Thermally activated delayed fluorescent material based on organic boron as well as preparation method and application of thermally activated delayed fluorescent material

Abstract

The invention provides a thermally activated delayed fluorescent material based on organic boron as shown in a formula (I) and a preparation method and application thereof. The material can be applied to the field of electroluminescence and can emit near ultraviolet light and visible light. The electroluminescent device prepared from the organic boron-based thermally activated delayed fluorescent material has excellent performance, stable light emitting color, good color purity, narrow emission spectrum, high device efficiency and good stability. # imgabs0 #

Description

Technical Field

[0001] The present invention specifically relates to a thermally activated delayed fluorescence material based on organic boron, its preparation method and application, belonging to the technical field of organic optoelectronic material applications. Background Art

[0002] After nearly 40 years of rapid development, organic light-emitting diodes (OLEDs) have been successfully applied to displays such as mobile phones, computers, and televisions, truly entering our lives. However, you must have noticed a problem, that is, we always need to charge our mobile phones and computers at various times. Therefore, with the increasingly better living needs of the people, a better screen is worthy of our continued pursuit. We need the screens we use to have lower energy consumption, higher brightness, longer lifespan, purer colors, and faster response.

[0003] In the initial stage, the two research topics of how to realize the generation and utilization of excitons and improve the injection and transport of carriers have always run through the development process of OLEDs. In addition to traditional fluorescence, currently industrialized noble metal phosphorescence, as well as emerging thermally activated delayed fluorescence (TADF), "hot excitons", and singlet fission materials can theoretically achieve 100% internal quantum efficiency, providing new development directions for low-cost and high-efficiency OLEDs. Among them, TADF materials have low cost and strong modifiability. In just over a decade, their efficiency and stability in green and red light have been comparable to or even surpassed commercial phosphorescent materials and have been gradually applied to display products. However, since the current traditional method for designing TADF mainly realizes the effective separation of the highest occupied molecular orbital and the lowest unoccupied molecular orbital by introducing donor (D) and acceptor (A) units with a large twist angle to obtain a small ΔE st , but a large twist angle often reduces the fluorescence quantum yield (PLQY), promotes the relaxation of the excited state structure, resulting in a relatively wide emission band (>70 nm), which cannot meet the requirements of future high-definition displays. On the other hand, using a conjugated structure to connect the donor and acceptor often leads to a large degree of delocalization of the electron cloud, which is likely to cause a red shift of the emission spectrum and is not conducive to achieving blue light emission. Although in recent years, multiple resonance (MR)-TADF materials have shown the advantages of narrow-band emission (<40 nm) and high efficiency due to their rigid skeletons and unique short-range charge transfer characteristics, the reverse intersystem crossing (RISC) process of such materials is usually relatively slow, resulting in a serious efficiency roll-off of the fabricated devices at high brightness, which is not conducive to the practical application of the devices.

[0004] Combining the design strategies of traditional TADF and MR-TADF, introducing a through-space charge transfer (TSCT) unit into a rigid resonance skeleton can effectively separate the molecular frontier orbitals in space and significantly reduce ΔE st, thus improving the RISC rate. In addition, its electron transfer is achieved through π-π interactions between donors and acceptors, which can simultaneously alleviate the aggregation-induced quenching (ACQ) and efficiency roll-off problems in the device. It is expected to achieve efficient and stable narrow-band blue TADF materials. SUMMARY OF THE INVENTION

[0005] In view of the above technical problems, the present invention provides a compound represented by formula (I):

[0006]

[0007] Wherein: R1 and R2 are the same or different and are independently selected from H, CN, unsubstituted, or optionally substituted by one, two or more Ra, the following groups: C 1-12 alkyl, C 1-12 alkoxy, C 6-20 aryl, 5-25 membered heteroaryl, -N-(C 6-20 aryl)2, -N-(5-25 membered heteroaryl)2, or a spiro ring formed by a 5-25 membered heteroaryl and C 6-20 aryl sharing a carbon atom;

[0008] Ra is selected from the following groups: cyano, C 1-12 alkyl, C 1-12 alkoxy, C 6-20 aryl, 5-25 membered heteroaryl, -N-(C 6-20 aryl)2 or -N-(5-25 membered heteroaryl)2;

[0009] m and n are the same or different and are independently 1, 2 or 3;

[0010] The Ra is further optionally substituted by one, two or more C 6-20 aryl;

[0011] Y is selected from any one of a chemical bond, -O-, -S-, -Se-, -Te-, -C(D1D2)-, -N(D3)-, -C(O)-, -S(=O)2-, -Si(D1D2)-, -P(D3)-, -P(=O)(D3)- or -B(D3)-;

[0012] G1, G2, D1, D2, D3 are the same or different and are independently selected from hydrogen, deuterium, halogen, nitrile, nitro, hydroxyl, =O, aldehyde, unsubstituted or optionally substituted by one, two or more Rb, the following groups: C 1-12 alkyl, -COC 1-12 alkyl, -COOC 1-12 alkyl, -CONHC 1-12 alkyl, C 3-20 cycloalkyl, C1-12 Alkoxy, C 6-20 Aryloxy, C 1-12 Alkylthio, C 6-20 Arylthio, C 1-12 Alkylsulfonyl, C 6-20 Arylsulfonyl, C 2-12 Alkenyl, -Si(C 1-12 alkyl)3, -Si(C 6-20 aryl)3, -Si(5 - 25 - membered heteroaryl)3, -B(C 1-12 alkyl)2, -B(C 6-20 aryl)2, -B(5 - 25 - membered heteroaryl)2, NH2, -P(C 6-20 aryl)3, Phosphoryloxy (P = O), C 6-20 Aryl, 5 - 25 - membered heteroaryl, 3 - 20 - membered heterocyclic group, a spiro ring formed by a 13 - 20 - membered fused cycloalkenyl and a 3 - 20 - membered heterocyclic group sharing a carbon atom; or a group as shown below:

[0013]

[0014]

[0015] Wherein: Y1, Y2, Y3 and Y4 are the same or different and are independently selected from -C(=O), -O-, -S, -Se- or -Te-;

[0016] D3, D4, D5, D6, D7, D8, D9, D 10 , D 11 , D 12 , D 13 , D 14 , D 15 , D 16 , D 17 , D 18 are the same or different and are independently selected from H, halogen, C 1-12 alkyl, halo - C 1-12 alkyl, C 1-12 alkoxy, C 6-20 aryl, 5 - 25 - membered heteroaryl, C 1-6 alkyl - substituted 5 - 25 - membered heteroaryl, -N-(5 - 25 - membered heteroaryl)2, -N-(C 6-20 aryl)2 or C 6-14 aryl - substituted 5 - 14 - membered heteroaryl;

[0017] Rb is selected from =O, halogen, cyano, nitro, hydroxy, aldehyde, C 1-12 alkyl, -COC 1-12 alkyl, -COOC 1-12 alkyl, C3-20 cycloalkyl, C 1-12 alkoxy, C 6-20 aryl, 5 - 25 - membered heteroaryl;

[0018] Ph represents a substituent selected from the following groups which are unsubstituted or optionally substituted by one, two or more Ri: C 6-20 aryl, 5 - 25 - membered heteroaryl;

[0019] Ri is selected from C 1-12 alkyl;

[0020] B linked to the substituent Ph is a boron atom.

[0021] According to an embodiment of the present invention, the structure shown in formula (I) is selected from the following structures:

[0022]

[0023] Among them, in formula I - A, Y is a chemical bond;

[0024] In formula I - B, Y is not a chemical bond and is selected from any one of - O -, - S -, - Se -, - Te -, - C(D1D2)-, - N(D3)-, - C(O)-, - S(=O)2-, - Si(D1D2)-, - P(D3)-, - P(=O)(D3)- or - B(D3)-;

[0025] R1, R2, G1, G2, Ph, D1, D2, D3 have the definitions as described above.

[0026] According to an embodiment of the present invention, said R1 and R2 are the same or different and are independently selected from H, CN, C 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl, 5 - 14 - membered heteroaryl, C 1-6 alkyl - substituted 5 - 14 - membered heteroaryl, - N - (5 - 14 - membered heteroaryl)2, - N - (C 1-6 alkyl - substituted C 6-14 aryl)2 or C 6-14 aryl - substituted 5 - 14 - membered heteroaryl;

[0027] According to an embodiment of the present invention, Ph is selected from the following groups which are unsubstituted or optionally substituted by one, two or more Ri: C 6-14 aryl, 5 - 14 - membered heteroaryl; Ri is selected from C 1-6 alkyl.

[0028] According to an embodiment of the present invention, Y is selected from any one of a chemical bond, -O-, -S-, -Se-, -Te-, -C(D1D2)-, -N(D3)-, -C(O)-, -S(=O)2-, -Si(D1D2)-, -P(D3)-, -P(=O)(D3)-, or -B(D3)-;

[0029] G1, G2, D1, D2, D3 are the same or different and are independently selected from H, C 1-6 alkyl, C 1-6 alkoxy, a group as follows that is unsubstituted or optionally substituted by one, two or more Rb: C 3-20 cycloalkyl, a 3-20 membered heterocyclic group, C 6-20 aryl, a 5-25 membered heteroaryl, a spiro ring formed by a 13-20 membered condensed cycloalkenyl and a 3-20 membered heterocyclic group sharing a carbon atom, -N-(C 6-20 aryl)2, -N-(a 5-25 membered heteroaryl)2; or a group as shown below:

[0030]

[0031] wherein: Y1, Y2, Y3, and Y4 are the same or different and are independently selected from -C(=O), -O-, -S, -Se-, or -Te-;

[0032] D3, D4, D5, D6, D7, D8, D9, D 10 , D 11 , D 12 , D 13 , D 14 , D 15 , D 16 , D 17 , D 18 are the same or different and are independently selected from H, halogen, C 1-12 alkyl, halo C 1-12 alkyl, C 1-12 alkoxy, C 6-14 aryl, a 5-14 membered heteroaryl, C 1-6 alkyl-substituted 5-14 membered heteroaryl, -N-(a 5-14 membered heteroaryl)2, -N-(C 6-14 aryl)2, or C 6-14 aryl-substituted 5-14 membered heteroaryl;

[0033] Rb is selected from =O, halogen, cyano, nitro, hydroxy, aldehyde, C 1-12 alkyl, C 3-20 cycloalkyl, -COC 1-12 alkyl, -COOC 1-12 alkyl, C 1-12 alkoxy, C6-14 aryl, 5- to 14-membered heteroaryl, -N-(C 6-14 aryl)2 or -N-(5- to 14-membered heteroaryl)2.

[0034] According to an embodiment of the present invention, G1 and G2 are the same or different and are independently selected from H, C 1-6 alkyl, unsubstituted, and the following groups optionally substituted with one, two or more Rb: C 6-14 aryl, 5- to 22-membered heteroaryl, -N-(C 6-14 aryl)2, -N-(5- to 14-membered heteroaryl)2, a spiro ring formed by a 13- to 20-membered fused cycloalkenyl and a 3- to 20-membered heterocyclic group sharing a carbon atom; or a group as shown below:

[0035]

[0036] wherein: Y1, Y2, Y3 and Y4 are the same or different and are independently selected from -C(=O), -O-, -S, -Se- or -Te-;

[0037] D3, D4, D5, D6, D7, D8, D9, D 10 , D 11 , D 12 , D 13 , D 14 , D 15 , D 16 , D 17 , D 18 are the same or different and are independently selected from H, halogen, C 1-6 alkyl, halo C 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl, 5- to 22-membered heteroaryl, C 1-6 alkyl-substituted 5- to 25-membered heteroaryl, -N-(5- to 14-membered heteroaryl)2, -N-(C 6-14 aryl)2 or C 6-14 aryl-substituted 5- to 14-membered heteroaryl;

[0038] Rb is selected from the following groups: cyano, C 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl, 5- to 14-membered heteroaryl, -N-(C 6-14 aryl)2 or -N-(5- to 14-membered heteroaryl)2.

[0039] According to an embodiment of the present invention, Y is a chemical bond, any one of -O-, -S-, -Se-, -Te-, -C(D1D2)-, -N(D3)-, -C(O)-, -S(=O)2-, -Si(D1D2)-, -P(D3)-, -P(=O)(D3)- or -B(D3)-;

[0040] D1, D2, D3 are the same or different and are independently selected from H, C 1-6 alkyl, unsubstituted or optionally substituted by one, two or more Rb, selected from the following groups: C 6-14 aryl, 5-22 membered heteroaryl; or the following groups:

[0041]

[0042] wherein: Y1, Y2, Y3 and Y4 are the same or different and are independently selected from -O-, -S-, -Se-, -Te- or -C(=O)-;

[0043] D3, D4, D5, D6, D7, D8, D9, D 10 、D 11 、D 12 、D 13 、D 14 、D 15 、D 16 、D 17 、D 18 are the same or different and are independently selected from H, halogen, C 1-12 alkyl, halo C 1-12 alkyl, C 1-12 alkoxy, C 6-14 aryl, 5-14 membered heteroaryl, C 1-6 alkyl-substituted 5-25 membered heteroaryl, -N-(5-25 membered heteroaryl)2, -N-(C 6-20 aryl)2 or C 6-14 aryl-substituted 5-14 membered heteroaryl;

[0044] wherein, Rb is selected from C 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl or 5-14 membered heteroaryl.

[0045] According to an embodiment of the present invention, R1 and R2 are the same and are selected from H;

[0046] Preferably, Y is a chemical bond, -O-, -S-, -Se-, -Te-, -C(D1D2)-, -N(D3)-; wherein, D1 and D2 are selected from methyl or ethyl;

[0047] D3 is selected from methyl, ethyl, isopropyl, tert-butyl,

[0048] Preferably, G1 and G2 are the same or different and are independently selected from H or the following groups:

[0049]

[0050]

[0051] Preferably, Ph is selected from the structures shown below:

[0052]

[0053] In some specific embodiments of the present invention, the compound represented by formula (I) is selected from one of the following structures:

[0054]

[0055]

[0056]

[0057] According to the embodiments of the present invention, the compound represented by formula (I) is a thermally activated delayed fluorescence material. The present invention also provides a method for preparing the compound represented by formula (I) as described above, including the following steps:

[0058]

[0059] Compound Ia reacts with compound Ph-L to obtain the compound represented by formula (I);

[0060] Wherein, Y, R1, R2, m, n, G1, G2 and Ph are as defined above; L is a leaving group, such as methyl borate.

[0061] The present invention also provides the use of the compound represented by formula (I) as described above as a thermally activated delayed fluorescence material in the preparation of organic electronic devices, preferably in the preparation of organic electroluminescent devices.

[0062] According to the embodiments of the present invention, the transfer thermally activated delayed fluorescence material has photoluminescence or electroluminescence properties and can emit near-ultraviolet light and visible light. Preferably, the compound is a thermally activated delayed fluorescence material.

[0063] The present invention also provides an organic electroluminescent device, which includes two electrodes and an organic layer located between the electrodes, and the organic layer includes the compound represented by formula (I) as described above.

[0064] Preferably, the organic layer includes an injection layer, a transport layer, a light-emitting layer, and a blocking layer.

[0065] Preferably, the compound represented by the formula (I) is located in the light-emitting layer as a thermally activated delayed fluorescence material.

[0066] The present invention also provides a method for preparing the organic electroluminescent device, which includes the following steps: sequentially disposing an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode on a substrate.

[0067] Preferably, the anode, the hole injection layer, the hole transport layer, the electron blocking layer, the light-emitting layer, the hole blocking layer, the electron transport layer, the electron injection layer, and the cathode are disposed by evaporation, spin coating, or inkjet printing, for example, by evaporation.

[0068] More preferably, the evaporation is carried out under a vacuum condition. For example, when evaporating an organic material, it is carried out under a vacuum degree lower than 2×10 -5 Pa. Further preferably, the evaporation rate and thickness of each functional layer are precisely controlled by a quartz crystal film thickness detector.

[0069] Beneficial effects

[0070] 1. The present invention provides a class of organic boron-based transfer thermally activated delayed fluorescence materials, which can be applied to the field of electroluminescence and can emit near-ultraviolet light and visible light.

[0071] 2. When using the compound provided by the present invention to prepare the light-emitting layer in an electroluminescent device, the obtained electroluminescent device has good device performance, and its specific advantages are as follows:

[0072] (1) In the present invention, by introducing donor-acceptor units to the ortho-position of the organic boron-based rigid skeleton, through theoretical calculation and analysis, it is obtained that the highest occupied molecular orbital (HOMO) is mainly distributed on the donor, and the lowest unoccupied molecular orbital (LUMO) is mainly distributed on the organic boron-based rigid skeleton. A relatively large torsional angle is formed between the two, and the overlap between the HOMO and LUMO orbitals is very small, which can effectively separate the molecular frontier orbitals in space and significantly reduce ΔE st, thereby enhancing the reverse intersystem crossing (RISC) rate. In addition, a small part of the HOMO orbitals is also distributed on the benzene ring opposite to the donor, indicating the existence of through-space charge transfer (TSCT) in the molecule. At the same time, the organic boron-based unit has high molecular rigidity, which is beneficial to suppressing intra- and intermolecular vibrational and rotational relaxations, thereby improving the luminescence efficiency and still maintaining its narrow-band emission characteristics, realizing the complementary advantages of both. From the perspective of molecular structure, the planar organic boron unit can ensure the thermal stability of the molecule, effectively suppress the deformation of the molecule in the excited state while suppressing non-radiative deactivation, thereby improving the photoluminescence quantum yield (PLQY) of the material. However, planar molecules usually have serious aggregation-caused quenching (ACQ) problems in the solid state. The electron transfer of the thermally activated delayed fluorescence based on organic boron TSCT is achieved through the π-π interaction between the donor and acceptor, which is beneficial to the radiative transition of the excited state and at the same time suppresses the non-radiative transition caused by ACQ, alleviating the problem of device efficiency roll-off.

[0073] (2) The electroluminescent device prepared using the organic boron-based thermally activated delayed fluorescence material of the present invention has excellent performance [stable emission color (the emission spectrum is stable under different driving voltages, as shown in the appendix Figure 9 ), good color purity, i.e., narrow emission spectrum, high device efficiency, and good stability].

[0074] (3) The preparation process of the organic boron-based thermally activated delayed fluorescence material of the present invention is simple, and the raw materials used in the synthesis are cheap and easily available. Such materials have good application effects in electroluminescent devices and have industrialization and commercialization prospects.

[0075] Term Definition and Explanation

[0076] Among some substituents is the connection site.

[0077] The term "halogen" refers to F, Cl, Br, and I. In other words, F, Cl, Br, and I can be described as "halogen" in this specification.

[0078] The term "C 1-12 alkyl" should be understood to represent a straight-chain or branched-chain saturated monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably C 1-10 alkyl. "C 1-10"Alkyl" should be understood to represent a straight-chain or branched-chain saturated monovalent hydrocarbon group having 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms. The alkyl groups are, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl, etc. or their isomers. In particular, the group has 1, 2, 3, 4, 5, 6 carbon atoms ("C 1-6 alkyl"), such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl, sec-butyl, tert-butyl, and more particularly, the group has 1, 2 or 3 carbon atoms ("C 1-3 alkyl"), such as methyl, ethyl, n-propyl or isopropyl.

[0079] The term "C 6-20 aryl" should be understood to represent a monovalent aromatic or partially aromatic monocyclic, bicyclic or tricyclic hydrocarbon ring having 6 to 20 carbon atoms, preferably "C 6-14 aryl". The term "C 6-14 aryl" should be understood to represent a monovalent aromatic or partially aromatic monocyclic, bicyclic or tricyclic hydrocarbon ring having 6, 7, 8, 9, 10, 11, 12, 13 or 14 carbon atoms ("C 6-14 aryl"), especially a ring having 6 carbon atoms ("C6 aryl"), such as phenyl; or biphenyl, or a ring having 9 carbon atoms ("C9 aryl"), such as indanyl or indenyl, or a ring having 10 carbon atoms ("C 10 aryl"), such as tetrahydronaphthyl, dihydronaphthyl or naphthyl, or a ring having 13 carbon atoms ("C 13 aryl"), such as fluorenyl, or a ring having 14 carbon atoms ("C 14 aryl"), such as anthryl.

[0080] The term "5-25 membered heteroaryl" should be understood to include monovalent monocyclic, bicyclic or tricyclic aromatic ring systems having 5 to 25 ring atoms and containing 1-5 heteroatoms independently selected from N, O and S, preferably "5-20 membered heteroaryl" or "5-14 membered heteroaryl". The term "5-14 membered heteroaryl" should be understood to include monovalent monocyclic, bicyclic or tricyclic aromatic ring systems having 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14 ring atoms, especially 5 or 6 or 9 or 10 carbon atoms, and containing 1-5, preferably 1-3 heteroatoms independently selected from N, O and S. And, in each case, it may additionally be benzo-fused. In particular, heteroaryl is selected from thienyl, furyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, thieno-4H-pyrazolyl, etc. and their benzo derivatives, such as benzofuryl, benzothienyl, benzoxazolyl, benzisoxazolyl, benzimidazolyl, benzotriazolyl, indazolyl, indolyl, isoindolyl, etc.; or pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, etc., and their benzo derivatives, such as quinolinyl, quinazolinyl, isoquinolinyl, etc.; or azocinyl, indolizinyl, purinyl, etc. and their benzo derivatives; or cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, naphthyridinyl, pteridinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl, etc.

[0081] The term "C 3-20 cycloalkyl" should be understood to denote a saturated monovalent monocyclic, bicyclic hydrocarbon ring or polycyclic hydrocarbon ring (also called a fused hydrocarbon ring) having 3-20 carbon atoms. Bicyclic or polycyclic cycloalkyls include spirocycloalkyls, bridged cycloalkyls, spirocycloalkyls; the spirocyclic is a fused ring structure formed by two or more cyclic structures sharing two adjacent ring atoms (i.e., sharing a bond) with each other. The bridged cycloalkyl is a fused ring structure formed by two or more ring structures sharing two non-adjacent ring atoms with each other. The spirocyclic is a fused ring structure formed by two or more cyclic structures sharing one ring atom with each other. For example, the C 3-20 cycloalkyl can be a C 3-8 monocyclic cycloalkyl, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, or a C 7-12 spirocycloalkyl, such as decahydronaphthalene ring; it can also be a C 7-12 bridged cycloalkyl, such as norbornane, adamantane, bicyclo[2,2,2]octane.

[0082] The term "3-20 membered heterocyclic group" means a saturated or unsaturated monovalent monocyclic, bicyclic or tricyclic hydrocarbon ring containing 1-5 heteroatoms independently selected from N, O and S, preferably "3-10 membered heterocyclic group". The term "3-10 membered heterocyclic group" means a saturated or unsaturated monovalent monocyclic, bicyclic or tricyclic hydrocarbon ring containing 1-5, preferably 1-3 heteroatoms selected from N, O and S. The heterocyclic group may be linked to the rest of the molecule through any one of the carbon atoms or a nitrogen atom (if present) of said carbon atoms. In particular, the heterocyclic group may include but is not limited to: 4-membered rings such as azetidinyl, oxetanyl; 5-membered rings such as tetrahydrofuranyl, dioxolanyl, pyrrolidinyl, imidazolidinyl, pyrazolidinyl, pyrroline; or 6-membered rings such as tetrahydropyranyl, piperidinyl, morpholinyl, dithianyl, thiomorpholinyl, piperazinyl or trithianyl; or 7-membered rings such as diazepanyl, diazepene. Optionally, the heterocyclic group may be a fused ring, bridged ring or spiro ring. The heterocyclic group may be bicyclic, for example but not limited to hexahydropyrrolo[1,2-a]pyrazin-2(1H)-yl. The ring containing a nitrogen atom may be partially unsaturated, i.e. it may contain one, two or more double bonds, such as but not limited to 2,5-dihydro-1H-pyrrolyl, 4H-[1,3,4]thiadiazinyl, 4,5-dihydrooxazolyl or 4H-[1,4]thiazinyl, 5H,6H,8H-[1,2,4]triazolo[4,3-a]pyrazinyl, or alternatively, it may be benzo-fused, such as but not limited to dihydroisoquinolinyl, 1,3-benzoxazolyl, 1,3-benzodioxolyl. The "3-20 membered heterocyclic group" may also be a bicyclic or tricyclic fused ring formed by 1 or 2 benzene rings and a 5-6 membered ring containing 1-2 heteroatoms through sharing 2 or 4 carbon atoms, such as 9,10-dihydroacridine.

[0083] The term "13-20 membered fused cycloalkenyl" means an unsaturated bicyclic or tricyclic hydrocarbon ring containing 13-20 ring atoms. For example, it is a fused ring formed by phenyl, a 5-6 membered saturated cycloalkyl and phenyl through sharing 2 carbon atoms respectively. For example, it is fluorene.

[0084] Unless otherwise specified, the heterocyclic group, heteroaryl or heteroarylene includes all its possible isomeric forms, such as its position isomers. Thus, for some illustrative non-limiting examples, pyridyl or pyridinylene includes pyridin-2-yl, pyridin-2-ylidene, pyridin-3-yl, pyridin-3-ylidene, pyridin-4-yl and pyridin-4-ylidene; thienyl or thienylene includes thien-2-yl, thien-2-ylidene, thien-3-yl and thien-3-ylidene.

[0085] The above definition of the term "C 1-12 alkyl" also applies to those containing "C1-12 Other terms for "alkyl", such as the term "C" 1-12 alkoxy", "halo C" 1-12 alkyl", etc. Description of the Drawings

[0086] Figure 1 This is the single crystal structure of Compounds 1-11 and 1-18 in Examples 6 and 8 of the present invention. The torsion angles of the donor group relative to the molecular nitrogen-containing backbone reach 89.86° and 88.2° respectively, approaching 90°. Such large torsion angles may bring a smaller ΔE to the material ST and thus lead to an improvement in TADF performance.

[0087] Figure 2 This is the calculation results of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of Compounds 1-11 and 1-18 in Examples 6 and 8 of the present invention. Theoretical calculation and analysis show that HOMO is mainly distributed on the donor, and LUMO is mainly distributed on the rigid backbone containing organoboron. A relatively large torsion angle is formed between the two, and the overlap between the HOMO and LUMO orbitals is very small, which can effectively separate the molecular frontier orbitals in space and can significantly reduce ΔE st and thus improve the RISC rate.

[0088] Figure 3 This is the thermogravimetric test curve of Compounds 1-11 and 1-18 in Examples 6 and 8 of the present invention. The decomposition temperature of Compound 1-11 is 435 °C, and the decomposition temperature of Compound 1-18 is 410 °C. Both compounds have good thermal stability, which is helpful for the thermal evaporation preparation of OLEDs.

[0089] Figure 4 This is the ultraviolet-visible absorption and photoluminescence spectra of Compounds 1-11 and 1-18 of the present invention in toluene solution. Both of them have a strong absorption peak at 300 nm, and this peak should be attributed to the π to π * transition, while the relatively broad absorption peak at about 400 nm is attributed to the intramolecular charge transfer from the donor to the nitrogen-containing heteroboron. The emission peak of Compound 1-18 is at 432 nm (deep blue light), and the full width at half maximum (FWHM) is 52 nm; while the electron-donating ability of 3,6-ditert-butylcarbazole relative to carbazole is enhanced, and the emission peak of Compound 1-11 is at 450 nm (pure blue light), and the FWHM is 50 nm.

[0090] Figure 5 This is the photoluminescence spectrum of the thin film prepared by using Compounds 1-11 and 1-18 in Examples 6 and 8 of the present invention as the guest luminescent material, the host material is DPEPO, and the doping concentration is 10 wt%. The emission peaks of the two are located at 459 nm (pure blue light) and 442 nm (deep blue light) respectively.

[0091] Figure 6 The current density-voltage-luminance (I-V-L) curve of the organic light-emitting device (OLED-6) containing Compound 1-11 prepared in Example 6 of the present invention. It can be seen from the curve analysis that the blue electro-luminescent device corresponding to Compound 1-11 prepared in Example 6 has a relatively low turn-on voltage (3.2 V) and a relatively high luminance (greater than 3000 nits).

[0092] Figure 7 The current efficiency and power efficiency-luminance curves of the organic light-emitting device (OLED-6) containing Compound 1-11 prepared in Example 6 of the present invention. It can be seen from the curve analysis that the light-emitting efficiencies of the electro-luminescent devices containing Compound 1-11 prepared in Example 6 are all relatively high.

[0093] Figure 8 The external quantum efficiency (EQE)-luminance curve of the organic light-emitting device (OLED-6) containing Compound 1-11 prepared in Example 6 of the present invention. It can be seen from the curve analysis that the maximum EQE of the electro-luminescent device corresponding to the compound prepared in Example 6 is relatively high, and the efficiency roll-off at 1000 nits is relatively small.

[0094] Figure 9 The electroluminescence spectra of the device (OLED-6) prepared with Compound 1-11 synthesized in Example 6 of the present invention as the guest luminescent material, DPEPO as the host material, and a doping concentration of 20 wt%. The excellent spectral stability indicates that excitons mainly recombine in the light-emitting layer. In addition, the device prepared based on Compound 1-11 can achieve deep blue light emission and a narrow emission band, and the CIE y value is less than 0.089, meeting the color gamut standard of the National Television Standards Committee (NTSC).

[0095] Figure 10 The structural diagram of the organic light-emitting device fabricated using the compound of the present invention.

[0096] Among them, 1 - transparent glass substrate, 2 - anode, 3 - hole injection layer, 4 - hole transport layer, 5 - electron blocking layer, 6 - light-emitting layer, 7 - hole blocking layer, 8 - electron transport layer, 9 - electron injection layer, 10 - cathode. Detailed Embodiments

[0097] The technical solutions of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only for illustrative and explanatory purposes of the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope intended to be protected by the present invention.

[0098] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

[0099] Synthesis of Compound 1-23 in Example 1

[0100] [Synthesis of Compound P1]

[0101]

[0102] Take 2-bromo-3-fluoroaniline (5 g, 26.3 mmol), tris(dibenzylideneacetone)dipalladium (602 mg, 0.658 mmol), 1,1'-bis(diphenylphosphino)ferrocene (729.02 mg, 1.31 mmol), and sodium tert-butoxide (3.54 g, 36.82 mmol) in a 100 mL Schlenk reaction tube. Add 30 mL of toluene as the reaction solvent to dissolve the above reactants, and then add o-bromoiodobenzene (3.95 mL, 31.56 mmol). Purge with nitrogen three times. The reaction time is 18 hours, and the reaction is refluxed at 110 °C. After the reaction is completed, extract and separate using dichloromethane / saturated brine. After extracting the organic layer liquid three times, dry it with anhydrous sodium sulfate, and then remove the organic solvent by rotary evaporator. The crude product is separated and purified by silica gel column chromatography (the eluting solvent is petroleum ether), and after rotary evaporation to dryness, the product (18.32 g, 24 mmol) is obtained as a white powder.

[0103] MS(EI): m / z 344.8987[M + ; Combustion elemental analysis: C 12 H8Br2FN (%) Calculated: C, 41.78; H, 2.34; Br, 46.32; F, 5.51; N, 4.06; Found: C, 41.79; H, 2.36; N, 4.08.

[0104] [Synthesis of Compound P2]

[0105]

[0106] 4-tert-Butylphenol (15 g, 100 mmol), 2-bromo-1,3-difluoro-5-iodobenzene (11.7 g, 36.6 mmol), and potassium carbonate (15 g, 110 mmol) were added to a dried reaction flask, and dry N,N-dimethylformamide (45 mL) was injected to dissolve them thoroughly. The mixture was evacuated and filled with argon three times. The temperature was raised to 170 °C, and the reaction was refluxed for 12 h. After the reaction was completed, it was cooled to room temperature. The mixture was diluted with toluene and poured into water. The toluene layer was extracted three times, collected, and dried over anhydrous sodium sulfate. After removing toluene by rotary evaporation, the crude product was separated and purified by silica gel column chromatography to obtain white powder Q2 (29.5 g).

[0107] Reactant Q2 (600 mg, 1.05 mmol) was placed in a dry reaction flask equipped with a condenser. The flask was evacuated and filled with argon more than three times, and then 5 mL of dry toluene was added to dissolve it. After the reaction system was cooled to -78 °C and stabilized for a period of time (about half an hour), a solution of n-butyllithium (1.6 M, 0.69 mL, 1.10 mmol) was added dropwise, and the reaction was carried out for 10 minutes. Subsequently, boron tribromide (0.12 mL, 1.26 mmol) was added dropwise at -78 °C, and the reaction was carried out at 0 °C for 1 h. After the reaction system was cooled to -30 °C again, N,N-diisopropylethylamine (0.40 mL, 2.10 mmol) was added dropwise, and the temperature was raised to 110 °C, and the reaction was carried out for 12 h. After cooling to room temperature, the reaction solution was diluted with toluene, extracted, the organic phase was separated, dried over anhydrous sodium sulfate, the solvent was removed, and the crude product was separated and purified by silica gel column chromatography to obtain white powder P2 (482 mg).

[0108] MS(EI): m / z 508.1071[M + ; Combustion elemental analysis: C 26 H 26 Calculated values for C, H, B, I, O in BIO2(%) are: C, 61.45; H, 5.16; B, 2.13; I, 24.97; O, 6.30; Found values are: C, 61.48; H, 5.15; O, 6.33.

[0109] [Synthesis of Compound P3]

[0110]

[0111] Take the product P1 (18.32 g, 24 mmol) and NaH (60% dispersed in kerosene) 532.48 mg (13.31 mmol) in a 100 mL Schlenk reaction tube. Cool the reaction tube to 0 °C outside the reaction tube by using ice cubes and ice-saturated brine. After evacuating and replacing with nitrogen three times, add the reaction solvent (anhydrous tetrahydrofuran). After activating the reaction at this temperature for half an hour, add P2 (19.5 g, 38.4 mmol), and then warm the reaction tube to room temperature and react for three hours. Use dichloromethane / saturated brine for extraction and separation. After extracting the organic layer liquid three times, dry it with anhydrous sodium sulfate, and then rotary evaporate the organic solvent to obtain the white solid product P3 (17.06 g, 23.52 mmol).

[0112] MS(EI): m / z 725.0935[M + ; Combustion elemental analysis: C 38 H 33 BBr2FNO2(%) Calculated value: C, 62.93; H, 4.59; B, 1.49; Br, 22.03; F, 2.62; N, 1.93; O, 4.41; Measured value: C, 62.95; H, 4.56; N, 1.95; O, 4.43.

[0113] [Synthesis of Compound P4]

[0114]

[0115] Take 3,6 - di - tert - butylcarbazole (28.22 mmol) in a Schlenk reaction tube, then add 1.69 g (42.34 mmol) of NaH (60% dispersed in kerosene). Use DMF as the solvent. After evacuating and replacing with nitrogen three times, stir at room temperature for half an hour. Take the product P3 (25 mmol) and add it to the reaction tube. Raise the reaction temperature to 150 °C and reflux for 12 hours. After the reaction is completed, add water to the reaction system to obtain a white suspension, and then further carry out suction filtration. The solid obtained by filtration is extracted with dichloromethane / saturated brine and then rotary evaporated to dryness to obtain the white solid product P4 (20 mmol) and directly put it into the next reaction.

[0116] MS(EI): m / z 984.2859[M + ; Combustion elemental analysis: C 58 H 57 BBr2N2O2(%) Calculated value: C, 70.74; H, 5.83; B, 1.10; Br, 16.23; N, 2.84; O, 3.25; Measured value: C, 70.75; H, 5.84; N, 2.86; O, 3.27.

[0117] [Synthesis of Compound 1-23]

[0118]

[0119] Take the product P4 (15 mmol) in a Schlenk reaction tube, add the reaction solvent anhydrous tetrahydrofuran, evacuate and replace with nitrogen three times, then use the method of adding liquid nitrogen and acetone to cool the reaction system to -78 °C. Slowly add 18.62 ml (46.57 mmol) of n-butyllithium (2.5 M hexane solution) dropwise using a syringe. Keep the temperature and stir for half an hour at -78 °C, warm the reaction vessel to room temperature and stir for another half an hour, then add 4.16 g (21.68 mmol) of methyl 2,4,6-trimethylphenylborate, and react at room temperature for 12 hours. After the reaction is completed, extract and separate with dichloromethane / saturated brine. After extracting the organic layer liquid three times, dry it with anhydrous sodium sulfate, and then remove the organic solvent by rotary evaporator. Separate and purify the product by silica gel column chromatography to obtain a pale yellow solid (7.04 g, 7.37 mmol).

[0120] MS(EI): m / z 954.5467[M + ; Combustion elemental analysis: C 67 H 68 B2N2O2(%) Calculated: C, 84.27; H, 7.18; B, 2.26; N, 2.93; O, 3.35; Found: C, 84.25; H, 7.17; N, 2.95; O, 3.33.

[0121] Synthesis of Compound 1-31 in Example 2

[0122] [Synthesis of Compound P5]

[0123]

[0124] Add 1-fluoro-2-bromo-3-iodobenzene (12.0 g, 40 mmol), 2-bromo-3-fluorophenol (9.2 g, 48 mmol), CuI (1.5 g, 8.0 mmol), iron(III) 2,4-pentanedionate (Fe(acac)3, 2.8 g, 8.0 mmol), potassium orthophosphate (K3PO4, 17.0 g, 80 mmol) and dimethyl sulfoxide (DMSO, 30 mL) to a 100 mL Schlenk tube with a magnetic stir bar, evacuate and fill with nitrogen three times. Place the tube in an oil bath at 110 °C and stir for 18 h, then cool to room temperature, dilute with ethyl acetate, wash with brine, dry over Na2SO4, and concentrate by rotary evaporator. Finally, purify the reactant by column chromatography to obtain a colorless solution P5 (36 mmol).

[0125] MS(EI): m / z 363.8733 [M + ; Combustion elemental analysis: C 12 H6Br2F2O (%) Calculated: C, 39.60; H, 1.66; Br, 43.91; F, 10.44; O, 4.40; Found: C, 39.62; H, 1.68; O, 4.43.

[0126] [Synthesis of Compound P6]

[0127]

[0128] Take carbazole (56.44 mmol) in a Schlenk reaction tube, then add 3.4 g (84.68 mmol) of NaH (60% dispersed in kerosene). Using DMF as the solvent, after purging with nitrogen three times, stir at room temperature for half an hour. Take compound P5 (25 mmol) and add it to the reaction tube. Raise the reaction temperature to 150 °C and reflux for 12 hours. After the reaction is completed, add water to the reaction system to obtain a white suspension, and then conduct suction filtration. The solid obtained by filtration is extracted with dichloromethane / saturated brine and then dried by rotary evaporation to obtain white solid product P6 (20 mmol).

[0129] MS(EI): m / z 658.0078 [M + ; Combustion elemental analysis: C 36 H 22 Br2N2O (%) Calculated: C, 65.67; H, 3.37; Br, 24.27; N, 4.25; O, 2.43; Found: C, 65.67; H, 3.37; N, 4.25; O, 2.43.

[0130] [Synthesis of Compound 1-31]

[0131]

[0132] Except for using P6 (15 mmol) to replace P4, the remaining steps are the same as those in the synthesis of Compound 1-23, and finally, light yellow solid 1-31 (8 mmol) is obtained.

[0133] MS(EI): m / z 628.2686 [M + ; Combustion elemental analysis: C 45 H 33 BN2O (%) Calculated: C, 85.99; H, 5.29; B, 1.72; N, 4.46; O, 2.55; Found: C, 85.97; H, 5.28; N, 4.48; O, 2.53.

[0134] Synthesis of Compound 1-2 in Example 3

[0135] [Synthesis of Compound P7]

[0136]

[0137] Except for using 2-bromo-3-fluorobenzenethiol (48 mmol) to replace 2-bromo-3-fluorophenol, the remaining steps are the same as those in the synthesis of Compound P5, and finally, white solid P7 (30 mmol) is obtained.

[0138] MS(EI): m / z 361.8599[M + ; Elemental analysis by combustion method: C 12 H7Br2FS(%) Calculated: C, 39.81; H, 1.95; Br, 44.14; F, 5.25; S, 8.86; Found: C, 39.84; H, 1.97; S, 8.84.

[0139] [Synthesis of Compound P8]

[0140]

[0141] Except for using P7 (25 mmol) to replace P3, the remaining steps are the same as those in the synthesis of Compound P4, and finally, white solid P8 (18 mmol) is obtained.

[0142] MS(EI): m / z 621.0523[M + ; Elemental analysis by combustion method: C 32 H 31 Br2NS(%) Calculated: C, 61.85; H, 5.03; Br, 25.71; N, 2.25; S, 5.16; Found: C, 61.88; H, 5.05; N, 2.27; S, 5.17.

[0143] [Synthesis of Compound 1-2]

[0144]

[0145] Except for using P8 (15 mmol) to replace P4, the remaining steps are the same as those in the synthesis of Compound 1-23, and finally, white solid 1-2 (8 mmol) is obtained.

[0146] MS(EI): m / z 591.3131[M + ; Elemental analysis by combustion method: C 41 H 42Calculated value of BNS(%): C, 83.23; H, 7.16; B, 1.83; N, 2.37; S, 5.42; Measured value: C, 83.26; H, 7.18; N, 2.36; S, 5.43.

[0147] Synthesis of Compound 1-41 in Example 4

[0148] [Synthesis of Compound P9]

[0149]

[0150] Except for using 5H-pyrido[4,3-b]indole (28.22 mmol) to replace 3,6-di-tert-butylcarbazole, the remaining steps are the same as those in the synthesis of Compound P8, and finally, white solid P9 (1.2 g) is obtained.

[0151] MS(EI): m / z 509.9224[M + ; Elemental analysis by combustion method: C 23 H 14 Calculated value of CBr2N2S(%): C, 54.14; H, 2.77; Br, 31.32; N, 5.49; S, 6.28; Measured value: C, 54.16; H, 2.79; N, 5.47; S, 6.26.

[0152] [Synthesis of Compound 1-41]

[0153]

[0154] Except for using P9 (15 mmol) to replace P4, the remaining steps are the same as those in the synthesis of Compound 1-23, and finally, white solid 1-41 (6.8 mmol) is obtained.

[0155] MS(EI): m / z 480.1832[M + ; Elemental analysis by combustion method: C 32 H 25 Calculated value of CBN2S(%): C, 80.00; H, 5.25; B, 2.25; N, 5.83; S, 6.67; Measured value: C, 80.03; H, 5.22; N, 5.85; S, 6.69.

[0156] Synthesis of Compound 1-43 in Example 5

[0157] [Synthesis of Compound P10]

[0158]

[0159] Except for using o-bromoiodobenzene (40 mmol) to replace 1-fluoro-2-bromo-3-iodobenzene and 2-bromo-3-fluorophenol (48 mmol) to replace 2-bromo-3-fluorobenzenethiol, the remaining steps are the same as those in the synthesis process of compound P5, and finally a white solid P10 (32 mmol) is obtained.

[0160] MS(EI): m / z 345.8827[M + ; Elemental analysis by combustion method: C 12 H7Br2FO(%) Calculated: C, 41.66; H, 2.04; Br, 46.19; F, 5.49; O, 4.62; Found: C, 41.68; H, 2.06; O, 4.65.

[0161] [Synthesis of Compound P11]

[0162]

[0163] Except for using P10 (25 mmol) to replace P7 and 3,6-diphenylcarbazole (28.22 mmol) to replace 3,6-di-tert-butylcarbazole, the remaining steps are the same as those in the synthesis process of compound P8, and finally a white solid P11 (27.7 mmol) is obtained.

[0164] MS(EI): m / z 645.0126[M + ; Elemental analysis by combustion method: C 36 H 23 Br2NO(%) Calculated: C, 67.00; H, 3.59; Br, 24.76; N, 2.17; O, 2.48; Found: C, 67.01; H, 3.56; N, 2.19; O, 2.46.

[0165] [Synthesis of Compound 1-43]

[0166]

[0167] Except for using P11 (15 mmol) to replace P4, the remaining steps are the same as those in the synthesis process of compound 1-23, and finally a white solid 1-43 (9.2 mmol) is obtained.

[0168] MS(EI): m / z 615.2733[M + ; Elemental analysis by combustion method: C 45 H 34 BNO(%) Calculated: C, 87.80; H, 5.57; B, 1.76; N, 2.28; O, 2.60; Found: C, 87.81; H, 5.59; N, 2.26; O, 2.61.

[0169] Synthesis of Compounds 1-11 in Example 6

[0170] [Synthesis of Compound P12]

[0171]

[0172] Except for using methyl iodide (38.4 mmol) instead of P2, the remaining steps were the same as those in the synthesis of Compound P3, and finally, white solid P12 (35 mmol) was obtained.

[0173] MS(EI): m / z 358.9144 [M + ; Elemental analysis by combustion method: C 13 H 10 Br2FN (%) Calculated: C, 43.49; H, 2.81; Br, 44.51; F, 5.29; N, 3.90; Found: C, 43.47; H, 2.83; N, 3.92.

[0174] [Synthesis of Compound P13]

[0175]

[0176] Except for using P12 (25 mmol) instead of P7, the remaining steps were the same as those in the synthesis of Compound P8, and finally, white solid P13 (15 mmol) was obtained.

[0177] MS(EI): m / z 618.1068 [M + ; Elemental analysis by combustion method: C 33 H 34 Br2N2 (%) Calculated: C, 64.09; H, 5.54; Br, 25.84; N, 4.53; Found: C, 64.07; H, 5.56; N, 4.56.

[0178] [Synthesis of Compounds 1-11]

[0179]

[0180] Except for using P13 (15 mmol) to replace P4, the remaining steps were the same as those in the synthesis of Compounds 1-23, and finally, white solid 1-11 (8.5 mmol) was obtained.

[0181] MS(EI): m / z 588.3676 [M + ; Elemental analysis by combustion method: C 42 H 45Calculated values of BN2(%) : C, 85.70; H, 7.71; B, 1.84; N, 4.76; Measured values: C, 85.71; H, 7.72; N, 4.75.

[0182] Synthesis of Compound 1-45 in Example 7

[0183] [Synthesis of Compound P14]

[0184]

[0185] Except for using 2-iodomesitylene (38.4 mmol) instead of P2, the remaining steps were the same as those in the synthesis of Compound P3, and finally, white solid P14 (35 mmol) was obtained.

[0186] MS(EI): m / z 462.9770[M + ; Elemental analysis by combustion method: C 21 H 18 Calculated values of Br2FN(%) : C, 54.46; H, 3.92; Br, 34.50; F, 4.10; N, 3.02; Measured values: C, 54.49; H, 3.95; N, 3.03.

[0187] [Synthesis of Compound P15]

[0188]

[0189] Except for using P14 (25.0 mmol) instead of P7, the remaining steps were the same as those in the synthesis of Compound P8, and finally, white solid P15 (15.5 mmol) was obtained.

[0190] MS(EI): m / z 722.1694[M + ; Elemental analysis by combustion method: C 41 H 42 Calculated values of Br2N2(%) : C, 68.15; H, 5.86; Br, 22.12; N, 3.88; Measured values: C, 68.17; H, 5.88; N, 3.86.

[0191] [Synthesis of Compound 1-45]

[0192]

[0193] Except for using P15 (15.0 mmol) to replace P4, the remaining steps were the same as those in the synthesis of Compound 1-23, and finally, white solid 1-45 (8.2 mmol) was obtained.

[0194] MS(EI): m / z 692.4302[M+ ; Combustion elemental analysis: C 50 H 53 Calculated values for BN2(%) : C, 86.68; H, 7.71; B, 1.56; N, 4.04; Measured values: C, 86.69; H, 7.74; N, 4.06.

[0195] Synthesis of Compound 1-18 in Example 8

[0196] [Synthesis of Compound P16]

[0197]

[0198] Except for using carbazole (28.22 mmol) instead of 3,6-di-tert-butylcarbazole, the remaining steps were the same as those in the synthesis of Compound P13, and finally, white solid P16 (20.52 mmol) was obtained.

[0199] MS(EI): m / z 505.9816[M + ; Combustion elemental analysis: C 25 H 18 Calculated values for Br2N2(%) : C, 59.31; H, 3.58; Br, 31.57; N, 5.53; Measured values: C, 59.33; H, 3.56; N, 5.56.

[0200] [Synthesis of Compound 1-18]

[0201]

[0202] Except for using P16 (15.5 mmol) to replace P4, the remaining steps were the same as those in the synthesis of Compound 1-23, and finally, white solid 1-18 (8.9 mmol) was obtained.

[0203] MS(EI): m / z 476.2424[M + ; Combustion elemental analysis: C 34 H 29 Calculated values for BN2(%) : C, 85.72; H, 6.14; B, 2.27; N, 5.88; Measured values: C, 85.76; H, 6.11; N, 5.86.

[0204] Preparation of Organic Electroluminescent Device 1 (OLED-1) in Example 9

[0205] In this embodiment, compound 1-23 prepared in Example 1 is used as the doped luminescent material, indium tin oxide (ITO) is used as the anode, commercial compound mCP is used as the host material, HAT-CN is used as the hole injection material, TAPC is used as the hole transport material, TCTA is used as the electron blocking material, DPEPO is used as the hole blocking material, TmPyPB is used as the electron transport material, Liq is used as the electron injection material, and metal aluminum Al is used as the cathode material. The device structure is: ITO / HAT-CN / TAPC / TCTA / Compound 1-23 (20 wt%):mCP / DPEPO / TmPyPB / Liq / Al. Here, 20 wt% is the weight percentage of compound 1-23 in the mixture composed of compound 1-23 and the host material.

[0206] Specifically, the device fabrication process is as follows: The transparent conductive glass substrate with the anode ITO is repeatedly cleaned with a detergent multiple times until it is clean, rinsed thoroughly with deionized water, and then placed in deionized water, acetone, and isopropanol solvents for ultrasonic treatment for 20 minutes each in sequence. After cleaning, it is placed in an environment of high-purity argon to dry the solvent on the surface of the glass substrate, and then placed in an ultraviolet ozone machine for 15 minutes. Carefully place the cleaned glass substrate with ITO in the chamber of the vacuum evaporation device, evacuate to a pressure lower than 2×10 -5 Pa and then start evaporating each functional layer: First, evaporate HAT-CN at a rate of 0.2 nm / s to a thickness of 10 nm as the hole injection layer; subsequently, evaporate TAPC at a deposition rate of 0.2 nm / s to a thickness of 50 nm as the hole transport layer; then, evaporate TCTA at a deposition rate of 0.2 nm / s to a thickness of 10 nm as the electron blocking layer; subsequently, co-evaporate the host material mCP and compound 1-23 from two sources at a deposition rate of 0.2 nm / s to a thickness of 20 nm as the light-emitting layer; then, evaporate DPEPO at a deposition rate of 0.2 nm / s to a thickness of 10 nm as the hole blocking layer; subsequently, evaporate TmPyPB at a deposition rate of 0.2 nm / s to a thickness of 30 nm as the electron transport layer; then, evaporate Liq at a deposition rate of 0.02 nm / s to a thickness of 1 nm as the electron injection layer; finally, evaporate Al at a deposition rate of 0.5 nm / s to a thickness of 100 nm as the cathode. The structure of the obtained organic electroluminescent device is as Figure 10 shown.

[0207] Fabrication of Organic Electroluminescent Device 2 (OLED-2) in Example 10

[0208] In this embodiment, Compound 1-31 prepared in Example 2 is used as the doped luminescent material, indium tin oxide (ITO) is used as the anode, commercial compound DPEPO is used as the host material, HAT-CN is used as the hole injection material, TAPC is used as the hole transport material, TCTA and mCP are used as the electron blocking materials, DPEPO is used as the hole blocking material, TmPyPB is used as the electron transport material, Liq is used as the electron injection material, and Al is used as the cathode material. The device structure is: ITO / HAT-CN / TAPC / TCTA / mCP / Compound 1-31 (20 wt%):DPEPO / DPEPO / TmPyPB / Liq / Al. The structure of the obtained organic light-emitting device is as Figure 10 shown.

[0209] Specifically, the device fabrication process is as follows: The transparent conductive glass substrate with the anode ITO is cleaned multiple times with a cleaner, rinsed thoroughly with deionized water, and then placed in deionized water, acetone, and isopropyl alcohol solvents for ultrasonic treatment for more than 15 minutes each. After cleaning, it is placed in an environment of high-purity argon to dry the solvent on the surface of the glass substrate, and then placed in an ultraviolet ozone machine for 15 minutes. Carefully place the cleaned glass substrate with ITO in the chamber of the vacuum evaporation device, evacuate to less than 2×10 -5 Pa and then start evaporating each functional layer: First, evaporate HAT-CN at a rate of 0.2 nm / s to a thickness of 10 nm as the hole injection layer; subsequently, evaporate TAPC at a deposition rate of 0.2 nm / s to a thickness of 50 nm as the hole transport layer; subsequently, evaporate TCTA and mCP at a deposition rate of 0.2 nm / s to a thickness of 10 nm each as the electron blocking layer; subsequently, co-evaporate the host material DPEPO and Compound 1-31 from two sources at a deposition rate of 0.2 nm / s to a thickness of 20 nm as the light-emitting layer; subsequently, evaporate DPEPO at a deposition rate of 0.2 nm / s to a thickness of 10 nm as the hole blocking layer; subsequently, evaporate TmPyPB at a deposition rate of 0.2 nm / s to a thickness of 50 nm as the electron transport layer; subsequently, evaporate Liq at a deposition rate of 0.02 nm / s to a thickness of 1 nm as the electron injection layer; finally, evaporate Al at a deposition rate of 0.5 nm / s to a thickness of 100 nm as the cathode.

[0210] Preparation of Organic Light-Emitting Device 3 (OLED-3) in Example 11

[0211] Except that Compound 1-2 is used as the light-emitting layer material instead of Compound 1-31 and the host material is replaced with DBFPO instead of DPEPO, OLED-3 is prepared under the same production conditions as OLED-2.

[0212] Preparation of Organic Light-Emitting Device 4 (OLED-4) in Example 12

[0213] OLED-4 was prepared under the same production conditions as OLED-2, except that compound 1-41 was used as the light-emitting layer material instead of compound 1-31.

[0214] Preparation of Organic Electroluminescent Device 5 (OLED-5) in Example 13

[0215] OLED-5 was prepared under the same production conditions as OLED-2, except that compound 1-43 was used as the light-emitting layer material instead of compound 1-31.

[0216] Preparation of Organic Electroluminescent Device 6 (OLED-6) in Example 14

[0217] OLED-6 was prepared under the same production conditions as OLED-2, except that compound 1-11 was used as the light-emitting layer material instead of compound 1-31.

[0218] Preparation of Organic Electroluminescent Device 7 (OLED-7) in Example 15

[0219] OLED-7 was prepared under the same production conditions as OLED-2, except that compound 1-45 was used as the light-emitting layer material instead of compound 1-31, and the host material was replaced with DBFPO instead of DPEPO.

[0220] Preparation of Organic Electroluminescent Device 8 (OLED-8) in Example 16

[0221] OLED-8 was prepared under the same production conditions as OLED-2, except that compound 1-18 was used as the light-emitting layer material instead of compound 1-31.

[0222] Figure 1 The single crystal structures of compounds 1-11 and 1-18 in Examples 6 and 8 of the present invention are shown. The torsion angles of the donor groups relative to the molecular nitrogen-containing backbone reach 89.86° and 88.2° respectively, approaching 90°. Such large torsion angles may bring smaller ΔE to the material ST , thereby bringing about an improvement in TADF performance.

[0223] Figure 2 The calculated results of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of compounds 1-11 and 1-18 in Examples 6 and 8 of the present invention are shown. Theoretical calculation and analysis show that HOMO is mainly distributed on the donor, and LUMO is mainly distributed on the rigid backbone containing organoboron. A relatively large torsion angle is formed between the two, and the overlap between the HOMO and LUMO orbitals is very small, which can effectively separate the molecular frontier orbitals in space and can significantly reduce ΔE st , thereby increasing the RISC rate.

[0224] Figure 3 These are the thermogravimetric test curves of Compounds 1-11 and 1-18 in Examples 6 and 8 of the present invention. The decomposition temperature of Compound 1-11 is 435 °C, and the decomposition temperature of Compound 1-18 is 410 °C. Both compounds have good thermal stability, which is helpful for the thermal evaporation preparation of OLEDs.

[0225] Figure 4 These are the ultraviolet-visible absorption and photoluminescence spectra of Compounds 1-11 and 1-18 of the present invention in toluene solution. Both of them have a strong absorption peak at 300 nm, and this peak should be attributed to the π-π* transition. The relatively broad absorption peak at around 400 nm is attributed to the intramolecular charge transfer from the donor to the nitrogen-containing heteroboron. The emission peak of Compound 1-18 is at 432 nm (deep blue light), and the full width at half maximum (FWHM) is 52 nm; while the electron-donating ability of 3,6-di-tert-butylcarbazole relative to carbazole is enhanced, and the emission peak of Compound 1-11 is at 450 nm (pure blue light), and the FWHM is 50 nm. * The emission peak of Compound 1-18 is at 432 nm (deep blue light), and the full width at half maximum (FWHM) is 52 nm; while the electron-donating ability of 3,6-di-tert-butylcarbazole relative to carbazole is enhanced, and the emission peak of Compound 1-11 is at 450 nm (pure blue light), and the FWHM is 50 nm.

[0226] Figure 5 These are the photoluminescence spectra of the thin films prepared with Compounds 1-11 and 1-18 of the present invention in Examples 6 and 8 as the guest luminescent materials, DPEPO as the host material, and the doping concentration of 10 wt%. The emission peaks of the two are at 459 nm (pure blue light) and 442 nm (deep blue light) respectively.

[0227] Figure 6 These are the current density-voltage-brightness (I-V-L) curves of the organic light-emitting device (OLED-6) containing Compound 1-11 prepared in Example 6 of the present invention. It can be analyzed from the curves that the corresponding deep blue light-emitting device containing Compound 1-11 prepared in Example 6 has a relatively low turn-on voltage (3.2 V) and a relatively high brightness (greater than 3000 nits).

[0228] Figure 7 These are the current efficiency and power efficiency-brightness curves of the organic light-emitting device (OLED-6) containing the compound prepared in Example 6 of the present invention. It can be analyzed from the curves that the light-emitting efficiency of the electroluminescent device corresponding to Compound 1-11 prepared in Example 6 is relatively high.

[0229] Figure 8 These are the external quantum efficiency (EQE)-brightness curves of the organic light-emitting device (OLED-6) containing the compound prepared in Example 6 of the present invention. It can be analyzed from the curves that the maximum EQE of the electroluminescent device corresponding to the compound prepared in Example 6 is relatively high, and the efficiency roll-off corresponding to 1000 nits is relatively small.

[0230] Figure 9For the device prepared with the compound 1-11 synthesized in Example 6 of the present invention as the guest luminescent material, DPEPO as the host material, and the doping concentration of compound 1-11 being 20 wt%, the electroluminescence spectra at different driving voltages are as follows. From Figure 9 It can be seen that the spectra at different driving voltages almost overlap without broadening. This indicates that the device has excellent spectral stability. This excellent spectral stability shows that excitons mainly recombine in the light-emitting layer. In addition, the device prepared based on compound 1-11 can achieve deep blue light emission and a narrow emission band. The CIE y value corresponding to 1000 candela per square meter is 0.089, meeting the color gamut standard of the National Television Standards Committee (NTSC).

[0231] Figure 10 The structure diagram of the organic electroluminescent device made using the compound of the present invention is shown in the following figure.

[0232] Among them, 1 - transparent glass substrate, 2 - anode, 3 - hole injection layer, 4 - hole transport layer, 5 - electron blocking layer, 6 - light-emitting layer, 7 - hole blocking layer, 8 - electron transport layer, 9 - electron injection layer, 10 - cathode.

[0233] The structures of the functional layer materials used in Examples 10 - 16 are as follows:

[0234]

[0235] Table 1. Comparison of OLED device performances in Examples 9 - 16

[0236]

[0237]

[0238] From the device characterization test results, it can be seen that for the OLED prepared with the compound of the present invention as the light-emitting layer material, not only can blue light emission be achieved, but also a relatively high external quantum efficiency is shown. Among them, the external quantum efficiency of the device prepared with compound 1-11 is 17.6%. The CIE y values corresponding to 1000 candela per square meter are 0.089 respectively, meeting the color gamut standard of the National Television Standards Committee (NTSC), and the efficiency roll-off is small (as shown in Figure 8 ).

[0239] From the above comparison, it can be seen that the thermally activated delayed fluorescence material based on organoboron of the present invention can effectively improve the device performance, and a relatively high device efficiency can also be obtained in the deep blue light band to achieve narrow emission, providing a feasible idea for the material design of future high-resolution displays. In addition, the compound of the present invention also has the advantages of simple synthesis method and low preparation cost.

[0240] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. The compound of formula (I): Wherein: R1 and R2 are the same or different and are each independently selected from H, CN, and the following unsubstituted groups optionally substituted with one, two or more Ra: C 1-12 alkyl, C 1-12 alkoxy, C 6-20 aryl, 5- to 25-membered heteroaryl, -N-(C 6-20 aryl)2, -N-(5- to 25-membered heteroaryl)2, or a spiro ring formed by a 5- to 25-membered heteroaryl and C 6-20 aryl sharing a common carbon atom; Ra is selected from the following groups: cyano, C 1-12 alkyl, C 1-12 alkoxy, C 6-20 aryl, 5- to 25-membered heteroaryl, -N-(C 6-20 aryl)2 or -N-(5- to 25-membered heteroaryl)2; m and n are the same or different and are independently 1, 2 or 3 from each other; Said Ra is further optionally substituted by one, two or more C 6-20 aryl groups; Y is selected from any one of a chemical bond, -O-, -S-, -Se-, -Te-, -C(D1D2)-, -N(D3)-, -C(O)-, -S(=O)2-, -Si(D1D2)-, -P(D3)-, -P(=O)(D3)- or -B(D3)-; G1, G2, D1, D2, D3 are the same or different and are each independently selected from hydrogen, deuterium, halogen, cyano, nitro, hydroxy, =O, aldehyde group, and the following groups which are unsubstituted or optionally substituted by one, two or more Rb: C 1-12 alkyl, -COC 1-12 alkyl, -COOC 1-12 alkyl, -CONHC 1-12 alkyl, C 3-20 cycloalkyl, C 1-12 alkoxy, C 6-20 aryloxy, C 1-12 alkylthio, C 6-20 arylthio, C 1-12 alkylsulfonyl, C 6-20 arylsulfonyl, C 2-12 alkenyl, -Si(C 1-12 alkyl)3, -Si(C 6-20 aryl)3, -Si(5-25-membered heteroaryl)3, -B(C 1-12 alkyl)2, -B(C 6-20 aryl)2, -B(5-25-membered heteroaryl)2, NH2, -P(C 6-20 aryl)3, phosphine oxide (P=O), C 6-20 aryl, 5-25-membered heteroaryl, 3-20-membered heterocyclic group, a spiro ring formed by a 13-20-membered fused cycloalkenyl and a 3-20-membered heterocyclic group sharing a carbon atom; or a group as shown below: Wherein: Y1, Y2, Y3 and Y4 are the same or different and are independently selected from -C(=O), -O-, -S, -Se- or -Te-; D3, D4, D5, D6, D7, D8, D9, D 10 , D 11 , D 12 , D 13 , D 14 , D 15 , D 16 , D 17 , D 18 are the same or different and are independently selected from H, halogen, C 1-12 alkyl, halo-C 1-12 alkyl, C 1-12 alkoxy, C 6-20 aryl, 5- to 25-membered heteroaryl, C 1-6 alkyl-substituted 5- to 25-membered heteroaryl, -N-(5- to 25-membered heteroaryl)2, -N-(C 6-20 aryl)2 or C 6-14 aryl-substituted 5- to 14-membered heteroaryl; Rb is selected from =O, halogen, cyano, nitro, hydroxy, aldehyde, C 1-12 alkyl, -COC 1-12 alkyl, -COOC 1-12 alkyl, C 3-20 cycloalkyl, C 1-12 alkoxy, C 6-20 aryl, 5-25 membered heteroaryl; Ph is selected from the following groups which are unsubstituted or optionally substituted by one, two or more Ri: C 6-20 aryl, 5- to 25-membered heteroaryl; Ri is selected from C 1-12 alkyl groups.

2. The compound according to claim 1, wherein, The structure of formula (I) is selected from the following structures: Wherein, in formula I-A, Y is a chemical bond; In formula I-B, Y is not a chemical bond and is selected from any one of -O-, -S-, -Se-, -Te-, -C(D1D2)-, -N(D3)-, -C(O)-, -S(=O)2-, -Si(D1D2)-, -P(D3)-, -P(=O)(D3)- or -B(D3)-; R1, R2, G1, G2, Ph, D1, D2, D3 have the definitions described in claim 1.

3. The compound according to claim 1, wherein R1 and R2 are the same or different and are each independently selected from H, CN, C 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl, 5- to 14-membered heteroaryl, C 1-6 alkyl-substituted 5- to 14-membered heteroaryl, -N-(5- to 14-membered heteroaryl)2, -N-(C 1-6 alkyl-substituted C 6-14 aryl)2 or C 6-14 aryl-substituted 5- to 14-membered heteroaryl; Ph is selected from the following groups which are unsubstituted or optionally substituted by one, two or more Ri: C 6-14 aryl, 5- to 14-membered heteroaryl; Ri is selected from C 1-6 alkyl; Y is selected from any one of a chemical bond, -O-, -S-, -Se-, -Te-, -C(D1D2)-, -N(D3)-, -C(O)-, -S(=O)2-, -Si(D1D2)-, -P(D3)-, -P(=O)(D3)- or -B(D3); G1, G2, D1, D2, D3 are the same or different and are each independently selected from H, C 1-6 alkyl, C 1-6 alkoxy, and the following groups which are unsubstituted or optionally substituted by one, two or more Rb: C 3-20 cycloalkyl, 3-20 membered heterocyclic group, C 6-20 aryl, 5-25 membered heteroaryl, a spiro ring formed by a 13-20 membered fused cycloalkenyl and a 3-20 membered heterocyclic group sharing a carbon atom, -N-(C 6-20 aryl)2, -N-(5-25 membered heteroaryl)2; or a group as shown below: Wherein: Y1, Y2, Y3 and Y4 are the same or different and are independently selected from C=O, O, S, Se or Te; D3, D4, D5, D6, D7, D8, D9, D 10 , D 11 , D 12 , D 13 , D 14 , D 15 , D 16 , D 17 , D 18 are the same or different and are each independently selected from H, halogen, C 1-12 alkyl, halo-C 1-12 alkyl, C 1-12 alkoxy, C 6-14 aryl, 5- to 14-membered heteroaryl, C 1-6 alkyl-substituted 5- to 14-membered heteroaryl, -N-(5- to 14-membered heteroaryl)2, -N-(C 6-14 aryl)2 or C 6-14 aryl-substituted 5- to 14-membered heteroaryl; Rb is selected from =O, halogen, cyano, nitro, hydroxy, aldehyde, C 1-12 alkyl, C 3-20 cycloalkyl, -COC 1-12 alkyl, -COOC 1-12 alkyl, C 1-12 alkoxy, C 6-14 aryl, 5-14-membered heteroaryl, -N-(C 6-14 aryl)2 or -N-(5-14-membered heteroaryl)2.

4. The compound according to any one of claims 1-3, wherein, G1 and G2 are the same or different and are each independently selected from H, C 1-6 alkyl, unsubstituted, or optionally substituted by one, two or more Rb, the following groups: C 6-14 aryl, 5-22 membered heteroaryl, -N-(C 6-14 aryl)2, -N-(5-14 membered heteroaryl)2, a spiro ring formed by a 13-20 membered fused cycloalkenyl and a 3-20 membered heterocyclic group sharing a carbon atom; or alternatively the following groups: Wherein: Y1, Y2, Y3 and Y4 are the same or different and are independently selected from C=O, O, S, Se or Te; D3, D4, D5, D6, D7, D8, D9, D 10 , D 11 , D 12 , D 13 , D 14 , D 15 , D 16 , D 17 , D 18 are the same or different and are each independently selected from H, halogen, C 1-6 alkyl, halo-C 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl, 5-22-membered heteroaryl, C 1-6 alkyl-substituted 5-25-membered heteroaryl, -N-(5-14-membered heteroaryl)2, -N-(C 6-14 aryl)2 or C 6-14 aryl-substituted 5-14-membered heteroaryl; Rb is selected from the following groups: cyano, C 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl, 5- to 14-membered heteroaryl, -N-(C 6-14 aryl)2 or -N-(5- to 14-membered heteroaryl)2.

5. The compound according to any one of claims 1-4, wherein Y is a chemical bond, any one of O, S, Se, Te, C=O, S(=O)2, CD1D2, SiD1D2, ND3, PD3 or BD3; D1, D2, and D3 are the same or different and are each independently selected from H, C 1-6 alkyl, unsubstituted or optionally substituted by one, two or more Rb selected from the following substituted groups: C 6-14 aryl, 5-22-membered heteroaryl; or the following groups: Wherein: Y1, Y2, Y3 and Y4 are the same or different and are independently selected from -C(=O), -O-, -S, -Se- or -Te-; D3, D4, D5, D6, D7, D8, D9, D 10 , D 11 , D 12 , D 13 , D 14 , D 15 , D 16 , D 17 , D 18 are the same or different and are each independently selected from H, halogen, C 1-12 alkyl, halo C 1-12 alkyl, C 1-12 alkoxy, C 6-14 aryl, 5- to 14-membered heteroaryl, C 1-6 alkyl-substituted 5- to 25-membered heteroaryl, -N-(5- to 25-membered heteroaryl)2, -N-(C 6-20 aryl)2 or C 6-14 aryl-substituted 5- to 14-membered heteroaryl; Among them, Rb is selected from C 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl or 5-14-membered heteroaryl.

6. The compound according to any one of claims 1-5, wherein R1 and R2 are the same and are selected from H; Preferably, Y is a chemical bond, -O-, -S-, -Se-, -Te-, -C(D1D2)-, -N(D3)-; wherein, D1 and D2 are selected from methyl or ethyl; D3 is selected from methyl, ethyl, isopropyl, tert-butyl, Preferably, G1 and G2 are the same or different and are independently selected from H or the following groups: Preferably, Ph is selected from the following structures:

7. The compound according to any one of claims 1-6, wherein, The compound of formula (I) is selected from one of the following structures:

8. A process for preparing the compound represented by formula (I) according to any one of claims 1-7, wherein, Comprising the following steps: Reacting compound Ia with compound Ph-L to obtain the compound of formula (I); Wherein, Y, R1, R2, m, n, G1, G2 and Ph have the definitions described in any one of claims 1-7; L is a leaving group.

9. Use of the compound of formula (I) according to any one of claims 1-7 as a thermally activated delayed fluorescence material in the preparation of organic electronic devices, preferably in the preparation of organic electroluminescent devices.

10. An organic electroluminescent device, wherein, It includes two electrodes and an organic layer located between the electrodes, and the organic layer includes the compound represented by the above formula (I).

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