A perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging and its preparation method

Abstract

The present invention provides a perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging and a preparation method thereof. Tetrapropylammonium iodide and cuprous iodide are successively added to a mixed solution of dimethylformamide and hypophosphorous acid to obtain A; A is subjected to oil bath-ultrasonic heating, and then filtered to obtain a transparent solution B; Polymethyl methacrylate is added to the transparent solution B, and induction heating-assisted stirring is carried out. It is heated from room temperature to a preset temperature at a preset induction frequency and kept warm, and then the carbon spheres are taken out to obtain C; C is transferred to a pretreated substrate, the solution is spin-coated on the substrate, and then the substrate is heated and annealed. After cooling to room temperature, the thin film is removed, and thus a perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging is obtained. The scintillator material prepared by the present invention is applied to X-ray detection imaging, and not only has a low X-ray dose and high resolution, but also has the advantages of simple process, non-toxic and pollution-free, and low cost.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of scintillator thin films for X-ray detection imaging, and specifically relates to a method for improving the high-temperature oxidation resistance of 321 stainless steel by low-temperature plasma. Background Art

[0002] X-ray imaging has become one of the most widely used and important clinical medical imaging means in the health field, and is an indispensable key technology for diagnosing lesions, injuries and aging of organs such as the brain, lungs, breasts, bones and cardiovascular system. Among them, the key core of X-ray imaging is the X-ray energy conversion material, that is, the scintillator material. Traditional X-ray imaging technologies commonly use materials such as CsI:Tl, Gd2O2S:Tb, and CZT, which have problems such as high preparation temperature, complex process, high price, and low conversion efficiency. At the same time, X-ray imaging systems still face industry pain points such as large irradiation dose, low resolution, and limited detection scenarios.

[0003] Currently, lead-based halide nanocrystals, as an excellent X-ray scintillator, have been widely reported as a promising scintillator due to their flexible preparation process, strong X-ray blocking ability, tunable emission wavelength, etc. However, their small Stokes shift and self-absorption severely inhibit the light emission efficiency. At the same time, the toxicity of lead is harmful to human health and the environment. In addition, the instability of lead halide perovskite itself and the difficulty in spin-coating large-area high-quality thin films also hinder its commercial application.

[0004] In recent years, lead-free metal halides have attracted the attention of researchers. For example, replacing Pb atoms with Cu, Mn, Bi, etc. have all been reported. Among them, the transition metal Cu has the lowest toxicity, and copper-based halides, as a new type of non-toxic scintillator material, have a large Stokes shift, small self-absorption, and are relatively stable in air. However, compared with lead-based halides, the detection dose of all-inorganic copper-based halides is larger and the resolution is lower. The new type of organic-inorganic hybrid copper-based halides has the advantages of low heavy metal content, environmental friendliness, and large light yield, and has become a research hotspot. Therefore, exploring organic-inorganic hybrid copper-based halide materials for X-ray imaging with low dose and stability has important research value. Summary of the Invention

[0005] The purpose of the present invention is to provide a perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging and its preparation method to overcome the defects of the existing technology. The scintillator material prepared by the present invention is applied to X-ray detection imaging, and not only has a low X-ray dose and high resolution, but also has the advantages of simple process, non-toxic and pollution-free, and low cost.

[0006] The present invention is realized through the following technical solutions:

[0007] A preparation method of a perovskite-like scintillator film for ultra-low dose flexible X-ray imaging, comprising the following steps:

[0008] 1) Add tetrapropylammonium iodide and cuprous iodide successively to a mixed solution of dimethylformamide and hypophosphorous acid solution to obtain A;

[0009] 2) Heat A by oil bath-ultrasound, and then obtain a transparent solution B after filtration;

[0010] 3) Add polymethyl methacrylate to the transparent solution B, then transfer it to an induction heating-stirring kettle, add carbon spheres as the induction source, move the induction heating-stirring kettle into the induction heating-stirring equipment, heat it from room temperature to a preset temperature at a preset induction frequency and keep it warm, and then take out the carbon spheres to obtain C;

[0011] 4) Transfer C to the pretreated substrate, scrape the solution on the substrate, then heat-anneal the substrate, and remove the film after cooling to room temperature to obtain the perovskite-like scintillator film for ultra-low dose flexible X-ray imaging.

[0012] Further, in step 1), the molar ratio of tetrapropylammonium iodide to cuprous iodide is 1:1, the volume ratio of dimethylformamide to hypophosphorous acid solution is 20:1, 6-12 mmol of the mixed powder of tetrapropylammonium iodide and cuprous iodide is added to every 10 mL of the mixed solution of dimethylformamide and hypophosphorous acid solution, and the mass fraction of the hypophosphorous acid solution is 50 wt%.

[0013] Further, in step 2), the oil bath temperature is 40-60 °C, the ultrasound frequency is 20-40 KHz, and the oil bath-ultrasound heating time is 5-15 min.

[0014] Further, in step 2), the filtration is carried out using a 0.22 μm filter head.

[0015] Further, in step 3), the addition amount of polymethyl methacrylate and the dimethylformamide in step 1) is in a ratio of 1 g:3 mL.

[0016] Further, in step 3), the diameter of the carbon spheres is 2 cm, and the stirring speed is 300-500 rpm.

[0017] Further, in step 3), move the induction heating-stirring kettle into the induction heating-stirring equipment, heat it from room temperature to 70-90 °C at an induction frequency of 300-500 KHz, and keep it warm for 10-30 min.

[0018] Further, in step 4), the substrate is a glass plate, and the pretreatment process is specifically: wash the glass plate successively with water, ethanol, and acetone, and then dry it.

[0019] Further, step 5) is specifically as follows: Transfer C onto a glass plate, scrape and coat the solution on the glass plate with a doctor blade, then heat and anneal the glass plate, and remove the film after cooling to room temperature. Among them, the height of the doctor blade is 400 - 600 μm, the scraping speed is 3 m / min, the annealing temperature is 50 - 70 °C, and the annealing time is 10 - 20 min.

[0020] A perovskite-like scintillator film for ultra-low-dose flexible X-ray imaging is prepared by the above preparation method.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] The present invention selects an organic-inorganic hybrid copper-based halide as the scintillator material, which has a perovskite-like structure, emits white light, has good stability in air, is non-toxic and pollution-free, has a wide source of raw materials, and has extremely high resource and cost advantages.

[0023] In the organic-inorganic hybrid copper-based halide flexible film prepared by the present invention, the large atomic numbers of Cu and I are beneficial to improving the X-ray absorption efficiency; the stable bonding energy generated by the inorganic core and the organic ligand can improve the quantum efficiency in its transmission and emission stages, and thus has a large light yield and an ultra-low X-ray detection limit, effectively reducing the X-ray usage dose; the photo-generated excitons will be strongly bound in a single cluster [CuI] of the zero-dimensional structure, and the copper-based halide has soft lattice characteristics, which will lead to a stronger exciton-phonon coupling degree, generating self-trapped exciton-induced luminescence behavior, having a large Stokes shift, and thus having a wide emission spectrum and a high matching degree with the photoelectric sensor, so as to have high-resolution and large-field-of-view imaging characteristics.

[0024] The preparation process of the organic-inorganic hybrid copper-based halide flexible film proposed by the present invention is green and simple, the conditions are mild and controllable, a large-area flexible film has been formed, the production cost is low, the repeatability is high, and it is easy to industrialize.

[0025] The organic-inorganic hybrid copper-based halide flexible film prepared by the present invention is applied to X-ray detection imaging, has the advantages of high X-ray responsivity, excellent stability and flexibility, etc., can significantly reduce the X-ray usage dose, improve the imaging resolution, and is expected to be used in commercial high-definition X-ray imaging screens. Description of the Drawings

[0026] Figure 1 XRD pattern of [(C3H7)4N]2Cu2I4 nanocrystals prepared in Example 2;

[0027] Figure 2 SEM image of [(C3H7)4N]2Cu2I4 nanocrystals prepared in Example 2;

[0028] Figure 3Excitation and emission spectra of the [(C3H7)4N]2Cu2I4 scintillator prepared in Example 2;

[0029] Figure 4 Response intensity curve of the [(C3H7)4N]2Cu2I4 scintillator prepared in Example 2 to X-rays with different dose rates;

[0030] Figure 5 Physical photos of the [(C3H7)4N]2Cu2I4 scintillator thin film prepared in Example 2 (a) under natural light and (b) under 310 nm ultraviolet light radiation;

[0031] Figure 6 X-ray imaging diagram of the [(C3H7)4N]2Cu2I4Cs3Cu2I5 scintillator prepared in Example 2 for circuit board lines, where (a) is a physical diagram of the circuit board and (b) is an X-ray imaging photo;

[0032] Figure 7 Resolution map of X-ray imaging of the [(C3H7)4N]2Cu2I4Cs3Cu2I5 scintillator prepared in Example 2 for circuit board lines. Detailed implementation mode

[0033] The present invention will be further described in detail below. The following is an explanation rather than a limitation of the present invention.

[0034] A preparation method of a perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging includes the following steps:

[0035] 1) High-purity tetrapropylammonium iodide ((C3H7)4N·I) and cuprous iodide (CuI) are successively added to a mixed solution of dimethylformamide (DMF) and hypophosphorous acid solution (H3PO2) with a mass fraction of 50 wt% to obtain A; wherein, the molar ratio of (C3H7)4N·I to CuI is 1:1, the volume ratio of DMF to H3PO2 is 20:1, and each 10 mL of the mixed solution of DMF and H3PO2 solution contains 6 - 12 mmol of the mixed powder of (C3H7)4N·I and CuI;

[0036] 2) A is heated by oil bath-ultrasound, and then filtered through a 0.22 μm filter head to obtain a transparent solution B; wherein, the oil bath temperature is 40 - 60 °C, the ultrasound frequency is 20 - 40 KHz, and the oil bath-ultrasound time is 5 - 15 min;

[0037] 3) Add polymethyl methacrylate (PMMA) to B, then transfer it to an induction heating-stirring kettle, add carbon spheres as the induction source, move the induction heating-stirring kettle into the induction heating-stirring equipment, and heat it from room temperature to 70-90 °C at an induction frequency of 300-500 KHz and keep it warm for 10-30 min, then take out the carbon spheres to obtain C; the addition amount of polymethyl methacrylate is in a ratio of 1 g: 3 mL to the dimethylformamide in step 1), and the stirring speed is 300-500 rpm;

[0038] 4) Clean the glass plate successively with water, ethanol, and acetone, dry it and place it on a coater;

[0039] 5) Transfer C onto the glass plate, quickly scrape the solution on the glass plate with a scraper, then heat and anneal the glass, and peel off the film after cooling to room temperature to obtain a perovskite-like scintillator film, wherein the height of the scraper is 400-600 μm, the scraping speed is 3 m / min, the annealing temperature is 50-70 °C, and the annealing time is 10-20 min.

[0040] The embodiments of the present invention will be described in detail below in conjunction with the examples. This embodiment is the preferred solution of the present invention and cannot limit the scope of the present invention. In the following examples, the methods and experimental equipment used are all conventional methods and instruments unless otherwise specified.

[0041] Example 1

[0042] 1. Add 1.6 mmol of high-purity (C3H7)4N·I and 1.6 mmol of CuI to 3 ml of DMF and 150 μl of a mixed solution of 50 wt% H3PO2 in sequence to obtain A;

[0043] 2. Heat A by oil bath-ultrasonic, the oil bath temperature is 40 °C, the ultrasonic frequency is 20 KHz, the oil bath-ultrasonic time is 5 min, and then filter it through a 0.22 μm filter head to obtain a transparent solution B;

[0044] 3. Add 1 g of PMMA to B, then transfer it to an induction heating-stirring kettle, add carbon spheres with a diameter of 2 cm as the induction source, move the induction heating-stirring kettle into the induction heating-stirring equipment, at a stirring speed of 300 rpm, heat it from room temperature to 70 °C at an induction frequency of 300 KHz, and keep it warm for 10 min, then take out the carbon spheres to obtain C;

[0045] 4. Clean the glass plate successively with water, ethanol, and acetone, dry it and place it on a coater;

[0046] 5. Transfer C onto a glass plate, quickly scrape and coat the solution on the glass plate with a scraper at a height of 400 μm at a speed of 3 m / min, then heat and anneal the glass at 50 °C for 10 min. After cooling to room temperature, peel off the film to obtain a perovskite-like scintillator film.

[0047] Example 2

[0048] 1. Sequentially add 1.8 mmol of high-purity (C3H7)4N·I and 1.8 mmol of CuI to a mixed solution of 3 ml of DMF and 150 μl of H3PO2 with a mass fraction of 50 wt% to obtain A;

[0049] 2. Heat A by oil bath-ultrasound, with the oil bath temperature at 50 °C, the ultrasound frequency at 30 KHz, and the oil bath-ultrasound time at 10 min. After filtering through a 0.22 μm filter head, obtain a transparent solution B;

[0050] 3. Add 1 g of PMMA to B, then transfer it to an induction heating-stirring kettle, add carbon spheres with a diameter of 2 cm as the induction source, move the induction heating-stirring kettle into the induction heating-stirring equipment, and heat from room temperature to 80 °C at an induction frequency of 400 KHz with a stirring speed of 400 rpm and keep it warm for 20 min. Then take out the carbon spheres to obtain C;

[0051] 4. Wash the glass plate successively with water, ethanol, and acetone, dry it, and place it on a coater;

[0052] 5. Transfer C onto the glass plate, quickly scrape and coat the solution on the glass plate with a scraper at a height of 500 μm at a speed of 3 m / min, then heat and anneal the glass at 60 °C for 15 min. After cooling to room temperature, peel off the film to obtain a perovskite-like scintillator film.

[0053] Example 3

[0054] 1. Sequentially add 2.2 mmol of high-purity (C3H7)4N·I and 2.2 mmol of CuI to a mixed solution of 6 ml of DMF and 300 μl of H3PO2 with a mass fraction of 50 wt% to obtain A;

[0055] 2. Heat A by oil bath-ultrasound, with the oil bath temperature at 60 °C, the ultrasound frequency at 40 KHz, and the oil bath-ultrasound time at 15 min. After filtering through a 0.22 μm filter head, obtain a transparent solution B;

[0056] 3. Add 2 g of PMMA to B, then transfer it to an induction heating-stirring kettle, and add carbon spheres with a diameter of 2 cm as the induction source. Move the induction heating-stirring kettle into the induction heating-stirring equipment. Under a stirring speed of 500 rpm, heat it from room temperature to 90 °C at an induction frequency of 500 kHz, and keep it warm for 30 min. Then take out the carbon spheres to obtain C;

[0057] 4. Clean the glass plate successively with water, ethanol, and acetone, and place it on the coater after drying;

[0058] 5. Transfer C onto the glass plate, and use a scraper with a height of 600 μm to quickly scrape the solution on the glass plate at a speed of 3 m / min. Then heat-anneal the glass at 70 °C for 20 min. After cooling to room temperature, peel off the film to obtain the perovskite-like scintillator film.

[0059] From Figure 1 the XRD pattern, it can be seen that the peaks of the sample in Example 2 correspond to the simulated XRD of [(C3H7)4N]2Cu2I4 single crystal and are relatively sharp, indicating that the purity and crystallinity of this sample are high. From Figure 2 the SEM image, it can be seen that the sample in Example 2 has a three-dimensional blocky morphology. From Figure 3 the excitation and emission spectra, it can be known that there is a large displacement difference between the absorption peak position and the emission peak position of the sample in Example 2, indicating that it has a large Stokes shift and can effectively avoid the self-absorption effect. At the same time, the sample in Example 2 has broadband spectral characteristics, indicating that its matching degree with the photoelectric sensor is high and it belongs to large field-of-view imaging. Figure 4 is the response intensity curve graph of the sample in Example 2 to X-rays with different dose rates. The detection limit of this sample is 53.34 nGy / s, which is much lower than the detection limits of Example 1 (72.61 nGy / s) and Example 3 (93.12 nGy / s), as well as the detection limit of the commercial scintillator (CsI(Tl)) (5.5 μGy / s). Figure 5 is the optical photo of the sample in Example 2 under 310 nm ultraviolet light irradiation. Figure 6 is the X-ray imaging graph of the sample in Example 2 for the circuit board. The image is clear and the imaging quality is high. Figure 7 is the resolution spectrum graph of the X-ray imaging of the circuit board lines by the sample in Example 2. Its resolution ability reaches 156.25 μm, and it has excellent ability to distinguish tiny details.

[0060] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. A preparation method of a perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging, characterized in that, It includes the following steps: 1) Add tetrapropylammonium iodide and cuprous iodide successively into the mixed solution of dimethylformamide and hypophosphorous acid solution to obtain A; wherein, the molar ratio of tetrapropylammonium iodide to cuprous iodide is 1:1, the volume ratio of dimethylformamide to hypophosphorous acid solution is 20:1, add 6 - 12 mmol of the mixed powder of tetrapropylammonium iodide and cuprous iodide into every 10 mL of the mixed solution of dimethylformamide and hypophosphorous acid solution, and the mass fraction of the hypophosphorous acid solution is 50 wt%; 2) Perform oil bath - ultrasonic heating on A, and then obtain a transparent solution B after filtration; 3) Add polymethyl methacrylate into the transparent solution B, then transfer it into an induction heating - stirring kettle, and add carbon spheres as the induction source. Move the induction heating - stirring kettle into the induction heating - stirring equipment, heat it from room temperature to 70 - 90 °C at an induction frequency of 300 - 500 KHz, and keep it warm for 10 - 30 min, then take out the carbon spheres to obtain C; the diameter of the carbon spheres is 2 cm, and the stirring speed is 300 - 500 rpm; 4) Transfer C onto the pretreated substrate, scrape - coat the solution on the substrate, then heat - anneal the substrate, and after cooling to room temperature, remove the film, thus obtaining a perovskite - like scintillator film for ultra - low - dose flexible X - ray imaging.

2. The preparation method of a perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging according to claim 1, characterized in that, In step 2), the oil bath temperature is 40 - 60 °C, the ultrasonic frequency is 20 - 40 KHz, and the oil bath - ultrasonic heating time is 5 - 15 min.

3. The preparation method of a perovskite-like scintillator film for ultra-low dose flexible X-ray imaging according to claim 1, characterized in that, In step 2), the filtration is carried out using a 0.22 μm filter head.

4. The preparation method of a perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging according to claim 1, characterized in that, In step 3), the addition amount of polymethyl methacrylate and the dimethylformamide in step 1) is in a ratio of 1 g:3 mL.

5. The preparation method of a perovskite-like scintillator film for ultra-low dose flexible X-ray imaging according to claim 1, characterized in that, In step 4), the substrate is a glass plate, and the pretreatment process is specifically: wash the glass plate successively with water, ethanol, and acetone, and then dry it.

6. The preparation method of a perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging according to claim 5, characterized in that, Step 5) is specifically: transfer C onto the glass plate, use a scraper to scrape - coat the solution on the glass plate, then heat - anneal the glass plate, and after cooling to room temperature, remove the film, wherein the height of the scraper is 400 - 600 μm, the scraping speed is 3 m / min, the annealing temperature is 50 - 70 °C, and the annealing time is 10 - 20 min.

7. A perovskite-like scintillator thin film for ultra-low dose flexible X-ray imaging, characterized in that, It is prepared by using the preparation method described in any one of claims 1 - 6.

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