Perovskite thin film preparation method, perovskite thin film and perovskite solar cell

Abstract

The invention provides a perovskite thin film preparation method, a perovskite thin film and a perovskite solar cell. The method comprises the steps of obtaining a substrate for preparing the perovskite thin film; obtaining a perovskite precursor solution, wherein the perovskite precursor solution comprises a first monomer molecule containing sulfydryl and a second monomer molecule containing a carbon-carbon double bond; coating the perovskite precursor solution on the substrate and carrying out annealing treatment to form a perovskite thin film; and photo-initiating a click reaction between sulfydryl in the first monomer molecule and a carbon-carbon double bond in the second monomer molecule to construct a cross-linked polymer network in situ in the perovskite thin film. A first monomer molecule containing sulfydryl and a second monomer molecule containing a carbon-carbon double bond are introduced into a perovskite precursor solution, so that the problem that the doping amount is limited due to poor solubility of a polymer when the polymer is directly added is avoided.

Description

Technical Field

[0001] The present invention relates to the photovoltaic field, and in particular to a method for preparing a perovskite film, a perovskite film and a perovskite solar cell. Background Art

[0002] The non-radiative recombination of carriers, ion migration, and water-oxygen corrosion inside perovskite solar cell devices mainly occur at the grain boundaries of polycrystalline perovskite films, and grain boundaries become an important factor affecting device efficiency and stability. Introducing polymers into perovskite films can effectively inhibit non-radiative recombination and ion migration at grain boundaries, improving device efficiency and stability. The current technical solution for introducing polymer networks into perovskite films is to directly add polymers to the perovskite precursor solution, but the polymers in the perovskite films prepared by this method have poor solubility in the precursor solution, which results in a limited amount of additive doping, thereby affecting the mechanical properties and stability of the film. Summary of the invention

[0003] The embodiments of the present application provide a method for preparing a perovskite film, a perovskite film and a perovskite solar cell to solve the problem that the polymer in the perovskite film prepared by the existing method has poor solubility in the precursor solution, which leads to limited doping amount of additives, thereby affecting the mechanical properties and stability of the film.

[0004] In order to solve the above technical problems, this application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides a method for preparing a perovskite film, the method comprising:

[0006] obtaining a substrate for preparing a perovskite film;

[0007] Obtaining a perovskite precursor solution, wherein the perovskite precursor solution includes a first monomer molecule containing a thiol group and a second monomer molecule containing a carbon-carbon double bond;

[0008] coating the perovskite precursor solution on the substrate and performing annealing treatment to form a perovskite film;

[0009] A cross-linked polymer network is constructed in situ in the perovskite film by light-initiating a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule.

[0010] Optionally, the annealing treatment and the light-induced click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule are performed simultaneously.

[0011] Optionally, the perovskite film composition is ABX 3, wherein A is a mixture of cesium, formamidine and methylamine in any proportion, B is a mixture of Pb and Sn in any proportion, and C is a mixture of chlorine, bromine and iodine in any proportion.

[0012] Optionally, the photo-initiated click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule comprises:

[0013] The perovskite precursor solution is irradiated with a xenon lamp or an ultraviolet LED light source to induce a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule.

[0014] Optionally, obtaining a substrate for preparing a perovskite film comprises:

[0015] Obtaining a transparent conductive electrode and a tin dioxide solution, coating the tin dioxide solution on the transparent conductive electrode, and performing an annealing treatment to obtain the substrate, wherein the substrate is a tin dioxide electron transport layer;

[0016] The step of obtaining a perovskite precursor solution comprises:

[0017] Obtain lead iodide solution;

[0018] Preparing a blank solvent and a mixed solvent containing the first monomer molecule and the second monomer molecule;

[0019] The blank solvent and the mixed solvent are added to the lead iodide solution to obtain the perovskite precursor solution.

[0020] Optionally, the step of coating the perovskite precursor solution on the substrate and performing annealing to form a perovskite film comprises:

[0021] Spin coating the perovskite precursor solution on the surface of the substrate and performing annealing treatment to obtain a lead iodide film;

[0022] An organic salt solution is prepared and spin-coated on the lead iodide film, and an annealing treatment is performed to obtain the perovskite film.

[0023] Optionally, after in-situ constructing a cross-linked polymer network in the perovskite film by photoinitiating a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule, the method further comprises:

[0024] Dissolve the Spiro-OMeTAD powder in chlorobenzene, add tert-butylpyridine and lithium salt solution, stir and filter, and spin-coat the perovskite film surface;

[0025] An oxidation operation is performed to obtain a hole transport layer.

[0026] Optionally, after performing the oxidation operation to obtain the hole transport layer, the method further comprises:

[0027] An Au film is plated on the hole transport layer.

[0028] In a second aspect, an embodiment of the present application further provides a perovskite film, which is made according to the perovskite film preparation method as described above.

[0029] In a third aspect, an embodiment of the present application further provides a perovskite solar cell, which comprises a perovskite film prepared by any of the methods described above.

[0030] The present application implements a method for preparing a perovskite film, which includes obtaining a substrate for preparing a perovskite film; obtaining a perovskite precursor solution, wherein the perovskite precursor solution includes a first monomer molecule containing a thiol group and a second monomer molecule containing a carbon-carbon double bond; coating the perovskite precursor solution on the substrate and performing an annealing treatment to form a perovskite film; and in situ constructing a cross-linked polymer network in the perovskite film by light-initiating a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule. The method avoids the problem of limited doping amount due to poor polymer solubility when directly adding a polymer by introducing a first monomer molecule containing a thiol group and a second monomer molecule containing a carbon-carbon double bond into the perovskite precursor solution. Because small monomer molecules have better solubility in solution than polymers and can achieve higher doping levels, the perovskite precursor solution containing monomer molecules is coated on a substrate and annealed to form a perovskite film. Then, a photo-initiated thiol-carbon-carbon double bond click reaction is used to in situ construct a cross-linked polymer network in the perovskite film. Since the in situ cross-linking of the polymer network is carried out in the state of small monomer molecules, compared with large polymers, it reduces the hindrance to the diffusion of organic salts, which is beneficial to the uniform formation of perovskite and improves the quality of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] Figure 1 is a flow chart of a method for preparing a perovskite film provided in an embodiment of the present application;

[0033] Figure 2 is an operation process diagram of a method for preparing a perovskite thin film provided in one embodiment of the present application;

[0034] Figure 3 This is a schematic diagram of a photo-triggered click reaction between a thiol group and a carbon-carbon double bond provided in one embodiment of the present application. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] The present application provides a method for preparing a perovskite film. Figure 1 , Figure 1 is a flow chart of the method for preparing a perovskite film provided in an embodiment of the present application, such as Figure 1 As shown, the following steps are included:

[0037] Step 101, obtaining a substrate for preparing a perovskite film;

[0038] In this step, the above-mentioned substrate is the basic support structure for the preparation of the perovskite film, and its characteristics will affect the growth and performance of the perovskite film. The selection range of the substrate is relatively wide, and the embodiments of the present application are not specifically limited to this. For example, a transparent conductive electrode can be used as a substrate, and different types of transparent conductive glass can also be used, such as FTO (fluorine-doped tin oxide), ITO (indium tin oxide) glass, etc. The conductivity, light transmittance and surface properties of different materials are slightly different, which can be determined according to specific application scenarios and process requirements. In the process of obtaining the substrate, if there are impurities or unevenness on the surface of the substrate, it may affect the coating uniformity of the perovskite precursor solution and the film quality of the subsequent film. In some optional embodiments, the substrate can be cleaned, polished and other pre-treatment operations before use to ensure that the substrate surface is clean and flat.

[0039] Step 102, obtaining a perovskite precursor solution, wherein the perovskite precursor solution includes a first monomer molecule containing a thiol group and a second monomer molecule containing a carbon-carbon double bond;

[0040] In this step, obtaining the perovskite precursor solution is one of the key links in preparing the perovskite film. Among them, the first monomer molecule containing a thiol group (-SH) and the second monomer molecule containing a carbon-carbon double bond (-C=C-) are important raw materials for constructing an in-situ cross-linked polymer network. The embodiment of the present application does not limit the types of the first monomer molecule and the second monomer molecule. The first monomer molecule containing a thiol group can include all molecules containing -SH functional groups, and the second monomer molecule containing a carbon-carbon double bond can include all molecules containing -C=C- functional groups. For example, the monomer molecule containing a thiol group can be 3-mercaptopropionic acid or alkylthiol, etc., and the monomer molecule containing a carbon-carbon double bond can be an acrylate or styrene, etc. The specific selection of the first monomer molecule and the second monomer molecule needs to comprehensively consider its reaction activity, compatibility with the perovskite system, and the film performance that is ultimately desired to be achieved. The embodiment of the present application does not limit the concentration of the monomer molecules when configuring the solution. For example, the molar concentration of the two monomer molecules can be controlled between 0.01-0.1 mol / L. At the same time, the embodiment of the present application does not limit the choice of solvent. The solvent can be N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), etc., which can both dissolve the perovskite raw materials and ensure the dispersion and stability of the monomer molecules. When preparing the solution, it is necessary to determine the appropriate solvent ratio based on the solubility of the raw materials and the reaction requirements.

[0041] Step 103, coating the perovskite precursor solution on the substrate and performing annealing treatment to form a perovskite film;

[0042] In this step, the coating process can be performed by spin coating, scraping, spraying and other methods. Taking spin coating as an example, the perovskite precursor solution can be dropped on the center of the substrate, and the solution can be evenly spread on the surface of the substrate to form a thin film by high-speed rotation. The coated solution is tightly attached to the substrate, laying the foundation for the formation of a uniform perovskite film; the annealing treatment promotes the volatilization of the solvent in the precursor solution, promotes the growth and crystallization of perovskite crystals, and improves the quality and performance of the film. For example, when preparing a certain type of perovskite film, a rotation speed of 3000-5000 rpm can be selected, and the spin coating time can be 30-60 seconds.

[0043] The purpose of the above annealing is to promote the formation and growth of perovskite crystals, remove solvents and impurities, and improve the crystallization quality of the film. The embodiment of the present application does not specifically limit the annealing temperature and time. For example, for common perovskite systems, the annealing temperature can be controlled at 100-150°C, and the annealing time can be 20-60 minutes. In some optional embodiments, during the annealing process, it can be carried out under an inert gas (such as nitrogen, argon or helium) atmosphere to prevent the film from being oxidized or reacting with moisture in the air.

[0044] For example, PbI is spin-coated on the substrate surface. 2 The precursor solution was spin-coated at 1500 rpm for 45 s, and then transferred to a hot stage and annealed at 70°C for 10 s. Then, an organic salt solution (FAI:MAI:MACl=90 mg:6.4 mg:9 mg dissolved in 1 mL of isopropanol solution) was spin-coated on the lead iodide film at 2000 rpm for 30 s, and then transferred to an air glove box and annealed at ~30% RH and 105°C for 30 min to finally form a perovskite film.

[0045] In some optional embodiments, during the coating process, a multilayer coating method can be used, that is, a thin layer of precursor solution is first coated and preliminarily annealed, and then a second layer is coated, and so on. This method helps to form a more uniform and more crystalline perovskite film. Multilayer coating combined with annealing can effectively improve the microstructure of the film, reduce defects and holes in the film, and improve the coverage and uniformity of the perovskite film.

[0046] Step 104 : Initiating a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule by light to in-situ construct a cross-linked polymer network in the perovskite film.

[0047] In this step, the above-mentioned light initiation method can be irradiated by a xenon lamp or an ultraviolet LED lamp, etc. The specific light initiation method is not specifically limited in the present embodiment. The light source can provide light of a specific wavelength and intensity to stimulate the click reaction between the thiol group and the carbon-carbon double bond. Figure 3 The click reaction can form a cross-linked polymer network in situ inside the perovskite film. The cross-linked polymer network is a three-dimensional network structure formed by monomer molecules connected to each other through chemical bonds.

[0048] The above-mentioned "in-situ construction" refers to directly constructing a cross-linked polymer network in the system where the perovskite film is formed, without separating the perovskite film from the environment in which it is formed for additional operations. In this embodiment, the polymer network constructed in situ is formed in the same system as the perovskite film, and the interface between the two is tighter and more fused. Compared with pre-synthesizing the polymer and then adding it to the perovskite film, the polymer network formed in situ can better interweave and penetrate with the perovskite grains and tightly fill the grain boundaries.

[0049] The constructed cross-linked polymer network is filled in the grain boundaries of the perovskite film, which inhibits the non-radiative recombination and ion migration of carriers at the grain boundaries, thereby improving the electrical properties of the perovskite film; at the same time, the polymer network can also block the intrusion of water molecules and oxygen, improve the stability of the film, and extend its service life. This in-situ construction of a cross-linked polymer network avoids the problems of poor solubility, limited doping amount, and hindered diffusion of organic salts that exist in the traditional direct addition of polymers, and provides an effective method for preparing high-performance perovskite films.

[0050] For example, after annealing the perovskite film, 100 mW cm 2 The perovskite film was irradiated with a xenon lamp light source for 30 minutes to polymerize trimethylolpropane ester and ethoxyethyl acrylate to form a polymer.

[0051] In the method for preparing the perovskite film of the embodiment of the present application, by introducing a first monomer molecule containing a thiol group and a second monomer molecule containing a carbon-carbon double bond into the perovskite precursor solution, the problem of limited doping amount due to poor polymer solubility when directly adding a polymer is avoided. Because small monomer molecules have better solubility in solution than polymers, a higher doping amount can be achieved. The perovskite precursor solution containing monomer molecules is coated on a substrate and annealed to form a perovskite film, and then a photo-induced thiol-carbon-carbon double bond click reaction is used to in-situ construct a cross-linked polymer network in the perovskite film. Since the in-situ cross-linked polymer network is carried out in the state of small monomer molecules, compared with large polymers, it reduces the hindrance to the diffusion of organic salts, which is conducive to the uniform formation of perovskites and improves the quality of the film.

[0052] Optionally, the annealing treatment and the light-induced click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule are performed simultaneously.

[0053] In the method for preparing the perovskite film of the embodiment of the present application, the above-mentioned simultaneous operation can be understood as the annealing treatment and the light-induced click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule can be carried out simultaneously, but the time for the operation is not required to be completely overlapped, but partial time overlap is allowed. Annealing and the light-induced click reaction are made to occur simultaneously. On the one hand, annealing can promote the formation and growth of perovskite crystals and improve the crystallinity of the film; on the other hand, the light-induced click reaction can allow the monomer molecules to form a cross-linked polymer network in situ inside the perovskite film. Performing these two processes simultaneously can reduce the preparation steps and improve production efficiency; and a cross-linked polymer network is formed while the perovskite crystals grow, so that the two can better interact and fuse, and the network can be more tightly filled at the grain boundaries, more effectively suppressing the non-radiative recombination and ion migration of carriers at the grain boundaries, thereby improving the photoelectric conversion efficiency and stability of the device.

[0054] Of course, in the perovskite film preparation method of the embodiment of the present application, whether the annealing treatment and the photo-initiated click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule are carried out simultaneously does not affect the realization of the basic function of the perovskite film preparation method. Regardless of whether these two operations are carried out simultaneously or in steps, they can form a polymer network structure in the perovskite film that helps to improve performance with the help of the photo-initiated cross-linking reaction of the monomer molecules.

[0055] Optionally, the perovskite film composition is ABX 3 , wherein A is a mixture of cesium, formamidine and methylamine in any proportion, B is a mixture of Pb and Sn in any proportion, and C is a mixture of chlorine, bromine and iodine in any proportion.

[0056] In the method for preparing a perovskite film in an embodiment of the present application, the above-mentioned A-position elements include cesium (Cs), formamidine (FA) and methylamine (MA). These elements occupy the A position in the perovskite crystal structure, and their ionic radius and electronic structure are different, which will affect the lattice structure and stability of the perovskite crystal. The above-mentioned B-position elements are composed of lead (Pb) and tin (Sn). The B-position elements play a key role in the transmission and recombination process of photogenerated carriers in the crystal. Lead has good photoelectric properties and can effectively promote the generation and transmission of photogenerated carriers; tin can adjust the band gap width of perovskite, thereby changing the absorption range and photoelectric conversion efficiency of the film to light. The above-mentioned X-position elements include chlorine (Cl), bromine (Br) and iodine (I). The introduction of iodine can enhance the absorption of long-wavelength light, and bromine can adjust the band gap of the film, so that the absorption spectrum is more matched to the solar spectrum, and the utilization efficiency of light is improved.

[0057] In this implementation, by adjusting the ratio of A, B, and X elements, the energy band structure and light absorption characteristics of the film can be optimized to improve the photoelectric conversion efficiency; the stability of the crystal structure can be enhanced, ion migration and oxidation can be inhibited, and thermal and chemical stability can be improved; the film can also be customized according to different application scenarios, such as indoor low-light, high-temperature and other environments.

[0058] Of course, other trace elements can also be introduced for doping based on the basic elements at positions A, B, and X. For example, some alkali metal elements (such as potassium and sodium) can be doped at position A to fine-tune the electronic structure of the crystal; some transition metal elements (such as manganese and iron) can be doped at position B to change the carrier transport characteristics; some other halogen or pseudo-halogen elements (such as fluorine and thiocyanate) can be doped at position X, which does not affect the realization of the basic functions of the perovskite film preparation method of the embodiment of the present application.

[0059] Optionally, the photo-initiated click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule comprises:

[0060] The perovskite precursor solution is irradiated with a xenon lamp or an ultraviolet LED light source to induce a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule.

[0061] In the method for preparing the perovskite film of the embodiment of the present application, the purpose of using a xenon lamp or an ultraviolet LED light source for irradiation is to provide energy for the click reaction. When the light emitted by the light source irradiates the perovskite film, the first monomer molecule and the second monomer molecule therein absorb the light energy, the thiol group and the carbon-carbon double bond are excited, thereby causing a click reaction and in-situ constructing a cross-linked polymer network in the perovskite film.

[0062] The cross-linked polymer network formed by the photoinduced click reaction fills the grain boundaries, reduces the loss of carriers at the grain boundaries, enables more carriers to participate in conduction, thereby increasing the open circuit voltage, short circuit current and fill factor of the device, and ultimately improving the photoelectric conversion efficiency of the device.

[0063] In the embodiments of the present application, for the xenon lamp or the ultraviolet LED, the output light intensity, irradiation time, wavelength and irradiation angle are not specifically limited. In some optional embodiments, the xenon lamp and the ultraviolet LED light source can also be used in combination. For example, a xenon lamp can be used for a short-term pre-irradiation of 5-10 minutes, and its wide spectrum can be used to stimulate partial reactions, and then a ultraviolet LED light source can be used for subsequent irradiation, and its precise wavelength characteristics can be used to further promote the reaction to optimize the structure of the cross-linked polymer network. Alternatively, a xenon lamp and an ultraviolet LED light source can be used alternately in the same reaction process.

[0064] Of course, in other optional embodiments of the present application, other light sources may be used to trigger a click reaction, such as a mercury lamp, a metal halide lamp, or an excimer laser, etc. The embodiments of the present application do not specifically limit the specific form of light initiation.

[0065] Optionally, obtaining a substrate for preparing a perovskite film comprises:

[0066] Obtaining a transparent conductive electrode and a tin dioxide solution, coating the tin dioxide solution on the transparent conductive electrode, and performing an annealing treatment to obtain the substrate, wherein the substrate is a tin dioxide electron transport layer;

[0067] The step of obtaining a perovskite precursor solution comprises:

[0068] Obtain lead iodide solution;

[0069] Preparing a blank solvent and a mixed solvent containing the first monomer molecule and the second monomer molecule;

[0070] The blank solvent and the mixed solvent are added to the lead iodide solution to obtain the perovskite precursor solution.

[0071] In the method for preparing the perovskite thin film of the embodiment of the present application, the transparent conductive electrode is responsible for extracting the photogenerated carriers and allowing light to pass through to the perovskite thin film layer. The specific material of the transparent conductive electrode is not specifically limited in the embodiment of the present application, and indium tin oxide (ITO), fluorine-doped tin oxide (FTO), etc. can be used. The tin dioxide solution is composed of tin dioxide (SnO 2 ) is dispersed in a specific solvent to form a solution. Tin dioxide is an n-type semiconductor material and is a key component of the electron transport layer in perovskite solar cells. It has good electron transport properties and can efficiently collect and transport electrons generated by the perovskite film. The above-mentioned tin dioxide electron transport layer, located between the transparent conductive electrode and the perovskite film, can receive the electrons generated by the perovskite film under light, and quickly transmit the electrons to the transparent conductive electrode, and then output to the external circuit. At the same time, it can also block holes, reduce electron-hole recombination, and improve the photoelectric conversion efficiency of the battery.

[0072] The blank solvent can be understood as a solvent used to dissolve raw materials and adjust the composition of the solution, and does not contain monomer molecules involved in the construction of a cross-linked polymer network. For example, a blank solvent A of 20 mL DMF:DMSO = 9:1 (volume ratio) can be configured, where DMF (N, N-dimethylformamide) and DMSO (dimethyl sulfoxide) are commonly used organic solvents, which have good solubility and can dissolve raw materials such as lead iodide, while not affecting the formation of perovskite films and cross-linked polymer networks in the subsequent preparation process.

[0073] The above-mentioned mixed solvent is a solution formed by dissolving the first monomer molecule and the second monomer molecule in a blank solvent. The concentration and ratio of the monomer molecules in the mixed solvent are not specifically limited in the embodiments of the present application. For example, 15μLTPTMP (0.045mmol) and 15μLPAE (0.045mmol) can be taken to a mixed solvent of 3mL DMF:DMSO=9:1 (volume ratio) to obtain a solvent B containing 0.015mmol / mL of TPTMP and PAE (TPTMP:PAE=1:1). The above-mentioned lead iodide is a key component in the formation of perovskite crystals;

[0074] In this embodiment, the transparent conductive electrode provides a conductive path so that the photogenerated carriers can be smoothly extracted; the electron transport layer formed by coating the tin dioxide solution thereon and annealing can efficiently collect and transport electrons, block holes, and reduce recombination, providing a good foundation for the subsequent preparation of perovskite films. By preparing a high-quality tin dioxide electron transport layer, the photoelectric conversion efficiency of the battery can be effectively improved. Good electron transport performance can reduce the loss of electrons during the transmission process, increase the short-circuit current and open-circuit voltage of the battery, and thus improve the overall performance of the battery.

[0075] Of course, in other optional embodiments of the present application, other methods can be used to make the substrate, or other solvent systems can be used to make the perovskite precursor solution, as long as the perovskite precursor solution includes a first monomer molecule containing a thiol group and a second monomer molecule containing a carbon-carbon double bond. This is not specifically limited in the embodiments of the present application.

[0076] Optionally, the step of coating the perovskite precursor solution on the substrate and performing annealing to form a perovskite film comprises:

[0077] Spin coating the perovskite precursor solution on the surface of the substrate and performing annealing treatment to obtain a lead iodide film;

[0078] An organic salt solution is prepared and spin-coated on the lead iodide film, and an annealing treatment is performed to obtain the perovskite film.

[0079] In the method for preparing the perovskite film of the embodiment of the present application, the above-mentioned spin coating is a common method for uniformly coating the solution on the surface of the substrate. By rotating the substrate at high speed, centrifugal force is utilized to spread the solution on the surface of the substrate into a uniform film. For parameters such as the rotation speed and time of spin coating, the embodiment of the present application is not specifically limited. The above-mentioned organic salt solution can be understood as an organic salt dissolved in a specific solvent, such as isopropanol to form. The embodiment of the present application is also not limited to the specific type of organic salt, which can be FAI, MAI or MACl, etc.

[0080] Exemplarily, a perovskite precursor solution can be spin-coated on the surface of a substrate with a tin dioxide electron transport layer, and the solution is evenly distributed on the substrate by spin coating at 1500rpm for 45s. The coated sample is then annealed to obtain a lead iodide film. An organic salt solution (such as FAI:MAI:MACl=90mg:6.4mg:9mg dissolved in 1mL isopropanol solution) is then configured and spin-coated on the lead iodide film at 2000rpm for 30s, and finally annealed again (~30%RH, annealing at 105°C for 30min) to obtain a perovskite film. Of course, in the embodiments of the present application, the type, proportion and solvent of the organic salt are not specifically limited, and the type, proportion or solvent of the organic salt can be changed according to specific needs. For example, the ratio of FAI, MAI, and MACl can be increased or decreased, or other organic salts can be tried; the solvent can be replaced, such as replacing isopropanol with ethanol or other alcohol solvents.

[0081] In the preparation of perovskite film, organic salt solution reacts with lead iodide film to form perovskite crystal structure. Through the combination of spin coating and annealing, the crystal structure of perovskite film can be made more stable, ion migration and non-radiative recombination can be reduced, and perovskite film with high crystallinity and few defects can be prepared, carrier recombination can be reduced, and the short-circuit current, open-circuit voltage and fill factor of the battery can be improved, thereby improving the photoelectric conversion efficiency of the battery.

[0082] Of course, in other optional embodiments of the present application, in addition to spin coating, other coating methods such as spray coating and scraper coating may also be tried.

[0083] Optionally, after in-situ constructing a cross-linked polymer network in the perovskite film by photoinitiating a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule, the method further comprises:

[0084] Dissolve the Spiro-OMeTAD powder in chlorobenzene, add tert-butylpyridine and lithium salt solution, stir and filter, and spin-coat the perovskite film surface;

[0085] An oxidation operation is performed to obtain a hole transport layer.

[0086] In the perovskite film preparation method of the embodiment of the present application, the above-mentioned Spiro-OMeTAD powder: that is, 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene, is a commonly used hole transport material. It has a high hole mobility and good film-forming properties, can effectively transport holes in perovskite solar cells, reduce hole recombination, and improve the photoelectric conversion efficiency of the battery. The above-mentioned chlorobenzene, as a solvent, has appropriate volatility and can gradually evaporate during the spin coating process, so that Spiro-OMeTAD forms a uniform film on the surface of the perovskite film. The above-mentioned addition of tert-butylpyridine can improve the hole mobility of Spiro-OMeTAD. It can interact with Spiro-OMeTAD, optimize its electronic structure, and promote the transmission of holes in the material. The above-mentioned lithium salt solution can be used as a dopant to increase the conductivity of Spiro-OMeTAD and further improve the hole transport efficiency. The purpose of stirring is to make the Spiro-OMeTAD powder, tert-butylpyridine and lithium salt solution fully mixed in chlorobenzene, and filtering can remove impurities and undissolved particles in the solution to prevent these impurities from affecting the quality of the hole transport layer during the spin coating process and avoid forming defects in the hole transport layer, thereby ensuring the uniformity and integrity of the hole transport layer. The specific methods and tools used for the above stirring and filtering are not specifically limited in the embodiments of the present application.

[0087] The above oxidation operation can be understood as placing the perovskite film spin-coated with hole transport material in a specific environment for a period of time to cause the Spiro-OMeTAD to undergo an oxidation reaction. The hole mobility of the oxidized Spiro-OMeTAD will be further improved, thereby improving the performance of the hole transport layer. The specific environment for the oxidation operation is not specifically limited in the embodiments of the present application, and can be a moisture-proof cabinet or a mixed environment of a specific gas, or a dry atmosphere box, etc.

[0088] In this embodiment, the hole transport layer prepared by this series of operations can efficiently collect and transport holes generated by the perovskite film, reduce hole recombination, increase the open circuit voltage, short circuit current and fill factor of the battery, and thus improve the photoelectric conversion efficiency of the perovskite solar cell.

[0089] Of course, in other optional embodiments of the present application, other hole transport materials may be used instead of Spiro-OMeTAD, such as some new organic hole transport materials or inorganic hole transport materials; other additives may also be used to replace tert-butylpyridine and lithium salt solution. The use of different hole transport materials or additives will not affect the realization of the basic functions of the perovskite film preparation method in the embodiments of the present application.

[0090] Optionally, after performing the oxidation operation to obtain the hole transport layer, the method further comprises:

[0091] An Au film is plated on the hole transport layer.

[0092] In the perovskite film preparation method of the embodiment of the present application, Au is gold, which is a metal with stable chemical properties and good conductivity. Au film coating refers to covering a layer of gold film on the surface of the hole transport layer through a specific coating technology. In the perovskite solar cell, this layer of gold film serves as the electrode of the battery, responsible for collecting holes transmitted from the hole transport layer and exporting them to the external circuit to achieve current output of the battery.

[0093] In this embodiment, the Au film is used as an electrode to efficiently collect holes transmitted by the hole transport layer, providing a good conductive path for the battery, so that the current generated by the battery can be smoothly output to the external circuit, realizing the conversion of solar energy into electrical energy. At the same time, gold has high chemical stability and is not easily oxidized. It can maintain good conductivity during the long-term operation of the battery, ensuring the stability of the battery performance.

[0094] The vacuum degree, gold plating rate and coating thickness during the gold plating process are not specifically limited in the present embodiment. For example, the vacuum degree can be evacuated to less than 10 -4 Pa, then The gold plating rate is set to make gold atoms deposit on the surface of the hole transport layer to form an Au film with a thickness of about 80nm. Of course, higher vacuum degrees such as 10 -6 Pa, other gold plating rates can also be used, such as Alternatively, the coating thickness may be changed to, for example, 50-100 nm, to explore the thickness that is most suitable for improving battery performance. In some optional embodiments of the present application, other coating methods may also be used, such as magnetron sputtering coating, electron beam evaporation coating, and the like.

[0095] Of course, in some other optional embodiments of the present application, other materials may be selected as electrodes, such as silver (Ag), copper (Cu) or carbon materials (such as carbon nanotubes, graphene, etc.). The selection of different electrode materials does not affect the realization of the basic functions of the implementation methods of the present application.

[0096] In a second aspect, an embodiment of the present application further provides a perovskite film, which is made according to the perovskite film preparation method as described above.

[0097] In a third aspect, an embodiment of the present application further provides a perovskite solar cell, which comprises a perovskite film prepared by any of the methods described above.

[0098] The present application implements a method for preparing a perovskite film, which includes obtaining a substrate for preparing a perovskite film; obtaining a perovskite precursor solution, wherein the perovskite precursor solution includes a first monomer molecule containing a thiol group and a second monomer molecule containing a carbon-carbon double bond; coating the perovskite precursor solution on the substrate and performing an annealing treatment to form a perovskite film; and in situ constructing a cross-linked polymer network in the perovskite film by light-initiating a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule. The method avoids the problem of limited doping amount due to poor polymer solubility when directly adding a polymer by introducing a first monomer molecule containing a thiol group and a second monomer molecule containing a carbon-carbon double bond into the perovskite precursor solution. Because small monomer molecules have better solubility in solution than polymers and can achieve higher doping levels, the perovskite precursor solution containing monomer molecules is coated on a substrate and annealed to form a perovskite film. Then, a photo-initiated thiol-carbon-carbon double bond click reaction is used to in situ construct a cross-linked polymer network in the perovskite film. Since the in situ cross-linking of the polymer network is carried out in the state of small monomer molecules, compared with large polymers, it reduces the hindrance to the diffusion of organic salts, which is beneficial to the uniform formation of perovskite and improves the quality of the film.

[0099] In order to further illustrate the beneficial effects achieved by the method for preparing the perovskite film of the embodiment of the present application, experiments were conducted using the perovskite films prepared in Embodiment 1 and Embodiment 2 of the present application and a comparative perovskite film.

[0100] In the method for preparing the perovskite film of Example 1 of the present application, 5 g of SnCl 4 ·5H 2 O was dissolved in 40mL of ethylene glycol and stirred overnight. Then 10ml of the above solution was taken into a 100mL round-bottom flask, and 2mL of acetic acid and ammonia solution and 1mL of tetramethylammonium hydroxide solution were added respectively while stirring. After cooling to room temperature, the round-bottom flask was placed in an oil bath and heated at 150°C for 30min, then ethanol was added to disperse it, the supernatant was discarded after centrifugation, and the precipitate was dispersed in ethanol again. Centrifuge twice at 2500rpm (25min each time) and twice at 5000rpm (5min each time). Finally, the precipitate obtained by centrifugation was dispersed in about 30mL of ethanol to obtain SnO with a concentration of 12.5mg / mL. 2 Nanocrystalline solution.

[0101] SnO 2 The nanocrystal solution was spin-coated on a transparent conductive electrode at a speed of 2500 rpm for 30 s and annealed at 105 °C for 1.5 h to obtain SnO 2 Electron transport layer.

[0102] Prepare 20 mL of blank solvent A with DMF:DMSO=9:1 (volume ratio). Take 15 μL of TPTMP (0.045 mmol) and 15 μL of PAE (0.045 mmol) to 3 mL of a mixed solvent of DMF:DMSO=9:1 (volume ratio) to obtain solvent B (TPTMP:PAE=1:1) containing 0.015 mmol / mL of TPTMP and PAE.

[0103] CsFAMAPbI containing TP polymer 3 Preparation of perovskite film (TPTMP and PAE doping ratios are both 0.1%): Weigh 691.25 mg of PbI 2 (1.5mmol), 12.65mg CsCl (0.075mmol), 900μL blank solvent A and 100μL solvent B were added respectively to obtain PbI with TPTMP and PAE doping ratio of 0.1% (molar ratio) 2 Precursor solution. After stirring the solution for 2 h, it was filtered using a 0.22 μm polytetrafluoroethylene filter for later use. 2 Spin coating PbI on the surface of electron transport layer 2 Precursor solution, spin coated at 1500rpm for 45s. Then transfer to a hot stage and anneal at 70℃ for 10s. The organic salt solution (FAI:MAI:MACl=90mg:6.4mg:9mg dissolved in 1mL isopropanol solution) is spin coated on the lead iodide film at 2000rpm for 30s. The above process was completed in a nitrogen glove box. Then transfer to an air glove box and anneal for 30min at ~30% RH and 105℃. After the perovskite film is annealed, a xenon lamp light source (100mWcm-2) is used to irradiate the perovskite film from the front for 30min to polymerize TPTMP and PAE to form polymer TP.

[0104] Weigh 72.3 mg of Spiro-OMeTAD powder and dissolve it in 1 mL of chlorobenzene. Add 28.8 μL of 4-tert-butylpyridine and 17.5 μL of lithium salt solution (520 mg dissolved in 1 mL of acetonitrile) and stir overnight. After filtering with a 0.22 μm polytetrafluoroethylene filter, spin coat the perovskite film at 4000 rpm for 30 seconds. Store overnight in a moisture-proof cabinet to oxidize Spiro-OMeTAD and improve its hole mobility.

[0105] Evacuate to less than 10-4Pa, the gold plating rate The coating thickness is approximately 80nm.

[0106] In the method for preparing the perovskite film of Example 2 of the present application, the implementation process is basically the same as that of Example 1 of the present application, except that after the annealing of the perovskite film is completed, no xenon lamp irradiation is used.

[0107] The experimental process of the comparative example 1 in the above-mentioned comparative perovskite film is basically the same as that of the embodiment 1 of the present application, except that PbI 2 TPTMP and PAE were not added to the melt.

[0108] CfAMAP 3 Perovskite film preparation (PbI 2 TPTMP and PAE are not added to the melt): 691.25 mg PbI2 (1.5 mmol) and 12.65 mg CsCl (0.075 mmol) are weighed, and 1000 μL blank solvent A is added to obtain PbI2 with a TPTMP and PAE doping ratio of 1% (molar ratio) 2 Precursor solution. The subsequent process is the same as that of Example 1 of the present application.

[0109] The experimental process of the comparative example 2 in the above-mentioned comparative perovskite film is basically the same as that of the embodiment 1 of the present application, except that PbI 2 TPTMP and PAE are not added to the melt, and after the perovskite film is annealed, no xenon lamp irradiation is used.

[0110] CfAMAP 3 Preparation of perovskite film (TPTMP and PAE are not added to the PbI2 melt, and Xe lamp is not used for irradiation): 691.25 mg of PbI 2 (1.5mmol), 12.65mg of CsCl (0.075mmol), and 1000μL of blank solvent A were added to obtain PbI with a TPTMP and PAE doping ratio of 1% (molar ratio) 2 Precursor solution. The other processes are the same as those in Example 1 of the present application. After the perovskite film is annealed, the xenon lamp light source is not used to irradiate the perovskite film.

[0111] Table 1 is a performance comparison of the perovskite battery prepared in the examples of the present application and the comparative perovskite battery device used in the comparative example:

[0112] Table 1: Performance of perovskite battery devices in examples and comparative examples

[0113]

[0114] By comparing Example 1 with Comparative Example 1, it can be seen that by introducing TPTMP and PAE monomer molecules into the precursor solution and inducing the polymerization of TPTMP and PAE by irradiation with a xenon lamp after the perovskite film is annealed, the open circuit voltage and fill factor of the perovskite battery can be improved, and the device efficiency is increased from 20.85% to 24.1%.

[0115] By comparing Example 2 with Comparative Example 2, it can be seen that only by introducing TPTMP and PAE monomer molecules into the film without introducing light, the device performance is not significantly improved, indicating that the improvement in device performance in Example 1 is mainly due to the light-induced TPTMP and PAE click reaction to form an in-situ cross-linked polymer in the perovskite film.

[0116] Comparison of Comparative Example 2 with Comparative Example 1 shows that when the perovskite film without TPTMP and PAE is illuminated, the device performance is almost unchanged.

[0117] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0118] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0119] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A method for preparing a perovskite film, characterized in that: include: obtaining a substrate for preparing a perovskite film; Obtaining a perovskite precursor solution, wherein the perovskite precursor solution includes a first monomer molecule containing a thiol group and a second monomer molecule containing a carbon-carbon double bond; coating the perovskite precursor solution on the substrate and performing annealing treatment to form a perovskite film; A cross-linked polymer network is constructed in situ in the perovskite film by light-initiating a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule.

2. The method according to claim 1, characterized in that The annealing treatment is performed simultaneously with the light-induced click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule.

3. The method according to claim 1, characterized in that: The perovskite film composition is ABX3, wherein A is a mixture of cesium, formamidine and methylamine in any proportion, B is a mixture of Pb and Sn in any proportion, and C is a mixture of chlorine, bromine and iodine in any proportion.

4. The method according to claim 3, characterized in that: The photo-induced click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule comprises: The perovskite precursor solution is irradiated with a xenon lamp or an ultraviolet LED light source to induce a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule.

5. The method according to any one of claims 1 to 4, characterized in that The method of obtaining a substrate for preparing a perovskite film comprises: Obtaining a transparent conductive electrode and a tin dioxide solution, coating the tin dioxide solution on the transparent conductive electrode, and performing an annealing treatment to obtain the substrate, wherein the substrate is a tin dioxide electron transport layer; The step of obtaining a perovskite precursor solution comprises: Obtain lead iodide solution; Preparing a blank solvent and a mixed solvent containing the first monomer molecule and the second monomer molecule; The blank solvent and the mixed solvent are added to the lead iodide solution to obtain the perovskite precursor solution.

6. The method according to any one of claims 1 to 4, characterized in that The step of coating the perovskite precursor solution on the substrate and performing annealing treatment to form a perovskite film comprises: Spin coating the perovskite precursor solution on the surface of the substrate and performing annealing treatment to obtain a lead iodide film; An organic salt solution is prepared and spin-coated on the lead iodide film, and an annealing treatment is performed to obtain the perovskite film.

7. The method according to any one of claims 1 to 4, characterized in that After in-situ construction of a cross-linked polymer network in the perovskite film by initiating a click reaction between the thiol group in the first monomer molecule and the carbon-carbon double bond in the second monomer molecule through light, the method further comprises: Dissolve the Spiro-OMeTAD powder in chlorobenzene, add tert-butylpyridine and lithium salt solution, stir and filter, and spin-coat the perovskite film surface; An oxidation operation is performed to obtain a hole transport layer.

8. The method according to any one of claims 7, characterized in that After the oxidation operation is performed to obtain the hole transport layer, the method further comprises: An Au film is plated on the hole transport layer.

9. A perovskite film, characterized in that: The perovskite film is made according to the perovskite film preparation method according to any one of claims 1 to 8.

10. A perovskite solar cell, characterized in that: The perovskite solar cell comprises a perovskite film prepared by the method according to any one of claims 1 to 9.

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