Perovskite particle preparation method, solar cell, and tandem solar cell

Abstract

The embodiment of the present application relates to a perovskite particle preparation method, a solar cell and a laminated solar cell, the perovskite particle preparation method comprises the following steps: dissolving organic raw materials and inorganic raw materials in a growth mother liquor and fully mixing to obtain a mixed solution; adjusting the reaction condition of the mixed solution, so that the mixed solution enters a nucleation critical state of perovskite particles; the mixed solution in the nucleation critical state is subjected to ultrasonic pulse stimulation, and the perovskite particles are screened out from the mixed solution after a preset time length. The embodiment of the present application is beneficial to simply and efficiently synthesizing a large amount of perovskite particles, improving the synthesis efficiency of perovskite solar cell preparation raw materials, and facilitating batch production of perovskite solar cell wafers.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of solar cells, in particular to a perovskite particle preparation method, a solar cell and a laminated solar cell. BACKGROUND

[0002] Fossil energy exists atmospheric pollution and limited reserves, and solar energy has advantages of clean, non-pollution and resource abundance, therefore, solar energy is gradually becoming a core clean energy to replace fossil energy, and solar cells become the development focus of clean energy utilization because of good photoelectric conversion efficiency.

[0003] An important factor affecting the proportion of solar energy in energy utilization is photoelectric conversion efficiency of solar cells, in order to improve the photoelectric conversion efficiency of solar cells, optimizing and improving the structure design and material composition of solar cells is a basic idea. Perovskite solar cells have a good development prospect because of long service life and relatively stable photoelectric conversion efficiency.

[0004] However, the current perovskite solar cell has problems of low manufacturing efficiency and difficulty in mass production. SUMMARY

[0005] The embodiment of the present application provides a perovskite particle preparation method, a solar cell and a laminated solar cell, which are at least beneficial to simply and efficiently synthesize a large amount of perovskite particles, improve the synthesis efficiency of perovskite solar cell preparation raw materials, and facilitate batch production of perovskite solar cell wafers.

[0006] The embodiment of the present application provides a perovskite particle preparation method, which comprises: dissolving organic raw materials and inorganic raw materials in a growth mother liquor and fully mixing and uniforming to obtain a mixed solution; adjusting the reaction condition of the mixed solution, so that the mixed solution enters a nucleation critical state of perovskite particles; performing ultrasonic pulse stimulation on the mixed solution entering the nucleation critical state, and screening the perovskite particles in the mixed solution after a preset time length.

[0007] In addition, the ultrasonic pulse stimulation on the mixed solution entering the nucleation critical state comprises: using ultrasonic waves with a frequency of 1Hz to 1MHz to perform the ultrasonic pulse stimulation on the mixed solution entering the nucleation critical state.

[0008] In addition, the duration of the ultrasonic pulse stimulation is 0.001S to 1S.

[0009] Additionally, the screening the perovskite particles from the mixed solution after the preset time length comprises: screening target perovskite particles from the mixed solution, the maximum distance between any two points on the outer surface of the target perovskite particles being 5 microns-100 microns.

[0010] Additionally, after the target perovskite particles are screened, the method further comprises: re-dissolving the remaining particles outside the target perovskite particles in the growth mother liquor or the mixed solution.

[0011] Additionally, the preset time length comprises 1 min to 2 h.

[0012] Additionally, after the mixed solution in the nucleation critical state is subjected to ultrasonic pulse stimulation, the method further comprises: adjusting the temperature of the mixed solution to 50°C-150°C.

[0013] Additionally, the adjusting the reaction condition of the mixed solution comprises: adjusting the temperature of the mixed solution to 25°C-150°C.

[0014] Additionally, before the organic raw material and the inorganic raw material are dissolved in the growth mother liquor, the method further comprises: determining the molar mass ratio of each element in the perovskite particles according to a target band gap of the perovskite particles; and weighing the organic raw material and the inorganic raw material according to the molar mass ratio of each element in the perovskite particles.

[0015] Additionally, the target band gap comprises 1 eV to 2 eV.

[0016] Correspondingly, the application also provides a solar cell, comprising: a first conductive layer, a first carrier transport layer, a perovskite absorption layer, and a second conductive layer which are sequentially stacked, the perovskite absorption layer comprising a plurality of perovskite particles, the perovskite particles being formed by the perovskite particle preparation method as described above.

[0017] Additionally, the first carrier transport layer is a hole transport layer or an electron transport layer.

[0018] Additionally, the solar cell further comprises: a second carrier transport layer, the second carrier transport layer being located between the perovskite absorption layer and the second conductive layer and being in contact with the perovskite absorption layer and the second conductive layer, respectively.

[0019] Additionally, in the case that the first carrier transport layer is a hole transport layer, the second carrier transport layer is an electron transport layer; in the case that the first carrier transport layer is an electron transport layer, the second carrier transport layer is a hole transport layer.

[0020] Correspondingly, the application also provides a laminated solar cell, comprising: a top cell, a bonding layer and a bottom cell which are sequentially stacked, wherein the top cell is the solar cell as described above.

[0021] In addition, the bottom cell comprises a crystalline silicon solar cell, a CIGS thin film solar cell, a cadmium telluride thin film solar cell, a III-V thin film solar cell or a narrow band gap perovskite thin film solar cell.

[0022] In addition, the bonding layer comprises a mechanical bonding layer composed of conductive glue.

[0023] The technical scheme provided by the application has at least the following advantages:

[0024] In the perovskite particle preparation scheme provided by the application, after the organic raw material and the inorganic raw material are dissolved in a growth mother liquor and fully mixed to obtain a mixed solution, the reaction conditions of the mixed solution are adjusted according to the characteristics of the perovskite particles, and the reaction system in the mixed solution is adjusted to a nucleation critical state of the perovskite particles. By adjusting the reaction system in the mixed solution to the nucleation critical state of the perovskite particles, the nucleation difficulty and the required time of the perovskite particles are reduced, and the nucleation efficiency and probability of the perovskite particles are improved. Then, the mixed solution in which the reaction system enters the nucleation critical state is subjected to ultrasonic pulse stimulation, and perovskite particles are screened out from the mixed solution after a preset time. By applying ultrasonic pulse stimulation to the mixed solution in which the reaction system is in the nucleation critical state, the nucleation number of the perovskite particles in the mixed solution is greatly increased by using extreme reaction conditions such as high temperature, high pressure and extremely high cooling rate, so that a large number of perovskite particles can be screened out from the mixed solution after a preset time, the synthesis efficiency of the perovskite particles is greatly improved, the raw material production efficiency of the perovskite solar cell sheet is improved, and the perovskite solar cell sheet can be mass-produced. BRIEF DESCRIPTION OF DRAWINGS

[0025] One or more embodiments are illustrated by way of example in the figures that are part of this disclosure and which are illustrative, but not limiting to the embodiments, unless otherwise specifically stated, the drawings in the figures do not constitute a proportional limit.

[0026] Figure 1 A flowchart of a perovskite particle preparation method provided by an embodiment of the application is shown in the figure.

[0027] Figure 2 A structural schematic diagram of a solar cell provided by another embodiment of the application is shown in the figure.

[0028] Figure 3 A structural schematic diagram of another solar cell provided by an embodiment of the application is shown in the figure.

[0029] Figure 4 A structure schematic diagram of a laminated solar cell is provided for another embodiment of the present application. DETAILED DESCRIPTION

[0030] As known from the background, perovskite solar cells have good development prospects due to the advantages of service life and photoelectric conversion efficiency, but the current perovskite solar cell production efficiency is low and it is difficult to mass-produce.

[0031] An embodiment of the present application provides a perovskite particle preparation method. In the process of preparing perovskite particles, the raw materials are dissolved in a growth mother liquor, and the mixed solution is obtained by fully mixing and uniformity. Then, the reaction conditions of the mixed solution are adjusted, and the reaction system in the mixed solution is adjusted to the nucleation critical state of perovskite particles. By adjusting the reaction system in the mixed solution to the nucleation critical state of perovskite particles, the difficulty and time required for perovskite particle nucleation are reduced, and the nucleation efficiency and probability of perovskite particles are improved. Then, the mixed solution in which the reaction system enters the nucleation critical state is subjected to ultrasonic pulse stimulation, and perovskite particles are screened out in the mixed solution after a preset time. By applying ultrasonic pulse stimulation to the mixed solution in which the reaction system is in the nucleation critical state, the nucleation number of perovskite particles in the mixed solution is greatly increased by using extreme reaction conditions such as high temperature, high pressure and extremely high cooling rate, so that a large number of perovskite particles can be obtained after a preset time, thereby greatly improving the synthesis efficiency of perovskite particles, avoiding the restriction of raw material synthesis efficiency on perovskite solar cell production, and facilitating mass production of perovskite solar cell sheets.

[0032] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art can understand that in the embodiments of the present application, many technical details are proposed in order to make the reader better understand the present application. However, the technical solutions claimed by the present application can be realized even without these technical details and various changes and modifications based on the following embodiments.

[0033] An embodiment of the present application provides a perovskite particle preparation method, which is applied to a perovskite particle synthesis device, such as an ultrasonic chemical device, etc. The preparation process of perovskite particles can refer to Figure 1 , including but not limited to the following steps:

[0034] Step 101: Dissolve the organic raw materials and inorganic raw materials in the growth mother liquor, and fully mix and uniformly obtain the mixed solution.

[0035] In the process of preparing perovskite particles, the particle synthesis equipment first dissolves the weighed organic and inorganic raw materials in a pre-prepared growth mother liquor. Then, the growth mother liquor containing the organic and inorganic raw materials is thoroughly stirred, shaken, and ultrasonically treated to obtain a fully mixed and homogeneous solution. The growth mother liquor can be propylene carbonate, butyrolactone, or other solvents that have a certain coordination ability with perovskite.

[0036] It is worth mentioning that the specific types of raw materials and growth mother liquor can be determined based on the basic preparation method used for perovskite particle preparation. These basic methods include cooling crystallization, reverse-temperature crystallization, and antisolvent-assisted crystallization. The selection of raw materials and growth mother liquor can be referenced during the dissolution of raw materials and preparation of the growth mother liquor. For example, when using antisolvent-assisted crystallization as the basic preparation method, methylammonium bromide (MABr, CH3NH3Br) can be used as the organic raw material, lead bromide (PbBr2) as the inorganic raw material, and N,N-dimethylformamide (DMF, C3H7NO) as the growth mother liquor, with dichloromethane (CH2CL2) as the antisolvent for perovskite particle preparation. When using the heated crystallization method as the basic preparation method, methylammonium iodide (MAI, CH3NH3I) and formamidinium iodide (FAI, (HC(NH2)2I)) can be used as organic raw materials, lead iodide (PbI2) as inorganic raw material, and propylene carbonate as the growth solution to prepare perovskite particles. When using the cooled crystallization method as the basic preparation method, methylammonium iodide (MAI) can be used as organic raw material, lead acetate trihydrate (Pb(CH2COOH)2·3H2O) as inorganic raw material, and hydroiodic acid (HI) as the growth solution to prepare perovskite particles. The specific basic preparation method, raw materials, and growth solution selected during particle preparation are not limited in the examples provided in this application.

[0037] In some embodiments, before dissolving the organic and inorganic raw materials in the growth mother liquor, the method further includes: determining the molar mass ratio of each element in the perovskite particles according to the target band gap of the perovskite particles; and weighing the organic and inorganic raw materials according to the molar mass ratio of each element in the perovskite particles.

[0038] Before synthesizing perovskite particles, the chemical formula of the perovskite particles to be synthesized can be determined based on the required band gap, i.e., the target band gap. Then, based on the chemical formula, the molar ratio of each element in the perovskite particles can be determined. After determining the molar ratio of each element in the perovskite particles to be synthesized, the different components in the organic material are adjusted according to the determined molar ratio, and then equimolar amounts of organic and inorganic raw materials are weighed.

[0039] For example, taking propylene carbonate as the growth mother liquor, organic raw materials as methylamine iodide (MAI, CH3NH3I) and formamidinium iodide (FAI, (HC(NH2)2I), and inorganic raw materials as lead iodide PbI2, the chemical formula of the prepared perovskite particles is MA X FA 1－ X PbI3.

[0040] Before the perovskite particle synthesis, if the chemical formula of the perovskite particles is determined according to the target band gap of the perovskite particles, the molar ratio of MAI to FAI in the organic raw materials to be dissolved is adjusted to 1:3 in the case of MA 0.25 FA 0.75 PbI3. 0.75 FA 0.25 PbI3. 0.5 FA 0.5 PbI3. In addition, in the process of adjusting the components in the organic raw materials, the inorganic raw materials need to be properly fine-tuned to keep the molar ratio of the organic raw materials to the inorganic raw materials always 1:1. After the molar ratio of each component in the organic raw materials is determined, the organic raw materials and the inorganic raw materials are weighed according to the determined molar ratio.

[0041] By determining the molar mass ratio of each element in the perovskite particles according to the target band gap of the perovskite particles to be synthesized, and weighing the raw materials according to the determined molar mass ratio, as many perovskite particles as possible in the prepared perovskite particles can meet the band gap requirements, which is convenient for subsequent application of the perovskite particles.

[0042] In some embodiments, the target band gap is 1 eV to 2 eV. Before the perovskite particle preparation, the subsequent application of the perovskite particles and the requirements in the solar cell photoelectric conversion process are considered. In the case of too small band gap of the perovskite particles, the solar cell made by using the perovskite particles to construct the perovskite absorption layer has poor light energy absorption capacity and absorbs less energy, so the number of generated carriers is very small, resulting in poor photoelectric conversion capacity of the solar cell; in the case of too large band gap of the perovskite particles, the solar cell made by using the perovskite particles to construct the absorption layer cannot absorb low-energy light for photoelectric conversion, the range of light that can be used by the solar cell is reduced, resulting in a decrease in light utilization rate of the solar cell.

[0043] Therefore, the energy band gap of the perovskite particles to be synthesized is set to 1eV to 2eV, for example, 1.2eV, 1.35eV, 1.5eV, 1.8eV or 1.95eV, etc., and the perovskite particles are prepared according to the target energy band gap of the perovskite particles to be synthesized. By setting the energy band gap of the perovskite particles to 1eV to 2eV, it is convenient for subsequent use of the perovskite particles to make high-efficiency solar cells, and to ensure that the solar cells made of the perovskite particles have good photoelectric conversion capability and light utilization capability.

[0044] In step 102, the reaction conditions of the mixed solution are adjusted so that the mixed solution enters the nucleation critical state of the perovskite particles.

[0045] After the raw materials are dissolved in the growth mother liquor and fully mixed to obtain the mixed solution, the particle synthesis equipment adjusts the reaction conditions of the mixed solution so that the reaction system in the mixed solution enters the nucleation state of the perovskite particles. The reaction conditions include temperature, pressure, catalyst, etc.

[0046] In some embodiments, adjusting the reaction conditions of the mixed solution includes adjusting the temperature of the mixed solution to 50°C to 150°C.

[0047] During the adjustment of the reaction conditions of the mixed solution, the nucleation suitable temperature of the perovskite particles needs to be considered, that is, at what temperature range of the reaction system in the mixed solution is the nucleation quantity of the perovskite particles larger. In the case of too high temperature of the mixed solution, the reaction system in the mixed solution may be too fast due to the too high temperature, thereby causing the adjacent perovskite particles to nucleate and aggregate, reducing the yield of the perovskite particles; in the case of too low temperature of the mixed solution, the reaction system in the mixed solution may be too slow due to the too low temperature, thereby causing the nucleation quantity of the perovskite particles to be too small or too slow, and it is difficult to improve the productivity of the perovskite particles.

[0048] Therefore, before adjusting the reaction conditions of the mixed solution, the nucleation suitable temperature of different types of single-crystal perovskite particles or polycrystal perovskite particles is determined according to the structure of the perovskite particles to be synthesized. Then, based on the energy band gap requirement of the perovskite particles to be synthesized, the specific type and structure of the perovskite particles to be synthesized are determined, and the nucleation suitable temperature of the perovskite particles is determined according to the specific type and structure of the synthesized perovskite particles. Finally, the temperature of the mixed solution is adjusted to 50°C to 150°C, for example, 55°C, 65°C, 79°C, 92.5°C, 120°C, 138°C or 147°C, etc., by combining the reaction suitable temperature of each material in the reaction system, so that the reaction system of the mixed solution enters the nucleation suitable temperature of the perovskite particles.

[0049] By adjusting the temperature of the mixed solution to 50-150°C, the reaction system in the mixed solution enters the suitable temperature for perovskite particle nucleation, and thus as many perovskite particles as possible can be nucleated in the mixed solution, and the number of synthesized perovskite particles is increased.

[0050] It is worth mentioning that in the process of adjusting the temperature of the mixed solution to 50-150°C, the mixed solution can be heated by a microwave reactor. For example, when the mixed solution is heated to 115°C, after the mixed solution is transferred into the microwave reactor, the heating temperature can be directly set to 115°C, and the mixed solution is heated to 115°C by the microwave reactor. By directly setting the heating temperature, the mixed solution can enter the suitable temperature for perovskite particle nucleation as soon as possible. The mixed solution can also be heated to 115°C by gradient heating, for example, the power of the microwave reactor is set to 250W, and the heating temperature and the corresponding heating time are controlled by gradient heating, which are 75°C-5min, 85°C-5min, 95°C-5min, 105°C-10min, and 115°C-5min. By gradient heating, the mixed solution can avoid side reactions or other abnormal reactions caused by rapid heating, and ensure that the mixed solution safely enters the suitable temperature for perovskite particle nucleation.

[0051] In addition, in order to further improve the synthesis efficiency of perovskite particles, a combination of multiple basic preparation methods can be used to synthesize perovskite particles. For example, in the case of combining the anti-solvent gas assisted method to synthesize perovskite particles, when adjusting the reaction conditions, the pressure, concentration and flow rate of the anti-solvent gas need to be adjusted, and the nucleation efficiency and number of perovskite particles are further improved.

[0052] Step 103, the mixed solution in the nucleation critical state is subjected to ultrasonic pulse stimulation, and perovskite particles are screened out from the mixed solution after a preset time.

[0053] The particle synthesis device adjusts the reaction conditions to make the reaction system in the mixed solution enter a nucleation critical state of perovskite particles, and then performs ultrasonic pulse stimulation on the mixed solution in the nucleation critical state through an ultrasonic device. Then, the reaction system in the mixed solution is allowed to react, and after the ultrasonic pulse stimulation is completed for a preset time length, the generated perovskite particles are screened out from the mixed solution. By applying ultrasonic pulse stimulation to the mixed solution in which the reaction system is in the nucleation critical state, the nucleation number of perovskite particles in the mixed solution is greatly increased by using extreme reaction conditions such as high temperature, high pressure, and extremely high cooling rate generated instantaneously. A large number of perovskite particles can be obtained after a preset time length, thereby greatly improving the synthesis efficiency of perovskite particles and avoiding the restriction of raw material synthesis efficiency on perovskite solar cell production, so as to facilitate mass production of perovskite solar cells. The synthesized perovskite particles can be single-crystal perovskite particles or polycrystal perovskite particles.

[0054] It is worth mentioning that, before the ultrasonic pulse stimulation is performed on the mixed solution before entering the nucleation critical state, a suitable stabilizer or additive can be added to the mixed solution and mixed uniformly in the mixed solution. The stabilizer and the additive serve to control the growth rate of the crystal during the crystal growth process, reduce the influence of ultrasonic pulse stimulation on the growth of the nucleated perovskite particles, make the size of the obtained perovskite particles as uniform as possible, reduce the crystal defects on the perovskite particles, and improve the quality of the synthesized perovskite particles. The type of the added stabilizer or additive can be selected according to the structure and type of the perovskite particles, and the embodiments of the present application do not limit this.

[0055] In some embodiments, the ultrasonic pulse stimulation on the mixed solution in the nucleation critical state includes: using ultrasonic waves with a frequency of 1 Hz to 1 MHz to perform ultrasonic pulse stimulation on the mixed solution in the nucleation critical state.

[0056] The purpose of the ultrasonic pulse stimulation on the mixed solution by the particle synthesis device is to increase the nucleation number of perovskite particles in the mixed solution, and thus to increase the number of synthesized perovskite particles. In the case of using ultrasonic waves with too high a frequency for ultrasonic pulse stimulation, although it can provide sufficient capacity to greatly increase the nucleation efficiency and number of perovskite particles, in the case of too much energy, the aggregation ability between adjacent perovskite particles is greatly improved, and thus the formed perovskite particles are excessively aggregated, changing from single crystals or regular polycrystals to irregular polycrystals. Therefore, although large-scale nucleation of perovskite particles occurs in the mixed solution, due to the excessive aggregation between adjacent perovskite particles, the number of single-crystal perovskite particles or regular polycrystal perovskite particles is greatly reduced, and thus the preparation efficiency of perovskite particles is reduced.

[0057] In the case that the frequency of the ultrasonic wave used in the ultrasonic pulse stimulation is too small, the energy provided by the ultrasonic pulse stimulation is too low to effectively provide ideal reaction conditions for the nucleation of perovskite particles, and thus the number of nucleated perovskite particles in the mixed solution is limited, and the preparation efficiency of perovskite particles cannot be effectively improved.

[0058] Therefore, during the ultrasonic pulse stimulation, the frequency of the ultrasonic wave used needs to be controlled, and the ultrasonic pulse stimulation is performed on the mixed solution in the critical nucleation state by using ultrasonic waves with a frequency of 1 Hz to 1 MHz. For example, the ultrasonic pulse stimulation is performed on the mixed solution by using ultrasonic waves with a frequency of 5 Hz, 10 Hz, 75 Hz, 100 Hz, 500 Hz, 1 KHz, 5 KHz, 10 KHz, 100 KHz, 500 KHz, 750 KHz, or 900 KHz. The number of nucleated perovskite particles in the mixed solution is greatly increased, and at the same time, the excessive aggregation between adjacent perovskite particles is avoided, so that the single-crystal perovskite particles or regular polycrystal perovskite particles to be synthesized are not converted into irregular polycrystal particles, and the actual yield of perovskite particles can also be greatly improved.

[0059] In some embodiments, the duration of the ultrasonic pulse stimulation is 0.001 S to 1 S.

[0060] During the ultrasonic pulse stimulation of the mixed solution by the particle synthesis device, not only the energy carried by the ultrasonic wave but also the duration of the ultrasonic pulse stimulation affects the number of nucleated perovskite particles in the mixed solution. In the case that the duration of the ultrasonic pulse stimulation is too long, the growth rate of some perovskite particles after nucleation is too fast, which causes the adhesion or aggregation between adjacent perovskite particles, so that the single-crystal perovskite particles are aggregated into polycrystal perovskite particles, or the regular polycrystal perovskite particles are converted into irregular polycrystal perovskite particles. At the same time, under the effect of the ultrasonic pulse stimulation, the number of crystal defects on the perovskite particles also increases, which affects the quality of the formed perovskite particles.

[0061] In the case that the duration of the ultrasonic pulse stimulation is too short, the number of perovskite particles that can quickly nucleate is limited, and the nucleation process of some perovskite particles may be interrupted, which causes slow nucleation or no nucleation, resulting in a limited increase in the number of nucleated perovskite particles. At the same time, due to the short duration of the ultrasonic pulse stimulation, the growth rate of the nucleated perovskite particles is also slow, and the time required for the nucleated perovskite particles to grow to a sufficient size is greatly increased, which further causes the waiting time required for the selection of perovskite particles to be greatly increased, and the preparation efficiency of perovskite particles is limited.

[0062] Therefore, during the process of the ultrasonic pulse stimulation, the duration of the ultrasonic pulse stimulation needs to be controlled, and the duration of the ultrasonic pulse stimulation on the mixed solution in the nucleation critical state is controlled to be 0.001S to 1S. For example, the duration of the ultrasonic pulse stimulation is controlled to be 0.001S, 0.002S, 0.005S, 0.01S, 0.015S, 0.025S, 0.05S, 0.08S, 0.1S, 0.2S, 0.5S, or 0.75S, etc. In this way, the number of nucleation of the perovskite particles in the mixed solution is greatly improved, the preset duration for waiting for screening of the perovskite particles is reduced, the adhesion or aggregation between the perovskite particles is avoided, the number of the perovskite particles is ensured, the crystal defects of the generated perovskite particles are as few as possible, and the quality of the perovskite particles is ensured.

[0063] In addition, during the process of the ultrasonic pulse stimulation, the duration of the ultrasonic pulse stimulation and the frequency of the ultrasonic wave are controlled, the mixed solution is stimulated for a suitable duration by the appropriate ultrasonic wave, the number of nucleation of the perovskite particles is as high as possible, the aggregation of the perovskite particles in the growth process is avoided, the quality of the perovskite particles is ensured, and the production capacity of the perovskite particles is as high as possible.

[0064] In some embodiments, after the ultrasonic pulse stimulation on the mixed solution in the nucleation critical state, the temperature of the mixed solution is adjusted to 25℃-150℃.

[0065] After the ultrasonic pulse stimulation on the mixed solution by the particle synthesis device, a large number of perovskite particles are nucleated in the mixed solution, and the nucleated perovskite particles grow in the mixed solution. During the growth process, if the temperature of the mixed solution is too high, the growth speed of the particles is too large, the adhesion or aggregation between the adjacent particles occurs, and the number of the perovskite particles obtained finally is reduced. If the temperature of the mixed solution is too low, the growth speed of the particles is too small, the particles grow slowly, and the preset duration for waiting for screening of the perovskite particles is large, which limits the production capacity of the perovskite particles.

[0066] Therefore, after the ultrasonic pulse stimulation, the temperature of the mixed solution is adjusted to 25℃ to 150℃, for example, to 25℃, 30℃, 35℃, 45℃, 55℃, 65℃, 79℃, 92.5℃, 120℃, 138℃, or 147℃, etc., so that the reaction system of the mixed solution enters the growth adaptation temperature of the perovskite particles. In this way, the growth of the nucleated perovskite particles in the mixed solution is as fast as possible, the aggregation or adhesion between the adjacent perovskite particles is avoided, and the number of the synthesized perovskite particles is improved.

[0067] In addition, the suitable temperature for nucleation and the suitable temperature for growth of the perovskite particles can be the same or different, and varies according to the structure and type of the perovskite particles, and thus, whether to adjust the temperature of the mixed solution after the ultrasonic pulse stimulation can be determined according to the type and structure of the perovskite particles to be synthesized, which is not limited in the embodiments of the present application.

[0068] In some embodiments, the perovskite particles are screened from the mixed solution after the preset time period, including: screening target perovskite particles from the mixed solution, the maximum distance between any two points on the outer surface of the target perovskite particles being 5 microns to 100 microns.

[0069] In the process of screening the perovskite particles from the mixed solution after the preset time period, the particles synthesis device can first use the mechanical arm to fish out the perovskite particles formed in the mixed solution and transfer them to an intermediate container. Then, the perovskite particles in the intermediate container are washed clean and transferred to a screening machine to screen target perovskite particles with appropriate size as products.

[0070] When the size of the perovskite particles is too large, i.e., the maximum distance between any two points on the surface of the particles is too large, after the perovskite particles are used to manufacture the absorption layer of the solar cell, the distance that the carriers need to move to the carrier transport layer or the conductive layer is too large after the carriers are generated by absorbing light energy, and it is difficult to complete the carrier migration, thereby resulting in poor photoelectric conversion efficiency of the solar cell. When the size of the perovskite particles is too small, i.e., the maximum distance between any two points on the surface of the particles is too small, the distance between different carriers is small during the migration of the carriers, and thus, the recombination of the carriers is prone to occur, resulting in poor photoelectric conversion efficiency of the solar cell.

[0071] Therefore, in the process of screening the perovskite particles, target perovskite particles with the maximum distance between any two points on the surface of the particles being 5 microns to 100 microns are screened, for example, target perovskite particles with the maximum distance between any two points on the surface of the particles being 5 microns, 7.5 microns, 10 microns, 15 microns, 25 microns, 60 microns, 80 microns, 85 microns or 95 microns, etc. are screened as the synthesis products. While ensuring that the carriers can more easily complete the carrier migration, the probability of recombination between different carriers is reduced, and the photoelectric conversion efficiency of the solar cell made of perovskite particles is ensured as much as possible.

[0072] In addition, in the process of screening the target perovskite particles, the screening can be performed by the screening machine, the particles with a size less than 5 microns are first screened out by the screening machine, and then the particles with a size greater than 100 microns are screened out; or the particles with a size greater than 100 microns are first screened out, and then the particles with a size less than 5 microns are screened out, wherein the particle size is the maximum distance between any two points on the surface of the particles. The specific screening method is not limited in the embodiments of the present application.

[0073] In addition, in the process of screening the target perovskite particles, in order to facilitate the subsequent use of the perovskite particles, further screening can be performed on the perovskite particles of a specific size in the target perovskite particles. For example, in the process of preparing a single-particle perovskite particle film using the perovskite particles, the perovskite particles with a size of 80 μm to 85 μm have better film forming effect. Therefore, in the process of screening the target perovskite particles, the target perovskite particles with a size of 5 μm to 100 μm can be screened out first, and then the perovskite particles with a size of 80 μm to 85 μm are screened out from the target perovskite particles. Alternatively, in the process of screening the target perovskite particles, the size of the target perovskite particles is directly limited to 80 μm to 85 μm, and the perovskite particles with a size of 80 μm to 85 μm are screened out by the screening machine as the target perovskite particles. The specific screening method in the screening process and the method of screening the target perovskite particles with a size of 5 μm to 100 μm are the same, and will not be described here. By further screening the target perovskite particles or further limiting the size range of the target perovskite particles, the target perovskite particles that are convenient to use can be accurately screened out from the mixed solution, and the application convenience of the perovskite particles is improved.

[0074] In some embodiments, the preset time length is 1 min to 2 h. Before the target perovskite particles are screened, the particles need to be generated in the mixed solution for a preset time length. If the preset time length is too small, the particle growth time is limited, and the size of the screened particles is too small. If the preset time length is too large, the particle growth time is too long, and the size of the screened particles is too large.

[0075] Therefore, before the particle synthesis equipment is used to screen the target perovskite particles, the preset time length for waiting for the generation of the perovskite particles is set to a time length of 1 min to 2 h, for example, 1 min, 5 min, 20 min, 45 min, 1 h, 1.5 h or 1 h 10 min, etc. The growth time of the perovskite particles in the mixed solution is appropriate, the number of the target perovskite particles in the mixed solution is as large as possible, and the production capacity of the target perovskite particles is improved.

[0076] In addition, due to the existence of certain errors in the nucleation time of each perovskite particle in the mixed solution, and the generation of part of the perovskite particles is inevitably disturbed by the ultrasonic pulse stimulation, the number distribution of perovskite particles of different sizes in the mixed solution can be approximately regarded as a normal distribution. Therefore, in combination with the target size of the target perovskite particles, that is, the target range of the maximum distance between any two points on the surface of the particle, the specific setting of the preset time length can ensure that the number of perovskite particles with the target size in the mixed solution is the largest. Thus, the synthesis efficiency of the target perovskite particles is further improved, and the production capacity of the target perovskite particles is improved.

[0077] In some embodiments, after the target perovskite particles are screened out, the remaining particles outside the target perovskite particles are further dissolved in the growth mother liquor or the mixed solution.

[0078] After the target perovskite particles are screened out, the particle synthesis device re-dissolves the remaining particles that are too large or too small in size into the growth mother liquor as raw materials for subsequent synthesis of perovskite particles, thereby avoiding waste of the remaining particles and reducing the cost of perovskite particle synthesis. Alternatively, the remaining particles that are too large or too small in size are re-dissolved into the mixed solution, and then the reaction conditions of the mixed solution are adjusted again for secondary perovskite particle preparation, thereby avoiding waste of the remaining raw materials and the remaining particles in the mixed solution and further reducing the cost of perovskite particle synthesis.

[0079] In summary, in the perovskite particle preparation method provided by an embodiment of the present application, after the raw materials are dissolved in the growth mother liquor and fully mixed to obtain a mixed solution, the reaction conditions of the mixed solution are adjusted to adjust the reaction system in the mixed solution to a nucleation critical state of perovskite particles. By adjusting the reaction system in the mixed solution to the nucleation critical state of perovskite particles, the difficulty and time required for perovskite particle nucleation are reduced, and the nucleation efficiency and probability of perovskite particles are improved. Then, the mixed solution in which the reaction system enters the nucleation critical state is subjected to ultrasonic pulse stimulation, and perovskite particles are screened out from the mixed solution after a preset time period. By applying ultrasonic pulse stimulation to the mixed solution in which the reaction system is in the nucleation critical state, the nucleation number of perovskite particles in the mixed solution is greatly increased by using extreme reaction conditions such as high temperature, high pressure, and extremely high cooling rate generated instantaneously, so that a large number of perovskite particles can be obtained after a preset time period, thereby greatly improving the synthesis efficiency of perovskite particles, avoiding the restriction of raw material synthesis efficiency on perovskite solar cell production, and facilitating mass production of perovskite solar cells.

[0080] Correspondingly, another embodiment of the present application further provides a solar cell, and a structural schematic diagram of the solar cell can refer to Figure 2 , which comprises a first conductive layer 201, a first carrier transport layer 202, a perovskite absorption layer 203, and a second conductive layer 204 which are sequentially stacked, wherein the perovskite absorption layer comprises a plurality of perovskite particles formed by the above perovskite particle preparation method.

[0081] The first conductive layer 201 and the second conductive layer 204 can be composed of metal grid lines or conductive films, and are used to transmit the electrical energy generated by the solar cell to external components.

[0082] In some embodiments, the first carrier transport layer 202 is a hole transport layer or an electron transport layer.

[0083] That is, the first carrier transport layer 202 is to collect and transport the carriers generated in the perovskite absorption layer 203, and based on the working mechanism of the solar cell, the first carrier transport layer 202 can be a hole transport layer or an electron transport layer.

[0084] Reference Figure 3 In some embodiments, the solar cell further comprises a second carrier transport layer 205, which is located between the perovskite absorption layer 203 and the second conductive layer 204 and in contact with the perovskite absorption layer 203 and the second conductive layer 204, respectively.

[0085] In order to further improve the efficiency of the solar cell, a carrier transport layer for collecting and transporting different carriers can be arranged on the opposite sides of the perovskite absorption layer 203, respectively.

[0086] In some embodiments, when the first carrier transport layer 202 is a hole transport layer, the second carrier transport layer 205 is an electron transport layer; and when the first carrier transport layer 202 is an electron transport layer, the second carrier transport layer 205 is a hole transport layer.

[0087] Correspondingly, another embodiment of the present application also provides a laminated solar cell, and a structural schematic diagram of the laminated solar cell can refer to Figure 4 , which comprises a top cell 401, a bonding layer 402 and a bottom cell 403 arranged in sequence, wherein the top cell 401 is the above-mentioned solar cell.

[0088] In some embodiments, the type of the bottom cell 403 includes a crystalline silicon solar cell, a CIGS thin-film solar cell, a cadmium telluride thin-film solar cell, a III-V thin-film solar cell or a narrow-bandgap perovskite thin-film solar cell, wherein the narrow-bandgap perovskite thin-film solar cell can be a narrow-bandgap single-crystal perovskite thin-film solar cell or a narrow-bandgap polycrystal perovskite thin-film solar cell.

[0089] In some embodiments, the bonding layer 402 comprises a mechanical bonding layer formed by conductive glue. The conductive glue can be formed by adding conductive particles to transparent glue with good light transmittance, for example, adding conductive particles to glue with a light transmittance of 80% or more above 400 nm or glue with a light transmittance of 80% or more above 450 nm. The conductive glue can also be transparent thin glue with certain conductive energy, and the degree of transparency can be similar to the above-mentioned glue. The specific type of conductive glue is not limited in the embodiments of the present application.

[0090] The application discloses the above-mentioned preferred embodiments, but is not intended to limit the claims, any person skilled in the art can make several possible changes and modifications without departing from the concept of the application, therefore the protection scope of the application should be limited by the claims.

[0091] Those skilled in the art can understand that the above-mentioned embodiments are specific embodiments for implementing the application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the application, therefore the protection scope of the application should be limited by the claims.

Claims

1. A method for preparing perovskite particles, characterized by, The method comprises the following steps: dissolving organic raw materials and inorganic raw materials in a growth mother liquor and mixing them evenly to obtain a mixed solution; adjusting the reaction conditions of the mixed solution so that the mixed solution enters a nucleation critical state of perovskite particles; ultrasonic pulse stimulation is performed on the mixed solution that has entered the nucleation critical state, and the perovskite particles are screened out from the mixed solution after a preset time length; the adjustment of the reaction conditions of the mixed solution comprises adjusting the temperature of the mixed solution to 50-150 DEG C.

2. The method of claim 1, wherein the perovskite particles are prepared by a method comprising: the ultrasonic pulse stimulation on the mixed solution that has entered the nucleation critical state comprises: the ultrasonic pulse stimulation on the mixed solution that has entered the nucleation critical state is performed by using ultrasonic waves with a frequency of 1-1 MHz.

3. The method for preparing perovskite particles according to claim 1, characterized in that, the duration of the ultrasonic pulse stimulation is 0.001-1 s.

4. The method of claim 1, wherein the perovskite particles are prepared by a method comprising: the screening of the perovskite particles from the mixed solution after a preset time length comprises: target perovskite particles with a maximum distance between any two points on the outer surface of 5-100 microns are screened out from the mixed solution.

5. The method of claim 4, wherein the perovskite particles are prepared by a method comprising: after the target perovskite particles are screened out, the remaining particles outside the target perovskite particles are re-dissolved in the growth mother liquor or the mixed solution.

6. The method of claim 1, wherein the perovskite particles are prepared by a method comprising: the preset time length is 1 min-2 h.

7. The method for preparing perovskite particles according to claim 1, characterized in that, after the ultrasonic pulse stimulation on the mixed solution that has entered the nucleation critical state, the temperature of the mixed solution is adjusted to 25-150 DEG C.

8. The method of claim 1 to 7, wherein before the organic raw materials and the inorganic raw materials are dissolved in the growth mother liquor, the following steps are further included: according to the target energy band gap of the perovskite particles, the molar mass ratio of each element in the perovskite particles is determined; according to the molar mass ratio of each element in the perovskite particles, the organic raw materials and the inorganic raw materials are weighed.

9. The method for preparing perovskite particles according to claim 8, characterized in that, the target energy band gap is 1-2 eV.

10. A solar cell, characterized by, The method comprises the following steps: a first conductive layer, a first carrier transport layer, a perovskite absorption layer and a second conductive layer are sequentially stacked, the perovskite absorption layer comprises a plurality of perovskite particles, and the perovskite particles are formed by the perovskite particle preparation method according to any one of claims 1-9.

11. The solar cell of claim 10, wherein, The first carrier transport layer is a hole transport layer or an electron transport layer.

12. The solar cell of claim 10, wherein, Further comprising: a second carrier transport layer is located between the perovskite absorption layer and the second conductive layer and in contact with the perovskite absorption layer and the second conductive layer, respectively.

13. The solar cell of claim 12, wherein, In the case where the first carrier transport layer is a hole transport layer, the second carrier transport layer is an electron transport layer; in the case where the first carrier transport layer is an electron transport layer, the second carrier transport layer is a hole transport layer.

14. A stacked solar cell, characterized by The method comprises the following steps: a top cell, a bonding layer and a bottom cell are sequentially stacked, and the top cell is a solar cell according to any one of claims 11-13.

15. The tandem solar cell of claim 14, wherein, The bottom cell comprises a crystalline silicon solar cell, a CIGS thin-film solar cell, a cadmium telluride thin-film solar cell, a III-V thin-film solar cell or a narrow-bandgap perovskite thin-film solar cell.

16. The laminated solar cell of claim 14, wherein, The conforming layer includes a mechanical conforming layer comprised of a conductive glue. The conforming layer includes a mechanical conforming layer comprised of a conductive glue.

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