Spirobifluorene carbazole derivative and organic electroluminescent device

Abstract

The invention belongs to the technical field of organic luminescent materials and semiconductors, and particularly relates to a spirobifluorene carbazole derivative and an organic electroluminescent device. The structural general formula of the spirobifluorene carbazole derivative is as shown in formula 1. According to the spirobifluorene carbazole derivative provided by the invention, spirobifluorene carbazole is taken as a mother nucleus, and electron donating and electron withdrawing groups are introduced, so that the compound has relatively good front line orbital energy level and triplet state energy, and meanwhile, the quantum yield of molecules is increased; when the compound is used as a main luminescent material in an organic electroluminescent device, the thermal performance of the material can be adjusted, the luminous efficiency of the device is remarkably improved, the light color is improved, and the service life is prolonged.

Description

Technical Field

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

[0002] Organic light-emitting diodes (OLEDs), with their superior characteristics such as self-emission, high brightness, wide color gamut, low power consumption, and flexibility, have shown broad application prospects in flat panel displays, lighting, and other fields, and have become one of the core research directions in the field of display and lighting technology. A typical OLED device generally consists of an anode, a cathode, and organic functional layers located between them, including a hole functional layer (including an injection layer and a transport layer), an emissive layer (EML), and an electron functional layer (including a transport layer and an injection layer). Among these, the emissive layer is the core functional layer that realizes electroluminescence, and its performance directly determines the luminous efficiency, color purity, and lifespan of the OLED device.

[0003] In the luminescent layer, the host material plays a crucial role in transporting charge carriers (holes or electrons), dispersing the luminescent guest material, and restricting exciton recombination at the guest material. Based on carrier transport characteristics, host materials can be categorized into hole-based host materials and electron-based host materials. Hole-based host materials must possess excellent hole transport capabilities and an energy level structure that matches the guest luminescent material and adjacent functional layers (hole transport layer and electron transport layer). They must also meet high thermal and chemical stability requirements to ensure efficient carrier transport and recombination, thereby improving the overall device performance.

[0004] However, some traditional hole-based host materials in existing technologies (such as triarylamine derivatives and monocarbazole derivatives) have low hole mobility, resulting in poor carrier transport efficiency and difficulty in improving device luminous efficiency. Other materials have low thermal decomposition temperatures and poor chemical stability, making them prone to degradation during long-term device operation, which leads to shortened device lifespan and increased operating voltage. In addition, some materials have insufficient energy level matching with guest luminescent materials or adjacent functional layers, affecting effective exciton recombination and balanced carrier injection. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a spirodifluoren-carbazole derivative and an organic electroluminescent device. This invention uses a spirodifluoren-carbazole derivative as the primary luminescent material in the luminescent layer, exhibiting high carrier transport performance, suitable triplet energy, and excellent thermal stability. This improves the external quantum efficiency of the device, extends its lifespan, enhances its color, and better matches the energy levels of adjacent energy layers, thereby increasing the device's luminous efficiency. It is a high-performance organic electroluminescent material.

[0006] The first objective of this invention is to provide a spirodifluoren-carbazole derivative, the general structural formula of which is shown in Formula 1: .

[0007] R1 and R2 are independently selected from H, D, cyano, trifluoromethyl, substituted or unsubstituted C6~C20 aryl, substituted or unsubstituted C6~C20 heteroaryl, respectively. The substituents on the aryl or heteroaryl are selected from F atom, D atom, cyano or trifluoromethyl, and the heteroatom in the heteroaryl is selected from N, O or S.

[0008] Ra is selected from one of methyl, methoxy, tert-butyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, wherein the substituent on the aryl or heteroaryl is a D atom, methyl, methoxy, tert-butyl, phenyl or diphenylamino, and the heteroatom in the heteroaryl is N, O, S or Si.

[0009] Furthermore, in R1 and R2, the aryl or heteroaryl group is selected from one of the following groups: .

[0010] In this context, "*" represents a bonding site.

[0011] Furthermore, in Ra, the aryl or heteroaryl group is selected from one of the following groups: .

[0012] in," " is the bonding site.

[0013] Furthermore, the spirodifluorenocarbazole derivatives are selected from one of the following compounds: .

[0014] The second objective of this invention is to provide an organic electroluminescent device, which includes an anode layer, a cathode layer, and an organic layer disposed between the anode layer and the cathode layer; the organic layer, along the direction from the anode layer to the cathode layer, consists of, from bottom to top, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, and an electron injection layer; the organic light-emitting layer is prepared from a first host light-emitting material, a second host light-emitting material, and a guest light-emitting material; the first host light-emitting material includes the aforementioned spirodifluorenazole-carbazole derivatives.

[0015] Furthermore, the mass ratio of the first main luminescent material to the second main luminescent material is 3-6:4-7, and the mass ratio of the main luminescent material to the guest luminescent material is 100:0.2-0.5.

[0016] In this invention, the main body of the organic light-emitting layer adopts a composite main body structure mode, which is formed by co-evaporation of a first main light-emitting material and a second main light-emitting material. As a preferred embodiment of this invention, the mass ratio of the first main light-emitting material and the second main light-emitting material is 6:4; the mass ratio of the main light-emitting material to the guest light-emitting material is 100:0.5.

[0017] In a preferred embodiment, a substrate layer is provided below the anode layer or above the cathode layer, which has the characteristics of high mechanical strength, excellent thermal stability, excellent water resistance and excellent transparency. As a preferred embodiment of the present invention, the substrate layer is made of polyethylene terephthalate (PET) plastic.

[0018] In this invention, the anode layer can be made by sputtering or depositing a specific functional layer material on the substrate layer. This material can be a transparent conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), or any combination thereof. The cathode layer can be a metallic element or alloy with good conductivity. Preferred metallic materials include magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), or any combination thereof.

[0019] In this invention, the organic layer can be formed on the electrode by various methods such as vacuum thermal evaporation, spin coating, inkjet printing, etc. The compound used as the organic functional layer can be a small organic molecule, a large organic molecule, an organic polymer, or a combination thereof.

[0020] Furthermore, the second host luminescent material is selected from one of the following compounds: .

[0021] Furthermore, the guest luminescent material is selected from one of the following compounds: .

[0022] A third object of the present invention is to provide a display panel including the aforementioned organic electroluminescent device. The substrate layer can serve as a substrate for a display, and a specific display image formed by embedding thin-film transistors (TFTs) and combinations of TFTs can be fabricated on the substrate.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The spirodifluoren-carbazole derivatives provided by this invention use spirodifluoren-carbazole as the parent core. The sp³ hybridization of the central carbon of the spirocyclic ring constructs a highly distorted non-planar three-dimensional structure, which can effectively suppress the tight π-π stacking between molecules. At the same time, this rigid three-dimensional structure can effectively suppress molecular crystallization, endowing the material with extremely high thermal and morphological stability, thereby extending the device's operating life. Carbazole, as an electron-rich aromatic heterocycle, has a high electron density, which can improve the HOMO energy level of the molecule, giving the material efficient hole injection and transport characteristics. Furthermore, a series of donor and acceptor groups are introduced into the parent core structure to construct an intramolecular charge transfer system of "donor-spirobridge-acceptor". On the one hand, this improves the HOMO energy level of the molecule and reduces the device's start-up voltage. On the other hand, it moderately reduces the LUMO energy level, allowing it to better match with adjacent energy levels and enhance the device's luminous efficiency. On the other hand, it promotes the meeting and recombination of electrons and holes within the molecule (or at the host-guest interface), thereby achieving carrier transport balance, avoiding exciton quenching interfaces, and effectively alleviating the efficiency roll-off problem of the device at high brightness.

[0024] The spirodifluoren-carbazole derivatives provided by this invention have a wide bandgap and high triplet energy level. Through reasonable substituent design, the singlet energy level and carrier injection performance can be adjusted without significantly reducing the triplet energy level of the main body, preventing energy dissipation in the main body in a non-radiative form, achieving effective exciton confinement, and thus improving the external quantum efficiency of the device.

[0025] This invention uses spirodifluorenylcarbazole derivatives as the primary luminescent material to prepare organic electroluminescent devices. It can adjust the thermal properties of the material and significantly improve the overall luminous efficiency, including a significantly lower driving voltage, an increase in external quantum efficiency of about 50%, improved light color, and extended lifespan. Attached Figure Description

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

[0027] Figure 2 This is the NMR spectrum of compound 2 of the present invention.

[0028] Figure 3 This is the NMR spectrum of compound 5 of the present invention.

[0029] Figure 4 This is the NMR spectrum of compound 10 of the present invention.

[0030] Figure 5 This is the NMR spectrum of compound 13 of the present invention.

[0031] Figure 6 The NMR spectrum of compound 26 of this invention is shown.

[0032] Figure label: 01-Substrate layer, 02-Anode layer, 03-Hole injection layer, 04-Hole transport layer, 05-Light emission layer, 06-Electron transport layer, 07-Electron injection layer, 08-Cathode layer. Detailed Implementation

[0033] 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.

[0034] It should be noted that the following embodiments use conventional instruments and equipment in the art. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Process equipment or apparatus in the following embodiments, unless otherwise specified, are all conventional equipment or apparatus in the art. All raw materials used in the following embodiments are conventional commercially available products with specifications in the art.

[0035] This invention uses spirodifluoren-carbazole as the parent core and substitutes it by introducing electron-donating and electron-withdrawing groups. A series of donor and acceptor groups are introduced into the parent core structure to construct an intramolecular charge transfer system of "donor-spirobridge-acceptor," yielding spirodifluoren-carbazole derivatives. The reactants involved include: .

[0036] It should be noted that the English name for high performance liquid chromatography is High Performance Liquid Chromatography, abbreviated as HPLC; and the English name for liquid chromatography-mass spectrometry is Liquid Chromatograph-Mass Spectrometer, abbreviated as LC-MS.

[0037] Example 1 The synthetic route for the spirodifluoren-carbazole derivative (compound 2) is shown below: .

[0038] Step 1: Synthesis of Intermediate 2-1: Under nitrogen protection, 1,4-dibromo-2,3-difluorobenzene (27.0 g, 0.1 mol), 3-iodo-9H-carbazole (58.6 g, 0.2 mol), Cs₂CO₃ (65.2 g, 0.2 mol), and 1000 mL LDMF (N,N-dimethylformamide) were added to a 2000 mL three-necked flask. Stirring was started, and the system was refluxed at 100 °C for 12 h until the reaction was complete. After cooling to room temperature, the mixture was filtered, and the filtrate was collected. A large amount of water was added, and a product precipitated. The product was then filtered again, and the filter cake was washed several times with methanol. The filter cake was collected to obtain the crude product. The crude product was purified by silica gel column chromatography (petroleum ether / dichloromethane = 8:1, v / v) to obtain 69.4 g of intermediate 2-1, with a yield of 85%. The HPLC purity was 97%, and the molecular weight was 817.8 as shown by LC-MS.

[0039] Step 2, Synthesis of Intermediate 2-2: Under nitrogen protection, intermediate 2-1 (40.9 g, 0.05 mol), reactant a5 (14.4 g, 0.1 mol), K2CO3 (18.0 g, 0.13 mol), Pd(PPh3)4 (1.2 g, 1 mmol), 400 mL THF (tetrahydrofuran), and 100 mL H2O were added to a 1000 mL three-necked flask. The system was heated to reflux for 5 h until the reaction was complete. The reaction solution was extracted with toluene, washed with water, and separated. The organic phase was filtered through diatomaceous earth, and the filtrate was collected and concentrated under reduced pressure to obtain a crude solid. The crude product was purified by silica gel column chromatography (petroleum ether / dichloromethane = 10:1, v / v) to obtain 28.6 g of intermediate 2-2, with a yield of 75%. The HPLC purity was 98%, and the molecular weight was 762.1 as shown by LC-MS.

[0040] Step 3, Synthesis of Intermediate 2-3: Under nitrogen protection, intermediate 2-2 (38.1 g, 0.05 mol) and 400 mL of tetrahydrofuran were added to a 1000 mL three-necked flask. Stirring was started to clarify the system. The reaction system was cooled to -78℃ to -85℃, and then 2.5 M n-butyllithium in n-hexane solution (240 mL, 0.06 mol) was slowly added dropwise. The mixture was stirred at -78℃ for 1 h. Then, 2-bromofluorenone (12.9 g, 0.05 mol) was added, and the mixture was stirred overnight at room temperature. After the reaction was complete, the reaction was quenched with saturated NH4Cl solution, extracted with ethyl acetate, and the organic phase was washed with water. The combined organic phases were dried over anhydrous sodium sulfate, filtered, and concentrated to obtain the residue. The residue was recrystallized from methanol. After filtration, it was dissolved in 150 mL of acetic acid solution, and then 5 mL of hydrochloric acid was added. The system was heated to 100℃ and reacted for 6 h. After the reaction was completed, the reaction solution was cooled to room temperature, and 450 mL of ice water was added to precipitate the product. The product was then filtered to obtain the crude product. The crude product was purified by silica gel column chromatography (petroleum ether: dichloromethane = 10:1, volume ratio) to obtain 32.5 g of intermediate 2-3, with a yield of 70.3%. The HPLC purity was 98%, and the LC-MS showed a molecular weight of 924.1.

[0041] Step 4: Synthesis of Intermediate 2-4: Under nitrogen protection, intermediate 2-3 (27.7 g, 0.03 mol), tri-tert-butylphosphine tetrafluoroborate (0.09 g, 0.3 mmol), K₂CO₃ (12.4 g, 0.09 mol), Pd(OAc)₂ (0.1 g, 0.6 mmol), and 300 mL of DMAC (N,N-dimethylacetamide) were added to a 1000 mL three-necked flask. The system was heated to 160 °C and refluxed for 10 h until the reaction was complete. The reaction solution was cooled to room temperature, extracted with toluene, washed with water, and separated. The organic phase was filtered through diatomaceous earth, and the filtrate was collected and concentrated under reduced pressure to obtain a crude solid. The crude product was purified by silica gel column chromatography (petroleum ether / dichloromethane = 8:1, v / v) to obtain 16.4 g of intermediate 2-4, with a yield of 65%. The HPLC purity was 98%, and the molecular weight was 842.2 as shown by LC-MS.

[0042] Step 5: Synthesis of spirodifluoren-carbazole derivatives (compound 2): Under nitrogen protection, intermediate 2-4 (25.3 g, 0.03 mol), reactant b3 (4.9 g, 0.03 mol), K2CO3 (11.1 g, 0.08 mol), Pd(PPh3)4 (0.7 g, 0.6 mmol), 320 mL THF, and 80 mL H2O were added to a 1000 mL three-necked flask. The system was heated to 65 °C and refluxed for 5 h until the reaction was complete. The reaction solution was extracted with toluene, washed with water, and separated. The organic phase was filtered through diatomaceous earth, and the filtrate was collected and concentrated under reduced pressure to obtain a crude solid. The crude product was purified by silica gel column chromatography (petroleum ether / dichloromethane = 15:1, v / v) to obtain 20.2 g of compound 2, with a yield of 76.3%. The HPLC purity was 98%, and the molecular weight was 882.3 as shown by LC-MS.

[0043] The 1H NMR data of compound 2 are as follows Figure 2 As shown: 1 H NMR (500 MHz, DMSO- d 6 ) δ 8.21 (d, J =5.1 Hz, 2H), 8.11 (s, 1H), 8.06 (d, J = 0.8 Hz, 2H), 8.02 (d, J = 13.1 Hz, 3H),7.97 (s, 1H), 7.72 (s, 1H), 7.64 (s, 1H), 7.62 – 7.52 (m, 5H), 7.44 – 7.36(m, 3H), 7.34 (s, 1H), 7.26 (dd, J = 7.6, 2.2 Hz, 3H), 7.11 (d, J = 1.9 Hz, 1H), 4.43 (s, 2H), 3.18 (d, J = 1.1 Hz, 1H), 3.08 (d, J = 1.0 Hz, 1H).

[0044] Example 2 The synthetic route for the spirodifluoren-carbazole derivative (compound 5) is shown below: .

[0045] Step 1, Synthesis of Intermediate 5-1: The synthesis method of 1,4-dibromo-2,3-difluorobenzene to 2-1 in Example 1 was followed, except that 3-iodo-9H-carbazole (58.6 g, 0.2 mol) was replaced with 4-(trifluoromethyl)-9H-carbazole (47.0 g, 0.2 mol), yielding 59.9 g of intermediate 5-1, with a yield of 85.6%, HPLC purity of 97%, and LC-MS showing a molecular weight of 701.9.

[0046] Step 2, Synthesis of Intermediate 5-2: Refer to the synthesis method of intermediates 2-2 to 2-3 in Example 1, except that intermediate 2-2 (38.1 g, 0.05 mol) is replaced with intermediate 5-1 (35.1 g, 0.05 mol), resulting in 30.2 g of intermediate 5-2, with a yield of 70%, HPLC purity of 98%, and LC-MS showing a molecular weight of 864.0.

[0047] Step 3, Synthesis of Intermediate 5-3: Refer to the synthesis method of intermediates 2-3 to 2-4 in Example 1, except that intermediate 2-3 (27.7 g, 0.03 mol) was replaced with intermediate 5-2 (25.9 g, 0.03 mol), yielding 14.6 g of intermediate 5-3, with a yield of 62.3%, HPLC purity of 98%, and LC-MS showing a molecular weight of 782.1.

[0048] Step 4: Synthesis of spirodifluoren-carbazole derivatives (compound 5): Under nitrogen protection, 5-3 (23.5 g, 0.03 mol), b2 (6.8 g, 0.04 mol), S-phos (1.2 g, 3 mmol), sodium tert-butoxide (8.6 g, 0.09 mol), and 300 mL of toluene were added to a 1000 mL three-necked flask. The mixture was stirred until the solution was clear, and then Pd2(dba)3 (1.4 g, 1.5 mmol) was added. The temperature was raised to 110℃~120℃ and the reaction was continued for 3 hours. After the reaction was completed, the mixture was filtered with diatomaceous earth while hot. The filtrate was cooled to room temperature, washed with purified water, separated, and the organic phase was retained. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined, dried with anhydrous sodium sulfate, concentrated, and column filtered (petroleum ether / dichloromethane = 10:1, volume ratio) to obtain compound 5, weighing 22.2 g, with a yield of 85%, an HPLC purity of 98%, and a molecular weight of 871.2 as shown by LC-MS.

[0049] The 1H NMR data of compound 5 are as follows Figure 3 As shown: 1 H NMR (500 MHz, DMSO- d 6 ) δ 8.22 (s,1H), 8.17 (s, 1H), 8.07 (d, J= 17.3 Hz, 2H), 8.01 (s, 1H), 7.83 (s, 1H), 7.65(d, J = 4.4 Hz, 2H), 7.57 (d, J = 2.9 Hz, 2H), 7.54 (d, J = 5.1 Hz, 3H), 7.50 (s,1H), 7.42 – 7.19 (m, 14H), 7.15 – 7.06 (m, 3H).

[0050] Example 3 The synthetic route for the spirodifluoren-carbazole derivative (compound 10) is shown below: .

[0051] Step 1, Synthesis of intermediate 10-1: The synthesis method of 1,4-dibromo-2,3-difluorobenzene to 2-1 in Example 1 was followed, except that 3-iodo-9H-carbazole (58.6 g, 0.2 mol) was replaced with 4-iodo-9H-carbazole (58.6 g, 0.2 mol). 71.0 g of intermediate 10-1 was obtained, with a yield of 87%, HPLC purity of 97%, and LC-MS showing a molecular weight of 817.8.

[0052] Step 2, Synthesis of Intermediate 10-2: Refer to the synthesis method of intermediates 2-1 to 2-2 in Example 1, except that: intermediate 2-1 (40.9g, 0.05mol) was replaced with intermediate 10-1 (40.9g, 0.05mol), and reactant a9 (12.4g, 0.1mol) was replaced with reactant a9 (14.4g, 0.1mol) to obtain intermediate 10-2 totaling 27.2g, yield 75.3%, HPLC purity 98%, LC-MS showed molecular weight 722.0.

[0053] Step 3, Synthesis of Intermediate 10-3: Refer to the synthesis method of intermediates 2-2 to 2-3 in Example 1, except that intermediate 2-2 (38.1 g, 0.05 mol) is replaced with intermediate 10-2 (36.1 g, 0.05 mol), resulting in 31.4 g of intermediate 10-3, with a yield of 71%, HPLC purity of 98%, and LC-MS showing a molecular weight of 884.1.

[0054] Step 4, Synthesis of Intermediate 10-4: Refer to the synthesis method of intermediates 2-3 to 2-4 in Example 1, except that intermediate 2-3 (27.7 g, 0.03 mol) is replaced with intermediate 10-3 (26.5 g, 0.03 mol), yielding 15.7 g of intermediate 10-4, with a yield of 65.3%, HPLC purity of 98%, and LC-MS showing a molecular weight of 804.2.

[0055] Step 5, Synthesis of spirodifluoren-carbazole derivative (compound 10): The synthesis method of intermediate 5-3 to compound 5 in Example 2 was followed, except that intermediate 5-3 (23.5 g, 0.03 mol) was replaced with intermediate 10-4 (24.1 g, 0.03 mol), and reactant b7 (9.0 g, 0.04 mol) was replaced with reactant b2 (6.8 g, 0.04 mol) to obtain 24.7 g of compound 10, with a yield of 87%, HPLC purity of 98%, and LC-MS showing a molecular weight of 947.3.

[0056] The 1H NMR data of compound 10 are as follows Figure 4 As shown: 1 H NMR (500 MHz, DMSO- d 6 ) δ 9.07 (s,2H), 8.64 (d, J = 6.4 Hz, 4H), 8.22 (s, 1H), 8.09 – 8.03 (m, 3H), 8.01 (s, 1H), 7.89 (d, J = 12.8 Hz, 2H), 7.82 (s, 1H), 7.72 (d, J = 15.2 Hz, 2H), 7.56 – 7.49 (m, 4H), 7.42 – 7.25 (m, 10H), 7.20 (s, 1H), 7.12-7.08 (m, 2H), 6.88 (dd, J =7.5, 2.0 Hz, 1H), 6.80 (dd, J = 7.5, 2.0 Hz, 1H), 0.54 (s, 6H).

[0057] Example 4 The synthetic route for the spirodifluoren-carbazole derivative (compound 13) is shown below: .

[0058] Step 1, Synthesis of intermediate 13-1: Following the synthesis method of 1,4-dibromo-2,3-difluorobenzene to 2-1 in Example 1, 72.8 g of intermediate 13-1 was obtained, with a yield of 89.3%, HPLC purity of 97%, and LC-MS showing a molecular weight of 817.8.

[0059] Step 2, Synthesis of Intermediate 13-2: Refer to the synthesis method of intermediates 2-1 to 2-2 in Example 1, except that: intermediate 2-1 (40.9g, 0.05mol) was replaced with intermediate 13-1 (40.9g, 0.05mol), and reactant a14 (16.3g, 0.1mol) was replaced with reactant a5 (14.4g, 0.1mol) to obtain 30.0g of intermediate 13-2, with a yield of 75.1%, HPLC purity of 98%, and LC-MS showing a molecular weight of 800.0.

[0060] Step 3, Synthesis of Intermediate 13-3: Refer to the synthesis method of intermediates 2-2 to 2-3 in Example 1, except that: intermediate 13-2 (40.0 g, 0.05 mol) is used to replace intermediate 2-2 (38.1 g, 0.05 mol), and reactant C6 (17.5 g, 0.06 mol) is used to replace 2-bromofluorenone (15.5 g, 0.06 mol) to obtain 35.1 g of intermediate 13-3, with a yield of 70.5%, HPLC purity of 98%, and LC-MS showing a molecular weight of 996.3.

[0061] Step 4, Synthesis of spirodifluoren-carbazole derivative (compound 13): The synthesis method of intermediates 2-3 to 2-4 in Example 1 was followed, except that intermediate 2-3 (27.7 g, 0.03 mol) was replaced with intermediate 13-3 (29.8 g, 0.03 mol), yielding 17.3 g of compound 13, with a yield of 63%, HPLC purity of 98%, and LC-MS showing a molecular weight of 914.4.

[0062] The 1H NMR data of compound 13 are as follows Figure 5 As shown: 1 H NMR (500 MHz, DMSO- d 6 ) δ 8.49 (s,1H), 8.41 (s, 1H), 8.13 (s, 1H), 8.07 (d, J = 3.5 Hz, 2H), 8.03 – 7.96 (m, 2H), 7.71 (d, J = 1.5 Hz, 3H), 7.65 (d, J= 7.3 Hz, 4H), 7.56 (s, 1H), 7.51 (s, 2H), 7.42 (s, 1H), 7.40 – 7.24 (m, 10H), 1.32 (s, 18H).

[0063] Example 5 The synthetic route for the spirodifluoren-carbazole derivative (compound 26) is shown below: .

[0064] Step 1, Synthesis of intermediate 26-1: The synthesis method of 1,4-dibromo-2,3-difluorobenzene to 2-1 in Example 1 was followed, except that 3-iodo-9H-carbazole (58.6 g, 0.2 mol) was replaced with carbazole (33.4 g, 0.2 mol), yielding 50.9 g of intermediate 26-1, with a yield of 90.3%, HPLC purity of 97%, and LC-MS showing a molecular weight of 566.0.

[0065] Step 2, Synthesis of Intermediate 26-2: The synthesis method of intermediates 2-2 to 2-3 in Example 1 was followed, except that intermediate 2-2 (38.1 g, 0.05 mol) was replaced with intermediate 26-1 (28.3 g, 0.05 mol), and 2-bromofluorenone (15.5 g, 0.06 mol) was replaced with reactant 3-bromo-9-fluorenone (15.5 g, 0.06 mol) to obtain 26.1 g of intermediate 26-2, with a yield of 72%, HPLC purity of 98%, and LC-MS showing a molecular weight of 728.0.

[0066] Step 3, Synthesis of Intermediate 13-3: Refer to the synthesis method of intermediates 2-3 to 2-4 in Example 1, except that intermediate 2-3 (27.7g, 0.03mol) is replaced with intermediate 26-2 (21.8g, 0.03mol), yielding 12.2g of intermediate 26-3, with a yield of 63%, HPLC purity of 98%, and LC-MS showing a molecular weight of 646.1.

[0067] Step 4, Synthesis of spirodifluoren-carbazole derivative (compound 26): The synthesis method of intermediate 5-3 to compound 5 in Example 2 was followed, except that intermediate 5-3 (23.5 g, 0.03 mol) was replaced with intermediate 26-3 (19.4 g, 0.03 mol), and reactant b8 (10.9 g, 0.04 mol) was replaced with reactant b2 (6.8 g, 0.04 mol) to obtain 22.5 g of compound 26, with a yield of 89.2%, HPLC purity of 98%, and LC-MS showing a molecular weight of 839.2.

[0068] The 1H NMR data of compound 26 are as follows Figure 6 As shown: 1 H NMR (500 MHz, DMSO- d 6 ) δ 8.25–8.14(m, 7H), 8.07 (s, 1H), 7.99 (s, 1H), 7.95–7.89 (m, 3H), 7.83 (s, 1H), 7.73(s, 1H), 7.67 (s, 1H), 7.61 (s, 1H), 7.60–7.36 (m, 10H), 7.36–7.32 (m, 3H),7.26 (d, J = 7.5 Hz, 4H).

[0069] The synthesis of other compounds follows the same method as the compounds described above, except that starting material 1, starting material 2, and starting material 3 can be substituted during the synthesis process. The reactant compositions of some compounds in this invention are shown in Table 1.

[0070] Table 1. Reactant composition of some compounds in this invention The spirodifluoren-carbazole derivatives prepared above exhibit hole transport characteristics and can be used as hole-transport type host light-emitting materials. In a preferred embodiment, the above-mentioned spirodifluoren-carbazole derivatives can be used as the first host light-emitting material, co-deposited with a suitable second host light-emitting material, and used as the host light-emitting material of the organic light-emitting layer to prepare an electromechanical light-emitting device.

[0071] The experimental organic electroluminescent device fabricated by this invention is shown in the schematic diagram below. Figure 1 As shown, the organic electroluminescent device specifically includes five parts: an anode, a hole transport layer (HTL), an emissive layer (EML), an electron transport layer (ETL), and a cathode.

[0072] The substrate layer 01 can be used below the anode layer 02 or above the cathode layer 08, and it needs to have the characteristics of high mechanical strength, excellent thermal stability, excellent water resistance and excellent transparency; the present invention preferably uses polyethylene terephthalate (PET) plastic.

[0073] The organic layer includes a hole injection layer 03, a hole transport layer 04, a light-emitting layer 05, an electron transport layer 06, and an electron injection layer 07. The hole transport layer 04 is located between the hole injection layer 03 and the light-emitting layer 05, and the electron transport layer 06 is located between the light-emitting layer 05 and the electron injection layer 07. The main material of the light-emitting layer adopts a composite main structure mode, which is made of a first main light-emitting material and a second main light-emitting material. The first main light-emitting material is selected from the spirodifluorenocarbazole derivative prepared in this invention. The mass ratio of the first main light-emitting material to the second main light-emitting material is 6:4.

[0074] The second host luminescent material is selected from one of the following compounds: .

[0075] The organic light-emitting layer is located between the hole transport layer and the electron transport layer. In this invention, the first host light-emitting material (compound 2, compound 5, compound 8, compound 10, compound 13, compound 17, compound 21, compound 26, compound 36, compound 58, compound 72, compound 86, compound 97, compound 101, compound 109, compound 128, compound 137, compound 146, compound 155 or compound 157) and the second host light-emitting material (BCP) are co-deposited in a mass ratio of 6:4 to form the host light-emitting material.

[0076] The guest luminescent material is selected from one of the following compounds: .

[0077] Furthermore, the preferred mass ratio of the host luminescent material to the guest luminescent material is 100:0.5. After the preparation of the main functional layers used to achieve organic light emission, the device is packaged using the currently common packaging method in the industry. The test device is prepared into a 30mm×30mm sample, and then the various luminescence performance indicators of the sample are tested and detected. Compared with existing conventional light-emitting devices, it exhibits excellent device performance.

[0078] Application examples A method for fabricating an organic electroluminescent device includes the following steps: A 30mm × 30mm × 1.0mm glass substrate with an ITO transparent electrode (anode layer, ITO film thickness set to 100nm) was sequentially ultrasonically cleaned with a cleaning solution, acetone, ultrapure water, and isopropanol, with each ultrasonic cleaning step lasting 10 minutes. The cleaned ITO glass substrate was then placed in an oven at 80℃ for 3 hours, followed by vacuum plasma cleaning for 10 minutes.

[0079] The plasma-treated glass substrate is mounted on the substrate holder of a vacuum evaporation apparatus. First, F4TCNQ or HATCN, or a mixture thereof, is vacuum-evaporated onto the side where the ITO transparent electrode is formed to form a hole injection layer 03 (HIL) with a thickness of 10 nm. Next, NPD compound is evaporated to form a hole transport layer 04 with a thickness of 40 nm. Then, a primary light-emitting layer 05 is evaporated onto the hole transport layer. During the primary light-emitting layer evaporation, a co-evaporation ratio of primary light-emitting material to guest light-emitting material of 100:0.5 is used, and the total thickness of the light-emitting layer (EML) is controlled to be 50 nm. Finally, an electron transport layer 06 (B4PYMPM) is evaporated onto the light-emitting layer, with a thickness controlled to be 40 nm. A 5nm layer of LiF is then sputtered onto the ETL layer as the electron injection layer 07 (EIL) of the device; then a MgAg alloy (mass ratio Mg:Ag=1:9) is sputtered onto the LiF layer as the cathode layer 08 of the device. The total thickness of the metal sputtering layer is controlled at 10nm.

[0080] The multilayer structure prepared above is vacuum-sealed to isolate it from air and water vapor, thus realizing the basic process of evaluation device fabrication.

[0081] The functional layer material structure used in the fabrication process of the test device is as follows: .

[0082] In this embodiment, the mass ratio of the first main luminescent material to the second main luminescent material is 6:4. The first main luminescent material is compound 2, compound 5, compound 8, compound 10, compound 13, compound 17, compound 21, compound 26, compound 36, compound 58, compound 72, compound 86, compound 97, compound 101, compound 109, compound 128, compound 137, compound 146, compound 155, or compound 157. These correspond to application examples 1 through 20, respectively.

[0083] Comparative Application Example 1 The fabrication method of the electroluminescent device is the same as the above application example, except that the structure of the organic electroluminescent device is: PET substrate / ITO / F4TCNQ / NPD / H-1:BCP:DP1=60:40:0.5 / B4PYMPM / LiF / Mg:Ag.

[0084] Comparative Application Example 2 The fabrication method of the electroluminescent device is the same as the application example above, except that the structure of the organic electroluminescent device is as follows: PET substrate / ITO / F4TCNQ / NPD / H-2:BCP:DP1=60:40:0.5 / B4PYMPM / LiF / Mg:Ag.

[0085] Comparative Application Example 3 The fabrication method of the electroluminescent device is the same as the application example above, except that the structure of the organic electroluminescent device is as follows: PET substrate / ITO / F4TCNQ / NPD / H-3:BCP:DP1=60:40:0.5 / B4PYMPM / LiF / Mg:Ag.

[0086] In the comparative application example 1, the first main luminescent material H-1 is selected from the prior art CN114920758A, a luminescent material and its application, and an organic electroluminescent device containing the same.

[0087] The first host luminescent material H-2 corresponding to Comparative Application Example 2 is selected from the prior art CN118221678A, a multi-phenanthroline luminescent organic compound, various intermediates and their preparation methods.

[0088] In contrast, the first host luminescent material H-3 in Application Example 3 is selected from the prior art CN114853767A, a multi-resonance small molecule luminescent material and an organic electroluminescent diode.

[0089] The structures of H-1, H-2, and H-1 are as follows: .

[0090] The electroluminescent devices from the above application examples and comparative application examples were fabricated into 30mm × 30mm samples. Then, under the same device fabrication process conditions, the anode and cathode layers were connected using an industry-known driving circuit, and the luminescence performance of each electroluminescent device was tested. The preparation process of the examples is basically the same as that of the comparative examples, except that the preferred compounds of this invention are used to replace compounds H-1 to H-3 of the comparative examples as the first host luminescent material, while the other functional layer materials remain unchanged, thus fabricating the devices of Examples 1 to 20. 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 (LT95, i.e., lifetime) was measured. The test results are shown in Table 2.

[0091] Table 2 Performance data of electroluminescent devices prepared in comparative and application examples. Note: Here, EQE refers to the external quantum efficiency at a working brightness of 1000 cd / m2.

[0092] As can be seen from the performance data in Table 1, compared with the electroluminescent devices prepared by the host luminescent materials H-1, H-2, and H-3 in the comparative application examples (comparative application examples 1 to 3), the electroluminescent devices prepared by using the preferred spirodifluorenoxa-carbazole derivative of the present invention as the first host luminescent material have significantly improved overall luminous efficiency. Among them, the driving voltage is significantly lower, the external quantum efficiency is increased by about 50%, and the service life is extended.

[0093] 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.

[0094] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A spirodifluorenazine-carbazole derivative, characterized in that, The general structural formula of the spirodifluoride-carbazole derivatives is shown in Formula 1: ； R1 and R2 are independently selected from H, D, cyano, trifluoromethyl, substituted or unsubstituted C6~C20 aryl, substituted or unsubstituted C6~C20 heteroaryl, respectively. The substituents on the aryl or heteroaryl are selected from F atom, D atom, cyano or trifluoromethyl, and the heteroatom in the heteroaryl is selected from N, O or S. Ra is selected from one of methyl, methoxy, tert-butyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, wherein the substituent on the aryl or heteroaryl is a D atom, methyl, methoxy, tert-butyl, phenyl or diphenylamino, and the heteroatom in the heteroaryl is N, O, S or Si.

2. The spirodifluorenazine-carbazole derivative according to claim 1, characterized in that, In R1 and R2, the aryl or heteroaryl group is selected from one of the following groups: ； In this context, "*" represents a bonding site.

3. The spirodifluorenazole-carbazole derivative according to claim 1, characterized in that, In Ra, the aryl or heteroaryl group is selected from one of the following groups: ； in," " is the bonding site.

4. The spirodifluoren-carbazole derivative according to claim 1, characterized in that, The spirodifluorenazole derivatives are selected from one of the following compounds: 。 5. An organic electroluminescent device, characterized in that, The electroluminescent device includes an anode layer and a cathode layer, as well as an organic layer disposed between the anode layer and the cathode layer. The organic layer, from bottom to top along the direction from the anode layer to the cathode layer, consists of a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, and an electron injection layer. The organic light-emitting layer is prepared from a first host light-emitting material, a second host light-emitting material, and a guest light-emitting material. The first host light-emitting material includes the aforementioned spirodifluorenazole-carbazole derivatives.

6. The organic electroluminescent device according to claim 5, characterized in that, The mass ratio of the first primary luminescent material to the second primary luminescent material is 3-6:4-7, and the mass ratio of the primary luminescent material to the secondary luminescent material is 100:0.2-0.

5.

7. The organic electroluminescent device according to claim 5, characterized in that, The second host luminescent material is selected from one of the following compounds: 。 8. The organic electroluminescent device according to claim 5, characterized in that, The guest luminescent material is selected from one of the following compounds: 。

Images