl, ethyl, t-butyl, benzene, naphthalene. The material described in claim 1 is structured as one of the following chemical formulas: BD4 BD5 BD6 The material of any one of claims 1 to 4, which is a luminescent object of an organic electroluminescent device. An organic electroluminescent device comprising a layered structure arranged in the following order: a transparent substrate, an anode layer, a hole transport layer, a light emitting layer, an electron transport layer and a cathode layer; the organic electroluminescent device is characterized by: The light-emitting layer contains the material described in any one of claims 1 to 4. The device of claim 6, wherein the illuminating layer of the luminescent layer is the material of any one of claims 1 to 4. The device of claim 6, wherein the anode layer and the hole transport layer further comprise a hole injection layer. The device of claim 6, wherein the electron transport layer and the cathode layer further comprise an electron injection layer. The device of claim 6, wherein the anode layer and the cathode layer are respectively in contact with an external power source to form an electrical path.