Benzotris (triazole)-based blue luminescent materials

Abstract

The invention belongs to the technical field of organic electroluminescent materials, and particularly discloses a blue luminescent material based on benzotri (triazole). The novel blue light-emitting material is synthesized by taking benzotri (triazole) as a molecular structure center and then respectively taking bis (3, 5-di-tert-butylphenyl) amine, bis (3, 5-diphenyl) amine, bis (3, 5-dimethoxyphenyl) amine, 9, 9-dimethyl acridine, 3, 6-di-tert-butylcarbazole or 4, 4-difluorodiphenylamine as electron-donating groups. Due to a relatively large torsion angle between a donor and an acceptor, the overall planarity of molecules is reduced, so that the molecular accumulation is favorably inhibited, and the quenching of excitons is further reduced; a central core of triazole has a relatively rigid structure, so that relatively high fluorescence quantum yield (PLQY) can be provided, and blue light emission with short wavelength of 434-486nm is realized; and the method has important significance for constructing a novel blue light-emitting material.

Description

Technical Field

[0001] The invention belongs to the technical field of organic electroluminescent materials, and specifically discloses a class of blue luminescent materials based on benzotriazole. Background Art

[0002] Blue emitting materials are crucial in organic electroluminescent devices (OLEDs), particularly as one of the three primary colors in display technology. Blue OLEDs not only play a vital role in optical communications and information security displays, but are also used in flat-panel displays and lighting. Many types of emitters are used in blue OLEDs, including metal complexes, conjugated polymers, and phosphorescent metal complexes. These materials impart exceptional properties to blue OLEDs, such as lightweight, low power consumption, fast response time, excellent processing performance, a wide temperature range, and low cost.

[0003] The first generation of traditional fluorescent materials could only utilize singlet excitons for emission, resulting in an internal quantum efficiency of 25%. This resulted in a theoretical maximum external quantum efficiency (EQE) of only 5% for fluorescent OLEDs, making them unsuitable for commercial use and limiting their further development. Seeking a breakthrough, in 1998, Forrest of Princeton University developed an organic electroluminescent material based on the metal complex porphyrin platinum. This marked the beginning of the second generation of organic electroluminescent materials—phosphorescent materials. Because these materials can fully utilize both singlet and triplet excitons for emission, they can achieve a theoretical internal quantum efficiency of 100%, significantly improving the material's luminous efficiency.

[0004] Compared with fluorescent materials, phosphorescent materials show lower driving voltage and high efficiency. In the display field, their vividness, color saturation, high contrast and other advantages have enabled them to be commercialized. However, their cost and stability issues are significant, so the third generation of organic light-emitting materials - thermally activated delayed fluorescence (TADF) materials were born. In 2009, the Adachi team demonstrated the application of thermally activated delayed fluorescence materials in OLEDs for the first time, which brought about a huge change in the development of OLEDs. Thermally activated delayed fluorescence (TADF) emitters reduce the energy difference (ΔE) between the singlet state (S1) and the triplet state (T1) through molecular design. ST ), triplet excitons can be upconverted to singlet states using thermal energy via reverse intersystem crossing (RISC). 100% IQE can be achieved by using TADF emitters, which avoids the use of heavy atoms in organic materials. This is known as a "third generation" emitter.

[0005] Recently, a new strategy utilizing hybrid localized and charge transfer (HLCT) excited states has been developed to design deep / pure blue emitters, which can also achieve 100% exciton utilization efficiency via a “hot exciton” pathway. Unlike TADF molecules, these HLCT-based emitters generate blue light by ionizing the high-lying triplet state (T n ) to singlet state (S1 or S2) by the alternating reverse intersystem crossing (hRISC) process to harvest singlet and triplet excitons. n and the small energy gap between the singlet state and T n The large energy gap between the T1 and T2 states is the driving force behind hRISCs via hot exciton channeling. These unique properties effectively prevent the aggregation of triplet excitons, thereby suppressing efficiency droop. Blue electroluminescence (EL) presents a unique challenge, as blue photons have the highest energy required for human color vision. Generating these high photon energies requires large-bandgap emitters, typically with S1 energies greater than 2.7 eV. Since most OLEDs consist of an EML with an emitter doped into a matrix, these matrices must also be stable to such high-energy charge carriers and excitons, significantly limiting the choice of available chemical groups. Furthermore, to support the high device efficiencies unlocked by triplet harvesting in the emissive dopant, the host must also possess a higher triplet energy than the emitter. These considerations also apply to red and green OLEDs, where requirements become particularly restrictive at the high energies associated with blue emission, which approaches or even exceeds the bond dissociation energy of some organic materials. The relatively weak metal-ligand bonds associated with phosphorescent complexes are believed to be the main reason why blue OLEDs have not developed as rapidly as other colors, and these material stability issues are also the main factor leading to the severe efficiency decline of blue OLEDs in recent years. Therefore, some innovative concepts are needed to design new blue materials. Summary of the Invention

[0006] To expand the variety of blue luminescent materials, the present invention uses benzotriazole (triazole) with excellent physical and chemical properties as the molecular structure center, and then uses bis(3,5-di-tert-butylphenyl)amine, bis(3,5-diphenyl)amine, bis(3,5-dimethoxyphenyl)amine, 9,9-dimethylacridine, 3,6-di-tert-butylcarbazole or 4,4-difluorodiphenylamine as electron-donating groups to synthesize a new type of blue luminescent material through the Buchwald-Hartwig coupling reaction, and uses it as the main material in the luminescent layer. This type of material has the following structure:

[0007]

[0008] The preferred structure of this type of material is shown below:

[0009]

[0010] First, benzotriazole was obtained by modifying the structure of the benzotriazole core. The specific steps are as follows:

[0011] (1) A mixed solution of trimesic acid, diphenylphosphoryl azide (DPPA), triethylamine, and toluene:tert-butyl alcohol was heated to 80°C for reaction for 3 hours, then heated to 120°C for reaction for 12 hours. After the reaction was completed, the mixture was cooled to room temperature and extracted with ethyl acetate. The organic layer was collected and washed with water, dried over anhydrous MgSO4, and evaporated to remove the solvent. Ethyl acetate and petroleum ether were then used as eluents to obtain 1,3,5-Boc-aminobenzene.

[0012] (2) 1,3,5-Boc-aminobenzene was added to a mixed solution of ethanol and concentrated hydrochloric acid in a volume ratio of 1:1, and stirred at ambient temperature overnight (12 hours). Ethanol was then added to induce precipitation, and the mixture was filtered to obtain triaminobenzene.

[0013] (3) 4-Bromoaniline was dissolved in anhydrous dichloroethane, placed at 0°C, and trifluoroacetic acid was added. After stirring for 10 minutes, tert-butyl nitrite was added. After reacting for 1 hour, the mixed solution was added to another flask containing potassium carbonate, triaminobenzene, and anhydrous dichloroethane at 0°C. After stirring for 15 minutes, the reaction flask was heated to room temperature and reacted for 12 hours. After the reaction, the mixture was cooled to room temperature and extracted with dichloroethane. The organic layer was collected and washed with water, dried over anhydrous MgSO4, and the solvent was evaporated. Methanol was added to induce precipitation, and the mixture was filtered to obtain M3.

[0014] (4) A mixed solution of M3, copper acetate monohydrate, and pyridine was reacted at 120°C for 3 h. After the reaction, the mixture was cooled to room temperature, water was added, and the pyridine solution was filtered off. Methanol solution was then added to induce precipitation, and the mixture was filtered to obtain benzotriazole.

[0015] Then, benzotriazole was used as the acceptor, and bis(3,5-di-tert-butylphenyl)amine, bis(3,5-diphenyl)amine, bis(3,5-dimethoxyphenyl)amine, 9,9-dimethylacridine, 3,6-di-tert-butylcarbazole or 4,4-difluorodiphenylamine were used as electron donor groups, trisdibenzylideneacetone dipalladium Pd2(dba)3, tri-tert-butylphosphine tetrafluoroborate (TBPBF4), and sodium tert-butoxide were added and dissolved in anhydrous toluene, and the mixed solution was stirred at 120°C for 24 hours. After the reaction is completed and cooled to room temperature, extraction with ethyl acetate is performed. The organic layer is collected, washed with water, dried over anhydrous MgSO₄, and the solvent is evaporated. Dichloroethane and petroleum ether are then used as eluents to obtain TPT-tBuTPA, TPT-TPA, TPT-2OMeTPA, TPT-Ph-DMAC, TPT-Ph-tBuCz, or TPT-2FTPA. The effects of different electron-donating donors on the overall molecular properties were studied, which has important implications for the construction and application of new blue-emitting materials.

[0016] Another object of the present invention is to provide a novel blue luminescent material as a main material of the light-emitting layer of an organic electroluminescent diode, so as to obtain a blue solution-processed organic electroluminescent device with excellent luminescent performance.

[0017] Among them, the guest material of the light-emitting layer of the electroluminescent device is PO-01 [bis(4-phenyl-thiophene[3,2-c]pyridine-C2,N) iridium(III) acetylacetonate] (PO-01).

[0018] The new blue luminescent material is used as the main material in the luminescent layer, and the doping mass ratio of the guest material PO-01 is 5%-20%.

[0019] The present invention has the following technical advantages:

[0020] 1. Utilize the easy-to-modify properties of the benzotriazole core to construct a series of new symmetrical receptor core blue luminescent materials;

[0021] 2. The blue luminescent material constructed with benzotriazole as the conjugated skeleton center, the localized MR structure of the molecular acceptor core is conducive to the molecule obtaining a high fluorescence quantum yield, and the CT between the peripheral electron donor and the central acceptor core and the LE state of the central core itself are conducive to improving the radiation decay rate k of the material. r , improving the material's performance, and TPT-TPA has a high PLQY (fluorescence quantum yield) of 98.86% in toluene solution. High fluorescence quantum yield can improve luminescence efficiency, enhance detection sensitivity, promote photocatalytic reactions, optimize photodetector performance, and promote scientific research and technological progress.

[0022] 3. The systematic study of the electron-donating ability and the influence of different electron-donating units on the overall molecular performance is of great significance for the construction of new blue light-emitting materials based on benzotriazole core.

[0023] The advantages of the present invention are:

[0024] On the one hand: due to the large torsion angle between the donor and acceptor, the overall planarity of the molecule decreases, which is beneficial to inhibit molecular stacking and thus reduce exciton quenching; on the other hand: after modification of the peripheral electron-donating groups, the solubility of the molecule is greatly improved (in chlorobenzene, under heating conditions, the solubility can reach greater than 10 mg / mL), and OLED devices can be prepared by solution processing, which expands the relevant research on blue emitters and serves as the main material in the light-emitting layer, expanding the application of blue light main materials.

[0025] TPT-tBuTPA, TPT-TPA, and TPT-2OMeTPA molecules exhibit HLCT properties, enabling energy transfer from high triplet to singlet states via reverse intersystem crossing (hRISC) of high triplet energy levels. This allows for 100% exciton utilization and prevents triplet aggregation, which can lead to triplet exciton quenching and severely impact luminescence efficiency. TPT-Ph-DMAC molecules exhibit TADF properties, similarly utilizing triplet-to-singlet RISC to achieve 100% exciton utilization, outperforming traditional fluorescent (25% exciton utilization) and phosphorescent materials (which are expensive and have significant environmental impacts due to the presence of heavy metals). The influence of different electron-donating units, both in terms of electron-donating capacity and structure, on the overall molecular performance is of great significance for the development of novel blue-emitting materials based on the benzotriazole core. BRIEF DESCRIPTION OF THE DRAWINGS

[0026]

Figure 1

[0027]

Figure 2

[0028]

Figure 3

[0029]

Figure 4

[0030]

Figure 5

[0031]

Figure 6

[0032] [Figure 7] is the H NMR spectra of the intermediates of the compounds TPT-tBuTPA, TPT-TPA, TPT-2OMeTPA, TPT-Ph-DMAC, TPT-Ph-tBuCz and TPT-2FTPA prepared in Example 1 of the present invention ( 1 1H NMR) (ac).

[0033] [Figure 8] is the H NMR spectra of the compounds TPT-tBuTPA (a), TPT-TPA (b), TPT-2OMeTPA (c), TPT-Ph-DMAC (d), TPT-Ph-tBuCz (e) and TPT-2FTPA (f) prepared in Example 1 of the present invention ( 1 1H NMR). DETAILED DESCRIPTION

[0034] The following specific implementation cases are intended to further illustrate the present invention, but these specific implementation cases do not limit the scope of protection of the present invention in any way.

[0035] Example 1

[0036] The synthesis scheme of the blue luminescent material based on the present invention is as follows:

[0037]

[0038] Synthesis of compound M1:

[0039] A 250 mL two-necked flask was charged with trimesic acid (2.0 g, 9.51 mmol), diphenylphosphoryl azide (DPPA) (9.16 g, 33.31 mmol), triethylamine (3.37 g, 33.31 mmol), and magnetite. Toluene:tert-butyl alcohol (50 mL:30 mL) was then added to the 250 mL two-necked flask. The pale yellow reaction solution was reacted at 80°C for 3 h, then heated to 120°C for 12 h. After completion of the reaction, the reaction mixture was extracted three times with EA (3 × 100 mL), washed three times with water (3 × 100 mL), dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation to obtain a pale yellow solid. Column chromatography using 6:1 PE:EA as the eluent yielded 2.8 g of the pure product, M1 (1,3,5-Boc-aminobenzene), as a white, fluffy solid in a 69% yield. 1 H NMR (400MHz, DMSO) δ9.21(s,1H),7.21(s,1H),1.45(s,9H).

[0040] Synthesis of compound M2:

[0041] A clean, dry 200 mL two-necked flask was charged with 2.0 g of 1,3,5-Boc-aminobenzene (M1) (4.72 mmol). A 1:1 volume ratio of ethanol (20 ml) and concentrated hydrochloric acid (20 ml) was slowly added to the mixture, and the mixture was stirred overnight (12 hours) at ambient temperature. Ethanol was then added to induce precipitation, and the mixture was filtered to obtain M2 as a white solid in a 75% yield. This was used immediately in the next step without further purification.

[0042] Synthesis of compound M3:

[0043] 5.8 g of 4-bromoaniline (5.5 g, 33.77 mmol) and a magnet were added to a 100 mL two-necked flask and dissolved in anhydrous dichloroethane. The reaction flask was placed at 0°C and trifluoroacetic acid (9.02 g, 79.12 1 mmol) was added. After stirring for 10 min, tert-butyl nitrite (4.35 g, 42.2 mmol) was added. After reacting for 1 hour, the mixed solution in the reaction flask was added to another 250 mL two-necked flask at 0°C containing potassium carbonate (7.29 g, 52.75 mmol), 1.3 g of M2 (1.3 g, 10.55 mmol) and anhydrous dichloroethane. After stirring for 15 min, the reaction flask was heated to room temperature and reacted for 12 h. After the reaction, the mixture was cooled to room temperature, extracted three times with DCM (3×100 mL), washed three times with water (3×100 mL), and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, and a large amount of methanol was added until a solid precipitated. The mixture was slurried and filtered, and the filter cake was dried to obtain 3.0 g of orange powder M3 with a yield of 42%. 1 H NMR (400MHz, DMSO) δ7.85 (d, J = 8.4 Hz, 6H), 7.66 (d, J = 8.3 Hz, 6H).

[0044] Synthesis of compound M4:

[0045] A clean, dry 100 mL single-necked flask was charged with M3 (1.0 g, 1.4 mmol), copper acetate monohydrate (2.9 g, 14.8 mmol), and 30 mL of pyridine. The mixture was placed in a thermostatic magnetic stirrer and reacted at 120°C under nitrogen for 3 h. After the reaction, the mixture was cooled to room temperature, water was added, and the pyridine solution was filtered off. Methanol solution was then added to the slurry, filtered, and the filter cake was dried to obtain 300 mg of the product M4 as a dark brown powder with a yield of 30%. 1 H NMR (400MHz, CDCl3) δ8.35 (d, J = 8.6 Hz, 6H), 7.74 (d, J = 8.7 Hz, 6H).

[0046] Synthesis of compound TPT-tBuTPA:

[0047] In a 100 mL two-necked flask, M4 (200 mg, 0.3 mmol) and bis(3,5-di-tert-butylphenyl)amine (422.4 mg, 1.5 mmol), trisdibenzylideneacetone dipalladium Pd2(dba)3 (16.49 mg, 6.0 mmol), tri-tert-butylphosphine tetrafluoroborate (TBPBF4) (10.45 mg, 0.018 mmol), sodium tert-butoxide (115.41 mg, 6.0 mmol), and 20 mL of anhydrous toluene were added. The mixture was evacuated and placed in a constant temperature magnetic stirrer. The mixture was stirred at 120 ° C under nitrogen protection for 24 h. After the reaction, the mixture was cooled to room temperature, and the organic solvent was removed by distillation under reduced pressure. The mixture was extracted with CH2Cl2. The organic phases were combined and dried over anhydrous magnesium sulfate. The organic solvent was removed by rotary evaporation under reduced pressure. The mixture was separated by column chromatography using PE and CH2Cl2 as eluents (volume ratio = 2:1) to obtain a yellow-green solid. The solid was further recrystallized from CH2Cl2 and CH3OH to obtain 156 mg of yellow-green powder TPT-tBuTPA with a yield of 41%. 1 H NMR (400MHz, CDCl3) δ8.25 (d, J = 9.0 Hz, 6H), 7.32 (d, J = 8.6 Hz, 12H), 7.19 (d, J = 9.0 Hz, 6H), 7.10 (d, J = 8.6 Hz, 12H), 1.34 (s, 56H).

[0048] Synthesis of compound TPT-TPA:

[0049] In a 100 mL two-necked flask, M4 (300 mg, 0.45 mmol) and bis(3,5-diphenyl)amine (381.4 mg, 2.25 mmol), trisdibenzylideneacetone dipalladium Pd2(dba)3 (24.74 mg, 0.027 mmol), tri-tert-butylphosphine tetrafluoroborate (TBPBF4) (15.67 mg, 0.05 mmol), sodium tert-butoxide (173.11 mg, 1.8 mmol), and 25 mL of anhydrous toluene were added. The mixture was evacuated and placed in a constant temperature magnetic stirrer. The mixture was stirred at 120 ° C under nitrogen protection for 24 h. After the reaction, the mixture was cooled to room temperature, and the organic solvent was removed by distillation under reduced pressure. The mixture was extracted with CH2Cl2, and the organic phases were combined and dried over anhydrous magnesium sulfate. The organic solvent was removed by rotary evaporation under reduced pressure, and column chromatography was performed using PE and CH2Cl2 as eluents (volume ratio = 2:1) to obtain a green solid. The solid was further recrystallized with CH2Cl2 and CH3OH to obtain 200 mg of green powder TPT-TPA with a yield of 47%. 1 HNMR (400MHz, CDCl3) δ8.29 (d, J = 9.1Hz, 6H), 7.35-7.29 (m, 12H), 7.24-

[0050] 7.16(m,18H),7.10(t,J=7.4Hz,6H).

[0051] Synthesis of compound TPT-2OMeTPA:

[0052] In a 100 mL two-necked flask, M4 (300 mg, 0.45 mmol) and bis(3,5-dimethoxyphenyl)amine (516.26 mg, 2.25 mmol), trisdibenzylideneacetone dipalladium Pd2(dba)3 (24.74 mg, 0.027 mmol), tri-tert-butylphosphine tetrafluoroborate (TBPBF4) (15.67 mg, 0.054 mmol), sodium tert-butoxide (173.11 mg, 1.8 mmol), and 25 mL of anhydrous toluene were added. The mixture was evacuated and placed in a constant temperature magnetic stirrer. The mixture was stirred at 120 ° C under nitrogen protection for 24 h. After the reaction, the mixture was cooled to room temperature, and the organic solvent was removed by distillation under reduced pressure. The mixture was extracted with CH2Cl2. The organic phases were combined and dried over anhydrous magnesium sulfate. The organic solvent was removed by rotary evaporation under reduced pressure. The mixture was separated by column chromatography using pure CH2Cl2 as an eluent to obtain a yellow-green solid. The solid was further recrystallized from CH2Cl2 and CH3OH to obtain 210 mg of yellow-green powder TPT-2OMeTPA with a yield of 42%. 1 H NMR (400MHz, CDCl3) δ8.20-8.17(m,6H),7.14-7.09(m,13H),7.04-7.01(m,6H),6.89-6.84(m,12H),3.81(s,18H).

[0053] Synthesis of compound TPT-Ph-DMAC:

[0054] In a 100 mL two-necked flask, M4 (300 mg, 0.45 mmol), 9,9-dimethylacridine (471.27 mg, 2.25 mmol), trisdibenzylideneacetone dipalladium Pd2(dba)3 (24.74 mg, 0.027 mmol), tri-tert-butylphosphine tetrafluoroborate (TBPBF4) (15.67 mg, 0.054 mmol), sodium tert-butoxide (216.39 mg, 2.25 mmol), and 20 mL of anhydrous toluene were added. The mixture was evacuated and placed in a constant temperature magnetic stirrer. The mixture was stirred at 120 ° C under nitrogen protection for 24 h. After the reaction, the mixture was cooled to room temperature, and the organic solvent was removed by distillation under reduced pressure. The mixture was extracted with CH2Cl2. The organic phases were combined and dried over anhydrous magnesium sulfate. The organic solvent was removed by rotary evaporation under reduced pressure. The mixture was separated by column chromatography using PE and CH2Cl2 as eluents (volume ratio = 2:1) to obtain a yellow solid. The solid was further recrystallized from CH2Cl2 and CH3OH to obtain 213 mg of yellow powder TPT-Ph-DMAC, with a yield of 45%. 1H NMR (300MHz, CDCl3) δ8.77(d,J=8.6Hz,6H),7.63(d,J=8.7Hz,6H),7.50(dd,J=7.4,1.9 Hz, 6H), 7.03 (t, J = 7.0 Hz, 6H), 6.97 (t, J = 6.8 Hz, 6H), 6.42–6.36 (m, 6H), 1.73 (s, 19H).

[0055] Synthesis of compound TPT-Ph-tBuCz:

[0056] M4 (300 mg, 0.45 mmol) and 3,6-di-tert-butylcarbazole (629.21 mg, 2.25 mmol), trisdibenzylideneacetone dipalladium Pd2(dba)3 (24.74 mg, 0.027 mmol), tri-tert-butylphosphine tetrafluoroborate (TBPBF4) (15.67 mg, 0.05 mmol), sodium tert-butoxide (173.11 mg, 1.8 mmol), and 25 mL of anhydrous toluene were added to a 100 mL two-necked flask. The mixture was evacuated and placed in a constant temperature magnetic stirrer. The mixture was stirred at 120 ° C under nitrogen protection for 24 h. After the reaction, the mixture was cooled to room temperature, and the organic solvent was removed by distillation under reduced pressure. The mixture was extracted with CH2Cl2. The organic phases were combined and dried over anhydrous magnesium sulfate. The organic solvent was removed by rotary evaporation under reduced pressure. The mixture was separated by column chromatography using PE and CH2Cl2 as eluents (volume ratio = 1:1) to obtain a brown solid. The solid was further recrystallized from CH2Cl2 and CH3OH to obtain 231 mg of white-brown powder TPT-Ph-tBuCz with a yield of 40%. 1 H NMR (400MHz, CDCl3) δ 8.75–8.70 (m, 6H), 8.19–8.16 (m, 6H), 7.87–7.83 (m, 6H), 7.53 (dd, J = 8.7, 1.9Hz, 6H), 7.48 (d, J = 8.6Hz, 6H), 1.49 (s, 54H).

[0057] Synthesis of compound TPT-2FTPA:

[0058] In a 100 mL two-necked flask, M4 (467 g, 0.7 mmol), 4,4-difluorodiphenylamine (720 mg, 3.5 mmol), trisdibenzylideneacetone dipalladium Pd2(dba)3 (38.51 mg, 0.04 mmol), tri-tert-butylphosphine tetrafluoroborate (TBPBF4) (24.4 mg, 0.08 mmol), sodium tert-butoxide (269.74 mg, 2.8 mmol), and 30 mL of anhydrous toluene were added. The mixture was evacuated and placed in a constant temperature magnetic stirrer. The mixture was stirred at 120 ° C under nitrogen protection for 24 h. After the reaction, the mixture was cooled to room temperature, and the organic solvent was removed by distillation under reduced pressure. The mixture was extracted with CH2Cl2. The organic phases were combined and dried over anhydrous magnesium sulfate. The organic solvent was removed by rotary evaporation under reduced pressure. The mixture was separated by column chromatography using PE and CH2Cl2 as eluents (volume ratio = 2:1) to obtain a brown solid. The solid was further recrystallized from CH2Cl2 and CH3OH to obtain 320 mg of light green powder TPT-2FTPA, with a yield of 43.9%. 1 H NMR (400MHz, CDCl3) δ8.28-8.23(m,6H),7.15-7.09(m,18H),7.06-7.01(m,12H).

[0059] Example 2

[0060] The compounds TPT-tBuTPA, TPT-TPA, TPT-2OMeTPA, TPT-Ph-DMAC, TPT-Ph-tBuCz and TPT-2FTPA in Example 1 were dissolved in chlorobenzene and heated to 100° C. The solubility was 10 mg / mL.

[0061] The compounds TPT-tBuTPA, TPT-TPA, TPT-2OMeTPA, TPT-Ph-DMAC, TPT-Ph-tBuCz and TPT-2FTPA in Example 1 were dissolved in toluene to prepare 10 -5 M solution, and tested its UV-visible absorption (UV), photoluminescence spectrum (PL) and photoluminescence spectrum (PL) under 10wt% PMMA. Figure 1 -a, the UV-visible absorption spectrum of the compound TPT-tBuTPA in solution has roughly two absorption peaks of different intensities: the weak absorption peak at short wavelength (280-330nm) is mainly attributed to the π-π* transition absorption of the molecule; the strong absorption peak at long wavelength (395nm) is attributed to the charge transfer (ICT) transition absorption peak from the electron-donating unit to the electron-withdrawing unit in the molecule. Figure 1-a, where the maximum emission peak of the compound TPT-tBuTPA is 462nm, in the blue light region. Under 10wt% PMMA, the maximum emission peak of the compound TPT-tBuTPA is at 488nm, red-shifted by 26nm, due to aggregation. Figure 1 -b shows that the UV-visible absorption spectrum of the compound TPT-TPA in solution has roughly two absorption peaks: the absorption peak at a wavelength (280-330nm) is mainly attributed to the π-π* transition absorption of the molecule; the absorption peak at a wavelength (392nm) is attributed to the charge transfer (ICT) transition absorption peak from the donor unit to the acceptor unit within the molecule. Figure 1 -b, where the maximum emission peak of the compound TPT-TPA is 450nm, in the blue light region. Under 10wt% PMMA, the maximum emission peak of the compound TPT-TPA is at 472nm, red-shifted by 22nm, due to aggregation. Figure 1 -c shows that the UV-visible absorption spectrum of the compound TPT-2OMeTPA in solution has roughly two absorption peaks: the absorption peak at a wavelength (280-330nm) is mainly attributed to the π-π* transition absorption of the molecule; the absorption peak at a wavelength (400nm) is attributed to the charge transfer (ICT) transition absorption peak from the donor unit to the acceptor unit within the molecule. Figure 1 -c, where the maximum emission peak of the compound TPT-2OMeTPA is 486nm, in the blue-green region. Under 10wt% PMMA, the maximum emission peak of the compound TPT-tBuTPA is at 511nm, red-shifted by 25nm, due to aggregation. Figure 1 -d, the UV-visible absorption spectrum of the compound TPT-Ph-DMAC in solution has roughly two absorption peaks of different intensities: the absorption peak at short wavelength (280-350nm) is mainly attributed to the π-π* transition absorption of the molecule; the absorption peak at long wavelength (380nm) is attributed to the charge transfer (ICT) transition absorption peak from the electron-donating unit to the electron-withdrawing unit in the molecule. Figure 1 -d, where the maximum emission peak of the compound TPT-Ph-DMAC is 472nm, in the blue light region. Under 10wt% PMMA, the maximum emission peak of the compound TPT-Ph-DMAC is at 476nm, red-shifted by 4nm, due to aggregation. Figure 1 -e, the UV-visible absorption spectrum of the compound TPT-Ph-tBuCz in solution has roughly two absorption peaks: the absorption peak at a wavelength (280-320nm) is mainly attributed to the π-π* transition absorption of the molecule; the absorption peak at a wavelength (370nm) is attributed to the charge transfer (ICT) transition absorption peak from the donor unit to the acceptor unit within the molecule. Figure 1-e, the maximum emission peak of the compound TPT-Ph-tBuCz is 434nm, in the blue light region. The maximum emission peak of the compound TPT-TPA under 10wt% PMMA is at 434nm, and no obvious red shift occurs. The spectrum is less affected by concentration. Figure 1 -d, the UV-visible absorption spectrum of compound TPT-2FTPA in solution has roughly two absorption peaks of different intensities: the absorption peak at short wavelength (280-425nm) is mainly attributed to the π-π* transition absorption of the molecule; the absorption peak at long wavelength (380nm) is attributed to the charge transfer (ICT) transition absorption peak from the electron-donating unit to the electron-withdrawing unit in the molecule. Figure 1 -f, where the maximum emission peak of compound TPT-2FTPA is 448 nm, in the blue region. Under 10 wt% PMMA, the maximum emission peak of compound TPT-2FTPA is at 472 nm, red-shifted by 24 nm, which is caused by aggregation.

[0062] Example 3

[0063] The fluorescence (Fl) and phosphorescence (Ph) of the compound TPT-tBuTPA in Example 1 were measured at low temperature. Figure 2 As shown in Figure 1-a, based on the starting points of the Fl and Ph spectra, the S1 / T1 energy levels of TPT-tBuTPA can be calculated to be 3.00 / 2.58 Ev. The fluorescence (Fl) and phosphorescence (Ph) of the compound TPT-TPA measured at low temperature. Figure 2 As shown in Figure 2-b, based on the starting points of the Fl and Ph spectral emissions, the S1 / T1 energy levels of TPT-TPA can be calculated to be 3.02 / 2.61 Ev. The fluorescence (Fl) and phosphorescence (Ph) of the compound TPT-2OMeTPA measured at low temperature. Figure 2 As shown in Figure 2-c, based on the starting points of the Fl and Ph spectral emissions, the S1 / T1 energy levels of TPT-2OMeTPA can be calculated to be 2.90 / 2.58 Ev. The fluorescence (Fl) and phosphorescence (Ph) of the compound TPT-Ph-DMAC measured at low temperature. Figure 2 As shown in Figure 1-d, based on the starting points of the Fl and Ph spectral emissions, the S1 / T1 energy levels of TPT-Ph-DMAC can be calculated to be 3.10 / 2.74 Ev. The fluorescence (Fl) and phosphorescence (Ph) of the compound TPT-Ph-tBuCz measured at low temperature are shown in Figure 1-d. Figure 2 -e, according to the starting point of the Fl and Ph spectrum emission, the S1 / T1 energy level of TPT-Ph-tBuCz can be calculated to be 3.28 / 2.88Ev. The fluorescence (Fl) and phosphorescence (Ph) of the compound TPT-2FTPA measured at low temperature. Figure 2-f, according to the starting points of Fl and Ph spectral emissions, the S1 / T1 energy levels of TPT-2FTPA can be calculated to be 3.08 / 2.61 Ev.

[0064] Example 4

[0065] The compounds TPT-tBuTPA, TPT-TPA and TPT-2OMeTPA in Example 1 were -5 M) measured the solvation effect diagram. Figure 3 As shown, the three compounds will emit narrow spectrum localized state in low polarity solvents, and exhibit broad spectrum emission without fine structure in high polarity solvents, which indicates that the molecules may have HLCT characteristics.

[0066] Example 5

[0067] The compounds TPT-tBuTPA, TPT-TPA and TPT-2OMeTPA prepared in Example 1 conform to the Lippert-Mataga curve of HLCT characteristics. Figure 4 As shown, the three compounds exhibit two linear fittings in low-polarity solvents and high-polarity solvents, respectively, indicating the existence of two different excited states, which is consistent with the HLCT characteristics.

[0068] Example 6

[0069] The fluorescence lifetime of the compound TPT-Ph-DMAC in Example 1 in a 10 wt% doped PMMA film was tested under vacuum. Figure 5 As shown, TPT-Ph-DMAC has a delayed component and a long lifetime, with a biexponential decay, which is consistent with the characteristics of TADF. (Other molecules were not observed to have long lifetimes in transient PL and therefore do not possess TADF properties.)

[0070] Example 7

[0071] The application of the compound TPT-TPA in Example 1 in an organic electroluminescent device. The compound is used as a dopant in the light-emitting layer of the device, and the device structure is an organic electroluminescent diode of ITO / PEDOT:PSS (35nm) / PVK (60nm) / EML (TPT-TPA:PO-01 (5wt%, 10wt%, 15wt%, 20wt%)) / DPEPO (10nm) / TmPyPB (50nm) / LiF (1nm) / Al (120nm). Among them, PEDOT:PSS is a hole injection layer; PVK is a hole transport layer; DPEPO is a hole blocking layer; TmPyPB is an electron transport layer; LiF / Al is a cathode. EML is a light-emitting layer, including TPT-TPA and PO-01, and the doping concentration of PO-01 in the light-emitting layer is 5, 10, 15, and 20wt%. Figure 6 As shown in (a), TPT-TPA is used as a host material, showing the electroluminescence spectrum of the PO-01 device after being doped with the host material. The emission is at 562-566nm, which has little effect on the spectrum of the guest material, making it an ideal host material. The devices with TPT-TPA doped in PO-01 at 5, 10, 15, and 20 wt% respectively achieved maximum external quantum efficiencies of 16.8%, 21.2%, 15.2%, and 10.3%. Figure 6 (b) shown; wherein the molecular structure of compound PO-01 is as shown Figure 6 (c) shown.

[0072] The device solution processing preparation method: The substrate is pretreated with oxygen plasma to enhance the functionality of the ITO thin film. Then, PEDOT:PSS is spin-coated onto the ITO substrate at 3200 rpm for 30 seconds and annealed at 150°C for 15 minutes to form a 35nm thick hole injection layer. A prepared host-guest mixed solution (the luminescent layer has PO-01 doping levels of 5, 10, 15, and 20 wt% in chlorobenzene (10 mg / ml)) is spin-coated onto the hole transport layer at 80°C and annealed for 30 minutes. DPEPO, TmPyPB, and a LiF / Al cathode are then sequentially evaporated onto the luminescent layer, hole blocking layer, and electron transport layer to produce a device containing the luminescent molecule of the present invention.

[0073] Example 8

[0074] The intermediates of the compounds TPT-tBuTPA, TPT-TPA and TPT-2OMeTPA prepared in Example 1 are shown in FIG7 ( 1 1H NMR) (ac).

[0075] Example 9

[0076] The H NMR spectra of the compounds TPT-tBuTPA (a), TPT-TPA (b) and TPT-2OMeTPA (c) prepared in Example 1 are shown in FIG8 ( 1 1H NMR) (ac).

[0077] Although the present invention has been described in conjunction with the preferred embodiments, the present invention is not limited to the above embodiments, and it should be understood that the appended claims summarize the scope of the present invention. Under the guidance of the inventive concept, those skilled in the art should appreciate that certain changes made to the various embodiments of the present invention will be covered by the spirit and scope of the claims of the present invention.

Claims

1. A class of blue luminescent materials based on benzotriazole, characterized by: The synthesis method of the blue luminescent material comprises: using benzotriazole as an acceptor, and then using bis(3,5-di-tert-butylphenyl)amine, bis(3,5-diphenyl)amine, bis(3,5-dimethoxyphenyl)amine, 9,9-dimethylacridine, 3,6-di-tert-butylcarbazole or 4,4-difluorodiphenylamine as electron-donating groups. Buchwald-Hartwig Synthesis of blue luminescent materials based on benzotriazole by coupling reaction.

2. The blue luminescent material based on benzotriazole according to claim 1, characterized in that: The molecular structure of the blue light-emitting material is shown below:

3. The blue luminescent material based on benzotriazole as claimed in claim 1, characterized in that: The molecular structure of the blue light-emitting material is shown below:

4. The blue luminescent material based on benzotriazole according to claim 1, characterized in that: The synthesis method of benzotriazole is as follows: Boc protection is performed to obtain 1,3,5-Boc-aminobenzene; 1,3,5-Boc-aminobenzene is then deprotected to obtain triaminobenzene; and then diazotization and oxidation are performed to obtain benzotriazole.

5. A use of the blue luminescent material based on benzotriazole as claimed in claim 1, characterized in that: The blue luminescent material is used for preparing an organic electroluminescent device.

6. The use of the blue luminescent material based on benzotriazole as claimed in claim 5, characterized in that: Blue light-emitting materials are used as host materials for the light-emitting layer of organic electroluminescent diodes.

7. The use of the blue luminescent material based on benzotriazole as claimed in claim 6, characterized in that: The guest material of the light-emitting layer of the organic electroluminescent diode is PO-01.

8. The use of the blue luminescent material based on benzotriazole as claimed in claim 7, characterized in that: The mass ratio of the guest material PO-01 in the light-emitting layer is 5%-20%.

9. The use of the blue luminescent material based on benzotriazole as claimed in claim 5, characterized in that: Organic electroluminescent devices are prepared by solution processing.

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