Aza-heterocycle-based exciplex acceptor material and preparation method and application thereof

Abstract

The application provides an excimer acceptor material based on a nitrogen heterocycle, a preparation method and application thereof, and belongs to the technical field of organic photoelectric materials. Two excimer acceptor materials are synthesized by combining 2-phenyl-4,6 di(4-pyridine)-1,3,5-triazine with spirobifluorene and pyridine. The synthesis method is simple, the yield is high, and the excimer acceptor material has good electrochemical stability. The spirobifluorene is added to improve the molecular rigidity, reduce non-radiative transition and reduce efficiency roll-off. The pyridine is added to deepen the LUMO level, which is conducive to the development of red excimer OLED. The synthesized excimer acceptor material is combined with a donor material to form an excimer, which is used as a light-emitting layer of an organic electroluminescent device. The excimer can realize yellow light and orange red light emission, has a high external quantum efficiency, and the highest external quantum efficiency can reach 11.5%. The excimer has a wide application prospect and can be widely applied in the fields of flat panel display and solid state lighting.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials technology, specifically relating to nitrogen heterocyclic excitocomplex acceptor materials, their preparation methods, and applications. Background Technology

[0002] Since Tang and Van Slyke first invented the Organic Light Emitting Diode (OLED) in 1987, OLED has been a hot research topic. Compared with existing liquid crystal displays (LCDs), OLEDs can emit light themselves, eliminating the need for a backlight. They also feature fast response times, low driving voltage, high luminous efficiency, high resolution, wide viewing angles, and high contrast. OLEDs use inexpensive glass, metal, or even flexible plastics as substrates, offering advantages such as low cost, simple manufacturing processes, and the ability to be mass-produced. They have become a new generation of full-color display and lighting technology, with broad application prospects in mobile phones, computers, televisions, digital cameras, GPS devices, flexible and foldable electronic products, and lighting.

[0003] The ratio of singlet to triplet excitons generated in OLEDs is 1:3. Traditional fluorescent OLEDs can only utilize singlet excitons for photon generation, resulting in a theoretical internal quantum efficiency (IQE) of only 25%. Phosphorescent OLEDs, by introducing phosphorescent materials containing heavy metals, can utilize both singlet and triplet excitons simultaneously, theoretically achieving 100% IQE. However, the rarity and polluting nature of heavy metals significantly limit the further application of phosphorescent OLEDs. In recent years, OLEDs utilizing thermally activated delayed fluorescence (TADF) have developed rapidly. Because they can achieve 100% internal quantum efficiency without the need for heavy metals, they have been widely studied. The TADF mechanism includes intramolecular TADF achieved using TADF materials and intermolecular TADF achieved using TADF excitopolymer complexes.

[0004] The formation and band gap size of exciton complexes are determined by the energy levels of the electron donor and acceptor. Therefore, electron donor and acceptor materials with a wide energy range and diverse types are key to promoting the development of exciton complexes. Typically, electron acceptor materials contain electron-deficient groups with strong electron-withdrawing capabilities, enabling efficient electron transport under applied voltage. Currently, triazine, pyridine, and other nitrogen-containing heterocyclic electron-withdrawing groups are widely used in electron acceptor materials. These groups possess stable electrochemical properties, good electron mobility, and high triplet energy levels, thus enabling efficient electron transport and exciton confinement. With in-depth research into the formation process and working principle of exciton complexes, many new acceptor materials have been designed and synthesized for high-performance exciton complex systems. However, many problems still need to be studied in the development of acceptor materials. Different acceptor materials exhibit specific and urgently need improved electroluminescence properties in devices; therefore, designing novel nitrogen-containing heterocyclic exciton complex acceptor materials is essential. Summary of the Invention

[0005] This invention addresses the technical problems existing in the prior art by proposing excitocomplex receptor materials based on nitrogen heterocycles, their preparation methods, and applications. Two excitocomplex receptor materials were synthesized using nitrogen heterocycles as the core.

[0006] The technical solution adopted in this invention is as follows:

[0007] A nitrogen-heterocyclic excitokinetic complex receptor material is characterized by having a structure as shown in formula (1):

[0008]

[0009] Wherein, when R1 is H, R2 is spirobifluorene; when R1 is pyridine, R2 is H;

[0010] The molecular structures of spirodifluorene and pyridine are shown in formulas (2) and (3), respectively:

[0011]

[0012] Furthermore, the molecular structures of the nitrogen-based excitocycline complex acceptor materials are as follows: 13DPy-TRZ and TRZ-SBF:

[0013]

[0014] A method for preparing excitocycline-based excitocycline receptor materials, characterized in that the molecular structure of the excitocycline receptor material is 13DPy-TRZ, and the specific preparation method is as follows:

[0015] Step 1: Under nitrogen protection, 3,5-dibromobenzonitrile and lithium dimethylaminodimethylamine were added to anhydrous diethyl ether and stirred for 1–3 h. Then, 4-cyanopyridine was added and stirring was continued for 4–6 h to obtain a mixed solution A with a concentration of 0.1–0.2 mmol / mL of 3,5-dibromobenzonitrile. The solution was then stirred in air for 0.5–2 h, and the precipitate was collected and recrystallized to obtain solid A. The molar ratio of 3,5-dibromobenzonitrile to lithium dimethylaminodimethylamine and 4-cyanopyridine was 1:(1.0–2.0):(2.0–2.5).

[0016] Step 2: Solid A, 4-pyridineboronic acid, and palladium catalyst were added sequentially under nitrogen protection in a molar ratio of 1:(1.5–2.5):(0.01–0.3) to 1,4-dioxane in a volume ratio of 4:1 and a 2M potassium carbonate aqueous solution, resulting in a mixed solution B with a solid A concentration of 0.03–0.10 mmol / mL. The mixture was heated to 80–100 °C and reacted for 20–24 h until solid A was completely reacted, yielding mixture B. After cooling to room temperature, mixture B was extracted with saturated sodium chloride aqueous solution and dichloromethane. Then, dichloromethane and 1,4-dioxane were removed, and a mixed solution of methanol and dichloromethane in a volume ratio of 10:1 was used as the eluent to purify mixture B by silica gel column chromatography. After recrystallization, filtration, and high-temperature sublimation, an excitokinase complex acceptor material with the molecular structure 13DPy-TRZ was obtained.

[0017] Furthermore, in step 1, anhydrous ethanol and deionized water are used for recrystallization.

[0018] Furthermore, the palladium catalyst is tetratriphenylphosphine palladium.

[0019] Furthermore, in step 2, dichloromethane and methanol are used for recrystallization.

[0020] A method for preparing an excitocycline-based excitocycline receptor material, characterized in that the molecular structure of the excitocycline receptor material is TRZ-SBF, includes the following steps:

[0021] Step 1: Under nitrogen protection, p-bromobenzonitrile and lithium dimethylamino were added to anhydrous diethyl ether and stirred for 1–3 h. Then, 4-cyanopyridine was added and stirring continued for 4–6 h to obtain a mixed solution C with a p-bromobenzonitrile concentration of 0.1–0.2 mmol / mL. After stirring in air for 0.5–2 h, the precipitate was collected and recrystallized to obtain solid C. The molar ratio of p-bromobenzonitrile to lithium dimethylamino and 4-cyanopyridine was 1:(1.0–2.0):(2.0–2.5).

[0022] Step 2: Solid C, 9,9'-spirodifluorene-3-boronic acid, and palladium catalyst were added sequentially under nitrogen protection in a molar ratio of 1:(1.5–2.5):(0.01–0.3) to tetrahydrofuran and 2M potassium carbonate aqueous solution in a volume ratio of 3:1, resulting in a mixed solution D with a solid C concentration of 0.03–0.10 mmol / mL. The mixture was heated to 60–80 °C and reacted for 8–10 h until solid C was completely reacted, yielding mixture D. After cooling to room temperature, mixture D was extracted with saturated sodium chloride aqueous solution and dichloromethane. Then, dichloromethane and tetrahydrofuran were removed, and mixture D was purified by silica gel column chromatography using a 15:1 volume ratio of methanol and dichloromethane as the eluent. After recrystallization, filtration, and high-temperature sublimation, an excitokinin complex acceptor material with the molecular structure TRZ-SBF was obtained.

[0023] Furthermore, in step 1, anhydrous ethanol and deionized water are used for recrystallization.

[0024] Furthermore, the palladium catalyst is tetratriphenylphosphine palladium.

[0025] Furthermore, in step 2, dichloromethane and methanol are used for recrystallization.

[0026] An organic electroluminescent device based on a nitrogen heterocyclic excitogenes complex acceptor material is characterized by comprising, from bottom to top, a substrate, an anode electrode, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode electrode; wherein the light-emitting layer is a thin film composed of a donor material and a nitrogen heterocyclic excitogenes complex acceptor material, and the proportion of the excitogenes complex acceptor material in the light-emitting layer is 5-30 wt%.

[0027] Furthermore, the donor material is a molecule containing donor groups such as acridine and phenoxazine.

[0028] Furthermore, the thickness of the light-emitting layer is 30–50 nm.

[0029] Furthermore, the anode electrode is ITO; the hole transport layer is TAPC; the electron blocking layer is TCTA; the electron transport layer is TmPyPB; the electron injection layer is LiF; and the cathode electrode is Al metal.

[0030] Furthermore, ITO conductive glass is used as the substrate and anode electrode.

[0031] The beneficial effects of this invention are as follows:

[0032] 1. This invention proposes excitocomplex acceptor materials based on nitrogen heterocycles, their preparation methods, and applications. By combining 2-phenyl-4,6-bis(4-pyridine)-1,3,5-triazine with spirobifluorene and pyridine, two excitocomplex acceptor materials were synthesized. The addition of spirobifluorene can increase the rigidity of the molecule, reduce nonradiative transitions, and lower the efficiency roll-off; the addition of pyridine can deepen the LUMO energy level, which is beneficial for the development of red excitocomplex OLEDs and provides more possibilities for the selection of red excitocomplex electron acceptor materials.

[0033] 2. The present invention uses 2-phenyl-4,6-bis(4-pyridine)-1,3,5-triazine containing para-pyridine, which helps to form intermolecular hydrogen bonds with the donor material, enhances intermolecular forces, and improves the external quantum efficiency (EQE) of organic electroluminescent devices.

[0034] 3. This invention combines the synthesized electron acceptor material with the donor material to form an excitocomplex, which serves as the emitting layer of an organic electroluminescent device. It can emit yellow and orange-red light with a peak emission wavelength of 612 nm. It also has a high external quantum efficiency, reaching up to 11.5%, and has broad application prospects. It is expected to be widely used in flat panel displays and solid-state lighting.

[0035] 4. The method for synthesizing the excitocomplex acceptor material proposed in this invention is simple, has a high yield, and exhibits excellent electrochemical stability. Attached Figure Description

[0036] Figure 1 The current density-voltage-luminescence intensity curve of the organic electroluminescent device formed by the excitocomplex acceptor material (13DPy-TRZ) based on nitrogen heterocyclic excitocomplex and 13AB in Example 1 of the present invention is shown.

[0037] Figure 2 This is an external quantum efficiency curve of the organic electroluminescent device formed by the excitocomplex acceptor material (13DPy-TRZ) based on nitrogen heterocyclic excitocomplex and 13AB in Example 1 of the present invention.

[0038] Figure 3 This is a current density-voltage-luminescence intensity curve of the organic electroluminescent device formed by the excitocomplex acceptor material (13DPy-TRZ) based on nitrogen heterocyclic excitocomplex and mPTBC in Example 1 of the present invention.

[0039] Figure 4 This is an external quantum efficiency curve of the organic electroluminescent device formed by the excitocomplex acceptor material (13DPy-TRZ) based on nitrogen heterocyclic excitocomplex and mPTBC in Example 1 of the present invention.

[0040] Figure 5This is a current density-voltage-luminescence intensity curve of the organic electroluminescent device formed by the excitocomplex acceptor material (13DPy-TRZ) based on nitrogen heterocyclic excitocomplex and mPTC in Example 1 of the present invention.

[0041] Figure 6 This is an external quantum efficiency curve of the organic electroluminescent device formed by the excitocomplex acceptor material (13DPy-TRZ) based on nitrogen heterocyclic excitocomplex and mPTC in Example 1 of the present invention.

[0042] Figure 7 This is the electroluminescence spectrum of the organic electroluminescent device in Example 1 of the present invention, which is based on the excitocomplex acceptor material (13DPy-TRZ) of nitrogen heterocycle and mPTC to form an excitocomplex.

[0043] Figure 8 This is a current density-voltage-luminescence intensity curve of the organic electroluminescent device formed by the excitocomplex acceptor material (TRZ-SBF) based on nitrogen heterocyclic excitocomplex and 13AB in Embodiment 2 of the present invention.

[0044] Figure 9 This is an external quantum efficiency curve of the organic electroluminescent device formed by the excitocomplex acceptor material (TRZ-SBF) based on nitrogen heterocyclic excitocomplex and 13AB in Embodiment 2 of the present invention.

[0045] Figure 10 This is a current density-voltage-luminescence intensity curve of the organic electroluminescent device formed by the excitocomplex acceptor material (TRZ-SBF) based on nitrogen heterocyclic excitocomplex and mPTBC in Embodiment 2 of the present invention.

[0046] Figure 11 This is an external quantum efficiency curve of the organic electroluminescent device formed by the excitocomplex acceptor material (TRZ-SBF) based on nitrogen heterocyclic excitocomplex and mPTBC in Embodiment 2 of the present invention.

[0047] Figure 12 This is a current density-voltage-luminescence intensity curve of the organic electroluminescent device formed by the excitocomplex acceptor material (TRZ-SBF) based on nitrogen heterocyclic excitocomplex and mPTC in Embodiment 2 of the present invention.

[0048] Figure 13 This is an external quantum efficiency curve of the organic electroluminescent device formed by the excitocomplex acceptor material (TRZ-SBF) based on nitrogen heterocyclic excitocomplex and mPTC in Embodiment 2 of the present invention.

[0049] Figure 14This is the electroluminescence spectrum of the organic electroluminescent device in Embodiment 1 of the present invention, which is formed by the excitocomplex acceptor material (TRZ-SBF) based on nitrogen heterocyclic excitocomplex and mPTC. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in conjunction with the following specific embodiments and with reference to the accompanying drawings.

[0051] Example 1

[0052] This embodiment proposes a nitrogen heterocyclic excitocomplex acceptor material (13DPy-TRZ) with the structure shown below:

[0053]

[0054] The synthetic route of the excitokinin complex acceptor material (13DPy-TRZ) is as follows:

[0055]

[0056] Specifically, the following steps are included:

[0057] Step 1: Under an inert atmosphere, 3,5-dibromobenzonitrile (0.97 g, 3.73 mmol) was added to 30 mL of anhydrous diethyl ether, followed by the addition of lithium dimethylamino (LiNMe2) (0.19 g, 3.73 mmol) and stirring for 1 h. Then, 4-cyanopyridine (0.77 g, 7.46 mmol) was added, and the reaction was continued under an inert atmosphere for 4 h. Finally, the mixture was stirred in air for 30 min, and the precipitate was collected. The solid was recrystallized from a 1:2 volume ratio of anhydrous ethanol and water to obtain 0.87 g of white solid A, with a yield of 50%.

[0058] Step 2: Add white solid A (0.47 g, 1 mmol), 4-pyridineboronic acid (0.27 g, 2.2 mmol), and tetrakis(triphenylphosphine)palladium (0.05 g, 0.05 mmol) to a 100 mL two-necked round-bottom flask equipped with a magnetic stirrer. Under nitrogen protection, add 24 mL of 1,4-dioxane and 6 mL of 2M potassium carbonate aqueous solution sequentially. Heat and stir under nitrogen to 80 °C and reflux for 24 h. After the white solid A has completely reacted, mixture B is obtained. After cooling to room temperature, mixture B is extracted with saturated sodium chloride aqueous solution and dichloromethane to remove dichloromethane and 1,4-dioxane. A 10:1 (v / v) mixture of methanol and dichloromethane is used as the eluent. The mixture B is purified by silica gel column chromatography. After recrystallization, filtration, and high-temperature sublimation, a yellow solid (0.325 g, 0.7 mmol) is obtained. The yield of the nitrogen-based excitocycline complex acceptor material (13DPy-TRZ) was approximately 65%.

[0059] In this embodiment, the obtained excitogenes acceptor material (13DPy-TRZ) is used to form excitogenes with donor materials 13AB, mPTBC, and mPTC, respectively. An organic electroluminescent device is then prepared by vapor deposition, comprising, from bottom to top, a glass substrate, an ITO anode electrode, a 40 nm thick TAPC hole transport layer, a 10 nm thick TCTA electron blocking layer, a 30 nm thick Donor:13DPy-TRZ emitting layer, a 45 nm thick TmPyPB electron transport layer, a 1 nm thick LiF electron injection layer, and a 100 nm thick Al cathode electrode. The Donor:13DPy-TRZ emitting layer is a thin film composed of a mixture of donor materials 13AB, mPTBC, and mPTC with the synthesized excitogenes acceptor material (13DPy-TRZ), wherein the excitogenes acceptor material (13DPy-TRZ) accounts for 10 wt%.

[0060] The current density-voltage-luminescence (JVL) curve of an organic electroluminescent device based on an excitocomplex acceptor material (13DPy-TRZ) and 13AB forming an excitocomplex is shown in the figure below. Figure 1 As shown, the maximum luminous intensity is 6560 cd / m². 2 The startup voltage is 3.31 V, and the external quantum efficiency curve is as follows: Figure 2 As shown, the maximum external quantum efficiency is 5.18%.

[0061] The JVL curve of an organic light-emitting device that forms an exciton complex with mPTBC based on a nitrogen heterocyclic exciton complex acceptor material (13DPy-TRZ) is shown in Figure 1. Figure 3 As shown, the maximum luminous intensity is 10200 cd / m².2 The startup voltage is 3.72 V, and the external quantum efficiency curve is as follows: Figure 4 As shown, the maximum external quantum efficiency is 4.23%.

[0062] The JVL curve of an organic light-emitting device that forms an exciton complex with mPTC based on a nitrogen heterocyclic exciton complex acceptor material (13DPy-TRZ) is shown in Figure 1. Figure 5 As shown, the maximum luminous intensity is 3580 cd / m². 2 The startup voltage is 2.97 V, and the external quantum efficiency curve is as follows: Figure 6 As shown, the maximum external quantum efficiency is 0.773%, as Figure 7 The electroluminescence spectrum shown indicates that the emission peak of the prepared organic electroluminescent device is 612 nm.

[0063] Example 2

[0064] This embodiment proposes a nitrogen heterocyclic excitolytic complex acceptor material (TRZ-SBF) with the structure shown below:

[0065]

[0066] The synthetic route of the excitokinin complex acceptor material (TRZ-SBF) is as follows:

[0067]

[0068] Specifically, the following steps are included:

[0069] Step 1: Under an inert atmosphere, p-bromobenzonitrile (0.68 g, 3.73 mmol) was added to 30 mL of anhydrous diethyl ether, followed by the addition of lithium dimethylamino (LiNMe2) (0.19 g, 3.73 mmol) and stirring for 1 h. Then, 4-cyanopyridine (0.77 g, 7.46 mmol) was added, and the reaction was continued under an inert atmosphere for 4 h. Finally, the mixture was stirred in air for 30 min, and the precipitate was collected. The solid was recrystallized from a 1:2 volume ratio of anhydrous ethanol and water to obtain a white solid C 0.95 g, with a yield of 65.2%.

[0070] Step 2: Add the above-mentioned white solid C (0.39 g, 1 mmol), 9,9'-spirodifluorene-3-boronic acid (0.4 g, 1.1 mmol), and tetraphenylphosphine palladium (0.05 g, 0.05 mmol) to a 100 mL two-necked round-bottom flask equipped with a magnetic stirrer. Under nitrogen protection, add 30 mL of tetrahydrofuran and 10 mL of 2M potassium carbonate aqueous solution sequentially. Heat and stir under nitrogen to 60 °C, reflux for 8 h, and wait for the white solid C to react completely to obtain mixture D. After cooling to room temperature, extract mixture D with saturated sodium chloride aqueous solution and dichloromethane to remove dichloromethane and tetrahydrofuran. Use a 15:1 (v / v) methanol and dichloromethane mixture as eluent to purify mixture D by silica gel column chromatography. After recrystallization, filtration, and high-temperature sublimation, obtain white solid (0.438 g, 0.7 mmol). The yield of the nitrogen heterocyclic excitosome receptor material (TRZ-SBF) was approximately 70%.

[0071] In this embodiment, the obtained excitogenes complex acceptor material (TRZ-SBF) is used to form excitogenes with donor materials 13AB, mPTBC, and mPTC, respectively. An organic electroluminescent device is then prepared by vapor deposition, comprising, from bottom to top, a glass substrate, an ITO anode electrode, a 40 nm thick TAPC hole transport layer, a 10 nm thick TCTA electron blocking layer, a 30 nm thick Donor:TRZ-SBF emitting layer, a 45 nm thick TmPyPB electron transport layer, a 1 nm thick LiF electron injection layer, and a 100 nm thick Al cathode electrode. The Donor:TRZ-SBF emitting layer is a thin film formed by mixing donor materials 13AB, mPTBC, and mPTC with the synthesized excitogenes complex acceptor material (TRZ-SBF), wherein the excitogenes complex acceptor material (TRZ-SBF) accounts for 10 wt%.

[0072] The current density-voltage-luminescence (JVL) curve of an organic electroluminescent device based on an excitocomplex acceptor material (TRZ-SBF) formed with 13AB is shown in the figure below. Figure 8 As shown, the maximum luminous intensity is 13300 cd / m². 2 The startup voltage is 3.04 V, and the external quantum efficiency curve is as follows: Figure 9 As shown, the maximum external quantum efficiency is 11.5%.

[0073] The JVL curve of an organic light-emitting device that forms an exciton complex with an exciton complex based on a nitrogen heterocyclic exciton complex acceptor material (TRZ-SBF) and mPTBC is shown in the figure. Figure 10 As shown, the maximum luminous intensity is 17500 cd / m². 2The startup voltage is 3.39 V, and the external quantum efficiency curve is as follows: Figure 11 As shown, the maximum external quantum efficiency is 8.14%.

[0074] The JVL curve of an organic light-emitting device that forms an exciton complex with mPTC based on a nitrogen heterocyclic exciton complex acceptor material (TRZ-SBF) is shown in the figure. Figure 12 As shown, the maximum luminous intensity is 2610 cd / m². 2 The startup voltage is 3.6 V, and the external quantum efficiency curve is as follows: Figure 13 As shown, the maximum external quantum efficiency is 0.989%, as Figure 14 The electroluminescence spectrum shown indicates that the emission peak of the prepared organic electroluminescent device is 560 nm.

[0075] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. An exciplex acceptor material based on a nitrogen heterocycle, characterized in that, The molecular structure is TRZ-SBF, 2. A process for the preparation of an aza-heterocycle-based exciplex acceptor material, characterized in that, The method comprises the following steps: Step 1: under nitrogen protection, bromobenzonitrile and dimethylamino lithium are added into anhydrous ether and stirred for 1-3 hours, 4-cyanopyridine is then added and stirred for 4-6 hours to obtain a mixed solution C with the concentration of bromobenzonitrile being 0.1-0.2 mmol / mL; then the mixture is stirred for 0.5-2 hours in air, and the precipitate is collected and recrystallized to obtain solid C; wherein the molar ratio of bromobenzonitrile, dimethylamino lithium and 4-cyanopyridine is 1:(1.0-2.0):(2.0-2.5); Step 2: solid C, 9,9'-spirobifluorene-3-boronic acid and palladium catalyst are added in the molar ratio of 1:(1.5-2.5):(0.01-0.3) under nitrogen protection, and tetrahydrofuran and 2M potassium carbonate aqueous solution are added in the volume ratio of 3:1 to obtain a mixed solution D with the concentration of solid C being 0.03-0.10 mmol / mL; the mixture is heated to 60-80 DEG C and reacted for 8-10 hours until solid C is completely reacted to obtain mixture D; after cooling to room temperature, the mixture D is extracted with saturated sodium chloride aqueous solution and dichloromethane; then dichloromethane and tetrahydrofuran are removed, and a mixed solution of methanol and dichloromethane in the volume ratio of 15:1 is used as an eluent to purify the mixture D by silica gel column chromatography; after recrystallization, suction filtration and high-temperature sublimation, the nitrogen heterocycle-based exciplex acceptor material according to claim 1 is obtained.

3. The method for preparing a radical complex acceptor material based on a nitrogen heterocycle according to claim 2, characterized in that, Step 1 uses ethanol and water for recrystallization, and step 2 uses dichloromethane and methanol for recrystallization.

4. The method for preparing a radical complex acceptor material based on a nitrogen heterocycle according to claim 2, characterized in that, The palladium catalyst in step 2 is tetrakis triphenylphosphine palladium.

5. An organic electroluminescent device, characterized by comprising The device comprises a substrate, an anode electrode, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode electrode arranged from bottom to top; the light-emitting layer is a thin film formed by mixing a donor material and the nitrogen heterocycle-based exciplex acceptor material according to claim 1, and the proportion of the exciplex acceptor material in the light-emitting layer is 5-30 wt%.

6. The organic electroluminescent device according to claim 5, wherein The donor material is a molecule containing an acridine and a phenoxazine donor group.

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