Aggregation-induced delayed fluorescence (AIDF) type organic scintillator material and preparation method thereof, and preparation method and application of flexible organic scintillation film

Abstract

The invention belongs to the technical field of organic radiation luminescence and radiation imaging, and discloses an aggregation-induced delayed fluorescence (AIDF) type organic scintillator material and a preparation method thereof, and a preparation method and application of a flexible organic scintillation film. The molecular structure of the material comprises carbonyl, methylene, sulfuryl and other connecting units, phthalonitrile is used as an acceptor unit, carbazole is used as a donor unit, an aggregation-induced excitation state is formed through space charge transfer among molecules, efficient AIDF luminescence and large Stokes shift characteristics are realized, the self-absorption phenomenon is effectively avoided, and the luminescent efficiency is improved. The X-ray fluorescence probe is suitable for a luminescence process under an X-ray excitation condition, the sensitivity of X-ray detection is remarkably improved, and the lowest detection limit can reach 276nGy.s <-1 > and is far superior to the 5.5 mu Gy.s <-1 > standard required by medical diagnosis. Besides, the flexible scintillator film prepared based on the material system radiates and emits light within the waveband range of 450-750 nm and is perfectly matched with the response area of a silicon-based detector, X-ray imaging with the high signal-to-noise ratio is achieved, and the imaging resolution is as high as 20.01 lp.mm <-1 >.

Description

Technical Field

[0001] This invention relates to the field of organic radiation luminescence and radiation imaging technology, specifically to an aggregation-induced delayed fluorescence (AIDF) type organic scintillator material and its preparation method, a method for preparing flexible organic scintillator films and their applications. Background Technology

[0002] Scintillators are functional materials that can convert high-energy ionizing radiation (such as X-rays and gamma rays) into visible light, and are widely used in security inspection, industrial non-destructive testing, scientific research, medical imaging, and other fields. Compared with traditional inorganic scintillators, organic scintillators exhibit enormous application potential due to the diversity of their molecular structure designs, good processability, and flexibility. First, organic scintillators have high sensitivity, efficiently converting X-ray signals into visible light output, meeting the imaging requirements under low-dose conditions. Second, they are highly malleable, easily processed into thin films, flexible devices, or large-area imaging panels, adaptable to complex device structures. Furthermore, the synthesis process of organic scintillators is relatively simple and low-cost, suitable for large-scale production, and possesses good economic viability and industrialization prospects.

[0003] However, existing organic scintillators still face significant challenges, especially the tendency for luminescence quenching at high concentrations, which reduces exciton recombination efficiency and affects the material's luminescence intensity and imaging quality. Furthermore, thermally activated delayed fluorescence (TADF) materials, hailed as third-generation organic light-emitting materials, have been widely used in various fields, but their quenching problem at high concentrations also limits further performance improvements. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing an aggregation-induced delayed fluorescence (AIDF) type organic scintillator material and its preparation method, as well as a method for preparing flexible organic scintillator films and their applications.

[0005] The technical solution of this invention to solve the above problems is an aggregation-induced delayed fluorescence (AIDF) type organic scintillator material with a structure as shown in formula (I):

[0006]

[0007] The preparation method of the above-mentioned aggregation-induced delayed fluorescence (AIDF) type organic scintillator material includes the following steps:

[0008] Step 1: Under argon protection, add carbazole and NaH to a two-necked flask, seal it, evacuate and purge with argon, and repeat three times.

[0009] Step 2: At 0°C, add anhydrous tetrahydrofuran using a syringe, stir until completely dissolved, and continue the reaction for 10 minutes after returning to room temperature;

[0010] Step 3: Dissolve the intermediate in THF solution and slowly inject it into a two-necked flask with a syringe. Stir at 0°C for 10 minutes, and then continue the reaction at room temperature for 2 hours.

[0011] Step 4: After the reaction is complete, the mixture is cooled naturally and extracted with dichloromethane. The organic phase is collected and dried with anhydrous MgSO4. The solvent is removed by vacuum evaporation. The obtained product is purified by column chromatography to obtain a yellow-green powder, which is the AIDF type organic scintillator material.

[0012] Furthermore, the intermediate is one of 3,5-dicyanobenzoyl chloride, 3,5-dicyanobenzyl chloride, and 3,5-dicyanobenzenesulfonyl chloride.

[0013] Furthermore, the molar ratio of the intermediate, carbazole, and NaH is 1:1:1.2.

[0014] A method for preparing a flexible organic scintillation film includes the following steps:

[0015] Step 1: Mix the AIDF-type organic scintillator material according to claim 1 with polysulfone at a mass ratio of 1:(10-100);

[0016] Step 2: Add organic solvent and stir until completely dissolved to obtain a mixed solution;

[0017] Step 3: Transfer the mixed solution into a mold and slowly evaporate the solvent at the reaction temperature to obtain a flexible organic scintillation film.

[0018] Furthermore, in step 2, the organic solvent includes one or more mixed solvents selected from dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetramethyl sulfoxide, dichloromethane, ethyl acetate, and chloroform.

[0019] Furthermore, the thickness of the flexible organic scintillation film is 50–900 μm.

[0020] Furthermore, the reaction temperature range in step 3 is 25–80°C.

[0021] The flexible organic scintillation films prepared by the above method have applications in X-ray detection, X-ray imaging, radiation dose measurement, and organic optoelectronic devices, including but not limited to flexible X-ray detectors, low-dose medical imaging equipment, portable X-ray security inspection instruments, and security monitoring equipment.

[0022] The present invention has the following beneficial effects:

[0023] This invention provides an aggregation-induced delayed fluorescence (AIDF) type organic scintillator material and its preparation method, as well as a method for preparing flexible organic scintillator films and their applications. The AIDF type organic scintillator material overcomes the technical bottlenecks of traditional inorganic scintillators, such as high manufacturing cost, complex preparation, severe self-absorption, and difficulty in achieving flexibility. It significantly improves X-ray detection sensitivity, with a detection limit as low as 276 nGy s. -1 This is better than the standard required for medical diagnosis (5.5 μGy s). -1 Spatial resolution up to 20.0 lp mm. -1 This material exhibits high imaging resolution. Through a large Stokes shift design, it effectively avoids self-absorption, achieving efficient photon utilization. Furthermore, it maintains stable and excellent luminescence performance even under high concentration conditions, solving the problem of quenching in organic scintillators. Its emission spectrum lies between 450 and 700 nm, highly matching the response range of silicon-based detectors. It can also be fabricated into flexible thin films, suitable for novel applications such as flexible X-ray detectors, wearable devices, and portable imaging systems. Moreover, the overall fabrication process is environmentally friendly, requiring no heavy metal components, making it suitable for large-scale, low-cost production. This invention not only significantly improves the overall performance of organic scintillator materials in X-ray imaging and detection but also provides new ideas and strategies for solving the high-concentration quenching problem and designing high-performance organic scintillators, possessing significant scientific research value and broad application prospects. Attached Figure Description

[0024] Figure 1 The image shows the luminescence lifetime of the AIDF-type organic scintillator material prepared in Example 1 under different temperature conditions.

[0025] Figure 2 The photoluminescence spectrum of the water / THF system of the AIDF-type organic scintillator material prepared in Example 1 is shown.

[0026] Figure 3 The following are emission spectra of different doping concentrations and radiation intensities for Comparative Examples 1-5.

[0027] Figure 4 The images show the radiation spectra of the AIDF-type organic scintillator thin film prepared in Comparative Example 4 at different dose rates.

[0028] Figure 5 The graph shows the relationship between the radiative emission intensity and radiation dose rate of the AIDF-type organic scintillator thin film prepared in Comparative Example 4.

[0029] Figure 6 The diagram shows the cyclic switching stability and continuous irradiation stability of the AIDF-type organic scintillator thin film prepared in Comparative Example 4.

[0030] Figure 7The spatial resolution (MTF) diagram of the AIDF-type organic scintillator thin film prepared in Comparative Example 4 is shown.

[0031] Figure 8 This is an X-ray scintillator image of the AIDF-type organic scintillator thin film prepared in Comparative Example 4.

[0032] Figure 9 Line-to-card image of the AIDF-type organic scintillator thin film prepared in Comparative Example 4. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] An AIDF-type organic scintillator material has the structure shown in formula (I):

[0035]

[0036] The molecular framework, comprising carbonyl, methylene, and sulfone linkers, uses phthalonitrile as the acceptor unit and carbazole as the donor unit. Employing a long-range donor-acceptor (DA) molecular structure, it avoids intramolecular charge transfer states. Instead, the intermolecular donor and acceptor are arranged at short distances, forming an aggregation-induced excited state through intermolecular charge transfer, while also possessing a small singlet triplet energy difference (ΔE). ST It has high AIDF luminescence efficiency and large Stokes shift properties, which can effectively avoid self-absorption and is suitable for X-ray excitation.

[0037] Example 1

[0038] AIDF-type organic scintillator material is 5-(9H-carbazole-9-carbonyl)isophthalonitrile, and its synthetic route is as follows:

[0039]

[0040] The specific preparation method includes the following steps:

[0041] Step 1: Under argon protection, add carbazole (0.84g, 5.0mmol) and NaH (0.24g, 6.0mmol) to a two-necked flask, seal it, evacuate and purge with argon, and repeat three times.

[0042] Step 2: At 0°C, add 20 mL of anhydrous tetrahydrofuran (THF) using a syringe and stir to dissolve at room temperature.

[0043] Step 3: At 0°C, the intermediate 3,5-dicyanobenzoyl chloride (1.10 g, 5 mmol) was dissolved in 10 mL of THF solution and slowly injected into a two-necked flask with a syringe. The mixture was stirred at 0°C for 10 minutes and then the reaction was continued at room temperature for 2 hours.

[0044] Step 4: After the reaction is complete, the mixture is allowed to cool naturally and extracted three times with dichloromethane. The organic phase is collected and dried over anhydrous MgSO4. Silica gel powder is added, and the solvent is removed by rotary evaporation under reduced pressure. The residue is purified by column chromatography to obtain 1.10 g of 5-(9H-carbazole-9-carbonyl)isophthalonitrile, a yellow-green powder, with a yield of 70%. The eluent for column chromatography purification is petroleum ether, and the ratio of petroleum ether to dichloromethane is 3:1.

[0045] Example 2

[0046] AIDF-type organic scintillator material is 5-((9H-carbazole-9-yl)methyl)isophthalonitrile, and its synthetic route is as follows:

[0047]

[0048] The specific preparation method includes the following steps:

[0049] Step 1: Under argon protection, add carbazole (0.84g, 5.0mmol) and NaH (0.24g, 6.0mmol) to a two-necked flask, seal it, evacuate and purge with argon, and repeat three times.

[0050] Step 2: At 0°C, add 20 mL of anhydrous tetrahydrofuran (THF) using a syringe and stir to dissolve at room temperature.

[0051] Step 3: At 0°C, the intermediate 3,5-dicyanobenzenesulfonyl chloride (0.88 g, 5 mmol) was dissolved in 10 mL of THF solution and slowly injected into a two-necked flask with a syringe. The mixture was stirred at 0°C for 10 minutes and then the reaction was continued at room temperature for 2 hours.

[0052] Step 4: After the reaction is complete, the mixture is cooled naturally and extracted three times with dichloromethane. The organic phase is collected and dried with anhydrous MgSO4. Silica gel powder is added and the solvent is removed by rotary evaporation under reduced pressure. The residue is purified by column chromatography to obtain 0.95 g of yellow-green powder 5-((9H-carbazole-9-yl)methyl)isophthalonitrile, with a yield of 62%. The eluent for column chromatography purification is petroleum ether, and the ratio of petroleum ether to dichloromethane is 4:1.

[0053] Example 3

[0054] AIDF-type organic scintillator material is 5-((9H-carbazole-9-yl)sulfonyl)isophthalonitrile, and its synthetic route is as follows:

[0055]

[0056] The specific preparation method includes the following steps:

[0057] Step 1: Under argon protection, add carbazole (0.84g, 5.0mmol) and NaH (0.24g, 6.0mmol) to a two-necked flask, seal it, evacuate and purge with argon, and repeat three times.

[0058] Step 2: At 0°C, add 20 mL of anhydrous tetrahydrofuran (THF) using a syringe and stir to dissolve at room temperature.

[0059] Step 3: At 0°C, the intermediate 3,5-dicyanobenzenesulfonyl chloride (1.13 g, 5 mmol) was dissolved in 10 mL of THF solution and slowly injected into a two-necked flask with a syringe. The mixture was stirred at 0°C for 10 minutes and then the reaction was continued at room temperature for 2 hours.

[0060] Step 4: After the reaction is complete, the mixture is cooled naturally and extracted three times with dichloromethane. The organic phase is collected and dried with anhydrous MgSO4. Silica gel powder is added and the solvent is removed by rotary evaporation under reduced pressure. The residue is purified by column chromatography to obtain 1.01 g of yellow-green powder 5-((9H-carbazole-9-yl)sulfonyl)isophthalonitrile, with a yield of 57%. The eluent for column chromatography purification is petroleum ether, and the ratio of petroleum ether to dichloromethane is 4:1.

[0061] Comparative Example 1

[0062] The preparation of a 1 wt% doped flexible thin film using the AIDF-type organic scintillator material prepared in Example 1 includes the following steps:

[0063] Weigh 0.01 g (1 wt%) of AIDF-type organic scintillator material (AIDF) and 0.99 g (99 wt%) of polysulfone (PSF), and add them together to a 100 mL beaker equipped with a magnetic stir bar. Add 20 mL of chloroform as a solvent and stir at room temperature for 2 hours to fully dissolve the AIDF material and PSF, forming a homogeneous and transparent solution. After dissolution, slowly drop the solution into a pre-prepared 5 cm × 5 cm quartz mold using a 10 mL syringe, ensuring a smooth liquid surface. Then cover the mold opening with aluminum foil and prick 5-10 tiny pores (approximately 0.5 mm in diameter) in the foil with a needle to release gas during solvent evaporation and prevent bubble formation. Place the mold in a well-ventilated room temperature environment and let it stand for 12 hours to allow the chloroform solvent to fully evaporate and form a cured film. A flexible organic scintillator film with a thickness of approximately 100 μm, a smooth surface, and no obvious defects is finally obtained. It exhibits good light transmittance in the visible light region and possesses excellent mechanical flexibility and stable luminescent properties.

[0064] Comparative Example 2

[0065] A flexible thin film with a doping concentration of 3 wt% was prepared using the AIDF-type organic scintillator material prepared in Example 1. The difference from the comparative example is that 0.03 g (3 wt%) of AIDF-type organic scintillator material and 0.97 g (97 wt%) of polysulfone (PSF) were weighed.

[0066] Comparative Example 3

[0067] A flexible thin film with a doping concentration of 5 wt% was prepared using the AIDF-type organic scintillator material prepared in Example 1. The difference from the comparative example is that 0.05 g (5 wt%) of AIDF-type organic scintillator material and 0.95 g (95 wt%) of polysulfone (PSF) were weighed.

[0068] Comparative Example 4

[0069] A flexible thin film with a doping concentration of 7 wt% was prepared using the AIDF-type organic scintillator material prepared in Example 1. The difference from the comparative example is that 0.07 g (7 wt%) of AIDF-type organic scintillator material and 0.93 g (93 wt%) of polysulfone (PSF) were weighed.

[0070] Comparative Example 5

[0071] A flexible thin film with a doping concentration of 10 wt% was prepared using the AIDF-type organic scintillator material prepared in Example 1. The difference from the comparative example is that 0.10 g (10 wt%) of AIDF-type organic scintillator material and 0.90 g (90 wt%) of polysulfone (PSF) were weighed.

[0072] The performance of the AIDF-type organic scintillator material prepared in Example 1 and the thin films prepared in Comparative Examples 1-5 were tested, and the test results are as follows:

[0073] Depend on Figure 1 The data shows that the material system has two distinct lifetime characteristics: instantaneous emission and delayed emission. Furthermore, the emission lifetime decreases with increasing temperature, which is consistent with the typical luminescence characteristics of TADF materials.

[0074] Figure 2 Data shows that as the concentration increases, the luminescence intensity in the 450–700 nm band gradually increases, and a new luminescence peak appears, indicating that the material exhibits AIDF behavior.

[0075] Figure 3 The results show that AIDF-type organic scintillator materials can maintain good X-ray emission intensity and unchanged emission peak position under different doping concentrations, and the best performance is achieved at 7wt% doping.

[0076] Figure 4 Data shows that at 210 mGy s -1At radiation doses of [specific value], the AIDF-type organic scintillator material exhibits radiative emission in the 450–700 nm wavelength range, displaying a yellow-green luminescence that matches the energy spectrum of the silicon-based detector, and its luminescence intensity reaches 10 [units unspecified]. 5 The order of magnitude indicates that it is an efficient organic scintillator material that does not contain heavy atoms.

[0077] Figure 5 Fitting analysis revealed that the radiative emission intensity of the AIDF-type organic scintillator material exhibits a linear relationship with the dose rate, demonstrating a sensitive response. The calculated detection limit is 276 nGy / s. -1 It is superior to the minimum requirements for medical X-ray diagnosis.

[0078] Figure 6 This indicates that at 210 mGy s -1 At certain doses, the AIDF-type organic scintillator material doped film showed almost no decrease in radiative luminescence intensity after 1800s of continuous irradiation or 120 cycles of switching, demonstrating excellent radiation resistance stability.

[0079] Figure 7 The results show that the material's modulation transfer function (MTF) was calculated to be 19.7 lpmm based on standard X-ray edge images. -1 It has a high resolution and excellent image clarity.

[0080] Figure 8 This further demonstrates the application potential of the material system in X-ray microstructure imaging, enabling high-resolution radiation imaging of complex microstructures such as chips.

[0081] Depend on Figure 9 It is known that this material film achieves a spatial resolution of up to 20.0 lpmm for image line-to-card imaging. -1 .

[0082] When the thin films prepared in Comparative Examples 1-5 are applied to an X-ray imaging device, the device possesses the following characteristics:

[0083] (1) High detection sensitivity, high spatial resolution and clear imaging under low dose conditions;

[0084] (2) Flexible and bendable thin film structure, adaptable to complex morphological surfaces;

[0085] (3) When integrated with silicon-based or perovskite detectors, a high-performance flexible X-ray imaging module can be constructed.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An aggregation-induced delayed fluorescence (AIDF) type organic scintillator material, characterized in that: The structure is shown in equation (I):

2. A method for preparing an aggregation-induced delayed fluorescence (AIDF) type organic scintillator material, characterized in that: Includes the following steps: Step 1: Under argon protection, add carbazole and NaH to a two-necked flask, seal it, evacuate and purge with argon, and repeat three times. Step 2: At 0°C, add anhydrous tetrahydrofuran using a syringe, stir until completely dissolved, and continue the reaction for 10 minutes after returning to room temperature; Step 3: Dissolve the intermediate in THF solution and slowly inject it into a two-necked flask with a syringe. Stir at 0°C for 10 minutes, and then continue the reaction at room temperature for 2 hours. Step 4: After the reaction is complete, the mixture is cooled naturally and extracted with dichloromethane. The organic phase is collected and dried with anhydrous MgSO4. The solvent is removed by vacuum evaporation. The obtained product is purified by column chromatography to obtain a yellow-green powder, which is the AIDF type organic scintillator material.

3. The method for preparing an aggregation-induced delayed fluorescence (AIDF) type organic scintillator material as described in claim 2, characterized in that: The intermediate is one of 3,5-dicyanobenzoyl chloride, 3,5-dicyanobenzyl chloride, and 3,5-dicyanobenzyl sulfonyl chloride.

4. The method for preparing an aggregation-induced delayed fluorescence (AIDF) type organic scintillator material as described in claim 2, characterized in that: The molar ratio of the intermediate, carbazole, and NaH is 1:1:1.

2.

5. A method for preparing a flexible organic scintillation thin film, characterized in that: Includes the following steps: Step 1: Mix the AIDF-type organic scintillator material according to claim 1 with polysulfone at a mass ratio of 1:(10-100); Step 2: Add organic solvent and stir until completely dissolved to obtain a mixed solution; Step 3: Transfer the mixed solution into a mold and slowly evaporate the solvent at the reaction temperature to obtain a flexible organic scintillation film.

6. The method for preparing the flexible organic scintillation thin film as described in claim 5, characterized in that: In step 2, the organic solvent includes one or more mixed solvents selected from dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetramethyl sulfoxide, dichloromethane, ethyl acetate, and chloroform.

7. The method for preparing the flexible organic scintillation thin film as described in claim 5, characterized in that: The thickness of the flexible organic scintillation film is 50–900 μm.

8. The method for preparing the flexible organic scintillation thin film as described in claim 5, characterized in that: The reaction temperature range in step 3 is 25–80°C.

9. The application of flexible organic scintillation films prepared by any one of claims 5-8 in X-ray detection, X-ray imaging, radiation dose measurement and organic optoelectronic devices, including but not limited to flexible X-ray detectors, low-dose medical imaging equipment, portable X-ray security inspection instruments and security monitoring equipment.

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