Perovskite precursor solution, method for preparing perovskite thin film at low temperature and perovskite solar cell

Abstract

The invention relates to a perovskite precursor solution, a method for preparing a perovskite thin film at low temperature and a perovskite solar cell, the perovskite precursor solution comprises a solution A and a solution B, the solution A comprises formamidine iodide, the solution B comprises lead iodide, and the preservation temperature of the solution A is 0-20 DEG C. Therefore, adverse chemical reactions among perovskite components are inhibited by adopting a method of reducing the temperature of the precursor solution, the crystallization quality of the perovskite thin film is improved, the usable time of the precursor solution is prolonged, the operation window is widened, and meanwhile, the waste of the solution is reduced. According to the low-temperature preparation method adopted by the invention, the open-circuit voltage, the short-circuit current and the filling factor of the carbon-based perovskite solar cell are improved, so that the perovskite solar cell with higher photoelectric conversion efficiency and better stability is obtained. The precursor solution stored at low temperature for a long time can still be used for preparing batteries, does not show obvious performance reduction, and is more suitable for industrial large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a perovskite precursor solution, a method for preparing a perovskite film at low temperature, and a perovskite solar cell. Background Art

[0002] In recent years, perovskite solar cells (PSCs) have made rapid progress in the photovoltaic field due to their excellent photoelectric performance and scalable preparation methods. The perovskite structure used in photovoltaic devices is ABX3, where A is a monovalent cation such as FA + ,MA + and Cs + , B-position divalent metal cations, such as Pb 2+ , Sn 2+ , X is a halogen ion, such as I - , Br - , Cl - The outstanding photovoltaic performance of PSCs is primarily attributed to the unique physical and chemical properties of metal halide perovskite materials. Currently, PSCs have achieved certified photoelectric conversion efficiencies exceeding 26% (hereafter referred to as efficiency). Reducing costs and improving stability are the main development directions for PSCs in the future.

[0003] Currently, the industry uses a two-step process to prepare perovskite thin films. The first step involves depositing an inorganic precursor film. Inorganic salts such as lead iodide (PbI2) or lead bromide (PbBr2) are dissolved in a polar solvent (such as DMF or DMSO) and then deposited by spin coating, doctor blade coating, or vapor deposition to form a uniform inorganic layer. The second step involves introducing and reacting the organic component. An organic ammonium salt solution such as methylamine iodide (MAI) or formamidine iodide (FAI) is impregnated or spin-coated onto the inorganic layer, whereupon the perovskite is formed via a solid-liquid or vapor-solid reaction. While this two-step process offers excellent reproducibility, the precursor solution is susceptible to chemical reactions during storage, adversely affecting the performance of perovskite solar cells. The large number of defect states in perovskite films is a major limitation to performance improvement. Furthermore, the precursor solution easily expires after storage, resulting in a waste of raw materials. Therefore, most two-step perovskite preparation processes require the precursor solution to be prepared freshly for immediate use. This cumbersome preparation process cannot meet the needs of future large-scale production. Prior art CN117881251A discloses a method for processing a perovskite precursor solution and its application, which points out that the perovskite precursor solution is not suitable for high-temperature environments, whether it is dissolved or stored. However, according to the document, placing the precursor solution under freezing conditions will also increase storage costs.

[0004] In summary, the current shortcomings of the two-step method for preparing perovskite solar cells include the following aspects: (1) The perovskite film prepared by the two-step method has a large number of defects, which seriously affect the efficiency and stability of the cell; (2) The stability of the precursor solution is poor, which limits the operating window of cell preparation. Summary of the Invention

[0005] Based on this, it is necessary to provide a perovskite precursor solution, a method for preparing perovskite thin films at low temperature, and a perovskite solar cell that can improve the open circuit voltage and fill factor of carbon-based perovskite solar cells, improve the photoelectric efficiency of the cells, have a relatively convenient production process, and have a relatively low storage cost.

[0006] In a first aspect, the present application provides a perovskite precursor solution, comprising liquid A and liquid B, wherein the liquid A comprises formamidine iodide, and the liquid B comprises lead iodide, wherein the storage temperature of the liquid A is 0 degrees Celsius to 20 degrees Celsius.

[0007] In one embodiment, the solution B comprises the following components: lead iodide, cesium chloride, dimethylformamide and dimethyl sulfoxide;

[0008] And / or, the solution A comprises the following components: formamidine iodide, methylammonium chloride and isopropyl alcohol;

[0009] And / or, the storage temperature of liquid A is 8-12 degrees Celsius.

[0010] In one embodiment, the mass volume ratio of lead iodide, cesium chloride, dimethylformamide and dimethyl sulfoxide in the solution B is 691 mg:12.5 mg:900 μl:100 μl;

[0011] and / or, in the solution A, the mass volume ratio of formamidine iodide, methylammonium chloride and isopropyl alcohol is 180 mg:180 mg:2 ml;

[0012] And / or, the storage temperature of liquid A is 10 degrees Celsius.

[0013] In a second aspect, the present application provides a method for preparing a perovskite film at a low temperature, wherein the perovskite precursor solution as described in any of the above embodiments is used to prepare the perovskite film on the electron transport layer. Preferably, the perovskite film is prepared by a two-step method, wherein liquid B is used to form a lead-based framework layer on the electron transport layer, and liquid A is used to convert the lead-based framework layer into a perovskite film. Of course, it should be understood that the two-step method should not be regarded as a limitation of the present application. The perovskite precursor solution provided in the present application can also be used to prepare the perovskite film by other methods in the industry that do not use the two-step method.

[0014] In one embodiment, the composition of the perovskite film is FA0.95 Cs 0.05 PbI3.

[0015] In one embodiment, the method comprises the following steps:

[0016] Pre-treating the conductive glass substrate;

[0017] An electron transport layer is formed on a conductive glass substrate using a tin oxide colloidal solution.

[0018] In one embodiment, a tin oxide colloidal solution containing methylenediamine dihydrochloride is used to form an electron transport layer on a conductive glass substrate. For example, the preparation process of the tin oxide colloidal solution containing methylenediamine dihydrochloride is as follows: the tin oxide colloidal solution is diluted to 3% with deionized water, and then methylenediamine dichloride is added at a concentration of 1-3 mg / mL.

[0019] In one embodiment, the conductive glass substrate is FTO conductive glass, and the pretreatment process includes cleaning and ozone treatment steps.

[0020] In one embodiment, after preparing the perovskite film, the following step is further included: scraping commercial carbon paste on the perovskite film to form an electrode.

[0021] In a third aspect, the present application provides a perovskite solar cell having a perovskite film prepared by the method described in any of the above embodiments.

[0022] The above-mentioned perovskite precursor solution provided by the present application includes liquid A and liquid B, wherein the liquid A includes formamidine iodide and the liquid B includes lead iodide, wherein the storage temperature of the liquid A is 0 degrees Celsius to 20 degrees Celsius. When it is applied to the two-step method for preparing a titanium ore film, the unfavorable chemical reaction between the perovskite components is suppressed by lowering the temperature of the precursor solution to 0 degrees Celsius to 20 degrees Celsius, thereby improving the crystallization quality of the perovskite film, prolonging the time that the precursor solution can be used, widening the operating window, and reducing the waste of the solution. The low-temperature preparation method adopted by the present invention improves the open circuit voltage, short-circuit current and fill factor of the carbon-based perovskite solar cell, thereby obtaining a perovskite solar cell with higher photoelectric conversion efficiency and better stability. At the same time, the precursor solution stored for a long time at low temperature can still be used to prepare the battery without showing obvious performance degradation, and is more suitable for industrial large-scale production. Moreover, the present application is stored at a temperature of 0-20 degrees Celsius by a frozen storage method relative to the existing literature, which can significantly reduce the storage cost. The applicant has found that after the perovskite precursor solution is treated at a low temperature of 0-20 degrees Celsius, it can improve the open circuit voltage and fill factor of the carbon-based perovskite solar cell, and ultimately significantly improve the battery efficiency. In particular, the perovskite precursor solution treated at 10°C can produce the most efficient carbon-based perovskite solar cell, with a photoelectric conversion efficiency of up to 18.80%. In addition, the perovskite precursor solution of the present application can be pre-configured, and the A solution can be stored at 0-20 degrees Celsius. There is no need to prepare it immediately, which improves the operational convenience of large-scale production. Moreover, compared with the frozen storage of the prior art, the low-temperature storage of the present application can also reduce the storage cost, which is conducive to reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The voltage-current curves of the photoelectric performance tests of the perovskite films of specific embodiments 1-3 and comparative example 1 of the present invention applied to carbon-based perovskite solar cell devices;

[0024] Figure 2 Schematic diagram of the structure of a perovskite solar cell according to an embodiment;

[0025] Figure 3 FIG. 1 is a flow chart of a method for preparing a perovskite thin film at low temperature according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention and to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, and preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0027] In a first aspect, the present application provides a perovskite precursor solution, comprising liquid A and liquid B, wherein the liquid A comprises formamidine iodide, and the liquid B comprises lead iodide, wherein the storage temperature of the liquid A is 0 degrees Celsius to 20 degrees Celsius.

[0028] The above-mentioned perovskite precursor solution provided by the present application includes liquid A and liquid B, wherein the liquid A includes formamidine iodide, and the liquid B includes lead iodide, wherein the storage temperature of the liquid A is 0 degrees Celsius to 20 degrees Celsius. In this way, the adverse chemical reaction between the perovskite components is suppressed by adopting a method of lowering the temperature of the precursor solution, the crystallization quality of the perovskite film is improved, the time that the precursor solution can be used is extended, the operating window is widened, and the waste of the solution is reduced. The low-temperature preparation method adopted in the present invention improves the open circuit voltage, short-circuit current and fill factor of the carbon-based perovskite solar cell, thereby obtaining a perovskite solar cell with higher photoelectric conversion efficiency and better stability. At the same time, the precursor solution stored for a long time at low temperature can still be used to prepare the battery, without showing obvious performance degradation, and is more suitable for industrial large-scale production. Moreover, the present application is stored at a temperature of 0-20 degrees Celsius by a frozen storage method relative to the existing literature, which can significantly reduce the storage cost. Moreover, the applicant's research found that after the perovskite precursor solution is treated at a low temperature of 0-20 degrees Celsius, it can increase the open circuit voltage and fill factor of carbon-based perovskite solar cells, and ultimately significantly improve the cell efficiency.

[0029] In one embodiment, the B solution includes the following components: lead iodide (PbI2), cesium chloride (CsCl), dimethylformamide (DMF) and dimethyl sulfoxide (DMSO); thus, lead iodide is used as a precursor of optoelectronic materials and a radiation shielding material, and it reacts with an organic salt in a two-step process to form a light-absorbing layer; and by adding cesium chloride, the stability of the perovskite lattice is adjusted, the phase transition is suppressed, and the thermal stability is improved. Dimethylformamide is used to dissolve lead salts and organic halides and optimize the uniformity of the precursor solution. The use of a mixed solvent of dimethyl sulfoxide and dimethylformamide can slow down the crystallization rate, reduce pinhole defects, and improve the density of the perovskite film. For example, in the B solution, the mass volume ratio of lead iodide, cesium chloride, dimethylformamide and dimethyl sulfoxide is 691 mg: 12.5 mg: 900 μl: 100 μl; for another example, the B solution includes the following components in parts by mass or volume: PbI2: 691 mg, CsCl: 12.5 mg, DMF: 900 μl, DMSO: 100 μl.

[0030] In one embodiment, the solution A comprises the following components: formamidine iodide (FAI), methylammonium chloride (MACl) and isopropyl alcohol (IPA); for example, in the solution A, the mass volume ratio of formamidine iodide, methylammonium chloride and isopropyl alcohol is 180 mg:18 mg:2 ml; for example, the solution A comprises the following components by mass or volume: FAI: 180 mg, MACl: 18 mg, IPA: 2 ml, for example, the solution A is stored at a temperature of 8-12 degrees Celsius, preferably, the solution A is stored at a temperature of 10 degrees Celsius. In this way, the use of the solution A of each component and the combination of a lower storage temperature can significantly reduce the temperature of the precursor solution to inhibit adverse chemical reactions between the perovskite components, further improve the crystallization quality of the perovskite film, further extend the time that the precursor solution can be used, broaden the operating window, and reduce solution waste. At the same time, the precursor solution stored for a long time at low temperature can still be used to prepare batteries without showing significant performance degradation, making it more suitable for industrial large-scale production.

[0031] It is particularly important to note that the perovskite precursor solution of the present application can be pre-prepared, and solution A can be stored at 0-20 degrees Celsius, which improves the operational convenience of large-scale production. Moreover, compared with the existing frozen storage method, the low-temperature storage method of the present application can also reduce storage costs, thereby helping to reduce production costs.

[0032] In a second aspect, the present application provides a method for preparing a perovskite film at low temperature, wherein the perovskite precursor solution as described in any of the above embodiments is used to prepare the perovskite film in a two-step process on the electron transport layer, wherein the B solution is used to form a lead-based framework layer on the electron transport layer, and the A solution stored at a low temperature of 0 degrees Celsius to 20 degrees Celsius is used to convert the lead-based framework layer into a perovskite film. For example, the components of the perovskite film are FA 0.95 Cs 0.05 In one specific embodiment, the method comprises the following steps S1 to S3:

[0033] S1: pretreatment of conductive glass substrate;

[0034] For example, the conductive glass substrate is a transparent conductive glass substrate, for example, FTO (fluorine-doped tin oxide) or ITO (indium tin oxide), for example, the conductive glass substrate is FTO conductive glass, and the pretreatment process includes cleaning and ozone treatment steps. For example, the FTO conductive glass is cleaned and ozone treated for 15 minutes.

[0035] S2: forming an electron transport layer on a conductive glass substrate using a tin oxide colloidal solution;

[0036] An electron transport layer is formed on a conductive glass substrate by using a tin oxide colloidal solution; for example, the preparation process of the electron transport layer is as follows: a spin coater is set to 4000 rpm, 50 microliters of the prepared tin oxide colloidal solution is dropped on the FTO, spin coating is started for 30 seconds, and then transferred to a 150°C hot plate for annealing for 30 minutes.

[0037] A preferred embodiment is to form an electron transport layer on a conductive glass substrate using a tin oxide colloidal solution to which methylenediamine dihydrochloride is added; for example, the preparation process of the tin oxide colloidal solution to which methylenediamine dihydrochloride (MDACl2) is added is as follows: the tin oxide colloidal solution is diluted to 3% with deionized water, and then methylenediamine dihydrochloride (MDACl2) is added at a concentration of 1-3 mg / mL. For example, the preparation process of the electron transport layer is as follows: the speed of the sizing machine is set to 4000 rpm, 50 microliters of the prepared tin oxide colloidal solution is dropped on the FTO, the spin coating is started for 30 seconds, and then transferred to a 150°C hot stage for annealing for 30 minutes. Preferably, the tin oxide colloidal solution is added with methylenediamine dihydrochloride (MDACl2) at a concentration of 2 mg / mL. In this way, the applicant has found that the tin oxide electron transport layer doped with MDACl2 can improve the open circuit voltage, short circuit current density and fill factor of the carbon-based perovskite solar cell, and ultimately significantly improve the battery efficiency. Among them, when the MDACl2 doping concentration in tin oxide was 2.0 mg / mL, the carbon-based perovskite solar cell achieved the highest photoelectric conversion efficiency.

[0038] S3: A perovskite thin film is prepared on the electron transport layer using a two-step method using a perovskite precursor solution; wherein the A solution is annealed after the A solution is spun.

[0039] For example, the perovskite component is FA 0.95 Cs 0.05 For PbI3, a perovskite precursor solution is required, which is liquid B (PbI2691mg, CsCl 12.5mg, DMF 900μl, DMSO 100μl) and liquid A (FAI 180mg, MACl 18mg, IPA 2ml). After dissolving liquid A, place it in an environment of 0℃ to 20℃. A two-step method is used to prepare a perovskite film on the above electron transport layer. After spin coating liquid A, anneal at 150℃ for 15 minutes. Figure 3 As shown in FIG, it is a diagram of the low-temperature preparation of perovskite film. First, liquid B is used to form a PbI2 layer on the electron transport layer, and then liquid A is used to react on the PbI2 layer to form an FAI layer. After the reaction, the perovskite film is prepared.

[0040] In one embodiment, after preparing the perovskite film, the following step is further included: applying a commercial carbon slurry on the perovskite film to form an electrode. The commercial carbon slurry is applied to the prepared perovskite film and annealed at 120°C for 10 minutes to complete the battery preparation. It should be noted that the subsequent battery preparation process is referenced to existing technologies and will not be further described in this application.

[0041] In a third aspect, the present application provides a perovskite solar cell having a perovskite film prepared by the method described in any of the above embodiments. Figure 2 As shown, the perovskite solar cell includes a transparent conductive substrate (FTO / ITO), an electron transport layer (ETL), a perovskite layer and a metal electrode / carbon electrode. Among them, the transparent conductive substrate is usually made of FTO or ITO material. The transparent conductive substrate is used as the photoanode substrate, usually using fluorine-doped tin oxide (FTO) or indium-doped tin oxide (ITO) coated glass, whose function is to transmit light and collect current. The electron transport layer (ETL) usually uses tin oxide (SnO2) colloid to form a dense film on the surface of the substrate through a coating process. As a component of the electron transport layer, it promotes the transmission of photogenerated electrons to the conductive substrate and optimizes the interface charge separation efficiency. Of course, it should be noted that Figure 2 The perovskite solar cell shown is only an example. It should be understood that the perovskite solar cell is not limited to the above structure, and may also be other structures known in the art.

[0042] The above-mentioned perovskite precursor solution provided by the present application includes liquid A and liquid B, wherein the liquid A includes formamidine iodide and the liquid B includes lead iodide, wherein the storage temperature of the liquid A is 0 degrees Celsius to 20 degrees Celsius. When it is applied to the two-step method for preparing a titanium ore film, the unfavorable chemical reaction between the perovskite components is suppressed by lowering the temperature of the precursor solution to 0 degrees Celsius to 20 degrees Celsius, thereby improving the crystallization quality of the perovskite film, prolonging the time that the precursor solution can be used, widening the operating window, and reducing the waste of the solution. The low-temperature preparation method adopted by the present invention improves the open circuit voltage, short-circuit current and fill factor of the carbon-based perovskite solar cell, thereby obtaining a perovskite solar cell with higher photoelectric conversion efficiency and better stability. At the same time, the precursor solution stored for a long time at low temperature can still be used to prepare the battery without showing obvious performance degradation, and is more suitable for industrial large-scale production. Moreover, the present application is stored at a temperature of 0-20 degrees Celsius by a frozen storage method relative to the existing literature, which can significantly reduce the storage cost. The applicant has found that after the perovskite precursor solution is treated at a low temperature of 0-20 degrees Celsius, it can improve the open circuit voltage and fill factor of the carbon-based perovskite solar cell, and ultimately significantly improve the battery efficiency. In particular, the perovskite precursor solution treated at 10°C can produce the most efficient carbon-based perovskite solar cell, with a photoelectric conversion efficiency of up to 18.80%. In addition, the perovskite precursor solution of the present application can be pre-configured, and the A solution can be stored at 0-20 degrees Celsius. There is no need to prepare it immediately, which improves the operational convenience of large-scale production. Moreover, compared with the frozen storage of the prior art, the low-temperature storage of the present application can also reduce the storage cost, which is conducive to reducing production costs.

[0043] The present application will be further described below with reference to specific embodiments and comparative examples.

[0044] Example 1

[0045] A specific implementation process for preparing a perovskite film on FTO is provided. The method for preparing the perovskite film includes the following steps:

[0046] 1. Clean the FTO conductive glass and treat it with ozone for 15 minutes.

[0047] 2. Electron Transport Layer Preparation: Dilute the tin oxide colloidal solution to 3% with deionized water, shake well, and filter. Set the spin coater to 4000 rpm. Drop 50 μl of the prepared tin oxide colloidal solution onto the FTO film. Spin coat for 30 seconds, then anneal on a 150°C hotplate for 30 minutes.

[0048] 3. Low temperature treatment of perovskite precursor solution: the perovskite component is FA 0.95 Cs 0.05To prepare PbI3, you need to prepare the perovskite precursor solutions: Solution B (691 mg of PbI2, 12.5 mg of CsCl, 900 μL of DMF, 100 μL of DMSO) and Solution A (180 mg of FAI, 18 mg of MACl, 2 mL of IPA). After dissolving Solution A, place it in a 0°C environment.

[0049] 4. Preparation of perovskite film: A two-step method is used to prepare the perovskite film on the above-mentioned electron transport layer. During the preparation, the A solution needs to be kept at different temperatures. After the spin coating is completed, annealing is performed at 150°C for 15 minutes.

[0050] 5. Apply commercial carbon slurry on the prepared perovskite film and anneal at 120°C for 10 minutes to complete the photovoltaic cell preparation.

[0051] Example 2

[0052] The difference from Example 1 is that after solution A is dissolved, it is placed in an environment at 10°C.

[0053] Example 3

[0054] The difference from Example 1 is that after solution A is dissolved, it is placed in an environment at 20°C.

[0055] Comparative Example 1

[0056] The difference from Example 1 is that after solution A is dissolved, it is placed in an environment at 30°C.

[0057] After the perovskite films prepared in Examples 1 to 3 and Comparative Example 1 were applied to prepare photovoltaic cells, the prepared carbon-based perovskite solar cell devices were tested for photoelectric performance, and the voltage-current curves were obtained as shown in FIG. Figure 1 , the photoelectric conversion efficiency is shown in Table 1.

[0058] Table 1 Test results of various embodiments and comparative examples

[0059]

[0060] According to Table 1 and Figure 1 It can be seen that compared with Comparative Example 1, the low-temperature treatment of the perovskite precursor solution at 0-20 degrees Celsius can improve the open-circuit voltage and fill factor of the carbon-based perovskite solar cell, ultimately significantly improving the cell's photoelectric efficiency. The perovskite precursor solution treated at 10°C can produce the most efficient carbon-based perovskite solar cell.

[0061] This application proposes to control the storage and use temperature of the precursor solution to inhibit adverse reactions occurring in the solution, thereby reducing defects in the perovskite film, extending the operating window of battery preparation, and improving the photovoltaic performance, stability and reproducibility of the device.

[0062] The preparation method of the perovskite solar cell of the present invention is as follows:

[0063] (1) Preparing a SnO2 electron transport layer on FTO or ITO conductive glass; (2) Preserving the prepared precursor solution in a temperature-controlled low-temperature refrigeration box; (3) Preparing a perovskite film on the electron transport layer using the low-temperature precursor solution; (3) Scraping a conductive carbon slurry on the perovskite film. Advantages and positive effects of the present invention: The present invention suppresses adverse chemical reactions between perovskite components by lowering the temperature of the precursor solution, thereby improving the crystallization quality of the perovskite film, extending the time the precursor solution can be used, broadening the operating window, and reducing solution waste. The low-temperature preparation method adopted by the present invention improves the open circuit voltage, short-circuit current, and fill factor of carbon-based perovskite solar cells, thereby obtaining perovskite solar cells with higher efficiency and better stability. At the same time, the precursor solution stored at low temperature for a long time can still be used to prepare batteries without showing obvious performance degradation, and is more suitable for industrial large-scale production.

[0064] The various technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. It should be noted that "in one embodiment", "for example", "for example", etc. in this application are intended to illustrate this application, rather than to limit this application. The above-mentioned embodiments only express several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, several variations and improvements can be made, which all belong to the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the attached claims.

Claims

1. A perovskite precursor solution, characterized in that The method comprises liquid A and liquid B, wherein the liquid A comprises formamidine iodide and the liquid B comprises lead iodide, wherein the storage temperature of the liquid A is 0 degrees Celsius to 20 degrees Celsius.

2. The perovskite precursor solution according to claim 1, characterized in that The B solution includes the following components: lead iodide, cesium chloride, dimethylformamide and dimethyl sulfoxide; And / or, the solution A comprises the following components: formamidine iodide, methylammonium chloride and isopropyl alcohol; And / or, the storage temperature of liquid A is 8-12 degrees Celsius.

3. The perovskite precursor solution according to claim 2, characterized in that In the solution B, the mass volume ratio of lead iodide, cesium chloride, dimethylformamide and dimethyl sulfoxide is 691 mg:12.5 mg:900 μl:100 μl; and / or, in the solution A, the mass volume ratio of formamidine iodide, methylammonium chloride and isopropyl alcohol is 180 mg:180 mg:2 ml; And / or, the storage temperature of liquid A is 10 degrees Celsius.

4. A method for preparing a perovskite thin film at low temperature, characterized in that: A perovskite thin film is prepared on an electron transport layer using the perovskite precursor solution as described in any one of claims 1 to 3.

5. The method according to claim 4, characterized in that A perovskite film is prepared on the electron transport layer using a perovskite precursor solution and a two-step method, wherein solution B is used to form a lead-based framework layer on the electron transport layer, and solution A is used to convert the lead-based framework layer into a perovskite film; And / or, the components of the perovskite film are FA 0.95 Cs 0.05 PbI3.

6. The method according to claim 4, characterized in that The method comprises the following steps: Pre-treating the conductive glass substrate; An electron transport layer is formed on a conductive glass substrate using a tin oxide colloidal solution; A perovskite thin film is prepared on the electron transport layer using a two-step method using a perovskite precursor solution; annealing treatment is performed after the A solution is spun.

7. The method according to claim 6, characterized in that An electron transport layer is formed on a conductive glass substrate using a tin oxide colloidal solution containing methylenediamine dihydrochloride. The preparation process of the tin oxide colloidal solution containing methylenediamine dihydrochloride is as follows: the tin oxide colloidal solution is diluted to 3% with deionized water, and then doped methylenediamine dichloride is added at a concentration of 1-3 mg / mL.

8. The method according to claim 6, characterized in that The conductive glass substrate is FTO conductive glass, and the pretreatment process includes cleaning and ozone treatment steps.

9. The method according to claim 6, characterized in that After the perovskite film is prepared, the following step is further included: coating a commercial carbon paste on the perovskite film to form an electrode.

10. A perovskite solar cell, characterized in that: A perovskite thin film prepared by the method according to any one of claims 4 to 9.

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