Six-membered heterocyclic diboron polycyclic compound for organic electroluminescent device

Abstract

The invention belongs to the technical field of organic light-emitting materials, and relates to a six-membered heterocyclic diboron polycyclic compound for an organic light-emitting device. Two B atoms are introduced to the two sides of a six-membered heterocyclic structure respectively, and covalent bonds are formed by the two B atoms and hetero atoms such as N, O and S respectively, so that the polycyclic compound with a specific structure is constructed. According to the structural design, the compound has enough high singlet state and triplet state energy while keeping a relatively large molecular distortion degree, and the energy difference between the singlet state and the triplet state is relatively small. The compound with the multi-resonance thermal activity delayed fluorescence effect can be applied to organic light-emitting diodes as a light-emitting material, and key properties such as light-emitting efficiency and color purity of organic electroluminescent devices are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of organic luminescent materials and relates to a six-membered heterocyclic diboron polycyclic compound for organic electroluminescent devices. Background Art

[0002] In recent years, thermally activated delayed fluorescence (TADF) materials have become a research hotspot in the field of organic optoelectronics due to their advantages of low cost and high efficiency. The excellent photophysical properties of TADF materials are related to their electroluminescence mechanism. Under the conditions of electrical excitation, the ratio of singlet S excitons to triplet T excitons is 1:3, and the high-energy exciton S n and T n The TADF material can transform into low-energy excitons S1 and T1 through vibrational relaxation and internal conversion. ST ) is small (generally less than 0.3eV). The continuously accumulated triplet exciton T1 can form a singlet exciton S1 through antisystem crossing under the action of thermal activation. The singlet exciton S1 undergoes radiative transition and produces delayed fluorescence. The theoretical maximum IQE is 100% (25% fluorescence + 75% delayed fluorescence). From the TADF electroluminescence mechanism, it can be seen that the antisystem crossing process (T1→S1) and the radiative transition process (S1→S0) are extremely important for the realization of the TADF mechanism. Both processes are related to ∆E ST There is an important relationship between ∆E and ST The smaller the ∆E is, the higher the intersystem crossing rate is and the lower the radiative transition rate is. Therefore, the appropriate ∆E ST Achieving the optimal match between the intersystem crossing rate and the radiative transition rate is a prerequisite for achieving efficient TADF. Summary of the Invention

[0003] To address these issues and deficiencies, the present invention provides a six-membered heterocyclic biboron polycyclic compound for use in organic electroluminescent devices. This polycyclic compound is constructed by introducing two boron atoms on either side of the six-membered heterocyclic ring, with the boron atoms forming covalent bonds with nitrogen, oxygen, and sulfur, respectively. The compound can be used as a blue or green light-emitting material in organic electroluminescent devices.

[0004] In a first aspect, the present invention provides a compound having a structure as shown in Formula I or Formula II, ; Wherein, X in Formula I or Formula II is selected from any one of CR5R6, NR7, O, and S; R5 and R6 in the CR5R6 are methyl or phenyl; R7 in the NR7 is a substituted or unsubstituted phenyl group, and the substituent is deuterium, a C6-C30 aryl or heteroaryl group, a C1-C5 alkyl group, a cyano group, or a trifluoromethyl group; Y in Formula I or Formula II is selected from any one of N, O, and S; X1 and X2 in Formula I or Formula II are selected from any one of NR8, O, S, and Se; R8 in the NR8 is a substituted or unsubstituted phenyl group, and the substituent is deuterium, a C6-C30 aryl or heteroaryl group, a C1-C5 alkyl group, a cyano group, or a trifluoromethyl group; Y1 and Y2 in Formula I or Formula II are selected from any one of NR9, O, and S; R9 in the NR9 is a substituted or unsubstituted phenyl group, or is bonded to an adjacent phenyl ring in the form of a single bond, and the substituent is deuterium, a C6-C30 aryl or heteroaryl group, a C1-C5 alkyl group, a cyano group, or a trifluoromethyl group; R1, R2, R3, and R4 in Formula I or Formula II are selected from any one of methyl, ethyl, isopropyl, tert-butyl, amino, C6-C30 aryl, or heteroaryl; In Formula I or Formula II, L1 is an aryl group or a heteroaryl group, and m is an integer from 0 to 5; In the formula I or formula II, Ar1 is an aryl group or a heteroaryl group, and n is an integer of 0 to 5; In the formula I or formula II, when Y is O or S, m and n are 0.

[0005] Furthermore, in the compounds provided by the present invention, any hydrogen atom in the compounds is deuterated or not.

[0006] Furthermore, in the compounds provided by the present invention, when Y is N, the structure of Formula I is as shown in Formulas A1 to A4, .

[0007] Furthermore, in the compounds provided by the present invention, when Y is N, the structures of Formula II are as shown in Formulas B1 to B4, .

[0008] Furthermore, in the compounds provided by the present invention, when Y is O, the structures of Formula I and Formula II are as shown in Formulas A5 to A8 and B5 to B8, .

[0009] Furthermore, in the compounds provided by the present invention, when Y is S, the structures of Formula I and Formula II are as shown in Formulas A9 to A12 and B9 to B12, .

[0010] Furthermore, in the compound provided by the present invention, the structure of the compound is as follows:

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[0058] In a second aspect, the present invention provides use of the above compound in an organic electroluminescent device.

[0059] In a third aspect, the present invention provides use of the above compound in an organic electroluminescent device.

[0060] In a fourth aspect, the present invention provides an organic electroluminescent device comprising an anode layer, a cathode layer, and an organic thin film layer located between the anode layer and the cathode layer, wherein the organic thin film layer comprises a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer, and the light-emitting layer contains the above-mentioned compound.

[0061] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: The present invention introduces two boron atoms on either side of a six-membered heterocyclic ring, with the B atoms forming covalent bonds with nitrogen, oxygen, and sulfur, respectively, to construct a polycyclic compound. This ensures that the compound maintains significant distortion while possessing sufficiently high singlet and triplet energies, suitable HOMO and LUMO energy levels, and a small energy difference between the singlet and triplet states. The six-membered heterocyclic central molecule participates in conjugation and charge transfer, and the change in heteroatoms improves the charge distribution within the molecule, resulting in a strong multiple resonance thermally activated delayed fluorescence (MR-TADF) effect. Application as a luminescent material in organic light-emitting diodes (OLEDs) narrows the emission spectrum, broadens the emission spectrum, and achieves emission from blue to green, improving the efficiency, color purity, and other properties of organic electroluminescent devices. The compound is widely applicable to OLED light-emitting devices and displays. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0063] Figure 1 Schematic diagram of the structure of an organic electroluminescent element. 1 is the substrate, 2 is the anode layer, 3 is the hole injection layer, 4 is the hole transport layer, 5 is the electron blocking layer, 6 is the light-emitting layer, 7 is the hole blocking layer, 8 is the electron transport layer, 9 is the electron injection layer, and 10 is the cathode layer. DETAILED DESCRIPTION

[0064] The technical solutions of the present invention are described below with reference to the following examples. However, the present invention is not limited to the following examples. The experimental methods and detection methods described in each example are conventional methods unless otherwise specified. The reagents and materials described are commercially available unless otherwise specified. The percentages in the following examples are percentages by mass unless otherwise specified.

[0065] Preparation Example This preparation example provides the synthesis methods of some compounds (Compound 8, Compound 26, Compound 28, Compound 55, Compound 136, Compound 141, Compound 144, Compound 150, Compound 241, Compound 243, Compound 251 and Compound 256). The synthesis methods of the remaining intermediates and compounds are similar and can be easily synthesized. The specific synthesis routes are shown below.

[0066] Synthesis of intermediate 8:

[0067] Synthesis of Intermediate 8-1: Under nitrogen, a reaction flask was charged with starting material 1 (50.00 g, 129.0 mmol), starting material 2 (24.46 g, 58.6 mmol), sodium tert-butoxide (16.90 g, 175.8 mmol), and toluene (1000 mL). Pd2(dba)3 (0.54 g, 0.58 mmol) and X-Phos (0.56 g, 1.17 mmol) were then added and heated to 108°C for 4 h. After the reaction, the mixture was cooled to room temperature and poured into water to produce a white precipitate, which was filtered. The precipitate was washed sequentially with water and ethanol. Finally, the mixture was passed through a silica gel column and recrystallized to obtain Intermediate 8-1 (48.30 g, 80% yield).

[0068] Synthesis of Intermediate 8-2: Under nitrogen, to a three-necked flask equipped with a condenser, add Intermediate 8-1 (45.30 g, 44.0 mmol) and dichloroethane (500 mL). The temperature was cooled to 0°C–5°C, and then boron tribromide (10.99 g, 44.0 mmol) was slowly added dropwise. After the reaction, the mixture was poured into a large amount of ice water and filtered. The filter cake was washed sequentially with water and ethanol, and finally filtered through a silica gel column and recrystallized to obtain Intermediate 8-2 (39.66 g, 90% yield).

[0069] Synthesis of Compound 8: Under nitrogen, intermediate 8-2 (35.60 g, 35.5 mmol) and o-dichlorobenzene (350 mL) were added sequentially to a three-necked flask equipped with a condenser. Boron tribromide (88.82 g, 355.3 mmol) was then slowly added dropwise. The mixture was heated to 150–160°C for 8 h. After completion of the reaction, the system was cooled to room temperature. A large amount of water was added to form a white precipitate, which was filtered. The filter cake was washed with water and then ethanol, and finally filtered through a silica gel column and recrystallized to afford Compound 8 (21.70 g, 60% yield).

[0070] The characterization results of the obtained compound 8 are as follows: HRMS: measured value: 1018.5280 [M+H] + ; Exact mass: 1018.5285. C 70 H 65 Calculated values for O3B2N3 (%): C, 82.60%; H, 6.44%; N, 4.13; Found: C, 82.54%; H, 6.36%; N, 4.06%.

[0071] Synthesis of compound 26:

[0072] The synthesis of intermediate 26-1 refers to the synthesis of intermediate 8-1, except that raw materials 1 and 2 are replaced by raw materials 3 and 4; The synthesis of intermediate 26-2 refers to the synthesis of intermediate 8-2, except that intermediate 8-1 is replaced by intermediate 26-1; The synthesis of compound 26 was based on the synthesis of compound 8, except that intermediate 8-2 was replaced by intermediate 26-2.

[0073] The characterization results of the obtained compound 26 are as follows: HRMS: measured value: 894.4852 [M+H] + ; Exact mass: 894.4859. C 61 H 61 Calculated values for O4B2N (%): C, 81.97%; H, 6.88%; N, 1.57%; Found: C, 81.90%; H, 6.79%; N, 1.50%.

[0074] Synthesis of compound 28:

[0075] The synthesis of intermediate 28-1 refers to the synthesis of intermediate 8-1, except that raw material 1 is replaced by raw material 3; The synthesis of intermediate 28-2 refers to the synthesis of intermediate 8-2, replacing intermediate 8-1 with intermediate 28-1; The synthesis of compound 28 was carried out by referring to the synthesis of compound 8, except that intermediate 8-2 was replaced by intermediate 28-2.

[0076] The characterization results of the obtained compound 28 are as follows: HRMS: measured value: 868.4330 [M+H]+; accurate mass: 868.4339. 58 H 55 Calculated values for O5B2N (%): C, 80.29%; H, 6.39%; N, 1.61%; Found: C, 80.20%; H, 6.31%; N, 1.55%.

[0077] Synthesis of compound 55:

[0078] The synthesis of intermediate 55-1 refers to the synthesis of intermediate 8-1, except that raw material 1 is replaced by raw material 5; Synthesis of Intermediate 55-2: Under nitrogen, a reaction flask was charged with Intermediate 55-1 (30.00 g, 30.3 mmol), aniline (8.46 g, 90.9 mmol), sodium tert-butoxide (8.73 g, 90.9 mmol), and toluene (300 mL). Pd2(dba)3 (0.17 g, 0.18 mmol) and X-Phos (0.18 g, 0.36 mmol) were then added and heated to 108°C for 4 h. After the reaction, the mixture was cooled to room temperature and poured into water to produce a white precipitate, which was filtered. The precipitate was washed sequentially with water and ethanol. Finally, the mixture was filtered through a silica gel column and recrystallized to obtain Intermediate 55-2 (23.40 g, 70% yield).

[0079] The synthesis of compound 55 was based on the synthesis of compound 8, except that intermediate 8-2 was replaced by intermediate 55-2.

[0080] The characterization results of the obtained compound 55 are as follows: HRMS: measured value: 1119.6270 [M+H] + ; Exact mass: 1119.6278. C 79 H 76 Calculated values for OB2N4 (%): C, 84.79%; H, 6.85%; N, 5.01%; found values: C, 84.70%; H, 6.78%; N, 4.96%.

[0081] Synthesis of compound 136:

[0082] The synthesis of intermediate 136-1 refers to the synthesis of intermediate 55-1, except that raw materials 5 and 6 are replaced by raw materials 7 and 8; The synthesis of intermediate 136-2 refers to the synthesis of intermediate 55-2, except that intermediate 55-1 is replaced by intermediate 136-1; The synthesis of compound 136 was based on the synthesis of compound 55, except that intermediate 55-2 was replaced by intermediate 136-2.

[0083] The characterization results of the obtained compound 136 are as follows: HRMS: measured value: 969.5328 [M+H] + ; Exact mass: 969.5332. C 67 H 66 Calculated values for O3B2N2 (%): C, 83.06%; H, 6.87%; N, 2.89%; Found: C, 83.01%; H, 6.82%; N, 2.80%.

[0084] Synthesis of compound 141:

[0085] The synthesis of intermediate 141-1 refers to the synthesis of intermediate 55-1, except that raw material 6 is replaced by raw material 8; The synthesis of intermediate 141-2 refers to the synthesis of intermediate 55-2, except that intermediate 55-1 is replaced by intermediate 141-1; The synthesis of compound 141 was based on the synthesis of compound 55, except that intermediate 55-2 was replaced by intermediate 141-2.

[0086] The characterization results of the obtained compound 141 are as follows: HRMS: measured value: 1119.6270 [M+H] + ; Exact mass: 1119.6278. C 79 H 76 Calculated values for OB2N4 (%): C, 84.79%; H, 6.85%; N, 5.01%; found values: C, 84.72%; H, 6.782%; N, 4.940%.

[0087] Synthesis of compound 144:

[0088] The synthesis of intermediate 144-1 refers to the synthesis of intermediate 55-1, except that raw material 6 is replaced by raw material 9; The synthesis of intermediate 144-2 refers to the synthesis of intermediate 55-2, except that intermediate 55-1 is replaced by intermediate 144-1; The synthesis of compound 144 was based on the synthesis of compound 55, except that intermediate 55-2 was replaced by intermediate 144-2.

[0089] The characterization results of the obtained compound 144 are as follows: HRMS: measured value: 805.4802 [M+H] + ; Exact mass: 805.4809. C 76 H 70 Calculated values for OB2N4S (%): C, 82.30%; H, 6.36%; N, 5.05%; found: C, 82.23%; H, 6.29%; N, 5.00%.

[0090] Synthesis of compound 150:

[0091] The synthesis of intermediate 150-1 refers to the synthesis of intermediate 8-1, except that raw material 1 is replaced by raw material 10; The synthesis of intermediate 150-2 refers to the synthesis of intermediate 8-2, except that intermediate 8-1 is replaced by intermediate 150-1; The synthesis of compound 150 was based on the synthesis of compound 8, except that intermediate 8-2 was replaced by intermediate 150-2.

[0092] The characterization results of the obtained compound 150 are as follows: HRMS: measured value: 806.4806 [M+H] + ; Exact mass: 806.4811. C 57 H 57 Calculated values for B2N3 (%): C, 84.97%; H, 7.13%; N, 5.22%; Found values: C, 84.90%; H, 7.05%; N, 5.18%.

[0093] Synthesis of compound 241:

[0094] The synthesis of intermediate 241 refers to the synthesis of intermediate 26-1, except that raw material 3 is replaced by raw material 11; The synthesis of compound 241 was carried out by referring to the synthesis of compound 26, except that intermediate 26-1 was replaced by intermediate 241.

[0095] The characterization results of the obtained compound 241 are as follows: HRMS: measured value: 1302.7682 [M+H] + ; Exact mass: 1302.7690. C 93 H 93 B2N5 (%) calculated values: C, 85.77%; H, 7.20%; N, 5.38%; found values: C, 85.70%; H, 7.04%; N, 5.31%.

[0096] Synthesis of compound 243:

[0097] The synthesis of intermediate 243 refers to the synthesis of intermediate 8-1, except that raw material 1 is replaced by raw material 11; The synthesis of compound 243 referred to the synthesis of compound 8, except that intermediate 8-1 was replaced by intermediate 243.

[0098] The characterization results of the obtained compound 243 are as follows: HRMS: measured value: 1292.7476 [M+H] + ; Exact mass: 1292.7482. C 91 H 91 Calculated values for OB2N5 (%): C, 84.57%; H, 7.10%; N, 5.42%; found values: C, 84.49%; H, 7.02%; N, 5.36%.

[0099] Synthesis of compound 251:

[0100] The synthesis of intermediate 251 refers to the synthesis of intermediate 55, except that raw material 5 is replaced by raw material 12; The synthesis of compound 251 was carried out by referring to the synthesis of compound 55, except that intermediate 55-1 was replaced by intermediate 251.

[0101] The characterization results of the obtained compound 251 are as follows: HRMS: measured value: 1077.6266 [M+H] + ; Exact mass: 1077.6271. C 75 H 78 Calculated values for O3B2N2 (%): C, 83.64%; H, 7.30%; N, 2.60%; Found: C, 83.60%; H, 7.22%; N, 2.54%.

[0102] Synthesis of compound 256:

[0103] The synthesis of intermediate 256 refers to the synthesis of intermediate 55, except that starting material 5 is replaced by starting material 11; The synthesis of compound 256 was carried out by referring to the synthesis of compound 55, except that intermediate 55-1 was replaced by intermediate 256.

[0104] The characterization results of the obtained compound 256 are as follows: HRMS: measured value: 1227.7212 [M+H] + ; Exact mass: 1227.7217. C 87 H 88Calculated values for OB2N4 (%): C, 85.14%; H, 7.23%; N, 4.57%; Found values: C, 85.08%; H, 7.17%; N, 4.50%.

[0105] With reference to the synthesis methods of the above compounds, all compounds in the present invention can be synthesized. The only difference is that different raw materials need to be used instead according to different products, and the mass amount of the raw materials is changed according to different molar amounts.

[0106] The performance parameters (including HOMO energy level, LUMO energy level, S1 and triplet energy T1) of some compounds synthesized in the present invention (Compound 5, Compound 7, Compound 8, Compound 26, Compound 27, Compound 28, Compound 33, Compound 46, Compound 55, Compound 60, Compound 77, Compound 81, Compound 85, Compound 97, Compound 101, Compound 110, Compound 125, Compound 136, Compound 144, Compound 150, Compound 170, Compound 181, Compound 205, Compound 224, Compound 241, Compound 243, Compound 251, Compound 256) and the existing OLED luminescent material BD01 were measured. The calculation method adopted the B3LYP hybrid functional and the basis set was 6-31g(d,p). The calculation results are shown in Table 1.

[0107] Table 1 Performance parameter measurement results of compounds and existing materials

[0108]

[0109] As shown in Table 1, the compounds of the present invention have a more suitable HOMO / LUMO and a smaller singlet-triplet energy difference (ΔEst), and are more likely to undergo intergap-crossing inversion from triplet to singlet.

[0110] Taking some compounds provided by the present invention as examples, the compounds are applied as luminescent host materials to organic electroluminescent devices to verify the excellent effects achieved.

[0111] The excellent effects of the OLED materials of the present invention when used in devices are specifically demonstrated through the device performance of Examples 1-28 and Comparative Examples. The structures and manufacturing processes of Examples 1-28 and Comparative Examples 1-2 are identical, and the same glass substrates, electrode materials, and film thicknesses are employed. The only difference is that the main material of the light-emitting layer has been adjusted, as detailed below.

[0112] Comparative Example 1 This comparative example provides an organic electroluminescent device, the structure of which is as follows: Figure 1As shown, it includes a substrate 1, an anode layer 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light-emitting layer 6, a hole blocking layer 7, an electron transport layer 8, an electron injection layer 9 and a cathode layer 10 stacked in sequence.

[0113] Among them, the substrate 1 is a glass substrate with a thickness of 0.7 mm, the material of the anode layer 2 is indium tin oxide (ITO) with a high work function, the material of the hole injection layer 3 is HT1 doped with HI-1, the mass ratio is 97:3, and the thickness is 10 nm; the material of the hole transport layer 4 is HT1, the thickness is 60 nm; the material of the electron blocking layer 5 is EB1, the thickness is 15 nm; the light-emitting layer 6 uses BH1 as the main material and BD01 as the light-emitting material, the doping mass percentage is 5%, and the light-emitting layer thickness is 30 nm; the material of the hole blocking layer 7 is HB, the thickness is 10 nm; the material of the electron transport layer 8 is ET-1 doped with Liq, the doping concentration is w50%, and the thickness is 30 nm; the material of the electron injection layer 9 is Liq, the thickness is 2 nm; the material of the cathode layer is Al, the thickness is 100 nm.

[0114] The basic material structures used in each functional layer of the organic electroluminescent device of Comparative Example 1 are as follows:

[0115]

[0116] The specific preparation steps of the organic electroluminescent device of Comparative Example 1 are as follows: (1) Clean the ITO anode on the transparent glass or plastic substrate by ultrasonic cleaning with deionized water, acetone, and ethanol for 20 minutes each, and then perform plasma treatment in an oxygen atmosphere for 5 minutes; (2) On the ITO anode layer, a hole injection layer material HT1:HI-1 was deposited by vacuum evaporation with a mass ratio of 97:3 and a thickness of 10 nm. This layer served as the hole injection layer. (3) Hole transport material HT1 was deposited on the hole injection layer by vacuum evaporation with a thickness of 60 nm. This layer served as the hole transport layer. (4) Vacuum evaporation of a second hole transport material BH1 with a thickness of 15 nm on the hole transport layer HT1, which serves as an electron blocking layer; (5) On the electron blocking layer, a light-emitting layer was co-deposited by vacuum evaporation, using BH1 as the host material and BD01 as the light-emitting material, with a doping mass ratio of 5% and a light-emitting layer thickness of 30 nm; (6) On top of the light-emitting layer, a hole blocking material HB is deposited by vacuum evaporation with a thickness of 10 nm. This layer serves as a hole blocking layer. (7) On the hole blocking layer, the electron transport material ET-1:Liq is evaporated by vacuum evaporation with a mass ratio of 1:1 and a thickness of 30 nm. This layer serves as the electron transport layer; (8) On the electron transport layer, the electron injection material Liq is evaporated by vacuum evaporation with a thickness of 2 nm. This layer serves as the electron injection layer; (9) On the electron injection layer, cathode Al is evaporated by vacuum evaporation with a thickness of 100 nm. This layer is used as a cathode conductive electrode and is the cathode layer.

[0117] The implementation process of Example 1 to Example 24 is the same as that of the comparative example, except that the luminescent material BD01 is replaced by Compound 5, Compound 8, Compound 26, Compound 28, Compound 33, Compound 46, Compound 55, Compound 60, Compound 77, Compound 81, Compound 85, Compound 97, Compound 101, Compound 110, Compound 125, Compound 136, Compound 144, Compound 150, Compound 170, Compound 181, Compound 205, Compound 224, Compound 251 and Compound 256 provided by the present invention.

[0118] The organic electroluminescent devices of Examples 1 to 24 and the comparative example were connected to the cathode and anode using a known driving circuit. The voltage-efficiency-current density relationship of the OLED devices was tested using a standard method using a Keithley 2400 power supply and a PR670 photometer. The light-emitting layer compositions and test results of Examples 1 to 24 are shown in Table 2, where the test data are relative values (%).

[0119] Table 2 Performance test results of organic electroluminescent devices in various examples

[0120] As shown in Table 2, the compounds provided by the present invention exhibit excellent performance when used as luminescent materials in OLED devices. Compared to the BD01 material described in Comparative Example 1, the compounds provided by the present invention exhibit significantly improved luminous efficiency, a narrower half-value width, and higher color purity. These compounds have significant application value in OLED devices and offer promising industrial prospects.

[0121] Examples 25-28 The implementation process of Examples 25 to 28 is the same as that of Comparative Example 1, except that the luminescent material of the luminescent layer is replaced by Compound 7, Compound 27, Compound 241 and Compound 243 instead of BD01.

[0122] Comparative Example 2 Comparative Example 2 is the same as Comparative Example 1, except that the luminescent material of the luminescent layer is replaced by GD01 instead of BD01.

[0123] Table 3 Performance test results of organic electroluminescent devices in various examples

[0124] As shown in Table 3, the six-membered heterocyclic diboron polycyclic compounds provided by the present invention exhibit high singlet and triplet energies, a small singlet-triplet energy gap, and suitable HOMO and LUMO energy levels. While maintaining strong rigidity, these diboron polycyclic compounds exhibit a strong multiple resonance thermally activated delayed fluorescence (MR-TADF) effect. Application as luminescent materials in organic light-emitting diodes (OLEDs) narrows the emission spectrum. By varying the heteroatom content and ring closure mechanism, the emission position is red-shifted from blue to green, improving the efficiency and color purity of organic electroluminescent devices. These compounds are widely applicable to OLED light-emitting devices and display devices.

[0125] As described above, the basic principles, main features and advantages of the present invention are well described. The above embodiments and descriptions are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the scope of protection determined by the present invention.

Claims

1. A compound, characterized in that The compound has a structure as shown in Formula I or Formula II, ； Wherein, X in Formula I or Formula II is selected from any one of CR5R6, NR7, O, and S; R5 and R6 in the CR5R6 are methyl or phenyl; R7 in the NR7 is a substituted or unsubstituted phenyl group, and the substituent is deuterium, a C6-C30 aryl or heteroaryl group, a C1-C5 alkyl group, a cyano group, or a trifluoromethyl group; Y in Formula I or Formula II is selected from any one of N, O, and S; X1 and X2 in Formula I or Formula II are selected from any one of NR8, O, S, and Se; R8 in the NR8 is a substituted or unsubstituted phenyl group, and the substituent is deuterium, a C6-C30 aryl or heteroaryl group, a C1-C5 alkyl group, a cyano group, or a trifluoromethyl group; Y1 and Y2 in Formula I or Formula II are selected from any one of NR9, O, and S; R9 in the NR9 is a substituted or unsubstituted phenyl group, or is bonded to an adjacent phenyl ring in the form of a single bond, and the substituent is deuterium, a C6-C30 aryl or heteroaryl group, a C1-C5 alkyl group, a cyano group, or a trifluoromethyl group; R1, R2, R3, and R4 in Formula I or Formula II are selected from any one of methyl, ethyl, isopropyl, tert-butyl, amino, C6-C30 aryl, or heteroaryl; In Formula I or Formula II, L1 is an aryl group or a heteroaryl group, and m is an integer from 0 to 5; In the formula I or formula II, Ar1 is an aryl group or a heteroaryl group, and n is an integer of 0 to 5; In the formula I or formula II, when Y is O or S, m and n are 0.

2. The compound according to claim 1, characterized in that Any hydrogen atom in the compound may be deuterated or not.

3. The compound according to claim 1, characterized in that When Y is N, the structure of Formula I is shown in Formulas A1 to A4, 。 4. The compound according to claim 1, characterized in that When Y is N, the structure of Formula II is as shown in Formulas B1 to B4; 。 5. The compound according to claim 1, characterized in that When Y is O, the structures of Formula I and Formula II are shown in Formulas A5 to A8 and B5 to B8. 。 6. The compound according to claim 1, characterized in that When Y is S, the structures of Formula I and Formula II are shown in Formulas A9 to A12 and B9 to B12. 。 7. The compound according to claim 1, characterized in that The structure of the compound is shown below, 。 8. Use of the compound according to any one of claims 1 to 7 in an organic electroluminescent device.

9. Use of the compound according to any one of claims 1 to 7 in an organic electroluminescent device.

10. An organic electroluminescent device comprising an anode layer, a cathode layer, and an organic thin film layer located between the anode layer and the cathode layer, wherein the organic thin film layer comprises a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer, characterized in that: The light-emitting layer contains the compound according to any one of claims 1 to 7.

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