Composite perovskite thick film x-ray detector interface processing and preparation method thereof

Abstract

This invention discloses an interface treatment and preparation method for a composite perovskite thick-film X-ray detector. The method includes the following steps: S1: Weigh polycrystalline perovskite precursor powder, dissolve it in an organic solution, and stir thoroughly to obtain a perovskite suspension precursor slurry; S2: On a slot coater, uniformly coat the perovskite suspension precursor slurry obtained in step S1 onto an ITO or TFT backplane using a scraping method; S3: Cover the coated precursor slurry in step S2 with a polymer surface-shaping film and anneal to form the perovskite absorption layer; S4: Add a removal agent to the device obtained in step S3 to remove the surface-shaping film, obtaining a dense perovskite X-ray absorption layer. This interface treatment and preparation method for a composite perovskite thick-film X-ray detector solves the shortcomings of existing thick-film perovskite absorption layers, such as large surface roughness, poor metal top electrode deposition quality, high leakage current, and poor imaging uniformity.

Description

Technical Field

[0001] This invention relates to the field of X-ray detection technology, specifically to an interface treatment and preparation method for a composite perovskite thick-film X-ray detector. Background Technology

[0002] With the development of industrial non-destructive testing, security inspection, medical imaging, and scientific instruments, direct X-ray detectors have attracted widespread attention due to their ability to directly convert X-rays into electrical signals, offering advantages such as fast response speed, high spatial resolution, and wide linear dynamic range. Perovskite materials, with their high X-ray absorption coefficient, excellent carrier transport properties, solution processability, and compatibility with large-area substrates, have become important candidate materials for the absorption layer of direct X-ray detectors. In particular, lead halide perovskite materials, such as MAPbI3, FAPbI3, CsPbBr3, as well as mixed cation and mixed halide perovskites, show promising application prospects in the field of X-ray detection.

[0003] However, unlike thin-film devices commonly used in perovskite photovoltaics, X-ray detectors often require high-concentration precursor slurries to prepare perovskite absorption layers on the micrometer scale or even thicker to ensure sufficient X-ray absorption thickness. High-concentration suspensions, during processes like blade coating, slot coating, or other thick-film deposition, can easily lead to increased surface roughness, more pores, and significant local undulations in the absorption layer. These problems further affect the deposition quality of the subsequent metal top electrode, resulting in discontinuous electrode coverage, reduced actual contact area, local electric field distortion, increased leakage current, and uneven pixel response, thus limiting the device's imaging performance.

[0004] In existing technologies, hot pressing can improve the surface smoothness and density of thick films to some extent. However, for devices already integrated with TFT readout arrays, the overall hot pressing process suffers from insufficient compatibility and is prone to damaging the bottom readout structure. Therefore, how to effectively shape the upper surface of perovskite thick films without damaging the bottom readout substrate and the overall device structure, and further improve the top electrode interface quality and device detection performance, 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, such as large surface roughness of existing thick-film perovskite absorber layers, poor deposition quality of metal top electrodes, high leakage current, and poor imaging uniformity, this invention is proposed.

[0008] Therefore, the purpose of this invention is to provide an interface treatment and preparation method for a composite perovskite thick-film X-ray detector. This invention can effectively solve the problems of large surface roughness of existing thick-film perovskite absorption layers, poor deposition quality of metal top electrodes, high leakage current, and poor imaging uniformity.

[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 out polycrystalline perovskite precursor powder, dissolve it in an organic solution, and stir thoroughly to obtain perovskite suspension precursor slurry;

[0013] S2: On a slot coater, the perovskite suspension precursor slurry obtained in step S1 is uniformly coated onto the ITO or TFT backplane using a scraping method.

[0014] S3: Cover the precursor slurry coated in step S2 with a polymer surface shaping film and anneal it to form the perovskite absorption layer.

[0015] S4: A removal agent is dropped onto the device obtained in step S3 to remove the surface shaping film, resulting in a dense perovskite X-ray absorbing layer.

[0016] S5: Place the device obtained in step S4 into a vacuum evaporation apparatus and deposit the Au common electrode at the top to obtain a perovskite X-ray detector.

[0017] As a preferred embodiment of the interface treatment and preparation method of the composite perovskite thick film X-ray detector of the present invention, in step S1, the polycrystalline perovskite precursor powder is weighed at 3-10 mol / L and the stirring time is 30-60 min.

[0018] In a preferred embodiment of the interface treatment and preparation method of the composite perovskite thick film X-ray detector of the present invention, the organic solvent in step S1 is either γ-butyrolactone or 2-methoxyethanol.

[0019] As a preferred embodiment of the interface processing and preparation method of the composite perovskite thick film X-ray detector of the present invention, in step S1, the polycrystalline perovskite precursor component is one of methylamine lead iodide perovskite, formamidinium lead iodide perovskite, cesium lead bromide perovskite or trication perovskite.

[0020] In a preferred embodiment of the interface treatment and preparation method of the composite perovskite thick film X-ray detector of the present invention, in step S2, the distance between the scraper and the substrate is 100-1000 μm.

[0021] As a preferred embodiment of the interface treatment and preparation method of the composite perovskite thick film X-ray detector of the present invention, in step S3, the annealing process is annealing at 60-100℃ for 30-60 min.

[0022] As a method for preparing the interface of a composite perovskite thick-film X-ray detector according to the present invention, the method further includes the following steps:

[0023] The organic solvent selected is capable of dissolving polycrystalline perovskite precursor powder and has a high saturated vapor pressure to ensure effective solvent evaporation and reduce solvent residue in the perovskite thick film. The organic solvent is γ-butyrolactone and / or 2-methoxyethanol.

[0024] The thickness of the final polycrystalline film is controlled by the distance of the scraper.

[0025] Temperature control, a lower annealing temperature helps to reduce residual tensile stress in the thick film, and the surface shaping film is one of polydimethylsiloxane film, polymethyl methacrylate film and polystyrene film;

[0026] The selected solvents are toluene, chlorobenzene, acetone, chloroform, and dichloromethane, which are incompatible with perovskite.

[0027] Evaporation deposition, with the thickness of the top common electrode being 80-120 nm.

[0028] 3. Beneficial effects:

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] Interface treatment and preparation method of this composite perovskite thick-film X-ray detector:

[0031] 1. This invention introduces a removable surface shaping film onto the surface of a high-concentration perovskite thick film, thereby effectively reducing the surface roughness and improving the surface smoothness of the film without changing its high X-ray absorption capacity;

[0032] 2. The surface shaping film of the present invention can flexibly constrain and shape the upper surface of the thick film during the annealing process, reduce surface pores, particle protrusions and undulating structures, and help to form a more uniform, continuous and dense upper surface;

[0033] 3. The smooth perovskite thick film formed by the surface shaping of this invention is beneficial to the continuous deposition of subsequent metal top electrodes, especially gold electrodes, and significantly improves the actual contact area and interface bonding quality of the metal / perovskite interface.

[0034] 4. The improved quality of the top electrode interface in this invention helps to establish a more uniform vertical electric field distribution, reduce local field enhancement, local leakage and current congestion caused by surface roughness and undulation, thereby reducing dark current and noise and improving charge collection uniformity.

[0035] 5. This invention is particularly suitable for thick-film X-ray detectors integrated with TFT arrays, and can achieve upper surface optimization without overall hot pressing of the bottom TFT structure, thus having good process compatibility and large-area imaging application prospects;

[0036] 6. This invention is applicable to a variety of organic-inorganic hybrid perovskite and all-inorganic perovskite systems, with a wide range of protection and strong versatility. Attached Figure Description

[0037] 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:

[0038] Figure 1 This is a physical image of a perovskite thick-film X-ray detector with a film on its surface, prepared as Example 1 of the present invention, which describes the interface treatment and preparation method of a composite perovskite thick-film X-ray detector.

[0039] Figure 2 This is a physical image of the perovskite thick-film X-ray detector after surface film removal, prepared in Example 1 of the present invention, which describes the interface treatment and preparation method of a composite perovskite thick-film X-ray detector.

[0040] Figure 3 Example 1 shows an SEM image of the upper surface of a perovskite thick-film X-ray detector prepared according to the present invention, which describes the interface processing and preparation method of a composite perovskite thick-film X-ray detector.

[0041] Figure 4 Example 1 shows an optical profilometer test image of the upper surface of a perovskite thick-film X-ray detector prepared according to the present invention, which describes the interface treatment and preparation method of a composite perovskite thick-film X-ray detector.

[0042] Figure 5Example 1 shows the dark current test diagram of the perovskite thick-film X-ray detector prepared according to the interface treatment and preparation method of the composite perovskite thick-film X-ray detector of the present invention.

[0043] Figure 6 Example 1 shows a half-exposure bright field image of a perovskite thick-film X-ray detector prepared according to the present invention, which describes the interface treatment and preparation method of a composite perovskite thick-film X-ray detector.

[0044] Figure 7 This is a surface image of a perovskite thick-film X-ray detector prepared in Example 2 of the present invention, which describes the interface treatment and preparation method of a composite perovskite thick-film X-ray detector.

[0045] Figure 8 Example 2 shows an SEM image of the upper surface of a perovskite thick-film X-ray detector prepared according to the present invention, which describes the interface processing and preparation method of a composite perovskite thick-film X-ray detector.

[0046] Figure 9 Example 2 shows an optical profilometer test image of the upper surface of a perovskite thick-film X-ray detector prepared according to the present invention, which describes the interface treatment and preparation method of the composite perovskite thick-film X-ray detector.

[0047] Figure 10 Example 2 shows the dark current test diagram of the perovskite thick-film X-ray detector prepared according to the interface treatment and preparation method of the composite perovskite thick-film X-ray detector of the present invention.

[0048] Figure 11 Example 2 shows a half-exposure bright field image of a perovskite thick-film X-ray detector prepared according to the present invention, which describes the interface treatment and preparation method of a composite perovskite thick-film X-ray detector.

[0049] Figure 12 This is a surface image of the perovskite thick-film X-ray detector prepared in Example 3 of the present invention, which describes the interface treatment and preparation method of a composite perovskite thick-film X-ray detector. Detailed Implementation

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0055] This invention provides an overall structural schematic diagram of an embodiment of a composite perovskite thick-film X-ray detector interface treatment and its preparation method, comprising:

[0056] Please see Figure 1-12 This embodiment describes an interface treatment and preparation method for a composite perovskite thick-film X-ray detector:

[0057] Example 1

[0058] The specific fabrication scheme of the composite perovskite thick-film X-ray detector line detector provided by this invention is as follows:

[0059] Weigh out a polycrystalline perovskite precursor powder with a mass concentration of 5 mg / ml, dissolve it in a 2-Me solution, and stir thoroughly for 60 min to obtain a perovskite suspension precursor slurry.

[0060] On a slot coater, the perovskite suspension precursor slurry obtained in step S1 is uniformly coated onto the TFT backplane using a scraping method.

[0061] The TFT board coated in step S2 is covered with a PDMS film and annealed at 80°C for 60 minutes to form a perovskite absorber layer.

[0062] Chlorobenzene is added to the device obtained in step S3 to dissolve the PDMS film, resulting in a dense perovskite absorber layer;

[0063] The device obtained in step S4 is placed in a vacuum evaporation apparatus to deposit the Au common electrode at the top, thus obtaining a perovskite X-ray detector.

[0064] The perovskite thick film prepared in this example is as follows: Figure 1 and Figure 2 As shown, Figure 1To obtain the perovskite absorber layer covering the PDMS film, chlorobenzene treatment was performed, and the PDMS film was dissolved to obtain... Figure 2 The perovskite absorber layer has a smooth and dense surface.

[0065] and Figure 3 SEM (Series Electron Microscopy) tests showed that the surface of the perovskite thick film was highly uniform within a 200 μm field of view, with no obvious macroscopic defects or abrupt changes.

[0066] Figure 4 Optical profilometer testing showed that the maximum profile height difference of the surface was 42.13 µm, and the average height deviation was approximately 29.57 µm. This indicates that the perovskite thick film in this example is sufficiently flat, forming a more uniform, continuous, and dense upper surface, which is beneficial for the subsequent continuous deposition of 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.

[0067] The perovskite X-ray detector in this example was placed in a test bench within a shielded enclosure, and its relevant photoelectric performance was tested using a Keithley 6517b electrometer. Figure 5 The dark current density is maintained at 0.24-0.26 µA / cm. 2 Within its range, it is very stable.

[0068] Figure 6 This is a half-exposure bright-field image of the perovskite X-ray detector in this example, showing that it has good pixel uniformity, proving that the charge collection uniformity has been improved.

[0069] Example 2

[0070] Weigh out a polycrystalline perovskite precursor powder with a mass concentration of 5 mg / ml, dissolve it in a 2-Me solution, and stir thoroughly for 60 min to obtain a perovskite suspension precursor slurry.

[0071] On a slot coater, the perovskite suspension precursor slurry obtained in step S1 is uniformly coated onto the TFT backplane using a scraping method.

[0072] The TFT board coated in step S2 is annealed at 80°C for 60 minutes to form a perovskite absorber layer.

[0073] The device obtained in step S3 is placed in a vacuum evaporation apparatus to deposit the Au common electrode at the top, thus obtaining a perovskite X-ray detector.

[0074] The perovskite thick film prepared in this example is as follows: Figure 7As shown, because the perovskite thick film did not undergo surface shaping treatment, residual shear stress after annealing and cooling causes microcracks on the surface of the perovskite thick film, resulting in a rough surface. This will significantly affect the detector's detection performance. The detector surface prepared in this example is as follows. Figure 8 SEM (Series Electron Microscopy) analysis revealed that the surface of the perovskite thick film exhibited high heterogeneity.

[0075] Figure 9 The maximum profile height difference shown in the optical profilometer test was 53.858 µm. This indicates that the perovskite thick film in this example is not smooth enough. The perovskite X-ray detector in this example was then subjected to relevant photoelectric performance tests, such as... Figure 10 The current density of its dark current is unstable and exhibits high deviation. For example... Figure 11 This is a half-exposure bright-field image of the perovskite X-ray detector in this example, showing that its pixels are not uniform, proving that its charge collection is not uniform.

[0076] Example 3

[0077] Weigh out a polycrystalline perovskite precursor powder with a mass concentration of 5 mg / ml, dissolve it in a 2-Me solution, and stir thoroughly for 60 min to obtain a perovskite suspension precursor slurry.

[0078] On a slot coater, the perovskite suspension precursor slurry obtained in step S1 is uniformly coated onto the TFT backplane using a scraping method.

[0079] The TFT board coated in step S2 is covered with a PDMS film and annealed at 150°C for 30-60 minutes to form a perovskite absorption layer.

[0080] In step S3, chlorobenzene is added to the device to dissolve the PDMS film and form a perovskite absorption layer.

[0081] The device obtained in step S4 is placed in a vacuum evaporation apparatus to deposit the Au common electrode at the top, thus obtaining a perovskite X-ray detector.

[0082] The perovskite thick film prepared in this example is as follows: Figure 12 As shown, the PDMS film detached after annealing, and the perovskite thick film cracked, making effective detection impossible.

[0083] Example 4

[0084] Includes the following steps:

[0085] S1: Weigh out polycrystalline perovskite precursor powder, dissolve it in an organic solution, and stir thoroughly to obtain perovskite suspension precursor slurry;

[0086] S2: On a slot coater, the perovskite suspension precursor slurry obtained in step S1 is uniformly coated onto the ITO or TFT backplane using a scraping method.

[0087] S3: Cover the precursor slurry coated in step S2 with a polymer surface shaping film and anneal it to form the perovskite absorption layer.

[0088] S4: A removal agent is dropped onto the device obtained in step S3 to remove the surface shaping film, resulting in a dense perovskite X-ray absorbing layer.

[0089] S5: Place the device obtained in step S4 into a vacuum evaporation apparatus and evaporate the top Au common electrode to obtain a perovskite X-ray detector.

[0090] Specifically, in step S1, the polycrystalline perovskite precursor powder is weighed at 8 mol / L and stirred for 45 min.

[0091] Furthermore, the organic solvent in step S1 is γ-butyrolactone (GBL);

[0092] Next, in step S1, the polycrystalline perovskite precursor is composed of formamidinium lead iodide perovskite (FAPbI3).

[0093] Meanwhile, in step S2, the distance between the scraper and the substrate is 500 μm;

[0094] Subsequently, in step S3, the annealing process is performed at 75 °C for 40 min;

[0095] Finally, the preparation method also includes the following steps:

[0096] The organic solvent selected is capable of dissolving polycrystalline perovskite precursor powder and has a high saturated vapor pressure to ensure effective solvent evaporation and reduce solvent residue in the perovskite thick film. The organic solvent is γ-butyrolactone and / or 2-methoxyethanol.

[0097] The thickness of the final polycrystalline film is controlled by the distance of the scraper.

[0098] Temperature control, a lower annealing temperature helps to reduce residual tensile stress in the thick film, and the surface shaping film is one of polydimethylsiloxane film, polymethyl methacrylate film and polystyrene film;

[0099] The selected solvents are toluene, chlorobenzene, acetone, chloroform, and dichloromethane, which are incompatible with perovskite.

[0100] Evaporation deposition, with the thickness of the top common electrode being 80-120 nm.

[0101] 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 interface processing of a composite perovskite thick-film X-ray detector, characterized in that, Includes the following steps: S1: Weigh out polycrystalline perovskite precursor powder, dissolve it in an organic solution, and stir thoroughly to obtain perovskite suspension precursor slurry; S2: On a slot coater, the perovskite suspension precursor slurry obtained in step S1 is uniformly coated onto the ITO or TFT backplane using a scraping method. S3: Cover the precursor slurry coated in step S2 with a polymer surface shaping film and anneal it to form the perovskite absorption layer. S4: A removal agent is dropped onto the device obtained in step S3 to remove the surface shaping film, resulting in a dense perovskite X-ray absorbing layer. S5: Place the device obtained in step S4 into a vacuum evaporation apparatus and deposit the Au common electrode at the top to obtain a perovskite X-ray detector.

2. The interface processing method for the composite perovskite thick-film X-ray detector according to claim 1, characterized in that, In step S1, the polycrystalline perovskite precursor powder is weighed at a concentration of 3-10 mol / L, and the stirring time is 30-60 min.

3. The interface processing method for the composite perovskite thick-film X-ray detector according to claim 2, characterized in that, The organic solvent in step S1 is either γ-butyrolactone or 2-methoxyethanol.

4. The interface processing method for the composite perovskite thick-film X-ray detector according to claim 3, characterized in that, In step S1, the polycrystalline perovskite precursor component is one of methylamine lead iodide perovskite, formamidinium lead iodide perovskite, cesium lead bromide perovskite, or trication perovskite.

5. The interface processing method for the composite perovskite thick-film X-ray detector according to claim 4, characterized in that, In step S2, the distance between the doctor blade and the substrate is 100-1000 μm.

6. The interface processing method for the composite perovskite thick-film X-ray detector according to claim 5, characterized in that, In step S3, the annealing process is to anneal at 60-100℃ for 30-60 minutes.

7. The method for preparing the interface of the composite perovskite thick-film X-ray detector according to any one of claims 1-6, characterized in that, It also includes the following steps: Select an organic solvent capable of dissolving polycrystalline perovskite precursor powder, wherein the organic solvent is γ-butyrolactone and / or 2-methoxyethanol; The thickness of the final polycrystalline film is controlled by the distance of the scraper. Temperature control; the surface shaping film is one of polydimethylsiloxane film, polymethyl methacrylate film, and polystyrene film. The selected solvents are toluene, chlorobenzene, acetone, chloroform, and dichloromethane, which are incompatible with perovskite. Evaporation deposition, with the thickness of the top common electrode being 80-120 nm.

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