A diazafluorene compound and material for organic electroluminescent device and organic electroluminescent device

Abstract

The present application discloses a diazafluorene compound, which is based on diazafluorene and introduces an aryl or heteroaryl group into the basic structure, and has the following general formula I: wherein X1 to X8 are independently represented by N atoms or C atoms, and the number of nitrogen atoms is 2; the aryl or heteroaryl group is a substituted or unsubstituted aryl or heteroaryl group; the refractive index of the compound is greater than or equal to 1.85. The present application also discloses a material for an organic electroluminescent device and an organic electroluminescent device. The diazafluorene compound described in the present application has a high refractive index, thermal stability and film-forming properties, and can be used as a light extraction layer material, suitable for making OLED devices by evaporation.

Description

Technical Field

[0001] The invention relates to an organic luminescent material, in particular to a diazafluorene compound and an organic electroluminescent device material and an organic electroluminescent device. Background Art

[0002] Organic light-emitting diodes (OLEDs) have many advantages such as full solid-state, active luminescence, low power consumption, high contrast, ultra-thin, wide viewing angle, fast response speed, wide temperature adaptability range, easy to realize flexible display and 3D display, etc., and have attracted much attention in the scientific and industrial circles. The light-emitting principle of OLED is that under the drive of forward voltage, electrons and holes are injected into the device from the cathode and anode respectively, and the carriers move toward the other electrode in the organic layer respectively, meet and combine in the light-emitting layer to form excitons, and the excitons radiate and transition back to the ground state to emit light. Due to the huge potential application value of OLED, how to prepare high-efficiency devices is attracting more and more attention. However, due to the huge gap between the external quantum efficiency and internal quantum efficiency of OLED, the development of OLED is greatly restricted. Therefore, how to improve the light extraction efficiency of OLED has become a research hotspot.

[0003] In order to solve the problem of low light extraction efficiency of OLED, adding a light extraction layer (CPL) on the surface of the device is currently the most effective way, and the preparation process is relatively simple and suitable for industrialization. The problems with existing CPL materials include: (1) the refractive index is not high enough, and the light extraction effect is not good enough; (2) the difference in refractive index measured in the wavelength regions of blue light, green light and red light is large. Therefore, all light in the light-emitting device emitting blue light, green light and red light cannot obtain high light extraction efficiency at the same time. (3) The decomposition temperature of the material is low, which leads to serious decomposition during long-term evaporation.

[0004] In order to improve the light extraction efficiency of organic light-emitting devices and increase the life of the devices, it is necessary to introduce a cover layer material with a high refractive index, excellent thin film stability and good durability. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present application is to provide a diazafluorene compound to solve the problems of low refractive index and poor film-forming stability of existing organic light-emitting materials.

[0006] To solve the above problems, the technical solutions adopted in this application are as follows:

[0007] A diazafluorene compound, with diazafluorene as the basic structure, an aryl group or a heteroaryl group is introduced into the basic structure, and has the following general formula I:

[0008]

[0009] Wherein, X1 to X8 are independently represented by N atoms or C atoms, and the number of nitrogen atoms is 2; the aryl or heteroaryl group is a substituted or unsubstituted aryl or heteroaryl group; and the refractive index of the compound is greater than or equal to 1.85.

[0010] As a further preferred embodiment, R1 and R2 in the general formula I described in the present application have groups with the same or different structures, representing one of an H atom, a C1-C30 straight-chain or branched alkyl group, a C1-C30 straight-chain or branched alkoxy group, a C1-C30 straight-chain or branched alkylthio group, a C1-C30 straight-chain or branched alkylamino group, a substituted or unsubstituted C6-C60 aryl group, or a substituted or unsubstituted C6-C60 heteroaryl group; A is an H atom, A substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C6-C60 heteroaryl group; L1 and L2 have the same or different structures and represent a single bond, a substituted or unsubstituted C6-C60 arylene group, or a substituted or unsubstituted C6-C60 heteroarylene group; Ar1 ​​and Ar2 have the same or different structures and represent a substituted or unsubstituted C6-C60 aryl group, or a substituted or unsubstituted C6-C60 heteroaryl group.

[0011] As a further preferred solution, the basic structure described in the present application has the following general formula II, and the general formula II is one of the following structures:

[0012]

[0013] As a further preferred embodiment, L1 and L2 described in the present application are independently selected from a single bond or one of the following groups:

[0014]

[0015] As a further preferred embodiment, Ar1 and Ar2 described in the present application are independently selected from one of the following groups:

[0016]

[0017]

[0018] As a further preferred embodiment, the general formula I described in the present application is one of the compounds represented by the following structural formulas 1 to 216:

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025] Furthermore, the present application also provides an application of a diazafluorene compound in an organic electroluminescent device, in which the diazafluorene compound is used as a light extraction layer of the organic electroluminescent device.

[0026] Furthermore, the present application also provides a material for an organic electroluminescent device, wherein the material is the diazafluorene compound described in the present application, and the compound is used as a light extraction layer of the organic electroluminescent device.

[0027] Furthermore, the present application also provides an organic electroluminescent device, which includes, from bottom to top, a substrate, an anode, a first hole injection layer, a second hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, a cathode, and a light extraction layer; the light extraction layer is a film layer formed on the cathode by the diazafluorene compound described in the present application.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The diazafluorene compound described in the present application has a high refractive index, thermal stability and film-forming performance, and can be used as a light extraction layer material and is suitable for manufacturing OLED devices by evaporation.

[0030] 2. The diazafluorene compounds described in the present application use diazafluorene as the basic structure. Diazafluorene is a rigid group that improves the stability and glass transition temperature of the material. In the present application, substituted or unsubstituted aromatic or heteroaromatic groups are introduced into diazafluorene as the basic structure to ensure that the material does not crystallize in the thin film state and has a low evaporation temperature, thereby meeting the needs of mass production. At the same time, it has a high refractive index and is applied to organic electroluminescent devices to effectively improve the light extraction efficiency of the device.

[0031] The present invention is further described in detail below in conjunction with specific implementation modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the ultraviolet-visible (UV-vis) absorption spectrum of the diazafluorene compound of Example 1.

[0033] Figure 2 This is the thermogravimetric (Tg) spectrum of the diazafluorene compound of Example 1.

[0034] Figure 3 Schematic diagram of the structure of the organic electroluminescent device described in the application implementation. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] The terms "comprises", "includes" and other equivalent descriptions in the specification and claims of this application are intended to cover non-exclusive inclusions, including both the contents clearly described in the specification and claims and the steps or units that are not described in the specification and claims but are inherent in the product, method or structure.

[0037] The diazafluorene compound described in the examples of the present application is based on diazafluorene as the basic structure, and an aryl or heteroaryl group is introduced into the basic structure, and has the following general formula I:

[0038]

[0039] Wherein, X1 to X8 are independently represented by N atoms or C atoms, and the number of nitrogen atoms is 2; the aryl or heteroaryl group is a substituted or unsubstituted aryl or heteroaryl group; the refractive index of the compound is greater than or equal to 1.85. Preferably, in some embodiments, the refractive index of the diazafluorene compound is 1.85-2.0. In the present application, diazafluorene has good planarity, a large conjugated area, and a more ordered molecular stacking; at the same time, it can form intermolecular hydrogen bonds, enhance intermolecular interactions, make the film denser, and have a higher refractive index.

[0040] Further, in some embodiments, R1 and R2 in the general formula I described in the present application have groups with the same or different structures, representing one of an H atom, a C1-C30 straight-chain or branched-chain alkyl group, a C1-C30 straight-chain or branched-chain alkoxy group, a C1-C30 straight-chain or branched-chain alkylthio group, a C1-C30 straight-chain or branched-chain alkylamino group, a substituted or unsubstituted C6-C60 aryl group, and a substituted or unsubstituted C6-C60 heteroaryl group.

[0041] Furthermore, in some embodiments, A in the general formula I described in the present application is one of an H atom, a substituted or unsubstituted C6-C60 aryl group, and a substituted or unsubstituted C6-C60 heteroaryl group.

[0042] Furthermore, in some embodiments, in the general formula I described in the present application, L1 and L2 have groups with the same or different structures, representing one of a single bond, a substituted or unsubstituted C6-C60 arylene group, and a substituted or unsubstituted C6-C60 heteroarylene group.

[0043] Furthermore, in some embodiments, in the general formula I described in the present application, Ar1 and Ar2 have the same or different structures, representing any one of a substituted or unsubstituted C6-C60 aryl group, and a substituted or unsubstituted C6-C60 heteroaryl group.

[0044] The following are specific embodiments of the present invention. In the following embodiments, unless otherwise specified, the raw materials, reaction monomers, and reagents used can all be purchased.

[0045] Example 1

[0046] This embodiment provides a diazafluorene compound, the structural formula of which is as shown in Formula 1:

[0047]

[0048] The reaction formula for preparing the diazafluorene compound is as follows:

[0049]

[0050] The method for preparing the compound is as follows:

[0051] 1) Preparation of intermediate M2: Weigh raw material M1 (8 g, 100 mmol) into a 250 mL double-necked round-bottom flask, add 50 mL of dichloromethane to dissolve, add Br2 (16 g, 100 mmol) dropwise under ice bath, and stop the reaction after 12 h. Pour into water, extract with dichloromethane, separate the layers, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound M2 (13.67 g, 86 mmol) by column chromatography, yield: 86%.

[0052] 2) Preparation of intermediate M4: Weigh intermediate M2 (7.95 g, 50 mmol) and raw material M3 (9.84 g, 60 mmol) into a 500 mL three-necked round-bottom flask, add 150 mL toluene, 100 mL water, and 50 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (2.9 g, 2.5 mmol) and K2CO3 (20.7 g, 150 mmol), heat to 85°C and react for 24 hours. Sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate layers, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound M4 (8.13 g, 41 mmol) by column chromatography, yield: 82%.

[0053] 3) Preparation of intermediate M5: Weigh Mg (1.2 g, 50 mmol) and 50 mL THF and add them to a 100 mL double-necked round-bottom flask, evacuate and fill with nitrogen 3 times, add CH3Br (4.56 g, 48 mmol) in small amounts several times, and reflux for 4 h. Take a 250 mL double-necked round-bottom flask, add intermediate M4 (7.93 g, 40 mmol) and 50 mL THF, evacuate and fill with nitrogen 3 times, add CH3MgBr in small amounts several times, and reflux for 12 h. Cool to room temperature, pour into water, extract with dichloromethane, separate layers, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound M5 (5.14 g, 24 mmol) by column chromatography, yield: 60%.

[0054] 4) Preparation of intermediate M6: Intermediate M5 (4.28 g, 20 mmol) was weighed into a 500 mL double-necked round-bottom flask, 200 mL of AcOH was added to dissolve, and HCl (10 mL) was slowly added dropwise under an ice bath. After the reaction was completed, the compound M6 (2.83 g, 14.4 mmol) was filtered to obtain a yield of 72%.

[0055] 5) Preparation of intermediate A1: Weigh intermediate M6 (1.96 g, 10 mmol) into a 100 mL double-necked round-bottom flask, add 50 mL of dichloromethane to dissolve, add Br2 (3.2 g, 20 mmol) dropwise under ice bath, and stop the reaction after 12 h. Pour into water, extract with dichloromethane, separate the layers, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound A1 (3 g, 8.5 mmol) by column chromatography, yield: 85%.

[0056] 6) Preparation of compound 1: Weigh intermediate A1 (1.77 g, 5 mmol) and raw material B1 (1.79 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85°C and react for 24 hours. Sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate layers, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and pass column chromatography to obtain compound 1 (1.74 g, 4.05 mmol), yield: 81%.

[0057] Figure 1 is the UV-visible absorption spectrum of compound 1, Figure 2 This is the thermogravimetric (Tg) spectrum of compound 1. Figure 1 The absorption edge of compound 1 is about 420nm, and there is basically no absorption in the visible light region above 420nm, which is conducive to obtaining higher light extraction and external quantum efficiency of OLED devices. Figure 2 It can be found that the thermal decomposition temperature of compound 1 exceeds 380°C, which has good thermal stability and can be used for preparing thin films by evaporation process, which is conducive to obtaining high-stability OLED devices.

[0058] Example 2

[0059] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 5:

[0060]

[0061] The reaction formula for preparing the diazafluorene compound is as follows:

[0062]

[0063] The method for preparing the compound is as follows:

[0064] Weigh the intermediate A1 (1.77g, 5mmol) and the raw material B2 (1.97g, 11mmol) into a 100mL double-necked round-bottom flask, add 15mL toluene, 10mL water, and 5mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289mg, 0.25mmol) and K2CO3 (2.07g, 15mmol), heat to 85℃ and react for 24 hours. Take the sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and pass column chromatography to obtain compound 5 (1.94g, 4.2mmol), yield: 84%.

[0065] Example 3

[0066] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 9:

[0067]

[0068] The reaction formula for preparing the diazafluorene compound is as follows:

[0069]

[0070] The method for preparing the compound is as follows:

[0071] Weigh the intermediate A1 (1.77g, 5mmol) and the raw material B3 (2.62g, 11mmol) into a 100mL double-necked round-bottom flask, add 15mL toluene, 10mL water, and 5mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289mg, 0.25mmol) and K2CO3 (2.07g, 15mmol), heat to 85℃ and react for 24 hours. Take the sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and pass column chromatography to obtain compound 9 (2.18g, 3.75mmol), yield: 75%.

[0072] Example 4

[0073] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 17:

[0074]

[0075] The reaction formula for preparing the diazafluorene compound is as follows:

[0076]

[0077] The method for preparing the compound is as follows:

[0078] Weigh the intermediate A1 (1.77 g, 5 mmol) and the raw material B4 (2.63 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound 17 (2.33 g, 4 mmol) by column chromatography, yield: 80%.

[0079] Example 5

[0080] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 32:

[0081]

[0082] The reaction formula for preparing the diazafluorene compound is as follows:

[0083]

[0084] The method for preparing the compound is as follows:

[0085] Weigh the intermediate A1 (1.77 g, 5 mmol) and the raw material B5 (3.47 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound 32 (3.05 g, 4.15 mmol) by column chromatography, yield: 83%.

[0086] Example 6

[0087] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 74:

[0088]

[0089] The reaction formula for preparing the diazafluorene compound is as follows:

[0090]

[0091]

[0092] The method for preparing the compound is as follows:

[0093] 1) Preparation of intermediate N2: Weigh the raw material N1 (10.55 g, 50 mmol) into a 500 mL three-necked round-bottom flask, add 200 mL of benzene to dissolve, bubble with dry HCl gas for 5 min, and then slowly add amyl nitrite (7.03 g, 60 mmol). While passing dry HCl gas, heat the mixture to 40°C and stir for 5 h. After stirring at room temperature for 12 h, filter the reactant and rinse with MeOH and DCM to obtain compound N2 (10.08 g, 42 mmol), with a yield of 84%.

[0094] 2) Preparation of intermediate N3: Weigh intermediate N2 (6 g, 25 mmol) and sodium dithionite (13 g, 75 mmol) into a 500 mL three-necked round-bottom flask, and add 50 mL of ethanol. Vacuum and fill with nitrogen three times, add 50 mL of 14.5% ammonia solution, and stir at room temperature in the dark for 3 days. After adding 50 mL of distilled water to the reaction system, heat and reflux in air for 24 h. After the reaction is completed, cool to room temperature and add 100 mL of distilled water. After stirring, filter the mixture and rinse thoroughly with MeOH and ether to obtain compound N3 (3.21 g, 7.75 mmol), yield: 62%.

[0095] 3) Preparation of intermediate N4: Weigh the intermediate N3 (4.14 g, 10 mmol) and sodium dichromate dihydrate (29.8 g, 100 mmol) into a 500 mL three-necked round-bottom flask, add acetic acid (250 mL) and acetic anhydride (50 mL), heat to 40° C. and stir for 3 d. After the reaction is completed, add water and NaHCO3 aqueous solution, filter the resulting precipitate and purify it by column chromatography to obtain compound N4 (2.92 g, 6.6 mmol), yield: 66%.

[0096] 4) Preparation of intermediate N5: Weigh Mg (1.2 g, 50 mmol) and 50 mL THF and add them to a 100 mL double-necked round-bottom flask, evacuate and fill with nitrogen 3 times, add 2-bromobiphenyl (20.51 g, 88 mmol) in small amounts several times, and reflux for 4 h. Take a 250 mL double-necked round-bottom flask, add intermediate N4 (17.68 g, 40 mmol) and 50 mL THF, evacuate and fill with nitrogen 3 times, add the prepared Grignard reagent in small amounts several times, and reflux for 12 h. Cool to room temperature, pour into water, extract with dichloromethane, separate layers, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound N5 (18.31 g, 24.4 mmol) by column chromatography, yield: 61%.

[0097] 5) Preparation of intermediate A2: Intermediate N5 (15 g, 20 mmol) was weighed into a 500 mL double-necked round-bottom flask, 200 mL of AcOH was added to dissolve, and HCl (10 mL) was slowly added dropwise under an ice bath. After the reaction was completed, the compound A2 (10.57 g, 14.8 mmol) was filtered to obtain a yield of 74%.

[0098] 6) Preparation of compound 74: Weigh intermediate A2 (3.57 g, 5 mmol) and raw material B1 (1.79 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85°C and react for 24 hours. Sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate layers, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and pass column chromatography to obtain compound 74 (3.24 g, 4.1 mmol), yield: 82%.

[0099] Example 7

[0100] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 78:

[0101]

[0102] The reaction formula for preparing the diazafluorene compound is as follows:

[0103]

[0104] The method for preparing the compound is as follows:

[0105] Weigh the intermediate A2 (3.57 g, 5 mmol) and the raw material B2 (1.97 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and pass column chromatography to obtain compound 78 (3.5 g, 4.25 mmol), yield: 85%.

[0106] Example 8

[0107] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 82:

[0108]

[0109] The reaction formula for preparing the diazafluorene compound is as follows:

[0110]

[0111] The method for preparing the compound is as follows:

[0112] Weigh the intermediate A2 (3.57 g, 5 mmol) and the raw material B3 (2.62 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen three times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound 82 (3.67 g, 3.9 mmol) by column chromatography, yield: 78%.

[0113] Example 9

[0114] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 90:

[0115]

[0116] The reaction formula for preparing the diazafluorene compound is as follows:

[0117]

[0118] The method for preparing the compound is as follows:

[0119] Weigh the intermediate A2 (3.57 g, 5 mmol) and the raw material B4 (2.63 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and pass column chromatography to obtain compound 90 (3.5 g, 3.7 mmol), yield: 74%.

[0120] Example 10

[0121] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 104:

[0122]

[0123] The reaction formula for preparing the diazafluorene compound is as follows:

[0124]

[0125] The method for preparing the compound is as follows:

[0126] Weigh the intermediate A2 (3.57 g, 5 mmol) and the raw material B5 (3.47 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound 104 (4.16 g, 3.8 mmol) by column chromatography, yield: 76%.

[0127] Embodiment 11

[0128] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 147:

[0129]

[0130] The reaction formula for preparing the diazafluorene compound is as follows:

[0131]

[0132] The method for preparing the compound is as follows:

[0133] 1) Preparation of intermediate L2: Weigh raw material L1 (14.7 g, 50 mmol) into a 1000 mL three-necked round-bottom flask, add 500 mL of ethanol, add NaBH4 (18.92 g, 500 mmol) dropwise under ice bath, and stir the reaction solution at room temperature for 20 h. Remove the solvent under reduced pressure, add 300 mL of water, extract with ether, dry the organic layer with anhydrous sodium sulfate, filter, and spin dry to obtain compound L2 (8.7 g, 32.5 mmol), yield: 65%.

[0134] 2) Preparation of intermediate A3: Weigh intermediate L2 (5.36 g, 20 mmol), raw material L3 (5.47 g, 30 mmol) and add them to a 1000 mL three-necked round-bottom flask, add 500 mL ethanol and 50 mL acetic acid, evacuate and fill with nitrogen three times, and heat to reflux for 12 h. After removing ethanol under reduced pressure, the residue was dissolved in dichloromethane, washed with water, and the organic phase was dried over anhydrous sodium sulfate, filtered, concentrated, and subjected to column chromatography to obtain compound A3 (7.17 g, 17.4 mmol), with a yield of 87%.

[0135] 3) Preparation of compound 147: Weigh intermediate A3 (2.06 g, 5 mmol) and raw material B1 (1.79 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85°C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate layers, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound 147 (2.12 g, 4.35 mmol) by column chromatography, yield: 87%.

[0136] Example 12

[0137] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 151:

[0138]

[0139] The reaction formula for preparing the diazafluorene compound is as follows:

[0140]

[0141] The method for preparing the compound is as follows:

[0142] Weigh the intermediate A3 (2.06 g, 5 mmol) and the raw material B2 (1.97 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen three times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and pass column chromatography to obtain compound 151 (2.13 g, 4.1 mmol), yield: 82%.

[0143] Example 13

[0144] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 155:

[0145]

[0146] The reaction formula for preparing the diazafluorene compound is as follows:

[0147]

[0148] The method for preparing the compound is as follows:

[0149] Weigh the intermediate A3 (2.06 g, 5 mmol) and the raw material B3 (2.62 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen 3 times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound 155 (2.71 g, 4.25 mmol) by column chromatography, yield: 85%.

[0150] Embodiment 14

[0151] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 162:

[0152]

[0153] The reaction formula for preparing the diazafluorene compound is as follows:

[0154]

[0155] The method for preparing the compound is as follows:

[0156] Weigh the intermediate A3 (2.06 g, 5 mmol) and the raw material B4 (2.63 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen three times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and obtain compound 162 (2.59 g, 4.05 mmol) by column chromatography, yield: 81%.

[0157] Embodiment 15

[0158] This embodiment provides a diazafluorene compound, the structural formula of which is shown in Formula 177:

[0159]

[0160] The reaction formula for preparing the diazafluorene compound is as follows:

[0161]

[0162] The method for preparing the compound is as follows:

[0163] Weigh the intermediate A3 (2.06 g, 5 mmol) and the raw material B5 (3.47 g, 11 mmol) into a 100 mL double-necked round-bottom flask, add 15 mL toluene, 10 mL water, and 5 mL ethanol to dissolve, evacuate and fill with nitrogen three times, then add Pd(PPh3)4 (289 mg, 0.25 mmol) and K2CO3 (2.07 g, 15 mmol), heat to 85 ° C and react for 24 hours. Take a sample point plate, the raw material has reacted completely. Cool to room temperature, pour into water, extract with dichloromethane, separate, dry the organic layer with anhydrous sodium sulfate, filter, concentrate, and pass column chromatography to obtain compound 177 (3.33 g, 4.2 mmol), yield: 84%.

[0164]

Performance test

[0165] The compounds of Examples 1-15 were tested for thermal properties and refractive index, and the existing compounds used in light-emitting devices were used as CPL layer materials as Comparative Example 1, in which Alq3 (8-hydroxyquinoline aluminum) was used. The glass transition temperature Tg was measured by differential scanning calorimetry (DSC, DSC200F3 differential scanning calorimeter of NETZSCH, Germany), with a heating rate of 10°C / min; the refractive index was measured by ellipsometer (JA Woollam Co., USA, model: ALPHA-SE), and the test was performed in an atmospheric environment. The results are shown in Table 1.

[0166] Table 1: Comparison results of performance of Examples 1-15 and existing materials

[0167]

[0168]

[0169] From the data in the above table, it can be seen that compared with the currently used Alq3 material, the organic compound of the present invention has a high glass transition temperature and a high refractive index. At the same time, due to the presence of a diazafluorene rigid group, the thermal stability of the material is guaranteed. Therefore, the organic material based on diazafluorene in the present invention can effectively improve the light extraction efficiency of the device after being applied to the CPL layer of the OLED device.

[0170] Application Examples

[0171] In order to verify the effect of the diazafluorene compounds described in the present application on the luminous efficiency of organic electroluminescent devices when applied to organic electroluminescent devices, the diazafluorene compounds of the above Examples 1-15 were used to prepare organic electroluminescent devices, which were listed as Application Examples 1-15, and the application of Alq3 was also used as Application Comparative Example 1. Application Examples 1-15 and Application Comparative Example 1 adopted the same production process, and the specific production method is as follows:

[0172] On a glass substrate, ITO / Ag / ITO was used as an anode; HIM-1 was vacuum evaporated on the anode as a first hole injection layer with a thickness of 60 nm; HAT-CN was vacuum evaporated on the first hole injection layer as a second hole injection layer with a thickness of 5 nm; NPB was vacuum evaporated on the second hole injection layer as a hole transport layer with a thickness of 60 nm; BH and 3% BD were vacuum evaporated on the hole transport layer as a light-emitting layer with a thickness of 25 nm; E was vacuum evaporated on the light-emitting layer. TM1: Liq (1: 1) is used as the electron transport layer with a vapor deposition thickness of 30 nm; LiF is vacuum evaporated on the electron transport layer as the electron injection layer with a vapor deposition thickness of 1 nm; Mg / Ag (9: 1) is vacuum evaporated on the electron injection layer as the cathode with a vapor deposition thickness of 15 nm; the diazafluorene compounds of Examples 1-15 (as application Examples 1-15) and Alq3 of Comparative Example 1 (as application Comparative Example 1) are vacuum evaporated on the cathode as the light extraction layer with a vapor deposition thickness of 60 nm.

[0173] The structural formulas of the relevant materials involved in the preparation process are as follows:

[0174]

[0175] The luminous efficiency of the organic electroluminescent devices of Application Examples 1-15 and Application Comparative Example 1 was tested. The results are shown in Table 2.

[0176] Table 2:

[0177]

[0178] It can be seen from the results in Table 2 that after the organic compound with diazafluorene as the core described in the present application is applied to the CPL layer of the OLED light-emitting device, the light extraction effect is significantly improved compared with the application comparative example 1 using the existing material Alq3.

[0179] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A diazafluorene compound, characterized in that Taking diazafluorene as the basic structure, a heteroaryl group is introduced into the basic structure, and the compound is one of the following structures: The compound has a refractive index greater than or equal to 1.

85.

2. Use of the diazafluorene compound as claimed in claim 1 in an organic electroluminescent device, characterized in that: The diazafluorene compound is used as a light extraction layer of an organic electroluminescent device.

3. A material for an organic electroluminescent device, characterized in that: The material is the diazafluorene compound according to claim 1, and the compound is used as a light extraction layer of an organic electroluminescent device.

4. An organic electroluminescent device, comprising, from bottom to top, a substrate, an anode, a first hole injection layer, a second hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, a cathode, and a light extraction layer; characterized in that: The light extraction layer is a film layer formed by the diazafluorene compound according to claim 1 on a cathode.

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