Use of additive, formamidinium iodide and preparation method therefor, perovskite solar cell, solar power generation device, and electric device

Abstract

The present application discloses a use of an additive, formamidinium iodide and a preparation method therefor, a perovskite solar cell, a solar power generation device, and an electric device. The additive comprises a reducing agent. By incorporating the reducing agent in the additive and using the additive to prepare formamidinium iodide, generation of elemental iodine in the preparation process of formamidinium iodide can be reduced; in addition, iodine which has been oxidized to elemental iodine can be reduced to iodine anions so as to generate formamidinium iodide. The stability of formamidinium iodide is improved, and thus the stability and efficiency of perovskite cells are improved.

Description

Application of additives, formamidine iodide and preparation method thereof, perovskite solar cell, solar power generation device and power-using device

[0001] Citation of Related Applications

[0002] This application claims priority to the Chinese patent application filed with the Patent Office of China on July 4, 2023, with application number 202310812876.5 and invention name “Additives and their applications, formamidine iodide and its preparation method, perovskite solar cells, solar power generation devices and power-using devices”, the entire contents of which are incorporated by reference into the application. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to the application of additives, formamidine iodide and its preparation method, perovskite solar cells, solar power generation devices and power-consuming devices. Background Art

[0004] Formamidine iodide is a key raw material for perovskite solar cells. Due to the development of perovskite solar cells, demand for formamidine iodide is expected to continue to increase. However, current production processes often result in iodine precipitation and surface yellowing in mass-produced finished formamidine iodide, which deepens in color with extended storage. The iodine precipitated from formamidine iodide can act as a carrier recombination center during the subsequent preparation of formamidine iodide perovskite thin films, thereby reducing the stability and efficiency of perovskite cells.

[0005] Summary of the Invention

[0006] The present application is made in view of the above-mentioned problems. The present application provides an application of an additive in the preparation of potassium iodide amidine, which reduces the precipitation of iodine during the preparation of formamidine iodide, thereby improving the stability and efficiency of perovskite batteries.

[0007] In order to achieve the above-mentioned objectives, the embodiments of the present application provide an application of an additive, formamidine iodide and a preparation method thereof, a perovskite solar cell, a solar power generation device and an electrical device.

[0008] In a first aspect, an embodiment of the present application proposes the use of an additive in the preparation of formamidine iodide, wherein the additive includes a reducing agent.

[0009] 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, the iodine that has been oxidized to elemental iodine can be reduced to iodide anions for generating formamidine iodide, thereby improving the stability of formamidine iodide and thus improving the stability and efficiency of the perovskite battery.

[0010] 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 the compounds of N, O, S and P elements is used to prepare formamidine iodide, it is possible to reduce the generation of iodine in the process of preparing formamidine iodide, and at the same time, iodine that has been oxidized to iodine can be reduced to iodide anions for generating formamidine iodide, improving the stability of formamidine iodide, and when the prepared formamidine iodide is applied to a perovskite battery, in the perovskite precursor solution, in the presence of a reducing agent containing at least one of the compounds of N, O, S and P elements, the reducing agent will complex with iodide, causing the solvent to leave quickly, allowing perovskite to achieve rapid nucleation and slow crystallization, thereby improving the stability and efficiency of the perovskite battery. When a reducing agent containing at least one of the compounds of N, O, S and P elements is not present, iodide will complex with the DMSO in the solvent, causing the high perovskite crystallization rate to become faster, which is not conducive to the volatilization of nucleation and solvent.

[0011] 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. Using at least one of the above-mentioned reducing agents can further reduce the precipitation of iodine in the process of preparing formamidine iodide, increase the rate of perovskite nucleation, slow down the crystallization rate of perovskite, increase the volatilization rate 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.

[0012] In a second aspect, the present invention provides a method for preparing formamidine iodide using the additive of the first aspect of the present invention. In some embodiments of the method for preparing formamidine iodide of the present invention, the use of the additive is not limited to a specific step and can be performed by pre-treating the raw materials with the additive or by adding the additive during the reaction to reduce the formation of elemental iodine.

[0013] In any embodiment, the method for preparing formamidine iodide comprises the following steps:

[0014] Mixing hydroiodic acid and an additive, cooling and storing, to obtain a hydroiodic acid pretreatment solution;

[0015] The formamidine acetate solution is mixed with the hydroiodic acid pretreatment solution, crystallized, washed and dried to obtain formamidine iodide.

[0016] By adding additive in hydroiodic acid, cooling preservation, obtain hydroiodic acid pretreatment liquid, in hydroiodic acid, add reducing agent, reducing agent can react with the iodine elemental substance in hydroiodic acid first, make iodine elemental substance be reduced to hydroiodic acid, reducing agent is oxidized, makes the content of iodine elemental substance in hydroiodic acid pretreatment liquid reduce.React with hydroiodic acid pretreatment liquid and formamidine acetate, the main product of reaction is formamidine iodide, thus reduces the iodine elemental substance content in formamidine iodide.In addition, cooling preservation can further reduce the generation of iodine elemental substance.

[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 additive accounts for 0.1% to 10% by weight of the hydroiodic acid pretreatment solution. Within this range, the additive can enhance the inhibitory effect on elemental iodine, provide a reducing agent to react with elemental iodine, and reduce the reaction between the reducing agent and formamidine acetate, thereby reducing side reaction products and impurities. When the prepared formamidine iodide is used in the preparation of perovskite batteries, it is beneficial to the stability and cycle performance of the perovskite battery and reduces costs. Optionally, the additive accounts for 0.5% to 5% by weight of the hydroiodic acid pretreatment solution.

[0019] In any embodiment, the step is to mix hydroiodic acid with an additive, cool and store, to obtain a hydroiodic acid pretreatment solution,

[0020] The cooling storage temperature is 0-10°C, which can reduce ice formation, facilitate the reaction between the reducing agent and the iodine element, and reduce the precipitation of the iodine element; optionally, the cooling storage temperature is 0-5°C; and / or,

[0021] The cooling storage time is 24 to 72 hours, which can improve the reaction efficiency of the reducing agent and the iodine element and improve the production efficiency. Optionally, the cooling storage time is 36 to 60 hours.

[0022] In any embodiment, the molar ratio of formamidine acetate to hydroiodic acid is 1:(0.9-1.2). A suitable molar ratio can ensure sufficient reaction while reducing residual reaction raw materials. Optionally, the molar ratio of formamidine acetate solution to hydroiodic acid is 1:(1.05-1.1).

[0023] 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 are performed.

[0024] The mixing temperature is 0-35° C., at which the yield of formamidine iodide can be increased while reducing ice formation; optionally, the mixing temperature is 0-5° C.; and / or,

[0025] The mixing time is 2 to 8 hours, during which time, the hydroiodic acid and the formamidine acetate can react fully, thereby increasing the yield of formamidine iodide, making the reaction more complete, and reducing the impact on production efficiency; optionally, the mixing time is 3 to 5 hours; and / or,

[0026] The crystallization temperature is 0-35° C., which can increase the crystallization rate of formamidine iodide and reduce ice formation; optionally, the crystallization temperature is 0-10° C.; and / or,

[0027] 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 formation of elemental iodine. Optionally, the drying pressure is -0.8 to -1 bar; and / or,

[0028] The drying temperature is 40-80°C, which is conducive to the volatilization of the solvent and reduces the risk of burns during the preparation process; optionally, the drying temperature is 60-70°C; and / or,

[0029] The drying time is 6 to 15 hours, which can reduce the amount of residual solvent and improve production efficiency; optionally, the drying time is 8 to 12 hours.

[0030] 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:

[0031] Mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution to obtain a mixed solution;

[0032] The mixed solution was evaporated to remove the solvent to obtain a crude formamidine iodide extract;

[0033] The crude formamidine iodide extract is mixed with a solvent, heated, recrystallized, washed, and dried to obtain formamidine iodide.

[0034] By recrystallizing the crude formamidine iodide extract, the impurities in the crude formamidine iodide extract can be further removed, thereby improving 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.

[0035] In any embodiment, the steps are mixing the crude formamidine iodide extract with a solvent, heating, recrystallizing, washing, and drying to obtain formamidine iodide.

[0036] The solvent includes ethanol, which is used as a solvent to facilitate removal and reduce impurities in formamidine iodide; and / or,

[0037] The heating temperature is 30-70° C., which is conducive to the dissolution of formamidine iodide, controls the volatilization rate of ethanol, and is conducive to recrystallization; optionally, the heating temperature is 40-50° C.; and / or,

[0038] The recrystallization temperature is 0-35°C, which can increase the crystallization rate of formamidine iodide and reduce ice formation; optionally, the recrystallization temperature is 0-5°C.

[0039] In a third aspect, the embodiments of the present application provide a formamidine iodide, which is prepared by the preparation method of formamidine iodide according to the second aspect of the present application.

[0040] In a fourth aspect, an embodiment of the present application provides a perovskite solar cell comprising the formamidine iodide of the third aspect of the present application.

[0041] In a fifth aspect, an embodiment of the present application proposes a solar power generation device, including the perovskite solar cell according to the fourth aspect of the present application.

[0042] In a sixth aspect, an embodiment of the present application proposes an electrical device, including the solar power generation device of the fifth aspect of the present application. DETAILED DESCRIPTION

[0043] The following specifically discloses the application of the additive, the preparation method of formamidine iodide, the solar power generation device, and the embodiment of the power device of the present application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid unnecessary lengthiness of the following description and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0044] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and 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 special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this 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 all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this 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.

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

[0046] 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.

[0047] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating 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), indicating 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.

[0048] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0049] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: 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).

[0050] Formamidine iodide is a key raw material for perovskite solar cells. Due to the development of perovskite solar cells, demand for formamidine iodide is expected to continue to increase. However, current production processes often result in iodine precipitation and surface yellowing in mass-produced finished formamidine iodide, which deepens in color with extended storage. The iodine precipitated from formamidine iodide can act as a carrier recombination center during the subsequent preparation of formamidine iodide perovskite thin films, thereby reducing the stability and efficiency of perovskite cells.

[0051] 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 require the use of cleaning agents such as ether for cleaning, which significantly reduces the cost of solvent use and thus reduces the synthesis cost of formamidine iodide. However, the above scheme requires high-temperature calcination, which has high requirements for temperature uniformity on the one hand and high temperature on the other hand. There is a risk of burns.

[0052] Surprisingly, by adding a reducing agent during the preparation of formamidine iodide, the iodine content 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 temperatures.

[0053] Based on this, the present application provides an application of an additive, formamidine iodide and a preparation method thereof, a perovskite solar cell, a solar power generation device and an electrical device.

[0054] In a first aspect, an embodiment of the present application proposes the use of an additive in the preparation of formamidine iodide, wherein the additive includes a reducing agent.

[0055] 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, the iodine that has been oxidized to elemental iodine can be reduced to iodide anions for generating formamidine iodide, thereby improving the stability of formamidine iodide and thus improving the stability and efficiency of the perovskite battery.

[0056] 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 the compounds of N, O, S and P elements is used to prepare formamidine iodide, it is possible to reduce the generation of iodine in the process of preparing formamidine iodide, and at the same time, iodine that has been oxidized to iodine can be reduced to iodide anions for generating formamidine iodide, improving the stability of formamidine iodide, and when the prepared formamidine iodide is applied to a perovskite battery, in the perovskite precursor solution, in the presence of a reducing agent containing at least one of the compounds of N, O, S and P elements, the reducing agent will complex with iodide, causing the solvent to leave quickly, allowing perovskite to achieve rapid nucleation and slow crystallization, thereby improving the stability and efficiency of the perovskite battery. When a reducing agent containing at least one of the compounds of N, O, S and P elements is not present, iodide will complex with the DMSO in the solvent, causing the high perovskite crystallization rate to become faster, which is not conducive to the volatilization of nucleation and solvent.

[0057] 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-mentioned reducing agents, the iodine in the preparation of formamidine iodide can be further reduced to increase the rate of perovskite nucleation, slow down the crystallization rate of perovskite, increase the volatilization rate 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 be included at the same time.

[0058] In a second aspect, the present invention provides a method for preparing formamidine iodide using the additive of the first aspect of the present invention. In some embodiments of the method for preparing formamidine iodide of the present invention, the use of the additive is not limited to a specific step and can be performed by pre-treating the raw materials with the additive or by adding the additive during the reaction to reduce the formation of elemental 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 preservation, obtain hydroiodic acid pretreatment liquid, add reducing agent in hydroiodic acid, reducing agent can react with the iodine element in hydroiodic acid first, make iodine element be reduced to hydroiodic acid, reducing agent is oxidized, reduces the content of iodine element in hydroiodic acid pretreatment liquid. Hydroiodic acid pretreatment liquid is reacted with formamidine acetate again, the main product of reaction is formamidine iodide, so as to reduce the iodine element content in formamidine iodide. In addition, cooling preservation can further reduce the generation of iodine element. And if reducing agent is added in the reaction process, then part of reducing agent can react with formamidine acetate, consumes reaction raw materials formamidine acetate, generates side reaction product, on the one hand there will be the reducing agent for reacting with iodine element to reduce, iodine element content becomes high, on the other hand there will be side reaction product and be unfavorable for the stability and the cyclicity of perovskite battery.

[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 weight percentage of the additive in the hydroiodic acid pretreatment solution is 0.1% to 10%. The weight percentage of the additive in the hydroiodic acid pretreatment solution within this range can improve the inhibition effect on elemental iodine, provide a reducing agent to react with elemental iodine, and at the same time reduce the reaction of the reducing agent with formamidine acetate, thereby reducing side reaction products and impurities. When the prepared formamidine iodide is used in the preparation of perovskite batteries, it is more conducive to the stability and cyclicity of the perovskite battery and reduces costs. The weight percentage 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 weight percentage of the additive in the hydroiodic acid pretreatment solution is 0.5% to 5%.

[0065] In any embodiment, the step of mixing hydroiodic acid with an additive and cooling the mixture to obtain a hydroiodic acid pretreatment solution is performed at a temperature of 0 to 10° C., which can reduce ice formation, facilitate the reaction between the reducing agent and elemental iodine, and reduce the precipitation of elemental iodine. The cooling 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 temperature is 0 to 5° C.

[0066] In any embodiment, the step of mixing hydroiodic acid with an additive and cooling and storing to obtain a hydroiodic acid pretreatment solution is performed for 24 to 72 hours, which can improve the reaction efficiency of the reducing agent and the iodine element and improve production efficiency. The cooling and 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 and storage time is 36 to 60 hours.

[0067] In any embodiment, the step of mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, crystallizing, washing, and drying to obtain the formamidine iodide, wherein the amount ratio of the formamidine acetate to the hydroiodic acid substance is 1: (0.9-1.2). The appropriate amount ratio can ensure sufficient reaction while reducing the residual reaction raw materials. The amount ratio of the formamidine acetate to the hydroiodic acid substance 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 amount ratio of the formamidine acetate solution to the hydroiodic acid substance is 1: (1.05-1.1).

[0068] 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, the mixing temperature is 0 to 35°C. At this temperature, the yield of formamidine iodide can be increased while reducing ice formation. 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.

[0069] In any embodiment, the step is to mix the acetic acid formamidine solution with the hydroiodic acid pretreatment liquid, crystallize, wash, and dry to obtain iodine formamidine. The mixing time is 2 to 8 hours. Under this time, hydroiodic acid and acetic acid formamidine can react fully, improve the yield of iodine formamidine, make the reaction more complete, and reduce the impact on production efficiency. 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 the acetic acid formamidine hydroiodic acid can be mixed by using a constant pressure funnel to slowly add the hydroiodic acid pretreatment liquid dropwise to the acetic acid formamidine solution, wait for the hydroiodic acid to be added dropwise, the solution becomes clear and transparent, and then mix for a preset time.

[0070] 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, the crystallization temperature is 0 to 35°C, which can increase the crystallization rate of formamidine iodide and reduce ice formation. 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.

[0071] 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, the drying method includes vacuum drying, wherein the drying pressure is 0 to -1 bar, and vacuum drying can reduce the contact between formamidine iodide and oxygen, thereby reducing the formation of elemental iodine. 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.

[0072] 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, the drying temperature is 40 to 80° C., which is conducive to the volatilization of the solvent and reduces the risk of burns during the preparation process. The drying temperature can 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 to 70° C.

[0073] 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, the drying time is 6 to 15 hours, and the drying time is less than 6 hours, which can reduce the residual solvent and improve production efficiency. 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.

[0074] 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:

[0075] Mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution to obtain a mixed solution;

[0076] The mixed solution was evaporated to remove the solvent to obtain a crude formamidine iodide extract;

[0077] The crude formamidine iodide extract is mixed with a solvent, heated, recrystallized, washed, and dried to obtain formamidine iodide.

[0078] By recrystallizing the crude formamidine iodide extract, the impurities in the crude formamidine iodide extract can be further removed, thereby improving 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.

[0079] 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 solid of iodoformamidine. The washing process can be performed multiple times using icy ethanol as a detergent.

[0080] In any embodiment, the steps of mixing the crude formamidine iodide extract with a solvent, heating, recrystallizing, washing, and drying to obtain formamidine iodide include ethanol. Ethanol is used as a solvent to facilitate removal and reduce impurities in the formamidine iodide.

[0081] In any embodiment, the steps of mixing the crude formamidine iodide extract with a solvent, heating, recrystallizing, washing, and drying to obtain formamidine iodide, wherein the heating temperature is 30 to 70° C., which is conducive to the dissolution of formamidine iodide, and controlling the volatilization rate of ethanol is 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 to 50° C.

[0082] In any embodiment, the step of mixing the crude formamidine iodide extract with a solvent, heating, recrystallizing, washing, and drying to obtain formamidine iodide, wherein the recrystallization temperature is 0 to 35°C, which can increase the crystallization rate of formamidine iodide and reduce ice formation. 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.

[0083] In a third aspect, the embodiments of the present application provide a formamidine iodide, which is prepared by the preparation method of formamidine iodide according to the second aspect of the present application.

[0084] Whether a reducing agent was 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 relatively small. The anion content can be detected by ion chromatography to improve the anion detection limit.

[0085] In a fourth aspect, an embodiment of the present application provides a perovskite solar cell comprising the formamidine iodide of the third aspect of the present application.

[0086] 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.

[0087] It should be noted that formamidine iodide can be used as FA x A' 1-xThe BX3 complex exists in the perovskite layer, wherein A' is a monovalent inorganic cation or an organic ammonium cation or a mixture of the two, which can be at least one of methylammonium ion (MA) and Cs; B is a divalent inorganic metal cation, which can be Pb 2+ 、Sn 2+ At least one of; X is a halogen element or a halogen-like element, which can be Cl - Br - , I - 、SCN - 、CNO - 、OCN - 、OSCN - 、CP - 、CN - 、SeCN - 、N3 - 、NO2 - At least one of ; 0<x≤1. Exemplary FAPbI3. After the perovskite layer is dissolved in water, FA x A' 1-x The BX3 complex decomposes to release water-soluble potassium iodide amidine, thereby verifying the presence of formamidine iodide in the perovskite solar cell. Testing the anion content in formamidine iodide can be used to determine whether a reducing agent was added during its preparation. It should be noted that due to recrystallization during the preparation process, the residual anion content is low. Ion chromatography can be used to detect anion content, improving the anion detection limit.

[0088] In a fifth aspect, an embodiment of the present application proposes a solar power generation device, including the perovskite solar cell according to the fourth aspect of the present application.

[0089] In some embodiments, a 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.

[0090] 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.

[0091] In a sixth aspect, an embodiment of the present application proposes an electrical device, including the solar power generation device of the fifth aspect of the present application.

[0092] 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.

[0093] The technical solutions of the present invention are 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.

[0094] Example 1

[0095] A method for preparing formamidine iodide comprises the following steps:

[0096] Mix hydroiodic acid and formamidine acetate solution in a 1:1 molar ratio at 4°C for 4 hours, add the reducing agent hypophosphorous acid in an amount of 0.5% of the total mass of hydroiodic acid and hypophosphorous acid, heat at 45°C, crystallize at 4°C, wash three times with icy ethanol, and dry under vacuum at -0.9 bar at 65°C for 12 hours to obtain formamidine iodide.

[0097] Example 2

[0098] A method for preparing formamidine iodide comprises the following steps:

[0099] Mixing hydroiodic acid and hypophosphorous acid, and storing at 4° C. for 48 hours to obtain a hydroiodic acid pretreatment solution, wherein the mass proportion of hypophosphorous acid in the hydroiodic acid pretreatment solution is 0.5%;

[0100] The formamidine acetate solution and the hydroiodic acid pretreatment solution were mixed at 4°C for 4 hours, heated at 45°C, crystallized at 4°C, washed with icy ethanol three times, and dried under -0.9 bar vacuum at 65°C for 12 hours to obtain formamidine iodide.

[0101] The molar ratio of hydroiodic acid to formamidine acetate is 1:1.

[0102] Example 3

[0103] A method for preparing formamidine iodide comprises the following steps:

[0104] Mixing hydroiodic acid and hypophosphorous acid, and storing at 4° C. for 48 hours to obtain a hydroiodic acid pretreatment solution, wherein the mass proportion of hypophosphorous acid in the hydroiodic acid pretreatment solution is 0.5%;

[0105] The formamidine acetate solution and the hydroiodic acid pretreatment solution were mixed at 4° C. for 4 h, with the molar ratio of hydroiodic acid to formamidine acetate being 1:1, to obtain a mixed solution;

[0106] The mixed solution is evaporated at room temperature to remove the solvent to obtain a crude formamidine iodide extract;

[0107] The crude extract of formamidine iodide was mixed with ethanol, heated at 45°C, recrystallized at 4°C, washed with icy ethanol three times, and dried under -0.9 bar vacuum at 65°C for 12 h to obtain formamidine iodide.

[0108] Example 4

[0109] A method for preparing formamidine iodide comprises the following steps:

[0110] Mixing hydroiodic acid and hypophosphorous acid, cooling and storing at 4° C. for 48 hours to obtain a hydroiodic acid pretreatment solution, wherein the mass proportion of hypophosphorous acid in the hydroiodic acid pretreatment solution is 0.5%;

[0111] The formamidine acetate solution and the hydroiodic acid pretreatment solution were mixed at 4° C. for 4 h to obtain a mixed solution, wherein the molar ratio of hydroiodic acid to formamidine acetate was 1:1;

[0112] The mixed solution was rotary evaporated to remove the solvent to obtain a crude formamidine iodide extract;

[0113] The crude extract of formamidine iodide was mixed with ethanol, heated at 45°C, recrystallized at 4°C, washed with icy ethanol three times, and dried under -0.9 bar vacuum at 65°C for 12 h to obtain formamidine iodide.

[0114] Some parameters of Examples 5 to 23 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.

[0115] Table 1 Additive parameters of Examples 5 to 23 and Comparative Examples 1 to 2

[0116] Performance Testing

[0117] 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 perovskite solar cells, and stability performance tests were 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.

[0118] The preparation process of perovskite solar cells is as follows:

[0119] Conductive glass

[0120] Conductive glass with a fluorine-doped tin oxide (FTO, 40 nm thick) thin film was purchased commercially and used directly after cleaning.

[0121]

Hole transport layer and passivation layer

[0122] Irradiate the cleaned conductive glass under a UV ozone generator for 10 minutes. Weigh 50 mg of nickel nitrate hexahydrate and dissolve it in 1 mL of methanol. Take the supernatant and spin-coat it onto the conductive glass. Then, anneal it according to the following procedure: maintain the temperature at 80°C for 10 minutes, increase the temperature to 345°C over 30 minutes, maintain it at 345°C for 30 minutes, and then cool it to 100°C before removing it to obtain a hole transport layer (30 nm thick).

[0123] Passivation layer: Prepare a 10 mg / mL potassium chloride aqueous solution, spin-coat it on the hole transport layer, and anneal at 100° C. for 10 min to obtain a passivation layer (5 nm thick).

[0124] Perovskite layer

[0125] Prepare the perovskite solution: dissolve 650 mg of iodomethane (FAI), 1800 mg of lead iodide (PbI2), and 50 mg of chloromethylamine (MACl) in 1 mL of solvent, wherein the solvent is a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), wherein the volume ratio of DMF to DMSO is 4:1 (DMF:DMSO), and take the supernatant for use (iodomethane (FAI) was synthesized independently, lead iodide (PbI2) and chloromethylamine (MACl) were purchased from Xi'an Baolait Materials Co., Ltd., and DMF and DMSO were purchased from Sigma).

[0126] Then, 60 μL of the supernatant of the perovskite solution was added dropwise onto the passivation layer, and the layer was spun for 30 seconds using a spinner, and then annealed at 150° C. for 1 hour to obtain a perovskite layer with a thickness of 500 nm.

[0127] Electron transport layer and buffer layer

[0128] Prepare [6,6]-phenyl-C61-butyric acid methyl ester (PCBM, commercially available) solution at a concentration of 20 mg / ml in chlorobenzene.

[0129] Prepare a bathocuproin (BCP, commercially available) solution at a concentration of 0.5 mg / mL in isopropanol.

[0130] 60 μL of the prepared PCBM solution was spin-coated onto the conductive glass with the perovskite layer for 30 seconds. The sample was then annealed at 100°C for 10 minutes, removed from the instrument, and cooled to room temperature to form the electron transport layer. Next, 60 μL of the BCP solution was spin-coated onto the electron transport layer for 30 seconds. This resulted in an electron transport layer (70 nm thick) and a buffer layer (3 nm thick).

[0131]

Metal electrode

[0132] 80nm of silver was evaporated in a vacuum evaporation device at a rate of 0.1A / s. After the evaporation was completed, a complete perovskite solar cell was obtained.

[0133] The photoelectric conversion efficiency of the cell was tested under standard simulated sunlight (spectrum: AM 1.5G, irradiance: 100mW / cm2); the photoelectric conversion efficiency of the device was tested after 1000 hours of illumination; the photoelectric conversion efficiency (PCE) of the perovskite solar cell was tested after 1000 hours of use under the conditions of relative humidity of 50±10% RH and 25°C, and the PCE was calculated using the following formula:

[0134] 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.

[0135] Ion chromatography can be used to analyze the content of impurity anions in formamidine iodide.

[0136] Weigh 1g of sample, add 100g of ultrapure water to dissolve and make up to volume, and perform ion chromatography after injection;

[0137] Ion chromatography eluent system: KOH (14 mM);

[0138] Then, qualitative analysis was performed based on the retention time of the test substance and the standard solution; quantitative analysis was performed based on the standard curve, and the analysis and measurement were performed using a Thermo Fisher Dionex ICS-6000 high pressure ion chromatograph.

[0139] The results of the statistical experiments are shown in Table 1 for Examples 5-23 and Comparative Examples 1-2. The results of Examples 1 to 4 are shown in Table 2.

[0140] Table 2 Performance test results of Examples 1 to 4

[0141] As can be seen from Table 1, by Examples 5 to 23 and Comparative Examples 1 to 2, it can be seen that by including a reducing agent in an additive, for preparing formamidine iodide, the generation of iodine elemental substance in the process of preparing formamidine iodide can be reduced, and the iodine that has been oxidized to iodine elemental substance can be reduced to iodide anion, for generating formamidine iodide, improving the stability of formamidine iodide, so as to improve the stability and efficiency of perovskite battery. Wherein, the light stability and photoelectric conversion efficiency of the high perovskite battery of Example 7-23 are better than those of Example 5-6, and Example 5-6 is better than Comparative Example 1-2. Comparative Example 1 adds the oxidant ammonium persulfate, which not only can not suppress the generation of iodine elemental substance, but also increases the generation of iodine elemental substance, thereby affecting photoelectric conversion efficiency and light stability. Comparative Example 2 does not add any additives, and photoelectric conversion efficiency and light stability are poorer than Examples 5 to 23, and it is easier to generate iodine elemental substance.

[0142] As can be seen from Examples 5 to 17, when a reducing agent containing a compound of at least one of the elements N, O, S, and P is used to prepare formamidine iodide, it can not only reduce the generation of elemental iodine during the preparation of formamidine iodide, but also reduce the iodine that has been oxidized to elemental iodine to iodide anions for generating formamidine iodide, thereby improving the stability of formamidine iodide. Furthermore, when the prepared formamidine iodide is applied to a perovskite cell, in the presence of a reducing agent containing a compound of at least one of the elements N, O, S, and P, the reducing agent will complex with the iodide, causing the solvent to quickly leave, allowing the perovskite to achieve rapid nucleation and slow crystallization, thereby improving the stability and efficiency of the perovskite cell. However, when a reducing agent containing at least one of the elements N, O, S, and P is not present, the iodide will complex with the DMSO in the solvent, causing the high perovskite crystallization rate to become faster, which is not conducive to nucleation and solvent volatilization.

[0143] 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 inhibition effect on elemental iodine can be improved, the reaction of the reducing agent with formamidine acetate can be reduced, the side reaction products and impurities can be reduced, which is beneficial to the photostability and cyclability of the perovskite battery and reduces the cost.

[0144] As can be seen from Table 2, Example 1 is to first mix hydroiodic acid and formamidine acetate solution, and then add the reducing agent. Although it can also suppress the formation of elemental iodine compared with Comparative Examples 1 and 2, the effect is worse than Comparative Examples 1 and 2, but the effect is not as good as Examples 2 to 23. Directly adding the reducing agent to hydroiodic acid can, on the one hand, reduce the formation of elemental iodine, and on the other hand, can also reduce the reaction between the reducing agent and formamidine acetate, thereby reducing side reaction products.

[0145] 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 iodide anions for generating formamidine iodide, thereby improving the stability of formamidine iodide and thus improving the stability and efficiency of the perovskite battery.

[0146] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of the present invention.

Claims

1. An application of an additive in the preparation of formamidine iodide, characterized in that: The additives include a reducing agent.

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

3. The use of the additive as claimed in claim 2 in the preparation of formamidine iodide, 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. A method for preparing formamidine iodide, characterized in that: Use the additive according to any one of claims 1 to 3.

5. The method for preparing formamidine iodide according to claim 4, characterized in that: The following steps are involved: Mixing hydroiodic acid with the 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.

6. The method for preparing formamidine iodide according to claim 5, characterized in that: 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%.

7. The method for preparing formamidine iodide according to any one of claims 5 or 6, characterized in that: 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.

8. The method for preparing formamidine iodide according to any one of claims 5 to 7, characterized in that: In the step of mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, The ratio of the amount of the formamidine acetate to the amount of the hydroiodic acid substance is 1:(0.9-1.2); optionally, the ratio of the amount of the formamidine acetate to the amount of the hydroiodic acid substance is 1:(1.05-1.1).

9. The method for preparing formamidine iodide according to any one of claims 5 to 8, characterized in that: In the step of mixing the formamidine acetate solution with the hydroiodic acid pretreatment solution, 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 0-35°C; optionally, the crystallization temperature is 0-10°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 40-80°C; optionally, the drying temperature is 60-70°C; and / or, The drying time is 6 to 15 hours; optionally, the drying time is 8 to 12 hours.

10. The method for preparing formamidine iodide according to any one of claims 5 to 9, 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.

11. The method for preparing formamidine iodide according to claim 10, characterized in that: 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.

12. A formamidine iodide, characterized in that: The method is prepared by the method for preparing formamidine iodide according to any one of claims 4 to 11.

13. A perovskite solar cell, characterized in that: Comprising the formamidine iodide as described in claim 12.

14. A solar power generation device, characterized in that: Comprising the perovskite solar cell as claimed in claim 13.

15. An electrical device, characterized in that: Comprising the solar power generation device as claimed in claim 14.

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