A thermally activated delayed fluorescence compound and an organic electroluminescent device thereof

Abstract

The present application belongs to the technical field of organic electroluminescent materials, and particularly relates to a kind of thermal activated delayed fluorescence compound and organic electroluminescent device thereof, the series of compounds provided by the present application adopt dicyano as acceptor, and the side chain carbazole compound on both sides is donor, and a benzopentaheterocyclic ring or five-membered heterocyclic structure is externally connected on the donor, which can improve the injection of electrons in the light-emitting layer, play the role of balancing carriers, be conducive to the generation of excitons, effectively reduce the triplet and singlet energy level, so as to realize the high fluorescent quantum efficiency of organic electroluminescent device, and improve the comprehensive performance of organic electroluminescent device.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescent materials technology, and particularly relates to a thermally activated delayed fluorescence compound and its organic electroluminescent device. Background Technology

[0002] Thermally activated delayed fluorescence (TADF) materials, as third-generation organic electroluminescent materials, have attracted widespread attention since their initial report by the Adachi research group at Kyushu University, Japan, due to their ability to achieve high internal quantum efficiency without relying on noble metals. These materials fully utilize the singlet and triplet excitons generated by electroexcitation through an efficient reverse system-to-singlet crossover (RISC) process, theoretically enabling organic light-emitting diodes (OLEDs) to achieve 100% internal quantum efficiency. They also possess advantages such as low cost and environmental friendliness, demonstrating enormous application potential.

[0003] In OLED devices, the statistical distribution of excitons is 25% singlet states and 75% triplet states. Traditional fluorescent materials can only utilize singlet excitons for light emission, with an upper limit of internal quantum efficiency of 25%. Phosphorescent materials, by leveraging the strong spin-orbit coupling of heavy metal atoms, can utilize both singlet and triplet excitons simultaneously, achieving 100% internal quantum efficiency. However, they rely on rare metals such as iridium (Ir) and platinum (Pt), resulting in high costs and environmental risks. TADF materials, as a purely organic light-emitting system, are designed to have an extremely small singlet-triplet energy level difference (ΔE). ST The molecular structure of the exciton is such that, under thermal activation conditions, the triplet exciton is converted into a singlet exciton through a RISC process, thereby emitting delayed fluorescence, which has the combined advantages of high efficiency and low cost.

[0004] To further enhance device performance and expand application range, a superfluorescence strategy using TADF materials as sensitizers has been developed in recent years. This strategy uses TADF materials as an exciton trapping layer and energy transfer medium, transferring singlet energy to conventional fluorescent dopants via efficient Förster resonance energy transfer (FRET), ultimately resulting in the emission of high-color-purity light from the fluorescent material. This structure retains the advantages of traditional fluorescent materials, such as narrow spectral density and good stability, while fully leveraging the efficient utilization of triplet excitons by TADF materials, significantly improving the luminous efficiency and color quality of the device.

[0005] Therefore, developing novel TADF materials with high luminous efficiency has become a key research direction for promoting the further development of OLED technology. By continuously optimizing molecular configurations and exploring novel donor-acceptor units and their spatial arrangements, it is hoped that the overall performance of materials can be improved while advancing the practical application of TADF materials in next-generation display technologies. Summary of the Invention

[0006] To address the problems existing in the background art, the present invention provides a thermally activated delayed fluorescence compound, the structure of which is shown in general formula (I):

[0007] ;

[0008] L is selected from single bond, substituted or unsubstituted C6-C. 12 Aromatic rings, either substituted or unsubstituted, are C3-C6 heteroaromatic rings, with each R5 independently selected from hydrogen, deuterium, or phenyl;

[0009] C is selected from structure (I)-1, and D is selected from (I)-2 or (I)-3:

[0010] ;

[0011] X is independently selected from O, S, and Se;

[0012] R is independently selected from hydrogen, deuterium, cyano, C1-C6 alkyl, substituted or unsubstituted C6-C 12 Aryl or C3-C 12 The heteroaryl group or the following groups, and at least one of C or D is an R group that is one of the following groups:

[0013] ;

[0014] X1 is independently selected from NR3, O, S, and Se; X2 is independently selected from N and CR4.

[0015] R1 to R4 are each independently selected from hydrogen, deuterium, cyano, C1-C6 alkyl, substituted or unsubstituted C6-C6. 12 Aryl or C3-C 12 heteroaryl groups;

[0016] * indicates a linking site. When substitution is present, the substituents are independently selected from deuterium, cyano, C1-C6 alkyl, C6-C6... 12 The aryl group, C3-C6 heteroaryl group, n is from 1 to the largest substitution site number of the ring, and the heteroatom is N.

[0017] As a preferred embodiment of the present invention, L is a single bond, phenyl, naphthyl or pyridyl.

[0018] As a preferred embodiment of the present invention, R is independently selected from hydrogen, deuterium, cyano, tert-butyl, phenyl, and pyridyl.

[0019] As a preferred embodiment of the present invention, X1 is independently selected from O or S, and X2 is independently selected from N or CR4.

[0020] As a preferred embodiment of the present invention, R1 to R4 are each independently selected from hydrogen, deuterium, cyano, methyl, tert-butyl, substituted or unsubstituted phenyl or pyridyl.

[0021] As a preferred embodiment of the present invention, when substitutions are present, each substituent is independently selected from deuterium, cyano, methyl, tert-butyl, phenyl, and pyridyl.

[0022] As a preferred embodiment of the present invention, the specific structure of the thermally activated delayed fluorescence compound is as follows:

[0023] ;

[0024] ;

[0025] ;

[0026] ;

[0027] ;

[0028] ;

[0029] ;

[0030] ;

[0031] ;

[0032] .

[0033] Another object of the present invention is to provide an organic electroluminescent device having an anode, a cathode, and an organic layer, wherein the organic layer includes a light-emitting layer, and the light-emitting layer includes the aforementioned thermally activated delayed fluorescence compound.

[0034] As a preferred embodiment of the present invention, the organic electroluminescent device is used to manufacture display devices, lighting sources, signal lights, and signs. The display devices include mobile phone displays, computer displays, television displays, smartwatch displays, smart car display panels, and VR or AR helmet displays.

[0035] The beneficial effects of this invention are as follows:

[0036] The series of compounds provided by this invention utilizes a dicyano group as the acceptor and carbazole compounds on both sides as donors. Furthermore, a benzo[5]-5-membered heterocyclic ring or a five-membered heterocyclic structure is externally attached to the donor. The introduction of the benzo[5]-5-membered heterocyclic ring or the five-membered heterocyclic structure can improve electron injection into the emitting layer, acting as a carrier balancer, which is beneficial for exciton generation and can effectively reduce the triplet and singlet energy levels, thereby achieving a smaller bandgap (ΔE). ST<0.01eV), it can also enhance charge transfer between near-enantiomers, effectively improve their spin-orbit coupling ability, and further increase the antisystem crossing coefficient (k). RISC This enables the conversion of triplet excitons and reduces their annihilation. Furthermore, the introduction of benzo[5] or five-membered heterocyclic structures increases the radiative transition rate (kJ / kJ) of the material. r This is more conducive to balancing the decay of radiative transitions and the transfer and transformation of excitons, thereby achieving high fluorescence quantum efficiency (PLQY). Attached Figure Description

[0037] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0038] Figure 1 This is the 1H NMR spectrum of compound 1 in this invention;

[0039] Figure 2 This is a transient lifetime decay curve of compound 1 in this invention. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below with reference to synthetic and device embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] Synthesis Examples

[0042] Example 1: Synthesis of Compound 1

[0043]

[0044] Synthesis of 1-3: Under nitrogen atmosphere, 1-1 (3.6 g, 14.5 mmol), 1-2 (5.9 g, 43.5 mmol), palladium acetate (Pd(OAC)2) (0.2 g, 0.87 mmol), copper acetate (Cu(OAC)2) (0.5 g, 2.9 mmol), potassium carbonate (K2CO3) (4.0 g, 29.1 mmol), and triphenylphosphine (PPh3) (2.3 g, 8.7 mmol) were placed in a three-necked flask, and 200 mL of toluene was added. The reaction mixture was heated to 110 °C and reacted at this temperature for 12 hours. After the reaction was complete, the reaction system was cooled to room temperature. Deionized water was added to the reaction system, followed by separation. The organic phase was collected, dried with sodium sulfate, and the filtrate was collected. The solvent was removed under reduced pressure using a rotary evaporator to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain 1-3 (3.2 g, 73%). The molecular weight determined by mass spectrometry was 300.41 (theoretical value: 300.38).

[0045] Synthesis of 1-5: Under a nitrogen atmosphere, 1-4 (16.3 g, 60 mmol), cuprous cyanide (CuCN) (12 g, 134 mmol), and N-methyl-2-pyrrolidone (NMP) (80 mL) were added to a 2 L three-necked flask, and the mixture was stirred at 150 °C for 5 hours. 100 mL of dichloromethane was added to the reaction mixture, and the mixture was filtered through diatomaceous earth and the filtrate was concentrated using an evaporator. After purification and concentration by silica gel chromatography, 1-5 (6.0 g, 61%) was obtained, with a molecular weight determined by mass spectrometry of 164.29 (theoretical value: 164.11).

[0046] Synthesis of 1-6: Under a nitrogen atmosphere, 1-5 (2.0 g, 12 mmol), potassium carbonate (3.3 g, 24 mmol), palladium acetate (0.1 g, 0.6 mmol), tricyclohexylphosphine (P(Cy)3) (0.5 g, 1.8 mmol), bromobenzene (3.2 mL, 30 mmol), 2-ethylhexanoic acid (7.8 mL, 5 mmol), and xylene (50 mL) were added to a 500 mL three-necked flask and stirred at 100 °C for 5 hours. 100 mL of dichloromethane was added to the reaction solution and passed through diatomaceous earth. The dichloromethane in the resulting solution was removed, and the precipitated solid was filtered. The solid was purified by silica gel column chromatography to obtain 1-6 (1.3 g, 35%), with a molecular weight determined by mass spectrometry of 316.19 (theoretical value: 316.31).

[0047] Synthesis of 1-7: Under a nitrogen atmosphere, 1-6 (3.2 g, 10 mmol), 1-3 (3.0 g, 10 mmol), cesium carbonate (Cs₂CO₃) (8.2 g, 25 mmol), and N,N-dimethylformamide (DMF) (50 mL) were added to a 250 mL two-necked flask. The reaction was carried out overnight at 120 °C under nitrogen protection. Heating was stopped, and after cooling to room temperature, 150 mL of water was added and stirred for 10 min. A large amount of white solid precipitated. The solid was filtered, and the filter cake was washed with ethanol for 2 h. After cooling, the solid was filtered again to obtain 1-7 (4.2 g, 70%). The molecular weight determined by mass spectrometry was 596.55 (theoretical value: 596.68).

[0048] Synthesis of Compound 1: Under a nitrogen atmosphere, 1-7 (6.0 g, 10 mmol), 1-8 (3.3 g, 10 mmol), cesium carbonate (8.2 g, 25 mmol), and N,N-dimethylformamide (50 mL) were added to a 250 mL two-necked flask. The reaction was carried out overnight at 120 °C under nitrogen protection. Heating was stopped, and after cooling to room temperature, 150 mL of water was added and stirred for 10 min. A large amount of white solid precipitated. The solid was filtered, and the filter cake was washed with ethanol for 2 h. After cooling, the solid was filtered again to obtain Compound 1 (6.6 g, 73%). The molecular weight determined by mass spectrometry was 910.18 (theoretical value: 910.07).

[0049] Example 2: Synthesis of Compound 20

[0050]

[0051] The synthesis methods of 20-2 and 1-3 are the same, except that 1-1 is replaced by 20-1. The molecular mass determined by mass spectrometry is 369.19 (theoretical value: 369.32).

[0052] Synthesis of 20-3: Under a nitrogen atmosphere, 20-2 (30.1 g, 76 mmol), tert-butylcarbamate (NH2BOC) (124 mg, 106 mmol), tris(dibenzylacetone)dipalladium-chloroform adduct (Pd2(dba)3.CHCl3) (104 mg, 10.0 mmol), 2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl (X-phos) (145 mg, 34.0 mmol), sodium tert-butoxide (NaOt-Bu) (107 mg, 111.0 mmol), and toluene (300 mL) were added to a 500 mL three-necked flask. The reaction system was then heated to 60 °C and reacted for 12 hours. After the reaction was complete, the mixture was diluted with ethyl acetate and water, and neutralized with 1 M hydrochloric acid. The organic layer was separated, washed with brine, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain the crude product. The crude product obtained in the previous step was dissolved in a mixed solution of dioxane (0.49 mL, 1.97 mmol) and dichloromethane (1.5 mL) containing 4 M hydrochloric acid. The solution was stirred at room temperature for 3 hours. The mixture was diluted with ethyl acetate, poured into ice water, neutralized with saturated sodium bicarbonate solution, washed with brine, dried over anhydrous sodium sulfate, and then concentrated. The crude product was purified by silica gel column chromatography to give 20-3 (20.7 g, 82%), with a molecular weight determined by mass spectrometry of 332.46 (theoretical value: 332.44).

[0053] Synthesis of 20-5: Under a nitrogen atmosphere, 20-3 (15.0 g, 45 mmol), 20-4 (8.6 g, 45 mmol), tris(dibenzylacetone)dipalladium (Pd2(dba)3) (0.8 g, 0.9 mmol), 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (X-phos) (0.4 g, 0.9 mmol), sodium tert-butoxide (6.5 g, 68 mmol), and 400 mL of toluene were added to a 1 L three-necked flask. The reaction mixture was heated to 110 °C and stirred for 8 hours. After the reaction was complete, the reaction mixture was cooled to room temperature. 300 mL of deionized water was added to the reaction system, the organic phase was collected by separation, dried with anhydrous sodium sulfate, and the organic reagents were removed by rotary evaporation under reduced pressure. The crude product was purified by silica gel column chromatography to obtain 20-5 (12.4 g, 65%), and the molecular weight determined by mass spectrometry was 442.84 (theoretical value: 442.98).

[0054] Synthesis of 20-6: Under a nitrogen atmosphere, 20-5 (9.2 g, 20.7 mmol), 1,3-bis(26-diisopropylphenyl)imidazolium gaseous compound (IPrHCl) (0.36 g, 0.82 mmol), palladium(II) acetate (Pd(OAc)2) (0.093 g, 0.41 mmol), potassium carbonate (5.8 g, 42 mmol), and 60 mL of N,N-dimethylacetamide (DMAc) were added to a 500 mL three-necked flask. The reaction system was heated to 140 °C and stirred for 12 hours. After the reaction was complete, it was cooled to room temperature. The precipitated solid in the reaction system was filtered, and the filter cake was washed three times with acetone. The filter cake was collected and dried in a vacuum oven to obtain 20-6 (3.2 g, 38%). The molecular weight determined by mass spectrometry was 406.39 (theoretical value: 406.52).

[0055] Synthesis of 20-7: Under a nitrogen atmosphere, 1-6 (4.0 g, 12.5 mmol), 70 mL of acetonitrile (MeCN), and 40 mL of water were added to a 1 L three-necked flask. Then, 1.5 mL of ammonia (30 wt%) was added to the flask. The reaction mixture was heated to 80 °C and stirred at this temperature for 10 hours. After the reaction was complete, the reaction solvent was cooled to room temperature. The organic phase was extracted with ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was removed from the organic phase using a rotary evaporator under reduced pressure. The residue was purified by silica gel column chromatography to obtain a solid, yielding 20-7 (3.6 g, 91%). The molecular weight determined by mass spectrometry was 313.19 (theoretical value: 313.34).

[0056] Synthesis of 20-8: Under a nitrogen atmosphere, 20-7 (16.0 g, 51 mmol), iodine (26 g, 102 mmol), and 125 mL of acetonitrile (MeCN) were added to a 500 mL three-necked flask. Then, tert-butyl nitrite (t-BuONO) (10 g, 102 mmol) was added to the reaction system, and the mixture was stirred at 25 °C for 8 hours. After the reaction was complete, 50 mL of saturated sodium bisulfite aqueous solution was added to the reaction solution. The reaction system was separated, and the organic phase was collected and dried using anhydrous sodium sulfate. The organic phase was subjected to reduced pressure evaporation using a rotary evaporator to remove the solvent from the resulting solution, and then purified by silica gel column chromatography to obtain 20-8 (13.6 g, 63%). The molecular weight determined by mass spectrometry was 424.37 (theoretical value: 424.22).

[0057] Synthesis of 20-10: 20-8 (16.1 g, 38 mmol), 20-9 (14.9 g, 41 mmol), tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) (0.44 g, 0.38 mmol), and potassium carbonate (11 g, 76 mmol) were placed in a 1 L three-necked flask. The mixture was purged three times with nitrogen. Under a nitrogen atmosphere, toluene / ethanol / water = 400 mL / 100 mL / 200 mL was added. The mixture was heated to 60 °C and maintained at this temperature... The reaction was carried out for 12 hours under the specified conditions. After the reaction system was cooled to room temperature, the organic phase was collected by separation. The organic phase was washed with brine and the aqueous phase was extracted with ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate. After drying, the solvent was removed by rotary evaporation under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain 20-10 (20.6 g, 88%). The molecular weight determined by mass spectrometry was 615.59 (theoretical value: 615.71).

[0058] Compound 20 was synthesized using the same method as compound 1, except that 20-10 replaced 1-7 and 20-6 replaced 1-8. The molecular mass determined by mass spectrometry was 1002.11 (theoretical value: 1002.23).

[0059] Example 3: Synthesis of Compound 58

[0060]

[0061] The synthesis methods of 58-2 and 1-3 are the same, except that 58-1 is used instead of 1-1. The molecular mass determined by mass spectrometry is 300.53 (theoretical value: 300.38).

[0062] Synthesis of 58-4: Under a nitrogen atmosphere, 58-3 (13.2 g, 50 mmol), copper oxide (I)(Cu₂O) (0.1 g, 0.66 mmol), ammonia (100 mL, 30%), and N-methylpyrrolidone (NMP) (100 mL) were added to a 500 mL three-necked flask. The reaction system was slowly heated to 80 °C and stirred at this temperature for 12 hours. After the reaction was complete, the reaction system was brought to room temperature, and 300 mL of deionized water was added. The mixture was extracted with dichloromethane, and the organic phase was collected, washed with brine, and dried with anhydrous sodium sulfate. The dried organic phase was concentrated using a rotary evaporator. The crude product obtained after concentration was purified by silica gel column chromatography to obtain 58-4 (8.1 g, 81%), with a molecular weight determined by mass spectrometry of 199.38 (theoretical value: 199.27).

[0063] The synthesis methods for 58-7 and 20-10 are the same, except that 58-5 is used to replace 20-8 and 58-6 is used to replace 20-9. The molecular mass determined by mass spectrometry is 248.25 (theoretical value: 248.12).

[0064] Synthesis of 58-8: Under a nitrogen atmosphere, 58-7 (1.7 g, 7 mmol), 4 M HCl (17.5 mL, 70 mmol), and 10 mL acetonitrile were added to a 250 mL three-necked flask, and the mixture was stirred thoroughly. The reaction system was cooled to 0 °C, and at this temperature, an aqueous solution of NaNO2 (7.7 mL, 7.7 mmol, 1 M) was slowly added dropwise, with stirring continuing for 45 minutes. Subsequently, an aqueous solution of KI (8.8 mL, 17.5 mmol, 2 M) was added dropwise to the reaction system at 0 °C, and the mixture was stirred at 0 °C for 5 minutes. The reaction was then continued to be stirred at room temperature for 2 hours until complete. The mixture was extracted with ethyl acetate, dried over anhydrous sodium sulfate, and the organic phase was removed by rotary evaporation under reduced pressure. The crude product was purified by silica gel column chromatography to obtain 58-8 (1.9 g, 76%), with a molecular weight determined by mass spectrometry of 359.16 (theoretical value: 359.00).

[0065] Synthesis of 58-9: Under a nitrogen atmosphere, 58-8 (1.8 g, 5 mmol) was placed in a 250 mL three-necked flask and dissolved in dichloromethane (DCM) (20 mL, 0.25 M). Subsequently, m-chloroperoxybenzoic acid (m-CPBA) (2.03 g, 10 mmol) was added in multiple portions. After m-CPBA was completely dissolved, the reaction solution was cooled to 0 °C, and trifluoromethanesulfonic acid (TfOH) (1.3 mL, 15 mmol) was added dropwise at this temperature. After the addition was complete, the reaction system was brought back to room temperature and stirred at room temperature for 2 hours. After the reaction was complete, dichloromethane was removed under reduced pressure using a rotary evaporator. Then, diethyl ether was added to the reaction residue, and the mixture was stirred at room temperature for 30 minutes. The residue was then filtered to obtain a filter cake, which was washed with diethyl ether several times. The filter cake was collected and dried in a vacuum oven to obtain 58-9 (1.6 g, 65%). The molecular weight determined by mass spectrometry was 507.19 (theoretical value: 507.06).

[0066] Synthesis of 58-10: Under a nitrogen atmosphere, 58-9 (5.1 g, 10 mmol), potassium tert-butoxide (KOt-Bu) (4.5 g, 40 mmol), Se (2.4 g, 30 mmol), and 200 mL of dimethyl sulfoxide (DMSO) were added to a 500 mL three-necked flask. The resulting mixture was stirred at 100 °C for 2 hours. After the reaction system was cooled to room temperature, 15 mL of water was added. The reaction mixture was extracted with ethyl acetate, and the organic layers were combined and dried over anhydrous sodium sulfate. The organic phase was purified by column chromatography after removing the solvent under reduced pressure using a rotary evaporator, yielding 58-10 (2.4 g, 77%) with a molecular weight determined by mass spectrometry of 309.92 (theoretical value: 310.06).

[0067] Synthesis of 58-11: 12.7 g (41 mmol) of 58-10 was placed in a 1 L three-necked flask, and anhydrous tetrahydrofuran (THF) (400 mL) solution was added. Nitrogen gas was purged three times. At -78 °C, lithium isopropylaminolithium (LDA) (2.0 M, 49 mmol) was added dropwise to the reaction solution. After stirring for 1 hour at the same temperature, 21 g (82 mmol) of iodine in THF (200 mL) solution was added dropwise to the reaction system. The reaction mixture was stirred at -78 °C for another 1 hour and then gradually brought to room temperature. The reaction solution was quenched with HCl (3M, 100mL), and stirring was continued for 0.5h. The organic layer was separated, the aqueous layer was extracted with ethyl acetate, the organic phase was collected, and dried with anhydrous Na2SO4. After drying, the solvent was removed by rotary evaporation under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain 58-11 (15.0g, 84%). The molecular weight determined by mass spectrometry was 435.81 (theoretical value: 435.96).

[0068] The synthesis methods of 58-12 and 20-5 are the same, the difference being that 58-11 replaces 20-4 and 58-4 replaces 20-3. The molecular mass determined by mass spectrometry is 507.16 (theoretical value: 507.32).

[0069] The synthesis methods of 58-13 and 20-6 are the same, except that 20-5 is replaced by 58-12. The molecular mass determined by mass spectrometry is 426.27 (theoretical value: 426.41).

[0070] The synthesis method of 58-14 is the same as that of 1-7. The difference is that 1-3 is replaced by 58-2. The molecular mass determined by mass spectrometry analysis is 596.81 (theoretical value: 596.68).

[0071] Compound 58 was synthesized using the same method as compound 1, except that 1-7 was replaced with 58-14. The molecular mass determined by mass spectrometry was 1002.95 (theoretical value: 1003.08).

[0072] Example 4: Synthesis of Compound 100

[0073]

[0074] The synthesis methods of 100-3 and 20-10 are the same, except that 100-1 is used to replace 20-8 and 100-2 is used to replace 20-9. The molecular mass determined by mass spectrometry analysis is 410.46 (theoretical value: 410.35).

[0075] The synthesis methods of 100-4 and 20-3 are the same, except that 100-3 is used instead of 20-2. The molecular mass determined by mass spectrometry is 346.34 (theoretical value: 346.47).

[0076] The synthesis methods of 100-5 and 20-5 are the same, except that 20-3 is replaced by 100-4. The molecular mass determined by mass spectrometry is 456.87 (theoretical value: 457.01).

[0077] The synthesis methods of 100-6 and 20-6 are the same, except that 100-5 is used instead of 20-5. The molecular mass determined by mass spectrometry is 420.71 (theoretical value: 420.55).

[0078] The synthesis of compound 100 was the same as that of compound 1, except that 58-14 replaced 1-7 and 100-6 replaced 1-8. The molecular mass determined by mass spectrometry was 997.36 (theoretical value: 997.23).

[0079] Example 5: Synthesis of Compound 128

[0080]

[0081] The synthesis method of 128-3 is the same as that of 1-3. The difference is that 128-1 is used instead of 1-1 and 128-2 is used instead of 1-2. The molecular mass determined by mass spectrometry is 284.49 (theoretical value: 284.32).

[0082] Synthesis of 128-6: Under nitrogen atmosphere, 128-4 (2.0 g, 10 mmol) and 128-5 (3.0 g, 22 mmol) were dissolved in dimethyl sulfoxide (DMSO) (100 mL) in a 250 mL three-necked flask. Potassium carbonate (5.5 g, 40 mmol) was then added to the reaction mixture, and the mixture was heated and stirred at 100 °C for 4 hours. After cooling, the reaction mixture was poured into water, and the aqueous layer was extracted with ethyl acetate. The organic mixture was washed with water and brine, and the organic phase was collected and dried over anhydrous sodium sulfate. After filtration, the organic phase was evaporated using a rotary evaporator to remove organic reagents. Recrystallization from the organic phase with methanol yielded 128-6 (3.3 g, 75%), with a molecular weight determined by mass spectrometry of 433.69 (theoretical value: 433.55).

[0083] Synthesis of 128-7: Under nitrogen atmosphere, 128-6 (10.8 g, 25 mmol), palladium trifluoroacetate (Pd(TFA)2) (0.8 g, 2.5 mmol), silver acetate (AgOAc) (16.7 g, 100 mmol), potassium carbonate (3.5 g, 25 mmol), and tertival acid (PivOH) (50 mL) were added to a 500 mL three-necked flask. The mixture was stirred at 130 °C for 24 hours. After the reaction was complete, the reaction mixture was cooled to room temperature, and dichloromethane and water were added for separation. The organic phase was collected, and the filtrate was concentrated using a rotary evaporator. The concentrated crude product was purified by column chromatography to obtain 128-7 (4.6 g, 43%). The molecular weight determined by mass spectrometry was 429.63 (theoretical value: 429.52).

[0084] The synthesis of 128-8 is the same as that of 1-7, except that 1-3 is replaced by 128-3. The molecular mass determined by mass spectrometry is 580.46 (theoretical value: 580.62).

[0085] Compound 128 was synthesized using the same method as compound 1, except that 1-7 was replaced by 128-7 and 1-8 was replaced by 128-6. The molecular mass determined by mass spectrometry was 990.29 (theoretical value: 990.13).

[0086] Example 6: Synthesis of Compound 159

[0087]

[0088] The synthesis methods of 159-2 and 20-5 are the same, except that 20-4 is replaced by 159-1. The molecular mass determined by mass spectrometry is 593.44 (theoretical value: 593.58).

[0089] The synthesis methods of 159-3 and 20-6 are the same, except that 20-5 is replaced by 159-2. The molecular mass determined by mass spectrometry is 512.52 (theoretical value: 512.66).

[0090] The synthesis methods of 159-5 and 1-7 are the same, except that 1-3 is replaced by 159-4. The molecular mass determined by mass spectrometry is 540.74 (theoretical value: 540.60).

[0091] Compound 159 was synthesized using the same method as compound 1, except that 1-7 was replaced by 159-5 and 1-8 was replaced by 159-3. The molecular mass determined by mass spectrometry was 1033.13 (theoretical value: 1033.26).

[0092] Example 7: Synthesis of Compound 185

[0093]

[0094] The synthesis methods of 185-2 and 1-3 are the same, except that 1-1 is replaced by 185-1. The molecular mass determined by mass spectrometry is 300.50 (theoretical value: 300.38).

[0095] Synthesis of 185-4: Under a nitrogen atmosphere, 2,2,6,6-tetramethylpiperidine lithium (LiTMP) (26.1 mL, 153 mmol) and THF (236 mL) were added to a 1 L three-necked flask and cooled to 0 °C using an ice bath. At 0 °C, n-butyllithium (1.6 M hexane solution) (96 mL, 153 mmol) was added dropwise to the reaction solution. After the addition was complete, the mixture was stirred at 0 °C for 30 minutes. The reaction system was then cooled to -78 °C. Triisopropyl borate (B(OiPr)3) (33.3 g, 177 mmol) and 185-3 (29.2 g, 118 mmol) were added sequentially. After all the addition was complete, the reaction system was slowly heated from -78 °C to room temperature. After the reaction was complete, 100 mL of 10% hydrochloric acid was added dropwise. Subsequently, liquid-liquid extraction was performed, the organic layer was collected, and washed with petroleum ether to obtain 185-4 (22.3 g, 65%), with a molecular weight determined by mass spectrometry of 290.77 (theoretical value: 290.91).

[0096] Synthesis of 185-5: Under a nitrogen atmosphere, 185-4 (15.1 g, 52 mmol), N-chlorosuccinimide (NCS) (7.0 g, 52 mmol), cuprous chloride (I) (5.2 g, 52 mmol), and acetonitrile (174 mL) were added to a 1 L three-necked flask. The reaction mixture was heated to 60 °C and stirred for 6 hours. After the reaction was complete, 150 mL of dichloromethane and 100 mL of water were added to the reaction mixture. The organic phase was collected by separation and dried over anhydrous sodium sulfate. The organic solvent was removed under reduced pressure using a rotary evaporator. The crude product was purified by silica gel column chromatography to obtain 185-5 (10.5 g, 72%). The molecular weight determined by mass spectrometry was 281.67 (theoretical value: 281.53).

[0097] Synthesis of 185-6: Under a nitrogen atmosphere, 185-3 (12.4 g, 50 mmol), copper oxide (I) (0.1 g, 0.66 mmol), ammonia (100 mL, 30%), and N-methylpyrrolidone (NMP) (100 mL) were added to a 500 mL three-necked flask. The reaction system was slowly heated to 80 °C and stirred at this temperature for 12 hours. After the reaction was complete, the reaction system was brought to room temperature, and 300 mL of deionized water was added. The mixture was extracted with dichloromethane, and the organic phase was collected, washed with brine, and dried with anhydrous sodium sulfate. The dried organic phase was concentrated using a rotary evaporator. The crude product obtained after concentration was purified by silica gel column chromatography to obtain 185-6 (7.4 g, 81%), with a molecular weight determined by mass spectrometry of 183.35 (theoretical value: 183.21).

[0098] Synthesis of 185-8: Under a nitrogen atmosphere, 185-6 (8.2 g, 45 mmol), 185-7 (12.7 g, 45 mmol), tris(dibenzylacetone)dipalladium (0.8 g, 0.9 mmol), tri-tert-butylphosphine (P(t-Bu)3) (1.0 g, 1.8 mmol), sodium tert-butoxide (6.5 g, 68 mmol), and 400 mL of toluene were added to a 1 L three-necked flask. The reaction system was heated to 100 °C and stirred at this temperature for 8 hours. After the reaction was complete, the reaction mixture was cooled to room temperature. 300 mL of deionized water was added to the reaction system, the organic phase was collected by separation, dried with anhydrous sodium sulfate, and the organic reagents were removed by rotary evaporation under reduced pressure. The crude product was purified by silica gel column chromatography to obtain 185-8 (11.7 g, 68%), and the molecular weight determined by mass spectrometry was 383.98 (theoretical value: 383.83).

[0099] The synthesis methods of 185-9 and 20-6 are the same, except that 20-5 is replaced by 185-8. The molecular mass determined by mass spectrometry is 347.51 (theoretical value: 347.37).

[0100] The synthesis method of 185-10 is the same as that of 1-7. The difference is that 1-3 is replaced by 185-2. The molecular mass determined by mass spectrometry is 596.51 (theoretical value: 596.68).

[0101] Compound 185 was synthesized using the same method as compound 1, except that 1-7 was replaced by 185-10 and 1-8 was replaced by 185-9. The molecular mass determined by mass spectrometry was 924.18 (theoretical value: 924.05).

[0102] Example 8: Synthesis of Compound 192

[0103]

[0104] The synthesis methods of 192-3 and 20-10 are the same, except that 192-1 is used to replace 20-8 and 192-2 is used to replace 20-9. The molecular mass determined by mass spectrometry is 314.53 (theoretical value: 314.41).

[0105] The synthesis methods of 192-5 and 185-6 are the same, the difference being that 185-3 is replaced by 192-4. The molecular mass determined by mass spectrometry is 275.24 (theoretical value: 275.37).

[0106] The synthesis methods of 192-6 and 185-8 are the same, the difference being that 192-5 is used instead of 185-6. The molecular mass determined by mass spectrometry is 475.81 (theoretical value: 475.99).

[0107] The synthesis methods for 192-7 and 185-9 are the same, except that 185-8 is replaced by 192-6. The molecular mass determined by mass spectrometry is 439.36 (theoretical value: 439.53).

[0108] The synthesis method of 192-8 is the same as that of 1-7. The difference is that 192-3 is used instead of 1-3. The molecular mass determined by mass spectrometry is 610.82 (theoretical value 610.71).

[0109] Compound 192 was synthesized using the same method as compound 1, except that 1-7 was replaced with 192-8. The molecular mass determined by mass spectrometry was 1030.06 (theoretical value: 1030.24).

[0110] The synthetic examples illustrate representative synthetic routes. Where specific conditions are not specified, they were performed under standard conditions or conditions provided by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Some reaction compounds were purchased from a commercial supplier (Zhengzhou Alpha Chemical Co., Ltd.), and some compounds that could not be directly purchased were prepared by simple reactions from commercially available raw materials. Percentages refer to mass percentages, and temperatures are in degrees Celsius (°C). The principles, procedures, routine post-treatments, silica gel column chromatography, recrystallization purification, and other techniques of this method are well-known to those skilled in the art and can be fully implemented to obtain the target product. The reactions in each preparation example are generally carried out under positive pressure of nitrogen or argon.

[0111] In addition, it should be noted that other compounds in this application can be obtained by referring to the synthetic routes of the synthetic examples listed above, so they will not be listed one by one here.

[0112] Device Examples

[0113] To evaluate the luminescence performance of the compounds described in this invention in organic electroluminescent devices, a series of OLED devices based on multilayer organic thin film structures were designed and constructed, and the specific fabrication process is shown below:

[0114] Preparation of Example 1:

[0115] The glass plate coated with the ITO transparent conductive layer was ultrasonically treated in a cleaning agent, rinsed in deionized water, ultrasonically degreased in a mixed solvent of acetone and ethanol, baked in a clean environment until all moisture was removed, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam.

[0116] The treated ITO transparent conductive layer was placed in a vacuum evaporation chamber. After the system reached a high vacuum, a hole injection layer (HIL) with a thickness of 10 nm was first deposited. This layer used a co-evaporation combination of HT and HI-1 (mass ratio 97:3, w / w), with the two materials placed in different evaporation sources. Precise ratio control was achieved by adjusting the evaporation rate. This doping system aims to improve the energy level matching between the anode and the organic layer and reduce the hole injection barrier.

[0117] A 15 nm thick HT-1 layer is deposited on top of the hole injection layer as a hole transport layer (HTL). The main function of this layer is to efficiently transport holes and suppress electron back injection, maintaining a good charge balance in the device. Subsequently, a 20 nm thick HT-2 layer is deposited as an electron blocking layer (EBL) to restrict electron penetration to the hole transport layer, thereby effectively improving the exciton binding ability and recombination efficiency in the light-emitting region.

[0118] A 30nm thick light-emitting layer (EML) was deposited on the electron blocking layer using a multi-source co-evaporation process. The host material was HOST, compound 1 was the sensitizing material MH, and the dopant was GD-1. They were placed in independent evaporation sources, and the co-doped composite light-emitting film was formed by controlling their evaporation rate ratio to 49:50:1 (w / w / w).

[0119] A 5nm thick HB-1 layer is deposited on the light-emitting layer as a hole blocking layer (HBL) to block holes from escaping into the electron region and enhance the electron injection interface.

[0120] A 30 nm thick electron transport layer (ETL) was deposited on the hole blocking layer using an ET-1 and LiQ doping system (mass ratio 50:50, w / w). This combination helps to improve the electron transport rate and interface injection efficiency.

[0121] Depositing 1 nm of Yb on the electron transport layer as an electron injection layer (EIL) helps to form an interfacial dipole and improve the injection efficiency of electrons from the Al cathode to the electron transport layer.

[0122] A Mg:Ag electrode layer with a thickness of 13 nm is deposited on top of the electron injection layer, wherein the mass ratio of Mg to Ag is 1:9. This layer serves as the cathode layer.

[0123] A CP-1 layer with a thickness of 65 nm was vacuum-deposited on the cathode as a light extraction layer (CPL).

[0124] The entire organic layer and cathode evaporation process is completed in a continuous vacuum to avoid interface oxidation or contamination, with the deposition rate set to 0.1 nm / s.

[0125] In the glove box, the vapor-deposited device is coated with UV adhesive using a coating equipment. The coated cover plate is then moved to the lamination section, where the vapor-deposited substrate is placed on top of the cover plate. Finally, the substrate and cover plate are laminated using a bonding equipment and cured with UV adhesive.

[0126] Preparation of Examples 2-30:

[0127] When forming the light-emitting layer (EML), the corresponding compound in Table 2 was used to replace Compound 1 in Example 1, and the organic electroluminescent device was prepared using the same method as in Example 1.

[0128] Preparation of Comparative Examples 1-20:

[0129] Except that when forming the light-emitting layer (EML), the corresponding compound in Table 3 was used to replace Compound 1 in Example 1, the organic electroluminescent device was prepared using the same method as in Example 1.

[0130] The structures of the compounds used in the device are as follows:

[0131] ;

[0132] .

[0133] Evaluation of compounds:

[0134] The emission peak position, photoluminescence quantum yield (PLQY), and anti-intersystem crossing coefficient k of each compound in Table 1 were analyzed. RISC ) and radiative transition rate coefficient (k r ), singlet-triplet bandgap (ΔE) ST The PLQY test: Dissolve the sample in nitrogen-saturated toluene and prepare 10... -5 mol / L solution was analyzed using a Hamamatsu PLQY spectrometer; emission peak positions were determined using a fluorescence spectrometer; ΔE ST Phosphorescence and fluorescence at 77K were obtained using a HITACHI F-7000 spectrometer; k RISC and k r The results were obtained through testing and calculation using FLS1000 and are shown in Tables 1-1 and 1-2 below:

[0135] ;

[0136] .

[0137] Device evaluation:

[0138] The voltage was increased at a rate of 0.1V per second, and the brightness of the device embodiment and the comparative example was measured when they reached lcd / m². 2 The voltage at which it is turned on is 10mA / cm. 2 The driving voltage and current efficiency of the device embodiments and comparative examples were determined at a current density of 35 mA / cm². The driving voltage and current efficiency were measured using an IVL (current-voltage-luminance) testing system (Suzhou Fushida Scientific Instruments Co., Ltd.). 2 The time required for the brightness to decrease to 95% of the initial brightness at a given current density (LT95) was measured. The lifetime testing system was the OLED lifetime testing system from Suzhou Fosstar Scientific Instruments Co., Ltd.; at 10 cd / m 2 The wavelength of the maximum emission peak, the full width at half maximum (FWHM), and the corresponding CIE color coordinates were obtained. The results are shown in Tables 2-1, 2-2, and 3 below.

[0139] ;

[0140] ;

[0141]

[0142] The data in Tables 1-3 show that the series of compounds provided by this invention have good compound properties, such as a smaller band gap (ΔE). ST <0.01eV), and a higher anti-system crossing coefficient (k RISC ) and radiative transition rate (k r It also has high fluorescence quantum efficiency (PLQY) and more suitable emission peak position, which makes organic electroluminescent devices prepared using it as a sensitizer have low turn-on voltage, high current efficiency and long lifespan, thus balancing the overall performance of the device.

[0143] The above embodiments only list the effect data of devices made from a portion of the structures. This is a representative sampling test. Based on the experimental data, the overall data is not significantly different and can represent the effects of other unlisted structures.

[0144] Those skilled in the art will readily recognize that many modifications and variations can be made to this invention without departing from its spirit and scope. Therefore, it is contemplated that this invention covers the modifications and variations provided within the scope of the appended claims and their equivalents.

[0145] This invention illustrates the organic electroluminescent material and organic electroluminescent device through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A thermally activated delayed fluorescence compound, characterized in that, Its structure is shown in general formula (I): ； L is selected from single bond, substituted or unsubstituted C6-C. 12 Aromatic rings, either substituted or unsubstituted, are C3-C6 heteroaromatic rings, with each R5 independently selected from hydrogen, deuterium, or phenyl; C is selected from structure (I)-1, and D is selected from (I)-2 or (I)-3: ； X is independently selected from O, S, and Se; R is independently selected from hydrogen, deuterium, cyano, C1-C6 alkyl, substituted or unsubstituted C6-C 12 Aryl or C3-C 12 The heteroaryl group or the following groups, and at least one of C or D is an R group that is one of the following groups: ； X1 is independently selected from NR3, O, S, and Se; X2 is independently selected from N and CR4. R1 to R4 are each independently selected from hydrogen, deuterium, cyano, C1-C6 alkyl, substituted or unsubstituted C6-C6. 12 Aryl or C3-C 12 heteroaryl groups; * indicates a linking site. When substitution is present, the substituents are independently selected from deuterium, cyano, C1-C6 alkyl, C6-C6... 12 The aryl group, C3-C6 heteroaryl group, n is from 1 to the largest substitution site number of the ring, and the heteroatom is N.

2. The thermally activated delayed fluorescence compound according to claim 1, characterized in that, L can be a single bond, phenyl, naphthyl, or pyridyl.

3. The thermally activated delayed fluorescence compound according to claim 1, characterized in that, R is independently selected from hydrogen, deuterium, cyano, tert-butyl, phenyl, and pyridyl.

4. The thermally activated delayed fluorescence compound according to claim 1, characterized in that, X1 is selected independently from O or S, and X2 is selected independently from N or CR4.

5. The thermally activated delayed fluorescence compound according to claim 1, characterized in that, R1 to R4 are each independently selected from hydrogen, deuterium, cyano, methyl, tert-butyl, substituted or unsubstituted phenyl or pyridyl.

6. The thermally activated delayed fluorescence compound according to claim 1, characterized in that, When substitutions are present, the substituents are each independently selected from deuterium, cyano, methyl, tert-butyl, phenyl, and pyridyl.

7. The thermally activated delayed fluorescence compound according to any one of claims 1-6, characterized in that, The specific structure of this compound is as follows: ； ； ； ； ； ； ； ； ； 。 8. An organic electroluminescent device comprising an anode, a cathode, and an organic layer, wherein the organic layer includes a light-emitting layer, characterized in that, The luminescent layer comprises the thermally activated delayed fluorescence compound of claim 1.

9. The organic electroluminescent device according to claim 8, characterized in that, This organic electroluminescent device is used to manufacture display devices, lighting sources, signal lights, and signs. The display devices include mobile phone displays, computer displays, television displays, smartwatch displays, smart car display panels, and VR or AR helmet displays.

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