Polycyclic aromatic compound and organic electroluminescent device

Abstract

The invention discloses a polycyclic aromatic compound and an organic electroluminescent device, and relates to the technical field of organic photoelectric materials. The polycyclic aromatic compound has a structure as shown in formula I. In the formula I, ring A is a substituted or unsubstituted benzene ring; at least one of Ra, Rb, Rc and Rd is selected from a formula I-a; wherein Z3 is respectively and independently selected from Si or Ge. The parent nucleus structure of the polycyclic aromatic compound provided by the invention has a B-N coordination structure, a carbazole structure and a large conjugated system fused by multiple aromatic rings, a rigid skeleton is formed by B and N atoms, and excessive aggregation of molecules can be inhibited by steric hindrance of Si or Ge, so that carrier transport blocking or exciton quenching caused by aggregation is avoided, and the performance of the compound is improved. Meanwhile, the dissolvability and processability of the material are improved, and the stability and efficiency of device performance are further guaranteed. The service life and the efficiency of a device prepared from the doping material are obviously improved.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic materials technology, and more specifically, to a polycyclic aromatic compound and an organic electroluminescent device. Background Technology

[0002] Organic light-emitting diodes (OLEDs) have become a highly promising new display technology due to their significant advantages such as flexibility, fast response, wide viewing angle, thinness, high brightness, and vibrant colors. They are widely used in smart terminal displays and solid-state lighting. The core of OLEDs lies in organic light-emitting materials, which achieve full-color gamut emission by mixing red, green, and blue materials. The development of novel light-emitting materials is crucial to the advancement of electroluminescence technology and is a focus of industry research.

[0003] Currently, traditional fluorescent doped materials are limited by technology, enabling only 25% singlet exciton emission, with a maximum internal quantum efficiency of only 25% and an external quantum efficiency generally below 5%. While phosphorescent materials can achieve 100% internal quantum efficiency, they suffer from high cost, poor stability, poor color purity, and efficiency roll-off, limiting their application in the OLED field. With the increasing demands for color rendering standards in the 5G era, not only are high-efficiency and stable materials required, but also narrower half-widths (HWHMs) are needed to improve color purity. Significant breakthroughs have been achieved in blue fluorescent doped materials through molecular engineering, with some boron-based materials achieving HWHMs below 30nm. However, research in the green region has largely focused on phosphorescent doped materials, where narrowing the emission peak shape is difficult. Therefore, developing high-efficiency green fluorescent doped materials with narrow HWHMs is of great significance.

[0004] In the research and development of red light materials, the mainstream approach has been to construct novel red organic electroluminescent materials that utilize multiple vibrational effects by condensing boron atoms with heteroatoms such as nitrogen and oxygen into polycyclic aromatic compounds. These fluorescent molecules possess high radiative transition rates, narrow full width at half maximum (FWHM), and high color purity, but they suffer from shortcomings in device lifetime and luminous efficiency, posing numerous challenges to industrialization. Therefore, developing new materials remains a pressing issue for those skilled in the art.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a polycyclic aromatic compound and an organic electroluminescent device. The polycyclic aromatic compound provided by this invention has the advantage that when used in an organic electroluminescent device, it simultaneously improves the luminous efficiency of the device and extends its service life.

[0007] This invention is implemented as follows: In a first aspect, the present invention provides a polycyclic aromatic compound having the structure shown in Formula I: ; Wherein, ring A is a substituted or unsubstituted benzene ring; At least one of Z1 and Z2 exists, and Z1 and Z2 are independently selected from chemical bonds, BR1, CR2R3, NR4, PR5, SiR6R7, GeR8R9, S, O, CO, and SO2, respectively; R1-R9 are independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, hydroxyl, cyano, CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C6-C30 heteroaryl, wherein the heteroatom contains at least one of O, S, N, Si, Ge, or Se; when Z1 or Z2 has two substituents, the two adjacent substituents are independent of each other or connected to each other to form a ring; X1 and X2 are independently selected from N or C, and X1 and X2 are not the same; R a R b R c R d Each of the following is independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, formula Ia, hydroxyl, cyano, CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, wherein the heteroatom contains at least one of O, S, N, Si, Ge or Se; and R a R b R c R d At least one of them is selected from formula Ia; n is independently selected from integers from 0 to 5; m is independently selected from integers from 0 to 3; p is independently selected from integers from 0 to 2; q is independently selected from integers from 0 to 5; R a R b R c Or R d When the number of substituents is greater than 1, two adjacent substituents are independent of each other or connected to each other to form a ring;

[0008] Z3 is independently selected from either Si or Ge; o is an integer independently selected from 0 to 2; R 10 -R 12 Each is independently selected from deuterium, halogen, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, substituted or unsubstituted C7-C30 aralkyl, and substituted or unsubstituted C3-C30 cycloalkyl. R 13 -R14 Each of the following is independently selected from hydrogen, deuterium, fluorine, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C3-C30 heterocycloalkyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C6-C30 heteroaryl.

[0009] In a second aspect, the present invention provides an organic electroluminescent device, comprising an anode and a cathode, and an organic thin film layer disposed between the anode and the cathode, the organic thin film layer comprising a polycyclic aromatic compound as described in any of the above embodiments.

[0010] The present invention has the following beneficial effects: The polycyclic aromatic compounds provided by this invention have a BN coordination structure and a carbazole structure as their parent core, where A is a substituted or unsubstituted benzene ring. In this case, the parent core structure also possesses a large conjugated system of fused polycyclic aromatic rings, forming a rigid framework through B and N atoms. The BN coordination structure can regulate charge, effectively balancing carrier (electron and hole) concentrations, reducing carrier recombination, and improving device efficiency. Simultaneously, the stable BN coordination bonds reduce energy loss during carrier transport, extending the effective carrier transport time and indirectly extending device lifetime. The large conjugated system of fused polycyclic aromatic rings endows the material with high carrier mobility, making carrier transport more efficient and reducing the probability of recombination during transport, further improving device efficiency. The rigid framework enhances the chemical and thermal stability of the material, preventing performance degradation due to material decomposition and structural collapse during device operation, thus extending device lifetime. The carbazole structure itself possesses high conjugation properties, which on the one hand improves intermolecular stacking and optimizes carrier transport channels; on the other hand, it can regulate the molecular arrangement, promote horizontal molecular alignment, enhance the light extraction efficiency of the emissive layer, and thus improve the device's luminous efficiency. In this invention, through R... a R b R c R d At least one substituent selected from formula Ia is present, wherein the steric hindrance of Si or Ge can suppress excessive molecular aggregation, avoiding carrier transport obstruction or exciton quenching caused by aggregation, while improving the solubility and processability of the material, further ensuring the stability and efficiency of device performance. Devices fabricated using the doped materials of this invention exhibit significantly improved lifetime and efficiency. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 The above is the 1H NMR spectrum of polycyclic aromatic compound 187 provided in Example 1 of this invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0014] This invention provides a polycyclic aromatic compound having the structure shown in Formula I: ; Wherein, ring A is a substituted or unsubstituted benzene ring; At least one of Z1 and Z2 must be present, that is, Z1 is present, Z2 is present, or both Z1 and Z2 are present. It should be noted that when either Z1 or Z2 is absent, it indicates that there are no chemical bonds or substituents at the corresponding site, and in this case, the corresponding site cannot form a ring.

[0015] Wherein, Z1 and Z2 are independently selected from chemical bonds, BR1, CR2R3, NR4, PR5, SiR6R7, GeR8R9, S, O, CO, and SO2, respectively; R1-R9 are independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, hydroxyl, cyano, -CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C6-C30 heteroaryl. Its heteroatom contains at least one of O, S, N, Si, Ge or Se; when Z1 or Z2 has two substituents, the two adjacent substituents are independent of each other or connected to each other to form a ring; it should be noted that "the two adjacent substituents are independent of each other or connected to each other to form a ring" means that when Z1 or Z2 is selected as CR2R3, SiR6R7, GeR8R9, R2 and R3 are independent of each other or connected to each other to form a ring, or R6 and R7 are independent of each other or connected to each other to form a ring, or R8 and R9 are independent of each other or connected to each other to form a ring.

[0016] X1 and X2 are independently selected from N or C, and X1 and X2 are not the same. That is, when X1 is N, X2 is C; when X1 is C, X2 is N.

[0017] R a R b R c R d Each of the following is independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, formula Ia, hydroxyl, cyano, -CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, wherein the heteroatom contains at least one of O, S, N, Si, Ge or Se; and R a R b R c R d At least one is selected from formula Ia; n is independently selected from integers from 0 to 5, specifically 0, 1, 2, 3, 4, 5; m is independently selected from integers from 0 to 3, specifically 0, 1, 2, 3; p is independently selected from integers from 0 to 2, specifically 0, 1, 2; q is independently selected from integers from 0 to 5, specifically 0, 1, 2, 3, 4, 5; R a R b R c Or R d When the number of R is greater than 1, two adjacent substituents are independent of each other or connected to each other to form a ring; it should be noted that "two adjacent substituents are independent of each other or connected to each other to form a ring" means that when R a When n is greater than 1, two adjacent R a They are independent or interconnected in a ring, and other R b R c Or R d Similarly, they will not be described one by one. The structural formula of formula Ia in this invention is as follows:

[0018] Z3 is independently selected from either Si or Ge; o is an integer independently selected from 0 to 2, specifically 0, 1, 2; R 10 -R 12 Each is independently selected from deuterium, halogen, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, substituted or unsubstituted C7-C30 aralkyl, and substituted or unsubstituted C3-C30 cycloalkyl. R 13 -R 14Each of the following is independently selected from hydrogen, deuterium, fluorine, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C3-C30 heterocycloalkyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C6-C30 heteroaryl.

[0019] Polycyclic aromatic compounds have the structures shown in Formulas I-1 to I-12: In Formulas I-1 to I-12, all hydrogen atoms are either deuterated or undeuterated.

[0020] In these formulas, I-1 to I-12 describe the specific cases of Z1, Z2, X1, and X2. Formulas I-1 to I-2 represent the simultaneous presence of both Z1 and Z2, both of which have substituents; Formulas I-3 to I-4 represent the simultaneous presence of both Z1 and Z2, both of which are chemical bonds; Formulas I-5 to I-6 represent the absence of Z1, the presence of Z2, and the presence of substituents; Formulas I-7 to I-8 represent the presence of Z1 as a chemical bond, the presence of Z2, and the presence of substituents; Formulas I-9 to I-10 represent the presence of Z1 as a substituent and the absence of Z2; and Formulas I-9 to I-10 also represent the presence of Z1 as a substituent and the presence of Z2 as a chemical bond. Furthermore, in the above formulas I-1 to I-12, X1 and X2 are selected from N or C, and X1 and X2 are not the same.

[0021] In some typical embodiments, R1-R9 are each independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, formula Ia, hydroxyl, cyano, CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C6-C18 heteroaryl, wherein the heteroatom contains at least one of O, S, N, Si, Ge or Se; wherein the substituted or unsubstituted C1-C15 alkyl in R1-R9 includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl or sec-butyl; the substituted or unsubstituted C6-C18 aryl includes phenyl, naphthyl, biphenyl, fluorenyl, terphenyl, phenanthryl or anthracene; and the substituted or unsubstituted C6-C18 heteroaryl includes dibenzothiophene, dibenzofuranyl or indole.

[0022] In some typical implementations, R a R b R c R dEach of the following is independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, formula Ia, hydroxyl, cyano, CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C6-C18 heteroaryl, wherein the heteroatom contains at least one of O, S, N, Si, Ge or Se; wherein R a R b R c R d The substituted or unsubstituted C1-C15 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or sec-butyl; the substituted or unsubstituted C6-C18 aryl groups include phenyl, naphthyl, biphenyl, fluorenyl, terphenyl, phenanthryl, or anthracene; and the substituted or unsubstituted C6-C18 heteroaryl groups include dibenzothiophene, dibenzofuranyl, or indoleyl.

[0023] In some typical implementations, R 10 -R 12 Each of the following is independently selected from deuterium, halogen, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C6-C18 heteroaryl, substituted or unsubstituted C7-C15 aralkyl, and substituted or unsubstituted C3-C15 cycloalkyl; wherein, R 10 -R 12 The substituted or unsubstituted C1-C15 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or sec-butyl; the substituted or unsubstituted C6-C18 aryl groups include phenyl, naphthyl, biphenyl, fluorenyl, terphenyl, phenanthryl, or anthracene; the substituted or unsubstituted C6-C18 heteroaryl groups include dibenzothiophene, dibenzofuranyl, or indolyl; the substituted or unsubstituted C7-C15 aryl groups include benzyl or phenethyl; and the substituted or unsubstituted C3-C15 cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

[0024] In some typical implementations, R 13 -R 14 Each of the following is independently selected from hydrogen, deuterium, fluorine, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C3-C18 heterocycloalkyl, substituted or unsubstituted C6-C18 aryl, and substituted or unsubstituted C6-C18 heteroaryl; R 13 -R 14The substituted or unsubstituted C1-C15 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or sec-butyl; the substituted or unsubstituted C3-C15 cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl; the substituted or unsubstituted C3-C18 heterocyclic alkyl groups include pyrrole, tetrahydrofuranyl, dihydrofuranyl, or dihydrothiophene; the substituted or unsubstituted C6-C18 aryl groups include phenyl, naphthyl, biphenyl, fluorenyl, terphenyl, phenanthryl, or anthracene; and the substituted or unsubstituted C6-C18 heteroaryl groups include dibenzothiophene, dibenzofuranyl, or indole.

[0025] In some typical implementations, all hydrogens in Formula I are either deuterated or undeuterated.

[0026] Furthermore, in all instances of "substituted or unsubstituted" in this invention, "substituted" refers to substitution by a substituent selected from the group consisting of one or more of the following groups linked together: hydrogen, deuterium, halogen, cyano, trimethylsilyl (TMS), trimethylgermanium, trifluoromethyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, 1-methylhexyl, phenyl, naphthyl, anthracene, phenanthrene, thiophene, furanyl, pyrrole, benzothiophene, benzofuranyl, pyridyl, indolyl, cyclopentyl, cyclohexyl, adamantyl.

[0027] Furthermore, it should be noted that the terms "substituted or unsubstituted C1-C30 alkyl", "substituted or unsubstituted C6-C30 aryl", "substituted or unsubstituted C6-C30 heteroaryl", "substituted or unsubstituted C7-C30 aryl", "substituted or unsubstituted C3-C30 cycloalkyl", "substituted or unsubstituted C3-C30 heterocycloalkyl", "substituted or unsubstituted C1-C15 alkyl", "substituted or unsubstituted C6-C18 aryl", and "substituted or unsubstituted" are not interchangeable. The number of carbon atoms in “substituted C6-C18 heteroaryl”, “substituted or unsubstituted C7-C15 aralkyl”, “substituted or unsubstituted C3-C15 cycloalkyl”, “substituted or unsubstituted C3-C15 cycloalkyl”, and “substituted or unsubstituted C3-C18 heterocyclic alkyl” indicates the number of carbon atoms constituting the unsubstituted aryl, unsubstituted alkyl, unsubstituted aralkyl, unsubstituted cycloalkyl, or unsubstituted heterocyclic alkyl, or the total number of carbon atoms constituting the heteroaryl, without considering the number of carbon atoms in the substituents.

[0028] Specifically, the polycyclic aromatic compounds provided by this invention are selected from any one of the following compounds:

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037] .

[0038] The organic electroluminescent compounds of the present invention can be prepared by synthetic methods known to those skilled in the art. For example, the present invention also provides a typical but non-limiting method for preparing the above-mentioned polycyclic aromatic compounds, comprising the following steps:

[0039] The restrictions on the groups in the above formula are the same as those mentioned above, and will not be repeated here.

[0040] Step 1 specifically includes the following steps: Under nitrogen protection, raw material A (1 eq) was dissolved in a mixed solution of diethyl ether and hydrochloric acid. Tetraisopropoxide titanium (1.3 eq) and cyclopentyl magnesium chloride (3 eq) were added to the solution and reacted at -30°C for 12 h to obtain intermediate 1. Raw material B (1.5 eq) was then added directly to the system and the reaction was continued for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, a certain amount of dilute hydrochloric acid and diethyl ether were added to the solution. The solution in the container changed from yellow turbidity to clear transparency. Extraction was performed using DCM and saturated brine. The organic phase was collected, combined, and concentrated. A mixed solution of dichloromethane and petroleum ether was used as the eluent, and intermediate 2 was purified by column chromatography. Step 2 specifically includes the following steps: Under nitrogen protection, intermediate 2 (1 eq) and starting material C (1.5 eq) were dissolved in CH3CN, and 18-crown-6 (2 eq) and KF (3 eq) were added. After reacting at room temperature for 5 h, the temperature was raised to 35 °C and the reaction was continued for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, a certain amount of dilute hydrochloric acid was added, and the solution changed from turbid to clear. Extraction was performed using DCM and saturated brine, the organic phase was collected, the organic phases were combined and concentrated, and intermediate 3 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as eluent. Step 3 specifically includes the following steps: Under nitrogen protection, intermediate 3 (1.05 eq) and raw material D (1 eq) were dissolved in THF. K2CO3 (2 eq), CuI (0.1 eq) and o-phenanthroline (0.2 eq) were added to the solution. After stirring, the mixture was reacted at 100 °C for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, saturated saline and EA were added to the solution, and the mixture was extracted and separated. The collected organic phase was concentrated and purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as the eluent to obtain intermediate 4. Step 4 specifically includes the following steps: Under nitrogen protection, the temperature was lowered to -78℃, and intermediate 4 (1.0 eq) was dissolved in THF. Butyllithium (1.2 eq) was slowly added to the intermediate 4 solution. After reacting for 2 hours, a THF solution of raw material E (0.9 eq) was slowly added to the reaction flask, stirred until homogeneous, and the refrigeration was stopped. The temperature was raised to room temperature, and the reaction continued for 12 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, saturated saline and EA were added, and the mixture was extracted and separated. The collected organic phase was concentrated, and intermediate 5 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as the eluent. Step 5 specifically includes the following steps: Under nitrogen protection, intermediate 5 (1 eq) was dissolved in DCM, and a mixed solution of dilute hydrochloric acid and acetic acid in a volume ratio of 1:1 was added to it. Solid precipitated in the solution. The solid was filtered and dried in an oven at 60°C for 5 h to obtain intermediate 6. Step 6 specifically includes the following steps: Under nitrogen protection, intermediate 6 (1 eq) and starting material F (1.5 eq) were dissolved in CH3CN, and 18-crown-6 (2 eq) and KF (3 eq) were added. After reacting at room temperature for 5 h, the temperature was raised to 35 °C and the reaction was continued for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, a certain amount of dilute hydrochloric acid was added, and the solution changed from turbid to clear. Extraction was performed using DCM and saturated brine, and the organic phase was collected. The organic phases were combined and concentrated. The intermediate 7 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as the eluent. Step 7 specifically includes the following steps: Under nitrogen protection, the temperature was lowered to -78℃, and intermediate 7 (1.0 eq) was dissolved in diethyl ether. Tert-butyllithium (1.2 eq) was slowly added to the intermediate 7 solution. After reacting for 2 hours, the diethyl ether solution of raw material G (0.9 eq) was slowly added to the reaction flask, stirred evenly, the refrigeration was stopped, the temperature was raised to room temperature, and the reaction was continued for 12 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, saturated saline and EA were added, and the mixture was extracted and separated. The collected organic phase was concentrated, and intermediate 8 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as the eluent. Step 8 specifically includes the following steps: Under nitrogen atmosphere, intermediate 8 (1.0 eq) was dissolved in tert-butylbenzene and slowly added to a solution of tert-butyllithium (1.2 eq) in n-pentane. The mixture was heated to 60°C and stirred for 2 h, then cooled to 0°C. Boron tribromide (2.0 eq) was added, and the mixture was heated to room temperature and stirred for 1 h. The mixture was then cooled to 0°C, and N,N-diisopropylethylamine (DIPEA) (2.0 eq) was added. The mixture was allowed to reach room temperature. The mixture was heated to 130°C and stirred for 6 h, then cooled to room temperature. Methanol was added to the mixture to remove residual BBr3. The mixture was separated and extracted with water and dichloromethane. The combined organic layers were condensed under vacuum and column chromatography to obtain compound I.

[0041] In addition, the present invention also provides an organic electroluminescent device, including an anode and a cathode, and an organic thin film layer disposed between the anode and the cathode, wherein the organic thin film layer includes the aforementioned polycyclic aromatic compounds.

[0042] The organic thin film layer includes a light-emitting layer, which comprises a host material, a dopant material, and a sensitizer. The dopant material includes polycyclic aromatic compounds. The mass percentages of the host material, dopant material, and sensitizer are 95-97:2.5-3.5:0.5-1.5.

[0043] Preferably, the organic thin film layer further includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, an electron transport layer, or an electron injection layer.

[0044] Additionally, it should be noted that the values ​​given in the following embodiments are as accurate as possible. However, those skilled in the art will understand that due to unavoidable measurement errors and experimental issues, each number should be understood as an approximation rather than an absolutely accurate value.

[0045] The following are common knowledge references: Organometallic Chemistry (6th Edition), Robert H. Crabtree, published by East China University of Science and Technology Press, Shanghai, September 00, 2017, ISBN: 978-7-5628-5111-0, page 388.

[0046] Organic Chemistry and Optoelectronic Materials Experiment Tutorial, Chen Runfeng, Publisher: Southeast University Press, Publication Date: 2019-11-00, ISBN: 9787564184230, Page 174.

[0047] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0048] Example 1 This embodiment provides a structure with the following formula: The polycyclic aromatic compound 187 is prepared by the following method:

[0049] Step 1 specifically includes the following steps: Under nitrogen protection, raw material A-187 (1 eq) was dissolved in a mixed solution of diethyl ether and hydrochloric acid. Tetraisopropoxide titanium (1.3 eq) and cyclopentyl magnesium chloride (3 eq) were added to the solution, and the reaction was carried out at -30°C for 12 h to obtain intermediate 1. Raw material B-187 (1.5 eq) was then added directly to the system, and the reaction was continued for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, a certain amount of dilute hydrochloric acid and diethyl ether were added to the solution. The solution in the container changed from yellow turbidity to clear transparency. Extraction was carried out using DCM and saturated brine. The organic phase was collected, combined, and concentrated. The solution was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as the eluent to obtain intermediate 2 (yield 25.9%). Step 2 specifically includes the following steps: Under nitrogen protection, intermediate 2 (1 eq) and starting material C-187 (1.5 eq) were dissolved in CH3CN, and 18-crown-6 (2 eq) and KF (3 eq) were added. After reacting at room temperature for 5 h, the temperature was raised to 35 °C and the reaction was continued for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, a certain amount of dilute hydrochloric acid was added, and the solution changed from turbid to clear. Extraction was performed using DCM and saturated brine, and the organic phase was collected. The organic phases were combined and concentrated, and intermediate 3 (yield 54.7%) was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as eluent. Step 3 specifically includes the following steps: Under nitrogen protection, intermediate 3 (1.05 eq) and starting material D-187 (1 eq) were dissolved in THF. K2CO3 (2 eq), CuI (0.1 eq), and o-phenanthroline (0.2 eq) were added to the solution. After stirring, the mixture was reacted at 100 °C for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, saturated brine and EA were added to the solution, and the mixture was extracted and separated. The collected organic phase was concentrated and purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as eluent to obtain intermediate 4 (yield 82.3%). Step 4 specifically includes the following steps: Under nitrogen protection, the temperature was lowered to -78℃, and intermediate 4 (1.0 eq) was dissolved in THF. Butyllithium (1.2 eq) was slowly added to the intermediate 4 solution. After reacting for 2 hours, a THF solution of raw material E-187 (0.9 eq) was slowly added to the reaction flask, stirred until homogeneous, and the refrigeration was stopped. The temperature was raised to room temperature, and the reaction continued for 12 hours. The reaction was detected by thin-layer chromatography. After the reaction was complete, saturated saline and EA were added, and the mixture was extracted and separated. The collected organic phase was concentrated, and intermediate 5 (yield 84.1%) was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as the eluent. Step 5 specifically includes the following steps: Under nitrogen protection, intermediate 5 (1 eq) was dissolved in DCM, and a mixed solution of dilute hydrochloric acid and acetic acid in a volume ratio of 1:1 was added. Solid precipitated in the solution. The solid was filtered and dried in an oven at 60°C for 5 h to obtain intermediate 6 (yield 91.4%). Step 6 specifically includes the following steps: Under nitrogen protection, intermediate 6 (1 eq) and starting material F-187 (1.5 eq) were dissolved in CH3CN, and 18-crown-6 (2 eq) and KF (3 eq) were added. After reacting at room temperature for 5 h, the temperature was raised to 35 °C and the reaction was continued for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, a certain amount of dilute hydrochloric acid was added, and the solution changed from turbid to clear. Extraction was performed using DCM and saturated brine, and the organic phase was collected. The organic phases were combined and concentrated, and intermediate 7 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether as eluent (yield 82.6%). Step 7 specifically includes the following steps: Under nitrogen atmosphere, intermediate 7 (1.0 eq) was dissolved in tert-butylbenzene and slowly added to a solution of tert-butyllithium (1.2 eq) in n-pentane. The mixture was heated to 60°C and stirred for 2 h, then cooled to 0°C. Boron tribromide (2.0 eq) was added, and the mixture was heated to room temperature and stirred for 1 h. The mixture was then cooled to 0°C, and N,N-diisopropylethylamine (DIPEA) (2.0 eq) was added. The mixture was allowed to reach room temperature. The mixture was heated to 130°C and stirred for 6 h, then cooled to room temperature. Methanol was added to the mixture to remove residual BBr3. The mixture was separated and extracted with water and dichloromethane. The combined organic layers were condensed under vacuum and column chromatography to give compound 187. (Yield: 29.5%, MS (ESI, m / Z): [M+H)) + =846.49).

[0050] The obtained compound 187 was analyzed, and the results are as follows: The proton NMR spectrum of compound 187 is shown below. Figure 1 As shown.

[0051] HPLC purity: >99.92%.

[0052] Elemental analysis: The test values ​​are: C, 86.22; H, 5.72; B, 1.37; N, 3.39; Si, 3.41.

[0053] The synthesis methods for other compounds are the same as those in the above embodiments, and will not be described in detail here. The present invention also provides an organic electroluminescent device, which is made of the organic light-emitting material, more specifically, an organic light-emitting material of a compound with chemical formula I.

[0054] Device Example 1: Fabrication of Green Organic Light Emitting Device a. ITO Anode: An ITO (Indium Tin Oxide)-Ag-ITO (Indium Tin Oxide) glass substrate with a coating thickness of 1500 Å was cleaned three times with distilled water and ultrasonically washed for 40 min. This was followed by repeated cleaning with distilled water three times and ultrasonic washing for 20 min. After cleaning, the substrate was ultrasonically washed sequentially with methanol, acetone, and isopropanol (5 min each time), dried, and then transferred to a plasma cleaner for 5 min. Finally, it was sent to a vapor deposition machine, where other functional layers were sequentially deposited onto the substrate using it as the anode. The organic layers specified below were deposited under a vacuum of approximately 10... -8 In the case of T, the ITO anode is sequentially vaporized at a rate of 0.2-2 Å / s via thermal vacuum evaporation.

[0055] b. HIL (Hole Injection Layer): Hole injection layer materials HT-1 and HI-1 are vacuum-deposited at a deposition rate of 1 Å / s as hole injection layer, wherein the deposition rate ratio of HT-1 and HI-1 is 98:2 and the thickness is 10 nm.

[0056] c. HTL (Hole Transport Layer): HT-1 of 130 nm was vacuum-deposited on the hole injection layer at a deposition rate of 1.5 Å / s as the hole transport layer.

[0057] d. EBL (Electron Blocking Layer): An electron blocking layer (EBM) with a thickness of 5 nm is vacuum-deposited on the hole transport layer at a deposition rate of 0.5 Å / s.

[0058] e. EML (Emitting Layer): A dual host material (Host-1 and Host-2) with a thickness of 200 nm is vacuum-deposited on the electron blocking layer at a deposition rate of 1 Å / s. Compound 187 is used as a dopant and GD-1 (Irppy) is used as a sensitizer. The mass ratio of the host material (Host-1 and Host-2), the dopant compound 187 and the sensitizer GD-1 (Irppy) is 96:3:1, and the deposition rate ratio of Host-1 to Host-2 in the host material is 4:6. The chemical formulas of Host-1, Host-2 and GD-1 are shown below.

[0059] f. HBL (hole blocking layer): A hole blocking layer HB-1 with a thickness of 5 nm is vacuum-deposited on the light-emitting layer at a deposition rate of 0.5 Å / s.

[0060] g. ETL (Electron Transport Layer): ET-1 and 8-hydroxyquinoline-lithium (Liq) with a thickness of 30 nm are vacuum-deposited on the hole blocking layer at a deposition rate of 1 Å / s, wherein the deposition rate ratio of ET-1 to Liq is 50:50.

[0061] h. EIL (Electron Injection Layer): An 8-hydroxyquinoline-lithium (Liq) film of 1.0 nm is vacuum-deposited on the electron transport layer at a deposition rate of 0.5 Å / s to form the electron injection layer.

[0062] i. Cathode: Magnesium and silver are deposited at a deposition rate of 1 Å / s for 13 nm, with a deposition rate ratio of 1:9, to obtain the OLED device.

[0063] j. Light Extraction Layer: A 65nm thick CPL-1 layer was vacuum-deposited on the cathode at a deposition rate of 1Å / s as the light extraction layer. The deposited substrate was then encapsulated. First, a UV adhesive was applied to the cleaned cover plate using a coating equipment. Then, the coated cover plate was moved to the lamination section, and the deposited substrate was placed on top of the cover plate. Finally, the substrate and cover plate were laminated using a bonding equipment, simultaneously curing the UV adhesive under UV light.

[0064] The structures of HT-1, HI-1, EBM, Host-1, Host-2, GD-1, HB-1, and ET-1 used in Embodiment 1 of the above devices are shown below:

[0065]

[0066] .

[0067] Device Examples 2-58 follow the same method as described above, but replace compound 187 used in Device Example 1 with compounds 1, 6, 9, 17, 19, 26, 31, 39, 123, 136, 140, 152, 156, 160, 162, 166, 172, 174, 179, 181, 182, 183, 184, 185, 187, 192, and 195, respectively. Organic electroluminescent devices were prepared by using the following doping materials: 199, 228, 207, 253, 263, 272, 280, 291, 299, 309, 319, 323, 334, 343, 355, 371, 413, 433, 434, 435, 436, 437, 438, 439, 440, 441, 442, 443, 444, and 445.

[0068] Comparative Example 1: This comparative example provides an organic electroluminescent device. The only difference between this organic electroluminescent device and Device Example 1 is that the organic electroluminescent device is prepared by evaporation using existing comparative compounds a, b, c, d, e, f, g, h, i, j, k, and l instead of the doping materials in Device Example 1. Comparative Examples 1 to 12 are prepared accordingly. The chemical structural formulas of the comparative compounds a, b, c, d, e, f, g, h, i, j, k, and l are as follows:

[0069] The driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained in Examples 1-58 and Comparative Examples 1-12 were characterized at a brightness of 15000 nits. The test results are shown in Table 1 below.

[0070] Table 1. Statistical table of performance parameter test results for different organic electroluminescent devices

[0071] As shown in Table 1 above, changing the substituents and their positions will alter the device's performance, thereby improving its luminous efficiency and lifespan to varying degrees.

[0072] As can be seen from Table 1, comparing Comparative Examples 1-12 and Examples 1-58, the light-emitting devices prepared using the compounds of the present invention show varying degrees of improvement in driving voltage, luminous efficiency, and lifetime performance. Specifically, Comparative Examples 1-12 have a driving voltage of 3.74~3.85 V, a luminous efficiency of 160.0~163.3 cd / A, and a lifetime of 674~708 h; while Examples 1-58 have a driving voltage of 3.45~3.64 V, a luminous efficiency of 176.8~184.3 cd / A, and a lifetime of 786~849 h.

[0073] As is well known, various literatures have fully demonstrated that oscillation strength and dS1T1 gap are key parameters of TADF (thermally activated delayed fluorescence) and other luminescent materials.

[0074] A larger oscillator strength means stronger absorption. Oscillation strength is a dimensionless parameter, and its magnitude directly reflects the transition probability (usually...). f =0 indicates that the transition is prohibited. fA value >0.1 indicates a strong allowed transition. Therefore, a large oscillator intensity in the S1 state indicates that the TADF emitter can be effectively excited, thus promoting efficient radiative decay. This means that if the oscillator intensity of the S1 state in the TADF emitter is small, excitons will be difficult to effectively emit from the S1 state through strong light radiation.

[0075] Furthermore, for a TADF emitter to achieve its theoretical efficiency of 100%, it must undergo a RISC process. To achieve an efficient RISC process, the band gap between S1 and T1 (i.e., dS1T1 gap, dS1T1 gap = S1 - T1) must be sufficiently small. If the band gap between S1 and T1 (dS1T1 gap) is too large, it will lead to a decrease in the RISC rate, triplet exciton accumulation, and an increase in optical loss due to nonradiative decay.

[0076] In this invention, for a specific structure represented by a representative structural formula, calculations are performed using the conventional Gaussian16 program, employing density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The calculation parameters are set as follows: the functional is B3LYP, and the basis set is a mixed basis set scheme (wherein, the metal atoms use the LANL2DZ pseudopotential basis set, and the non-metal atoms use the 6-31G(d,p) basis set). Through the above calculations, the physical properties (including but not limited to emission wavelength, fluorescence quantum yield, excited state lifetime, and HOMO / LUMO energy levels) of the specific structure as a TADF luminescent material can be predicted and verified, and compared with the same physical properties of compounds e and j as TADF luminescent materials.

[0077] The specific test structure is as follows:

[0078]

[0079] The gap between T1, S1, dS1T1 and the above compounds f The values ​​were tested, and the test results are shown in Table 2. Table 2. Statistical table of physical property test results for different examples

[0080] By comparing the specific structures in the table above, it can be seen that the compound provided in this application, compared to compounds e and j, possesses oscillator strength. f It has the characteristics of being larger and having a smaller S1-T1 band gap (dS1T1 gap).

[0081] Compared with organic electroluminescent devices prepared using comparative compounds a~l as doping materials, the organic electroluminescent devices prepared using the compounds provided in this invention as doping materials in the light-emitting layer have improved driving voltage, increased luminous efficiency, and significantly improved device lifetime.

[0082] In summary, the polycyclic aromatic compounds provided by this invention have a BN coordination structure and a carbazole structure as their parent core, with A being a substituted or unsubstituted benzene ring. In this case, the parent core structure also possesses a large conjugated system of fused polycyclic aromatic rings, forming a rigid framework through B and N atoms. The BN coordination structure can regulate charge, effectively balancing carrier (electron and hole) concentrations, reducing carrier recombination, and improving device efficiency. Simultaneously, the stable BN coordination bonds reduce energy loss during carrier transport, extending the effective carrier transport time and indirectly extending device lifetime. The large conjugated system of fused polycyclic aromatic rings endows the material with high carrier mobility, making carrier transport more efficient and reducing the probability of recombination during transport, further improving device efficiency. The rigid framework enhances the chemical and thermal stability of the material, preventing performance degradation due to material decomposition and structural collapse during device operation, thus extending device lifetime. The carbazole structure itself possesses high conjugation properties, which on the one hand improves intermolecular stacking and optimizes carrier transport channels; on the other hand, it can regulate the molecular arrangement, promote horizontal molecular alignment, enhance the light extraction efficiency of the emissive layer, and thus improve the device's luminous efficiency. In this invention, through R... a R b R c R d At least one substituent selected from Formula Ia is present, wherein the steric hindrance of Si or Ge can suppress excessive molecular aggregation, avoiding carrier transport obstruction or exciton quenching caused by aggregation, while improving the solubility and processability of the material, further ensuring the stability and efficiency of device performance. Furthermore, when fluorine-containing substituents are used in this invention, the introduction of fluorine can also lower the HOMO and LUMO energy levels of organic materials, enhance charge carrier mobility, and strengthen intermolecular electrostatic forces, resulting in better material stability and significantly improved device lifetime. Devices fabricated using the doped materials of this invention exhibit significantly improved lifetime and efficiency.

[0083] It should be noted that the present invention is illustrated through the above embodiments to demonstrate the polycyclic aromatic compounds of the present invention and the organic light-emitting devices using such compounds. However, the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Equivalent substitutions of the raw materials selected in the present invention, the addition of auxiliary components, and the selection of specific methods all fall within the protection scope and disclosure scope of the present invention.

[0084] Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention shall be included within the scope of protection of this invention.

Claims

1. A polycyclic aromatic compound, characterized in that, It has the structure shown in Equation I: ； Wherein, ring A is a substituted or unsubstituted benzene ring; At least one of Z1 and Z2 is present, and Z1 and Z2 are independently selected from chemical bonds, BR1, CR2R3, NR4, PR5, SiR6R7, GeR8R9, S, O, CO, SO2, respectively; R1-R9 are independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, hydroxyl, cyano, -CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, and their heteroatoms contain at least one of O, S, N, Si, Ge or Se; when Z1 or Z2 has two substituents, the two adjacent substituents are independent of each other or connected to each other to form a ring; X1 and X2 are independently selected from N or C, and X1 and X2 are not the same; R a R b R c R d Each of the following is independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, formula Ia, hydroxyl, cyano, -CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, wherein the heteroatom contains at least one of O, S, N, Si, Ge or Se; and R a R b R c R d At least one of them is selected from formula Ia; n is independently selected from integers from 0 to 5; m is independently selected from integers from 0 to 3; p is independently selected from integers from 0 to 2; q is independently selected from integers from 0 to 5; R a R b R c Or R d When the number of substituents is greater than 1, two adjacent substituents are independent of each other or connected to each other to form a ring; Z3 is independently selected from either Si or Ge; o is an integer independently selected from 0 to 2; R 10 -R 12 Each is independently selected from deuterium, halogen, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, substituted or unsubstituted C7-C30 aralkyl, and substituted or unsubstituted C3-C30 cycloalkyl. R 13 -R 14 Each of the following is independently selected from hydrogen, deuterium, fluorine, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C3-C30 heterocycloalkyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C6-C30 heteroaryl.

2. The polycyclic aromatic compound according to claim 1, characterized in that, The polycyclic aromatic compounds have the structures shown in Formulas I-1 to I-12: In Formulas I-1 to I-12, all hydrogen atoms are either deuterated or undeuterated.

3. The polycyclic aromatic compound according to claim 1, characterized in that, R1-R9 are each independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, formula Ia, hydroxyl, cyano, CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C6-C18 heteroaryl, and their heteroatoms contain at least one of O, S, N, Si, Ge or Se; And / or, R a R b R c R d The atoms are independently selected from hydrogen, deuterium, -F, -Cl, -Br, -I, -SF5, formula Ia, hydroxyl, cyano, CF3, nitro, amino, trimethylsilyl, trimethylgermanyl, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C6-C18 heteroaryl, and the heteroatom contains at least one of O, S, N, Si, Ge or Se; And / or, R 10 -R 12 Each of the following is independently selected from deuterium, halogen, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C6-C18 heteroaryl, substituted or unsubstituted C7-C15 aralkyl, and substituted or unsubstituted C3-C15 cycloalkyl. And / or, R 13 -R 14 Each of the following is independently selected from hydrogen, deuterium, fluorine, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C3-C18 heterocycloalkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C6-C18 heteroaryl. And / or, all hydrogens in Formula I are independently either deuterated or undeuterated.

4. The polycyclic aromatic compound according to claim 1, characterized in that, R1-R9 and R a R b R c R d The substituted or unsubstituted C1-C15 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or sec-butyl; the substituted or unsubstituted C6-C18 aryl groups include phenyl, naphthyl, biphenyl, fluorenyl, terphenyl, phenanthryl, or anthracene; the substituted or unsubstituted C6-C18 heteroaryl groups include dibenzothiophene, dibenzofuranyl, or indoleyl. And / or, R 10 -R 12 The substituted or unsubstituted C1-C15 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or sec-butyl; the substituted or unsubstituted C6-C18 aryl groups include phenyl, naphthyl, biphenyl, fluorenyl, terphenyl, phenanthryl, or anthracene; the substituted or unsubstituted C6-C18 heteroaryl groups include dibenzothiophene, dibenzofuranyl, or indolyl; the substituted or unsubstituted C7-C15 aryl groups include benzyl or phenethyl; and the substituted or unsubstituted C3-C15 cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl. And / or, R 13 -R 14 The substituted or unsubstituted C1-C15 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or sec-butyl; the substituted or unsubstituted C3-C15 cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl; the substituted or unsubstituted C3-C18 heterocyclic alkyl groups include pyrrole, tetrahydrofuranyl, dihydrofuranyl, or dihydrothiophene; the substituted or unsubstituted C6-C18 aryl groups include phenyl, naphthyl, biphenyl, fluorenyl, terphenyl, phenanthryl, or anthracene; and the substituted or unsubstituted C6-C18 heteroaryl groups include dibenzothiophene, dibenzofuranyl, or indole.

5. The polycyclic aromatic compound according to claim 1, characterized in that, The substitution in the context of substitution or non-substitution refers to substitution by a substituent selected from one or more of the following groups linked together: hydrogen, deuterium, halogen, cyano, trimethylsilyl (TMS), trimethylgermanium, trifluoromethyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, 1-methylhexyl, phenyl, naphthyl, anthracene, phenanthrene, thiophene, furanyl, pyrrole, benzothiophene, benzofuranyl, pyridyl, indolyl, cyclopentyl, cyclohexyl, adamantyl.

6. The polycyclic aromatic compound according to claim 1, characterized in that, The polycyclic aromatic compounds are selected from any one of the following compounds: 。 7. An organic electroluminescent device, characterized in that, It includes an anode and a cathode, and an organic thin film layer disposed between the anode and the cathode, the organic thin film layer comprising a polycyclic aromatic compound as described in any one of claims 1-6.

8. The organic electroluminescent device according to claim 7, characterized in that, The organic thin film layer includes a light-emitting layer, which comprises a host material, a dopant material, and a sensitizer. The dopant material includes the polycyclic aromatic compound.

9. The organic electroluminescent device according to claim 7, characterized in that, The mass percentages of the main material, the dopant material, and the sensitizer are 95-97:2.5-3.5:0.5-1.

5.

10. The organic electroluminescent device according to claim 7, characterized in that, The organic thin film layer further includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, an electron transport layer, or an electron injection layer.

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