Perovskite aqueous slurry and preparation method and application thereof

Abstract

The invention discloses perovskite aqueous slurry as well as a preparation method and application thereof, and belongs to the technical field of perovskite flat X-ray detectors. According to the preparation method disclosed by the invention, the polymer precursor and the water are used as raw materials to realize the preparation of the aqueous gel, the aqueous gel can be dissolved in the perovskite raw material to realize the preparation of the perovskite aqueous slurry, and the water is used as a green solvent, so that the harm to an operator and the environment caused by the use of a toxic organic solvent is avoided; and the used green solvent is very easy to remove, so that compared with a preparation process of an organic solvent, the preparation method greatly improves the environmental protection level of detector manufacturing, and is more in line with commercial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite X-ray flat panel detectors, and particularly relates to a perovskite aqueous slurry, a preparation method thereof, and an application thereof. Background Art

[0002] X-ray flat panel detectors have been widely used in fields such as medical imaging, industrial non-destructive testing, and security inspections. These detectors are generally divided into direct type and indirect type. Compared with indirect detectors that rely on scintillator materials, direct semiconductor detectors can directly convert X-rays into electrical signals, thus significantly reducing pixel crosstalk and improving spatial resolution. Current direct semiconductor detectors mainly include amorphous selenium (α-Se), cadmium zinc telluride (CZT), and perovskite. However, α-Se and CZT have problems such as high production energy consumption and low radiation absorption coefficients, which hinder their practical commercial applications. Metal halide perovskites have emerged as promising alternative materials for X-ray detection due to their excellent X-ray absorption ability, long carrier transport lifetime, and relatively simple preparation process. Perovskite-based X-ray detectors can be roughly divided into single crystal and polycrystalline detectors. The application of single crystal detectors is restricted by challenges such as difficulty in scaling up production, long growth cycles, and single-point imaging limitations, which limit their practical applications and commercialization. Polycrystalline perovskite detectors are usually manufactured using techniques such as spraying, imprinting, and blade coating. Among them, blade coating has become the most reliable method for manufacturing large-area perovskite flat panel detectors due to its scalability and simple process. In 2024, Fan et al. used blade coating technology to manufacture large-area perovskite thin films and coated their slurry on the surface of thin film transistors (TFTs), thus achieving high-quality X-ray imaging. In this method, it is crucial to develop a suitable slurry that can be directly blade-coated on the substrate. Current perovskite preparations rely on organic solvents such as γ-butyrolactone (GBL), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO); GBL belongs to an easily produced drug solvent and has certain toxicity, making it not suitable for large-scale use. Organic solvents such as DMF and DMSO are highly toxic and pose significant risks to production personnel and the surrounding environment, highlighting the urgent need to develop environmentally friendly alternatives. As is well known, the A-site ionic salts in perovskites are soluble in water, but the solubility of lead iodide is very low, and it is difficult to prepare a uniform perovskite slurry only with water. In previous studies, the team of Baomin Xu from Southern University of Science and Technology published in " ScienceThe paper titled "Aqueous synthesis of perovskite precursors for highly efficient perovskite solar cells" on [] uses water to synthesize perovskite precursor powder. However, organic solvents such as acetonitrile and 2-ME are still selected for fabricating perovskite thin films. And its film thickness is only a few hundred nanometers, which is used for photovoltaics. This thickness is not suitable for X-ray detectors. Summary of the Invention

[0003] The object of the present invention is to provide a perovskite aqueous slurry, its preparation method and application, so as to solve the technical problems that existing perovskite doctor blade slurries need to use toxic solvents during preparation, resulting in environmental pollution and high toxicity, which are difficult to meet the environmental protection requirements.

[0004] To achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a preparation method of a perovskite aqueous slurry, including the following steps: Dissolve the polymer precursor in water and stir to obtain an aqueous gel; Add the perovskite raw material to the aqueous gel and stir to obtain a perovskite aqueous slurry; Among them, the polymer precursor is one or more of polyacrylamide, polyethylene glycol, polyvinylpyrrolidone and polyvinyl alcohol.

[0005] Further, the dosage ratio of the polymer precursor to water is (7~10) g : (100~150) mL.

[0006] Further, the stirring for obtaining the aqueous gel is carried out at 90~95 °C for 1~3 h.

[0007] Further, the perovskite raw material is one or more of three-dimensional perovskite, quasi-two-dimensional perovskite and 0-dimensional perovskite.

[0008] Further, the dosage ratio of the perovskite raw material to the aqueous gel is (0.3~0.5) mmol : (3~5) mL.

[0009] Further, the stirring for obtaining the perovskite aqueous slurry is carried out at 90~95 °C for 1~2 h.

[0010] The present invention also discloses a perovskite aqueous slurry prepared by the above preparation method.

[0011] The present invention also discloses the application of the above perovskite aqueous slurry in the preparation of flat panel detectors, including the following steps: Coat the perovskite aqueous slurry on the surface of the substrate to obtain a perovskite solution deposition functional film, and then evaporate and deposit electrodes after heating to obtain a flat panel detector; The substrate is a pixel array thin film transistor or a COMS substrate.

[0012] Further, the coating thickness of the perovskite aqueous slurry on the surface of the substrate is 100-200 microns.

[0013] Further, the heating temperature is 90-95 °C and the time is 1-2 h.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a preparation method of a perovskite aqueous slurry. By using a polymer precursor and water as raw materials, the preparation of an aqueous gel is realized. This aqueous gel can be dissolved with a perovskite raw material to realize the preparation of a perovskite aqueous slurry. This method uses water as a green solvent, avoiding the harm to operators and the environment caused by the use of toxic organic solvents, and the green solvent used is extremely easy to remove. Compared with the removal time of organic solvents, the entire preparation process is greatly accelerated, which is more in line with commercial production.

[0015] The present invention also discloses a perovskite aqueous slurry prepared by the above preparation method. The perovskite aqueous slurry synthesized by the one-step method disclosed in the present invention can be used to scrape and prepare a perovskite thick film with a thickness of hundreds of microns. The thick film prepared by this method is suitable for perovskite X-ray detectors because perovskite X-ray detection requires a thick film of hundreds of microns to completely absorb X-rays.

[0016] The present invention also discloses the application of the above perovskite aqueous slurry in the preparation of flat panel detectors. According to relevant experimental results, the flat panel detector prepared by using the above perovskite aqueous slurry has high sensitivity (10099 µGy air cm -2 ) and a low detection limit (19.8 nGy air s -1 ). This performance is superior to that of the currently commercialized amorphous selenium detector, which indicates that to obtain X-ray imaging of the same quality, the dose used by the detector prepared by this method is lower than that of amorphous selenium, which is beneficial to reducing the harm of X-rays to the human body; moreover, the surface of the flat panel detector is extremely flat, and the surface roughness is only 0.65 microns, which is beneficial to subsequent electrode processing. At the same time, it has excellent optical imaging performance and ray imaging performance, and high-quality internal X-ray imaging of an object is obtained at 71.5 µGy air . This dose is only 3 / 4 of the medical imaging dose (100 µGy air ), reducing the harm of X-rays to the human body. Description of the Drawings

[0017] Figure 1 It is a cross-sectional scanning electron microscope image of a film formed by coating a perovskite aqueous slurry on the surface of a substrate; Figure 2 It is a surface scanning electron microscope image of a film formed by coating a perovskite aqueous slurry on the surface of a substrate; Figure 3 It is a graph showing the variation of X-ray sensitivity with voltage of a flat panel detector prepared using a perovskite aqueous slurry; Figure 4 It is the lower limit of X-ray detection of a flat panel detector prepared using a perovskite aqueous slurry; Figure 5 It is a physical image of a flat panel detector prepared using a perovskite aqueous slurry, the surface roughness measured by atomic force microscopy, and the imaging diagrams under different light intensities; Wherein: a - physical image; b - surface roughness; c - imaging diagrams under different light intensities; Figure 6 It is an X-ray imaging diagram of a flat panel detector prepared using a perovskite aqueous slurry; Wherein: a - X-ray imaging of metal hollow letters under different X-ray doses; b - X-ray imaging of a power adapter and a mobile phone camera module. Detailed implementation manners

[0018] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning that those skilled in the art understand for the present invention. In case of conflict, the definition in this specification shall prevail.

[0019] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0020] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0021] In this article, unless otherwise specified, the terms "comprising", "including", "containing", "having" or similar terms cover the meanings of "consisting of" and "mainly consisting of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A only comprises a".

[0022] In this text, for the sake of brevity in description, not all possible combinations of all technical features in each implementation or embodiment are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation or embodiment can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0023] The present invention discloses a preparation method of a perovskite aqueous slurry. Green and environmentally friendly pure water is used as a solvent to prepare a perovskite hydrogel, and this perovskite hydrogel is further used as a perovskite doctor blade coating slurry for doctor blade coating to manufacture a perovskite X-ray flat panel detector. Specifically, it includes the following steps: Step 1: Preparation of the hydrogel: Dissolve the polymer precursor in water, cool to room temperature after high-speed stirring, (where the polymer can be polyacrylamide, polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, etc.); Step 2: Preparation of the slurry: Weigh the perovskite raw materials according to the stoichiometric ratio, add them to the prepared hydrogel solution, and stir for 1 - 2 h, (the perovskite raw materials can be three-dimensional perovskite, quasi-two-dimensional perovskite, and 0-dimensional perovskite, etc.); Step 3: Fabrication of the flat panel detector: Use a high-temperature tape to limit the film thickness, doctor blade coat the prepared perovskite slurry on a pixel array thin film transistor (TFT) or a COMS substrate; then place it on a heating table at 90 °C and heat for 1 h.

[0024] Preferably, the dosage ratio of the polymer precursor to water is (7 - 10) g : (100 - 150) mL.

[0025] Preferably, the stirring for obtaining the aqueous gel is carried out at 90 - 95 °C for 2 - 3 h.

[0026] Preferably, the dosage ratio of the perovskite raw materials to the aqueous gel is (0.3 - 0.5) mmol : (3 - 5) mL.

[0027] Preferably, the stirring for obtaining the perovskite aqueous slurry is carried out at 90 - 95 °C for 1 - 2 h.

[0028] Preferably, the coating thickness of the perovskite aqueous slurry on the substrate surface is 100 - 200 microns. (The film thickness can be adjusted by changing the distance between the doctor blade and the substrate as required to obtain films of different thicknesses).

[0029] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0030] In the following examples, conventional instruments and equipment in the art are used. For the experimental methods without specific conditions noted in the following examples, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. In the following examples, various raw materials are used. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0031] Example 1 A preparation method of a perovskite aqueous slurry, comprising the following steps: 1. Dissolve 8 g of polyethylene glycol in 100 mL of deionized water, and stir for 1 h to obtain a polyethylene glycol hydrogel solution; 2. Add 3 mL of 8% polyethylene glycol hydrogel solution to 0.3 mmol of BA2MA9Pb 10 I 31 perovskite raw materials, and stir at 95 °C for 1 h to obtain a perovskite aqueous slurry.

[0032] Example 2 1. Dissolve 8 g of polyacrylamide in 100 mL of deionized water, and stir for 1 h to obtain a polyacrylamide hydrogel solution; 2. Add 3 mL of 8% polyacrylamide hydrogel solution to 0.3 mmol of BA2MA9Pb 10 I 31 perovskite raw materials, and stir at 95 °C for 1 h to obtain a perovskite aqueous slurry.

[0033] Example 3 1. Dissolve 8 g of polyvinylpyrrolidone in 100 mL of deionized water, and stir for 1 h to obtain a polyvinylpyrrolidone hydrogel solution; 2. Add 3 mL of 8% polyvinylpyrrolidone hydrogel solution to 0.3 mmol of BA2MA9Pb 10 I 31 perovskite raw materials, and stir at 95 °C for 1 h to obtain a perovskite aqueous slurry.

[0034] Example 4 1. Dissolve 8 g of polyvinyl alcohol in 100 mL of deionized water, and stir for 1 h to obtain a polyvinyl alcohol hydrogel solution; 2. Add 3 mL of 8% polyvinyl alcohol hydrogel solution to 0.3 mmol of BA2MA9Pb 10 I 31 perovskite raw materials, and stir at 95 °C for 1 h to obtain a perovskite aqueous slurry.

[0035] Example 5 A preparation method of perovskite aqueous slurry, comprising the following steps: 1. Dissolve 8 g of polyvinyl alcohol in 100 mL of deionized water, stir for 1 h to obtain a polyvinyl alcohol hydrogel solution; 2. Add 3 mL of 8% polyvinyl alcohol hydrogel solution to 0.3 mmol of perovskite raw material of MAPbI3, stir at 95 °C for 1 - 2 h to obtain perovskite aqueous slurry.

[0036] Example 6 A preparation method of perovskite aqueous slurry, comprising the following steps: 1. Dissolve 8 g of polyvinyl alcohol in 100 mL of deionized water, stir for 1 h to obtain a polyvinyl alcohol hydrogel solution; 2. Add 3 mL of 8% polyvinyl alcohol hydrogel solution to 0.3 mmol of perovskite raw material of MAPbBr3, stir at 95 °C for 1 h to obtain perovskite aqueous slurry.

[0037] Example 7 A preparation method of perovskite aqueous slurry, comprising the following steps: 1. Dissolve 7 g of polyvinyl alcohol in 150 mL of deionized water, stir for 3 h to obtain a polyvinyl alcohol hydrogel solution; 2. Add 5 mL of 8% polyvinyl alcohol hydrogel solution to 0.5 mmol of perovskite raw material of MAPbI3, stir at 90 °C for 2 h to obtain perovskite aqueous slurry.

[0038] Example 8 1. Dissolve 10 g of polyvinyl alcohol in 120 mL of deionized water, stir for 3 h to obtain a polyvinyl alcohol hydrogel solution; 2. Add 4 mL of 8% polyvinyl alcohol hydrogel solution to 0.4 mmol of perovskite raw material of BA2MA9Pb 10 I 31 and stir at 95 °C for 2 h to obtain perovskite aqueous slurry.

[0039] Application Example 1 Coat the perovskite aqueous slurry prepared in Example 4 on the ultraviolet - cleaned conductive glass ITO. The wet film thickness can be controlled by the high - temperature tape pasted at both ends of the glass sheet, with a thickness of about 200 microns. After heating at 95 °C for 2 h, evaporate 80 - nanometer - thick gold on its surface as the gold electrode. The area of the gold electrode can be controlled by the mask template, and thus a single - point detector is obtained.

[0040] Application Example 2 The perovskite aqueous slurry prepared in Example 4 was coated on the ultraviolet-cleaned conductive glass FTO. The wet film thickness could be controlled by high-temperature tapes pasted at both ends of the glass sheet, with a thickness of about 200 microns. After heating at 90 °C for 1.2 h, gold with a thickness of 80 nm was evaporated on its surface as the gold electrode. The area of the gold electrode could be controlled by a mask, and thus a single-point detector was obtained.

[0041] Application Example 3 The perovskite aqueous slurry prepared in Example 4 was coated on the ultraviolet-cleaned thin-film transistor (TFT). The wet film thickness could be controlled by high-temperature tapes pasted at both ends of the glass sheet, with a thickness of about 200 microns. After heating at 80 °C for 1 h, gold with a thickness of 160 nm was evaporated on its surface as the gold electrode, obtaining a flat-panel detector. The area of the flat-panel detector was determined by the area of the TFT.

[0042] Application Example 4 The perovskite aqueous slurry prepared in Example 4 was coated on the ultraviolet-cleaned CMOS. The wet film thickness could be controlled by high-temperature tapes pasted at both ends of the glass sheet, with a thickness of about 200 microns. After heating at 85 °C for 1 h, gold with a thickness of 160 nm was evaporated on its surface as the gold electrode, obtaining a flat-panel detector. The area of the flat-panel detector was determined by the area of the CMOS.

[0043] Figure 1 Figure 14 is a cross-sectional scanning electron microscope image of the film formed by coating the perovskite aqueous slurry on the substrate surface. It can be seen from the figure that the film is 200 microns thick; from Figure 2 the surface scanning electron microscope image, it can be seen that the surface of the film is very flat, indicating that the film is conducive to absorbing X-rays and conducting carriers. This perovskite aqueous slurry is suitable for blade coating to prepare X-ray flat-panel detectors.

[0044] Figure 3 Figure 15 is a graph showing the variation of the X-ray sensitivity of the flat-panel detector prepared with the perovskite aqueous slurry with voltage. It can be seen from the figure the variation of the sensitivity of the device with voltage, and the maximum can reach 10099 µC Gy air s -1 .

[0045] Figure 4 Figure 16 is the lower limit of X-ray detection of the flat-panel detector prepared with the perovskite aqueous slurry. It can be seen that the lowest detection limit is as low as 19.8 nGy air s -1 , indicating that the detector has a strong detection ability for low-dose X-rays.

[0046] Figure 5The figure shows the physical diagram of the flat panel detector in Application Example 4, the surface roughness measured by atomic force microscopy, and the imaging diagrams under different light intensities. The atomic force microscope scanned a 100 µm × 100 µm area, and the calculated roughness was 0.65 µm. And the optical imaging under different light intensities.

[0047] Figure 6 For X-ray imaging, the letters can still be clearly distinguished at a dose of 22 µGy air (only 1 / 5 of the medical imaging dose of 100 µGy air . On the right is the physical object imaging, and the interior of the power adapter and the interior of the mobile phone camera module can be clearly seen at a dose of 71.5 µGy air (only 3 / 4 of the medical imaging dose of 100 µGy air ), indicating that the flat panel detector has excellent imaging capabilities The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention fall within the protection scope of the claims of the present invention.

Claims

1. A preparation method of a perovskite aqueous slurry, characterized in that, It includes the following steps: Dissolve the polymer precursor in water, and stir to obtain an aqueous gel; Add the perovskite raw material to the aqueous gel, and stir to obtain a perovskite aqueous slurry; Among them, the polymer precursor is one or more of polyacrylamide, polyethylene glycol, polyvinylpyrrolidone, and polyvinyl alcohol.

2. The preparation method of a perovskite aqueous slurry according to claim 1, wherein, The dosage ratio of the polymer precursor to water is (7~10) g:(100~150) mL.

3. The preparation method of a perovskite aqueous slurry according to claim 1, wherein The stirring for obtaining the aqueous gel is carried out at 90~95 °C for 1~3 h.

4. The preparation method of a perovskite aqueous slurry according to claim 1, wherein The perovskite raw material is one or more of three-dimensional perovskite, quasi-two-dimensional perovskite, and 0-dimensional perovskite.

5. The preparation method of a perovskite aqueous slurry according to claim 1, characterized in that, The dosage ratio of the perovskite raw material to the aqueous gel is (0.3~0.5) mmol:(3~5) mL.

6. The preparation method of a perovskite aqueous slurry according to claim 1, characterized in that, The stirring for obtaining the perovskite aqueous slurry is carried out at 90~95 °C for 1~2 h.

7. A perovskite aqueous slurry, characterized in that, It is prepared by using the preparation method described in any one of claims 1~6.

8. Use of a perovskite aqueous slurry as described in claim 7 in the preparation of a flat panel detector, characterized in that, It includes the following steps: Coat the perovskite aqueous slurry on the surface of the substrate to obtain a perovskite solution-deposited functional film, heat it, and then evaporate the electrode to obtain a flat panel detector; The substrate is a pixel array thin film transistor or a COMS substrate.

9. Use of a perovskite aqueous slurry in the preparation of a flat panel detector according to claim 8, characterized in that, The coating thickness of the perovskite aqueous slurry on the surface of the substrate is 100~200 microns.

10. The application of a perovskite aqueous slurry in the preparation of a flat panel detector according to claim 8, characterized in that, The heating temperature is 90~95 °C, and the time is 1~2 h.

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