Synthesis method of high-purity super-crystal formamidine bromide (FABr)

Abstract

The invention discloses a method for synthesizing high-purity super-crystal formamidine bromide (FABr), which is characterized in that the FABr is synthesized by means of anti-solvent addition and staged cooling, and the method comprises the following steps: (1) feeding for reaction; (2) extracting a crude product; (3) suction filtration and washing; (4) crystallizing and purifying; and (5) vacuum drying, through combination of a neutralization reaction and a recrystallization process, impurities such as metal ions and acetate ions can be effectively removed, the purity of a final product can reach 99.9% or above through verification, the method is short in process route and mild in reaction condition, the total yield can be stabilized to be 85% or above, the whole process is carried out at low temperature and in an inert atmosphere, thermal decomposition and oxidation of FABr are reduced, and the method is suitable for industrial production. The product has excellent thermal stability and storage stability, the FABr crystal obtained through temperature-controlled crystallization is uniform in size, easy to store and used for subsequent preparation of a perovskite precursor solution, used reagents are common, the cost is low, operation steps are simple, and industrial large-scale production is easy to achieve.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic material preparation technology, specifically to a method for synthesizing high-purity supercrystalline formamidinium bromide (FABr). Background Technology

[0002] Formamidinium bromide (FABr) is a key precursor material for preparing the light-absorbing layer of formamidinium-based perovskite (FAPbX3). Its purity, stability, and ion defect concentration directly determine the quality of the final perovskite film and the performance of the optoelectronic device. Currently, the synthesis methods of FABr suffer from problems such as complex processes, low product purity, and easy introduction of metal ions and organic impurities, affecting the efficiency and stability of perovskite solar cells. Therefore, developing a simple, low-cost synthesis method suitable for industrial production and capable of stably obtaining high-purity FABr has significant application value. Summary of the Invention

[0003] The purpose of this invention is to provide a method for synthesizing high-purity supercrystalline formamidine bromide (FABr) to solve the problems of complex process, low product purity, and easy introduction of metal ions and organic impurities in the FABr synthesis methods proposed in the background art, which affect the efficiency and stability of perovskite solar cells.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for synthesizing high-purity supercrystalline formamidinium bromide (FABr), which synthesizes FABr by means of antisolvent addition and staged cooling, comprising the following steps: (1) Feeding reaction: Add formamidine acetate and hydrobromic acid to the reactor at a mass ratio of 1:1.8~2.4, and mechanically stir for 0.5~2h under ice bath conditions to obtain solution A; (2) Crude product extraction: The solution A was transferred to a rotary evaporator through a filter device and the solvent was evaporated at 45℃~60℃ under -0.1MPa to obtain yellow solid B; (3) Filtration and washing: The yellow solid B obtained by evaporation is transferred to a filter and then washed with an antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1~1.5. Impurities are removed by filtration and washing to obtain white solid C. (4) Crystallization and purification: Transfer the white solid C to a culture tank, and then add anhydrous ethanol for recrystallization. The mass ratio of formamidine acetate to ethanol is 1:1.5~3. The temperature is controlled at 75℃~80℃ during the dissolution process. After the white solid C is completely dissolved, add the reducing agent and the antisolvent to the solution. The mass ratio of formamidine acetate to the antisolvent is 1:0.5~1. After complete dissolution and uniform mixing, solution D is obtained. Staged cooling: Transfer solution D to a culture tank and place it in a constant temperature incubator at 40℃~50℃ for 12~48h. Then, lower the temperature of the constant temperature incubator to 15℃~30℃ and keep it for 12~48h. Then, transfer it to a freezer at -10℃~-25℃ for further cooling for 12~24h to obtain mixture E. (5) Vacuum drying: Pour the mixture E into a filter, filter out the solvent, and rinse with the antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1~1.5 to obtain solid F and filtrate G. Transfer solid F to a vacuum oven and dry it under vacuum at -0.1MPa to obtain FABr crystal product. Filtrate G is recovered and reused.

[0005] Preferably, the antisolvent is methyl tert-butyl ether.

[0006] Preferably, the antisolvent is ethyl acetate.

[0007] Preferably, the antisolvent is diethyl ether.

[0008] Preferably, the cooling rate of the different stages of the staged cooling is set to -2℃ / min to -5℃ / min.

[0009] Preferably, the vacuum drying temperature is 50~70℃ and the time is 24~72 hours.

[0010] Compared with the prior art, the beneficial effects of the present invention are: 1. High purity: Through neutralization reaction combined with recrystallization process, impurities such as metal ions and acetate ions can be effectively removed, and the purity of the final product has been verified to reach over 99.9%.

[0011] 2. High yield: This method has a short process route, mild reaction conditions, and the overall yield can be consistently above 85%.

[0012] 3. Good stability: The entire process is carried out at low temperature and inert atmosphere, which reduces the thermal decomposition and oxidation of FABr, and the product has excellent thermal stability and storage stability.

[0013] 4. Good product morphology: The FABr crystals obtained by temperature-controlled crystallization are uniform in size, easy to store and use in the preparation of subsequent perovskite precursor solutions.

[0014] 5. Suitable for large-scale production: The reagents used are common, the cost is low, the operation steps are simple, and it is easy to achieve industrial-scale production. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the synthesis method steps of the present invention; Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: 1. Feeding reaction: Add formamidine acetate and hydrobromic acid to the reactor at a mass ratio of 1:1.8, and mechanically stir for 0.5 h under ice bath conditions to obtain solution A; 2. Crude product extraction: Solution A was transferred to a rotary evaporator via a filtration device, and the solvent was evaporated to dryness at 60°C under -0.1 MPa to obtain a yellow solid B; 3. Filtration and washing: The yellow solid B obtained by evaporation is transferred to a filter and then washed with an antisolvent. The mass ratio of methylammonium acetate to the antisolvent is 1:1. Impurities are removed by filtration and washing to obtain white solid C. 4. Crystallization and purification: Transfer the white solid C to a culture vessel, then add anhydrous ethanol for recrystallization. The mass ratio of formamidine acetate to ethanol is 1:1.5, and the temperature is controlled at 75℃ during the dissolution process. After the white solid C is completely dissolved, add a small amount of reducing agent and antisolvent to the solution. The mass ratio of formamidine acetate to antisolvent is 1:0.5. After complete dissolution and homogenization, solution D is obtained. Staged cooling: Transfer solution D to a culture vessel and place it in a 50℃ constant temperature incubator for 12 h. Then, lower the temperature of the constant temperature incubator to 15℃ and keep it for 12 h. Finally, transfer it to a -10℃ freezer for further cooling for 12 h to obtain mixture E. 5. Vacuum drying: Pour mixture E into a filter, filter out the solvent, and rinse with the antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1 to obtain solid F and filtrate G. Transfer solid F to a vacuum oven and dry it at -0.1 MPa and 50°C for 24 hours to obtain FABr crystal product. Filtrate G is recovered and reused.

[0018] Example 2: 1. Feeding reaction: Add formamidine acetate and hydrobromic acid to the reactor at a mass ratio of 1:2.4, and mechanically stir for 2 hours under ice bath conditions to obtain solution A; 2. Crude product extraction: Solution A was transferred to a rotary evaporator via a filtration device, and the solvent was evaporated to dryness at 60°C under -0.1 MPa to obtain a yellow solid B; 3. Filtration and washing: The yellow solid B obtained by evaporation is transferred to a filter and then washed with an antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1.5. Impurities are removed by filtration and washing to obtain white solid C. 4. Crystallization and purification: Transfer the white solid C to a culture vessel, then add anhydrous ethanol for recrystallization. The mass ratio of formamidine acetate to ethanol is 1:3, and the temperature is controlled at 80℃ during the dissolution process. After the white solid C is completely dissolved, add a small amount of reducing agent and antisolvent to the solution. The mass ratio of formamidine acetate to antisolvent is 1:0.6. After complete dissolution and homogeneous mixing, solution D is obtained. Staged cooling: Transfer solution D to a culture vessel and place it in a 45℃ constant temperature incubator for 12 h. Then, lower the temperature of the constant temperature incubator to 30℃ and store it for 48 h. Finally, transfer it to a -25℃ freezer for further cooling for 24 h to obtain mixture E. 5. Vacuum drying: Pour mixture E into a filter, filter out the solvent, and rinse with the antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1.5 to obtain solid F and filtrate G. Transfer solid F to a vacuum oven and dry it at -0.1 MPa and 70°C for 72 h to obtain FABr crystal product. Filtrate G is recovered and reused.

[0019] Example 3: 1. Feeding reaction: Add formamidine acetate and hydrobromic acid to the reaction vessel at a mass ratio of 1:2, and mechanically stir for 1 hour under ice bath conditions to obtain solution A; 2. Crude product extraction: Solution A was transferred to a rotary evaporator via a filtration device, and the solvent was evaporated to dryness at 50°C under -0.1 MPa to obtain a yellow solid B; 3. Filtration and washing: The yellow solid B obtained by evaporation is transferred to a filter and then washed with an antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1.2. Impurities are removed by filtration and washing to obtain white solid C. 4. Crystallization and purification: Transfer the white solid C to a culture vessel, then add anhydrous ethanol for recrystallization. The mass ratio of formamidine acetate to ethanol is 1:2, and the temperature is controlled at 80℃ during the dissolution process. After the white solid C is completely dissolved, add a small amount of reducing agent and antisolvent to the solution. The mass ratio of formamidine acetate to antisolvent is 1:1. After complete dissolution and homogenization, solution D is obtained. Staged cooling: Transfer solution D to a culture vessel and store it in a 45℃ constant temperature incubator for 24 hours. Then, transfer it to a 20℃ constant temperature incubator for 24 hours, and then transfer it to a -20℃ freezer for further cooling for 18 hours to obtain mixture E. 5. Vacuum drying: Pour mixture E into a filter, filter out the solvent, and rinse with the antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1.2 to obtain solid F and filtrate G. Transfer solid F to a vacuum oven and dry it at -0.1 MPa and 60°C for 48 h to obtain FABr crystal product. Filtrate G is recovered and reused.

[0020] Example 4: 1. Feeding reaction: Add formamidine acetate and hydrobromic acid to the reactor at a mass ratio of 1:2.2, and mechanically stir for 1.5 h under ice bath conditions to obtain solution A; 2. Crude product extraction: Solution A was transferred to a rotary evaporator via a filtration device, and the solvent was evaporated to dryness at 55°C under -0.1 MPa to obtain yellow solid B; 3. Filtration and washing: The yellow solid B obtained by evaporation is transferred to a filter and then washed with an antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1.5. Impurities are removed by filtration and washing to obtain white solid C. 4. Crystallization and purification: Transfer the white solid C to a culture tank, then add anhydrous ethanol for recrystallization. The mass ratio of formamidine acetate to ethanol is 1:2.5, and the temperature is controlled at 75℃ during the dissolution process. After the white solid C is completely dissolved, add a small amount of reducing agent and antisolvent to the solution. The mass ratio of formamidine acetate to antisolvent is 1:0.8. After complete dissolution and homogenization, solution D is obtained. Staged cooling: Transfer solution D to a culture tank and place it in a 50℃ constant temperature incubator for 18 h. Then, lower the temperature of the constant temperature incubator to 25℃ and store it for 48 h. Finally, transfer it to a -15℃ freezer for further cooling for 24 h to obtain mixture E. 5. Vacuum drying: Pour mixture E into a filter, filter out the solvent, and rinse with the antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1.5 to obtain solid F and filtrate G. Transfer solid F to a vacuum oven and dry it at -0.1 MPa and 65°C for 72 h to obtain FABr crystal product. Filtrate G is recovered and reused.

[0021] Example 5: 1. Feeding reaction: Add formamidine acetate and hydrobromic acid to the reactor at a mass ratio of 1:2.4, and mechanically stir for 1.5 h under ice bath conditions to obtain solution A; 2. Crude product extraction: Solution A was transferred to a rotary evaporator via a filtration device, and the solvent was evaporated to dryness at 50°C under -0.1 MPa to obtain a yellow solid B; 3. Filtration and washing: The yellow solid B obtained by evaporation is transferred to a filter and then washed with an antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1.5. Impurities are removed by filtration and washing to obtain white solid C. 4. Crystallization and purification: Transfer the white solid C to a culture vessel, then add anhydrous ethanol for recrystallization. The mass ratio of formamidine acetate to ethanol is 1:2.5, and the temperature is controlled at 80℃ during the dissolution process. After the white solid C is completely dissolved, add a small amount of reducing agent and antisolvent to the solution. The mass ratio of formamidine acetate to antisolvent is 1:0.5. After complete dissolution and homogenization, solution D is obtained. Staged cooling: Transfer solution D to a culture vessel and place it in a 45℃ constant temperature incubator for 18 h. Then, lower the temperature of the constant temperature incubator to 25℃ and store it for 24 h. Finally, transfer it to a -20℃ freezer for further cooling for 24 h to obtain mixture E. 5. Vacuum drying: Pour mixture E into a filter, filter out the solvent, and rinse with the antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1.5 to obtain solid F and filtrate G. Transfer solid F to a vacuum oven and dry it at -0.1 MPa and 70°C for 48 h to obtain FABr crystal product. Filtrate G is recovered and reused.

[0022] The antisolvent is one of methyl tert-butyl ether, ethyl acetate, and diethyl ether. During the recrystallization process, the antisolvent reduces the solubility of FAI in the solvent system, thereby inducing crystal precipitation and improving crystal morphology, particle size distribution, and purity.

[0023] Specific functions include: 1. Reduced solubility: The antisolvent is miscible with the main solvent, but has poor solubility for the target substance. Its addition reduces the overall solubility of the system, causing the solution to become supersaturated, thus promoting crystal nucleation and growth.

[0024] 2. Controlling the crystallization process: By adjusting the addition rate, ratio, and temperature of the antisolvent, the crystallization kinetics can be controlled, avoiding excessive local supersaturation that could lead to impurity encapsulation or crystal agglomeration, thereby improving product purity.

[0025] The cooling rate of the different stages of the staged cooling is set to -2℃ / min to -5℃ / min. During the recrystallization process, the role of staged cooling is to optimize crystal quality, improve product purity, and avoid defects caused by rapid cooling.

[0026] Specific functions include: 1. Controlling crystal growth rate: Staged cooling gradually reduces the temperature, preventing instantaneous supersaturation of the solution and thus reducing the rapid formation of numerous small crystal nuclei. This promotes orderly crystal growth, resulting in larger, more uniform crystal grains and reducing impurity inclusions.

[0027] 2. Improve crystal morphology and purity: If the temperature drops too quickly, fine crystals or dendrites are easily formed, and the increased specific surface area will actually adsorb more impurities; while slow, phased cooling can promote the formation of regular crystals and improve separation efficiency.

[0028] Preferably, the vacuum drying temperature is 50~70℃ and the time is 24~72 hours. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing high-purity supercrystalline formamidinium bromide (FABr), characterized in that: The synthesis of FABr by means of antisolvent addition and staged cooling includes the following steps: (1) Feeding reaction: Add formamidine acetate and hydrobromic acid to the reactor at a mass ratio of 1:1.8~2.4, and mechanically stir for 0.5~2h under ice bath conditions to obtain solution A; (2) Crude product extraction: The solution A was transferred to a rotary evaporator through a filter device and the solvent was evaporated at 45℃~60℃ under -0.1MPa to obtain yellow solid B; (3) Filtration and washing: The yellow solid B obtained by evaporation is transferred to a filter and then washed with an antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1~1.

5. Impurities are removed by filtration and washing to obtain white solid C. (4) Crystallization and purification: Transfer the white solid C to a culture tank, and then add anhydrous ethanol for recrystallization. The mass ratio of formamidine acetate to ethanol is 1:1.5~3. The temperature is controlled at 75℃~80℃ during the dissolution process. After the white solid C is completely dissolved, add the reducing agent and the antisolvent to the solution. The mass ratio of formamidine acetate to the antisolvent is 1:0.5~1. After complete dissolution and uniform mixing, solution D is obtained. Staged cooling: Transfer solution D to a culture tank and place it in a constant temperature incubator at 40℃~50℃ for 12~48h. Then, lower the temperature of the constant temperature incubator to 15℃~30℃ and keep it for 12~48h. Then, transfer it to a freezer at -10℃~-25℃ for further cooling for 12~24h to obtain mixture E. (5) Vacuum drying: Pour the mixture E into a filter, filter out the solvent, and rinse with the antisolvent. The mass ratio of formamidine acetate to antisolvent is 1:1~1.5 to obtain solid F and filtrate G. Transfer solid F to a vacuum oven and dry it under vacuum at -0.1MPa to obtain FABr crystal product. Filtrate G is recovered and reused.

2. The method for synthesizing high-purity supercrystalline formamidinium bromide (FABr) according to claim 1, characterized in that: The antisolvent is methyl tert-butyl ether.

3. The method for synthesizing high-purity supercrystalline formamidinium bromide (FABr) according to claim 1, characterized in that: The antisolvent is ethyl acetate.

4. The method for synthesizing high-purity supercrystalline formamidinium bromide (FABr) according to claim 1, characterized in that: The antisolvent is diethyl ether.

5. The method for synthesizing high-purity supercrystalline formamidinium bromide (FABr) according to claim 1, characterized in that: The cooling rate for each stage of the phased cooling process is set to -2℃ / min to -5℃ / min.

6. The method for synthesizing high-purity supercrystalline formamidinium bromide (FABr) according to claim 1, characterized in that: The vacuum drying temperature is 50~70℃, and the time is 24~72 hours.

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