Method for preparing pixelated scintillator film
By combining in-situ growth and picosecond laser etching, pixelated structures can be directly constructed in scintillator films, solving the problems of complex preparation processes and material toxicity in existing technologies, and realizing efficient and low-cost preparation of large-area pixelated scintillator films.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-06
- Publication Date
- 2026-04-07
AI Technical Summary
Existing methods for preparing pixelated scintillators rely on templates or microporous carriers, which involve complex processes, make it difficult to achieve large-area continuous preparation, and traditional materials have limitations due to their toxicity.
By growing scintillator films in situ and forming pixelated structures using picosecond laser etching, the introduction of templates or microporous carriers is avoided. Total internal reflection of the air layer is used to suppress optical crosstalk, and Cu-based or Mn-based halide scintillator materials are employed.
It has achieved the fabrication of large-area pixelated scintillator thin films with simple process and low cost. The materials have no toxicity restrictions, and the size and spacing of the pixel units can be controlled, making it suitable for mass production.
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Figure CN121815779A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of radiation detection imaging, and relates to a method for preparing a pixelated scintillator film. BACKGROUND
[0002] The scintillator-based radiation detection imaging technology has been widely applied in the fields of medical imaging, security detection, industrial non-destructive testing and scientific research due to its high sensitivity and non-destructive detection advantages. With the increasing requirements of imaging systems on spatial resolution and signal-to-noise ratio, the traditional continuous scintillator is prone to light scattering when the thickness increases, which leads to the decline of imaging resolution and makes it difficult to meet the demand of high-precision imaging.
[0003] Studies have shown that by constructing a pixelated scintillator structure, an optical isolation interface is formed between the pixel units, which can effectively suppress the lateral crosstalk of photons, thereby improving the spatial resolution of the scintillator. The related preparation method has become a research hotspot in the field of radiation detection imaging. The existing technologies mainly include two categories: one is the template / micropore limited growth method, such as the preparation of perovskite scintillator array by Zhang et al. (ACS Applied Nano Materials (2022) 5:881-889), which uses the channel structure of AAO to suppress the light crosstalk between pixels. However, the porosity of AAO template is limited, the thickness is limited, the mechanical strength is low and fragile, the template processing is complex, and large-area thick film cannot be prepared on a large scale; the other is the pixel filling method of low refractive index material or micropore filling method, such as the filling of low refractive index material in CsI:Tl pixels by Hormozan et al. (Med. Phys. (2016) 43:696-701). This kind of method usually involves deep reactive ion etching, material filling and high-temperature treatment, and the preparation process is complex, and the thallium element contained in CsI:Tl material has a certain toxicity, which limits its further application.
[0004] In summary, the existing pixelated scintillator preparation methods generally have the problems of dependence on templates or micropore carriers, complex preparation process, and difficulty in realizing large-area continuous preparation, and there is an urgent need for a new pixelated scintillator film preparation method with simple process, controllable structure and suitable for large-scale preparation. SUMMARY
[0005] To achieve the above-mentioned purpose, the present application provides a method for preparing a pixelated scintillator film, which comprises the following technical means:
[0006] First, a scintillator thin film is directly prepared on a substrate by in-situ growth. The in-situ growth includes uniformly coating a scintillator precursor solution on a surface of the substrate by a doctor blade method or a spin coating method, and obtaining a continuous and dense scintillator thin film through annealing treatment, thereby avoiding the limitation of a traditional template or a micro-porous structure on the thickness and structural integrity of the thin film.
[0007] Subsequently, the in-situ grown scintillator thin film is subjected to selective etching treatment by a picosecond laser, local film material is ablated and vaporized by the action of a laser with a high energy density, and an air layer for pixel isolation is formed in-situ inside the thin film, so that a pixelated scintillator structure is constructed without introducing additional templates or isolation materials.
[0008] Due to the large refractive index difference between the formed air isolation layer and the scintillator material, a total internal reflection effect can be generated at the pixel unit and air interface, thereby effectively suppressing the lateral crosstalk of photons and improving the spatial resolution performance of the scintillator thin film.
[0009] The technical scheme of the present application is as follows:
[0010] A method for preparing a pixelated scintillator thin film, comprising the following steps:
[0011] (1) A continuous scintillator layer is prepared on a substrate by in-situ growth, and the scintillator layer is a Cu-based halide scintillator or a Mn-based halide scintillator;
[0012] (2) Selective etching treatment is performed on the in-situ grown scintillator layer by a picosecond laser, so that the scintillator layer in the etched region is ablated and vaporized, an air layer for pixel isolation is formed in-situ inside the scintillator layer, and the scintillator layer is divided into a plurality of independent pixel units, thereby obtaining a pixelated scintillator thin film.
[0013] The refractive index difference between the air layer formed by the picosecond laser etching and the scintillator material introduces a total internal reflection mechanism at the pixel unit interface, which is used to suppress the optical lateral crosstalk between the pixel units.
[0014] The pixelated scintillator thin film comprises a scintillator layer and a substrate;
[0015] The scintillator layer is a scintillator array structure left after laser etching treatment;
[0016] The substrate is one of a single crystal silicon substrate, a quartz glass substrate, a borosilicate glass substrate, and a soda-lime glass substrate.
[0017] The in-situ growth method comprises the following steps:
[0018] (1) adding the scintillator raw material and the binder into a solvent, and stirring magnetically at a temperature of 80-140℃ and a stirring speed of 500-1500 rpm until the solution is transparent to prepare a scintillator precursor solution;
[0019] (2) pretreating the substrate, ultrasonically treating the substrate with acetone, ethanol and deionized water respectively, drying, and then treating with an oxygen plasma cleaning machine;
[0020] (3) using a doctor blade method or a spin coating method to apply the scintillator precursor solution on the substrate;
[0021] (4) annealing the substrate after the application of step (3) on a hot plate or in a drying oven to obtain a scintillator thin film.
[0022] The binder is polyvinylidene fluoride and / or polymethyl methacrylate, and the addition ratio of the binder to the solvent is 0.2-0.3 g / ml;
[0023] The scintillator raw material is selected from a combination of a metal halide and an organic ligand or an organic cation source, wherein the metal halide includes but is not limited to cuprous iodide, cesium iodide, manganese bromide, the organic ligand or the organic cation source includes but is not limited to triphenylphosphonium bromide, tetrabutylammonium iodide, and the mass ratio of the scintillator raw material to the binder is 0.5:1-2.5:1.
[0024] The doctor blade method is to drop the scintillator precursor solution on the substrate with a pipette, then evenly disperse the scintillator precursor solution on the substrate with a doctor blade, and obtain a scintillator thin film through annealing treatment.
[0025] The spin coating method is to drop the scintillator precursor solution on a rotating substrate with a pipette, the rotation speed is 800-3000 rpm, and the time is 10-60 s, the centrifugal force generated by the rotation is used to evenly disperse the scintillator precursor solution dropped on the surface of the perovskite precursor solution, and a scintillator thin film is obtained through annealing treatment.
[0026] The solvent is one or a mixture of two or more of dimethylacetamide, N-N dimethylformamide, N-methylpyrrolidone, ethyl acetate, and dimethyl sulfoxide.
[0027] The annealing treatment is to place the scintillator thin film and the substrate after the doctor blade or spin coating on a hot plate with a temperature of 75-120℃ for a duration of 6-48 h to ensure that the solvent is evaporated and the perovskite material is completely crystallized, and then slowly cool to room temperature.
[0028] The picosecond laser is generated by a picosecond pulse laser, the wavelength of the laser is 355 nm, the pulse width is 7-10 ps, the spot diameter is 7 μm, and the spot area is 38.465×10-8 cm 2 , energy density is 1.3-26 J / cm -2 .
[0029] The pixelated pattern is a discrete independent pixel unit pattern, wherein the pixel unit is a square, a rectangle, a rhombus or a circle, the size a of each pixel unit is 20-200 μm, and the interval b between each pixel unit is 7-50 μm.
[0030] The present application has the following beneficial effects:
[0031] (1) The present application directly prepares a scintillator thin film by in-situ growth, and combines with picosecond laser etching to form a pixelated structure, without introducing a template, a microporous carrier or a filling isolation material, thereby avoiding the problems of fragile structure and limited porosity in the prior art;
[0032] (2) The pixelated structure is directly formed in the thin film by laser processing, the pixel unit size and the interval can be accurately controlled by laser parameters, the structure is strong in discrete nature and good in repeatability;
[0033] (3) The scintillator material system used in the present application is a Cu-based or Mn-based halide, which avoids the toxicity limitation of traditional lead-containing or thallium-containing scintillator materials, and widens the application range of the materials;
[0034] (4) The entire preparation process only includes solution coating, annealing and laser etching steps, which is simple in process, low in cost, and suitable for large-area continuous preparation and large-scale production. BRIEF DESCRIPTION OF DRAWINGS
[0035] Figure 1 is a schematic diagram of the method for preparing a pixelated scintillator thin film of the present application;
[0036] Figure 2 is an optical micrograph of a pixelated (C 25 H 22 P)2MnBr4 NC @PVDF thin film prepared in Example 1;
[0037] Figure 3 is an optical micrograph of a pixelated [(C3H7)4N]2Cu2I4 NC @PVDF thin film prepared in Example 2;
[0038] Figure 4 is an optical micrograph of a pixelated CsCu2I3@PVDF thin film prepared in Example 3;
[0039] Figure 5 is an optical micrograph of a pixelated Cs3Cu2I5@PMMA thin film prepared in Example 4. DETAILED DESCRIPTION
[0040] The specific embodiments of the present application are further illustrated in the following with reference to the accompanying drawings and technical solutions.
[0041] The method described in the present application is used to prepare a pixelated scintillator thin film for radiation detection. Figure 1 The specific embodiments of the method are shown. In general, the scintillator thin film is prepared by in-situ growth, doctor blade method, spin coating method, and then the thin film is laser scanned and etched to produce a plurality of independent scintillator pixel units, and the pixelated thin film is composed of these pixel units. The shape, side length a of the pixel unit and the pitch b of the pixel unit can be set autonomously by drawing a pattern, and the specific embodiments of the present application are further illustrated in the following with reference to the accompanying drawings and technical solutions.
[0042] Example 1: Preparation of pixelated BTP2MnBr4 NC thin film
[0043] Preparation of precursor solution: 10 mmol C 25 H 22 BrP, 5 mmol MnBr2 and 3 g PVDF powder were directly mixed in 10 ml DMF solvent and magnetically stirred at 140 ℃ until completely dissolved into a transparent solution.
[0044] Pre-treatment of substrate: first, the substrate was ultrasonically treated with acetone, ethanol and deionized water for 15 minutes respectively, then placed in an oven with a constant temperature of 85 ℃ for drying, treated with an oxygen plasma cleaning machine for 15 min, and the treated substrate was preheated on a heating plate at 120 ℃ for standby.
[0045] Preparation of BTP2MnBr4 NC @PVDF thin film: 2 ml of precursor solution was taken with a straw and dropped on the substrate, the solution was uniformly dispersed on the substrate with a doctor blade, annealed on a heating plate at 120 ℃ for 24 h, then slowly cooled to room temperature to obtain a BTP2MnBr4 NC @PVDF thin film.
[0046] Preparation of pixelated structure: the BTP2MnBr4 NC @PVDF thin film with the substrate was placed on a three-dimensional precision machining table, a picosecond laser with a wavelength of 355 nm, a pulse width of 7 ps and an energy density of 26 J / cm -2 was selected, the three-dimensional translation table control program was written according to the array pattern to be processed, and the picosecond laser was used to produce tiny pixel units on the surface of the thin film, thereby obtaining the required pixelated structure.
[0047] Figure 2 The pixelated (C 25 H 22P) Optical micrograph of 2MnBr4NC@PVDF scintillator thin film. The image was taken by Figure 2 It can be seen that by picosecond laser etching treatment on the in-situ grown continuous scintillator thin film, the thin film is divided into a plurality of square pixel units independent of each other, the boundaries of each pixel unit are clear and arranged in an orderly manner, and an obvious isolation region is formed between the pixel units. The isolation region is composed of an air layer formed in-situ after the ablation and vaporization of the scintillator material in the laser etching process, without introducing any template or filling material, thereby avoiding the problems of low porosity and fragile structure in the traditional template method. The pixel unit size and spacing are uniform and consistent, indicating that the method has good structure controllability and repeatability.
[0048] Example 2: Preparation of [(C3H7)4N]2Cu2I4 NC@PVDF thin film
[0049] Preparation of precursor solution: 5 mmol of CuI, 5 mmol of C 12 H 28 IN and 1.2 g of PVDF powder were directly mixed in 5 ml of DMF solvent and magnetically stirred at 100°C until completely dissolved into a transparent solution.
[0050] Pre-treatment of substrate: first, the substrate was ultrasonically treated with acetone, ethanol and deionized water for 15 minutes respectively, then placed in an oven with a constant temperature of 85°C for drying, treated with an oxygen plasma cleaning machine for 15 min, and the treated substrate was preheated on a heating plate at 120°C for standby.
[0051] Preparation of [(C3H7)4N]2Cu2I4 NC@PVDF thin film: 1 ml of precursor solution was taken with a straw and dropped on the substrate, and the solution was uniformly dispersed on the substrate with a scraper, and then annealed on a heating plate at 120°C for 12 h, and then slowly cooled to room temperature to obtain the [(C3H7)4N]2Cu2I4 NC@PVDF thin film.
[0052] Preparation of pixelated structure: the [(C3H7)4N]2Cu2I4@PVDF thin film with the substrate was placed on a three-dimensional precision machining table, a picosecond laser with a wavelength of 355 nm, a pulse width of 7 ps and an energy density of 6.5 J / cm -2 was selected, the three-dimensional translation table control program was written according to the processed array pattern, and the picosecond laser generated micro pixel units on the surface of the thin film, thereby obtaining the required pixelated structure.
[0053] Figure 3Optical micrograph of the pixelated [(C3H7)4N]2Cu2I2NC@PVDF scintillator film prepared in Example 2. As shown, different shaped pixel units can be formed in the in-situ grown scintillator film after picosecond laser etching, and the separation between the pixel units is clear and not connected, indicating that the method of the present application is not limited by the shape of the pixel, and has good flexibility in structure design.
[0054] The results further demonstrate that the present application directly forms an air isolation layer inside the film by laser etching, which can achieve pixel isolation without relying on a microporous template or a low refractive index filling material, thereby simplifying the preparation process and overcoming the complex process problem of the existing CsI:Tl filling method.
[0055] Example 3: Preparation of a pixelated CsCu2I3@PVDF film
[0056] Preparation of the precursor solution: 8 mmol of Cul, 8 mmol of Csl, 6 g of PVDF and 100 ml of H3PO2 were directly mixed in 20 ml of DMF solvent, and magnetically stirred at 80°C for 5 h until the solution was clear.
[0057] Pre-treatment of the substrate: First, the substrate was ultrasonically treated with acetone, ethanol and deionized water for 15 minutes respectively, then placed in an oven with a constant temperature of 85°C for drying, and treated with an oxygen plasma cleaning machine for 15 min.
[0058] Preparation of the CsCu2I3@PVDF film: 1 ml of the precursor solution was taken with a straw and dropped on the substrate, and the solution was evenly dispersed on the substrate with a spatula. The film was annealed on a heating plate at 75°C for 6 h, and then slowly cooled to room temperature to obtain the CsCu2I3@PVDF film.
[0059] Preparation of the pixelated structure: The CsCu2I3@PVDF film with the substrate was placed on a three-dimensional precision machining table, a picosecond laser with a wavelength of 355 nm, a pulse width of 7 ps and an energy density of 4.3 J / cm -2 was selected, and the three-dimensional translation table control program was written according to the array pattern to be processed, so that the picosecond laser produced micro pixel units on the surface of the film, thereby obtaining the desired pixelated structure.
[0060] Figure 4 Optical micrograph of the pixelated CsCu2I3@PVDF scintillator film prepared in Example 3. As can be seen from Figure 4 , the pixel units are regularly arranged, the edges are complete, and the isolation region between the pixel units is continuous and uniform in width, indicating that the picosecond laser etching has good consistency in processing the in-situ grown scintillator film.
[0061] This embodiment shows that the method of the present application is not only suitable for organic-inorganic hybrid systems, but also for all-inorganic Cu-based halide scintillator thin films, and can achieve pixelated structure without the aid of templates or microporous glass plates, which is beneficial to expand the selection range of material systems and realize large-area preparation.
[0062] Example 4: Pixelated Cs3Cu2I5@PMMA thin film
[0063] Preparation of precursor solution: 8 mmol of Cul, 12 mmol of Csl, 4 g of PMMA and 100 ml of H3PO2 were directly mixed in 20 ml of DMF solvent, and after magnetic stirring at 80°C for 5 h, the solution was used as the precursor solution.
[0064] Pre-treatment of substrate: First, the substrate was ultrasonically treated with acetone, ethanol and deionized water for 15 minutes, respectively, and then placed in an oven with a constant temperature of 85°C for drying, and treated with an oxygen plasma cleaning machine for 15 min.
[0065] Preparation of Cs3Cu2I5@PMMA thin film: First, the treated quartz glass substrate was vacuum adsorbed on the spin coater, 2 ml of the precursor solution was dropped on the center of the substrate with a pipette, and then rotated at a speed of 3000 rpm for 30 seconds. After spin coating, it was placed on a heating plate at 75°C for annealing for 6 h to obtain the Cs3Cu2I5@PMMA thin film.
[0066] Preparation of pixelated structure: The Cs3Cu2I5@PMMA thin film with the substrate was placed on a three-dimensional precision machining table, a picosecond laser with a wavelength of 355 nm, a pulse width of 7 ps and an energy density of 8.67 J / cm -2 was selected, and the three-dimensional translation table control program was written according to the array pattern to be processed, so that the picosecond laser generated a small pixel unit on the surface of the thin film, thereby obtaining the required pixelated structure.
[0067] Figure 5 Optical micrograph of the pixelated Cs3Cu2I5@PMMA scintillator thin film prepared in Example 4. It can be seen that even under different adhesive system (PMMA) and different substrate conditions, the pixelated structure with clear boundaries and good separation can be obtained by the method of the present application, and the pixel unit morphology remains stable. Figure 5
[0068] The results show that the method of "in-situ growth of thin film-picosecond laser etching" proposed by the present application has good material system compatibility and process stability, further verifying the feasibility of realizing large-scale continuous preparation in practical application.
[0069] In summary, the results of Examples 1-4 show that the present application can directly construct a pixelated structure in a continuous scintillator film by combining in-situ growth of thin films with picosecond laser etching, without introducing a template, a microporous carrier or a filling isolation material. The air isolation layer formed effectively suppresses optical cross-talk between pixels, and the method has good adaptability to material systems, binder types and pixel shapes, thereby overcoming the defects of existing pixelated scintillator preparation methods, such as fragile structure, complex process and difficulty in achieving large-area preparation.
Claims
1. A method for preparing a pixelated scintillator thin film, characterized in that, Includes the following steps: (1) A continuous scintillator layer is prepared on a substrate by in-situ growth, wherein the scintillator layer is a Cu-based halide scintillator or a Mn-based halide scintillator; (2) On the scintillator layer obtained by in-situ growth, a picosecond laser is used for selective etching to ablate and vaporize the scintillator layer in the etched area, and an air layer for pixel isolation is formed in-situ inside the scintillator layer, thereby dividing the scintillator layer into multiple independent pixel units to obtain a pixelated scintillator film.
2. The method according to claim 1, characterized in that, The pixelated scintillator film includes a scintillator layer and a substrate; The scintillator layer is a scintillator array structure left after laser etching. The substrate is one of the following: a single-crystal silicon substrate, a quartz glass substrate, a borosilicate glass substrate, or a soda-lime glass substrate.
3. The method according to claim 1, characterized in that, The in-situ growth method includes the following steps: (1) Add the scintillator raw material and binder to the solvent, and magnetically stir at a temperature of 80-140℃ and a stirring speed of 500-1500 rpm until the solution is transparent to prepare the scintillator precursor solution. (2) The substrate was pretreated by ultrasonic treatment with acetone, ethanol and deionized water respectively, dried and then treated with oxygen plasma cleaning machine. (3) Apply the scintillator precursor solution onto the substrate using a scraping or spin coating method; (4) Anneal the substrate coated in step (3) on a heating plate or in a drying oven to obtain a scintillator film.
4. The method according to claim 3, characterized in that, The binder is polyvinylidene fluoride and / or polymethyl methacrylate, and its addition ratio to the solvent is 0.2-0.3 g / ml; The scintillator raw material is selected from a combination of metal halides and organic ligands or organic cation sources, wherein the metal halides include, but are not limited to, cuprous iodide, cesium iodide, and manganese bromide, and the organic ligands or organic cation sources include, but are not limited to, triphenylphosphine bromide and tetrabutylammonium iodide. The mass ratio of the scintillator raw material to the binder is 0.5:1 to 2.5:
1.
5. The method according to claim 3, characterized in that, The aforementioned scraping method involves using a pipette to draw up a scintillator precursor solution and drop it onto a substrate, then using a scraper to evenly disperse the scintillator precursor solution onto the substrate, and finally annealing it to obtain a scintillator film.
6. The method according to claim 3, characterized in that, The spin coating method involves using a pipette to draw a scintillator precursor solution and drop it onto a rotating substrate. The rotation speed is 800-3000 rpm, and the time is 10-60 seconds. The centrifugal force generated by the rotation is used to uniformly disperse the scintillator precursor solution dropped onto the surface of the perovskite precursor solution. After annealing, a scintillator film is obtained.
7. The method according to claim 3, characterized in that, The solvent is one or a mixture of two or more of dimethylacetamide, N-dimethylformamide, N-methylpyrrolidone, ethyl acetate, and dimethyl sulfoxide.
8. The method according to claim 3, characterized in that, The annealing process involves placing the scintillator film and substrate, after being scraped or spin-coated, on a heating plate at a temperature of 75-120°C for 6-48 hours to ensure solvent evaporation and complete crystallization of the perovskite material, followed by slow cooling to room temperature.
9. The method according to claim 1, characterized in that, The picosecond laser is generated by a picosecond pulsed laser with a wavelength of 355 nm, a pulse width of 7-10 ps, a spot diameter of 7 μm, and a spot area of 38.465 × 10⁻⁶. -8 cm 2 The energy density is 1.3-26 J / cm³. -2 .
10. The method according to claim 1, characterized in that, The pixelated pattern is a discrete pattern of independent pixel units, wherein the pixel units are square, rectangular, rhomboid or circular, the size a of each pixel unit is 20-200 μm, and the spacing b between each pixel unit is 7-50 μm.