HK1228369B - Organic electronic material - Google Patents

Description

Organic electronic materials

Technical Field

The invention relates to a novel organic electroluminescent material, which is deposited into a thin film by vacuum evaporation and applied as a blue electroluminescent material on an organic electroluminescent diode, belonging to the technical field of organic electroluminescent device display.

Background Art

As a new display technology, organic electroluminescent devices have unique advantages such as self-luminescence, wide viewing angle, low energy consumption, high efficiency, thinness, rich colors, fast response speed, wide applicable temperature range, low driving voltage, flexible, bendable and transparent display panels, and environmental friendliness. Therefore, organic electroluminescent device technology can be used in flat panel displays and new generation lighting, and can also be used as a backlight source for LCDs.

Organic light-emitting devices (OLEDs) are fabricated by spin-coating or depositing a layer of organic material between two metal electrodes. A typical three-layer OLED consists of a hole transport layer, a light-emitting layer, and an electron transport layer. Holes generated by the anode, via the hole transport layer, combine with electrons generated by the cathode, via the electron transport layer, to form excitons in the light-emitting layer, which then emit light. OLEDs can emit red, green, and blue light by varying the material in the light-emitting layer. Therefore, stable, efficient, and color-pure OLED materials are crucial for the application and promotion of OLEDs and are urgently needed for the widespread application of large-area OLED displays.

Among the three primary colors (red, blue, and green), red and green light materials have recently made significant progress and meet the market demand for panels. A range of commercially available blue light materials are also available. Among the most widely used early on were Idemitsu Kosan Co., Ltd.'s distyryl biphenyl (DPVBi) compounds. Devices made with these compounds have high efficiency, but these materials often have poor stability. Furthermore, the color of their emission is sky blue, with a CIE value of y > 0.15. Therefore, their poor temperature resistance and impure color have greatly limited their application in full-color display devices. Another class of blue light materials include Kodak's ADN and tetra-tert-butylperylene, but these compounds suffer from relatively poor luminous efficiency and poor stability, preventing their widespread use.

Summary of the Invention

The present invention overcomes the defects of the above compounds and provides a series of organic electroluminescent blue light materials with good thermal stability, high luminous efficiency and high luminous purity. The organic electroluminescent devices prepared from them have the advantages of good electroluminescent efficiency, excellent color purity and long life.

The organic electronic material of the present invention has the structural formula (I):

wherein R ₁ -R ₁₇ independently represent hydrogen, a deuterium atom, a halogen, a cyano group, a nitro group, a C1-C8 alkyl group, a C1-C8 alkoxy group, a C6-C30 substituted or unsubstituted aryl group, a C3-C30 substituted or unsubstituted aryl group containing one or more heteroatoms, a C2-C8 substituted or unsubstituted alkene group, or a C2-C8 substituted or unsubstituted alkynyl group; wherein Ar ₁ -Ar ₃ independently represent a C6-C60 substituted or unsubstituted aryl group, a C3-C60 substituted or unsubstituted heteroaryl group containing one or more heteroatoms, or a triaromatic (C6-C30)amine group.

Preferably, R ₁ -R ₁₇ are independently hydrogen, halogen, cyano, nitro, C1-C8 alkyl, C1-C8 alkoxy, C2-C8 substituted or unsubstituted alkenyl, C2-C8 substituted or unsubstituted alkynyl, C1-C4 alkyl substituted or unsubstituted phenyl, C1-C4 alkyl substituted or unsubstituted naphthyl, or are combined to form C1-C4 alkyl substituted or unsubstituted fluorenyl; Ar ₁ -Ar ₃ independently represents a C1-C4 alkyl or C6-C30 aryl substituted phenyl group, a C1-C4 alkyl or C6-C30 aryl substituted naphthyl group, a phenyl group, a naphthyl group, a pyridyl group, a N-C6-C30 aryl group or a C1-C4 alkyl substituted carbazolyl group, a dibenzothiophenyl group, a dibenzofuranyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, a (9,9-dialkyl)fluorenyl group, a (9,9-dialkyl substituted or unsubstituted aryl)fluorenyl group, or a 9,9-spirofluorenyl group.

Preferably: wherein, R ₁ -R ₂ can be independently preferably represented by hydrogen, halogen, C1-C4 alkyl, C1-C4 alkyl substituted or unsubstituted phenyl, C1-C4 alkyl substituted or unsubstituted naphthyl, or combined to form C1-C4 alkyl substituted or unsubstituted fluorenyl; wherein, R ₃ -R ₁₇ can be independently preferably represented by hydrogen, halogen, C1-C4 alkyl, C1-C4 alkyl substituted or unsubstituted phenyl, C1-C4 alkyl substituted or unsubstituted naphthyl, preferably Ar ₁ -Ar ₃ are independently represented by phenyl, tolyl, xylyl, tert-butylphenyl, naphthyl, pyridyl, methylnaphthalene, biphenyl, diphenylphenyl, naphthylphenyl, diphenylbiphenyl, diaromaticaminophenyl, N-phenylcarbazolyl, (9,9-dialkyl)fluorenyl, (9,9-dialkyl substituted or unsubstituted phenyl)fluorenyl, 9,9-spirofluorenyl.

Preferably: wherein, R ₃ -R ₁₇ are preferably hydrogen, R ₁ and R ₂ can independently preferably represent hydrogen, methyl, ethyl, propyl, isopropyl, tert-butyl, phenyl, biphenyl, naphthyl, or combine to form fluorenyl; Ar ₁ -Ar ₃ independently represent phenyl, pyridyl, tolyl, xylyl, naphthyl, methylnaphthalene, biphenyl, diphenylphenyl, naphthylphenyl, diphenylbiphenyl, (9,9-dialkyl)fluorenyl, (9,9-dimethyl substituted or unsubstituted phenyl)fluorenyl, 9,9-spirofluorenyl.

Preferably, R ₃ to _{R 17} are hydrogen; R ₁ and R ₂ are independently hydrogen, methyl, or combined to form fluorenyl; Ar ₁ , Ar ₂ , and Ar ₃ are independently phenyl or naphthyl.

Preferred:

Application of the above organic electronic materials in the fields of organic electroluminescent devices, organic solar cells, organic thin film transistors or organic photoreceptors.

As mentioned above, the specific embodiments of the present invention are as follows, but are not limited to the structures listed:

The organic electronic material provided by the present invention can be made into an organic electroluminescent device, which comprises an anode, a cathode and one or more organic layers, at least one of which contains the organic electronic material described in structural formula I.

The multiple organic layers are respectively a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer and/or an electron injection layer. It should be noted that the above organic layers can be used as needed, and not every organic layer needs to be present.

The hole transport layer, electron transport layer and light emitting layer contain organic materials as described in Structural Formula 1.

The hole transport layer and hole injection layer in the present invention require materials with excellent hole transport properties, capable of effectively transporting holes from the anode to the organic light-emitting layer. They can include small molecule and polymer organic materials, including, but not limited to, triaromatic amine compounds, diphenyl diamine compounds, thiazole compounds, oxazole compounds, imidazole compounds, fluorene compounds, phthalocyanine compounds, hexanitrilehexaazatriphenylene, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4-TCNQ), polyvinylcarbazole, polythiophene, polyethylene, and polyphenylsulfonic acid.

The organic electroluminescent layer of the present invention may contain, in addition to the compound of structural formula (I) of the present invention, the following compounds, but is not limited thereto, naphthalene compounds, pyrene compounds, fluorene compounds, phenanthrene compounds, chrysene compounds, fluoranthene compounds, anthracene compounds, pentacene compounds, perylene compounds, diarylvinyl compounds, triphenylamine compounds, amine compounds, benzimidazole compounds, furan compounds, and organic metal chelates.

The organic electron transport material used in the organic electronic device of the present invention is required to have excellent electron transport properties and be able to effectively transport electrons from the cathode to the light-emitting layer. The following compounds can be selected, but are not limited to them, oxazolidines, thiazole compounds, triazole compounds, triazoxide compounds, triazabenzene compounds, oxaline compounds, diazaanthracene compounds, silicon-containing heterocyclic compounds, quinoline compounds, phenanthroline compounds, metal chelates, and fluorine-substituted benzene compounds.

The organic electronic device of the present invention may be added with an electron injection layer as needed. The electron injection layer can effectively inject electrons from the cathode into the organic layer. The electron injection layer is mainly selected from alkali metals or alkali metal compounds, or from alkaline earth metals or alkaline earth metal compounds. The following compounds can be selected, but are not limited to, lithium, lithium fluoride, lithium oxide, lithium nitride, 8-hydroxyquinoline lithium, cesium, cesium carbonate, 8-hydroxyquinoline cesium, calcium, calcium fluoride, calcium oxide, magnesium, magnesium fluoride, magnesium carbonate, and magnesium oxide.

Device experiments have shown that the organic electronic material of formula (I) has good thermal stability, high luminous efficiency, and high luminous purity. Organic electroluminescent devices made with this organic luminescent material have the advantages of good electroluminescent efficiency, excellent color purity, and long life.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a structural diagram of a device according to the present invention,

Among them, 10 represents the glass substrate, 20 represents the anode, 30 represents the hole injection layer, 40 represents the hole transport layer, 50 represents the light emitting layer, 60 represents the electron transport layer, 70 represents the electron injection layer, and 80 represents the cathode.

FIG2 is a ¹ H NMR chart of compound 89.

FIG3 is a ¹³ C NMR chart of compound 89.

FIG4 is the HPLC chart of compound 89.

FIG5 is a TGA chart of compound 89.

FIG6 is a voltage-current density curve of Example 4, Example 5 and Comparative Example 1

FIG7 is a luminance-CIEy coordinate diagram of Example 4, Example 5 and Comparative Example 1

FIG8 is the electroluminescence spectra of Example 4, Example 5 and Comparative Example 1

FIG9 is a current density-current efficiency curve of Example 4, Example 5 and Comparative Example 1

DETAILED DESCRIPTION

In order to describe the present invention in more detail, the following examples are given, but the present invention is not limited thereto.

(Compounds 1a, 1b, 1e, 1h, 3a, and 89a below are commonly available commercially)

Example 1

Synthesis of intermediate 1c

To a reaction flask, add 1a (240.00 g, 0.88 mol), 1b (496.32 g, 1.76 mol), Pd(PPh ₃ ) ₄ (20.35 g, 17.60 mmol), potassium carbonate (302.52 g, 2.20 mol), toluene (2400 mL), and purified water (1200 mL). After purging nitrogen three times, heat the mixture until the reaction temperature reaches 95-105°C and maintain this temperature for 8-12 hours. Samples were taken by TLC and HPLC, indicating complete reaction. Heating was discontinued, the temperature was lowered to 20-30°C, and the filtrate was filtered. The organic layer was separated and the aqueous layer was extracted with ethyl acetate. The combined organic layers were washed with water, dried over anhydrous magnesium sulfate, filtered, and the filtrate was concentrated to yield a dark yellow solid crude product. Recrystallization from petroleum ether afforded an off-white solid with a yield of 90% and a purity of 95%.

Synthesis of intermediate 1d

To a reaction flask, add the appropriate proportions of 1c (302g, 0.78mol), B(OEt) _₃ (142g, 0.97mol), n-BuLi/THF (1.6M, 600mL), and anhydrous THF (3000mL). After purging nitrogen three times, cool the reaction mixture to -75--65°C. Slowly add the n-BuLi/THF solution dropwise, maintaining the reaction temperature between -75--65°C. After complete addition, maintain this temperature for 0.5-1h. Then, add a predetermined amount of B(OEt) _₃ dropwise, maintaining the reaction temperature between -75--65°C. After complete addition, maintain this temperature for 0.5-1h. The reaction mixture is then brought to room temperature and allowed to warm naturally for 4-6h. Then, add 2M dilute hydrochloric acid to adjust the pH to 2-3. Stir for approximately 1h to terminate the reaction. Ethyl acetate was added for extraction, and the aqueous layer was extracted with EA again. The organic layers were combined, dried over anhydrous magnesium sulfate, filtered, and the filtrate was concentrated to obtain an off-white solid product with a purity of 95% and a yield of 62.5%.

Synthesis of intermediate 1f

To a reaction flask, add 1d (150 g, 0.43 mol), 1e (500 g, 0.86 mol), Pd(PPh ₃ ) ₄ (5.0 g, 0.44 mmol), potassium carbonate (130 g, 0.92 mol), toluene (1000 mL), and purified water (500 mL). Purge nitrogen three times and then turn on the heat. When the reaction temperature reaches 95-105°C, maintain this temperature for 8-12 hours. Samples are taken by TLC and HPLC. If the reaction is complete, discontinue heating, cool to 20-30°C, filter, and separate the organic layer from the filtrate. The aqueous layer is then extracted with ethyl acetate. The combined organic layers are dried over anhydrous magnesium sulfate, filtered, and the filtrate is concentrated to yield a dark yellow solid crude product with a purity of 80% and a yield of 78.1%.

Synthesis of intermediate 1g

Add 1f (210g, 0.42mol), NBS (135g, 0.71mol), and DMF (5L) to the reaction flask. Pump nitrogen three times and start heating. When the reaction liquid temperature reaches 60-65°C, maintain this temperature for 6-8h. Take samples by TLC and HPLC. The raw material reaction is complete. Stop heating, cool to 20-30°C, pour the reaction liquid into ice water, precipitate a dark yellow solid, filter to obtain a yellow solid, and dry to obtain 1g of crude product. Add DCM/MeOH to the crude product until the solution becomes slightly turbid, continue stirring for about 30min, precipitate a large amount of solid, filter to obtain a light yellow solid product with a yield of about 54.05% and a purity of 98.5%.

¹ H NMR (300MHz, CDCl ₃ )δ8.64(d,J＝8.8Hz,2H),7.99–7.90(m,4H),7.87(t,J＝1.6Hz,1H),7.78(dd,J＝9.3, 2.3Hz, 6H), 7.61 (ddd, J＝8.8, 6.5, 1.1Hz, 2H), 7.56–7.48 (m, 6H), 7.46–7.38 (m, 4H).

¹³ C NMR (76MHz, CDCl ₃ )δ142.67(s),142.03(s),141.26(s),140.69(s),137.83(s),137.52(s),131.87(s),131.24(s),130.44(s),129.09(s) ,128.80(s),128.38–127.40(m),127.18(s),126.05–125.21(m),123.08(s),77.74(s),77.31(s),76.89(s),30.10(s).

Synthesis of compound 1

To a 500ml three-necked flask were added 1g (9.5g, 16.92mmol), 1h (6.41g, 30.51mmol), Pd(PPh3 _{) 4} (1.5g, 1.3mmol), potassium carbonate (5.84g, 42.3mmol), toluene (150mL), and purified water (75mL). After purging nitrogen three times, the reaction was continued at 105°C. Liquid chromatography indicated a standstill time of approximately 12 hours. Initially, the reaction solution was a khaki-yellow color, similar to the catalyst, which gradually turned into a yellow solution. After the standstill, the upper layer became a clear, light yellow, while the lower layer was water. After the standstill, the reaction was filtered, and the residue was washed with ethyl acetate until no product remained. The filtrate was collected and dried, resulting in a large amount of off-white solid precipitated. The residue was collected and dried to yield the desired product with a purity of 98%. Vacuum sublimation afforded an off-white solid powder with a purity of 99.5%.

¹ H-NMR (300MHz, CDCl ₃ )δ8.10–8.21(d,2H),7.96–7.98(dd,3H),7.87–7.89(m,2H),7.81–7.86(m,4H),7.78–7.81(d,4H),7 .62–7.65(m, 2H), 7.59(s, 1H), 7.51–7.57(m, 5H), 7.45–7.48(m, 2H), 7.36–7.43(m, 7H), 3.88(s, 2H).

Example 2

Synthesis of compound 3

To a 500ml three-necked flask were added 1g (9.5g, 16.92mmol), 3a (7.25g, 30.46mmol), Pd( _PPh3 ) ₄ (1.5g, 1.3mmol), potassium carbonate (5.84g, 42.3mmol), toluene (150mL), and purified water (75mL). After purging nitrogen three times, the reaction was continued at 105°C. Liquid chromatography indicated a standstill time of approximately 12 hours. Initially, the reaction solution was a khaki-yellow color, similar to the catalyst, which gradually turned into a yellow solution. After the standstill, the upper layer became a clear, light yellow, while the lower layer was water. After the standstill, the reaction was filtered, and the residue was washed with ethyl acetate until no product remained. The filtrate was collected and dried, resulting in a large amount of off-white solid precipitated. The residue was collected and dried to yield the desired product with a purity of 98%. Vacuum sublimation afforded an off-white solid powder with a purity of 99.7%.

¹ H-NMR (300MHz, CDCl ₃ )δ8.1–8.2(d,2H),7.96–7.99(dd,3H),7.88–7.89(m,2H),7.81–7.86(m,4H),7.78–7.81(d,4H),7. 61–7.65(m, 2H), 7.59(s, 1H), 7.51–7.56(m, 5H), 7.46–7.48(m, 2H), 7.35–7.43(m, 7H), 1.61(s, 6H).

Example 3

Synthesis of compound 89

To a reaction vessel, 1 g (10.0 g, 17.8 mmol), 89a (7.1 g, 19.6 mmol), Pd(PPh ₃ ) ₄ (432.2 mg, 0.35 mmol), K ₂ CO ₃ (6.14 g, 44.5 mmol), toluene (300 mL), and water (150 mL) were added sequentially. The apparatus was deoxygenated and purged with nitrogen. The mixture was then heated to 100°C and reacted overnight. A plate was spotted with DCM:PE in a ratio of 1:5. The product emitted a strong blue light under a 365 nm UV lamp, with an Rf value of approximately 0.2. The reaction mixture was filtered through silica gel, and the filter cake was washed twice with ethyl acetate (100 mL). The layers were separated, and the aqueous layer was extracted once with ethyl acetate (100 mL). The organic layers were combined and washed once with water (200 mL). The solvent was removed by spin drying. The crude product was recrystallized from 120 ml of DCM/MeOH and filtered to yield 13.1 g of a yellow solid powder with a purity of 98.7% and a yield of 92.2%. Vacuum sublimation afforded a light yellow solid powder with a purity of 99.7%. m/z = 797.

Figures 2 and 3 show that the proton and carbon spectra of compound 89 are completely consistent with its structure. The HPLC chromatogram of compound 89 in Figure 4 demonstrates the high purity of the product prepared according to the synthesis method of the present invention. The thermogravimetric analysis of compound 89 in Figure 5 shows that the decomposition temperature of this type of compound is above 400°C, indicating its very high thermal stability.

Example 4

Preparation of organic electroluminescent device 1

Preparation of OLED using the organic electronic material of the present invention

First, the transparent conductive ITO glass substrate 10 (with the anode 20 thereon) is cleaned in sequence with a detergent solution and deionized water, ethanol, acetone, and deionized water, and then treated with oxygen plasma for 30 seconds.

Then, HAT-CN ₆ was evaporated on the ITO to a thickness of 10 nm as the hole injection layer 30 .

Then, NPB was evaporated to form a hole transport layer 40 with a thickness of 30 nm.

Then, Compound 3 was evaporated to a thickness of 30 nm on the hole transport layer to form the light emitting layer 50 .

Then, TPBi was evaporated to a thickness of 15 nm on the light-emitting layer as the electron transport layer 60 .

Finally, 15 nm BPhen:Li was evaporated to form the electron injection layer 70 and 150 nm Al was evaporated to form the device cathode 80 .

The prepared device has a voltage of 3.58V at an operating current density of 20mA/cm2, a current efficiency of 3.21cd/A, a CIEy coordinate of 0.0853 at a brightness of 1000cd/ ^m2 , and emits blue light.

The structure of the device

Example 5

Preparation of organic electroluminescent device 2

The method is the same as that of Example 4, except that compound 3 is replaced by compound 89 to prepare an organic electroluminescent device.

The prepared device has a voltage of 3.84V at an operating current density of 20mA/cm2, a current efficiency of 2.83cd/A, a CIEy coordinate of 0.0888 at a brightness of 1000cd/ ^m2 , and emits blue light.

Comparative Example 1

The method was the same as that of Example 4, except that compound 3 was replaced by the following compound TAT to prepare an organic electroluminescent device for comparison.

TAT structure

The prepared device has a voltage of 4.00 V at an operating current density of 20 mA/cm2, a current efficiency of 2.46 cd/A, a CIEy coordinate of 0.0952 at a brightness of 1000 cd/ ^m2 , and emits blue light.

Examples 4 and 5 illustrate specific applications of the materials of the present invention. The devices prepared therefrom emit blue light with higher efficiency and brightness than the comparative examples. As described above, the materials of the present invention have high stability, and the organic electroluminescent devices prepared therefrom exhibit high efficiency and light purity.

Claims (7)

1. An organic electronic material having the structural formula described in formula (I): Wherein, _R3 - _R17 independently represent hydrogen, _R1 - _R2 independently represent hydrogen, C1-C8 alkyl, C1-C4 alkyl substituted or unsubstituted phenyl, C1-C4 alkyl substituted or unsubstituted naphthyl, or combined into C1-C4 alkyl substituted or unsubstituted fluorenyl; _Ar1 - _Ar3 independently represent C1-C4 alkyl or C6-C30 aryl substituted phenyl, C1-C4 alkyl or C6-C30 aryl substituted naphthyl, phenyl, naphthyl, pyridyl. 2. The organic electronic material according to claim 1, wherein _R1 - _R2 independently represents hydrogen, C1-C4 alkyl, C1-C4 alkyl-substituted or unsubstituted phenyl, C1-C4 alkyl-substituted or unsubstituted naphthyl, or combined into C1-C4 alkyl-substituted or unsubstituted fluorenyl; _R3 - _R17 independently represents hydrogen, and _Ar1 - _Ar3 independently represents phenyl, tolyl, tert-butylphenyl, naphthyl, pyridyl, methylnaphthalene, biphenyl, diphenylphenyl, naphthylphenyl, diphenylbiphenyl. 3. The organic electronic material according to claim 2, wherein _R3 - _R17 is hydrogen, _R1 and _R2 are independently represented as hydrogen, methyl, ethyl, propyl, isopropyl, tert-butyl, phenyl, naphthyl, or combined to form fluorenyl; _Ar1 - _Ar3 are independently represented as phenyl, pyridyl, tolyl, naphthyl, methylnaphthalene, biphenyl, diphenylphenyl, naphthylphenyl, diphenylbiphenyl. 4. In the organic electronic material according to claim 3, _R3 - _R17 are hydrogen; _R1 and _R2 independently represent hydrogen, methyl, or combined into fluorenyl; _Ar1 , _Ar2 , and _Ar3 independently represent phenyl or naphthyl. 5. The organic electronic material according to claim 1 is a compound with the following structure: 6. The organic electronic material according to claim 5 is a compound with the following structure: 7. The application of the organic electronic material according to any one of claims 1-6 in the fields of organic electroluminescent devices, organic solar cells, organic thin-film transistors or organic photoreceptors.