Method for preparing quasi-two-dimensional perovskite thick film and application thereof

Abstract

The invention relates to the technical field of perovskite material preparation, in particular to a method for preparing a quasi-two-dimensional perovskite thick film and application of the quasi-two-dimensional perovskite thick film. The method comprises the following steps: mixing DMePDAI2 and FA < 0.5 > MA < 0.5 > PbI3 to obtain perovskite mixed powder; the method comprises the following steps: dissolving perovskite mixed powder by using N, N-dimethylformamide to obtain a quasi-two-dimensional perovskite precursor crude solution; stirring the quasi-two-dimensional perovskite precursor crude solution and acetonitrile to obtain a quasi-two-dimensional perovskite precursor solution; preheating the seed layer to obtain a preheated seed layer; spraying a quasi-two-dimensional perovskite precursor solution to the surface of the preheated seed layer to obtain a coarse perovskite thick film; the spraying temperature is lower than 100 DEG C; and annealing the coarse perovskite thin film to obtain the perovskite thick film. According to the method, the viscosity, the boiling point and the saturated vapor pressure of the quasi-two-dimensional perovskite precursor solution can be adjusted by adding acetonitrile, so that the quality of the perovskite thick film prepared by a spraying coating method is improved.

Description

Technical Field

[0001] The present application relates to the technical field of perovskite material preparation, and particularly relates to a method for preparing a quasi-two-dimensional perovskite thick film and its application. Background Art

[0002] Lead halide perovskite can be used as a raw material for X-ray detectors in the direct detection mode, and there have been reports on the use of lead halide perovskite for low-dose digital radiography. Currently, perovskite thin film detectors have been first applied in X-ray imaging with a single-pixel setup, and clearly revealed the structure of leaf veins. If methylammonium lead iodide (MAPbI 3 ) polycrystals are integrated into the transistor array of a perovskite thin film detector, high-resolution X-ray images can be achieved. In addition, the application of large-area sintered perovskite wafers in X-ray detection has also been realized. The above-mentioned perovskite detectors all exhibit remarkable X-ray sensitivity, ranging from 10 3 μC·Gyair -1 ·cm -2 ~10 6 μC·Gyair -1 ·cm -2 , which is attributed to the strong stopping ability of the perovskite structure and efficient carrier transport. In addition, the raw material cost of halide perovskite is relatively low, and the preparation of halide perovskite can be integrated into devices as thick films through inexpensive methods such as hot pressing, aerosol-liquid-solid method, solution infiltration method, and slow crystallization method. However, it is difficult to prepare high-quality and thick perovskite thin films by these methods.

[0003] The spray coating method is a mature technology and is currently widely used in the preparation of automotive paint and anti-corrosion coatings for ferries. Compared with spin coating or blade coating techniques, the spray coating technique is not limited by the shape of the substrate. In addition, spraying is a pressure-driven coating process. The principle is that the spray solvent will quickly volatilize under strong airflow conditions, causing the coating material to deposit on the substrate surface. During this process, the deposited coating material is already in a supersaturated state, which makes the subsequent coating not dissolve the coating already deposited on the substrate surface, so that the thickness of the deposited coating can be evenly stacked layer by layer to hundreds of micrometers or even millimeters. However, the perovskite precursor needs to completely volatilize the solvent at high temperature to form a dry perovskite thick film. However, the high-temperature environment will not only directly affect the components of the perovskite, seriously reducing the performance of the X-ray detector, but also cause explosive crystallization and nucleation of the coating material, affecting the quality of the perovskite crystals. Summary of the Invention

[0004] The present application provides a method for preparing a quasi-two-dimensional perovskite thick film and its application to solve the following technical problem: how to improve the quality of the perovskite thick film prepared by the spray coating method.

[0005] In a first aspect, the present application provides a method for preparing a quasi-two-dimensional perovskite thick film, the method comprising:

[0006] Mix DMePDAI 2 and FA 0.5 MA 0.5 PbI 3 to obtain a perovskite mixed powder;

[0007] Dissolve the perovskite mixed powder using N,N-dimethylformamide to obtain a crude quasi-two-dimensional perovskite precursor solution;

[0008] Stir the crude quasi-two-dimensional perovskite precursor solution and acetonitrile to obtain a quasi-two-dimensional perovskite precursor solution;

[0009] Preheat the seed layer to obtain a preheated seed layer;

[0010] Spray the quasi-two-dimensional perovskite precursor solution onto the surface of the preheated seed layer multiple times to obtain a crude perovskite thick film; wherein, the temperature of the spraying < 100 °C;

[0011] Anneal the crude perovskite thin film to obtain a perovskite thick film.

[0012] Optionally, the volume V1 of the N,N-dimethylformamide and the volume V2 of the acetonitrile satisfy: V1:V2 = (4 - 9):1.

[0013] Optionally, the volume V1 of the N,N-dimethylformamide and the volume V2 of the acetonitrile satisfy: V1:V2 = 9:1.

[0014] Optionally, the amount of substance n1 of the DMePDAI 2 and the amount of substance n2 of the FA 0.5 MA 0.5 PbI 3 satisfy the relationship: n1:n2 ≥ 1:21.

[0015] Optionally, the temperature of the spraying is 85 °C - 95 °C, and the spraying time is 15 min - 25 min.

[0016] Optionally, the spraying amount of the spraying is 0.5 mL - 1.5 mL, and the interval between two adjacent sprayings is 25 s - 35 s.

[0017] Optionally, the temperature of the preheating is 85 °C - 95 °C; and / or

[0018] The temperature of the annealing is 85 °C - 95 °C, and the annealing time is 25 min - 35 min.

[0019] Optionally, before preheating the seed layer to obtain a preheated seed layer, the following steps are included:

[0020] Perform surface treatment on the conductive glass to obtain surface-treated glass;

[0021] Perform first spin coating on the surface of the surface-treated glass using an aqueous solution of tin oxide to obtain functional glass;

[0022] Mix biphenyltetracarboxylic dianhydride, p-phenylenediamine, and N-methylpyrrolidone to obtain a polyimide precursor solution;

[0023] Mix methylammonium iodide, lead iodide, and the polyimide precursor solution to obtain a perovskite seed layer solution;

[0024] Perform second spin coating on the surface of the functional glass using the perovskite seed layer solution to obtain a seed layer.

[0025] Optionally, the rotation speed of the first spin coating is 600 rpm to 2000 rpm, and the time of the first spin coating is 25 s to 35 s; and / or

[0026] The rotation speed of the second spin coating is 600 rpm to 2000 rpm, and the time of the second spin coating is 55 s to 65 s.

[0027] In a second aspect, the present application provides an X-ray detector, and the X-ray detector includes a quasi-two-dimensional perovskite thick film prepared by the method described in the first aspect.

[0028] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0029] A method for preparing a quasi-two-dimensional perovskite thick film provided by an embodiment of the present application adds acetonitrile during the preparation of the quasi-two-dimensional perovskite precursor solution. Based on the characteristics of the low molecular weight and low viscosity of acetonitrile, the low-viscosity solvent system of N,N-dimethylformamide and acetonitrile compared with the traditional solvent system of N,N-dimethylformamide and dimethyl sulfoxide, this low-viscosity solvent system has a faster mass transfer efficiency and mass transfer speed, and can effectively adjust the viscosity, boiling point, and saturation vapor pressure of the quasi-two-dimensional perovskite precursor solution, so that the quasi-two-dimensional perovskite precursor solution can also be spray-formed under relatively low temperature conditions below 100 °C. The relatively low temperature conditions can maximize the guarantee of the perovskite components and avoid the explosive precipitation and nucleation of crystals in the quasi-two-dimensional perovskite precursor solution, which affects the quality of the perovskite crystals, thereby improving the quality of the perovskite thick film prepared by the spray coating method. Description of the Drawings

[0030] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0031] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0032] Figure 1 Schematic flow diagram of a method for preparing a quasi-two-dimensional perovskite thick film provided by an embodiment of the present application;

[0033] Figure 2 Schematic detailed flow diagram of a method for preparing a quasi-two-dimensional perovskite thick film provided by an embodiment of the present application;

[0034] Figure 3 Electron microscopy observation result diagram of the samples of Example 1 and Comparative Example 1 of the present application after spraying for 3 s, wherein, Figure 3 A is the electron microscopy observation result diagram of the sample of Comparative Example 1 after spraying for 3 s, Figure 3 B is the electron microscopy observation result diagram of the sample of Example 1 after spraying for 3 s;

[0035] Figure 4 Scanning electron microscopy result diagram of the perovskite thick film provided by Example 1 of the present application;

[0036] Figure 5 ITO / SnO prepared from the perovskite thick film provided by Comparative Example 1 of the present application 2 / FA 0.5 MA 0.5 PbI 3 / Au device structure X-ray response degree result diagram;

[0037] Figure 6 ITO / SnO prepared from the perovskite thick film provided by Example 1 of the present application 2 / FA 0.5 MA 0.5 PbI 3 / Au device structure X-ray response degree result diagram;

[0038] Figure 7 ITO / SnO prepared from the perovskite thick film provided by Example 1 of the present application 2 / FA 0.5 MA 0.5 PbI 3 / Au device structure voltage-current comparison diagram. Detailed implementation manners

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0040] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within that range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0041] In this text, terms such as "including" mean "including but not limited to". Relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "multiple" means two or more; "at least one kind", "at least one of the following items" or similar expressions refer to any combination of these items, including any combination of single items or plural items; for example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both mean: a, b, c, a-b (that is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple respectively. "Part representation methods" such as weight parts and mass parts represent the proportional relationship between each component. In the proportional relationships involved in this text, the parameters that need to be described by the ratio should be understood as the antecedents of the ratio formula in the order of description, and the ratio numbers should be understood as the consequents of the ratio formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one by one with the ratio numbers in the ratio formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0042] It should be noted that the preparation of perovskite thick films is best in the form of quasi-single crystals. However, if the organic molecules (mainly MA) and iodide ions in the perovskite octahedral unit cell are affected by high temperature, they will decompose, and the decomposition of the organic molecules and iodide ions will destroy the unit cell structure of the perovskite, introducing more defects into the perovskite, thereby affecting the quality and electrical properties of the perovskite thick film.

[0043] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, and equipment used in this text can be obtained through market purchases or can be prepared by existing methods.

[0044] Figure 1 This application provides a schematic flow chart of a method for preparing a quasi-two-dimensional perovskite thick film for an embodiment of the application;

[0045] As Figure 1 shown, this application provides a method for preparing a quasi-two-dimensional perovskite thick film, and the method includes:

[0046] S1. Mix DMePDAI 2 and FA 0.5 MA0.5 PbI 3 Mix them to obtain perovskite mixed powder;

[0047] S2. Dissolve the perovskite mixed powder with N,N-dimethylformamide to obtain a quasi-two-dimensional perovskite precursor crude solution;

[0048] S3. Stir the quasi-two-dimensional perovskite precursor crude solution and acetonitrile to obtain a quasi-two-dimensional perovskite precursor solution;

[0049] S4. Preheat the seed layer to obtain a preheated seed layer;

[0050] S5. Spray the quasi-two-dimensional perovskite precursor solution onto the surface of the preheated seed layer multiple times to obtain a crude perovskite thick film; wherein, the spraying temperature < 100 °C;

[0051] S6. Anneal the crude perovskite thin film to obtain a perovskite thick film.

[0052] It should be noted that DMePDAI 2 is the solid powder of DMePDAI purchased from Xi'an YuRi Solar Energy Co., Ltd., and it is N,N-dimethyl-1,3-propanediamine hydroiodide (N,N-dimethyl-1,3-propanediamine iodide) throughout the process. 2

[0053] It should be noted that the embodiment of the present application provides a method for preparing a quasi-two-dimensional perovskite thick film. In the key process of preparing the quasi-two-dimensional perovskite precursor solution in this method, acetonitrile, a special substance, is ingeniously added. The added acetonitrile can be used as an organic solvent with unique physical and chemical properties. Based on its low molecular weight and the characteristic of showing a small mass and spatial size at the molecular level, acetonitrile molecules can move more flexibly in the solution system, greatly reducing the internal friction of the solution, and thus showing the characteristic of low viscosity.

[0054] In addition, when acetonitrile and N,N-dimethylformamide form a low-viscosity solvent system, it shows more significant advantages compared with the traditional N,N-dimethylformamide and dimethyl sulfoxide solvent systems. From the perspective of mass transfer, this low-viscosity solvent system has a faster mass transfer efficiency and mass transfer speed. Inside the solution, solute molecules can diffuse and migrate more rapidly in the low-viscosity environment, greatly improving the interaction and reaction rate between substances.

[0055] ​This excellent mass transfer performance is also reflected in the effective regulation of other physical properties of the solution. This low-viscosity solvent system can precisely control the viscosity of the quasi-two-dimensional perovskite precursor solution to an ideal range suitable for spray forming. At the same time, the boiling point and saturated vapor pressure of the solution are also optimized, enabling the quasi-two-dimensional perovskite precursor solution to still be smoothly spray-formed under relatively low temperatures, i.e., below 100 °C.

[0056] It is worth mentioning that the relatively low temperature condition plays a crucial role throughout the preparation process. In such a temperature environment, the components of the perovskite can be maximally protected, avoiding possible component decomposition or variation due to high temperatures. More critically, the low temperature effectively inhibits the explosive precipitation and nucleation of crystals in the quasi-two-dimensional perovskite precursor solution. Once explosive precipitation and nucleation of crystals occur, a large number of crystal nuclei will rapidly form in a short time, which will not only lead to uneven crystal growth but also may introduce various defects, seriously affecting the quality of the perovskite crystals. By using the low-viscosity solvent system and low-temperature conditions in this method, the above problems are successfully avoided, enabling the preparation of perovskite thick films with higher quality and better performance during the spray coating process. These high-quality perovskite thick films are expected to exhibit more excellent performance and broader application prospects in many applications such as the optoelectronic field.

[0057] In some alternative embodiments, the volume V1 of N,N-dimethylformamide and the volume V2 of acetonitrile satisfy: V1:V2 = (4 - 9):1.

[0058] In these embodiments, the volume V1 of N,N-dimethylformamide and the volume V2 of acetonitrile can satisfy: V1:V2 = (4 - 9):1, ensuring that the quasi-two-dimensional perovskite precursor solution has sufficient N,N-dimethylformamide and sufficient acetonitrile. Sufficient N,N-dimethylformamide can fully dissolve the perovskite mixed powder and facilitate the subsequent mixing of acetonitrile, while sufficient acetonitrile can effectively regulate the viscosity, boiling point, and saturated vapor pressure of the quasi-two-dimensional perovskite precursor solution, enabling the quasi-two-dimensional perovskite precursor solution to be spray-formed even under relatively low temperature conditions below 100 °C, thereby improving the quality of the perovskite thick films prepared by the spray coating method.

[0059] The value of the volume V1 of this N,N-dimethylformamide can be 4, 5, 6, 7, 8, or 9.

[0060] In some alternative embodiments, the volume V1 of N,N-dimethylformamide and the volume V2 of acetonitrile satisfy: V1:V2 = 9:1.

[0061] In these embodiments, the volume V1 of N,N-dimethylformamide and the volume V2 of acetonitrile may satisfy: V1:V2 = 9:1, further enabling the quasi-two-dimensional perovskite precursor solution to have sufficient N,N-dimethylformamide and sufficient acetonitrile. Sufficient N,N-dimethylformamide can fully dissolve the perovskite mixed powder and facilitate subsequent mixing with acetonitrile, while sufficient acetonitrile can effectively adjust the viscosity, boiling point, and saturated vapor pressure of the quasi-two-dimensional perovskite precursor solution, enabling the quasi-two-dimensional perovskite precursor solution to be spray-formed even at relatively low temperatures below 100 °C, thereby improving the quality of the perovskite thick film prepared by the spray coating method.

[0062] In some alternative embodiments, the amount of substance n1 of the DMePDAI 2 and the amount of substance n2 of the FA 0.5 MA 0.5 PbI 3 satisfy the relationship: n1:n2 ≥ 1:21.

[0063] In these embodiments, the amount of substance n1 of the DMePDAI 2 and the amount of substance n2 of the FA 0.5 MA 0.5 PbI 3 may satisfy the relationship: n1:n2 ≥ 1:21, such that the FA 0.5 MA 0.5 PbI 3 has sufficient DMePDAI 2 component. Sufficient DMePDAI 2 component can effectively improve the quality and performance of the quasi-two-dimensional perovskite precursor solution, thereby ultimately improving the quality and performance of the perovskite thick film.

[0064] In some alternative embodiments, the temperature of the spraying is 85 °C to 95 °C, and the time of the spraying is 15 min to 25 min.

[0065] In these embodiments, the temperature of the spraying can be 85 °C to 95 °C, and the time of the spraying can be 15 min to 25 min, such that the spraying has sufficient temperature and time. Sufficiently high temperature and sufficiently long spraying time can cause the solvent of the quasi-two-dimensional perovskite precursor solution to rapidly volatilize to form a perovskite crystal layer of sufficient thickness on the surface of the preheated seed layer.

[0066] The temperature of the spraying can be 85 °C, 89 °C, 90 °C, 91 °C, 92 °C, 93 °C, 94 °C, or 95 °C.

[0067] The spraying time can be 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min or 25 min.

[0068] In some alternative embodiments, the spraying volume is 0.5 mL to 1.5 mL, and the interval between two adjacent sprays is 25 s to 35 s.

[0069] In these embodiments, the spraying volume can be 0.5 mL to 1.5 mL, so that the discharge amount of the quasi-two-dimensional perovskite precursor solution in the spraying stage is controlled within an appropriate range, so that the solvent of the quasi-two-dimensional perovskite precursor solution can quickly volatilize under the conditions of the spraying temperature, so that a perovskite crystal with a sufficient thickness can be formed on the surface of the preheated seed layer; in addition, the interval between two adjacent sprays can be 25 s to 35 s, so that the solvent of the quasi-two-dimensional perovskite precursor solution can quickly volatilize, so that a perovskite crystal with a sufficient thickness can be formed on the surface of the preheated seed layer.

[0070] The spraying volume can be 0.5 mL, 0.6 mL, 0.7 mL, 0.8 mL, 0.9 mL, 1.0 mL, 1.1 mL, 1.2 mL, 1.3 mL, 1.4 mL or 1.5 mL.

[0071] The interval between two adjacent sprays can be 25 s, 26 s, 27 s, 28 s, 29 s, 30 s, 31 s, 32 s, 33 s, 34 s or 35 s.

[0072] In some alternative embodiments, the preheating temperature is 85 °C to 95 °C; and / or

[0073] The annealing temperature is 85 °C to 95 °C, and the annealing time is 25 min to 35 min.

[0074] In these embodiments, the preheating temperature can be 85 °C to 95 °C, so that the seed layer can be fully heated in the preheating stage, so as to facilitate the rapid volatilization of the solvent of the quasi-two-dimensional perovskite precursor solution in the subsequent spraying stage, so that a perovskite crystal with a sufficient thickness can be formed on the surface of the preheated seed layer; in addition, the annealing temperature can be 85 °C to 95 °C, and the annealing time can be 25 min to 35 min, so that the crude perovskite film is annealed under sufficient temperature conditions, so that the residual solvent of the crude perovskite film is fully volatilized, so that a perovskite crystal with a sufficient thickness can be formed on the surface of the preheated seed layer.

[0075] The preheating temperature can be 85 °C, 86 °C, 87 °C, 88 °C, 89 °C, 90 °C, 91 °C, 92 °C, 93 °C, 94 °C or 95 °C.

[0076] The annealing temperature can be 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C or 95°C.

[0077] The annealing time can be 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min or 35 min.

[0078] Figure 2 The figure provides a detailed process schematic diagram of a method for preparing a quasi-two-dimensional perovskite thick film in an embodiment of the present application;

[0079] In some alternative embodiments, as Figure 2 shown, before preheating the seed layer to obtain a preheated seed layer, it includes:

[0080] S401. Surface-treat the conductive glass to obtain surface-treated glass;

[0081] S402. Perform a first spin coating on the surface of the surface-treated glass with an aqueous solution of tin oxide to obtain functional glass;

[0082] S403. Mix pyromellitic dianhydride, p-phenylenediamine and N-methylpyrrolidone to obtain a polyimide precursor solution;

[0083] S404. Mix methylammonium iodide, lead iodide and the polyimide precursor solution to obtain a perovskite seed layer solution;

[0084] S405. Perform a second spin coating on the surface of the functional glass with the perovskite seed layer solution to obtain a seed layer.

[0085] In these embodiments, first perform a first spin coating on the surface of the surface-treated glass with an aqueous solution of tin oxide, so that the aqueous solution of tin oxide can fully adhere to the surface of the conductive glass to form a stable functional layer. Then mix pyromellitic dianhydride, p-phenylenediamine and N-methylpyrrolidone to obtain a polyimide precursor solution. Next, mix the polyimide precursor solution with methylammonium iodide and lead iodide to obtain a perovskite seed layer solution. Finally, perform a second spin coating on the surface of the functional glass with the perovskite seed layer solution, which can make the components of the perovskite seed layer solution stably adhere to the surface of the functional glass and form a seed layer.

[0086] In some alternative embodiments, the rotation speed of the first spin coating is 600 rpm to 2000 rpm, and the time of the first spin coating is 25 s to 35 s; and / or

[0087] The rotation speed of the second spin coating is 600 rpm to 2000 rpm, and the time of the second spin coating is 55 s to 65 s.

[0088] In these embodiments, the rotation speed of the first spin coating can be 600 rpm to 2000 rpm, and the time of the first spin coating can be 25 s to 35 s, so that the tin oxide aqueous solution can fully adhere to the surface of the conductive glass to form a stable functional layer; in addition, the rotation speed of the second spin coating can be 600 rpm to 2000 rpm, and the time of the second spin coating can be 55 s to 65 s, so that the perovskite seed layer solution can fully adhere to the surface of the functional glass, and the components of the perovskite seed layer solution can stably adhere to the surface of the functional glass and form a seed layer.

[0089] The rotation speed of the first spin coating can be 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm or 2000 rpm.

[0090] The time of the first spin coating can be 25 s, 26 s, 27 s, 28 s, 29 s, 30 s, 31 s, 32 s, 33 s, 34 s or 35 s.

[0091] The rotation speed of the second spin coating can be 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm or 2000 rpm.

[0092] The time of the second spin coating can be 55 s, 56 s, 57 s, 58 s, 59 s, 60 s, 61 s, 62 s, 63 s, 64 s or 65 s.

[0093] It should be noted that both the first spin coating and the second spin coating can run at a low rotation speed for a period of time and then at a high rotation speed for a period of time, so that the first spin coating and the second spin coating can be fully

[0094] Based on a general inventive concept, the embodiments of the present application provide an X-ray detector, and the X-ray detector includes the quasi-two-dimensional perovskite thick film prepared by the method.

[0095] The X-ray detector is implemented based on the above method. For the specific steps of the method, reference can be made to the above embodiments. Since the X-ray detector adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated one by one here.

[0096] The following further elaborates the present application in conjunction with specific embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually determined according to national standards / industry standards; if there are no corresponding national standards / industry standards, they are carried out according to general international standards, conventional conditions or the conditions recommended by the manufacturer.

[0097] Example 1

[0098] As Figure 2 shown, a method for preparing a quasi-two-dimensional perovskite thick film, the method comprising:

[0099] S1. Mix DMePDAI 2 and FA 0.5 MA 0.5 PbI 3 to obtain a perovskite mixed powder, wherein the molar ratio of DMePDA 2+ to FA + and MA + ions is 2:21:21;

[0100] S2. Dissolve the perovskite mixed powder with 9 mL of N,N-dimethylformamide to obtain a crude quasi-two-dimensional perovskite precursor solution;

[0101] S3. Stir the crude quasi-two-dimensional perovskite precursor solution and 1 mL of acetonitrile to obtain a quasi-two-dimensional perovskite precursor solution;

[0102] S401. Perform surface treatment on the ITO conductive glass to obtain surface-treated glass; the steps include:

[0103] Clean the ITO conductive glass, and then ultrasonically clean the cleaned ITO conductive glass in a glass cleaning agent, UP water, and ethanol for 30 min respectively, and then place the surface-treated ITO conductive glass in ethanol for standby to obtain surface-treated glass;

[0104] S402. Perform a first spin coating on the surface of the surface-treated glass with an aqueous tin oxide solution to obtain functional glass; the steps include:

[0105] Take out the hydrophilic colloid dispersion of tin dioxide and mix it with UP water in a volume ratio of 1:2 to obtain an aqueous tin dioxide solution; then take out the prepared aqueous tin dioxide solution after ultrasonic treatment for 30 min and set it aside. Then take out the surface-treated glass from ethanol, and then blow dry the ethanol on the surface of the surface-treated glass with compressed air. Then place the surface-treated glass on a spin coater, evenly spread the aqueous tin dioxide solution on the cleaned ITO conductive glass, and perform the first spin coating (first treat it at 600 rpm for 10 s and then at 2000 rpm for 20 s) to obtain a functional glass. The functional glass obtained after the first spin coating is placed on a hot stage and annealed at 150 °C for 1 h;

[0106] S403. Mix biphenyltetracarboxylic dianhydride, p-phenylenediamine and N-methylpyrrolidone to obtain a polyimide precursor solution; including the steps:

[0107] Weigh 2.86 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA, purity 95%) and 1.08 g of p-phenylenediamine (PD) and 22.35 g of N-methylpyrrolidone (NMP) respectively. First add NMP as a solvent, and then add the two solid drugs of BPDA and PD. After the preparation is completed, stir in time. Then stir the obtained mixed solution on a hot stage at 40 °C for more than 8 h. After preparation, there is no need to filter to obtain the polyimide precursor solution PI-NMP;

[0108] S404. Mix methylammonium iodide, lead iodide and the polyimide precursor solution to obtain a perovskite seed layer solution; including the steps:

[0109] Mix 4.8 g of the above polyimide precursor solution PI-NMP, 2.4 g of N,N-dimethylformamide (DMF), 1.5897 g of methylammonium iodide (MAI) and 4.6101 g of lead iodide (PbI 2 ) and stir for 10 h without heating to obtain a perovskite seed layer solution;

[0110] S405. Use the perovskite seed layer solution to perform the second spin coating on the surface of the functional glass to obtain a seed layer; including the steps:

[0111] Drop the perovskite seed layer solution evenly on the surface of the functional glass, and then perform the second spin coating (first treat it at 600 rpm for 10 s and then at 2000 rpm for 50 s). When the second spin coating starts for 40 s, drop 400 μL of chlorobenzene solution evenly on the center of the functional glass. After the spin coating is completed, place it on a hot stage and anneal at 100 °C for 30 min to prepare a seed layer of polymer PI perovskite;

[0112] S4. Preheat the seed layer of polymer PI perovskite on a hot stage to obtain a preheated seed layer;

[0113] S5. Spray the quasi-two-dimensional perovskite precursor solution onto the surface of the preheated seed layer multiple times to obtain a thick perovskite film; including the steps:

[0114] Take out 1 mL of the quasi-two-dimensional perovskite precursor solution, then ultrasonicate for 30 min, and then add it to a gas spray gun. The gas source used by the gas spray gun is nitrogen. Then spray the quasi-two-dimensional perovskite precursor solution onto the surface of the preheated seed layer at intervals multiple times to obtain a thick perovskite film;

[0115] S6. Anneal the thick perovskite film on a hot stage to obtain a thick perovskite film.

[0116] The volume V1 of N,N-dimethylformamide and the volume V2 of acetonitrile satisfy: V1:V2 = 9:1.

[0117] DMePDAI 2 The amount of substance n1 and FA 0.5 MA 0.5 PbI 3 The amount of substance n2 satisfy the relationship: n1:n2 = 1:21.

[0118] The spraying temperature is 90 °C, and the spraying time is 20 min.

[0119] The spraying amount is 1.0 mL, and the interval between two adjacent sprays is 30 s.

[0120] The preheating temperature is 90 °C;

[0121] The annealing temperature is 90 °C, and the annealing time is 30 min.

[0122] Example 2

[0123] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0124] The spraying temperature is 85 °C, and the spraying time is 25 min.

[0125] The spraying amount is 0.5 mL, and the interval between two adjacent sprays is 35 s.

[0126] The preheating temperature is 85 °C;

[0127] The annealing temperature is 85 °C, and the annealing time is 25 min.

[0128] Example 3

[0129] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0130] The spraying temperature is 95 °C, and the spraying time is 15 min.

[0131] The spraying volume is 1.5 mL, and the interval between two adjacent sprayings is 25 s.

[0132] The preheating temperature is 95 °C;

[0133] The annealing temperature is 95 °C, and the annealing time is 25 min.

[0134] Comparative Example 1

[0135] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0136] Dimethyl sulfoxide is used to replace acetonitrile.

[0137] Comparative Example 2

[0138] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0139] The spraying temperature is 150 °C.

[0140] Comparative Example 3

[0141] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0142] The spraying volume is 2.0 mL, and the spraying time is 10 min.

[0143] Comparative Example 4

[0144] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0145] The spraying volume is 0.2 mL, and the spraying time is 50 min.

[0146] Related experiments and effect data:

[0147] Figure 3 Exemplarily shown is the electron microscope observation result diagram of the samples after spraying for 3 s in Example 1 and Comparative Example 1 of the present application;

[0148] Figure 4 Exemplarily shown is the scanning electron microscope result diagram of the perovskite thick film provided in Example 1 of the present application;

[0149] Figure 5 Exemplarily shown is the ITO / SnO prepared from the perovskite thick film provided in Comparative Example 1 of the present application 2 /

[0150] FA 0.5 MA 0.5 PbI 3X-ray response degree result diagram of the ITO / SnO

[0151] Figure 6 Exemplarily shown is the ITO / SnO prepared from the perovskite thick film provided in Example 1 of the present application 2 /

[0152] FA 0.5 MA 0.5 PbI 3 X-ray response degree result diagram of the ITO / SnO

[0153] Figure 7 Exemplarily shown is the ITO / SnO prepared from the perovskite thick film provided in Example 1 of the present application 2 /

[0154] FA 0.5 MA 0.5 PbI 3 Voltage-current comparison diagram of the ITO / SnO

[0155] 1. Samples after spraying for 3 s in Example 1 and Comparative Example 1 were collected respectively and observed by electron microscopy. The results are as Figure 3 shown; then the perovskite thick film obtained in Example 1 was detected by scanning electron microscopy. The results are as Figure 4 shown.

[0156] 2. Using the perovskite thick films prepared in Example 1 and Comparative Example 1, ITO / SnO 2 /

[0157] FA 0.5 MA 0.5 PbI 3 / Au was used as the device structure to detect its X-ray response degree. The results are as Figure 5 and Figure 6 shown.

[0158] 3. Using the perovskite thick film prepared in Example 1, ITO / SnO 2 / FA 0.5 MA 0.5 PbI 3 / Au was used as the device structure to detect its current-voltage. The results are as Figure 7 shown.

[0159] In summary, a method for preparing a quasi-two-dimensional perovskite thick film provided by an embodiment of the present application adds acetonitrile during the preparation of the quasi-two-dimensional perovskite precursor solution, which can effectively adjust the viscosity, boiling point, and saturated vapor pressure of the quasi-two-dimensional perovskite precursor solution, thereby improving the quality of the perovskite thick film prepared by the spray coating method.

[0160] In addition, a method for preparing a quasi-two-dimensional perovskite thick film provided by an embodiment of the present application uses a lower temperature during the spraying process, so that the overall energy consumption of the method is lower.

[0161] In addition, a method for preparing a quasi-two-dimensional perovskite thick film provided by an embodiment of the present application has higher crystal quality and better electrical properties for the prepared perovskite thick film, and lower dark current for the perovskite thick film obtained by spraying.

[0162] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but will conform to the widest scope consistent with the principles and novel features claimed in the present application.

Claims

1. A method for preparing a quasi-two-dimensional perovskite thick film, the method comprising: DMePDAI2 and FA 0.5 MA 0.5 PbI3 is mixed to obtain a perovskite mixed powder; Dissolving the perovskite mixed powder using N,N-dimethylformamide to obtain a quasi-two-dimensional perovskite precursor crude solution; Stirring the quasi-two-dimensional perovskite precursor crude liquid and acetonitrile to obtain a quasi-two-dimensional perovskite precursor solution; preheating the seed layer to obtain a preheated seed layer; Spraying the quasi-two-dimensional perovskite precursor solution onto the surface of the preheated seed layer multiple times to obtain a thick coarse perovskite film; wherein the spraying temperature is less than 100° C.; The rough perovskite film is annealed to obtain a thick perovskite film.

2. The method according to claim 1, wherein the volume V1 of the N,N-dimethylformamide and the volume V2 of the acetonitrile satisfy: V1:V2=(4-9):

1.

3. The method according to claim 2, wherein the volume V1 of the N,N-dimethylformamide and the volume V2 of the acetonitrile satisfy: V1:V2=9:

1.

4. The method according to claim 1, wherein the amount n1 of DMePDAI2 and the amount n2 of FA 0.5 MA 0.5 The amount of substance n2 of PbI3 satisfies the relationship: n1:n2≥1:

21.

5. The method according to claim 1, wherein the spraying temperature is 85°C to 95°C, and the spraying time is 15 min to 25 min.

6. The method according to claim 1, wherein the spraying amount is 0.5 mL to 1.5 mL, and the interval between two adjacent sprayings is 25 s to 35 s.

7. The method according to claim 1, wherein the preheating temperature is 85°C to 95°C; and / or The annealing temperature is 85° C. to 95° C., and the annealing time is 25 min to 35 min.

8. The method according to claim 1, wherein the preheating of the seed layer to obtain the preheated seed layer comprises: The conductive glass is surface treated to obtain surface treated glass; Performing a first spin coating on the surface of the surface-treated glass using a tin oxide aqueous solution to obtain a functional glass; Mixing biphenyltetracarboxylic acid dianhydride, p-phenylenediamine and n-methylpyrrolidone to obtain a polyimide precursor solution; Mixing methylamine iodine, lead iodide and the polyimide precursor solution to obtain a perovskite seed layer solution; The perovskite seed layer solution is used to perform a second spin coating on the surface of the functional glass to obtain a seed layer.

9. The method according to claim 8, wherein the first spin coating speed is 600 rpm to 2000 rpm, and the first spin coating time is 25 s to 35 s; and / or The rotation speed of the second spin coating is 600 rpm to 2000 rpm, and the time of the second spin coating is 55 s to 65 s.

10. An X-ray detector, comprising a quasi-two-dimensional perovskite thick film prepared by the method according to any one of claims 1 to 9.

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