Boron nitrogen-phosphorus oxygen skeleton fused compound and organic electroluminescent device thereof

Abstract

The invention belongs to the technical field of organic electroluminescence, and particularly relates to a boron nitrogen-phosphorus oxygen skeleton fused series compound and an organic electroluminescence device.A phosphorus oxygen unit is introduced into a boron / nitrogen type multiple resonance thermal activation delayed fluorescence skeleton through a one-step phosphorus oxygen post-modification method, metal does not need to participate in the synthesis route, the yield is high, and the method is suitable for industrial production. A universal strategy is provided for expanding the structural diversity of an MR-TADF system, the provided multi-resonance type thermally activated delayed fluorescent material containing fusion of the boron, nitrogen and phosphorus oxygen frameworks has the characteristic of wide color gamut emission, and an organic electroluminescent device prepared by using the material as a luminescent material realizes wide color gamut and narrow spectrum TADF emission and has wide application prospects. And the electroluminescent device has relatively low efficiency roll-off, and is an organic luminescent functional material with good performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic electroluminescent materials, and particularly relates to a boron-nitrogen-phosphorus-oxygen skeleton fused compound and an organic electroluminescent device thereof. BACKGROUND

[0002] Organic light-emitting diodes (OLEDs) have the advantages of bright color, fast response speed, large viewing angle, low driving voltage, energy saving, lightness and thinness, and flexible display. Since 2012, Adachi et al. reported high-efficiency electroluminescent devices based on pure organic thermally activated delayed fluorescence (TADF) compounds, and such materials have been widely studied. TADF materials use pure organic building blocks, and through special molecular design, the highest occupied molecular orbital and the lowest unoccupied molecular orbital are effectively separated, reducing the energy level difference between the lowest excited singlet state and the triplet state, so that triplet excitons can be converted into singlet excitons through the inverse intersystem crossing process, and then emit fluorescence by radiative transition to the ground state, with an exciton utilization rate of 100%.

[0003] Traditional TADF materials with D-A structure have a large half-peak width (half-peak width greater than 70 nm) due to large structural relaxation, and the corresponding OLED device has low color purity, which cannot meet the requirements of high color purity display. In 2016, Hatakeyama et al. reported a new type of thermally activated delayed fluorescence (MR-TADF) material based on boron / nitrogen multiple resonance structure. Such materials have high quantum yield and narrow emission spectrum, and the electroluminescent devices prepared using such materials as the light-emitting layer have high efficiency and high color purity.

[0004] Although the high color purity of MR-TADF materials has great advantages in display and lighting applications, the construction of such materials currently mainly adopts the de novo synthesis strategy. In this strategy, the boron precursor is designed through reverse synthesis analysis, and is converted into the target compound through two main boronization methods (one-pot boronization method and one-time boronization method). This seriously limits the structural diversity and flexibility of property adjustment of MR-TADF materials. Secondly, most of the reported MR-TADF materials have rigid planar molecular skeletons due to their inherent characteristics, which easily cause serious aggregation-induced quenching and spectral broadening at high doping concentrations. At the same time, due to the small spin-orbital coupling effect between the singlet and triplet states of such materials, the reverse intersystem crossing rate is slow, which seriously limits the commercial development of OLED devices. SUMMARY

[0005] To solve the problems in the background art, the first object of the present application is to provide a boron-nitrogen-phosphorus-oxygen skeleton fused compound, the molecular structure of which is shown in the following formula (I-1) or formula (I-2) or formula (I-3): ; ring A, ring B, ring C, ring D each independently represents a C6~C 60 aromatic ring or a C5~C 60 heteroaromatic ring; no connection between ring A and ring C, between ring B and ring D, or connection by a C-C single bond, or connection by one of O, S, Se, C=O, S(=O)2, P=O(R6), NR7, PR8, C(R9)(R 10 ), Si(R 11 )(R 12 ), Ge(R 13 )(R 14 ), BR 15 ; X is selected from one of C, Si, Ge; Z is selected from N or CR 16 ; n is each independently selected from 1 to the maximum number of substituents allowed for the ring; R a , R b , R c , R d , R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 are the same or different, each independently selected from hydrogen, deuterium, tritium, halogen, cyano, trifluoromethyl, substituted or unsubstituted C1~C 30 chain alkyl, C1~C 30 alkoxy, C1~C 30 alkylthio, C1~C 30 cycloalkyl, C2~C 30 aliphatic chain amine, C4~C 30 cyclic aliphatic chain amine, C6~C 30 aryl amine, C4~C 30 heteroaryl amine, C6~C 30 aryloxy, C6~C 30 aryl boron, C6~C 30 aryl, C4~C 30 heteroaryl; and are not connected or connected by a C-C bond to their adjacent aromatic or heteroaromatic ring, respectively; R a , R b , R c , R d are not connected or connected in a ring; When substituents are present, each substituent is independently selected from deuterium, tritium, halogen, cyano, trifluoromethyl, C1~C. 30 Chain alkyl, C1~C 30 Alkoxy, C1~C 30 Alkylthio group, C3~C 30 cycloalkyl, C2~C 30 Aliphatic chain hydrocarbon amine group, C4~C 30 Cyclic aliphatic chain hydrocarbon amino group, C6~C 30 arylamine, C4~C 30 heteroarylamine, C6~C 30 aryloxy group, C6~C 30 Aromatic boronyl, C6~C 30 Aryl, C4~C 30 Mixed aromatic compounds.

[0006] As a preferred embodiment of the present invention, rings A, B, C, and D are each independently represented as C6~C6. 30 Aromatic rings or C5~C 30 The heterocyclic aromatic rings, with rings A, B, C, and D each independently represented as C6~C6. 30 Aromatic rings or C5~C 30 The heterocyclic aromatic rings have no connection between ring A and ring C, or between ring B and ring D, or are connected by single C-C bonds, or by O, C=O, S(=O)2, Se, NR7, C(R9)(R 10 ), Si(R) 11 (R) 12 A type of connection in ).

[0007] As a preferred embodiment of the present invention, X is selected from C or Si.

[0008] As a preferred embodiment of the present invention, R1 and R3 may be the same or different, and are selected from C1 to C2. 12 Chain alkyl groups, substituted or unsubstituted C6~C 30 Aryl.

[0009] As a preferred embodiment of the present invention, R2 is selected from hydrogen, C1~C123 ... 12 Chain alkyl, substituted or unsubstituted C6~C 30 arylamine, substituted or unsubstituted C4~C 30 heteroarylamine, substituted or unsubstituted C4~C 30 Mixed aromatic compounds.

[0010] Preferably, R4 and R5 may be the same or different, and are selected from substituted or unsubstituted C6~C. 30 Aryl.

[0011] As a preferred embodiment of the present invention, the specific structure of the compound is as follows: ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； .

[0012] As a preferred embodiment of the present invention, the compound is synthesized using a one-step phosphorus-oxygen post-modification method, and the synthetic routes of formulas (I-1), (I-2), and (I-3) are as follows: .

[0013] Another object of the present invention is to provide an organic electroluminescent device comprising a light-emitting layer containing the aforementioned boron-nitrogen-phosphorus-oxygen fused compound.

[0014] As a preferred embodiment of the present invention, the organic electroluminescent device is used to manufacture display devices, lighting sources, signal lights, and signs. The display devices include mobile phone displays, computer displays, television displays, smartwatch displays, smart car display panels, and VR or AR helmet displays.

[0015] The beneficial effects of this invention are as follows: The boron-nitrogen-phosphorus-oxygen fusion framework compounds provided by this invention introduce P=O units into a B / N type multiple resonance thermally activated delayed fluorescence framework via a one-step phosphorus-oxygen (P=O) post-modification method. This synthetic route does not require metal participation, has high yield, and provides a universal strategy for expanding the structural diversity of MR-TADF systems. Moreover, introducing P=O groups at the meta position of boron atoms can effectively alleviate H···H mutual repulsion and improve the rigidity and planarity of the molecule, thereby achieving narrow-band emission and fast radiative transitions. In particular, the oxygen atom in the P=O group deviates from the π-conjugation of the framework. The planar shape allows the excited state to exhibit a mixed n→π* and π→π* transition characteristic, which enhances spin-orbit coupling, promotes spin-flipping, and improves device performance. At the same time, the sp³ hybridization of the P atom introduces steric hindrance, which can effectively reduce intermolecular π···π stacking, thereby suppressing aggregation-induced quenching and spectral broadening. In addition, the different donor-acceptor properties of the P=O group and the nitrogen atom cause a significant blue shift in the emission color. By changing the peripheral donor groups, the emission color can be further adjusted by utilizing the different electron-donating capabilities of these groups and the degree of conjugation of the highest occupied orbital, demonstrating strong adaptability. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the organic electroluminescent device structure of the present invention; Figure 2 Compound 8 in this invention, at 298 K, 1×10-5 Emission spectrum of M in toluene solution. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] Unless otherwise specified, all reagents and instruments used were commercially available products. Some reaction compounds were purchased from a supplier (Zhengzhou Alpha Chemical Co., Ltd.), while others that could not be directly purchased were prepared by simple reactions from commercially available raw materials. Synthesis Examples

[0019] Example 1: Synthesis of Compound 8

[0020] ; Under a nitrogen atmosphere, phenylphosphonic acid (0.282 g, 2.0 mmol), substrate 1 (1.640 g, 1.0 mmol), and 4-dimethylaminopyridine (DMAP) (0.590 g, 4.8 mmol) were placed in a pressure-resistant Schlenk tube with a magnetic stir bar. Dichloroethane (DCE) (15 mL) was then added using a syringe. The mixture was stirred until a homogeneous solution was formed. Trifluoromethanesulfonic anhydride (Tf₂O) (0.8 mL, 4.8 mmol) was then added using a syringe. The reaction mixture was heated in an oil bath at 120 °C for 20 hours. After the reaction system cooled to room temperature, the reaction was quenched with saturated sodium bicarbonate solution. The reaction mixture was extracted with dichloromethane and water, and the organic phase was dried with anhydrous magnesium sulfate. The organic phase was then evaporated to dryness under reduced pressure. The crude product was purified by silica gel column chromatography. A blue-green solid, compound 8 (0.648 g, 85%), was obtained.

[0021] MALDI-TOF-MS results: Molecular ion peak: 762.23; Elemental analysis results: Theoretical values: C, 81.88; H, 6.87; B, 1.42; N, 3.67; O, 2.10; P, 4.06; Experimental values: C, 81.81; H, 6.80; N, 3.69; Compound 8 at 298 K, 1×10 -5 The emission spectrum of M in toluene solution is as follows: Figure 2 As shown.

[0022] Example 2: Synthesis of Compound 80 ; Compound 80 is synthesized in the same way as compound 8, except that substrate 1 is replaced by substrate 2.

[0023] MALDI-TOF-MS results: Molecular ion peak 570.50; Elemental analysis results: Theoretical values ​​C, 75.81; H, 3.53; B, 1.90; N, 4.91; O, 8.42; P, 5.43; Experimental values ​​C, 75.61; H, 3.47; N, 4.86.

[0024] Example 3: Synthesis of Compound 95 ; Compound 95 was synthesized using the same method as compound 8, except that substrate 1 was replaced with substrate 3.

[0025] MALDI-TOF-MS results: Molecular ion peak 870.80; Elemental analysis results: Theoretical values ​​C, 85.52; H, 4.63; B, 1.24; N, 3.22; O, 1.84; P, 3.56; Experimental values ​​C, 85.66; H, 4.54; N, 3.27.

[0026] Example 4: Synthesis of Compound 110 ; Compound 110 was synthesized in the same way as compound 8, except that substrate 1 was replaced with substrate 4.

[0027] MALDI-TOF-MS results: Molecular ion peak 720.31; Elemental analysis results: Theoretical values ​​C, 80.01; H, 4.20; B, 1.50; N, 7.78; O, 2.22; P, 4.30; Experimental values ​​C, 80.11; H, 4.15; N, 7.85.

[0028] Example 5: Synthesis of Compound 178 ; Compound 178 was synthesized in the same way as compound 8, except that substrate 1 was replaced with substrate 5.

[0029] MALDI-TOF-MS results: Molecular ion peak 740.65; Elemental analysis results: Theoretical values ​​C, 81.08; H, 5.17; B, 1.46; N, 3.78; O, 4.32; P, 4.18; Experimental values ​​C, 81.20; H, 5.14; N, 3.89.

[0030] Example 6: Synthesis of Compound 415 ; Compound 415 was synthesized using the same method as compound 8, except that substrate 1 was replaced with substrate 6.

[0031] MALDI-TOF-MS results: Molecular ion peak 869.42; Elemental analysis results: Theoretical values ​​C, 84.24; H, 4.29; B, 1.24; N, 4.83; O, 1.84; P, 3.56; Experimental values ​​C, 84.31; H, 4.36; N, 4.89.

[0032] Example 7: Synthesis of Compound 447 ; Compound 447 was synthesized in the same way as compound 8, except that substrate 1 was replaced with substrate 7.

[0033] MALDI-TOF-MS results: Molecular ion peak 719.30; Elemental analysis results: Theoretical values: C, 80.12; H, 3.78; B, 1.50; N, 5.84; O, 4.45; P, 4.30; Experimental values: C, 80.34; H, 3.92; N, 5.89.

[0034] Example 8: Synthesis of Compound 499 ; Compound 499 was synthesized using the same method as compound 8, except that substrate 1 was replaced with substrate 8.

[0035] MALDI-TOF-MS results: Molecular ion peak 738.25; Elemental analysis results: Theoretical values: C, 84.42; H, 6.44; B, 1.15; N, 2.98; O, 1.70; P, 3.30; Experimental values: C, 84.31; H, 6.32; N, 2.32.

[0036] Example 9: Synthesis of Compound 507 ; Compound 507 was synthesized in the same way as compound 8, except that substrate 1 was replaced with substrate 9.

[0037] MALDI-TOF-MS results: Molecular ion peak 838.52; Elemental analysis results: Theoretical values ​​C, 83.04; H, 6.73; B, 1.29; N, 3.34; O, 1.91; P, 3.69; Experimental values ​​C, 83.21; H, 6.84; N, 3.43.

[0038] Example 10: Synthesis of Compound 517 ; Compound 517 is synthesized in the same way as compound 8, except that trifluoromethylphenylphosphonic acid is used instead of phenylphosphonic acid.

[0039] MALDI-TOF-MS results: Molecular ion peak 830.46; Elemental analysis results: Theoretical values: C, 76.62; H, 6.19; B, 1.30; F, 6.86; N, 3.37; O, 1.93; P, 3.73; Experimental values: C, 76.47; H, 6.31; N, 3.46.

[0040] Example 11: Synthesis of Compound 529 ; Compound 529 is synthesized in the same way as compound 8, except that compound 8 is used to replace substrate 1.

[0041] MALDI-TOF-MS results: Molecular ion peak 884.85; Elemental analysis results: Theoretical values: C, 78.73; H, 6.27; B, 1.22; N, 3.17; O, 3.62; P, 7.00; Experimental values: C, 78.69; H, 6.30; N, 3.14.

[0042] Example 12: Synthesis of Compound 564 ; Compound 564 was synthesized using the same method as compound 8, except that substrate 1 was replaced with compound 80.

[0043] MALDI-TOF-MS results: Molecular ion peak: 692.31; Elemental analysis results: Theoretical values: C, 72.86; H, 3.35; B, 1.56; N, 4.05; O, 9.24; P, 8.95; Experimental values: C, 72.82; H, 3.21; N, 4.23.

[0044] Example 13: Synthesis of Compound 575 ; Compound 575 was synthesized using the same method as compound 8, except that substrate 1 was replaced with compound 95.

[0045] MALDI-TOF-MS results: Molecular ion peak 992.86; Elemental analysis results: Theoretical values ​​C, 82.26; H, 4.37; B, 1.09; N, 2.82; O, 3.22; P, 6.24; Experimental values ​​C, 82.33; H, 4.31; N, 2.89.

[0046] Example 14: Synthesis of Compound 590 ; Compound 590 was synthesized using the same method as compound 8, except that substrate 1 was replaced with compound 110.

[0047] MALDI-TOF-MS results: Molecular ion peak 842.61; Elemental analysis results: Theoretical values ​​C, 76.97; H, 3.95; B, 1.28; N, 6.65; O, 3.80; P, 7.35; Experimental values ​​C, 76.88; H, 3.55; N, 6.51.

[0048] Example 15: Synthesis of Compound 633 ; Compound 633 was synthesized using the same method as compound 8, except that substrate 1 was replaced with compound 178.

[0049] MALDI-TOF-MS results: Molecular ion peak 862.71; Elemental analysis results: Theoretical values ​​C, 77.97; H, 4.79; B, 1.25; N, 3.25; O, 5.56; P, 7.18; Experimental values ​​C, 77.89; H, 4.65; N, 3.33.

[0050] Example 16: Synthesis of Compound 791 ; Compound 791 was synthesized using the same method as compound 8, except that substrate 1 was replaced with compound 447.

[0051] MALDI-TOF-MS results: Molecular ion peak 841.33; Elemental analysis results: Theoretical values ​​C, 77.07; H, 3.59; B, 1.28; N, 4.99; O, 5.70; P, 7.36; Experimental values ​​C, 77.15; H, 3.67; N, 4.79.

[0052] Example 17: Synthesis of Compound 833 ; Compound 833 is synthesized in the same way as compound 8, except that substrate 1 is replaced by compound 415.

[0053] MALDI-TOF-MS results: Molecular ion peak 991.86; Elemental analysis results: Theoretical values ​​C, 81.14; H, 4.07; B, 1.09; N, 4.24; O, 3.23; P, 6.25; Experimental values ​​C, 81.33; H, 4.28; N, 4.39.

[0054] Example 18: Synthesis of Compound 839 ; Compound 839 is synthesized in the same way as compound 8, except that substrate 1 is replaced by substrate 11.

[0055] MALDI-TOF-MS results: Molecular ion peak 706.53; Elemental analysis results: Theoretical values: C, 83.29; H, 4.57; B, 1.53; N, 3.96; O, 2.26; P, 4.38; Experimental values: C, 83.15; H, 4.39; N, 3.99.

[0056] Example 19: Synthesis of Compound 897 ; Compound 897 was synthesized in the same way as compound 8, except that trifluoromethylphenylphosphonic acid was used instead of phenylphosphonic acid, and compound 517 was used instead of substrate 1.

[0057] MALDI-TOF-MS results: Molecular ion peak 1020.62; Elemental analysis results: Theoretical values: C, 70.59; H, 5.23; B, 1.06; F, 11.17; N, 2.74; O, 3.13; P, 6.07; Experimental values: C, 70.64; H, 5.32; N, 2.66.

[0058] In addition, it should be noted that other compounds in this application can be obtained by referring to the preparation methods of the examples listed above, so they will not be listed one by one here.

[0059] Device Examples The technical effects and advantages of the present invention will be demonstrated and verified by specifically applying the compounds of the present invention to organic electroluminescent devices and testing their actual performance.

[0060] The structure of an organic electroluminescent device is as follows: ITO(10nm) / HI(10nm) / HT(30nm) / EBL(10nm) / Host:Dopant(5wt%,30nm) / HBL(10nm) / ET(30nm) / LiF(0.5nm)Al(150nm).

[0061] Combination Figure 1 The fabrication process of organic electroluminescent devices is described below: The glass substrate coated with anolyte was ultrasonically treated in a commercial cleaning agent, rinsed in deionized water, ultrasonically degreased in an acetone:ethanol mixed solvent, baked in a clean environment until all moisture was removed, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam. It was then placed in a vacuum chamber and evacuated to a vacuum level of 1×10⁻⁶. -5 ~9×10 -3Pa, using a co-evaporation method, firstly, ITO (10nm) is evaporated as anode 1, and then hole injection layer 2 (HT, 30nm), hole transport layer 3 (HT, 30nm), electron blocking layer 4 (EBL, 10nm), light emitting layer 5 (Host:Dopant, 5wt%, 30nm), hole blocking layer 6 (HBL, 10nm), electron transport layer 7 (ET, 30nm), and electron injection layer 8 (LiF, 0.5nm) are evaporated on anode 1 in sequence. Finally, Al (150nm) is evaporated to form a semi-transparent cathode 9.

[0062] The structures of the compounds used in the above preparation process are as follows: ; The Dopant used in the above-mentioned device preparation adopted compounds C1~C3 as comparative examples 1~3, and the compounds in Table 1 below were used as examples 1~19.

[0063] Device performance evaluation: The device's current, voltage, brightness, and emission spectrum characteristics were simultaneously tested using a PhotoResearch PR655 spectrophotometer and a Keithley K2400 digital source meter system. Performance testing was conducted at room temperature and under ambient conditions. (1 cd / m²) 2 The voltage at which light is emitted is the turn-on voltage, and the emission wavelength and full width at half maximum (FWHM) are 10 cd / m. 2 The spectral values ​​during emission, and the external quantum efficiency (EQE) of the device, are calculated based on the Lambaugh distribution of emission, using current density, luminance, electroluminescence spectrum, and the apparent function. The maximum external quantum efficiency is EQE. max 1000cd / m 2 The external quantum efficiency during emission is EQE 1000 Efficiency rolls off to 1~EQE 1000 / EQE max This refers to 1000 cd / m 2 The external quantum efficiency during emission is the percentage decrease from the maximum external quantum efficiency relative to the maximum external quantum efficiency. Device lifetime (T90,h) refers to the device's initial luminance of 1000 cd / m². 2 When the brightness of the device drops to 90% of its initial brightness (i.e., the brightness of the device drops to 500 cd / m²), 2 The time required (in hours). Test data is shown in Table 1 below:

[0064] The series of compounds provided by this invention still exhibit narrow electroluminescence spectra, high external quantum efficiency, and small efficiency roll-off even at high concentrations (5 wt%) of doping. Furthermore, compared to the boron-nitrogen-structured multiple resonance TADF dyes in the comparative example, the devices fabricated using the series of compounds provided by this invention have longer lifetimes. This is because the series of compounds provided by this invention introduces phosphorus-oxygen locking, which enhances the rigidity of the MR core planarity, reduces the degree of excited-state structural relaxation, and suppresses nonradiative transitions. Simultaneously, the trigonal pyramidal configuration of the sp³ hybridized P atoms introduces steric hindrance, effectively reducing intermolecular π···π stacking, thereby suppressing aggregation-induced quenching and spectral broadening. In addition, the introduction of the n→π* and π→π* mixed transition characteristics of the P=O group enhances spin-orbit coupling, suppresses triplet-triplet exciton annihilation, and slows down efficiency roll-off, thus improving the overall performance of the device in multiple aspects.

[0065] The experimental data above show that the boron, nitrogen, phosphorus and oxygen fusion multi-resonance thermally activated delayed fluorescence material provided by this invention has the characteristic of wide color gamut emission. Organic electroluminescent devices prepared as luminescent materials achieve wide color gamut and narrow spectrum TADF emission, and the electroluminescent devices have low efficiency roll-off, making them high-performance organic light-emitting functional materials.

[0066] The above embodiments only list the effect data of devices made from a portion of the structures. This is a representative sampling test. Based on the experimental data, the overall data is not significantly different and can represent the effects of other unlisted structures.

[0067] Those skilled in the art will readily recognize that many modifications and variations can be made to this invention without departing from its spirit and scope. Therefore, it is contemplated that this invention covers the modifications and variations provided within the scope of the appended claims and their equivalents.

Claims

1. A compound with a boron-nitrogen-phosphorus-oxygen fused skeleton, characterized in that, The general molecular structural formula of this compound is shown in formula (I-1), (I-2), or (I-3) below: ； Rings A, B, C, and D are each independently represented as C6~C6. 60 Aromatic rings or C5~C 60 The aromatic rings; there is no connection between ring A and ring C, or between ring B and ring D, or they are connected by single C-C bonds, or by O, S, Se, C=O, S(=O)2, P=O(R6), NR7, PR8, C(R9)(R 10 ), Si(R) 11 (R) 12 ), Ge(R) 13 (R) 14 ), BR 15 A type of connection; X is selected from one of C, Si, and Ge; Z is selected from N or CR. 16 ; n are each independently selected from 1 to the maximum permissible number of substituents in the ring; R a R b R c R d , R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 R 12 R 13 R 14 R 15 R 16 Whether the groups are the same or different, each is independently selected from hydrogen, deuterium, tritium, halogen, cyano, trifluoromethyl, substituted or unsubstituted C1~C. 30 Chain alkyl, C1~C 30 Alkoxy, C1~C 30 Alkylthio, C1~C 30 cycloalkyl, C2~C 30 Aliphatic chain hydrocarbon amine group, C4~C 30 Cyclic aliphatic chain hydrocarbon amino group, C6~C 30 arylamine, C4~C 30 heteroarylamine, C6~C 30 aryloxy group, C6~C 30 Aromatic boronyl, C6~C 30 Aryl, C4~C 30 Heteroaryl groups; and are either not connected to or connected to their neighboring aromatic or heteroaryl rings via C-C bonds; R a Between, R b Between, R c Between, R d They are either not connected or connected in a loop; When substituents are present, each substituent is independently selected from deuterium, tritium, halogen, cyano, trifluoromethyl, C1~C. 30 Chain alkyl, C1~C 30 Alkoxy, C1~C 30 Alkylthio group, C3~C 30 cycloalkyl, C2~C 30 Aliphatic chain hydrocarbon amine group, C4~C 30 Cyclic aliphatic chain hydrocarbon amino group, C6~C 30 arylamine, C4~C 30 heteroarylamine, C6~C 30 aryloxy group, C6~C 30 Aromatic boronyl, C6~C 30 Aryl, C4~C 30 Mixed aromatic compounds.

2. The compound with a boron-nitrogen-phosphorus-oxygen fused framework according to claim 1, characterized in that, Rings A, B, C, and D are each independently represented as C6~C6. 30 Aromatic rings or C5~C 30 The heterocyclic aromatic rings, with rings A, B, C, and D each independently represented as C6~C6. 30 Aromatic rings or C5~C 30 The heterocyclic aromatic rings have no connection between ring A and ring C, or between ring B and ring D, or are connected by single C-C bonds, or by O, C=O, S(=O)2, Se, NR7, C(R9)(R 10 ), Si(R) 11 (R) 12 A type of connection in ).

3. The compound with a boron-nitrogen-phosphorus-oxygen fused framework according to claim 1, characterized in that, X is selected from C or Si.

4. The compound with a boron-nitrogen-phosphorus-oxygen fused framework according to claim 1, characterized in that, R1 and R3 may be the same or different, and are selected from C1 to C2. 12 Chain alkyl groups, substituted or unsubstituted C6~C 30 Aryl.

5. The compound with a boron-nitrogen-phosphorus-oxygen fused framework according to claim 1, characterized in that, R2 is selected from hydrogen, C1~C123 ... 12 Chain alkyl, substituted or unsubstituted C6~C 30 arylamine, substituted or unsubstituted C4~C 30 heteroarylamine, substituted or unsubstituted C4~C 30 Mixed aromatic compounds.

6. The compound with a boron-nitrogen-phosphorus-oxygen fused framework according to claim 1, characterized in that, R4 and R5 may be the same or different, and are selected from substituted or unsubstituted C6~C. 30 Aryl.

7. The compound with a boron-nitrogen-phosphorus-oxygen fused framework according to claim 1, characterized in that, The specific structure of this compound is as follows: ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； 。 8. The compound with a boron-nitrogen-phosphorus-oxygen fused framework according to claim 1, characterized in that, The compound was synthesized using a one-step phosphorus-oxygen post-modification method. The synthetic routes for formulas (I-1), (I-2), and (I-3) are as follows: 。 9. An organic electroluminescent device, comprising a light-emitting layer, characterized in that, The light-emitting layer contains a compound with a boron-nitrogen-phosphorus-oxygen framework fused according to any one of claims 1 to 8.

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

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