An organic-inorganic hybrid lead halide scintillator and a preparation method and application thereof

Abstract

The application relates to the technical field of X-ray scintillator materials, in particular to an organic-inorganic hybrid lead halide scintillator as well as a preparation method and application thereof, the preparation method comprising the following steps: adding n-heptyltriphenylphosphonium bromide and lead bromide into a glass bottle, then adding N,N-dimethylformamide, heating and stirring until complete dissolution to obtain a precursor solution; placing the obtained precursor solution at room temperature until white block crystals appear at the bottom of the glass bottle; taking out the obtained crystals, washing with ultrapure water, and vacuum drying to obtain a scintillator. The scintillator prepared by the above steps has excellent thermal stability and has no obvious degradation below 305 DEG C; the linear response interval of the scintillator during X-ray imaging spans three orders of magnitude, meaning that the detection range of the scintillator is relatively wide, and the scintillator has great application potential in the field of X-ray imaging.

Description

Technical Field

[0001] This invention relates to the field of X-ray scintillator materials technology, and in particular to an organic-inorganic hybrid lead halide scintillator, its preparation method, and its application. Background Technology

[0002] X-ray detection technology is widely used in medical imaging, non-destructive testing, radiometric detection, geological exploration, and high-energy physics research. Traditional commercial scintillators, such as thallium-doped cesium iodide (CsI:Tl), thallium-doped sodium iodide (NaI:Tl), cerium-doped yttrium lutetium silicate (LYSO:Ce), bismuth germanate (BGO), and cadmium tungstate (CdWO4), possess advantages such as high X-ray absorption and strong radiative emission. However, these traditional scintillators typically have low luminous efficiency, slow response speed, and high manufacturing costs, making it difficult to meet the demands of high-resolution, rapid imaging applications. Furthermore, the need for technological upgrades has led to higher demands on scintillator performance. Therefore, developing scintillators with excellent overall performance and low manufacturing costs remains of significant research importance. Compared to structurally invariant all-inorganic materials, organic-inorganic hybrid perovskites exhibit greater diversity in crystal structure and size due to the large number of metal ions and multi-component organic amines. Summary of the Invention

[0003] The purpose of this invention is to provide an organic-inorganic hybrid lead halide scintillator, its preparation method, and its application. The prepared scintillator has excellent thermal stability and no significant degradation below 305℃. Its linear response range during X-ray imaging spans three orders of magnitude, which means that its detection range is relatively wide and it has great application potential in the field of X-ray imaging.

[0004] To achieve the above objectives, the present invention provides an organic-inorganic hybrid lead halide scintillator, the chemical formula of which is (C 25 H 30 P)2PbBr4.

[0005] The above-mentioned method for preparing an organic-inorganic hybrid lead halide scintillator includes the following steps: S1. Add n-heptyltriphenylphosphine bromide and lead bromide to a glass bottle, then add N,N-dimethylformamide, heat and stir until completely dissolved to obtain a precursor solution; S2. Let the precursor solution obtained in S1 stand at room temperature and evaporate the solvent until white blocky crystals appear at the bottom of the glass bottle. S3. After removing the crystal obtained in S2, wash it with ultrapure water and dry it under vacuum to obtain a scintillator.

[0006] Preferably, in S1, the molar ratio of n-heptyltriphenylphosphine bromide to lead bromide is 2:1.

[0007] Preferably, in S1, the heating and stirring temperature is 50-70℃, and the heating and stirring time is 20-40 minutes.

[0008] Preferably, in S1, the concentration of the precursor solution is 3-4 g / mL.

[0009] Preferably, in S2, the standing time at room temperature is 20-30 hours.

[0010] Preferably, in step S3, the ultrapure water washing is performed 2-3 times, and the vacuum drying time is not less than 2 hours.

[0011] An application of an organic-inorganic hybrid lead halide scintillator in the preparation of flexible scintillator films for X-ray imaging.

[0012] Preferably, the preparation of the scintillator flexible thin film includes the following steps: T1. Mix the scintillator powder, thermoplastic polyurethane elastomer and N,N-dimethylformamide and stir until homogeneous to obtain a mixed solution; T2. Pour the mixed solution obtained in T1 into a mold, vacuum for 20-50 minutes to remove air bubbles, and anneal at 70-90℃ for 50-70 hours to obtain a scintillator flexible film.

[0013] Preferably, in T1, the mass ratio of scintillator powder to thermoplastic polyurethane elastomer is 1:1-2.

[0014] Therefore, the present invention employs the above-mentioned organic-inorganic hybrid lead halide scintillator, its preparation method, and its application, and its beneficial effects are as follows: 1. The preparation method provided by this invention is simple to operate, belongs to the exciton luminescence mechanism, and achieves a fluorescence quantum yield of 30% and a fluorescence lifetime of 90.0 ns; 2. The scintillator prepared by this invention exhibits excellent thermal stability, showing no significant degradation below 305℃, and achieving a photon yield of up to 67,500 photons MeV in X-ray imaging. -1 Its linear response range spans three orders of magnitude, which means that its detection range is relatively wide and it has great application potential in the field of X-ray imaging. 3. The scintillator flexible thin film prepared by this invention can achieve flexible imaging under X-rays.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the crystal structure of the lead halide scintillator in Embodiment 1 of the present invention; Figure 2These are the theoretical and actual XRD spectra of the lead halide scintillator in Embodiment 1 of the present invention; Figure 3 These are the photoexcitation and photoemission spectra of the lead halide scintillator in Embodiment 1 of the present invention; Figure 4 This is the transient photoemission spectrum and fitted fluorescence lifetime diagram of the lead halide scintillator in Example 1 of the present invention; Figure 5 This is a temperature-dependent emission spectrum combination diagram of the lead halide scintillator in Embodiment 1 of the present invention, wherein, Figure 5 (a) in the image is a pseudo-color image. Figure 5 (b) in the figure is the fitted exciton activation energy diagram; Figure 6 This is the fluorescence quantum yield spectrum of the lead halide scintillator in Example 1 of the present invention; Figure 7 This is a thermal analysis curve of the lead halide scintillator in Embodiment 1 of the present invention; Figure 8 This is a graph showing the fitted curves of the radiative emission intensity of the lead halide scintillator under different X-ray dose rates in Embodiment 1 of the present invention. Figure 9 This is a combination diagram of whether or not the flexible lead halide scintillator film in Embodiment 1 of the present invention is irradiated with ultraviolet light, wherein, Figure 9 Image (a) in the image is a physical photograph of a flexible thin film of a lead halide scintillator. Figure 9 (b) in the figure shows the luminescence of the flexible lead halide scintillator film under ultraviolet light irradiation; Figure 10 These are photographs of the test object and the image taken during X-ray imaging of the lead halide scintillator flexible thin film in Embodiment 1 of the present invention. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0018] In some embodiments of the present invention, an organic-inorganic hybrid lead halide scintillator is provided, the chemical formula of which is (C 25 H 30 P)2PbBr4.

[0019] This invention provides a method for preparing an organic-inorganic hybrid lead halide scintillator, comprising the following steps: S1, n-Heptyltriphenylphosphine bromide C 25 H 30PBr and lead bromide PbBr2 were added to a glass bottle, followed by N,N-dimethylformamide DMF. The mixture was heated and stirred until completely dissolved to obtain a precursor solution. S2. Let the precursor solution obtained in S1 stand at room temperature and evaporate the solvent until white blocky crystals appear at the bottom of the glass bottle. S3. After removing the crystal obtained in S2, wash it with ultrapure water and dry it under vacuum to obtain a scintillator.

[0020] In some embodiments of the present invention, in S1, the molar ratio of n-heptyltriphenylphosphine bromide to lead bromide is 2:1. As a bulky organic cation, the molar ratio of n-heptyltriphenylphosphine to lead bromide strictly determines the formation of the low-dimensional structure; a ratio of 2:1 ensures the formation of isolated (PbBr4). 2- It has a tetrahedral structure and is surrounded by organic cations.

[0021] In some embodiments of the present invention, in step S1, the heating and stirring temperature is 50-70°C, and the heating and stirring time is 20-40 minutes. At this heating temperature, the dissolution of n-heptyltriphenylphosphine bromide and lead bromide by DMF can be accelerated, while avoiding excessively rapid volatilization of DMF or the formation of unknown complexes due to high temperatures. As a strongly polar aprotic solvent, DMF can effectively dissociate lead bromide and stabilize precursor ions.

[0022] In some embodiments of the present invention, in S1, the concentration of the precursor solution is 3-4 g / mL, which is intended to approximate saturation solubility.

[0023] In some embodiments of the present invention, in step S2, the standing time at room temperature is 20-30 hours. Utilizing the natural evaporation of the DMF solvent, the precursor solution slowly reaches a supersaturated state. The slow evaporation rate promotes the ordered arrangement of ions, forming pure-phase bulk crystals with few defects and high crystallinity. This process facilitates the formation of large-sized (C) crystals. 25 H 30 P) + Effective cation isolation (PbBr4) 2- Anionic group.

[0024] In some embodiments of the present invention, in step S3, the ultrapure water washing is performed 2-3 times, and the vacuum drying time is not less than 2 hours. Ultrapure water washing removes residual DMF solvent and unreacted precursor salts from the crystal surface. Vacuum drying thoroughly removes adsorbed moisture and trace amounts of solvent.

[0025] In some embodiments of the present invention, an organic-inorganic hybrid lead halide scintillator is applied to the preparation of a flexible scintillator film for X-ray imaging.

[0026] In some embodiments of the present invention, the preparation of the scintillator flexible thin film includes the following steps: T1. The scintillator powder, thermoplastic polyurethane elastomer, and N,N-dimethylformamide are mixed and stirred evenly to obtain a mixed solution. The thermoplastic polyurethane elastomer (TPU) acts as a flexible polymer, serving as a dispersion medium and binder, uniformly encapsulating the scintillator nanocrystals to achieve flexible imaging.

[0027] T2. Pour the mixed solution obtained in T1 into a mold, vacuum for 20-50 minutes to remove air bubbles, and anneal at 70-90℃ for 50-70 hours to obtain a flexible scintillator film. Air microbubbles are introduced during slurry mixing; in X-ray imaging, these bubbles can interfere with image quality. Vacuuming removes these bubbles to ensure the flexible scintillator film is dense and uniform. Slow evaporation of DMF prevents the formation of pores within the flexible scintillator film. Prolonged annealing allows the TPU molecular chains to fully extend and form good interfacial contact with the scintillator particles, eliminating internal stress.

[0028] In some embodiments of the present invention, in T1, the mass ratio of scintillator powder to thermoplastic polyurethane elastomer is 1:1-2.

[0029] Example 1 A method for preparing an organic-inorganic hybrid lead halide scintillator includes the following steps: S1. Add n-heptyltriphenylphosphine bromide and lead bromide in a molar ratio of 2:1 to a glass bottle, then add N,N-dimethylformamide, heat and stir at 60°C for 30 min until completely dissolved to obtain a precursor solution with a concentration of 3.676 g / mL.

[0030] S2. Let the precursor solution obtained in S1 stand at room temperature for 24 hours, and evaporate the solvent until white blocky crystals appear at the bottom of the glass bottle.

[0031] S3. After removing the crystal obtained in S2, wash it 2-3 times with ultrapure water, and then vacuum dry it for at least 2 hours to obtain the scintillator (C). 25 H 30 P)2PbBr4, crystal structure as follows Figure 1 As shown in the figure, (PbBr4) 2- By (C) 25 H 30 P) + Surrounded by organic groups.

[0032] Example 2 The method for preparing a flexible scintillator thin film includes the following steps: T1, a scintillator (C) with a mass ratio of 1:1.6. 25 H 30P)2PbBr4 powder and thermoplastic polyurethane elastomer (TPU) were added to N,N-dimethylformamide and stirred until homogeneous to obtain a mixed solution with a concentration of 0.325 g / mL.

[0033] T2. Pour the mixed solution obtained in T1 into a mold, vacuum for 30 minutes to remove air bubbles from the mixed solution, and anneal at 80°C for 60 hours to obtain a scintillator flexible film (C). 25 H 30 P)2PbBr4-TPU.

[0034] Performance testing a. Regarding the scintillator (C) in Example 1 25 H 30 XRD analysis was performed on P)2PbBr4, and the results are as follows: Figure 2 As shown, the calculated single-crystal X-ray diffraction data are consistent with the XRD peak positions obtained from the X-RD test experiment, indicating that the prepared scintillator (C0.05) has the desired effect. 25 H 30 P)2PbBr4 is the pure phase.

[0035] The scintillator (C) in Example 1 25 H 30 The photoexcitation spectrum (PLE) and photoemission spectrum (PL) of P)2PbBr4 are as follows: Figure 3 As shown, the absorption peak of the scintillator is located at 400 nm, and the emission peak is located at 430 nm.

[0036] In Example 1 (C) 25 H 30 The transient photoemission spectrum (TRPL) of P)2PbBr4, such as Figure 4 As shown, the fluorescence lifetime obtained after exponential fitting is 90 ns.

[0037] The scintillator (C) in Example 1 25 H 30 The pseudo-color image of the temperature-dependent fluorescence emission spectrum of P)2PbBr4, such as Figure 5 As shown, it can be seen that the luminescence intensity decreases with increasing temperature in the range of 180-380K. Figure 5 In the figure, (b) represents the exciton activation energy Ea, fitted based on the relationship between the integral of fluorescence intensity and temperature. 25 H 30 The Ea obtained from fitting P)2PbBr4 is 327.38 meV, which is a relatively large exciton activation energy and high exciton stability, indicating that thermal quenching at room temperature can be ignored.

[0038] The scintillator (C) in Example 1 25 H 30Fluorescence quantum yield (PLQY) plots of P)2PbBr4 and blank reference, as shown Figure 6 As shown, the PLQY of this scintillator can reach 30%, indicating that its photoluminescence is relatively strong.

[0039] The scintillator (C) in Example 1 25 H 30 Thermal analysis curve of P)2PbBr4, such as Figure 7 As shown, the data includes thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) curves. (From...) Figure 7 It can be seen that the scintillator has good thermal stability and does not show significant degradation below 305℃.

[0040] The scintillator (C) in Example 1 25 H 30 Fitting curves of radiative luminescence intensity (RL) of P)2PbBr4 at different X-ray dose rates, as shown in... Figure 8 As shown. By Figure 8 It can be seen that the linear response range of this scintillator during X-ray imaging spans three orders of magnitude, indicating that its detection range is relatively wide.

[0041] b. The scintillator flexible film in Example 2 (C) 25 H 30 Physical images of P)2PbBr4-TPU and photos of its luminescence under UV light, such as... Figure 9 As shown, by Figure 9 It can be seen that the actual scintillator flexible film is white under natural light, but emits a uniform and bright blue light under ultraviolet light.

[0042] The scintillator flexible film in Example 2 (C 25 H 30 Physical photographs and imaging images of P)2PbBr4-TPU under X-ray imaging, such as Figure 10 As shown, a plastic capsule containing a metal spring and a crab specimen were placed between an X-ray source and a scintillator film, respectively. It can be seen that the metal spring inside the capsule and the skeletal structure of the crab specimen can be clearly observed under X-rays using the flexible scintillator film, indicating that it has good imaging capabilities.

[0043] Therefore, the present invention employs the above-mentioned organic-inorganic hybrid lead halide scintillator, its preparation method and application. The scintillator prepared has excellent thermal stability and no obvious degradation below 305℃. Its linear response range during X-ray imaging spans three orders of magnitude, which means that its detection range is relatively wide and it has great application potential in the field of X-ray imaging.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An organic-inorganic hybrid lead halide scintillator, characterized in that: The chemical formula of the scintillator is (C 25 H 30 P)2PbBr4.

2. A method for preparing an organic-inorganic hybrid lead halide scintillator, characterized in that: The preparation of the scintillator as described in claim 1 comprises the following steps: S1. Add n-heptyltriphenylphosphine bromide and lead bromide to a glass bottle, then add N,N-dimethylformamide, heat and stir until completely dissolved to obtain a precursor solution; S2. Let the precursor solution obtained in S1 stand at room temperature and evaporate the solvent until white blocky crystals appear at the bottom of the glass bottle. S3. After removing the crystal obtained in S2, wash it with ultrapure water and dry it under vacuum to obtain the scintillator.

3. The method for preparing an organic-inorganic hybrid lead halide scintillator according to claim 2, characterized in that: In S1, the molar ratio of n-heptyltriphenylphosphine bromide to lead bromide is 2:

1.

4. The method for preparing an organic-inorganic hybrid lead halide scintillator according to claim 2, characterized in that: In S1, the heating and stirring temperature is 50-70℃, and the heating and stirring time is 20-40 minutes.

5. The method for preparing an organic-inorganic hybrid lead halide scintillator according to claim 2, characterized in that: In S1, the concentration of the precursor solution is 3-4 g / mL.

6. The method for preparing an organic-inorganic hybrid lead halide scintillator according to claim 2, characterized in that: In S2, the standing time at room temperature is 20-30 hours.

7. The method for preparing an organic-inorganic hybrid lead halide scintillator according to claim 2, characterized in that: In S3, the ultrapure water washing is performed 2-3 times, and the vacuum drying time is no less than 2 hours.

8. An application of an organic-inorganic hybrid lead halide scintillator, characterized in that: The scintillator as described in claim 1 is used in the preparation of a flexible scintillator film for X-ray imaging.

9. The application of the organic-inorganic hybrid lead halide scintillator according to claim 8, characterized in that: The preparation of a scintillator flexible thin film includes the following steps: T1. Mix the scintillator powder, thermoplastic polyurethane elastomer and N,N-dimethylformamide and stir until homogeneous to obtain a mixed solution; T2. Pour the mixed solution obtained in T1 into a mold, vacuum for 20-50 minutes to remove air bubbles, and anneal at 70-90℃ for 50-70 hours to obtain a scintillator flexible film.

10. The application of the organic-inorganic hybrid lead halide scintillator according to claim 9, characterized in that: In T1, the mass ratio of scintillator powder to thermoplastic polyurethane elastomer is 1:1-2.

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