Pyrene-based red and near-infrared luminescent materials with thermally activated delayed fluorescence properties for use as doping materials in the luminescent layer.

Abstract

This invention belongs to the field of organic electroluminescent materials technology, specifically disclosing a class of red and near-infrared luminescent materials based on pyrene cores with thermally activated delayed fluorescence (TRF) properties for use as doping materials in the luminescent layer. Using pyrene as the molecular structural center, two pyrene-pyrazine derivative acceptors (symmetric and asymmetric) were constructed, and then bis(3,5-di-tert-butylphenyl)amine was used as the electron-donating group to synthesize a class of red and near-infrared luminescent materials with TRF properties. Due to the large torsion angle between the acceptor and donor, the overall planarity of the molecule is reduced, which helps to suppress molecular stacking and thus reduce exciton quenching. Furthermore, the modification of the outer tert-butyl group gives the molecule excellent solubility, enabling the fabrication of OLED devices via solution processing, and achieving the fabrication of long-wavelength 650nm solution-processed OLED devices. This is of great significance for constructing novel solution-processable red and near-infrared luminescent materials based on pyrene cores.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescent materials technology, and specifically discloses a class of red and near-infrared luminescent materials based on pyrene nuclei with thermally activated delayed fluorescence characteristics for use as doping materials in the luminescent layer. Background Technology

[0002] As one of the most important applications of near-infrared emitting materials, near-infrared OLEDs play a crucial role not only in night vision devices, optical communications, and information security displays, but also in flat panel displays and lighting equipment. Many types of emitters are employed in NIR OLEDs, such as metal complexes, conjugated polymers, and phosphorescent metal complexes. These materials endow NIR OLEDs with excellent properties, such as light weight, low power consumption, fast response time, good processing performance, wide temperature range, and low cost.

[0003] First-generation traditional fluorescent materials can only emit light using singlet excitons, with an internal quantum efficiency of 25%. This results in a theoretical maximum external quantum efficiency (EQE) of only 5% for fluorescent OLED devices, hindering their commercialization and limiting further development. In search of a breakthrough, in 1998, Princeton University's Forrest Gump...

[0004] Organic electroluminescent materials based on the metal complex porphyrin platinum were developed, marking the emergence of second-generation organic electroluminescent materials—phosphorescent materials. Because these materials can fully utilize singlet and triplet excitons for luminescence, they can achieve a theoretical internal quantum efficiency of 100%, significantly improving the luminescence efficiency of the materials.

[0005] Compared to fluorescent materials, phosphorescent materials exhibit lower driving voltage and higher efficiency. Their vividness, color saturation, and high contrast in the display field have enabled their commercialization. However, significant cost and stability issues have led to the development of third-generation organic light-emitting materials—thermally active delayed fluorescence (TADF) materials. In 2009, the Adachi team first demonstrated the application of TADF materials in OLEDs, bringing about a significant transformation in OLED development. These materials are free of heavy metals and can achieve 100% internal quantum efficiency (IQE), earning them the title of third-generation organic light-emitting materials. They are also more cost-effective and environmentally friendly, making them more conducive to the industrialization of OLEDs and a key research direction in organic electroluminescent materials.

[0006] Professor Wang Yue and colleagues reported the first NIR TADF molecule, TPA-DCPP, in 2015. They selected the pyrazine derivative 2,3-dicyanopyrazinephenanthrene (DCPP), with its extended conjugated structure, as an electron-withdrawing molecule. The efficient HOMO-LUMO separation and partial orbital overlap resulting from the D-π-A-π-D configuration ensured the ΔE of TPA-DCPP.ST As low as 0.13 eV and 9.0 × 10 -7 s -1 Big K f Value. It exhibits broad near-infrared emission, with a maximum wavelength of 708 nm, and Φ in the pure thin film. PL The value is 14%. However, the undoped OLED devices based on TPA-DCPP, fabricated using vacuum evaporation, exhibit a maximum EQE of 2.1% and an EL peak at 710 nm.

[0007] Liao and his colleagues developed a novel TADF material using a new acceptor, dibenzo[a,c]phenazine-3,6-dicarboxynitrile (PZCN). The material's large, planar structure helps suppress nonradiative transitions. In 2021, they designed and synthesized a series of highly efficient red / DR TADF materials. By introducing pyridinyl (PY) groups into trifluoromethyl (CF3) and cyano (CN) groups, they effectively modulated the emission wavelength in the DR region. The incorporation of molten polycyclic aromatic hydrocarbons (dibenzo[a,c]phenazine) significantly suppressed the internal conversion (IC) process in these materials. However, due to the introduction of rigid conjugated groups, the material's solubility decreased significantly, requiring vacuum evaporation for device fabrication.

[0008] The above research reveals that most OLED devices made with TADF materials are currently fabricated using vacuum evaporation, especially for long-wavelength materials (red-near-infrared materials). Due to the increased conjugation of these materials, their solubility significantly decreases. This method often leads to raw material waste, high costs, and complex processes during mass production. Solution-based fabrication of devices still requires further development. Summary of the Invention

[0009] To expand the design of efficient and solution-processable red and near-infrared TADF materials, this invention uses pyrene, with its excellent physicochemical properties, as the molecular structural center. Two pyrene-pyrazine derivative acceptors (symmetric and asymmetric) were designed, and then bis(3,5-di-tert-butylphenyl)amine was used as a solubilizing electron-donating group to synthesize a class of solution-processable red and near-infrared luminescent materials based on pyrene-pyrazine acceptors with thermally activated delayed fluorescence properties. These materials have the following structure:

[0010]

[0011] The preferred structure of this type of material is shown in the following formula:

[0012]

[0013] By modifying the structure of the pyrene nucleus, two pyrene-pyrazine derivative acceptor groups (symmetric and asymmetric) were constructed, and bis(3,5-di-tert-butylphenyl)amine was used as a solubilizing electron-donating group. The asymmetric acceptor nucleus provides stronger electron-withdrawing ability and also provides some inert groups, increasing the solubility of the molecule and suppressing the planar stacking of the rigid acceptor portion; the symmetric acceptor nucleus has better solubility, but its electron-withdrawing ability is relatively weaker. Two TADF molecules were designed using these two acceptor nuclei, and their photophysical-structural relationship and applications were investigated.

[0014] Another objective of this invention is to provide the application of red and near-infrared luminescent materials with symmetric and asymmetric acceptor nuclei as doping materials for the luminescent layer of organic light-emitting diodes, thereby obtaining red solution-processed organic light-emitting devices with excellent luminescent performance.

[0015] The main material of the light-emitting layer of the electroluminescent device is TCTA.

[0016] The luminescent material is doped at a mass ratio of 1-3% in the luminescent layer.

[0017] The technical advantages of this invention patent are:

[0018] 1. Taking advantage of the ease of modification of pyrene nuclei and their excellent physicochemical properties, such as excellent thermal stability, high fluorescence quantum yield, and ease of forming electroexcitogenic complexes, a series of novel red and near-infrared luminescent materials with asymmetric and symmetric acceptor nuclei are constructed.

[0019] 2. Using pyrene-pyrazine derivatives (symmetric and asymmetric) as strong electron acceptors and bis(3,5-di-tert-butylphenyl)amine as electron donors, the two are coupled through reactions such as bromination and Buchwald-Hartwig coupling. The resulting structure is more conducive to twisting the molecular acceptor and donor, thereby achieving effective separation of the leading orbitals, specifically the separation of the highest occupied orbital (HOMO) and the lowest unoccupied orbital (LUMO). This helps reduce ΔE. ST It is easy to obtain TADF properties, which further improves the luminescence efficiency of the material. At the same time, the molecular charge transfer process is enhanced, which is more conducive to achieving redshift of emission.

[0020] 3. The effects of electron-withdrawing ability and different acceptor core structures on the overall molecular properties were systematically studied, which is of great significance for constructing novel red and near-infrared luminescent materials based on pyrene nuclei.

[0021] The advantages of this invention are:

[0022] On the one hand, the large torsion angle between the acceptor and donor reduces the overall planarity of the molecule, which helps suppress molecular stacking and thus reduces exciton quenching. On the other hand, the modification with the outer tert-butyl group gives the molecule excellent solubility (in chlorobenzene, the solubility can reach greater than 10 mg / mL under heating conditions), enabling the fabrication of OLED devices via solution processing. Furthermore, high-efficiency fabrication of long-wavelength 650 nm solution-processed OLED devices has been achieved. This expands the research on near-infrared emitters. The influence of electron-withdrawing ability and different acceptor nuclei structures on the overall molecular performance is of great significance for constructing novel red and near-infrared luminescent materials based on pyrene nuclei. Attached Figure Description

[0023] 【 Figure 1 The compound PB-4tBuDPA obtained in Example 1 of this invention is: in toluene solution (10 -5 The ultraviolet-visible absorption (UV) and photoluminescence spectrum (PL) of M).

[0024] 【 Figure 2 The compound PBCN-4tBuDPA obtained in Example 1 of this invention was prepared in toluene solution (10... -5 The ultraviolet-visible absorption (UV) and photoluminescence spectrum (PL) of M).

[0025] 【 Figure 3 [Image caption: Delay lifetime curve of compound PB-4tBuDPA prepared in Example 1 of this invention in a 1wt% TCTA-doped thin film.]

[0026] 【 Figure 4 [Image of compound PB-4tBuDPA prepared in Example 1 of this invention: Electroluminescence spectrum (EL) of the device body TCTA and compound PBCNT as dopant (a); Relationship between brightness and maximum external quantum efficiency (b); Molecular structure diagram of the main emitting layer compound TCTA (c).]

[0027] 【 Figure 5 [Image caption: Electroluminescence spectrum (EL) of compound PBCN-4tBuDPA prepared in Example 1 of this invention: the device body is TCTA, and compound PBCNT is used as a dopant.]

[0028] [Figure 6] shows the 1H NMR spectrum of the compounds PBCN-4tBuDPA and the intermediate of PB-4tBuDPA obtained in Example 1 of this invention. 1 H NMR)(af).

[0029] [Figure 7] shows the 1H NMR spectra of compounds PB-4tBuDPA(a) and PBCN-4tBuDPA(b) prepared in Example 1 of this invention. 1 H NMR). Detailed Implementation

[0030] The following specific implementation examples are intended to further illustrate the present invention, but these specific implementation examples do not limit the scope of protection of the present invention in any way.

[0031] Example 1

[0032] The synthesis scheme of red and near-infrared luminescent materials based on the present invention is as follows:

[0033]

[0034] Synthesis of compound M1:

[0035] At room temperature, 2.0 g (9.6 mmol) of pyrene, 246 mg (1.15 mmol) of ruthenium trichloride, 40 mL of acetonitrile (CH3CN), 40 mL of dichloromethane (CH2Cl2), 50 mL of H2O, and a magnet were added to a 500 mL double-necked flask. Sodium periodate (NaIO4) was added in three portions (16.9 g, 79 mmol). The dark brown reaction solution was reacted at 35 °C for 12 h. After the reaction was complete, the reaction mixture was washed with 200 mL of H2O and filtered to remove insoluble organic matter. The filtrate was extracted three times with CH2Cl2 (3 × 100 mL) and washed three times with water (3 × 100 mL). The solution was dried over anhydrous magnesium sulfate and filtered to obtain a dark orange solution. The solvent was removed by vacuum distillation to obtain a dark orange solid. Using pure CH2Cl2 as the eluent, column chromatography was performed to obtain 550 mg of pure product, orange solid M1 (pyrene-4,5,9,10-tetraone), with a yield of 21%. 1 H NMR (400MHz, CDCl3) δ (ppm) 8.52 (d, J = 7.6 Hz, 4H), 7.73 (t, J = 7.6 Hz, 2H).

[0036] Synthesis of compound M2:

[0037] Take a clean and dry 100 mL double-necked flask and add 2.0 g of pyrene-4,5,9,10-tetraone (M1) (7.6 mmol) and 20 mL of concentrated H2SO4. Place the apparatus in a thermostatic magnetic stirrer and add 3.4 g (19.0 mmol) of N-bromosuccinimide (NBS) in three portions over 15 minutes at room temperature. Then, heat to 60 °C and react overnight. After the reaction is complete, cool to room temperature and slowly add to ice water. Stir for 30 min, filter, and wash the filter cake with boiling water to obtain a yellow filter cake. Recrystallize from CH2Cl2 and methanol (CH3OH) to obtain 2.8 g of yellow powder M2 (2,7-dibromo-pyrene-4,5,9,10-tetraone), with a yield of 90%. 1 H NMR (400MHz, DMSO) δ (ppm) 8.36 (s, 4H).

[0038] Synthesis of compound M3:

[0039] 1.0 g of M2 (2,7-dibromo-pyrene-4,5,9,10-tetraone) (1.0 g, 2.3 mmol) and p-toluenesulfonic acid monohydrate (546.0 mg, 2.8 mmol), along with ethylene glycol (37.0 g, 0.6 mol) dissolved in anhydrous toluene, were added to a 250 mL three-necked flask. The apparatus was placed in a thermostatic magnetic stirrer, and a water separator was installed (to separate water produced during the reaction). The reaction was carried out at 140 °C for 48 h under N2 protection. After the reaction was completed, the mixture was cooled to room temperature, and a large amount of methanol was added until a solid precipitated. The solid was filtered, and the filter cake was dried to obtain 960.0 mg of pale yellow powder M3, with a yield of 70%. 1 H NMR (400MHz, CDCl3) δ7.85 (s, 4H), 4.17 (s, 8H), 3.62 (s, 8H).

[0040] Synthesis of compound M4:

[0041] In a clean and dry 250 mL single-necked flask, add 4-tert-butylphenylboronic acid (1.0 g, 5.6 mmol), 4,5-dibromo-o-phenylenediamine (750 mg, 1.75 mmol), Pd(PPh3)4 (170.0 mg, 0.15 mmol), and K2CO3 aqueous solution (2 mol / L, 7.5 mmol), along with 60 mL of 1,4-Dioxane. Place the apparatus in a thermostatically controlled magnetic stirrer and react at 110 °C under nitrogen protection for 24 h. After the reaction is complete, cool to room temperature, remove the organic solvent 1,4-Dioxane by vacuum distillation, and extract with CH2Cl2. Combine the organic phases, dry with anhydrous magnesium sulfate, and elute with pure CH2Cl2. Separate by column chromatography to obtain a gray solid, recrystallize from CH2Cl2 and CH3OH to give 490.0 mg of white powder product M6, with a yield of 70%. 1 H NMR (400MHz, CDCl3) δ (ppm) 7.17 (d, J = 8.3 Hz, 4H), 7.01 (d, J = 8.3 Hz, 4H), 6.78 (s, 2H), 3.46 (s, 4H), 1.28 (s, 18H).

[0042] Synthesis of compound M5:

[0043] Add 1-bromo-3,5-tert-butylbenzene (1.5 g, 5.57 mmol) and 3,5-di-tert-butylaniline (1.5 g, 7.24 mmol), tris(dibenzylacetone)palladium (Pd2(dba)3) (306.0 mg, 0.33 mmol), tri-tert-butylphosphine tetrafluoroborate (TBPBF4) (191.0 mg, 0.66 mmol), and sodium tert-butoxide (1.6 g, 16.71 mmol) to a 100 mL double-necked flask, dissolve in 50 mL anhydrous toluene, and then... Under vacuum, the apparatus was placed in a thermostatic magnetic stirrer and stirred for 24 hours at 110°C under argon protection. After the reaction was completed, the mixture was cooled to room temperature, the organic solvent was removed by vacuum distillation, and the mixture was extracted with CH2Cl2. The organic phases were combined, dried with anhydrous magnesium sulfate, and the organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed using PE and CH2Cl2 as eluents (volume ratio = 6:1) to obtain a white solid. Further recrystallization with CH2Cl2 and CH3OH yielded 1.65 g of white powder M5, with a yield of 68%. 1 H NMR (400MHz, CDCl3) δ6.97 (s, 6H), 5.74 (s, 1H), 1.31 (s, 36H).

[0044] Synthesis of compound M6:

[0045] Add M3 (807.0 mg, 1.35 mmol), M5 (1.3 g, 3.36 mmol), tris(dibenzylacetone)palladium (Pd2(dba)3) (74.0 mg, 0.081 mmol), 2-biscyclohexylphosphine-2',4',6'-triisopropylbiphenyl (X-Phos) (77.0 mg, 0.162 mmol), and potassium tert-butoxide (608.0 mg, 5.4 mmol) to a 100 mL double-necked flask, dissolve in 50 mL of anhydrous toluene, evacuate, place the apparatus in a thermostatic magnetic stirrer, and stir for 12 h at 115 °C under argon protection. After the reaction was completed, the mixture was cooled to room temperature, the organic solvent was removed by vacuum distillation, and the mixture was extracted with CH2Cl2. The organic phases were combined, dried with anhydrous magnesium sulfate, and the organic solvent was removed by rotary evaporation under reduced pressure. The mixture was separated by column chromatography using PE and CH2Cl2 as eluents (volume ratio = 2:1) to obtain a green solid. The solid was further recrystallized with CH2Cl2 and CH3OH to obtain 1.12 g of purplish-black powder M6, with a yield of 68%. 1 H NMR (400MHz, CD2Cl2) δ7.23(s,4H),7.04(s,4H),6.87(s,8H),3.93(s,8H),3.57(s,8H),1.16(s,72H).

[0046] Synthesis of compound M7:

[0047] Compound M6 (1.0 g, 0.8 mmol) and 100 mL of trifluoroacetic acid (TFA) were added to a 250 mL three-necked flask and the mixture was evacuated. The apparatus was placed in a thermostatic magnetic stirrer and stirred at room temperature for 36 h under argon protection. After the reaction was completed, the mixture was cooled to room temperature, and 200 mL of ice water was added. A black solid precipitated, which was filtered, and the filter cake was washed with CH2Cl2. The filtrate was collected, and the organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed using PE and CH2Cl2 as eluents (volume ratio = 1:1) to obtain a blue-black solid. Further recrystallization with CH2Cl2 and CH3OH yielded 780.0 mg of blue-black powder M7, with a yield of 93%. 1 H NMR (400MHz, CDCl3) δ8.06 (s, 4H), 7.18 (s, 4H), 6.92 (s, 8H), 1.25 (s, 72H).

[0048] Synthesis of compounds PBCN-4tBuDPA and PB-4tBuDPA:

[0049] Compounds M7 (200.0 mg, 0.19 mmol), M4 (78.0 mg, 2.1 mmol), 60 mL of CHCl3, and 15 mL of acetic acid were added to a 250 mL three-necked flask, with M4 dissolved in CHCl3. The mixture was added dropwise over 3 hours using a constant-pressure dropping funnel. The flask was then evacuated and placed in a constant-temperature magnetic stirrer. The mixture was stirred for 8 hours at 85 °C under argon protection. A sample was taken to check if M7 had reacted completely. After the reaction was complete, excess diaminomaleonitrile was added, and the reaction was continued for another 15 hours. After the reaction was completed, the mixture was cooled to room temperature, and the organic solvent was removed by vacuum distillation and extracted with CH2Cl2. The organic phases were combined, dried with anhydrous magnesium sulfate, and the organic solvent was removed by rotary evaporation under reduced pressure. Column chromatography was performed using PE and CH2Cl2 as eluents (volume ratio = 3:1) to separate a red solid and a purplish-red solid. Further recrystallization with CH2Cl2 and CH3OH yielded 70.0 mg of purplish-black powder PBCN-4tBuDPA (40% yield) and 80.0 mg of red powder PB-4tBuDPA (24.5% yield). PBCN-4tBuDPA:1H NMR (400MHz, CDCl3) δ9.64 (s, 2H), 9.16 (s, 2H), 8.20 (s, 2H), 7.29 (d, J = 8.1Hz, 4H ),7.20(s,12H),7.14(d,J=8.0Hz,4H),1.33(s,18H),1.30(s,72H).PB-4tBuDPA: 1 H NMR (400MHz, CDCl3) δ8.21 (s, 4H), 7.32–7.25 (m, 20H), 7.15 (d, J = 8.0Hz, 12H), 1.33 (s, 36H), 1.29 (s, 72H).

[0050] Example 2

[0051] The compounds PBCN-4tBuDPA and PB-4tBuDPA from Example 1 were dissolved in chlorobenzene and heated to 85°C, and their solubilities were 10 mg / mL and 16 mg / mL, respectively.

[0052] The compounds PBCN-4tBuDPA and PB-4tBuDPA from Example 1 were dissolved in toluene to prepare a 10 -5 Solution M was used to test its ultraviolet-visible absorption (UV) and photoluminescence (PL) spectra. (The text abruptly ends here.) Figure 1It can be seen that the UV-Vis absorption spectrum of compound PB-4tBuDPA in solution exhibits approximately two different absorption peaks: a strong absorption peak at short wavelengths (300-406 nm) mainly attributed to π-π* transitions within the molecule; and a weak absorption peak at long wavelengths (502 nm) attributed to charge transfer (ICT) transitions from electron-donating to electron-withdrawing units within the molecule. Figure 1 As shown, the compound PB-4tBuDPA has a maximum emission peak at 645 nm, in the red light region. Figure 2 It can be seen that the UV-Vis absorption spectrum of compound PBCN-4tBuDPA in solution has approximately two types of absorption peaks: the absorption peak at short wavelengths (280-354 nm, 413 nm) is mainly attributed to the π-π* transition absorption of the molecule; the absorption peak at long wavelengths (521 nm) is attributed to the charge transfer (ICT) transition absorption peak from the donor unit to the acceptor unit within the molecule. For example... Figure 2 As shown, the maximum emission peak of compound PBCN-4tBuDPA is 745 nm, which is in the near-infrared region.

[0053] Example 3

[0054] The fluorescence lifetime of compound PB-4tBuDPA in Example 1 was tested in a vacuum atmosphere in a 1 wt% TCTA-doped thin film, as shown in the figure. Figure 3 As shown, the retardation lifetime of PB-4tBuDPA is 7.3 μs, and the retardation component accounts for 78.8% of the total.

[0055] Example 4

[0056] Application of compounds PB-4tBuDPA and PBCN-4tBuDPA in Example 1 in organic light-emitting diodes (OLEDs). These compounds were used as dopants in the emitting layer of the device, which had a structure of ITO / PEDOT:PSS (35nm) / PVK (60nm) / EML (35nm) / DPEPO (6nm) / TmPyPB (55nm) / LiF (0.5nm) / Al (100nm) OLED. In this structure, PEDOT:PSS is the hole injection layer; PVK is the hole transport layer; DPEPO is the hole blocking layer; TmPyPB is the electron transport layer; and LiF / Al is the cathode. EML is the emitting layer, comprising TCTA (the host material) and either PB-4tBuDPA or PBCN-4tBuDPA (the dopant), with doping concentrations of 1, 2, and 3 wt% in the emitting layer. Figure 4As shown in (a), PB-4tBuDPA was used as a dopant, and the electroluminescence spectra of the device at this doping ratio are displayed at 652 nm, 652 nm, and 654 nm, all in the deep red region. The devices doped with PB-4tBuDPA at 1, 2, and 3 wt% achieved maximum external quantum efficiencies of 11.1%, 15.2%, and 9.8%, respectively. Figure 4 As shown in (b); the molecular structure of the compound TCTA is as follows: Figure 4 As shown in (c). However, compound PBCN-4tBuDPA exhibits poor performance, with an EL peak at 706 nm and a maximum EQE not exceeding 1%. Figure 5 As shown.

[0057] Device solution fabrication method: The substrate is pretreated with oxygen plasma to enhance the functionality of the ITO thin film. Then, PEDOT:PSS is spin-coated onto the ITO substrate at 3200 rpm for 30 seconds and annealed at 150°C for 15 minutes to obtain a 35 nm thick hole injection layer. PVK is prepared at 10 mg / mL and then spin-coated onto the hole injection layer as a hole transport layer. A prepared host-guest mixture solution (doping amounts of the light-emitting layer dopant are 1, 2, and 3 wt%, with chlorobenzene as the solvent) is spin-coated onto the hole transport layer at 80°C and then annealed for 30 minutes. DPEPO, TmPyPB, and LiF / Al cathodes are then sequentially deposited onto the light-emitting layer, hole blocking layer, and electron transport layer to obtain a device containing the light-emitting molecules of this invention.

[0058] Example 5

[0059] The proton NMR spectra of compounds PBCN-4tBuDPA and key intermediates M1-3 and M5-7 in Example 1 are shown in Figure 6(af).

[0060] Example 6

[0061] Figure 7 shows the 1H NMR spectra of compounds PB-4tBuDPA(a) and PBCN-4tBuDPA(b) from Example 1.

[0062] Although the invention has been described in conjunction with preferred embodiments, the invention is not limited to the above embodiments, and it should be understood that the appended claims summarize the scope of the invention. Guided by the inventive concept, those skilled in the art should recognize that any modifications made to the various embodiments of the invention will be covered by the spirit and scope of the claims.

Claims

1. A class of red and near-infrared luminescent materials based on pyrene nuclei and possessing thermally activated delayed fluorescence properties, characterized in that: The molecular structure of the luminescent material is shown in the following formula:

2. The red and near-infrared luminescent material based on pyrene nuclei with thermally activated delayed fluorescence properties as described in claim 1, characterized in that: The molecular structure of the luminescent material is shown in the following formula:

3. An application of the red and near-infrared luminescent material based on pyrene nuclei with thermally activated delayed fluorescence properties as described in claim 1, characterized in that: The red and near-infrared luminescent materials with thermally activated delayed fluorescence properties are used as doping materials for the luminescent layer of organic light-emitting diodes.

4. The application of the red and near-infrared luminescent material based on the pyrene nucleus with thermally activated delayed fluorescence properties as described in claim 3, characterized in that: The main material of the light-emitting layer is TCTA.

5. The application of the red and near-infrared luminescent material based on pyrene nuclei with thermally activated delayed fluorescence properties as described in claim 3, characterized in that: The red and near-infrared luminescent materials with thermally activated delayed fluorescence properties are doped in the luminescent layer at a mass ratio of 1-3%.

6. The application of the red and near-infrared luminescent material based on the pyrene nucleus with thermally activated delayed fluorescence properties as described in claim 3, characterized in that: The organic light-emitting diode is fabricated using a solution processing method.

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