Perovskite thin film, perovskite solar cell and preparation method thereof

Abstract

The invention discloses a perovskite thin film, a perovskite solar cell and a preparation method. The perovskite thin film is obtained by coating a perovskite precursor solution to obtain a perovskite wet film, then soaking the perovskite wet film into an anti-solvent containing a precursor substance to obtain a perovskite intermediate-state thin film, and finally soaking the perovskite intermediate-state thin film into a preheated anti-solvent for heat treatment. Component balance in the perovskite film can be effectively adjusted, defects are passivated, a more uniform and high-quality perovskite film can be obtained, and the efficiency of a perovskite solar cell is improved.

Description

Technical Field

[0001] This invention relates to the field of perovskites, and more specifically, to perovskite thin films for photovoltaic power generation, corresponding perovskite solar cells, and methods for their preparation. Background Technology

[0002] Solar energy, as an abundant, clean, and environmentally friendly renewable energy source, has broad application prospects in today's world where energy and environmental issues are increasingly serious. Perovskite solar cells, as a novel photovoltaic technology, have attracted widespread attention due to their advantages such as low cost, solution-based fabrication, simple processing, tunable bandgap, and flexibility. The core light-absorbing layer of perovskite solar cells is made of perovskite material, which, thanks to its superior photoelectric properties, has been used in photovoltaic devices for over a decade, resulting in significant progress in this field. Currently, the best-performing perovskite solar cells are mainly based on organic-inorganic hybrid perovskite materials. The crystal quality of the light-absorbing layer film formed by this material has a significant impact on the performance of the solar cell. How to prepare uniform, pore-free, high-quality perovskite films on substrates is a key technological challenge.

[0003] Current methods for obtaining perovskite thin films primarily involve first rapidly removing the solvent from the perovskite solution on the substrate surface after coating, forming a yellow to brownish-yellow mesophase. This mesophase film is then subjected to post-processing operations such as heating to obtain a crystalline perovskite film. However, existing methods, in the process of rapidly removing the solvent from the wet perovskite film, obtaining the intermediate-state film, and crystallizing it to form perovskite, may suffer from poor experimental repeatability, incomplete perovskite crystal conversion, and numerous internal defects, leading to reduced light energy conversion efficiency.

[0004] CN 117015249A provides a method for preparing perovskite thin films and batteries. In this method, diethyl ether is added dropwise as an antisolvent 5 to 7 seconds after the perovskite precursor liquid film has finished rotating, in order to remove the solvent and promote the crystallization of perovskite. However, this method has high requirements for time control, poor repeatability, and is difficult to scale up.

[0005] CN 116981319A provides a method for preparing perovskite thin films by immersion heating, which reduces the influence of environmental factors on perovskite film formation, but this method cannot effectively improve the defects of perovskite thin films. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a perovskite thin film and its preparation method, making it better suited for perovskite solar cells. The method involves immersing an intermediate-state perovskite thin film in an antisolvent containing a small amount of precursor material, then removing it. The antisolvent removes the solvent from the wet perovskite film, while the precursor material optimizes the film composition morphology, reduces defects, and yields a good perovskite mesophase thin film. Then, through heat treatment, a high-quality perovskite thin film is obtained. This invention improves the film formation quality of the perovskite thin film, thereby increasing the light conversion efficiency of the perovskite photovoltaic cell.

[0007] One objective of this invention is to provide a perovskite thin film, which is obtained by coating a perovskite precursor solution to obtain a wet perovskite film, immersing the wet perovskite film in an antisolvent containing the precursor substance to obtain a perovskite intermediate film, and finally immersing the perovskite intermediate film in a preheated antisolvent for heat treatment.

[0008] The perovskite precursor solution contains PbX2 and precursor substance AX.

[0009] In PbX2, X is an anion, preferably I. － ,Br － Cl － At least one of the following. PbX2 is preferably at least one of lead iodide, lead bromide or lead chloride.

[0010] The precursor substance is AX, where A is a cation, preferably formamidinium ion, methylamine ion, butylamine ion, phenylethylamine ion, or Cs. + At least one of the following; X is an anion, preferably I. － ,Br － Cl － At least one of the following. For example, the precursor substance may be at least one of butylamine hydroiodide (BAI), methylamine hydroiodide (MAI), formamidin hydroiodide (FAI), methylamine hydrochloride (MACl), and phenethylamine hydroiodide (PEAI).

[0011] The antisolvent is selected from at least one of isopropanol, diethyl ether, anisole, chlorobenzene, dichlorobenzene, trichlorobenzene, n-butanol, isobutanol, dichloromethane, and ethyl acetate, such as a combination of one or two of them.

[0012] The second objective of this invention is to provide a method for preparing a perovskite thin film, preferably the perovskite thin film described in the first objective of this invention, comprising coating a perovskite precursor solution to obtain a perovskite wet film, immersing the perovskite wet film in an antisolvent containing the precursor substance to obtain a perovskite intermediate film, and finally immersing the perovskite intermediate film in a preheated antisolvent for heat treatment.

[0013] Preferably, the preparation method includes the following steps:

[0014] (1) A perovskite wet film was obtained by coating a perovskite precursor solution containing PbX2 and AX.

[0015] (2) The perovskite wet film is immersed in an antisolvent containing AX to obtain a perovskite intermediate film;

[0016] (3) The perovskite intermediate film is immersed in a preheated antisolvent for heat treatment.

[0017] In step (1):

[0018] PbX2 is at least one of lead iodide, lead bromide, or lead chloride.

[0019] AX is the precursor substance, and A is the cation, preferably formamidinium ion, methylamine ion, butylamine ion, phenylethylamine ion, or Cs. + At least one of the following; X is an anion, preferably I. － ,Br － Cl － At least one of the following. For example, it can be at least one of butylamine iodide (BAI), methylamine hydroiodide (MAI), formamidin hydroiodide (FAI), methylamine hydrochloride (MACl), and phenethylamine hydroiodide (PEAI).

[0020] The solvent for the perovskite precursor solution is at least one of DMF and DMSO.

[0021] The steps for coating the perovskite precursor solution to obtain a perovskite wet film are not particularly limited. Common methods in the prior art can be used, or appropriate adjustments and selections can be made according to the actual requirements.

[0022] In step (2):

[0023] The antisolvent is selected from one or more of isopropanol, n-butanol, isobutanol, diethyl ether, anisole, chlorobenzene, dichlorobenzene, trichlorobenzene, dichloromethane, and ethyl acetate. For example, the antisolvent can be one of isopropanol, n-butanol, isobutanol, diethyl ether, anisole, chlorobenzene, dichlorobenzene, trichlorobenzene, dichloromethane, and ethyl acetate, or it can be isopropanol, n-butanol, or a mixture of isobutanol and other antisolvents.

[0024] The concentration of AX in the antisolvent is 0.1 to 10 mg / ml, for example, it can be 0.1 mg / ml, 0.5 mg / ml, 1 mg / ml, 2 mg / ml, 3 mg / ml, 4 mg / ml, 5 mg / ml, 6 mg / ml, 8 mg / ml, 9 mg / ml, 10 mg / ml, etc.

[0025] Soaking time is 1 to 5 seconds, for example, 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, etc.

[0026] In step (3):

[0027] The antisolvent is selected from one or more of isopropanol, n-butanol, isobutanol, diethyl ether, anisole, chlorobenzene, dichlorobenzene, trichlorobenzene, dichloromethane, and ethyl acetate.

[0028] The heat treatment temperature is 60 to 180°C, preferably 80 to 150°C, for example, 60°C, 80°C, 100°C, 120°C, 140°C, 150°C, 160°C, 180°C, etc.

[0029] The heat treatment time is 10 to 90 minutes, preferably 20 to 60 minutes, for example, 10 minutes, 20 minutes, 40 minutes, 60 minutes, 80 minutes, 90 minutes, etc.

[0030] The third objective of this invention is to provide a perovskite solar cell, comprising, in sequence: a transparent conductive substrate, a hole transport layer, a light-absorbing layer, an electron transport layer, a passivation layer, and a metal electrode layer, wherein the light-absorbing layer is the perovskite thin film described in the first objective of this invention or the perovskite thin film obtained by the preparation method described in the second objective of this invention.

[0031] In the perovskite solar cell of this invention, there are no particular limitations on the transparent conductive substrate, hole transport layer, electron transport layer, passivation layer, and metal electrode layer, which can be adjusted according to the actual requirements.

[0032] Preferably, the transparent conductive substrate is glass coated with a transparent metal oxide conductive film of ITO, FTO or AZO, or conductive PET.

[0033] Preferably, the hole transport layer is NiO. x Nanoparticle layer or PTAA organic hole transport layer or 4PACZ and its derivative monolayer.

[0034] Preferably, the electron transport layer is C 60 At least one of tin dioxide, PCBM, PBDB-T, and PM6.

[0035] Preferably, the passivation layer is a BCP layer.

[0036] Preferably, the metal electrode is at least one of gold, silver, and copper electrodes.

[0037] The fourth objective of this invention is to provide a method for preparing the perovskite solar cell described in the third aspect of this invention, including cleaning a transparent conductive substrate, spin-coating a hole transport layer, spin-coating a light-absorbing layer, depositing an electron transport layer, depositing a passivation layer, and depositing a metal electrode layer.

[0038] According to a preferred embodiment of the present invention, the method for fabricating the perovskite solar cell includes the following steps:

[0039] Step 1: Clean the transparent conductive substrate with a solvent and then dry it;

[0040] Step 2: Spin-coat the hole transport layer precursor solution onto a transparent conductive substrate, and anneal it to obtain the hole transport layer.

[0041] Step 3: Drop-coat the perovskite precursor solution onto the substrate on which the hole transport layer has been deposited, spin-coat to obtain a perovskite wet film, immerse the perovskite wet film in an antisolvent containing the precursor material to obtain a perovskite intermediate film, and finally immerse the perovskite intermediate film in a preheated antisolvent for heat treatment to obtain a perovskite light-absorbing layer.

[0042] Step 4: Deposit an electron transport layer on the light-absorbing layer;

[0043] Step 5: Evaporate the passivation layer;

[0044] Step 6: Evaporate the metal electrode layer.

[0045] In step one, the product is dried and then subjected to ultraviolet (UV) treatment.

[0046] In step two, the spin coating speed is 1000-6000 rpm; the annealing temperature is 100-180℃; and the annealing time is 10-40 minutes.

[0047] In step three, the spin coating speed is 1000-6000 rpm.

[0048] In step four, the electron transport layer is prepared using vacuum evaporation or solution deposition.

[0049] This invention provides a method for improving the quality of perovskite thin films and enhancing the efficiency of perovskite solar cells. The steps include depositing a hole transport layer, depositing a perovskite light-absorbing layer, immersing a wet perovskite film in an antisolvent containing an AX additive, removing it to obtain an intermediate phase film, immersing the intermediate phase film in a preheated antisolvent for heat treatment, removing it to obtain a perovskite thin film, and depositing an electron transport layer, a passivation layer, and a metal electrode layer on the perovskite thin film to obtain a high-performance perovskite solar cell. Compared with existing technologies, this invention uses an immersion method when treating the wet perovskite film with an antisolvent, and adds AX material as an additive to the antisolvent used for immersion. Then, during the heat treatment of the perovskite intermediate phase film, an immersion heating method is further used to obtain a crystalline perovskite thin film.

[0050] The present invention also has the following characteristics:

[0051] (1) The anti-solvent immersion method used in this invention to treat perovskite wet film to obtain the intermediate phase is more advantageous for large-area perovskite production than the traditional spin coating method of adding anti-solvent. Furthermore, the addition of AX additive to the immersion anti-solvent can effectively adjust the component balance in the perovskite film and passivate defects, resulting in fewer perovskite defects and higher efficiency of the obtained solar cell.

[0052] (2) The heat treatment method used in this invention is also the anti-solvent immersion method. Compared with the existing hot-stage heating annealing process, the solvent immersion method is heated more uniformly, avoiding uneven textures in the perovskite mesophase wet film obtained in the previous step due to different surface solvent evaporation rates, thereby obtaining a more uniform and high-quality perovskite film.

[0053] (3) The heat treatment method of anti-solvent immersion described in this invention can also effectively isolate the influence of external environmental factors such as water and oxygen on the perovskite crystallization film formation process, thereby improving the film formation quality of perovskite films and the efficiency of perovskite solar cells. Detailed Implementation

[0054] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0055] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0056] A preferred embodiment of the method for preparing perovskite thin films and corresponding solar cell films of the present invention includes the following steps:

[0057] A perovskite solar cell is obtained by sequentially depositing a hole transport layer, a perovskite thin film light-absorbing layer, an electron transport layer, a passivation layer, and a metal electrode layer on the surface of a transparent conductive substrate.

[0058] Furthermore, the transparent conductive substrate is glass or conductive PET coated with a transparent metal oxide conductive film of ITO, FTO, or AZO, and needs to be cleaned before use. A possible cleaning method is as follows: first clean the substrate with detergent and sonicate it for 15-30 minutes, then immerse the substrate in deionized water, acetone, ethanol, or isopropanol respectively, sonicate it for 15-30 minutes, and then dry it.

[0059] Furthermore, the substrate is surface-treated with UV for 15–30 minutes, and then a hole transport layer is deposited on it.

[0060] Furthermore, the hole transport layer is NiO. x The process of forming the hole transport layer preferably includes: a nanoparticle layer, a PTAA organic hole transport layer, or a monolayer of 4PACZ and its derivatives;

[0061] Hole transport layer solution was deposited on a transparent conductive substrate using a solution method, and the hole transport layer was obtained after annealing.

[0062] The hole transport layer is annealed at a temperature of 100℃ to 180℃ for a time of 10 min to 40 min.

[0063] Furthermore, the method for preparing the perovskite thin film light-absorbing layer includes the following steps:

[0064] Step 1: Dissolve the composition of precursor raw materials PbX2 and AX in a suitable solvent to obtain a perovskite precursor solution; wherein, in the composition of precursor raw materials AX and PbX2, A is formamidinium ion FA. + methylamine ion MA + Cesium ions (Cs) + , butylamine ion BA + Phenylethylamine ions (PEA) + A combination of one or more cations, where X is iodine I. － Br － chlorine Cl － At least one anion is present in the precursor solvent, which is at least one of DMF or DMSO.

[0065] In the perovskite precursor solution, the amounts of AX and PbX2 are the standard amounts, or may be adjusted according to actual requirements.

[0066] Step 2: Coat the perovskite precursor solution obtained in Step 1 onto the substrate that has been coated with a hole transport layer to obtain a perovskite wet film.

[0067] Step 3: Immerse the obtained perovskite wet film in an antisolvent containing AX raw material, quickly immerse for 1-5 seconds and then remove it to obtain a perovskite intermediate film.

[0068] Step 4: Immerse the obtained perovskite intermediate film in a preheated antisolvent for heat treatment to obtain the perovskite film. Preferably, the heat treatment temperature is 60℃~180℃ and the time is 10min~90min.

[0069] Furthermore, the antisolvent in step 3 is one or more of the following: isopropanol, diethyl ether, anisole, chlorobenzene, dichlorobenzene, trichlorobenzene, n-butanol, isobutanol, dichloromethane, and ethyl acetate.

[0070] Furthermore, the antisolvent in step 4 may be the same as or different from the antisolvent in step 3.

[0071] Furthermore, the electron transport layer is C 60 It is one of the following: tin dioxide, PCBM, PBDB-T, and PM6, prepared by vacuum evaporation or solution deposition.

[0072] Furthermore, a passivation layer is deposited on the aforementioned thin film.

[0073] Furthermore, the passivation layer is a BCP, prepared by vacuum evaporation or solution deposition.

[0074] Furthermore, a metal electrode is deposited on the aforementioned thin film.

[0075] Furthermore, the metal electrode is one of gold, silver, or copper electrodes, and is prepared by vacuum evaporation.

[0076] This invention provides a method for improving the quality of perovskite thin films and enhancing the efficiency of perovskite solar cells. Compared with existing technologies, this invention employs an immersion method when treating the wet perovskite film with an antisolvent, adding AX material as an additive to the antisolvent used for immersion. Then, during the heat treatment of the perovskite mesophase film, an immersion heating method is further used to obtain a crystalline perovskite thin film. The perovskite thin film obtained by this method has a more balanced composition, more uniform heating, is less affected by the external environment during the processing, has fewer film defects, and results in a more efficient perovskite solar cell.

[0077] To further illustrate the present invention, the following detailed description of the perovskite thin film preparation method and the corresponding perovskite solar cell preparation method is provided through specific embodiments and comparative examples.

[0078] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0079] Example 1

[0080] (1) Select FTO as a transparent conductive substrate. First, clean the substrate with detergent and sonicate it for 15-30 minutes. Then, immerse the substrate in deionized water, acetone, ethanol and isopropanol respectively and sonicate it for 15-30 minutes before drying.

[0081] (2) The substrate was treated with UV for 15-30 minutes. Then, 40 μL of PTAA solution was pipetted onto the FTO substrate. The spin coater was then started and the spin coater was used at 5000 rpm for 30 seconds. The resulting sample was then transferred to a hot plate and annealed at 110°C for 15 minutes to achieve the deposition of the hole transport layer.

[0082] (3) Prepare FA according to the proportion 0.75 MA 0.25 PbI 2.8 Cl 0.2 The perovskite solution was prepared by mixing DMF and DMSO in a volume ratio of 4:1, resulting in a concentration of 1.5 M. After thorough mixing at 50 °C, the solution was filtered to obtain a clear perovskite solution.

[0083] (4) The above perovskite solution is drop-coated onto the substrate on which the hole transport layer has been deposited, and then the spin coater is started and the perovskite wet film is obtained by spin coating at 4000 rpm for 15 seconds.

[0084] (5) Immerse the obtained perovskite wet film in the antisolvent for 3 seconds, and then quickly remove it to obtain a perovskite mesophase film. The antisolvent used is a chlorobenzene solution containing BAI (0.5 mg / ml) and isopropanol (10%).

[0085] (6) The obtained perovskite mesophase film is immersed in another chlorobenzene solution preheated to 110°C for heat treatment for 20 minutes, and then taken out and dried to obtain the perovskite film.

[0086] (7) Place the sample obtained above in a vacuum evaporation apparatus and sequentially deposit 20 nm of C. 60 A perovskite solar cell was obtained using an 8nm BCP and a 120nm silver electrode.

[0087] Example 2

[0088] (1) Select FTO as a transparent conductive substrate. First, clean the substrate with detergent and sonicate it for 15-30 minutes. Then, immerse the substrate in deionized water, acetone, ethanol and isopropanol respectively and sonicate it for 15-30 minutes before drying.

[0089] (2) The substrate was treated with UV for 15-30 minutes. Then, 40 μL of PTAA solution was pipetted onto the FTO substrate. The spin coater was then started and the spin coater was used at 5000 rpm for 30 seconds. The resulting sample was then transferred to a hot plate and annealed at 110°C for 15 minutes to achieve the deposition of the hole transport layer.

[0090] (3) Prepare FA according to the proportion 0.75 MA 0.25 PbI 2.8 Cl 0.2 The perovskite solution was prepared by mixing DMF and DMSO in a volume ratio of 4:1, resulting in a concentration of 1.5 M. After thorough mixing at 50 °C, the solution was filtered to obtain a clear perovskite solution.

[0091] (4) The above perovskite solution is drop-coated onto the substrate on which the hole transport layer has been deposited, and then the spin coater is started and the perovskite wet film is obtained by spin coating at 4000 rpm for 15 seconds.

[0092] (5) Immerse the obtained perovskite wet film in the antisolvent for 3 seconds, and then quickly remove it to obtain a perovskite mesophase film. The antisolvent used is an anisole solution containing BAI (0.5 mg / ml) and isobutanol (10%).

[0093] (6) The obtained perovskite mesophase film was immersed in an anisole solution preheated to 110°C for heat treatment for 20 minutes, and then removed and dried to obtain the perovskite film.

[0094] (7) The sample obtained above was placed in a vacuum evaporation apparatus and C60 of 20 nm, BCP of 8 nm and silver electrode of 120 nm were deposited in sequence to obtain perovskite solar cells.

[0095] Example 3

[0096] (1) Select FTO as a transparent conductive substrate. First, clean the substrate with detergent and sonicate it for 15-30 minutes. Then, immerse the substrate in deionized water, acetone, ethanol and isopropanol respectively and sonicate it for 15-30 minutes before drying.

[0097] (2) The substrate was treated with UV for 15-30 minutes. Then, 40 μL of PTAA solution was pipetted onto the FTO substrate. The spin coater was then started and the spin coater was used at 5000 rpm for 30 seconds. The resulting sample was then transferred to a hot plate and annealed at 110°C for 15 minutes to achieve the deposition of the hole transport layer.

[0098] (3) Prepare FA according to the proportion 0.75 MA 0.25 PbI 2.8 Cl 0.2 The perovskite solution was prepared by mixing DMF and DMSO in a volume ratio of 4:1, resulting in a concentration of 1.5 M. After thorough mixing at 50 °C, the solution was filtered to obtain a clear perovskite solution.

[0099] (4) The above perovskite solution is drop-coated onto the substrate on which the hole transport layer has been deposited, and then the spin coater is started and the perovskite wet film is obtained by spin coating at 4000 rpm for 15 seconds.

[0100] (5) Immerse the obtained perovskite wet film in the antisolvent for 3 seconds, and then quickly remove it to obtain a perovskite mesophase film. The antisolvent used is a chlorobenzene solution containing PEAI (0.5 mg / ml) and isopropanol (10%).

[0101] (6) The obtained perovskite mesophase film is immersed in another chlorobenzene solution preheated to 110°C for heat treatment for 20 minutes, and then taken out and dried to obtain the perovskite film.

[0102] (7) The sample obtained above was placed in a vacuum evaporation apparatus and C60 of 20 nm, BCP of 8 nm and silver electrode of 120 nm were deposited in sequence to obtain perovskite solar cells.

[0103] Example 4

[0104] (1) Select FTO as a transparent conductive substrate. First, clean the substrate with detergent and sonicate it for 15-30 minutes. Then, immerse the substrate in deionized water, acetone, ethanol and isopropanol respectively and sonicate it for 15-30 minutes before drying.

[0105] (2) The substrate was treated with UV for 15-30 minutes. Then, 40 μL of PTAA solution was pipetted onto the FTO substrate. The spin coater was then started and the spin coater was used at 5000 rpm for 30 seconds. The resulting sample was then transferred to a hot plate and annealed at 110°C for 15 minutes to achieve the deposition of the hole transport layer.

[0106] (3) Prepare FA according to the proportion 0.75 MA 0.25 PbI2.8 Cl 0.2 The perovskite solution was prepared by mixing DMF and DMSO in a volume ratio of 4:1, resulting in a concentration of 1.5 M. After thorough mixing at 50 °C, the solution was filtered to obtain a clear perovskite solution.

[0107] (4) The above perovskite solution is drop-coated onto the substrate on which the hole transport layer has been deposited, and then the spin coater is started and the perovskite wet film is obtained by spin coating at 4000 rpm for 15 seconds.

[0108] (5) Immerse the obtained perovskite wet film in the antisolvent for 3 seconds, and then quickly remove it to obtain a perovskite mesophase film. The antisolvent used is a n-butanol solution containing an appropriate amount of BAI (0.5 mg / ml).

[0109] (6) The obtained perovskite mesophase film is immersed in another n-butanol solvent preheated to 110°C for heat treatment for 20 minutes, and then taken out and dried to obtain the perovskite film.

[0110] (7) The sample obtained above was placed in a vacuum evaporation apparatus and C60 of 20 nm, BCP of 8 nm and silver electrode of 120 nm were deposited in sequence to obtain perovskite solar cells.

[0111] Comparative Example 1

[0112] (1) Select FTO as a transparent conductive substrate. First, clean the substrate with detergent and sonicate it for 15-30 minutes. Then, immerse the substrate in deionized water, acetone, ethanol and isopropanol respectively and sonicate it for 15-30 minutes before drying.

[0113] (2) The substrate was treated with UV for 15-30 minutes. Then, 40 μL of PTAA solution was pipetted onto the FTO substrate. The spin coater was then started and the spin coater was used at 5000 rpm for 30 seconds. The resulting sample was then transferred to a hot plate and annealed at 110°C for 15 minutes to achieve the deposition of the hole transport layer.

[0114] (3) Prepare FA according to the proportion 0.75 MA 0.25 PbI 2.8 Cl 0.2 The perovskite solution was prepared by mixing DMF and DMSO in a volume ratio of 4:1, resulting in a concentration of 1.5 M. After thorough mixing at 50 °C, the solution was filtered to obtain a clear perovskite solution.

[0115] (4) The above perovskite solution is drop-coated onto the substrate on which the hole transport layer has been deposited, and then the spin coater is started and the perovskite wet film is obtained by spin coating at 4000 rpm for 15 seconds.

[0116] (5) Immerse the obtained perovskite wet film in the antisolvent for 3 seconds, and then quickly remove it to obtain a perovskite mesophase film. The antisolvent used is chlorobenzene solution.

[0117] (6) The obtained perovskite mesophase film is transferred to a hot stage preheated to 110°C for heat treatment. The annealing time is 20 minutes to obtain the perovskite film.

[0118] (7) The sample obtained above was placed in a vacuum evaporation apparatus and C60 of 20 nm, BCP of 8 nm and silver electrode of 120 nm were deposited in sequence to obtain perovskite solar cells.

[0119] Comparative Example 2

[0120] (1) Select FTO as a transparent conductive substrate. First, clean the substrate with detergent and sonicate for 15-30 minutes. Then, immerse the substrate in deionized water, acetone, ethanol and isopropanol respectively and sonicate for 15-30 minutes before drying.

[0121] (2) The substrate was treated with UV for 15-30 minutes. Then, 40 μL of PTAA solution was pipetted onto the FTO substrate. The spin coater was then started and the spin coater was used at 5000 rpm for 30 seconds. The resulting sample was then transferred to a hot plate and annealed at 110°C for 15 minutes to achieve the deposition of the hole transport layer.

[0122] (3) Prepare FA according to the proportion 0.75 MA 0.25 PbI 2.8 Cl 0.2 The perovskite solution was prepared by mixing DMF and DMSO in a volume ratio of 4:1, resulting in a concentration of 1.5 M. After thorough mixing at 50 °C, the solution was filtered to obtain a clear perovskite solution.

[0123] (4) The above perovskite solution is drop-coated onto the substrate on which the hole transport layer has been deposited, and then the spin coater is started and the perovskite wet film is obtained by spin coating at 4000 rpm for 15 seconds.

[0124] (5) Immerse the obtained perovskite wet film in the antisolvent for 15 seconds, and then quickly remove it to obtain a perovskite mesophase film. The antisolvent used is a chlorobenzene solution containing BAI (0.5 mg / ml) and isopropanol (10%).

[0125] (6) The obtained perovskite mesophase film is transferred to a hot stage preheated to 110°C for heat treatment. The annealing time is 20 minutes to obtain the perovskite film.

[0126] (7) The sample obtained above was placed in a vacuum evaporation apparatus and C60 of 20 nm, BCP of 8 nm and silver electrode of 120 nm were deposited in sequence to obtain perovskite solar cells.

[0127] The perovskite solar cells obtained in the examples and the perovskite solar cells obtained in the comparative examples were placed under a solar simulator and their JV performance was compared with that of a standard sunlight. The comparison results are shown in Table 1 below.

[0128] Table 1. Performance test data of perovskite solar cells obtained from the examples and comparative examples.

[0129]

[0130] In Table 1, Examples 1, 2, and 3 are perovskite solar cells treated by immersion in anisole solution containing BAI and isobutanol, anisole solution containing BAI and isobutanol, chlorobenzene solution containing PEAI and isopropanol, and n-butanol solution containing BAI, respectively. Compared with devices that were directly immersed without BAI (Comparative Example 1) and Comparative Example 2, the perovskite thin film and its corresponding perovskite solar cell prepared by the method of the present invention have a higher fill factor, better photoelectric conversion efficiency, and superior performance compared with the comparative examples.

[0131] The above description is only a portion of preferred embodiments of the present invention and is not intended to limit the present invention. The technical methods described herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention should not be limited to the embodiments shown herein, and any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A perovskite thin film, obtained by coating a perovskite precursor solution to obtain a wet perovskite film, immersing the wet perovskite film in an antisolvent containing the precursor substance to obtain a perovskite intermediate film, and finally immersing the perovskite intermediate film in a preheated antisolvent for heat treatment.

2. The perovskite thin film according to claim 1, characterized in that: The perovskite precursor solution comprises PbX2 and precursor substance AX; and / or The precursor substance is AX, where A is a cation, preferably formamidinium ion, methylamine ion, butylamine ion, phenylethylamine ion, or Cs. + At least one of the following; X is an anion, preferably I. － ,Br － Cl － At least one of them.

3. A method for preparing a perovskite thin film, preferably used for preparing the perovskite thin film according to claim 1 or 2, comprising the following steps: (1) A perovskite wet film was obtained by coating a perovskite precursor solution containing PbX2 and AX. (2) The perovskite wet film is immersed in an antisolvent containing AX to obtain a perovskite intermediate film; (3) The perovskite intermediate film is immersed in a preheated antisolvent for heat treatment.

4. The method for preparing perovskite thin films according to claim 3, characterized in that... In step (2): The antisolvent is selected from at least one of isopropanol, diethyl ether, anisole, chlorobenzene, dichlorobenzene, trichlorobenzene, n-butanol, isobutanol, dichloromethane, or ethyl acetate; and / or, The concentration of AX in the antisolvent is 0.1–10 mg / ml; and / or, Soaking time is 1 to 5 seconds.

5. The method for preparing perovskite thin films according to claim 3, characterized in that... In step (3): The heat treatment temperature is 60–180°C, preferably 80–150°C; and / or, The heat treatment time is 10 to 90 minutes, preferably 20 to 60 minutes.

6. A perovskite solar cell, comprising, in sequence: The perovskite film comprises a transparent conductive substrate, a hole transport layer, a light-absorbing layer, an electron transport layer, a passivation layer, and a metal electrode layer, wherein the light-absorbing layer is a perovskite film as described in any one of claims 1 to 2 or a perovskite film obtained by the preparation method described in any one of claims 3 to 5.

7. The perovskite solar cell according to claim 6, characterized in that: The transparent conductive substrate is glass coated with a transparent metal oxide conductive film of ITO, FTO, or AZO, or conductive PET; and / or, The hole transport layer is NiO. x Nanoparticle layers or PTAA organic hole transport layers or 4PACZ and its derivative monolayers; and / or, The electron transport layer is C. 60 At least one of tin dioxide, PCBM, PBDB-T, and PM6; and / or, The passivation layer is a BCP layer; and / or, The metal electrode is at least one of gold, silver, and copper electrodes.

8. A method for preparing a perovskite solar cell according to any one of claims 6 to 7, comprising cleaning a transparent conductive substrate, spin-coating a hole transport layer, spin-coating a light-absorbing layer, depositing an electron transport layer, depositing a passivation layer, and depositing a metal electrode layer.

9. The method for preparing a perovskite solar cell according to claim 8, characterized in that... Includes the following steps: Step 1: Clean the transparent conductive substrate with a solvent and then dry it; Step 2: Spin-coat the hole transport layer precursor solution onto a transparent conductive substrate, and anneal it to obtain the hole transport layer. Step 3: Drop-coat the perovskite precursor solution onto the substrate on which the hole transport layer has been deposited, spin-coat to obtain a perovskite wet film, immerse the perovskite wet film in an antisolvent containing the precursor material to obtain a perovskite intermediate film, and finally immerse the perovskite intermediate film in a preheated antisolvent for heat treatment to obtain a perovskite light-absorbing layer. Step 4: Deposit an electron transport layer on the light-absorbing layer; Step 5: Evaporate the passivation layer; Step 6: Evaporate the metal electrode layer.

10. The method for preparing a perovskite solar cell according to claim 9, characterized in that: In step one, after drying, ultraviolet treatment is performed; and / or, In step two, the spin coating speed is 1000–6000 rpm; the annealing temperature is 100–180°C; and the annealing time is 10–40 minutes; and / or, In step three, the spin coating speed is 1000–6000 rpm; and / or, In step four, the electron transport layer is prepared using vacuum evaporation or solution deposition.

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