Multi-resonance thermal activation delayed fluorescence material as well as preparation method and application thereof

Abstract

The invention relates to a multi-resonance thermal activation delayed fluorescence material as well as a preparation method and application thereof, and belongs to the technical field of organic light-emitting materials. The structural formula of the multi-resonance thermal activation delayed fluorescence material is shown in the specification, wherein R1, R2, R3, R4 and R5 are independently selected from hydrogen, unsubstituted or substituted aryl and unsubstituted or substituted alkyl; x1, X2 and X3 are independently selected from oxygen, sulfur, selenium, sulfoxide group, sulfuryl or N-R, R is unsubstituted or substituted aryl and unsubstituted or substituted alkyl, and substitution is carried out in a single bond or ring formation mode. Dark blue light emission is successfully realized through oxygen atom doping with low orbital energy. The high-rigidity core skeleton can effectively inhibit structural relaxation so as to realize narrow-band emission, and the asymmetric molecular structure design is adopted, so that the fused skeleton generates reasonable distortion, the spin-orbit coupling effect is enhanced, the reverse intersystem crossing process is accelerated, and further efficient thermal activation delayed fluorescence is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic light-emitting materials, and particularly relates to a multi-resonance thermally activated delayed fluorescence material and a preparation method and application thereof. BACKGROUND

[0002] Organic light-emitting diode (OLED) display technology has been widely used in flat panel display and solid-state lighting fields due to its low power consumption, excellent color reproduction, fast response time, and flexibility, and has shown great commercial potential. In a typical OLED device, when a bias is applied between the cathode and the anode, electrons and holes are injected into the light-emitting layer through the electron transport layer and the hole transport layer, respectively. In the light-emitting layer, electrons and holes recombine to form excitons, and photons are emitted through fluorescent or phosphorescent radiative transition processes. The selection of the light-emitting layer material is a key factor in determining the performance of the OLED device.

[0003] In recent years, thermally activated delayed fluorescence (TADF) materials have attracted much attention due to their ability to achieve theoretical 100% exciton utilization through the reverse intersystem crossing (RISC) process. However, early developed TADF materials, although having high external quantum efficiency, generally have problems such as large full width at half maximum (FWHM) and insufficient color purity, especially in the deep blue region. Recent studies have shown that TADF materials based on multi-resonance (MR) effect can achieve narrow spectral band emission, which is an effective strategy to obtain high color purity emission. However, traditional B / N-type MR-TADF materials usually have difficulty in achieving short-wavelength emission (λ em <460nm) that meets the requirements of deep blue light, which cannot meet the technical requirements of ultra-high-definition display (UHD). Recent studies have successfully achieved deep blue light emission meeting the BT.2020 standard by introducing oxygen atoms to construct a B / N / O-type MR-TADF system (Angew. Chem. Int. Ed., 60, 17910 (2021); Adv. Mater., 34, 2107951 (2022); ACS Materials Letters, 6, 3246 (2024)). However, the introduction of oxygen atoms weakens the MR effect of the molecule, leading to a decrease in device performance.

[0004] Therefore, it is still an urgent problem to develop MR-TADF materials with narrow spectral band emission, high color purity, and high external quantum efficiency. SUMMARY

[0005] To solve the above technical problems, the present application provides a multi-resonance thermally activated delayed fluorescence material and a preparation method and application thereof.

[0006] The first object of the present application is to provide a multiple resonance heat-activated delayed fluorescent material, which has the following structural formula:

[0007]

[0008] wherein R1, R2, R3, R4, R5 are independently selected from hydrogen, unsubstituted or substituted aryl, unsubstituted or substituted alkyl, the substitution being carried out in a single bond or in a ring-forming manner;

[0009] X1, X2, X3 are independently selected from oxygen, sulfur, selenium, sulfoxide, sulfone or N-R, R being unsubstituted or substituted aryl, unsubstituted or substituted alkyl, the substitution being carried out in a single bond or in a ring-forming manner.

[0010] In one embodiment of the present application, the aryl is selected from phenyl, biphenyl, terphenyl, quaterphenyl, pyridyl, pyrimidyl, pyrazyl, pyridazyl, triazyl, quinolyl, isoquinolyl, indolyl, phenothiazyl, furanyl, thienyl, pyrrolyl, thiazolyl, isothiazolyl, pyrazolyl, imidazolyl, oxazolyl, isoxazolyl, naphthyl, anthryl, phenanthryl, pyrenyl, perylenyl, fluorenyl, carbazolyl, coumarinyl, quinolonyl, benzocarbazolyl, benzofluorenyl or benzothienyl; the substituent in the substituted aryl is selected from alkyl, alkoxy or alkylamine; the alkyl is selected from methyl, ethyl, propyl, butyl, pentyl, hexyl or heptyl. The aryl substituent can be an aryl having only carbon atoms as the ring-forming atoms of the aromatic ring, or an aryl having atoms other than carbon as the ring-forming atoms of the aromatic ring. The aryl substituent can be further substituted by other groups, which can be alkoxy or alkylamine, or aryloxy or arylamine, or an aryl or alkyl substituted by other linking atoms or other linking groups other than oxygen or nitrogen, such as sulfur, sulfoxide or sulfone, as long as the aryl or alkyl is linked to the aryl substituent by a chemical bond. The aryl substituent can be substituted by one or more other groups.

[0011] In one embodiment of the present application, the alkyl group is selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, or heptyl; the substituent in the substituted alkyl group is selected from the group consisting of phenyl, tolyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, methoxyphenyl, ethoxyphenyl, propoxyphenyl, butoxyphenyl, pentoxyphenyl, hexyloxyphenyl, heptyloxyphenyl, methylaminophenyl, ethylaminophenyl, propylaminophenyl, butylaminophenyl, pentylaminophenyl, hexylaminophenyl, heptylaminophenyl, biphenyl, or carbazolyl. The alkyl group as a substituent (including isomeric substituents) can be a carbon-hydrogen element group alkyl group, or an alkyl group containing atoms other than carbon and hydrogen. The alkyl group can be a chain alkyl group, or a ringed alkyl group. When the number of carbon atoms in the alkyl substituent exceeds two carbon atoms, isomeric alkyl groups are within the scope of the present application. The alkyl substituent can be further substituted with an aryl group. When the alkyl substituent is substituted with an aryl group, the number of substituents can be one, or multiple alkyl groups.

[0012] In one embodiment of the present application, the multiple resonance thermally activated delayed fluorescence material is selected from the group consisting of:

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026] Further, the multiple resonance thermally activated delayed fluorescence material is selected from compound 1-47 (TBNO-1) and / or compound 2-89 (TBNO-2). The compound TBNO-1 and the compound TBNO-2 exhibit excellent luminescent properties in solution state and doped thin film state, with extremely narrow full width at half maximum and extremely high fluorescence quantum yield and high efficiency thermally activated delayed fluorescence properties. The organic electroluminescent device prepared by using the compound TBNO-1 and the compound TBNO-2 as a doped fluorescent material can achieve extremely high external quantum efficiency, excellent color purity and significantly reduced efficiency roll-off properties.

[0027] A second object of the present application is to provide a preparation method of the multiple resonance thermally activated delayed fluorescence material, comprising the following steps:

[0028]

[0029] wherein R1, R2, R3, R4, R5 are independently selected from hydrogen, unsubstituted or substituted aryl, unsubstituted or substituted alkyl, and the substitution is carried out in a single bond or a ring-forming manner;

[0030] X1, X2, X3 are independently selected from oxygen, sulfur, selenium, sulfoxide group, sulfone group or N-R, R is unsubstituted or substituted aryl, unsubstituted or substituted alkyl, and the substitution is carried out in a single bond or a ring-forming manner;

[0031] S1, under the action of a metal catalyst and a base, compound 1 is subjected to carbon-nitrogen coupling reaction with an aromatic amine compound X2 in an organic solvent to generate compound 2;

[0032] S2, under the action of a metal catalyst and a base, compound 2 in S1 is subjected to carbon-nitrogen coupling reaction with compound 3 in an organic solvent to generate compound 4;

[0033] S3, compound 4 in S2 is subjected to boronization reaction with BBr3 in a solvent to obtain the multiple resonance thermally activated delayed fluorescence material.

[0034] In an embodiment of the present application, in S1 and S2, the metal catalyst is independently selected from one or more of palladium chloride, palladium acetate, tris(dibenzylideneacetone)dipalladium and 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl.

[0035] In an embodiment of the present application, in S1 and S2, the base is independently selected from one or more of potassium tert-butoxide, sodium tert-butoxide and cesium carbonate.

[0036] In an embodiment of the present application, in S1 and S2, the organic solvent is independently selected from one or more of dimethylformamide, toluene and m-xylene.

[0037] In one embodiment of the present application, in S3, the solvent is selected from o-dichlorobenzene and / or 1,2,4-trichlorobenzene.

[0038] A third object of the present application is to provide an application of the multiple resonance thermally activated delayed fluorescence material in an organic electroluminescent device.

[0039] The technical solution of the present application has the following advantages compared with the prior art:

[0040] (1) The multiple resonance thermally activated delayed fluorescence material according to the present application successfully realizes deep blue light emission by doping oxygen atoms with low orbital energy; the highly rigid core skeleton can effectively inhibit structural relaxation, thereby realizing narrow-band emission; the introduction of oxygen atoms weakens the MR effect of the molecular skeleton, which leads to the problem of device performance degradation; the use of an asymmetric molecular structure design causes the fused skeleton to produce reasonable distortion, increases the spin-orbit coupling effect, and accelerates the reverse intersystem crossing process, thereby realizing efficient thermally activated delayed fluorescence.

[0041] (2) The organic electroluminescent device prepared from the multiple resonance thermally activated delayed fluorescence material according to the present application exhibits high efficiency and high color purity deep blue light emission characteristics, and is suitable for high-end optoelectronic applications such as ultra-high-definition display. It can also be applied to host-guest type electroluminescent systems such as fluorescent light emitting materials and phosphorescent light emitting materials. In addition to flat panel displays (such as OLED televisions and smartphone screens), the material also has potential application value in the field of energy-saving solid-state lighting. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to make the content of the present application easier to be clearly understood, the present application will be further described in detail below according to specific embodiments of the present application and in conjunction with the drawings, in which:

[0043] Figure 1 The figure is a structural schematic diagram of the organic electroluminescent device of the present application;

[0044] Explanation of reference numerals: 1 - substrate, 2 - hole transport layer, 3 - light emitting layer, 4 - hole blocking layer, 5 - electron transport layer, 6 - cathode layer. DETAILED DESCRIPTION

[0045] The present application will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present application and implement it, but the embodiments are not limiting to the present application.

[0046] Example 1

[0047] The multiple resonance thermally activated delayed fluorescence material and the preparation method thereof of the present embodiment specifically include the following steps:

[0048]

[0049] S1, synthesis of intermediate 1a: 1,3-dibromo-5-chlorobenzene (8.1 g, 30 mmol), 4,4'-dimethyldiphenylamine (14.8 g, 75 mmol), tris(dibenzylideneacetone)dipalladium (824 mg, 0.9 mmol), 2-biscyclohexylphosphino-2',6'-dimethoxy-1,1'-biphenyl (739 mg, 1.8 mmol), sodium tert-butoxide (11.5 g, 120 mmol) and toluene (100 mL) were added into a two-necked flask under nitrogen protection, the reaction was heated to 110 °C and stirred for 12 h after three times of nitrogen replacement, the reaction mixture was extracted with deionized water and dichloromethane, the lower organic phase was collected, dried over anhydrous sodium sulfate, then the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography with PE:EA (10:1) as eluent to obtain white solid, intermediate 1a (12.9 g, 86%). 1 HNMR (400 MHz, CD2Cl2) δ: 7.12-7.06 (m, 8H), 6.99-6.94 (m, 8H), 6.49 (t, J = 2.1 Hz, 1H), 6.43 (d, J = 2.0 Hz, 2H), 2.32 (s, 12H). MALDI-TOF: Calculated: 502.22, Found: 502.02.

[0050] S2, synthesis of intermediate 1b: BBr3 (4.0 mL, 40 mmol) was slowly added to a solution of intermediate 1a (2.0 g, 4 mmol) in o-dichlorobenzene (30 mL) under nitrogen protection at room temperature, heated to 180 °C and stirred for 20 h, after cooling to room temperature, the reaction mixture was slowly dropped into a phosphate buffer solution, neutralized and the pH was adjusted to 7, extracted with deionized water and dichloromethane, the lower organic phase was collected, dried over anhydrous sodium sulfate, then the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography with PE:EA (8:1) as eluent to obtain yellow solid, intermediate 1b (1.4 g, 69%). 1 HNMR (400 MHz, CD2Cl2) δ: 8.64 (d, J = 2.2 Hz, 2H), 7.48-7.39 (m, 4H), 7.19 (dd, J = 8.8, 2.2 Hz, 2H), 7.15-7.09 (m, 4H), 6.61 (d, J = 8.7 Hz, 2H), 5.99 (s, 2H), 2.45 (d, J = 7.0 Hz, 12H). MALDI-TOF: Calculated: 510.20, Found: 510.42.

[0051] S3, synthesis of intermediate 1c: under nitrogen protection, intermediate 1b (510 mg, 1.0 mmol), 2,4,6-trimethylaniline (203 mg, 1.5 mmol), tris(dibenzylideneacetone)dipalladium (27 mg, 0.03 mmol), 2-bis(cyclohexylphosphino)-2',6'-dimethoxy-1,1'-biphenyl (25 mg, 0.06 mmol), sodium tert-butoxide (192 mg, 2.0 mmol) and toluene (30 mL) were added into two reaction flasks, the reaction liquid was replaced with nitrogen for three times, heated to 80 °C and stirred for 12 h, after cooling to room temperature, the reaction mixture was extracted with deionized water and dichloromethane, the lower organic phase was collected, dried over anhydrous sodium sulfate, then the solvent was removed by rotary evaporation, and purified by silica gel column chromatography with PE:EA (4:1) as eluent to obtain yellow solid, intermediate 1c (500 mg, 82%). 1 H NMR (400 MHz, CD2Cl2) δ: 8.58 (d, J = 2.2 Hz, 2H), 7.31 (s, 2H), 7.29 (s, 2H), 7.10 (d, J = 2.2 Hz, 1H), 7.07 (d, J = 2.2 Hz, 1H), 7.04 (d, J = 2.0 Hz, 2H), 7.02 (d, J = 1.9 Hz, 2H), 6.62 (s, 2H), 6.55 (s, 1H), 6.53 (s, 1H), 5.13 (s, 1H), 5.00 (s, 2H), 2.40 (s, 6H), 2.39 (s, 6H), 2.14 (s, 3H), 1.86 (s, 6H). MALDI-TOF: Calculated: 609.33, Found: 609.09.

[0052] S4, synthesis of intermediate 1d: under nitrogen protection, intermediate 1c (305 mg, 0.5 mmol), 7-bromo-3,11-di-tert-butyl-5,9-dioxa-13b-borphenalen-3-ene (230 mg, 0.5 mmol), tris(dibenzylideneacetone)dipalladium (27 mg, 0.03 mmol), 2-bis(cyclohexylphosphino)-2',6'-dimethoxy-1,1'-biphenyl (25 mg, 0.06 mmol), sodium tert-butoxide (192 mg, 2.0 mmol) and toluene (30 mL) were added into two reaction flasks, the reaction liquid was replaced with nitrogen for three times, heated to 110 °C and stirred for 18 h, the subsequent steps were the same as the preparation of intermediate 1c, to obtain yellow solid, intermediate 1d (300 mg, 61%). 1H NMR (400 MHz, CD2Cl2) δ: 8.66-8.62 (m, 2H), 8.45 (d, J = 8.1 Hz, 2H), 7.38 (d, J = 1.8 Hz, 2H), 7.34 (dd, J = 8.0, 1.9 Hz, 2H), 7.22 (d, J = 8.0 Hz, 4H), 7.14 (dd, J = 8.8, 2.1 Hz, 2H), 7.06-7.02 (m, 4H), 6.72 (s, 2H), 6.66 (d, J = 8.7 Hz, 2H), 6.54 (s, 2H), 5.64 (s, 2H), 2.43 (s, 6H), 2.26 (s, 3H), 2.08 (s, 6H), 1.73 (s, 6H), 1.34 (s, 18H). MALDI-TOF: Calculated: 989.53, Found: 989.23.

[0053] S5, Synthesis of compound TBNO-1: Under nitrogen protection, intermediate 1d (250 mg, 0.25 mmol) and 15 mL of o-dichlorobenzene solvent were sequentially added into a two-mouth reaction flask. After the reaction solution was replaced by nitrogen, boron tribromide (0.2 mL, 2 mmol) was slowly added dropwise, and then the reaction was raised to 200°C for stirring for 24 h. After the reaction was cooled to room temperature, methanol was slowly added for quenching, followed by extraction with a large amount of dichloromethane and deionized water. The lower organic phase was collected, dried over anhydrous sodium sulfate, vacuum concentrated by a rotary evaporator, and purified by silica gel column chromatography with PE:EA (4:1) as the eluent to obtain yellow solid, i.e. compound TBNO-1 (199 mg, 80%). 1 H NMR (400 MHz, CDCl3-d) δ: δ: 8.78-8.73 (m, 2H), 8.71 (d, J = 8.1 Hz, 1H), 8.67-8.63 (m, 2H), 8.42 (d, J = 8.7 Hz, 1H), 8.21 (d, J = 8.6 Hz, 1H), 7.71 (d, J = 1.8 Hz, 1H), 7.55 (dd, J = 8.1, 1.9 Hz, 1H), 7.46-7.42 (m, 3H), 7.40 (dd, J = 8.9, 2.2 Hz, 1H), 7.31 (dd, J = 8.7, 2.1 Hz, 2H), 7.01 (d, J = 5.8 Hz, 3H), 6.93 (s, 1H), 6.82 (d, J = 8.7 Hz, 1H), 6.56 (s, 1H), 5.36 (d, J = 8.4 Hz, 2H), 2.62 (d, J = 14.6 Hz, 6H), 2.55 (s, 3H), 2.48 (d, J = 6.0 Hz, 6H), 1.78 (s, 3H), 1.72 (s, 3H), 1.51 (s, 9H), 1.43 (s, 9H). 13C NMR (125 MHz, CDC13-d) δ: 157.38, 157.18, 157.12, 155.32, 152.28, 152.18, 149.94, 148.75, 148.16, 146.89, 146.00, 145.90, 144.98, 141.09, 140.08, 137.12, 137.05, 135.86, 135.54, 135.50, 135.35, 135.29, 135.12, 135.01, 134.96, 134.90, 134.80, 134.30, 130.84, 130.57, 130.56, 130.50, 130.48, 130.40, 130.16, 127.97, 126.32, 122.97, 122.92, 122.33, 122.25, 122.16, 121.13, 121.11, 119.90, 115.51, 114.24, 113.34, 104.74, 34.67, 34.66, 31.58, 31.57, 31.55, 21.05, 21.03, 21.02, 20.67, 20.64, 18.27. MALDI-TOF: Calculated: 997.51, Found: 997.23.

[0054] Example 2

[0055] The multiple resonance thermally activated delayed fluorescent material and the preparation method thereof of the present embodiment specifically comprises the following steps:

[0056]

[0057] S1, synthesis of intermediate 2a: under nitrogen protection, 1-bromo-3-chloro-5-fluorobenzene (4.16 g, 20 mmol), 3-(tert-butyl)phenol (3.0 g, 20 mmol), cesium carbonate (9.8 g, 30 mmol) and N,N-dimethylformamide (100 mL) were added to a double-mouth reaction flask, the reaction solution was replaced with nitrogen for three times, heated to 150°C and stirred for 12 h, and the subsequent steps were the same as the preparation of intermediate 1a to obtain the oil product, intermediate 2a (5.9 g, 87%). 1H NMR (400 MHz, CD2CI2) δ: 7.22 (t, J = 7.9 Hz, 1H), 7.15 (ddd, J = 7.9, 1.8, 1.1 Hz, 1H), 7.13 (t, J = 1.7 Hz, 1H), 7.01 (t, J = 2.1 Hz, 1H), 6.94 (dd, J = 2.2, 1.7 Hz, 1H), 6.83 (t, J = 2.0 Hz, 1H), 6.74 (ddd, J = 8.0, 2.4, 1.1 Hz, 1H), 1.22 (s, 9H). MALDI-TOF: Calculated: 338.01, Found: 338.12.

[0058] S2, synthesis of intermediate 2b: Intermediate 2a (3.4 g, 10 mmol), 4,4'-dimethyldiphenylamine (1.4 g, 10 mmol), tris(dibenzylideneacetone)dipalladium (275 mg, 0.3 mmol), 2-biscyclohexylphosphino-2',6'-dimethoxy-1,1'-biphenyl (246 mg, 0.6 mmol), sodium tert-butoxide (1.92 g, 20 mmol) and toluene (100 mL) were added into a two-necked flask under nitrogen protection, the reaction was heated to 80 °C and stirred for 18 h after purging with nitrogen for three times, the subsequent steps were the same as the preparation of intermediate 1a, to obtain the product intermediate 2b (3.6 g, 79%) as an oil. 1 H NMR (400 MHz, CD2CI2) δ: 7.22 (t, J = 7.9 Hz, 1H), 7.15 (ddd, J = 7.9, 1.8, 1.1 Hz, 1H), 7.13 (t, J = 1.7 Hz, 1H), 7.01 (t, J = 2.1 Hz, 1H), 6.94 (dd, J = 2.2, 1.7 Hz, 1H), 6.83 (t, J = 2.0 Hz, 1H), 6.74 (ddd, J = 8.0, 2.4, 1.1 Hz, 1H), 1.22 (s, 9H). MALDI-TOF: Calculated: 338.01, Found: 338.12.

[0059] S3, synthesis of intermediate 2c: Intermediate 2b (2.3 g, 5 mmol) and o-dichlorobenzene (30 mL) were added into a two-necked flask under nitrogen protection at room temperature, the reaction was heated to 180 °C and stirred for 20 h after purging with nitrogen for three times, then boron tribromide (4.0 mL, 40 mmol) was slowly added, the subsequent steps were the same as the preparation of intermediate 1b (PE:EA was 10:1), to obtain the product intermediate 2c (482 mg, 21%) as a light yellow solid. 1H NMR (400 MHz, CDC13-d) δ: 8.71 (d, J = 8.1 Hz, 1H), 8.67 (s, 1H), 7.53-7.44 (m, 4H), 7.29 (dd, J = 8.8, 1.9 Hz, 1H), 7.20 (d, J = 8.1 Hz, 2H), 7.02 (d, J = 1.4 Hz, 1H), 6.72 (d, J = 8.8 Hz, 1H), 6.30 (d, J = 1.4 Hz, 1H), 2.53 (d, J = 16.9 Hz, 6H), 1.45 (s, 9H). MALDI-TOF: Calculated: 463.19, Found: 463.33.

[0060] S4, synthesis of intermediate 2d: Intermediate 2c (463 mg, 1.0 mmol), 2,4,6-trimethylaniline (68 mg, 0.5 mmol), tris-dibenzylideneacetone palladium (27 mg, 0.03 mmol), 2-biscyclohexylphosphino-2',6'-dimethoxy-1,1'-biphenyl (25 mg, 0.06 mmol), sodium tert-butoxide (96 mg, 1.0 mmol) and tert-butylbenzene (30 mL) were added to a two-necked flask under nitrogen protection, the reaction was replaced with nitrogen for three times, heated to 180 °C and stirred for 20 h, the subsequent steps were the same as the preparation of intermediate 1c, to obtain yellow solid, intermediate 2d (375 mg, 76%). 1 H NMR (400 MHz, CDC13-d) δ: 8.68 (d, J = 8.2 Hz, 2H), 8.63 (s, 2H), 7.46 (d, J = 1.8 Hz, 2H), 7.41 (dd, J = 8.1, 1.8 Hz, 2H), 7.23 (s, 4H), 7.21 (d, J = 1.8 Hz, 2H), 7.05 (d, J = 8.1 Hz, 4H), 6.77-6.70 (m, 6H), 5.71 (d, J = 1.8 Hz, 2H), 2.49 (s, 6H), 2.32 (s, 3H), 2.20 (s, 6H), 1.78 (s, 6H), 1.44 (s, 18H). MALDI-TOF: Calculated: 989.53, Found: 989.33.

[0061] S5, synthesis of compound TBNO-2: Intermediate 2d (330 mg, 0.3 mmol) and o-dichlorobenzene (15 mL) were added to a two-necked flask under nitrogen protection, the reaction was replaced with nitrogen for three times, then boron tribromide (0.3 mL, 3 mmol) was added dropwise, then the reaction was raised to 200 °C and stirred for 20 h, the subsequent steps were the same as the preparation of compound TBNO-1 (PE:EA was 3:1), to obtain yellow solid, compound TBNO-2 (202 mg, 68%).1 HNMR (400 MHz, CDC13-d) δ: 8.86 (d, J = 8.2 Hz, 1H), 8.78-8.73 (m, 2H), 8.66 (d, J = 8.6 Hz, 1H), 8.56 (s, 1H), 8.41 (d, J = 8.7 Hz, 1H), 8.12 (d, J = 8.6 Hz, 1H), 7.67 (d, J = 1.8 Hz, 1H), 7.56 (dd, J = 8.1, 1.8 Hz, 1H), 7.50-7.41 (m, 3H), 7.35 (dd, J = 8.6, 1.9 Hz, 1H), 7.30-7.26 (m, 2H), 7.04-6.99 (m, 2H), 6.93 (d, J = 5.6 Hz, 2H), 6.72 (d, J = 8.7 Hz, 1H), 6.30 (s, 1H), 5.57 (s, 1H), 2.91 (d, J = 27.1 Hz, 1H), 2.58 (s, 3H), 2.52 (s, 6H), 2.44 (s, 6H), 1.72 (d, J = 5.9 Hz, 6H), 1.50 (s, 9H), 1.41 (s, 9H). 13 C NMR (125 MHz, CDC13-d) δ: 158.34, 157.91, 157.30, 157.12, 152.28, 152.18, 149.44, 148.54, 148.09, 147.07, 146.02, 145.93, 144.86, 141.09, 140.08, 137.04, 136.97, 135.86, 135.54, 135.53, 135.41, 135.38, 135.35, 134.90, 134.82, 134.80, 134.30, 130.61, 130.57, 130.56, 130.50, 130.48, 130.33, 130.16, 129.04, 127.88, 126.32, 124.64, 122.95, 122.93, 122.27, 121.29, 121.22, 121.20, 114.27, 113.31, 113.21, 106.43, 34.67, 34.66, 31.58, 31.57, 31.55, 21.05, 21.03, 21.02, 20.67, 20.64, 18.28. MALDI-TOF: Calculated: 997.51, Found: 997.13.

[0062] Example 3

[0063] The multiple resonance thermally activated delayed fluorescent material and the method of preparing the same of the present embodiment specifically include the following steps:

[0064]

[0065] S1-S3, synthesis of intermediates 3a-3c: same as synthesis of intermediates 1a-1c in Example 1;

[0066] S4, synthesis of intermediate 3d: same as synthesis of intermediate 1d in Example 1, except the position of the t-butyl group was switched; 1 H NMR (500 MHz, CDC13-d) δ: 7.48 (d, J = 2.1 Hz, 2H), 7.28 (dd, J = 7.0, 2.1 Hz, 2H), 7.21 (d, J = 1.9 Hz, 2H), 7.16-7.13 (m, 2H), 7.06 (s, 8H), 7.02 (d, J = 7.3 Hz, 2H), 6.89-6.83 (m, 4H), 6.69 (s, 2H), 6.42 (t, J = 1.2 Hz, 2H), 2.38 (s, 6H), 2.35 (s, 6H), 2.26 (s, 3H), 2.19 (s, 6H), 1.34 (s, 18H). MALDI-TOF: Calculated: 989.53, Found: 989.33.

[0067] S5, synthesis of compound 1-53: same as synthesis of compound TBNO-1 in Example 1, except the position of the t-butyl group was switched; 1 H NMR (500 MHz, CDC13-d) δ: 7.48 (d, J = 2.1 Hz, 2H), 7.28 (dd, J = 7.0, 2.1 Hz, 2H), 7.21 (d, J = 1.9 Hz, 2H), 7.16-7.13 (m, 2H), 7.06 (s, 8H), 7.02 (d, J = 7.3 Hz, 2H), 6.89-6.83 (m, 4H), 6.69 (s, 2H), 6.42 (t, J = 1.2 Hz, 2H), 2.38 (s, 6H), 2.35 (s, 6H), 2.26 (s, 3H), 2.19 (s, 6H), 1.34 (s, 18H). MALDI-TOF: Calculated: 989.53, Found: 989.33. 13CNMR (125 MHz, CDC13-d) δ 157.64, 156.69, 156.44, 156.01, 149.94, 148.75, 148.16, 147.60, 147.58, 146.89, 146.00, 145.90, 144.98, 141.09, 140.08, 135.86, 135.54, 135.50, 135.35, 135.29, 135.12, 135.01, 134.96, 134.90, 134.80, 134.30, 133.55, 133.49, 130.57, 130.56, 130.50, 130.48, 130.26, 130.16, 129.78, 127.97, 127.06, 126.32, 122.97, 122.92, 122.33, 122.25, 122.16, 119.48, 117.80, 116.82, 115.51, 104.74, 34.53, 31.27, 31.25, 31.24, 21.05, 21.03, 21.02, 20.67, 20.64, 18.27. MALDI-TOF: Calculated: 997.51, Found: 997.53.

[0068] Example 4

[0069] The multiple resonance thermally activated delayed fluorescent material and the method of preparing the same according to the present embodiment specifically include the following steps:

[0070]

[0071] S1, synthesis of intermediate 4a: basically the same as the synthesis of intermediate 2a in Example 2, except that the raw material t-butyl is replaced by methyl; 1 H NMR (500 MHz, CDC13-d) δ: 7.32 (dt, J = 16.3, 2.1 Hz, 2H), 7.19 (ddd, J = 7.6, 1.4, 0.8 Hz, 2H), 6.97 (t, J = 2.2 Hz, 1H), 6.94-6.90 (m, 2H), 2.35 (d, J = 0.9 Hz, 3H). MALDI-TOF: Calculated: 295.96, Found: 295.66.

[0072] S2, synthesis of intermediate 4b: basically the same as the synthesis of intermediate 2b in Example 2, except that the raw material t-butyl is replaced by methyl; 1H NMR (500 MHz, CDCI3-d) δ: 7.21-7.17 (m, 2H), 7.06 (d, J = 8.3 Hz, 4H), 7.04-6.99 (m, 5H), 6.94-6.90 (m, 3H), 6.75 (t, J = 2.2 Hz, 1 H), 2.35 (s, 9H). MALDI-TOF: Calculated: 413.15, Found: 413.05.

[0073] S3, synthesis of intermediate 4c: essentially the same as the synthesis of intermediate 2c in Example 2, except that the starting tert-butyl group was replaced by a methyl group; 1 H NMR (500 MHz, CDCI3-d) δ: 7.39 (d, J = 2.0 Hz, 2H), 7.21 (d, J = 2.2 Hz, 2H), 7.16-7.13 (m, 2H), 7.11-7.08 (m, 2H), 7.06 (s, 8H), 7.02 (s, 1 H), 7.01 (s, 1 H), 6.87 (s, 2H), 6.84 (d, J = 7.6 Hz, 2H), 6.42 (d, J = 2.2 Hz, 2H), 6.12 (d, J = 2.2 Hz, 2H), 2.39-2.37 (m, 12H), 2.35 (s, 6H), 2.26 (s, 3H), 2.19 (s, 6H). MALDI-TOF: Calculated: 905.43, Found: 905.23.

[0074] S4, synthesis of intermediate 4d: essentially the same as the synthesis of intermediate 2d in Example 2, except that the starting tert-butyl group was replaced by a methyl group; 1 H NMR (500 MHz, CDCI3-d) δ: 7.39 (d, J = 2.0 Hz, 2H), 7.21 (d, J = 2.2 Hz, 2H), 7.16-7.13 (m, 2H), 7.11-7.08 (m, 2H), 7.06 (s, 8H), 7.02 (s, 1 H), 7.01 (s, 1 H), 6.87 (s, 2H), 6.84 (d, J = 7.6 Hz, 2H), 6.42 (d, J = 2.2 Hz, 2H), 6.12 (d, J = 2.2 Hz, 2H), 2.39-2.37 (m, 12H), 2.35 (s, 6H), 2.26 (s, 3H), 2.19 (s, 6H). MALDI-TOF: Calculated: 905.43, Found: 905.23.

[0075] S5, synthesis of compound 2-41 : essentially the same as the synthesis of compound TBNO-2 in Example 2, except that the starting tert-butyl group was replaced by a methyl group; 1HNMR (500 MHz, CDC13-d) δ: 7.40 (d, J = 1.9 Hz, 2H), 7.21 (dddd, J = 6.2, 4.3, 2.1, 1.1 Hz, 3H), 7.16-7.11 (m, 3H), 7.11-7.08 (m, 2H), 7.07 (s, 6H), 7.02 (d, J = 7.3 Hz, 1H), 6.89 (s, 1H), 6.88-6.82 (m, 4H), 6.45 (s, 1H), 2.38 (d, J = 1.9 Hz, 9H), 2.37-2.34 (m, 9H), 2.26 (t, J = 1.1 Hz, 3H), 2.13 (d, J = 0.8 Hz, 6H). 13 C NMR (125 MHz, CDC13-d) δ 158.75, 158.35, 155.13, 155.08, 149.44, 148.54, 148.09, 147.07, 146.02, 145.93, 144.86, 141.09, 140.08, 135.86, 135.53, 135.41, 135.38, 135.37, 135.35, 135.02, 134.97, 134.90, 134.80, 134.54, 134.49, 134.30, 131.06, 130.57, 130.56, 130.50, 130.48, 130.16, 128.85, 127.88, 126.57, 126.37, 126.32, 124.43, 122.95, 122.93, 122.27, 121.29, 116.78, 115.80, 113.21, 106.43, 21.07, 21.05, 21.04, 21.03, 21.02, 20.67, 20.64, 18.28. MALDI-TOF: Calculated: 913.42, Found: 913.22.

[0076] Example 5

[0077] The multiple resonance thermally activated delayed fluorescent material and the method for preparing the same according to the present embodiment specifically include the following steps:

[0078]

[0079] S1, synthesis of intermediate 5a: the same as the synthesis of intermediate 2a in Example 2;

[0080] S2, synthesis of intermediate 5b: basically the same as the synthesis of intermediate 2b in Example 2, except that the raw material methyl is replaced by tert-butyl; 1H NMR (500 MHz, CDCI3-d) δ: 7.28-7.22 (m, 3H), 7.14-7.07 (m, 5H), 7.04 (ddd, J = 6.8, 2.2, 1.3 Hz, 2H), 7.00 (t, J = 2.1 Hz, 1H), 6.96-6.90 (m, 3H), 6.75 (t, J = 2.2 Hz, 1H), 1.33 (d, J = 0.8 Hz, 27H). MALDI-TOF: Calculated: 539.30, Found: 539.15.

[0081] S3, synthesis of intermediate 5c: essentially the same as the synthesis of intermediate 2c in Example 2, except that the starting material methyl was replaced by tert-butyl; 1 H NMR (500 MHz, CDCI3-d) δ: 7.53 (d, J = 6.5 Hz, 1H), 7.46 (d, J = 6.8 Hz, 1H), 7.24 (ddd, J = 7.3, 5.7, 1.6 Hz, 1H), 7.18 (d, J = 1.9 Hz, 1H), 7.13-7.07 (m, 3H), 7.01 (dt, J = 4.6, 2.2 Hz, 2H), 6.97 (dd, J = 6.9, 1.9 Hz, 1H), 6.84 (d, J = 2.2 Hz, 1H), 6.73 (d, J = 2.2 Hz, 1H), 1.33 (d, J = 1.7 Hz, 27H). MALDI-TOF: Calculated: 547.28, Found: 547.24.

[0082] S4, synthesis of intermediate 5d: essentially the same as the synthesis of intermediate 2d in Example 2, except that the starting material methyl was replaced by tert-butyl; 1 H NMR (500 MHz, CDCI3-d) δ: 7.53 (d, J = 6.5 Hz, 2H), 7.46 (d, J = 6.8 Hz, 2H), 7.27-7.22 (m, 2H), 7.18 (d, J = 2.1 Hz, 2H), 7.13-7.07 (m, 6H), 7.01 (dd, J = 6.5, 2.1 Hz, 2H), 6.97 (dd, J = 6.9, 2.1 Hz, 2H), 6.87 (s, 2H), 6.84 (d, J = 2.1 Hz, 2H), 6.42 (d, J = 2.2 Hz, 2H), 6.12 (d, J = 2.2 Hz, 2H), 2.26 (s, 3H), 2.19 (s, 6H), 1.33 (d, J = 1.7 Hz, 54H). MALDI-TOF: Calculated: 1157.31, Found: 1157.11.

[0083] S5, synthesis of compound 2-95: essentially the same as the synthesis of compound TBNO-2 in Example 2, except that the starting material methyl was replaced with tert-butyl; 1 H NMR (500 MHz, CDC13-d) δ: 7.53 (dd, J = 6.6, 2.1 Hz, 2H), 7.51-7.45 (m, 3H), 7.28-7.22 (m, 3H), 7.18 (d, J = 1.9 Hz, 1H), 7.15 (t, J = 2.2 Hz, 1H), 7.10 (ddt, J = 8.9, 6.6, 1.1 Hz, 2H), 7.01 (dd, J = 6.5, 2.2 Hz, 2H), 6.97 (dd, J = 6.8, 2.0 Hz, 3H), 6.90-6.84 (m, 5H), 6.45 (s, 1H), 2.26 (t, J = 1.0 Hz, 3H), 2.13 (d, J = 0.8 Hz, 6H), 1.33 (d, J = 1.8 Hz, 54H). 13 C NMR (125 MHz, CDC13-d) δ 158.34, 157.90, 157.30, 157.12, 152.28, 152.18, 151.73, 151.68, 151.65, 151.22, 149.44, 148.09, 147.47, 147.28, 145.78, 145.41, 144.51, 143.81, 140.08, 138.19, 138.05, 137.39, 137.06, 137.04, 136.53, 135.74, 135.42, 135.35, 134.30, 131.62, 131.32, 130.16, 129.80, 129.25, 128.10, 124.86, 124.36, 122.22, 121.54, 121.22, 121.20, 121.18, 121.14, 121.12, 121.01, 117.61, 117.48, 116.81, 114.27, 113.32, 113.21, 106.43, 36.00, 35.99, 34.67, 34.66, 34.59, 31.58, 31.57, 31.55, 31.22, 31.09, 31.07, 31.05, 31.03, 20.64, 18.28. MALDI-TOF: Calculated: 1165.70, Found: 1165.60.

[0084] Test Example 1

[0085] The compound TBNO-1 of Example 1-2 and the compound TBNO-2 were tested at a concentration of 10 -5The photophysical properties of films doped with 9-(3-(9H-carbazole-9-yl)phenyl)-9H-3,9'-dicarbazole (mCPBC) at a concentration of 2.0 wt% were characterized, and the results are shown in Table 1.

[0086] Table 1

[0087]

[0088] Where: λ abs , λ em ,Stokes shift,FWHM,Es,E T ΔE ST PLQY represent the position of the absorption peak, the position of the emission peak, the Stokes shift, the full width at half maximum (FWHM) of the emission spectrum, the lowest excitation singlet state, the lowest excitation triplet state, the energy level difference between the lowest excitation singlet state and the lowest excitation triplet state, and the fluorescence quantum yield, respectively.

[0089] As can be seen from Table 1, the emission spectra of compounds TBNO-1 and TBNO-2 under toluene solution and mCPBC thin film conditions are in the deep blue light region, with extremely small Stokes shift, extremely narrow emission band and extremely high luminescence efficiency. They also have high fluorescence quantum yield and efficient thermally activated delayed fluorescence characteristics, which are consistent with the expected photophysical properties of rigid fused molecular skeleton and asymmetric molecular structure design.

[0090] Test Example 2

[0091] The compounds TBNO-1 and TBNO-2 from Examples 1-2 were fabricated into organic electroluminescent devices and their performance was tested.

[0092] Fabrication of organic electroluminescent devices: Refer to Figure 1 As shown, a 3mm wide striped ITO transparent conductive glass was used as substrate 1. After being washed with ITO cleaning agent, it was treated with ozone and ultraviolet light for 15 minutes. Then, substrate 1 was placed in a vacuum evaporation chamber, and the chamber pressure was reduced to 1×10⁻⁶. -4Pa, sequentially on the substrate 1, a hole transport layer 2 (30 nm thick 4,4'- cyclohexyl di[N,N-di(4-methylphenyl) aniline] (TAPC)), a light-emitting layer 3 (20 nm thick mCPBC and compound TBNO-1 or compound TBNO-2 in a mass ratio of 98:2), a hole blocking layer 4 (10 nm thick 2,8-bis(diphenyl phosphine oxide) dithiophene (PPT)), an electron transport layer 5 (30 nm thick 3,3'-[5'-[3-(3-pyridyl) phenyl][1,1':3',1"-terphenyl]-3,3"-diyl]dipyridine (TmPyPb)), and a cathode layer 6 (1 nm and 100 nm thick lithium fluoride and aluminum); wherein the organic material is formed by a hot resistance heating method, and the compound is vacuum evaporated at a film formation rate of 0.1 nm / s-0.2 nm / s; the cathode is made by configuring a metal mask in a manner orthogonal to the ITO stripe; and an organic electroluminescent device with a light-emitting area of 10 mm 2 is obtained. The device is sealed in a nitrogen atmosphere glove box with a water and oxygen concentration of 1 ppm or less, and the sealing uses a glass sealing cover and the aforementioned film formation substrate epoxy ultraviolet curing resin (manufactured by Nagase Chemtex Corporation).

[0093] Performance test: a direct current is applied to the organic electroluminescent device, and a luminescence performance is evaluated using an external quantum efficiency measurement system C9920-12, and a current-voltage characteristic is measured using a computer-controlled Keithley 2400 digital source meter. As a luminescence characteristic, an electroluminescence spectrum, a half peak width, a CIE color coordinate value, an external quantum efficiency (%), a maximum current efficiency (cd / m 2 ), and a power efficiency (lm / W) are measured under a change in an applied direct current voltage. The results show that the electroluminescence spectrum peak of the organic electroluminescent device made of the compound TBNO-1 is 454 nm, the half peak width is 19 nm, the CIE color coordinate value is (0.143, 0.051), the maximum external quantum efficiency is 42.5%, the maximum current efficiency is 27.1 cd / A, and the maximum power efficiency is 17.1 lm / W; and the electroluminescence spectrum peak of the organic electroluminescent device made of the compound TBNO-2 is 452 nm, the half peak width is 17 nm, the CIE color coordinate value is (0.145, 0.044), the maximum external quantum efficiency is 40.4%, the maximum current efficiency is 21.3 cd / A, and the maximum power efficiency is 17.6 lm / W.

[0094] In summary, the multiple resonance thermally activated delayed fluorescence material of the present application can be applied to a high-performance deep blue organic electroluminescent device.

[0095] Obviously, the above embodiments are merely example for clearly illustrating, and are not limitation to the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and can not be exhausted. The obvious changes or variations derived therefrom are still within the scope of the present invention.

Claims

1. A multi-resonance thermally activated delayed fluorescence material, characterized in that, Its structural formula is shown below: R1, R2, R3, R4, and R5 are independently selected from hydrogen, unsubstituted or substituted aryl groups, and unsubstituted or substituted alkyl groups, with substitution occurring via single bonds or cyclization. X1, X2, and X3 are independently selected from oxygen, sulfur, selenium, sulfoxide, sulfone, or NR, where R is an unsubstituted or substituted aryl, unsubstituted or substituted alkyl, and substitution is performed by single bond or cyclic substitution.

2. The multiple resonance thermally activated delayed fluorescence material according to claim 1, characterized in that, The aryl group is selected from phenyl, biphenyl, terphenyl, tetraphenyl, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, quinolinyl, isoquinolinyl, indolyl, phenothiazinyl, furanyl, thiopheneyl, pyrroleyl, thiazolyl, isothiazinyl, pyrazolyl, imidazolyl, oxazolyl, isoxazolyl, naphthyl, anthraceneyl, phenanthryl, pyrene, peryl, fluorenyl, carbazolyl, coumarinyl, quinoloneyl, benzocarbazolyl, benzofluorenyl, or benzothiopheneyl; the substituent in the substituted aryl group is selected from alkyl, alkoxy, or alkylamine groups.

3. The multiple resonance thermally activated delayed fluorescence material according to claim 1, characterized in that, The alkyl group is selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, or heptyl; the substituent in the substituted alkyl group is selected from phenyl, tolyl, ethylphenyl, propanylphenyl, butylphenyl, pentanylphenyl, hexylphenyl, heptylphenyl, methoxyphenyl, ethoxyphenyl, propoxyphenyl, butoxyphenyl, pentanylphenyl, hexylphenyl, heptylphenyl, methylaminophenyl, ethylaminophenyl, propylaminophenyl, butylaminophenyl, pentanylphenyl, hexylphenyl, heptylphenyl, biphenyl, or carbazole.

4. The multiple resonance thermally activated delayed fluorescence material according to claim 1, characterized in that, The multiple resonance thermally activated delayed fluorescence material is selected from the following compounds:

5. The method for preparing the multiple resonance thermally activated delayed fluorescence material according to any one of claims 1-4, characterized in that, Includes the following steps: R1, R2, R3, R4, and R5 are independently selected from hydrogen, unsubstituted or substituted aryl groups, and unsubstituted or substituted alkyl groups, with substitution occurring via single bonds or cyclization. X1, X2, and X3 are independently selected from oxygen, sulfur, selenium, sulfoxide, sulfone, or NR, where R is an unsubstituted or substituted aryl, unsubstituted or substituted alkyl, and substitution is performed by single bond or cyclization. S1. Under the action of a metal catalyst and a base, compound 1 and aromatic amine compound X2 undergo a carbon-nitrogen coupling reaction in an organic solvent to generate compound 2. S2. Under the action of a metal catalyst and a base, compound 2 and compound 3 described in S1 undergo a carbon-nitrogen coupling reaction in an organic solvent to generate compound 4. Compound 4 described in S3 and S2 undergoes a borylation reaction with BBr3 in a solvent to obtain the multi-resonance thermally activated delayed fluorescence material.

6. The method for preparing the multiple resonance thermally activated delayed fluorescence material according to claim 5, characterized in that, In S1 and S2, the metal catalyst is independently selected from one or more of palladium chloride, palladium acetate, tridibenzylacetone dipalladium, and 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl.

7. The method for preparing the multiple resonance thermally activated delayed fluorescence material according to claim 5, characterized in that, In S1 and S2, the base is independently selected from one or more of potassium tert-butoxide, sodium tert-butoxide, and cesium carbonate.

8. The method for preparing the multiple resonance thermally activated delayed fluorescence material according to claim 5, characterized in that, In S1 and S2, the organic solvent is independently selected from one or more of dimethylformamide, toluene, and m-xylene.

9. The method for preparing the multiple resonance thermally activated delayed fluorescence material according to claim 5, characterized in that, In S3, the solvent is selected from o-dichlorobenzene and / or 1,2,4-trichlorobenzene.

10. The application of the multiple resonant thermally activated delayed fluorescence material as described in any one of claims 1-4 in organic electroluminescent devices.

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