Thermal activation delayed fluorescence emission material and application thereof

Abstract

The invention relates to a thermal activation delayed fluorescence emission material and application thereof. The thermal activation delayed fluorescence emission material has a structure as shown in a formula I or a formula II. The thermally activated delayed fluorescence generation material is narrow in half-peak width of a light-emitting spectrum and high in exciton utilization efficiency, can provide excellent light-emitting performance in a device structure, and has a wide application prospect. Formula I and formula II

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescent materials technology, specifically relating to a thermally activated delayed fluorescence emission material and its applications. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are the most promising new information display and lighting technologies after liquid crystal displays (LCDs). Organic light-emitting materials are the core materials of OLEDs, determining the device's emission color, exciton utilization efficiency, and device stability. Research on organic light-emitting materials has progressed over thirty years, developing several generations of materials, including fluorescent materials, phosphorescent materials, thermally activated delayed fluorescence (TADF) materials, and thermally exciton-emitting materials. Among these, delayed fluorescence materials, due to their pure organic molecules and high exciton utilization efficiency, have attracted significant industry attention and are a class of light-emitting materials with extremely promising industrial prospects.

[0003] Among them, resonant thermally activated delayed fluorescence (RTF) materials have gained increasing favor in recent years due to their narrow emission half-width. Currently, only boron-nitrogen and nitrogen-carbonyl systems can achieve RTF. Although these materials achieve excellent luminescence efficiency, they are advantageous in emitting blue light, and the device stability still does not meet industry requirements. Furthermore, the number of such luminescent material systems is limited, making further optimization to produce red light with high color purity and high efficiency difficult.

[0004] Recently, scholars have revealed that the organic molecular framework of indolocarbazole (ICz) has rigidity and multiple resonance characteristics, enabling narrow-spectrum deep blue light emission. However, the single-triple band gap of this type of framework is large (0.49 eV), and it is still impossible to achieve multiple resonance delayed fluorescence emission with a narrow emission half-width. Therefore, the indolocarbazole framework is mainly used to construct host materials, fluorescent materials, and delayed fluorescence emission materials with DA characteristics. However, such materials have a relatively wide emission half-width and poor color purity.

[0005] Chinese patent CN 111848620 A discloses a series of pyridine or pyrazine-indolocarbazole (single nitrogen or two nitrogen atom hybridized ICz skeleton) organic semiconductor compounds. Their construction principle involves using pyridine-indolocarbazole or pyrazine-indolocarbazole as the LUMO in the molecule, along with a charge-donating group as the HOMO, to construct delayed fluorescence emission materials with DA or DAD characteristics. Although nitrogen-hybridized indolocarbazole achieves delayed fluorescence emission materials, the construction of these luminescent materials is not based on the principle of multiple resonance luminescence design, but rather on a molecular design based on donor and acceptor structures. This results in a broad emission peak and poor color purity.

[0006] Clearly, in order to meet the ever-increasing performance requirements of industrial production, it is urgent to explore and obtain multi-resonance delayed fluorescence emission materials with high color purity, high luminous efficiency, and low cost, as well as organic OLED display and lighting products based on them, and continuous exploration is needed. Summary of the Invention

[0007] This invention addresses the scarcity of high-color-purity TADF luminescent materials and the poor stability of TADF materials used in OLED devices by providing a thermally activated delayed fluorescence emission material with multiple resonances and its applications.

[0008] A first aspect of the present invention provides a thermally activated delayed fluorescence emission material having the structure shown in Formula I or Formula II: Formula I Formula II in, Ring A is selected from any of the following structures: , , , , , ; Ring B is selected from any of the following structures: , ; Indicates the group linkage site; X, X1, and X2 may be the same or different, and each is independently selected from O, S, Se, CR7R8, S=O, SO2, and C=O; R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different, and each is independently selected from the structure shown in Formula 1 or Formula 2, or from the group consisting of: hydrogen, deuterium, halogen, cyano, nitro, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 alkylthio, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C2- C30 heterocyclic alkyl, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C1-C60 heteroaryl, substituted or unsubstituted C6-C60 arylamino, substituted or unsubstituted C3-C60 heteroarylamino, substituted or unsubstituted C6-C60 aryloxy, substituted or unsubstituted C3-C30 heteroaryloxy, substituted or unsubstituted C6-C30 arylthio, substituted or unsubstituted C3-C60 heteroarylthio; Formula 1 Formula 2 Indicates the group linkage site; The substituents described in R1, R2, R3, R4, R5, R6, R7, and R8 are each independently selected from deuterium, halogen, cyano, nitro, C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkylthio, C1-C20 alkylsilyl, C3-C20 cycloalkyl, C2-C20 heterocycloalkyl, C6-C30 aryl, C3-C30 heteroaryl, C6-C30 arylamino, C1-C30 heteroarylamino, C6-C30 aryloxy, C3-C30 heteroaryloxy, C6-C30 arylthio, and C3-C30 heteroarylthio. Optionally, R1, R2, R3, R4, R5, R6, R7, and R8 are not connected to their adjacent groups or are linked by chemical bonds to form a ring.

[0009] A second aspect of the present invention provides an organic electroluminescent device comprising an ITO conductive glass, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, and a cathode, wherein the light-emitting layer comprises the thermally activated delayed fluorescence emission material described in the first aspect.

[0010] The present invention has the following beneficial effects: The fluorescent emitting material of this invention has a central core composed of multiple nitrogen-doped indole [3,2,1-jk]carbazole atoms, forming a multi-CN alternating fused ring framework. The central core can be modified with various electron-donating, electron-deficient substituents, and aromatic rings to control the material's emission color, full width at half maximum (FWHM), luminescence efficiency, and excited-state kinetic parameters. The fluorescent emitting material provided by this invention can serve as an organic electroluminescent material with a narrow FWHM and thermally activated delayed fluorescence characteristics. The fluorescent emitting material of this invention exhibits a narrow FWHM and high exciton utilization efficiency, providing excellent luminescence performance in device structures and showing broad application prospects. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the organic electroluminescent device of the present invention; Figure 2 The following are transient fluorescence lifetime and delayed fluorescence lifetime diagrams for Examples 4-7 of the present invention, wherein (a) is the transient fluorescence lifetime and delayed fluorescence lifetime diagram for Example 4; (b) is the transient fluorescence lifetime and delayed fluorescence lifetime diagram for Example 5; (c) is the transient fluorescence lifetime and delayed fluorescence lifetime diagram for Example 6; and (d) is the transient fluorescence lifetime and delayed fluorescence lifetime diagram for Example 7. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0013] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0014] In this invention, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0015] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0016] This invention provides a thermally activated delayed fluorescence emission material having the structure shown in Formula I or Formula II: Formula I Formula II in, Ring A is selected from any of the following structures: , , , , , ; Ring B is selected from any of the following structures: , ; Indicates the group linkage site; X, X1, and X2 may be the same or different, and each is independently selected from O, S, Se, CR7R8, S=O, SO2, and C=O; R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different, and each is independently selected from the structure shown in Formula 1 or Formula 2, or from the group consisting of: hydrogen, deuterium, halogen, cyano, nitro, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 alkylthio, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C2- C30 heterocyclic alkyl, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C1-C60 heteroaryl, substituted or unsubstituted C6-C60 arylamino, substituted or unsubstituted C3-C60 heteroarylamino, substituted or unsubstituted C6-C60 aryloxy, substituted or unsubstituted C3-C30 heteroaryloxy, substituted or unsubstituted C6-C30 arylthio, substituted or unsubstituted C3-C60 heteroarylthio; Formula 1 Formula 2 Indicates the group linkage site; The substituents described in R1, R2, R3, R4, R5, R6, R7, and R8 are each independently selected from deuterium, halogen, cyano, nitro, C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkylthio, C1-C20 alkylsilyl, C3-C20 cycloalkyl, C2-C20 heterocycloalkyl, C6-C30 aryl, C3-C30 heteroaryl, C6-C30 arylamino, C1-C30 heteroarylamino, C6-C30 aryloxy, C3-C30 heteroaryloxy, C6-C30 arylthio, and C3-C30 heteroarylthio. Optionally, R1, R2, R3, R4, R5, R6, R7, and R8 are not connected to their adjacent groups or are linked by chemical bonds to form a ring.

[0017] The fluorescent emitting material of this invention has a central core composed of multiple nitrogen-doped indole [3,2,1-jk]carbazole atoms, forming a multi-CN alternating fused ring framework. The central core can be modified with various electron-donating, electron-deficient substituents, and aromatic rings to control the material's emission color, full width at half maximum (FWHM), luminescence efficiency, and excited-state kinetic parameters. The fluorescent emitting material provided by this invention can serve as an organic electroluminescent material with a narrow FWHM and thermally activated delayed fluorescence characteristics. The fluorescent emitting material of this invention exhibits a narrow FWHM and high exciton utilization efficiency, providing excellent luminescence performance in device structures and showing broad application prospects.

[0018] Specifically, the thermally activated delayed fluorescence emission material of this invention selects multi-nitrogen atom-doped indole[3,2,1-jk]carbazole as the central framework, utilizing the strong electron-withdrawing inductive effect of N atoms in the aromatic ring and the electron-donating effect of N atoms in the non-aromatic ring to regulate the separation of the frontier orbital electron cloud at different atoms of the chemical bond. The fluorescence emission material of this application introduces meta-nitrogen atom doping, which, compared to single-N atom doping (such as...),... or ) and para-N atom doping (e.g. In this application, meta-doped N atoms form alternating CN chemical bonds. In the aromatic ring, the N atoms adopt sp2 bonding. 2 Hybridization means that a pair of nonbonded electrons does not participate in π conjugation and can serve as an electron-rich center. The N atom is more electronegative than the C atom, and the CN bond will form an electron-deficient-electron-rich center. In molecules with multiple alternating CN bonds, the HOMO and LUMO orbital electrons are distributed on the N and C atoms, respectively, forming short-range complete separation of orbital electrons on chemical bonds, which can achieve near degeneracy of singlet and triplet energy levels.

[0019] Furthermore, the electron distribution of HOMO and LUMO orbitals can be modulated by the number and position of nitrogen atoms introduced. The n orbitals of N atoms can participate in energy level composition, resulting in a variety of excited states. The luminescence efficiency of the material can reach 58%~98%. The introduction of electron-donating and electron-deficient substituents into the benzene ring without nitrogen atoms can further modulate the luminescence, thereby achieving a small singlet-triplet band gap. The rigid structure of the indole[3,2,1-jk]carbazole framework ensures that the material can provide a narrow full width at half maximum (FWHM) emission spectrum.

[0020] Meanwhile, the rigid structure of the indole[3,2,1-jk]carbazole framework ensures that the material can provide a narrow half-width (WHM) emission spectrum, with the resulting material exhibiting a WHM of 25–50 nm. This enables stable, high-efficiency, narrow WHM blue, green, and red light emission.

[0021] In summary, the molecular design of the material of this invention is theoretically superior. It effectively controls the separation of frontier orbital electrons by utilizing the distinct electronic effects exhibited by N atoms in different environments. Experiments have shown that it has excellent luminescence performance and can be considered one of the best choices for organic light-emitting layer materials in organic electroluminescent devices.

[0022] In some embodiments, the thermally activated delayed fluorescence emission material has any of the following structures: Formula I-1 Formula I-2 Formula I-3 Formula I-4 Formula I-5 Formula I-6 Formula I-7 Formula I-8 Formula I-9 Formula II-1 The definitions of X, X1, X2, R1, R2, R3, R4, R5, and R6 are the same as those in Equation I and Equation II.

[0023] In some embodiments, the thermally activated delayed fluorescence emission material has any of the following structures: Formula I-1-1 Formula I-2-1 Formula I-3-1 Formula I-4-1 Formula I-5-1 Formula I-6-1 Formula I-7-1 Formula I-8-1 Formula I-9-1 The definitions of X, X1, X2, R1, R2, R3, R4, R5, and R6 are the same as those in Formulas I and II. Preferably, X, X1, and X2 are selected from O and S. Selecting X, X1, and X2 from O and S both have good effects, with S having a better effect due to its heavy atom effect.

[0024] In some embodiments, R1, R2, R3, R4, R5, and R6 may be the same or different, and each is independently selected from the structure shown in Formula 1 or Formula 2 or from the group consisting of: hydrogen, deuterium, F, Cl, Br, I, cyano, nitro, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 alkylthio, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C20 heterocycloalkyl, substituted or unsubstituted phenyl, substituted or unsubstituted diphenyl, substituted or unsubstituted triphenyl, substituted or unsubstituted tetraphenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted phenanthyl, substituted or unsubstituted triphenylene, substituted or unsubstituted anthracene, substituted or unsubstituted Benzoanthracene, substituted or unsubstituted pyrene, substituted or unsubstituted thionyl, substituted or unsubstituted perylyl, substituted or unsubstituted fluoranthracene, substituted or unsubstituted carbazolyl, substituted or unsubstituted fluorenyl, substituted or unsubstituted indolyl, substituted or unsubstituted quinolinyl, substituted or unsubstituted benzofuranyl, substituted or unsubstituted benzothiophene, substituted or unsubstituted thiophene, substituted or unsubstituted pyrroleyl, substituted or unsubstituted furanyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophene, substituted or unsubstituted benzimidazolyl, substituted or unsubstituted benzoxazolyl, substituted or unsubstituted diphenylamino, substituted or unsubstituted triphenylamino, substituted or unsubstituted phenazinyl, substituted or unsubstituted thiophenazinyl, substituted or unsubstituted acridineyl; Formula 1 Formula 2 Indicates the group linkage site; The substituents described in R1, R2, R3, R4, R5, and R6 are each independently selected from any one or a combination of at least two of the following: deuterium, F, Cl, Br, I, cyano, nitro, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylthio, C6-C20 aryl, C1-C20 heteroaryl, C6-C20 arylamino, C1-C20 heteroarylamino, C6-C20 aryloxy, C6-C20 heteroaryloxy, C6-C20 arylthio, and C3-C20 heteroarylthio. Optionally, R1, R2, R3, R4, R5, and R6 are not connected to their adjacent groups or are linked by chemical bonds to form a ring.

[0025] Furthermore, peripheral substituents can regulate the solubility of luminescent molecules in organic solvents and the distance between luminescent molecules during solid-state stacking, suppressing luminescence quenching caused by aggregation. When the substituents are aromatic, long-range charge-transfer excited states can be induced, allowing for fine control of the energy level distribution of the excited states, reducing the singlet-triplet band gap, and regulating the dynamics of the excited states. Moreover, when the substituents are aromatic, narrow half-width blue light emission and high-efficiency luminescent materials can be obtained.

[0026] In some implementations, R1 and R2 are the same.

[0027] In some implementations, R4 and R5 are the same.

[0028] In some embodiments, R7 and R8 are each independently selected from C1-C10 alkyl groups, preferably C1-C5 straight-chain alkyl groups, such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, etc.

[0029] In some embodiments, R1, R2, R3, R4, R5, and R6 are each independently selected from the group consisting of hydrogen, deuterium, F, Br, CF3, CN, or the following groups: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , .

[0030] In some embodiments, R1 is selected from the group consisting of hydrogen, deuterium, F, Br, CF3, CN, or the following groups: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , .

[0031] In some embodiments, R2 is selected from the group consisting of hydrogen, deuterium, F, Br, CF3, CN, or the following groups: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , .

[0032] In some embodiments, R3 is selected from the group consisting of hydrogen, deuterium, F, CF3, CN, or the following groups: , , , , , , , , , .

[0033] In some embodiments, the thermally activated delayed fluorescence emission material is selected from any of the following structures: .

[0034] A second aspect of the present invention provides an organic electroluminescent device comprising an ITO conductive glass, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, and a cathode, wherein the light-emitting layer comprises the thermally activated delayed fluorescence emission material described in the first aspect.

[0035] In some embodiments, the organic electroluminescent device emits blue, green, and red light.

[0036] In some embodiments, the thermally activated delayed fluorescence emission material described in the first aspect of the present invention can be applied to organic light-emitting diodes (OLEDs).

[0037] In some embodiments, the present invention discloses an organic light-emitting diode (OLED), which includes the following components: Substrate material, anode, hole injection layer, hole transport layer, electron blocking layer, organic light-emitting layer, electron transport layer, electron injection layer, cathode.

[0038] In some embodiments, the organic light-emitting layer includes a host material and a dopant material, wherein the dopant material includes the thermally activated delayed fluorescence emission material described in the first aspect of this application.

[0039] In some embodiments, the amount of the dopant material is 1-30 wt% of the host material, for example, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt% or any value between them.

[0040] In some embodiments, the substrate material is selected from one or more of glass, metal foil, or polymer film.

[0041] In some embodiments, the anode may be a transparent conductive indium tin oxide.

[0042] In some embodiments, the cathode may be conductive aluminum or other metals.

[0043] Definitions and general terms Unless otherwise stated, the terms used in the specification and claims of this invention have the following definitions.

[0044] Certain embodiments of the invention will now be described in detail, examples of which are illustrated by the accompanying structural and chemical formulas. The invention is intended to cover all alternatives, modifications, and equivalents, all of which are included within the scope of the invention as defined in the claims. Those skilled in the art will recognize that many similar or equivalent methods and materials can be used to practice the invention. The invention is by no means limited to the methods and materials described herein. In the event that one or more of the incorporated documents, patents, and similar materials differ from or contradict this application (including, but not limited to, defined terminology, application of terminology, described techniques, etc.), this application shall prevail.

[0045] It should be further appreciated that certain features of the invention, for clarity, have been described in multiple independent embodiments, but may also be provided in combination in a single embodiment. Conversely, various features of the invention, for brevity, have been described in a single embodiment, but may also be provided individually or in any suitable sub-combination.

[0046] Unless otherwise stated, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. All patents and publications related to this invention are incorporated herein by reference in their entirety.

[0047] Unless otherwise stated or there is a clear conflict in the context, the articles “a,” “an,” and “described” as used herein are intended to include “at least one” or “one or more.” Therefore, these articles as used herein refer to articles for one or more (i.e., at least one) objects. For example, “a component” refers to one or more components, meaning that more than one component may be considered for use or adoption in the implementation of the described embodiments.

[0048] In the present invention, for the expression of chemical elements, unless otherwise specified, it includes the concept of isotopes with the same chemical properties. For example, hydrogen (H) includes 1 H (protium), 2 H (deuterium, D), 3 H (tritium, T), etc.; carbon (C) includes 12C, 13C, etc.

[0049] In the present invention, unless otherwise specified, the heteroatoms of heteroaryl are selected from N, O, S, P, B, Si or Se, preferably N, O or S. The heteroatoms of heterocycloalkyl are selected from N, O, S, P, B, Si or Se, preferably N, O or S. The heteroatoms of aliphatic heterocycle are selected from N, O, S, P, B, Si or Se, preferably N, O or S.

[0050] In the present invention, the expression of the ring structure with a "-" drawn across it indicates that the connection site is at any position on the ring structure where bonding can occur.

[0051] In the present invention, " ", " " both represent the connection site of the group.

[0052] In the present invention, "independently of each other" means that when the subject has multiple ones, they can be the same or different from each other.

[0053] In the present invention, the expression of Ca-Cb represents that the group has a carbon atom number of a-b. Unless otherwise specified, the carbon atom number does not include the carbon atom number of the substituent.

[0054] In the present invention, the C1-C20 can all be C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18 or C19, etc.

[0055] In the present invention, the C3-C20 can all be C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18 or C19, etc.

[0056] In the present invention, the C2-C20 can all be C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18 or C19, etc.

[0057] In the present invention, the C6-C30 can all be C6, C9, C10, C12, C14, C16, C18, C20, C22, C24, C26 or C28, etc.

[0058] In this invention, C3-C30 can all be C3, C4, C5, C6, C9, C10, C12, C14, C16, C18, C20, C22, C24, C26, or C28, etc. The term "comprising" is an open-ended expression, meaning it includes the content specified in this invention, but does not exclude other aspects.

[0059] As described in this invention, the compounds of this invention may optionally be substituted with one or more substituents, such as the general formula compounds above, or as the specific examples, subclasses, and classes of compounds included in this invention as described in the embodiments. It should be understood that the term "optionally substituted" is used interchangeably with the term "substituted or unsubstituted." Generally, the term "optionally," whether or not preceding the term "substituted," refers to the substitution of one or more hydrogen atoms selected from the given structure by a specific substituent. Unless otherwise indicated, an optional substituent group may have one substituent substituted at each substituted position of the group. When more than one position in the given structural formula is substituted by one or more substituents selected from a specific group, the substituents may be substituted at the same or different positions. The substituents mentioned therein can be, but are not limited to, deuterium, hydroxyl, amino, halogen, cyano, aryl, heteroaryl, alkoxy, alkylamino, alkylthio, alkyl, alkenyl, alkynyl, heterocyclic, mercapto, nitro, aryloxy, heteroaryloxy, oxo (=O), carboxyl, hydroxy-substituted alkoxy, hydroxy-substituted alkyl-C (=O), alkyl-C (=O), alkyl-S (=O), alkyl-S (=O)2-, hydroxy-substituted alkyl-S (=O), hydroxy-substituted alkyl-S (=O)2, carboxyalkoxy, etc.

[0060] In the compounds mentioned in this invention, multiple substitution refers to the range including disubstitution, up to the maximum number of available substitutions. When a substituent in a compound mentioned in this invention represents multiple substitution (including disubstitution, trisubstitution, tetrasubstitution, etc.), it means that the substituent can exist at multiple available substitution positions on its linkage structure. The substituent existing at multiple available substitution positions can be of the same structure or different structures.

[0061] As used in this invention, the term "alkyl" refers to a saturated straight-chain or branched monovalent hydrocarbon group having 1-30 carbon atoms, or 1-20 carbon atoms, or 1-10 carbon atoms, or 1-6 carbon atoms, or 1-4 carbon atoms, or 1-3 carbon atoms, wherein the alkyl group may be independently and optionally substituted by one or more substituents described in this invention. Examples of alkyl groups include, but are not limited to, methyl (Me, -CH3), ethyl (Et, -CH2CH3), n-propyl (n-Pr, -CH2CH2CH3), isopropyl (i-Pr, -CH(CH3)2), n-butyl (n-Bu, -CH2CH2CH2CH3), isobutyl (i-Bu, -CH2CH(CH3)2), sec-butyl (s-Bu, -CH(CH3)CH2CH3), tert-butyl (t-Bu, -C(CH3)3), n-pentyl (-CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (-CH2CH2CH(CH3)2), 2-methyl-1- Butyl (-CH2CH(CH3)CH2CH3), n-hexyl (-CH2CH2CH2CH2CH2CH3), 2-hexyl (-CH(CH3)CH2CH2CH2CH3), 3-hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl (-CH(CH3)CH(CH3)CH2CH3) ), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3), n-heptyl, n-octyl, etc. The term "alkyl" and its prefix "alkane" are used herein to refer to both straight-chain and branched saturated carbon chains. The term "alkane" is used herein to refer to a saturated divalent hydrocarbon group obtained by eliminating two hydrogen atoms from a straight-chain or branched saturated hydrocarbon; examples of such groups include, but are not limited to, methylene, methine, methinepropyl, etc.

[0062] The term "alkoxy" as used in this invention refers to an alkyl group, as defined herein, that is attached to the main carbon chain by an oxygen atom. Examples of such alkyl groups include, but are not limited to, methoxy, ethoxy, propoxy, butoxy, etc. Furthermore, the alkoxy group may be substituted or unsubstituted, wherein the substituent may be, but is not limited to, hydroxyl, amino, halogen, cyano, alkoxy, alkyl, alkenyl, alkynyl, mercapto, nitro, etc.

[0063] The term "cycloalkyl" refers to a monovalent or polyvalent, non-aromatic, saturated or partially unsaturated ring that does not contain heteroatoms, including monocyclic rings of 3-12 carbon atoms or bicyclic rings of 7-12 carbon atoms. Bicyclic carbocyclic rings with 7-12 atoms can be bicyclic [4,5], [5,5], [5,6], or [6,6] systems, while bicyclic carbocyclic rings with 9 or 10 atoms can be bicyclic [5,6] or [6,6] systems. Suitable cyclic aliphatic groups include, but are not limited to, cycloalkyl, cycloalkenyl, and cycloynyl groups. Examples of cyclic aliphatic groups include, but are by no means limited to, cyclopropyl, cyclobutyl, cyclopentyl, 1-cyclopentyl-1-enyl, 1-cyclopentyl-2-enyl, 1-cyclopentyl-3-enyl, cyclohexyl, 1-cyclohexyl-1-enyl, 1-cyclohexyl-2-enyl, 1-cyclohexyl-3-enyl, cyclohexadienyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl, etc. Furthermore, the "cyclic aliphatic group" or "carbocyclic", "carbocyclic group", and "cycloalkyl" may be substituted or unsubstituted, wherein the substituent may be, but is not limited to, hydroxyl, amino, halogen, cyano, aryl, heteroaryl, alkoxy, alkylamino, alkyl, alkenyl, alkynyl, heterocyclic, mercapto, nitro, aryloxy, hydroxy-substituted alkoxy, hydroxy-substituted alkyl-C(=O), alkyl-C(=O), alkyl-S(=O), alkyl-S(=O)2-, hydroxy-substituted alkyl-S(=O), hydroxy-substituted alkyl-S(=O)2, carboxyalkoxy, etc.

[0064] The terms “heterocyclic,” “heterocyclic group,” “heterocyclic alicyclic group,” or “heterocyclic” are used interchangeably herein to refer to monocyclic, bicyclic, or tricyclic systems in which one or more carbon atoms on the ring are independently and optionally substituted with heteroatoms, which have the meaning as described herein. The ring may be fully saturated or contain one or more unsaturations, but is by no means aromatic, and has only one connection point to another molecule. One or more hydrogen atoms on the ring are independently and optionally substituted with one or more substituents described herein. Some of these embodiments are that the "heterocycle", "heterocyclic group", "heterocyclic alicyclic group" or "heterocyclic" group is a 3-7 membered monocyclic ring (1-6 carbon atoms and 1-3 heteroatoms selected from N, O, P, S, wherein S or P is optionally replaced by one or more oxygen atoms to obtain, for example, a group of S(=O), S(=O)2, P(=O), P(=O)2, and when the ring is a ternary ring, there is only one heteroatom), or a 7-10 membered bicyclic ring (4-9 carbon atoms and 1-3 heteroatoms selected from N, O, P, S, wherein S or P is optionally replaced by one or more oxygen atoms to obtain, for example, a group of S(=O), S(=O)2, P(=O), P(=O)2).

[0065] Heterocyclic groups can be carbonyl or heteroatomyl. "Heterocyclic group" also includes groups formed by the fusion of a heterocyclic group with a saturated or partially unsaturated ring or heterocycle. Examples of heterocycles include, but are not limited to, pyrrolidinyl, tetrahydrofuranyl, dihydrofuranyl, tetrahydrothiophenyl, tetrahydropyranyl, dihydropyranyl, tetrahydrothiophenyl, piperidinyl, morpholinyl, thiomorpholinyl, thiazolyl, thiazolyl, oxazolyl, piperazine, homopiperazine, azahexacyclic butyl, oxacyclobutyl, thiohexacyclic butyl, piperidinyl, homopiperidinyl, glycidyl, azaheptanyl, oxacycloheptanyl, thioheptanyl, 4-methoxy-piperidin-1-yl, 1,2, 3,6-Tetrahydropyridin-1-yl, oxazolidinyl, diazadinyl, thioazolidinyl, pyrrolin-1-yl, 2-pyrrolinyl, 3-pyrrolinyl, dihydroindolyl, 2H-pyranyl, 4H-pyranyl, dioxacyclohexyl, 1,3-dioxopentyl, pyrazolinyl, dithiaalkyl, dithiamonyl, dihydrothiophenyl, pyrazolinyl imidazolinyl, imidazolinyl, 1,2,3,4-tetrahydroisoquinolinyl, 1,2,6-thiadiazine 1,1-dioxo-2- 4-hydroxy-1,4-azaphosphane 4-oxide-1-yl, 2-hydroxy-1-(piperazin-1-yl)acetone-4-yl, 2-hydroxy-1-(5,6-dihydro-1,2,4-triazin-1(4H)-yl)acetone-4-yl, 5,6-dihydro-4H-1,2,4-oxadiazin-4-yl, 2-hydroxy-1-(5,6-dihydropyridin-1(2H)-yl)acetone-4-yl, 3-azabicyclo[3.1.0]hexyl, 3- Examples of heterocyclic groups include azabicyclo[4.1.0]heptyl, azabicyclo[2.2.2]hexyl, 2-methyl-5,6,7,8-tetrahydro-[1,2,4]triazol[1,5-c]pyrimidin-6-yl, 4,5,6,7-tetrahydroisoxazol[4,3-c]pyridin-5-yl, 3H-indolyl-2-oxo-5-azabicyclo[2.2.1]heptane-5-yl, 2-oxo-5-azabicyclo[2.2.2]octane-5-yl, quinazinyl, and N-pyridylurea. Examples of heterocyclic groups also include 1,1-dioxothiomorpholinyl, and groups in which two carbon atoms on the ring are replaced by oxygen atoms, such as pyrimidinyldione groups. Furthermore, the heterocyclic group can be substituted or unsubstituted, wherein the substituent can be, but is not limited to, oxo (=O), hydroxyl, amino, halogen, cyano, heteroaryl, alkoxy, alkylamino, alkyl, alkenyl, alkynyl, heterocyclic, mercapto, nitro, aryloxy, hydroxy-substituted alkoxy, hydroxy-substituted alkyl-C (=O), alkyl-C (=O), alkyl-S (=O), alkyl-S (=O)2-, hydroxy-substituted alkyl-S (=O), hydroxy-substituted alkyl-S (=O)2, carboxyalkoxy, etc.

[0066] In this invention, unless otherwise specified, the term C6-C30 aryl (C6-C30 aromatic ring) includes monocyclic aryl and fused-ring aryl; the monocyclic aryl means that the group contains at least one phenyl group, and when it contains at least two phenyl groups, the phenyl groups are linked by a single bond, exemplarily including but not limited to: phenyl, biphenyl, terphenyl, tetraphenyl, etc.; the fused-ring aryl means that the group contains at least two rings (and at least one ring is an aromatic ring), and the rings share two adjacent carbon atoms that are fused together, exemplarily including but not limited to: naphthyl, anthraceneyl, phenanthryl, indene, fluorenyl and their derivatives (9,9-dimethyl... Aryl fluorenyl, 9,9-diethylfluorenyl, 9,9-dipropylfluorenyl, 9,9-dibutylfluorenyl, 9,9-dipentylfluorenyl, 9,9-dihexylfluorenyl, 9,9-diphenylfluorenyl, 9-methyl-9-phenylfluorenyl, 9,9-dinaphthylfluorenyl, spirodifluorenyl, benzo[A]fluorenyl, benzo[B]fluorenyl, benzo[C]fluorenyl, fluoranyl, triphenylene, pyrene, peryl, phenyl, tetraphenyl, acenaphthene, benzo[acenaphthene], etc. It should be noted that monocyclic aryl and fused-ring aryl groups linked by single bonds also fall under the category of aryl groups, such as phenylnaphthyl, naphthylphenyl, and binaphthyl.

[0067] In this invention, unless otherwise specified, the term C3-C30 heteroaryl (C3-C30 heteroaryl ring) includes monocyclic heteroaryl or fused-ring heteroaryl. A monocyclic heteroaryl means that the molecule contains at least one heteroaryl group. When the molecule contains one heteroaryl group and other groups (such as aryl, heteroaryl, etc.), the heteroaryl group and other groups are connected by a single bond, exemplarily including but not limited to: pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, furanyl, thiophene, pyrroleyl, bipyridyl, phenylpyridinyl, pyridylphenyl, etc. The term "fused-ring heteroaryl" refers to a molecule containing at least one aromatic heterocycle and one aromatic ring (aromatic heterocycle or aromatic ring), which share two adjacent fused groups. Exemplary examples include, but are not limited to: quinolinyl, isoquinolinyl, quinoxalinyl, quinazolinyl, benzofuranyl, benzothiopheneyl, isobenzofuranyl, isobenzothiopheneyl, indolyl, dibenzofuranyl, benzonaphthofuranyl (benzo[B]naphtho[2,3-D]furanyl, benzo[B]naphtho[1,2-D) Furanyl, benzo[B]naphtho[2,1-D]furanyl), dibenzothiophenyl, benzo[B]naphtho[2,3-D]thiophenyl, benzo[B]naphtho[1,2-D]thiophenyl, benzo[B]naphtho[2,1-D]thiophenyl, carbazoleyl and its derivatives (N-phenylcarbazoleyl, N-naphthylcarbazoleyl, benzocarbazoleyl, dibenzocarbazoleyl, indole-carbazoleyl, azacarbazoleyl, etc.), acridineyl, phenothiazinyl, phenotoxazinyl, hydrogenated acridineyl, etc.

[0068] In this invention, specific examples of the term C6-C30 arylamino are monovalent groups obtained by substituting at least one hydrogen atom in -NH2 with the aforementioned aryl group, including but not limited to: phenylamino, methylphenylamino, naphthylamino, anthraceneylamino, phenanthreneamino, biphenylamino, etc. Specific examples of the term C3-C30 heteroarylamino are monovalent groups obtained by substituting at least one hydrogen atom in -NH2 with the aforementioned heteroaryl group, including but not limited to: pyridinylamino, pyrimidinylamino, dibenzofuranylamino, etc.

[0069] In this invention, the term C6-C30 aryloxy group refers to a monovalent group formed by attaching the aforementioned aryl group to O, and the term C3-C30 heteroaryloxy group refers to a monovalent group formed by attaching the aforementioned heteroaryl group to O.

[0070] In this invention, the term C6-C30 arylthio group refers to a monovalent group formed by attaching the aforementioned aryl group to S, and the term C3-C30 heteroarylthio group refers to a monovalent group formed by attaching the aforementioned heteroaryl group to S.

[0071] In the compounds mentioned in this invention, hydrogen atoms can be partially or completely replaced by deuterium. Other atoms such as carbon and nitrogen can also be replaced by their other stable isotopes. Substitution with other stable isotopes in the compounds may be preferred due to their ability to enhance device efficiency and stability.

[0072] In this invention, unless explicitly specified, for example, that adjacent substituents can optionally connect to form a ring, adjacent substituents in the compound cannot connect to form a ring. In the compounds mentioned in this disclosure, the optional connection of adjacent substituents to form a ring includes both cases where adjacent substituents can connect to form a ring and cases where adjacent substituents do not connect to form a ring. When adjacent substituents can optionally connect to form a ring, the formed ring can be a monocyclic or polycyclic ring, and can be an alicyclic, heterocyclic, aromatic, or heteroaromatic ring. In this context, adjacent substituents can refer to substituents bonded to the same atom, substituents bonded to carbon atoms directly bonded to each other, or substituents bonded to carbon atoms further away. Preferably, adjacent substituents refer to substituents bonded to the same carbon atom and substituents bonded to carbon atoms directly bonded to each other.

[0073] The statement that adjacent substituents can optionally connect to form a ring also refers to the formation of a ring by two substituents bonded to the same carbon atom, which can be exemplified by the following formula: .

[0074] The statement that adjacent substituents can optionally connect to form a ring also refers to the formation of a ring by two substituents that are considered to be bonded to carbon atoms directly bonded to each other, which can be exemplified by the following formula: .

[0075] Furthermore, the statement that adjacent substituents can optionally connect to form a ring is also intended to mean that, in the case where one of the two substituents bonded to the carbon atom directly bonded to each other represents hydrogen, the second substituent bonds at the position where the hydrogen atom is bonded, thereby forming a ring. This is illustrated by the following example: .

[0076] Example 1 (1) Synthesis of intermediate M1 (3,6-di-tert-butyl-9-(2-(4-(tert-butyl)phenyl)pyrimidin-5-yl)-9H-carbazole) Tris(dibenzylacetone)dipalladium (Pd2(dba)3) (0.04 g, 0.04 mmol) and 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (XPhos) (0.04 g, 0.08 mmol) were added to a dry three-necked flask, and the air was replaced with nitrogen. 50 ml of toluene was added and stirred to dissolve the precipitate. The mixture was then heated to 60 °C and reacted for 10 min. Subsequently, 3,6-tert-butylcarbazole (0.6 g, 2.15 mmol), 2-tert-butylphenyl-5-chloropyrimidine (0.45 g, 2.36 mmol), and sodium tert-butoxide (0.29 g, 3 mmol) were added, and the mixture was heated to 120 °C and reacted for 24 h. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. Water / dichloromethane was added for extraction, and the organic phase was collected, dried over anhydrous Na2SO4, purified by column chromatography, and recrystallized to obtain intermediate M1. The yield was 92.5%. 1 H NMR (400 MHz, CDCl3) d (ppm): 9.07 (s, 2H), 8.48 (d, J = 8.1 Hz, 2H), 8.15(d, J = 1.8 Hz, 2H), 7.58 (d, J = 8.0 Hz, 2H), 7.51 (dd, J = 8.7, 2.0 Hz,2H), 7.37 (d, J = 8.6 Hz, 2H), 1.47 (s, 18H), 1.40 (s, 9H). (2) Synthesis of intermediate M2 (1-bromo-3,6-di-tert-butyl-9-(2-(4-tert-butylphenyl)pyrimidin-5-yl)-9H-carbazole) Intermediate M1 (0.7 g, 1.48 mmol) was added to a dry three-necked flask, the air was replaced with nitrogen, 50 ml of tetrahydrofuran was added and stirred until dissolved, and then cooled to 0°C in an ice bath. The solution dissolved in tetrahydrofuran was then... N 1-Bromosuccinimide (NBS) (0.29 g, 1.63 mmol) was added dropwise to a three-necked flask and reacted at 30 °C for 12 h. After the reaction was complete, water / dichloromethane was added for extraction, the organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to give intermediate M2. The yield was 64.0%. 1 H NMR (400 MHz, CDCl3) d (ppm): 8.85 (s, 2H), 8.53 – 8.47 (m, 2H), 8.12 (t, 2H), 7.62 – 7.55 (m, 3H), 7.49 (m, 1H), 7.06 (d, J = 8.7 Hz, 1H), 1.43 (m, 27H). (3) Synthesis of the target product NICz A dry three-necked flask was purged with nitrogen, and intermediate M2 (0.4 g, 0.71 mmol), cesium carbonate (0.7 g, 2.15 mmol), and terpentine (PivOH) (0.29 g, 2.84 mmol) were added. The flask was then purged with nitrogen again, and bis(triphenylphosphine)palladium dichloride (0.13 g, 0.185 mmol) and tricyclohexylphosphine (PCy3) (0.2 g, 0.71 mmol) were added. 15 mL of anhydrous toluene was added and stirred until dissolved. The mixture was heated to 120 °C and reacted for 24 h. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. The mixture was extracted with water / dichloromethane, and the organic phase was collected, dried over anhydrous Na2SO4, purified by column chromatography, and recrystallized to obtain the product of Example 1. The yield was 63.3%. 1 H NMR (400 MHz, CDCl3) d (ppm): 9.35 (d, J = 1.3 Hz,1H), 8.55 (m, 2H), 8.49 (d, J = 1.3 Hz, 1H), 8.37 (d, J = 1.4 Hz, 1H), 8.21 (t, J =1.6 Hz, 1H), 7.81 (m, 1H), 7.66 (m, 1H), 7.58 (m, 2H), 1.45 (m, J = 35.0, 1.3Hz, 27H).

[0077] Example 2 (1) Synthesis of M3: Tris(dibenzylacetone)dipalladium (0.057 g, 0.06 mmol) and 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (0.059 g, 0.12 mmol) were added to a dry three-necked flask, and the air was replaced with nitrogen. 100 ml of toluene was added and stirred until dissolved. The mixture was heated to 60 °C and reacted for 10 min. Subsequently, 5H-benzofurano[3,2-C]carbazole (0.8 g, 3.11 mmol), 2-tert-butylphenyl-5-chloropyrimidine (0.71 g, 3.73 mmol), and sodium tert-butoxide (0.42 g, 4.35 mmol) were added, and the mixture was heated to 120 °C and reacted for 24 h. The reaction was monitored by TLC. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. Water / dichloromethane was added for extraction, and the organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain M3. The yield was 90.4%. 1 H NMR (400 MHz, CDCl3) d (ppm): 9.12 (s, 2H), 8.63 – 8.58 (m, 1H), 8.50(d, J = 8.4 Hz, 2H), 8.01 (m, 2H), 7.76 (d, J = 8.0 Hz, 1H), 7.60 (d, J = 8.4Hz, 2H), 7.50 (m, 4H), 7.41 (m, 2H), 1.42 (s, 9H). (2) Synthesis of M4: Intermediate M3 (0.6 g, 1.28 mmol) was added to a dry three-necked flask, the air was replaced with nitrogen, 50 ml of tetrahydrofuran was added and stirred until dissolved, and then cooled to 0°C in an ice bath. The solution dissolved in tetrahydrofuran was then... N 1-Bromosuccinimide (0.34 g, 1.93 mmol) was added dropwise to a three-necked flask and reacted at 30 °C for 12 h. After the reaction was complete, water / dichloromethane was added for extraction, and the organic phase was collected and dried over anhydrous Na2SO4 to obtain intermediate M4. (3) Synthesis of the target product DBF-NICz: A dry three-necked flask was purged with nitrogen, and intermediate M4 (0.78 g, 1.43 mmol), cesium carbonate (1.4 g, 4.29 mmol), and terpentine (0.58 g, 5.72 mmol) were added. The flask was then purged with nitrogen again, and bis(triphenylphosphine)palladium dichloride (0.5 g, 0.72 mmol) and tricyclohexylphosphine (0.4 g, 1.43 mmol) were added. 50 mL of anhydrous toluene was added and stirred until dissolved. The mixture was heated to 120 °C and reacted for 48 h. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. The mixture was extracted with water / dichloromethane, and the organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 41.5%. 1 H NMR (400 MHz, CDCl3) d (ppm): 1 H NMR (400 MHz, Chloroform-d) δ 9.31 (s,1H), 8.85 (s, 1H), 8.58 (d, J = 8.4 Hz, 2H), 8.38 (d, J = 7.8 Hz, 1H), 8.11(d, J = 7.4 Hz, 1H), 7.90 (d, J = 8.1 Hz, 1H), 7.73 – 7.59 (m, 4H), 7.56 –7.44 (m, 3H), 1.43 (s, 9H).

[0078] Example 3 (1) Synthesis of M5 Tris(dibenzylacetone)dipalladium (0.14 g, 0.16 mmol) and 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (0.14 g, 0.31 mmol) were added to a dry three-necked flask, and the air was replaced with nitrogen. 100 mL of toluene was added and stirred until dissolved. The mixture was heated to 60 °C and reacted for 10 min. Then, 3,6-phenylcarbazole (2.49 g, 7.78 mmol), 2-tert-butylphenyl-5-chloropyrimidine (2.1 g, 8.55 mmol), and sodium tert-butoxide (1.05 g, 10.91 mmol) were added, and the mixture was heated to 120 °C and reacted for 24 h. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. Water was added, and the mixture was extracted with dichloromethane. The organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 85.3%. 1 H NMR (400 MHz, CDCl3) d(ppm): 9.10 (s, 2H), 8.49 (d, J = 8.3 Hz, 2H), 8.41 (d, J = 1.8 Hz,2H), 7.75 – 7.70 (m, 6H), 7.59 (d, J = 8.3 Hz, 2H), 7.50 (dt, J = 7.7, 3.5Hz, 6H), 7.37 (t, J = 7.4 Hz, 2H), 1.41 (s, 9H). (2) Synthesis of M6 Intermediate M5 (2.3 g, 3.78 mmol) was added to a dry three-necked flask, the air was replaced with nitrogen, 50 ml of tetrahydrofuran was added and stirred until dissolved, and then cooled to 0°C in an ice bath. The solution in DMF was then... N 0.74 g (4.16 mmol) of bromosuccinimide was added dropwise to a three-necked flask and reacted overnight at 60 °C. After the reaction was complete, water / dichloromethane was added for extraction, the organic phase was collected and dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 64.0%. 1 HNMR (400 MHz, CDCl3) d (ppm): 8.97 (s, 2H), 8.18 (d, J = 6.8 Hz, 1H), 8.14 (d,J = 2.4 Hz, 1H), 7.99 (d, J = 2.2 Hz, 1H), 7.87 (d, J = 2.0 Hz, 1H), 7.85 –7.80 (m, 2H), 7.73 (dd, J = 6.8, 2.4 Hz, 1H), 7.61 (dd, J = 8.1, 1.5 Hz, 4H), 7.51 – 7.47 (m, 2H), 7.47 – 7.34 (m, 6H), 1.41 (s, 9H). (3) Synthesis of the target product tPh-NICz A dry three-necked flask was purged with nitrogen, and intermediate M6 (2.4 g, 4 mmol), cesium carbonate (5.15 g, 16 mmol), and terpentine (1.61 g, 16 mmol) were added. The flask was then purged with nitrogen again, and bis(triphenylphosphine)palladium dichloride (0.28 g, 0.4 mmol) and tricyclohexylphosphine (0.227 g, 0.8 mmol) were added. 100 mL of anhydrous toluene was added and stirred until dissolved. The mixture was heated to 120 °C and reacted for 48 h. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. Extraction with water / dichloromethane was performed, and the organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 29.7%. 1 H NMR (400MHz, CDCl3) d (ppm): 9.25 (s, 1H), 8.55 – 8.49 (m, 3H), 8.37 (d, J = 1.0 Hz,1H), 8.31 (d, J = 1.4 Hz, 1H), 7.80 – 7.68 (m, 6H), 7.61 – 7.47 (m, 6H), 7.45– 7.39 (m, 2H), 1.41 (s, 9H).

[0079] Example 4 (1) Synthesis of M7 Tris(dibenzylacetone)dipalladium (0.17 g, 0.18 mmol) and 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (0.17 g, 0.36 mmol) were added to a dry three-necked flask, and the air was replaced with nitrogen. 100 mL of toluene was added and stirred until dissolved. The mixture was heated to 60 °C and reacted for 10 min. Subsequently, 3,6-phenylcarbazole (2.9 g, 9.08 mmol), 2-ethoxy-5-bromopyrimidine (2 g, 9.53 mmol), and sodium tert-butoxide (1.22 g, 12.7 mmol) were added, and the mixture was heated to 120 °C and reacted overnight. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. Water was added, and the mixture was extracted with dichloromethane. The organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 93.73%. 1 H NMR (400 MHz, CDCl3) d(ppm): 8.75 (s, 2H), 8.38 (d, J = 1.8 Hz, 2H), 7.73 – 7.68 (m, 5H), 7.67 (d,J = 1.8 Hz, 1H), 7.47 (t, J = 7.6 Hz, 4H), 7.39 – 7.29 (m, 4H), 4.57 (q, J =7.1 Hz, 2H), 1.57 – 1.50 (m, 3H). (2) Synthesis of M8 Intermediate M7 (2.8 g, 6.34 mmol) was added to a dry three-necked flask, the air was replaced with nitrogen, 50 ml of tetrahydrofuran was added and stirred until dissolved, and then cooled to 0°C in an ice bath. The solution in DMF was then... N 1.35 g (7.61 mmol) of bromosuccinimide was added dropwise to a three-necked flask and reacted overnight at room temperature. After the reaction was complete, water / dichloromethane was added for extraction, the organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 75.9%. 1 HNMR (400 MHz, CDCl3) d (ppm): 8.62 (s, 2H), 8.35 (t, J = 1.8 Hz, 2H), 7.85 (d,J = 1.7 Hz, 1H), 7.72 – 7.66 (m, 5H), 7.48 (td, J = 7.7, 1.9 Hz, 5H), 7.37(td, J = 7.7, 5.5 Hz, 2H), 4.58 (q, J = 7.1 Hz, 2H), 1.54 (t, J = 7.1 Hz, 3H). (3) Synthesis of the target compound OEt-NICz A dry three-necked flask was purged with nitrogen, and intermediate M8 (2.6 g, 5 mmol), cesium carbonate (6.53 g, 20 mmol), and terpentine (2.04 g, 20 mmol) were added. The flask was then purged with nitrogen again, and bis(triphenylphosphine)palladium dichloride (0.35 g, 0.5 mmol) and tricyclohexylphosphine (0.28 g, 1 mmol) were added. 100 mL of anhydrous toluene was added and stirred until dissolved. The mixture was heated to 120 °C and reacted for 48 h. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. Extraction with water / dichloromethane was performed, and the organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 33.2%. 1 H NMR (400MHz, CDCl3) d(ppm): 9.00 (d, 1H), 8.39–8.42 (d, 2H), 8.33 (s, 1H), 7.79 (m, 2H), 7.71–7.74 (m, 4H), 7.50–7.54 (m, 4H), 7.40–7.49 (m, 2H), 4.58 (m, 2H), 1.54 (m, 3H). Transient fluorescence lifetime and delayed fluorescence lifetime are shown in the figure. Figure 2 As shown in (a), where the inset is a transient fluorescence lifetime diagram, it can be seen that the fluorescent emitting material of this application has a long lifetime.

[0080] Example 5 (1) Synthesis of intermediate M9 Tris(dibenzylacetone)dipalladium (0.12 g, 0.13 mmol) and 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (0.12 g, 0.25 mmol) were added to a dry three-necked flask, and the air was replaced with nitrogen. 100 mL of toluene was added and stirred until dissolved. The mixture was heated to 60 °C and reacted for 10 min. Subsequently, 3,6-phenylcarbazole (2 g, 6.26 mmol), 2-methylmercapto-5-bromopyrimidine (1.41 g, 6.89 mmol), and sodium tert-butoxide (0.84 g, 8.77 mmol) were added, and the mixture was heated to 120 °C and reacted overnight. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. Water was added, and the mixture was extracted with dichloromethane. The organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 92.9%. 1 H NMR (400 MHz, CDCl3) d (ppm): 8.82 (s, 2H), 8.39 (d, J = 1.7 Hz, 2H), 7.71 (m, 6H), 7.48 (t,4H), 7.41 – 7.32 (m, 4H), 2.69 (s, 3H). (2) Synthesis of intermediate M10 Intermediate M9 (1.5 g, 3.39 mmol) was added to a dry three-necked flask, the air was replaced with nitrogen, 50 ml of DMF was added and stirred until dissolved, and then cooled to 0°C in an ice bath. The solution in DMF was then... N 0.66 g (3.72 mmol) of bromosuccinimide was added dropwise to a three-necked flask and reacted overnight at 60 °C. After the reaction was complete, water / dichloromethane was added for extraction, the organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 73.23%. 1H NMR (400MHz, CDCl3-d) d (ppm): 8.76 (s, 1H), 8.32 (d, J = 1.8 Hz, 1H), 7.64 (m, 6H), 7.42 (t, 5H), 7.34 – 7.27 (m, 4H), 2.63 (s, 3H). (3) Synthesis of the target compound SMe-NICz A dry three-necked flask was purged with nitrogen, and intermediate M10 (1.5 g, 2.44 mmol), cesium carbonate (1.19 g, 3.66 mmol), and terpentine (1.0 g, 9.77 mmol) were added. The flask was then purged with nitrogen again, and bis(triphenylphosphine)palladium dichloride (0.17 g, 0.24 mmol) and tricyclohexylphosphine (0.068 g, 0.24 mmol) were added. 100 mL of anhydrous toluene was added and stirred until dissolved. The mixture was heated to 120 °C and reacted for 48 h. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. Extraction with water / dichloromethane was performed, and the organic phase was collected, dried over anhydrous Na₂SO₄, purified by column chromatography, and recrystallized to obtain the target product. The yield was 31.7%. 1 H NMR (400 MHz, CDCl3-d) d (ppm): 9.14 (s, 1H), 8.53 – 8.42 (m, 2H), 8.37 (d, J = 1.3 Hz, 1H), 7.84 (s, 2H), 7.74 (m, 4H), 7.53 (m, 4H), 7.47 – 7.37 (m, 2H), 2.78 (s, 3H). Transient and delayed fluorescence lifetimes are shown in the graphs. Figure 2 As shown in (b), where the inset is a transient fluorescence lifetime diagram, it can be seen that the fluorescent emitting material of this application has a long lifetime.

[0081] Example 6 (1) Synthesis of M11 3,6-Dibromo-9H-carbazole (3.08 g, 9.48 mmol) was added to a three-necked flask, evacuated, and purged three times with dry nitrogen. 25 mL of anhydrous DMF was added and stirred to dissolve. Then, NaH (1.14 g, 28.46 mmol) was dissolved in anhydrous DMF (25 mL) and slowly added dropwise to the flask using a syringe. The mixture was stirred at room temperature for 1 hour. Next, 2-(4-(tert-butyl)phenyl)-5-fluoropyrimidine (2.40 g, 10.43 mmol) was dissolved in anhydrous DMF (25 mL) and slowly added dropwise to the mixture using a syringe. The mixture was stirred at 60 °C for 12 hours, and the reaction was monitored by TLC. After the reaction was complete, the mixture was cooled to room temperature, poured into 200 mL of water, filtered, and the precipitate was collected and dried under vacuum. The residue was purified by silica gel column chromatography (dichloromethane / petroleum ether) to obtain the target product. The yield was 63.69%. 1 HNMR (400MHz, CDCl3) d (ppm): 8.97 (s, 2H), 8.45 (d, J = 8.2 Hz, 2H), 8.20 (d, J = 1.9 Hz, 2H), 7.61–7.52 (m, 4H), 7.26 (d, J = 8.6 Hz, 2H), 1.40 (s, 9H). (2) Synthesis of M12 Intermediate M11 (2.00 g, 3.74 mmol) was added to a three-necked flask, evacuated, and purged three times with dry nitrogen. Then, 10 ml of DMF was injected, and the mixture was stirred at 0°C for 1 hour. N 0.79 g (4.49 mmol) of bromosuccinimide was dissolved in DMF (30 ml) and slowly added dropwise to the reaction mixture. The reaction mixture was stirred at 70 °C for 12 hours. After the reaction was complete, the mixture was cooled to room temperature, poured into 100 ml of deionized water, filtered, and the precipitate was washed and dried under vacuum. The product was purified by silica gel column chromatography (dichloromethane / petroleum ether) to obtain the target product. The yield was 62.6%. 1 HNMR (400MHz, CDCl3) d (ppm): 8.84 (d, J = 1.3 Hz, 2H), 8.52–8.47 (m, 2H), 8.20 (dt, J = 5.3, 1.5Hz, 2H), 7.74 (d, J = 1.4 Hz, 1H), 7.60–7.53 (m, 3H), 7.00 (d, J = 9.2 Hz,1H), 1.40 (s, 9H). (3) Synthesis of M13 Intermediate M12 (2.10 g, 3.41 mmol), pentylamino acid (1.39 g, 13.66 mmol), and cesium carbonate (4.45 g, 13.66 mmol) were added to a three-necked flask, which was then evacuated and purged three times with dry nitrogen. Subsequently, bis(triphenylphosphine)palladium dichloride (0.24 g, 0.34 mmol) and tricyclohexylphosphine (0.19 g, 0.68 mmol) were added, the flask was sealed, and the mixture was rinsed with nitrogen. 50 mL of anhydrous toluene was added to the three-necked flask, and the reaction mixture was stirred at 120 °C for 48 hours, with the reaction progress monitored by TLC. After the reaction was complete, the mixture was cooled to room temperature, quenched with deionized water, extracted with dichloromethane, and dried over anhydrous Na₂SO₄. The product was purified by silica gel column chromatography (dichloromethane / petroleum ether) to obtain the target product. The yield was 20.31%. 1 H NMR (400MHz, CDCl3) d (ppm): 9.28 (d, J = 2.8 Hz, 1H), 8.55–8.45 (m,3H), 8.24 (s, 1H), 8.18 (d, J = 1.8 Hz, 1H), 7.71 (dt, J = 11.1, 8.5 Hz, 2H), 7.62–7.55 (m, 2H), 1.41 (s, 9H). HRMS(ESI): C 26 H 19 N3Br2[M+H] + 532.00185, found 532.00626. (4) Synthesis of the target compound PhCz-NICz The starting material M13 (0.20 g, 0.38 mmol) and 4-(9H-carbazole-9-yl)phenylboronic acid (0.23 g, 0.79 mmol) were added to a three-necked flask, and the mixture was evacuated and purged three times with dry nitrogen. Then, tetra(triphenylphosphine)palladium (0.02 g, 0.015 mmol), 1,4-dioxane (15 ml), potassium carbonate (0.52 g, 3.75 mmol), and water (5 ml) were added. The reaction mixture was stirred at 110 °C for 30 hours. After the reaction was complete, it was cooled to room temperature, quenched with deionized water, extracted with dichloromethane, and dried over anhydrous Na₂SO₄. The solid was purified by recrystallization after silica gel column chromatography to obtain the target product. The yield was 95.2%. 1 HNMR (400MHz, CDCl3) d(ppm): 9.42 (s, 1H), 8.72 (s, 1H), 8.62 (d, J =8.9 Hz, 3H), 8.53 (s, 1H), 8.18 (d, J = 7.8 Hz, 4H), 8.03 (d, J = 8.0 Hz,2H), 7.99 (d, J = 7.3 Hz, 4H), 7.75 (t, J = 8.7 Hz, 4H), 7.62 (d, J = 8.2 Hz,2H), 7.54 (m, 4H), 7.45 (t, 4H), 7.32 (t, 4H), 1.40 (s, 9H). Such as Figure 2 As shown in the figure. Transient fluorescence lifetime and delayed fluorescence lifetime are plotted as follows. Figure 2 As shown in (c), where the inset is a transient fluorescence lifetime diagram, it can be seen that the fluorescent emitting material of this application has a long lifetime.

[0082] Example 7 Synthesis of the target compound tCz-NICz Tris(dibenzylacetone)dipalladium (0.02 g, 0.02 mmol) and 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (0.02 g, 0.08 mmol) were added to a dry three-necked flask, and the air was replaced with nitrogen. 100 ml of toluene was added and stirred until dissolved. The mixture was heated to 60 °C and reacted for 10 min. Then, M13 (prepared in the same manner as in Example 6, 0.53 g, 0.10 mmol), 3,6-tert-butylcarbazole (0.33 g, 0.12 mmol), and sodium tert-butoxide (0.14 g, 1.40 mmol) were added, and the mixture was heated to 120 °C and reacted overnight. After the reaction was complete, heating was stopped and the mixture was cooled to room temperature. Water / dichloromethane was added for extraction. The organic phase was collected, dried over anhydrous Na2SO4, purified by column chromatography, and recrystallized to obtain the target product. The yield was 89.72%. 1 HNMR (400MHz, CDCl3) d (ppm): 1¹H NMR (400 MHz, CDCl₃) δ 8.66 (s, 1H), 8.61 (m, 3H), 8.34 (s, 1H), 8.28 (d, J = 2.0 Hz, 1H), 8.24 – 8.15 (m, 4H), 7.84 (m, 1H), 7.58 (d, J = 8.2 Hz, 2H), 7.49 (m, 5H), 7.42 (d, J = 8.6 Hz, 2H), 7.35 (d, J = 8.7 Hz, 2H), 1.48 (s, 36H), 1.40 (s, 9H). As shown in Figure 8. Transient fluorescence lifetime and delayed fluorescence lifetime plots are shown below. Figure 2 As shown in (d), where the inset is a transient fluorescence lifetime diagram, it can be seen that the fluorescent emitting material of this application has a long lifetime.

[0083] Example 8 M13 (0.20 g, 0.38 mmol) and dibenzo[b,d]furan-1-ylboronic acid (0.17 g, 0.79 mmol) were added to a three-necked flask, and the mixture was evacuated and purged three times with dry nitrogen. Then, a 5 mL aqueous solution of tetra(triphenylphosphine)palladium (0.02 g, 0.015 mmol), 1,4-dioxane (15 mL), and potassium carbonate (0.52 g, 3.75 mmol) was added. The reaction mixture was stirred at 110 °C for 30 hours. After the reaction was complete, it was cooled to room temperature, quenched with deionized water, extracted with dichloromethane, and dried over anhydrous Na₂SO₄. The solid was purified by recrystallization after silica gel column chromatography to obtain the target product. The yield was 93.0%. 1 HNMR (400MHz, CDCl3) d (ppm): 9.50 (s, 1H), 8.69 (s, 1H), 8.57 (d, J =8.2 Hz, 2H), 8.50 (s, 1H), 8.42 (s, 1H), 8.11 (d, J = 8.2 Hz, 1H), 7.95 (dd,J = 8.2, 1.5 Hz, 1H), 7.66 – 7.52 (m, 9H), 7.44 – 7.34 (m, 5H), 7.09 (t, J =7.6 Hz, 1H), 7.00 (t, J = 7.6 Hz, 1H), 1.40 (s, 9H).

[0084] Example 9 M13 (0.20 g, 0.38 mmol) and 2-boronic acid-9,9'-spirodifluorene (0.35 g, 0.79 mmol) were added to a three-necked flask, and the mixture was evacuated and purged three times with dry nitrogen. Then, an aqueous solution (5 ml) of tetra(triphenylphosphine)palladium (0.02 g, 0.015 mmol), 1,4-dioxane (15 ml), and potassium carbonate (0.52 g, 3.75 mmol) was added. The reaction mixture was stirred at 110 °C for 30 hours. After the reaction was complete, it was cooled to room temperature, quenched with deionized water, extracted with dichloromethane, and dried over anhydrous Na₂SO₄. The solid was purified by recrystallization after silica gel column chromatography to obtain the target product. The yield was 91.8%. 1 HNMR (400MHz, CDCl3) d (ppm): 9.29 (s, 1H), 8.63 – 8.53 (m, 3H), 8.47 (s, 1H), 8.39 (s, 1H), 8.28 – 8.18 (m, 2H), 7.98 (d, J = 7.6 Hz, 2H), 7.92 – 7.81 (m,6H), 7.58 (d, J = 8.2 Hz, 2H), 7.51 – 7.35 (m, 8H), 7.19 – 7.09 (m, 6H), 6.84(tt, J = 15.6, 7.9 Hz, 8H), 1.40 (s, 9H).

[0085] Comparative Example 1 The starting material, 5,11-dibromoindolo[3,2,1-jk]carbazole (0.16 g, 0.38 mmol) and 4-(3,6-di-tert-butyl-9H-carbazole-9-yl)phenylboronic acid (0.32 g, 0.79 mmol), was added to a three-necked flask, and the mixture was evacuated and purged three times with dry nitrogen. Then, tetra(triphenylphosphine)palladium (0.02 g, 0.015 mmol), 1,4-dioxane (15 ml), and potassium carbonate (0.52 g, 3.75 mmol) in water (5 ml) were added. The reaction mixture was stirred at 110 °C for 30 hours. After the reaction was complete, it was cooled to room temperature, quenched with deionized water, extracted with dichloromethane, and dried over anhydrous Na₂SO₄. The solid was purified by recrystallization after silica gel column chromatography to obtain the target product. The yield was 90.2%. 1 HNMR (400MHz, CDCl3) d(ppm): 8.62(m, 2H), 8.56-58(d, 2H), 8.42-8.46(d, 2H), 8.21−8.16 (d, 4H), 8.1(s, 2H),7.98−7.96 (d, 4H), 7.87−7.84 (d, 4H), 7.69−7.66 (d, 4H), 7.60 (s, 4H), 7.51−7.44 (m, 1H), 1.48 (s, 18H).

[0086] Device Example 1 The specific steps for fabricating organic electroluminescent devices include: 1. The patterned ITO glass is ultrasonically cleaned in a cleaning solution, rinsed with deionized water, ultrasonically cleaned in a mixed solution of ethanol and acetone, rinsed further with deionized water, and then placed under nitrogen until it is dried. Finally, it is treated with a UV machine. 2. Place the cleaned glass slide with the anode pattern into the vapor deposition apparatus and evacuate to a vacuum of 5 × 10⁻⁶. - 5 MPa. A hole injection layer HI is formed by evaporating hole injection material onto the anode layer film, with a evaporation thickness of 5 nm; 3. Hole transport material is deposited on the hole injection layer to form a hole transport layer (HTL) with a deposition thickness of 40 nm; 4. An electron blocking layer (EBL) is deposited on top of the hole transport layer, with a deposition thickness of 5 nm; 5. An organic light-emitting layer is deposited on top of the electron blocking layer. The organic layer includes a host material and a light-emitting dye. The host material is CzSi, and the fluorescent dye is the fluorescent emitting material NICz prepared in Example 1. The doping amount of the light-emitting dye is 3wt%, and the deposition thickness is 20nm. 6. A hole blocking layer (HBL) is deposited on the organic light-emitting layer with a deposition thickness of 5 nm; 7. An electron transport layer (ETL) is formed by evaporating an electron transport material onto the hole blocking layer, with a evaporation thickness of 40 nm; 8. An electron injection layer LiF is formed by evaporating electron injection material on the electron transport layer, with a evaporation thickness of 1 nm; 9. An aluminum layer is deposited on top of the electron injection layer as the device cathode, with a deposition thickness of 80 nm.

[0087] The structure of the organic electroluminescent device fabricated in this embodiment is as follows: Figure 1 As shown, the specific structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / CzSi:3 wt% NICz(20nm) / HBL(5nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0088] Device Example 2 The difference from Device Example 1 is that the luminescent dye NICz in the organic light-emitting layer is replaced with the fluorescent emitting material DBF-NICz in Example 2. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / CzSi:3 wt% DBF-NICz(20nm) / HBL(5 nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0089] Device Example 3 The difference from Device Example 1 is that the luminescent dye NICz in the organic light-emitting layer is replaced with the fluorescent emitting material tPh-NICz in Example 3. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / CzSi:3 wt% tPh-NICz(20nm) / HBL(5 nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0090] Device Example 4 The preparation method differs from that of Device Example 1 in that the luminescent dye NICz used in the organic light-emitting layer is replaced with the fluorescent emitting material OEt-NICz from Example 4. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / CzSi:3 wt% OEt-NICz(20nm) / HBL(5 nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0091] Device Example 5 The preparation method differs from that of Device Example 1 in that the luminescent dye used in the organic light-emitting layer is replaced with the fluorescent emitting material of Example 5. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / CzSi:3 wt% SMe-NICz(20nm) / HBL(5 nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0092] Device Example 6 The preparation method differs from that of Device Example 1 in that the luminescent dye used in the organic light-emitting layer is replaced with the fluorescent emitting material of Example 6. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / CzSi:3 wt% PhCz-NICz(20nm) / HBL(5 nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0093] Device Example 7 The preparation method differs from that of Device Example 1 in that the luminescent dye used in the organic light-emitting layer is replaced with the material of Example 7. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / CzSi:3 wt% tCz-NICz(20nm) / HBL(5 nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0094] Device Example 8 The difference from Device Example 1 is that the luminescent dye NICz in the organic light-emitting layer is replaced with the fluorescent emitting material BF-NICz in Example 8. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / CzSi:3 wt% BF-NICz(20nm) / HBL(5nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0095] Device Example 9 The difference from Device Example 1 is that the luminescent dye NICz in the organic light-emitting layer is replaced with the fluorescent emitting material SF-NICz in Example 9. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / CzSi:3 wt% SF-NICz(20nm) / HBL(5nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0096] Device Example 10 The fabrication method differs from that in Device Example 6 in that the host material CzSi used in the organic light-emitting layer is replaced with DPEPO. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / DPEPO:3 wt% PhCz-NICz(20nm) / HBL(5 nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0097] Device Example 11 The fabrication method differs from that in Device Example 7 in that the host material CzSi used in the organic light-emitting layer is replaced with DPEPO. The specific device structure is as follows: ITO / HI (5 nm) / HTL (40 nm) / EBL (5 nm) / DPEPO:3 wt% tCz-NICz(20nm) / HBL(5 nm) / ETL (40 nm) / LiF (1 nm) / Al (80 nm).

[0098] Device Comparison Example 1 The difference from Device Example 1 is that the luminescent dye NICz in the organic light-emitting layer is replaced with the fluorescent emitting material in Comparative Example 1.

[0099] The structural formulas of the organic materials used in the above-mentioned device embodiments and device comparative examples are as follows:

[0100] When a DC voltage of 2V-12V is applied to the organic electroluminescent device prepared in the above device embodiment, the 1cd / m² is measured. 2 The performance parameters during emission are shown in Table 1. Detailed performance data (wavelength, full width at half maximum (FWHM), current efficiency (CE), external quantum efficiency (EQE), CIE color coordinates, etc.) of the organic electroluminescent devices fabricated in the above device embodiments are shown in Table 1.

[0101] Table 1. Summary of electroluminescent performance parameters of organic electroluminescent devices prepared in application examples

[0102] CE a Indicates current efficiency; CIE(x, y) b CIE under maximum EQE state x, y .

[0103] As can be seen from the data in the table above, compared to existing compounds that can only be used as the main material for OLED devices, the compounds of this invention belong to a novel class of multiple resonance narrow-spectrum fluorescent dyes. This invention utilizes nitrogen atoms... 2 Hybridization has the characteristic of electron withdrawal. By introducing two nitrogen atoms into the hybrid ICz framework through the meta-position strategy, the HOMO and LUMO of the fluorescent emitting material framework are localized on different atoms of the chemical bond, which enhances the resonance effect of the molecular framework and thus reduces the singlet-triplet band gap.

[0104] Furthermore, through peripheral substituent modification engineering, long-range charge transfer was introduced, which reduced the singlet-triple band gap and adjusted the singlet-triple band gap difference of the material to be less than 0.3 eV, thereby exciting the thermally activated delayed fluorescence feature of the material. The luminescence mainly comes from the NICz skeleton, and its rigid molecular skeleton ensures that the material has a narrow emission half-width.

[0105] The results above show that the electroluminescence spectrum of the device embodiment prepared using the fluorescent emitting material of this application has a narrow half-maximum width, confirming its effective multiple resonance effect. Compared with non-nitrogen-doped ICz luminescent materials in the prior art, the structure and device of this invention have a significant advantage in efficiency. Given its excellent luminous efficiency, color purity, and stability, the above-mentioned compound has good application prospects.

[0106] In summary, the fluorescent emitting material constructed by meta-doping two N atoms with indole-carbazole and introducing a long-range charge transfer strategy in this invention exhibits a narrow emission half-width, high color purity, and high efficiency. When applied to OLEDs, it improves luminous efficiency and device stability.

[0107] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A thermally activated delayed fluorescence emission material having the structure shown in Formula I or Formula II: Formula I Formula II in, Ring A is selected from any of the following structures: 、 、 、 、 、 ； Ring B is selected from any of the following structures: 、 ； Indicates the group linkage site; X, X1, and X2 may be the same or different, and each is independently selected from O, S, Se, CR7R8, S=O, SO2, and C=O; R1, R2, R3, R4, R5, R6, R7, and R8 may be the same or different, and each is independently selected from the structure shown in Formula 1 or Formula 2, or from the group consisting of: hydrogen, deuterium, halogen, cyano, nitro, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 alkylthio, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C2- C30 heterocyclic alkyl, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C1-C60 heteroaryl, substituted or unsubstituted C6-C60 arylamino, substituted or unsubstituted C3-C60 heteroarylamino, substituted or unsubstituted C6-C60 aryloxy, substituted or unsubstituted C3-C30 heteroaryloxy, substituted or unsubstituted C6-C30 arylthio, substituted or unsubstituted C3-C60 heteroarylthio; Formula 1 Formula 2 Indicates the group linkage site; The substituents described in R1, R2, R3, R4, R5, R6, R7, and R8 are each independently selected from deuterium, halogen, cyano, nitro, C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkylthio, C1-C20 alkylsilyl, C3-C20 cycloalkyl, C2-C20 heterocycloalkyl, C6-C30 aryl, C3-C30 heteroaryl, C6-C30 arylamino, C1-C30 heteroarylamino, C6-C30 aryloxy, C3-C30 heteroaryloxy, C6-C30 arylthio, and C3-C30 heteroarylthio. Optionally, R1, R2, R3, R4, R5, R6, R7, and R8 are not connected to their adjacent groups or are linked by chemical bonds to form a ring.

2. The thermally activated delayed fluorescence emission material according to claim 1, characterized in that, The thermally activated delayed fluorescence emission material has any of the following structures: Formula I-1 Formula I-2 Formula I-3 Formula I-4 Formula I-5 Formula I-6 Formula I-7 Formula I-8 Formula I-9 Formula II-1 The definitions of X, X1, X2, R1, R2, R3, R4, R5, and R6 are the same as those in Equation I and Equation II.

3. The thermally activated delayed fluorescence emission material according to claim 1 or 2, characterized in that, The thermally activated delayed fluorescence emission material has any of the following structures: Formula I-1-1 Formula I-2-1 Formula I-3-1 Formula I-4-1 Formula I-5-1 Formula I-6-1 Formula I-7-1 Formula I-8-1 Formula I-9-1 The definitions of X, X1, X2, R1, R2, R3, R4, R5, and R6 are the same as those in Formula I and Formula II. Preferably, X, X1, and X2 are selected from O and S.

4. The thermally activated delayed fluorescence emission material according to any one of claims 1-3, characterized in that, R1, R2, R3, R4, R5, and R6 may be the same or different, and each is independently selected from the structure shown in Formula 1 or Formula 2, or from the group consisting of: hydrogen, deuterium, F, Cl, Br, I, cyano, nitro, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 alkylthio, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C20 heterocycloalkyl, substituted or unsubstituted phenyl, substituted or unsubstituted diphenyl, substituted or unsubstituted triphenyl, substituted or unsubstituted tetraphenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted phenanthyl, substituted or unsubstituted triphenylene, substituted or unsubstituted anthracene, substituted or unsubstituted benzo[a]anthrayl. Substituted or unsubstituted pyrene, substituted or unsubstituted phenyl, substituted or unsubstituted peryl, substituted or unsubstituted fluoranyl, substituted or unsubstituted carbazolyl, substituted or unsubstituted fluorenyl, substituted or unsubstituted indolyl, substituted or unsubstituted quinolinyl, substituted or unsubstituted benzofuranyl, substituted or unsubstituted benzothiophenyl, substituted or unsubstituted thiophenyl, substituted or unsubstituted pyrroleyl, substituted or unsubstituted furanyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophenyl, substituted or unsubstituted benzimidazolyl, substituted or unsubstituted benzoxazolyl, substituted or unsubstituted diphenylamino, substituted or unsubstituted triphenylamino, substituted or unsubstituted phenazinyl, substituted or unsubstituted thiophenazinyl, substituted or unsubstituted acridineyl; Formula 1 Formula 2 Indicates the group linkage site; The substituents described in R1, R2, R3, R4, R5, and R6 are each independently selected from any one or a combination of at least two of the following: deuterium, F, Cl, Br, I, cyano, nitro, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylthio, C6-C20 aryl, C1-C20 heteroaryl, C6-C20 arylamino, C1-C20 heteroarylamino, C6-C20 aryloxy, C6-C20 heteroaryloxy, C6-C20 arylthio, and C3-C20 heteroarylthio. Optionally, R1, R2, R3, R4, R5, and R6 are not connected to their adjacent groups or are linked by chemical bonds to form a ring; Preferably, R1 and R2 are the same, and R4 and R5 are the same; and / or R7 and R8 are each independently selected from C1-C10 alkyl groups, preferably C1-C5 straight-chain alkyl groups.

5. The thermally activated delayed fluorescence emission material according to any one of claims 1-4, characterized in that, R1, R2, R3, R4, R5, and R6 are each independently selected from the group consisting of hydrogen, deuterium, F, Br, CF3, CN, or the following groups: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 6. The thermally activated delayed fluorescence emission material according to any one of claims 1-5, characterized in that, R1 is selected from the group consisting of hydrogen, deuterium, F, Br, CF3, CN, or the following groups: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 7. The thermally activated delayed fluorescence emission material according to any one of claims 1-6, characterized in that, R2 is selected from the group consisting of hydrogen, deuterium, F, Br, CF3, CN, or the following groups: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 8. The thermally activated delayed fluorescence emission material according to any one of claims 1-7, characterized in that, R3 is selected from the group consisting of hydrogen, deuterium, F, CF3, CN, or the following groups: 、 、 、 、 、 、 、 、 、 。 9. The thermally activated delayed fluorescence emission material according to any one of claims 1-8, characterized in that, The thermally activated delayed fluorescence emission material is selected from any of the following structures: 。 10. An organic electroluminescent device, comprising ITO conductive glass, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, and a cathode, wherein the light-emitting layer comprises the thermally activated delayed fluorescence emission material according to any one of claims 1-9; Preferably, the organic electroluminescent device emits blue, green, and red light.

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