Bis-keto thermal-activated delayed fluorescence material and applications thereof

Abstract

This invention relates to a class of thermally activated delayed fluorescence materials containing dicarbonyl groups and their applications, belonging to the field of electroluminescent materials technology. The material uses a dicarbonylquinoline group with intramolecular hydrogen bonding and a twisted spatial configuration as its core, introducing O, S, and Se atoms at the meta position of the carbonyl group. By utilizing heteroatom and heavy atom effects, the electronic structure and excited-state properties of the molecule are precisely controlled, increasing the spin-orbit coupling (SOC) strength of the molecule. While maintaining a small energy level difference, it increases the anti-system crossing rate, thereby promoting a balance between the anti-system crossing rate and the radiative transition rate. Furthermore, the intramolecular hydrogen bonds enhance the molecule's rigidity, suppressing excited-state vibrational relaxation, thus achieving high fluorescence quantum yield and narrow-band emission, thereby improving luminescence efficiency. The material of this invention exhibits excellent optoelectronic properties, providing an ideal material solution for fabricating high-efficiency and low-roll-off OLED devices.

Description

Technical Field

[0001] This application relates to the field of organic materials, and in particular to a method for synthesizing a class of thermally activated delayed fluorescence materials containing dicarbonyl groups and their applications. Background Technology

[0002] Organic light-emitting diodes (OLED devices), as a next-generation display technology, have become a core direction for display technology upgrades due to their advantages such as light weight, energy efficiency, and flexibility, and are widely used in smartphones, televisions, and lighting. Organic light-emitting materials, as the core functional components of OLED devices, directly determine the device's photoelectric efficiency, stability, and lifespan, and are crucial for the commercialization of OLED technology. Currently, organic light-emitting materials are mainly classified into three categories based on their light-emitting mechanism: traditional fluorescent materials, heavy metal complex phosphorescent materials, and thermally activated delayed fluorescence materials (TADF).

[0003] Traditional fluorescent materials can only utilize 25% of singlet excitons generated by electrical excitation, resulting in extremely low theoretical quantum efficiency, which is insufficient to meet the demands of high-brightness and high-efficiency displays. While heavy metal complex phosphorescent materials (such as iridium and platinum complexes) can achieve 100% exciton utilization through spin-orbit coupling, their complex synthesis processes, high cost of heavy metals, and potential environmental risks limit their large-scale mass production and application. Thermally activated delayed fluorescence (TADF) materials, however, have become a research hotspot in the field of organic light-emitting materials due to their unique luminescence mechanism. In their molecular structure, electron donors (D) and electron acceptors (A) form a spatially twisted configuration through a specific connection, resulting in a high degree of separation between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), thus achieving extremely low singlet-triplet splitting energies. By converting triplet excitons into singlet excitons through reverse system crossing (RISC) to participate in luminescence, 100% exciton utilization can theoretically be achieved, without heavy metals and with low synthesis costs. This perfectly balances efficiency and economy, and is considered the core development direction for next-generation OLED light-emitting materials.

[0004] However, existing TADF materials still face many technical bottlenecks that restrict their industrial application in OLED devices. For example, the donor-acceptor structure matching of most TADF materials is insufficient, leading to Δ E ST Limited control precision; although some materials achieve small Δ... E ST However, it suffers from low luminescence quantum yield; simultaneously, insufficient molecular rigidity, excessive crystallinity, or poor solubility can easily lead to poor film formation quality during device fabrication, resulting in defects such as pinholes and phase separation. Therefore, developing molecularly controllable quantum yields with high luminescence yield is crucial. E STNovel TADF materials with precise control, high luminous efficiency, excellent thermal stability and carrier transport performance have become a key requirement for breaking through the current bottlenecks of OLED technology and promoting its large-scale commercialization. Summary of the Invention

[0005] The purpose of this invention is to provide a class of thermally activated delayed fluorescence materials containing dicarbonyl groups. By using heteroatoms and heavy atoms (O, S, and Se) in conjunction with dicarbonyl-containing quinoline as acceptor units, a small singlet-triplet energy level difference (Δ) is achieved. E ST Simultaneously, it enhances the self-selected orbital coupling (SOC) strength and promotes efficient reverse intersystem crossing (RISC). Furthermore, it effectively suppresses excited-state structural relaxation by utilizing intramolecular hydrogen bonding in dicarbonylquinoline, thereby achieving narrow-band emission and high color purity, and resulting in a higher external quantum efficiency (EQE) for the final fabricated OLED device. The technical solution of this invention is as follows: The present invention discloses a thermally activated delayed fluorescence material containing a dicarbonyl group, wherein the organic compound has the structures shown in T1, T2, and T3:

[0006] A method for preparing the aforementioned thermally activated delayed fluorescence material containing dicarbonyl groups:

[0007] S1. Under nitrogen protection, compound B, compound C, tris(dibenzylacetone)dipalladium, tri-tert-butylphosphine tetrafluoroborate, sodium tert-butoxide and anhydrous toluene were added to a dry three-necked flask. The molar ratio of compound B, compound C, tris(dibenzylacetone)dipalladium, tri-tert-butylphosphine tetrafluoroborate, and sodium tert-butoxide is 1:1.2:(0.05-0.08):(0.2-0.4):4; S2. Stir at 100-120℃ for 10-14 hours. After the reaction is complete, remove the solvent by vacuum distillation, extract, purify by column chromatography, and recrystallize to obtain the target product.

[0008] The preparation method of the above-mentioned thermally activated delayed fluorescence material containing dicarbonyl groups specifically includes the following steps: Under nitrogen protection, 7-bromoquinoline-2,3-difuranyl ketone / 7-bromoquinoline-2,3-dithienyl ketone / 7-bromoquinoline-2,3-diselenophenyl ketone (1 eq.), 9,9-dimethyl-10(9H)-acridine (1.2 eq.), tris(dibenzylideneacetone)dipalladium (0.06 eq.), tri-tert-butylphosphine tetrafluoroborate (0.2 eq.), sodium tert-butoxide (4 eq.), and anhydrous toluene were added to a pre-dried three-necked flask. The mixture was stirred at 110 °C for 12 hours. After the reaction was confirmed by TLC, the solvent was removed by vacuum distillation. The mixture was extracted with DCM-saturated brine and the organic phase dichloromethane was combined. The mixture after removing dichloromethane was purified by column chromatography to obtain the crude product, which was then recrystallized from dichloromethane / methanol to obtain products T1, T2, and T3.

[0009]

[0010] In this method for preparing thermally activated delayed fluorescence materials containing dicarbonyl groups, the preparation of B1-B3 includes the following steps:

[0011] Step 1: Synthesis of compound A1

[0012] 2-Nitro-4-bromobenzaldehyde and SnCl2 were added to a round-bottom flask equipped with a stir bar and dissolved in a mixture of ethyl acetate and methanol. After the reaction was complete, the mixture was quenched with NaHCO3, extracted with DCM, and the extract was concentrated under vacuum. The product was purified by column chromatography to obtain compound A1.

[0013] The equivalent ratio of 2-nitro-4-bromo-benzaldehyde and SnCl2 is 1:3. Step 2: Synthesis of compounds A2-A4

[0014] A mixture of CuBr2 and EA was heated to reflux, and then a CHCl3 solution containing an ethyl ketone derivative was added. The reaction mixture was stirred under reflux for 12 hours, cooled to room temperature, and filtered through a diatomaceous earth mat to remove the white CuBr precipitate. The precipitate was washed with CHCl3, and the filtrate was transferred to a separatory funnel, washed with 5% NaHCO3, and dried over anhydrous Na2SO4. The combined organic phases were concentrated under reduced pressure to obtain the crude product, which was purified by column chromatography to give compound A2-4.

[0015] The equivalent ratio of CuBr2 to acetophenone is 2:1. Step 3: Synthesis of ammonium salts A5-A7

[0016] Compounds A2-A4 were added to a round-bottom flask equipped with a stir bar and dissolved in THF. A trimethylamine solution was then added to the system, and the mixture was stirred at room temperature for 12 hours. The mixture was filtered, and products A5-A7 were obtained as white powders by washing twice with ethyl acetate.

[0017] The equivalent ratio of compound A2-A4 to trimethylamine is 1:1.

[0018] Step 4: Synthesis of intermediates B1-B3

[0019] Compound A1, ammonium salt A5-7, CuCl2, Cs2CO3, and KI were placed in a round-bottom flask equipped with a stir bar, and anhydrous dichloromethane (DCM) was added. The mixture was stirred at 80 °C for 12 hours under an oxygen atmosphere. Afterward, the mixture was cooled to room temperature and concentrated under vacuum. The crude product was purified by column chromatography to finally obtain compound B1-3, which was a yellow oil.

[0020] The equivalent ratio of compound A1, ammonium salts A5-A7, CuCl, Cs2CO3 and KI is 2:2.4:0.2:5:5.

[0021] This invention provides an organic compound containing a dicarbonyl group, which can be used as a thermally activated delayed fluorescence material in organic electroluminescent devices.

[0022] The beneficial effects of this invention are as follows: This invention provides a class of thermally activated delayed fluorescence materials containing dicarbonyl groups. The core feature of this class of materials is that they follow an equilibrium Δ E ST , k r and k RISCThe molecular design principles successfully achieved a balance between high performance and high stability. Specifically, by introducing O, S, and Se atoms at the meta positions of dicarbonylquinoline groups, which possess both intramolecular hydrogen bonding and twisted spatial configuration characteristics, the electronic structure and excited-state properties of the molecule were precisely controlled through heteroatom and heavy atom effects. This increased the spin-orbit coupling (SOC) strength of the molecule, maintaining a small energy level difference while increasing the anti-system crossing rate, thus promoting a balance between the anti-system crossing rate and the radiative transition rate. Furthermore, the combination of intramolecular hydrogen bonding and twisted configuration increased the rigidity of the molecule, effectively suppressing concentration quenching caused by π-π stacking and non-radiative energy loss caused by molecular vibrational relaxation, thereby contributing to improved photoluminescence quantum yield and material stability. Finally, a class of OLED devices with both high efficiency and low roll-off was fabricated. The successful implementation of this project provides an ideal solution for the design of TADF materials. Attached Figure Description

[0023] Figure 1 This is the HOMO and LUMO orbital distribution diagram of compound T1 calculated using Gaussian 09.

[0024] Figure 2 This is the HOMO and LUMO orbital distribution diagram of compound T2 calculated using Gaussian 09.

[0025] Figure 3 This is the HOMO and LUMO orbital distribution diagram of compound T3 calculated using Gaussian 09.

[0026] Figure 4 These are the UV-Vis absorption and fluorescence emission spectra of compounds T1 and T3 in toluene solution.

[0027] Figure 5 These are the fluorescence and phosphorescence spectra of compounds T1 and T3 at 77 K.

[0028] Figure 6 These are the transient fluorescence spectra of compounds T1 and T3.

[0029] Figure 7 These are the cyclic voltammetry diagrams for compounds T1 and T3.

[0030] Figure 8 These are the current density-voltage-brightness curves for sky-blue light devices T1 and T3.

[0031] Figure 9 These are the external quantum efficiency-brightness curves for sky-blue light devices T1 and T3.

[0032] Figure 10 These are the electroluminescence spectra of sky-blue light devices T1 and T3.

[0033] Figure 11 These are the chemical structural formulas of compounds T1, T2, and T3. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Compounds T1, T2, and T3 are synthesized according to the following preparation route:

[0035] The synthetic methods for compounds T1, T2, and T3 include the following steps: Example 1: Synthesis of compound A1:

[0036] 2-Nitro-4-bromobenzaldehyde (3.45 g, 15 mmol) was added to a round-bottom flask (250 mL) equipped with a magnetic inlet and dissolved in a mixture of ethyl acetate (30 mL) and methanol (30 mL). SnCl2 (8.6 g, 45 mmol) was then added. The mixture was stirred at room temperature in air for 24 h until complete. After the reaction was complete, it was quenched with NaHCO3 and extracted with DCM. The crude product was purified by silica gel column chromatography (200-300 mesh) using petroleum ether:EA = 10:1 (v:v) as the mobile phase to obtain Al, a yellow oily substance (2.22 g, 75% yield). TOF-EI-MS: 196.9475 [M]. + ].

[0037] Example 2 Synthesis of compounds A2-A4:

[0038] A mixture of CuBr2 (8.93 g, 40 mmol) and EA (20 mL) was heated to reflux, and then a solution of CHCl3 (15 mL) containing 2-acetylfuran (2.2 g, 20 mmol) was added. The reaction mixture was stirred at reflux at 65 °C for 12 hours, cooled to room temperature, and filtered on a diatomaceous earth mat to remove the white CuBr precipitate. The precipitate was washed with CHCl3, and the filtrate was transferred to a separatory funnel, washed with 5% NaHCO3, dried over anhydrous Na2SO4, and the combined organic phases were concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography (200-300 mesh) using petroleum ether:EA = 30:1 (v:v) as the mobile phase to give compound A1 (2.4 g, 64% yield). TOF-EI-MS: 184.9472 [M] + ].

[0039] Compound A2 (2.4 g, 60% yield) was prepared using a similar method to that used for compound A1, except that the substrate 2-acetylfuran was replaced with 2-acetylthiophene (2.5 g, 20 mmol). TOF-EI-MS: 203.9240 [M] + ].

[0040] Using a method similar to that used to prepare compound A1, except that the substrate 2-acetylfuran was replaced with 2-acetylselenophene (3.5 g, 20 mmol), all other steps were identical, yielding compound A3 (2.5 g, 50% yield). TOF-EI-MS: 251.8687 [M + ].

[0041] Example 3 Synthesis of ammonium salts A5-A7:

[0042] Compound A2 (1.9 g, 10 mmol) was added to a round-bottom flask equipped with a stir bar and dissolved in 40 mL of THF. A trimethylamine solution (2 g, 10 mmol) was added to the system, and the mixture was stirred at room temperature for 12 hours. The mixture was filtered and washed twice with ethyl acetate to give product A5 as a white powder (1.3 g, 74% yield).

[0043] Using a method similar to that used to prepare compound A5, except that substrate compound A2 was replaced with compound A3, and all other steps were exactly the same, product A6 (1.4 g, yield 74%) was obtained.

[0044] Using a method similar to that used to prepare compound A5, except that substrate compound A2 was replaced with compound A4, and all other steps were exactly the same, product A7 (1.84 g, 80% yield) was obtained.

[0045] Example 4 Synthesis of compounds B1-B3:

[0046] In a 500 mL round-bottom flask equipped with a stirrer, a mixture of A1 (1.1 g, 5.56 mmol), A5 (1.1 g, 6.65 mmol), CuCl2 (0.055 g, 0.56 mmol), Cs2CO3 (4.53 g, 13.8 mmol), and KI (2.31 g, 13.8 mmol) was added. Then, 50 mL of dry dichloromethane was added, and the mixture was placed in a preheated oil bath and stirred at 80 °C for 12 h under an oxygen atmosphere. Subsequently, the mixture was cooled to room temperature and concentrated under vacuum. The resulting mixture was purified by silica gel column chromatography using petroleum ether:EA:CH2Cl2 = 50:1:1 (v:v:v) as the mobile phase, yielding a yellow oily product B1 (0.9 g, yield 41%). TOF-EI-MS: 394.9790 [M] + ].

[0047] Using a similar method to that used to prepare compound B1, except that substrate A5 was replaced with A6 (1.2 g, 6.65 mmol), all other steps were the same, yielding product B2 (1.1 g, 45% yield). TOF-EI-MS: 426.9334 [M] + ].

[0048] Using a similar method to that used to prepare compound B1, except that substrate A5 was replaced with A7 (2.1 g, 6.65 mmol), all other steps were the same, yielding product B3 (1.0 g, 35% yield). TOF-EI-MS: 522.8226 [M] + ].

[0049] Example 5 Synthesis of compounds T1, T2 and T3:

[0050] Under nitrogen protection, B1-3 (47 mg / 51 mg / 63 mg, 0.12 mmol), 9,9-dimethyl-10(9H)-acridine (30 mg, 0.144 mmol), tris(dibenzylacetone)dipalladium (6.6 mg, 0.0060 mmol), tri-tert-butylphosphine tetrafluoroborate (7 mg, 0.024 mmol), sodium tert-butoxide (46.0 mg, 0.48 mmol), and 20 ml of anhydrous toluene were added to a pre-dried three-necked flask and heated to 110 °C. The mixture was stirred at ℃ for 12 h. After the reaction was confirmed by TLC, the solvent was removed by vacuum distillation. The mixture was extracted with DCM-saturated brine and the organic phase dichloromethane was combined. The mixture after removing dichloromethane was purified by silica gel column chromatography with petroleum ether:EA:CH2Cl2 = 50:1:1 (v:v:v) as the mobile phase to obtain the crude product. The crude product was then recrystallized from dichloromethane / methanol to obtain products T1, T2 and T3 (37 mg / 31 mg / 32 mg, yield 60% / 55% / 40%). TOF-EI-MS: 524.1735 [M + ] / 556.1280[M + ] / 652.0618[M + ].

[0051] Using a method similar to that used to prepare compound T1, except that substrate B1 was replaced with B2 (51 mg, 0.12 mmol), and all other steps were the same, product T2 (31 mg, 55% yield) was obtained. TOF-EI-MS: 556.1280 [M] + ].

[0052] Using a method similar to that used to prepare compound T1, except that substrate B1 was replaced with B3 (63 mg, 0.12 mmol), all other steps were the same, yielding product T3 (32 mg, 40% yield). TOF-EI-MS: 652.0618 [M] + ].

[0053] Example 6: DFT Theoretical Calculation Study Density functional theory simulations of the molecular structure were performed using the Gaussian09 program. The HOMO and LUMO distributions of the molecule are as follows: Figure 1 , Figure 2 and Figure 3 As shown, the HOMO electron cloud of the molecule is mainly distributed on the acridine donor group, while the LUMO electron cloud is mainly distributed on the dicarbonylquinoline group and the electron-withdrawing heteroatom group, with a small overlap. This theoretically proves that the molecule has the ability to transport holes and electrons. Compared with similar molecules, the dihedral angle between the donor and acceptor is larger, which promotes greater separation of the HOMO and LUMO of the molecule, resulting in a smaller Δ...E ST Furthermore, the frontier molecular orbitals are distributed on O, S, and Se atoms, demonstrating that heteroatoms or heavy atoms influence the electronic structure and excited-state properties of the molecule, thereby enhancing the spin-orbit coupling effect. Therefore, combining these two points, all molecules maintain a small energy level difference and increased spin-orbit coupling strength, enabling the molecules to maintain a high antisystem crossing rate and a high fluorescence quantum yield.

[0054] Example 7: Study of photophysical properties: At room temperature, using dry toluene as a solvent, the solution concentration is 1 × 10⁻⁶. -5 mol / L, the UV-Vis absorption and fluorescence spectra at room temperature T1 and T2 were measured, such as Figure 4 As shown. The strong absorption band around 290-320 nm can be attributed to the dimethylacridine group center. and Electron transition absorption, while the absorption band at long wavelengths of 350-450 nm can be attributed to the dimethylacridine to dicarbonyl group. Absorption due to charge transfer state transitions. The fluorescence spectra of T1 and T3 in toluene both showed characteristics of lacking fine vibrational structure, confirming the CT luminescence characteristics.

[0055] To further estimate the excited-state energy levels of this series of molecules, their LT-FL and LT-PH spectra were measured. The low-temperature spectra of all molecules in this series did not reveal fine vibrational structures, indicating that their S1 and T1 states originate from charge states and exhibit relatively small energy differences. Figure 5 As shown. Based on the initial peaks of their respective spectra, the energy levels T1 and T3 are calculated.

[0056] Table 1. Physical property data of compounds T1 and T3

[0057] The transient spectra of this series of molecularly doped films were tested. Figure 6 As shown, at room temperature, the transient spectra of all molecules exhibit a double exponential decay characteristic of the transient and delayed components, proving the existence of TADF properties. The lifetimes of T1 and T3 are 10.2 µs and 8.2 µs, respectively.

[0058] Example 8: Electrochemical Properties Study A blank scan was performed at a scan rate of 100 mV / s, followed by the addition of T1 and T3, respectively, with dry dichloromethane and N , NUsing dimethylformamide as the solvent and tetrabutylammonium hexafluorophosphate (Bu4NPF6) as the electrolyte, after nitrogen bubbling for 10 min to remove oxygen, the positive and negative cyclic voltammetry curves for T1 and T3 were measured on a CHI610E electrochemical analyzer. Figure 7 Based on the initial oxidation and reduction peak potentials, and the formulas, the HOMO and LUMO energy levels of T1 and T3 were calculated to be 5.30 / 2.80 eV and 5.45 / 2.90 eV, respectively.

[0059] Example 9: Study on electroluminescence properties: Electroluminescent devices were prepared using the dicarbonyl-containing thermally activated delayed fluorescence materials T1 and T3 prepared in Example 5 as guest materials for the emitting layer. These devices were designated as sky-blue devices T1 and T3, respectively, and the devices were characterized and tested. The specific structure of the electroluminescent device is as follows: ITO / PEDOT:PSS (40 nm) / TAPC (10 nm) / mCP (5 nm) / T1 or T3:DPEPO (7 wt%, 20 nm) / TmPyPb (40 nm) / LiF (1 nm) / Al (200 nm), (dopants: T1, T2, and T3). In these devices, PEDOT:PSS and LiF serve as the hole and electron injection layers, respectively; TAPC and TmPyPB serve as the hole and electron transport layers, respectively. Furthermore, DPEPO is chosen as the host material because its triplet energy level is higher than that of the luminescent material, ensuring energy transfer from the host to the object and effectively preventing energy transfer from the luminescent material back to the host. Figure 8 The current density-voltage-luminance curves of sky-blue light-emitting devices fabricated using T1 and T3 as guest materials are shown in the figure. From this figure, it can be seen that the turn-on voltages of the devices are 3.2 V and 3.0 V, respectively, and the maximum luminance is 13000 cd / m². 2 and 34000 cd / m 2 The efficiency curves and electroluminescence spectra of the sky-blue light devices T1 and T3 are as follows: Figure 9 and Figure 10 As shown, the maximum external quantum efficiencies of sky-blue light-emitting devices T1 and T3 are 26.0% and 30.2%, respectively. CIE (0.18, 0.33) and CIE (0.16, 0.23) values ​​are also shown. From the electroluminescence spectra of the devices, it can be seen that the emission peaks of sky-blue light-emitting devices T1 and T3 only contain emission peaks from the guest materials T1 and T3, respectively, without emission peaks from the host material or other materials. It is worth noting that sky-blue light-emitting device T3 achieves a brightness of 100 cd / m². -2 and at 1000 cd m -2The out-of-time quantum efficiencies were 22.5% and 12.2%, respectively. Compared with similar devices reported previously, the doped device fabricated using the small molecule T3 as the luminescent material exhibited an excellent efficiency roll-off. Therefore, combining theoretical calculations and photophysical testing results, it can be inferred that T1 and T3 possess both high efficiency and low roll-off characteristics.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A class of thermally activated delayed fluorescence materials containing dicarbonyl groups, characterized in that, The general structural formula of the fluorescent material is: ； Where R is O, S, or Se.

2. A method for preparing a thermally activated delayed fluorescence material containing a dicarbonyl group as described in claim 1, characterized in that: ； S1. Under nitrogen protection, compound B, compound C, tris(dibenzylacetone)dipalladium, tri-tert-butylphosphine tetrafluoroborate, sodium tert-butoxide and anhydrous toluene were added to a dry three-necked flask. The molar ratio of compound B, compound C, tris(dibenzylacetone)dipalladium, tri-tert-butylphosphine tetrafluoroborate, and sodium tert-butoxide is 1:1.2:(0.05-0.08):(0.2-0.4):4; S2. Stir at 100-120℃ for 10-14 hours. After the reaction is complete, remove the solvent by vacuum distillation, extract, purify by column chromatography, and recrystallize to obtain the target product.

3. The method for preparing a thermally activated delayed fluorescence material containing a dicarbonyl group according to claim 2, characterized in that: Compound B is 7-bromoquinoline-2,3-difuranyl ketone, 7-bromoquinoline-2,3-dithienyl ketone, or 7-bromoquinoline-2,3-diselenophenyl ketone.

4. The application of the type of thermally activated delayed fluorescence material containing dicarbonyl groups as described in claim 1, characterized in that, The fluorescent material is used to prepare electroluminescent devices.

5. An organic electroluminescent device, characterized in that: The electroluminescent device includes the thermally activated delayed fluorescence material containing dicarbonyl groups as described in claim 1.

6. The electroluminescent device according to claim 5, characterized in that, The electroluminescent device includes a light-emitting layer containing the fluorescent material.

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