A method for preparing a perovskite film in two steps by lamination in air

Abstract

The application provides a method for preparing a perovskite film through a two-step method of laminating in air, and belongs to the technical field of perovskite preparation; the method solves the problems of the traditional two-step method of spin coating for preparing a perovskite, such as limitation, poor quality of prepared perovskite film, environmental pollution and poor performance; the method comprises the following steps: first, spin coating a first step lead iodide solution on a first substrate to form a lead iodide film; then, adding a second step MAI solution to the center of a second substrate; contacting one side of the second substrate with the MAI solution with one side of the first substrate with the lead iodide film to form a double-layer substrate; placing the double-layer substrate in air for a period of time, and then performing a reaction between the MAI solution and the lead iodide film through hot pressing in air, so that a perovskite film is formed, and pressure assistance is introduced in the process of hot pressing; annealing the double-layer substrate after hot pressing to form a perovskite; and the application is applied to perovskite preparation.

Description

Technical Field

[0001] This invention provides a two-step lamination method for preparing perovskite thin films in air, belonging to the field of perovskite thin film preparation technology. Background Technology

[0002] Perovskite materials possess excellent optoelectronic properties, and significant progress has been made in optoelectronic devices in recent years. Among these advancements, the quality of the perovskite thin film plays a decisive role in device performance. Pengjun Zhao et al. prepared perovskite thin films using a one-step spin-coating method. Precursor materials were dissolved in a suitable solvent according to stoichiometric ratios and spin-coated in one step to obtain perovskite. This method is simple, but crystal growth is generally uncontrollable and the film is uneven. Yunkang Cui et al. prepared perovskite using a two-step method, first depositing metal halides and then spin-coating organic components to form perovskite. This method offers good controllability, but it results in numerous grain boundary defects, easy water and oxygen intrusion, and poor stability. Zhaolai Chen et al. grew single-crystal perovskite using a space-confined method, achieving high-quality films, but this method was time-consuming. Sheng et al. added 2 vol% water to the perovskite precursor, resulting in larger perovskite grains and a lower defect state density, demonstrating that a certain amount of water is beneficial for perovskite crystallization. Junyan Xiao et al. obtained dense, uniform, high-quality perovskite films through pressure-assisted perovskite growth, promoting carrier transport, reducing defects, suppressing non-radiative recombination, and thus improving device performance.

[0003] The traditional two-step spin-coating method for preparing perovskites still has at least the following drawbacks: (1) The traditional two-step spin coating method for preparing perovskite needs to be carried out in a glove box in order to prevent high humidity from damaging the perovskite, which greatly limits the preparation environment of perovskite; (2) During the traditional spin coating process, a large amount of solution falls off, which is not conducive to environmental protection and is not suitable for large-area preparation, thus limiting further commercial use; (3) Traditional annealing methods cannot control the pressure, resulting in poor quality perovskite films; (4) Perovskite prepared in air contains water of crystallization, thus exhibiting better humidity stability in air. Perovskite prepared by the traditional two-step spin coating method is easily decomposed by water and oxygen intrusion, resulting in a decrease in device performance. Summary of the Invention

[0004] To address the limitations of traditional two-step spin-coating methods for preparing perovskite films, which result in poor quality, environmental unfriendliness, and poor performance of the produced films, this invention proposes a two-step lamination method for preparing perovskite films in air.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for preparing perovskite thin films by two-step lamination in air, comprising the following steps: S1: First, spin-coat the first step lead iodide solution onto the first substrate to form a lead iodide film; S2: Then add the second step MAI solution to the center of the second substrate; S3: Place one side of the second substrate to which the MAI solution was added in step S2 into contact with one side of the first substrate to which the lead iodide film is formed, to form a double-layer substrate; S4: The bilayer substrate is placed in the air for a period of time, and then the MAI solution and lead iodide film are reacted by hot pressing in the air to form a perovskite film, and pressure assistance is introduced during the hot pressing process. S5: Anneal the bilayer substrate after hot pressing in step S4 to form perovskite.

[0006] In step S2, 5-20 μL of the second step MAI solution is specifically added to the center of the second substrate.

[0007] The bilayer substrate formed in step S3 enables the MAI solution from the second step to quickly spread across the entire surface of the first substrate, reacting with the lead iodide film to generate perovskite.

[0008] The perovskite mentioned refers to perovskites of all systems.

[0009] Steps S1, S2, and S3 are all performed in air.

[0010] In step S4, the double-layer substrate is placed in the air for 0-60 minutes.

[0011] The pressure assistance introduced during the hot pressing process in step S4 is in the range of 0-100 kPa.

[0012] The advantages of this invention over the prior art are as follows: 1. Compared with the preparation of perovskite thin films in a traditional glove box, the preparation of perovskite in the air reduces environmental restrictions and is simpler to operate; 2. Compared with the traditional two-step spin coating method, the lamination method eliminates solution waste, improves material utilization, reduces costs, and reduces environmental burden; 3. Compared with the traditional two-step spin coating method, the lamination method has no limitation on the preparation area of ​​perovskite and is compatible with large-area preparation processes; 4. Compared with the traditional perovskite annealing process, pressure conditions are introduced to regulate the crystallization kinetics of perovskite, which can obtain high-quality perovskite films with higher crystallinity and larger grain size. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a flowchart of the two-step lamination process for preparing perovskite thin films in air according to the present invention; Figure 2 The image shows a comparison of XRD patterns of perovskite formed by lamination under different pressure conditions in air and perovskite formed by the traditional two-step method, using MAPbI3 perovskite as an example. Figure 3 The images are scanning electron microscope images of MAPbI3 perovskite films generated under 0 kPa conditions using spin coating in a glove box, spin coating in air, and lamination in air, respectively. Figure 4 SEM images of MAPbI3 perovskites prepared by the lamination method of this invention under different pressure conditions. Detailed Implementation

[0014] Figure 1 This is a schematic diagram of the two-step air lamination method for preparing perovskite thin films proposed in this invention. First, a lead iodide film is spin-coated. Then, a solution is laminated in air to react with the lead iodide film, followed by hot-pressing and annealing to form perovskite. Specific steps include: 1. Spin-coat the first step of lead iodide solution onto a 2cm × 2cm substrate. Then, drop 5-20 μL of the second step MAI solution onto the center of another substrate in the air. Place the two parts facing each other. Due to surface tension and the gravity of the top substrate, the second step solution quickly spreads across the entire surface and reacts with the first step film to form perovskite. The perovskite is perovskite of all systems. The traditional two-step method is spin-coating in a nitrogen-filled glove box, which is environmentally restrictive. Furthermore, a large amount of ink detaches during spin-coating, which is not environmentally friendly, and it is only suitable for small-area batch production. The lamination method, however, leaves no residual solution and is compatible with large-area processes. As the area increases, the amount of the second step solution added increases. 2. The opposing double-layer substrates are placed in air for a fixed time, from 0 to 60 minutes. Moisture in the air has a positive effect on perovskite growth. The opposing encapsulation structure limits the intrusion of moisture from the air, thus positively impacting perovskite growth. Traditional spin coating methods, fabricated in a glove box with a nitrogen atmosphere, completely isolate moisture and fail to utilize its positive effects. 3. The opposing encapsulation structures are hot-pressed to form a high-quality perovskite film, replacing the traditional spin-coating hot-stage annealing method. Pressure assistance is introduced, with the pressure assistance range being 0-100 kPa. This not only helps the second-step solution to fully contact and react with the first-step lead iodide film, but also restricts the longitudinal growth of the perovskite, which is conducive to the formation of dense perovskite. Furthermore, because pressure can regulate the crystallization kinetics of perovskite, high-quality perovskite films can be obtained by controlling the pressure.

[0015] The present invention proposes a two-step air lamination method for preparing perovskite, which involves drop-coating the second-step solution onto the center of a substrate and laminating it opposite the first-step film. Under the action of surface tension and the gravity of the top substrate, perovskite is formed. The crystallization process of perovskite is controlled by adjusting the pressure, thereby preparing a high-quality perovskite film.

[0016] Example 1 A two-step air lamination method for preparing perovskite thin films, the specific steps of which are as follows: 1. Spin-coat the first step lead iodide solution onto one substrate. Then, drop 10 μL of the second step MAI solution into the center of another substrate in the air. Place the two parts facing each other. Due to surface tension and the gravity of the top substrate, the second step solution will quickly spread over the entire surface and react with the first step lead iodide film.

[0017] 2. Placing the opposing double-layer substrates in the air for 10 minutes, the water in the air has a positive effect on the perovskite. The opposing encapsulation structure has a certain limitation on the intrusion of moisture in the air, which has a positive effect on the growth of perovskite.

[0018] 3. The opposing encapsulation structures are hot-pressed to form a high-quality perovskite film, replacing the traditional spin coating method with hot-stage annealing. Pressure assistance is introduced, with a pressure of 10 kPa.

[0019] Example 2 A two-step air lamination method for preparing perovskite thin films, the specific steps of which are as follows: 1. Spin-coat the first step lead iodide solution onto one substrate. Then, drop 15 μL of the second step MAI solution into the center of another substrate in the air. Place the two parts facing each other. Due to surface tension and the gravity of the top substrate, the second step solution quickly spreads across the entire surface and reacts with the first step lead iodide film.

[0020] 2. Placing the opposing double-layer substrates in the air for 20 minutes, the water in the air has a positive effect on the perovskite. The opposing encapsulation structure has a certain limitation on the intrusion of moisture in the air, which has a positive effect on the growth of perovskite.

[0021] 3. The opposing encapsulation structures are hot-pressed to form a high-quality perovskite film, replacing the traditional spin coating hot stage annealing method. Pressure assistance is introduced, with a pressure of 30 kPa.

[0022] Example 3 A two-step air lamination method for preparing perovskite thin films, the specific steps of which are as follows: 1. Spin-coat the first step lead iodide solution onto one substrate. Then, drop 20 μL of the second step MAI solution into the center of another substrate in the air. Place the two parts facing each other. Due to surface tension and the gravity of the top substrate, the second step solution quickly spreads across the entire surface and reacts with the first step lead iodide film.

[0023] 2. Placing the opposing double-layer substrates in the air for 30 minutes, the water in the air has a positive effect on the perovskite. The opposing encapsulation structure has a certain limitation on the intrusion of moisture in the air, which has a positive effect on the growth of perovskite.

[0024] 3. The opposing encapsulation structures are hot-pressed to form a high-quality perovskite film, replacing the traditional spin coating hot stage annealing method. Pressure assistance is introduced, with a pressure of 50 kPa.

[0025] Example 4 A two-step air lamination method for preparing perovskite thin films, the specific steps of which are as follows: 1. Spin-coat the first step lead iodide solution onto one substrate. Then, drop 10 μL of the second step MAI solution into the center of another substrate in the air. Place the two parts facing each other. Due to surface tension and the gravity of the top substrate, the second step solution will quickly spread over the entire surface and react with the first step lead iodide film.

[0026] 2. Placing the opposing double-layer substrates in the air for 5 minutes, the water in the air has a positive effect on the perovskite. The opposing encapsulation structure has a certain limitation on the intrusion of moisture in the air, which has a positive effect on the growth of perovskite.

[0027] 3. The opposing encapsulation structures are hot-pressed to form a high-quality perovskite film, replacing the traditional spin coating hot stage annealing method. Pressure assistance is introduced, with a pressure of 70 kPa.

[0028] Example 5 A two-step air lamination method for preparing perovskite thin films, the specific steps of which are as follows: 1. Spin-coat the first step lead iodide solution onto one substrate. Then, drop 15 μL of the second step MAI solution into the center of another substrate in the air. Place the two parts facing each other. Due to surface tension and the gravity of the top substrate, the second step solution quickly spreads across the entire surface and reacts with the first step lead iodide film.

[0029] 2. Placing the opposing double-layer substrates in the air for 20 minutes, the water in the air has a positive effect on the perovskite. The opposing encapsulation structure has a certain limitation on the intrusion of moisture in the air, which has a positive effect on the growth of perovskite.

[0030] 3. The opposing encapsulation structures are hot-pressed to form a high-quality perovskite film, replacing the traditional spin coating method with hot-stage annealing. Pressure assistance is introduced, with a pressure of 0 kPa.

[0031] Figure 2 A comparison of XRD patterns of perovskite formed by lamination under different pressure conditions in air with that formed by the traditional two-step method shows that the peak intensity is significantly enhanced, indicating improved crystallinity of the perovskite. The peak intensity is highest at 10 kPa, followed by 30 kPa, 50 kPa, and 70 kPa.

[0032] Figure 2 A comparison of XRD patterns of perovskite formed by lamination under different pressure conditions in air with that formed by the traditional two-step method shows that the peak intensity is significantly enhanced, indicating improved crystallinity of the perovskite. The peak intensity is highest at 10 kPa, followed by 30 kPa, 50 kPa, and 70 kPa.

[0033] Figure 3 The images shown are, in order, scanning electron microscope images of perovskite films generated under 0 kPa conditions by two-step spin coating in a glove box, two-step spin coating in air, and two-step lamination in air. It can be seen that compared with direct spin coating in air, the perovskite grain size generated by two-step lamination in air is significantly increased and the defects are significantly reduced.

[0034] Figure 4 SEM images of perovskites laminated under different pressure conditions show that, consistent with XRD, the grain size is largest at 10 kPa, followed by 30 kPa, 50 kPa, and 70 kPa.

[0035] Regarding the specific structure of this invention, it should be noted that the connection relationships between the various component modules used in this invention are definite and achievable. Except as specifically described in the embodiments, their specific connection relationships can bring about corresponding technical effects and solve the technical problems proposed by this invention without relying on the execution of corresponding software programs. The models of the components, modules, and specific components appearing in this invention, the connection methods between them, and the conventional usage methods and expected technical effects brought about by the above technical features, unless specifically described, are all publicly disclosed content in patents, journal articles, technical manuals, technical dictionaries, and textbooks that can be obtained by those skilled in the art before the application date, or belong to conventional technology, common knowledge, and other existing technologies in this field. There is no need to elaborate, which makes the technical solution provided in this case clear, complete, and achievable, and can reproduce or obtain corresponding physical products based on this technical means.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing perovskite thin films by two-step lamination in air, characterized in that: Includes the following steps: S1: First, spin-coat the first step lead iodide solution onto the first substrate to form a lead iodide film; S2: Then add the second step MAI solution to the center of the second substrate; S3: Place one side of the second substrate to which the MAI solution was added in step S2 into contact with one side of the first substrate to which the lead iodide film is formed, to form a double-layer substrate; Steps S1, S2, and S3 are all performed in the air; S4: The bilayer substrate is placed in the air for a period of time, and then the MAI solution and lead iodide film are reacted by hot pressing in the air to form a perovskite film, and pressure assistance is introduced during the hot pressing process. The perovskite film is formed under the action of surface tension and the gravity of the top substrate, and the crystallization process of the perovskite is controlled by controlling the pressure. S5: Anneal the bilayer substrate after hot pressing in step S4 to form perovskite.

2. The method for preparing perovskite thin films by two-step lamination in air according to claim 1, characterized in that: In step S2, 5-20 μL of the second step MAI solution is specifically added to the center of the second substrate.

3. The method for preparing perovskite thin films by two-step lamination in air according to claim 1, characterized in that: The bilayer substrate formed in step S3 enables the MAI solution from the second step to quickly spread across the entire surface of the first substrate, reacting with the lead iodide film to generate perovskite.

4. The method for preparing perovskite thin films by two-step lamination in air according to claim 3, characterized in that: The perovskite mentioned refers to perovskites of all systems.

5. The method for preparing perovskite thin films by two-step lamination in air according to claim 1, characterized in that: In step S4, the double-layer substrate is placed in the air for 0-60 minutes.

6. The method for preparing perovskite thin films by two-step lamination in air according to claim 1, characterized in that: The pressure assistance introduced during the hot pressing process in step S4 is in the range of 0-100 kPa.

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