Perovskite thin film and preparation method thereof, perovskite solar cell, and optoelectronic device

Abstract

The application relates to the technical field of preparing photoelectric materials, and particularly relates to a perovskite thin film and a preparation method thereof, a perovskite solar cell and a photoelectric device. The preparation method comprises the following steps: forming a perovskite precursor liquid film on a substrate by using a perovskite precursor liquid, wherein the perovskite precursor liquid comprises a first solvent and perovskite precursor materials; forming a gas atmosphere in a container, maintaining the airtightness of the container, heating the perovskite precursor liquid film to a first temperature, increasing the internal air pressure of the container to a preset air pressure, and the preset air pressure is 5-300 kPa higher than the external air pressure of the container; changing the airtightness of the container to maintain the preset air pressure, heating, drying, and preparing a perovskite dry film; and performing annealing treatment to prepare the perovskite thin film. The method can effectively reduce pores and defects at the perovskite / substrate interface, and can prepare a high-quality perovskite thin film without pores and a high-efficiency and stable solar cell.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic materials technology, specifically to a perovskite thin film and its preparation method, a perovskite solar cell, and an optoelectronic device. Background Technology

[0002] In research and laboratory settings, perovskite thin films are typically prepared using spin coating. However, spin coating relies on high-speed centrifugal force to remove solvent and obtain a dry perovskite film, a process that results in 90% material waste and is difficult to scale up to the fabrication of square-scale cells. Current drying methods for large-area perovskite thin films include air knife blowing, vacuum flash evaporation, and anti-solvent immersion. These methods rapidly remove most of the solvent within seconds to minutes, causing the solvent to leave through the upper surface of the film. This leads to a sharp increase in solute concentration near the upper surface, creating a supersaturated state. This high supersaturation in the upper layer of the film causes homogeneous nucleation and crystallization, which then grows downwards—a solidification process from the upper surface to the bottom. During this top-down process, some solvent remains at the bottom of the perovskite film, leaving submicron-sized voids at the buried interface during subsequent annealing. These voids hinder the extraction of photogenerated carriers by the charge transport layer, exacerbating charge accumulation and ion migration at the interface, directly leading to the decomposition of the perovskite and severely impacting the long-term operational stability of perovskite solar cells.

[0003] Therefore, there is an urgent need to propose a perovskite thin film and its preparation method, which can effectively reduce the porosity and defects at the perovskite / substrate interface, and prepare a high-quality perovskite thin film without pores and a highly efficient and stable perovskite solar cell. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a perovskite thin film and its preparation method, a perovskite solar cell, and an optoelectronic device. In particular, it relates to a method for the slow removal of solvent from a perovskite wet film and the slow crystallization of perovskite. In this method, the solvent removal time can reach tens of minutes to several hours, allowing the perovskite thin film to crystallize and grow from the bottom up, reducing the porosity at the buried interface of the film, and can be used for the production and preparation of large-area perovskite thin films.

[0005] The inventive concept of this invention is to design and develop a semi-closed annealing device that can precisely control the solvent vapor overflow rate. During the solvent evaporation process, the supersaturation of the upper solution is precisely controlled, which slows down and suppresses the homogeneous nucleation rate in the upper solution. By utilizing the rate advantage of heterogeneous nucleation on the substrate, the growth of perovskite crystals from the substrate is realized, reducing voids and defects at the buried interface, and ultimately improving the performance of large-area perovskite films.

[0006] The first aspect of the present invention provides a method for preparing a perovskite thin film, comprising the following steps:

[0007] (1) A perovskite precursor liquid forms a perovskite precursor liquid film on a substrate, wherein the perovskite precursor liquid includes a first solvent and a perovskite precursor material.

[0008] (2) A gas atmosphere is formed inside the container to maintain the airtightness of the container. The perovskite precursor liquid film is heated to raise the temperature to a first temperature, so that the internal gas pressure of the container rises to a preset gas pressure. The preset gas pressure is 5-200 kPa greater than the external gas pressure of the container. Preferably, the preset gas pressure is 105-150 kPa.

[0009] (3) Change the airtightness of the container to maintain the preset air pressure, heat the perovskite precursor liquid film to raise the temperature to a second temperature and maintain it, dry it, and obtain a perovskite dry film.

[0010] (4) The perovskite dry film is annealed to obtain the perovskite thin film.

[0011] Compared to existing technologies, the beneficial effects of the method for preparing perovskite thin films provided in this first aspect are as follows:

[0012] This method dries the perovskite precursor liquid film under controlled temperature and vapor pressure, controlling the supersaturation of the wet perovskite film and enabling slow crystallization growth of the perovskite film from the substrate upwards. Compared to other perovskite film drying methods, this method effectively reduces porosity and defects at the perovskite / substrate interface, producing a high-quality, pore-free perovskite film and a highly efficient and stable perovskite solar cell. Furthermore, the perovskite solar cell containing this perovskite film exhibits a fill factor and photoelectric conversion efficiency exceeding 0.70 and 19.5%, respectively. The stability of the fabricated perovskite solar cell is significantly improved, maintaining over 90% of its initial efficiency after 1000 hours of continuous operation under sunlight.

[0013] Preferably, in step (1), the method for forming the perovskite precursor liquid film includes at least one of slot coating, scraper coating, spraying, spin coating, and inkjet printing.

[0014] Preferably, in step (1), the first solvent includes at least one of γ-butyrolactone, dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone.

[0015] Preferably, in step (1), the perovskite precursor material includes at least one of ABX3, AX, and BX2 type perovskite materials; wherein A is selected from CH3NH 3+ CH3CH2NH 3+NH2CH=NH 2+ Cs + At least one of them, B is selected from Pb 2+ Sn 2+ 、Ge 2+ At least one of them, X is selected from Cl - ,Br - I - At least one of them.

[0016] Preferably, in step (1), the perovskite precursor material is of type ABX3, where A is CH3NH 3+ CH3CH2NH 3+ NH2CH=NH 2+ Cs + At least one of them, B is Pb 2+ Sn 2+ 、Ge 2+ At least one of them, X is selected from Cl - ,Br - I - At least one of them.

[0017] Preferably, in step (1), the substrate includes one of tin fluoride oxyfluoride (FTO) conductive glass, indium tin oxide (ITO) conductive glass, and aluminum-doped zinc oxide (AZO) conductive glass.

[0018] Preferably, in step (1), a seed crystal layer is first set on the substrate before forming the perovskite precursor liquid film; more preferably, the seed crystal layer includes lead iodide.

[0019] Preferably, the container is a drying device. The drying device includes: a shell; a heating mechanism disposed at the bottom and / or side wall of the shell for raising the temperature inside the shell; a pressure detector connected to the shell for monitoring the pressure inside the shell; and an exhaust port, which is controllable from fully closed to fully open and disposed on the shell for controlling the airtightness of the shell.

[0020] Preferably, the drying device further includes a temperature monitoring device for monitoring the temperature inside the housing; more preferably, the temperature monitoring device includes at least one of a thermocouple, a liquid thermometer, a resistance temperature measuring device, an infrared temperature sensor, and a bimetallic thermometer.

[0021] Preferably, the drying device further includes a solvent tank disposed within the housing for storing the second solvent.

[0022] Preferably, the drying apparatus further includes: an atmosphere-forming heating mechanism connected to the solvent tank for heating the solvent tank; the atmosphere-forming heating mechanism includes at least one of a heating platform, a heating wire, and a heating rod.

[0023] Preferably, the drying device further includes a gas filling device mechanism connected to the housing for filling the housing with gas; more preferably, the gas filling device mechanism includes at least one of a gas cylinder and a steam generator.

[0024] Preferably, the drying device further includes an exhaust mechanism connected to the housing for discharging gas from the housing.

[0025] Preferably, the exhaust mechanism further includes at least one of an exhaust pipe, a vacuum pump, and a gas storage device.

[0026] Preferably, the heating mechanism includes at least one of a heating platform, a heating wire, and a heating rod.

[0027] Preferably, the pressure detection mechanism includes a barometer or a differential pressure gauge, and the barometer includes at least one of a digital barometer, a liquid-free barometer, and a mercury barometer.

[0028] Preferably, in step (2), the gas atmosphere includes at least one of an inorganic gas and the vapor of a second solvent; the inorganic gas includes at least one of nitrogen, oxygen, carbon dioxide, helium, neon, argon, krypton, xenon, and radon; the second solvent includes at least one of ethanol (EtOH), isopropanol (IPA), chlorobenzene, toluene (PhMe), ethyl acetate (EA), petroleum ether (PE), chloroform (TCM), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and γ-butyrolactone (GBL); alternatively, the gas atmosphere may be the outside air of the container.

[0029] Preferably, the method for forming a gaseous atmosphere includes: connecting the interior of the container to the outside to form a gaseous atmosphere; introducing inorganic gas and / or vapor of a second solvent into the container to form a gaseous atmosphere; adding the second solvent into the container and then heating the second solvent to form a gaseous atmosphere; first evacuating the container, then adding the second solvent into the container and then heating the second solvent to form a gaseous atmosphere; or first evacuating the container, then introducing inorganic gas and / or vapor of a second solvent into the container to form a gaseous atmosphere.

[0030] Preferably, in step (2), the first temperature is 55-115℃; more preferably, the first temperature is 60-110℃.

[0031] Preferably, in step (2), the rate of temperature increase is 5-10℃ / min.

[0032] Preferably, in step (2), the method for increasing the gas pressure inside the container includes: evaporation of the first solvent in the perovskite precursor liquid film, introduction of air and / or vapor of the second solvent into the container, pre-filling the container with the second solvent, and heating to cause the second solvent to evaporate.

[0033] Preferably, in step (2), the external air pressure is 98-104 kPa; more preferably, the external air pressure is 99-102 kPa; without limitation, the external air pressure can be standard atmospheric pressure.

[0034] Preferably, in step (2), the preset air pressure is 105-150 kPa; more preferably, the preset air pressure is 107-123 kPa; and even more preferably, the preset air pressure is 110-120 kPa.

[0035] Preferably, in step (2), the preset air pressure is 5-200 kPa greater than the external air pressure of the container; more preferably, the preset air pressure is 5-100 kPa greater than the external air pressure of the container; and even more preferably, the preset air pressure is 5-50 kPa greater than the external air pressure of the container.

[0036] Preferably, in step (3), the second temperature is 75-300℃; more preferably, the second temperature is 75-200℃; and even more preferably, the second temperature is 80-150℃.

[0037] Preferably, in step (3), the rate of temperature increase is 1-5℃ / min.

[0038] Preferably, in step (3), the drying is to dry the perovskite precursor liquid film while maintaining the second temperature.

[0039] Preferably, in step (4), the annealing temperature is 50-500℃; more preferably, the annealing temperature is 60-250℃; and even more preferably, the annealing temperature is 80-170℃.

[0040] A second aspect of the present invention provides a perovskite thin film, said perovskite thin film being prepared by any of the preparation methods described above.

[0041] A third aspect of the present invention provides a perovskite solar cell, the perovskite solar cell comprising the above-described perovskite thin film.

[0042] Preferably, the perovskite solar cell has a fill factor of more than 0.70 and a photoelectric conversion efficiency of more than 19.5%.

[0043] Preferably, the perovskite solar cell further includes an electron transport layer, a hole transport layer, electrodes, and a cell substrate.

[0044] Preferably, the electron transport layer and / or the hole transport layer are disposed on the battery substrate and connected to the battery substrate.

[0045] A fourth aspect of the present invention provides an optoelectronic device comprising the perovskite thin film described above.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] (1) This method dries the perovskite precursor liquid film under controlled temperature and vapor pressure, controlling the supersaturation of the perovskite wet film and achieving slow crystallization growth of the perovskite film from the substrate upwards. Compared with other perovskite film drying methods, this method can effectively reduce porosity and defects at the perovskite / substrate interface, producing a high-quality perovskite film without pores and a highly efficient and stable perovskite solar cell. Furthermore, the fill factor and photoelectric conversion efficiency of the perovskite solar cell containing this perovskite film exceed 0.70 and 19.5%, respectively. The stability of the prepared perovskite solar cell is greatly improved, maintaining more than 90% of its initial efficiency after 1000 hours of continuous operation under sunlight.

[0048] (2) With the drying device of the present invention, the supersaturation of the perovskite wet film can be effectively controlled, so as to realize the slow crystallization growth of the perovskite film from the substrate from bottom to top. Attached Figure Description

[0049] Figure 1 This is a scanning electron microscope image of the cross-section of the perovskite solar cell prepared in Example 1;

[0050] Figure 2 A scanning electron microscope image of the cross-section of the perovskite solar cell prepared in Comparative Example 1.

[0051] Figure 3 This is a schematic diagram of the structure in Example 2 where the substrate is placed inside the drying device;

[0052] Figure label:

[0053] 100-Housing, 200-Heating stage, 300-Exhaust vent with controllable sealing, 400-Digital barometer, 500-Mercury thermometer, 600-Solvent bath, 700-Heating wire, 800-Base. Detailed Implementation

[0054] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0055] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0056] Example 1

[0057] Example 1 describes the fabrication steps of a perovskite thin film and its corresponding perovskite solar cell.

[0058] The method for preparing perovskite thin films includes the following steps:

[0059] (1) Weigh out 39 mg CsI (cesium iodide), 146.17 mg FAI (formamidine iodide), 357.28 mg PbI2 (lead iodide), 82.58 mg PbBr2 (lead bromide), and 20.4 mg MACl (methylammonium chloride), respectively, and dissolve them in 1 mL of DMF (N,N-dimethylformamide) to prepare CsI. 0.15 FA 0.85 PbI 2.55 Br 0.45 Perovskite precursor solution: The prepared perovskite precursor solution is applied to the substrate to form a perovskite precursor solution liquid film by slit coating.

[0060] (2) Place the perovskite precursor liquid film together with the substrate on the hot plate inside the drying device, set the exhaust port of the solvent vapor of the drying device to be fully closed, maintain the airtightness inside the drying device, set the hot plate to heat up to 110°C, and when it reaches 110°C, monitor the change of air pressure inside the drying device until the pressure value reaches 120 kPa.

[0061] (3) When the pressure reaches 120 kPa, the temperature is gradually increased to 150℃ at a rate of 1℃ / min. During the process, the exhaust port is gradually opened and the exhaust speed is controlled so that the pressure is maintained at 120±3 kPa. The pressure inside the device is restored to normal pressure after the perovskite wet film drying is completed, and the perovskite dry film is obtained.

[0062] (4) The perovskite dry film was annealed at 150°C for 2 hours to complete the preparation of the perovskite thin film.

[0063] The fabrication of perovskite solar cells includes the following steps:

[0064] (1) Cut the FTO (tin fluoride oxide) conductive glass into 10cm×10cm pieces, and ultrasonically clean it for 10min in glass cleaner, deionized water and ethanol respectively. After drying the residual solvent on the surface, put it into the ultraviolet ozone generator for 15min.

[0065] (2) 5g urea, 100μL mercaptoacetic acid, 5mL concentrated hydrochloric acid (37wt%), and 1.096g stannous chloride dihydrate (SnCl2·2H2O) were sequentially added to 400mL of pure water to obtain SnO2 (tin dioxide) mother liquor. 20mL of the SnO2 mother liquor was added to 100mL of pure water and ultrasonically mixed to form a 0.002M SnO2 dilution. The surface-treated FTO (tin fluoride oxyfluoride) conductive glass was then placed in the SnO2 dilution and placed in a 90℃ oven for 3 hours. After hydrolysis, the glass was rinsed several times along the container wall with deionized water. When the water in the container became clear, the FTO conductive glass was placed face up in a box containing isopropanol and ultrasonically sonicated for another 5 minutes. It was then rinsed three more times with deionized water and dried on both sides with an air gun. Finally, it was annealed on a hot plate at 170℃ for 1 hour to obtain a dense electron transport layer.

[0066] (3) A perovskite thin film layer was prepared on the electron transport layer according to the preparation method of perovskite thin film in Example 1;

[0067] (4) Weigh 73 mg of Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene) powder, then add 18 μL of lithium salt solution (520 mg / mL, solvent: acetonitrile), 29 μL of cobalt salt solution (300 mg / mL, solvent: acetonitrile), 30 μL of TBP (tert-butylpyridine), and 1 mL of chlorobenzene to prepare a hole transport layer solution. Take 0.2 mL of the hole transport layer solution and coat it onto the surface of the perovskite film to form a hole transport layer.

[0068] (5) A gold electrode with a thickness of 80 nm was prepared on the hole transport layer by thermal evaporation to obtain a perovskite solar cell.

[0069] (6) In the above preparation process, the positive and negative electrodes of the perovskite solar cell are divided and connected in series and parallel by laser etching process.

[0070] The photoelectric conversion efficiency of the prepared perovskite solar cells was tested. During the test, a stainless steel ferrous metal sheet was used to control the incident light area to be 80 cm². 2 The irradiation conditions are standard solar irradiance conditions (100 mW / cm²). 2 ).

[0071] Testing showed that the 10 perovskite solar cells prepared in this embodiment had an average fill factor of 0.71 and a photoelectric conversion efficiency of 19.8%, and could maintain more than 90% of their initial efficiency after working continuously for 1000 hours under sunlight.

[0072] Figure 1 The image shows a scanning electron microscope (SEM) image of the cross-section of the perovskite solar cell prepared in Example 1. From top to bottom, it is divided into the perovskite thin film layer, the electron transport layer, and the substrate (FTO conductive glass). It can be seen that the perovskite thin film layer and the electron transport layer of the perovskite solar cell prepared in Example 1 are tightly bonded together.

[0073] Comparative Example 1

[0074] Comparative Example 1 illustrates the fabrication steps of a perovskite thin film and its corresponding perovskite solar cell.

[0075] The difference between Comparative Example 1 and Example 1 is that the drying condition of the perovskite wet film in step (2) of the preparation of the perovskite film in Comparative Example 1 is a vacuum at 110°C.

[0076] The method for preparing perovskite thin films includes the following steps:

[0077] (1) Weigh out 39 mg CsI (cesium iodide), 146.17 mg FAI (formamidine iodide), 357.28 mg PbI2 (lead iodide), 82.58 mg PbBr2 (lead bromide), and 20.4 mg MACl (methylammonium chloride), respectively, and dissolve them in 1 mL of DMF (N,N-dimethylformamide) to prepare CsI. 0.15 FA 0.85 PbI 2.55 Br 0.45 Perovskite precursor solution: The prepared perovskite precursor solution is applied to the substrate to form a perovskite precursor solution liquid film by slit coating.

[0078] (2) Place the perovskite precursor liquid film together with the substrate on the hot stage in the drying device. Set the exhaust port of the solvent vapor in the drying device to be fully sealed to maintain the airtightness inside the drying device. Set the hot stage to heat up to 110°C. Evacuate the drying device to 3Pa and maintain it for 10 minutes. The perovskite wet film is dried and the perovskite dry film is obtained. The pressure inside the device is restored to atmospheric pressure.

[0079] (3) The perovskite dry film was annealed at 150°C for 2 hours to complete the preparation of the perovskite thin film.

[0080] The fabrication of perovskite solar cells includes the following steps:

[0081] (1) Cut the FTO (tin fluoride oxide) conductive glass into 10cm×10cm pieces, and ultrasonically clean it for 10min in glass cleaner, deionized water and ethanol respectively. After drying the residual solvent on the surface, put it into the ultraviolet ozone generator for 15min.

[0082] (2) 5g urea, 100μL mercaptoacetic acid, 5mL concentrated hydrochloric acid (37wt%), and 1.096g stannous chloride dihydrate (SnCl2·2H2O) were sequentially added to 400mL of pure water to obtain SnO2 (tin dioxide) mother liquor. 20mL of the SnO2 mother liquor was added to 100mL of pure water and ultrasonically mixed to form a 0.002M SnO2 dilution. The surface-treated FTO (tin fluoride oxyfluoride) conductive glass was then placed in the SnO2 dilution and placed in a 90℃ oven for 3 hours. After hydrolysis, the glass was rinsed several times along the container wall with deionized water. When the water in the container became clear, the FTO conductive glass was placed face up in a box containing isopropanol and ultrasonically sonicated for another 5 minutes. It was then rinsed three more times with deionized water and dried on both sides with an air gun. Finally, it was annealed on a hot plate at 170℃ for 1 hour to obtain a dense electron transport layer.

[0083] (3) A perovskite thin film layer was prepared on the electron transport layer according to the preparation method of the perovskite thin film in Comparative Example 1.

[0084] (4) Weigh 73 mg of Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene) powder, then add 18 μL of lithium salt solution (520 mg / mL, solvent: acetonitrile), 29 μL of cobalt salt solution (300 mg / mL, solvent: acetonitrile), 30 μL of TBP (tert-butylpyridine), and 1 mL of chlorobenzene to prepare a hole transport layer solution. Take 0.2 mL of the hole transport layer solution and coat it onto the surface of the perovskite film to form a hole transport layer.

[0085] (5) A gold electrode with a thickness of 80 nm was prepared on the hole transport layer by thermal evaporation to obtain a perovskite solar cell.

[0086] (6) In the above preparation process, the positive and negative electrodes of the perovskite solar cell are divided and connected in series and parallel by laser etching process.

[0087] The photoelectric conversion efficiency of the prepared perovskite solar cells was tested. During the test, a stainless steel ferrous metal sheet was used to control the incident light area to be 80 cm². 2 The irradiation conditions are standard solar irradiance conditions (100 mW / cm²). 2 ).

[0088] Testing showed that the 10 perovskite solar cells prepared in this embodiment had an average fill factor of 0.66 and a photoelectric conversion efficiency of 17.4%, and could maintain more than 80% of their initial efficiency after working continuously for 1000 hours under sunlight.

[0089] Figure 2 The image shows a scanning electron microscope (SEM) image of the cross-section of the perovskite solar cell fabricated in Comparative Example 1. From top to bottom, it consists of the perovskite thin film layer, the electron transport layer, and the substrate (FTO conductive glass). It can be seen that a bottom void exists below the perovskite thin film layer in Comparative Example 1, at the junction of the perovskite thin film layer and the electron transport layer. This is because during the top-down curing process, some solvent remains at the bottom of the perovskite film, resulting in submicron-level voids at the buried interface during subsequent annealing.

[0090] Example 2

[0091] Example 2 describes the fabrication steps of a perovskite thin film and its corresponding perovskite solar cell.

[0092] Example 2 differs from Example 1 in that, in step (2) of the perovskite film preparation in Example 2, a gas atmosphere of a mixed solvent of DMF and ethanol is preset in the drying device before the perovskite precursor liquid film is placed inside the drying device. The rest of the process is the same as in Example 1.

[0093] The method for preparing perovskite thin films includes the following steps:

[0094] (1) Weigh out 39 mg CsI (cesium iodide), 146.17 mg FAI (formamidine iodide), 357.28 mg PbI2 (lead iodide), 82.58 mg PbBr2 (lead bromide), and 20.4 mg MACl (methylammonium chloride), respectively, and dissolve them in 1 mL of DMF (N,N-dimethylformamide) to prepare CsI. 0.15 FA 0.85 PbI 2.55 Br 0.45 Perovskite precursor solution: The prepared perovskite precursor solution is applied to the substrate to form a perovskite precursor solution liquid film by slit coating.

[0095] (2) Add DMF and ethanol solvent to the pre-set solvent tank of the drying device, heat to 60°C and open the exhaust port to form a gas atmosphere of DMF and ethanol mixed solvent in the drying device; place the perovskite precursor liquid film together with the substrate on the hot plate in the drying device, set the exhaust port of the solvent vapor of the drying device to be fully closed to maintain the airtightness of the drying device, set the hot plate to heat up to 110°C, and when it reaches 110°C, monitor the change of gas pressure in the drying device until the pressure value reaches 120 kPa.

[0096] (3) When the pressure reaches 120 kPa, the temperature is gradually increased to 150℃ at a rate of 1℃ / min. During the process, the exhaust port is gradually opened and the exhaust speed is controlled so that the pressure is maintained at 120±3 kPa. The pressure inside the device is restored to normal pressure after the perovskite wet film drying is completed, and the perovskite dry film is obtained.

[0097] (4) The perovskite dry film was annealed at 150°C for 2 hours to complete the preparation of the perovskite thin film.

[0098] The fabrication of perovskite solar cells includes the following steps:

[0099] (1) Cut the FTO (tin fluoride oxide) conductive glass into 10cm×10cm pieces, and ultrasonically clean it for 10min in glass cleaner, deionized water and ethanol respectively. After drying the residual solvent on the surface, put it into the ultraviolet ozone generator for 15min.

[0100] (2) 5g urea, 100μL mercaptoacetic acid, 5mL concentrated hydrochloric acid (37wt%), and 1.096g stannous chloride dihydrate (SnCl2·2H2O) were sequentially added to 400mL of pure water to obtain SnO2 (tin dioxide) mother liquor. 20mL of the SnO2 mother liquor was added to 100mL of pure water and ultrasonically mixed to form a 0.002M SnO2 dilution. The surface-treated FTO (tin fluoride oxyfluoride) conductive glass was then placed in the SnO2 dilution and placed in a 90℃ oven for 3 hours. After hydrolysis, the glass was rinsed several times along the container wall with deionized water. When the water in the container became clear, the FTO conductive glass was placed face up in a box containing isopropanol and ultrasonically sonicated for another 5 minutes. It was then rinsed three more times with deionized water and dried on both sides with an air gun. Finally, it was annealed on a hot plate at 170℃ for 1 hour to obtain a dense electron transport layer.

[0101] (3) A perovskite thin film layer was prepared on the electron transport layer according to the preparation method of perovskite thin film in Example 2;

[0102] (4) Weigh 73 mg of Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene) powder, then add 18 μL of lithium salt solution (520 mg / mL, solvent: acetonitrile), 29 μL of cobalt salt solution (300 mg / mL, solvent: acetonitrile), 30 μL of TBP (tert-butylpyridine), and 1 mL of chlorobenzene to prepare a hole transport layer solution. Take 0.2 mL of the hole transport layer solution and coat it onto the surface of the perovskite film to form a hole transport layer.

[0103] (5) A gold electrode with a thickness of 80 nm was prepared on the hole transport layer by thermal evaporation to obtain a perovskite solar cell.

[0104] (6) In the above preparation process, the positive and negative electrodes of the perovskite solar cell are divided and connected in series and parallel by laser etching process.

[0105] The photoelectric conversion efficiency of the prepared perovskite solar cells was tested. During the test, a stainless steel ferrous metal sheet was used to control the incident light area to be 80 cm². 2 The irradiation conditions are standard solar irradiance conditions (100 mW / cm²). 2 ).

[0106] Testing showed that the 10 perovskite solar cells prepared in this embodiment had an average fill factor of 0.73 and a photoelectric conversion efficiency of 20.4%, and could maintain more than 90% of their initial efficiency after working continuously for 1000 hours under sunlight.

[0107] Figure 3 This is a schematic diagram of the structure of the substrate placed in the drying device in Example 2. The drying device includes: a housing 100, a heating stage 200, an exhaust port 300 with controllable sealing degree, a digital barometer 400, a mercury thermometer 500, a solvent tank 600, and an electric heating wire 700 (atmosphere forming heating mechanism). The heating stage 200 is located at the bottom inside the housing 100 for heating the substrate, and the heating temperature of the heating stage can be set. The exhaust port 300 is installed on the housing 100 for controlling the airtightness of the housing 100. The digital barometer 400 and the mercury thermometer 500 are connected to the substrate and are used to detect the air pressure and air temperature inside the housing 100, respectively. The solvent tank 600 is located at the bottom inside the housing 100 for storing DMF and ethanol solvents. The electric heating wire 700 is connected to the solvent tank for heating the solvent tank 600 to form a gas atmosphere. In use, the substrate 800 is placed above the heating stage 200.

[0108] Example 3

[0109] Example 3 describes the fabrication steps of a perovskite thin film and its corresponding perovskite solar cell.

[0110] The difference between Example 3 and Example 2 is that in Example 3, in step (2) of the perovskite film preparation, a vacuum is first drawn before a mixed solvent atmosphere is formed. The rest of the process is the same as in Example 2.

[0111] The preparation of perovskite thin films includes the following steps:

[0112] (1) Weigh out 39 mg CsI (cesium iodide), 146.17 mg FAI (formamidine iodide), 357.28 mg PbI2 (lead iodide), 82.58 mg PbBr2 (lead bromide), and 20.4 mg MACl (methylammonium chloride) respectively, and dissolve them in 1 mL of DMF (N,N-dimethylformamide) to prepare CsI. 0.15 FA 0.85 PbI 2.55 Br 0.45 Perovskite precursor solution: The prepared perovskite precursor solution is applied to the substrate to form a perovskite precursor solution liquid film by slit coating.

[0113] (2) Add DMF and ethanol solvent to the atmosphere preset solvent tank of the drying device, set the exhaust port of the solvent vapor of the drying device to be fully closed, maintain the airtightness of the drying device, make the drying device reach a vacuum state through the exhaust mechanism, close the exhaust mechanism to keep DMF and ethanol at 25°C, and wait for the gas pressure to reach 101 kPa to form a gas atmosphere of DMF and ethanol mixed solvent in the drying device; place the perovskite precursor liquid film together with the substrate on the hot stage in the drying device, set the hot stage to heat up to 110°C, when it reaches 110°C, monitor the gas pressure change in the drying device until the pressure value reaches 120 kPa.

[0114] (3) When the pressure reaches 120 kPa, the temperature is gradually increased to 150℃ at a rate of 1℃ / min. During the process, the exhaust port is gradually opened and the exhaust speed is controlled so that the pressure is maintained at 120±3 kPa. The pressure inside the device is restored to normal pressure after the perovskite wet film drying is completed, and the perovskite dry film is obtained.

[0115] (4) The perovskite dry film was annealed at 150°C for 2 hours to complete the preparation of the perovskite thin film.

[0116] The fabrication of perovskite solar cells includes the following steps:

[0117] (1) Cut the FTO (tin fluoride oxide) conductive glass into 10cm×10cm pieces, and ultrasonically clean it for 10min in glass cleaner, deionized water and ethanol respectively. After drying the residual solvent on the surface, put it into the ultraviolet ozone generator for 15min.

[0118] (2) 5g urea, 100μL mercaptoacetic acid, 5mL concentrated hydrochloric acid (37wt%), and 1.096g stannous chloride dihydrate (SnCl2·2H2O) were sequentially added to 400mL of pure water to obtain SnO2 (tin dioxide) mother liquor. 20mL of the SnO2 mother liquor was added to 100mL of pure water and ultrasonically mixed to form a 0.002M SnO2 dilution. The surface-treated FTO (tin fluoride oxyfluoride) conductive glass was then placed in the SnO2 dilution and placed in a 90℃ oven for 3 hours. After hydrolysis, the glass was rinsed several times along the container wall with deionized water. When the water in the container became clear, the FTO conductive glass was placed face up in a box containing isopropanol and ultrasonically sonicated for another 5 minutes. It was then rinsed three more times with deionized water and dried on both sides with an air gun. Finally, it was annealed on a hot plate at 170℃ for 1 hour to obtain a dense electron transport layer.

[0119] (3) A perovskite thin film layer was prepared on the electron transport layer according to the preparation method of the perovskite thin film in Example 3;

[0120] (4) Weigh 73 mg of Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene) powder, then add 18 μL of lithium salt solution (520 mg / mL, solvent: acetonitrile), 29 μL of cobalt salt solution (300 mg / mL, solvent: acetonitrile), 30 μL of TBP (tert-butylpyridine), and 1 mL of chlorobenzene to prepare a hole transport layer solution. Take 0.2 mL of the hole transport layer solution and coat it onto the surface of the perovskite film to form a hole transport layer.

[0121] (5) A gold electrode with a thickness of 80 nm was prepared on the hole transport layer by thermal evaporation to obtain a perovskite solar cell.

[0122] (6) In the above preparation process, the positive and negative electrodes of the perovskite solar cell are divided and connected in series and parallel by laser etching process.

[0123] The photoelectric conversion efficiency of the prepared perovskite solar cells was tested. During the test, a stainless steel ferrous metal sheet was used to control the incident light area to be 80 cm². 2 The irradiation conditions are standard solar irradiance conditions (100 mW / cm²). 2 ).

[0124] Testing showed that the 10 perovskite solar cells prepared in this embodiment had an average fill factor of 0.75 and a photoelectric conversion efficiency of 20.8%, and could maintain more than 90% of their initial efficiency after working continuously for 1000 hours under sunlight.

[0125] Example 4

[0126] Example 4 describes the fabrication steps of a perovskite thin film and its corresponding perovskite solar cell, which differ from those in Example 1.

[0127] Example 4 differs from Example 1 in that: in Example 4, the preparation of a lead iodide seed layer is added before the perovskite film preparation step; the perovskite precursor solution is changed to a GBL (γ-butyrolactone) solvent system and lead iodide methylamine perovskite; the perovskite precursor solution film is formed on a substrate containing the seed layer; and the gas pressure and temperature are adjusted according to the different perovskite precursor solution systems. The remaining processes are the same as in Example 1.

[0128] The preparation of perovskite thin films includes the following steps:

[0129] (1) Weigh 750 mg of PbI2 (lead iodide) and dissolve it in 1 mL of DMF (N,N-dimethylformamide) and 160 μL of DMSO mixed solvent to prepare lead iodide solution and stir overnight at 70 °C. Coat the prepared lead iodide solution onto the substrate and heat and blow dry to form lead iodide seed crystal layer.

[0130] (2) Weigh 197.5 mg MAI (methyl iodide) and 573 mg PbI2 (lead iodide) respectively and dissolve them in 1 mL of GBL (γ-butyrolactone) to prepare MAPbI3 perovskite precursor solution. The prepared perovskite precursor solution is then applied to a substrate containing lead iodide seed crystal layer by slit coating to form a perovskite precursor solution liquid film.

[0131] (3) Place the perovskite precursor liquid film together with the substrate on the hot plate inside the drying device, set the exhaust port of the solvent vapor of the drying device to be fully closed, maintain the airtightness inside the drying device, set the hot plate to heat up to 60°C, when it reaches 60°C, monitor the change of air pressure inside the drying device until the pressure value reaches 110 kPa.

[0132] (4) When the pressure reaches 110 kPa, the temperature is gradually increased to 80℃ at a rate of 1℃ / min. During the process, the exhaust port is gradually opened and the exhaust speed is controlled so that the pressure is maintained at 110±3 kPa. The pressure inside the device is restored to normal pressure after the perovskite wet film is dried, and the perovskite dry film is obtained.

[0133] (5) The perovskite dry film was annealed at 80°C for 2 hours to complete the preparation of the perovskite thin film.

[0134] The fabrication of perovskite solar cells includes the following steps:

[0135] (1) Cut the FTO (tin fluoride oxide) conductive glass into 10cm×10cm pieces, and ultrasonically clean it for 10min in glass cleaner, deionized water and ethanol respectively. After drying the residual solvent on the surface, put it into the ultraviolet ozone generator for 15min.

[0136] (2) 5g urea, 100μL mercaptoacetic acid, 5mL concentrated hydrochloric acid (37wt%), and 1.096g stannous chloride dihydrate (SnCl2·2H2O) were sequentially added to 400mL of pure water to obtain SnO2 (tin dioxide) mother liquor. 20mL of the SnO2 mother liquor was added to 100mL of pure water and ultrasonically mixed to form a 0.002M SnO2 dilution. The surface-treated FTO (tin fluoride oxyfluoride) conductive glass was then placed in the SnO2 dilution and placed in a 90℃ oven for 3 hours. After hydrolysis, the glass was rinsed several times along the container wall with deionized water. When the water in the container became clear, the FTO conductive glass was placed face up in a box containing isopropanol and ultrasonically sonicated for another 5 minutes. It was then rinsed three more times with deionized water and dried on both sides with an air gun. Finally, it was annealed on a hot plate at 170℃ for 1 hour to obtain a dense electron transport layer.

[0137] (3) A perovskite thin film layer was prepared on the electron transport layer according to the preparation method of perovskite thin film in Example 4;

[0138] (4) Weigh 73 mg of Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene) powder, then add 18 μL of lithium salt solution (520 mg / mL, solvent: acetonitrile), 29 μL of cobalt salt solution (300 mg / mL, solvent: acetonitrile), 30 μL of TBP (tert-butylpyridine), and 1 mL of chlorobenzene to prepare a hole transport layer solution. Take 0.2 mL of the hole transport layer solution and coat it onto the surface of the perovskite film to form a hole transport layer.

[0139] (5) A gold electrode with a thickness of 80 nm was prepared on the hole transport layer by thermal evaporation to obtain a perovskite solar cell.

[0140] (6) In the above preparation process, the positive and negative electrodes of the perovskite solar cell are divided and connected in series and parallel by laser etching process.

[0141] The photoelectric conversion efficiency of the prepared perovskite solar cells was tested. During the test, a stainless steel ferrous metal sheet was used to control the incident light area to be 80 cm². 2 The irradiation conditions are standard solar irradiance conditions (100 mW / cm²). 2 ).

[0142] Testing showed that the 10 perovskite solar cells prepared in this embodiment had an average fill factor of 0.76 and a photoelectric conversion efficiency of 21.3%, and could maintain more than 95% of their initial efficiency after working continuously for 1000 hours under sunlight.

Claims

1. A method for preparing a perovskite thin film, characterized in that, Includes the following steps: Step (1): A perovskite precursor liquid film is formed on the substrate by the perovskite precursor liquid, wherein the perovskite precursor liquid includes a first solvent and a perovskite precursor material; the first solvent includes at least one of γ-butyrolactone, dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone. Step (2): In the container, a gas atmosphere is formed to maintain the airtightness of the container. The perovskite precursor liquid film is heated to raise the temperature to a first temperature, so that the internal gas pressure of the container rises to a preset gas pressure, which is 5-50 kPa greater than the external gas pressure of the container. The gas atmosphere includes at least one of an inorganic gas and the vapor of a second solvent; the inorganic gas includes at least one of nitrogen, oxygen, carbon dioxide, helium, neon, argon, krypton, xenon, and radon; the second solvent includes at least one of ethanol, isopropanol, chlorobenzene, toluene, ethyl acetate, petroleum ether, and chloroform; the first temperature is 55-115°C. Step (3): Change the airtightness of the container to maintain the preset air pressure, heat the perovskite precursor liquid film to raise the temperature to a second temperature and maintain it, dry it, and obtain a perovskite dry film; the second temperature is 75-300℃, and the preset air pressure is 105-150kPa. Step (4): Anneal the perovskite dry film to obtain the perovskite thin film; The perovskite precursor liquid film is dried under controllable temperature and vapor pressure to control the supersaturation of the perovskite wet film, thereby enabling the slow crystallization growth of the perovskite film from the substrate upwards.

2. The preparation method according to claim 1, characterized in that, In step (1), before forming the perovskite precursor liquid film, the step further includes: setting a seed crystal layer on the substrate, wherein the seed crystal layer includes lead iodide.

3. The preparation method according to claim 1, characterized in that, The container is a drying device, and the drying device includes: case; A heating mechanism is disposed at the bottom and / or side wall inside the housing for raising the temperature inside the housing; A barometer, connected to the housing, is used to monitor the air pressure inside the housing; An exhaust port, which can be controlled to change from fully closed to fully open, is provided on the housing to control the airtightness of the housing.

4. A perovskite thin film, characterized in that, The perovskite thin film is prepared by any one of the preparation methods described in claims 1-3.

5. A perovskite solar cell, characterized in that, The perovskite solar cell includes the perovskite thin film as described in claim 4.

6. An optoelectronic device, characterized in that, The optoelectronic device includes the perovskite thin film as described in claim 4.

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