Two-dimensional lead-free double perovskite material and preparation method and X-ray detection application thereof

Abstract

The invention belongs to the technical field of X-ray detection, and particularly relates to lead-free two-dimensional double perovskite, a preparation method of the lead-free two-dimensional double perovskite and an X-ray detector manufactured based on the perovskite. The lead-free two-dimensional double perovskite is applied to X-ray detection. According to the preparation method, histamine dihydrochloride (C5H11Cl2N3Cl), silver chloride (AgCl) and bismuth trioxide (Bi2O3) are mainly used as raw materials, a mixed solution of hydrobromic acid (HBr) and hypophosphorous acid (H2PO2) is used as a solvent, a single crystal material ((C5H9N3) 2AgBiBr8 single crystal) is prepared through a hydrothermal method, and the two sides of the single crystal are coated with silver paste to serve as electrodes, so that the direct type X-ray detector is obtained. The preparation method disclosed by the invention has the characteristics of simplicity, easiness in operation, low requirement on equipment, low cost, low energy consumption and suitability for expanded production.

Description

Technical Field

[0001] The present invention belongs to the technical field of X-ray detection, and in particular relates to a lead-free two-dimensional double perovskite and a preparation method thereof, and an X-ray detector made based on the perovskite and applied to X-ray detection. Background Art

[0002] X-ray detectors can directly convert X-rays into electrical signals, achieving real-time imaging and digital processing. These detectors are widely used in various fields, including but not limited to non-destructive testing, airport security, railway equipment inspection, nuclear reaction monitoring and medical diagnosis. At present, commercial X-ray detection materials are mainly crystalline silicon, α-Se, CZT and HgI2. Sufficient reliability has been achieved, but the performance is far from meeting today's growing needs. Great efforts have been made to improve the performance of these materials, but they still suffer from problems such as complex manufacturing processes, high costs, and high energy consumption.

[0003] Recently, organic-inorganic hybrid perovskites, such as two-dimensional perovskite single crystals, have shown great application prospects in direct X-ray detection due to their high resistivity, large mobility lifetime values, excellent phase stability and low-cost manufacturing. The typical structures of two-dimensional perovskite single crystals are Ruddlesden-Popper type and Dion-Jacobson type. Although Dion-Jacobson type perovskites have excellent photoelectric response in theory, their application in X-ray detection is very rare compared with Ruddlesden-Popper type. For example, Liu et al. designed a new type of (DGA)PbI4 using the strong interaction between DGA and PbI2. This interaction leads to minimal lattice distortion and increased hydrogen bonding, which enhances the lattice rigidity, weakens electron-phonon coupling, suppresses carrier disorder scattering, and significantly improves carrier transport and stability. High carrier mobility and remarkable sensitivity are achieved. However, the presence of Pb hinders its further commercialization. It is necessary to find environmentally friendly metals to completely replace Pb.

[0004] Therefore, it is necessary to conduct in-depth research on two-dimensional perovskite materials. On the basis of optimizing the preparation process, it is possible to achieve higher-quality images when the materials are used in X-ray imaging and reduce harm to the human body. Summary of the invention

[0005] In order to solve the problems of complex process, high cost and high energy consumption in the prior art, one of the purposes of the present invention is to disclose a two-dimensional lead-free double perovskite material, and the new material has excellent semiconductor properties in terms of high resistivity, low trap state density and long carrier migration lifetime; the second purpose of the present invention is to disclose a preparation method of the two-dimensional lead-free double perovskite material, and the preparation method has the characteristics of simplicity, easy operation and low cost; the third purpose of the present invention is to disclose the application of the two-dimensional lead-free double perovskite material in X-ray imaging, and the X-ray detector exhibits self-powered characteristics and short response time under X-ray irradiation.

[0006] The technical solution of the present invention is:

[0007] 1. A two-dimensional lead-free double perovskite material, the chemical formula of which is (C5H9N3)2AgBiBr8.

[0008] 2. A method for preparing a two-dimensional lead-free double perovskite material, comprising the following steps:

[0009] (1) histamine dihydrochloride, silver chloride, bismuth trioxide, hydrobromic acid and hypophosphorous acid are mixed according to the proportions and heat treated until they are completely dissolved;

[0010] (2) gradually heating the completely dissolved solution to 160-180° C. within 4-6 hours, keeping the temperature at 160-180° C. for 2-3 hours, then cooling the solution to 80-100° C. within 60-72 hours, then cooling the solution to 20-25° C. within 60-72 hours, keeping the temperature at 20-25° C. for 5-10 hours, filtering out the synthesized crystals and washing them with acetone to obtain a two-dimensional lead-free double perovskite material, which is then stored in a vacuum.

[0011] Preferably, the mass volume ratio of histamine dihydrochloride, silver chloride, bismuth trioxide, hydrobromic acid and hypophosphorous acid added in step (1) is 0.2761-0.2765:0.2148-0.2152:0.3492-0.3468:8-12:1.5-2.5, g:g:g:ml:ml.

[0012] Further preferably, step (2) is: gradually heating the completely dissolved solution to 180°C within 4 hours, keeping it warm at 180°C for 2 hours, then cooling the solution to 100°C within 72 hours, and then cooling the solution to 20°C within 72 hours, keeping it warm at 20°C for 5 hours, filtering out the synthesized crystals and washing them with acetone to obtain a two-dimensional lead-free double perovskite material, and storing it in a vacuum.

[0013] 3. The application of the two-dimensional lead-free double perovskite material in the preparation of an X-ray detection device comprises the following steps:

[0014] (1) placing a (C5H9N3)2AgBiBr8 crystal in a nitrogen environment, washing it with anhydrous ether for 3-5 times to remove organic matter and particulate impurities on the surface, and then drying it in a vacuum oven at 60-80°C for 18-24 hours;

[0015] (2) While ensuring that the crystal surface is clean, silver paste is applied to both sides of the crystal by a coating method to act as a metal Ag electrode to obtain an X-ray detector device.

[0016] The beneficial effects of the present invention are as follows: the technical solution disclosed in the present invention adopts a temperature cooling strategy to synthesize a two-dimensional layered perovskite (C5H9N3)2AgBiBr8 single crystal. The new material has excellent semiconductor properties in terms of high resistivity, low trap state density and long carrier migration lifetime. And the X-ray detector prepared based on the (C5H9N3)2AgBiBr8 crystal exhibits self-powered characteristics and a short response time under X-ray irradiation. The X-ray detector also has high sensitivity and low detection limit, both of which are superior to commercial α-Se semiconductors. The prepared device also exhibits excellent imaging performance and long-term stability in X-ray imaging.

[0017] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 The synthesis steps of (C5H9N3)2AgBiBr8 single crystal;

[0020] Figure 2 This is a physical picture of (C5H9N3)2AgBiBr8 single crystal;

[0021] Figure 3 This is a comparison chart between the single crystal analysis results and the test XRD;

[0022] Figure 4 is the relationship between current and time at different voltages and different X-ray doses;

[0023] Figure 5 is the relationship between current and time under bias voltage 0V and different X-ray doses;

[0024] Figure 6 It is a schematic diagram of an X-ray detection imaging system;

[0025] Figure 7 It is a physical picture used for X-ray imaging;

[0026] Figure 8 This is an imaging result diagram for X-ray imaging. DETAILED DESCRIPTION

[0027] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0028] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0029] Example 1

[0030] according to Figure 1 The process flow chart shown in FIG. 1 is to prepare a two-dimensional lead-free double perovskite material, comprising the following steps:

[0031] (1) Take a beaker and add 10 ml of hydrobromic acid (HBr) and 2 ml of hypophosphorous acid (H2PO2) to the mixture. Then add 1.5 mmol of histamine dihydrochloride (C5H 11 Cl2N3Cl), 1.5mmol of silver chloride (AgCl) and 0.75mmol of bismuth trioxide (Bi2O3);

[0032] (2) Then place it on a hot plate and stir at 80°C until completely dissolved, then transfer the solution to an absolutely clean glass bottle, then set the oven parameters, set the oven temperature to 180°C, the heating time is 4 hours, then keep the temperature for 2 hours, then cool to room temperature, cool down the temperature time for 4 hours, then heat to 180°C, keep warm for 2 hours, cool from 180°C to 100°C for 72 hours, cool from 100°C to 20°C for 72 hours, keep warm to 20°C for 5 hours. Finally, filter out the synthesized crystals, wash with acetone (slightly soluble or insoluble and volatile solvent), and vacuum store. The (C5H9N3)2AgBiBr8 single crystals prepared by this method are shown in Figure 2 shown.

[0033] Application Examples

[0034] A direct X-ray detection device is prepared according to the following method:

[0035] (1) Place a piece of (C5H9N3)2AgBiBr8 crystal (about 5 g) in a nitrogen environment, wash it with anhydrous ether three times to remove organic matter and particulate impurities on the surface, and then dry it in a vacuum oven at 60°C for 24 hours to ensure that the crystal surface is clean;

[0036] (2) Silver paste is applied on both sides of the crystal by the coating method to act as metal Ag electrodes.

[0037] Performance Testing

[0038] The two-dimensional lead-free layered double perovskite single crystal material ((C5H9N3)2AgBiBr8 single crystal) prepared in Example 1 was subjected to the following operations: X-ray powder diffraction (XRD) was used for detection, and the obtained X-ray powder diffraction pattern was as follows: Figure 3 As shown. Figure 3 It can be seen that the XRD of the (C5H9N3)2AgBiBr8 single crystal prepared in Example 1 is consistent with the XRD (Simulation) simulated after single crystal analysis, proving that the structure of the (C5H9N3)2AgBiBr8 single crystal can indeed be prepared according to the preparation method of Example 1 of the present invention.

[0039] The direct X-ray detector device manufactured in the application example is placed under X-ray irradiation, and a digital source meter is used to collect electrical signals, such as Figure 4 As shown in the figure, it can be seen that the current value changes in response to different voltages and different X-ray doses. Figure 5 It can be seen that when the bias voltage is 0V, the detector still has a current response under X-ray irradiation, which proves that the device has the self-powered characteristic. In order to verify the imaging effect of the X-ray detector, a successful construction Figure 6 The imaging platform shown, through Figure 7 Key physical picture and Figure 8 As can be seen from the imaging results, the shape of the key can be clearly seen.

[0040] In summary, this technical solution uses a temperature cooling strategy to synthesize a two-dimensional layered perovskite (C5H9N3)2AgBiBr8 single crystal. The new material has excellent semiconductor properties in terms of high resistivity, low trap state density and long carrier migration lifetime. The X-ray detector based on the (C5H9N3)2AgBiBr8 perovskite material exhibits self-powered characteristics and a short response time (21.8 / 42.7ms) under X-ray irradiation. The X-ray detector has a high sensitivity (252.38μC Gy air -1 cm -2 ) and a low detection limit (68.9n Gy air s -1 ), both of which are superior to the commercialized α-Se semiconductor (~20μC Gy air -1 cm -2 and ~5.5nGy air s -1 ). The fabricated devices also exhibited excellent imaging performance and long-term stability in X-ray imaging.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A two-dimensional lead-free double perovskite material, characterized in that: The chemical formula of the material is (C5H9N3)2AgBiBr8.

2. A method for preparing a two-dimensional lead-free double perovskite material, characterized in that: The steps include: (1) histamine dihydrochloride, silver chloride, bismuth trioxide, hydrobromic acid and hypophosphorous acid are mixed according to the proportions and heat treated until they are completely dissolved; (2) gradually heating the completely dissolved solution to 160-180° C. within 4-6 hours, keeping the temperature at 160-180° C. for 2-3 hours, then cooling the solution to 80-100° C. within 60-72 hours, then cooling the solution to 20-25° C. within 60-72 hours, keeping the temperature at 20-25° C. for 5-10 hours, filtering out the synthesized crystals and washing them with acetone to obtain a two-dimensional lead-free double perovskite material, which is then stored in a vacuum.

3. The method for preparing a two-dimensional lead-free double perovskite material according to claim 2, characterized in that: The mass volume ratio of histamine dihydrochloride, silver chloride, bismuth trioxide, hydrobromic acid and hypophosphorous acid added in step (1) is 0.2761-0.2765:0.2148-0.2152:0.3492-0.3468:8-12:1.5-2.5, g:g:g:ml:ml.

4. The method for preparing a two-dimensional lead-free double perovskite material according to claim 2, characterized in that: Step (2) is: gradually heating the completely dissolved solution to 180°C within 4 hours, keeping it at 180°C for 2 hours, then cooling the solution to 100°C within 72 hours, and then cooling the solution to 20°C within 72 hours, keeping it at 20°C for 5 hours, filtering out the synthesized crystals and washing them with acetone to obtain a two-dimensional lead-free double perovskite material, and storing it in a vacuum.

5. Application of two-dimensional lead-free double perovskite material in the preparation of X-ray detection devices, characterized in that: The steps include: (1) placing a (C5H9N3)2AgBiBr8 crystal in a nitrogen environment, washing it with anhydrous ether for 3-5 times to remove organic matter and particulate impurities on the surface, and then drying it in a vacuum oven at 60-80°C for 18-24 hours; (2) While ensuring that the crystal surface is clean, silver paste is applied to both sides of the crystal by a coating method to serve as metal Ag electrodes, thereby obtaining an X-ray detector device.

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