Narrow-band blue light molecule and preparation method and application thereof

Abstract

The application discloses a narrow-band blue light molecule and a preparation method and application thereof. The application introduces two donor units into a fluorene skeleton, forms a dislocation structure with a multiple resonance unit in space, and regulates the strength of the space charge transfer. On one hand, the reverse intersystem crossing rate can be improved to improve the performance and efficiency of a device. On the other hand, the high-efficiency light emission of the narrow-band is maintained. The application further discloses a preparation method and application of the material. The narrow-band blue light molecule can be used as a novel light-emitting molecule with high performance, high color purity and high quantum efficiency. The narrow-band blue light molecule has great application potential in the preparation of light-emitting materials, light-emitting devices and electronic technology, and has a bright prospect in the field of display technology and solid-state lighting.

Description

Technical Field

[0001] This application relates to the field of organic light-emitting materials technology, and more specifically, to a method for preparing and applying a narrow-band blue light molecule. Background Technology

[0002] In past reports, DA-type TSCT-TADF molecules (thermally activated delayed fluorescent molecules via space charge transfer) with narrow emission spectra (half-width at half maximum of about 50 nm) generally use polycyclic aromatic hydrocarbon compounds fused with boron and oxygen atoms as acceptor units. However, the boron-oxygen unit has weak multiple resonance characteristics. When used as an acceptor in TSCT-TADF molecules, it interacts with the donor unit to produce emission dominated by long-range charge transfer. Its multiple resonance characteristics are easily destroyed, making it difficult to maintain its narrow-band emission characteristics.

[0003] However, due to the high structural rigidity of the boron-oxygen unit, it can effectively suppress structural relaxation of the excited state and, to some extent, suppress the broadening of the emission half-width at half-maximum. Existing common MR-TADF materials (multiple resonance thermally activated delayed fluorescence materials) suffer from large ΔE due to excessive overlap of HOMO and LUMO. ST This also slows down the reverse intersystem crossing process.

[0004] Application content

[0005] To overcome one of the problems existing in the prior art, the primary objective of this application is to provide a narrow-band blue light molecule that modulates the space charge transfer intensity by introducing two donor units into the fluorene framework to form a misaligned structure with multiple resonance units in space, thus having the advantages of high luminous efficiency, narrow band and high color purity.

[0006] Another objective of this application is to provide a method for preparing the aforementioned narrow-band blue light-emitting molecules.

[0007] Another objective of this application is to provide applications for the aforementioned narrow-band blue light molecules.

[0008] The above-mentioned objectives of this application are achieved through the following technical solutions:

[0009] A narrow-band blue light molecule, which can be used in organic small molecule optoelectronic functional materials, has the molecular structure shown in formula (Ⅰ):

[0010]

[0011] Where D is an electron-donating group.

[0012] Preferably, in the narrow-band blue light molecule of this application, D is selected from one of the following structural formulas:

[0013]

[0014] This application also provides a method for preparing the above-mentioned narrow-band blue light molecule, comprising the following steps:

[0015] S1 Preparation of Intermediate 1:

[0016] 2,6-Difluoro-4-bromoiodobenzene, 3,6-di-tert-butylcarbazole and cesium carbonate were added sequentially to a reaction flask. After the nitrogen gas was replaced three times, N,N-dimethylformamide was added, and the reaction was refluxed under nitrogen. After the reaction was completed, the system was allowed to return to room temperature, and then extracted and washed with dichloromethane and saturated brine. After the organic phase was recovered and the solvent was removed, ethanol was added, heated and stirred, and filtered to obtain intermediate 1, the structure of which is shown below.

[0017]

[0018] S2 preparation of intermediate 2:

[0019] Intermediate 1 obtained in step S1 was dissolved in o-xylene, and n-butyllithium was slowly added under stirring. Then, boron tribromide was added under stirring, followed by N,N-diisopropylethylamine, and stirring was continued for 5 hours. After the reaction was completed, water was added to quench the reaction. The product was extracted and washed with dichloromethane and saturated brine, the organic phase was recovered and dried with anhydrous magnesium sulfate, the solvent was removed by vacuum distillation, and the crude product was then purified by column chromatography to obtain intermediate 2, the structure of which is shown below.

[0020]

[0021] S3 preparation of intermediate 3:

[0022] Intermediate 2 obtained in step S2 was dissolved in 1,4-dioxane, and pinacol diborate, 1,1-bis(diphenylphosphine)ferrocene palladium dichloride, and potassium acetate were added. After reacting under nitrogen purging for 24 hours three times, the mixture was extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried over anhydrous magnesium sulfate. The solvent was removed by vacuum distillation, and the crude product was then purified by column chromatography to generate intermediate 3, the structure of which is shown below.

[0023]

[0024] S4. Preparation of intermediate 4:

[0025] 1-Bromo-9-fluorenone and a compound containing an electron-donating group were added to a two-necked flask, carbon tetrachloride and methanesulfonic acid solvent were added, nitrogen was purged three times and the reaction was carried out for 24 hours. The mixture was extracted and washed with dichloromethane and saturated brine, the organic phase was recovered and dried with anhydrous magnesium sulfate, the solvent was removed by vacuum distillation, and the crude product was then separated and purified by column chromatography to generate intermediate 4.

[0026] S5. Preparation of narrow-band blue light molecules:

[0027] Intermediate 3, intermediate 4, and potassium carbonate were added to a two-necked flask. Tetrahydrofuran and water were added as solvents. After purging with nitrogen three times, tetra(triphenylphosphine)palladium catalyst was added and reacted for 12 hours. After removing tetrahydrofuran, the product was extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried with anhydrous magnesium sulfate. The solvent was removed by vacuum distillation. The crude product was then purified by column chromatography to obtain a narrow-band blue light molecule.

[0028] Preferably, in step S1, the molar ratio of 2,6-difluoro-4-bromoiodobenzene, 3,6-di-tert-butylcarbazole and cesium carbonate is 1:(2-3):(2-3), the reaction temperature is 110-150°C, and the reaction time is 24-36 h.

[0029] Preferably, in step S2, the molar ratio of intermediate 1, n-butyllithium (2.5M) and boron tribromide is 1:(2-3):(1-2), the reaction temperature is 0 to -20°C, and the reaction time is 1 to 2 hours.

[0030] Preferably, in step S3, the molar ratio of intermediate 2 to pinacol diborate, potassium acetate, and 1,1-bis(diphenylphosphine)ferrocene palladium dichloride is 1:2:3:0.05, the reaction temperature is 100-140°C, and the reaction time is 12-24 h.

[0031] Preferably, in step S4, the molar ratio of 1-bromo-9-fluorenone to the donor group, carbon tetrachloride, and methanesulfonic acid is 1:4, the reaction temperature is 90°C, and the reaction time is 24 h.

[0032] Preferably, in step S5, the molar ratio of intermediate 3, intermediate 4, potassium carbonate, tetrahydrofuran, water and tetra(triphenylphosphine)palladium is (1-2):1:2:0.05, the reaction temperature is 70-80°C, and the reaction time is 12 hours.

[0033] The narrow-band blue light-emitting molecules described in this application are used in luminescent materials, luminescent devices, or smart materials.

[0034] Compared with the prior art, the beneficial effects of this application are:

[0035] The narrow-band blue luminescent molecule provided in this application bridges donor units and multiple resonance units via a fluorene framework, combining two different charge transfer modes: long-range charge transfer and short-range charge transfer. While maintaining the narrow-band emission characteristic of short-range charge transfer in the multiple resonance units, the introduction of high-energy excited states with long-range charge transfer properties promotes multi-channel exciton spin-flip coupling, achieving faster reverse intersystem crossing. Simultaneously, the additional donor units provide a significant steric hindrance effect, preventing long-range π-π stacking between molecules and effectively suppressing the severe aggregation-induced luminescence quenching of MR-TADF molecules. This results in an EQE of 33.61% at a 20% doping concentration, making it a novel luminescent molecule with good performance, low cost, and high luminescence intensity. Attached Figure Description

[0036] Figure 1 The 1H NMR spectrum of compound A1 prepared in Example 1 of this application;

[0037] Figure 2 This is the mass spectrum of compound A1 prepared in Example 1 of this application;

[0038] Figure 3 The 1H NMR spectrum of compound A2 prepared in Example 2 of this application;

[0039] Figure 4 This is the mass spectrum of compound A2 prepared in Example 2 of this application;

[0040] Figure 5 The 1H NMR spectrum of compound A3 prepared in Example 3 of this application;

[0041] Figure 6 This is the mass spectrum of compound A3 prepared in Example 3 of this application;

[0042] Figure 7 The 1H NMR spectrum of compound A4 prepared in Example 4 of this application;

[0043] Figure 8 This is the mass spectrum of compound A4 prepared in Example 4 of this application;

[0044] Figure 9 Compounds A1, A2, A3, and A4 prepared for Examples 1, 2, 3, and 4 of this application were subjected to a concentration of 1.0 × 10⁻⁶. -5 Ultraviolet absorption spectrum of M in toluene solution;

[0045] Figure 10 Compounds A1, A2, A3, and A4 prepared for Examples 1, 2, 3, and 4 of this application were subjected to a concentration of 1.0 × 10⁻⁶. -5 Fluorescence emission spectrum of M in toluene solution;

[0046] Figure 11 The figures show the brightness-external quantum efficiency characteristic curves and electroluminescence spectra of the device under different doping concentrations in Example 1 of this application.

[0047] Figure 12 The three-dimensional design of the narrow-band blue light molecule provided in this application and the schematic diagram of the related principle are shown. Detailed Implementation

[0048] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0049] It should be noted that:

[0050] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0051] In this application, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0052] Unless otherwise specified, the components or preferred components involved in this application may be combined to form new technical solutions.

[0053] In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "1~5" means that all real numbers between "1~5" have been listed in this document, and "1~5" is simply a shortened representation of these numerical combinations.

[0054] The “scope” disclosed in this application may be in the form of a lower limit and an upper limit, and may be one or more lower limits and one or more upper limits, respectively.

[0055] In this application, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0056] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to a person skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this application.

[0057] This application discovers that polycyclic aromatic hydrocarbon compounds fused with boron and nitrogen atoms can serve as highly efficient narrowband OLED light-emitting materials. The multiple resonance effect of boron and nitrogen atoms disperses HOMO and LUMO in different atoms, giving the molecule TADF characteristics. Short-range charge transfer induced by the multiple resonance effect enables narrow emission and extremely high color purity. The boron-nitrogen unit not only functions as an MR-TADF molecule but can also act as an acceptor in DA-type TSCT-TADF molecules. The sufficiently strong multiple resonance effect of the boron-nitrogen unit is not disrupted by additionally introduced donors, thus maintaining its narrowband emission characteristics. Introducing donor units into MR-TADF molecules to generate long-range charge transfer can enhance the reverse intersystem crossing rate, effectively addressing the large ΔE caused by excessive HOMO and LUMO overlap in MR-TADF. ST This also slows down the reverse intersystem crossing process.

[0058] This application provides a narrow-band blue light molecule that can be used in organic small molecule optoelectronic functional materials, and it has the molecular structure shown in formula (Ⅰ):

[0059]

[0060] Where D is an electron-donating group.

[0061] The narrow-band blue luminescent molecule provided in this application bridges donor units and multiple resonance units via a fluorene framework, combining two different charge transfer mechanisms: long-range charge transfer and short-range charge transfer. While maintaining the narrow-band emission characteristic of short-range charge transfer in the multiple resonance units, the introduction of high-energy excited states with long-range charge transfer properties promotes multi-channel exciton spin-flip coupling, enabling faster reverse intersystem crossing. Simultaneously, the additional donor units provide significant steric hindrance, preventing long-range π-π stacking between molecules and effectively suppressing the severe aggregation-induced luminescence quenching of MR-TADF molecules, thus maintaining good luminescence performance even at high doping concentrations.

[0062] In some preferred embodiments, the narrow-band blue light molecule of this application, wherein D is selected from one of the following structural formulas:

[0063]

[0064] Therefore, specifically, the structural formula of the aforementioned narrow-band blue light molecule is one of the following structures:

[0065]

[0066]

[0067] Therefore, this application bridges the donor unit and the multiple resonant unit using a fluorene framework, combining two different charge transfer modes: long-range charge transfer and short-range charge transfer. While maintaining the narrow-band emission characteristic of the short-range charge transfer of the multiple resonant unit, a high-energy excited state with long-range charge transfer properties is introduced to promote multi-channel exciton spin-flip coupling, achieving faster reverse intersystem crossing and maintaining good luminescence performance.

[0068] In some preferred embodiments, the narrow-band blue light molecule in this application, wherein D is selected from one of the following structural formulas:

[0069]

[0070] More specifically, this application can construct narrow-band blue light molecules as described below:

[0071]

[0072] The narrow-band blue light molecular systems constructed in this application are diverse, and while maintaining narrow emission, they also improve the reverse intersystem crossing rate and suppress aggregation-induced luminescence quenching.

[0073] In some preferred embodiments, D is selected from one of the following structural formulas:

[0074]

[0075] For example, a narrow-band blue light molecule can be constructed as shown below:

[0076]

[0077] The narrow-band blue light molecular systems constructed in this application are diverse, and while maintaining narrow emission, they also improve the reverse intersystem crossing rate and suppress aggregation-induced luminescence quenching.

[0078] This application also provides a method for preparing the above-mentioned narrow-band blue light-emitting molecule. The method includes the following steps:

[0079] S1 Preparation of Intermediate 1:

[0080] 2,6-Difluoro-4-bromoiodobenzene, 3,6-di-tert-butylcarbazole and cesium carbonate were added sequentially to a reaction flask. After the nitrogen gas was replaced three times, N,N-dimethylformamide was added, and the reaction was refluxed under nitrogen. After the reaction was completed, the system was allowed to return to room temperature, and then extracted and washed with dichloromethane and saturated brine. After the organic phase was recovered and the solvent was removed, ethanol was added, heated and stirred, and filtered to obtain intermediate 1, the structure of which is shown below.

[0081]

[0082] S2 preparation of intermediate 2:

[0083] Intermediate 1 obtained in step S1 was dissolved in o-xylene, and n-butyllithium was slowly added under stirring. Then, boron tribromide was added under stirring, followed by N,N-diisopropylethylamine, and stirring was continued for 5 hours. After the reaction was completed, water was added to quench the reaction. The product was extracted and washed with dichloromethane and saturated brine, the organic phase was recovered and dried with anhydrous magnesium sulfate, the solvent was removed by vacuum distillation, and the crude product was then purified by column chromatography to obtain intermediate 2, the structure of which is shown below.

[0084]

[0085] S3 preparation of intermediate 3:

[0086] Intermediate 2 obtained in step S2 was dissolved in 1,4-dioxane, and pinacol diborate, 1,1-bis(diphenylphosphine)ferrocene palladium dichloride, and potassium acetate were added. After reacting under nitrogen purging for 24 hours three times, the mixture was extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried over anhydrous magnesium sulfate. The solvent was removed by vacuum distillation, and the crude product was then purified by column chromatography to generate intermediate 3, the structure of which is shown below.

[0087]

[0088] S4. Preparation of intermediate 4:

[0089] 1-Bromo-9-fluorenone and a compound containing an electron-donating group were added to a two-necked flask, along with carbon tetrachloride and methanesulfonic acid solvent. The mixture was purged with nitrogen three times and reacted for 24 hours. The product was extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried over anhydrous magnesium sulfate. The solvent was removed by vacuum distillation. The crude product was then purified by column chromatography to yield intermediate 4.

[0090] S5. Preparation of narrow-band blue light molecules:

[0091] Intermediate 3, intermediate 4, and potassium carbonate were added to a two-necked flask. Tetrahydrofuran and water were added as solvents. After purging with nitrogen three times, tetra(triphenylphosphine)palladium catalyst was added and reacted for 12 hours. After removing tetrahydrofuran, the product was extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried with anhydrous magnesium sulfate. The solvent was removed by vacuum distillation. The crude product was then purified by column chromatography to obtain a narrow-band blue light molecule.

[0092] In some preferred embodiments, in step S1 of the method for preparing narrow-band blue light molecules of this application, the molar ratio of 2,6-difluoro-4-bromoiodobenzene, 3,6-di-tert-butylcarbazole and cesium carbonate is 1:(2-3):(2-3), the reaction temperature is 110-150°C, and the reaction time is 24-36 h.

[0093] In some preferred embodiments, the molar ratio of intermediate 1, n-butyllithium (2.5M), and boron tribromide in step S2 of the method for preparing narrow-band blue light molecules of this application is 1:(2-3):(1-2), the reaction temperature is 0 to -20°C, and the reaction time is 1 to 2 hours.

[0094] In some preferred embodiments, in the preparation method described in this application, the molar ratio of intermediate 2 to pinacol diborate, potassium acetate, and 1,1-bis(diphenylphosphine)ferrocene palladium dichloride in step S3 is 1:2:3:0.05, the reaction temperature is 100-140°C, and the reaction time is 12-24 h.

[0095] In some preferred embodiments, in the preparation method described in this application, the molar ratio of 1-bromo-9-fluorenone to the donor group, carbon tetrachloride and methanesulfonic acid in step S4 is 1:4, the reaction temperature is 90°C, and the reaction time is 24 h.

[0096] In some preferred embodiments, in the preparation method described in this application, the molar ratio of intermediate 3, intermediate 4, potassium carbonate, tetrahydrofuran, water and tetra(triphenylphosphine)palladium in step S5 is (1-2):1:2:0.05, the reaction temperature is 70-80°C, and the reaction time is 12h.

[0097] This application also provides the application of narrowband blue light molecules as luminescent materials, luminescent devices, or smart materials.

[0098] The preparation method of narrow-band blue light molecular formula (I) compounds will be described in detail below, taking A1, A2, A3 and A4 as examples.

[0099] Example 1

[0100] This embodiment provides a narrow-band blue light molecule, with the structural formula shown in A1:

[0101]

[0102] The preparation method of this compound is as follows:

[0103] S1. Preparation of intermediate 1:

[0104] 2,6-Difluoro-4-bromoiodobenzene (20 mmol, 6.38 g), 3,6-di-tert-butylcarbazole (25 mmol, 13.97 g), and cesium carbonate (30 mmol, 19.55 g) were sequentially added to a 250 mL two-necked flask. After purging with nitrogen three times, 80 mL of N,N-dimethylformamide was added via syringe. The reaction was carried out at 150 °C for 24 hours under nitrogen atmosphere. After the reaction was completed, the system was allowed to return to room temperature, and then extracted and washed with dichloromethane and saturated brine. The organic phase was recovered, the solvent was removed, and ethanol was added. The mixture was heated and stirred, and then filtered to obtain intermediate 1 with a yield of 75%. The structural formula of intermediate 1 is shown below:

[0105]

[0106] The reaction equations in the above preparation method are as follows:

[0107]

[0108] S2. Preparation of intermediate 2;

[0109] At a low temperature of -10°C, intermediate 1 (1 mmol, 837.7 mg) was dissolved in 20 mL of o-xylene. 2.1 mL of n-butyllithium (2.5 M) (1.8 mmol, 0.4 mL) was slowly added with stirring. After stirring for 1 hour, boron tribromide (1.5 mmol, 375 mg) was added with stirring. After two hours, N,N-diisopropylethylamine (2.0 mmol, 258.48 mg) was added, and the mixture was heated to 120°C and reacted for 12 hours. After the reaction was complete, water was added to quench the reaction. The mixture was then extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried over anhydrous magnesium sulfate. The solvent was removed by vacuum distillation, and the crude product was purified by column chromatography to obtain intermediate 2 in 30% yield. The structural formula of intermediate 2 is shown below:

[0110]

[0111] The reaction equation in the above preparation method is as follows:

[0112]

[0113] S3. Preparation of intermediate 3;

[0114] Intermediate 2 (1 mmol, 719.6 mg) was dissolved in 1,4-dioxane, and pinacol diboronate (2 mmol, 507.88 mg), 1,1-bis(diphenylphosphine)ferrocene palladium dichloride (0.05 mmol, 36.59 mg), and potassium acetate (3 mmol, 294.42 mg) were added. The mixture was purged with nitrogen three times and reacted at 110 °C for 24 hours. The mixture was then extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried over anhydrous magnesium sulfate. The solvent was removed by vacuum distillation, and the crude product was purified by column chromatography to yield intermediate 3 in 60% yield. The structural formula of intermediate 3 is shown below.

[0115]

[0116] The reaction equations involved in the above preparation steps are as follows:

[0117]

[0118] Preparation of intermediate 4 (S4):

[0119] 1-Bromo-9-fluorenone (1 mmol, 260 mg) and N-phenylcarbazole (4 mmol, 970 mg) were dissolved in carbon tetrachloride and methanesulfonic acid solvent. The mixture was purged with nitrogen three times and reacted at 90 °C for 24 hours. The mixture was then extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried over anhydrous magnesium sulfate. The solvent was removed by vacuum distillation. The crude product was then purified by column chromatography to yield intermediate 4 in 63% yield. The structural formula of intermediate 4 is shown below:

[0120]

[0121] The reaction equation in the above preparation method is as follows:

[0122]

[0123] Preparation of S5.A1:

[0124] Intermediate 4 (1 mmol, 730 mg), intermediate 3 (1.2 mmol, 920 mg), and potassium carbonate (2 mmol, 280 mg) were dissolved in tetrahydrofuran and water (1:8). After purging with nitrogen three times, the catalyst tetra(triphenylphosphine)palladium (0.05 mmol, 60 mg) was added and the reaction was carried out at 75 °C for 24 hours. After removing the tetrahydrofuran, the mixture was extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried over anhydrous magnesium sulfate. The solvent was removed by vacuum distillation. The crude product was then purified by column chromatography in 71% yield, yielding the final compound A1, the structure of which is shown below:

[0125]

[0126] The reaction equation in the above preparation method is as follows:

[0127]

[0128] Example 2

[0129] This embodiment provides another narrow-band blue light molecule, the preparation method of which is basically the same as that of Example 1. The difference is that, unlike Example 1, the group of R1 is... The narrow-band blue light molecule A2 was obtained, and its structural formula is shown below:

[0130]

[0131] Example 3

[0132] This embodiment provides another narrow-band blue light molecule, the preparation method of which is basically the same as that of Example 1. The difference is that, unlike Example 1, the group of R1 is... The narrow-band blue light molecule A3 was obtained, and its structural formula is shown below:

[0133]

[0134] Example 4

[0135] This embodiment provides another narrow-band blue light molecule, the preparation method of which is basically the same as that of Example 1. The difference is that, unlike Example 1, the group of R1 is... The narrow-band blue light molecule A4 was obtained, and its structural formula is shown below:

[0136]

[0137] Performance testing

[0138] The narrow-band blue light molecules A1, A2, A3, and A4 prepared in Examples 1, 2, 3, and 4 were characterized and their performance was tested.

[0139] The testing method is as follows:

[0140] Compound structure determination: Bruker 400MHz superconducting nuclear magnetic resonance spectrometer, deuterated chloroform or deuterated dimethyl sulfoxide as solvent;

[0141] Mass spectrometry detection: A1, A2, A3, and A4 obtained in Examples 1, 2, 3, and 4 were dissolved in dichloromethane to prepare a solution with a concentration of 1 mg / mL, and mass spectrometry was performed using a liquid chromatography-mass spectrometry (LCMS-2020) instrument.

[0142] Ultraviolet absorption spectroscopy detection: Shimadzu UV-2700 UV-Vis spectrophotometer was used, with a scanning range of 310–650 nm;

[0143] Emission spectroscopy detection: A steady-state / transient fluorescence spectrometer (FLS980) was used, with an excitation wavelength of 365 nm, under nitrogen protection, and a test temperature of 300 K.

[0144] The test results are as follows:

[0145] The 1H NMR spectrum of the narrow-band blue light molecule A1 prepared in Example 1 is as follows: Figure 1 As shown. From Figure 1 It can be seen that: 1 HNMR(400MHz,Methylene Chloride-d2)δ8.94(d,J=2.0Hz,2H),8.29(d,J=1.9Hz,2H),8.05(dd,J=7.7,1.2Hz,1H),7.96(d,J=2.1Hz,2H),7.84(dt,J= 7.7,1.0Hz,1H),7.80(d,J=2.0Hz,2H),7.64(d,J=7.8Hz,2H),7.58(d,J=2.9Hz,1H),7.52(s,2H),7.35(dd,J=8.7,1.9Hz,2H The peak energies of the proton NMR spectrum of this molecular molecule correspond one-to-one with the target product, and the number is reasonable; the mass spectrum of compound A1 prepared in Example 1 of this application is as follows: 7.27 (dd, J = 7.5, 1.1 Hz, 1H), 7.23 (dt, J = 8.7, 1.2 Hz, 2H), 7.19 (d, J = 6.3 Hz, 1H), 7.16-7.10 (m, 8H), 7.08 (dd, J = 7.5, 1.2 Hz, 1H), 6.98 (t, J = 8.3 Hz, 4H), 6.92 (t, J = 7.5 Hz, 2H), 6.80 (d, J = 8.9 Hz, 5H), 6.12 (d, J = 8.9 Hz, 2H), 1.58 (s, 18H), 1.10 (s, 18H). Figure 2 As shown. From Figure 2 As can be seen in the figure, the relative molecular mass is 1287.65, which is consistent with the relative molecular mass of the synthesized A1. Combining the results of the above proton NMR spectrum and mass spectrum, it can be concluded that the product obtained in Example 1 is A1.

[0146] The 1H NMR spectrum of the narrow-band blue light molecule A2 prepared in Example 2 is as follows: Figure 3 As shown. From Figure 3 It can be seen that: 1HNMR(400MHz,Chloroform-d)δ9.10(d,J=2.0Hz,2H),8.38(d,J=1.8Hz,2H),8.10(d, J=2.0Hz,2H),7.93-7.80(m,3H),7.77-7.68(m,3H),7.52(t,J=7.5Hz,1H),7.49-7.36 (m,3H), 7.33-7.21(m,3H), 7.15-7.02(m,3H), 6.76-6.72(m,8H), 6.72-6.69(m,5H), 6.69-6.66(m,2H), 6.41-6.36(m,5H), 6.36-6.34(m,5H), 1.64(s,18H), 1.31(s,18H). The molecular proton NMR peak energies correspond one-to-one with the target product, and the number is reasonable; the mass spectrum of compound A2 prepared in Example 2 of this application is as follows. Figure 4 As shown. From Figure 4 As can be seen in the figure, the relative molecular mass is 1292.68, which is consistent with the relative molecular mass of the synthesized A2. Combining the above NMR and mass spectrometry results, it can be concluded that the product obtained in Example 2 is A2.

[0147] The 1H NMR spectrum of the narrow-band blue light molecule A3 prepared in Example 3 is as follows: Figure 5 As shown. From Figure 5 It can be seen that: 1 ¹H NMR (400MHz, Chloroform-d) δ 9.12 (d, J = 1.9Hz, 3H), 8.43 (d, J = 1.8Hz, 3H), 8.17 (d, J = 2.1Hz, 3H), 7.98 (d, J = 8.8Hz, 4H), 7.81 (d, J = 9.3Hz, 3H), 7.65 (dd, J = 8.8, 2.1Hz, 4H), 7.32 (t, J = 7.5Hz, 2H), 7.24-6.91 (m, 8H), 6.42 (s, 13H), 1.70 (s, 18H), 1.22 (s, 18H). The ¹H NMR molecular peak energies correspond one-to-one with the target product, and the number is reasonable; the mass spectrum of compound A3 prepared in Example 3 of this application is as follows. Figure 6 As shown. From Figure 6 As can be seen in the figure, the relative molecular mass is 1319.63, which is consistent with the relative molecular mass of the synthesized A3. Combining the above NMR and mass spectrometry results, it can be concluded that the product obtained in Example 3 is A3.

[0148] The proton NMR spectrum of the narrow-band blue light molecule A4 prepared in Example 4 is as follows: Figure 7 As shown. From Figure 7 It can be seen that: 1HNMR(400MHz,Chloroform-d)δ9.10(d,J=1.9Hz,2H),8.34(d,J=1.8Hz,2H),8.04-7.97(m,3H),7.86(d, J=7.6Hz,1H),7.80-7.71(m,4H),7.58(t,J=7.6Hz,1H),7.47(dd,J=8.8,2.1Hz,2H),7.37(t,J=6.8Hz,1 The 1H NMR molecular proton spectrum peak energies correspond one-to-one with the target product, and the number is reasonable; the mass spectrum of compound A4 prepared in Example 4 of this application is as follows: 7.24-7.17 (m, 3H), 6.89 (d, J = 8.5 Hz, 2H), 6.76 (dd, J = 8.5, 2.2 Hz, 2H), 6.66 (d, J = 3.4 Hz, 4H), 6.59-6.52 (m, 4H), 6.37-6.29 (m, 4H), 6.16 (d, J = 7.0 Hz, 2H), 5.95 (d, J = 6.9 Hz, 2H), 1.69 (s, 18H), 1.17 (s, 18H). Figure 8 As shown. From Figure 8 As can be seen in the figure, the relative molecular mass is 1347.59, which is consistent with the relative molecular mass of the synthesized A4. Combining the above NMR and mass spectrometry results, it can be concluded that the product obtained in Example 4 is A4.

[0149] Using a Shimadzu UV-2700 UV-Vis spectrophotometer, A1, A2, A3, and A4 obtained in the examples were dissolved in dichloromethane solution to prepare a 1×10⁻⁶ solution. -3 The stock solution was prepared at mol / L and then diluted to 1×10⁻⁶. -5 The test was conducted using a mol / L toluene solution.

[0150] Figure 9 The A1, A2, A3, and A4 prepared in Examples 1, 2, 3, and 4 were subjected to a 1×10⁻⁶ ppm. -5 The UV-Vis absorption spectrum of toluene in mol / L. Figure 9 It can be seen that the main absorption peaks of A1, A2, A3, and A4 are all located at 472 nm.

[0151] Fluorescence emission spectroscopy was used: an FLS980 fluorescence spectrometer. A1, A2, A3, and A4 obtained in the examples were dissolved in dichloromethane solution to prepare a 1×10⁻⁶ solution. -3 The stock solution, initially at mol / L, was diluted to 1×10⁻⁶ for testing. -5 A solution of mol / L.

[0152] Figure 10 The A1, A2, A3, and A4 prepared in Examples 1, 2, 3, and 4 were subjected to a 1×10⁻⁶ ppm.-5 Fluorescence emission spectrum of a mol / L toluene solution. From Figure 10 It can be seen that the main emission peaks of A1, A2, A3, and A4 are located at around 486nm, all of which emit blue light. Furthermore, the half-width of A1, A2, A3, and A4 is in the range of 22nm-25nm, which means that short-wavelength emission is achieved and good luminescence performance is maintained.

[0153] Figure 11 The figures show the luminance-external quantum efficiency (EQE) curves and electroluminescence spectra of the devices with different doping concentrations in Example 1 of this application. As can be seen from the figures, Example 1 of this application achieves a maximum EQE of 33.61% at a doping concentration of 20 wt%. (Reference) Figure 12 The three-dimensional design diagram and schematic diagram of the narrow-band blue light molecule provided in this application are shown. This is because the narrow-band blue light molecule provided in this application bridges the donor unit and the multiple resonance unit through the fluorene framework, realizing a combination of two different charge transfer modes: long-range charge transfer and short-range charge transfer. While maintaining the narrow-band emission characteristic of the short-range charge transfer of the multiple resonance unit, the high-energy excited state with long-range charge transfer properties is introduced to promote the exciton spin-flip coupling of the multi-channel system, achieving faster reverse intersystem crossing and maintaining good luminescence performance.

[0154] Meanwhile, as the doping concentration increases, there is no significant decrease in efficiency like most MR-TADF devices. On the contrary, as the doping concentration increases, the maximum EQE gradually increases, and the maximum EQE does not change significantly between 5wt% and 20wt% doping concentrations, showing excellent insensitivity to doping concentration. This is mainly because the additional donor unit can bring a great steric hindrance effect, which prevents molecules from forming long-range π-π stacking, effectively suppressing the severe aggregation-induced luminescence quenching of MR-TADF molecules, and enabling the molecules to maintain good luminescence performance at high doping concentrations.

[0155] In summary, the narrow-band blue molecule provided in this application can serve as a novel luminescent molecule with high performance, high color purity, and high quantum efficiency. This narrow-band blue molecule has enormous application potential in the preparation of luminescent materials, luminescent devices, and smart materials, and shows great promise in the fields of full-color displays and solid-state lighting.

[0156] Meanwhile, this application achieves the controllable preparation of narrow-band blue light molecules; the raw materials are widely available, enabling large-scale production and possessing broad commercial prospects.

[0157] The narrow-band blue light molecule provided in this application bridges the donor unit and the multiple resonance unit through a fluorene framework, combining two different charge transfer modes: long-range charge transfer and short-range charge transfer. While maintaining the narrow-band emission characteristic of short-range charge transfer in the multiple resonance unit, a high-energy excited state with long-range charge transfer properties is introduced to promote multi-channel exciton spin-flip coupling, achieving faster reverse intersystem crossing.

[0158] Meanwhile, the additional donor unit introduces a significant steric hindrance effect, preventing long-range π-π stacking between molecules. This effectively suppresses the severe aggregation-induced luminescence quenching of MR-TADF molecules, resulting in an EQE of 33.61% at a 20% doping concentration. This makes it a novel luminescent molecule with good performance, low cost, and high luminescence intensity. It overcomes the shortcomings of existing technologies, such as the lack of efficient, high-color-purity, and low-roll-off narrow-spectrum blue light emitting materials.

[0159] Therefore, the narrow-band blue light molecule provided in this application can be used as a luminescent material or smart material, and has great application prospects in the fields of full-color display and solid-state lighting.

[0160] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0161] Although several embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A narrow-band blue light molecule, which can be used in organic small molecule optoelectronic functional materials, characterized in that, It has the molecular structure shown in formula (Ⅰ): Wherein, D is an electron-donating group, and D is selected from one of the following structural formulas:

2. The method for preparing narrow-band blue light molecules according to claim 1, characterized in that, Includes the following steps: S1. Preparation of intermediate 1 2,6-Difluoro-4-bromoiodobenzene, 3,6-di-tert-butylcarbazole, and cesium carbonate were added sequentially to a reaction flask. After purging with nitrogen three times, N,N-dimethylformamide was added, and the reaction was refluxed under nitrogen. After the reaction was completed, the system was allowed to return to room temperature, and then extracted and washed with dichloromethane and saturated brine. The organic phase was recovered, the solvent was removed, and ethanol was added. The mixture was heated and stirred, and then filtered to obtain intermediate 1, the structural formula of which is shown below: S2. Preparation of intermediate 2 Intermediate 1 obtained in step S1 was dissolved in o-xylene, and n-butyllithium was slowly added with stirring. Then, boron tribromide was added with stirring, followed by N,N-diisopropylethylamine, and stirring was continued. After the reaction was completed, water was added to quench the reaction. The product was extracted and washed with dichloromethane and saturated brine, the organic phase was recovered and dried with anhydrous magnesium sulfate, the solvent was removed by vacuum distillation, and the crude product was then purified by column chromatography to obtain intermediate 2, the structure of which is shown below. S3. Preparation of intermediate 3 Intermediate 2 obtained in step S2 was dissolved in 1,4-dioxane, and pinacol diboronate, 1,1-bis(diphenylphosphine)ferrocene palladium dichloride, and potassium acetate were added. After reacting under nitrogen purging for 12-24 hours three times, the mixture was extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried over anhydrous magnesium sulfate. The solvent was removed by vacuum distillation, and the crude product was then purified by column chromatography to generate intermediate 3, the structure of which is shown below: S4. Preparation of intermediate 4 1-Bromo-9-fluorenone and a compound containing an electron-donating group were added to a two-necked flask, and carbon tetrachloride and methanesulfonic acid solvent were added. The mixture was purged with nitrogen three times and reacted for 24 hours. The product was extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried over anhydrous magnesium sulfate. The solvent was removed by vacuum distillation. The crude product was then purified by column chromatography to yield intermediate 4, whose structural formula is shown below: S5. Preparation of narrow-band blue light molecules: Intermediate 3, intermediate 4, and potassium carbonate were added to a two-necked flask. Tetrahydrofuran and water were added as solvents. After purging with nitrogen three times, tetra(triphenylphosphine)palladium catalyst was added and reacted for 12 hours. After removing tetrahydrofuran, the product was extracted and washed with dichloromethane and saturated brine. The organic phase was recovered and dried with anhydrous magnesium sulfate. The solvent was removed by vacuum distillation. The crude product was then purified by column chromatography to obtain a narrow-band blue light molecule.

3. The method for preparing narrow-band blue light molecules according to claim 2, characterized in that, In step S1, the molar ratio of 2,6-difluoro-4-bromoiodobenzene, 3,6-di-tert-butylcarbazole and cesium carbonate is 1:(2-3):(2-3).

4. The method for preparing narrow-band blue light molecules according to claim 3, characterized in that, In step S1, the reaction temperature is 110–150°C and the reaction time is 24–36 h.

5. The method for preparing narrow-band blue light molecules according to claim 2, characterized in that, In step S2, the molar ratio of intermediate 1, n-butyllithium, and boron tribromide is 1:(2-3):(1-2), the reaction temperature is 0 to -20°C, and the reaction time is 1 to 2 hours.

6. The method for preparing narrow-band blue light molecules according to claim 2, characterized in that, In step S3, the molar ratio of intermediate 2 to pinacol diborate, potassium acetate, and 1,1-bis(diphenylphosphine)ferrocene palladium dichloride is 1:2:3:0.05, the reaction temperature is 100-140℃, and the reaction time is 24h.

7. The method for preparing narrow-band blue light molecules according to claim 2, characterized in that, In step S4, the molar ratio of 1-bromo-9-fluorenone to the compound containing an electron-donating group is 1:4, and the reaction temperature is 90°C.

8. The method for preparing narrow-band blue light molecules according to claim 2, characterized in that, In step S5, the molar ratio of intermediate 3, intermediate 4, potassium carbonate and tetra(triphenylphosphine)palladium is (1-2):1:2:0.05, and the reaction temperature is 70-80℃.

9. The application of the narrow-band blue light molecule of claim 1 as a luminescent material and luminescent device.

Images