Diamine monoboron compounds and their derived polymers and their use in the field of OLEDs

Abstract

The application belongs to the field of organic photoelectric materials and its application, discloses a kind of diamin monoboron compound and its derived polymer and their application in OLED field, the diamin monoboron compound has general structure as indicated in at least one of general formula A-1 to general formula A-4.This application improves the chemical structure of diamin monoboron compound, and the corresponding diamin monoboron compound can be applied to OLED device light-emitting layer, and its derived polyimide polymer can be applied to OLED flexible substrate.Based on B-N resonance effect and long-range charge transfer state and short-range charge transfer state interaction, the orbital spin coupling constant between ground state and excited state is improved, and the diamin monoboron compound can effectively improve the color purity of OLED device, and prepare high-efficiency, low-driving-voltage blue-violet light (i.e., 400nm-430nm) and narrow-emission OLED device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic optoelectronic materials and their applications, and more particularly relates to a class of diamine-based monoboron compounds and their derived polymers and their applications in the field of OLEDs. BACKGROUND

[0002] Organic electroluminescence technology (OLED) has been widely used in the display field due to its self-luminescence, fast response speed, flexibility and foldability, etc. At the same time, with the continuous development of OLED-related technologies and the continuous improvement of consumers' requirements for product performance, the current organic luminescent materials generally face the problem of too wide emission spectrum full width at half maximum (FWHM) (70-100 nm), so that OLED cannot directly realize high color purity display, and corresponding solutions are urgently needed.

[0003] The third generation of thermally activated delayed fluorescence materials (TADF) realizes 100% internal quantum efficiency in small organic molecules, which is expected to replace existing traditional fluorescent materials and phosphorescent light-emitting materials, and has advantages in cost and efficiency. However, TADF materials generally have strong structural relaxation characteristics due to their molecular design, resulting in a FWHM of their luminescence spectrum usually above 70 nm, which greatly affects the color purity of OLED devices. To solve this problem, Professor T. Hatakeyama of Gakushuin University and others developed thermally induced delayed fluorescence materials with multiple resonance characteristics (MR-TADF), which principle is to realize the separation of molecular HOMO / LUMO on the atomic scale through the opposite resonance effect of electron-deficient atoms (B) and electron-rich atoms (N), thereby obtaining an extremely narrow FWHM while maintaining the characteristics of TADF materials. However, most of the MR-TADF molecules reported so far use weak donors or acceptors to modify the resonance skeleton, making the front orbital energy level distribution mainly dominated by short-range charge transfer states (SRCT), resulting in weak orbital spin coupling (SOC) between the ground state and the excited state, which limits the performance of OLED devices based on MR-TADF molecules. At the same time, weak donors or acceptors are difficult to significantly adjust the light color of MR-TADF molecules, and most MR-TADF molecules emit sky blue or green light, making it very lacking in high-performance, blue-violet light-emitting MR-TADF molecules at the present stage.

[0004] A group of single boron derivatives based on fluorene-based aniline fusion donors, their preparation and application were obtained by the inventors of the present invention in the previous study (see Chinese patent CN 202210431760.2). A rigid group fluorene derivative is introduced on the basis of retaining an electron-rich N atom, and a new fusion donor is formed by combination. This kind of fusion donor based on fluorene-based aniline has the characteristics of rigidity and bulkiness. The single boron derivative based on fluorene-based aniline fusion donor is obtained, and based on the B-N resonance effect, FWHM below 30 nm can be achieved, which can effectively improve the color purity of OLED devices. However, the emission wavelength of this series of single boron derivatives is 440 nm to 500 nm, and the light color is still difficult to meet the blue light standard of BT.2020 issued by the International Telecommunication Union Radio Communication Department (ITU-R). In fact, the currently reported narrow emission boron-nitrogen derivatives are almost difficult to have blue-violet light (in the field, the wavelength of "blue-violet light" is 400 nm to 430 nm) (ref: Chinese Journal of Organic Chemistry 2023, 43(5) 1645-1690), so it is urgent to explore high-performance, blue-violet light-emitting MR-TADF molecules.

[0005] In addition, in recent years, polyimide film is often selected as the preferred material for OLED flexible substrate, because polyimide has excellent thermal stability, chemical stability, mechanical properties, etc. However, the dielectric constant and dielectric loss of traditional polyimide are generally high. For example, the dielectric constant (D k ) value of commercial Kapton film is 3.4 and the dielectric loss (D f ) value is 0.016 at 10 GHz, which easily leads to serious transmission loss of OLED devices. In addition, charge transfer complexes are easily formed between polyimide molecular chains, which makes the optical transparency of the film often poor, which easily affects the overall performance of OLED devices. Therefore, how to improve the dielectric and optical properties of polyimide film substrate has become a research hotspot. SUMMARY

[0006] In view of the above defects or improvement needs of the prior art, the purpose of the present application is to provide a kind of diamine monoboron compound and its derived polymer and their application in OLED field, wherein by improving the chemical structure of diamine monoboron compound, the general formula A-1 to general formula A-4 (R1, R2 group in each general formula meets the specific group requirement) with specific chemical structure is formed, the corresponding obtained diamine monoboron compound can be applied to OLED device light-emitting layer, and its derived polyimide polymer can be applied to OLED flexible substrate.Based on B-N resonance effect and long-range charge transfer state and short-range charge transfer state interaction, the orbital spin coupling constant between ground state and excited state is improved, the color purity of OLED device can be effectively improved by the diamine monoboron compound, and high-efficiency, low-driving-voltage blue-violet light (i.e., 400nm-430nm) and narrow emission (half peak width FWHM is below 30nm) OLED device is prepared;based on extremely rigid bulky side group structure and improved polymer free volume, the polyimide polymer derived from the diamine monoboron compound is beneficial to prepare flexible OLED substrate with excellent optical and dielectric properties.

[0007] To achieve the above purpose, according to one aspect of the present application, a kind of diamine monoboron compound is provided, characterized in that the diamine monoboron compound has general formula structure as indicated in at least one of general formula A-1 to general formula A-4,

[0008]

[0009] Wherein, R1, R2 group is independently selected from hydrogen, deuterium, methyl, phenyl, methoxy, trifluoromethyl, tert-butyl, naphthyl, anthryl, silane group, halogen, pyrazine, pyridine, pyrimidine, benzimidazole ring, carbazole, indolocarbazole, phenoxazine, phenothiazine, phenoselenazine, phenanthroimidazole, substituted or unsubstituted C2-C 10 Straight-chain alkyl, substituted or unsubstituted C2-C 10 Straight-chain alkyl, substituted or unsubstituted C2-C 30 Aryl, substituted or unsubstituted C2-C 10 Alkoxy, substituted or unsubstituted C1-C 10 Alkylamino, substituted or unsubstituted C2-C 10 Silane group.

[0010] As a further preferred embodiment of the present application, the R1 group is selected from hydrogen, methyl, phenyl, trifluoromethyl, tert-butyl, halogen, pyrazine, pyridine, pyrimidine, phenoxazine, phenothiazine, phenoselenazine; the R2 group is selected from hydrogen, methyl, trifluoromethyl, tert-butyl, halogen.

[0011] As a further preferred embodiment of the present application, the structure of the diamine monoboron compound is as shown in any one of formula 1 to formula 144:

[0012]

[0013]

[0014]

[0015]

[0016]

[0017] According to another aspect of the present application, the present application provides a polyimide polymer derived from the above-mentioned diamine-based monoboron compound, characterized in that the polyimide polymer has a general structure as shown in at least one of the general formula B-1 to general formula B-4:

[0018]

[0019] wherein Ar is a tetravalent aromatic group; n is a natural number from 1 to 1000;

[0020] The general formula B-1 is derived from the diamine-based monoboron compound satisfying the general formula A-1;

[0021] The general formula B-2 is derived from the diamine-based monoboron compound satisfying the general formula A-2;

[0022] The general formula B-3 is derived from the diamine-based monoboron compound satisfying the general formula A-3;

[0023] The general formula B-4 is derived from the diamine-based monoboron compound satisfying the general formula A-4.

[0024] As a further preferred embodiment of the present application, Ar is selected from:

[0025]

[0026] According to yet another aspect of the present application, the present application provides an application of the above-mentioned diamine-based monoboron compound and / or the above-mentioned polyimide polymer in an organic electroluminescent device.

[0027] As a further preferred embodiment of the present application, the diamine-based monoboron compound is particularly applied in a light-emitting layer of an organic electroluminescent device as a guest light-emitting material;

[0028] The polyimide polymer is particularly applied in a flexible substrate of an organic electroluminescent device as a thin film material.

[0029] As a further preferred embodiment of the present application, the organic electroluminescent device comprises, in sequence, an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, a cathode;

[0030] Preferably, an electron blocking layer or an exciton blocking layer is further arranged between the hole transport layer and the light-emitting layer; and a hole blocking layer or an exciton blocking layer is further arranged between the light-emitting layer and the electron transport layer.

[0031] Compared with the reported MR-TADF compounds, the diamine monoboron compound in the present application has multiple resonance induction effect, thermally delayed fluorescence characteristics and LRCT / SRCT interaction, which can make the singlet and triplet energy levels different, realize the narrowing of the half peak width of the light-emitting spectrum and high-efficiency fluorescent emission, and be applied to the light-emitting layer structure of the organic electroluminescent device (OLED) as the organic fluorescent light-emitting material, which is beneficial to improve the color purity of the OLED light-emitting and make the light color obviously blue-shifted, and is beneficial to prepare high-performance blue-violet light narrow-emission OLED device.

[0032] In addition, compared with the flexible OLED polyimide substrate in the prior research CN 202210431760.2, the diamine monoboron compound derived polyimide has extremely rigid bulky side groups and increased free volume, which inhibits the formation of charge transfer complexes in the molecular chain, thereby reducing the dielectric constant and dielectric loss of the polyimide substrate and improving the optical transparency.

[0033] The present application uses a multiple resonance nucleus based on a boron-nitrogen structure, which can realize a FWHM of less than 30 nm, and can effectively improve the color purity of the OLED device. max ), which is beneficial to prepare high-performance narrow-emission blue-violet light OLED devices.

[0034] Specifically, the present invention can achieve the following beneficial effects:

[0035] (1) This invention expands a new MR-TADF luminescent molecular system by modifying the periphery of the multi-resonance core with strong donor amino groups. While maintaining the narrow emission spectrum characteristics, the strong N-π-B structure effectively weakens the electron-withdrawing ability of B atoms, thereby making the light color significantly blue-shifted, so as to solve the problem of the scarcity of narrow emission blue-violet MR-TADF materials at present.

[0036] (2) The diamine-based monoboron compounds described in this invention possess LRCT / SRCT interactions, which are beneficial for enhancing spin-orbit coupling. When applied to the emissive layer in organic electroluminescent devices, they can further improve device performance and facilitate the fabrication of high-efficiency, low-driving-voltage blue-violet narrow-emission OLED devices. As illustrated in the examples below, this invention significantly improves EQE and blue-violet light color on the basis of narrow emission.

[0037] (3) The polyimide derived from the diamine monoboron compound described in this invention has extremely rigid large-volume side groups. When applied to the flexible substrate in organic electroluminescent devices, it can enhance the free volume of the substrate film and reduce the generation of charge transfer complexes, thereby making the polyimide film described in this invention have low dielectric constant, dielectric loss and excellent optical properties.

[0038] (4) Furthermore, the material obtained by the present invention can be used simultaneously in the light-emitting layer and the flexible substrate (as described below). Figure 5 (As shown), this is the first report.

[0039] This invention develops novel MR-TADF diamine-based monoboron compounds with a strong donor amino group as the core. These diamine-based monoboron compounds possess long-range charge-transfer states, increasing the orbital-spin coupling constant between the ground and excited states, which is beneficial for fabricating high-performance blue-violet narrow-emission OLED devices. The polyimide polymers derived from these diamine-based monoboron compounds have large rigid side groups and free volume, which helps suppress the formation of charge-transfer complexes and facilitates the fabrication of flexible OLED substrates with high transparency and excellent dielectric properties. In summary, the diamine-based monoboron compounds and their derived polyimide polymers in this invention have significant scientific and technological value and promising industrial applications. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of an electroluminescent device.

[0041] Figure 2 The external quantum efficiency-current density relationship characteristic curves are shown for device examples 1 to 5.

[0042] Figure 3Driving voltage comparison chart for device examples 1 to 5 and device comparative example 1.

[0043] Figure 4 Dielectric property comparison chart for thin film examples 1, 9, 12, 15 and thin film comparative example 1.

[0044] Figure 5 Schematic diagram of application of diamine monoboron compound and derived polymer thereof in the present application to electroluminescent device. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0046] In general, the diamine monoboron compound in the present application has a general structure as shown in at least one of general formula A-1 to general formula A-4; the polyimide derived based on the diamine monoboron compound has a general structure as shown in at least one of general formula B-1 to general formula B-4:

[0047]

[0048] wherein R1, R2 groups are independently selected from the group consisting of hydrogen, deuterium, methyl, phenyl, methoxy, trifluoromethyl, t-butyl, naphthyl, anthryl, silyl, halogen, pyrazine, pyridine, pyrimidine, benzimidazole ring, carbazole, indolocarbazole, phenoxazine, phenothiazine, phenoselenazine, phenanthroimidazole, substituted or unsubstituted C2~C 10 linear alkyl, substituted or unsubstituted C2~C 10 branched alkyl, substituted or unsubstituted C7~C 30 aryl, substituted or unsubstituted C2~C 10 alkoxy, substituted or unsubstituted C1~C 10 alkylamino, substituted or unsubstituted C2~C 10 silyl; Ar is a tetravalent aromatic group; n = 1 to 1000.

[0049] The synthesis route of general formula A-1 to general formula A-4 is shown as follows:

[0050]

[0051] Taking general formula A-1 to general formula A-4 as an example, 144 specific structure diamine monoboron compounds can be obtained, wherein:

[0052] In Formula 1 to Formula 48, R1 is selected from hydrogen, methyl, tert-butyl, phenyl ring, methyl, pyridine, pyrimidine, pyrazine, halogen, and R2 is hydrogen;

[0053] In Formula 49 to Formula 60, R1 is hydrogen, and R2 is selected from methyl, trifluoromethyl, halogen;

[0054] In Formula 61 to Formula 144, R1 is selected from methyl, tert-butyl, trifluoromethyl, halogen, and R2 is selected from methyl, trifluoromethyl, halogen.

[0055] The following is a synthesis example:

[0056] Synthesis Example 1

[0057] The diamine-based monoboron compound 1 according to the present application conforms to general formula A-1, and has the following structure:

[0058]

[0059] The preparation method comprises the following steps:

[0060]

[0061] (1) 10.00 g (36.64 mmol) of 3,5-dichloroiodobenzene, 9.97 g (38.48 mmol) of 4,4'-dinitrosodiphenylamine, 15.19 g (109.93 mmol) of potassium carbonate, 0.70 g (3.66 mmol) of cuprous iodide, and 0.84 g (7.33 mmol) of L-proline were weighed into a 500 mL three-necked flask, and 80 mL of super dry DMF was added. The reaction system was stirred under nitrogen at room temperature, and was refluxed at 150°C for 24 hours. After the reaction was stopped, the reaction system was naturally cooled to room temperature, and the organic phase and the aqueous phase were separated by extraction with dichloromethane and saturated brine. The solvent was removed by rotary evaporation. The crude product was column chromatographed on a silica gel column with petroleum ether / dichloromethane (15:1 by volume), and was dried to obtain a yellow powder of 12.04 g.

[0062]

[0063] (2) Take 10.00 g (24.74 mmol) of the product of the first step, 8.79 g (51.95 mmol) of diphenylamine, 1.13 g (1.24 mmol) of tris-dibenzylideneacetone palladium, 0.72 g (2.47 mmol) of tri-tert-butylphosphine tetrafluoroborate, 14.27 g (148.44 mmol) of sodium tert-butoxide in a 500 mL three-necked flask, and add 60 mL of dry toluene. Then, blow off for 15 minutes under nitrogen, heat to 120°C under nitrogen, and stir for 20 hours. After the reaction is complete, cool to room temperature, extract with dichloromethane and saturated brine, collect the organic layer, dry, and concentrate. Column chromatography of the crude product on a silica gel column using petroleum ether / dichloromethane (15:1 by volume) gives a yellow powder 14.33 g.

[0064]

[0065] (3) Under nitrogen, add 10 g (14.93 mmol) of the product of the second step and o-dichlorobenzene (80 mL) in sequence to a 500 mL three-necked round-bottom flask, and stir until uniform. Then, add 11.51 mL (119.44 mmol) of boron tribromide to the mixture, and after the dropwise addition is complete, warm to 180°C. After stirring at 180°C for 24 hours, cool the reaction to room temperature, add 39.00 mL (223.95 mmol) of N,N-diisopropylethylamine at 0°C, stir for half an hour, add an aqueous sodium acetate solution to adjust the pH to neutral, extract the organic layer with dichloromethane, dry over magnesium sulfate, concentrate under vacuum, remove the o-dichlorobenzene solvent by distillation under reduced pressure at 100°C, and perform column chromatography to obtain a bright yellow powder 7.11 g.

[0066]

[0067] (4) Take 7.00 g (10.33 mmol) of the product of the third step and 1.40 g of palladium on carbon, place in a 500 mL three-necked flask, maintain under nitrogen, add 50 mL of super-dry THF, stir under nitrogen, warm to 68°C, then slowly add 4.4 mL of hydrazine hydrate to the reaction system, and after the dropwise addition is complete, react for 12 hours. After the reaction is stopped, cool the reaction system to room temperature naturally, remove the palladium on carbon by filtration, and then remove the solvent using a rotary evaporator. Column chromatography of the crude product on a silica gel column using petroleum ether / ethyl acetate (8:1 by volume) gives a bright yellow solid with a yield of 75%.

[0068] The characterization results of the diamine-based monoboron derivative are as follows: mass spectrum: 617.28; and nuclear magnetic resonance results are as follows: 1H NMR (500 MHz, Chloroform-d) δ 7.44 - 7.33 (m, 4H), 7.30 - 7.23 (m, 1H), 7.13 - 7.07 (m, 2H), 7.09 - 7.02 (m, 3H), 7.00 (dd, J = 6.7, 1.4 Hz, 1H), 6.66 - 6.59 (m, 2H), 6.57 - 6.51 (m, 1H), 4.00 (d, J = 5.7 Hz, 1H), 3.94 (d, J = 5.7 Hz, 1H).

[0069] Synthesis Example 2

[0070] The diamine-based monoboron compound 2 according to the present application, which conforms to the general formula A-2, has the following structure:

[0071]

[0072] The preparation method comprises the following steps:

[0073]

[0074] (1) 1,3-dibromo-5-chlorobenzene (5.00 g, 18.49 mmol), diphenylamine (6.57 g, 38.84 mmol), sodium tert-butoxide (10.66 g, 110.97 mmol), tri-tert-butylphosphonium tetrafluoroborate (0.54 g, 1.85 mmol), tris(dibenzylideneacetone)dipalladium (0.85 g, 0.93 mmol) and toluene (60 mL) were sequentially added into a 250 mL three-necked round-bottom flask, and stirred at 120°C for 20 hours under a nitrogen atmosphere. After cooling to room temperature, the reaction solution was repeatedly extracted with deionized water and dichloromethane. The crude product was collected and purified on a silica gel column with petroleum ether (PE) / dichloromethane (DCM) as the eluent. The purified product was a white powder, and the yield was 80%.

[0075]

[0076] (2) The product (4.00 g, 8.95 mmol) obtained in the first step and o-dichlorobenzene (40 mL) were sequentially added into a 250 mL three-necked round-bottom flask under nitrogen protection, and stirred uniformly. Subsequently, boron tribromide (3.45 ml, 35.80 mmol) was added into the mixture, and after the dropwise addition was completed, the reaction was carried out at 180°C for 24 hours. Subsequently, the reaction was cooled to room temperature, N,N-diisopropylethylamine (23.38 mL, 134.23 mmol) was added at 0°C, and after stirring for half an hour, the pH was adjusted to neutral by adding an aqueous sodium acetate solution. The organic layer was extracted with dichloromethane, dried with magnesium sulfate, concentrated under vacuum, and the o-dichlorobenzene solvent was removed by distillation under reduced pressure at 100°C. Column chromatography was performed to obtain a bright yellow solid product, and the reaction yield was 50%.

[0077]

[0078] (3) Weigh 5.00 g (10.99 mmol) of the product of the second step, 2.38 g (12.09 mmol) of 3,6-diaminocarbazole, 4.56 g (32.98 mmol) of potassium carbonate, and place them in a 500 mL three-necked flask, keep it under nitrogen atmosphere, and add 50 mL of super dry DMF, stir under nitrogen atmosphere, and heat to 150°C and react for 20 h. After stopping the reaction, the reaction system is naturally cooled to room temperature, the organic phase and the aqueous phase are separated by using dichloromethane and water extraction, and the solvent is removed by rotary evaporation. The crude product is column chromatographed on a silica gel column with petroleum ether / ethyl acetate (8:1 by volume). Dry to obtain a bright yellow solid, with a yield of 87%.

[0079] The characterization results of the diamine monoboron derivative are as follows: mass spectrum is 615.26; and nuclear magnetic resonance results are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.61 (d, J = 7.8 Hz, 1H), 7.47-7.33 (m, 5H), 7.26 (td, J = 7.0, 1.5 Hz, 1H), 7.09-6.98 (m, 1H), 7.05-6.98 (m, 1H), 6.72 (dd, J = 7.8, 2.0 Hz, 1H), 4.26 (s, 2H).

[0080] Synthesis Example 3

[0081] The diamine monoboron compound 3 according to the present application meets general formula A-3, and has the following structure:

[0082]

[0083] The preparation method comprises the following steps:

[0084]

[0085] (1) In a 500 mL three-necked round bottom flask, 11.68 g (36.64 mmol) of 2-bromo-1,3-difluoro-5-iodobenzene, 9.97 g (38.48 mmol) of 4,4'-dinitrosodiphenylamine, 15.19 g (109.93 mmol) of potassium carbonate, 0.70 g (3.66 mmol) of cuprous iodide, 0.84 g (7.33 mmol) of L-proline and 80 mL of super dry DMF were sequentially added into a 500 mL three-necked flask. Subsequently, the mixed solution was heated to 150 °C under nitrogen protection and stirred for 20 hours. After the reaction was completed, it was naturally cooled to room temperature, and the toluene was removed by a rotary evaporator. Then, the reaction solution was extracted with dichloromethane and saturated brine, and the organic phase containing the product was collected. Purification was performed by column chromatography on a silica gel column using petroleum ether / dichloromethane (15:1 by volume) as the eluent, and finally yellow solid crystals were obtained with a yield of 90%.

[0086]

[0087] (2) 10.00 g (22.21 mmol) of the product from the first step, 3.71 g (44.42 mmol) of carbazole, 9.21 g (66.63 mmol) of potassium carbonate and 50 mL of super dry DMF were weighed into a three-necked flask. Subsequently, the reaction system was heated to 150 °C under nitrogen and stirred for 20 hours. After the reaction was completed, it was cooled to room temperature, extracted with dichloromethane and saturated brine, and the organic layer was collected, dried and concentrated. The crude product was column chromatographed on a silica gel column using petroleum ether / dichloromethane (10:1 by volume) as the eluent, and dried to obtain a yellow powder with a yield of 91%.

[0088]

[0089] (3) Weigh 5 g (6.72 mmol) of the product of the second step, add it to a 250 ml three-necked round-bottom flask, and add 100 ml of a t-butylbenzene solution to it, then pump out the nitrogen, and then place the three-necked flask in a low-temperature reaction bath (-40 °C), pump out the air in the needle, and then pump out the t-butyllithium (19.00 ml, 25.20 mmol) under the protection of a nitrogen atmosphere, and then slowly inject it into the flask, and fully stir for 2 h; then warm it to room temperature, pump out again, and pump out the n-pentane in the t-butyllithium solvent; then slowly add boron tribromide (2.40 ml, 25.20 mmol) at -40 °C, stir at room temperature for 1 h; then inject N,N-diisopropylethylamine (7.00 ml, 50.40 mol), warm it to 140 °C, adjust the condensing water to keep the refluxing speed of the reaction proper, and continue to stir the reaction for 12 h. After the reaction is completed, wait for the reaction system to return to room temperature, quench the reaction system with ethanol, spin dry the t-butylbenzene solvent, add an appropriate amount of silica gel to the sample, and separate the crude product by column chromatography using petroleum ether / dichloromethane (10:1 by volume) as the eluent to obtain a yellow solid with a yield of 37%.

[0090]

[0091] (4) Add 6.43 g (9.54 mmol) of the product of the third step, 1.40 g of palladium on carbon, and 50 ml of super-dry THF to a 500 ml three-necked flask, stir under a nitrogen atmosphere, and warm it to 68 °C, and then slowly add 4.2 ml of hydrazine hydrate to the reaction system, and after the addition is completed, react for 18 h. After the reaction is completed, the reaction system is naturally cooled to room temperature, the palladium on carbon is removed by filtration, and then the solvent is removed by rotary evaporation. The crude product is separated by column chromatography on a silica gel column using petroleum ether / ethyl acetate (10:1 by volume). Dry the bright yellow solid to obtain a yield of 80%.

[0092] The characterization results of the diamine-based monoboron derivative are as follows: the mass spectrum is 613.24; and the nuclear magnetic resonance results are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 8.18 (dd, J = 6.2, 1.1 Hz, 1H), 8.15-8.09 (m, 2H), 7.68 (dd, J = 6.3, 1.4 Hz, 1H), 7.39 (ddd, J = 7.4, 6.4, 1.2 Hz, 1H), 7.33 (t, J = 6.1 Hz, 1H), 7.27 (ddd, J = 8.3, 7.1, 1.2 Hz, 1H), 7.14 (dd, J = 19.8, 2.0 Hz, 1H), 7.12-7.07 (m, 2H), 6.66-6.59 (m, 2H), 4.00 (d, J = 5.7 Hz, 1H), 3.94 (d, J = 5.7 Hz, 1H).

[0093] Synthesis Example 4

[0094] The diamine-based monoboron compound 4 according to the present application, which conforms to the general formula A-4, has the following structure:

[0095]

[0096] The preparation method comprises the following steps:

[0097]

[0098] (1) 5.00 g (22.21 mmol) of 2-bromo-5-chloro-1,3-difluorobenzene, 3.71 g (44.42 mmol) of carbazole, 9.21 g (66.63 mmol) of potassium carbonate and 50 mL of super dry DMF were weighed into a 250 mL three-necked round-bottom flask under a nitrogen atmosphere, the temperature was raised to 150°C and the reaction was carried out for 20 hours. After the reaction was completed, the reaction solution was repeatedly extracted with deionized water and dichloromethane. The crude product was collected and purified on a silica gel column with petroleum ether (PE) as the eluent. The purified product was a white powder with a yield of 88%.

[0099]

[0100] (2) 3.50 g (6.72 mmol) of the product from the first step was weighed into a 250 mL three-necked round-bottom flask, 100 mL of tert-butylbenzene solution was added, and then nitrogen was pumped out. The three-necked flask was then placed in a low-temperature reaction bath (-40°C), the air in the needle was pumped out, and then tert-butyllithium (19.00 mL, 25.20 mmol) was pumped out under a nitrogen atmosphere, and then slowly injected into the flask, and stirred for 2 hours. Then the temperature was raised to room temperature, and the n-pentane in the tert-butyllithium solvent was pumped out again. Then 2.40 mL (25.20 mmol) of boron tribromide was slowly added at -40°C, and stirred at room temperature for 1 hour. Then 7.00 mL (50.40 mmol) of N,N-diisopropylethylamine was injected, the temperature was raised to 140°C, the condensate water was adjusted to keep the refluxing speed appropriate, and the stirring was continued for 12 hours. After the reaction was completed, the reaction system was allowed to return to room temperature, and then ethanol was used to quench the reaction system, the tert-butylbenzene solvent was spun dry, an appropriate amount of silica gel was added, and the crude product was separated by column chromatography with petroleum ether as the eluent to obtain a yellow solid with a yield of 41%.

[0101]

[0102] (3) Weigh 4.41 g (9.79 mmol) of the product of the second step, 2.12 g (10.76 mmol) of 3,6-diaminocarbazole, 4.56 g (32.98 mmol) of potassium carbonate, place them in a 500 mL three-necked flask, keep it under nitrogen atmosphere, and add 50 mL of super dry DMF. Stir under nitrogen atmosphere, warm up to 150 °C, and react for 20 h. After stopping the reaction, cool the reaction system to room temperature naturally, separate the organic phase and the aqueous phase using dichloromethane and water, and remove the solvent using a rotary evaporator. Column chromatography of the crude product on a silica gel column using petroleum ether / ethyl acetate (15:1 by volume) gives a bright yellow solid with a yield of 77%.

[0103] The characterization results of the diamine monoboron derivative are as follows: mass spectrum: 611.23; and nuclear magnetic resonance results are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 8.18 (dd, J = 6.2, 1.1 Hz, 1H), 8.15-8.09 (m, 2H), 7.68 (dd, J = 6.3, 1.4 Hz, 1H), 7.64-7.58 (m, 2H), 7.45 (d, J = 2.0 Hz, 1H), 7.39 (ddd, J = 7.4, 6.4, 1.2 Hz, 1H), 7.33 (t, J = 6.1 Hz, 1H), 7.27 (ddd, J = 8.3, 7.2, 1.2 Hz, 1H), 6.72 (dd, J = 7.7, 2.0 Hz, 1H), 4.26 (s, 2H).

[0104] Synthesis Example 5

[0105] The diamine monoboron compound 13 according to the present application conforms to general formula A-1, and has the following structure:

[0106]

[0107] The preparation method comprises the following steps:

[0108]

[0109] (1) 10.00 g (36.64 mmol) of 3,5-dichloroiodobenzene, 9.97 g (38.48 mmol) of 4,4'-dinitrosodiphenylamine, 15.19 g (109.93 mmol) of potassium carbonate, 0.70 g (3.66 mmol) of cuprous iodide, and 0.84 g (7.33 mmol) of L-proline were weighed into a 500 mL three-necked flask, and 80 mL of super dry DMF was added. The reaction system was stirred at room temperature under nitrogen, and refluxed at 150°C for 24 hours. After the reaction was stopped, the reaction system was naturally cooled to room temperature, and the organic phase and the aqueous phase were separated by extraction with dichloromethane and saturated brine, and the solvent was removed by rotary evaporation. The crude product was column chromatographed on a silica gel column with petroleum ether / dichloromethane (15:1 by volume) to obtain a yellow powder 12.04 g.

[0110]

[0111] (2) 10.00 g (23.75 mmol) of bis(4-iodophenyl)amine, 6.08 g (49.88 mmol) of phenylboronic acid, 19.69 g (142.50 mmol) of potassium carbonate, and 1.65 g (1.43 mmol) of tetrakis(triphenylphosphine)palladium were weighed into a 500 mL three-necked flask, and 60 mL of toluene, 20 mL of ethanol, and 20 mL of water were added. The reaction system was stirred at room temperature under nitrogen, and refluxed at 110°C for 24 hours. After the reaction was stopped, the reaction system was naturally cooled to room temperature, and the organic phase and the aqueous phase were separated by extraction with dichloromethane and saturated brine, and the solvent was removed by rotary evaporation. The crude product was column chromatographed on a silica gel column with petroleum ether / dichloromethane (15:1 by volume) to obtain a white powder.

[0112]

[0113] (3) 10.00 g (24.74 mmol) of the product of the first step, 16.70 g (51.95 mmol) of the product of the second step, 1.13 g (1.24 mmol) of tris(dibenzylideneacetone)dipalladium, 0.72 g (2.47 mmol) of tri-tert-butylphosphine tetrafluoroborate, and 14.27 g (148.44 mmol) of sodium tert-butoxide were weighed into a 500 mL three-necked flask, and 60 mL of dry toluene was added. Then, nitrogen was introduced and purged for 15 minutes, and the reaction was stirred at 120°C under reflux for 20 hours. After the reaction was completed, it was cooled to room temperature, and the organic layer was collected by extraction with dichloromethane and saturated brine, dried, and concentrated. The crude product was column chromatographed on a silica gel column with petroleum ether / dichloromethane (15:1 by volume) to obtain a yellow powder.

[0114]

[0115] (4) Under nitrogen protection, 10 g (10.27 mmol) of the product of the third step above and o-dichlorobenzene (80 mL) were sequentially added into a 500 mL three-necked round-bottom flask and stirred uniformly. Subsequently, 7.97 mL (82.72 mmol) of boron tribromide was added into the mixture, after the dropwise addition was completed, the temperature was raised to 180°C. After stirring at 180°C for 24 hours, the reaction was cooled to room temperature, 26.82 mL (154.05 mmol) of N,N-diisopropylethylamine was added at 0°C, after stirring for half an hour, the pH was adjusted to neutral by adding an aqueous sodium acetate solution, the organic layer was extracted by dichloromethane, dried by magnesium sulfate, concentrated under vacuum, and then the o-dichlorobenzene solvent was removed by distillation under reduced pressure at 100°C, and column chromatography was performed to obtain 6.27 g of bright yellow powder.

[0116]

[0117] (5) 10.14 g (10.33 mmol) of the product of the fourth step above and 1.40 g of palladium-carbon were weighed into a 500 mL three-necked flask, kept under a nitrogen atmosphere, and 50 mL of super-dry THF was added, stirred under a nitrogen atmosphere, and the temperature was raised to 68°C, after which 4.4 mL of hydrazine hydrate was slowly added dropwise into the reaction system, and after the dropwise addition was completed, the reaction was carried out for 12 hours. After the reaction was stopped, the reaction system was naturally cooled to room temperature, and the palladium-carbon was removed by filtration, and then the solvent was removed by rotary evaporation. The crude product was subjected to column chromatography on a silica gel column using petroleum ether / ethyl acetate (8:1 by volume). After drying, a bright yellow solid was obtained, and the yield was 67%.

[0118] The characterization results of the diamine monoboron derivative are as follows: the mass spectrum is 921.40; and the nuclear magnetic resonance results are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.67-7.52 (m, 8H), 7.44 (ddt, J = 7.7, 6.2, 1.3 Hz, 4H), 7.44-7.36 (m, 2H), 7.17-7.07 (m, 5H), 6.66-6.59 (m, 2H), 6.57-6.51 (m, 1H), 4.00 (d, J = 5.7 Hz, 1H), 3.94 (d, J = 5.7 Hz, 1H).

[0119] Synthesis Example 6

[0120] The diamine monoboron compound 49 according to the present application conforms to the general formula A-1, and the structure is as follows:

[0121]

[0122] The preparation method comprises the following steps:

[0123]

[0124] (1) 10.00 g (36.64 mmol) of 3,5-dichloroiodobenzene, 9.97 g (38.48 mmol) of 4,4'-dinitrosodiphenylamine, 15.19 g (109.93 mmol) of potassium carbonate, 0.70 g (3.66 mmol) of cuprous iodide, and 0.84 g (7.33 mmol) of L-proline were weighed into a 500 mL three-necked flask, and 80 mL of super dry DMF was added. The reaction system was stirred at room temperature under nitrogen, and refluxed at 150°C for 24 hours. After the reaction was stopped, the reaction system was naturally cooled to room temperature, and the organic phase and the aqueous phase were separated by extraction with dichloromethane and saturated brine, and the solvent was removed by rotary evaporation. The crude product was column chromatographed on a silica gel column with petroleum ether / dichloromethane (15:1 by volume), and dried to obtain 12.04 g of a yellow powder.

[0125]

[0126] (2) 10.00 g (82.52 mmol) of 2,6-dimethylaniline, 12.96 g (82.52 mmol) of bromobenzene, 3.78 g (4.13 mmol) of tris(dibenzylideneacetone)dipalladium, 2.40 g (8.26 mmol) of tri-tert-butylphosphonium tetrafluoroborate, and 23.79 g (247.56 mmol) of sodium tert-butoxide were weighed into a 500 mL three-necked flask, and 60 mL of dry toluene was added. Then, nitrogen was introduced and purged for 15 minutes, and the reaction was stirred at 120°C under reflux for 22 hours. After the reaction was completed, it was cooled to room temperature, and the organic layer was collected by extraction with dichloromethane and saturated brine, dried, and concentrated. The crude product was column chromatographed on a silica gel column with petroleum ether / dichloromethane (20:1 by volume), and dried to obtain 18.75 g of a white powder.

[0127]

[0128] (3) 10.00 g (24.74 mmol) of the product of the first step, 10.25 g (51.95 mmol) of the product of the second step, 1.13 g (1.24 mmol) of tris(dibenzylideneacetone)dipalladium, 0.72 g (2.47 mmol) of tri-tert-butylphosphonium tetrafluoroborate, and 14.27 g (148.44 mmol) of sodium tert-butoxide were weighed into a 500 mL three-necked flask, and 60 mL of dry toluene was added. Then, nitrogen was introduced and purged for 15 minutes, and the reaction was stirred at 120°C under reflux for 20 hours. After the reaction was completed, it was cooled to room temperature, and the organic layer was collected by extraction with dichloromethane and saturated brine, dried, and concentrated. The crude product was column chromatographed on a silica gel column with petroleum ether / dichloromethane (15:1 by volume), and dried to obtain a yellow powder.

[0129]

[0130] (4) Under nitrogen protection, 7.45 g (10.27 mmol) of the product of the third step above and o-dichlorobenzene (80 mL) were sequentially added into a 500 mL three-necked round bottom flask and stirred uniformly. Subsequently, 7.97 mL (82.72 mmol) of boron tribromide was added into the mixture, and after the dropwise addition was completed, the temperature was raised to 180°C. After stirring at 180°C for 24 hours, the reaction was cooled to room temperature, 26.82 mL (154.05 mmol) of N,N-diisopropylethylamine was added at 0°C, and after stirring for half an hour, the pH was adjusted to neutral with an aqueous sodium acetate solution, the organic layer was extracted with dichloromethane, dried with magnesium sulfate, concentrated under vacuum, and the o-dichlorobenzene solvent was removed by distillation under reduced pressure at 100°C, and column chromatography was performed to obtain a bright yellow powder.

[0131]

[0132] (5) 7.56 g (10.33 mmol) of the product of the fourth step above and 1.40 g of palladium-carbon were weighed into a 500 mL three-necked flask, maintained under a nitrogen atmosphere, and 50 mL of super-dry THF was added, stirred under a nitrogen atmosphere, and the temperature was raised to 68°C, after which 4.4 mL of hydrazine hydrate was slowly added dropwise to the reaction system, and after the dropwise addition was completed, the reaction was continued for 12 hours. After the reaction was stopped, the reaction system was naturally cooled to room temperature, filtered to remove the palladium-carbon, and the solvent was removed using a rotary evaporator. The crude product was column chromatographed on a silica gel column using petroleum ether / ethyl acetate (8:1 by volume). The dried product was a bright yellow solid, and the yield was 71%.

[0133] The characterization results of the diamine monoboron derivative are as follows: mass spectrum: 673.34; and nuclear magnetic resonance results are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.38 (dd, J = 7.3, 1.4 Hz, 1H), 7.26 (td, J = 7.0, 1.4 Hz, 1H), 7.13 (dd, J = 6.8, 1.5 Hz, 1H), 7.14-7.07 (m, 5H), 7.05 (td, J = 7.3, 1.5 Hz, 1H), 6.71-6.65 (m, 1H), 6.65-6.59 (m, 2H), 4.00 (d, J = 5.7 Hz, 1H), 3.94 (d, J = 5.7 Hz, 1H).

[0134] Similarly, the remaining diamine monoboron compounds can be synthesized in a similar manner.

[0135] The diamine monoboron compound above can be applied in an organic electroluminescent device, for example, the diamine monoboron compound can be used as a light-emitting guest material of a light-emitting layer in an organic electroluminescent device. Figure 1An example electroluminescent device structure. The corresponding organic electroluminescent device comprises a cathode and between the cathode a transport layer, an emitting layer and an injection layer, wherein the emitting layer comprises the diamine monoboron compound of the present application.

[0136] The diamine monoboron compound of the present application can be used as a guest emitting material in an OLED electroluminescent device. For example, using an ITO substrate, the device preparation process can include, for example, substrate pretreatment, ITO (indium tin oxide) glass substrate is sequentially cleaned in ITO cleaning agent, isopropanol, acetone, ethanol, deionized water for 30 minutes, dried with nitrogen blowing, and then baked at 120°C for 2 hours. Before preparing the device, the ITO glass substrate is treated by oxygen plasma for 5 minutes, then transferred to an organic vacuum chamber to evaporate the organic functional layer material, and after completion, transferred to a metal vacuum chamber to evaporate the metal electrode. In the specific preparation process, the best host material, exciton blocking layer material or injection and transport layer material can be selected according to the properties of the diamine monoboron compound itself, such as the emission peak position, the lowest singlet and triplet state energy level value; in addition, the film thickness of each functional layer and the concentration of the host-guest doping are also optimized.

[0137] The following are device examples (each organic functional layer is optimized):

[0138] Device comparative example 1:

[0139] ITO / MoO3(10nm) / TAPC(60nm) / mCP(10nm) / PPF:Dopant(9wt%,20nm) / PPF(10nm) / TmPyPB(30nm) / LiF(1nm) / Al(100nm)。

[0140] The guest emitting material (Dopant) in the emitting layer is the conventional MR-TADF monoboron compound PAB, the electroluminescent peak wavelength of the device is 452 nm, the half peak width (FWHM) is 28 nm, the maximum external quantum efficiency (EQEmax) is 21.6%, the driving voltage is 4.0V, and the device lifetime LT95 is 75 hours @ initial brightness 2000cd / m 2 .

[0141] Device example 1:

[0142] ITO / MoO3(10nm) / TAPC(60nm) / mCP(10nm) / PPF:Dopant(9wt%,20nm) / PPF(10nm) / TmPyPB(30nm) / LiF(1nm) / Al(100nm)。

[0143] The light-emitting layer dopant is the diamine monoboron compound 1 described in the present application, the electroluminescent peak wavelength of the device is 417 nm, the full width at half maximum (FWHM) is 27 nm, the maximum external quantum efficiency (EQEmax) is 32.9%, the driving voltage is 3.4 V, and the device lifetime LT95 is 90 hours @ initial brightness 2000 cd / m 2 .

[0144] Device Example 2:

[0145] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(9 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0146] The light-emitting layer dopant is the diamine monoboron compound 2 described in the present application, the electroluminescent peak wavelength of the device is 425 nm, the full width at half maximum (FWHM) is 24 nm, the maximum external quantum efficiency (EQEmax) is 30.7%, the driving voltage is 3.4 V, and the device lifetime LT95 is 95 hours @ initial brightness 2000 cd / m 2 .

[0147] Device Example 3:

[0148] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(6 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0149] The light-emitting layer dopant is the diamine monoboron compound 3 described in the present application, the electroluminescent peak wavelength of the device is 420 nm, the full width at half maximum (FWHM) is 25 nm, the maximum external quantum efficiency (EQEmax) is 33.4%, the driving voltage is 3.5 V, and the device lifetime LT95 is 92 hours @ initial brightness 2000 cd / m 2 .

[0150] Device Example 4:

[0151] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(6 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0152] The light-emitting layer dopant is the diamine monoboron compound 4 described in the present application, the electroluminescent peak wavelength of the device is 426 nm, the full width at half maximum (FWHM) is 26 nm, the maximum external quantum efficiency (EQEmax) is 34.1%, the driving voltage is 3.5 V, and the device lifetime LT95 is 100 hours @ initial brightness 2000 cd / m 2 .

[0153] Device embodiment 5:

[0154] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(9 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0155] The light-emitting layer dopant is the diamine monoboron compound 5 described in the present application, the electroluminescent peak wavelength of the device is 429 nm, the full width at half maximum (FWHM) is 26 nm, the maximum external quantum efficiency (EQEmax) is 32.9%, the driving voltage is 3.4 V, and the device lifetime LT95 is 98 hours @ initial brightness 2000 cd / m 2 .

[0156] Device embodiment 6:

[0157] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(9 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0158] The light-emitting layer dopant is the diamine monoboron compound 6 described in the present application, the electroluminescent peak wavelength of the device is 429 nm, the full width at half maximum (FWHM) is 26 nm, the maximum external quantum efficiency (EQEmax) is 35.1%, the driving voltage is 3.4 V, and the device lifetime LT95 is 100 hours @ initial brightness 2000 cd / m 2 .

[0159] Device embodiment 7:

[0160] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(9 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0161] The light-emitting layer dopant is the diamine monoboron compound 7 described in the present application, the electroluminescent peak wavelength of the device is 429 nm, the full width at half maximum (FWHM) is 28 nm, the maximum external quantum efficiency (EQEmax) is 34.3%, the driving voltage is 3.4 V, and the device lifetime LT95 is 89 hours @ initial brightness 2000 cd / m 2 .

[0162] Device Example 8:

[0163] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(9 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0164] The light-emitting layer dopant is the diamine monoboron compound 8 described in the present application, the electroluminescent peak wavelength of the device is 430 nm, the full width at half maximum (FWHM) is 28 nm, the maximum external quantum efficiency (EQEmax) is 30.1%, the driving voltage is 3.4 V, and the device lifetime LT95 is 92 hours @ initial brightness 2000 cd / m 2 .

[0165] Device Example 9:

[0166] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(9 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0167] The light-emitting layer dopant is the diamine monoboron compound 9 described in the present application, the electroluminescent peak wavelength of the device is 422 nm, the full width at half maximum (FWHM) is 25 nm, the maximum external quantum efficiency (EQEmax) is 34.6%, the driving voltage is 3.3 V, and the device lifetime LT95 is 88 hours @ initial brightness 2000 cd / m 2 .

[0168] Device Example 10:

[0169] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(9 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0170] The light-emitting layer dopant is the diamine monoboron compound 10 described in the present application, the electroluminescent peak wavelength of the device is 429 nm, the full width at half maximum (FWHM) is 27 nm, the maximum external quantum efficiency (EQEmax) is 31.8%, the driving voltage is 3.5 V, and the device lifetime LT95 is 91 hours @ initial brightness 2000 cd / m 2 .

[0171] Device Example 11:

[0172] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(3 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0173] The light-emitting layer dopant is the diamine monoboron compound 11 described in the present application, the electroluminescent peak wavelength of the device is 414 nm, the full width at half maximum (FWHM) is 23 nm, the maximum external quantum efficiency (EQEmax) is 30.9%, the driving voltage is 3.4 V, and the device lifetime LT95 is 80 hours @ initial brightness 2000 cd / m 2 .

[0174] Device Example 12:

[0175] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(3 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0176] The light-emitting layer dopant is the diamine monoboron compound 12 described in the present application, the electroluminescent peak wavelength of the device is 420 nm, the full width at half maximum (FWHM) is 23 nm, the maximum external quantum efficiency (EQEmax) is 32.0%, the driving voltage is 3.4 V, and the device lifetime LT95 is 85 hours @ initial brightness 2000 cd / m 2 .

[0177] Device Example 13:

[0178] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(3 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0179] The light-emitting layer dopant is the diamine monoboron compound 13 described in the present application, the electroluminescent peak wavelength of the device is 410 nm, the full width at half maximum (FWHM) is 26 nm, the maximum external quantum efficiency (EQEmax) is 30.1%, the driving voltage is 3.6 V, and the device lifetime LT95 is 80 hours @ initial brightness 2000 cd / m 2 .

[0180] Device Example 14:

[0181] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(3 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0182] The light-emitting layer dopant is the diamine monoboron compound 14 described in the present application, the electroluminescent peak wavelength of the device is 416 nm, the full width at half maximum (FWHM) is 28 nm, the maximum external quantum efficiency (EQEmax) is 32.4%, the driving voltage is 3.7 V, and the device lifetime LT95 is 78 hours @ initial brightness 2000 cd / m 2 .

[0183] Device Example 15:

[0184] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(6 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0185] The light-emitting layer dopant is the diamine monoboron compound 15 described in the present application, the electroluminescent peak wavelength of the device is 414 nm, the full width at half maximum (FWHM) is 26 nm, the maximum external quantum efficiency (EQEmax) is 32.3%, the driving voltage is 3.6 V, and the device lifetime LT95 is 88 hours @ initial brightness 2000 cd / m 2 .

[0186] Device Example 16:

[0187] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(6 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0188] The light-emitting layer dopant is the diamine monoboron compound 16 described in the present application, the electroluminescent peak wavelength of the device is 419 nm, the full width at half maximum (FWHM) is 29 nm, the maximum external quantum efficiency (EQEmax) is 33.0%, the driving voltage is 3.5 V, and the device lifetime LT95 is 90 hours @ initial brightness 2000 cd / m 2 .

[0189] Device Example 17:

[0190] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(3 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0191] The light-emitting layer dopant is the diamine monoboron compound 17 described in the present application, the electroluminescent peak wavelength of the device is 410 nm, the full width at half maximum (FWHM) is 29 nm, the maximum external quantum efficiency (EQEmax) is 30.7%, the driving voltage is 3.7 V, and the device lifetime LT95 is 85 hours @ initial brightness 2000 cd / m 2 .

[0192] Device Example 18:

[0193] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(3 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0194] The light-emitting layer dopant is the diamine monoboron compound 18 described in the present application, the electroluminescent peak wavelength of the device is 416 nm, the full width at half maximum (FWHM) is 29 nm, the maximum external quantum efficiency (EQEmax) is 31.1%, the driving voltage is 3.6 V, and the device lifetime LT95 is 90 hours @ initial brightness 2000 cd / m 2 .

[0195] Device Example 19:

[0196] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(9 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0197] The light-emitting layer dopant is the diamine monoboron compound 19 described in the application, the electroluminescent peak wavelength of the device is 410 nm, the full width at half maximum (FWHM) is 24 nm, the maximum external quantum efficiency (EQEmax) is 32.0%, the driving voltage is 3.5 V, and the device lifetime LT95 is 94 hours @ initial brightness 2000 cd / m 2 .

[0198] Device Example 20:

[0199] ITO / MoO3(10 nm) / TAPC(60 nm) / mCP(10 nm) / PPF:Dopant(9 wt%, 20 nm) / PPF(10 nm) / TmPyPB(30 nm) / LiF(1 nm) / Al(100 nm).

[0200] The light-emitting layer dopant is the diamine monoboron compound 20 described in the application, the electroluminescent peak wavelength of the device is 415 nm, the full width at half maximum (FWHM) is 26 nm, the maximum external quantum efficiency (EQEmax) is 33.9%, the driving voltage is 3.4 V, and the device lifetime LT95 is 100 hours @ initial brightness 2000 cd / m 2 .

[0201] The above examples demonstrate that the diamine monoboron compound based on the application has blue-violet light emission (410 nm-430 nm) and extremely narrow full width at half maximum (<30 nm), which can effectively improve the color purity of the device. In addition, due to the introduction of strong donor amino groups, LRCT / SRCT interaction is generated, and the OLED device prepared based on the diamine monoboron derivative can obtain higher device efficiency (EQE>30%) and lower driving voltage.

[0202] Figure 1 Figure 2 is the external quantum efficiency-current density relationship characteristic curve of device examples 1 to 5. From the device external quantum efficiency curve, it can be concluded that the light-emitting efficiency of the material is at a high level, which meets the requirements of industrial application of organic electroluminescent materials. Figure 3 is a driving voltage comparison chart of device examples 1 to 5 and device comparative example 1, which shows that the OLED device prepared from the diamine monoboron compound described in the application has a lower driving voltage than the conventional MR-TADF material, which meets the requirements of industrial application of organic electroluminescent materials.

[0203] In accordance with yet another aspect of the present application, the polyimide polymers derived from the diamine-based monoboron compounds described herein can be used as flexible substrates in OLED electroluminescent devices. A specific polyimide film preparation process can include, for example: (1) adding one or more diamines to a polar aprotic organic solvent under nitrogen atmosphere protection at 0-20 °C, followed by adding one or more dianhydrides twice with an interval of 10-30 minutes and controlling the molar ratio of diamine to dianhydride to be 0.95-1.05, and continuously stirring for 5-24 hours to obtain a polyamic acid (PAA) solution; (2) uniformly coating the polyamic acid solution on a substrate, removing part of the solvent in the polyamic acid solution by soft baking at 80-100 °C, and allowing the polyamic acid solution to undergo thermal imidization, mainly using a stepwise heating method, and then cooling to room temperature to obtain a polyimide film.

[0204] The following are film examples:

[0205] Film Comparative Example 1:

[0206] (1) 10 mmol of 4,4'-diaminodiphenyl ether (ODA) was dissolved in super dry N,N-dimethylacetamide (DMAc) in a flask under a nitrogen atmosphere at room temperature, and then 10 mmol of pyromellitic dianhydride (PMDA) was added twice and stirred for 24 hours to obtain a PAA-0 solution.

[0207] (2) Then, the polyamic acid solution was uniformly spread on a clean substrate by spin coating at a speed of 1200 revolutions / s for 40 seconds, and part of the organic solvent was removed by soft baking at 90 °C for 15 minutes.

[0208] (3) Finally, thermal imidization was carried out under a nitrogen atmosphere, mainly using a stepwise heating method, with a heating program of 100 °C / 1 hour, 200 °C / 1 hour, 300 °C / 1 hour, 350 °C / 1 hour, a heating rate of 5 °C / minute, and then cooling to room temperature to obtain a polyimide substrate PI-0. The Young's modulus of the polyimide PI-0 was 3.20 Gpa, the dielectric constant at 10 GHz was 3.2, the dielectric loss at 10 GHz was 15 ‰, and the 450 nm transmittance was 50%.

[0209] Film Example 1, in accordance with general formula B-1:

[0210] The preparation method of this embodiment 1 is different from comparative example 1 in that the diamine of step (1) is replaced by the diamine single boron compound 1 according to the application, the dianhydride is replaced by 4,4'-oxydiphthalic anhydride (ODPA), and PAA-1 solution is obtained by direct polymerization, and then polyimide PI-1 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-1 is 3.10 Gpa, the dielectric constant at 10 GHz is 3.15, the dielectric loss at 10 GHz is 10.1 ‰, and the 450 nm transmittance is 88%.

[0211] Film embodiment 2, according to general formula B-1:

[0212] The preparation method of this embodiment is different from film embodiment 1 in that the diamine of step (1) is replaced by a mixed diamine of diamine single boron compound 1 and 4,4'-diamino diphenyl ether (ODA) with a mixing molar ratio of 1:9, and PAA-2 is obtained by polymerization, and then polyimide PI-2 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-2 is 3.03 Gpa, the dielectric constant at 10 GHz is 3.10, the dielectric loss at 10 GHz is 9.9 ‰, and the 450 nm transmittance is 88%.

[0213] Film embodiment 3, according to general formula B-1:

[0214] The preparation method of this embodiment is different from film embodiment 1 in that the diamine of step (1) is replaced by a mixed diamine of diamine single boron compound 1 and 4,4'-diamino diphenyl ether (ODA) with a mixing molar ratio of 2:8, and PAA-3 is obtained by polymerization, and then polyimide PI-3 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-3 is 3.11 Gpa, the dielectric constant at 10 GHz is 3.10, the dielectric loss at 10 GHz is 8.0 ‰, and the 450 nm transmittance is 87%.

[0215] Film embodiment 4, according to general formula B-1:

[0216] The preparation method of this embodiment is different from film embodiment 1 in that the dianhydride of step (1) is replaced by 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and PAA-13 is obtained by direct polymerization, and then polyimide PI-13 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-13 is 3.19 Gpa, the dielectric constant at 10 GHz is 2.99, the dielectric loss at 10 GHz is 6.0 ‰, and the 450 nm transmittance is 93%.

[0217] Film embodiment 5, according to general formula B-1:

[0218] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the dianhydride of step (1) is replaced by 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), direct polymerization to obtain PAA-14, and then curing at 350°C to obtain polyimide PI-14. The Young's modulus of the polyimide PI-14 is 3.25 Gpa, the dielectric constant at 10 GHz is 3.00, the dielectric loss at 10 GHz is 7.1 ‰, and the 450 nm transmittance is 90%.

[0219] Thin film embodiment 6, according to general formula B-1:

[0220] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the dianhydride of step (1) is replaced by 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), direct polymerization to obtain PAA-14, and then curing at 350°C to obtain polyimide PI-14. The Young's modulus of the polyimide PI-14 is 3.25 Gpa, the dielectric constant at 10 GHz is 3.00, the dielectric loss at 10 GHz is 7.1 ‰, and the 450 nm transmittance is 90%.

[0221] Thin film embodiment 7, according to general formula B-1:

[0222] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the dianhydride of step (1) is replaced by 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), direct polymerization to obtain PAA-14, and then curing at 350°C to obtain polyimide PI-14. The Young's modulus of the polyimide PI-14 is 3.25 Gpa, the dielectric constant at 10 GHz is 3.00, the dielectric loss at 10 GHz is 7.1 ‰, and the 450 nm transmittance is 90%.

[0223] Thin film embodiment 8, according to general formula B-1:

[0224] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the dianhydride of step (1) is replaced by 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), direct polymerization to obtain PAA-14, and then curing at 350°C to obtain polyimide PI-14. The Young's modulus of the polyimide PI-14 is 3.25 Gpa, the dielectric constant at 10 GHz is 3.00, the dielectric loss at 10 GHz is 7.1 ‰, and the 450 nm transmittance is 90%.

[0225] Thin film embodiment 9, according to general formula B-2:

[0226] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the diamine of step (1) is replaced by diamine type monoboron compound 2, and PAA-4 is polymerized, and then polyimide PI-4 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-4 is 3.20 Gpa, the dielectric constant at 10 GHz is 3.05, the dielectric loss at 10 GHz is 8.2 ‰, and the 450 nm transmittance is 89%.

[0227] Thin film embodiment 10, according to general formula B-2:

[0228] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the diamine of step (1) is replaced by a mixed diamine of diamine type monoboron compound 2 and 4,4'-diamino diphenyl ether (ODA) with a mixing molar ratio of 1:9, and PAA-5 is polymerized, and then polyimide PI-5 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-5 is 3.17 Gpa, the dielectric constant at 10 GHz is 3.01, the dielectric loss at 10 GHz is 6.7 ‰, and the 450 nm transmittance is 95%.

[0229] Thin film embodiment 11, according to general formula B-2:

[0230] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the diamine of step (1) is replaced by a mixed diamine of diamine type monoboron compound 2 and 4,4'-diamino diphenyl ether (ODA) with a mixing molar ratio of 2:8, and PAA-6 is polymerized, and then polyimide PI-6 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-6 is 3.11 Gpa, the dielectric constant at 10 GHz is 3.11, the dielectric loss at 10 GHz is 7.8 ‰, and the 450 nm transmittance is 91%.

[0231] Thin film embodiment 12, according to general formula B-3:

[0232] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the diamine of step (1) is replaced by diamine type monoboron compound 3, and PAA-7 is polymerized, and then polyimide PI-7 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-7 is 3.20 Gpa, the dielectric constant at 10 GHz is 3.08, the dielectric loss at 10 GHz is 6.9 ‰, and the 450 nm transmittance is 93%.

[0233] Thin film embodiment 13, according to general formula B-3:

[0234] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the diamine of step (1) is replaced by a mixed diamine of diamine type monoboron compound 3 and 4,4'-diamino diphenyl ether (ODA) with a mixing molar ratio of 1:9, and PAA-8 is polymerized, and then polyimide PI-8 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-8 is 3.09 Gpa, the dielectric constant at 10 GHz is 3.00, the dielectric loss at 10 GHz is 6.1 ‰, and the 450 nm transmittance is 95%.

[0235] Thin film embodiment 14, according to general formula B-3:

[0236] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the diamine of step (1) is replaced by a mixed diamine of diamine type monoboron compound 3 and 4,4'-diamino diphenyl ether (ODA) with a mixing molar ratio of 2:8, and PAA-9 is polymerized, and then polyimide PI-9 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-9 is 3.00 Gpa, the dielectric constant at 10 GHz is 2.99, the dielectric loss at 10 GHz is 5.8 ‰, and the 450 nm transmittance is 96%.

[0237] Thin film embodiment 15, according to general formula B-4:

[0238] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the diamine of step (1) is replaced by diamine type monoboron compound 4, and PAA-10 is polymerized, and then polyimide PI-10 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-10 is 3.06 Gpa, the dielectric constant at 10 GHz is 3.04, the dielectric loss at 10 GHz is 7.0 ‰, and the 450 nm transmittance is 90%.

[0239] Thin film embodiment 16, according to general formula B-4:

[0240] The preparation method of this embodiment is different from that of thin film embodiment 1 in that the diamine of step (1) is replaced by a mixed diamine of diamine type monoboron compound 4 and 4,4'-diamino diphenyl ether (ODA) with a mixing molar ratio of 1:9, and PAA-11 is polymerized, and then polyimide PI-11 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-11 is 3.23 Gpa, the dielectric constant at 10 GHz is 3.11, the dielectric loss at 10 GHz is 9.2 ‰, and the 450 nm transmittance is 87%.

[0241] Thin film embodiment 17, according to general formula B-4:

[0242] The preparation method of the embodiment is different from that of the thin film embodiment 1 in that the diamine of step (1) is replaced by a mixed diamine of diamine type monoboron compound 4 and 4,4'-diamino diphenyl ether (ODA) with a mixing molar ratio of 2:8, and PAA-12 is polymerized, and then polyimide PI-12 is obtained by curing at 350°C. The Young's modulus of the polyimide PI-12 is 3.33 Gpa, the dielectric constant at 10 GHz is 3.02, the dielectric loss at 10 GHz is 7.4‰, and the 450 nm transmittance is 90%.

[0243] The above embodiments demonstrate that the polyimide polymers derived from the diamine type monoboron compound according to the present application have excellent dielectric properties and optical properties. Figure 4 The dielectric property comparison chart of thin film embodiments 1, 9, 12, 15 and thin film comparative example 1. From the data in the chart, it can be concluded that the polyimide thin film according to the present application has more excellent dielectric properties, meeting the requirements of the industrialization application of flexible OLED display substrates. The diamine type monoboron compound obtained by the present application has a wide application scenario and application potential.

[0244] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A diaminoborane compound characterized by, The diamine monoboron compound has a general structure as shown in at least one of general formula A-1 to general formula A-4, wherein R1, R2 are independently selected from hydrogen, deuterium, methyl, phenyl, methoxy, trifluoromethyl, tert-butyl, halogen, pyrazinyl, pyridyl, pyrimidinyl.

2. The diamine monoboron compound according to claim 1, wherein, The structure of the diamine monoboron compound is shown in any one of formula 1 to formula 144: 。 3. A polyimide polymer derived from the diamine-based monoboronic compound according to claim 1 or 2, characterized in that, The polyimide polymer has a general structure as shown in at least one of general formula B-1 to general formula B-4: wherein Ar is a tetravalent aromatic group; n is a natural number from 1 to 1000; General formula B-1 is constructed from the diamine monoboron compound satisfying general formula A-1; General formula B-2 is constructed from the diamine monoboron compound satisfying general formula A-2; General formula B-3 is constructed from the diamine monoboron compound satisfying general formula A-3; General formula B-4 is constructed from the diamine monoboron compound satisfying general formula A-4; Ar is selected from: 。 4. Use of the diamine monoboron compound according to claim 1 or 2 and / or the polyimide polymer according to claim 3 in an organic electroluminescence device, characterized in that, The diamine monoboron compound is particularly applied in the light-emitting layer of the organic electroluminescent device as a guest light-emitting material; The polyimide polymer is particularly applied in the flexible substrate of the organic electroluminescent device as a thin film material.

5. The use according to claim 4, wherein the compound is ###0002### The organic electroluminescent device comprises, in sequence, an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode.

6. The use according to claim 5, wherein the compound is ###0002### An electron blocking layer or an exciton blocking layer is further provided between the hole transport layer and the light-emitting layer; a hole blocking layer or an exciton blocking layer is further provided between the light-emitting layer and the electron transport layer.

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