A tetraphenylbenzene derivative with high level of dipole orientation and its preparation method and application

Abstract

The application discloses a kind of high level dipole orientation tetraphenyl benzene derivatives and its preparation method and application, the tetraphenyl benzene derivative has structure shown in formula (I):In formula (I), any two of R1, R2, R3, R4 Four groups are each independently selected from N-containing electron-donating group, and the other two are each independently selected from electron-withdrawing group.The tetraphenyl benzene derivative is prepared using two-step suzuki coupling reaction.The tetraphenyl benzene derivative of the application has excellent solid-state light emitting efficiency and high molecular level dipole orientation, and can be used as non-doped light-emitting layer to prepare non-doped blue light organic electroluminescent device with high efficiency, low degree of efficiency roll-off, low start voltage, with maximum external quantum efficiency reaching 8.32%, which is greatly improved compared with prior art, and has wide application prospect in the field of organic optoelectronics.

Description

Technical Field

[0001] This invention belongs to the field of organic light-emitting materials technology, and particularly relates to tetraphenylbenzene derivatives that can be used in organic light-emitting materials. Specifically, it relates to a high-level dipole-oriented tetraphenylbenzene derivative, its preparation method, and its application. Background Technology

[0002] Organic light-emitting diodes (OLEDs) play a crucial role in white lighting and full-color displays. Compared to red and green OLEDs, highly efficient and stable blue OLEDs are extremely rare, primarily due to the lack of effective blue light materials. Currently, commercially available blue light materials are anthracene-based fluorescent materials. However, these anthracene-based materials often exhibit aggregation-induced fluorescence quenching (ACQ) effects, where fluorescence intensity decreases or disappears with increasing aggregation. Therefore, in practical applications, traditional fluorescent materials need to be doped into specific host matrices. However, host-guest doping techniques require precise control of doping concentration and suffer from drawbacks such as phase separation and poor repeatability. Furthermore, the host material for deep blue fluorescent materials requires stringent conditions, such as high triplet energy levels, excellent electron-hole transport capabilities, and energy level matching.

[0003] Based on the highly efficient light-emitting properties of aggregation-induced emission (AIE) materials in both aggregated and solid states, it is hoped that the key ACQ (external quantum efficiency) problem faced by traditional organic light-emitting materials can be fundamentally solved. This would facilitate the construction of high-performance undoped deep blue OLED devices without the need for complex device structures or doping processes, resulting in low manufacturing costs. However, currently only a relatively small number of AIE molecules can be used in undoped deep blue OLEDs, and their device efficiency is far from meeting the requirements of practical applications. Therefore, designing blue light-emitting materials with simple structures and improving their performance (especially maximum external quantum efficiency) remains a significant challenge.

[0004] The external quantum efficiency of a device is mainly controlled by three factors: the luminescence efficiency of the emitting layer material, the exciton utilization rate of the emitting layer material, and the optical coupling extraction of the device. AIE materials, due to their high solid-state luminescence efficiency, can be used to fabricate undoped devices; the exciton utilization rate of the material mainly depends on the utilization of triplet excitons; and the optical coupling extraction of the device can be improved by increasing the horizontal dipole orientation efficiency of the molecules. Therefore, designing blue light-emitting materials with simple structures and high luminescence efficiency remains a significant challenge. Summary of the Invention

[0005] To overcome the problems existing in the prior art, this invention provides a high-level dipole-oriented tetraphenylbenzene derivative, its preparation method, and its application. This derivative uses the AIE chromophore tetraphenylbenzene as a backbone, with different bi-donor units or bi-acceptor units connected at the ortho, meta, or para positions. This tetraphenylbenzene derivative exhibits efficient solid-state blue light emission. At the same time, it has a high level of luminescent dipole orientation under its solid film, and can be used as an undoped luminescent layer for the preparation of organic electroluminescent devices, showing broad application prospects in the field of organic optoelectronics.

[0006] One objective of this invention is to provide a high-level dipole-oriented tetraphenylbenzene derivative having the structure shown in formula (I):

[0007]

[0008] In formula (I), any two of the four groups R1, R2, R3, and R4 are independently selected from N-containing electron-donating groups, and the other two are independently selected from electron-withdrawing groups; preferably, the two groups selected from N-containing electron-donating groups are the same, and the two groups selected from electron-withdrawing groups are the same.

[0009] The tetraphenylbenzene derivatives of this invention use tetraphenylbenzene as a backbone to connect different donor units (containing N electron-donating groups) and acceptor units (electron-withdrawing groups).

[0010] In a preferred embodiment, the N-containing electron-donating group is selected from any one of aromatic amino group, cycloaromatic amino group, aromatic amine-substituted aryl group, and cycloaromatic amine-substituted aryl group.

[0011] In a further preferred embodiment, the aromatic amino group is selected from any of the groups shown in the following formula:

[0012]

[0013] Among them, R ’ It is selected from any one of hydrogen, methoxy, fluorine, C1 to C20 alkyl (preferably C1 to C10 alkyl), and C1 to C20 substituted alkyl (preferably C1 to C10 substituted alkyl), where * indicates the substitution position.

[0014] In a further preferred embodiment, the cycloarylamine group is selected from any one of the groups shown in the following formula:

[0015]

[0016] Among them, R ’ It is selected from any one of hydrogen, methoxy, fluorine, C1 to C20 alkyl (preferably C1 to C10 alkyl), and C1 to C20 substituted alkyl (preferably C1 to C10 substituted alkyl), where * indicates the substitution position.

[0017] In this invention, the aromatic amine refers to an aryl group connected to an N-containing straight chain or a straight chain, wherein the aryl group optionally contains elements such as S, O, and N; the cyclic aromatic amine refers to an aryl group connected to an N-containing heterocycle, wherein the aryl group optionally contains elements such as S, O, and N, and the N-containing heterocycle optionally also contains elements such as S or O.

[0018] In a further preferred embodiment, the aryl group substituted by the aromatic amine is selected from any of the groups shown in the following formula:

[0019]

[0020] Among them, R ’ It is selected from any one of hydrogen, methoxy, fluorine, C1 to C20 alkyl (preferably C1 to C10 alkyl), and C1 to C20 substituted alkyl (preferably C1 to C10 substituted alkyl), where n is a natural number from 1 to 10, and * indicates the substitution position.

[0021] In a further preferred embodiment, the aryl group substituted by the cycloarylamine is selected from any of the groups shown in the following formula:

[0022]

[0023] Among them, R ’ It is selected from any one of hydrogen, methoxy, fluorine, C1 to C20 alkyl (preferably C1 to C10 alkyl), and C1 to C20 substituted alkyl (preferably C1 to C10 substituted alkyl), where n is a natural number from 1 to 10, and * indicates the substitution position.

[0024] In this invention, the C1 to C20 alkyl groups can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl, or C10 alkyl, etc. n is a natural number from 1 to 10, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0025] In a preferred embodiment, the electron-withdrawing group is selected from any of the groups shown in the following formula:

[0026]

[0027] Wherein, R” is selected from hydrogen atom, tert-butyl, cyano, fluorine atom, trifluoromethyl or alkyl chain, m is a natural number from 0 to 10, and * is the substitution position.

[0028] In a further preferred embodiment, the electron-withdrawing group is selected from any of the following groups:

[0029]

[0030] Wherein, R” is selected from cyano or trifluoromethyl, m is a natural number from 0 to 5 (e.g., m = 0), and * indicates the substitution position.

[0031] In a further preferred embodiment, the electron-withdrawing group is selected from cyano or trifluoromethyl.

[0032] In this invention, m can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0033] In a preferred embodiment, the high-level dipole-oriented tetraphenylbenzene derivative has the structure shown in formula (II), formula (III), or formula (IV), preferably the structure shown in formula (II) or formula (III), and more preferably the structure shown in formula (II):

[0034]

[0035] In equations (II), (III), and (IV), R a Selected from the N-containing electron-donating group, R b Selected from the electron-withdrawing groups.

[0036] Among them, the inventors found through a large number of experiments that the compound shown in formula (II) has the best blue light performance (e.g., maximum external quantum efficiency), followed by the compound shown in formula (III).

[0037] In a further preferred embodiment, the high-level dipole-oriented tetraphenylbenzene derivative has the structure shown in formula (II'), formula (III'), or formula (IV'), preferably the structure shown in formula (II') or formula (III'), and more preferably the structure shown in formula (II'):

[0038]

[0039] In equations (II'), (III'), and (IV'), R a Selected from the N-containing electron-donating group, R b Selected from the electron-withdrawing group, for example, selected from cyano or trifluoromethyl.

[0040] In this invention, the carrier transport properties of tetraphenylbenzene derivatives are modulated by attaching different double electron-donating and double electron-withdrawing groups (e.g., cyano or trifluoromethyl) to the tetraphenylbenzene backbone, thus constructing donor-acceptor (DA) type compounds. The twisted tetraphenylbenzene effectively avoids the formation of intermolecular π-π stacking, which is detrimental to luminescence. Furthermore, DA type compounds readily form intermolecular interactions, thereby restricting molecular motion in the aggregated state and enabling them to exhibit high luminescence efficiency even in the aggregated state. Attaching different double electron-donating and acceptor groups at different positions facilitates the control of molecular-level dipole orientation in the solid-state thin film of the derivative. Devices fabricated from films with high-level molecular dipole orientation are more likely to achieve high device efficiency. In addition, changing the substituent positions of such derivatives also helps to control the high-energy thermal exciton processes of this type of material, regulating the exciton utilization rate and thus improving device efficiency.

[0041] A second objective of this invention is to provide a method for preparing a high-level dipole-oriented tetraphenylbenzene derivative, preferably used for preparing the high-level dipole-oriented tetraphenylbenzene derivative described in one objective of this invention. The preparation method includes:

[0042] (1) The compound shown in formula (i) reacts with phenylboronic acid substituted with electron-withdrawing groups to give an intermediate;

[0043] (2) The intermediate reacts with phenylboronic acid substituted with N-donating groups to obtain the high-level dipole-oriented tetraphenylbenzene derivative.

[0044]

[0045] In equation (i), R 1 R 2 R 3 R 4 Any two of the four groups are selected from iodine substituents, and the other two are selected from bromine substituents.

[0046] The reactions described in steps (1) and (2) are Suzuki coupling reactions.

[0047] In this invention, the compound represented by formula (i) is selected from the compounds represented by formula (i-1), formula (i-2), or formula (i-3), preferably from the compounds represented by formula (i-1) or formula (i-2), and more preferably from the compound represented by formula (i-1):

[0048]

[0049] In a preferred embodiment, the electron-withdrawing group-substituted phenylboronic acid has the same definition as the electron-withdrawing group in one of the objects of the present invention. Preferably, the electron-withdrawing group-substituted phenylboronic acid is selected from at least one of the compounds shown in formula (ii-1), and more preferably from at least one of the compounds shown in formula (ii-2).

[0050]

[0051] In equations (ii-1) and (ii-2), R b Selected from electron-withdrawing groups as described in one of the purposes of this invention.

[0052] Preferably, the electron-withdrawing group is selected from any one of the following groups:

[0053]

[0054] Wherein, R” is selected from hydrogen atom, tert-butyl, cyano, fluorine atom, trifluoromethyl or alkyl chain, m is a natural number from 0 to 10, and * is the substitution position.

[0055] More preferably, the electron-withdrawing group is selected from any of the following groups:

[0056]

[0057] Wherein, R” is selected from cyano or trifluoromethyl, m is a natural number from 0 to 5 (e.g., m = 0), and * indicates the substitution position.

[0058] Most preferably, the electron-withdrawing group is selected from cyano or trifluoromethyl.

[0059] In this invention, m can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0060] In a preferred embodiment, the N-electron-donating group-substituted phenylboronic acid has the same definition as the N-electron-donating group in one of the objectives of this invention. Preferably, the N-electron-donating phenylboronic acid is selected from at least one of the compounds shown in formula (iii-1), and more preferably from at least one of the compounds shown in formula (iii-2).

[0061]

[0062] In equations (iii-1) and (iii-2), R a Selected from the N-containing electron-donating groups described in one of the purposes of this invention.

[0063] Preferably, the N-containing electron-donating group is selected from any one of aromatic amino group, cycloaromatic amino group, aromatic amine-substituted aryl group, and cycloaromatic amine-substituted aryl group.

[0064] More preferably:

[0065] (A) The aromatic amino group is selected from any of the groups shown in the following formula:

[0066]

[0067] Wherein, R' is selected from any one of hydrogen, methoxy, fluorine, C1-C20 alkyl (preferably C1-C10 alkyl), and C1-C20 substituted alkyl (preferably C1-C10 substituted alkyl), and * indicates the substitution position.

[0068] (B) The cyclic aromatic amino group is selected from any of the groups shown in the following formula:

[0069]

[0070] Wherein, R' is selected from any one of hydrogen, methoxy, fluorine, C1-C20 alkyl (preferably C1-C10 alkyl), and C1-C20 substituted alkyl (preferably C1-C10 substituted alkyl), and * indicates the substitution position.

[0071] (C) The aryl group substituted by the aromatic amine is selected from any of the groups shown in the following formula:

[0072]

[0073] Wherein, R' is selected from any one of hydrogen, methoxy, fluorine, C1 to C20 alkyl (preferably C1 to C10 alkyl), and C1 to C20 substituted alkyl (preferably C1 to C10 substituted alkyl), n is a natural number from 1 to 10, and * indicates the substitution position.

[0074] (D) The aryl group substituted by the cyclic aromatic amine is selected from any of the groups shown in the following formula:

[0075]

[0076] Wherein, R' is selected from any one of hydrogen, methoxy, fluorine, C1 to C20 alkyl (preferably C1 to C10 alkyl), and C1 to C20 substituted alkyl (preferably C1 to C10 substituted alkyl), n is a natural number from 1 to 10, and * indicates the substitution position.

[0077] In this invention, the C1 to C20 alkyl groups can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl, or C10 alkyl, etc. n is a natural number from 1 to 10, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0078] In a preferred embodiment, in step (1), the molar ratio of the compound shown in formula (i) to the electron-withdrawing group-substituted phenylboronic acid is 1:(2 to 2.5), preferably 1:(2.1 to 2.3), for example 1:2.1, 1:2.15, 1:2.2, 1:2.25, 1:2.3, 1:2.4 or 1:2.5.

[0079] In a preferred embodiment, the reaction in step (1) is carried out in the presence of a base and a palladium-based compound.

[0080] In a further preferred embodiment, in step (1), the alkali is selected from at least one of alkali metal hydroxides, alkaline earth metal hydroxides, and alkali metal carbonates, preferably from at least one of alkali metal carbonates (e.g., Cs2CO3, K2CO3, Na2CO3, Li2CO3); and / or, the palladium-based compound is selected from at least one of tetrakis(triphenylphosphine)palladium and tetrakis(triphenylphosphine)palladium dichloride.

[0081] In a further preferred embodiment, in step (1), the molar ratio of the base to the compound shown in formula (i) is (1-5):1, preferably (2-4):1, for example 3:1; and / or, the molar ratio of the palladium-based compound to the compound shown in formula (i) is (0.01-0.1):1, preferably (0.02-0.08):1, for example 0.02, 0.03, 0.04, 0.05, 0.06, 0.07 or 0.08.

[0082] The molar amount of the compound in formula (i) is expressed as molecular molar amount.

[0083] In a preferred embodiment, the reaction temperature in step (1) is 66-80°C, preferably 76-80°C, for example 66°C, 68°C, 70°C, 72°C, 75°C, 78°C or 80°C.

[0084] In a preferred embodiment, the reaction in step (1) is carried out under a protective atmosphere, such as nitrogen and / or an inert atmosphere.

[0085] In a preferred embodiment, a post-processing is performed after the reaction described in step (1), the post-processing including extraction, concentration and silica gel column chromatography.

[0086] In a further preferred embodiment, at least one of dichloromethane and ethyl acetate is used for extraction.

[0087] Extraction can remove water, inorganic bases, catalysts, and some salts generated in the reaction.

[0088] In a preferred embodiment, in step (2), the molar ratio of the intermediate to the phenylboronic acid substituted with an N-donating group is 1:(2.1-3), for example 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3, preferably 1:(2.3-2.8), more preferably 1:(2.3-2.5).

[0089] In a preferred embodiment, the reaction in step (2) is carried out in the presence of a base and a palladium-based compound.

[0090] In a further preferred embodiment, in step (2), the alkali is selected from at least one of alkali metal hydroxides, alkaline earth metal hydroxides, and alkali metal carbonates, preferably from at least one of alkali metal carbonates (e.g., Cs2CO3, K2CO3, Na2CO3, Li2CO3); and / or, the palladium-based compound is selected from at least one of tetrakis(triphenylphosphine)palladium and tetrakis(triphenylphosphine)palladium dichloride.

[0091] In a further preferred embodiment, in step (2), the molar ratio of the base to the intermediate is 1:(1-5), preferably 1:(2-4), for example 1:1, 1:2, 1:3, 1:4 or 1:5; and / or, the molar ratio of the palladium-based compound to the intermediate is (0.02-1):1, preferably (0.05-0.5):1, for example 0.02:1, 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1.

[0092] The molar amount of the intermediate is expressed as its molecular molar amount.

[0093] In a preferred embodiment, the reaction temperature in step (2) is 66-80°C, preferably 76-80°C, for example 66°C, 68°C, 70°C, 72°C, 75°C, 78°C or 80°C.

[0094] In a preferred embodiment, the reaction in step (2) is carried out under a protective atmosphere, such as nitrogen and / or an inert atmosphere.

[0095] In a preferred embodiment, a post-processing is performed after the reaction described in step (2), the post-processing including extraction, concentration and silica gel column chromatography.

[0096] In a further preferred embodiment, at least one of dichloromethane and ethyl acetate is used for extraction.

[0097] Extraction can remove water, inorganic bases, catalysts, and some salts generated in the reaction.

[0098] In this invention: in step (1), the electron-withdrawing group-substituted phenylboronic acid first undergoes a Suzuki coupling reaction with the two iodine substituents in the compound shown in formula (i) to obtain an intermediate; in step (2), the N-electron-donating group-substituted phenylboronic acid then undergoes a Suzuki coupling reaction with the two bromine substituents on the intermediate to obtain the high-level dipole-oriented tetraphenylbenzene derivative.

[0099] A third objective of this invention is to provide the application of the high-level dipole-oriented tetraphenylbenzene derivatives described in the first objective of this invention, or the high-level dipole-oriented tetraphenylbenzene derivatives obtained by the preparation method described in the second objective of this invention, in organic electroluminescent devices, preferably as undoped light-emitting layers.

[0100] The tetraphenylbenzene derivatives with high-level dipole orientation described in this invention have excellent solid-state luminescence efficiency and high molecular-level dipole orientation. They can be used as a single luminescent layer to prepare undoped electroluminescent devices with good photoelectric performance, simple structure, and low cost. They have broad application prospects in the field of organic electroluminescence and are expected to be widely used in flat panel displays and solid-state lighting.

[0101] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0102] Compared with the prior art, the present invention has the following beneficial effects:

[0103] (1) The present invention uses a two-step Suzuki coupling reaction to prepare the high-level dipole-oriented tetraphenylbenzene derivatives. The synthesis method is simple, the raw materials are readily available, and the yield is high. The high-level dipole-oriented tetraphenylbenzene derivatives have stable structures and are easy to store.

[0104] (2) The high-level dipole-oriented tetraphenylbenzene derivatives prepared in this invention use tetraphenylbenzene as a backbone, with different bi-donor units and bi-acceptor units connected at different positions. By regulating the molecular structure, the solid-state fluorescence quantum yield and molecular-level dipole orientation of the material can be controlled, achieving high-efficiency solid-state blue light emission and excellent molecular-level dipole orientation, with the maximum horizontal dipole orientation reaching 85.5%. In addition, these derivatives have bipolar electron and hole transport characteristics and excellent electroluminescence performance.

[0105] (3) The tetraphenylbenzene derivatives of the present invention have excellent solid-state luminescence efficiency and high molecular-level dipole orientation. They can be used as undoped light-emitting layers to prepare high-efficiency, low-degree efficiency roll-off and low-start-up voltage undoped blue organic electroluminescent devices. The maximum external quantum efficiency reaches 8.32%, which is a great improvement compared with the prior art (it is well known to those in the art that even a slight improvement in the maximum external quantum efficiency is very rare, but this application has achieved a great improvement). It has a wide range of application prospects in the field of organic optoelectronics. Attached Figure Description

[0106] Figure 1 The image shows the angle-dependent fluorescence spectrum of the undoped thin film prepared using TPB-2AC.

[0107] Figure 2 The current density, brightness and voltage curves (JVL curves) of the undoped blue OLED device fabricated using TPB-2AC are shown.

[0108] Figure 3 The graph shows the efficiency of an undoped blue OLED device fabricated using TPB-2AC as a function of brightness.

[0109] Figure 4 Angle-dependent fluorescence spectra of undoped thin films prepared using iTPB-2AC;

[0110] Figure 5 The JVL curve of the undoped blue OLED device fabricated using iTPB-2AC is shown.

[0111] Figure 6 The graph shows the efficiency of an undoped blue OLED device fabricated using iTPB-2AC as a function of brightness.

[0112] Figure 7 The JVL curve of an undoped blue OLED device fabricated using DPA-TPB-CN is shown.

[0113] Figure 8 This is a graph showing the efficiency of an undoped blue OLED device fabricated using DPA-TPB-CN as a function of brightness. Detailed Implementation

[0114] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0115] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0116] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0117] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0118] 1,2-Dibromo-4,5-diiodobenzene and 1,4-dibromo-2,5-diiodobenzene were purchased from Dalian Jindian Biotechnology Co., Ltd.

[0119] It should be noted that when the material of this invention is applied to OLED devices, the solid film is prepared by vapor deposition rather than solution spin coating (for example, the prior art CN110105244A uses solution spin coating to prepare the film). These two different film preparation methods result in a significant difference in blue light performance, possibly because the different molecular stacking methods have a substantial impact on light emission. Therefore, films obtained using different methods are not comparable in performance.

[0120]

Example 1

[0121] In this embodiment, the structural formula of the high-level dipole-oriented tetraphenylbenzene derivative (TPB-2AC) is shown below:

[0122]

[0123] The synthesis route is as follows:

[0124]

[0125] (1) 1,2-Dibromo-4,5-diiodobenzene (9.7 g, 20.0 mmol), 4-cyanobenzoboronic acid (6.4 g, 44.0 mmol), anhydrous potassium carbonate (8.3 g, 60.0 mmol) and Pd(PPh3)4 (1.2 g, 1.0 mmol) were added to a 50 mL reaction flask. Under nitrogen protection, 120 mL of tetrahydrofuran (THF) and 30 mL of water were added and the mixture was refluxed overnight. After the reaction was cooled, it was extracted with dichloromethane, concentrated, and then column-pressed to obtain intermediate 1-1 with a yield of 87%.

[0126] (2) Intermediate 1-1 (1.3 g, 3.0 mmol), triphenylamine 4-borate (1.94 g, 7.0 mmol), anhydrous potassium carbonate (1.2 g, 9.0 mmol) and Pd(PPh3)4 (173 mg, 0.15 mmol) were added to a 100 mL reaction flask. Under nitrogen protection, 18 mL of THF and 3 mL of water were added, and the mixture was refluxed overnight. After the reaction was cooled, it was extracted with dichloromethane, concentrated, and then column-pressed to obtain a white solid TPB-2AC with a yield of 94%.

[0127] The product identification data are as follows: 1 H NMR (500MHz, CDCl3) δ (TMS, ppm): 7.57 (d, 4H), 7.49 (s, 2H), 7.30 (d, 4H), 7.29-7.25 (m, 8H), 7.09 (m, 12H), 7.05 (m, 4H, 6.98 (d, 4H). 13 C NMR (125MHz, CDCl3) δ (TMS, ppm): 147.53, 146.95, 145.20, 140.90, 137.30, 133.96, 132.08, 132.50, 129.32, 123.10, 122.80, 118.64, 110.93. HRMS (C 56 H 38 N4):m / z 766.3104(M + ,calcd766.3096).

[0128]

Example 2

[0129] In this embodiment, the structural formula of the high-level dipole-oriented tetraphenylbenzene derivative (iTPB-2AC) is shown below:

[0130]

[0131] The synthesis route is as follows:

[0132]

[0133] (1) 1,4-Dibromo-2,5-diiodobenzene (9.7 g, 20.0 mmol), 4-cyanobenzoboronic acid (6.4 g, 44.0 mmol), anhydrous potassium carbonate (8.3 g, 60.0 mmol) and Pd(PPh3)4 (1.2 g, 1.0 mmol) were added to a 50 mL reaction flask. Under nitrogen protection, 120 mL of tetrahydrofuran (THF) and 30 mL of water were added and the mixture was refluxed overnight. After the reaction was cooled, it was extracted with dichloromethane, concentrated, and then subjected to column chromatography (i.e., the crude product was obtained after concentrating the organic phase, and then purified and separated by silica gel column chromatography) to obtain intermediate 1-2 with a yield of 85%.

[0134] (2) Intermediate 1-2 (1.3 g, 3.0 mmol), triphenylamine 4-borate (1.94 g, 7.0 mmol), anhydrous potassium carbonate (1.2 g, 9.0 mmol) and Pd(PPh3)4 (173 mg, 0.15 mmol) were added to a 100 mL reaction flask. Under nitrogen protection, 18 mL of THF and 3 mL of water were added, and the mixture was refluxed overnight. After the reaction was cooled, it was extracted with dichloromethane, concentrated, and then column-pressed to obtain a pale yellow solid iTPB-2AC with a yield of 96%.

[0135] The product identification data are as follows: 1 H NMR (500MHz, CD2Cl2) δ (TMS, ppm): 7.60 (d, 4H), 7.51 (s, 2H), 7.39 (d, 4H), 7.27 (m, 9H), 7.11-6.95 (m, 19H). 13 C NMR(125MHz,CD2Cl2)δ(TMS,ppm):149.14,148.63,142.35,142.05,138.83,136.94,133.37,131.60,131.41,131.34,13 1.22,130.87,130.67,128.46,127.91,127.25,126.38,125.90,124.75,124.60,124.59,124.39,121.54,121.35.HRMS(C 56 H 38 N4):m / z766.3088(M + ,calcd 766.3096).

[0136]

Example 3

[0137] In this embodiment, the structural formula of the high-level dipole-oriented tetraphenylbenzene derivative (TPB-2CzC) is shown below:

[0138]

[0139] The synthesis route is as follows:

[0140]

[0141] (1) Intermediate 1-1 was prepared in the same manner as in Example 1;

[0142] (2) Intermediate 1-1 (1.3 g, 3.0 mmol), 4-(9H-carbazole-9-yl)phenylboronic acid (2.0 g, 7.0 mmol), anhydrous potassium carbonate (1.2 g, 9.0 mmol) and Pd(PPh3)4 (173 mg, 0.15 mmol) were added to a 100 mL reaction flask. Under nitrogen protection, 18 mL of THF and 3 mL of water were added, and the mixture was refluxed overnight. After the reaction was cooled, it was filtered directly, washed with THF and dried to obtain a white solid TPB-2CzC with a yield of 90%.

[0143] Nuclear magnetic resonance (NMR) analysis confirmed the successful preparation of the tetraphenylbenzene derivative (TPB-2CzC).

[0144]

Example 4

[0145] In this embodiment, the structural formula of the high-level dipole-oriented tetraphenylbenzene derivative (iTPB-2CzC) is shown below:

[0146]

[0147] The synthesis route is as follows:

[0148]

[0149] (1) Intermediate 1-2 was prepared in the same manner as in Example 2;

[0150] (2) Intermediate 1-2 (428 mg, 1.5 mmol), 4-(9H-carbazole-9-yl)phenylboronic acid (1.08 g, 3.75 mmol), anhydrous potassium carbonate (621 mg, 4.5 mmol) and Pd(PPh3)4 (87 mg, 0.075 mmol) were added to a 100 mL reaction flask. Under nitrogen protection, 10 mL of THF and 3 mL of water were added, and the mixture was refluxed overnight. After the reaction cooled, it was filtered directly, washed with THF and dried to obtain a white solid iTPB-2CzC with a yield of 91%.

[0151] Nuclear magnetic resonance (NMR) analysis confirmed the successful preparation of the tetraphenylbenzene derivative (iTPB-2CzC).

[0152]

Example 5

[0153] In this embodiment, the structural formula of the high-level dipole-oriented tetraphenylbenzene derivative (iTPB-2PAC) is shown below:

[0154]

[0155] The synthesis route is as follows:

[0156]

[0157] (1) Intermediate 1-2 was prepared in the same manner as in Example 2;

[0158] (2) Intermediate 1-2 (1.3 g, 3.0 mmol), 4-(N,N-diamino)biphenyl-4"-boric acid (2.54 g, 7 mmol), anhydrous potassium carbonate (1.2 g, 9.0 mmol) and Pd(PPh3)4 (173 mg, 0.15 mmol) were added to a 100 mL reaction flask. Under nitrogen protection, 18 mL THF and 3 mL water were added, and the mixture was refluxed overnight. After the reaction was cooled, it was extracted with dichloromethane, concentrated, and then column-pressed to obtain a pale yellow solid iTPB-2PAC with a yield of 95%.

[0159] Nuclear magnetic resonance (NMR) analysis confirmed the successful preparation of the tetraphenylbenzene derivative (iTPB-2PAC).

[0160]

Example 6

[0161] In this embodiment, the process of embodiment 2 is repeated, with the difference being:

[0162] In step (1), 44 mmol of 4-cyanobenzoic acid was replaced with 42 mmol of 4-trifluoromethylphenylboronic acid, while other conditions in step (1) remained unchanged.

[0163] In step (2), 6.3 mmol of 4-boronic acid triphenylamine was used to replace 7.0 mmol of 4-boronic acid triphenylamine, while other conditions in step (2) remained unchanged.

[0164] The product was obtained by nuclear magnetic resonance characterization.

[0165]

Example 7

[0166] In this embodiment, the process of embodiment 3 is repeated, with the difference being:

[0167] In step (1), 46 mmol of 4-trifluoromethylphenylboronic acid was used to replace 44 mmol of 4-cyanobenonic acid in the preparation of intermediate 1-1, while other conditions in step (1) remained unchanged.

[0168] In step (2), 8.4 mmol of 4-(9H-carbazole-9-yl)phenylboronic acid was used to replace 7.0 mmol of 4-(9H-carbazole-9-yl)phenylboronic acid, while other conditions in step (2) remained unchanged.

[0169] The product was obtained by nuclear magnetic resonance characterization.

[0170]

Example 8

[0171] In this embodiment, the process of embodiment 5 is repeated, with the difference being:

[0172] In step (1), intermediate 1-2 is prepared by replacing 4-(9H-carbazole-9-yl)phenylboronic acid with an equimolar amount of 4-trifluoromethylphenylboronic acid, while other conditions in step (1) remain unchanged.

[0173] In step (2), 9.3 mmol of 4-(N,N-diamino)biphenyl-4"-boric acid was used to replace 7.0 mmol of 4-(N,N-diamino)biphenyl-4"-boric acid, while other conditions in step (2) remained unchanged.

[0174] The product was obtained by nuclear magnetic resonance characterization.

[0175]

Example 9

[0176] In this embodiment, the process of Example 1 was repeated, except that an equal amount of 1,3-dibromo-4,6-diiodobenzene (as shown below) was used to replace the 1,2-dibromo-4,5-diiodobenzene in step (1), while other conditions remained unchanged, to obtain mTPB-2AC. The product was characterized by NMR.

[0177]

[0178] Comparative Example 1

[0179] The comparative example shows the preparation of an organic electroluminescent material containing tetraphenylbenzene, with the structure shown in Formula A:

[0180]

[0181] The synthesis route is as follows:

[0182]

[0183]

[0184] (1) p-bromotriphenyl (compound 1) (6 g, 15.5 mmol), 4-cyanobenzonic acid (compound 2) (2.50 g, 17.0 mmol), anhydrous potassium carbonate (6.4 g, 46.5 mmol) and Pd(PPh3)4 (895 mg, 0.8 mmol) were added to a 250 mL reaction flask. Under nitrogen protection, 105 mL THF and 15 mL water were added and the mixture was refluxed overnight. After the reaction was cooled, it was extracted with dichloromethane, concentrated, and then passed through a column chromatography to obtain a white solid 3.

[0185] (2) White solid 3 (2.136 g, 1.5 mmol), compound 9 (1.127 g, 3.9 mmol), anhydrous potassium carbonate (1.616 g, 11.7 mmol) and Pd(PPh3)4 (225 mg, 0.195 mmol) were added to a 250 mL reaction flask. Under nitrogen protection, 10 mL THF and 5 mL water were added and the mixture was refluxed overnight. After the reaction was cooled, it was extracted with dichloromethane, concentrated, and then passed through a column to obtain white solid DPA-TPB-CN.

[0186]

Application Example 1

[0187] Application Example 1 tests the performance of the blue OLED device fabricated from the high-level dipole-oriented tetraphenylbenzene derivative (TPB-2AC) in Example 1:

[0188] Undoped blue light-emitting devices were fabricated using TPB-2AC, a tetraphenylbenzene derivative with high-level dipole orientation prepared in Example 1 (solid-state thin film fluorescence quantum yield = 86.7%, molecular-level dipole orientation up to 83.0%), as the luminescent material. The device performance was characterized and tested, and the results are shown in [Figure 1]. Figures 1-3 .

[0189] Device structure: ITO / HAT-CN (5nm) / TAPC (50nm) / TCTA (5nm) / TPB-2AC (20nm) / TmPyPB (40nm) / LiF (1nm) / Al (120nm).

[0190] The device fabrication process is as follows: The electroluminescent device is fabricated according to methods known in the art. Specifically, under high vacuum conditions, 5 nm of HAT-CN (hexaazatriphenylhexacarbonyl nitrile), 50 nm of TAPC 1,1'-bis(bis-4-tolylaminophenyl)cyclohexylamine, 5 nm of TCTA (4,4',4”-tris(carbazole-9-yl)triphenylamine), 20 nm of TPB-2AC, 40 nm of TmPyPB (1,3,5-tris[(3-pyridyl)-3-phenyl]benzene), 1 nm of LiF and 120 nm of Al are deposited sequentially on a cleaned conductive glass (ITO) substrate.

[0191] Figure 1 The image shows the angle-dependent fluorescence spectrum of the undoped thin film prepared using TPB-2AC. As can be seen from the figure, the molecular-level dipole orientation of TPB-2AC reaches 83.0%.

[0192] Figure 2This is a JVL curve (current density, brightness, and voltage) of an undoped blue OLED device fabricated using TPB-2AC. The curve shows that the TPB-2AC-based OLED device exhibits high maximum brightness and low start-up voltage, reaching 7601 cd / m². 2 2.6V.

[0193] Figure 3 This is a graph showing the efficiency of an undoped blue OLED device fabricated using TPB-2AC as a function of brightness. The graph shows that the undoped device based on TPB-2AC exhibits good efficiency with a roll-off effect, reaching a maximum external quantum efficiency of 5.92% at a brightness of 1000 cd / m². 2 At that time, the external quantum efficiency remained at 5.71%.

[0194]

Application Example 2

[0195] This application example tests the performance of the undoped deep blue OLED device based on the high-level dipole-oriented tetraphenylbenzene derivative (iTPB-2AC) prepared in Example 2:

[0196] Undoped blue light-emitting devices were fabricated using the high-level dipole-oriented tetraphenylbenzene derivative iTPB-2AC (solid-state thin film fluorescence quantum yield = 88.0%, molecular-level dipole orientation up to 85.5%) prepared in Example 2 as the luminescent material. The devices were then characterized and tested, and the results are shown in [Figure 1]. Figures 4-6 .

[0197] Device structure: ITO / HAT-CN (5nm) / TAPC (50nm) / TCTA (5nm) / iTPB-2AC (20nm) / TmPyPB (40nm) / LiF (1nm) / Al (120nm).

[0198] The device fabrication process is similar to that in Application Example 1.

[0199] Figure 4 The image shows the angle-dependent fluorescence spectrum of the undoped thin film prepared using iTPB-2AC. As can be seen from the figure, the molecular-level dipole orientation of iTPB-2AC reaches 85.5%.

[0200] Figure 5 The figure shows the JVL curve of the undoped blue OLED device fabricated using iTPB-2AC. As can be seen from the figure, the maximum luminance and start-up voltage of the undoped device based on iTPB-2AC are 3217 cd / m². 2 The brightness is related to various factors, including the radiative transition rate of molecules, exciton utilization, and transport performance, and the fabrication of the device also plays a role. The onset voltage is related to the transport performance of molecules.

[0201] Figure 6 This is a graph showing the efficiency of an undoped blue OLED device fabricated using iTPB-2AC as a function of brightness. The graph shows that the undoped device based on iTPB-2AC exhibits good efficiency with a roll-off effect, reaching a maximum external quantum efficiency of 8.23% at a brightness of 1000 cd / m². 2 At that time, the external quantum efficiency remained high.

[0202]

Application Example 3

[0203] This application example tests the performance of the undoped deep blue OLED device based on the high-level dipole-oriented tetraphenylbenzene derivative (DPA-TPB-CN) prepared in Comparative Example 1:

[0204] Undoped blue light-emitting devices were fabricated using the high-level dipole-oriented tetraphenylbenzene derivative DPA-TPB-CN (solid-state thin film fluorescence quantum yield = 49.6%, molecular-level dipole orientation = 79%) prepared in Comparative Example 1 as the luminescent material. The devices were then characterized, and the results are shown in [Figure 1]. Figures 7-8 .

[0205] Device structure: ITO / HAT-CN (5nm) / TAPC (50nm) / TCTA (5nm) / DPA-TPB-CN (20nm) / TmPyPB (40nm) / LiF (1nm) / Al (120nm).

[0206] The device fabrication process is similar to that in Application Example 1.

[0207] Figure 7 The figure shows the JVL curve of the undoped blue OLED device fabricated using DPA-TPB-CN. As can be seen from the figure, the maximum luminance and start-up voltage of the undoped device based on DPA-TPB-CN are 5234 cd / m². 2 2.8V.

[0208] Figure 8 This is a graph showing the efficiency of an undoped blue OLED device fabricated using DPA-TPB-CN as a function of brightness. The graph shows that the undoped device based on DPA-TPB-CN exhibits good efficiency with a roll-off effect, reaching a maximum external quantum efficiency of 4.53% at a brightness of 1000 cd / m². 2 At that time, the external quantum efficiency was 4.23%.

[0209] Data from the above application examples demonstrate that this invention obtains highly efficient solid-state blue light-emitting tetraphenylbenzene derivatives by attaching different double electron-donating and electron-withdrawing groups to different positions of tetraphenylbenzene. Undoped deep blue OLEDs fabricated using these high-level dipole-oriented tetraphenylbenzene derivatives as the emitting layer exhibit high efficiency, low efficiency roll-off, and low start-up voltage, indicating that these high-level dipole-oriented tetraphenylbenzene derivatives have broad application prospects in the field of organic optoelectronics.

[0210] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A tetraphenylbenzene derivative having the structure shown in the following formula: 。 2. A method for preparing a tetraphenylbenzene derivative, used to prepare the tetraphenylbenzene derivative of claim 1, the method comprising: (1) The compound shown in formula (i-1) reacts with phenylboronic acid substituted with electron-withdrawing groups to give an intermediate; (2) The intermediate reacts with phenylboronic acid substituted with an N-donating group to obtain the tetraphenylbenzene derivative; The phenylboronic acid substituted with an N-donating group is the compound shown in formula (ii-1): Equation (ii-1) The electron-withdrawing group substituted for the phenylboronic acid is the compound shown in formula (ii-2): Equation (ii-2).

3. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of the compound shown in formula (i-1) to the electron-withdrawing group-substituted phenylboronic acid is 1:(2~2.5); The reaction described in step (1) is carried out in the presence of a base and a palladium-based compound.

4. The preparation method according to claim 2, characterized in that, The reaction temperature in step (1) is 66~80℃.

5. The preparation method according to claim 2, characterized in that, Post-processing is performed after the reaction described in step (1), which includes extraction, concentration and silica gel column chromatography.

6. The preparation method according to claim 3, characterized in that, The molar ratio of the base to the compound shown in formula (i-1) in step (1) is (1~5):

1.

7. The preparation method according to claim 3, characterized in that, The molar ratio of the palladium-based compound in step (1) to the compound shown in formula (i-1) is (0.01~0.1):

1.

8. The preparation method according to any one of claims 2 to 7, characterized in that, In step (2), the molar ratio of the intermediate to phenylboronic acid substituted with an N-donating group is 1:(2.1~3).

9. The preparation method according to any one of claims 2 to 7, characterized in that, The reaction described in step (2) is carried out in the presence of a base and a palladium-based compound.

10. The preparation method according to any one of claims 2 to 7, characterized in that, The reaction temperature in step (2) is 66~80℃.

11. The preparation method according to any one of claims 2 to 7, characterized in that, The reaction described in step (2) is followed by post-processing, which includes extraction, concentration and silica gel column chromatography.

12. The preparation method according to claim 9, characterized in that, The molar ratio of the alkali to the intermediate in step (2) is 1:(1~5).

13. The preparation method according to claim 9, characterized in that, The molar ratio of the palladium-based compound to the intermediate in step (2) is (0.02~1):

1.

14. The application of the tetraphenylbenzene derivative of claim 1 as an undoped light-emitting layer in an organic electroluminescent device.

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