A benzospirrofluorene compound and an electroluminescent device

Abstract

The application provides a benzo-spirobifluorene compound and an electroluminescent device. The structural formula of the benzo-spirobifluorene compound is shown in general formula (1). The electroluminescent device has high luminous efficiency and long service life by using the benzo-spirobifluorene compound as a guest light-emitting material.

Description

Technical Field

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

[0002] Organic light-emitting diodes, or OLEDs for short, have attracted much attention in the lighting and display fields due to their excellent characteristics such as self-illumination, high brightness, high contrast, flexibility, low energy consumption, and wide viewing angle.

[0003] A typical OLED device usually consists of an anode layer, a hole transport layer, an emissive layer, an electron transport layer, and a cathode layer. Under the influence of an applied voltage, holes injected from the anode layer move to the emissive layer through the hole transport layer, while electrons injected from the cathode layer move to the emissive layer through the electron transport layer, recombine to form excitons, and the exciton energy is transferred to the emissive material, thus causing light emission. The performance of the emissive material in the emissive layer directly determines the overall luminous efficacy and lifespan of the OLED device; therefore, developing high-performance emissive materials has become a key factor driving the development of OLED technology.

[0004] In the spirodifluorene structure, two fluorene rings form a spiro ring by sharing a carbon atom, resulting in a highly rigid and spatially twisted three-dimensional configuration. This structure can significantly reduce energy loss caused by molecular vibration or rotation, and lower the probability of nonradiative transitions. At the same time, the rigid framework can suppress intermolecular π-π stacking, avoiding exciton quenching and fluorescence quenching. Therefore, it is widely used in OLED organic functional layer materials.

[0005] Currently, existing technologies report on spirodifluorene-based compounds and their applications in OLED devices. For example, Chinese patent application CN116655603A proposes a class of spirodifluorene compounds for use as luminescent materials. Although the fabricated devices have low driving voltages, their luminous efficiency and lifetime are still unsatisfactory. Chinese patent CN112424191B proposes a new class of compounds and organic light-emitting devices containing them. These new compounds are used as electron transport materials. Although the lifetime of the fabricated devices is significantly extended, their luminous efficiency is still unsatisfactory.

[0006] It is evident that the currently disclosed spirodifluorene compounds still suffer from unsatisfactory luminous efficiency and lifespan, making it difficult to meet the higher requirements of OLED devices in terms of luminous performance and lifespan. Summary of the Invention

[0007] To address the technical problems of insufficient lifetime and low luminous efficiency of existing luminescent materials, this invention provides a benzospirodifluorene compound and an electroluminescent device.

[0008] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a benzo[a]spirodifluorene compound, the structural formula of which is shown in general formula (1):

[0009] In the formula: For structure A, For structure B, The main structure; In structure B, Z1, Z2, and Z3 are independently selected from C-R0 and N, respectively; when Z1, Z2, and Z3 are all C-R0, at least one of the three R0 groups and R1 and R2 is selected from F, cyano, trifluoromethyl, or diphenylphosphine, and the remaining groups are independently selected from H, F, cyano, trifluoromethyl, or diphenylphosphine; when Z1, Z2, and Z3 are all N, R1 and R2 are phenyl; when one or two of Z1, Z2, and Z3 are N, R0, R1, and R2 are independently selected from H, F, cyano, trifluoromethyl, or diphenylphosphine. In structure A, R3 to R7 are independently selected from H, C1 to C8 alkyl or cycloalkyl, deuterated methyl, deuterated tert-butyl, isopropylphenyl, phenyl, phenanthrene, hydroxyl, dibenzofuranyl, aniline, 2-cyclohexylphenyl, and R3 to R5 are independent of each other or bonded to each other.

[0010] Preferably, structure A is selected from the following groups:

[0011] in," "Indicates the position where structure A is bonded to the C atom in the main structure; only one of A1~A5, A11, A14, and A15 is present." "It bonds with C atoms in the main structure."

[0012] Preferably, structure B is selected from the following groups:

[0013] in," "" indicates the position where structure B is bonded to the C atom in the main structure.

[0014] Preferably, the benzo[a]spirodifluorene compound is selected from one of the following compounds 1 to 72: .

[0015] In a second aspect, 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; the emitting layer comprises a host emitting material and a guest emitting material, wherein the guest emitting material comprises the benzo[a]spirodifluorene compound described in the present invention.

[0016] Preferably, the anode layer is made of indium tin oxide, indium zinc oxide, tin dioxide, or zinc oxide; a material with a high work function is selected to facilitate the injection of holes into the organic layer composed of the hole transport layer, the light-emitting layer, and the electron transport layer.

[0017] Preferably, the cathode layer is made of at least one of magnesium, silver, aluminum, aluminum-lithium, calcium, magnesium-indium, and magnesium-silver. Choosing a material with a low work function facilitates the injection of electrons into the organic layer composed of the hole transport layer, the light-emitting layer, and the electron transport layer.

[0018] Preferably, the hole transport layer can be a single-layer hole transport layer containing only one compound, or it can be a composite hole transport layer containing multiple compounds. The composite hole transport layer is composed of multiple organic hole materials, including a hole injection layer, a hole transport layer, and an electron blocking layer stacked sequentially.

[0019] In this invention, the hole injection layer is preferably a p-doped hole injection layer, which means a hole injection layer doped with a p-doped agent. A p-doped agent is a material that can impart p-type semiconductor characteristics. P-type semiconductor characteristics refer to the characteristics of injecting or transporting holes at the HOMO energy level, that is, having high hole conductivity.

[0020] Preferably, the electron transport layer is a composite electron transport layer, comprising, in sequence, an electron injection layer, an electron transport layer, and a hole blocking layer, wherein the material of the electron transport layer is selected from... , and At least one of them.

[0021] Compared with the prior art, the present invention has the following beneficial effects: First, in the benzo[a]spirodifluorene compound structure of the present invention, the main structure is... The spiro ring formed by the fluorene ring and the benzo[a]fluorene ring sharing carbon atoms has a long conjugated system and a highly rigid and spatially twisted three-dimensional configuration. This structure can reduce the probability of nonradiative transitions. At the same time, the rigid framework can suppress intermolecular π-π stacking, avoid exciton quenching and fluorescence quenching, and improve luminescence efficiency.

[0022] Secondly, the main structure of the present invention As a π-bridge, in the benzospirofluorene group An electron-donating group (structure A) is introduced on the spirofluorene group. An electron-withdrawing group (structure B) is introduced to form a "donor-π bridge-acceptor" (D-π-A) type push-pull electron system. By adjusting the strength of the electron-donating / withdrawing groups, the HOMO-LUMO energy level difference of the molecule can be precisely controlled, which helps to promote the blue shift of the device's emission wavelength and meet the requirements of blue light display.

[0023] Furthermore, the spirocyclic structure of the benzo[a]spirodifluorene of this invention has significant steric hindrance. Combined with the steric effect of the two side groups, it can reduce the aggregation of guest molecules during evaporation or device operation (avoiding crystallization or phase separation), while also reducing undesirable interactions with the host material. This structural stability helps reduce performance degradation of the device during long-term operation and extends the lifespan of the OLED.

[0024] Finally, the electroluminescent device of the present invention uses the aforementioned benzospirodifluorene compound as the guest light-emitting material, and has high luminous efficiency and long service life. Attached Figure Description

[0025] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a cross-sectional view of the electroluminescent device of the present invention.

[0027] Figure 2 The NMR spectrum of compound 1 synthesized in Example 1.

[0028] Figure 3 The NMR spectrum of compound 49 synthesized in Example 2.

[0029] Figure 4 The NMR spectrum of compound 52 synthesized in Example 3.

[0030] Figure 5 The NMR spectrum of compound 54 synthesized in Example 4.

[0031] Figure 6 The NMR spectrum of compound 55 synthesized in Example 5.

[0032] Figure 7 The NMR spectrum of compound 58 synthesized in Example 6.

[0033] 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

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0036] The benzo[a]spirodifluorene compounds represented by general formula (1) of this invention are obtained by substituting structures A and B at different sites of spirodifluorene. Wherein, p1 or p2 is a compound that must participate in the reaction, and q1, q2, or q3 is a compound that must participate in the reaction; structure A is provided by reactant a; structure B is provided by reactant b; reactant a is selected from formulas a1 to a2. 23 At least one of the compounds shown; reactant b is selected from one of the compounds shown in formulas b1 to b9: .

[0037] Example 1 of compound preparation (synthesis of compound 1): The synthetic method and specific synthetic route for benzo[a]spirodifluorene compounds are shown below:

[0038] Step 1, Synthesis of intermediate M1-1: Procedure: Under nitrogen protection, add 0.5 mol of q1 (3'-chloro-2-iodine-1,1'-biphenyl) and 1.5 L of THF to a 5 L three-necked flask. Start stirring and cool the system to -78 °C. Add 313 mL of n-butyllithium (2.0 mol / L) dropwise to the system and maintain the reaction at -78 °C for 1.5 h. Then, slowly add 500 mL of THF solution containing 1.0 mol of reactant p1 dropwise to the above system. After the addition is complete, maintain the reaction at -78 °C for 1.0 h. Allow the reaction system to naturally rise to room temperature and quench with 30 mL of water. The reaction is then complete. Concentrate the reaction solution under reduced pressure to dryness, add 1000 mL of toluene and 500 mL of water, stir, wash with water, and separate the liquid. Wash the organic phase with water until neutral and dry with anhydrous sodium sulfate. Filter and collect the dried organic phase, transfer it to another 5 L three-necked flask, and slowly add 2.0 mol of methanesulfonic acid dropwise while stirring. Continue stirring at room temperature for 1 h until the reaction is complete. Then, 400 mL of water was added to quench the reaction, and 6 N sodium hydroxide solution was slowly added dropwise until the reaction solution was weakly alkaline. The organic phase was separated and washed with water in small amounts several times until neutral. The organic phase was concentrated under reduced pressure and dried. After being dispersed by reflux with 1000 mL of n-heptane, it was cooled to room temperature and filtered. The intermediate M1-1 was obtained by vacuum drying, weighing 187.4 g, with a yield of 78.1%.

[0039] Step 2, Synthesis of intermediate M1: Under nitrogen protection, 0.3 mol of intermediate M1-1, 0.3 mol of pinacol diborate, 0.6 mol of potassium acetate, and 2.0 L of 1,4-dioxane were added to a 5 L three-necked flask. The mixture was stirred and heated to 60 °C, then 3 mmol of Pd(dppf)Cl2 was added. The mixture was then heated to reflux for 8 h until intermediate M1-1 was completely reacted. The reaction solution was directly filtered, and the filtrate was collected, concentrated under reduced pressure, dissolved in 1000 mL of toluene, and washed with water. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated. After passing the organic phase through a silica gel column, the column chromatography solution was concentrated again under reduced pressure until solid precipitates. The solution was then cooled to 10 °C for crystallization, filtered, and dried to obtain intermediate M1, totaling 123.9 g, with a yield of 78.4%. The HPLC purity was 98%, and the LC-MS showed a molecular weight of 527.0.

[0040] Step 3, Synthesis of Intermediate 1-1: Procedure: Under nitrogen protection, 0.2 mol of intermediate M1, 0.2 mol of a1, 4 mmol of Pd(PPh3)4, 0.4 mol of K2CO3, 800 mL of THF, and 200 mL of H2O were added to a 2 L three-necked flask. The system was heated to reflux and reacted for 18 h until the reaction was complete. The reaction solution 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 / dichloromethane = 8:1) to obtain 83.7 g of intermediate 1-1, with a yield of 71.0% and an HPLC purity of 99%.

[0041] Step 4, Synthesis of Intermediates 1-2: The synthesis method of intermediate M1 was similar, but with the following difference: 0.1 mol of intermediate 1-1 was used to replace 0.3 mol of intermediate M1-1 to obtain intermediate 1-2, totaling 52.3 g, with a yield of 76.9% and an HPLC purity of 98%.

[0042] Step 5, Synthesis of Compound 1: The synthesis method for intermediate 1-1 was the same, except that 0.01 mol of intermediate 1-2 was used to replace 0.3 mol of intermediate M1, yielding compound 1, totaling 5.4 g, with a yield of 69.2%, HPLC purity of 99%, and LC-MS showing a molecular weight of 786.1. The NMR spectrum of compound 1 is shown below. Figure 2 As shown.

[0043] 1H NMR data for compound 1: 1H NMR (500 MHz, Chloroform) δ 8.92 (d, J =30.0 Hz, 2H), 8.52 (s, 1H), 8.36 (s, 4H), 8.24 (s, 1H), 7.90 (d, J = 8.0 Hz,2H), 7.76 – 7.45 (m, 12H), 7.40 – 7.11 (m, 7H), 1.31 (d, J = 35.0 Hz, 18H).

[0044] High Performance Liquid Chromatography (HPLC) is the English name for high performance liquid chromatography. Liquid Chromatography-Mass Spectrometry (LC-MS) is the English name for liquid chromatography-mass spectrometry. Pd(dppf)Cl2 is 1,1-bis(diphenylphosphine)ferrocene palladium dichloride. Pd(PPh3)4 is tetrakis(triphenylphosphine)palladium.

[0045] Compound preparation example 2 (synthesis of compound 49): The synthetic method and specific synthetic route for benzo[a]spirodifluorene compounds are shown below:

[0046] Step 1, Synthesis of intermediate M2-1: The synthesis method of intermediate M1-1 in Example 1 was followed, except that 0.5 mol of p1 was replaced with 0.5 mol of p2 to obtain intermediate M2-1, totaling 183.5 g, with a yield of 76.5% and an HPLC purity of 98%.

[0047] Step 2, Synthesis of intermediate M2: The synthesis method of intermediate M1 in Example 1 was followed, except that 0.3 mol of intermediate M1-1 was replaced with 0.3 mol of intermediate M2-1 to obtain intermediate M2, totaling 119.0 g, with a yield of 75.3%, HPLC content of 98%, and LC-MS showing a molecular weight of 527.0.

[0048] Step 3, Synthesis of Intermediate 49-1: The synthesis method of intermediate 1-1 in Example 1 is the same, except that 0.2 mol of intermediate M1 is replaced with 0.2 mol of intermediate M2, and reactant a is used. 13 Replacing reactant a1 yielded intermediate 49-1, totaling 81.3 g, with a yield of 69.2% and an HPLC purity of 98%.

[0049] Step 4, Synthesis of Intermediate 49-2: The synthesis method of intermediate 1-2 in Example 1 was followed, except that 0.1 mol of intermediate 1-1 was replaced with 0.1 mol of intermediate 49-1 to obtain intermediate 49-2, 52.1 g, yield 75.7%, HPLC content 98%.

[0050] Step 5, Synthesis of Compound 49: The synthesis method of compound 1 in Example 1 was followed, with the difference that intermediate 1-2 was replaced by intermediate 49-2, and reactant b2 was replaced by reactant b1, yielding compound 49, totaling 5.5 g, with a yield of 70.4%, HPLC purity of 99%, and LC-MS showing a molecular weight of 783.1. The NMR spectrum of compound 49 is shown below. Figure 3 As shown.

[0051] 1H NMR data for compound 49: 1H NMR (500 MHz, Chloroform ) δ 8.90 (s,1H), 8.47 – 8.40 (m, 2H), 8.23 ​​(s, 1H), 8.16 (s, 1H), 8.01 – 7.86 (m, 6H),7.80 (d, J = 22.4 Hz, 2H), 7.69 – 7.45 (m, 9H), 7.42 (s, 1H), 7.36 – 7.19 (m,5H), 7.10 (d, J = 10.0 Hz, 2H), 1.71 (s, 4H), 0.91 (s, 12H). Compound preparation example 3 (synthesis of compound 52): The synthetic method and specific synthetic route for benzo[a]spirodifluorene compounds are shown below:

[0052] Step 1, Synthesis of intermediate M3-1: The synthesis method of intermediate M1-1 in Example 1 was followed, except that 0.5 mol of q1 was replaced with 0.5 mol of q2 to obtain intermediate M3-1; the total yield was 195.0 g, the yield was 81.3%, and the HPLC content was 98%.

[0053] Step 2, Synthesis of intermediate M3: The synthesis method of intermediate M1 in Example 1 was followed, except that 0.3 mol of intermediate M1-1 was replaced with 0.3 mol of intermediate M3-1 to obtain intermediate M3; the total amount was 124.7 g, the yield was 78.9%, the HPLC content was 98%, and the LC-MS showed a molecular weight of 527.0.

[0054] Step 3, Synthesis of Intermediate 52-1: The synthesis method of intermediate 1-1 in Example 1 is the same, except that 0.2 mol of intermediate M1 is replaced with 0.2 mol of intermediate M3, and compound a is used. 14 Replacing compound a1 yielded intermediate 52-1, totaling 92.0 g, with a yield of 72.4% and an HPLC purity of 98%.

[0055] Step 4, Synthesis of Intermediate 52-2: The synthesis method of intermediate 1-2 in Example 1 was followed, except that 0.1 mol of intermediate 1-1 was replaced with 0.1 mol of intermediate 52-1 to obtain intermediate 52-2, which weighed 57.6 g, with a yield of 79.3% and an HPLC content of 98%.

[0056] Step 5, Synthesis of Compound 52: The synthesis method of compound 1 in Example 1 was followed, with the difference that intermediate 1-2 was replaced by intermediate 52-2, and compound b1 was replaced by compound b2, yielding compound 52, totaling 5.9 g, with a yield of 71.2%, HPLC purity of 99%, and LC-MS showing a molecular weight of 831.2. The NMR spectrum of compound 52 is shown below. Figure 4 As shown.

[0057] 1H NMR data for compound 52: 1H NMR (500 MHz, Chloroform) δ 8.92 (d, J = 30.0 Hz, 2H), 8.23 ​​(d, J = 5.0 Hz, 2H), 8.08 (s, 1H), 7.89 (dd, J = 21.4, 17.8 Hz, 7H), 7.79 (s, 1H), 7.70 (d, J = 20.9 Hz, 3H), 7.62 – 7.44 (m, 9H), 7.43 – 7.28 (m, 3H), 7.28 – 7.09 (m, 6H), 1.69 (s, 12H).

[0058] Compound preparation example 4 (synthesis of compound 54): The synthetic method and specific synthetic route of benzo[a]spirodifluorene compounds are shown below:

[0059] Step 1, Synthesis of intermediate M4-1: The synthesis method of intermediate M1-1 in Example 1 was followed, except that 0.5 mol of p1 was replaced by 0.5 mol of p2 and 0.5 mol of q1 was replaced by 0.5 mol of q2 to obtain intermediate M4-1, totaling 186.2 g, with a yield of 77.6% and an HPLC purity of 98%.

[0060] Step 2, Synthesis of intermediate M4: The synthesis method of intermediate M1 in Example 1 was followed, except that 0.3 mol of intermediate M1-1 was replaced with 0.3 mol of intermediate M4-1 to obtain intermediate M4, totaling 114.0 g, with a yield of 72.1%, HPLC purity of 98%, and LC-MS showing a molecular weight of 527.0.

[0061] Step 3, Synthesis of Intermediate 54-1: The synthesis method of intermediate 1-1 in Example 1 is the same, except that 0.2 mol of intermediate M1 is replaced with 0.2 mol of intermediate M4, and compound a is used. 14Replacing compound a1 yielded intermediate 54-1, totaling 82.7 g, with a yield of 65.1% and an HPLC purity of 99%.

[0062] Step 4, Synthesis of Intermediate 54-2: The synthesis method of intermediate 1-2 in Example 1 was followed, except that 0.1 mol of intermediate 1-1 was replaced with 0.1 mol of intermediate 54-1 to obtain intermediate 54-2, which weighed 56.7 g, with a yield of 78.0% and an HPLC purity of 98%.

[0063] Step 5, Synthesis of Compound 54: The synthesis method of compound 1 in Example 1 was followed, with the difference that intermediate 1-2 was replaced by intermediate 54-2, and compound b2 was replaced by compound b1, yielding compound 54, totaling 5.9 g, with a yield of 72.3%, HPLC purity of 99%, and LC-MS showing a molecular weight of 831.2. The NMR spectrum of compound 54 is shown below. Figure 5 As shown.

[0064] 1H NMR data for compound 54: 1H NMR (500 MHz, Chloroform) δ 8.90 (s, 1H), 8.43 (s, 1H), 8.23 ​​(d, J = 4.6 Hz, 2H), 8.08 (s, 1H), 8.00 – 7.86 (m, 6H), 7.78 (d, J = 3.0 Hz, 2H), 7.68 (t, J = 9.7 Hz, 3H), 7.62 – 7.45 (m, 9H), 7.43– 7.22 (m, 6H), 7.12 (d, J = 31.4 Hz, 3H), 1.69 (s, 12H).

[0065] Compound preparation example 5 (synthesis of compound 55): The synthetic method and specific synthetic route for benzo[a]spirodifluorene compounds are shown below:

[0066] Step 1, Synthesis of intermediate M5-1: The synthesis method of intermediate M1-1 in Example 1 was followed, except that 0.5 mol of q1 was replaced with 0.5 mol of q3 to obtain intermediate M5-1, totaling 159.5 g, with a yield of 66.5% and an HPLC purity of 98%.

[0067] Step 2, Synthesis of intermediate M5: The synthesis method of intermediate M1 in Example 1 was followed, except that 0.3 mol of intermediate M1-1 was replaced with 0.3 mol of intermediate M5-1 to obtain intermediate M5; the total amount was 111.9 g, the yield was 70.8%, the HPLC content was 98%, and the LC-MS showed a molecular weight of 527.0.

[0068] Step 3, Synthesis of Intermediate 55-1: The synthesis method of intermediate 1-1 in Example 1 is the same, except that 0.2 mol of intermediate M1 is replaced with 0.2 mol of intermediate M5, and compound a is used. 13 Replacing compound a1 yielded intermediate 55-1; total yield 79.0 g, yield 67.3%, HPLC purity 99%.

[0069] Step 4, Synthesis of Intermediate 55-2: The synthesis method of intermediates 1-2 in Example 1 was followed, except that 0.1 mol of intermediate 1-1 was replaced with 0.1 mol of intermediate 55-1 to obtain intermediate 55-2: 49.2 g, yield 72.5%, HPLC content 98%.

[0070] Step 5: Synthesis of spirodifluorene compounds: The synthesis method of compound 1 in Example 1 was followed, with the difference that intermediate 1-2 was replaced by intermediate 55-2, and compound b2 was replaced by compound b1, yielding compound 55: 5..g, yield 64.3%, HPLC purity 99%, LC-MS showed a molecular weight of 783.1. The NMR spectrum of compound 55 is shown below. Figure 6 As shown.

[0071] 1H NMR data for compound 55: 1H NMR (500 MHz, Chloroform) δ 8.92 (d, J =30.0 Hz, 2H), 8.41 (s, 1H), 8.23 ​​(d, J = 5.0 Hz, 2H), 7.91 (d, J = 25.0 Hz,5H), 7.80 (s, 1H), 7.72 – 7.63 (m, 4H), 7.59 – 7.44 (m, 7H), 7.33 (t, J = 13.9Hz, 3H), 7.27 – 7.07 (m, 5H), 1.71 (s, 4H), 0.91 (s, 12H).

[0072] Compound preparation example 6 (synthesis of compound 58): The synthetic method and specific synthetic route for benzo[a]spirodifluorene compounds are shown below:

[0073] Step 1: Synthesis of intermediate M6-1: The synthesis method of intermediate M1-1 in Example 1 was followed, except that 0.5 mol of p1 was replaced by 0.5 mol of p2 and 0.5 mol of q1 was replaced by 0.5 mol of q3 to obtain intermediate M6-1, totaling 169.8 g, with a yield of 70.8% and an HPLC purity of 98%.

[0074] Step 2, Synthesis of intermediate M6: The synthesis method of intermediate M1 in Example 1 was followed, except that 0.3 mol of intermediate M1-1 was replaced with 0.3 mol of intermediate M6-1 to obtain intermediate M6, totaling 119.2 g, with a yield of 73.6%, an HPLC purity of 98%, and a molecular weight of 527.0 as shown by LC-MS.

[0075] Step 3, Synthesis of Intermediate 58-1: The synthesis method of intermediate 1-1 in Example 1 is the same, except that 0.2 mol of intermediate M1 is replaced with 0.2 mol of intermediate M6, and compound a is used. 14 Replacing compound a1 yielded intermediate 58-1, totaling 90.5 g, with a yield of 71.2% and an HPLC purity of 99%.

[0076] Step 4, Synthesis of Intermediate 58-2: The synthesis method of intermediate 1-2 in Example 1 was followed, except that 0.1 mol of intermediate 1-1 was replaced with 0.1 mol of intermediate 58-1 to obtain intermediate 58-2, which weighed 54.2 g, with a yield of 74.6% and an HPLC purity of 98%.

[0077] Step 5, Synthesis of Compound 58: The synthesis method of compound 1 in Example 1 was followed, with the difference that intermediate 1-2 was replaced by intermediate 58-2, and compound b2 was replaced by compound b1, yielding compound 58, totaling 5.5 g, with a yield of 65.9%, HPLC purity of 99%, and LC-MS showing a molecular weight of 831.4. The NMR spectrum of compound 58 is shown below. Figure 7 As shown.

[0078] 1H NMR data for compound 58: 1H NMR (500 MHz, Chloroform) δ 8.90 (s, 1H), 8.43 (s, 1H), 8.24 (d, 1H) J= 11.8 Hz, 2H), 8.17 (s, 1H), 8.00 – 7.75 (m, 9H), 7.70 – 7.45 (m, 10H), 7.43 – 7.20 (m, 6H), 7.12 (d, J = 31.4 Hz, 3H), 6.06 (s, 1H), 1.69 (s, 12H).

[0079] The synthesis of other compounds follows the same method as the above compounds, except that the corresponding reactants p (p1, p2), q (q1~q3), and reactant a (a1~a2) are used. 25 The reactants b (b1~b9) can be replaced. The reactant composition of some compounds in this invention is shown in Table 1.

[0080] Table 1

[0081] Electroluminescent devices were fabricated using benzo[a]spirodifluorene compounds as guest luminescent materials. A schematic diagram of the electroluminescent device is shown below. Figure 1 As shown, the device includes a substrate 1 and, sequentially stacked on the substrate 1, 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. The electroluminescent device is fabricated using currently recognized device fabrication technology in the industry.

[0082] The structures of some of the materials used in the fabrication of electroluminescent devices are as follows:

[0083] Example 1 The method for fabricating an electroluminescent device includes the following steps: Under high vacuum conditions, on the cleaned conductive glass, indium tin oxide with a thickness of 25 nm was sequentially deposited as an anode layer 2, a mixture of compounds of formula HT-1 and formula P-1 with a thickness of 10 nm (mass ratio of 97:3) as a hole injection layer 3, HT-1 with a thickness of 50 nm as a hole transport layer 4, and EB-1 with a thickness of 10 nm as an electron blocking layer 5. After the electron blocking layer 5 was deposited, a light-emitting layer 6 with a thickness of 30 nm was deposited. The light-emitting layer 6 used PH-2 as the host light-emitting material and prepared compound 1 synthesized in Example 1 as the guest light-emitting material, and the mass ratio of the host light-emitting material to the guest light-emitting material was 97:3. A hole-blocking layer 7 with a thickness of 16 nm, an electron transport layer 8 with a thickness of 25 nm, an 8-hydroxyquinoline lithium layer with a thickness of 10 nm, and an Al electrode layer with a thickness of 50 nm are sequentially deposited on the light-emitting layer 6. Finally, a cover layer material X is deposited as a cover layer and encapsulated to obtain an electroluminescent device, denoted as Ex.1.

[0084] Example 2 The preparation method of the electroluminescent device is basically the same as that of Example 1, except that: PH-2 is used as the host luminescent material and compound 1 is used as the guest luminescent material in the luminescent layer 6, and the mass ratio of the host luminescent material to the guest luminescent material is 99:1, thus obtaining the electroluminescent device, denoted as Ex.2.

[0085] Example 3 The preparation method of the electroluminescent device is basically the same as that of Example 1, except that: PH-2 is used as the host luminescent material and compound 1 is used as the guest luminescent material in the luminescent layer 6, and the mass ratio of the host luminescent material to the guest luminescent material is 98:2, thus obtaining the electroluminescent device, denoted as Ex.3.

[0086] Examples 4-40 The preparation method of the electroluminescent device is basically the same as that of Example 1, except that the compounds in Table 2 below are used as guest luminescent materials in sequence; and the mass ratio of host luminescent material to guest luminescent material is 98:2, and the electroluminescent devices are obtained, which are denoted as Ex.4 to Ex.40 respectively.

[0087] Table 2

[0088] Comparative Example 1 The method for fabricating an electroluminescent device includes the following steps: Under high vacuum conditions, on the cleaned conductive glass, a 25 nm thick indium tin oxide layer is deposited sequentially as an anode layer 2, a 10 nm thick mixture of HT-1 and P-1 (mass ratio of 97:3) as a hole injection layer 3, a 50 nm thick HT-1 as a hole transport layer 4, and a 10 nm thick EB-1 as an electron blocking layer 5. After the electron blocking layer 5 is deposited, a 30 nm thick light-emitting layer 6 is deposited. The light-emitting layer 6 uses PH-2 as the host light-emitting material and compound E-4 from Chinese patent application CN116655603A as the guest light-emitting material, with a mass ratio of host light-emitting material to guest light-emitting material of 98:2. A 16 nm thick HB-1 layer as a hole blocking layer 7, a 25 nm thick E1 layer as an electron transport layer 8, a 10 nm thick lithium 8-hydroxyquinoline layer as an electron injection layer 9, and a 50 nm thick Al electrode layer as a cathode layer 10 are sequentially deposited on the light-emitting layer 6. Finally, a capping layer material X is deposited as a capping layer, and the device is encapsulated to obtain the electroluminescent device, denoted as Pro.1. The following is a description of a device fabricated using this method: Figure 1 The electroluminescent device shown.

[0089] Comparative Example 2 The preparation method of the electroluminescent device is basically the same as that of Comparative Example 1, except that the light-emitting layer is different. The light-emitting layer uses PH-2 as the main light-emitting material and compound E-8 from Chinese patent application with publication number CN116655603A as the guest light-emitting material to obtain the electroluminescent device, denoted as Pro.2.

[0090] Comparative Example 3 The preparation method of the electroluminescent device is basically the same as that of Comparative Example 1, except that the light-emitting layer is different. The light-emitting layer uses PH-2 as the main light-emitting material and compound E12 from Chinese Patent No. CN116655603A as the guest light-emitting material to obtain the electroluminescent device, denoted as Pro.3.

[0091] Comparative Example 4 The above-described embodiments and the preparation method of the electroluminescent device are basically the same as the preparation method of Comparative Example 1, except that the light-emitting layer is different. The light-emitting layer uses PH-2 as the main light-emitting material and compound A-7 from the Korean patent application with publication number KR1020150030300A as the guest light-emitting material to obtain the electroluminescent device, referred to as Pro.4.

[0092] The electroluminescent device in the comparative example was fabricated as a 30 mm × 30 mm sample. Then, under the same device fabrication process conditions, the anode and cathode layers were connected using an industry-known driving circuit to characterize the OLED. The test results are shown in Table 3.

[0093] Table 3 Performance data of the electroluminescent devices prepared in the comparative examples and embodiments

[0094] Note: The current density during the test was 15 mA / cm². 2 EQE refers to the external quantum efficiency of a device, and lifetime T95 refers to the time it takes for the device's brightness to decay to 95% of its initial brightness.

[0095] As can be seen from the data in Table 3, compared with the electroluminescent devices prepared using Comparative Examples 1 to 4 in the prior art as guest light-emitting materials, the electroluminescent devices prepared using the benzospirodifluorene compounds synthesized in the preparation examples of this invention as guest light-emitting materials have significantly longer lifespans and significantly improved external quantum efficiency.

[0096] Table 3 also shows that, compared to the electroluminescent devices prepared using Comparative Examples 1-3 in the prior art as guest luminescent materials, the electroluminescent devices prepared using the benzospirofluorene compounds synthesized in this invention as guest luminescent materials exhibit a significant blue shift in emission wavelength (with most devices emitting wavelengths concentrated in the 460nm-470nm range, which falls within the blue light range). This indicates that the benzospirofluorene group... An electron-donating group (structure A) is introduced on the spirofluorene group. By introducing electron-withdrawing groups (structure B) to form a "donor-π bridge-acceptor" (D-π-A) type push-pull electron system, the HOMO-LUMO energy level difference of the molecule can be precisely controlled by adjusting the strength of the electron-donating / withdrawing groups, which helps to promote the blue shift of the device's emission wavelength and meet the requirements of blue light display.

[0097] The data from the electroluminescent devices Ex.1 to Ex.3 show that when the mass of the guest light-emitting material in the light-emitting layer is in the range of 1% to 3%, the overall luminous efficiency of the electroluminescent devices is similar; when the mass of the guest light-emitting material is 2%, the luminous performance of the electroluminescent device prepared is slightly better than that of Example 1 and Example 2.

[0098] In summary, when the benzo[a]spirodifluorene compounds described in this invention are used as guest luminescent materials in the luminescent layer of OLEDs, they can effectively improve the luminous efficiency and lifespan of OLED devices.

[0099] 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.

[0100] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A benzospirodifluorene compound, characterized in that, The structural formula of the benzo[a]spirodifluorene compounds is shown in general formula (1): In the formula: For structure A, For structure B, The main structure; In structure B, Z1, Z2, and Z3 are independently selected from C-R0 and N, respectively; when Z1, Z2, and Z3 are all C-R0, at least one of the three R0 groups and R1 and R2 is selected from F, cyano, trifluoromethyl, and diphenylphosphine, and the remaining groups are independently selected from H, F, cyano, trifluoromethyl, and diphenylphosphine; when Z1, Z2, and Z3 are all N, R1 and R2 are phenyl; when one or two of Z1, Z2, and Z3 are N, R0, R1, and R2 are independently selected from H, F, cyano, trifluoromethyl, and diphenylphosphine, respectively. In structure A, R3 to R7 are independently selected from H, C1 to C8 alkyl or cycloalkyl, deuterated methyl, deuterated tert-butyl, isopropylphenyl, phenyl, phenanthrene, hydroxyl, dibenzofuranyl, aniline, 2-cyclohexylphenyl, and R3 to R5 are independent of each other or bonded to each other.

2. The benzo[a]spirodifluorene compound according to claim 1, characterized in that, The structure A is selected from the following groups: in," "Indicates the position where structure A is bonded to the C atom in the main structure; only one of A1~A5, A11, A14, and A15 can be present." "It bonds with C atoms in the main structure." 3. The benzo[a]spirodifluorene compound according to claim 1, characterized in that, The structure B is selected from the following groups: in," "" indicates the position where structure B is bonded to the C atom in the main structure.

4. The benzo[a]spirodifluorene compound according to claim 1, characterized in that, The benzospirodifluoride compounds are selected from the following compounds 1 to 72: 。 5. An electroluminescent device, characterized in that, The electroluminescent device comprises an anode layer, a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode layer stacked sequentially; the light-emitting layer comprises a host light-emitting material and a guest light-emitting material, wherein the guest light-emitting material comprises a benzospirodifluorene 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 luminescent material is 1% to 3% of the mass of the luminescent layer.

7. The electroluminescent device according to claim 6, characterized in that, The host luminescent material is selected from the following compounds: 、 、 、 、 。 8. The electroluminescent device according to claim 6, characterized in that, The material selection of the electron transport layer , and At least one of them.

9. The electroluminescent device according to claim 6, characterized in that, The anode layer is made of indium tin oxide, indium zinc oxide, tin dioxide, or zinc oxide.

10. The electroluminescent device according to claim 6, characterized in that, The cathode layer is made of at least one of magnesium, silver, aluminum, aluminum-lithium, calcium, magnesium-indium, and magnesium-silver.

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