Novel host material based on seven-membered ring triphenyl [b, d, f] azepine unit

Abstract

The invention relates to the field of organic electroluminescent materials (OLEDs), in particular to a novel host material structure based on a seven-membered ring triphenyl [b, d, f] azepine unit and application of the material in an organic electroluminescent display device. The novel host material based on the seven-membered ring triphenyl [b, d, f] azepine unit has a structure as shown in a formula (1): # imgabs0 #. The invention provides a preparation method of the organic electroluminescent host material based on the seven-membered ring triphenyl [b, d, f] azepine unit and application of the organic electroluminescent host material as the host material to manufacture an organic electroluminescent device.

Description

Technical Field

[0001] The present invention relates to the field of organic electroluminescent materials (OLEDs), and in particular to the structure of a novel organic electroluminescent host material based on a seven-membered ring triphenyl[b,d,f]azepine unit and the application of the material in an organic electroluminescent display device. Background Art

[0002] Organic Light-Emitting Diodes (OLEDs) have been attracting attention from academia and industry as a new technology in the field of display and lighting due to their advantages such as low energy consumption, wide viewing angle, brilliant colors, and flexibility. The electroluminescence phenomenon was first observed by G. Destriau in 1936, but it did not receive the attention it deserved. It was not until 1987 that Dr. Qingyun Deng and others from Eastman Kodak invented a sandwich-type organic double-layer thin-film electroluminescent device, which has since set off a technological boom in OLEDs research worldwide. Among the red, green and blue primary color OLEDs devices, the development of high-performance blue OLEDs has also attracted great attention from academia and industrial production. The use of boron nitrogen (BN) multi-resonance narrow-band luminescent materials to achieve high-performance blue OLEDs has been widely studied and has become a relatively effective approach. However, research on the host material has lagged behind significantly, although it plays an important role in determining device performance.

[0003] In addition to having good host materials, excellent blue light OLED devices must have the following properties: 1. A simple synthesis route enables efficient and rapid large-scale synthesis. 2. The emission spectrum of the host material is wide enough to facilitate energy transfer. 3. The host material has a high triplet energy level to prevent the reverse transfer of triplet energy from the dopant material to the host material. 4. The carriers in the host material can move quickly, thereby avoiding significant quenching of excitons in the device's light-emitting layer. 5. The HOMO / LUMO energy levels of the host material match the energy levels of the adjacent hole transport layer and electron transport layer to reduce the injection barrier and thus lower the device startup voltage. Therefore, we have developed a new type of host material based on a seven-membered ring triphenyl [b, d, f] azepine unit to meet the above requirements. Summary of the Invention

[0004] The purpose of the present invention is to provide a new type of host material based on a seven-membered ring triphenyl [b, d, f] azepine unit.

[0005] The novel host material based on the seven-membered ring triphenyl[b,d,f]azepine unit of the present invention has the structure shown in formula (1):

[0006] In formula (1), Ar represents any one of a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms, a substituted or unsubstituted arylamine group having 6 to 30 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted arylalkylsilyl group having 6 to 30 carbon atoms, a nitro group, a cyano group, and a halogen group.

[0007] Preferably, the molecular structure in formula (1) includes but is not limited to the following structural formula:

[0008] The second object of the present invention is to provide a method for preparing the above-mentioned organic electroluminescent host material, characterized in that the reaction equation occurring during the preparation process is:

[0009] In the reaction formula (1), Y represents a chlorine atom, a bromine atom or an iodine atom.

[0010] The specific reaction steps of the reaction equation are as follows: in a nitrogen or argon atmosphere, a seven-membered ring triphenyl[b,d,f]azepine unit 1 and a halide 2, palladium acetate, tri-tert-butylphosphine tetrafluoroborate, and sodium tert-butoxide are added to a toluene solution, the mixed solution is reacted at 110° C. for 24 hours, and then cooled, filtered through diatomaceous earth, dried under reduced pressure, and subjected to silica gel column chromatography to obtain the target product.

[0011] The molar ratio of the seven-membered ring triphenyl[b,d,f]azepine unit 1 and the halide 2: palladium acetate: tri-tert-butylphosphine tetrafluoroborate: sodium tert-butoxide is (2.2-2.5):1:(0.05-0.1):(0.2-0.5):(3-8).

[0012] The third object of the present invention is to apply a new host material molecule based on a seven-membered ring triphenyl [b, d, f] azapine unit to the production of an organic electroluminescent device, characterized in that the organic electroluminescent device using a phosphorescent material as the light-emitting material comprises, from bottom to top, an ITO conductive glass substrate (anode), a hole transport layer, an electron blocking layer, a light-emitting layer using FIrpic as a blue phosphorescent light-emitting material or FIrpic as a sensitizer and BCz-BN as a blue light-emitting material, doped in the organic electroluminescent host material involved in the present invention), an electron transport layer, an electron injection layer, and a cathode layer.

[0013] The organic electroluminescent device is prepared by vacuum evaporation. The molecular structure of the organic compound used in the device is as follows: The beneficial effects of the present invention are:

[0014] The novel host material molecule based on the seven-membered ring triphenyl [b, d, f] azepine unit provided by the present invention has good thermal stability and morphological stability as well as good photoelectric properties, and its wide emission spectrum can accelerate Energy transfer (FET) process, its high hole transfer rate can significantly avoid exciton quenching.

[0015] The novel material molecule based on the seven-membered ring triphenyl[b,d,f]azepine unit provided by the present invention can be used as a host material to sensitize blue luminescent materials.

[0016] The host material prepared by the present invention is used for the preparation of blue light OLEDs devices, has good device performance, achieves high device efficiency and extremely low efficiency roll-off, and has good industrial application prospects.

[0017] The novel host material molecule based on the seven-membered ring triphenyl[b,d,f]azepine unit prepared by the present invention provides a new design idea for constructing host materials with non-traditional structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the H NMR spectrum of compound A.

[0019] Figure 2 is the C NMR spectrum of compound A.

[0020] Figure 3 is the H NMR spectrum of compound B.

[0021] Figure 4 This is the TGA of compounds A and B.

[0022] Figure 5 DSC of compounds A and B.

[0023] Figure 6 This is a schematic diagram of the structure of an organic electroluminescent device prepared with A and B as the main materials.

[0024] Figure 7 These are the test results of the organic electroluminescent device prepared with A and B as the main materials and FIrpic as the luminescent material.

[0025] Figure 8 These are the test results of the organic electroluminescent device prepared with A and B as the main materials, FIrpic as the sensitizer, and BCz-BN as the luminescent material.

[0026] Figure 9Schematic diagram of the single-hole device structure prepared with A and B as the main materials and the device test results. DETAILED DESCRIPTION

[0027] In order to better understand the content of the present invention, the present invention is explained below with reference to specific examples, which are not intended to limit the scope of the present invention.

[0028] Example 1: Preparation of Compound A Under a nitrogen atmosphere, compound 2 (1.6 g, 4.0 mmol), triphenyl[b,d,f]azepine (1.1 g, 4.4 mmol, 1.1 equiv), palladium acetate (45.3 mg, 0.2 mmol, 5 mol%), tri-tert-butylphosphine tetrafluoroborate (116.1 mg, 0.4 mmol, 10.0 mol%), sodium tert-butoxide (768.8 mg, 8.0 mmol, 2.0 equiv), and toluene (30 mL) were added to a two-necked flask equipped with a magnetic stirrer. The resulting mixture was stirred at 110°C for 24 hours. After cooling to room temperature, the mixture was diluted with 20-30 mL of dichloromethane and filtered through celite. The filtrate was concentrated in vacuo and the residue was purified by silica gel column chromatography (petroleum ether / dichloromethane = 3 / 1, v / v) to provide 2.2 g of the desired product A in a 96% yield. 1 H NMR (400MHz, CDCl3): δ = 6.63 (d, J = 8.4Hz, 1H), 6.87–6.90 (m, 2H), 7.09 (t, J = 8.4Hz, 1H), 7.32 (t, J = 6.4Hz, 2H), 7.51–7.38(m,12H),7.56(t,J=7.6Hz,1H),7.64–7.62(m,5H),7.69(d,J=8.0Hz,2H),8.18(d,J=8.0Hz,2H)ppm. 13 C NMR (100MHz, CDCl3): δ=110.0,110.7,111.6,116.8,120.1,120.4,123.5,125.4,125.6,126.1,126.2,127.6,127. 9,128.6,129.2,129.3,129.5,130.0,131.2,137.7,138.0,139.1,140.8,141.0,143.9,145.9,148.0ppm.HRMS (ESI + ):Calculated value C 42 H 29 N2[M+H] + 561.2325, found 561.2327. The H NMR spectrum of A is shown in the attached Figure 1, the NMR spectrum of A is shown in the attached Figure 2 .

[0029] Example 2: Preparation of Compound B Under a nitrogen atmosphere, a two-necked flask equipped with a magnetic stirrer was charged with 3,3'-dibromobiphenyl (1.9 g, 6.0 mmol), triphenyl[b,d,f]azepine TBA (3.5 g, 14.4 mmol, 2.4 equiv), palladium acetate (67.9 mg, 0.3 mmol, 5 mol%), tri-tert-butylphosphine tetrafluoroborate (348.3 mg, 1.2 mmol, 20.0 mol%), sodium tert-butoxide (3.4 g, 8.0 mmol, 4.0 equiv), and toluene (50 mL). The resulting mixture was stirred at 110°C for 24 hours. After cooling to room temperature, the reaction mixture was filtered through celite, washed with a large amount of dichloromethane, and the filtrate was concentrated in vacuo. The filtrate was then recrystallized to yield 2.0 g of the desired product B in a 52% yield. 1 H NMR (400 MHz, CDCl3): δ = 6.46 (dd, J1 = 9.2 Hz, J2 = 10.4 Hz, 2H), 6.61 (d, J = 7.2 Hz, 1H), 6.92 (t, J = 8.4 Hz, 1H), 7.33–7.37 (m, 2H), 7.39–7.47 (m, 4H), 7.53–7.50 (m, 4H), 7.65 (d, J = 7.2 Hz, 2H) ppm. Due to the poor solubility of compound B, no carbon spectrum could be obtained. HRMS (ESI + ):Calculated value C 48 H 32 N2[M+H] + 637.2638, found 637.2641. The H NMR spectrum of B is shown in the attached Figure 3 .

[0030] The present invention uses compounds A and B as host materials to fabricate organic electroluminescent devices, with commercially available phosphorescent material FIrpic and BCz-BN synthesized according to literature reports as luminescent materials. It should be understood that the device implementation process and results are intended only to better illustrate the present invention and are not intended to limit it.

[0031] Prepare the organic phosphorescent electroluminescent device as follows: 1. Cleaning ITO (indium tin oxide) glass: wash with alkali and deionized water in sequence until the water on the surface neither gathers into droplets nor flows down in streams. After drying, treat in a plasma cleaner for 10 minutes; 2. Vacuum-deposit a hole transport layer TAPC (30 nm) and an electron blocking layer TCTA (10 nm) on the anode ITO glass at a deposition rate of 0.1 nm / s. 3. Vacuum evaporate the co-evaporated light layer on the electron blocking layer at a rate of 0.1 nm / s; 4. Vacuum evaporate the electron transport layer TmPyPb (35 nm) on the light-emitting layer at a rate of 0.1 nm / s; 5. Vacuum evaporate LiF (0.8 nm) on the electron transport layer at a rate of 0.08 nm / s; 6. Vacuum evaporate cathode Al (100 nm) on the electron injection layer at a rate of 0.1 nm / s.

[0032] Example 1: ITO / TAPC (30 nm) / TCTA (10 nm) / 10 wt% FIrpic: A or B (30 nm) / TmPyPb (35 nm) / LiF (0.8 nm) / Al (100 nm).

[0033] Example 2: ITO / TAPC (30 nm) / TCTA (10 nm) / 0.5 wt% BCz-BN: 10 wt% FIrpic: A or B (30 nm) / TmPyPb (35 nm) / LiF (0.8 nm) / Al (100 nm).

[0034] The test results of the device are shown in Table 1 and Table 2 Table 1 Table 2

[0035] Data annotation: [a] Brightness is 1000cd m -2 [b] CIE coordinates of the device’s luminescence spectrum; [c] luminance of 1 cd m -2 The driving voltage is [d] when the brightness is 1000 cd m -2 [e] Maximum external quantum efficiency; [f] Maximum power efficiency; [g] Brightness is 1000 cd m -2 External quantum efficiency when [f] is 10000 cd m -2 The external quantum efficiency when .

[0036] The above descriptions are only some implementation cases of the present invention and are not intended to limit the present invention. Any modifications, replacements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

[0037] Although the present invention has been disclosed by way of examples and preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. On the contrary, those skilled in the art will appreciate that various modifications and similar arrangements are intended to be encompassed. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

Claims

1. A novel organic electroluminescent host material based on a seven-membered ring triphenyl[b,d,f]azepine unit and its application in an organic electroluminescent display device, characterized in that It has the structure shown in formula (1): In formula (1), Ar represents any one of a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms, a substituted or unsubstituted arylamine group having 6 to 30 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted arylalkylsilyl group having 6 to 30 carbon atoms, a nitro group, a cyano group, and a halogen group.

2. A novel electroluminescent host material based on a seven-membered ring triphenyl[b,d,f]azepine unit according to claim 1, characterized in that The specific structure of formula (1) includes but is not limited to: Any one of .

3. An organic electroluminescent device comprising the compound according to any one of claims 1 and 2, characterized in that The compound is used as the main material of the light-emitting layer to prepare a blue light OLEDs device.

4. A method for preparing the compound according to any one of claims 1 and 2, characterized in that The reaction equation occurring during the preparation process is: In the reaction equation, X represents a chlorine atom, a bromine atom or an iodine atom; The specific reaction steps of the reaction equation are as follows: in a nitrogen or argon atmosphere, a seven-membered ring triphenyl[b,d,f]azepine unit 1 and a halide 2, palladium acetate, tri-tert-butylphosphine tetrafluoroborate, and sodium tert-butoxide are added to a toluene solution, the mixed solution is reacted at 110° C. for 24 hours, and then cooled, filtered through diatomaceous earth, dried under reduced pressure, and subjected to silica gel column chromatography to obtain the target product; The molar ratio of the seven-membered ring triphenyl[b,d,f]azepine unit 1 and the halide 2: palladium acetate: tri-tert-butylphosphine tetrafluoroborate: sodium tert-butoxide is (2.2-2.5):1:(0.05-0.1):(0.2-0.5):(3-8).

5. As described in claims 1 and 2, a novel host material molecule based on a seven-membered ring triphenyl[b,d,f]azepine unit is selected and applied to the production of OLED devices, characterized in that: The organic electroluminescent device using phosphorescent materials as the light-emitting materials comprises, from bottom to top, an ITO conductive glass substrate (anode), a hole transport layer (TAPC), an electron blocking layer (TCTA), a light-emitting layer (FIrpic as a blue phosphorescent light-emitting material or FIrpic as a sensitizer, BCz-BN as a blue light-emitting material, doped with the organic electroluminescent host material involved in the present invention), an electron transport layer (TmPyPb), an electron injection layer (LiF), and a cathode layer (Al).

6. As described in claim 5, the organic electroluminescent device prepared with the novel host material molecule based on the seven-membered ring triphenyl[b,d,f]azepine unit has the following performance characteristics: high triplet energy level, fast hole transport, good morphological stability, good device performance, and high blue light device efficiency and low efficiency roll-off.

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