Melt-processable perovskite material for direct X-ray detection and method and application thereof

Abstract

The invention discloses a melt-processable perovskite material for direct X-ray detection, and a method and application thereof, and belongs to the technical field of direct X-ray detection. The molecular formula of the meltable perovskite detection material is A2PbX4; wherein A < + > is an A-site organic cation, and the organic cation contains 2-5 carbon atoms and an amino group; x <-> is halogen or halogen-like anions. According to the invention, cation characteristics are optimized by introducing nitrogen heterocyclic rings, conjugated double bonds, elements with strong electronegativity and the like into an organic cation structure. Meanwhile, an anion alloying method is combined to carry out coordinated regulation and control on anion components, so that regulation and control on the characteristics such as the melting point, the decomposition temperature and the sensitivity of the perovskite are realized, the meltable perovskite material is obtained, and the problem that the conventional melt method is difficult to realize regulation and control on the characteristics such as the melting point, the decomposition temperature and the sensitivity of the perovskite is solved; and the technical problem that the perovskite material is difficult to prepare by a melt method is solved.

Description

Technical Field

[0001] This invention belongs to the field of direct X-ray detection technology, specifically relating to a melt-processable perovskite material, method, and application for direct X-ray detection. Background Technology

[0002] Currently, solution processing has become the mainstream technology for preparing perovskite functional layers due to its significant advantages such as low cost, simple process, and low equipment requirements. The core of solution processing lies in dissolving the perovskite precursor in a specific solvent to form a homogeneous solution, which is then coated onto a substrate using solution processing techniques such as spin coating, blade coating, and spray coating. Post-treatment steps such as annealing then achieve the crystallization and formation of the perovskite thin film. Solution processing has a relatively simple process flow, low equipment requirements, and is suitable for large-scale production and compatibility with various substrate materials, thus it has been widely used in the preparation of perovskite functional layers. However, solution processing also has some limitations. For example, the solvents are highly toxic; the use of volatile organic solvents not only poses potential environmental hazards but may also adversely affect the health of operators. Furthermore, the evaporation rate and uniformity of the solvent are difficult to control precisely, easily leading to the formation of pores or non-uniform structures in the film, affecting the quality and performance of the perovskite thin film.

[0003] X-ray detectors are mainly divided into two categories based on their operating principles: indirect and direct. Indirect X-ray detectors first convert X-rays into visible light using a scintillator, and then convert this into an electrical signal using a visible light sensor for detection. Direct X-ray detectors, on the other hand, directly convert X-rays into electrical signals using semiconductor materials. Currently, research on the melt-process fabrication of perovskite direct X-ray detectors mainly focuses on all-inorganic perovskite systems such as CsPbBr3 and Cs3Bi2Br9. However, the stable crystal structure of these materials results in high melting points (e.g., CsPbBr3 has a melting point as high as 560℃), which far exceeds the temperature tolerance of common imaging substrates (such as CMOS and TFT) (typically below 200℃). These high temperatures can easily damage the imaging substrate, thus greatly limiting the application potential of the melt method in the fabrication of arrayed imaging devices. Therefore, developing perovskite materials with melting points that match the temperature tolerance of the imaging substrate has become crucial for promoting the development of perovskite X-ray flat panel detectors using the melt method. Summary of the Invention

[0004] The purpose of this invention is to provide a meltable perovskite material, method, and application for direct X-ray detection. This material has a suitable melting point (90-200℃) and is suitable for direct detection. It aims to solve the technical problem that existing meltable perovskite materials have problems such as excessively high melting point, large band gap, and low carrier mobility, which make it difficult to achieve in-situ integration with common planar conductive substrates, thus restricting the fabrication of high-performance, high-stability direct X-ray detectors.

[0005] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a meltable perovskite material for direct X-ray detection, wherein the molecular formula of the meltable perovskite detection material is A2PbX4; Among them, A + The A-site organic cation contains 2-5 carbon atoms and one amino group; X - It is a halogen or halogen-like anion.

[0006] Furthermore, the organic cation at the A site also includes F, Cl, or O; The halogen or halogen-like anion is Cl. - ,Br - I - and SCN - One or more of them.

[0007] Furthermore, the melting point of the fusible perovskite detection material is 90~200℃.

[0008] This invention also discloses a method for preparing the above-mentioned melt-processable perovskite material for direct X-ray detection, comprising the following steps: The halide salt of the organic cation at site A, lead halide, and solvent are mixed and stirred to obtain a perovskite precursor solution. The perovskite precursor solution is dropped into an antisolvent, and after filtration and drying, a melt-processable perovskite material for direct X-ray detection is obtained.

[0009] Furthermore, the halogen salt of the organic cation at the A site is one of 3,3-difluoroazacyclobutane halogen salt, 3-fluoroazacyclobutane halogen salt, 3-chloroazacyclobutane halogen salt, and 3-bromoazacyclobutane halogen salt; Lead halides are lead iodide, lead chloride, or lead bromide.

[0010] Furthermore, the halogen salt of the organic cation at the A site is a hydrochloride, hydrobromide, or hydroiodide. The solvent is N,N-dimethylformamide, γ-butyrolactone, N-methylpyrrolidone, or dimethyl sulfoxide.

[0011] Furthermore, the molar ratio of the halogen salt of the A-site organic cation to the solvent is 2:1; the volume of the solvent used is 1 to 2 times the total molar amount of the halogen salt of the A-site organic cation and the solvent.

[0012] Further, the antisolvent is chlorobenzene, anisole, ethyl acetate, or chloroform; the volume ratio of the perovskite precursor solution to the antisolvent is 1:(10~30). The mixing temperature is 30~60℃, and the time is 2~8h.

[0013] The present invention also discloses a melt-processable perovskite material for direct X-ray detection prepared by the above preparation method.

[0014] This invention also discloses the application of the above-mentioned perovskite material in the fabrication of direct perovskite X-ray detectors or imaging devices, including the following steps: A fusible perovskite material for direct X-ray detection is laid on the substrate surface. The substrate is then heated until the fusible perovskite detection material melts. A flat metal sheet is then pressed onto the molten perovskite detection material. The material is then cooled and the metal sheet is removed to obtain a perovskite film integrated with the substrate. Subsequently, a metal electrode is deposited on the surface of the perovskite film to obtain a direct perovskite X-ray detector or imaging device. The conductive substrate is one of ITO, FTO and TFT; The temperature of the heating substrate is the melting point of perovskite; the cooling is performed at a rate of 5~20℃ / min to room temperature.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a melt-processable perovskite material for direct X-ray detection. The cationic properties are optimized by introducing nitrogen heterocycles, conjugated double bonds, and highly electronegative elements into the organic cationic structure. Simultaneously, anionic alloying is used to synergistically regulate the anionic composition, enabling control over the melting point, decomposition temperature, and sensitivity of the perovskite. This results in a melt-processable perovskite material, solving the technical problem that existing melt methods struggle to control these properties, hindering the preparation of perovskite materials.

[0016] This invention also discloses a method for preparing the aforementioned fusible perovskite detection material. This method employs a solvent-free melt method, involving only two basic steps: heating and melting, and cooling and solidification. The process is simple and efficient. Compared with traditional solution methods, this method effectively avoids problems such as difficult solvent evaporation, toxic reagent residues, solvent hazards, and porosity defects caused by evaporation.

[0017] The present invention also discloses the application of the above-mentioned fusible perovskite detection material in the preparation of direct perovskite X-ray detectors or imaging devices. The method eliminates the interference of solvent by heating the perovskite material to a molten state, so that the precursor can crystallize uniformly in a solvent-free environment. This solvent-free melt environment can effectively avoid defects caused by solvent residue or incomplete evaporation, thereby significantly improving the crystallization quality and uniformity of the perovskite film, and thus improving the electrical performance and imaging quality of the device.

[0018] Furthermore, this method achieves thin film preparation through direct heating and controlled cooling rate, eliminating the use of solvents and related evaporation treatment steps, greatly simplifying the process. It also completely avoids the use of solvents, fundamentally eliminating the environmental pollution and health risks caused by solvent evaporation and residues, thus meeting the requirements of green chemistry and sustainable development.

[0019] Furthermore, because the melt method can produce high-quality, defect-free perovskite films and avoids the potential impact of solvent residue on device performance, the perovskite imaging devices prepared by this method exhibit higher stability and reliability during long-term use. In addition, the solvent-free nature of the melt method results in a tighter contact between the perovskite film and the imaging substrate, leading to more stable electrical connections, thereby further improving device performance and lifespan. Attached Figure Description

[0020] Figure 1 The crystal structures are three-dimensional ABX3 perovskite and two-dimensional A2BX4 perovskite; Where: a-three-dimensional ABX3 perovskite; b-two-dimensional A2BX4 perovskite; Figure 2 The organic cation used in this invention; Among them: a-3,3-difluoroazirheterobutane cation; b-3-fluoroazirheterobutane cation; c-3-chloroazirheterobutane cation; d-3-bromoazirheterobutane cation; Figure 3 This is a schematic diagram of the process for preparing perovskite films using the melt method of the present invention; Figure 4 Images showing the process of heating, melting, cooling and solidifying the melt-processable (3,3-DFAZ)2PbI2Cl2 two-dimensional perovskite material of this invention; Figure 5 This is a schematic diagram of the structure of the two-dimensional perovskite direct X-ray detector prepared by the melt method according to the present invention. Figure 6 The key performance parameters (sensitivity and detection limit) of the X-ray detector prepared from the melt-processable two-dimensional perovskite material described in this invention are presented, and their performance is compared and analyzed with that of previously reported two-dimensional perovskite detectors.

[0021] Figure 7 This is a photograph of the two-dimensional perovskite X-ray imaging device fabricated on a TFT substrate by the melt method according to the present invention. Figure 8 This invention describes the imaging principle of the X-ray imaging device prepared by the melt method and the imaging results of metallic letters. Wherein: a- Schematic diagram of X-ray imaging principle; b- Photograph of the metal letter; c- Imaging result of the metal letter under X-ray irradiation by an X-ray imaging device. Detailed Implementation

[0022] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0023] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0024] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0025] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0026] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0027] This invention provides a fusible perovskite detection material for use in direct X-ray detection. This material is based on the A2PbX4 (A is an organic cation, X is a halide or halide-like anion)RP (Ruddlesden-Popper) perovskite system. The cation properties are optimized by introducing nitrogen heterocycles, conjugated double bonds, and elements with high electronegativity into the organic cation structure. Simultaneously, an anion alloying method is used to improve the performance of Cl... - ,Br - I - SCN - By synergistically regulating anionic components, the melting point, decomposition temperature, and sensitivity of perovskite can be controlled, thereby obtaining fusible perovskite materials.

[0028] The specific preparation method includes the following steps: The halide salt of the organic cation at site A, lead halide, and solvent are mixed and stirred to obtain a perovskite precursor solution. The perovskite precursor solution was dropped into an antisolvent, and after filtration and drying, a fusible perovskite detection material solid powder was obtained.

[0029] Preferably, the solvent is N,N-dimethylformamide (DMF). γ Butyrolactone (GBL), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), etc.

[0030] Preferably, the halogen salt of the organic cation at the A site is a halide salt of organic cations such as 3,3-difluoroazetidine (DFAZ), 3-fluoroazetidine (FAZ), 3-chloroazetidine (CAZ), and 3-bromoazetidine (BAZ), including hydrochloride, hydrobromide, and hydroiodide.

[0031] Preferably, the lead halide is lead iodide (PbI2), lead chloride (PbCl2), lead bromide (PbBr2), etc.

[0032] Preferably, the molar ratio of the halogen salt of the A-site organic cation to the solvent is 2:1; the volume of the solvent is 1 to 2 times the total molar amount of the halogen salt of the A-site organic cation and the solvent.

[0033] Preferably, the antisolvent is chlorobenzene, anisole, ethyl acetate, chloroform, etc.; the volume ratio of the perovskite precursor solution to the antisolvent is 1:(10~30); the mixing and stirring temperature is 30~60℃, and the time is 2~8h.

[0034] In the fabrication of direct X-ray detection, a fusible perovskite detector material is heated above its melting point to completely melt it, forming a stable melt. This melt exhibits good fluidity at high temperatures and can spread uniformly on the imaging substrate surface. Next, by precisely controlling the cooling rate, the melt gradually crystallizes on the substrate, forming a high-quality perovskite thin film. This crystallization process can be carried out without solvent participation, avoiding problems such as incomplete solvent evaporation, pore formation, and solvent residue associated with traditional solution methods. Simultaneously, the melt method ensures close contact and good electrical connection between the perovskite thin film and the substrate, thereby achieving efficient carrier transport. After the perovskite thin film is prepared, a conductive electrode (such as ITO, gold, or silver) is further deposited on its surface to fabricate a perovskite X-ray imaging device.

[0035] This invention presents a novel strategy for in-situ integration of perovskite thick films for direct X-ray detection using a solvent-free melt method. Solution-coated / spray-coated perovskite films for X-ray detection with in-situ integration with pixelated substrates are currently the main methods, but they still face problems of solvent residue and environmental pollution. The solvent-free melt method for preparing perovskite thick films, achieving in-situ integration of perovskite semiconductors and pixelated substrates, solves the solvent-related problems of solution-coated / spray-coated methods, providing a completely new process route for X-ray imaging device fabrication.

[0036] A strategy combining organic cation design and anion alloying is proposed to achieve molten perovskite. This method not only melts the perovskite material but also suppresses the quantum confinement effect of RP perovskite, thereby improving carrier mobility. It balances the processability and photoelectric properties of perovskite materials for X-ray detection, providing a new approach to achieving the goal of "low melting point - high performance".

[0037] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0038] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0039] Example 1 A method for preparing a melt-processable perovskite material and detector for direct X-ray detection includes the following steps: 0.2 mmol of DFAZCl and 0.1 mmol of lead iodide (PbI2) were mixed in a glass bottle, and then 1 mL of DMF was added to the bottle. The mixture was stirred at 30 °C for 2 h until it became clear and transparent to obtain a precursor solution. 1 mL of the precursor solution was added dropwise to 10 mL of chlorobenzene antisolvent to obtain a fusible perovskite material of (3,3-DFAZ)2PbI2Cl2. Finally, the perovskite powder was obtained by filtration, washing and drying.

[0040] Example 2 0.2 mmol of DFAZCl and 0.1 mmol of lead iodide (PbI2) were mixed in a glass bottle, and then 2 mL of DMF was added to the bottle. The mixture was stirred at 30 °C for 2 h until it became clear and transparent to obtain a precursor solution. 1 mL of the precursor solution was added dropwise to 10 mL of chlorobenzene antisolvent to obtain a fusible perovskite material of (3,3-DFAZ)2PbI2Cl2. Finally, the perovskite powder was obtained by filtration, washing and drying.

[0041] Example 3 0.2 mmol of DFAZCl and 0.1 mmol of lead iodide (PbI2) were mixed in a glass bottle, and then 1 mL of DMF was added to the bottle. The mixture was stirred at 30 °C for 2 h until it became clear and transparent to obtain a precursor solution. 1 mL of the precursor solution was added dropwise to 30 mL of chlorobenzene antisolvent to obtain a fusible perovskite material (3,3-DFAZ)2PbI2Cl2. Finally, the perovskite powder was obtained by filtration, washing and drying.

[0042] Example 4 0.2 mmol of DFAZCl and 0.1 mmol of lead iodide (PbI2) were mixed in a glass bottle, and then 1 mL of DMF was added to the bottle. The mixture was stirred at 30 °C for 2 h until it became clear and transparent to obtain a precursor solution. 1 mL of the precursor solution was added dropwise to 30 mL of anisole antisolvent to obtain a fusible perovskite material of (3,3-DFAZ)2PbI2Cl2. Finally, the perovskite powder was obtained by filtration, washing and drying.

[0043] Example 5 0.2 mmol of DFAZCl and 0.1 mmol of lead iodide (PbI2) were mixed in a glass bottle, and then 1 mL of GBL was added. The mixture was stirred at 30 °C for 2 h until clear and transparent to obtain a precursor solution. 1 mL of the precursor solution was added dropwise to 30 mL of anisole antisolvent to obtain a fusible perovskite material of (3,3-DFAZ)2PbI2Cl2. Finally, the perovskite powder was obtained by filtration, washing, and drying.

[0044] Example 6 0.2 mmol of CAZCl and 0.1 mmol of lead iodide (PbI2) were mixed in a glass bottle, and then 1 mL of GBL was added. The mixture was stirred at 30 °C for 2 h until clear and transparent to obtain a precursor solution. 1 mL of the precursor solution was added dropwise to 30 mL of anisole antisolvent to obtain a fusible perovskite material of (3,3-CAZ)2PbI2Cl2. Finally, the perovskite powder was obtained by filtration, washing, and drying.

[0045] Example 7 0.2 mmol of BAZCl and 0.1 mmol of lead iodide (PbI2) were mixed in a glass bottle, and then 1 mL of GBL was added. The mixture was stirred at 30 °C for 2 h until clear and transparent to obtain a precursor solution. 1 mL of the precursor solution was added dropwise to 30 mL of anisole antisolvent to obtain a fusible perovskite material of (3,3-BAZ)2PbI2Cl2. Finally, the perovskite powder was obtained by filtration, washing, and drying.

[0046] Application Example 1 The (3,3-DFAZ)2PbI2Cl2 perovskite powder prepared in Example 1 was uniformly spread on the surface of conductive glass ITO. The ITO was heated to the point where the (3,3-DFAZ)2PbI2Cl2 perovskite was completely melted (approximately 125°C) using a hot stage. A flat metal sheet was pressed onto the molten perovskite, and then cooled at a rate of 5°C / min. After cooling to room temperature, the metal sheet was removed to obtain a perovskite film integrated with the substrate. Finally, a metal electrode was deposited on the perovskite film to obtain a direct perovskite X-ray detector.

[0047] Application Example 2 The (3,3-DFAZ)2PbI2Cl2 perovskite powder prepared in Example 2 was uniformly spread on the surface of conductive glass ITO. The ITO was heated to the point where the (3,3-DFAZ)2PbI2Cl2 perovskite was completely melted (approximately 125°C) using a hot stage. A flat metal sheet was pressed onto the molten perovskite, and then cooled at a rate of 5°C / min until it reached room temperature. The metal sheet was then removed to obtain a perovskite film integrated with the substrate. Finally, a metal electrode was deposited on the perovskite film to obtain a direct perovskite X-ray detector.

[0048] Application Example 3 The (3,3-DFAZ)2PbI2Cl2 perovskite powder prepared in Example 3 was uniformly spread on the surface of conductive glass ITO. The ITO was heated to the point where the (3,3-DFAZ)2PbI2Cl2 perovskite was completely melted (approximately 125°C) using a hot stage. A flat metal sheet was pressed onto the molten perovskite, and then the temperature was lowered at a rate of 5°C / min. After cooling to room temperature, the metal sheet was removed to obtain a perovskite film integrated with the substrate. Finally, a metal electrode was deposited on the perovskite film to obtain a direct perovskite X-ray detector.

[0049] Application Example 4 The (3,3-DFAZ)₂PbI₂Cl₂ perovskite powder prepared in Example 4 was uniformly spread on the surface of conductive glass ITO. The ITO was heated to the point where the (3,3-DFAZ)₂PbI₂Cl₂ perovskite was completely melted (approximately 125°C) using a hot stage. A flat metal sheet was pressed onto the molten perovskite, and then the temperature was lowered at a rate of 5°C / min. After cooling to room temperature, the metal sheet was removed, resulting in a perovskite film integrated with the substrate. Finally, a metal electrode was deposited on the perovskite film to obtain a direct perovskite X-ray detector.

[0050] Application Example 5 The (3,3-DFAZ)2PbI2Cl2 perovskite powder prepared in Example 5 was uniformly spread on the surface of conductive glass ITO. The ITO was heated to the point where the (3,3-DFAZ)2PbI2Cl2 perovskite was completely melted (approximately 125°C) using a hot stage. A flat metal sheet was pressed onto the molten perovskite, and then the temperature was lowered at a rate of 5°C / min. After cooling to room temperature, the metal sheet was removed to obtain a perovskite film integrated with the substrate. Finally, a metal electrode was deposited on the perovskite film to obtain a direct perovskite X-ray detector.

[0051] Application Example 6 The (3,3-DFAZ)2PbI2Cl2 perovskite powder prepared in Example 5 was uniformly spread on the surface of a conductive glass TFT. The TFT was heated to the point where the (3,3-DFAZ)2PbI2Cl2 perovskite was completely melted (approximately 125°C) using a hot stage. A flat metal sheet was pressed onto the molten perovskite, and then the temperature was lowered at a rate of 5°C / min. After cooling to room temperature, the metal sheet was removed to obtain a perovskite film integrated with the substrate. Finally, a metal electrode was deposited on the perovskite film to obtain a direct perovskite X-ray imaging device.

[0052] Figure 1The figures show the crystal structures of three-dimensional ABX3 perovskite and two-dimensional A2BX4 perovskite, where a represents three-dimensional ABX3 perovskite and b represents two-dimensional A2BX4 perovskite. As can be seen from the figures, the presence of organic cations at the A-sites in the two-dimensional perovskite leads to a layered structure, which significantly inhibits interlayer ion migration. Furthermore, the weak interlayer interactions allow the two-dimensional perovskite to melt at relatively low temperatures.

[0053] Figure 2 The organic cations used in this invention include: α-3,3-difluoroazacyclobutane cation, β-3-fluoroazacyclobutane cation, β-3-chloroazacyclobutane cation, and β-3-bromoazacyclobutane cation. These ions all possess strong polarity, which enhances the interaction between the organic cations and the inorganic framework, thereby increasing the stability of the perovskite. Furthermore, the strong polarity increases the repulsive force between the interlayer organic cations, weakening the interaction between adjacent layers and making the two-dimensional perovskite easier to melt. In addition, the small molecular size of these cations reduces the distance between adjacent inorganic layers, thereby enhancing interlayer carrier transport and improving the detection performance of the X-ray detector.

[0054] Figure 3 This is a schematic diagram of the process of preparing perovskite film by the melt method of the present invention. It can be seen that the melt method for preparing perovskite only involves heating and melting and cooling and solidification. The entire process does not involve solvents, thus avoiding problems such as residues, toxicity and porosity caused by solvents.

[0055] Figure 4 The images show the process of heating, melting, cooling, and solidifying the (3,3-DFAZ)2PbI2Cl2 two-dimensional perovskite material that can be melt-processed according to the present invention. This demonstrates that the perovskite material prepared by the present invention can be melted at a relatively low temperature, thus providing a basis for preparing films using the melt method.

[0056] Figure 5 This is a schematic diagram of the structure of the two-dimensional perovskite direct X-ray detector prepared by the melt method according to the present invention. The detector includes three layers: the bottom layer is a planar conductive substrate, such as ITO, FTO, TFT, etc.; the middle layer is a perovskite layer prepared by the melt method; and the top layer is a metal electrode prepared by vapor deposition.

[0057] Figure 6 The key performance parameters (sensitivity and detection limit) of the X-ray detector prepared from the melt-processable two-dimensional perovskite material described in this invention are presented, and their performance is compared with that of two-dimensional perovskite detectors prepared by solution methods as previously reported. It can be seen that the X-ray detector prepared by the melt method (This Work) exhibits excellent detection performance, comparable to two-dimensional perovskite X-ray detectors prepared by solution methods.

[0058] Figure 7 The image shows a two-dimensional perovskite X-ray imaging device fabricated on a TFT substrate using the melt method according to the present invention, illustrating that the melt method can be used to fabricate arrayed X-ray flat panel imaging devices.

[0059] Figure 8 This invention presents the imaging principle of the X-ray imaging device prepared by the melt method and the imaging results of metallic letters. It can be seen that the imaging device prepared by the melt method possesses excellent imaging performance and can achieve imaging of common objects.

[0060] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A fusibly processable perovskite material for direct X-ray detection, characterized in that, The formula of the fusible perovskite detection material is A2PbX4. wherein A + is an A-site organic cation containing 2-5 carbon atoms and one amino group; X - is a halogen or halogen-like anion.

2. The melt-processable perovskite material for direct X-ray detection according to claim 1, characterized in that, The A-site organic cation further comprises F, Cl or O. The halogen or halogen-like anion is one or more of Cl - , Br - , I - , and SCN - .

3. The melt-processable perovskite material for direct X-ray detection of claim 1, wherein, The melting point of the fusible perovskite detection material is 90-200℃.

4. The method of claim 1 to 3 for the preparation of a melt processable perovskite material for direct X-ray detection, characterized in that, The method comprises the following steps: The halide salt of the A-site organic cation, lead halide and a solvent are mixed and stirred to obtain a perovskite precursor solution; The perovskite precursor solution is dropped into an anti-solvent, and after filtration and drying, a fusible processing perovskite material for direct X-ray detection is obtained.

5. A method of producing a melt-processable perovskite material for direct X-ray detection according to claim 4, characterized in that, The halide salt of the A-site organic cation is one of 3,3-difluoroazetidinium halide, 3-fluoroazetidinium halide, 3-chloroazetidinium halide and 3-bromoazetidinium halide. The lead halide is lead iodide, lead chloride or lead bromide.

6. A method of producing a melt-processable perovskite material for direct X-ray detection according to claim 5, characterized in that, The halide salt of the A-site organic cation is hydrochloride, hydrobromide or hydroiodide. The solvent is N,N-dimethylformamide, γ-butyrolactone, N-methylpyrrolidone or dimethyl sulfoxide.

7. A method of producing a melt-processable perovskite material for direct X-ray detection according to claim 5, characterized in that, The molar ratio of the halide salt of the A-site organic cation to the solvent is 2:1; the volume of the solvent is 1-2 times the total amount of moles of the halide salt of the A-site organic cation and the solvent.

8. A method of producing a melt-processable perovskite material for direct X-ray detection according to claim 5, characterized in that, The anti-solvent is chlorobenzene, anisole, ethyl acetate or chloroform; the volume ratio of the perovskite precursor solution to the anti-solvent is 1: (10-30). The temperature of the mixing and stirring is 30-60℃, and the time is 2-8h.

9. A melt-processable perovskite material for direct X-ray detection, characterized in that, The method is prepared by the preparation method of any one of claims 1-8.

10. Use of the perovskite material of claim 9 in the preparation of a direct perovskite X-ray detector or imaging device, characterized in that The method comprises the following steps: The fusible processing perovskite material for direct X-ray detection is laid on the surface of a substrate, and then the substrate is heated to melt the fusible perovskite detection material, and then a flat metal sheet is pressed on the melted perovskite detection material, and then the metal sheet is removed after cooling to obtain a perovskite film layer integrated with the substrate; Then a layer of metal electrode is deposited on the surface of the perovskite film layer to obtain a direct perovskite X-ray detector or imaging device; The conductive substrate is one of ITO, FTO and TFT. The temperature of the heated substrate is the melting point of the perovskite; the cooling is at a rate of 5-20℃ / min to room temperature.

Images