Additive and application thereof, formamidine iodide and preparation method thereof, perovskite solar cell, solar power generation device and power utilization device

Abstract

The invention discloses an additive and application thereof, formamidine iodide and a preparation method thereof, a perovskite solar cell, a solar power generation device and a power utilization device. The additive comprises a reducing agent. According to the present invention, the reducing agent is contained in the additive, and is used for preparing the formamidine iodide, such that the generation of the iodine simple substance during the formamidine iodide preparation process can be reduced, the iodine oxidized into the iodine simple substance can be reduced into the iodine negative ion so as to be used for generating the formamidine iodide, and the stability of the formamidine iodide can be improved so as to improve the stability and the efficiency of the perovskite cell.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and specifically to additives and applications thereof, formamidine iodide and a preparation method thereof, perovskite solar cells, solar power generation devices and power-using devices. Background Art

[0002] Formamidine iodide is one of the important raw materials for perovskite solar cells. Due to the development of perovskite solar cells, the demand for formamidine iodide will continue to increase. In the current preparation process, the finished formamidine iodide products prepared in large quantities have the problem of iodine precipitation and yellowing on the surface, and the color deepens with the extension of storage time. The iodine precipitated from formamidine iodide will become the recombination center of carriers in the subsequent preparation process of formamidine iodide perovskite film, thereby reducing the stability and efficiency of perovskite cells. Summary of the invention

[0003] The present application is made in view of the above-mentioned problems, and its purpose is to provide an additive for preparing formamidine iodide, reducing the precipitation of iodine during the preparation process of formamidine iodide, thereby improving the stability and efficiency of perovskite batteries.

[0004] In order to achieve the above-mentioned objectives, the embodiments of the present application provide an additive and application thereof, formamidine iodide and a preparation method thereof, a perovskite solar cell, a solar power generation device and an electrical device.

[0005] In a first aspect, an embodiment of the present application provides an additive for preparing formamidine iodide, wherein the additive includes a reducing agent.

[0006] Therefore, in the technical solution of the embodiment of the present application, by including a reducing agent in the additive for preparing formamidine iodide, the generation of elemental iodine in the process of preparing formamidine iodide can be reduced. At the same time, iodine that has been oxidized to elemental iodine can be reduced to iodine anions for generating formamidine iodide, thereby improving the stability of formamidine iodide and thus improving the stability and efficiency of the perovskite battery.

[0007] In any embodiment, the reducing agent includes a compound containing at least one of N, O, S and P elements. When a reducing agent containing at least one of N, O, S and P elements is used to prepare formamidine iodide, the generation of iodine in the process of preparing formamidine iodide can be reduced, and the iodine that has been oxidized to iodine can be reduced to iodine anions, which are used to generate formamidine iodide, improve the stability of formamidine iodide, and can be used in the prepared formamidine iodide for perovskite cells. In the presence of a reducing agent containing at least one of N, O, S and P elements, the reducing agent will be complexed with iodide, so that the solvent leaves quickly, so that the perovskite reaches rapid nucleation and slow crystallization, thereby improving the stability and efficiency of the perovskite cell. When the reducing agent does not contain at least one of N, O, S and P elements, the iodide will be complexed with DMSO in the solvent, so that the high perovskite crystallization rate becomes faster, which is not conducive to nucleation and solvent volatilization.

[0008] In any embodiment, the reducing agent includes at least one of hypophosphorous acid, red phosphorus, sulfurous acid, L-ascorbic acid, sodium thiosulfate, sodium hypophosphite, oxalic acid, hydrosulfuric acid and formamidine sulfinic acid. By using at least one of the above reducing agents, the precipitation of iodine in the process of preparing formamidine iodide can be further reduced, the rate of perovskite nucleation can be increased, the crystallization rate of perovskite can be slowed down, the volatility of the solvent can be increased, and the stability and efficiency of the perovskite battery can be improved. In some embodiments of the present application, the reducing agent can include only one of hypophosphorous acid, red phosphorus, sulfurous acid, L-ascorbic acid, sodium thiosulfate, sodium hypophosphite, oxalic acid, hydrosulfuric acid and formamidine sulfinic acid. In other embodiments of the present application, two or more of them can also be included at the same time.

[0009] In the second aspect, the examples of the present application propose the use of the additive of the first aspect of the present application in the preparation of formamidine iodide.

[0010] In the third aspect, the embodiments of the present application provide a method for preparing formamidine iodide, using the additive of the first aspect of the present application. In some embodiments of the method for preparing formamidine iodide of the present application, the use of additives does not limit specific steps, and the additives can be used for pretreatment of the raw materials or for adding additives during the reaction to reduce the generation of iodine.

[0011] In any embodiment, the method for preparing formamidine iodide comprises the following steps:

[0012] Mixing hydroiodic acid and an additive, cooling and storing, to obtain a hydroiodic acid pretreatment solution;

[0013] The formamidine acetate solution is mixed with the hydroiodic acid pretreatment solution, crystallized, washed and dried to obtain formamidine iodide.

[0014] By adding additives in hydroiodic acid, cooling and preserving, hydroiodic acid pretreatment liquid is obtained, and a reducing agent is added to hydroiodic acid, and the reducing agent will react with the iodine in hydroiodic acid first, so that the iodine is reduced to hydroiodic acid, and the reducing agent is oxidized, so that the content of iodine in the hydroiodic acid pretreatment liquid is reduced. Hydroiodic acid pretreatment liquid is then reacted with formamidine acetate, and the main product of the reaction is formamidine iodide, so as to reduce the iodine content in formamidine iodide. In addition, cooling and preserving can further reduce the generation of iodine. And if a reducing agent is added during the reaction, part of the reducing agent will react with formamidine acetate, and the reaction raw material formamidine acetate is consumed to generate side reaction products, and on the one hand, there will be a reduction in the reducing agent reacting with the iodine, and the iodine content becomes high, and on the other hand, it will be unfavorable for the stability and cyclicity of the perovskite battery because of the presence of side reaction products.

[0015] In any embodiment, the step is to mix hydroiodic acid with an additive, cool and store, to obtain a hydroiodic acid pretreatment solution,

[0016] The mass proportion of the additive in the hydroiodic acid pretreatment solution is 0.1% to 10%. When the mass proportion of the additive in the hydroiodic acid pretreatment solution is less than 0.1%, the inhibitory effect on the iodine element is insufficient, and there is not enough reducing agent to react with the iodine element. When the mass proportion of the additive in the hydroiodic acid pretreatment solution is greater than 10%, the reducing agent is too much, and the excess reducing agent will react with formamidine acetate to produce side reaction products and excessive impurities, which is not conducive to the stability and cyclability of the perovskite battery, and also increases the cost. Optionally, the mass proportion of the additive in the hydroiodic acid pretreatment solution is 0.5% to 5%.

[0017] In any embodiment, the step is to mix hydroiodic acid with an additive, cool and store, to obtain a hydroiodic acid pretreatment solution,

[0018] The cooling temperature is 0 to 10°C. When the cooling temperature is lower than 0°C, ice will form, which is not conducive to the reaction between the reducing agent and the iodine element. When the cooling temperature is higher than 10°C, the reaction temperature is too high, and the iodine element is more likely to be formed, requiring more reducing agent to react with the iodine element. Optionally, the cooling temperature is 0 to 5°C; and / or,

[0019] The cooling storage time is 24 to 72 hours. If the cooling storage time is less than 24 hours, the reducing agent and the iodine element will not react completely and the iodine element cannot be fully removed. If the cooling storage time is more than 72 hours, the production efficiency will be affected. Optionally, the cooling storage time is 36 to 60 hours.

[0020] In any embodiment, the steps are mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing, and drying to obtain formamidine iodide.

[0021] The molar ratio of formamidine acetate to hydroiodic acid is 1:(0.9-1.2). A suitable molar ratio can ensure sufficient reaction. If the proportion of formamidine acetate is too large, the reaction will be insufficient, making it difficult to remove the residual formamidine acetate. If the proportion of hydroiodic acid is too large, the post-processing will be complicated and the processing cost will be increased. Optionally, the molar ratio of formamidine acetate solution to hydroiodic acid is 1:(1.05-1.1).

[0022] In any embodiment, the steps are mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing, and drying to obtain formamidine iodide.

[0023] The mixing temperature is 0 to 35° C. At this temperature, the yield of formamidine iodide can be improved. If the temperature is lower than 0° C., the solution will freeze, which is not conducive to the reaction. If the temperature is higher than 35° C., the reaction rate is too fast and the reaction temperature is too high, which is not conducive to the formation of formamidine iodide. Optionally, the mixing temperature is 0 to 5° C.; and / or,

[0024] The mixing time is 2 to 8 hours. Under this time, hydroiodic acid and formamidine acetate can react fully to improve the yield of formamidine iodide. If the mixing time is less than 2 hours, the reaction is not sufficient. If the mixing time is more than 8 hours, the production efficiency is affected. Optionally, the mixing time is 3 to 5 hours; and / or,

[0025] The crystallization temperature is 0-35°C. If the temperature is lower than 0°C, ice will form, affecting the crystallization of formamidine iodide. If the temperature is higher than 35°C, the crystallization rate of formamidine iodide will be too slow. Optionally, the crystallization temperature is 0-10°C; and / or,

[0026] The drying method includes vacuum drying, wherein the drying pressure is 0 to -1 bar. Vacuum drying can reduce the contact between formamidine iodide and oxygen, thereby reducing the generation of elemental iodine. When the pressure is greater than 0 bar, the oxygen content is high, which is not conducive to reducing the generation of elemental iodine. When the pressure is less than -1 bar, the preparation cost will be increased. Optionally, the drying pressure is -0.8 to -1 bar; and / or,

[0027] The drying temperature is 40-80°C. A temperature below 40°C is not conducive to the volatilization of the solvent, and a temperature above 80°C may easily cause the risk of burns during the preparation process. Optionally, the drying temperature is 60-70°C; and / or,

[0028] The drying time is 6 to 15 hours. If the drying time is less than 6 hours, the residual solvent will increase, and if the drying time is more than 15 hours, the production efficiency will be affected. Optionally, the drying time is 8 to 12 hours.

[0029] In any embodiment, the steps of mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing, and drying to obtain formamidine iodide include:

[0030] Mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution to obtain a mixed solution;

[0031] The mixed solution is evaporated to remove the solvent to obtain a crude formamidine iodide extract;

[0032] The crude formamidine iodide extract is mixed with a solvent, heated, recrystallized, washed, and dried to obtain formamidine iodide.

[0033] By recrystallizing the crude formamidine iodide extract, the impurities in the crude formamidine iodide extract can be further removed to improve the purity of the formamidine iodide. In some embodiments of the present application, the recrystallization can be a single recrystallization or multiple recrystallizations according to different requirements.

[0034] In any embodiment, the steps are mixing the crude formamidine iodide extract with a solvent, heating, recrystallizing, washing, and drying to obtain formamidine iodide.

[0035] The solvent includes ethanol, which is used as a solvent to facilitate removal and reduce impurities in formamidine iodide; and / or,

[0036] The heating temperature is 30-70°C, which is conducive to the dissolution of formamidine iodide. The dissolution rate of formamidine iodide in the solvent is too slow when the temperature is lower than 30°C. The ethanol evaporates too quickly when the temperature is higher than 70°C, which is not conducive to recrystallization. Optionally, the heating temperature is 40-50°C; and / or,

[0037] The temperature of recrystallization is 0-35°C. If the temperature is lower than 0°C, ice will form, affecting the crystallization of formamidine iodide. If the temperature is higher than 35°C, the crystallization rate of formamidine iodide will be too slow. Optionally, the temperature of recrystallization is 0-5°C.

[0038] In a fourth aspect, an embodiment of the present application provides a formamidine iodide, which is prepared by the preparation method of formamidine iodide of the third aspect of the present application.

[0039] In a fifth aspect, an embodiment of the present application proposes a perovskite solar cell, comprising the formamidine iodide of the fourth aspect of the present application.

[0040] In a sixth aspect, an embodiment of the present application proposes a solar power generation device, including the perovskite solar cell of the fifth aspect of the present application.

[0041] In a seventh aspect, an embodiment of the present application proposes an electrical device, including the solar power generation device of the sixth aspect of the present application. DETAILED DESCRIPTION

[0042] The following specifically discloses the implementation methods of the additive, the preparation method of the additive, the solar power generation device, and the power-consuming device of the present application. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present application and is not intended to limit the subject matter described in the claims.

[0043] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0044] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0045] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0046] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0047] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0048] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0049] Formamidine iodide is one of the important raw materials for perovskite solar cells. Due to the development of perovskite solar cells, the demand for formamidine iodide will continue to increase. In the current preparation process, the finished formamidine iodide products prepared in large quantities have the problem of iodine precipitation and yellowing on the surface, and the color deepens with the extension of storage time. The iodine precipitated from formamidine iodide will become the recombination center of carriers in the subsequent preparation process of formamidine iodide perovskite film, thereby reducing the stability and efficiency of perovskite cells.

[0050] Therefore, there are endless studies on the removal of iodine. For example, a kind of formamidine iodide and its preparation method, formamidine acetate is mixed with hydroiodic acid, and the mixed solution is evaporated to obtain a shaved ice material; the shaved ice material is heated and calcined to obtain formamidine iodide. The above method does not need to be cleaned with cleaning agents such as ether, which significantly reduces the cost of using solvents, thereby reducing the synthesis cost of formamidine iodide. However, the above scheme needs to be calcined at high temperature. On the one hand, the temperature uniformity is required to be high, and on the other hand, high temperature will have a risk of scalding.

[0051] Unexpectedly, by adding a reducing agent during the preparation of formamidine iodide, the iodine in formamidine iodide can be reduced, the stability of formamidine iodide can be improved, thereby improving the stability and efficiency of perovskite batteries, while also avoiding the risk of burns caused by high temperature.

[0052] Based on this, the present application provides an additive and its application, formamidine iodide and its preparation method, a perovskite solar cell, a solar power generation device and an electricity-using device.

[0053] In a first aspect, an embodiment of the present application provides an additive for preparing formamidine iodide, wherein the additive includes a reducing agent.

[0054] Therefore, in the technical solution of the embodiment of the present application, by including a reducing agent in the additive for preparing formamidine iodide, the generation of elemental iodine in the process of preparing formamidine iodide can be reduced. At the same time, iodine that has been oxidized to elemental iodine can be reduced to iodine anions for generating formamidine iodide, thereby improving the stability of formamidine iodide and thus improving the stability and efficiency of the perovskite battery.

[0055] In any embodiment, the reducing agent includes a compound containing at least one of N, O, S and P elements. When a reducing agent containing at least one of N, O, S and P elements is used to prepare formamidine iodide, the generation of iodine in the process of preparing formamidine iodide can be reduced, and the iodine that has been oxidized to iodine can be reduced to iodine anions, which are used to generate formamidine iodide, improve the stability of formamidine iodide, and can be used in the prepared formamidine iodide for perovskite cells. In the presence of a reducing agent containing at least one of N, O, S and P elements, the reducing agent will be complexed with iodide, so that the solvent leaves quickly, so that the perovskite reaches rapid nucleation and slow crystallization, thereby improving the stability and efficiency of the perovskite cell. When the reducing agent does not contain at least one of N, O, S and P elements, the iodide will be complexed with DMSO in the solvent, so that the high perovskite crystallization rate becomes faster, which is not conducive to nucleation and solvent volatilization.

[0056] In any embodiment, the reducing agent includes at least one of hypophosphorous acid, red phosphorus, sulfurous acid, L-ascorbic acid, sodium thiosulfate, sodium hypophosphite, oxalic acid, hydrosulfuric acid and formamidine sulfinic acid. By using at least one of the above reducing agents, the iodine in the process of preparing formamidine iodide can be further reduced to increase the rate of perovskite nucleation, slow down the crystallization rate of perovskite, increase the volatility of the solvent, and thus improve the stability and efficiency of the perovskite battery. In some embodiments of the present application, the reducing agent may include only one of hypophosphorous acid, red phosphorus, sulfurous acid, L-ascorbic acid, sodium thiosulfate, sodium hypophosphite, oxalic acid, hydrosulfuric acid and formamidine sulfinic acid. In other embodiments of the present application, two or more of them may also be included at the same time.

[0057] In the second aspect, the examples of the present application propose the use of the additive of the first aspect of the present application in the preparation of formamidine iodide.

[0058] In the third aspect, the embodiments of the present application provide a method for preparing formamidine iodide, using the additive of the first aspect of the present application. In some embodiments of the method for preparing formamidine iodide of the present application, the use of additives does not limit specific steps, and the additives can be used for pretreatment of the raw materials or for adding additives during the reaction to reduce the generation of iodine.

[0059] In any embodiment, the method for preparing formamidine iodide comprises the following steps:

[0060] Mixing hydroiodic acid and an additive, cooling and storing, to obtain a hydroiodic acid pretreatment solution;

[0061] The formamidine acetate solution is mixed with the hydroiodic acid pretreatment solution, crystallized, washed and dried to obtain formamidine iodide.

[0062] By adding additives in hydroiodic acid, cooling and preserving, hydroiodic acid pretreatment liquid is obtained, and a reducing agent is added to hydroiodic acid, and the reducing agent will react with the iodine in hydroiodic acid first, so that the iodine is reduced to hydroiodic acid, and the reducing agent is oxidized, and the content of the iodine in the hydroiodic acid pretreatment liquid is reduced. Hydroiodic acid pretreatment liquid is then reacted with formamidine acetate, and the main product of the reaction is formamidine iodide, so as to reduce the iodine content in formamidine iodide. In addition, cooling and preserving can further reduce the generation of iodine. And if a reducing agent is added during the reaction, part of the reducing agent will react with formamidine acetate, and the reaction raw material formamidine acetate is consumed to generate side reaction products, and on the one hand, there will be a reduction in the reducing agent reacting with the iodine, and the iodine content becomes high, and on the other hand, there will be side reaction products that are unfavorable for the stability and cyclicity of perovskite batteries.

[0063] In any embodiment, the step is to mix hydroiodic acid with an additive, cool and store, to obtain a hydroiodic acid pretreatment solution,

[0064] The mass proportion of the additive in the hydroiodic acid pretreatment solution is 0.1% to 10%. When the mass proportion of the additive in the hydroiodic acid pretreatment solution is less than 0.1%, the inhibitory effect on the iodine element is insufficient, and there is not enough reducing agent to react with the iodine element. When the mass proportion of the additive in the hydroiodic acid pretreatment solution is greater than 10%, the reducing agent is too much, and the excess reducing agent will react with the acetic acid formamidine to produce side reaction products, which is not conducive to the stability and cyclicity of the perovskite battery. The mass proportion of the additive in the hydroiodic acid pretreatment solution can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9% or 10%. Optionally, the mass proportion of the additive in the hydroiodic acid pretreatment solution is 0.5% to 5%.

[0065] In any embodiment, the step is to mix hydroiodic acid with an additive, cool and store, to obtain a hydroiodic acid pretreatment solution,

[0066] The cooling and storage temperature is 0 to 10°C. When the cooling temperature is lower than 0°C, ice will form, which is not conducive to the reaction between the reducing agent and the iodine element. When the cooling temperature is higher than 10°C, the reaction temperature is too high, and the iodine element is more likely to be formed, requiring more reducing agent to react with the iodine element. The cooling and storage temperature can be 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C or 10°C; optionally, the cooling and storage temperature is 0 to 5°C; and / or,

[0067] The cooling storage time is 24 to 72 hours. If the cooling storage time is less than 24 hours, the reducing agent and the iodine will not react completely and the iodine will not be fully removed. If the cooling storage time is more than 72 hours, the production efficiency will be affected. The cooling storage time can be 24 hours, 30 hours, 36 hours, 42 hours, 48 ​​hours, 54 hours, 60 hours, 66 hours or 72 hours. Optionally, the cooling storage time is 36 to 60 hours.

[0068] In any embodiment, the steps are mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing, and drying to obtain formamidine iodide.

[0069] The ratio of the amount of formamidine acetate to hydroiodic acid is 1:(0.9-1.2). The appropriate ratio of the amount of the substance can ensure the full reaction. If the proportion of formamidine acetate is too large, the reaction will be insufficient, making it difficult to remove the residual formamidine acetate. If the proportion of hydroiodic acid is too large, the post-processing will be cumbersome and the processing cost will be increased. The ratio of the amount of formamidine acetate to hydroiodic acid can be 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09, 1:1.1, 1:1.15 or 1:1.2. Optionally, the ratio of the amount of formamidine acetate solution to the hydroiodic acid pretreatment liquid is 1:(1.05-1.1).

[0070] In any embodiment, the steps are mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing, and drying to obtain formamidine iodide.

[0071] The mixing temperature is 0 to 35° C. At this temperature, the yield of formamidine iodide can be improved. If the temperature is lower than 0° C., the solution will freeze, which is not conducive to the reaction. If the temperature is higher than 35° C., the reaction rate is too fast and the reaction temperature is too high, which is not conducive to the formation of formamidine iodide. The mixing temperature can be 0° C., 1° C., 2° C., 3° ​​C., 4° C., 5° C., 8° C., 10° C., 15° C., 20° C., 25° C., 30° C. or 35° C.; optionally, the mixing temperature is 0 to 5° C.; and / or,

[0072] The mixing time is 2 to 8 hours. Under this time, hydroiodic acid and formamidine acetate can react fully to increase the yield of formamidine iodide. If the mixing time is less than 2 hours, the reaction is not sufficient. If the mixing time is greater than 8 hours, the production efficiency is affected. The mixing time can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours or 8 hours; optionally, the mixing time is 3 to 5 hours. In some embodiments of the present application, the hydroiodic acid pretreatment liquid and formamidine acetate hydroiodic acid can be mixed by using a constant pressure funnel to slowly add the hydroiodic acid pretreatment liquid to the formamidine acetate solution, wait for the hydroiodic acid to be added, the solution becomes clear and transparent, and then mix for a preset time; and / or,

[0073] The crystallization temperature is 0 to 35°C. When the temperature is lower than 0°C, ice will form, which will affect the crystallization of formamidine iodide. When the temperature is higher than 35°C, the crystallization rate of formamidine iodide will be too slow. The crystallization temperature can be 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 8°C, 10°C, 15°C, 20°C, 25°C, 30°C or 35°C; optionally, the crystallization temperature is 0 to 10°C; and / or,

[0074] The drying method includes vacuum drying, wherein the drying pressure is 0 to -1 bar. Vacuum drying can reduce the contact between formamidine iodide and oxygen, thereby reducing the generation of elemental iodine. When the pressure is greater than 0 bar, the oxygen content is high, which is not conducive to reducing the generation of elemental iodine. When the pressure is less than -1 bar, the preparation cost will be increased. The drying pressure can be 0 bar, -0.1 bar, -0.2 bar, -0.3 bar, -0.4 bar, -0.5 bar, -0.6 bar, -0.7 bar, -0.8 bar, -0.9 bar or -1 bar; optionally, the drying pressure is -0.8 to -1 bar; and / or,

[0075] The drying temperature is 40-80°C. A temperature below 40°C is not conducive to the volatilization of the solvent, and a temperature above 80°C may easily cause the risk of scalding during the preparation process. The drying temperature may be 40°C, 45°C, 50°C, 55°C, 60°C, 62°C, 65°C, 68°C, 70°C, 75°C or 80°C; optionally, the drying temperature is 60-70°C; and / or,

[0076] The drying time is 6 to 15 hours. If the drying time is less than 6 hours, the solvent residue will increase. If the drying time is more than 15 hours, the production efficiency will be affected. The drying time can be 6 hours, 7 hours, 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, 13 hours, 14 hours or 15 hours. Optionally, the drying time is 8 to 12 hours.

[0077] In any embodiment, the steps of mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing, and drying to obtain formamidine iodide include:

[0078] Mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution to obtain a mixed solution;

[0079] The mixed solution is evaporated to remove the solvent to obtain a crude formamidine iodide extract;

[0080] The crude formamidine iodide extract is mixed with a solvent, heated, recrystallized, washed, and dried to obtain formamidine iodide.

[0081] By recrystallizing the crude formamidine iodide extract, the impurities in the crude formamidine iodide extract can be further removed to improve the purity of the formamidine iodide. In some embodiments of the present application, the recrystallization can be a single recrystallization or multiple recrystallizations according to different requirements.

[0082] In some embodiments of the present application, the mixed solution can be evaporated by rotary evaporation to remove the solvent to obtain a white powdery iodoformamidine solid. The washing process can be performed multiple times using icy ethanol as a washing agent.

[0083] In any embodiment, the steps are mixing the crude formamidine iodide extract with a solvent, heating, recrystallizing, washing, and drying to obtain formamidine iodide.

[0084] The solvent includes ethanol, which is used as a solvent to facilitate removal and reduce impurities in formamidine iodide; and / or,

[0085] The heating temperature is 30-70°C, which is conducive to the dissolution of formamidine iodide. The dissolution rate of formamidine iodide in the solvent is too slow when the temperature is lower than 30°C. The ethanol evaporates too quickly when the temperature is higher than 70°C, which is not conducive to recrystallization. The heating temperature can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C; optionally, the heating temperature is 40-50°C; and / or,

[0086] The recrystallization temperature is 0 to 35°C. If the temperature is below 0°C, ice will form, affecting the crystallization of formamidine iodide. If the temperature is above 35°C, the crystallization rate of formamidine iodide will be too slow. The recrystallization temperature can be 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 8°C, 10°C, 15°C, 20°C, 25°C, 30°C or 35°C; optionally, the recrystallization temperature is 0 to 5°C.

[0087] In a fourth aspect, an embodiment of the present application provides a formamidine iodide, which is prepared by the preparation method of formamidine iodide of the third aspect of the present application.

[0088] Whether a reducing agent is added during the preparation of formamidine iodide can be detected by detecting the anion content in formamidine iodide. It should be noted that due to recrystallization during the preparation process, the residual anion content is small. The anion content can be detected by ion chromatography to improve the anion detection limit.

[0089] In a fifth aspect, an embodiment of the present application proposes a perovskite solar cell, comprising the formamidine iodide of the fourth aspect of the present application.

[0090] In some embodiments, the perovskite solar cell may further include a conductive glass layer, an electron transport layer, a perovskite layer, and a hole transport layer, wherein the perovskite layer includes the formamidine iodide of the fourth aspect of the present application.

[0091] It should be noted that formamidine iodide can exist in the perovskite layer in the form of a FAPbI3 complex. After the perovskite layer is dissolved in water, the FAPbI3 complex can decompose potassium iodide amidine soluble in water, thereby verifying that the perovskite solar cell contains formamidine iodide. The anion content in formamidine iodide can be detected to detect whether a reducing agent is added during the preparation of formamidine iodide. It should be noted that due to recrystallization during the preparation process, the residual anion content is small, and the anion content can be detected by ion chromatography to improve the anion detection limit.

[0092] In a sixth aspect, an embodiment of the present application proposes a solar power generation device, including the perovskite solar cell of the fifth aspect of the present application.

[0093] In some embodiments, the solar power generation device may include a mounting bracket, a perovskite solar cell, a secondary battery, and an electric power output unit. The electric energy generated by the perovskite solar cell under sunlight is stored in the secondary battery and outputted for use through the electric power output unit.

[0094] In other embodiments, the solar power generation device may not include a secondary battery and may directly output the electrical energy generated by the perovskite solar cell under sunlight through an electrical power output unit for use.

[0095] In a seventh aspect, an embodiment of the present application proposes an electrical device, including the solar power generation device of the sixth aspect of the present application.

[0096] Electrical devices may include, but are not limited to, solar street lights, solar water heaters, solar charging stations, solar satellite ships, and solar electric vehicles.

[0097] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0098] Example 1

[0099] A method for preparing formamidine iodide comprises the following steps:

[0100] Mix hydroiodic acid and formamidine acetate solution, add a reducing agent, crystallize, wash and dry to obtain formamidine iodide.

[0101] Example 2

[0102] A method for preparing formamidine iodide comprises the following steps:

[0103] Mixing hydroiodic acid and an additive, cooling and storing, to obtain a hydroiodic acid pretreatment solution;

[0104] The formamidine acetate solution is mixed with the hydroiodic acid pretreatment solution, crystallized, washed and dried to obtain formamidine iodide.

[0105] Example 3

[0106] A method for preparing formamidine iodide comprises the following steps:

[0107] Mixing hydroiodic acid and an additive, cooling and storing, to obtain a hydroiodic acid pretreatment solution;

[0108] Mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution to obtain a mixed solution;

[0109] The mixed solution is evaporated to remove the solvent to obtain a crude formamidine iodide extract;

[0110] The crude formamidine iodide extract is mixed with a solvent, heated, recrystallized, washed, and dried to obtain formamidine iodide.

[0111] Example 4

[0112] A method for preparing formamidine iodide comprises the following steps:

[0113] Mixing hydroiodic acid and hypophosphorous acid, cooling and storing at 4° C. for 48 hours, to obtain a hydroiodic acid pretreatment solution, wherein the amount of hypophosphorous acid added to the hydroiodic acid pretreatment solution is 0.5%;

[0114] The formamidine acetate solution and the hydroiodic acid pretreatment solution are mixed at 4° C. for 4 hours to obtain a mixed solution, wherein the molar ratio of hydroiodic acid to formamidine acetate is 1:1;

[0115] The mixed solution was rotary evaporated to remove the solvent to obtain a crude formamidine iodide extract;

[0116] The crude formamidine iodide extract was mixed with a solvent, heated at 45°C, recrystallized at 4°C, washed with ice ethanol three times, and dried under -0.9 bar vacuum at 65°C for 12 hours to obtain formamidine iodide.

[0117] Some parameters of Examples 5 to 17 of the present application and Comparative Examples 1 to 2 are set according to Table 1, and other parameters are the same as those of Example 4.

[0118]

[0119] Performance Testing

[0120] The formamidine iodide prepared by the preparation methods of formamidine iodide in Examples 5 to 23 and Comparative Examples 1 to 2 was prepared into a perovskite solar cell, and a stability performance test was performed. At the same time, the color of the formamidine iodide prepared by the preparation methods of formamidine iodide in Examples 1 to 23 and Comparative Examples 1 to 2 was observed, and the content of impurity anions in the formamidine iodide was detected:

[0121] The photoelectric conversion efficiency of the cell was tested under the standard simulated sunlight emitting a standard sunlight (spectrum of AM 1.5G, irradiance of 100mW / cm2); the photoelectric conversion efficiency of the device after 1000h of illumination was tested; the photoelectric conversion efficiency (PCE) of the perovskite solar cell was tested after 1000h of use under the conditions of relative humidity of 50±10%RH and 25℃, and the PCE was calculated by the following formula:

[0122]

[0123] Where PCE is the photoelectric conversion efficiency, Voc is the open circuit voltage, Jsc is the short circuit current density, FF is the fill factor, and Pin is the input power.

[0124] Ion chromatography can be used to detect the content of impurity anions in formamidine iodide.

[0125] The results of the experiments are summarized in Table 1 for Examples 5-23 and Comparative Examples 1-2. The results of Examples 1 to 4 are shown in Table 2.

[0126] Table 2 Performance test results of Examples 1 to 4

[0127]

[0128] As can be seen from Table 1, it can be seen from Examples 5 to 23 and Comparative Examples 1 to 2 that by including a reducing agent in an additive for preparing formamidine iodide, the generation of iodine in the process of preparing formamidine iodide can be reduced, and iodine that has been oxidized to iodine can be reduced to iodine anions for generating formamidine iodide, improving the stability of formamidine iodide, thereby improving the stability and efficiency of the perovskite battery. Among them, the stability and efficiency of the high perovskite battery of Examples 7-23 are better than those of Examples 5-6, and Examples 5-6 are better than Comparative Examples 1-2. Comparative Example 1 adds an oxidant, ammonium persulfate, which not only fails to suppress the generation of iodine, but also increases the generation of iodine, thereby affecting the photoelectric conversion efficiency and light stability. Comparative Example 2 does not add any additives, and the photoelectric conversion efficiency and light stability are poorer than those of Examples 5 to 23, and it is easier to generate iodine.

[0129] It can be seen from Examples 5 to 17 that when a reducing agent containing at least one of N, O, S and P elements is used to prepare formamidine iodide, the generation of iodine in the process of preparing formamidine iodide can be reduced, and iodine that has been oxidized to iodine can be reduced to iodine anions for generating formamidine iodide, improving the stability of formamidine iodide, and when the prepared formamidine iodide is applied to perovskite cells, in the presence of a reducing agent containing at least one of N, O, S and P elements, the reducing agent will be complexed with iodide, so that the solvent leaves quickly, so that the perovskite reaches rapid nucleation and slow crystallization, thereby improving the stability and efficiency of the perovskite cell. When a reducing agent containing at least one of N, O, S and P elements is not present, the iodide will be complexed with DMSO in the solvent, so that the high perovskite crystallization rate becomes faster, which is not conducive to nucleation and solvent volatilization.

[0130] It can be seen from Examples 7 and 18 to 23 that when the mass proportion of the additive in the hydroiodic acid pretreatment solution is less than 0.1%, the inhibitory effect on the iodine element is insufficient, and there is not enough reducing agent to react with the iodine element. When the mass proportion of the additive in the hydroiodic acid pretreatment solution is greater than 10%, the reducing agent is too much, and the excess reducing agent will react with formamidine acetate to produce side reaction products and excessive impurities, which is not conducive to the stability and cyclability of the perovskite battery, and also increases the cost.

[0131] As can be seen from Table 2, in Example 1, hydroiodic acid and formamidine acetate solution are first mixed, and then a reducing agent is added. Although the generation of elemental iodine can be suppressed compared with Comparative Examples 1 and 2, the effect is worse than that of Comparative Examples 1 and 2, but the effect is not as good as that of Examples 2 to 23. Directly adding a reducing agent to hydroiodic acid can reduce the generation of elemental iodine on the one hand, and on the other hand, can also reduce the reaction between the reducing agent and formamidine acetate, thereby reducing side reaction products.

[0132] In summary, the additive proposed in the present application includes a reducing agent in the additive for preparing formamidine iodide, which can reduce the generation of elemental iodine in the process of preparing formamidine iodide. At the same time, the iodine that has been oxidized to elemental iodine can be reduced to iodine anions for generating formamidine iodide, thereby improving the stability of formamidine iodide and thus improving the stability and efficiency of the perovskite battery.

[0133] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. An additive for preparing formamidine iodide, characterized in that: The additives include a reducing agent.

2. The additive according to claim 1, characterized in that The reducing agent includes a compound containing at least one of N, O, S and P elements.

3. The additive according to claim 2, characterized in that The reducing agent includes at least one of hypophosphorous acid, red phosphorus, sulfurous acid, L-ascorbic acid, sodium thiosulfate, sodium hypophosphite, oxalic acid, hydrosulfuric acid and formamidinesulfinic acid.

4. Use of the additive according to any one of claims 1 to 3 in the preparation of formamidine iodide.

5. A method for preparing formamidine iodide, characterized in that: Use the additive according to any one of claims 1 to 3.

6. The method for preparing formamidine iodide according to claim 5, characterized in that: The following steps are involved: Mixing hydroiodic acid and an additive, cooling and storing, to obtain a hydroiodic acid pretreatment solution; The formamidine acetate solution is mixed with the hydroiodic acid pretreatment solution, crystallized, washed and dried to obtain formamidine iodide.

7. The method for preparing formamidine iodide according to claim 6, characterized in that: The step is to mix hydroiodic acid and an additive, cool and store, and obtain a hydroiodic acid pretreatment solution. The mass proportion of the additive in the hydroiodic acid pretreatment solution is 0.1% to 10%; optionally, the mass proportion of the additive in the hydroiodic acid pretreatment solution is 0.5% to 5%.

8. The method for preparing formamidine iodide according to any one of claims 6 or 7, characterized in that: The step is to mix hydroiodic acid and an additive, cool and store, and obtain a hydroiodic acid pretreatment solution. The temperature of the cooling storage is 0-10°C; optionally, the temperature of the cooling storage is 0-5°C; and / or, The cooling storage time is 24 to 72 hours; optionally, the cooling storage time is 36 to 60 hours.

9. The method for preparing formamidine iodide according to any one of claims 6 to 8, characterized in that: The steps are: mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing, and drying to obtain formamidine iodide. The ratio of the amount of formamidine acetate to the amount of hydroiodic acid is 1:(0.9-1.2); optionally, the ratio of the amount of formamidine acetate solution to the amount of hydroiodic acid is 1:(1.05-1.1).

10. The method for preparing formamidine iodide according to any one of claims 6 to 9, characterized in that: The steps are: mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing, and drying to obtain formamidine iodide. The mixing temperature is 0 to 35°C; optionally, the mixing temperature is 0 to 5°C; and / or, The mixing time is 2 to 8 hours; optionally, the mixing time is 3 to 5 hours; and / or, The crystallization temperature is 0 to 35°C; optionally, the crystallization temperature is 0 to 10°C; and / or, The drying method includes vacuum drying, wherein the drying pressure is 0 to -1 bar; optionally, the drying pressure is -0.8 to -1 bar; and / or, The drying temperature is 40 to 80°C; optionally, the drying temperature is 60 to 70°C; and / or, The drying time is 6 to 15 hours; optionally, the drying time is 8 to 12 hours.

11. The method for preparing formamidine iodide according to any one of claims 6 to 10, characterized in that: The steps of mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing and drying to obtain formamidine iodide include: Mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution to obtain a mixed solution; The mixed solution is evaporated to remove the solvent to obtain a crude formamidine iodide extract; The crude formamidine iodide extract is mixed with a solvent, heated, recrystallized, washed, and dried to obtain formamidine iodide.

12. The method for preparing formamidine iodide according to claim 11, characterized in that: The steps are as follows: mixing the crude formamidine iodide extract with a solvent, heating, recrystallizing, washing, and drying to obtain formamidine iodide. The solvent comprises ethanol; and / or, The heating temperature is 30-70°C; optionally, the heating temperature is 40-50°C; and / or, The recrystallization temperature is 0-35°C; optionally, the recrystallization temperature is 0-5°C.

13. A formamidine iodide, characterized in that The method is prepared by the method for preparing formamidine iodide according to any one of claims 5 to 12.

14. A perovskite solar cell, characterized in that: Comprising the formamidine iodide as described in claim 13.

15. A solar power generation device, characterized in that: Comprising the perovskite solar cell as claimed in claim 14.

16. An electrical device, characterized in that: Comprising the solar power generation device as claimed in claim 15.

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