Organic red light compound and application thereof in organic electroluminescent device

Abstract

The present application relates to a kind of organic red light compounds shown in formula I and its application in organic electroluminescent device.The compound of the present application is a kind of asymmetric donor-acceptor type organic red fluorescent small molecule, with obvious charge transfer (HLCT) excited state properties, can take into account the high photoluminescence efficiency of solid state doped thin film and high exciton utilization in electroluminescence.This kind of material is used as light emitting layer in device with CBP doping, can prepare high-efficiency red light device, has important application value in full-color display and white light illumination field.

Description

Technical Field

[0001] This invention relates to the field of organic electroluminescence technology, and in particular to a class of organic electroluminescent red fluorescent compounds and their application in electroluminescent devices. Background Technology

[0002] Organic light-emitting diodes (OLEDs) possess advantages such as high contrast, wide color gamut, high response speed, low power consumption, and flexibility, making them widely used in display fields such as tablets, smartphones, and wearable electronic devices, as well as in lighting. In OLED displays, organic light-emitting materials play a crucial role, and the choice of these materials directly affects the device's electroluminescence performance. Compared to green and blue light-emitting materials, organic red light-emitting materials require a smaller band gap. Due to the band gap rule, as the light emission band gap narrows (i.e., a red shift in light color), the radiative transition rate gradually decreases, meaning the luminous efficiency gradually declines. Therefore, the design and development of red light-emitting materials with high luminous efficiency has always been a research hotspot in the OLED field. Summary of the Invention

[0003] In red OLED devices, color temperature and efficiency are two crucial evaluation metrics. Generally, emission wavelengths exceeding 600 nm are considered red light. Electroluminescent materials with donor-acceptor (DA) structures enhance charge transfer (CT) by increasing the electron-donating ability of the donor (within the same acceptor), thus achieving a redshift in color temperature. However, excessively strong CT leads to spatially separated transition orbitals, making it difficult to achieve high photoluminescence efficiency. Therefore, based on strong CT materials, appropriately introducing localized states (LE) to construct hybrid localized charge transfer (HLCT) states can improve photoluminescence efficiency while maintaining a certain color temperature, further achieving effective electroluminescence. HLCT materials not only utilize the high luminescence efficiency of LE states but also the high exciton utilization of CT states. Therefore, developing a class of high-efficiency organic red-light compounds with HLCT properties and realizing their application in organic electroluminescent devices is of significant practical importance.

[0004] One of the objectives of this invention is to provide a class of asymmetric donor-acceptor type organic red fluorescent small molecules with obvious HLCT excited state properties, which can balance the high photoluminescence efficiency of solid-state doped films and the high exciton utilization rate in electroluminescence.

[0005] A second objective of this invention is to provide an organic electroluminescent device comprising the compound.

[0006] A third objective of this invention is to provide an application of the compound in the preparation of organic electroluminescent devices.

[0007] In one aspect, the present invention provides a compound represented by Formula I.

[0008]

[0009] in,

[0010] B1 is selected from or

[0011] R1 and R2 are each independently selected from hydrogen, C1-C10 alkyl, C1-C10 alkoxy, and C6-C30 aryl; preferably each independently selected from hydrogen and C1-C4 alkyl, and particularly each independently selected from hydrogen, methyl, or ethyl.

[0012] A1 and A2 are each independently CR3 or N;

[0013] R3 is independently selected from hydrogen, halogen, cyano, C1-C10 alkyl, C1-C10 alkoxy, and C6-C30 aryl; preferably independently selected from hydrogen, fluorine, cyano, C1-C4 alkyl, and C6-C12 aryl, more preferably independently selected from hydrogen.

[0014] Alternatively, two adjacent R3s together with the connected C to form a C6-C30 aromatic ring, especially a C6-C12 aromatic ring, and even more so a benzene ring.

[0015] Preferably, Selected from

[0016] D1, D2, D4, and D5 are each independently selected from hydrogen, halogen, C1-C10 alkyl, C1-C10 alkoxy, C6-C30 aryl groups, and C6-C30 aryl groups substituted with substituents selected from halogen, cyano, C1-C10 alkyl, and C1-C10 alkoxy groups; preferably, each is independently selected from hydrogen, halogen, C1-C4 alkyl, C1-C4 alkoxy, C6-C12 aryl groups, and C6-C12 aryl groups substituted with substituents selected from halogen, cyano, C1-C4 alkyl, and C1-C4 alkoxy groups, particularly independently selected from hydrogen, fluorine, methyl, phenyl,

[0017] D3 is selected from hydrogen, halogen, cyano, C1-C10 alkyl, C1-C10 alkoxy, C6-C30 aryl, and C6-C30 aryl substituted with a substituent selected from halogen, cyano, C1-C10 alkyl, and C1-C10 alkoxy. Preferably, the aryl group is selected from hydrogen, halogen, cyano, C1-C4 alkyl, C1-C4 alkoxy, C6-C12, or C6-C12 aryl group substituted with a substituent selected from halogen, cyano, C1-C4 alkyl, and C1-C4 alkoxy. In particular, it is selected from hydrogen, fluorine, cyano, methyl, phenyl,

[0018] X1 is selected from C6-C30 aryl groups and C6-C30 aryl groups substituted with substituents selected from halogens, cyano groups, C1-C10 alkyl groups, and C1-C10 alkoxy groups, preferably selected from C6-C12 aryl groups and C6-C30 aryl groups substituted with substituents selected from halogens, cyano groups, C1-C4 alkyl groups, and C1-C4 alkoxy groups, particularly selected from phenyl groups.

[0019] X2 is selected from Group 4 elements, preferably C or Si.

[0020] X3 is selected from Group 6 elements, preferably O or S.

[0021] Alternatively, two adjacent substituents in D1, D2, D3, D4, and D5 together with the connected C form a C6-C30 aromatic ring or a C6-C30 aromatic ring substituted with substituents selected from halogens, cyano, C1-C4 alkyl, and C1-C4 alkoxy, especially a C6-C12 aromatic ring or a C6-C12 aromatic ring substituted with substituents selected from halogens, cyano, C1-C4 alkyl, and C1-C4 alkoxy, more especially a benzene ring or a benzene ring substituted with substituents selected from halogens, cyano, C1-C4 alkyl, and C1-C4 alkoxy;

[0022] or for in particular

[0023] In some implementations, R1 and R2 are the same; D1 and D5 are the same; D2 and D4 are the same.

[0024] In some embodiments, the compound of formula I is selected from compounds of formulas I-1-1, I-1-2, I-1-3, I-2-1, I-2-2, and I-2-3:

[0025]

[0026] D1, D2, D3, D4, and D5 are defined as above.

[0027] In this paper, the following definitions are made:

[0028] This indicates that the group is attached to the parent nucleus from this location.

[0029] A "connecting bond" means that the atoms on both sides of the bond are directly connected.

[0030] C1-C10 alkyl refers to straight-chain or branched alkyl groups containing 1-10 carbon atoms; specific examples may include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2- Ethylbutyl, heptyl, n-heptyl, 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, trioctyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, and similar groups, but not limited to these; the meaning of C1-C4 alkyl is deduced by analogy.

[0031] C1-C10 alkoxy groups refer to straight-chain or branched alkoxy groups containing 1-10 carbon atoms. Specific examples include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentoxy, isopentoxy, neopentoxy, n-hexyloxy, isohexyloxy, 3-methylpentoxy, 3,3-dimethylbutoxy, 2-ethylbutoxy, n-octoxy, n-nonoxy, n-decoxy, etc. The meanings of C1-C4 alkoxy groups are deduced similarly.

[0032] C6-C30 aryl groups refer to monocyclic or polycyclic aryl groups having 6 to 30 carbon atoms, particularly monocyclic or bicyclic cyclic systems. Specific examples of aryl groups include phenyl, biphenyl, triphenyl, naphthyl, anthracene, etc. Aryl, phenanthrene, perylene, fluoranyl, benzo[9,10]phenanthrene, pyrene, tetraphenyl, pentaphenyl, fluorenyl, indene, acenaphthene, benzofluorenyl, spirobisfluorenyl, 2,3-dihydro-1H-indene, etc., but not limited to these. C6-C30 aromatic rings refer to the ring structures of the above-mentioned aryl groups. The meanings of aryl or aromatic rings in C6-C12 follow the same logic.

[0033] The cyano group refers to -CN.

[0034] Halogens can be fluorine, chlorine, bromine, or iodine.

[0035] In some embodiments, the compound of formula I is selected from the following structures:

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047] Based on the structures of the compounds disclosed in this invention, those skilled in the art can design appropriate synthetic routes to synthesize the compounds of this invention using reaction principles known in the art, or synthesize the compounds of this invention by referring to the synthetic routes disclosed in the embodiments. Therefore, this invention does not specifically limit the synthetic methods of the compounds of this invention.

[0048] In some embodiments, the compounds of the present invention can be obtained by referring to method 1 or 2 as follows:

[0049]

[0050] Compound II-1 or II-2 is coupled with compound III to obtain compound IV-1 or IV-2; compound IV-1 or IV-2 is coupled with compound V to obtain compound I-1 or I-2; wherein the definitions of each substituent are the same as those defined above.

[0051] Compounds II, III, and V described above can be known compounds, or they can be synthesized by those skilled in the art using appropriate synthetic routes designed based on specific structures and well-known reaction principles, or synthesized using the synthetic routes disclosed in the examples.

[0052] The compounds of this invention are a class of asymmetric donor-acceptor type organic red fluorescent small molecules with significant charge-transfer (HLCT) excited-state properties, which can balance the high photoluminescence efficiency of solid-state doped films and the high exciton utilization in electroluminescence. When these materials are used as the light-emitting layer in devices with CBP doping, high-efficiency red light devices can be fabricated, which have important application value in the fields of full-color displays and white light illumination.

[0053] Another aspect of the present invention provides the application of the compounds described herein in the preparation of organic electroluminescent materials, organic electroluminescent devices, or display devices.

[0054] Another aspect of the present invention provides an article comprising the compound described herein, wherein the article is an organic electroluminescent material, an organic electroluminescent device, or a display device.

[0055] Preferably, the organic electroluminescent device comprises a hole injection layer, a hole transport layer, a hole blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer connected sequentially on one side of the anode layer; the light-emitting layer comprises the compound described in this invention.

[0056] The anode material can be selected from metals such as copper, gold, silver, iron, chromium, nickel, manganese, palladium, platinum, and their alloys. Anode materials can also be selected from metal oxides such as indium oxide, zinc oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); anode materials can also be selected from conductive polymers such as polyaniline, polypyrrole, and poly(3-methylthiophene). Furthermore, anode materials can also be selected from materials and combinations thereof that facilitate hole injection, in addition to those listed above, including known materials suitable for anode applications.

[0057] The cathode layer material can be selected from metals such as aluminum, magnesium, silver, indium, tin, titanium, and their alloys. Cathode materials can also be selected from multilayer metal materials such as LiF / Al, LiO2 / Al, BaF2 / Al, etc. In addition to the cathode materials listed above, cathode materials can also be materials and combinations thereof that facilitate electron injection, including known materials suitable for cathodes.

[0058] Organic electroluminescent devices can be fabricated according to methods known in the art, which will not be described in detail here. An organic electroluminescent device can be fabricated as follows: an anode is formed on a smooth, transparent or opaque substrate; an organic thin layer is formed on the anode; and a cathode is formed on the organic thin layer. The organic thin layer can be formed using known film-forming methods such as evaporation, sputtering, spin coating, dipping, and ion plating.

[0059] Display devices can be mobile phone screens, computer screens, television screens, smartwatch screens, smart car screens, VR or AR headset screens, and screens for various smart devices.

[0060] The present invention has the following beneficial effects:

[0061] (1) The compound provided by this invention is a pure organic red fluorescent small molecule with a large terphenyl-acceptor structural twist angle. This molecular design can reduce the impact of molecular aggregation, not only weakening aggregation quenching but also facilitating the construction of localized charge-transfer excited states. When such materials are used as a light-emitting layer in devices with CBP doping, they can ensure high photoluminescence efficiency while guaranteeing carrier injection and transport in electroluminescent devices, resulting in good performance of such light-emitting materials in electroluminescent devices and promising application prospects.

[0062] (2) The compounds provided by this invention have simple structures, readily available raw materials, and are easy to synthesize, making them suitable for large-scale production.

[0063] (3) The doped OLED device prepared based on the compound provided by the present invention has advantages such as low turn-on voltage, red light emission, high brightness and high device efficiency.

[0064] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments.

[0065] Unless otherwise expressly stated, numerical ranges throughout the application include any subranges therein and any numerical values ​​incremented by the smallest subunit of a given value. Unless otherwise expressly stated, numerical values ​​throughout the application represent approximate measures or limitations on the range of embodiments including minor deviations from a given value and having approximately the mentioned value as well as having the mentioned precise value. Except in the detailed description of the working embodiments provided at the end, all numerical values ​​of parameters (e.g., quantities or conditions) in this application (including the appended claims) should in all cases be understood to be modified by the term “approximately,” regardless of whether “approximately” actually precedes the numerical value. “Approximately” indicates that the stated numerical value allows for slight inaccuracies (some close to precision at that value; approximately or reasonably close to the value; approximate). If the inaccuracy provided by “approximately” is not understood in this common sense in the art, then “approximately” as used herein at least indicates a variation that can be produced by common methods of measuring and using these parameters. For example, “approximately” can include variations less than or equal to 10%, less than or equal to 5%, less than or equal to 4%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, or less than or equal to 0.5%. Attached Figure Description

[0066] Figure 1 The curves showing the relationship between external quantum efficiency and brightness of doped organic light-emitting devices prepared by using compounds 1, 3, 9, 22, 32, 42, and 43 of Examples as light-emitting layers and CBP doping, respectively.

[0067] Figure 2 The electroluminescence spectra of doped organic electroluminescent devices prepared by using compounds 1, 3, 9, 22, 32, 42, and 43 of Examples as light-emitting layers and CBP doping are shown.

[0068] Figure 3The current density-voltage relationship curves are shown for the doped organic electroluminescent devices prepared by using compounds 1, 3, 9, 22, 32, 42, and 43 of Examples as CBP doping as the light-emitting layer.

[0069] Figure 4 The brightness-voltage relationship curves of doped organic electroluminescent devices prepared by using compounds 1, 3, 9, 22, 32, 42, and 43 of Examples as CBP doping as the light-emitting layer are shown.

[0070] Figure 5 The current efficiency-luminance relationship curves are shown for doped organic electroluminescent devices prepared by using compounds 1, 3, 9, 22, 32, 42, and 43 of Examples as CBP doping as the light-emitting layer.

[0071] Figure 6 The power efficiency-luminance relationship curves are shown for doped organic electroluminescent devices prepared by using compounds 1, 3, 9, 22, 32, 42, and 43 of Examples as CBP doping as the light-emitting layer. Detailed Implementation

[0072] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0073] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0074] 4,9-Dibromonaphthothiadiazole was purchased from Jilin Zhongke Science & Technology Co., Ltd.; 10-(4-bromobenzene)-9,9-dimethyl-9,10-dihydroacridine and 2-bromoindolo[3,2,1-JK]carbazole were purchased from Zhengzhou Alpha Chemical Co., Ltd.; 10H-spiro[acridine-9,9'-fluorene] was purchased from Beijing Yibo Yuntian Technology Co., Ltd.; 4-(diphenylamino)phenylboronic acid was purchased from Anhui Zesheng Technology Co., Ltd.; and 4-(1-phenyl-1H-benzimidazol-2-yl)phenylboronic acid and (3,5-diphenylphenyl)boronic acid were purchased from Anhui Zesheng Technology Co., Ltd.

[0075] Example 1: Synthesis of Compound 1

[0076] (1) Synthesis of intermediate M1

[0077] [Reaction Formula 1]

[0078]

[0079] Potassium carbonate (5.5 g, 4 mmol), 4,9-dibromonaphthalene[2,3-c][1,2,5]thiadiazole (3.44 g, 10 mmol), and [1,1':3',1"-terphenyl]-5'-ylboronic acid (3.29 g, 12 mmol) were dissolved in toluene (15 mL), THF (10 mL), and deionized water (10 mL), with Pd(PPh3)4 (30 mg) added as a catalyst. The mixture was stirred at 90 °C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, potassium carbonate was eluted with 20 mL of deionized water, and the organic layer was extracted with dichloromethane. Finally, intermediate M1 (2.96 g, 60% yield) was obtained by column chromatography (dichloromethane:petroleum ether = 1:4). Theoretical mass spectrometry value: M W 493.42, measured m / z = 494.83 [M+H] + . 1 H NMR (500MHz, DMSO) δ8.45(d,J=8.9Hz,1H),8.13(s,1H),8.10(d,J=9.1Hz,1H),7.91(d,J=1.6Hz,2H),7. 87(d,J=7.3Hz,4H),7.78–7.74(m,1H),7.61–7.57(m,1H),7.52(t,J=7.7Hz,4H),7.43(t,J=7.3Hz,2H).

[0080] (2) Synthesis of intermediate M2

[0081] [Reaction 2]

[0082]

[0083] 10-(4-bromophenyl)-9,9-dimethyl-9,10-dihydroacridine (3.64 g, 10 mmol), potassium acetate (9.81 g, 100 mmol), and 4,4,5,5-tetramethyl-2-(tetramethyl-1,3,2-dioxaborane-2-yl)-1,3,2-dioxaborane (7.62 g, 30 mmol) were dissolved in 1,4-dioxane (200 mL), and Pd(dppf)₂Cl₂ (300 mg) was added as a catalyst. The mixture was stirred at 87 °C for 36 hours under a nitrogen atmosphere. After cooling to room temperature, potassium acetate was washed away with deionized water (40 mL), and the organic layer was extracted with dichloromethane. Finally, the intermediate M₂ (3.41 g, 83% yield) was obtained by column chromatography (dichloromethane:petroleum ether = 2:1). Theoretical mass spectrometry value: M W 411.35, measured m / z = 410.89 [M] + . 1H NMR(500MHz,DMSO)δ8.04–7.94(m,2H),7.50(dd,J=7.7,1.6Hz,2H),7.40–7.36(m,2H),7.01– 6.94(m,2H),6.94–6.88(m,2H),6.14(dd,J=8.2,1.4Hz,2H),1.62(s,6H),1.38–1.31(m,12H).

[0084] (3) Synthesis of Compound 1

[0085] [Reaction 3]

[0086]

[0087] M2 (0.49 g, 1.2 mmol), potassium carbonate (5.5 g, 4 mmol), and M1 (0.49 g, 1 mmol) were dissolved in toluene (15 mL) + THF (10 mL) + deionized water (10 mL), with Pd(PPh3)4 (30 mg) added as a catalyst. The mixture was stirred at 90 °C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 20 mL of deionized water was added to elute the potassium carbonate, and the organic layer was extracted with dichloromethane. Finally, compound 1 (0.35 g, 51% yield) was obtained by column chromatography (dichloromethane:petroleum ether = 1:4). Theoretical mass spectrometry value: M W 697.90, measured m / z = 682.66 [M-Me] + . 1 H NMR (500MHz, CD2Cl2) δ8.25(t,J=8.0Hz,2H),8.10(s,1H),8.02(d,J=8.0Hz,2H),7.97(s,2H),7.84(d,J=8.1Hz,4H),7.66(d,J=8.1Hz,2H),7 .55(t,J=7.9Hz,7H),7.53–7.48(m,1H),7.48–7.43(m,2H),7.13(t,J=7.6Hz,2H),7.02(t,J=7.4Hz,2H),6.59(d,J=8.1Hz,2H),1.78(s,6H).

[0088] Example 2 Synthesis of Compound 3

[0089] (1) Synthesis of compound 3

[0090] [Reaction 4]

[0091]

[0092] (4-(diphenylamino)phenyl)boronic acid (0.35 g, 1.2 mmol), potassium carbonate (5.5 g, 4 mmol), and M1 (0.49 g, 1 mmol) were dissolved in toluene (15 mL), THF (10 mL), and deionized water (10 mL), with Pd(PPh3)4 (30 mg) added as a catalyst. The mixture was stirred at 90 °C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 20 mL of deionized water was added to elute the potassium carbonate, and the organic layer was extracted with dichloromethane. Finally, compound 3 (0.41 g, 63% yield) was obtained by column chromatography (dichloromethane:petroleum ether = 1:4). Theoretical mass spectrometry value: M W 657.83, measured m / z = 657.69 [M] + . 1 H NMR (500MHz, CD2Cl2) δ8.24–8.16(m,2H),8.07(s,1H),7.93(s,2H),7.82(d,J=7.9Hz,4H),7.61(d,J=7 .8Hz,2H),7.54(t,J=7.6Hz,4H),7.48–7.42(m,4H),7.42–7.36(m,4H),7.36–7.24(m,6H),7.15(s,2H).

[0093] Example 3 Synthesis of Compound 9

[0094] (1) Synthesis of intermediate M3

[0095] [Reaction 5]

[0096]

[0097] 10H-spirocyclic [acridin-9,9'-fluorene] (3.31 g, 10 mmol), 1-bromo-4-iodobenzene (3.10 g, 11 mmol), tri-tert-butylphosphine (1 mL, 2 M), and sodium tert-butoxide (1.92 g, 20 mmol) were dissolved in toluene (100 mL), and Pd₂(dba)₃ (150 mg) was added as a catalyst. The mixture was stirred at 110 °C for 48 hours under a nitrogen atmosphere. After cooling to room temperature, sodium tert-butoxide was washed away with deionized water (40 mL), and the organic layer was extracted with dichloromethane. Finally, intermediate M3 (3.94 g, 81% yield) was obtained by column chromatography (petroleum ether). Theoretical mass spectrometry value: M W 486.41, measured m / z = 485.82 [M] + . 1H NMR(500MHz,CD2Cl2)δ7.89(dd,J=16.4,8.0Hz,4H),7.44(dd,J=16.3,8.0Hz,6H),7.3 2(t,J=7.4Hz,2H), 6.98(t,J=7.8Hz,2H), 6.61(t,J=7.4Hz,2H), 6.41(d,J=8.1Hz,4H).

[0098] (2) Synthesis of intermediate M4

[0099] [Reaction Formula 6]

[0100]

[0101] M3 (3.94 g, 8 mmol), potassium acetate (7.84 g, 80 mmol), and 4,4,5,5-tetramethyl-2-(tetramethyl-1,3,2-dioxaborane-2-yl)-1,3,2-dioxaboranecyclopentane (6.10 g, 24 mmol) were dissolved in 1,4-dioxane (200 mL), and Pd(dppf)₂Cl₂ (150 mg) was added as a catalyst. The mixture was stirred at 87 °C for 36 hours under a nitrogen atmosphere. After cooling to room temperature, potassium acetate was washed away with deionized water (40 mL), and the organic layer was extracted with dichloromethane. Finally, intermediate M4 (3.37 g, 79% yield) was obtained by column chromatography (dichloromethane:petroleum ether = 1:4). Theoretical mass spectrometry value: M W 533.48, measured m / z = 533.16 [M] + . 1 H NMR (500MHz, CD2Cl2) δ8.16(d,J=7.9Hz,2H),7.88(d,J=7.5Hz,2H),7.55(d,J=7.9Hz,2H),7.44(t,J=7.3Hz ,4H),7.32(t,J=7.4Hz,2H),6.95(t,J=7.8Hz,2H),6.59(t,J=7.4Hz,2H),6.43–6.33(m,4H),1.45(s,12H).

[0102] (3) Synthesis of compound 9

[0103] [Reaction Formula 7]

[0104]

[0105] M4 (0.64 g, 1.2 mmol), potassium carbonate (5.5 g, 4 mmol), and M1 (0.49 g, 1 mmol) were dissolved in toluene (15 mL) + THF (10 mL) + deionized water (10 mL), with Pd(PPh3)4 (30 mg) added as a catalyst. The mixture was stirred at 90 °C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, potassium carbonate was eluted with deionized water (20 mL), and the organic layer was extracted with dichloromethane. Finally, compound 9 (0.45 g, 55% yield) was obtained by column chromatography (dichloromethane: petroleum ether = 1:4). Theoretical mass spectrometry value: M W 820.03, measured m / z = 820.04 [M] + . 1 H NMR (500MHz, CD2Cl2) δ8.32–8.25(m,2H),8.14–8.08(m,3H),7.99(s,2H),7.91(d,J=7.6Hz,2H),7.84(dd,J=7.1,6.3Hz,6H),7.59–7.50 (m,8H),7.50–7.44(m,4H),7.36(t,J=7.4Hz,2H),7.11(t,J=7.7Hz,2H),6.73–6.69(m,2H),6.67(d,J=7.3Hz,2H),6.47(d,J=7.7Hz,2H).

[0106] Example 4 Synthesis of Compound 32

[0107] (1) Synthesis of intermediate M5

[0108] [Reaction Equation 8]

[0109]

[0110] A mixture of phenanthrene-9,10-dione (4.16 g, 20 mmol), aniline (7.45 g, 80 mmol), p-bromobenzaldehyde (3.70 g, 20 mmol), ammonium acetate (7.70 g, 100 mmol), and acetic acid (60 mL) was stirred at 120 °C under a nitrogen atmosphere for 4 h. After cooling to room temperature, the mixture was filtered to obtain a yellow solid, washed with a small amount of acetic acid and water, and dried under vacuum. The crude product was purified by column chromatography (eluent: dichloromethane) to give a white solid intermediate M5 (7.50 g, yield 83%). The product was not further purified and was used directly in the next reaction. Theoretical mass spectrometry value: M W 449.35, measured m / z = 449.62 [M] + . 1H NMR (500MHz, DMSO) δ8.94(d,J=8.3Hz,1H),8.89(d,J=8.4Hz,1H),8.69(dd,J=7.9,1.1Hz,1H),7.81–7.76(m,1H),7.75–7.72(m,3H ),7.72(d,J=3.8Hz,3H),7.71–7.68(m,2H),7.61–7.55(m,3H),7.53–7.49(m,2H),7.38–7.32(m,1H),7.09(dd,J=8.3,0.8Hz,1H).

[0111] (2) Synthesis of intermediate M6

[0112] [Reaction Formula 9]

[0113]

[0114] M5 (6.74 g, 15 mmol), 4,4,5,5-tetramethyl-2-(tetramethyl-1,3,2-dioxaborane-2-yl)-1,3,2-dioxacycloborane (11.43 g, 45 mmol), and potassium acetate (14.72 g, 150 mmol) were dissolved in 1,4-dioxane (200 mL), and Pd(dppf)₂Cl₂ (300 mg) was added as a catalyst. The mixture was stirred at 87 °C for 36 hours under a nitrogen atmosphere. After cooling to room temperature, the potassium acetate was washed away with deionized water (40 mL), and the organic layer was extracted with dichloromethane. Finally, intermediate M6 (6.03 g, 81% yield) was obtained by column chromatography (dichloromethane:petroleum ether = 1:2). Theoretical mass spectrometry value: M W 496.42, measured m / z = 495.82 [M] + . 1 H NMR (500MHz, DMSO) δ8.94(d,J=8.3Hz,1H),8.89(d,J=8.4Hz,1H),8.70(dd,J=7.9,1.1Hz,1H),7.81–7.76(m,1H),7. 75–7.66(m,6H),7.64–7.58(m,4H),7.58–7.55(m,1H),7.38–7.32(m,1H),7.11(dd,J=8.3,0.8Hz,1H),1.30(s,12H).

[0115] (3) Synthesis of compound 32

[0116] [Reaction Formula 10]

[0117]

[0118] M6 (0.59 g, 1.2 mmol), potassium carbonate (5.5 g, 4 mmol), and M1 (0.49 g, 1 mmol) were dissolved in toluene (15 mL) + THF (10 mL) + deionized water (10 mL), with Pd(PPh3)4 (30 mg) added as a catalyst. The mixture was stirred at 90 °C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, potassium carbonate was eluted with deionized water (20 mL), and the organic layer was extracted with dichloromethane. Finally, compound 32 (0.48 g, 61% yield) was obtained by column chromatography (dichloromethane:petroleum ether = 1:4). Theoretical mass spectrometry value: M W 782.96, measured m / z = 782.67 [M] + . 1 H NMR(500MHz,CD2Cl2)δ8.92(s,1H),8.86(d,J=8.4Hz,1H),8.81(d,J=8.5Hz,1H ),8.24–8.18(m,1H),8.10–8.04(m,2H),7.99–7.90(m,4H),7.83(t,J=8.8Hz,5 H),7.80–7.73(m,6H),7.69(d,J=8.1Hz,2H),7.60(t,J=7.7Hz,1H),7.54(t,J= 7.6Hz, 4H), 7.45 (t, J = 7.1Hz, 4H), 7.35 (t, J = 7.6Hz, 1H), 7.27 (d, J = 8.2Hz, 1H).

[0119] Example 5 Synthesis of Compound 22

[0120] (1) Synthesis of intermediate M7

[0121] [Reaction Formula 11]

[0122]

[0123] 2-Bromoindol-3,2,1-[k]carbazole (3.20 g, 10 mmol), 4,4,5,5-tetramethyl-2-(tetramethyl-1,3,2-dioxaborane-2-yl)-1,3,2-dioxaborane (7.62 g, 30 mmol), and potassium acetate (9.81 g, 10 mmol) were dissolved in 1,4-dioxane (200 mL), and Pd(dppf)₂Cl₂ (300 mg) was added as a catalyst. The mixture was stirred at 85 °C for 36 hours under a N₂ atmosphere. After cooling to room temperature, potassium acetate was washed away with deionized water (40 mL), and the organic layer was extracted with dichloromethane. Finally, intermediate M7 (2.90 g, 79% yield) was obtained by column chromatography (dichloromethane:petroleum ether = 1:4). Theoretical mass spectrometry value: M W367.26, measured m / z = 366 [M] + . 1 H NMR (500MHz, CD2Cl2) δ8.59(s,2H),8.22(d,J=7.7Hz,2H),7.99(d,J=8.0Hz,2H),7.67–7.60(m,2H),7.47–7.40(m,2H),1.47(s,12H).

[0124] (2) Synthesis of intermediate M8

[0125] [Reaction 12]

[0126]

[0127] 4,9-Dibromonaphthyl[2,3-c][1,2,5]thiadiazole (2.41 g, 7 mmol), M7 (2.86 g, 7.8 mmol), and K2CO3 (5.5 g) were dissolved in toluene (15 mL), THF (10 mL), and deionized water (10 mL), with Pd(PPh3)4 (15 mg) added as a catalyst. The mixture was stirred at 90 °C for 36 hours under a N2 atmosphere. After cooling to room temperature, potassium carbonate was washed away with deionized water (30 mL), and the organic layer was extracted with dichloromethane. Finally, intermediate M8 (2.12 g, 60% yield) was obtained by column chromatography (dichloromethane:petroleum ether = 1:4). Theoretical mass spectrometry value: M W 504.41, measured m / z = 504.54 [M] + . 1 H NMR(500MHz,CD2Cl2)δ8.56(d,J=9.2Hz,1H),8.30(s,2H),8.23(d,J=8.1Hz,2H ),8.13–8.07(m,3H),7.73–7.67(m,2H),7.67–7.64(m,1H),7.49–7.41(m,3H).

[0128] (2) Synthesis of compound 22

[0129] [Reaction Formula 13]

[0130]

[0131] M8 (1.00 g, 2 mmol), 4-(1-phenyl-1H-benzimidazol-2-yl)phenylboronic acid (0.75 g, 2.4 mmol), and K2CO3 (5.5 g) were dissolved in toluene (15 mL), THF (10 mL), and deionized water (10 mL), with Pd(PPh3)4 (15 mg) added as a catalyst. The mixture was stirred at 90 °C for 36 hours under a N2 atmosphere. After cooling to room temperature, potassium carbonate was washed away with deionized water (30 mL), and the organic layer was extracted with dichloromethane. Finally, column chromatography (dichloromethane:petroleum ether = 1:1) yielded compound 22 (0.86 g, 62% yield). Theoretical mass spectrometry value: M W 693.83, measured m / z = 693.01 [M] + . 1 H NMR (500MHz, CD2Cl2) δ8.35(s,2H),8.24(d,J=7.7Hz,2H),8.14–8.05(m,4H),7.94(d,J=8.2Hz,3H),7.73(d,J=8.3Hz,2H),7.72 –7.65(m,4H),7.65–7.59(m,1H),7.58–7.54(m,2H),7.48–7.45(m,2H),7.45–7.41(m,2H),7.41–7.35(m,2H),7.35–7.32(m,1H).

[0132] Example 6 Synthesis of Compound 42

[0133] (1) Synthesis of compound 42

[0134] [Reaction Formula 14]

[0135]

[0136] Similar to the synthesis of compound 22, M8 and M6 were coupled to synthesize compound 42 (0.98 g, yield 63%). Theoretical mass spectrometry value: MW 793.95, measured m / z = 793.54 [M]. + . 1H NMR (500MHz, CD2Cl2) δ8.93(d,J=9.1Hz,1H),8.87(d,J=8.2Hz,1H),8.81(d,J=8.5H z,1H),8.36(s,2H),8.25(d,J=7.6Hz,2H),8.15–8.06(m,4H),7.97(d,J=8.2Hz,2H) ,7.84(t,J=7.4Hz,1H),7.81–7.75(m,5H),7.73(d,J=8.3Hz,3H),7.72–7.67(m,2H) ,7.60(t,J=7.7Hz,1H),7.50–7.44(m,3H),7.44–7.34(m,2H),7.28(d,J=8.4Hz,1H).

[0137] Example 7 Synthesis of Compound 43

[0138] (1) Synthesis of intermediate M9

[0139] [Reaction Formula 15]

[0140]

[0141] Similar to the synthesis of intermediate M5, intermediate M9 (8.04 g, 85% yield) was synthesized by replacing aniline with p-cyanoaniline in the reaction formula. Theoretical mass spectrometry value: MW 473.05, measured m / z = 472.83 [M]. + . 1 H NMR (500MHz, DMSO) δ8.96(d,J=8.3Hz,1H),8.90(d,J=8.3Hz,1H),8.69(dd,J=8.0,1.2Hz,1H),8.27–8.13(m,2H),8.06–7.96(m, 2H),7.82–7.76(m,1H),7.75–7.68(m,1H),7.63–7.55(m,3H),7.49–7.45(m,2H),7.44–7.38(m,1H),7.07(dd,J=8.3,0.7Hz,1H).

[0142] (2) Synthesis of intermediate M10

[0143] [Reaction Formula 16]

[0144]

[0145] Similar to the synthesis method of intermediate M6, intermediate M10 (6.41 g, yield 82%) was synthesized. Theoretical mass spectrometry value: MW 521.23, measured m / z = 521.91 [M]. + .1 H NMR (500MHz, DMSO) δ8.96(d,J=8.3Hz,1H),8.90(d,J=8.4Hz,1H),8.70(dd,J=7.9,1.1Hz,1H),8.22–8.13(m,2H),8.03–7.96(m,2H),7.83–7.76(m,1 H),7.74–7.68(m,1H),7.66(d,J=8.3Hz,2H),7.63–7.57(m,1H),7.54(d,J =8.2Hz,2H),7.45–7.38(m,1H),7.09(dd,J=8.3,0.7Hz,1H),1.31(s,12H).

[0146] (3) Synthesis of compound 43

[0147] [Reaction Formula 17]

[0148]

[0149] Similar to the synthesis of compound 22, M8 and M10 were coupled to synthesize compound 42 (0.96 g, yield 59%). Theoretical mass spectrometry value: MW 818.96, measured m / z = 818.54 [M]. + . 1 H NMR (500MHz, CD2Cl2) δ8.94(d,J=7.4Hz,1H),8.89(d,J=8.4Hz,1H),8.82(d,J=8.3 Hz,1H),8.36(s,2H),8.25(d,J=7.6Hz,2H),8.18–8.12(m,1H),8.12–8.06(m,5H),7 .90(dd,J=11.2,8.4Hz,4H),7.87–7.83(m,1H),7.81–7.74(m,3H),7.73–7.68(m,2 H),7.67–7.61(m,1H),7.51–7.44(m,3H),7.44–7.37(m,2H),7.23(d,J=7.7Hz,1H).

[0150] Compounds 2-21 and 23-210 can be synthesized similarly to compounds 1 and 22.

[0151] Application Examples: Fabrication and Characterization of Undoped Electroluminescent Devices

[0152] ITO glass plate preparation: First, soak the plate in a 1:1 mixture of deionized water and ethanol for 4 hours. Then, wipe it clean with lint-free paper. Perform two cycles of ultrasonic cleaning using a clean solvent of ethanol-toluene-acetone-isopropanol. Finally, immerse the glass substrate in isopropanol. Before transferring it to the glove box, purge any residual organic solvent from the ITO glass plate with nitrogen gas, then irradiate it with UV light for 20 minutes. Afterward, transfer it to a vacuum evaporation oven for vapor deposition.

[0153] Organic electroluminescent devices were prepared by vapor deposition using compounds 1, 3, 9, 22, 32, 42, and 43 from the examples, doped with CBP, as the light-emitting layer, according to the following bottom-to-top structure:

[0154] ITO / HATCN (5nm) / TAPC (10nm) / TCTA (10nm) / 20wt% compound 1-doped CBP (20nm) / TPBi (50nm) / LiF (1nm) / Al (100nm);

[0155] ITO / HATCN (5nm) / TAPC (10nm) / TCTA (10nm) / 20wt% compound 3-doped CBP (20nm) / TPBi (50nm) / LiF (1nm) / Al (100nm);

[0156] ITO / HATCN (5nm) / TAPC (10nm) / TCTA (10nm) / 15wt% compound 9 doped CBP (20nm) / TPBi (50nm) / LiF (1nm) / Al (100nm);

[0157] ITO / HATCN (5nm) / TAPC (10nm) / TCTA (10nm) / 20wt% compound 32 doped CBP (20nm) / TPBi (50nm) / LiF (1nm) / Al (100nm);

[0158] ITO / HATCN (5nm) / TAPC (10nm) / TCTA (10nm) / 5wt% compound 22 doped CBP (20nm) / TPBi (50nm) / LiF (1nm) / Al (100nm);

[0159] ITO / HATCN (5nm) / TAPC (20nm) / TCTA (10nm) / 10wt% compound 42 doped CBP (20nm) / TPBi (40nm) / LiF (1nm) / Al (100nm);

[0160] ITO / HATCN (5nm) / TAPC (15nm) / TCTA (10nm) / 5wt% compound 43 doped CBP (20nm) / TPBi (45nm) / LiF (1nm) / Al (100nm);

[0161] HATCN is a hole-injection layer with a deposition rate of 0.2-0.4 As. -1 TAPC is a hole transport layer, with a deposition rate of 3.0 As. -1 TCTA is a hole-blocking layer, deposited at a rate of 3.0 As. -1 TPBi is the electron transport layer, and the deposition rate is 1.25 As. -1 The LiF layer was used for electron injection, and the deposition rate was 0.5 As. -1 Al is the cathode, and the deposition rate is 15As. -1 .

[0162] The material structures of HATCN, TAPC, TCTA, TPBi, and CBP are as follows:

[0163]

[0164] A DC voltage was applied to the fabricated organic electroluminescent device, and its luminescence performance was tested using a Spectrascan PR650 luminance meter. The current-voltage characteristics were measured using a computer-controlled Keithley 2400 digital source meter. As luminescence characteristics, the electroluminescence spectrum and current efficiency (cdA) under varying applied DC voltage were determined. -1 CIE color coordinates, external quantum efficiency (%), power efficiency (lm W) -1 Maximum brightness (cd m) -2 ).

[0165] The external quantum efficiency-luminescence spectrum, current density-voltage-luminescence curve, and current efficiency-luminescence-power efficiency curve of the undoped organic electroluminescent device prepared using the compound of the examples as the emitting layer are shown below. Figures 1-6 As shown in Table 1, its electroluminescence properties are as follows.

[0166] Table 1 Performance of red organic light-emitting devices doped with the compounds

[0167]

[0168] As can be seen from the electroluminescence performance of the above embodiments, doped devices prepared by using this type of material and CBP doping as the light-emitting layer can produce a series of orange-red to red electroluminescent devices with electroluminescence peaks in the range of 596nm-664nm. These electroluminescent devices also possess advantages such as low turn-on voltage, high brightness, and high luminous efficiency. In particular, the doped device based on compound 1 exhibits a red electroluminescence spectrum of 620nm, color coordinates of (0.60, 0.40), and an external quantum efficiency of 14.24%, placing its device performance at an advanced level among red-light devices.

[0169] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the claims of the present invention; and such modifications or substitutions are still within the scope defined by the claims of the present invention.

Claims

1. A compound represented by Formula I, (I) in, B1 is selected from or ; R1 and R2 are the same and are selected from hydrogen, methyl, or ethyl. To ; D1, D2, D4, and D5 are hydrogen; D3 is selected from , , , , , , , ; X1is selected from phenyl, , , , , , , , ; X2 is either C or Si; X3 is either O or S.

2. The compound according to claim 1, wherein, Compounds of Formula I are selected from the following structures: 。 3. The use of the compound of claim 1 or 2 in the preparation of organic electroluminescent materials, organic electroluminescent devices or display devices.

4. The use of claim 3, wherein, The organic electroluminescent device comprises: a hole injection layer, a hole transport layer, a hole blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer connected sequentially on one side of the anode injection layer; the light-emitting layer contains at least one compound selected from claims 1 or 2.

5. An article comprising at least one compound selected from claims 1 or 2, wherein the article is an organic electroluminescent material, an organic electroluminescent device, or a display device.

6. The article of claim 5, wherein, The organic electroluminescent device comprises: a hole injection layer, a hole transport layer, a hole blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer connected sequentially on one side of the anode injection layer; the light-emitting layer contains at least one compound selected from claims 1 or 2.

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