WO2023087453A1

WO2023087453A1 - Direct x-ray image detector and method for manufacturing same

Info

Publication number: WO2023087453A1
Application number: PCT/CN2021/138092
Authority: WO
Inventors: 薛冬峰; 李云龙; 陈慧雯; 王晓明
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2021-11-19
Filing date: 2021-12-14
Publication date: 2023-05-25
Also published as: CN114252031A; CN114252031B

Abstract

A direct X-ray image detector and a method for manufacturing same. The method for manufacturing the direct X-ray image detector comprises the following steps: synthesizing a long-chain organic carboxylic acid and an organic ligand into an ionic liquid; dissolving the ionic liquid, a halocarbon metal, and a halide salt in an organic solvent to obtain a precursor gel; forming a film on the surface of a pixel array of a substrate by using the precursor gel, and annealing, to form a two-dimensional hybrid perovskite quantum array film layer on the surface of the pixel array of the substrate; and preparing an electrode layer to obtain a direct X-ray image detector. According to the method for manufacturing the direct X-ray image detector, a long-chain organic carboxylic acid is introduced, the [BX6] octahedron aggregation rate is reduced, the viscosity of the precursor solution is improved, a quantum well array with single well width distribution is constructed, the film forming thickness of the quantum array film layer is increased, the X-ray absorption and conversion efficiency of the device is improved, and high-definition imaging of X-rays is achieved.

Description

Direct type X-ray image detector and its preparation method

technical field

The application belongs to the field of optoelectronic technology, and in particular relates to a direct X-ray image detector and a preparation method thereof.

Background technique

The direct type X-ray image detector consists of a semiconductor active layer and a thin film transistor pixel array. The working principle is that the semiconductor active layer directly converts the X-rays passing through the measured object into electrical signals, and then uses a computer to control the capacitor in the thin film transistor pixel array. The switch collects electrical signals and converts the electrical signals into images. The color depth of pixels in the images is determined by the intensity of the generated electrical signals. Since the measured object absorbs X-rays differently, the X-ray dose rate passing through the measured object can reflect the shape of the object, and the role of the semiconductor active layer is to convert these X-rays with different dose rates into electrical signals of different intensities , describe the shape of the object through the color depth of the pixel. Therefore, in addition to the directional migration of carriers, constructing a quantum well array with a wide distribution of single wells, so that the carriers are evenly transported to the array substrate, is one of the key technologies for realizing high-definition imaging of X-ray direct detectors.

At present, through the regulation of organic ligands, solvents, and additives, the aggregation speed of octahedrons in the nucleation process of two-dimensional hybrid perovskite is controlled, and the volatilization speed of solvents and additives in the film growth process is controlled at the same time. However, this conventional method is easy to synthesize multi-n quantum well films, which is not conducive to the uniform transport of carriers to the array substrate. Moreover, the current research on the regulation of the vertical substrate orientation of two-dimensional hybrid perovskite is mostly used in solar cells, so the thickness of the film is about 0.5 μm, which has low absorption of high-energy X-rays and produces fewer carriers. The signal is weak, affecting the final imaging clarity.

technical problem

The purpose of the present application is to provide a direct type X-ray image detector and its preparation method, aiming to solve the problem of low absorption coefficient of X-rays and poor imaging effect of the existing direct type X-ray image detector to a certain extent.

technical solution

In order to realize the above-mentioned application purpose, the technical scheme adopted in this application is as follows:

In a first aspect, the present application provides a method for preparing a direct X-ray image detector, comprising the following steps:

Synthesis of long-chain organic carboxylic acids and organic ligands into ionic liquids;

Dissolving the ionic liquid, carbon group metal halide and halide salt in an organic solvent to obtain a precursor gel; the halide salt includes an organic ammonium halide or an alkali metal halide;

Obtaining a substrate with a pixel array distributed on its surface, forming a film of the precursor gel on the surface of the pixel array of the substrate, annealing, and forming a two-dimensional hybrid perovskite quantum array film on the surface of the pixel array of the substrate layer;

An electrode layer is prepared on the surface of the quantum array film layer away from the substrate to obtain a direct X-ray image detector.

Further, the number of carbon atoms of the long-chain organic carboxylic acid is 3-10.

Further, the organic ligand is selected from at least one of n-butylamine, isobutylamine, α-phenethylamine, allylamine, and 2-thio-ethylamine.

Further, in the direct X-ray image detector, the thickness of the quantum array film layer is 8-20 μm.

Further, the long-chain organic carboxylic acid is selected from at least one of propionic acid, n-butyric acid, isobutyric acid and n-valeric acid.

Further, the method for synthesizing the ionic liquid adopts a vacuum rotary evaporation method.

Further, the step of synthesizing the ionic liquid comprises:

Mixing the long-chain organic carboxylic acid and the organic ligand at a temperature of 0°C to 5°C to obtain a crude product;

The crude product was rotary evaporated under reduced pressure at a temperature of 60-100°C, and the product was collected;

The product is subjected to crystallization treatment at a temperature of -30~-10°C to obtain a crystalline product;

The crystalline product is purified to obtain the ionic liquid.

Further, the halogenated carbon group metal is selected from at least one of lead chloride, lead bromide, lead iodide, tin chloride, tin bromide, and tin iodide.

Further, the organic ammonium halide salt is selected from: methylamine hydroiodide, CH ₃ NH ₃ Cl, CH ₃ NH ₃ Br, CH ₃ NH ₃ I, CH ₂ (NH ₃ ) ₂ Cl, CH ₂ (NH ₃ ) At least one of ₂ Br and CH ₂ (NH ₃ ) ₂ I.

Further, the alkali metal halide is selected from at least one of CsCl, CsBr, CsI, RbCl, RbBr, and RbI.

Further, the organic solvent is selected from: a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide.

Further, the step of preparing the precursor gel includes: after dissolving the ionic liquid, the halogenated carbon group metal and the halide salt in an organic solvent, heat preservation at a temperature of 90-110°C for 5~ 120s, obtain the precursor gel;

Further, the step of the annealing treatment includes: at a temperature of 100-150°C, after scraping the precursor gel onto the surface of the pixel array of the substrate, at a temperature of 80-150°C Under dry annealing for 5~20 minutes;

Further, in the organic solvent, the volume ratio of the dimethyl sulfoxide to the N,N-dimethylformamide is (1-4):(1-4).

In the second aspect, the present application provides a direct X-ray image detector, including: a substrate, a pixel array bonded on the surface of the substrate, a quantum array film layer vertically grown on the surface of the pixel array, and lamination The electrode layer arranged on the surface of the quantum array film layer; wherein, the quantum array film layer contains a general structural formula of A'A _n-1 B _n X _3n+1 and/or A' ₂ A _n-1 A two-dimensional hybrid perovskite of B _n X _3n+1 , where A' is an organic ligand, A is an ammonium ion or an alkali metal ion, B is a carbon group metal ion, and X is a halogen ion; n is 2~10 .

Further, the organic ammonium ion is selected from at least one of CH ₃ NH ₃ ⁺ and CH ₂ (NH ₃ ) ₂ ⁺ .

Further, the alkali metal ion is selected from at least one of Cs ⁺ and Rb ⁺ .

Further, the carbon group metal ion is selected from at least one of lead and tin.

Further, the halide ion is selected from at least one of chlorine, bromine and iodine.

Further, the material of the pixel array includes: at least one of ITO, FTO, P3HT:PCBM.

Further, the material of the substrate is selected from glass.

Further, the electrode layer is selected from at least one of carbon electrodes and metal electrodes.

Beneficial effect

The preparation method of the direct type X-ray image detector provided by the first aspect of the present application uses a long-chain organic carboxylic acid and an organic ligand to synthesize an ionic liquid, and then dissolves the ionic liquid, a halogenated carbon group metal, and a halide salt in an organic solvent, and utilizes The strong coordination between the carbonyl group and the octahedral central cation, as well as the intermolecular force between the carboxylic acid alkyl chains, reduce the driving force of [BX ₆ ] octahedral aggregation, inhibit the rapid aggregation of octahedron, and improve the precursor solution Viscosity, forming a stable precursor gel. It is then deposited on the substrate with the pixel array, and the gel film layer is constructed in situ. During the deposition process, the octahedron of the two-dimensional hybrid perovskite and the interlayer organic cation self-assemble through the intermolecular force, and the pixel array is perpendicular to the Basal growth. While the two-dimensional hybrid perovskite crystals grow, the strong coordination between the carbonyl group in the long-chain organic acid and the octahedral central cation makes the organic solvent and carboxylic acid in the gel layer volatilize at a uniform speed, and through annealing treatment , a two-dimensional hybrid perovskite quantum array film is formed. Then an electrode layer is prepared on the surface of the quantum array film layer away from the substrate to obtain a direct X-ray image detector. Not only can a quantum well array with a single well width distribution be constructed, but also the film thickness of the quantum array film layer can be increased, thereby improving the ability of the direct type X-ray image detector to capture X-rays, and improving the absorption and conversion efficiency of the device for X-rays. Realize high-definition imaging of X-rays.

In the direct X-ray image detector prepared by the above method provided in the second aspect of the present application, the two-dimensional hybrid perovskite grown vertically on the surface of the pixel array in the quantum array film layer makes the carriers in the quantum array film layer move along Directional migration along the growth direction of the quantum well suppresses lateral drift and scattering of carriers, improves carrier transfer efficiency, and avoids carrier loss. In addition, the direct X-ray image detector prepared by the above method can not only construct a quantum well array with a single well width distribution, so that the carriers can be evenly transported to the array substrate, which is to realize high-definition imaging of the X-ray direct detector; Increase the film thickness of the quantum array film layer, thereby improving the ability of the direct type X-ray image detector to capture X-rays, thereby further improving the absorption and conversion efficiency of the device for X-rays. Therefore, the direct X-ray image detector provided by the present application has pixel confinement characteristics, can directly absorb and convert X-rays into charge carriers, has high absorption and conversion efficiency of X-rays, and has high detection sensitivity.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the accompanying drawings that need to be used in the descriptions of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description are only for the present application For some embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without creative effort.

FIG. 1 is a schematic flow chart of a method for preparing a direct X-ray image detector provided in an embodiment of the present application;

Fig. 2 is a schematic structural diagram of a direct X-ray image detector provided in an embodiment of the present application;

FIG. 3 is a graph showing the functional relationship between the photocurrent density and the X-ray dose rate of the direct X-ray image detectors provided in Examples 1-3 and Comparative Example 1 of the present application.

Embodiments of the present invention

In order to make the technical problems, technical solutions and beneficial effects to be solved in the present application clearer, the present application will be further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

In this application, the term "and/or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, A and/or B may mean: A exists alone, A and B exist simultaneously, and B exists alone Condition. Among them, A and B can be singular or plural. The character "/" generally indicates that the contextual objects are an "or" relationship.

In this application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one (one) of a, b, or c", or "at least one (one) of a, b, and c" can mean: a, b, c, a-b (that is, a and b), a-c, b-c, or a-b-c, where a, b, c can be single or multiple.

It should be understood that in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the order of execution, and some or all steps may be executed in parallel or sequentially, and the execution order of each process shall be based on its functions and The internal logic is determined and should not constitute any limitation to the implementation process of the embodiment of the present application.

Terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of this application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

The weight of the relevant components mentioned in the description of the embodiments of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the various components. The scaling up or down of the content of the fraction is within the scope disclosed in the description of the embodiments of the present application. Specifically, the mass in the description of the embodiments of the present application may be µg, mg, g, kg and other well-known mass units in the chemical industry.

The terms "first" and "second" are only used for descriptive purposes to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX can also be called the second XX, and similarly, the second XX can also be called the first XX. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features.

As shown in Figure 1, the first aspect of the embodiment of the present application provides a method for preparing a direct X-ray image detector, including the following steps:

S10. Synthesizing long-chain organic carboxylic acids and organic ligands into ionic liquids;

S20. dissolving the ionic liquid, the carbon group metal halide and the halide salt in an organic solvent to obtain a precursor gel; the halide salt includes an organic ammonium halide or an alkali metal halide;

S30. Obtaining a substrate with a pixel array distributed on its surface, forming a film of the precursor gel on the surface of the pixel array of the substrate, annealing, and forming a two-dimensional hybrid perovskite quantum array film layer on the surface of the pixel array of the substrate;

S40. Prepare an electrode layer on the surface of the quantum array film layer away from the substrate to obtain a direct X-ray image detector.

The general structural formula of the two-dimensional hybrid perovskite in the quantum array film layer prepared in the embodiment of the present application is A'A _n-1 B _n X _3n+1 and/or A' ₂ A _n-1 B _n X _{3n+ 1.} The carbon group metal ion at the B position and the halogen ion at the X position form a [BX ₆ ] octahedron through coordination, and the cations such as ammonium ions or alkali metal ions at the A position are distributed in the gaps generated by the octahedral common top connection, and the coordination The number is 12, and the organic ligand at the A' position is bonded to the anion on the edge of the octahedron through electrostatic attraction, forming an organic spacer layer. When the dielectric constant of the spacer layer does not match the octahedral sheet, the [BX ₆ ] octahedral layer forms a natural quantum well, where n represents the well width of the quantum well, that is, the number of octahedral layers, preferably 2-10. In the direct X-ray image detector prepared in the embodiment of the present application, the quantum array film layer can absorb X-rays and directly convert them into electrical signals. It is evenly transmitted to the substrate formed with the pixel array, and then the electrical signal is converted into an image, and high-definition images with different color shades are formed according to the intensity of the electrical signal.

The preparation method of the direct X-ray image detector provided in the first aspect of the embodiment of the present application uses long-chain organic carboxylic acid and organic ligand to synthesize ionic liquid, and then dissolves ionic liquid, halide carbon group metal and halide salt in organic solvent , using the strong coordination between the carbonyl group and the octahedral central cation, and the intermolecular force between the carboxylic acid alkyl chains, to reduce the driving force of [BX ₆ ] octahedral aggregation, inhibit the rapid aggregation of octahedron, and improve the precursor The viscosity of the precursor solution forms a stable precursor gel. It is then deposited on the substrate with the pixel array, and the gel film layer is constructed in situ. During the deposition process, the octahedron of the two-dimensional hybrid perovskite and the interlayer organic cation self-assemble through the intermolecular force, and the pixel array is perpendicular to the Basal growth. While the two-dimensional hybrid perovskite crystals grow, the strong coordination between the carbonyl group in the long-chain organic acid and the octahedral central cation makes the organic solvent and carboxylic acid in the gel layer volatilize at a uniform speed, and through annealing treatment , a two-dimensional hybrid perovskite quantum array film is formed. Then an electrode layer is prepared on the surface of the quantum array film layer away from the substrate to obtain a direct X-ray image detector. The preparation method of the direct-type X-ray image detector in the embodiment of the present application introduces long-chain organic carboxylic acid, reduces the aggregation rate of [BX ₆ ] octahedron, and increases the viscosity of the precursor solution, which not only can construct a quantum well array with a wide distribution of single wells , and can increase the film thickness of the quantum array film layer, thereby improving the ability of the direct type X-ray image detector to capture X-rays, and improving the absorption and conversion efficiency of the device for X-rays. Realize high-definition imaging of X-rays.

In some embodiments, in the above step S10, the long-chain organic carboxylic acid and the organic ligand are synthesized into an ionic liquid, and the high viscosity, boiling point and solubility of the ionic liquid, as well as the recrystallization purification of the ionic liquid, improve the product purity and reduce the The influence of raw material impurities on the crystallization product improves the crystallization efficiency and purity of the subsequent two-dimensional hybrid perovskite.

In some embodiments, in the above step S10, the long-chain organic carboxylic acid has 3 to 10 carbon atoms, and the organic carboxylic acid with the length of carbon atoms can not only better adjust the driving force of [BX ₆ ] octahedral aggregation , and have better intermolecular forces, which can effectively adjust the aggregation rate of octahedra and the viscosity of the precursor solution, thereby regulating the crystallization rate and growth method of the two-dimensional hybrid perovskite, ensuring that the two-dimensional hybrid perovskite Uniform growth along the direction perpendicular to the substrate to construct a quantum well array with a single well width distribution. If the number of carbon atoms in the organic carboxylic acid is too low, the adjustment effect on the aggregation rate of the octahedron and the viscosity of the precursor solution is not good; if the number of carbon atoms in the organic carboxylic acid is too high, it will not be conducive to volatilization, and lead to The crystallization and growth rates of hybrid perovskites are too slow to even affect crystal formation. Specifically, the number of carbon atoms of the long-chain organic carboxylic acid may be 3, 4, 5, 6, 7, 8, 9, 10, etc. In some specific embodiments, the long-chain organic carboxylic acid is selected from at least one of propionic acid, n-butyric acid, isobutyric acid, and n-valeric acid. Further preferably, the long-chain organic carboxylic acid is selected from at least one of propionic acid, n-butyric acid and isobutyric acid.

In some embodiments, the organic ligand is selected from: at least one of n-butylamine, isobutylamine, α-phenethylamine, allylamine, and 2-thio-ethylamine; these organic ligands pass through The electrostatic attraction bonds with the anions at the edge of the octahedron to form an organic spacer layer. When the dielectric constant of the spacer layer is mismatched with the octahedral sheet, the [BX ₆ ] octahedral layer forms a natural quantum well.

In some embodiments, the method for synthesizing the ionic liquid adopts a reduced-pressure rotary evaporation method.

In some embodiments, the step of synthesizing an ionic liquid comprises:

S11. Mixing the long-chain organic carboxylic acid and the organic ligand at a temperature of 0°C to 5°C to obtain a crude product. Wherein, the molar ratio of the long-chain organic carboxylic acid and the organic ligand is preferably 1:1. Preferably, the mixing treatment time is 1 to 3 hours. An acid-base reaction occurs between an organic carboxylic acid and an organic ligand, such as: R-COOH+R-NH ₂ →R-COONH ₃ -R, the reaction is an exothermic reaction, and the temperature of the examples in this application is 0℃~5℃ The mixed treatment can reduce the heat of the reaction system and remove impurities whose freezing point is higher than that of the ice-water bath.

S12. Rotate the crude product under reduced pressure at a temperature of 60-100°C to collect the product. Further, the crude product was reacted in a reduced-pressure rotary evaporator at a temperature of 70-90°C for 1-3 hours to remove the solvent by volatilization, and the product was collected by distillation.

S13. The product is subjected to crystallization treatment under the condition of crystallization below the freezing point at a temperature of -30~-10°C to obtain a crystalline product. The preferred crystallization time is 1-3 hours.

S14. Purify the crystalline product to obtain an ionic liquid. In a specific embodiment, the purification step includes: washing the crystallized product three times with diethyl ether, dichloromethane, cyclohexane, petroleum ether, etc., re-dissolving with solvents such as ethanol, acetone, tetrahydrofuran, dichloromethane, etc., adding diethyl ether, dichloromethane, etc. Recrystallize three times from methane, cyclohexane, petroleum ether, etc.; the recrystallized product is dissolved in solvents such as ethanol, acetone, tetrahydrofuran, and dichloromethane again, and reacted in a vacuum rotary evaporator at 60-100°C for 1 h, preferably 70~90°C, the collected liquid product is an ionic liquid, and the ionic liquid is cooled to room temperature for later use.

In some embodiments, in the above step S20, the step of preparing the precursor gel includes: after dissolving the ionic liquid, the halide carbon group metal and the halide salt in the organic solvent, the temperature is kept at 90-110°C for 5~ 120s, preferably 10-30s, to concentrate the solution to a gel state with higher viscosity. During the preparation of the precursor gel in the example of this application, the strong coordination between the carbonyl group and the octahedral central cation and the intermolecular force between the carboxylic acid alkyl chains are used to reduce the driving force for [BX ₆ ] octahedral aggregation , to suppress the rapid aggregation of octahedra while increasing the viscosity of the precursor solution to form a stable precursor gel.

In some embodiments, the carbon group metal halide is selected from at least one of lead chloride, lead bromide, lead iodide, tin chloride, tin bromide, and tin iodide; these carbon group metal halides can be combined with organic Self-assembly of ammonium halide or alkali metal halide introduces carbon group metals such as lead and tin into the lattice of two-dimensional hybrid perovskite. The absorption efficiency of carbon group metals such as lead and tin on X-rays is high, which can significantly improve X-ray absorption efficiency of two-dimensional hybrid perovskite.

In some embodiments, the organic ammonium halide salt is selected from the group consisting of: CH ₃ NH ₃ Cl, CH ₃ NH ₃ Br, CH ₃ NH ₃ I, CH ₂ (NH ₃ ) ₂ Cl, CH ₂ (NH ₃ ) ₂ Br, CH At least one of ₂ (NH ₃ ) ₂ I; these organic ammonium halide salts can form perovskite materials through self-assembly with halogenated carbon group metals, and CH ₃ NH ₃ ⁺ , CH ₂ (NH ₃ ) Organic ammonium ions such as ₂ ⁺ can effectively improve the thermal stability of perovskite materials.

In some embodiments, the alkali metal halide is selected from at least one of: CsCl, CsBr, CsI, RbCl, RbBr, and RbI; these alkali metal halides can form perovskite materials through self-assembly with carbon group metal halides, calcium The introduction of alkali metal ions such as Cs ⁺ , Rb ⁺ into titanium materials can effectively improve the thermal stability of perovskite materials.

In some embodiments, the organic solvent is selected from: a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide. Further, in the organic solvent, the volume ratio of dimethyl sulfoxide and N,N-dimethylformamide is (1~4):(1~4). In some specific embodiments, the volume ratio of dimethyl sulfoxide and N,N-dimethylformamide can be 4:1, 3:2, 2:3, 1:4, etc., preferably 2:3 or 1 :4. The mixed organic solvent used in the examples of this application not only has a good dissolving effect on the raw material components, but also facilitates the contact reaction between the components; it is also beneficial to control the growth rate and orientation of the two-dimensional hybrid perovskite, and to optimize the Crystalline quality. Specifically, the S=O bond in DMSO is easy to coordinate with the B-site cations in the two-dimensional hybrid perovskite to form an intermediate, preventing perovskite [BX ₆ ] octahedra such as [PbI ₆ ] rapid aggregation. In this way, the nucleation reaction is reduced, and the quality of the film layer is optimized, mainly the orientation and grain size, and the large grain size contributes to the sensitivity of X-rays. However, due to the high boiling point of dimethyl sulfoxide, the volatilization speed is too slow, which will increase the roughness of the film layer, which is not conducive to X-ray response. N,N-dimethylformamide is a good solvent for perovskite precursors, and its effect is similar to that of dimethyl sulfoxide, but the interaction between C=O and B-site cations is weak, and the boiling point is low. The nucleation rate suppression effect of hybrid perovskite crystals is poor. Therefore, using a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide, the ratio of the two affects the volatilization rate of the system solvent, thereby affecting the orientation of the film layer.

In some embodiments, in the above step S30, the annealing step includes: scraping the precursor gel onto the surface of the pixel array of the substrate at a temperature of 100-150°C; Annealing under low conditions for 5-20 minutes. In the embodiment of the present application, the precursor gel is scraped onto a substrate with a pixel array formed at a temperature of 100-150°C. The thickness of the array film layer improves the absorption efficiency of the device for X-rays; on the other hand, the hot substrate is conducive to the growth of the two-dimensional hybrid perovskite along the direction perpendicular to the substrate, forming a quantum well with a vertical substrate orientation. Then, annealing is carried out at a temperature of 80-150°C for 5-20 minutes. Through the thermal disturbance during the annealing process, the two-dimensional hybrid perovskite is further self-assembled, and the crystal form of the perovskite is more ordered. Improve the purity and integrity of the two-dimensional hybrid perovskite to make its performance more stable, so as to obtain the quantum array film layer of the two-dimensional hybrid perovskite vertically grown on the surface of the pixel array. If the annealing rate is too slow or the annealing temperature is too low, the optimization effect on the crystal form and purity of the two-dimensional hybrid perovskite is not good, which is not conducive to improving the stability of the two-dimensional hybrid perovskite; if the annealing heating rate is too high Fast or the temperature is too high, the material is easy to decompose.

In some embodiments, in the direct-type X-ray image detector, the thickness of the quantum array film layer is 8-20 μm, which improves the ability of the direct-type X-ray image detector to capture X-rays, and improves the device's ability to capture X-rays. absorption conversion efficiency. In some specific embodiments, in the direct X-ray image detector, the thickness of the quantum array film layer includes but is not limited to 8-10 μm, 10-12 μm, 12-15 μm, 15-18 μm, 18-20 μm, etc.

In some embodiments, the step of cleaning the substrate formed with the pixel array is also included: the substrate formed with the pixel array is successively washed in an ultrasonic cleaner with solvents such as deionized water, acetone, ethanol and isopropanol, using Dry with nitrogen flow, and clean in an ultraviolet ozone cleaning machine for 0-20 min, preferably 10-15 min. Next, place the substrate formed with the pixel array on a film coating machine and preheat to 80-150°C, preferably 100-120°C.

In some embodiments, in the above step S40, the electrode layer prepared on the surface of the quantum array film layer away from the substrate may be a carbon electrode or a metal electrode. In some specific embodiments, the preparation of the carbon electrode includes the steps of: coating the carbon paste on the surface of the quantum array film by scraping, and then curing at 80-120°C for 5-45 minutes, preferably at 90-110°C , cured for 20-30 min to form a carbon electrode layer. In other embodiments, the metal electrode can be prepared by vacuum evaporation or sputtering, and the electrode layer can be made of Al, Ag, Au, Cu and other metal materials.

As shown in Figure 2, the second aspect of the embodiment of the present application provides a direct X-ray image detector prepared in the above embodiment, including: a substrate, a pixel array bonded to the surface of the substrate, and a quantum sensor vertically grown on the surface of the pixel array. The array film layer, and the electrode layer laminated on the surface of the quantum array film layer; wherein, the quantum array film layer contains a general structural formula of A'A _n-1 B _n X _3n+1 and/or A' ₂ A _n-1 B _n X _3n+1 two-dimensional hybrid perovskite, where A' is an organic ligand, A is an ammonium ion or an alkali metal ion, B is a carbon group metal ion, and X is a halogen ion; n is 2~10.

The direct X-ray image detector prepared by the method of the above embodiment provided in the second aspect of the embodiment of the present application includes a laminated substrate-pixel array-quantum array film layer-electrode layer, and the structure in the quantum array film layer A two-dimensional hybrid perovskite with the general formula A'A _n-1 B _n X _3n+1 and/or A' ₂ A _n-1 B _n X _3n+1 , the carbon group metal ion at the B site and the X site The halide ions form the [BX ₆ ] octahedron through coordination, and cations such as ammonium ions or alkali metal ions at the A site are distributed in the gaps generated by the octahedral common top connection. The coordination number is 12, and the organic ligand at the A' Gravity bonds to the anions at the edges of the octahedrons, forming an organic spacer layer. When the dielectric constant of the spacer layer does not match the octahedral sheet, the [BX ₆ ] octahedral layer forms a natural quantum well, where n represents the well width of the quantum well, that is, the number of octahedral layers. The quantum well structure has a confinement effect on the carriers. The two-dimensional hybrid perovskite grown vertically on the surface of the pixel array in the quantum array film layer of the embodiment of the present application allows the carriers in the quantum array film layer to move along the direction of the quantum well. Directional migration in the growth direction suppresses lateral drift and scattering of carriers, improves carrier transfer efficiency, and avoids carrier loss. In addition, the direct X-ray image detector prepared by the method of the above embodiment can not only construct a quantum well array with a single well width distribution, but also allow carriers to be uniformly transported to the array substrate, which is to realize high-definition imaging of the X-ray direct detector; Moreover, the film thickness of the quantum array film layer can be increased, thereby improving the ability of the direct type X-ray image detector to capture X-rays, thereby further improving the absorption and conversion efficiency of the device for X-rays. Therefore, the direct X-ray image detector provided by the embodiment of the present application has pixel confinement characteristics, can directly absorb and convert X-rays into charge carriers, has high X-ray absorption conversion efficiency, and high detection sensitivity.

In some embodiments, the organic ligand is selected from: at least one of n-butylamine, isobutylamine, α-phenethylamine, allylamine, and 2-thio-ethylamine; these organic ligands pass through The electrostatic attraction bonds with the anions at the edge of the octahedron to form an organic spacer layer. When the dielectric constant of the spacer layer is mismatched with the octahedral sheet, the [BX ₆ ] octahedral layer forms a natural quantum well, two-dimensional hybridization In the perovskite, n represents the well width of the quantum well, that is, the number of octahedral layers.

In some embodiments, the organic ammonium ion is selected from at least one of: CH ₃ NH ₃ ⁺ , CH ₂ (NH ₃ ) ₂ ⁺ ; these organic ammonium ions can effectively improve the thermal stability of the two-dimensional hybrid perovskite performance.

In some embodiments, the alkali metal ions are selected from at least one of Cs ⁺ and Rb ⁺ ; these alkali metal ions can effectively improve the thermal stability of the two-dimensional hybrid perovskite.

In some embodiments, the carbon group metal ion is selected from: at least one of lead and tin; these carbon group metals have high absorption efficiency for X-rays, and can significantly improve the absorption efficiency of two-dimensional hybrid perovskites for X-rays .

In some embodiments, the halide ion is selected from at least one of chlorine, bromine, and iodine. Halogen ions form [BX ₆ ] regular octahedra with carbon group metal elements in the form of 6 coordination, and eight [BX ₆ ] regular octahedrons form a cage in the form of common vertex connection, and A is ammonium ion or alkali metal ion occupying the cage The center plays a supporting role in the perovskite structure and forms 12 coordination with halogen. The organic ligands at the A' site are bonded to the anions at the edge of the octahedron through electrostatic attraction, forming an organic spacer layer.

In some embodiments, the materials of the pixel array include: indium tin oxide (ITO), fluorine-doped SnO ₂ conductive glass (FTO), poly-3-hexylthiophene and fullerene derivative [6,6]-phenyl - At least one of the blends of C61-isomethyl butyrate (P3HT:PCBM).

In some embodiments, the material of the substrate is selected from glass.

In some embodiments, the electrode layer is selected from at least one of carbon electrodes and metal electrodes. In some specific embodiments, metal materials such as Al, Ag, Au, and Cu may be used for the electrode layer.

In order to make the above-mentioned implementation details and operations of the present application clearly understood by those skilled in the art, and to demonstrate the remarkable performance of the direct X-ray image detector and its manufacturing method in the embodiment of the present application, the following examples are given through multiple embodiments The above-mentioned technical solution will be described.

Example 1

A kind of direct type X -ray image detector, its preparation comprises the steps:

① Propionic acid and n-butylamine organic ligand (A’) with a molar ratio of 1:1 were stirred in an ice-water bath at 0°C for 2 h to mix well. The crude product was then transferred to a vacuum rotary evaporator, reacted at 80 °C for 1 h, and collected the product; then the product was placed in the refrigerator at low temperature (about -20 °C) for 2 h, and the crystallized product was washed three times with ether , redissolved in ethanol and recrystallized three times by adding ether; the obtained crystalline product was dissolved in ethanol again, reacted in a vacuum rotary evaporator at 80 °C for 1 h, and collected the liquid product as ionic liquid (A'Oc). The ionic liquid was cooled to room temperature for later use.

② Dissolve step ① ionic liquid, methylamine hydroiodide (MAI) and lead iodide (PbI ₂ ) in a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide (volume ratio of 1 :4), raise the temperature of the obtained solution to 100°C, set the constant temperature time for 30 s, lower the temperature to room temperature, and concentrate the solution to a high-viscosity gel to obtain a precursor gel; wherein, the reaction equation is: , that is, ionic liquid, Methylamine hydroiodide (MAI), lead iodide (PbI ₂ ) react by the ratio of the amount of substance of 2:(n+1):n, wherein n is 10, and the concentration of lead iodide in solvent is 3 mol/L, the total solvent volume is 0.5 ml.

③ After obtaining the indium tin oxide pixel substrate (10×10 μm indium tin oxide pixel dot substrate distributed on the glass substrate), wash the indium tin oxide substrate in an ultrasonic cleaner successively using deionized water, acetone, ethanol and isopropanol , dried with nitrogen flow, cleaned in a UV ozone cleaning machine for 15 min, and then placed the indium tin oxide substrate on a film coating machine to preheat to 120 °C; then the precursor gel was dropped onto the hot indium tin oxide substrate, Set the temperature program to adjust the substrate temperature to 130 °C, set the constant temperature time to 120 s, and move the scraper at the same time to make the precursor gel form a uniform film layer on the base substrate. Set the temperature of the coating machine at 120°C, hold the constant temperature for 10 min, and anneal to form a quantum array film with pixel confinement to obtain a two-dimensional hybrid perovskite quantum array film with a thickness of 18-20 μm.

④ On the quantum array film, the carbon paste was coated on the surface of the film by scraping. The amount of carbon paste was 80 μL, and then cured at 110°C for 30 min to form a carbon electrode and prepare a direct X-ray image detector.

Example 2

A direct type X -ray image detector, the difference between it and Embodiment 1 is that in step ①, n-butylamine is replaced by phenethylamine.

Example 3

A direct X-ray image detector, the difference from Embodiment 1 is that in step ①, lead iodide is replaced by lead bromide.

Comparative example 1

A direct type X -ray image detector, the difference from Embodiment 1 is: in step ①, propionic acid is replaced by acetic acid. In step ③, the precursor gel is deposited on the indium tin oxide pixel substrate by spin coating, and annealed to form a quantum array film with pixel confinement. In the obtained direct X-ray image detector, the two-dimensional hybrid calcium The thickness of the titanite quantum array thin film is about 0.5 μm.

Further, in order to verify the progress of the embodiments of the present application, the photocurrent density of the film layer of the direct X-ray image detector prepared in Examples 1 to 3 and Comparative Example 1 was measured under different dose rates of X-ray irradiation. Change, and calculate the X-ray sensitivity according to the fitting line, that is, the slope of the line, and the average energy of X-ray is about 20 keV. The test results are shown in Figure 3, where the abscissa is the dose rate, and the ordinate is the photocurrent density. It can be seen from the test results of accompanying drawing 3 that the ionic liquid prepared from long-chain carboxylic acid as raw material is used as the precursor of perovskite in the process of direct type X-ray image detector in Examples 1 to 3 of the present application, and the method by scraping Compared with Comparative Example 1, which did not use long-chain carboxylic acid, the prepared direct X-ray image detector exhibited higher X-ray sensitivity, indicating that the long-chain carboxylic acid-type ionic liquid is conducive to the construction of thicker quantum arrays The film layer is beneficial to improve the sensitivity of the direct type X-ray image detector, thereby improving the imaging clarity of the X-ray.

The above descriptions are only preferred embodiments of the application, and are not intended to limit the application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the application should be included in the protection of the application. within range.

Claims

A method for preparing a direct type X-ray image detector, characterized in that it comprises the following steps:

Synthesis of long-chain organic carboxylic acids and organic ligands into ionic liquids;

Dissolving the ionic liquid, carbon group metal halide and halide salt in an organic solvent to obtain a precursor gel; the halide salt includes an organic ammonium halide or an alkali metal halide;

Obtaining a substrate with a pixel array distributed on its surface, forming a film of the precursor gel on the surface of the pixel array of the substrate, annealing, and forming a two-dimensional hybrid perovskite quantum array film on the surface of the pixel array of the substrate layer;

An electrode layer is prepared on the surface of the quantum array film layer away from the substrate to obtain a direct X-ray image detector.
The preparation method of direct type X-ray image detector as claimed in claim 1, is characterized in that, the carbon atom number of described long-chain organic carboxylic acid is 3～10;

And/or, the organic ligand is selected from: at least one of n-butylamine, isobutylamine, α-phenethylamine, allylamine, and 2-thio-ethylamine;

And/or, in the direct X-ray image detector, the thickness of the quantum array film layer is 8-20 μm.
The preparation method of direct type X-ray image detector as claimed in claim 2, is characterized in that, described long-chain organic carboxylic acid is selected from: at least one in propionic acid, n-butyric acid, isobutyric acid, n-valeric acid kind;

And/or, the method for synthesizing the ionic liquid adopts a vacuum rotary evaporation method.
The preparation method of direct type X-ray image detector as claimed in claim 3, is characterized in that, the step of synthesizing described ionic liquid comprises:

Mixing the long-chain organic carboxylic acid and the organic ligand at a temperature of 0°C to 5°C to obtain a crude product;

The crude product was rotary evaporated under reduced pressure at a temperature of 60-100°C, and the product was collected;

The product is subjected to crystallization treatment at a temperature of -30~-10°C to obtain a crystalline product;

The crystalline product is purified to obtain the ionic liquid.
The method for preparing a direct X-ray image detector according to any one of claims 1 to 4, wherein the halocarbon group metal is selected from the group consisting of: lead chloride, lead bromide, lead iodide, lead chloride At least one of tin, tin bromide, and tin iodide;

And/or, the organic ammonium halide salt is selected from: methylamine hydroiodide, CH 3 NH 3 Cl, CH 3 NH 3 Br, CH 3 NH 3 I, CH 2 (NH 3 ) 2 Cl, CH 2 ( At least one of NH 3 ) 2 Br, CH 2 (NH 3 ) 2 I;

And/or, the alkali metal halide is selected from: at least one of CsCl, CsBr, CsI, RbCl, RbBr, RbI;

And/or, the organic solvent is selected from: a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide.
The method for preparing a direct X-ray image detector according to claim 5, wherein the step of preparing the precursor gel comprises: mixing the ionic liquid, the carbon group metal halide and the halide salt After being dissolved in an organic solvent, heat preservation at a temperature of 90-110°C for 5-120s to obtain the precursor gel;

And/or, the step of the annealing treatment includes: at a temperature of 100-150°C, after scraping the precursor gel onto the surface of the pixel array of the substrate, at a temperature of 80-150°C Dry and anneal for 5-20 minutes under the same conditions;

And/or, in the organic solvent, the volume ratio of the dimethyl sulfoxide to the N,N-dimethylformamide is (1-4):(1-4).
A direct X-ray image detector prepared by the method according to any one of claims 1 to 6, characterized in that it comprises: a substrate, a pixel array bonded to the surface of the substrate, and a pixel array vertically grown on the surface of the pixel array The quantum array film layer, and the electrode layer laminated on the surface of the quantum array film layer; wherein, the quantum array film layer contains a general structural formula of A'A n-1 B n X 3n+ 1 and/or A' 2 A n-1 B n X 3n+1 two-dimensional hybrid perovskite, where A' is an organic ligand, A is an ammonium ion or an alkali metal ion, and B is a carbon group metal ion , X is a halide ion; n is 2~10.
The direct X-ray image detector according to claim 7, wherein, in the direct X-ray image detector, the thickness of the quantum array film layer is 8-20 μm.
The direct X-ray image detector according to claim 7, wherein the organic ligand is selected from the group consisting of: n-butylamine, isobutylamine, α-phenylethylamine, allylamine, 2-thio - at least one of ethylamines;

And/or, the organic ammonium ion is selected from: at least one of CH 3 NH 3 + , CH 2 (NH 3 ) 2 + ;

And/or, the alkali metal ion is selected from: at least one of Cs + and Rb + ;

And/or, the carbon group metal ion is selected from: at least one of lead and tin;

And/or, the halide ion is selected from at least one of chlorine, bromine, and iodine.
The direct X-ray image detector according to any one of claims 7 to 9, wherein the material of the pixel array comprises: at least one of ITO, FTO, P3HT:PCBM;

And/or, the material of the substrate is selected from glass;

And/or, the electrode layer is selected from at least one of carbon electrodes and metal electrodes.