A preparation method of a TFT integrated X-ray detector based on yellow phase FAPbI3 precursor film limited phase change

Abstract

The application discloses a preparation method of a TFT integrated X-ray detector based on yellow-phase FAPbI3 precursor film limited phase change, S1, FAI and PbI2 with a molar ratio of 1:1 are weighed and added into a solvent system, and are fully stirred for 20-30 hours to obtain one-dimensional vacuum tubular yellow-phase FAPbI3 polycrystalline particles, the obtained particles are centrifuged, washed and dried for standby, S2, the hollow yellow-phase FAPbI3 powder obtained in S1 is added into an organic solvent, and is fully stirred for 2-5 hours to prepare a precursor slurry with a concentration of 2-10 M, the application uses the hollow yellow-phase FAPbI3 precursor to construct a thick film on a TFT array substrate, and obtains a TFT integrated X-ray detector with a dense black-phase FAPbI3 absorbing layer through limited heat pressing phase change, and the problems of solvent retention at the bottom, film layer holes and cracks, weak yellow-phase response, loose film layer after ordinary heat annealing phase change, difficulty of the TFT substrate in bearing high-pressure heat pressing and uneven pixel response in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detector technology, specifically to a method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film-confined phase transition. Background Technology

[0002] Direct X-ray detectors can directly convert incident X-rays into electrical signals within a semiconductor absorption layer. Compared to indirect detectors coupled with a scintillator and photodiode, this reduces spatial resolution loss caused by light scattering and crosstalk, making them valuable for applications in low-dose medical imaging, industrial non-destructive testing, security inspection, and scientific instruments. Perovskite materials, with their high X-ray absorption capacity, solution processability, and potential for large-area low-temperature fabrication, are important candidate materials for the absorption layer of direct X-ray detectors.

[0003] However, unlike the nanoscale or submicron-scale thin films commonly used in perovskite photovoltaic devices, X-ray detectors typically require perovskite absorber layers with thicknesses ranging from tens of micrometers to millimeters to improve X-ray absorption efficiency. Thick film fabrication often employs high-concentration precursor slurries, crystal powder suspensions, or powder-filled film deposition processes. Since the thick film drying process usually proceeds from the top surface to the bottom surface, solvent evaporation and structural densification occur first on the top surface. Solvent at the bottom of the film and near the TFT pixel electrodes is difficult to remove in time, easily leading to defects such as residual solvent at the bottom, voids, bulges, cracks, and discontinuous interface contacts. These defects can cause localized electric field distortion, increased dark current, uneven pixel response, and limit the imaging quality of large-area TFTs.

[0004] In existing technologies, black-phase FAPbI3 possesses high lead-iodine content, good X-ray absorption potential, and excellent photoelectric properties. However, the tens to millimeter-scale thick films required for X-ray detectors are prone to defects such as pores, cracks, and discontinuous interface contacts due to solvent residue during fabrication, making it difficult to achieve non-destructive heterogeneous integration with the readout circuit. Therefore, how to achieve a high-performance black-phase FAPbI3 perovskite thick-film X-ray detector with no solvent retention, no film pores or cracks at the bottom, a dense film after phase transition, and further improved top electrode interface quality and device detection performance without damaging the bottom readout substrate and the overall device structure remains a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] 1. Technical problems to be solved:

[0007] To address the problems mentioned above in existing perovskite thick-film X-ray detectors, such as bottom solvent retention, film pores and cracks, weak yellow phase response, loose film after ordinary thermal annealing phase transition, inability of TFT substrates to withstand high-pressure hot pressing, and uneven pixel response, this invention is proposed.

[0008] Therefore, the purpose of this invention is to provide a method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film-confined phase transition, which can effectively solve the above-mentioned problems.

[0009] 2. Technical Solution:

[0010] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0011] Includes the following steps:

[0012] S1. Weigh FAI and PbI2 in a molar ratio of 1:1 and add them to the solvent system. Stir thoroughly for 20-30 hours to obtain one-dimensional yellow phase FAPbI3 polycrystalline particles in a vacuum tube shape. The obtained particles are centrifuged, washed and dried for later use.

[0013] S2. Add the hollow yellow phase FAPbI3 powder obtained in S1 to an organic solvent and stir thoroughly for 2-5 hours to prepare a precursor slurry with a concentration of 2-10M.

[0014] S3. On a slot coater, adjust the appropriate blade distance and use a blade coating method to uniformly and controllably coat the perovskite precursor slurry obtained in S2 onto the pixel area of ​​a commercial TFT substrate.

[0015] S4. The TFT device loaded with perovskite paste obtained in S3 is pre-annealed at 30-40°C for 12-24 hours to obtain a TFT substrate loaded with a yellow phase FAPbI3 thick film.

[0016] S5. Cover the surface of the TFT substrate loaded with yellow phase FAPbI3 thick film with a heat-resistant, low-adhesion, and releasable confinement pad, and place it in a temperature-controlled lamination equipment. Pressurize and heat it at 100-200℃ and 3-20MPa for 8-12 hours to convert the yellow phase FAPbI3 in situ into black phase FAPbI3 on ​​the TFT substrate.

[0017] S6. After hot pressing, the device is cooled to room temperature while maintaining natural pressing, and then the confinement pad is removed to obtain a TFT substrate of thin film crystal loaded with black phase FAPbI3 thick film.

[0018] S7. Place the device obtained in S6 in a vacuum evaporation equipment to prepare a top Au common electrode on a black phase FAPbI3 thick film to obtain a TFT-integrated black phase FAPbI3 direct X-ray detector. After preparing the top metal common electrode, the obtained TFT-integrated black phase FAPbI3 direct X-ray detector and the PCB readout circuit board are placed in a shielded lead box for use, and the inside of the detector housing is kept in a dry environment.

[0019] In a preferred embodiment of the method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition according to the present invention, the solvent in S1 can be either acetonitrile or isopropanol.

[0020] As a preferred embodiment of the method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition according to the present invention, the organic solvent in S2 may be one of γ-butyrolactone, 2-methoxyethanol, N,N-dimethylformamide, dimethyl sulfoxide, and isopropanol.

[0021] In a preferred embodiment of the method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition according to the present invention, in step S3, the distance between the doctor blade and the substrate is 100-1000 μm, and the thickness of the final polycrystalline film is controlled by the distance of the doctor blade.

[0022] As a preferred embodiment of the method for fabricating a TFT integrated X-ray detector based on a confined phase transition of a yellow-phase FAPbI3 precursor film according to the present invention, the pre-annealing in S4 does not completely transform the yellow-phase FAPbI3 into the black-phase FAPbI3, but mainly completes the film formation and solvent removal. The main transformation from yellow to black phase occurs during the confined hot-pressing phase transition process in S6.

[0023] In a preferred embodiment of the method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition according to the present invention, the confined spacer in step S5 is one of a polytetrafluoroethylene spacer, a silicone spacer, and a PI spacer.

[0024] In a preferred embodiment of the method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition according to the present invention, in step S7, the thickness of the top Au common electrode deposited by vapor deposition is 80–120 nm.

[0025] 3. Beneficial effects:

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] This method for fabricating a TFT integrated X-ray detector based on a confined phase transition using a yellow-phase FAPbI3 precursor film:

[0028] 1. This invention uses hollow yellow-phase FAPbI3 as a precursor for thick film formation, rather than directly as the final functional phase. This hollow structure provides built-in solvent drainage channels during the thick film drying stage, which can alleviate solvent retention at the bottom caused by top-down drying of the thick film, reducing internal voids, bulges, and interface debonding.

[0029] 2. This invention utilizes the characteristic that yellow phase FAPbI3 is easy to form low-dimensional or porous aggregated structures. First, a relatively dense yellow phase thick film is formed in the TFT pixel area, and then the black phase is converted. This avoids the problems of uneven dispersion and bottom defects that are easy to occur in the direct black phase paste thick film forming.

[0030] 3. In this invention, confined hot pressing is applied simultaneously during the transformation from yellow phase to black phase, so that lattice reconstruction, grain rearrangement and thick film densification occur at the same time, which can reduce the structural looseness, microcracks and film debonding that occur after ordinary hot annealing phase transformation.

[0031] 4. This invention uses low-adhesion heat-resistant pads such as polytetrafluoroethylene as confined hot-pressing interfaces, which can uniformly transmit pressure at phase transition temperatures and reduce adhesion between the perovskite thick film and the pressure plate. After demolding, the film layer remains intact, which is suitable for the fabrication of TFT array devices.

[0032] 5. This invention enables the TFT glass substrate to complete thick film phase transformation and densification without cracking or significant damage to the readout structure by controlling the hot-pressing pressure window.

[0033] 6. The black phase FAPbI3 thick film obtained by this invention has a more continuous contact with the TFT pixel electrode and a smoother top electrode deposition surface, which helps to reduce dark current, improve pixel response uniformity and X-ray imaging quality. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0035] Figure 1 The images show SEM images and physical photos of hollow tubular yellow-phase FAPbI3 precursor particles prepared according to Example 1 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0036] Figure 2This is a physical image of a yellow-phase perovskite thick-film X-ray detector prepared according to Example 1 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0037] Figure 3 This is a physical image of a black phase perovskite thick-film X-ray detector prepared according to Example 1 of the fabrication method of a TFT integrated X-ray detector based on a yellow phase FAPbI3 precursor film confined phase transition of the present invention.

[0038] Figure 4 This is a SEM image of a black phase perovskite thick-film X-ray detector prepared according to Example 1 of the fabrication method of a TFT integrated X-ray detector based on a yellow phase FAPbI3 precursor film confined phase transition of the present invention.

[0039] Figure 5 The image shows the XRD pattern of a perovskite thick-film X-ray detector prepared according to Example 1 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0040] Figure 6 The image shows the long-term stability XRD test results of a perovskite thick-film X-ray detector prepared in a dry lead box, according to Example 1 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0041] Figure 7 This is a perovskite thick-film X-ray detector prepared in Example 1 of the present invention, which is a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition. The detector has multiple bright and dark state images within six months.

[0042] Figure 8 This is an imaging test image of a perovskite thick-film X-ray detector prepared according to Example 1 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0043] Figure 9 This is a physical image of a perovskite thick-film X-ray detector prepared according to Example 2 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0044] Figure 10 This is a bright-dark state image of a perovskite thick-film X-ray detector prepared according to Example 2 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0045] Figure 11This is a physical image of a perovskite thick-film X-ray detector prepared according to Example 3 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0046] Figure 12 This is a bright-dark state image of a perovskite thick-film X-ray detector prepared according to Example 3 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0047] Figure 13 This is a physical image of a perovskite thick-film X-ray detector prepared according to Example 4 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention.

[0048] Figure 14 This is a physical image of a perovskite thick-film X-ray detector prepared according to Example 5 of the fabrication method of a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition of the present invention. Detailed Implementation

[0049] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0050] This invention is described in detail with reference to the schematic diagrams. When describing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0051] The orientation or positional relationship indicated in the terminology is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0052] The term "connection method" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0054] This invention provides a schematic diagram of the overall structure of one embodiment of a method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film-confined phase transition, including:

[0055] Please see Figures 1-14 This embodiment describes a method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film-confined phase transition, comprising the following steps:

[0056] S1. Weigh FAI and PbI2 in a molar ratio of 1:1 and add them to the solvent system. Stir thoroughly for 20-30 hours to obtain one-dimensional yellow phase FAPbI3 polycrystalline particles in a vacuum tube shape. The obtained particles are centrifuged, washed and dried for later use.

[0057] S2. Add the hollow yellow phase FAPbI3 powder obtained in S1 to an organic solvent and stir thoroughly for 2-5 hours to prepare a precursor slurry with a concentration of 2-10M.

[0058] S3. On a slot coater, adjust the appropriate blade distance and use a blade coating method to uniformly and controllably coat the perovskite precursor slurry obtained in S2 onto the pixel area of ​​a commercial TFT substrate.

[0059] S4. The TFT device loaded with perovskite paste obtained in S3 is pre-annealed at 30-40°C for 12-24 hours to obtain a TFT substrate loaded with a yellow phase FAPbI3 thick film.

[0060] S5. Cover the surface of the TFT substrate loaded with yellow phase FAPbI3 thick film with a heat-resistant, low-adhesion, and releasable confinement pad, and place it in a temperature-controlled lamination equipment. Pressurize and heat it at 100-200℃ and 3-20MPa for 8-12 hours to convert the yellow phase FAPbI3 in situ into black phase FAPbI3 on ​​the TFT substrate.

[0061] S6. After hot pressing, the device is cooled to room temperature while maintaining natural pressing, and then the confinement pad is removed to obtain a TFT substrate of thin film crystal loaded with black phase FAPbI3 thick film.

[0062] S7. Place the device obtained in S6 in a vacuum evaporation equipment to prepare a top Au common electrode on a black phase FAPbI3 thick film, and obtain a TFT-integrated black phase FAPbI3 direct X-ray detector.

[0063] Specifically, the solvent in S1 can be either acetonitrile or isopropanol.

[0064] Furthermore, specifically, the organic solvent in S2 can be one of γ-butyrolactone, 2-methoxyethanol, N,N-dimethylformamide, dimethyl sulfoxide, or isopropanol.

[0065] Next, specifically in S3, the distance between the doctor blade and the substrate is 100-1000 μm, and the final thickness of the polycrystalline film is controlled by the distance of the doctor blade.

[0066] Meanwhile, specifically, the pre-annealing in S4 does not completely transform the yellow phase FAPbI3 into the black phase FAPbI3, but mainly completes the film formation and solvent removal. The main transformation from the yellow phase to the black phase occurs during the confined hot pressing phase transformation process in S6.

[0067] Specifically, the confinement gasket in S5 is one of the following: a polytetrafluoroethylene gasket, a silicone gasket, or a PI gasket.

[0068] Subsequently, specifically in S7, the thickness of the top Au common electrode deposited by vapor deposition is 80–120 nm.

[0069] Example 1

[0070] Weigh out FAI and PbI2 in a molar ratio of 1:1 and add them to the solvent system. Stir thoroughly for 20–30 h to obtain hollow particles, tubular particles, or porous aggregated particles with yellow FAPbI3 as the main component. The obtained particles are then centrifuged, washed, and dried for later use.

[0071] Weigh out 5 mg / ml of yellow phase FAPbI3 and dissolve it in 2-methoxyethanol solution, and stir thoroughly for 60 min to obtain perovskite suspension precursor slurry.

[0072] On a slot coater, the perovskite suspension precursor slurry obtained in S2 is uniformly coated onto the TFT backplane using a scraping method.

[0073] The yellow phase thick film obtained from S3 was pre-dried at 20–30 °C for 12–24 h.

[0074] Once the yellow phase thick film reaches a pressure-bearing state, a polytetrafluoroethylene gasket is placed on the upper surface of the thick film.

[0075] The TFT / yellow phase FAPbI3 thick film covered with a polytetrafluoroethylene gasket was placed in a temperature-controlled lamination device and kept at 100-200℃ and 3-10MPa for 8-12 hours to allow the yellow phase FAPbI3 to be converted in situ to black phase FAPbI3 on ​​the TFT substrate.

[0076] After hot pressing, the device was cooled to room temperature while maintaining natural compression, and then the confinement pad was removed to obtain a dense black phase FAPbI3 thick film.

[0077] The device obtained in S7 was placed in a vacuum evaporation apparatus to prepare a top Au common electrode on a black phase FAPbI3 thick film, resulting in a TFT integrated black phase FAPbI3 direct X-ray detector, which was then placed in a dry lead box for use.

[0078] In this example, Figure 1 SEM (Semiconductor Electron Microscopy) tests showed that the yellow-phase FAPbI3 powder has a hollow structure.

[0079] Figure 2 The image shows the actual fabricated yellow-phase perovskite thick-film X-ray detector, which can be seen to have a smooth and dense surface.

[0080] Figure 3 The physical image of the black phase perovskite thick film X-ray detector shows that the yellow phase FAPbI3 is completely transformed in situ into the black phase FAPbI3 on ​​the TFT substrate.

[0081] Figure 4 In SEM electron microscopy testing, the dense cross-section of the thick film and its continuous contact with the TFT pixel electrode are conducive to the continuous deposition of subsequent metal top electrodes, especially gold electrodes. This significantly improves the actual contact area and interface bonding quality of the metal / perovskite interface, thereby reducing dark current and noise and improving charge collection uniformity.

[0082] Figure 5 XRD analysis showed that the characteristic peaks of the yellow phase weakened or disappeared after hot pressing, while the characteristic peaks of the black phase FAPbI3 were enhanced.

[0083] Figure 6 The image shows the XRD test results of the perovskite material in a dry lead box. Thanks to the top electrode encapsulation and the dry lead box working environment, the black phase FAPbI3 exhibits good structural stability within six months.

[0084] Figure 7 These are multiple bright and dark state images of the perovskite X-ray detector in this example over a period of six months. They exhibit stable bright and dark field characteristics, indicating good pixel uniformity and demonstrating improved charge collection uniformity.

[0085] Figure 8 The image presented is an imaging test image of the fabricated perovskite thick-film X-ray detector. The image quality is excellent and the picture is clear.

[0086] Example 2

[0087] Weigh out 5 mg / ml of black phase FAPbI3 directly, dissolve it in 2-methoxyethanol solution, and stir thoroughly for 60 min to obtain perovskite suspension precursor slurry.

[0088] On a slot coater, the perovskite suspension precursor slurry obtained in S2 is uniformly coated onto the TFT backplane using a scraping method.

[0089] The black phase thick film obtained by S3 was pre-dried at 20-30℃ for 12-24 hours.

[0090] After the black phase thick film reaches a pressure-bearing state, a polytetrafluoroethylene gasket is placed on the upper surface of the thick film.

[0091] The TFT / black phase FAPbI3 thick film covered with a polytetrafluoroethylene gasket was placed in a temperature-controlled lamination apparatus and kept at 100–200°C and 3–10 MPa for 8–12 hours.

[0092] After hot pressing, the device was cooled to room temperature while maintaining natural compression, and then the confinement pad was removed to obtain a black phase FAPbI3 thick film.

[0093] The device obtained in S7 was placed in a vacuum evaporation apparatus to prepare a top Au common electrode on a black phase FAPbI3 thick film, thus obtaining a TFT integrated black phase FAPbI3 direct X-ray detector.

[0094] The perovskite thick film prepared in this example is as follows: Figure 9 As shown, the presence of holes on the surface makes it rough, which will significantly affect the detector's detection performance. The detector fabricated in this example is as follows. Figure 10 The images showing both light and dark states indicate that the pixels are not uniform, proving that the charge collection is uneven.

[0095] Example 3

[0096] Weigh out FAI and PbI2 in a molar ratio of 1:1 and add them to the solvent system. Stir thoroughly for 20–30 h to obtain hollow particles, tubular particles, or porous aggregated particles with yellow FAPbI3 as the main component. The obtained particles are then centrifuged, washed, and dried for later use.

[0097] Weigh out 5 mg / ml of yellow phase FAPbI3 and dissolve it in 2-methoxyethanol solution, and stir thoroughly for 60 min to obtain perovskite suspension precursor slurry.

[0098] On a slot coater, the perovskite suspension precursor slurry obtained in S2 is uniformly coated onto the TFT backplane using a scraping method.

[0099] The yellow phase thick film obtained from S3 was pre-dried at 20–30 °C for 12–24 h.

[0100] The yellow phase thick film obtained in S4 was kept at 100-200℃ for 8-12 hours to allow the yellow phase FAPbI3 to be converted in situ to the black phase FAPbI3 on ​​the TFT substrate.

[0101] The device obtained from S5 was placed in a vacuum evaporation apparatus to prepare a top Au common electrode on a black phase FAPbI3 thick film, thus obtaining a TFT integrated black phase FAPbI3 direct X-ray detector.

[0102] The perovskite thick film prepared in this example is as follows: Figure 11 As shown, after only hot annealing, microcracks appeared in the thick film due to the lack of vertical confinement pressure during the phase transition. The perovskite X-ray detector in this example was subjected to relevant photoelectric performance tests, such as... Figure 12 As shown, the pixels are not uniform, indicating that the charge collection is uneven.

[0103] Example 4

[0104] Weigh out FAI and PbI2 in a molar ratio of 1:1 and add them to the solvent system. Stir thoroughly for 20–30 h to obtain hollow particles, tubular particles, or porous aggregated particles with yellow FAPbI3 as the main component. The obtained particles are then centrifuged, washed, and dried for later use.

[0105] Weigh out 5 mg / ml of yellow phase FAPbI3 and dissolve it in 2-methoxyethanol solution, and stir thoroughly for 60 min to obtain perovskite suspension precursor slurry.

[0106] On a slot coater, the perovskite suspension precursor slurry obtained in S2 is uniformly coated onto the TFT backplane using a scraping method.

[0107] The yellow phase thick film obtained from S3 was pre-dried at 20–30 °C for 12–24 h.

[0108] After the yellow phase thick film reaches a pressure-bearing state, it is placed in a temperature-controlled lamination device and kept at 100-200℃ and 3-10MPa for 8-12 hours to allow the yellow phase FAPbI3 to be converted in situ into the black phase FAPbI3 on ​​the TFT substrate.

[0109] After hot pressing, the device was cooled to room temperature while maintaining natural pressing to obtain a black phase FAPbI3 thick film.

[0110] The device obtained in S7 was placed in a vacuum evaporation apparatus to prepare a top Au common electrode on a black phase FAPbI3 thick film, thus obtaining a TFT integrated black phase FAPbI3 direct X-ray detector.

[0111] The perovskite thick film prepared in this example is as follows: Figure 13 The problem shown is that the pressure plate adheres and the membrane surface is damaged, making effective detection impossible.

[0112] Example 5

[0113] Weigh out FAI and PbI2 in a molar ratio of 1:1 and add them to the solvent system. Stir thoroughly for 20–30 h to obtain hollow particles, tubular particles, or porous aggregated particles with yellow FAPbI3 as the main component. The obtained particles are then centrifuged, washed, and dried for later use.

[0114] Weigh out 5 mg / ml of yellow phase FAPbI3 and dissolve it in 2-methoxyethanol solution, and stir thoroughly for 60 min to obtain perovskite suspension precursor slurry.

[0115] On a slot coater, the perovskite suspension precursor slurry obtained in S2 is uniformly coated onto the TFT backplane using a scraping method.

[0116] The yellow phase thick film obtained from S3 was pre-dried at 20–30 °C for 12–24 h.

[0117] Once the yellow phase thick film reaches a pressure-bearing state, a polytetrafluoroethylene gasket is placed on the upper surface of the thick film.

[0118] The TFT / yellow phase FAPbI3 thick film covered with a polytetrafluoroethylene gasket was placed in a temperature-controlled lamination device and kept at 100-200℃ and 15-20MPa for 8-12 hours to allow the yellow phase FAPbI3 to be converted in situ to black phase FAPbI3 on ​​the TFT substrate.

[0119] After hot pressing, the device was cooled to room temperature while maintaining natural compression, and then the confinement pad was removed to obtain a dense black phase FAPbI3 thick film.

[0120] The device obtained in S7 was placed in a vacuum evaporation apparatus to prepare a top Au common electrode on a black phase FAPbI3 thick film, thus obtaining a TFT integrated black phase FAPbI3 direct X-ray detector.

[0121] The perovskite thick film prepared in this example is as follows: Figure 14 The TFT glass substrate shown is cracked, making effective detection impossible.

[0122] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for fabricating a TFT integrated X-ray detector based on a confined phase transition of a yellow-phase FAPbI3 precursor film, characterized in that, Includes the following steps: S1. Weigh FAI and PbI2 in a molar ratio of 1:1 and add them to the solvent system. Stir thoroughly for 20-30 hours to obtain one-dimensional yellow phase FAPbI3 polycrystalline particles in a vacuum tube shape. The obtained particles are centrifuged, washed and dried for later use. S2. Add the hollow yellow phase FAPbI3 powder obtained in S1 to an organic solvent and stir thoroughly for 2-5 hours to prepare a precursor slurry with a concentration of 2-10M. S3. On a slot coater, adjust the appropriate blade distance and use a blade coating method to uniformly and controllably coat the perovskite precursor slurry obtained in S2 onto the pixel area of ​​a commercial TFT substrate. S4. The TFT device loaded with perovskite paste obtained in S3 is pre-annealed at 30-40°C for 12-24 hours to obtain a TFT substrate loaded with a yellow phase FAPbI3 thick film. S5. Cover the surface of the TFT substrate loaded with yellow phase FAPbI3 thick film with a heat-resistant, low-adhesion, and releasable confinement pad, and place it in a temperature-controlled lamination equipment. Pressurize and heat it at 100-200℃ and 3-20MPa for 8-12 hours to convert the yellow phase FAPbI3 in situ into black phase FAPbI3 on ​​the TFT substrate. S6. After hot pressing, the device is cooled to room temperature while maintaining natural pressing, and then the confinement pad is removed to obtain a TFT substrate of thin film crystal loaded with black phase FAPbI3 thick film. S7. Place the device obtained in S6 in a vacuum evaporation equipment to prepare a top Au common electrode on a black phase FAPbI3 thick film to obtain a TFT-integrated black phase FAPbI3 direct X-ray detector. After preparing the top metal common electrode, the obtained TFT-integrated black phase FAPbI3 direct X-ray detector and the PCB readout circuit board are placed in a shielded lead box for use, and the inside of the detector housing is kept in a dry environment.

2. The fabrication method of the TFT integrated X-ray detector based on the confined phase transition of the yellow-phase FAPbI3 precursor film according to claim 1, characterized in that, The solvent in S1 can be either acetonitrile or isopropanol.

3. The method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film-confined phase transition according to claim 2, characterized in that, The organic solvent in S2 can be one of γ-butyrolactone, 2-methoxyethanol, N,N-dimethylformamide, dimethyl sulfoxide, and isopropanol.

4. The method for fabricating a TFT integrated X-ray detector based on a confined phase transition of a yellow-phase FAPbI3 precursor film according to claim 3, characterized in that, In step S3, the distance between the doctor blade and the substrate is 100-1000 μm, and the final thickness of the polycrystalline film is controlled by the distance of the doctor blade.

5. The fabrication method of the TFT integrated X-ray detector based on the confined phase transition of the yellow-phase FAPbI3 precursor film according to claim 4, characterized in that, The pre-annealing in S4 does not completely transform the yellow phase FAPbI3 into the black phase FAPbI3, but mainly completes the film formation and solvent removal. The main transformation from yellow to black phase occurs during the confined hot-pressing phase transformation process in S6.

6. The method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film-confined phase transition according to claim 5, characterized in that, The confinement gasket in S5 is one of a polytetrafluoroethylene gasket, a silicone gasket, and a PI gasket.

7. The method for fabricating a TFT integrated X-ray detector based on a yellow-phase FAPbI3 precursor film confined phase transition according to claim 6, characterized in that, In S7, the thickness of the top Au common electrode deposited by vapor deposition is 80–120 nm.

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