A benzothieno-azacycle compound and an electroluminescent device

Abstract

The application belongs to the technical field of organic light-emitting materials and semiconductor, and particularly relates to a benzothiophene-nitrogen heterocycle compound and an electroluminescent device. The benzothiophene-nitrogen heterocycle compound is obtained by introducing different substituents at the N atom site of the main body structure and the 2nd site of thiophene, and has a donor-acceptor type structure. The structural formula of the benzothiophene-nitrogen heterocycle compound is shown in the following. The electroluminescent device is prepared by using the benzothiophene-nitrogen heterocycle compound as a guest light-emitting material. The light-emitting efficiency of the device can be effectively improved, the service life is prolonged, the emitted light has good color purity. The emission wavelength of the electroluminescent device is in the visible light range, which meets the application requirements of different scenes.

Description

Technical Field

[0001] This invention belongs to the field of organic light-emitting materials and semiconductor technology, specifically relating to a benzothiophene-azo-heterocyclic compound and an electroluminescent device. Background Technology

[0002] Organic light-emitting diodes, or OLEDs for short, are a key technology in the display and lighting fields due to their advantages such as self-illumination, wide viewing angle, high contrast, and flexibility. Their core performance largely depends on the material of the light-emitting layer. Among these, thermally activated delayed fluorescence (TEF) materials, as third-generation OLED light-emitting materials, theoretically achieve 100% exciton utilization without relying on precious metals, and therefore have attracted considerable attention.

[0003] Thermally activated delayed fluorescence (TADF) materials achieve 100% exciton utilization by using molecular designs with a small singlet-triple energy level difference, enabling triplet excitons to be converted into singlet excitons for emission via reverse intersystem crossing. To achieve this property, the classic strategy is to construct donor-acceptor (DA) configuration molecules to achieve a smaller singlet-triple energy level difference, thus breaking the exciton utilization limit of fluorescent materials.

[0004] However, these DA-type molecules typically suffer from the following technical problems: strong charge transfer states lead to enhanced excited-state charge transfer characteristics, causing emission spectrum broadening and decreased color purity, especially prominent in blue light materials. For example, the classic DA-type TADF compound 3BPy-mDTC, with tert-butylcarbazole (DTC) as the donor and benzoylpyridine (3BPy) as the acceptor, has a blue emission spectrum with a full width at half maximum (FWHM) of 66 nm, and the emission wavelength deviates from the standard blue light range, resulting in color purity that fails to reach the ideal level and limiting its application. The problem of spectral broadening caused by strong charge transfer characteristics has not yet been completely solved.

[0005] Furthermore, the relatively flexible molecular framework and long exciton lifetime of DA-type TADF compounds are prone to concentration quenching and efficiency roll-off at high currents, thus limiting the stability and lifetime of devices. For example, traditional TADF molecules (such as 4CzIPN and DAcIPN) with their DA or DAD frameworks tend to have an increased number of non-radiative decay channels in the excited state of the molecules in the aggregated state, resulting in reduced luminous efficiency; at the same time, the delayed fluorescence lifetime is significantly shortened, leading to a prominent efficiency roll-off problem at high brightness, making it impossible to balance high brightness and high quantum efficiency, and thus failing to meet the performance requirements of practical OLED applications.

[0006] While emerging multi-resonance TADF materials can achieve narrow-band emission and ensure high color purity through atomically precise push-pull electron effects, their synthesis is cumbersome and yields are low, thus limiting their practical applications. Furthermore, in the crucial field of blue light, TADF materials generally suffer from drawbacks such as short lifetime, poor color purity, and insufficient chemical stability. Summary of the Invention

[0007] To address the shortcomings of existing TADF compounds in achieving both high luminous efficiency and high color purity, as well as insufficient stability, this invention provides a benzothiophene-azo-heterocyclic compound and an electroluminescent device.

[0008] This invention uses a fused-ring skeleton of benzothiophene and a nitrogen-containing heterocycle as the main structure. By introducing different substituents at the N atom site of the main structure and the 2 site of thiophene, benzothiophene-nitrogen heterocyclic compounds with a donor-acceptor structure are obtained. The rigid structure of the benzothiophene-nitrogen heterocyclic compounds and the steric hindrance provided by the R1 and Ar1 groups effectively reduce molecular aggregation and excitoassociation formation, suppressing concentration quenching and thus improving the efficiency roll-off phenomenon of devices at high current densities. Furthermore, the rigid structure and conjugated system of the fused-ring skeleton also enhance the thermal and morphological stability of the material, which is beneficial for extending the device's operating life.

[0009] The first objective of this invention is to provide a benzothiophene-azo heterocyclic compound, the structural formula of which is shown below: ; R1 is selected from substituted or unsubstituted C5 to C13. 30 aryl groups and substituted or unsubstituted C5-C6 groups 30 Ar1 is any one of the heteroaryl groups, wherein the heteroatom of the heteroaryl group in R1 is selected from at least one of N, S, O, and Si; the substituent in R1 is at least one of methyl, deuterated methyl, tert-butyl, deuterated tert-butyl, and phenyl; and Ar1 is selected from substituted or unsubstituted C6-C6 groups. 20 The heteroaryl group in Ar1 is selected from at least one of N, S and O; the substituent in Ar1 is phenyl.

[0010] Preferably, R1 is selected from any one of the following groups: ; “ “” indicates a bonding site, and R1 is bonded through any one of these bonding sites.

[0011] Preferably, Ar1 is selected from any one of the following groups: .

[0012] Preferably, the benzothiophene-azo-heterocyclic compound is selected from one of the following compounds: .

[0013] The present invention provides an electroluminescent device comprising an anode layer, a hole transport layer, an emitting layer, an electron transport layer and a cathode layer stacked sequentially, wherein the emitting layer is prepared by a host emitting material and a guest emitting material, and the guest emitting material is the benzothiophene-nitrogen heterocyclic compound.

[0014] Preferably, the mass of the guest luminescent material accounts for 1.0 wt.% to 3.0 wt.% of the mass of the luminescent layer.

[0015] Preferably, the host luminescent material is selected from at least one of the following compounds: .

[0016] In this invention, the electroluminescent device comprises, from the anode layer to the cathode layer, a substrate, an anode layer, a hole injection layer (HIL), a hole transport layer, an electron blocking layer (EBL), an emission material layer (EML), a hole blocking layer (HBL), an electron transport layer, an electron injection layer (EIL), a cathode layer, and a capping layer, which are stacked sequentially.

[0017] Preferably, the anode layer is made of a transparent conductive oxide material, including but not limited to indium tin oxide, indium zinc oxide, tin dioxide, and zinc oxide.

[0018] Preferably, the cathode layer is made of a highly conductive elemental metal or alloy, selected from at least one of magnesium, silver, aluminum, aluminum-lithium alloy, calcium, magnesium-indium alloy, and magnesium-aluminum alloy.

[0019] Preferably, the hole transport layer is a single-layer hole transport layer or a multi-layer composite hole transport layer; wherein, the single-layer hole transport layer is a single-layer hole transport layer containing one or more compounds (which has both hole injection function and hole transport effect); the multi-layer hole transport layer is composed of a hole injection layer, a hole transport layer and an electron blocking layer stacked in sequence.

[0020] Preferably, the material of the hole transport layer is selected from at least one of the following compounds: .

[0021] Preferably, the electron transport layer is a composite electron transport layer, which is formed by sequentially stacking an electron injection layer, an electron transport layer, and an electron blocking layer. The material of the electron transport layer is selected from at least one of the following compounds:

[0022] .

[0023] Preferably, the substrate is made of glass or polymer materials with high mechanical strength, excellent thermal stability, and waterproof and light-transmitting properties, such as PET (polyethylene terephthalate) plastic.

[0024] Furthermore, when applied to display devices, the substrate can integrate a thin-film transistor array, and a preset display pattern can be formed by driving the TFT array. The thickness and surface treatment process of the substrate can be adjusted according to the device requirements.

[0025] Compared with the prior art, the present invention has the following beneficial effects: This invention uses a fused-ring framework of benzothiophene and a nitrogen-containing heterocyclic ring as the main structure. By substituting an R1 group at the N atom site of the main structure and an Ar1 group at the 2 site of thiophene, a benzothiophene-nitrogen heterocyclic compound with a DA-type structure is obtained. The rigid structure and the steric hindrance of the R1 and Ar1 groups effectively restrict intramolecular vibrations and rotations, reducing non-radiative transitions and improving radiative transition efficiency. Simultaneously, it inhibits molecular aggregation, reduces concentration quenching and efficiency roll-off, thereby improving the quantum yield of the device. Furthermore, the rigid structure and conjugated system of the fused-ring framework enhance the thermal stability and film-forming properties of the material, strengthen the chemical stability of the molecules, and significantly extend the device's lifetime under air or long-term operation.

[0026] This invention utilizes a DA-type structure with electron-donating and electron-withdrawing groups to construct hybrid local charge-transfer excited states, enabling reverse intersystem crossing from triplet excitons to singlet states. This approach brings exciton utilization close to 100%, significantly improving the external quantum efficiency of the device. Simultaneously, the combination of sulfur and nitrogen atoms in the donor-acceptor unit allows for the control of the frontier orbital distribution, reducing the carrier injection barrier and thus improving luminescence efficiency. Furthermore, it precisely adjusts the emission wavelength (covering blue, green, and red bands) to adapt to OLED devices in different wavelength ranges.

[0027] This invention adjusts the degree of conjugation and the range of electron delocalization of the molecule by flexibly selecting and combining the R1 and Ar1 substituents in the main structure, suppresses the formation of excito-associations, and gives the compound molecule certain TADF characteristics, which helps to achieve narrow-band emission and thus improve the color purity of the luminescence.

[0028] Using the benzothiophene-nitrogen heterocyclic compounds synthesized in this invention as guest light-emitting materials to prepare electroluminescent devices can effectively improve the luminous efficiency of the devices, extend their service life, and make the emitted light have good color purity. Furthermore, the emission wavelength of the electroluminescent devices is within the visible light range, meeting the application requirements of different scenarios. Attached Figure Description

[0029] Figure 1 This is the chemical structural formula of the benzothiophene-azo heterocyclic compound synthesized in this invention.

[0030] Figure 2 This is a cross-sectional view of the electroluminescent device of the present invention.

[0031] Figure 3The NMR spectrum of compound 4 prepared in Example 1 is shown.

[0032] Figure 4 The NMR spectrum of compound 10 prepared in Example 2 is shown.

[0033] Figure 5 The NMR spectrum of compound 17 prepared in Example 3 is shown.

[0034] Figure 6 The NMR spectrum of compound 26 prepared in Example 4 is shown.

[0035] Figure 7 The NMR spectrum of compound 39 prepared in Example 5 is shown.

[0036] Figure label: 1-Substrate, 2-Anode layer, 3-Hole injection layer, 4-Hole transport layer, 5-Electron blocking layer, 6-Light emitting layer, 7-Hole blocking layer, 8-Electron transport layer, 9-Electron injection layer, 10-Cathode layer, 11-Cover layer. Detailed Implementation

[0037] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading this description, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0038] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Process equipment or apparatus not specifically specified in the following examples are all conventional equipment or apparatus in the art. All raw materials used in the following examples are conventional commercially available products with specifications in the art, unless otherwise stated.

[0039] like Figure 1 As shown, this invention uses a fused-ring skeleton of benzothiophene-azo heterocyclic rings as the main structure. By introducing different substituents at the N atom site of the main structure and the 2nd site of thiophene, benzothiophene-azo heterocyclic compounds with a "DA" structure are obtained. Specifically, an R1 group is substituted at the N atom site of the main structure, and an Ar1 group is substituted at the 2nd site of thiophene. The Ar1 group is provided by reactant a; the R1 group is provided by reactant b; reactant a is selected from one of the compounds shown in formulas a1 to a12, and reactant b is selected from at least one of the compounds shown in formulas b1 to b20.

[0040] .

[0041] It should be noted that the English name for High Performance Liquid Chromatography is HPLC; the English name for Liquid Chromatography-Mass Spectrometry is LC-MS; the Chinese name for Pd(dppf)Cl2 is 1,1-bis(diphenylphosphine)ferrocene palladium dichloride; the Chinese name for Pd(PPh3)4 is tetrakis(triphenylphosphine)palladium; the Chinese name for Pd2(dba)3 is tetrakis(dibenzylideneacetone)dipalladium; the Chinese name for P(t-Bu)3 is tritert-butylphosphine; BrettPhos Pd The Chinese name for G3 is methanesulfonic acid (2-dicyclohexylphosphine)-3,6-dimethoxy-2',4',6'-triisopropyl-1,1'-biphenyl)(2'-amino-1,1'-biphenyl-2-yl)palladium(II); the Chinese name for S-phos is 2-dicyclohexylphosphine-2',6'-dimethoxy-1,1'-diphenyl.

[0042] In a specific embodiment of the synthesis of benzothiophene-azo-heterocyclic compounds, the synthesis processes of the required intermediates M1 and M2 are as follows: The synthetic route for intermediate M1 is as follows: .

[0043] The specific synthesis process is as follows: Under nitrogen protection, 0.1 mol of 2-bromoaniline, 0.1 mol of pinacol diborate, 0.3 mol of potassium acetate, and 600 mL of 1,4-dioxane were added to a 1000 mL three-necked flask. After stirring, the mixture was heated to 65 °C, and 2 mmol of Pd(dppf)Cl2 was added. The mixture was then refluxed at 100-105 °C for 5 h until the reactants were completely reacted. The reaction solution was filtered while hot, and the filtrate was collected, concentrated under reduced pressure, dissolved in 250 mL of toluene, and washed with water. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated. The organic phase was then passed through a silica gel column, and the column chromatography was reduced pressure again until solid precipitated. The mixture was cooled to 10 °C, crystallized, filtered, and dried to obtain intermediate M1, weighing 18.6 g, with a yield of 85%, an HPLC purity of 98%, and a molecular weight of 219.1 as shown by LC-MS.

[0044] The synthetic route for intermediate M2 is as follows: .

[0045] Step 1, Synthesis of intermediate M2-1: Under nitrogen protection, methyl 3-bromo-4-chloro-benzo[b]thiophene-2-carboxylate (0.1 mol), intermediate M1 (0.1 mol), Pd(PPh3)4 (2 mmol), K2CO3 (0.2 mol), 480 mL of 1,4-dioxane, and 120 mL of H2O were added to a 1000 mL three-necked flask. The system was heated to reflux and reacted for 12 h until the reaction was complete. After the reaction solution was cooled to room temperature, it was washed with water and separated. The organic phase was passed through a diatomaceous earth funnel and the filtrate was collected. The filtrate was concentrated under reduced pressure to obtain a crude solid product. The crude solid product was purified by silica gel column chromatography (petroleum ether and dichloromethane in a volume ratio of 8:1) to obtain intermediate M2-1, weighing 23.9 g, with a yield of 75.3%, HPLC purity of 98%, and LC-MS showing a molecular weight of 317.0.

[0046] Step 2, Synthesis of intermediate M2-2: Under nitrogen protection, intermediate M2-1 (0.1 mol) and 600 mL of toluene were added to a 1000 mL three-necked flask. The mixture was stirred until the solution was clear. Palladium acetate (2 mmol), S-phos (5 mmol), and sodium tert-butoxide (0.3 mol) were then added. The reaction mixture was heated to 100 °C and reacted for 10 h. After the reaction was completed, the mixture was filtered while hot using diatomaceous earth. The filtrate was cooled to room temperature and washed with purified water. The organic phase was separated and the aqueous phase was extracted with ethyl acetate. The organic phases were combined, dried over anhydrous magnesium sulfate, concentrated, and column filtered (petroleum ether and dichloromethane in a volume ratio of 8:1) to obtain intermediate M2-2, weighing 19.8 g, with a yield of 70.5%, an HPLC purity of 98%, and a molecular weight of 281.1 as shown by LC-MS.

[0047] Step 3, Synthesis of intermediate M2-3: Under nitrogen protection, intermediate 2-2 (0.1 mol), sodium hydroxide (0.3 mol), 50 mL of water, and 250 mL of ethanol were added to a 500 mL three-necked flask. Stirring was initiated, and the reaction mixture was heated to reflux for 12 h. After the reaction was complete, the mixture was cooled to room temperature, and the reaction solution was concentrated under reduced pressure to remove some of the ethanol. The pH of the concentrate was adjusted to strongly acidic with concentrated hydrochloric acid, resulting in the precipitation of a white solid. The filtrate was removed by suction filtration, and the filter cake was retained to obtain intermediate M2-3, weighing 24.2 g. The yield was 90.6%, the HPLC purity was 97%, and the molecular weight was 267.0 as shown by LC-MS.

[0048] Step 4: Synthesis of intermediate M2: Under oxygen protection, intermediate M2-3 (0.1 mol), CuI (0.15 mol), CuCl (0.12 mol), and 500 mL of dimethyl sulfoxide were added to a 1000 mL three-necked flask. The oxygen was replaced three times, and a pressure of 1 atm was applied. The reaction mixture was stirred and heated to 160 °C for 12 h. After the reaction was complete, the mixture was cooled to room temperature, filtered through diatomaceous earth, and the filtrate was concentrated under reduced pressure to obtain a residue. The residue was purified by silica gel column chromatography (petroleum ether and dichloromethane in a volume ratio of 10:1) to obtain intermediate M2, weighing 19.4 g, with a yield of 75.5%, an HPLC purity of 98%, and a molecular weight of 257.0 as shown by LC-MS.

[0049] Example 1 The synthetic method and specific synthetic route for benzothiophene-azo heterocyclic compounds are shown below: .

[0050] Step 1, Synthesis of Intermediate 4-1: Under nitrogen protection, intermediate M2 (0.1 mol), compound b4 (0.1 mol), sodium tert-butoxide (0.3 mol), and 500 mL of toluene were added to a 1000 mL three-necked flask. After stirring, the mixture was heated to 65 °C, and P(t-Bu)3 (5 mmol) and Pd2(dba)3 (2 mmol) were added. The mixture was then heated to 100 °C and refluxed for 6 h until intermediate M2 was completely reacted. The reaction solution was cooled and filtered. The filtrate was collected, concentrated under reduced pressure to dryness, dissolved in 250 mL of toluene, and washed with water. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated. The organic phase was passed through a silica gel column, and the column chromatography solution was concentrated again under reduced pressure until solid precipitates. The mixture was then cooled until crystallization was complete, filtered, and dried to obtain intermediate 4-1, weighing 36.6 g, with a yield of 73.2%. The HPLC purity was 98%, and the LC-MS showed a molecular weight of 500.1.

[0051] Step 2, Synthesis of Compound 4: Under nitrogen protection, intermediate 4-1 (0.05 mol), compound a4 (0.08 mol), K3PO4 (0.12 mol), and 500 mL of 1,4-dioxane were added to a 1000 mL three-necked flask. After stirring, the temperature was raised to 65 °C, and BrettPhos Pd G3 (2.5 mmol) was added. The temperature was then raised to reflux for 12 h until intermediate 4-1 was completely reacted. The reaction solution was cooled and filtered. The filtrate was collected, concentrated under reduced pressure to dryness, dissolved in 200 mL of toluene, and washed with water. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated. The organic phase was passed through a silica gel column, and the column chromatography was concentrated again under reduced pressure until solid precipitates. The solution was then cooled until crystallization was complete, filtered, and dried to obtain compound 4, weighing 24.9 g, with a yield of 81.4%, HPLC purity of 98%, and LC-MS molecular weight of 611.2.

[0052] The 1H NMR spectrum of compound 4 is shown below. Figure 3 As shown, the 1H NMR spectrum data are: 1 H NMR(500 MHz, DMSO-d6) δ7.97 (dd, J = 5.1, 3.2 Hz, 2H), 7.94 - 7.86 (m, 1H), 7.79 (dd, J = 5.1, 3.1Hz, 2H), 7.72 (dd, J = 6.8, 1.1 Hz, 1H), 7.41 - 7.25 (m, 8H), 7.21 - 7.13 (m,2H), 7.13 - 7.08 (m, 4H), 7.06-7.02 (m, 3H), 6.93-6.91 (m, 1H), 6.31 (t, J =2.1 Hz, 1H).

[0053] Example 2 The synthetic method and specific synthetic route for benzothiophene-azo heterocyclic compounds are shown below: .

[0054] Step 1, Synthesis of Intermediate 10-1: Under nitrogen protection, intermediate M2 (0.1 mol), compound a10 (0.1 mol), Pd(PPh3)4 (2 mmol), K2CO3 (0.2 mol), 480 mL of 1,4-dioxane, and 120 mL of H2O were added to a 1000 mL three-necked flask. The system was heated to reflux and reacted for 12 h until the reaction was complete. After the reaction solution was cooled to room temperature, it was washed with water and separated. The organic phase was passed through a diatomaceous earth funnel and the filtrate was collected. The filtrate was concentrated under reduced pressure to obtain a crude solid product. The crude solid product was purified by silica gel column chromatography (petroleum ether and dichloromethane in a volume ratio of 10:1) to obtain intermediate 10-1, weighing 29.3 g, with a yield of 86%, an HPLC purity of 98%, and a molecular weight of 341.0 as shown by LC-MS.

[0055] Step 2, Synthesis of Compound 10: Under nitrogen protection, intermediate 10⁻¹ (0.1 mol), compound b10 (0.1 mol), sodium tert-butoxide (0.3 mol), and 600 mL of toluene were added to a 1000 mL three-necked flask. After stirring, the mixture was heated to 65 °C, and P(t-Bu)₃ (5 mmol) and Pd₂(dba)₃ (2 mmol) were added. The mixture was then refluxed at 100 °C for 6 h until intermediate 10⁻¹ was completely reacted. The reaction solution was cooled and filtered. The filtrate was collected, concentrated under reduced pressure to dryness, dissolved in 250 mL of toluene, and washed with water. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated. The organic phase was then passed through a silica gel column, and the column chromatography was reduced pressure again until solid precipitates. The mixture was then cooled until crystallization was complete, filtered, and dried to obtain compound 10, weighing 50.7 g, with a yield of 87.1%, HPLC purity of 98%, and LC-MS molecular weight of 582.1.

[0056] The 1H NMR spectrum of compound 10 is shown below. Figure 4 As shown; 1H NMR data: 1 H NMR (500 MHz, DMSO-d6) δ8.30 (dd, J = 4.9, 2.2 Hz, 1H), 8.15 - 8.08 (m, 1H), 7.97 (dd, J = 7.7, 2.2Hz, 1H), 7.94 - 7.88 (m, 1H), 7.69 - 7.61 (m, 2H), 7.61 - 7.56 (m, 2H), 7.53- 7.46 (m, 2H), 7.46 - 7.28 (m, 9H), 7.24 (dd, J = 7.7, 4.8 Hz, 1H), 7.14 -7.08 (m, 1H), 7.06 (dd, J = 6.6, 1.3 Hz, 1H).

[0057] Example 3 The synthetic method and specific synthetic route for benzothiophene-azo heterocyclic compounds are shown below: .

[0058] Step 1, Synthesis of Intermediate 17-1: Referring to Example 2, the synthesis process of intermediate M2 to compound 10-1 was modified as follows: compound a5 (0.1 mol) was used to replace compound a10 (0.1 mol) to obtain intermediate 17-1, weighing 38.3 g, with a yield of 84.8%, HPLC purity of 98%, and LC-MS showing a molecular weight of 451.1.

[0059] Step 2, Synthesis of Compound 17: Referring to Example 2, the synthesis method of intermediate 10-1 to compound 10 was modified as follows: intermediate 10-1 (0.1 mol) was replaced with intermediate 17-1 (0.1 mol), and compound b10 (0.1 mol) was replaced with compound b17 (0.1 mol) to obtain compound 17, weighing 61.3 g, with a yield of 89%, an HPLC purity of 98%, and a molecular weight of 689.3 as shown by LC-MS.

[0060] The 1H NMR spectrum of compound 17 is shown below. Figure 5 As shown; 1H NMR data: 1 H NMR (500 MHz, DMSO-d6)δ 8.54 (s, 1H), 8.39 (s, 1H), 8.23 ​​(d, J = 4.2 Hz, 2H), 8.18 (s, 1H), 7.92-7.86 (m, 2H), 7.82 (s, 1H), 7.71 (d, J = 13.0 Hz, 2H), 7.55 -7.50 (m, 3H),7.49 (s, 1H), 7.39-7.27 (m, 4H), 7.10 (d, J = 9.2 Hz, 2H), 7.00 (dd, J = 7.3,2.2 Hz, 1H), 1.34 (d, J = 17.9 Hz, 18H).

[0061] Example 4 The synthetic method and specific synthetic route for benzothiophene-azo heterocyclic compounds are shown below: .

[0062] Step 1, Synthesis of Compound 26-1: Referring to Example 2, the synthesis process of intermediate M2 to compound 10-1 was modified by replacing compound a10 (0.1 mol) with compound a2 (0.1 mol) to obtain intermediate 26-1, weighing 38.5 g, with a yield of 85%, HPLC purity of 98%, and LC-MS showing a molecular weight of 453.1.

[0063] Step 2: Synthesis of compound 26: Referring to Example 2, the synthesis method of intermediate 10-1 to compound 10 was modified as follows: intermediate 26-1 (0.1 mol) was used to replace intermediate 10-1 (0.1 mol), and compound b5 (0.1 mol) was used to replace compound b10 (0.1 mol), resulting in compound 26, weighing 62.6 g, with a yield of 88.2%, an HPLC purity of 98%, and a molecular weight of 710.2 as shown by LC-MS.

[0064] The 1H NMR spectrum of compound 26 is shown below. Figure 6 As shown; 1H NMR data: 1 H NMR (500 MHz, DMSO-d6 )δ 8.27-8.22 (m, 4H), 7.98 (s, 1H), 7.92-7.86 (m, 2H), 7.55-7.20 (m, 19H),7.20-7.10 (m, 3H), 7.05 (dd, J = 7.4, 2.2 Hz, 1H).

[0065] Example 5 The synthetic method and specific synthetic route for benzothiophene-azo heterocyclic compounds are shown below: .

[0066] Step 1, Synthesis of Compound 39: Referring to Example 2, the synthesis process of intermediate M2 to compound 10-1 was modified by replacing compound a10 (0.1 mol) with compound a6 (0.1 mol) to obtain intermediate 39-1, weighing 36.1 g, with a yield of 84.6%, HPLC purity of 98%, and LC-MS showing a molecular weight of 427.1.

[0067] Step 2: Synthesis of compound 39: Referring to Example 2, the synthesis method of intermediate 10-1 to compound 10 was modified as follows: intermediate 39-1 (0.1 mol) was used to replace intermediate 10-1 (0.1 mol), and compound b11 (0.1 mol) was used to replace compound b10 (0.1 mol), resulting in compound 39, weighing 53.1 g, with a yield of 88%, an HPLC purity of 98%, and a molecular weight of 603.2 as shown by LC-MS.

[0068] The 1H NMR spectrum of compound 39 is shown below. Figure 7 As shown; 1H NMR data: 1 H NMR (500 MHz, DMSO-d6 )δ 8.42 (s, 1H), 8.14 (d, J = 3.3 Hz, 2H), 8.10 (s, 2H), 8.04 (s, 2H), 7.94-7.88 (m, 2H), 7.66 (s, 2H), 7.60-7.54 (m, 4H), 7.53 (s, 2H), 7.50-7.40 (m,3H), 7.39-7.27 (m, 3H), 7.11-7.05 (m, 2H).

[0069] The synthesis of other compounds follows the same process as the synthesis of compound 4 in Example 1 and compound 10 in Example 2, except that the corresponding starting reactant a and reactant b are selected during the synthesis process.

[0070] The reactant compositions of some compounds in this invention are shown in Table 1: Table 1. Reactant composition of some compounds in this invention Electroluminescent devices were fabricated using benzothiophene-nitrogen heterocyclic compounds as guest luminescent materials. A schematic diagram of the electroluminescent device is shown below. Figure 2 As shown, it includes a substrate 1 and an anode layer 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light-emitting layer 6, a hole blocking layer 7, an electron transport layer 8, an electron injection layer 9, a cathode layer 10, and a capping layer 11, which are sequentially stacked on the substrate 1.

[0071] The fabrication method for electroluminescent devices employs currently recognized industry-standard device fabrication technologies. The chemical structures of some of the materials used in the fabrication process are as follows:

[0072] .

[0073] Application Example 1 The method for fabricating an electroluminescent device includes the following steps: In an electroluminescent device, from the anode layer to the cathode layer, the following layers are sequentially stacked: PET plastic, indium tin oxide (ITO), HAT-CN, TCTA, mCBP, light-emitting layer, PPT, ET-1, Liq, Mg:Ag (1:9) and CPL.

[0074] Under high vacuum conditions, using a 1.5 mm thick PET substrate 1 as the polymer substrate, a 100 nm thick indium tin oxide (ITO) material is adhered to the substrate 1 as the anode 2. Using a vacuum evaporation apparatus, a 20 nm thick compound HAT-CN is deposited sequentially as a hole injection layer 3, a 40 nm thick compound TCTA as a hole transport layer 4, a 30 nm thick compound mCBP as an electron blocking layer 5, and a 50 nm thick light-emitting layer 6. The light-emitting layer 6 is prepared using compound CBP as the first host light-emitting material, BCP as the second host light-emitting material, and compound 1 as the guest light-emitting material; the mass ratio of compound CBP, compound BCP, and compound 1 is 49:49:2.

[0075] Continue by depositing a 10 nm thick compound PPT as a hole blocking layer 7 and a 30 nm thick ET-l as an electron transport layer 8 on the light-emitting layer 6; then, deposit a 10 nm thick Liq as an electron injection layer 9 and an 80 nm thick Mg-Ag electrode layer as a cathode layer 10 on the electron transport layer 8 in sequence; the mass ratio of Mg to Ag is 1:9.

[0076] Finally, a 40 nm thick CPL layer is deposited on the cathode layer 8 as a high refractive index capping layer 11; then, after vacuum encapsulation, an electroluminescent device, denoted as Ex.1, is obtained.

[0077] Application Example 2 The preparation method of the electroluminescent device is basically the same as that of Application Example 1, except that the guest luminescent material is different; compounds 4, 10, 17, 26, 39, 43, 55, 63, 67, 77, 79, 91, 98, 116, 120, 126, 133, 138, 148, 153, 157, 171, 175, 190, 193, and 197 are used respectively. Compounds 202, 203, and 209 were used to replace compound 1 as the guest luminescent material in the luminescent layer 5 to prepare corresponding electroluminescent devices, denoted as Ex.2, Ex.3, Ex.4, Ex.5, Ex.6, Ex.7, Ex.8, Ex.9, Ex.10, Ex.11, Ex.12, Ex.13, Ex.14, Ex.15, Ex.16, Ex.17, Ex.18, Ex.19, Ex.20, Ex.21, Ex.22, Ex.23, Ex.24, Ex.25, Ex.26, Ex.27, Ex.28, and Ex.29.

[0078] Application Comparative Example 1 The preparation method of the electroluminescent device is basically the same as that in Application Example 1, except that the guest light-emitting material is different. Compound ref-1 from the patent application with publication number EP4486099A1 is used as the guest light-emitting material to obtain the electroluminescent device, denoted as Pro.1. The chemical structural formula of compound ref-1 is as follows: .

[0079] Application Comparative Example 2 The preparation method of the electroluminescent device is basically the same as that in Application Example 1, except that the guest luminescent material is different. Compound ref-2 from the patent application with publication number WO2013 / 055132A is used as the guest luminescent material to obtain the electroluminescent device, denoted as Pro.2. The chemical structural formula of compound ref-2 is as follows: .

[0080] Application Comparative Example 3 The preparation method of the electroluminescent device is basically the same as that in Application Example 1, except that the guest light-emitting material is different. Compound ref-3 from the patent application with publication number KR1020130139412A is used as the bulk light-emitting material, resulting in an electroluminescent device, denoted as Pro.3. The chemical structural formula of compound ref-3 is as follows: .

[0081] Electroluminescent devices from Application Examples 1-2 and Comparative Examples 1-3 were fabricated into 50mm × 50mm samples. Then, under the same device fabrication process conditions, the anode and cathode layers were connected using an industry-known driving circuit, and the luminescent performance of each electroluminescent device was tested. For the electroluminescent devices, at 10mA / cm... 2 The driving voltage and luminous efficiency were measured at a current density of 20 mA / cm². 2 The time required for the brightness to return to 95% of its initial brightness at a given current density is LT95, which is the lifetime. The test results are shown in Table 2.

[0082] Table 2 Performance data of the electroluminescent devices prepared in Application Examples 1-2 and Comparative Examples 1-3 Note: "EQE" refers to 1000 cd / m³ 2 External quantum efficiency at operating brightness.

[0083] As can be seen from the performance data in Table 2, compared with the electroluminescent devices prepared using the guest luminescent materials ref-1, ref-2, and ref-3 in the comparative examples, the electroluminescent devices prepared using the benzothiophene-nitrogen heterocyclic compounds of this invention as guest luminescent materials show a significant improvement in overall luminous efficiency. Specifically, the full width at half maximum (FWHM) is significantly narrowed, the external quantum efficiency is increased by approximately 50%, and the lifespan is extended. Furthermore, adjusting the degree of molecular conjugation and the range of electron delocalization suppresses excitoassociation formation, giving the compound molecules certain TADF characteristics, which helps to achieve narrow-band emission and thus improves the color purity of the emitted light.

[0084] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Many other changes and modifications can be made without departing from the concept and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A benzothiophene-azo-heterocyclic compound, characterized in that, The structural formula of the benzothiophene-nitrogen heterocyclic compound is shown below: ； R1 is selected from substituted or unsubstituted C5 to C13. 30 aryl groups and substituted or unsubstituted C5-C6 groups 30 The heteroaryl group in R1 is selected from at least one of N, S, O and Si; the substituent in R1 is at least one of methyl, deuterated methyl, tert-butyl, deuterated tert-butyl and phenyl. Ar1 is selected from substituted or unsubstituted C6 to C1. 20 The heteroaryl group in Ar1 is selected from at least one of N, S and O; the substituent in Ar1 is phenyl.

2. The benzothiophene-nitrogen heterocyclic compound according to claim 1, characterized in that, R1 is selected from any one of the following groups: ； " “” indicates a bonding site, and R1 is bonded through any one of these bonding sites.

3. The benzothiophene-nitrogen heterocyclic compound according to claim 1, characterized in that, Ar1 is selected from any one of the following groups: 。 4. The benzothiophene-nitrogen heterocyclic compound according to claim 1, characterized in that, Benzothiophene-azo-heterocyclic compounds are selected from one of the following compounds: 。 5. An electroluminescent device, comprising an anode layer, a hole transport layer, an emitting layer, an electron transport layer, and a cathode layer stacked sequentially, wherein the emitting layer is prepared from a host emitting material and a guest emitting material, and the guest emitting material is a benzothiophene-azo-heterocyclic compound as described in any one of claims 1 to 4.

6. The electroluminescent device according to claim 5, characterized in that, The mass of the guest luminescent material accounts for 1.0 wt.% to 3.0 wt.% of the mass of the luminescent layer.

7. The electroluminescent device according to claim 6, characterized in that, The main luminescent material is selected from at least one of the following compounds: 。

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