A six-membered heterocyclic diboron polycyclic compound for an organic electroluminescent device

Abstract

The present application belongs to the technical field of organic light-emitting materials, and relates to a six-membered heterocyclic double-boron polycyclic compound for an organic electroluminescent device. The present application introduces two B atoms on both sides of a six-membered heterocyclic structure respectively, and makes the two B atoms form covalent bonds with N, O, S and other heteroatoms respectively, to construct a polycyclic compound with a specific structure. This structure design makes the compound have a large molecular twist degree, and also has a high singlet and triplet energy, and a small energy difference between the singlet and the triplet. The compound with the multiple resonance thermally activated delayed fluorescence effect can be applied to an organic light-emitting diode as a light-emitting material, to improve the key performances such as the light-emitting efficiency and color purity of the organic electroluminescent device.

Description

Technical Field

[0001] This invention belongs to the field of organic light-emitting materials technology, and relates to a six-membered heterocyclic diboron polycyclic compound for use in organic electroluminescent devices. Background Technology

[0002] In recent years, thermally active delayed fluorescence materials (TADFs) 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 electro-excitation conditions, the ratio of singlet S excitons to triplet T excitons formed is 1:3, and the high-energy S excitons... n and T n Through vibrational relaxation and internal conversion, they transform into low-energy excitons S1 and T1. Due to the lowest singlet excited state-triple excited state bandgap (∆E) of the TADF material, ST The ΔE is relatively small (generally less than 0.3 eV). The continuously accumulating triplet excitons T1 can undergo antisystem crossing under thermal activation to form singlet excitons S1. The singlet exciton S1 then undergoes radiative transition, producing 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 of these processes are related to ΔE. ST They are closely related. Generally, ∆E ST The smaller the value, the higher the inter-antisystem transition rate and the lower the radiative transition rate. Therefore, choosing an appropriate ∆E is crucial. ST Achieving the optimal match between antisystem crossover rates and radiative transition rates is a prerequisite for realizing efficient TADF. Summary of the Invention

[0003] To address the aforementioned problems and shortcomings, this invention provides a six-membered heterocyclic diboron polycyclic compound for use in organic electroluminescent devices. This invention constructs a polycyclic compound by introducing two boron atoms on both sides of a six-membered heterocycle, with the boron atoms forming covalent bonds with N, O, and S, respectively. This 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.

[0005] ;

[0006] Wherein, X in Formula I or Formula II is selected from any one of CR5R6, NR7, O, and S;

[0007] R5 and R6 in CR5R6 are methyl or phenyl;

[0008] R7 in NR7 is a substituted or unsubstituted phenyl group, and the substituent is deuterium, C6~C30 aryl or heteroaryl, C1~C5 alkyl, cyano, or trifluoromethyl.

[0009] In Formula I or Formula II, Y is selected from any one of N, O, and S;

[0010] X1 and X2 in Formula I or Formula II are selected from any one of NR8, O, S, and Se;

[0011] R8 in NR8 is a substituted or unsubstituted phenyl group, and the substituent is deuterium, C6~C30 aryl or heteroaryl, C1~C5 alkyl, cyano, or trifluoromethyl.

[0012] In Formula I or Formula II, Y1 and Y2 are selected from any one of NR9, O, and S;

[0013] R9 in NR9 is a substituted or unsubstituted phenyl group, or is bonded to an adjacent benzene ring by a single bond, and the substituent is deuterium, C6-C30 aryl or heteroaryl, C1-C5 alkyl, cyano, or trifluoromethyl.

[0014] 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.

[0015] In Formula I or Formula II, L1 is aryl or heteroaryl, and m is an integer from 0 to 5;

[0016] In Formula I or Formula II, Ar1 is aryl or heteroaryl, and n is an integer from 0 to 5;

[0017] In Equation I or Equation II, when Y is 0 or S, m and n are 0.

[0018] Furthermore, in the compounds provided by the present invention, any hydrogen atom in the compound is either deuterated or undeuterated.

[0019] Furthermore, in the compounds provided by this invention, when Y is N, the structure of formula I is as shown in formulas A1 to A4.

[0020] .

[0021] Furthermore, in the compounds provided by this invention, when Y is N, the structure of formula II is as shown in formulas B1 to B4.

[0022] .

[0023] Furthermore, in the compounds provided by this invention, when Y is O, the structures of Formula I and Formula II are as shown in Formulas A5~A8 and B5~B8.

[0024] .

[0025] Furthermore, in the compounds provided by this invention, when Y is S, the structures of Formula I and Formula II are as shown in Formulas A9~A12 and B9~B12.

[0026] .

[0027] Furthermore, the compounds provided by this invention have the following structures:

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[0075] .

[0076] Secondly, the present invention provides the application of the above-mentioned compounds in organic electroluminescent devices.

[0077] Thirdly, the present invention provides the application of the above-mentioned compounds in organic electroluminescent devices.

[0078] Fourthly, 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 aforementioned compound.

[0079] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0080] This invention introduces two boron atoms on either side of a six-membered heterocycle, with the boron atoms forming covalent bonds with N, O, and S, respectively, to construct a polycyclic compound. This allows the compound to maintain significant twist 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 central molecule of the six-membered heterocycle participates in conjugation and charge transfer, improving the charge distribution within the molecule through changes in the heteroatoms. This results in a strong multiple resonance thermally active delayed fluorescence (MR-TADF) effect, enabling the compound to narrow its emission spectrum and broaden its spectral coverage in OLEDs, achieving emission from blue to green light. This improves the efficiency, color purity, and other performance characteristics of organic light-emitting devices, making it widely applicable to OLED light-emitting devices and display devices. Attached Figure Description

[0081] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0082] Figure 1This is a schematic diagram of an organic electroluminescent device. In the diagram, 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 Implementation

[0083] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods and detection methods described in each embodiment are conventional methods; unless otherwise specified, the reagents and materials can be purchased commercially. Unless otherwise specified, the percentages in the following embodiments refer to mass percentages.

[0084] Preparation Example

[0085] This preparation example provides synthetic methods for 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 synthetic methods for the remaining intermediates and compounds are similar and easy to obtain. The specific synthetic routes are shown below.

[0086] Synthesis of intermediate 8:

[0087]

[0088] Synthesis of Intermediate 8-1: Under nitrogen protection, 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) were added to a reaction flask. Then, Pd₂(dba)₃ (0.54 g, 0.58 mmol) and X-Phos (0.56 g, 1.17 mmol) were added, and the mixture was heated to 108 °C for 4 h. After the reaction was complete, the mixture was cooled to room temperature, and a white precipitate formed when poured into water. The precipitate was filtered. The precipitate was washed successively with water and ethanol. Finally, intermediate 8-1 (48.30 g, 80% yield) was obtained by silica gel column chromatography and recrystallization.

[0089] Synthesis of Intermediate 8-2: Under nitrogen protection, intermediate 8-1 (45.30 g, 44.0 mmol) and dichloroethane (500 mL) were added sequentially to a three-necked flask equipped with a condenser. The temperature was lowered to 0℃~5℃, and then boron tribromide (10.99 g, 44.0 mmol) was slowly added dropwise. After the reaction was complete, the system was poured into a large amount of ice water and filtered. The filter cake was washed with water and ethanol sequentially, and finally passed through a silica gel column and recrystallized to obtain intermediate 8-2 (39.66 g, 90% yield).

[0090] Synthesis of Compound 8: Under nitrogen protection, intermediate 8-2 (35.60 g, 35.5 mmol), o-dichlorobenzene (350 mL), and boron tribromide (88.82 g, 355.3 mmol) were added sequentially to a three-necked flask equipped with a condenser. The mixture was then slowly added dropwise, and the reaction was heated to 150-160 °C for 8 h. After the reaction was complete, the system was cooled to room temperature. A large amount of water was added, resulting in the formation of a white precipitate, which was filtered. The filter cake was washed successively with water and ethanol, and the filtrate was finally purified by silica gel column chromatography and recrystallization to obtain Compound 8 (21.70 g, yield 60%).

[0091] The characterization results of compound 8 are as follows: HRMS: Measured value: 1018.5280 [M+H] + Precise quality: 1018.5285. C 70 H 65 Calculated values ​​of O3B2N3 (%): C, 82.60%; H, 6.44%; N, 4.13%; Measured values: C, 82.54%; H, 6.36%; N, 4.06%.

[0092] Synthesis of compound 26:

[0093]

[0094] The synthesis of intermediate 26-1 is the same as that of intermediate 8-1, except that raw materials 1 and 2 are replaced with raw materials 3 and 4.

[0095] The synthesis of intermediate 26-2 is the same as that of intermediate 8-2, except that intermediate 8-1 is replaced with intermediate 26-1;

[0096] The synthesis of compound 26 is the same as that of compound 8, except that intermediate 8-2 is replaced with intermediate 26-2.

[0097] The characterization results of compound 26 are as follows: HRMS: Measured value: 894.4852 [M+H] + Precision mass: 894.4859. C 61 H 61 Calculated values ​​of O4B2N (%): C, 81.97%; H, 6.88%; N, 1.57%; Measured values: C, 81.90%; H, 6.79%; N, 1.50%.

[0098] Synthesis of compound 28:

[0099]

[0100] The synthesis of intermediate 28-1 is the same as that of intermediate 8-1, except that raw material 1 is replaced with raw material 3;

[0101] The synthesis of intermediate 28-2 is the same as that of intermediate 8-2, except that intermediate 8-1 is replaced with intermediate 28-1;

[0102] The synthesis of compound 28 is the same as that of compound 8, except that intermediate 8-2 is replaced with intermediate 28-2.

[0103] The characterization results of the obtained compound 28 are as follows: HRMS: Measured value: 868.4330 [M+H]+; Precise mass: 868.4339. C 58 H 55 Calculated values ​​of O5B2N (%): C, 80.29%; H, 6.39%; N, 1.61%; Measured values: C, 80.20%; H, 6.31%; N, 1.55%.

[0104] Synthesis of compound 55:

[0105]

[0106] The synthesis of intermediate 55-1 is the same as that of intermediate 8-1, except that raw material 1 is replaced with raw material 5.

[0107] Synthesis of intermediate 55-2: Under nitrogen protection, 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) were added to a reaction flask. Then, Pd₂(dba)₃ (0.17 g, 0.18 mmol) and X-Phos (0.18 g, 0.36 mmol) were added, and the mixture was heated to 108 °C for 4 h. After the reaction was complete, the mixture was cooled to room temperature, and a white precipitate formed when poured into water. The precipitate was filtered. The precipitate was washed successively with water and ethanol. Finally, intermediate 55-2 (23.40 g, 70% yield) was obtained by silica gel column chromatography and recrystallization.

[0108] The synthesis of compound 55 is the same as that of compound 8, except that intermediate 8-2 is replaced with intermediate 55-2.

[0109] The characterization results of compound 55 are as follows: HRMS: Measured value: 1119.6270 [M+H] + Precise quality: 1119.6278. C 79 H 76 Calculated OB2N4 (%): C, 84.79%; H, 6.85%; N, 5.01%; Measured: C, 84.70%; H, 6.78%; N, 4.96%.

[0110] Synthesis of compound 136:

[0111]

[0112] The synthesis of intermediate 136-1 is the same as that of intermediate 55-1, except that raw materials 5 and 6 are replaced with raw materials 7 and 8.

[0113] The synthesis of intermediate 136-2 is the same as that of intermediate 55-2, except that intermediate 55-1 is replaced with intermediate 136-1;

[0114] The synthesis of compound 136 is based on the synthesis of compound 55, except that intermediate 55-2 is replaced with intermediate 136-2.

[0115] The characterization results of the obtained compound 136 are as follows: HRMS: Measured value: 969.5328 [M+H] + Precision quality: 969.5332. C 67 H 66 Calculated values ​​of O3B2N2 (%): C, 83.06%; H, 6.87%; N, 2.89%; Measured values: C, 83.01%; H, 6.82%; N, 2.80%.

[0116] Synthesis of compound 141:

[0117]

[0118] The synthesis of intermediate 141-1 is the same as that of intermediate 55-1, except that raw material 6 is replaced with raw material 8.

[0119] The synthesis of intermediate 141-2 is the same as that of intermediate 55-2, except that intermediate 55-1 is replaced with intermediate 141-1;

[0120] The synthesis of compound 141 is based on the synthesis of compound 55, except that intermediate 55-2 is replaced with intermediate 141-2.

[0121] The characterization results of the obtained compound 141 are as follows: HRMS: Measured value: 1119.6270 [M+H] + Precise quality: 1119.6278. C 79 H 76 Calculated OB2N4 (%): C, 84.79%; H, 6.85%; N, 5.01%; Measured: C, 84.72%; H, 6.782%; N, 4.940%.

[0122] Synthesis of compound 144:

[0123]

[0124] The synthesis of intermediate 144-1 is the same as that of intermediate 55-1, except that raw material 6 is replaced with raw material 9.

[0125] The synthesis of intermediate 144-2 is the same as that of intermediate 55-2, except that intermediate 55-1 is replaced with intermediate 144-1.

[0126] The synthesis of compound 144 is based on the synthesis of compound 55, except that intermediate 55-2 is replaced with intermediate 144-2.

[0127] The characterization results of compound 144 are as follows: HRMS: Measured value: 805.4802 [M+H] + Precision mass: 805.4809. C 76 H 70 Calculated values ​​of OB2N4S (%): C, 82.30%; H, 6.36%; N, 5.05%; Measured values: C, 82.23%; H, 6.29%; N, 5.00%.

[0128] Synthesis of Compound 150:

[0129]

[0130] The synthesis of intermediate 150-1 is the same as that of intermediate 8-1, except that raw material 1 is replaced with raw material 10.

[0131] The synthesis of intermediate 150-2 is the same as that of intermediate 8-2, except that intermediate 8-1 is replaced with intermediate 150-1;

[0132] The synthesis of compound 150 is the same as that of compound 8, except that intermediate 8-2 is replaced with intermediate 150-2.

[0133] The characterization results of the obtained compound 150 are as follows: HRMS: Measured value: 806.4806 [M+H] + Precision mass: 806.4811. C 57 H 57 B2N3 (%) Calculated values: C, 84.97%; H, 7.13%; N, 5.22%; Measured values: C, 84.90%; H, 7.05%; N, 5.18%.

[0134] Synthesis of compound 241:

[0135]

[0136] The synthesis of intermediate 241 is the same as that of intermediate 26-1, except that raw material 3 is replaced with raw material 11.

[0137] The synthesis of compound 241 is the same as that of compound 26, except that intermediate 26-1 is replaced with intermediate 241.

[0138] The characterization results of the obtained compound 241 are as follows: HRMS: Measured value: 1302.7682 [M+H] + Precise quality: 1302.7690. C 93 H 93 B2N5 (%) Calculated values: C, 85.77%; H, 7.20%; N, 5.38%; Measured values: C, 85.70%; H, 7.04%; N, 5.31%.

[0139] Synthesis of compound 243:

[0140]

[0141] The synthesis of intermediate 243 is the same as that of intermediate 8-1, except that raw material 1 is replaced with raw material 11;

[0142] The synthesis of compound 243 is the same as that of compound 8, except that intermediate 8-1 is replaced with intermediate 243.

[0143] The characterization results of the obtained compound 243 are as follows: HRMS: Measured value: 1292.7476 [M+H] + Precise mass: 1292.7482. C 91 H 91 Calculated OB2N5 (%): C, 84.57%; H, 7.10%; N, 5.42%; Measured: C, 84.49%; H, 7.02%; N, 5.36%.

[0144] Synthesis of compound 251:

[0145]

[0146] The synthesis of intermediate 251 is the same as that of intermediate 55, except that raw material 5 is replaced with raw material 12.

[0147] The synthesis of compound 251 is the same as that of compound 55, except that intermediate 55-1 is replaced with intermediate 251.

[0148] The characterization results of the obtained compound 251 are as follows: HRMS: Measured value: 1077.6266 [M+H] + Precise mass: 1077.6271. C 75 H 78 Calculated values ​​of O3B2N2 (%): C, 83.64%; H, 7.30%; N, 2.60%; Measured values: C, 83.60%; H, 7.22%; N, 2.54%.

[0149] Synthesis of compound 256:

[0150]

[0151] The synthesis of intermediate 256 is the same as that of intermediate 55, except that raw material 5 is replaced with raw material 11.

[0152] The synthesis of compound 256 is the same as that of compound 55, except that intermediate 55-1 is replaced with intermediate 256.

[0153] The characterization results of the obtained compound 256 are as follows: HRMS: Measured value: 1227.7212 [M+H] + Precise mass: 1227.7217. C 87 H 88 Calculated OB2N4 (%): C, 85.14%; H, 7.23%; N, 4.57%; Measured: C, 85.08%; H, 7.17%; N, 4.50%.

[0154] All compounds in this invention can be synthesized using the same methods as those described above. The only difference is that different raw materials need to be used to replace the original materials, and the mass amount of the raw materials needs to be changed according to the molar amount.

[0155] The performance parameters (including HOMO level, LUMO level, S1 and triplet energy T1) of some compounds synthesized in this invention (compounds 5, 7, 8, 26, 27, 28, 33, 46, 55, 60, 77, 81, 85, 97, 101, 110, 125, 136, 144, 150, 170, 181, 205, 224, 241, 243, 251 and 256) and the existing OLED luminescent material BD01 were measured. The calculation method used was B3LYP hybrid functional with basis set 6-31g(d,p). The calculation results are shown in Table 1.

[0156] Table 1. Results of performance parameter determination for compounds and existing materials.

[0157]

[0158]

[0159] As shown in Table 1, the compounds described in this invention have a suitable HOMO / LUMO ratio and a smaller singlet-triplet energy difference (ΔEst), making it easier for the triplet-to-singlet gap crossover reversal to occur.

[0160] The following section uses some of the compounds provided by this invention as examples to apply them as light-emitting host materials in organic electroluminescent devices to verify their excellent performance.

[0161] The superior effects of the OLED material of the present invention in the device are explained in detail through the device performance of Examples 1-28 and Comparative Examples 1-2. The structural fabrication process of Examples 1-28 and Comparative Examples 1-2 are exactly the same, and the same glass substrate and electrode materials are used. The electrode material film thickness is also kept consistent. The difference is that the main material of the light-emitting layer is adjusted, as detailed below.

[0162] Comparative Example 1

[0163] This comparative example provides an organic electroluminescent device, the specific structure of which is as follows: Figure 1 As 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, which are stacked in sequence.

[0164] The substrate 1 is a 0.7 mm thick glass substrate. The anode layer 2 is made of indium tin oxide (ITO) with a high work function. The hole injection layer 3 is made of HT1-doped HI-1 with a mass ratio of 97:3 and a thickness of 10 nm. The hole transport layer 4 is made of HT1 with a thickness of 60 nm. The electron blocking layer 5 is made of EB1 with a thickness of 15 nm. The light-emitting layer 6 uses BH1 as the host material and BD01 as the light-emitting material with a doping mass percentage of 5% and a thickness of 30 nm. The hole blocking layer 7 is made of HB with a thickness of 10 nm. The electron transport layer 8 is made of ET-1-doped Liq with a doping concentration of w50% and a thickness of 30 nm. The electron injection layer 9 is made of Liq with a thickness of 2 nm. The cathode layer is made of Al with a thickness of 100 nm.

[0165] The basic material structures used in each functional layer of the organic electroluminescent device in Comparative Example 1 are as follows:

[0166]

[0167]

[0168] The specific fabrication steps of the organic electroluminescent device in Comparative Example 1 are as follows:

[0169] (1) Clean the ITO anode on the transparent glass or plastic substrate by ultrasonic cleaning with deionized water, acetone and ethanol for 20 min each, and then perform plasma treatment in an oxygen atmosphere for 5 min.

[0170] (2) On the ITO anode layer, a hole injection layer material HT1:HI-1 with a mass ratio of 97:3 and a thickness of 10nm is deposited by vacuum evaporation. This layer serves as the hole injection layer.

[0171] (3) Hole transport material HT1 with a thickness of 60 nm is deposited on the hole injection layer by vacuum evaporation. This layer serves as the hole transport layer.

[0172] (4) A second hole transport material BH1 with a thickness of 15 nm is deposited on the hole transport layer HT1 by vacuum evaporation. This layer serves as an electron blocking layer.

[0173] (5) On the first electron blocking layer, a light-emitting layer is 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.

[0174] (6) Hole blocking material HB with a thickness of 10nm is deposited on the light-emitting layer by vacuum evaporation. This layer serves as the hole blocking layer.

[0175] (7) On the hole blocking layer, electron transport material ET-1:Liq is deposited by vacuum evaporation with a mass ratio of 1:1 and a thickness of 30nm. This layer serves as the electron transport layer.

[0176] (8) On the electron transport layer, the electron injection material Liq is deposited by vacuum evaporation with a thickness of 2nm. This layer serves as the electron injection layer.

[0177] (9) On the electron injection layer, cathode Al is deposited by vacuum evaporation with a thickness of 100 nm. This layer is used as the cathode conductive electrode and is called the cathode layer.

[0178] The implementation process of Examples 1 to 24 is the same as that of the comparative examples, except that compounds 5, 8, 26, 28, 33, 46, 55, 60, 77, 81, 85, 97, 101, 110, 125, 136, 144, 150, 170, 181, 205, 224, 251 and 256 provided by the present invention are used instead of the luminescent material BD01.

[0179] The cathodes and anodes of the organic electroluminescent devices in Examples 1 to 24 and the comparative examples were connected using a known driving circuit. The voltage-efficiency-current density relationship of the OLED devices was tested using a Keithley 2400 power supply and a PR670 photometer in accordance with standard methods. The light-emitting layer composition and test results of Examples 1 to 24 are shown in Table 2. The test data are relative values ​​(%).

[0180] Table 2 Performance test results of organic electroluminescent devices in each embodiment

[0181]

[0182] As shown in Table 2, the compounds provided by this invention exhibit excellent performance when used as luminescent materials in OLED devices. Compared with the BD01 material described in Comparative Example 1, the luminescent efficiency of the devices using the compounds of this invention is significantly improved, the full width at half maximum (FWHM) is narrower, and the color purity is higher. These compounds have significant application value in OLED devices and promising prospects for industrialization.

[0183] Examples 25-28

[0184] The implementation process of Examples 25-28 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.

[0185] Comparative Example 2

[0186] 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.

[0187] Table 3 Performance test results of organic electroluminescent devices in each embodiment

[0188]

[0189] As shown in Table 3, the diboron polycyclic compound centered on a six-membered heterocycle provided by this invention possesses high singlet and triplet energies, a small singlet-triplet energy difference, and suitable HOMO and LUMO energy levels. While maintaining strong rigidity, the diboron polycyclic compound exhibits a strong multiple resonance thermally active delayed fluorescence (MR-TADF) effect. When applied as a luminescent material in OLEDs, it narrows the emission spectrum. Furthermore, by varying the heteroatoms and the ring-closure mechanism, the emission position shifts from blue to red light to the green region, improving the efficiency, color purity, and other performance characteristics of organic electroluminescent devices. Therefore, it is widely applicable to OLED luminescent devices and display devices.

[0190] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications 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 protection scope defined by the present invention.

Claims

1. A compound characterized by, The compound has a structure as shown in formula I or formula II, ； X in the formula I or formula II is selected from any one of CR5R6, NR7, O, S; R5 and R6 in the CR5R6 are methyl; R7 in the NR7 is substituted or unsubstituted phenyl, and the substituent is C1-C5 alkyl; Y in the formula I or formula II is selected from any one of N, O, S; X1 and X2 in the formula I or formula II are selected from any one of NR8, O, S, Se; R8 in the NR8 is substituted or unsubstituted phenyl, and the substituent is C1-C5 alkyl; Y1 and Y2 in the formula I or formula II are selected from any one of NR9, O, S; R9 in the NR9 is substituted or unsubstituted phenyl, and the substituent is C1-C5 alkyl; R1, R2, R3 and R4 in the formula I or formula II are selected from any one of methyl, ethyl, isopropyl and tert-butyl; In the formula I or formula II, m and n are 0.

2. The compound of claim 1, wherein When Y is N, the formula I is selected from any one of the following structures, 。 3. The compound of claim 1, wherein When Y is N, the formula II is selected from any one of the following structures, 。 4. The compound of claim 1, wherein When Y is O, the formula I and the formula II are selected from any one of the following structures, 。 5. The compound of claim 1, wherein When Y is S, the formula I and the formula II are selected from any one of the following structures, 。 6. A compound characterized by, The compound is selected from any one of the following structures, 。 7. Use of the compound according to any one of claims 1 to 6 in an organic electroluminescent device.

8. Use of the compound according to any one of claims 1 to 6 in an organic electroluminescent device.

9. An organic electroluminescent device comprising an anode layer, a cathode layer, and an organic thin film layer between the anode layer and the cathode layer, the organic thin film layer comprising 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 6.

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