Compound with condensed ring group, organic electroluminescent device and display device

Abstract

The invention discloses a compound with a condensed ring group, an organic electroluminescent device and a display device, and relates to the technical field of organic electroluminescence. According to the present invention, the compound having the fused ring group generally has a wide HOMO electron cloud delocalization range, and the wide electron cloud delocalization range generally means the high hole mobility, such that the exciton recombination region is widened so as to provide the good light emitting efficiency and the good service life of the light emitting device containing the compound; meanwhile, through structural optimization of the compound designed by the invention, methyl is selectively introduced to a specific position to replace H with relatively high activity, so that the stability of the compound is better, and the luminescence performance of the device is further improved.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescence technology, specifically relating to a compound having a fused ring group, an organic electroluminescent device, and a display device. Background Technology

[0002] Organic electroluminescence, generally speaking, refers to organic light-emitting diodes (OLEDs) that use electric current to drive organic semiconductor thin films to achieve light emission and display. The structure of an OLED device includes a cathode, an anode, and an organic layer disposed between the cathode and anode. When an OLED device is operating, a voltage is applied between the two electrodes. Holes are injected from the anode into the organic layer, and electrons are injected from the cathode into the organic layer. When holes and electrons meet, they form excitons. When these excitons transfer energy to the light-emitting material, light is emitted through radiative transitions in the material.

[0003] The organic layer typically includes films such as a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer. Sometimes, an auxiliary hole transport layer, called a second hole transport layer, is placed between the hole transport layer and the light-emitting layer. A good second hole transport layer can improve the interface characteristics between adjacent layers, helping to reduce leakage current and improve the overall stability and lifetime of the device. However, if the hole mobility of the second hole transport layer is low, the exciton recombination region is prone to tend towards the interface between the second hole transport layer and the light-emitting layer, leading to exciton quenching and drift to the hole auxiliary layer, thereby reducing the device's lifetime and efficiency. Summary of the Invention

[0004] The technical objective of this invention is to further develop materials for organic electroluminescent devices, provide a compound with fused ring groups that can improve hole transport mobility, and an organic electroluminescent device and display device using the compound.

[0005] The technical solution provided by this invention includes the following aspects:

[0006] In a first aspect, a compound having a fused ring group is characterized by having a structure expressed by formula (1):

[0007]

[0008] In formula (1):

[0009] L1 is a direct bond or a C6-C12 arylene group;

[0010] One of the groups in Ar1 and Ar2 is dimethylfluorene, and the other group is selected from substituted or unsubstituted C6-C20 aryl and substituted or unsubstituted C5-C20 heteroaryl. The substituted C6-C20 aryl and substituted C5-C20 heteroaryl contain one or more substituents, and the substituents, whether the same or different, are selected from phenyl or methyl.

[0011] Based on the above solutions, even better solutions include:

[0012] Furthermore, the C6-C12 arylene group is a phenylene group.

[0013] Furthermore, the C6-C20 aryl group is biphenyl or fluorenyl, and the C5-C20 heteroaryl group is a heteroaryl group containing O or S heteroatoms.

[0014] Furthermore, equation (1) is expressed by the following equation (1-1) or equation (1-2):

[0015]

[0016] Furthermore, one of the groups in Ar1 and Ar2 is selected from group (b), and the other group is selected from any one of group (a), group (b), group (c), and group (d):

[0017]

[0018] Here, * indicates a connection bit.

[0019] Furthermore, at least one of Ar1 and Ar2 is selected from group (b), and the linkage position is at position 2 of group (b).

[0020] Furthermore, the compounds of the present invention are selected from any one of the following compounds:

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027] In a second aspect, the present invention provides an organic electroluminescent device, characterized in that it comprises a first electrode, a second electrode, and an organic layer formed between the first electrode and the second electrode, wherein the organic layer contains a compound having a fused ring group as described in any of the preceding claims.

[0028] Preferably, the organic layer includes a hole injection layer, a first hole transport layer, a second hole transport layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer, wherein the second hole transport layer comprises a compound having a fused ring group as described in any of the preceding claims.

[0029] Thirdly, the present invention provides a display device, characterized in that it comprises an organic electroluminescent device as described above.

[0030] The beneficial effects of this invention are as follows:

[0031] 1) The compound of the present invention has a wide HOMO electron cloud delocalization range. A wide electron cloud delocalization range means a higher hole mobility, which in turn widens the exciton recombination region, enabling the light-emitting device containing the compound to have good luminous efficiency and lifetime.

[0032] 2) The compounds of the present invention introduce methyl groups at specific positions in the parent nucleus to replace the more reactive H, thereby improving the stability of the compounds and further enhancing the luminescence performance of the devices. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the organic electroluminescent device provided by the present invention;

[0034] Figure 2 This is the HPLC chromatogram of compound 1 of the present invention;

[0035] Figure 3 This is the DSC spectrum of compound 1 of the present invention.

[0036] Figure 1 The reference numerals in the figures represent: 1-anode, 2-hole injection layer, 3-first hole transport layer, 4-second hole transport layer, 5-light emission layer, 6-hole blocking layer, 7-electron transport layer, 8-electron injection layer, and 9-cathode. Detailed Implementation

[0037] Embodiments of various aspects of the invention are further described and illustrated below. It should be understood that the following description is not intended to limit the claims to the specific aspects described. Rather, it is intended to cover substitutions, modifications, and equivalents that may be included within the scope defined by the appended claims.

[0038] In this document, the terms “substituted” and “unsubstituted” refer to the recoordination of at least one hydrogen atom of a group with other substituent groups. “Aryl” in this document refers to a group containing one or more aromatic rings, which, unless otherwise specified, includes, but is not limited to, benzene, naphthalene, phenanthrene, fluorene, etc. “Heteroaryl” in this document refers to a group obtained by substituting one or more carbon atoms in the structure of an aryl group with one or more heteroatoms (such as O or S).

[0039] The terms C6-C20, C5-C20, and C6-C12 in the text indicate that the modified groups contain 6-20, 5-20, and 6-12 carbon atoms, respectively. If the corresponding groups can be substituted, C6-C20, C5-C20, and C6-C12 do not necessarily include the number of carbon atoms of the substituents.

[0040] The present invention will be further illustrated below with examples of synthesis, application, and testing.

[0041] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0042] Synthesis example 1:

[0043]

[0044] The preparation process of compound 1 is as follows:

[0045] S1. Synthetic ZJ1

[0046] S1.1. Plan

[0047]

[0048] S1.2. Process

[0049] Add SM1 (100g, 0.388mol, 1eq), SM2 (90.1g, 0.408mol, 1.05eq), potassium carbonate (107.3g, 0.776mol, 2eq), and toluene / ethanol / water (1500ml + 750ml + 450ml) to a 3L reaction flask. Under nitrogen protection, add tetrakis(triphenylphosphine)palladium (8.97g, 7.76mmol, 0.02eq), heat to 85℃, reflux and stir for 48h. Monitor SM1 ≤ 1% using HPLC.

[0050] S1.3. Post-processing

[0051] The reaction was stopped, the temperature was lowered to 35℃, 200ml of water was added, and the mixture was stirred and separated. 300ml of DCM was added to the aqueous phase and the mixture was stirred and extracted. The organic phases were combined and filtered through silica gel. The filtrate was concentrated to dryness under reduced pressure. 200ml of PE was added, the temperature was lowered to -5±5℃, and the mixture was stirred to crystallize for 2 hours. The crystals were filtered, and the filter cake was dried at 65℃ by forced air drying to obtain 97.34g of gray solid, with a yield of 86.9%.

[0052] S2. Synthetic ZJ2

[0053] S2.1. Plan

[0054]

[0055] S2.2. Process

[0056] Add ZJ1 (97.34g, 0.337mol, 1eq), potassium carbonate (107.3g, 0.776mol, 3eq) and DMF (1000ml) to a 2L single-necked flask, heat to 160℃ and stir for 24h. Monitor ZJ1 ≤ 0.5% by HPLC.

[0057] S2.3. Post-processing

[0058] The reaction was stopped, the temperature was lowered to 100°C, and the mixture was filtered to remove potassium carbonate. The filter cake was washed with a small amount of DMF, and 3 L of water was added to the filtrate. The mixture was stirred for 2 hours, filtered under vacuum, and the filter cake was washed with 500 ml of water. After the filter cake was dried, 200 ml of ethanol was added, the temperature was raised to 75°C, and the mixture was stirred and slurried for 2 hours. The temperature was lowered to room temperature, filtered under vacuum, and the filter cake was dried under forced air at 65°C to obtain 81.95 g of gray solid, with a yield of 90.5%.

[0059] S3. Synthesis of ZJ3

[0060] S3.1. Plan

[0061]

[0062] S3.2. Process

[0063] Under nitrogen protection, bis(pyridine)tetrafluoroborate iodine (226.86 g, 0.61 mol, 2 eq) and dichloromethane (1000 ml) were added to a 2 L three-necked flask. The mixture was cooled to -70 °C, and fluoroboric acid (107 g, 1.22 mol, 4 eq) was added. The mixture was stirred for 10 minutes, filtered, and the solid was removed. The filtrate was transferred to a dry 3 L three-necked flask and cooled to -60 °C. A solution of ZJ2 (81.95 g, 0.305 mol, 1 eq) in dichloromethane (500 ml) was added dropwise. After the addition was complete, the reaction was allowed to proceed for 8 h. HPLC monitoring showed that ZJ2 ≤ 0.5%.

[0064] S3.3. Post-processing:

[0065] Stop the reaction, add 800 ml of water, stir and separate the liquids. Extract the aqueous phase with 400 ml of DCM, combine the organic phases, dry with anhydrous sodium sulfate, filter, concentrate the filtrate to dryness under reduced pressure, add 200 ml of ethanol, cool to -5℃ and stir for 2 h, filter, dry the filter cake at 65℃ with forced air to obtain 70.1 g of gray solid, yield 82.5%.

[0066] S4. Synthesis of ZJ4

[0067] S4.1. Plan

[0068]

[0069] S4.2. Process

[0070] Under nitrogen protection, ZJ3 (70.1 g, 0.252 mol, 1 eq) and ultra-dry THF (700 ml) were added to a 2 L three-necked flask. AlCl3 (41.9 g, 0.314 mol, 1.25 eq) was slowly added and stirred for 15 minutes. The mixture was then cooled to -5 to 0 °C, and lithium hydroxide (LAH) (9.05 g, 0.378 mol, 1.5 eq) was added in batches. After the addition was complete, the mixture was heated to 85 °C and stirred under reflux for 5 h. HPLC monitoring showed that ZJ3 ≤ 1%.

[0071] S4.3. Post-processing

[0072] The reaction was stopped, and the mixture was slowly cooled to room temperature. Ethyl acetate (500 ml) was slowly added until no more bubbles were produced. 800 ml of water was added, and the mixture was stirred and separated. The aqueous phase was extracted with 400 ml of ethyl acetate. The organic phases were combined and concentrated to dryness under reduced pressure. 100 g of 100-200 mesh silica gel was added to prepare silica gel slurry. 700 g of 100-200 mesh silica gel was packed into a column for column chromatography. The column was washed with pure PE, and the product spot was collected. The product was concentrated to dryness under reduced pressure to give 43.9 g of off-white solid, with a yield of 65.8%.

[0073] S5. Synthetic ZJ5

[0074] S5.1. Scheme

[0075]

[0076] S5.2. Process

[0077] Under nitrogen protection, ZJ4 (43.9 g, 0.166 mol, 1 eq) and ultra-dry THF (400 ml) were added to a 2 L three-necked flask. The temperature was lowered to -10 to 0 °C, and 60% sodium hydride (26.6 g, 0.664 mol, 4 eq) was added slowly in portions. After the addition was complete, the temperature was raised to 40 °C and stirred for 1 h. The temperature was then lowered to -10 to 0 °C, and iodomethane (70.7 g, 0.498 mol, 3 eq) was added dropwise. After the addition was complete, the mixture was transferred to room temperature (25 ± 5 °C) and stirred for 18 h. The ZJ4 content was monitored by HPLC to be ≤0.5%.

[0078] S5.3. Post-processing

[0079] The reaction was stopped, the reaction solution was cooled to -10℃, and water (400ml) was slowly added dropwise to quench the reaction. The mixture was stirred and separated. The aqueous phase was extracted with 200ml of DCM. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated to dryness under reduced pressure. 100ml of PE was added, the mixture was cooled to -5℃ and stirred to induce crystallization for 2 hours. The mixture was then filtered, and the filter cake was dried under blast at 85℃ to obtain 34.5g of off-white solid, with a yield of 71%.

[0080] S6. Synthesize target compound 1

[0081] S6.1. Scheme

[0082]

[0083] S6.2. Process

[0084] In a 1L three-necked flask, ZJ5 (34.5g, 0.118mol, 1eq), SM3 (42.6g, 0.118mol, 1eq), sodium tert-butoxide (13.6g, 0.141mol, 1.2eq), XPhos (2.25g, 4.72mmol, 0.04eq), and toluene (350ml) were added. Under N2 protection, palladium acetate (0.53g, 2.36mmol, 0.02eq) was added. After the addition was complete, the temperature was raised to 100℃ and the reaction was stirred until ZJ5 was ≤0.5% as monitored by HPLC.

[0085] S6.3. Post-processing

[0086] The reaction was stopped, and the mixture was filtered through silica gel while hot. The filtrate was concentrated to dryness under reduced pressure. No solid was formed. 60g of 100-200 mesh silica gel was added to prepare silica gel slurry, and 500g of 100-200 mesh silica gel was packed into a column for column chromatography. The PE / DCM ratio was 20 / 1 to 10 / 1. The product spot was collected and concentrated to dryness under reduced pressure. 150ml of ethanol was added to the solid, and the mixture was refluxed and stirred for 12 hours. The mixture was cooled to room temperature and filtered. The filter cake was recrystallized four times with toluene / ethanol (50ml + 100ml). The filter cake was then filtered and dried at 85℃ with a forced air drying process to obtain 37.62g of off-white solid, which was the target compound 1, with an HPLC purity of approximately 99.97% and a yield of 51.9%.

[0087] Synthesis example 2:

[0088]

[0089] The preparation process of compound 4 includes:

[0090] S7. Synthetic ZJ6

[0091] S7.1 solution

[0092]

[0093] The synthesis process of ZJ5 is the same as that of Synthesis Example 1 (steps S1-S5), and will not be repeated here.

[0094] S7.2 process

[0095] In a 1L three-necked flask, ZJ5 (34.5g, 0.118mol, 1eq), pinacol diboronate (38.9g, 0.153mol, 1.3eq), potassium acetate (34.7g, 0.354mol, 3eq), XPhos (5.63g, 11.8mmol, 0.1eq), and 1,4-dioxane (350ml) were added. Under N2 protection, palladium acetate (1.32g, 5.9mmol, 0.05eq) was added, and the mixture was heated to 90–100℃ and stirred for 12 h. The ZJ5 content was monitored by HPLC to be ≤0.5%.

[0096] S7.3 Post-processing:

[0097] The reaction was stopped, and the mixture was filtered through silica gel while hot. The filter cake was washed with 400 ml of DCM, and the filtrate was concentrated to dryness under reduced pressure. 60 ml of ethanol was added, and the mixture was cooled to 0°C and stirred to induce crystallization for 5 h. The mixture was then filtered, and the filter cake was dried in a forced-air oven at 85°C to obtain 37 g of gray solid, with a yield of 81.7%.

[0098] S8. Synthetic ZJ7

[0099] S8.1 solution

[0100]

[0101] S8.2 process

[0102] In a 2L three-necked flask, ZJ6 (37g, 96.3mmol, 1eq), SM4 (27.2g, 96.3mmol, 1eq), potassium carbonate (26.6g, 0.193mol, 2eq), Pd(PPd3)4 (2.23g, 1.926mmol, 0.02eq) and toluene / ethanol / water (600ml + 300ml + 180ml) were added. Under N2 protection, the mixture was heated to 85℃ and refluxed for 24h. HPLC monitoring was performed until ZJ6 ≤ 1%.

[0103] S8.3 Post-processing:

[0104] The reaction was stopped, the temperature was lowered to 30±5℃, 200ml of water was added and stirred to separate the liquids. 200ml of DCM was added to the aqueous phase and stirred to extract. The organic phases were combined and filtered through silica gel. The filtrate was concentrated to dryness under reduced pressure. 150ml of PE was added and stirred to crystallize for 5 hours. The mixture was then filtered and the filter cake was dried at 85℃ to obtain 31.4g of gray solid, with a yield of 78.9%.

[0105] S9. Synthesis of target compound 4

[0106]

[0107] S9.1 process

[0108] In a 1L three-necked flask, ZJ7 (31.4g, 76mmol, 1eq), SM5 (27.5g, 76mmol, 1eq), sodium tert-butoxide (8.76g, 91.2mmol, 1.2eq), tritert-tert-butylphosphine (6.2ml, 3.04mmol, 0.04eq), and toluene (300ml) were added. Under N2 protection, tris(dibenzylacetone)palladium (1.39g, 1.52mmol, 0.02eq) was added. After the addition was complete, the temperature was raised to 100℃ and the reaction was stirred for 6h. HPLC monitoring showed that ZJ7 ≤ 1%.

[0109] S9.2 Post-processing

[0110] The reaction was stopped, and the mixture was filtered through silica gel while hot. The filtrate was concentrated to dryness under reduced pressure. 45g of 100-200 mesh silica gel was added to prepare silica gel slurry. 450g of 100-200 mesh silica gel was packed into a column for column chromatography. The PE / DCM ratio was 20 / 1 to 10 / 1. The product spot was collected and concentrated to dryness under reduced pressure. The product was recrystallized four times with toluene / ethanol (50ml + 100ml). The mixture was filtered, and the filter cake was dried at 85℃ with a forced air drying process to give 29.1g of off-white solid, which was the target compound, with a yield of 55.2%.

[0111] Following a similar preparation method to that used in Synthesis Example 1 and Synthesis Example 2, compounds 3, 6, 9, 12, 15, 18, 21, 22, 25, 27, 29, 31, 33, 35, 39, 41, 43, 44, 46, 47, 49, and 50 were subsequently prepared sequentially, as shown in Table 1 below:

[0112] Table 1

[0113]

[0114]

[0115]

[0116]

[0117]

[0118] The results of the synthetic identification of compounds 1, 3, 4, 6, 9, 12, 15, 18, 21, 22, 25, 27, 29, 31, 33, 35, 39, 41, 43, 44, 46, 47, 49 and 50 are shown in Table 2 below:

[0119] Table 2

[0120]

[0121]

[0122] Material property testing:

[0123] The melting point temperatures Tm of compounds 1, 3, 4, 6, 9, 12, 15, 18, 21, 22, 25, 27, 29, 31, 33, 35, 39, 41, 43, 44, 46, 47, 49, and 50 were tested, and the results are shown in Table 3 below.

[0124] Table 3

[0125] serial number Tm / ℃ serial number Tm / ℃ serial number Tm / ℃ 1 286.00℃ 21 294.61℃ 39 302.77℃ 3 292.50℃ 22 288.49℃ 41 275.23℃ 4 298.72℃ 25 291.52℃ 43 281.35℃ 6 295.41℃ 27 289.47℃ 44 281.54℃ 9 300.12℃ 29 292.41℃ 46 283.01℃ 12 303.43℃ 31 281.66℃ 47 280.76℃ 15 271.98℃ 33 287.64℃ 49 300.71℃ 18 287.91℃ 35 293.71℃ 50 289.67℃

[0126] Note: The melting point temperature Tm above was determined using differential scanning calorimetry (DSC, Shinco DSC N-650) at a heating rate of 10℃ / min.

[0127] Based on the melting point temperature data, it can be seen that the compound synthesized in this invention exhibits excellent thermal stability.

[0128] Device performance testing:

[0129] Application Example 1:

[0130] ITO was used as the anode substrate material for the reflective layer, and its surface was treated sequentially with water, acetone, and N2 ions.

[0131] A 10 nm layer of HT-1 doped with 5% NDP-9 is deposited on top of the ITO anode substrate to form a hole injection layer (HIL).

[0132] A first hole transport layer (HTL) is formed by depositing 100 nm of HT-1 above the hole injection layer (HIL);

[0133] Compound 1 of the present invention is vacuum-deposited over the first hole transport layer (HTL) to form a second hole transport layer (GPL) with a thickness of 10 nm.

[0134] GH-2 and GH-1 were used as the main light-emitting materials in a 5:5 (mass ratio) ratio, and GD-1 was used as the dopant material (the amount of GD-1 was 8% of the total weight of GH-1 and GH-2) and were co-deposited to form a light-emitting layer with a thickness of 20 nm on the second hole transport layer (GPL).

[0135] HB-1 was deposited onto the light-emitting layer to obtain a hole blocking layer (HBL) with a thickness of 20 nm;

[0136] ET-1 and LiQ were co-deposited onto the hole blocking layer (HBL) in a 5:5 (mass ratio) to obtain an electron transport layer (ETL) with a thickness of 30 nm.

[0137] Magnesium (Mg) and silver (Ag) are mixed in a 9:1 ratio (by mass) and vapor-deposited onto the electron transport layer (ETL) to form an electron injection layer (EIL) with a thickness of 50 nm.

[0138] Silver (Ag) is vapor-deposited onto the electron injection layer to form a cathode with a thickness of 12 nm. A 50 nm thick DNTPD is then deposited on the cathode sealing layer. Furthermore, the cathode surface is sealed with a UV-curable adhesive and a sealing film containing a desiccant to protect the organic electroluminescent device from the influence of atmospheric oxygen or moisture. Thus, an organic electroluminescent device is prepared.

[0139] The structural formulas of the compounds used in the above process are as follows:

[0140]

[0141]

[0142] Application Example 2-24:

[0143] Organic electroluminescent devices of Application Examples 2-24 were fabricated by replacing compound 1 with compounds 3, 4, 6, 9, 12, 15, 18, 21, 22, 25, 27, 29, 31, 33, 35, 39, 41, 43, 44, 46, 47, 49 and 50 as materials for the second hole transport layer, respectively, and the preparation of other organic layers was the same as in Application Example 1.

[0144] Compare with Example 1-2:

[0145] Organic electroluminescent devices of Comparative Example 1 and Comparative Example 2 were fabricated by vapor deposition using control compounds D1 and D2 as materials for the second hole transport layer of the device, with the preparation of other organic layers being the same as in Application Example 1.

[0146] The structures of compounds D1 and D2 are shown below:

[0147]

[0148] The characteristics of the organic electroluminescent devices manufactured using Examples 1-24 and the organic electroluminescent devices manufactured using Control Examples 1 and 2 were tested under the same conditions. The test results are shown in Table 4 below:

[0149] Table 4

[0150]

[0151]

[0152] A direct comparison of Compound 1 and Comparative Compound D1 reveals that, compared to Compound D1, Compound 1 has two H groups replaced by two methyl groups at specific positions. Replacing the relatively reactive H groups with methyl groups at these positions aims to further improve the compound's stability and enhance the device's luminescent performance. As shown in the table above, compared to Comparative Example 1, the device in Application Example 1 exhibits a significant improvement in luminescent efficiency and a decrease in startup voltage, thus reducing power consumption. Furthermore, a comparison between Application Example 1 and Comparative Example 2 shows that Application Example 1 outperforms Comparative Example 2 in both luminescent efficiency and startup voltage. Comparing Compound 1 and Compound D2 reveals differences in the structures of their fused-ring groups and the connection sites with the N atoms of the amine groups. Testing revealed that, compared to Compound D2, Compound 1 has better solubility, lower sublimation temperature, and lower deposition temperature. This is beneficial for improving film quality, reducing film defects, facilitating hole transport, reducing leakage current, and ultimately enhancing device performance, primarily manifested in higher luminescent efficiency, lower driving voltage, and longer luminescent lifetime.

[0153] Furthermore, compared with the various application examples, it can be seen that the devices containing the compounds of the present invention have better luminous efficiency and lower operating voltage, which is superior to the comparative devices.

[0154] Under the same conditions, the organic electroluminescent devices manufactured for Examples 1-24 and the organic electroluminescent devices manufactured for Comparative Examples 1 and 2 were subjected to lifetime tests. The tests were conducted at a current density of 10 mA / cm². 2 The luminescence lifetime T97% data (the time it takes for the luminescence brightness to decrease to 97% of the initial brightness) was obtained under the following conditions.

[0155] Using device lifetime data containing the comparative compound D1 as a reference, Table 5 is obtained as follows:

[0156] Table 5

[0157]

[0158] As can be seen from the table above, compared with the comparative compounds with similar structures, the devices of the present invention exhibit superior performance in terms of luminescence lifetime when applied to organic electroluminescent devices under the same test conditions.

[0159] The above tests demonstrate that the improvements made to the compound in this invention have improved the luminous efficiency and lifetime of the device.

[0160] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A compound having a fused ring group, characterized in that, It has a structure expressed by equation (1): In formula (1): L1 is a direct bond or a C6-C12 arylene group; One of Ar1 and Ar2 is dimethylfluorene, and the other group is selected from substituted or unsubstituted C6-C20 aryl and substituted or unsubstituted C5-C20 heteroaryl groups, wherein the substituted C6-C20 aryl and substituted C5-C20 heteroaryl groups contain one or more substituents, and the same or different substituents are selected from phenyl or methyl.

2. The compound having a fused ring group as described in claim 1, characterized in that, The C6-C12 arylene group is a phenylene group.

3. The compound having a fused ring group as described in claim 1, characterized in that, The C6-C20 aryl group is biphenyl or fluorenyl, and the C5-C20 heteroaryl group is a heteroaryl group containing O or S heteroatoms.

4. The compound having a fused ring group as described in claim 1, characterized in that, Equation (1) is expressed by the following equation (1-1) or equation (1-2):

5. The compound having a fused ring group as described in claim 1, characterized in that, One of the groups in Ar1 and Ar2 is selected from group (b), and the other group is selected from any one of group (a), group (b), group (c), and group (d): Here, * indicates a connection bit.

6. The compound having a fused ring group as described in claim 5, characterized in that, At least one of Ar1 and Ar2 is selected from group (b), and the linkage position is at position 2 of group (b).

7. The compound having a fused ring group as described in claim 1, characterized in that, Selected from any of the following compounds:

8. An organic electroluminescent device, characterized in that, It includes a first electrode, a second electrode, and an organic layer formed between the first electrode and the second electrode, said organic layer containing a compound having a fused ring group as described in any one of claims 1-7.

9. The organic electroluminescent device as described in claim 8, characterized in that, The organic layer includes a hole injection layer, a first hole transport layer, a second hole transport layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer, wherein the second hole transport layer comprises a compound having a fused ring group as described in any one of claims 1-7.

10. A display device, characterized in that, It includes the organic electroluminescent device as described in claim 8 or 9.

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