Method for assisting preparation of perovskite thick film by directional arrangement of liquid molecules and x-ray detector

Abstract

This invention relates to the field of semiconductor device technology, and discloses a method for preparing perovskite thick films assisted by oriented liquid molecules and an X-ray detector. The preparation method includes: S10, depositing an oriented liquid molecule layer on a substrate; S20, depositing a perovskite precursor solution containing the oriented liquid molecules on the oriented liquid molecule layer; S30, annealing to obtain a perovskite thick film with a thickness of one to five hundred micrometers, wherein the oriented liquid molecules are cyano-containing ester organic compounds. Through the self-organizing properties of the oriented liquid molecule material and its complexation with lead ions, the perovskite nucleation and growth process can be effectively modulated, guiding the crystal to arrange in an orderly manner, suppressing random nucleation and phase separation, thereby significantly reducing pores and defects in thick films prepared by various solution processes, improving the film's density and carrier transport performance, and significantly enhancing the detection performance of the X-ray detector.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and in particular to a method for preparing perovskite thick films with the assistance of directionally arranged liquid molecules and an X-ray detector. Background Technology

[0002] The discovery of ionizing radiation in the late 19th century greatly promoted the development of high-energy particle physics and spurred the transformation of science and technology. The advent of radiation detectors further propelled the application and development of ionizing radiation. Today, high-energy radiation detection (especially X-ray detection) has become an indispensable cornerstone of modern scientific and medical progress. Utilizing the powerful penetrating ability of X-rays, we can not only perform medical diagnosis but also conduct non-destructive detection of information within matter.

[0003] An X-ray detector is an imaging device that converts X-ray radiation into a measurable electrical signal. It is widely used in medical diagnostics, industrial non-destructive testing, security inspection, and space science. Its detection mechanism is primarily based on the interaction between X-rays and the detector material, generating electron-hole pairs through the photoelectric effect or Compton effect. Under X-ray irradiation, the detector material absorbs photon energy, causing electrons to transition from the valence band to the conduction band, forming free charge carriers. Under the influence of an applied electric field, these charge carriers move directionally towards the poles, thus outputting an electrical signal proportional to the X-ray intensity, thereby enabling the monitoring of X-ray intensity or energy. Currently, common X-ray detectors mainly include scintillator detectors, semiconductor detectors, and the perovskite detectors that have emerged in recent years. Scintillator detectors convert X-rays into visible light using scintillation crystals (such as CsI:Tl), and then read the optical signal using photodiodes or silicon photomultiplier tubes. Semiconductor detectors (such as α-Se and CdTe) can directly convert X-rays into charge signals, offering high resolution and response speed. Perovskite detectors, as an emerging class of detectors, are considered to have significant potential for high-sensitivity, low-dose X-ray imaging due to their advantages such as high X-ray absorption coefficient, high carrier mobility lifetime product, and the ability to be fabricated at low temperatures using solution methods. For modern flat-panel X-ray imaging systems, the detector panel typically needs to have a large area to meet clinical and industrial imaging requirements and is often integrated with a thin-film transistor (TFT) backplane. Therefore, the fabrication process of the detector material must meet requirements such as large area, uniformity, and low processing temperature to maintain good compatibility with the TFT array. Although perovskite single crystals exhibit excellent carrier transport performance, their large-area fabrication still faces challenges such as difficult film formation, high cost, high process complexity, and poor mechanical flexibility, making it difficult to meet the needs of commercial integration. In comparison, perovskite polycrystalline thick films are more suitable for integration with flexible or rigid TFT backplanes because they can achieve large-area, thickness-controllable uniform deposition at low temperatures using solution methods. This provides an important pathway for the development of high-performance, low-cost, and scalable X-ray detection equipment.

[0004] Various methods exist for preparing perovskite thick films. To achieve efficient X-ray absorption, obtaining continuous, dense thick films ranging from several micrometers to hundreds of micrometers is crucial. Currently, common solution-based preparation processes, such as spin coating, blade coating, and in-situ growth, while differing in their underlying principles, all suffer from film formation defects stemming from the rapid evaporation of the solvent and insufficient control of crystallization kinetics in the solution system. This common bottleneck leads to problems such as non-dense crystallization, numerous grain boundaries, and the presence of voids and microcracks in the prepared thick films, regardless of whether spin coating, blade coating, or in-situ growth is used. These issues severely restrict carrier migration and collection efficiency, ultimately reducing the final performance of the detection device. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing perovskite thick films assisted by directionally arranged liquid molecules and an X-ray detector, which addresses the shortcomings of existing technologies. This method can synthesize perovskite thick films with controllable thickness, smoothness, and density, for use in the preparation of X-ray detectors.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The first aspect of this invention provides a method for preparing perovskite thick films assisted by oriented liquid molecules, comprising: S10, a layer of oriented liquid molecules is first deposited on the substrate to form an oriented liquid molecule layer; S20, continue to deposit a perovskite precursor solution containing oriented liquid molecules on the layer of oriented liquid molecules; S30, annealing, to obtain a perovskite thick film with a thickness of one micrometer to five hundred micrometers; The directionally arranged liquid molecules are cyanide-containing ester organic compounds.

[0007] According to the above scheme, the substrate is an FTO conductive glass substrate. The FTO glass needs to be cleaned sequentially with deionized water, alcohol, and acetone, dried, and then irradiated with a UV cleaning machine before use.

[0008] According to the above scheme, preferably, the thickness of the perovskite thick film is 100-300 micrometers.

[0009] Preferably, the oriented liquid molecules are ,or or .

[0010] According to the above scheme, preferably, step S10 specifically includes: dissolving the oriented liquid molecules in an organic solvent to form a spin-coating solution, and spin-coating the spin-coating solution onto a substrate at a depth of 100-120 mm. o C annealing deposits a layer of oriented liquid molecules. Spin coating speed is 2000 rpm / s-3000 rpm / s, and annealing time is 20 min-30 min.

[0011] Preferably, the concentration of oriented liquid molecules in the spin-coating solution is 0.5-3 mol / L, and the organic solvent is either γ-valerolactone or β-butyrolactone.

[0012] According to the above scheme, in S20, the solution method is a scraping method.

[0013] Preferably, in S20, the amount of oriented liquid molecules added is 5% to 10% of the amount of the perovskite precursor material, measured by molar ratio.

[0014] Preferably, methyl ammonium halide and lead halide are dissolved together in a solution of oriented liquid molecules according to the theoretical reaction stoichiometric ratio, typically with a stoichiometric ratio of 1:1 and a perovskite precursor solution concentration of 4-4.5 mol / L.

[0015] According to the above scheme, the methyl ammonium halide includes any one of methyl ammonium iodide, methyl ammonium bromide, and methyl ammonium chloride.

[0016] According to the above scheme, step S20 involves preparing a perovskite precursor solution containing oriented liquid molecules, and then depositing a perovskite precursor layer on the substrate where the oriented liquid molecule layer was deposited using a solution method. Specifically, this involves weighing the oriented liquid molecules according to a certain ratio, adding a solvent to form an oriented liquid molecule solution, and then adding methyl ammonium halide and lead iodide to the oriented liquid molecule solution to obtain a perovskite precursor solution containing oriented liquid molecules.

[0017] Preferably, S20 is applied using a scraping method, the specific steps of which are as follows: S201, weigh the oriented liquid molecules according to the ratio, add the corresponding amount of solvent to form an oriented liquid molecule solution, weigh the required perovskite precursor sample according to the ratio, add the corresponding amount of oriented liquid molecule solution, and stir fully with magnetic force to form a supersaturated solution of perovskite. S202, place the thoroughly mixed perovskite precursor solution on FTO conductive glass, adjust the height of the scraper, and uniformly coat the film from left to right.

[0018] According to the above scheme, step S30 specifically includes: in 25-150 o Dry the product at C until no liquid phase flow is observed, then transfer it to a flatbed hot press for annealing at a pressure of 0.5 MPa-10 MPa and an annealing temperature of 25-150°C. o C, annealing time of 1-20 h, to obtain perovskite thick films with a thickness of one micrometer to several hundred micrometers.

[0019] Preferably, in step S30, during the annealing process, attention should be paid to the surface condition of the perovskite thick film, and a PI film should be applied in advance.

[0020] Accordingly, the present invention also provides a perovskite thick film, which is prepared by the method for preparing perovskite thick film as described in any of the preceding claims; wherein the chemical formula of the perovskite thick film is MAPbX3, and X represents iodine, bromine or chlorine.

[0021] Preferably, the thickness of the perovskite thick film is 100-300 micrometers.

[0022] Furthermore, the present invention provides an X-ray detector, including an X-ray absorbing layer, which is prepared by the method for preparing a perovskite thick film as described in any of the preceding claims.

[0023] According to the above scheme, the structure of the X-ray detector consists of a cathode, an electron transport layer, an X-ray absorption layer, a hole blocking layer, a hole transport layer, and an anode stacked in sequence.

[0024] The method for fabricating the aforementioned X-ray detector specifically includes: S10, an electron transport layer is obtained by spin-coating SnO2 solution onto FTO and then annealing. S20, using the obtained conductive glass as a substrate, a perovskite thick film is obtained on the substrate according to the above preparation method; S30, a hole-blocking layer C is deposited on the surface of a perovskite thick film. 60 and hole transport layer (BCP); S40, gold electrodes are deposited on the obtained hole transport layer to obtain an X-ray detector.

[0025] The beneficial effects of this invention are: The present invention provides a method for preparing perovskite thick films assisted by oriented liquid molecules. First, an oriented liquid molecule layer, preferably a cyano-containing ester organic compound, is deposited on a substrate to form an oriented liquid molecule layer. Then, a perovskite precursor solution containing the oriented liquid molecules is deposited on the aforementioned oriented liquid molecule layer. During annealing to prepare the perovskite thick film, the self-organizing properties of the oriented liquid molecule material and its complexation with lead ions effectively modulate the perovskite nucleation and growth process, guiding the crystals to arrange in an orderly manner and suppressing random nucleation and phase separation. This significantly reduces pores and defects in thick films prepared by various solution processes, improves the film's density and carrier transport performance, and overcomes the problems of non-dense crystallization, disordered grain growth, and the presence of pores and Pb defects in existing perovskite thick film preparation techniques. The fluidity of the oriented liquid molecules also ensures that the grains are not crushed, reducing grain boundaries within the thick film. Ultimately, this gives the perovskite thick film excellent electron transport capabilities, significantly improving the detection performance of X-ray detectors. Furthermore, uncoordinated Pb on the crystal surface (i.e., "bare" lead) carries a positive charge, which can form deep-level defects in the band structure. These defects act like "traps," capturing photogenerated carriers (electrons or holes) and causing them to recombine (nonradiative recombination), thus reducing detector performance. However, the cyano and ester groups in the oriented liquid molecules can passivate the Pb defects present in the perovskite film, reducing nonradiative recombination and significantly improving the material's detection performance.

[0026] The preparation method of this invention also has the advantages of simple operation, low equipment requirements, and no need for expensive reaction devices. It can conveniently, greenly and economically prepare perovskite thick films with controllable thickness, smooth and dense texture and excellent performance, which is expected to generate good social and economic benefits. Attached Figure Description

[0027] Figure 1 A flowchart illustrating a method for preparing a perovskite thick film assisted by oriented liquid molecules, as provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the X-ray detector prepared in Example 1; Figure 3 The chemical structural formulas of the oriented liquid molecules used in the perovskite thick films prepared in Examples 1-8; Figure 4 a is a comparison diagram of the light response of the perovskite thick films prepared in Comparative Example 1 and Examples 1-9 under a field strength of 10V / mm. Figure 4 b is Figure 4 a magnified view of a section; Figure 5 Cross-sectional SEM images of the MAPbI3 perovskite thick films prepared in Comparative Example 1 (1), Example 2 (2), Example 4 (4) and Example 7 (3); Figure 6 The surface SEM images of the MAPbI3 perovskite thick films prepared in Comparative Example 1 (1), Example 2 (2), Example 4 (4) and Example 7 (3) of this invention are shown. Figure 7 The detection limit diagrams for the X-ray detectors prepared for Comparative Example 1 (left side, Figure a) and Example 2 (right side, Figure b). Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Existing technologies often produce perovskite thick films that suffer from problems such as poor crystal density, numerous grain boundaries, internal pores, and Pb defects. This invention provides a method for preparing perovskite thick films with the assistance of oriented liquid molecules and an X-ray detector. The method incorporates oriented liquid molecules that complex with PbX2 (X = chlorine, bromine, iodine) to regulate crystallization kinetics and act as a guiding agent, thereby improving the quality and density of the thick film. The fluidity of the oriented liquid molecules also ensures that the grains are not crushed, reducing internal grain boundaries and thus improving the detection performance of the X-ray detector. Furthermore, this method is simple to operate, requires minimal equipment, and eliminates the need for expensive reaction apparatus, promising significant social and economic benefits.

[0030] To enable those skilled in the art to better understand and implement the present invention, the present invention will be described in detail below. It should be emphasized that the following embodiments are merely illustrative and are not intended to limit the scope of protection of the present invention.

[0031] Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for preparing perovskite thick films assisted by directionally aligned liquid molecules, as provided in an embodiment of the present invention. Specifically, it may include the following steps: S10 involves first depositing a layer of oriented liquid molecules on the substrate to form an oriented liquid molecule layer.

[0032] Specifically, step S10 includes: dissolving the oriented liquid molecules in an organic solvent to form a spin-coating solution, and spin-coating the solution onto a substrate at a depth of 100-120°C. o C-annealing deposits a layer of directionally aligned liquid molecules. In some specific embodiments, the spin coating speed is 2000 rpm / s-3000 rpm / s, and the annealing time is 20 min-30 min.

[0033] Specifically, the substrate is an FTO conductive glass substrate. In some specific embodiments, the FTO glass needs to be cleaned sequentially with deionized water, alcohol, and acetone, dried, and then irradiated with a UV cleaner for 15 minutes.

[0034] Specifically, the concentration of the oriented liquid molecules in the spin-coating solution is 0.5-3 mol / L, and the organic solvent is either γ-valerolactone or β-butyrolactone.

[0035] S20, continue to deposit a perovskite precursor solution containing oriented liquid molecules on the layer of oriented liquid molecules.

[0036] Specifically, S20 involves preparing a mixed solution containing oriented liquid molecules and a perovskite precursor solution, and then depositing a perovskite precursor layer on the substrate where the oriented liquid molecule layer was deposited using a solution method. Specifically, the amount of oriented liquid molecules added, measured by molar ratio, is 5% to 10% of the amount of the perovskite precursor material.

[0037] Specifically, the solution method is a blade coating method. More specifically, S20 uses a blade coating method, and the specific steps are as follows: S201, weigh the oriented liquid molecules according to the ratio, add the corresponding amount of solvent to form an oriented liquid molecule solution, weigh the required perovskite precursor sample according to the ratio, add the corresponding amount of oriented liquid molecule solution, and stir fully with magnetic force to form a supersaturated solution of perovskite. S202: Place the thoroughly mixed perovskite precursor solution onto FTO conductive glass, adjust the doctor blade height, and uniformly coat the film from left to right. Specifically, the doctor blade height can be adjusted as needed to obtain film thicknesses ranging from one micrometer to several hundred micrometers, and the coating speed should be kept uniform to ensure a smooth surface of the coated film.

[0038] Specifically, methyl ammonium halide and lead halide are dissolved together in a liquid crystal solution according to the theoretical reaction stoichiometric ratio, usually 1:1, and the concentration of the perovskite precursor solution is 4-4.5 mol / L.

[0039] Specifically, the stirring time of S201 is 5-12 h, which can ensure that the perovskite precursor solution is fully and evenly mixed.

[0040] In embodiments of the present invention, methyl ammonium halide includes any one of methyl ammonium iodide (MAPbI3), methyl ammonium bromide (MAPbBr3), and methyl ammonium chloride (MAPbCl3).

[0041] Specifically, the oriented liquid molecules are cyanide-containing ester organic compounds.

[0042] Preferably, the oriented liquid molecules are ,or or .

[0043] S30, annealing to obtain perovskite thick films with a thickness of one micrometer to five hundred micrometers. Specifically, in the range of 25-150 o Dry the product at C until no liquid phase flow is observed, then transfer it to a flatbed hot press for annealing at a pressure of 0.5 MPa-10 MPa and an annealing temperature of 25-150°C. o C, annealing time is 1-20 h, to obtain perovskite thick films with a thickness of one micrometer to five hundred micrometers.

[0044] Specifically, in step S30, during the annealing process, attention should be paid to the surface condition of the perovskite thick film, and a PI film should be applied in advance.

[0045] Accordingly, the present invention also provides a perovskite thick film, which is prepared by the method for preparing perovskite thick films as described in any of the preceding claims; The chemical formula of the perovskite thick film is MAPbX3, where X represents iodine, bromine, or chlorine.

[0046] Furthermore, the present invention provides an X-ray detector, including an X-ray absorbing layer, which is prepared by the method for preparing a perovskite thick film as described in any of the preceding claims.

[0047] This method overcomes the problems of disordered growth and easy grain breakage under high pressure in perovskite thick film crystals prepared by traditional coating and annealing by innovatively using the guiding effect and fluidity of oriented liquid molecules. This ensures the quality of the prepared thick film and improves the detection performance of X-ray detectors prepared with thick film.

[0048] The technical solution of the present invention will now be further described with reference to specific embodiments. The raw materials used in the following embodiments are all commercially available.

[0049] Comparative Example 1: First, a perovskite precursor solution was prepared by mixing 0.07108 g MAI and 0.20745 g PbI₂ in a molar ratio of 1:1 to obtain a raw material mixture. The purity of all raw materials was >99.99%.

[0050] Next, the powders were ground separately and mixed evenly. 100 μL of the green solvent γ-valerol was added to the mixed powder and then stirred with a magnetic stirrer for 12 h until completely dissolved to obtain a 4.5 mol / L MAPbI3 perovskite precursor solution.

[0051] Next, the FTO conductive glass was ultrasonically cleaned with deionized water, alcohol and acetone for 30 min in sequence, dried and irradiated with a UV cleaner for 15 min. The uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 100 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0052] Example 1: First, the FTO conductive glass was ultrasonically cleaned sequentially with deionized water, alcohol, and acetone for 30 min, dried, and then irradiated with a UV cleaner for 15 min. SnO2 solution was then spin-coated onto the treated glass at 3000 rpm / s for 30 s, followed by annealing at 115℃ for 15 min.

[0053] Next, 0.0249 g of 4'-cyanobiphenyl-4-yl-2-acrylate (CBEV) was weighed and mixed with 100 μL of the green solvent γ-valerol to prepare a 1 mol / L mixed reagent. The purity of all raw materials was >99.99%. Then, the mixture was spin-coated onto an FTO conductive glass substrate pre-coated with SnO2 at a speed of 2000 rpm, with a thickness of 100-120 mm. o Annealed at C for 20 min, a layer of oriented liquid molecules was deposited by spin coating.

[0054] Next, 0.0121 g of 4'-cyanobiphenyl-4-yl-2-acrylate (CBEV) was weighed, which corresponds to 10% of the molar amount of the perovskite precursor, and mixed with 100 μL of the green solvent γ-valerolactone to prepare a mixed reagent. The purity of all raw materials was >99.99%.

[0055] Next, a perovskite precursor solution was prepared by mixing 0.07108 g MAI and 0.20745 g PbI2 in a molar ratio of 1:1. The MAI and PbI2 were ground separately and then mixed thoroughly. The mixed reagents were added to the powder mixture, and the mixture was stirred magnetically for 12 h until completely dissolved to obtain a 4.5 mol / L MAPbI3 perovskite precursor solution. The purity of all raw materials was >99.99%.

[0056] Finally, the uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 100 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0057] After the thick film is prepared, C is sequentially deposited on its surface. 60 Finally, Au electrodes with dimensions of 1 mm × 1 mm and a thickness of 200 nm were deposited on the thick film surface using vacuum evaporation. C electrodes were then deposited on the FTO conductive glass to obtain a structure of C / SnO2 / MAPbI3 / C. 60 / BCP / Au X-ray detector.

[0058] Example 2: First, weigh 0.0269 g of 4-butylbenzoic acid-4-cyanophenyl ester and mix it with 100 μL of the green solvent γ-valerol to prepare a 1 mol / L mixed reagent. The purity of all raw materials is >99.99%. The FTO conductive glass is then ultrasonically cleaned sequentially with deionized water, alcohol, and acetone for 30 min, dried, and irradiated with a UV cleaner for 15 min. Finally, it is spin-coated onto the FTO conductive glass substrate at 2000 rpm, with a coating thickness of 100-120 mm. o Annealed at C for 20 min, a layer of oriented liquid molecules was deposited by spin coating.

[0059] Next, 0.01256 g of 4-butylbenzoic acid-4-cyanophenyl ester was weighed, which corresponds to 10% of the molar amount of the perovskite precursor by molar ratio. This was mixed with 100 μL of the green solvent γ-valerolactone to prepare a mixed reagent. The purity of all raw materials was >99.99%.

[0060] Next, a perovskite precursor solution was prepared by mixing 0.07108 g MAI and 0.20745 g PbI2 in a molar ratio of 1:1. After grinding each component separately and mixing them thoroughly, the above-mentioned mixed reagent was added to the mixed powder, and the mixture was stirred magnetically for 12 h until completely dissolved to obtain a 4.5 mol / L MAPbI3 perovskite precursor solution. The purity of all raw materials was >99.99%.

[0061] Finally, the uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 100 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0062] Example 3: First, weigh 0.0286 g of 4-heptylbenzoic acid-4-cyanophenyl ester and mix it with 100 μL of the green solvent γ-valerol to prepare a 1 mol / L mixed reagent. The purity of all raw materials is >99.99%. The FTO conductive glass is then ultrasonically cleaned sequentially with deionized water, alcohol, and acetone for 30 min, dried, and irradiated with a UV cleaner for 15 min. Finally, it is spin-coated onto the FTO conductive glass substrate at 2000 rpm, with a coating thickness of 100-120 mm. o Annealed at C for 20 min, a layer of oriented liquid molecules was deposited by spin coating.

[0063] Next, 0.0213 g of 4-heptylbenzoic acid-4-cyanophenyl ester was weighed, which corresponds to 10% of the molar amount of the perovskite precursor. This was mixed with 100 μL of the green solvent γ-valerolactone to prepare a mixed reagent. The purity of all raw materials was >99.99%.

[0064] Next, a perovskite precursor solution was prepared by mixing 0.07108 g MAI and 0.20745 g PbI2 in a molar ratio of 1:1. After grinding each component separately and mixing them thoroughly, the above-mentioned mixed reagent was added to the mixed powder, and the mixture was stirred magnetically for 12 h until completely dissolved to obtain a 4.5 mol / L MAPbI3 perovskite precursor solution. The purity of all raw materials was >99.99%.

[0065] Finally, the uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 100 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0066] Example 4: First, weigh 0.0249 g of 4-cyano-4'-pentylbiphenyl (5CB) and mix it with 100 μL of the green solvent γ-valerol to prepare a 1 mol / L mixed reagent. The purity of all raw materials is >99.99%. The FTO conductive glass was ultrasonically cleaned sequentially with deionized water, alcohol, and acetone for 30 min, dried, and then irradiated with a UV cleaner for 15 min. The coating was then spin-coated onto the FTO conductive glass substrate at 2000 rpm, with a thickness of 100-120 mm. o Annealed at C for 20 min, a layer of oriented liquid molecules was deposited by spin coating.

[0067] Next, 0.0112 g of 4-cyano-4'-pentylbiphenyl (5CB) was weighed, which corresponds to 10% of the molar amount of the perovskite precursor, and mixed with 100 μL of the green solvent γ-valerolactone to prepare a mixed reagent. The purity of all raw materials was >99.99%.

[0068] Next, a perovskite precursor solution was prepared by mixing 0.07108 g MAI and 0.20745 g PbI2 in a molar ratio of 1:1. After grinding each component separately and mixing them thoroughly, the above-mentioned mixed reagent was added to the mixed powder, and the mixture was stirred magnetically for 12 h until completely dissolved to obtain a 4.5 mol / L MAPbI3 perovskite precursor solution. The purity of all raw materials was >99.99%.

[0069] Finally, the uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 100 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0070] Example 5: First, weigh 0.0223 g of 4-cyano-4'-ethoxybiphenyl (2OCB) and mix it with 100 μL of the green solvent γ-valerol to prepare a 1 mol / L mixed reagent. The purity of all raw materials is >99.99%. The FTO conductive glass was ultrasonically cleaned sequentially with deionized water, alcohol, and acetone for 30 min, dried, and then irradiated with a UV cleaner for 15 min. Finally, it was spin-coated onto the FTO conductive glass substrate at 2000 rpm, with a coating thickness of 100-120 mm. o Annealed at C for 20 min, a layer of oriented liquid molecules was deposited by spin coating.

[0071] Next, 0.0100 g of 4-cyano-4'-ethoxybiphenyl (2OCB) was weighed, which corresponds to 10% of the molar amount of the perovskite precursor, and mixed with 100 μL of the green solvent γ-valerolactone to prepare a mixed reagent. The purity of all raw materials was >99.99%.

[0072] Next, a perovskite precursor solution was prepared by mixing 0.07108 g MAI and 0.20745 g PbI2 in a molar ratio of 1:1. After grinding each component separately and mixing them thoroughly, the above-mentioned mixed reagent was added to the mixed powder, and the mixture was stirred magnetically for 12 h until completely dissolved to obtain a 4.5 mol / L MAPbI3 perovskite precursor solution. The purity of all raw materials was >99.99%.

[0073] Finally, the uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 100 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0074] Example 6: First, weigh 0.0277 g of 4-cyano-4'-heptylbiphenyl (7CB) and mix it with 100 μL of the green solvent γ-valerol to prepare a 1 mol / L mixed reagent. The purity of all raw materials is >99.99%. The FTO conductive glass is then ultrasonically cleaned sequentially with deionized water, alcohol, and acetone for 30 min, dried, and irradiated with a UV cleaner for 15 min. Finally, it is spin-coated onto the FTO conductive glass substrate at 2000 rpm, with a coating thickness of 100-120 mm. o Annealed at C for 20 min, a layer of oriented liquid molecules was deposited by spin coating.

[0075] Next, 0.0125 g of 4-cyano-4'-heptylbiphenyl (7CB) was weighed, which corresponds to 10% of the molar amount of the perovskite precursor, and mixed with 100 μL of the green solvent γ-valerolactone to prepare a mixed reagent. The purity of all raw materials was >99.99%.

[0076] Next, a perovskite precursor solution was prepared by mixing 0.07108 g MAI and 0.20745 g PbI2 in a molar ratio of 1:1. After grinding each component separately and mixing them thoroughly, the above-mentioned mixed reagent was added to the mixed powder, and the mixture was stirred magnetically for 12 h until completely dissolved to obtain a 4.5 mol / L MAPbI3 perovskite precursor solution. The purity of all raw materials was >99.99%.

[0077] Finally, the uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 100 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0078] Example 7: First, weigh 0.0238 g of 4'-methyl-4-pentylbiphenyl and mix it with 100 μL of the green solvent γ-valerol to prepare a 1 mol / L mixed reagent. The purity of all raw materials is >99.99%. The FTO conductive glass is then ultrasonically cleaned sequentially with deionized water, alcohol, and acetone for 30 min, dried, and irradiated with a UV cleaner for 15 min. Finally, it is spin-coated onto the FTO conductive glass substrate at 2000 rpm, with a coating thickness of 100-120 mm. o Annealed at C for 20 min, a layer of oriented liquid molecules was deposited by spin coating.

[0079] Next, 0.0107 g of 4'-methyl-4-pentylbiphenyl, corresponding to 10% of the molar amount of the perovskite precursor, was weighed and mixed with 100 μL of the green solvent γ-valerol to prepare a mixed reagent. The purity of all raw materials was >99.99%.

[0080] Next, a perovskite precursor solution was prepared by mixing 0.07108 g MAI and 0.20745 g PbI2 in a molar ratio of 1:1. After grinding each component separately and mixing them thoroughly, the above-mentioned mixed reagent was added to the mixed powder, and the mixture was stirred magnetically for 12 h until completely dissolved to obtain a 4.5 mol / L MAPbI3 perovskite precursor solution. The purity of all raw materials was >99.99%.

[0081] Finally, the uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 100 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0082] Example 8: First, weigh 0.0250 g of 4'-cyanobenylidene-4-ethoxyaniline and mix it with 100 μL of the green solvent γ-valerol to prepare a 1 mol / L mixed reagent. The purity of all raw materials is >99.99%. The FTO conductive glass is then ultrasonically cleaned sequentially with deionized water, alcohol, and acetone for 30 min, dried, and irradiated with a UV cleaner for 15 min. Finally, it is spin-coated onto the FTO conductive glass substrate at 2000 rpm, with a coating thickness of 100-120 mm. o Annealed at C for 20 min, a layer of oriented liquid molecules was deposited by spin coating.

[0083] Next, 0.0113 g of 4'-cyanobenylidene-4-ethoxyaniline was weighed, which corresponds to 10% of the molar amount of the perovskite precursor, and mixed with 100 μL of the green solvent γ-valerolactone to prepare a mixed reagent. The purity of all raw materials was >99.99%.

[0084] Next, a perovskite precursor solution was prepared by mixing 0.07108 g MAI and 0.20745 g PbI2 in a molar ratio of 1:1. After grinding each component separately and mixing them thoroughly, the above-mentioned mixed reagent was added to the mixed powder, and the mixture was stirred magnetically for 12 h until completely dissolved to obtain a 4.5 mol / L MAPbI3 perovskite precursor solution. The purity of all raw materials was >99.99%.

[0085] Finally, the uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 100 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0086] Example 9: First, weigh 0.1614 g of 4-butylbenzoic acid-4-cyanophenyl ester and mix it with 300 μL of the green solvent γ-valerol to prepare a 2 mol / L mixed reagent. The purity of all raw materials is >99.99%. The FTO conductive glass is then ultrasonically cleaned sequentially with deionized water, alcohol, and acetone for 30 min, dried, and irradiated with a UV cleaner for 15 min. Finally, it is spin-coated onto the FTO conductive glass substrate at 2000 rpm, with a coating thickness of 100-120 mm. o Annealed at C for 20 min, a layer of oriented liquid molecules was deposited by spin coating.

[0087] Next, 0.02638 g of 4-butylbenzoic acid-4-cyanophenyl ester was weighed, which corresponds to 7% of the molar amount of the perovskite precursor by molar ratio. This was mixed with 300 μL of the green solvent γ-valerolactone to prepare a mixed reagent. The purity of all raw materials was >99.99%.

[0088] Next, a perovskite precursor solution was prepared by mixing 0.21324 g MAI and 0.62235 g PbI2 in a 1:1 molar ratio. After grinding each component separately and mixing them thoroughly, the above-mentioned reagent mixture was added to the powder mixture and stirred magnetically for 12 h until completely dissolved, yielding a 4.5 mol / L MAPbI3 perovskite precursor solution. The purity of all raw materials was >99.99%.

[0089] Finally, the uniformly vibrated perovskite precursor solution was placed on the treated FTO conductive glass, and the solution was uniformly coated with a scraper at a height of 350 μm. Then, it was annealed on a flat plate hot press at 100℃ and 6MPa for 8 h to obtain a perovskite thick film.

[0090] Please see Figure 2 , Figure 2 A schematic diagram of the X-ray detector prepared for implementation 1; Please see Figure 3 , Figure 3 The molecular structural formulas of the oriented liquid molecules used in Examples 1-8; Please see Figure 5 , Figure 5 Cross-sectional SEM images of the MAPbI3 perovskite thick films prepared in Comparative Example 1 (1), Example 2 (2), Example 4 (4), and Example 6 (3); wherein, by Figure 5 It can be seen that the cross-section of the MAPbI3 thick film prepared in Comparative Example 1 of the present invention has relatively obvious pores; the cross-section of the MAPbI3 thick film prepared in Examples 2 and 4 has almost no pores and grain boundaries, and the grains are arranged very tightly; although Example 6 is dense, it has many grain boundaries and many pores at the bottom, which affects the contact between MAPbI3 and the glass substrate.

[0091] Please see Figure 6 , Figure 6 The images show surface SEM images of the MAPbI3 perovskite thick films prepared in Comparative Examples 1 (1), 2 (2), 4 (4), and 6 (3) of this invention; wherein, the films are prepared by... Figure 6 It can be seen that the MAPbI3 thick film prepared in Comparative Example 1 of the present invention has a large number of pores and defects on its surface. The MAPbI3 thick films prepared in Examples 2 and 4 have only a small number of pores on their surfaces, and the number of grain boundaries is relatively reduced, with the grains arranged very tightly. The surface of Example 6 also has fewer pores and larger grains, but the surface is not smooth enough and the grain distribution is disordered.

[0092] Please see Figure 4 , Figure 4 a represents the light-to-dark ratio of the perovskite thick films prepared in Comparative Example 1 and Examples 1-9 of this invention at a field strength of 10V / mm. Figure 4 b is an enlarged view of some embodiments; by Figure 4 As can be seen from the diagram, the light-to-dark ratio of the perovskite thick films (Examples 1-3) prepared after adding oriented liquid molecules (cyano-containing ester organic compounds) was significantly improved, especially in Examples 2 and 3, where the light-to-dark ratio exceeded 20, far surpassing that of Comparative Example 1. The perovskite thick films prepared after adding other liquid molecules (molecules without ester or cyano groups, Examples 4-8) exhibited poor performance and low light-to-dark ratios. Please refer to [link / reference]. Figure 7 , Figure 7 The detection limit of the perovskite thick films prepared in Comparative Example 1(a) and Example 2(b) of this invention; by Figure 7 It can be seen that the detection limit of perovskite thick films after adding oriented liquid molecules can reach 13.22 nGy S. -1 Comparing Examples 2 and 9, it can be seen that adjusting the height of the scraper to prepare thick films of different sizes does not significantly affect the detection performance of the thick films. In summary, this invention provides a method for preparing perovskite thick films assisted by oriented liquid molecules and an X-ray detector. This method improves the quality and density of the thick film by adding oriented liquid molecules that complex with PbX2 (X = chlorine, bromine, iodine) to regulate crystallization kinetics and act as a guiding agent. The fluidity of the oriented liquid molecules also ensures that the grains are not crushed, reducing grain boundaries within the thick film and thus improving the detection performance of the X-ray detector. Furthermore, this invention has advantages such as simple operation, low equipment requirements, and no need for expensive reaction apparatus, and is expected to generate significant social and economic benefits.

[0093] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0094] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing perovskite thick films assisted by oriented liquid molecules, comprising: S10, a layer of oriented liquid molecules is first deposited on the substrate to form an oriented liquid molecule layer; S20, continue to deposit a perovskite precursor solution containing oriented liquid molecules on the layer of oriented liquid molecules; S30, annealing, to obtain a perovskite thick film with a thickness of one micrometer to five hundred micrometers, wherein the oriented liquid molecules are cyanide-containing ester organic compounds.

2. The method for preparing perovskite thick films assisted by directionally aligned liquid molecules according to claim 1, characterized in that: The directionally arranged liquid molecules are ,or or .

3. The method for preparing perovskite thick films assisted by directionally aligned liquid molecules according to claim 1, characterized in that: The thickness of perovskite thick films is 100-300 micrometers.

4. The method for preparing perovskite thick films assisted by directionally aligned liquid molecules according to claim 1, characterized in that... In S20, the amount of oriented liquid molecules added, measured by molar ratio, is 5% to 10% of the amount of the perovskite precursor material.

5. The method for preparing perovskite thick films assisted by directionally aligned liquid molecules according to claim 1, characterized in that: In step S20, a perovskite precursor solution containing directionally aligned liquid molecules is prepared, and a perovskite precursor layer is deposited on the substrate on which the directionally aligned liquid molecules have been deposited by the solution method; the solution method is a blade coating method.

6. The method for preparing perovskite thick films assisted by directionally aligned liquid molecules according to claim 5, characterized in that: Methyl ammonium halide and lead halide are dissolved together in a solution of directionally aligned liquid molecules according to the theoretical reaction stoichiometric ratio, and the concentration of the perovskite precursor solution is 4-4.5 mol / L; the methyl ammonium halide includes any one of methyl ammonium iodide, methyl ammonium bromide and methyl ammonium chloride.

7. The method for preparing perovskite thick films assisted by directionally aligned liquid molecules according to claim 1, characterized in that: Step S10 specifically includes: dissolving the oriented liquid molecules in an organic solvent to form a spin-coating solution, and spin-coating the solution onto a substrate at a depth of 100-120°C. o C annealing deposits a layer of directionally aligned liquid molecules; the concentration of the directionally aligned liquid molecules in the spin-coating solution is 0.5-3 mol / L; the organic solvent is either γ-valerolactone or β-butyrolactone. S20 is applied using a scraping method, with the following specific steps: S201, weigh the oriented liquid molecules according to the ratio, add the corresponding amount of solvent to form an oriented liquid molecule solution, weigh the required perovskite precursor sample according to the ratio, add the corresponding amount of oriented liquid molecule solution, and stir fully with magnetic force to form a supersaturated solution of perovskite. S202, place the thoroughly mixed perovskite precursor solution on FTO conductive glass, adjust the height of the scraper, and uniformly coat the film from left to right; Step S30 specifically includes: in 25-150 o Dry the product at C until no liquid phase flow is observed, then transfer it to a flatbed hot press for annealing at a pressure of 0.5 MPa-10 MPa and an annealing temperature of 25-150°C. o C, annealing time is 1-20 h, to obtain perovskite thick films with a thickness of one micrometer to five hundred micrometers.

8. A perovskite thick film, prepared by the method for preparing a perovskite thick film according to any one of claims 1-7, wherein the chemical formula of the perovskite thick film is MAPbX3, where X represents iodine, bromine or chlorine.

9. An X-ray detector, characterized in that: It includes an X-ray absorbing layer, which is prepared by the method for preparing a perovskite thick film as described in any of the preceding claims.

10. The X-ray detector according to claim 9, characterized in that: The structure of an X-ray detector consists of a cathode, an electron transport layer, an X-ray absorption layer, a hole blocking layer, a hole transport layer, and an anode, stacked sequentially.

Images