Scintillator thick film and preparation method thereof

Abstract

The invention relates to a scintillator thick film and a preparation method thereof, and belongs to the technical field of scintillator films. The scintillator thick film comprises: a substrate; the flexible high polymer layer is attached to the surface of the substrate; the scintillator film layer is attached to the surface of the flexible high polymer layer, and hydrogen bond connection is formed between the flexible high polymer layer and the scintillator film layer. According to the embodiment of the invention, the flexible high polymer is used as the connecting layer, the connecting layer is in good contact with the substrate downwards and has stronger hydrogen-bond interaction with the scintillator film layer upwards, the problem of mismatching of thermal expansion coefficients of the pure scintillator film layer and the glass substrate can be relieved through the flexible effect of the high polymer layer, and the phenomenon of cracking of the scintillator thick film is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of scintillator films, and particularly to a thick scintillator film and a preparation method thereof. Background Art

[0002] X-ray detectors based on scintillator films have important applications in multiple fields, including medical imaging, industrial non-destructive testing, security inspection, and scientific research. These detectors use scintillator materials to convert X-rays into visible light, and then convert the optical signal into an electrical signal through a photodetector, thereby realizing the detection and imaging of X-rays. The intensity change of X-rays after penetrating an object can be expressed by the formula I = I 0 ·e μd , where I 0 is the initial intensity of the X-ray, d is the thickness of the object penetrated by the X-ray, and μ is the absorption coefficient. This shows that the attenuation ability of X-rays is mainly related to the absorption coefficient and thickness of the penetrated object. Therefore, in applications that require high-energy rays, it is necessary to increase the thickness of the scintillator film to improve the absorption rate of X-rays, thereby improving the detection efficiency.

[0003] Currently, the relatively mature method for preparing thick scintillator films is to prepare CsI:Tl thick films by multiple thermal evaporation processes in a laminated manner. However, the thermal evaporation method requires expensive vacuum equipment, high energy consumption, and low utilization rate of raw materials, resulting in high preparation costs. During the preparation process, it is necessary to precisely control the evaporation rate and substrate temperature and perform multiple laminations, and the operation process is relatively complex. In addition, the CsI:Tl scintillator contains highly toxic thallium elements, posing potential risks to the environment and human health. Another commonly used method is to mix the scintillator with a polymer to form a scintillator-polymer precursor, and then prepare a thick scintillator film by methods such as drop coating and blade coating. This method has a simple preparation process and high process compatibility. However, the presence of the polymer will reduce the filling factor of the thick scintillator film, resulting in a low light output efficiency. Moreover, as the film thickness continues to increase, there are problems such as cracking, poor crystallinity, and poor stability in the film layer. Summary of the Invention

[0004] The present application provides a thick scintillator film and a preparation method thereof to solve the following technical problem: how to reduce the occurrence of cracking in the thick scintillator film.

[0005] In a first aspect, an embodiment of the present application provides a thick scintillator film, which includes:

[0006] A substrate;

[0007] A flexible polymer layer attached to the surface of the substrate;

[0008] A scintillator film layer attached to the surface of the flexible polymer layer, and a hydrogen bond connection is formed between the flexible polymer layer and the scintillator film layer.

[0009] Optionally, the flexible polymer contained in the flexible polymer layer includes at least one of the following: polyvinylpyrrolidone, polyimide, polymethyl methacrylate, and polyacrylonitrile.

[0010] Optionally, the molecular weight of the flexible polymer contained in the flexible polymer layer is 50,000 to 250,000.

[0011] Optionally, the thickness of the scintillator thick film is 150 μm to 400 μm.

[0012] Optionally, the thickness of the flexible polymer layer is 600 nm to 900 nm.

[0013] In a second aspect, an embodiment of the present application provides a method for preparing the scintillator thick film according to any one of the embodiments in the first aspect. The method includes:

[0014] First coat a flexible polymer solution on the surface of a substrate, and drop an extractant onto the surface of the substrate during the first coating process to obtain a substrate with a flexible polymer layer attached to its surface;

[0015] Anneal the substrate with the flexible polymer layer attached to its surface for the first time;

[0016] Second coat a precursor solution of the scintillator on the surface of the substrate with the flexible polymer layer attached to its surface after the first annealing to obtain a semi-finished scintillator thick film;

[0017] Anneal the semi-finished scintillator thick film for the second time to obtain a scintillator thick film.

[0018] Optionally, the raw materials of the flexible polymer solution include cesium iodide and cuprous iodide; the concentration of the precursor solution of the scintillator is 0.2 mol / L to 0.6 mol / L.

[0019] Optionally, the temperature of the first annealing and the temperature of the second annealing are 90°C to 110°C respectively.

[0020] Optionally, the first coating method is spin coating, and the spin coating sequentially includes first spin coating and second spin coating; wherein,

[0021] The rotation speed of the first spin coating is 200 RPM to 1000 RPM, and the rotation speed of the second spin coating is 1200 RPM to 3000 RPM.

[0022] Optionally, the second coating method is spraying, and the process parameters of the spraying include: the distance between the spray gun and the substrate is 2 cm to 10 cm, the spraying speed is 15 μL / s to 25 μL / s, and the pressure of the spray gun is 0.4 MPa to 0.8 MPa.

[0023] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0024] The scintillator thick film provided by the embodiment of the present application includes: a substrate; a flexible polymer layer attached to the surface of the substrate; and a scintillator film layer attached to the surface of the flexible polymer layer, and a hydrogen bond connection is formed between the flexible polymer layer and the scintillator film layer. The structure of the scintillator thick film can achieve 100% filling of the scintillator film layer with a high filling factor. Generally, for a scintillator film layer with a high filling factor, due to the difference in the thermal expansion coefficient between the film layer and the substrate, after subsequent high-temperature annealing, the film layer will crack and peel off, and this situation will become more serious as the film thickness increases. In the embodiment of the present application, a flexible polymer is used as the connection layer, which has good contact with the substrate downward and stronger hydrogen bond interaction with the scintillator film layer upward, and the flexible effect of the polymer layer can alleviate the problem of mismatch in the thermal expansion coefficient between the pure scintillator film layer and the glass substrate. In summary, the occurrence of cracking in the scintillator thick film is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present application and used together with the specification to explain the principles of the present application.

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic flow chart of a method for preparing a scintillator thick film provided by an embodiment of the present application;

[0028] Figure 2 It is a schematic external view of a scintillator thick film provided by Embodiment 1 of the present application;

[0029] Figure 3 It is an image of the film layer cross-section of a scintillator thick film under a scanning electron microscope provided by Embodiment 1 of the present application;

[0030] Figure 4 It is an image of the back of the film layer of a scintillator thick film under an optical microscope provided by Embodiment 1 of the present application;

[0031] Figure 5 It is an image of the back of the film layer of a scintillator thick film under an optical microscope provided by Comparative Example 1 of the present application;

[0032] Figure 6The photoluminescence spectrum and photoluminescence excitation spectrum of a scintillator thick film provided in Embodiment 1 of the present application. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0034] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within that range, such as 1, 2, 3, 4, 5, and 6, regardless of what the range is. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0035] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Additionally, in the description of the specification of the present application, the terms "including", "comprising", etc. mean "including but not limited to". In this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this document, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one item (piece) below", or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). For example, "at least one item (piece) among a, b, or c", or, "at least one item (piece) among a, b, and c" can all represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, c can be single or multiple respectively.

[0036] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, equipment, etc. used in the present application can be obtained through market purchases or can be prepared by existing methods.

[0037] In a first aspect, an embodiment of the present application provides a scintillator thick film, which includes:

[0038] a substrate;

[0039] a flexible polymer layer attached to the surface of the substrate;

[0040] a scintillator film layer attached to the surface of the flexible polymer layer, and a hydrogen bond connection is formed between the flexible polymer layer and the scintillator film.

[0041] Generally, due to the difference in the thermal expansion coefficient between the scintillator film layer with a high filling factor and the thermal expansion coefficient of the substrate, during the subsequent high-temperature annealing process, the film layer will crack and peel off. Moreover, when the film thickness increases, this problem becomes more serious. The difference in the thermal expansion coefficient will cause the expansion or contraction degrees of the substrate and the scintillator film layer to be inconsistent when the temperature changes, thereby generating stress at the interface between the two. When the stress accumulates to a certain extent, it will cause the film layer to crack and peel off.

[0042] The embodiment of the present application uses the flexible polymer layer as a connection layer. On the one hand, it has good contact with the substrate, providing a stable connection basis for the entire structure; on the other hand, the hydrogen bond formed with the scintillator film layer enhances the binding force between the two. More importantly, the flexibility of the flexible polymer layer can buffer the stress generated due to the mismatch of the thermal expansion coefficient through its own deformation when the temperature changes, so that the stress will not be overly concentrated at the interface between the scintillator film layer and the substrate, thereby reducing the occurrence of cracking of the scintillator thick film. This design starts from both the structure and material characteristics, effectively solving the problem of film layer cracking caused by the difference in the thermal expansion coefficient.

[0043] The substrate serves as the basic support structure of the entire scintillator thick film, providing an attachment carrier for the subsequent flexible polymer layer and scintillator film layer. The substrate can be quartz glass, FTO glass, or ITO glass. The flexible polymer layer plays a key connection and buffering role. It is attached to the surface of the substrate and can have good contact with the substrate to ensure its stable existence on the substrate. At the same time, a hydrogen bond connection is formed between it and the upper scintillator film layer. This connection method not only enhances the binding force with the scintillator film layer, but also helps to regularize the film layer structure at the microscopic level due to the certain directionality and saturation of the hydrogen bond. In addition, the flexible nature of the flexible polymer layer can effectively relieve the stress problem caused by the difference in the thermal expansion coefficient. The scintillator film layer is the core part that realizes the function of the scintillator thick film and directly participates in processes such as the absorption and conversion of rays. It is attached to the surface of the flexible polymer layer and is tightly connected to the flexible polymer layer through hydrogen bonds. Moreover, this structure can achieve 100% filling of the scintillator film layer with a high filling factor, which means that the internal structure of the scintillator film layer is dense and void-free, and its performance can be maximally exerted.

[0044] In some embodiments, the flexible polymers contained in the flexible polymer layer include at least one of the following: polyimide, polymethyl methacrylate, and polyacrylonitrile.

[0045] The flexible polymers contained in the flexible polymer layer can be one or a combination of more of polyvinylpyrrolidone (PVP), polyimide (PI), polymethyl methacrylate (PMMA), and polyacrylonitrile (PAN).

[0046] In some embodiments, the molecular weight of the flexible polymers contained in the flexible polymer layer is 50,000 to 250,000.

[0047] The molecular weight of the flexible polymers contained in the flexible polymer layer is 50,000 to 250,000. A suitable molecular weight helps the flexible polymer molecules to form good interactions with the matrix and the molecules on the surface of the scintillator film layer. One of the main functions of the flexible polymer layer is to buffer the stress generated by the difference in the coefficient of thermal expansion between the scintillator film layer and the matrix. When the molecular weight is between 50,000 and 250,000, the length and flexibility of the molecular chain are appropriate, and it can effectively absorb and disperse stress through its own stretching, bending and other deformations when the temperature changes. Like an "elastic buffer pad", it minimizes the impact of thermal stress on the scintillator film layer, thereby greatly reducing the risk of cracking of the thick scintillator film and improving the reliability and service life of the thick scintillator film. Exemplarily, the molecular weight of this flexible polymer can be 50,000, 70,000, 90,000, 120,000, 150,000, 200,000, 230,000, 250,000, etc.

[0048] In some embodiments, the thickness of the thick scintillator film is 150 μm to 400 μm.

[0049] The thickness of the thick scintillator film can be 150 μm to 400 μm, which can absorb more rays or particles, thereby improving the detection efficiency of the scintillator for rays, etc., and being effectively applied to the field of high-energy X-ray detection. Exemplarily, the thickness of this thick scintillator film can be 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, etc.

[0050] In some embodiments, the thickness of the flexible polymer layer is 600 nm to 900 nm.

[0051] The thickness of the flexible polymer layer is 600 nm to 900 nm. A suitable thickness is conducive to the active groups in the flexible polymer layer approaching the corresponding groups on the surface of the scintillator film layer sufficiently, thereby forming more and stronger hydrogen bonds. Within the thickness range of 600 nm to 900 nm, the flexible polymer molecules have sufficient space and number of groups to form hydrogen bonds with the scintillator film layer. This connection method has both a certain strength and a certain flexibility, and can adapt to the relative displacement or deformation that may occur under different conditions while ensuring the tight connection between the two. When the thickness of the flexible polymer layer is 600 nm to 900 nm, its flexibility and elasticity can play a good buffering role in the subsequent annealing, reducing the probability of problems such as cracking and peeling of the thick scintillator film due to thermal stress. Exemplarily, the thickness of the flexible polymer layer can be 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, etc.

[0052] In a second aspect, an embodiment of the present application provides a method for preparing a thick scintillator film according to any one of the embodiments of the first aspect. Figure 1 The following is a schematic flowchart of a method for preparing a thick scintillator film provided by an embodiment of the present application; please refer to Figure 1 The method includes:

[0053] S1. First coat a flexible polymer solution on the surface of a substrate, and drip an extractant onto the surface of the substrate during the first coating process to obtain a substrate with a flexible polymer layer attached to its surface.

[0054] Coating the flexible polymer solution on the surface of the substrate is a basic step for forming the flexible polymer layer. The coating process can make the flexible polymer evenly distributed on the surface of the substrate, creating conditions for subsequent good bonding with the substrate and establishing a connection with the scintillator film layer. Dripping an extractant onto the surface of the substrate during the coating process, the extractant can change the properties of the flexible polymer solution, prompting the flexible polymer molecules to arrange and aggregate better on the surface of the substrate. It may cause partial volatilization or extraction of the solvent in the solution, thereby accelerating the curing and attachment process of the flexible polymer and helping to form a dense, uniform and tightly bonded flexible polymer layer with the substrate. The extractant can be a chlorobenzene solution, dichloromethane, toluene, etc.

[0055] In some embodiments, the raw materials of the flexible polymer solution include cesium iodide and cuprous iodide; the concentration of the precursor solution of the scintillator is 0.2 mol / L to 0.6 mol / L.

[0056] Cesium iodide (CsI) has a high luminescence efficiency and good energy resolution. When it is added to a flexible polymer solution, CsI may be dispersed in the polymer matrix in the form of fine particles or molecules during the subsequent formation of the flexible polymer layer. When radiation and the like act on the scintillator thick film, CsI can absorb the radiation energy and generate scintillation light, thereby helping to improve the scintillation performance and detection efficiency of the entire scintillator thick film. Copper iodide (CuI) is a material with special optoelectronic properties, which acts synergistically with CsI to further optimize the luminescence characteristics of the scintillator thick film. The ions in CsI and CuI may interact with the flexible polymer molecules and the substances on the surface of the scintillator film layer. These ions can serve as active sites to promote the formation of closer hydrogen bond connections between the flexible polymer layer and the scintillator film layer, thereby improving the structural stability of the scintillator thick film and reducing the risk of film cracking and peeling. The concentration of the precursor solution of the scintillator can be 0.2 mol / L to 0.6 mol / L, which can ensure the uniformity of the film layer while obtaining a scintillator film layer with an appropriate thickness to achieve better detection performance. An appropriate concentration helps the precursor to form a good crystal structure during annealing. Exemplarily, the concentration of the precursor solution of the scintillator can be 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, etc.

[0057] The solvents in the flexible polymer solution and the precursor solution can be one or a combination of more of dimethyl sulfoxide (DMSO), acetonitrile (ACN), and N,N-dimethylformamide (DMF).

[0058] In some embodiments, the first coating method is spin coating, and the spin coating sequentially includes first spin coating and second spin coating; wherein,

[0059] The rotation speed of the first spin coating is 200 RPM to 1000 RPM, and the rotation speed of the second spin coating is 1200 RPM to 3000 RPM.

[0060] Spin coating can use centrifugal force to evenly spread the solution on the surface of the substrate, thereby forming a film with a uniform thickness and a flat surface. The first spin coating at a relatively low speed (200 RPM to 1000 RPM) can preliminarily spread the flexible polymer solution on the surface of the substrate, and the lower speed can reduce the generation of bubbles in the solution. The second spin coating at a relatively high speed (1200 RPM to 3000 RPM) can control the thickness of the flexible polymer layer and further homogenize the film layer. Exemplarily, the speed of the first spin coating can be 200 RPM, 300 RPM, 400 RPM, 500 RPM, 600 RPM, 700 RPM, 800 RPM, 900 RPM, 1000 RPM, etc.; the speed of the second spin coating can be 1200 RPM, 1400 RPM, 1600 RPM, 1800 RPM, 2000 RPM, 2200 RPM, 2400 RPM, 2600 RPM, 2800 RPM, 3000 RPM, etc.

[0061] S2. Anneal the substrate with the flexible polymer layer attached to its surface for the first time;

[0062] Anneal the substrate with the flexible polymer layer attached to its surface for the first time. The heating during the annealing process can further volatilize the residual solvent in the flexible polymer layer and remove possible impurities at the same time. This helps to improve the purity and stability of the flexible polymer layer, and avoid affecting its performance and the bonding effect with other layers due to the presence of solvents or impurities. Annealing can also enhance the interaction between the flexible polymer molecular chains.

[0063] S3. Second coat the precursor solution of the scintillator on the surface of the substrate with the flexible polymer layer attached to its surface after the first annealing to obtain a semi-finished scintillator thick film;

[0064] Coat the precursor solution of the scintillator on the surface of the substrate with the flexible polymer layer attached to its surface after the first annealing. The components in the precursor solution will undergo chemical reactions and phase changes during subsequent processing, and finally form a film layer with scintillation function. During the coating process, the precursor solution of the scintillator will come into contact with the surface of the flexible polymer layer, providing an opportunity to form hydrogen bond connections between the two.

[0065] In some embodiments, the second coating method is spraying, and the process parameters of the spraying include: the distance between the spray gun and the substrate is 2 cm to 10 cm, the spraying speed is 15 μL / s to 25 μL / s, and the pressure of the spray gun is 0.4 MPa to 0.8 MPa.

[0066] Spraying is an efficient method that can achieve uniform coating over a large area. Compared with other coating methods, it can evenly disperse the precursor solution of the scintillator in the form of tiny droplets on the surface of the substrate, which is conducive to forming a uniform and continuous scintillator film layer. The distance between the spray gun and the substrate can be 2 cm to 10 cm, which can achieve a balance between the spreading property and the dispersibility of the droplets to obtain a scintillator film layer with good quality; the spraying speed can be 15 μL / s to 25 μL / s, and an appropriate speed can make the droplets orderly accumulate and fuse on the substrate surface to form a dense film structure; the pressure of the spray gun can be 0.4 MPa to 0.8 MPa, which can obtain droplets with appropriate particle size and dispersibility to prepare a high-quality scintillator film layer. An appropriate pressure can make the droplets impact the substrate surface at a certain speed, enhancing the bonding force between the droplets, the substrate, and the flexible polymer layer, and improving the adhesion and stability of the film layer. Exemplarily, the distance between the spray gun and the substrate can be 2 cm, 4 cm, 6 cm, 8 cm, 10 cm, etc.; the spraying speed can be 15 μL / s, 17 μL / s, 19 μL / s, 21 μL / s, 23 μL / s, 25 μL / s, etc.; the pressure of the spray gun can be 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, etc.

[0067] S4. Anneal the scintillator thick film semi-finished product for the second time to obtain a scintillator thick film.

[0068] Performing the second annealing treatment on the scintillator thick film semi-finished product helps the growth and perfection of crystals, improving the crystallinity and performance of the scintillator. The second annealing can also further enhance the bonding force between the flexible polymer layer and the scintillator film layer.

[0069] In some embodiments, the temperatures of the first annealing and the second annealing are 90°C to 110°C respectively.

[0070] After the flexible polymer solution is coated on the substrate surface and the extractant is added, there will be some residual solvents and possibly small molecule impurities in the flexible polymer layer. The temperature of the first annealing can be 90°C to 110°C, enabling these solvents and small molecule impurities to obtain sufficient energy to volatilize. The temperature of the first annealing can also enhance the mechanical properties of the flexible polymer layer, enabling it to better withstand the stresses during subsequent processes and use, and improving the bonding state between the flexible polymer layer and the substrate. The temperature of the second annealing can be 90°C to 110°C, which can promote the chemical reaction of the precursor and gradually transform it into a crystal structure with scintillation function, enhancing the interaction between the flexible polymer layer and the scintillator film layer. Exemplarily, the temperatures of the first annealing and the second annealing can be 90°C, 95°C, 100°C, 105°C, 110°C, etc.

[0071] The preparation method of the scintillator thick film is realized based on the above-mentioned scintillator thick film. The specific structure of the scintillator thick film can be referred to the above embodiments. Since the preparation method of the scintillator thick film adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated one by one here.

[0072] The following will further illustrate the present application with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods without specific conditions noted in the following embodiments are usually determined according to national standards. If there is no corresponding national standard, they are carried out according to general international standards, conventional conditions or conditions recommended by the manufacturer.

[0073] Example 1

[0074] A scintillator thick film with a thickness of 160 μm; the scintillator thick film includes:

[0075] ITO glass substrate;

[0076] A flexible PVP polymer layer attached to the surface of the substrate with a thickness of 800 nm; the molecular weight of PVP is 150,000;

[0077] A scintillator film layer attached to the surface of the flexible PVP polymer layer, and a hydrogen bond connection is formed between the flexible polymer layer and the scintillator film layer.

[0078] A preparation method of a scintillator thick film includes:

[0079] S11. First coat the flexible polymer solution on the surface of the substrate, and drop an extractant on the surface of the substrate during the first coating to obtain a substrate with a flexible polymer layer attached to its surface;

[0080] S11 specifically includes: Preparation of precursor solution: Weigh 0.006 mol of cesium iodide and 0.004 mol of cuprous iodide in a clean glass bottle according to a molar ratio of 3:2 in a glove box, and add 5 ml of DMF to dissolve. Then place it on a magnetic stirrer and stir for 12 h to ensure complete dissolution. Obtain the precursor solution (Cs 3 Cu 2 I 5 ) of the scintillator for standby, with a concentration of 0.6 mol / L.

[0081] Surface treatment of ITO glass: First ultrasonically clean the ITO glass with ethanol and then dry it, and then perform plasma treatment for 20 min. Thereby improving the wettability of the ITO surface.

[0082] Spin - coating PVP layer: First, weigh 0.1 g of PVP powder with a molecular weight of 150,000, dissolve it in 4 ml of DMF solvent, and heat and stir on a hot stage at 60 °C for 2 h. Take a piece of surface - treated ITO glass and place it at the center of the spin coater. Use a pipette to take 400 μl of PVP solution and evenly drop it on the glass slide so that the solution can completely cover the entire glass surface. Set the spin coater program to spin at 600 RPM for 20 s first, and then increase the speed to 2000 RPM and spin for 40 s. Then use a pipette to take 200 μl of chlorobenzene solution, and the pipette is 1 cm above the center of the glass slide. Continuously and evenly drop the chlorobenzene at the 40th s of the total spin - coating time to ensure that the liquid flows continuously in a column.

[0083] S21. Anneal the substrate with a flexible polymer layer attached to its surface for the first time; specifically: transfer the spin - coated ITO glass to a hot stage at 100 °C and anneal for 30 min;

[0084] S31. Second - coat the precursor solution of the scintillator on the surface of the substrate with a flexible polymer layer attached to its surface after the first annealing to obtain a semi - finished scintillator thick film; specifically: pour the prepared precursor solution into the liquid storage cavity of the spray gun in a glove box. The nozzle diameter is 0.5 mm, and an air compressor provides 0.6 Mpa for the spray gun. First, place the ITO glass spin - coated with PVP on a hot stage at 90 °C and pre - heat for 15 min. The spray gun is 6 cm away from the substrate. Adjust the air valve to control the liquid flow rate at 20 μl / s and spray back and forth in a "zig - zag" pattern. From top to bottom is one cycle. There is a 30 - s interval between cycles to allow the solvent to fully volatilize. After every 5 cycles are sprayed, the hot - stage temperature is increased by 0.6 °C;

[0085] S41. Anneal the semi - finished scintillator thick film for the second time to obtain a scintillator thick film; specifically: after spraying, anneal on a hot stage at 100 °C for 20 min.

[0086] Comparative Example 1

[0087] Based on the disclosure of Example 1, the difference between Comparative Example 1 and Example 1 is that there is no flexible polymer layer.

[0088] Figure 2 This is a schematic diagram of the appearance of a scintillator thick film provided in Example 1 of this application; please refer to Figure 2 , with a size of 2.5 cm * 2.5 cm and a uniform coating; Figure 3 This is a cross - sectional image of the film layer of a scintillator thick film under a scanning electron microscope provided in Example 1 of this application; please refer to Figure 3 , and the thickness of the scintillator thick film is 160 μm; Figure 4 This is the back - side image (with PVP) of the film layer of a scintillator thick film under an optical microscope provided in Example 1 of this application;Figure 5 This is the backside image of a scintillator thick film provided in Comparative Example 1 of this application under an optical microscope (without PVP); please refer to Figures 4 - 5 and it can be seen that Figure 4 the film layer with PVP has better contact than Figure 5 the one without PVP. For the scintillator thick film without PVP, delamination can be clearly seen, that is, the film layer and the substrate are not in contact; Figure 5 there are light-colored and dark-colored parts in Figure 4 . The light-colored part indicates that the film layer is not in contact with the substrate, which means it is prone to cracking, while Figure 5 the light-colored part is significantly less than Figure 6 This is the photoluminescence spectrum and photoluminescence excitation spectrum of a scintillator thick film provided in Example 1 of this application; please refer to Figure 6 , Cs 3 Cu 2 I 5 The fluorescence emission peak is at 430 nm, indicating that the scintillator thick film prepared in Example 1 has a large Stokes shift, small self-absorption, and good luminescence performance.

[0089] One or more technical solutions in the embodiments of this application at least further have the following technical effects or advantages:

[0090] (1) This scintillator thick film is applied to high-energy ray detection. The preparation method of this scintillator thick film has the advantages of simple process, adjustable thickness, low cost, good connectivity, and high crystallization quality, and can be applied to the field of high-energy X-ray detection;

[0091] (2) PVP polymer is selected as the connection layer, and the precursor solution of the scintillator is sprayed on it to prepare the scintillator thick film. This preparation method has the advantages of fast preparation speed, high raw material utilization rate, adjustable film layer thickness, good connectivity, and high crystallization quality, and the finally obtained scintillator thick film has the advantage of excellent ray absorption ability;

[0092] (3) First, a layer of polyvinylpyrrolidone (PVP) is spin-coated on the glass substrate, and then the precursor solution of the scintillator is sprayed on the hot stage, and repeated spraying is carried out to form a dense scintillator thick film. On the one hand, a stronger hydrogen bond connection is formed between the bottom PVP layer and the scintillator film layer; on the other hand, the PVP layer helps to release the thermal stress during the annealing process, solving the problem that the thick film is prone to cracking due to the mismatch of the thermal expansion coefficients of the scintillator film layer and the glass substrate;

[0093] (4) N,N-dimethylformamide (DMF) with a low boiling point and a large saturated vapor pressure is selected as the solvent, so that the solvent is more likely to volatilize during the annealing process, avoiding the influence of solvent residues in the film layer on crystallinity and stability;

[0094] (5) During the process of repeated spraying, gradually increasing the temperature of the hot stage can adjust the growth rate of the film layer to obtain a thick film with better crystallinity and fewer defects.

[0095] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A scintillator thick film, comprising: matrix; A flexible polymer layer is attached to the surface of the substrate; The scintillator film layer is attached to the surface of the flexible polymer layer, and a hydrogen bond is formed between the flexible polymer layer and the scintillator film layer.

2. The scintillator thick film according to claim 1, characterized in that: The flexible polymer contained in the flexible polymer layer includes at least one of the following: polyvinyl pyrrolidone, polyimide, polymethyl methacrylate, and polyacrylonitrile.

3. The scintillator thick film according to claim 1 or 2, characterized in that: The molecular weight of the flexible polymer contained in the flexible polymer layer is 50,000-250,000.

4. The scintillator thick film according to claim 1, characterized in that: The thickness of the scintillator thick film is 150 μm to 400 μm.

5. The scintillator thick film according to claim 1, characterized in that: The thickness of the flexible polymer layer is 600nm-900nm.

6. A method for preparing a scintillator thick film according to any one of claims 1 to 5, the method comprising: First coating a flexible polymer solution on the surface of a substrate, and dripping an extractant onto the surface of the substrate during the first coating process to obtain a substrate with a flexible polymer layer attached to the surface; Performing a first annealing on the substrate with the flexible polymer layer attached to the surface; coating a scintillator precursor solution on the surface of the substrate with the flexible polymer layer attached to the surface after the first annealing for a second time to obtain a scintillator thick film semi-finished product; The scintillator thick film semi-finished product is subjected to a second annealing to obtain a scintillator thick film.

7. The method according to claim 6, characterized in that The raw materials of the flexible polymer solution include: cesium iodide and cuprous iodide; the concentration of the precursor solution of the scintillator is 0.2 mol / L to 0.6 mol / L.

8. The method according to claim 6, characterized in that The first annealing temperature and the second annealing temperature are respectively 90° C. to 110° C.

9. The method according to claim 6, characterized in that The first coating method is spin coating, and the spin coating includes first spin coating and second spin coating in sequence; wherein, The rotation speed of the first spin coating is 200RPM-1000RPM, and the rotation speed of the second spin coating is 1200RPM-3000RPM.

10. The method according to claim 6, characterized in that The second coating method is spraying, and the process parameters of the spraying include: the distance between the spray gun and the substrate is 2 cm to 10 cm, the spraying speed is 15 μL / s to 25 μL / s, and the pressure of the spray gun is 0.4 MPa to 0.8 MPa.

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