A fluorescent host material, a preparation method and an organic electroluminescent device comprising the same

Abstract

The application belongs to the technical field of organic electroluminescent materials, and provides a fluorescent host material, a preparation method and an organic electroluminescent device containing the same, a structural general formula of the fluorescent host material is shown in the specification. The synthesized fluorescent host material can solve the problems of poor solubility and non-film-forming property of the existing host material, and can improve the problems of unsatisfactory performance of the material in device life and luminous efficiency.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescent materials, specifically relating to a fluorescent host material, a preparation method thereof, and an organic electroluminescent device containing the same. Background Technology

[0002] In recent years, organic light-emitting diodes (OLEDs) have demonstrated unique advantages in flat panel displays and solid-state lighting, thus attracting considerable attention. Compared to red and green OLEDs, the performance of blue OLEDs is still far from meeting the requirements for practical applications, necessitating in-depth research into blue light materials and devices. Due to the wide bandgap of blue materials, materials with good electroluminescence properties generally need to meet the following criteria: efficient carrier injection and transport characteristics, effective recombination of electron-hole pairs, good thermal stability, and ease of forming amorphous thin films. Therefore, designing and synthesizing blue light materials with good electroluminescence properties is a very challenging task.

[0003] As an emerging flat panel display device, OLED boasts numerous advantages, including all-solid-state operation, high brightness, wide viewing angle, self-emissive nature, fast response speed, compatibility with flexible substrates, low power consumption, and a wide operating temperature range. In terms of processing, organic electroluminescent devices can be fabricated using vacuum evaporation and spin coating methods to create luminescent thin films. Given these unparalleled advantages and promising technological prospects compared to other display technologies, OLED is expected to permeate all aspects of people's lives in the near future, and may even play a significant role in the national economy and defense industry. The history of OLED development is inextricably linked to the development of OLED materials and devices.

[0004] Organic light-emitting devices convert electrical energy into light by applying electricity to organic light-emitting materials, and typically include an anode, a cathode, and an organic layer formed between or outside the two electrodes. This organic layer may include hole injection layers, hole transport layers, hole auxiliary layers, light-emitting auxiliary layers, electron blocking layers, light-emitting layers, electron buffer layers, hole blocking layers, electron transport layers, electron injection layers, and capping layers, etc.

[0005] Among them, the fluorescent material tri-(8-hydroxyquinoline)aluminum (Alq3) is a representative. With continuous research, some organic fluorescent small molecules can also be used as the main luminescent materials. These are mainly aromatic hydrocarbons and heterocyclic compounds, including diazoles, triazoles, stilbenesides, benzimidazoles, anthracenes, biphenyls, etc. Most of these compounds were developed from the perspective of blue luminescent materials.

[0006] Currently, the biggest problem with blue light devices is their low efficiency and short lifespan, which fail to meet the requirements of commercial applications. The primary reason for this is the lack of highly efficient and stable blue light-emitting materials. While red and green light materials have met commercial application requirements, blue light materials have not. Therefore, developing novel, high-efficiency blue fluorescent materials is of great significance in improving the driving voltage, efficiency, and lifespan of these devices. Summary of the Invention

[0007] In view of this, the present invention provides a fluorescent host material, a preparation method thereof, and an organic electroluminescent device comprising the same. The fluorescent host material synthesized by the present invention can solve the problems of poor solubility and lack of film-forming properties of existing host materials, and can improve the unsatisfactory performance of the material in terms of device lifetime and luminous efficiency.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] The first technical objective of this invention is to provide a fluorescent host material, wherein the fluorescent host material is selected from compounds represented by the following general formula I:

[0010]

[0011] In the formula:

[0012] R1 is selected from phenyl, biphenyl, terphenyl, and naphthyl;

[0013] R2 is selected from phenyl, biphenyl, terphenyl, and naphthyl;

[0014] R3-R4 may be the same or different from each other, and each is independently selected from hydrogen and deuterium;

[0015] n and m are integers selected from 0 to 4.

[0016] Furthermore, all of the above groups can be replaced by deuterium.

[0017] Furthermore, the fluorescent host material is selected from any one of the following structures:

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026] The definitions of the functional groups corresponding to compounds of general formula I in the above-described compounds and the compounds in the specific embodiments are also covered within the preferred definition range of each functional group. Any combination or combination of these specific functional group definitions and the functional group definitions in general formula I are also covered within the technical solutions described in this specification.

[0027] The second technical objective of this invention is to provide a method for preparing the above-mentioned fluorescent host material, the method specifically comprising the following steps:

[0028] Raw material A and raw material B were added to a mixed solution of toluene, ethanol, and water. The mixture was then purged three times. Under nitrogen protection, potassium carbonate and tetraphenylphosphine palladium were added, stirred until homogeneous, and heated to 80-90°C. The mixture was then refluxed for 6-8 hours. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain intermediate 1.

[0029] Under nitrogen protection, raw material C and intermediate 1 were dissolved in 1,4-dioxane solution, potassium acetate and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride were added, the mixture was stirred until homogeneous, and the temperature was raised to 110-120℃ and refluxed for 10-12 h. After the reaction was completed, the temperature was lowered slightly, and the mixture was filtered with diatomaceous earth to remove salt and catalyst. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining substances were purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:2) to obtain intermediate 2.

[0030] Raw material D and intermediate 2 were added to a mixed solution of toluene, ethanol, and water. The mixture was then purged three times. Under nitrogen protection, potassium carbonate and tetraphenylphosphine palladium were added, stirred until homogeneous, and heated to 80-90°C. The mixture was then refluxed for 6-8 hours. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain the compound shown in formula I.

[0031] The specific synthesis route is as follows:

[0032]

[0033] In the formula, Hal1-Hal3 are selected from fluorine, chlorine, bromine, and iodine, respectively; R1-R4, m, and n are as specified above.

[0034] Note: In the general formula, the raw material D and the target compound need to be deuterated according to the specific embodiment.

[0035] A third technical objective of the present invention is to provide an organic electroluminescent device, the organic electroluminescent device comprising a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode; and the organic layer comprising a light-emitting layer; the light-emitting layer comprising the fluorescent host material as described above.

[0036] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention introduces anthracene groups into benzonaphthofuran, increasing the rigidity and stability of the compound, resulting in materials with good thermal stability. The tunable HOMO and LUMO energy levels, along with suitable singlet and triplet energy levels, allow light-emitting devices fabricated using this type of material to exhibit advantages such as low driving voltage, high efficiency, and long lifetime.

[0038] The deuteration in the compounds of this invention improves the luminous efficiency of organic electroluminescent devices and extends their lifespan. Furthermore, the reaction process for preparing the deuterated compounds of this invention is simple, the reaction conditions are mild, no complicated purification process is required, and the post-processing is simple, making it suitable for the preparation of organic electroluminescent devices. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1 This is the 1H NMR spectrum of compound 57 of the present invention. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Additionally, it should be noted that the values ​​given in the following embodiments are as accurate as possible. However, those skilled in the art will understand that due to unavoidable measurement errors and experimental issues, each number should be understood as an approximation rather than an absolutely accurate value.

[0043] Example 1

[0044]

[0045] Raw material A (1.0 eq) (CAS: 2625815-01-0) and raw material B (1.1 eq) (CAS: 98-80-6) were added to a mixed solution of toluene, ethanol, and water. After purging three times, potassium carbonate (2.0 eq) and tetrakis(triphenylphosphine)palladium (Pd(pph3)4) (0.01 eq) were added under nitrogen protection. The mixture was stirred until homogeneous, heated to 90°C, and refluxed for 8 hours. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate. The solvent was removed using a rotary evaporator to obtain intermediate 1 (yield: 82.4%).

[0046] Under nitrogen protection, starting material C (1.1 eq) (CAS: 108-78-1) and intermediate 1 (1.0 eq) were dissolved in 1,4-dioxane solution, and potassium acetate (2.0 eq) and [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride (0.2 eq) were added. The mixture was stirred until homogeneous, heated to 120 °C, and refluxed for 12 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate. The solvent was removed using a rotary evaporator. The remaining substances were purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:2) to obtain intermediate 2 (yield: 64.8%).

[0047] Raw material D (1.0 eq) (CAS: 1609386-55-1) and intermediate 2 (1.0 eq) were added to a mixed solution of toluene, ethanol and water. After purging three times, potassium carbonate (2.0 eq) and tetrakis(triphenylphosphine)palladium (Pd(pph3)4) (0.01 eq) were added under nitrogen protection. The mixture was stirred until homogeneous, heated to 90 °C, and refluxed for 8 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate. The solvent was removed using a rotary evaporator to obtain compound 1 (yield: 52.3%).

[0048] MS(ESI, m / Z): [M+H]+: 546.49

[0049] Elemental analysis:

[0050] The calculated values ​​are: C, 92.28; H, 4.79; O, 2.93.

[0051] The test values ​​were: C, 91.85; H, 5.05; O, 3.20.

[0052] Example 2

[0053]

[0054] Raw material A (1.0 eq) (CAS: 2625815-01-0) and raw material B (1.1 eq) (CAS: 98-80-6) were added to a mixed solution of toluene, ethanol, and water. The mixture was then purged three times. Under nitrogen protection, potassium carbonate (2.0 eq) and tetrakis(triphenylphosphine)palladium (Pd(pph3)4) (0.01 eq) were added. The mixture was stirred until homogeneous, heated to 90°C, and refluxed for 8 hours. After the reaction was complete, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalyst. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried using anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain intermediate 1. (Yield: 79.5%)

[0055] Under nitrogen protection, starting material C (1.1 eq) (CAS: 108-78-1) and intermediate 1 (1.0 eq) were dissolved in 1,4-dioxane solution, and potassium acetate (2.0 eq) and [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride (0.2 eq) were added. The mixture was stirred until homogeneous, heated to 120 °C, and refluxed for 12 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate. The solvent was removed using a rotary evaporator. The remaining substances were purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:2) to obtain intermediate 2 (yield: 69.8%).

[0056] Starting material D (1.0 eq) (CAS: 1609386-55-1) and AlCl3 (0.5 eq) were added to C6D6 (300 mL) and stirred for 2 hours. After the reaction was complete, D2O (60 mL) was added, and the mixture was stirred for 30 minutes. Then, trimethylamine (6 mL) was added dropwise. The reaction mixture was transferred to a separatory funnel and extracted with water and toluene. The extract was dried over anhydrous magnesium sulfate (MgSO4) and recrystallized from ethyl acetate to give intermediate 3 (yield: 61.8%).

[0057] Intermediate 3 (1.0 eq) and intermediate 2 (1.1 eq) were added to a mixed solution of toluene, ethanol and water, followed by three purgings. Under nitrogen protection, potassium carbonate (2.0 eq) and tetrakis(triphenylphosphine)palladium (Pd(pph3)4) (0.01 eq) were added, stirred until homogeneous, heated to 90 °C, and refluxed for 8 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain compound 57 (yield: 55.6%).

[0058] MS(ESI, m / Z): [M+H]+: 559.58

[0059] Elemental analysis:

[0060] The calculated values ​​are: C, 90.12; H, 7.02; O, 2.86.

[0061] The test values ​​are: C, 89.87; H, 7.25; O, 3.14.

[0062] Example 3

[0063]

[0064] Raw material A (1.0 eq) (CAS: 2355228-11-4) and raw material B (1.1 eq) (CAS: 98-80-6) were added to a mixed solution of toluene, ethanol, and water. The mixture was then purged three times. Under nitrogen protection, potassium carbonate (2.0 eq) and tetraphenylphosphine palladium (Pd(pph3)4) (0.01 eq) were added. The mixture was stirred until homogeneous, heated to 90°C, and refluxed for 8 hours. After the reaction was complete, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalyst. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried using anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain intermediate 1. (Yield: 82.5%)

[0065] Under nitrogen protection, starting material C (1.1 eq) (CAS: 108-78-1) and intermediate 1 (1.0 eq) were dissolved in 1,4-dioxane solution, and potassium acetate (2.0 eq) and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (0.2 eq) were added. The mixture was stirred until homogeneous, heated to 120 °C, and refluxed for 12 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate. The solvent was removed using a rotary evaporator. The remaining substances were purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:2) to obtain intermediate 2 (yield: 75.6%).

[0066] Raw material D (1.0 eq) (CAS: 1609386-55-1) and intermediate 2 (1.1 eq) were added to a mixed solution of toluene, ethanol and water. After purging three times, potassium carbonate (2.0 eq) and tetrakis(triphenylphosphine)palladium (Pd(pph3)4) (0.01 eq) were added under nitrogen protection. The mixture was stirred until homogeneous, heated to 90°C, and refluxed for 8 hours. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate. The solvent was removed using a rotary evaporator to obtain intermediate 3 (yield: 61.7%).

[0067] Intermediate 3 and AlCl3 (0.5 eq) were added to C6D6 (300 mL) and stirred for 2 hours. After the reaction was complete, D2O (60 mL) was added, and the mixture was stirred for 30 minutes. Then, trimethylamine (6 mL) was added dropwise. The reaction mixture was transferred to a separatory funnel and extracted with water and toluene. The extract was dried over anhydrous magnesium sulfate (MgSO4) and recrystallized from ethyl acetate to give compound 74 (yield: 54.5%).

[0068] MS(ESI, m / Z): [M+H]+: 572.59

[0069] Elemental analysis:

[0070] The calculated values ​​are: C, 88.07; H, 9.14; O, 2.79.

[0071] The test values ​​are: C, 87.75; H, 9.46; O, 3.13.

[0072] The synthesis methods for other compounds are the same as those in the above examples, and will not be described in detail here. The mass spectra, molecular formulas, and yields of other synthesis examples are shown in Table 1 below:

[0073] Table 1

[0074]

[0075]

[0076] Device Example 1

[0077] Specifically, the fabrication of organic electroluminescent devices includes the following steps:

[0078] a. ITO Anode: An ITO (Indium Tin Oxide)-Ag-ITO (Indium Tin Oxide) glass substrate with a coating thickness of 150nm is cleaned twice in distilled water, ultrasonically washed for 30 minutes, then repeatedly cleaned twice with distilled water, ultrasonically washed for 10 minutes. After cleaning, it is transferred to a spin dryer for drying, and finally baked in a vacuum oven at 220℃ for 2 hours. After baking, it is cooled before use. Using this substrate as the anode, a vapor deposition process is performed to deposit other functional layers sequentially on it.

[0079] b. HIL (Hole Injection Layer): The evaporation rate of the hole injection layer material HT and P-dopant was vacuum evaporated, and the chemical formulas are shown below; wherein, the evaporation rate ratio of HT and P-dopant is 97:3, and the thickness is 10nm.

[0080] c. HTL (Hole Transport Layer): At a certain evaporation rate, a 120nm HT layer was vacuum-deposited on top of the hole injection layer as a hole transport layer.

[0081] d. Light-emitting auxiliary layer: with At a certain evaporation rate, a 5nm EB layer was vacuum-deposited on the hole transport layer as a light-emitting auxiliary layer.

[0082] e. EML (Emitting Layer): The evaporation rate was such that compound 1 with a thickness of 25 nm was vacuum-deposited on the light-emitting auxiliary layer as the host material and dopant material as the light-emitting layer. The chemical formula of the dopant is shown below; the evaporation rate ratio of the host to the dopant is 98:2.

[0083] f. HBL (Hole Blocking Layer): The evaporation rate is such that a hole blocking layer with a thickness of 5.0 nm is vacuum-deposited on the light-emitting layer. The structural formula of HB is shown below.

[0084] g. ETL (Electron Transport Layer): The evaporation rate was such that ET and Liq with a thickness of 30 nm were vacuum-deposited on the hole blocking layer as electron transport layers. The chemical formula of ET is shown below; the evaporation rate ratio of ET to Liq is 50:50.

[0085] h, EIL (Electron Injection Layer): with At a certain evaporation rate, a 1.0 nm Yb film was deposited on the electron transport layer to form an electron injection layer.

[0086] i. Cathode: with The evaporation rate ratio was 1:9, and magnesium and silver were deposited at a ratio of 1:9 on the electron injection layer to obtain the cathode.

[0087] j. Optical extraction layer: with The evaporation rate was used to vacuum evaporate a 65 nm thick CPL layer on the cathode as a light extraction layer.

[0088] k. Encapsulate the vapor-deposited substrate: First, use a coating equipment to coat the cleaned cover plate with UV adhesive. Then, move the coated cover plate to the lamination section, place the vapor-deposited substrate on the top of the cover plate, and finally, laminate the substrate and cover plate together under the action of the lamination equipment, while simultaneously curing the UV adhesive by light.

[0089] Device Examples 2-30

[0090] The preparation methods of Device Examples 2-30 differ from those of Device Example 1 only in that the main material compound 1 in Device Example 1 is replaced with 57, 74, 3, 5, 7, 12, 17, 24, 29, 30, 34, 41, 46, 52, 58, 63, 67, 70, 75, 84, 89, 91, 96, 100, 103, 107, 108, 113, and 115, respectively, to obtain Device Examples 2-30.

[0091] The structural formulas involved above are as follows:

[0092]

[0093] Device Comparison:

[0094] The comparative examples provide an organic electroluminescent device. The only difference between this organic electroluminescent device and device example 1 is that the organic electroluminescent device is prepared by replacing the main material (compound 1) in device example 1 with existing comparative compounds a, b, c, and d for vapor deposition, thus preparing devices 1-4. The chemical structural formulas of comparative compounds a, b, c, and d are as follows:

[0095]

[0096] The driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained in Examples 1-30 and Comparative Examples 1-4 were characterized at a brightness of 1000 nits. The test results are shown in Table 2 below.

[0097] Table 2

[0098]

[0099] Note: In blue top-emitting devices, current efficiency is greatly affected by chromaticity. Therefore, the influence of chromaticity on efficiency is taken into account, and the ratio of luminous efficiency to CIEy is defined as the BI value, i.e., BI = (cd / A) / CIEy.

[0100] As shown in Table 2, the organic electroluminescent devices prepared using the compound of general formula I of this invention as the host material exhibit significantly improved lifetime and luminous efficiency compared to the structurally similar comparative compounds 1-4, and also improved driving voltage. In particular, the deuterated host compound shows a significant improvement in both lifetime and efficiency.

[0101] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fluorescent host material, characterized in that, The fluorescent host material is selected from compounds represented by the following general formula I: In the formula: R1 is selected from phenyl, biphenyl, terphenyl, and naphthyl; R2 is selected from phenyl, biphenyl, terphenyl, and naphthyl; R3-R4 may be the same or different from each other, and each is independently selected from hydrogen and deuterium; n and m are integers selected from 0 to 4.

2. The fluorescent host material according to claim 1, characterized in that, All of the groups can be replaced by deuterium.

3. The fluorescent host material according to claim 1, characterized in that, The fluorescent host material is selected from any one of the following structures:

4. A method for preparing the fluorescent host material as described in claim 1, characterized in that, The method specifically includes the following steps: Raw material A and raw material B were added to a mixed solution of toluene, ethanol, and water. The mixture was then purged three times. Under nitrogen protection, potassium carbonate and tetraphenylphosphine palladium were added, stirred until homogeneous, and heated to 80-90°C. The mixture was then refluxed for 6-8 hours. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain intermediate 1. Under nitrogen protection, raw material C and intermediate 1 were dissolved in a 1,4-dioxane solution, potassium acetate and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride were added, the mixture was stirred until homogeneous, and the temperature was raised to 110-120℃ and refluxed for 10-12 h. After the reaction was completed, the temperature was lowered slightly, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining substances were purified by column chromatography using a mixed solution of dichloromethane and petroleum ether to obtain intermediate 2. Raw material D and intermediate 2 were added to a mixed solution of toluene, ethanol, and water. The mixture was then purged three times. Under nitrogen protection, potassium carbonate and tetraphenylphosphine palladium were added, stirred until homogeneous, and heated to 80-90°C. The mixture was then refluxed for 6-8 hours. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain the compound shown in formula I. The specific synthesis route is as follows: In the formula, Hal1-Hal3 are selected from fluorine, chlorine, bromine, and iodine, respectively; R1-R4, m, and n are as defined in claim 1.

5. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode; and the organic layer includes a light-emitting layer; the light-emitting layer includes the fluorescent host material as described in claim 1.

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