A method for preparing a perovskite film by reducing the surface energy of PbI2 using aryl amidine hydrochloride, the perovskite film and application

Abstract

The application provides a method for preparing a perovskite film by reducing the surface energy of PbI2 by using aryl amidine hydrochloride, the perovskite film and application. The method comprises the following steps: preparing a PbI2 solution modified by aryl amidine hydrochloride and coating on the surface of a substrate, annealing to obtain a PbI2 film, then coating a cation solution on the surface of the PbI2 film, and annealing to obtain a perovskite film. By using 2-phenoxyethyl amidine hydrochloride, the surface energy of the PbI2 film is effectively reduced, and the PbI2 porous channel is successfully constructed, so that the cation solution can fully diffuse in the PbI2 film, the solid-liquid interface reaction between PbI2 and the cation is promoted, the problem of PbI2 residue is solved, and the high-quality preparation of the perovskite film is ensured. The perovskite solar cell device prepared by using the perovskite film has obviously improved open-circuit voltage, fill factor and photoelectric conversion efficiency, and has excellent photoelectric performance.

Description

Technical Field

[0001] This invention relates to the field of perovskite photovoltaic technology, and more particularly to a method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides, the perovskite thin films, and their applications. Background Technology

[0002] Since the study of the photovoltaic effect in the 19th century, the development of solar cells has progressed through silicon-based solar cells, copper indium gallium selenide (CIGS) solar cells, and third-generation solar cells. Among them, organic-inorganic hybrid perovskite solar cell devices (PVSCs) have attracted much attention in the photovoltaic energy field due to their excellent photoelectric performance. In the structure of PVSCs, the perovskite thin film, as the light-absorbing layer, plays a decisive role in the photoelectric performance due to its crystal quality and phase purity. In the fabrication process of perovskite thin films, the two-step sequential deposition method can effectively decouple the nucleation and crystal growth of perovskite, has good crystallization control capability, and can achieve precise control of the perovskite crystal growth process, thus having wide applications. Lead iodide (PbI2) is the most important precursor material for the two-step sequential deposition method of perovskite thin film preparation. If the lead iodide reaction is insufficient during the preparation process, a large amount of PbI2 residue will be present in the final perovskite thin film, which can easily lead to the degradation of the perovskite thin film and thus reduce the photoelectric conversion efficiency of PVSCs. To eliminate residual PbI2 in perovskite films, it is necessary to address the solid-liquid interface reaction between PbI2 and cations. For example, constructing porous PbI2 channels can confine the cation solution within a scaffold network, promoting the vertical growth of perovskite crystals and forming a cross-linked network at grain boundaries. This effectively releases mechanical stress and inhibits ion migration, improving the quality of the perovskite film. However, this approach still faces significant challenges: PbI2 films prepared by traditional methods have high surface energy. Directly coating a cation solution onto a high-surface-energy PbI2 film results in poor affinity for the cation solution, limiting the solid-liquid interface reaction between PbI2 and cations. This leads to anisotropic growth of the perovskite crystals, making it difficult to completely eliminate residual PbI2 and easily introducing additional grain boundary defects, thus hindering the improvement of PVSC photoelectric conversion efficiency.

[0003] Therefore, how to reduce the surface energy of PbI2 to promote the solid-liquid interface reaction between PbI2 and cations, eliminate residual PbI2, and thus prepare high-quality perovskite thin films has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] To address the issues of high surface energy of PbI2 films, insufficient solid-liquid interface reaction between PbI2 and cations, and degradation of perovskite films due to residual PbI2, this invention provides a method for preparing perovskite films by reducing the surface energy of PbI2 using arylamidine hydrochlorides, the perovskite films themselves, and their applications.

[0005] A first aspect of the present invention provides a method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides, comprising: A modified PbI2 solution was obtained by stirring a raw material system consisting of lead iodide and arylamidine hydrochloride. The modified PbI2 solution was coated on the substrate surface, and a PbI2 film was obtained after a first annealing treatment. A cationic solution was coated on the surface of the PbI2 film, followed by a second annealing treatment to obtain a perovskite film.

[0006] The method described above for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochloride is 2-phenoxyacetamidine hydrochloride.

[0007] In the method described above for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochloride, the molar ratio of lead iodide to arylamidine hydrochloride is 100:(2-4).

[0008] The method described above for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides further includes a first solvent in the raw material system, wherein the first solvent is at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP).

[0009] The method described above for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides, wherein the stirring process is carried out at a temperature of 40–80 °C for 2–8 h. And / or, the stirring process is carried out in nitrogen.

[0010] In the method described above for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides, the temperature in the first annealing treatment is 60–70 °C and the time is 10–300 s.

[0011] As described above, the method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides involves dissolving a cationic substance in a second solvent; the cationic substance is at least one of formamidine iodide, methylamine chloride, and methylamine iodide; and the second solvent is at least one of isopropanol, methanol, and ethanol. And / or, the concentration of the cation solution is 100–110 mg / mL.

[0012] In the method described above for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides, the second annealing treatment is performed at a temperature of 120–150 °C for 10–30 min. And / or, the second annealing treatment is performed under ambient humidity conditions of 20% ≤ RH ≤ 40%.

[0013] A second aspect of the present invention provides a perovskite thin film prepared by the method described above.

[0014] A third aspect of the present invention provides a perovskite solar cell device, including a perovskite light-absorbing layer, wherein the perovskite thin film is used as the perovskite light-absorbing layer.

[0015] The solution of the present invention has at least the following effects: This invention provides a method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides. By utilizing arylamidine hydrochlorides (such as 2-phenoxyacetamidine hydrochloride), the surface energy of the PbI2 film is reduced, while the resulting PbI2 film possesses porous channels. The reduced surface energy increases the affinity of the PbI2 film for cation solutions, allowing for sufficient diffusion of the cation solution within the PbI2 film and promoting the solid-liquid interface reaction between PbI2 and cations. Furthermore, the porous channels of the PbI2 film ensure sufficient reaction between PbI2 and cations, effectively preventing the presence of residual PbI2 in the perovskite film and significantly improving its crystallinity and crystal quality. In addition, the arylamidine hydrochloride's crystal plane control function allows PbI2 crystals to grow along the (001) crystal plane, thereby enabling perovskite crystals to grow along the (100) crystal plane, effectively enhancing the crystallinity of the perovskite film. The perovskite solar cell device fabricated using this perovskite thin film exhibits significantly improved open-circuit voltage (up to 1.19V), fill factor (up to 84.39%), and photoelectric conversion efficiency (up to 26.47%), demonstrating excellent photoelectric performance. This provides valuable insights for further improving the efficiency of perovskite solar cell devices and their large-area fabrication. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 The surface energy test results of the PbI2 thin films obtained in Example 1, Comparative Example 1, Comparative Example 4, and Comparative Example 7 of this invention; Figure 2 The XRD test results are for the PbI2 thin films obtained in Example 1, Comparative Example 1, Comparative Example 4, and Comparative Example 7 of this invention. Figure 3 The above are the SEM test results of the PbI2 films obtained in Example 1, Comparative Example 1, Comparative Example 4, and Comparative Example 7 of this invention. Figure 4 The XRD test results are for the perovskite films obtained in Example 2, Comparative Example 2, Comparative Example 5, and Comparative Example 8 of this invention. Figure 5 The SEM test results are of the perovskite films obtained in Example 2, Comparative Example 2, Comparative Example 5, and Comparative Example 8 of this invention. Figure 6 The perovskite solar cell devices obtained in Examples 3, 3, 6, and 9 of this invention are compared with standard silicon solar cells. JV Test results of the characteristic curve. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this art or in accordance with the product instructions. Reagents or instruments used without specified manufacturers are all conventional products that can be obtained commercially.

[0019] It should be noted that the use of terms such as "first" and "second" in this invention is for distinguishing similar objects and not for describing a specific order or sequence, and therefore should not be construed as a limitation of this invention.

[0020] In the following description, in this invention, "and / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. Here, A and B can be singular or plural; the symbol " / " means "or".

[0021] In the following description, the terms “including,” “containing,” “having,” and “containing” are open-ended terms, meaning that they include but are not limited to.

[0022] Those skilled in the art should understand that, in the following description of the embodiments of the present invention, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0023] Those skilled in the art will understand that the numerical ranges in the embodiments of the present invention should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, the technical / scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention pertains. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] A first aspect of the present invention provides a method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides, comprising: A modified PbI2 solution was obtained by stirring a raw material system consisting of lead iodide and arylamidine hydrochloride. The modified PbI2 solution was coated on the substrate surface, and a PbI2 film was obtained after a first annealing treatment. A cationic solution was coated on the surface of the PbI2 film, followed by a second annealing treatment to obtain a perovskite film.

[0026] The present invention does not specifically limit the coating method described above, and coating can be carried out by methods well known in the art, such as spin coating, scraping coating or spraying, etc., preferably spin coating.

[0027] The present invention does not impose any particular limitation on the specific material of the substrate, and the material can be selected according to actual needs.

[0028] In this invention, the substrate has a first surface and a second surface disposed opposite to each other. In this invention, either the first surface or the second surface of the substrate can be used as the substrate surface.

[0029] The present invention does not limit the shape, size, or thickness of the substrate; it can be selected according to actual needs.

[0030] The present invention does not limit the shape, size, or thickness of the PbI2 film; it can be selected according to actual needs.

[0031] This invention does not limit the shape, size, or thickness of the perovskite thin film; it can be selected according to actual needs.

[0032] Specifically, a raw material system comprising lead iodide (PbI2) and arylamidine hydrochloride is mixed to obtain a mixture solution. The mixture solution is stirred to fully disperse the components, resulting in a modified PbI2 solution. The modified PbI2 solution is uniformly coated onto the surface of a substrate. After a first annealing treatment, the solvent is removed and the PbI2 crystals preferentially grow along the (001) crystal plane to obtain a PbI2 thin film. Then, a cationic solution is uniformly coated onto the surface of the PbI2 thin film away from the substrate to allow the cationic solution to fully diffuse in the PbI2 thin film. After a second annealing treatment, the solvent is removed and the reaction between PbI2 and the cationic solution is fully carried out to obtain a perovskite thin film. The research of this invention shows that the obtained perovskite thin film is used to prepare perovskite solar cell devices, which exhibit significantly improved open-circuit voltage (up to 1.19V), fill factor (up to 84.39%), and photoelectric conversion efficiency (up to 26.47%), demonstrating excellent photoelectric performance.

[0033] The technical principle employed in this invention is explained as follows: By utilizing arylamidine hydrochlorides (such as 2-phenoxyacetamidine hydrochloride), the surface energy of the PbI2 film is reduced, while the resulting PbI2 film possesses porous channels. The reduced surface energy of the PbI2 film increases its affinity for cation solutions, allowing the cation solutions to diffuse fully within the film, promoting the solid-liquid interface reaction between PbI2 and cations. Furthermore, the porous channels of the PbI2 film ensure sufficient reaction between PbI2 and cations, effectively preventing the presence of residual PbI2 in the perovskite film and significantly improving its crystallinity and crystal quality. In addition, arylamidine hydrochlorides also have a crystal plane control effect, causing PbI2 crystals to grow along the (001) crystal plane, thereby enabling perovskite crystals to grow along the (100) crystal plane, effectively enhancing the crystallinity of the perovskite film.

[0034] In one specific embodiment, the arylamidine hydrochloride is 2-phenoxyacetamidine hydrochloride. When the above-mentioned arylamidine hydrochloride is 2-phenoxyacetamidine hydrochloride, it can effectively reduce the surface energy of the PbI2 film and improve the crystallinity of the PbI2 film. The reason for this may be that the 2-phenoxyacetamidine in the 2-phenoxyacetamidine hydrochloride is oriented and adsorbed on the PbI2 surface. During the preparation of the PbI2 film, the PbI2 crystal grows along the (001) crystal plane, which reduces the surface energy of PbI2 and improves the crystallinity of PbI2.

[0035] In one specific embodiment, to further reduce the surface energy of the PbI2 film, the molar ratio of lead iodide to the arylamidine hydrochloride is 100:(2-4), preferably 100:3. In one specific embodiment, the raw material system further includes a first solvent, which is at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP).

[0036] The present invention does not impose any particular limitation on the specific amount of the first solvent, as long as it can completely dissolve lead iodide and arylamidine hydrochloride.

[0037] In one specific embodiment, the stirring process is carried out at a temperature of 40–80 °C for 2–8 h.

[0038] In one specific embodiment, to avoid interference from ambient moisture on the mixture solution, the stirring process is carried out under nitrogen.

[0039] In one specific embodiment, the temperature in the first annealing process is 60–70 °C and the time is 10–300 s.

[0040] In one specific embodiment, the cationic solution is prepared by dissolving a cationic substance in a second solvent; the cationic substance is at least one of formamidine iodide (FAI), methylamine chloride (MACl), and methylamine iodide (MAI), and the second solvent is at least one of isopropanol, methanol, and ethanol.

[0041] In one specific embodiment, the second annealing process is carried out at a temperature of 120–150 °C for a time of 10–30 min.

[0042] In one specific embodiment, the second annealing treatment is carried out under conditions of ambient humidity of 20%≤RH≤40%.

[0043] A second aspect of the present invention provides a perovskite thin film prepared by the method described above.

[0044] A third aspect of the present invention provides a perovskite solar cell device, including a perovskite light-absorbing layer, wherein the perovskite thin film is used as the perovskite light-absorbing layer.

[0045] In one specific embodiment, the perovskite solar cell device further includes a conductive substrate, an electron transport layer, a hole transport layer, and a metal electrode; the conductive substrate, the electron transport layer, the perovskite light-absorbing layer, the hole transport layer, and the metal electrode are stacked sequentially.

[0046] In one specific embodiment, the hole transport layer is a 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD) layer, a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA) layer, a poly(triethylthiophenol) (P3HT) layer, and a nickel oxide (NiO) layer. x One of the layers.

[0047] This invention relates to Spiro-OMeTAD layers, PTAA layers, P3HT layers, and NiO. x The specific source of the layer is not particularly limited; it can be purchased directly from the market or prepared according to methods known in the art.

[0048] In one specific embodiment, the metal electrode is one of silver (Ag), gold (Au), and aluminum (Al).

[0049] The present invention does not impose any particular limitation on the specific source of the metal electrode, which can be purchased directly from the market or prepared according to methods known in the art.

[0050] The present invention will be further described below through specific embodiments.

[0051] In the examples below, the perovskite thin films are all prepared using a two-step sequential deposition method.

[0052] Example 1 (PhOAaCl, PbI2 thin film) This embodiment provides a method for preparing PbI2 thin films, including: (1) Pretreatment of the substrate: The 1.5 cm × 1.5 cm ITO transparent conductive substrate was ultrasonically cleaned with acetone, deionized water and isopropanol for 30 min respectively, then dried with nitrogen (N2) and placed in a plasma cleaner for 20 min of ozone plasma treatment to obtain the pretreated substrate.

[0053] (2) Preparation of modified PbI2 solution: 5.59 mg 2-phenoxyacetamidine hydrochloride (PhOAaCl) and 691.5 mg lead iodide (PbI2) were dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain modified PbI2 solution; The mixed solvent is obtained by mixing DMF and DMSO at a volume ratio of 95:5.

[0054] (3) Preparation of PbI2 thin film: 50 μL of the modified PbI2 solution in step (2) was uniformly spin-coated onto the surface of the pretreated substrate in step (1) by spin-coating deposition, and then annealed at 70 °C for 300 s to obtain PbI2 thin film (denoted as PbI2 thin film treated with PhOAaCl). The spin coating process involves a rotation speed of 1500 rpm and a time of 30 s.

[0055] The structural formula of 2-phenoxyacetamidine hydrochloride is as follows:

[0056] Example 2 (PhOAaCl, perovskite thin film) This embodiment provides a method for preparing perovskite thin films, including: (1) Pre-treatment of the substrate: Same as step (1) in Example 1.

[0057] (2) Preparation of modified PbI2 solution: Same as step (2) in Example 1.

[0058] (3) Preparation of cation solution: Dissolve 90 mg FAI, 9 mg MACl and 6.39 mg MAI in 1 mL isopropanol and stir at room temperature for 4 h in a glove box filled with nitrogen to obtain cation solution.

[0059] (4) Preparation of PbI2 thin film: Same as step (3) in Example 1.

[0060] (5) Preparation of perovskite film: 75 μL of the cation solution in step (3) was uniformly spin-coated onto the surface of the PbI2 film in step (4) by spin-coating deposition. Then, the film was placed on a hot table at 150 °C for annealing for 15 min under the condition of 20%≤RH≤40% humidity to obtain perovskite film (denoted as perovskite film treated with PhOAaCl). The spin coating process involves a rotation speed of 2000 rpm and a time of 30 s.

[0061] Example 3 (PhOAaCl, perovskite solar cell device) This embodiment provides a method for fabricating a perovskite solar cell device, including the following steps: (1) Pre-treatment of the substrate: Same as step (1) in Example 2.

[0062] (2) Preparation of modified PbI2 solution: Same as step (2) in Example 2.

[0063] (3) Preparation of cation solution: Same as step (3) in Example 2.

[0064] (4) Preparation of electron transport layer solution: Mix 15 wt% SnO2 colloidal solution and deionized water at a volume ratio of 1:3, place on a shaker and shake at room temperature for 5 h to obtain electron transport layer solution.

[0065] (5) Preparation of hole transport layer solution: 72.3 mg Spiro-OMeTAD (CAS No. 207739-728) was dissolved in 1 mL of chlorobenzene (CB), and then 28.8 μL of 4-tert-butylpyridine (TBP) and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) solution (520 mg Li-TFSI was dissolved in 1 mL of acetonitrile) were added sequentially. The mixture was stirred at room temperature for 4 h in a glove box filled with nitrogen to obtain hole transport layer solution.

[0066] (6) Preparation of electron transport layer: 65 μL of electron transport layer solution in step (4) is uniformly spin-coated onto the surface of the pretreated substrate in step (1) by spin-coating deposition, and then annealed at 150 °C for 300s to form an electron transport layer on the substrate surface. The spin coating process involves a rotation speed of 3000 rpm and a time of 30 s.

[0067] (7) Preparation of PbI2 thin film: 50 μL of the modified PbI2 solution in step (2) was uniformly spin-coated onto the surface of the electron transport layer in step (6) by spin-coating deposition, and then annealed at 70 °C for 300 s to obtain PbI2 thin film; The spin coating process involves a rotation speed of 1500 rpm and a time of 30 s.

[0068] (8) Preparation of perovskite light-absorbing layer: 75 μL of the cationic solution in step (3) was uniformly spin-coated onto the surface of the PbI2 film in step (7) by spin-coating deposition. Then, the film was placed on a hot table at 150°C for annealing for 15 min under the condition of ambient humidity of 20%≤RH≤40% to obtain a perovskite film. The perovskite film was used as the perovskite light-absorbing layer. The spin coating process involves a rotation speed of 2000 rpm and a time of 30 s.

[0069] (9) Preparation of hole transport layer: 65 μL of hole transport layer solution in step (5) is uniformly spin-coated onto the surface of perovskite light-absorbing layer in step (8) by spin-coating deposition to obtain hole transport layer (also known as Spiro-OMeTAD layer). The spin coating process involves a rotation speed of 4000 rpm and a time of 30 s.

[0070] (10) Evaporation of metal electrode: Silver (Ag) is deposited on the surface of hole transport layer by evaporation to obtain a metal electrode Ag with a thickness of 100 nm, thereby preparing a perovskite solar cell device. That is, the perovskite solar cell device is composed of an ITO transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer and a metal electrode Ag stacked in sequence.

[0071] Comparative Example 1 (without PhOAaCl, PbI2 film) The method for preparing PbI2 thin films provided in this comparative example is basically the same as that in Example 1, except that step (2) is not added: 2-phenoxyacetamidine hydrochloride (PhOAaCl) is not added. The specific steps of step (2) are as follows: 691.5 mg of lead iodide (PbI2) is dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain a PbI2 solution; wherein, the mixed solvent is obtained by mixing DMF and DMSO at a volume ratio of 95:5.

[0072] The PbI2 film obtained in this comparative example is referred to as the original PbI2 film.

[0073] Comparative Example 2 (Perovskite film without PhOAaCl) The method for preparing perovskite thin films provided in this comparative example is basically the same as that in Example 2, except that step (2) is not added: 2-phenoxyacetamidine hydrochloride (PhOAaCl) is not added. The specific steps of step (2) are as follows: 691.5 mg of lead iodide (PbI2) is dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain a PbI2 solution; wherein, the mixed solvent is obtained by mixing DMF and DMSO at a volume ratio of 95:5.

[0074] The perovskite film obtained in this comparative example is referred to as the original perovskite film.

[0075] Comparative Example 3 (without PhOAaCl, perovskite solar cell device) The preparation method of the perovskite solar cell device provided in this comparative example is basically the same as that in Example 3, except that step (2) is not added: 2-phenoxyacetamidine hydrochloride (PhOAaCl) is not added. The specific steps of step (2) are as follows: 691.5 mg of lead iodide (PbI2) is dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain a PbI2 solution; wherein, the mixed solvent is obtained by mixing DMF and DMSO at a volume ratio of 95:5.

[0076] Comparative Example 4 (MeOAaCl replaces PhOAaCl, PbI2 film) The method for preparing PbI2 thin films provided in this comparative example is basically the same as that in Example 1, except that in step (2): 5.59 mg of 2-phenoxyacetamidine hydrochloride (PhOAaCl) is replaced with 3.74 mg of methoxyacetamidine hydrochloride (MeOAaCl). The specific steps of step (2) are as follows: 3.74 mg of methoxyacetamidine hydrochloride (MeOAaCl) and 691.5 mg of lead iodide (PbI2) are dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain a modified PbI2 solution; wherein, the mixed solvent is obtained by mixing DMF and DMSO in a volume ratio of 95:5. The structural formula of methoxyacetamidine hydrochloride is as follows:

[0077] The PbI2 film obtained in this comparative example is denoted as the PbI2 film treated with MeOAaCl.

[0078] Comparative Example 5 (MeOAaCl replaces PhOAaCl, perovskite thin film) The method for preparing perovskite thin films provided in this comparative example is basically the same as that in Example 2, except that in step (2): 5.59 mg of 2-phenoxyacetamidine hydrochloride (PhOAaCl) is replaced with 3.74 mg of methoxyacetamidine hydrochloride (MeOAaCl). The specific steps of step (2) are as follows: 3.74 mg of methoxyacetamidine hydrochloride (MeOAaCl) and 691.5 mg of lead iodide (PbI2) are dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain a modified PbI2 solution; wherein, the mixed solvent is obtained by mixing DMF and DMSO at a volume ratio of 95:5.

[0079] The perovskite film obtained in this comparative example is referred to as the perovskite film treated with MeOAaCl.

[0080] Comparative Example 6 (MeOAaCl replaces PhOAaCl, perovskite solar cell device) The preparation method of the perovskite solar cell device provided in this comparative example is basically the same as that in Example 3, except that in step (2): 5.59 mg of 2-phenoxyacetamidine hydrochloride (PhOAaCl) is replaced with 3.74 mg of methoxyacetamidine hydrochloride (MeOAaCl). The specific steps of step (2) are as follows: 3.74 mg of methoxyacetamidine hydrochloride (MeOAaCl) and 691.5 mg of lead iodide (PbI2) are dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain a modified PbI2 solution; wherein, the mixed solvent is obtained by mixing DMF and DMSO at a volume ratio of 95:5.

[0081] Comparative Example 7 (PbI2 film with PhAaCl replacing PhOAaCl) The method for preparing PbI2 thin films provided in this comparative example is basically the same as that in Example 1, except that in step (2): 5.59 mg of 2-phenoxyacetamidine hydrochloride (PhOAaCl) is replaced with 5.12 mg of phenacetamidine hydrochloride (PhAaCl). The specific steps of step (2) are as follows: 5.12 mg of phenacetamidine hydrochloride (PhAaCl) and 691.5 mg of lead iodide (PbI2) are dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain a modified PbI2 solution; wherein, the mixed solvent is obtained by mixing DMF and DMSO in a volume ratio of 95:5. The structural formula of phenacetamidine hydrochloride is as follows:

[0082] The PbI2 film obtained in this comparative example is denoted as the PbI2 film treated with PhAaCl.

[0083] Comparative Example 8 (PhAaCl replaced PhOAaCl, perovskite thin film) The method for preparing perovskite thin films provided in this comparative example is basically the same as that in Example 2, except that in step (2): 5.59 mg of 2-phenoxyacetamidine hydrochloride (PhOAaCl) is replaced with 5.12 mg of phenacetamidine hydrochloride (PhAaCl). The specific steps of step (2) are as follows: 5.12 mg of phenacetamidine hydrochloride (PhAaCl) and 691.5 mg of lead iodide (PbI2) are dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain a modified PbI2 solution; wherein, the mixed solvent is obtained by mixing DMF and DMSO at a volume ratio of 95:5.

[0084] The perovskite film obtained in this comparative example is denoted as the PhAaCl-treated perovskite film.

[0085] Comparative Example 9 (PhAaCl replaces PhOAaCl, perovskite solar cell device) The preparation method of the perovskite solar cell device provided in this comparative example is basically the same as that in Example 3, except that in step (2): 5.59 mg of 2-phenoxyacetamidine hydrochloride (PhOAaCl) is replaced with 5.12 mg of phenoxyacetamidine hydrochloride (PhAaCl). The specific steps of step (2) are as follows: 5.12 mg of phenoxyacetamidine hydrochloride (PhAaCl) and 691.5 mg of lead iodide (PbI2) are dissolved in 1 mL of mixed solvent, and then placed in a glove box filled with nitrogen and stirred at 60 °C for 6 h to obtain a modified PbI2 solution; wherein, the mixed solvent is obtained by mixing DMF and DMSO at a volume ratio of 95:5.

[0086] Performance testing 1. Surface energy tests were performed on the PbI2 films obtained in Examples 1, 1, 4, and 7 of this invention. The surface energy was tested using the pendant drop method, where deionized water (H2O) and diiodomethane (DIM) were dropped onto the surface of the PbI2 film, respectively. The surface energy was then directly calculated using the contact angle values ​​of the two liquids. The results are as follows: Figure 1 As shown. Figure 1 The surface energy test results of the PbI2 thin films obtained in Examples 1, 1, 4 and 7 of this invention are presented to explore the superiority of PhOAaCl in reducing the surface energy of PbI2.

[0087] Depend on Figure 1It can be seen that, compared with the original PbI2 film (58.32 mN / m), the surface energy of the PbI2 film treated with PhOAaCl is significantly reduced to 53.16 mN / m, which is also significantly lower than that of the PbI2 film treated with MeOAaCl (57.42 mN / m) and the PbI2 film treated with PhAaCl (56.41 mN / m), demonstrating the excellent effect of PhOAaCl in reducing the surface energy of PbI2. Furthermore, the water contact angle of the PbI2 film treated with PhOAaCl was significantly larger than that of the original PbI2 film, the PbI2 film treated with MeOAaCl, and the PbI2 film treated with PhAaCl. This indicates that the hydrophobicity of the PbI2 film prepared using the PhOAaCl-modified PbI2 solution was significantly improved. This indirectly reflects the increased affinity of the PhOAaCl-treated PbI2 film for cation solutions, ensuring sufficient diffusion of cations in the PbI2 film and sufficient reaction at the solid-liquid interface between cations and PbI2. This effectively avoids the presence of residual PbI2 in the final perovskite film, which is beneficial to improving the photoelectric conversion efficiency and operational stability of perovskite solar cell devices.

[0088] 2. X-ray diffraction (XRD) tests were performed on the PbI2 thin films obtained in Examples 1, 1, 4, and 7 of this invention. The results are as follows: Figure 2 As shown. Figure 2 The XRD test results of the PbI2 films obtained in Examples 1, 1, 4, and 7 of this invention are shown to investigate the effect of PhOAaCl on the crystallinity of PbI2 films.

[0089] Depend on Figure 2 It can be seen that, compared with the original PbI2 film, the PbI2 film treated with MeOAaCl, and the PbI2 film treated with PhAaCl, the PbI2 film treated with PhOAaCl exhibits significantly enhanced diffraction peak intensity and narrower half-width at half-maximum (FWHM) at the 2θ=12.6° position (corresponding to the (001) crystal plane of PbI2). Furthermore, almost no diffraction peaks related to the (100) and (110) crystal planes were detected in the PbI2 film treated with PhOAaCl, indicating that PhOAaCl can effectively promote the growth of PbI2 crystals along the (001) crystal plane, and the PbI2 film treated with PhOAaCl has excellent crystallinity.

[0090] 3. The PbI2 films obtained in Examples 1, 1, 4, and 7 of this invention were tested using scanning electron microscopy (SEM). The results are as follows: Figure 3 As shown. Figure 3The SEM test results of the PbI2 films obtained in Examples 1, 1, 4, and 7 of this invention are shown to investigate the influence of PhOAaCl on the morphology and structure of the PbI2 films.

[0091] Depend on Figure 3 It is evident that the original PbI2 film surface exhibits a highly dense morphology, which hinders the subsequent penetration of cations into the PbI2 film interior. Compared with PbI2 films treated with MeOAaCl and PhAaCl, the PbI2 film treated with PhOAaCl exhibits a distinctly flat, sheet-like nanostructure and an expanded surface porous region (porous channels), indicating that the (001) crystal plane of PbI2 is dominant in the PbI2 film. Furthermore, the porous channels of the PhOAaCl-treated PbI2 film ensure sufficient solid-liquid interface reaction between PbI2 and cations, further preventing the presence of residual PbI2 in the final perovskite film.

[0092] 4. X-ray diffraction (XRD) tests were performed on the perovskite films obtained in Examples 2, 2, 5, and 8 of this invention. The results are as follows: Figure 4 As shown. Figure 4 The XRD test results of the perovskite films obtained in Examples 2, 2, 5, and 8 of this invention are shown to investigate the effect of PhOAaCl on the crystallinity of the perovskite films.

[0093] Depend on Figure 4 It can be seen that, compared with the original perovskite film, the perovskite film treated with MeOAaCl, and the perovskite film treated with PhAaCl, the perovskite film treated with PhOAaCl exhibits significantly enhanced diffraction peak intensity and narrower half-width at half-maximum (FWHM) at the 2θ=14° position (corresponding to the (100) crystal plane of the perovskite crystal). Furthermore, almost no diffraction peak related to PbI2 at the 2θ=12.6° position was detected in the perovskite film treated with PhOAaCl, while the perovskite films treated with MeOAaCl and PhAaCl contained lead iodide (PbI2), indicating that the perovskite film treated with PhOAaCl has superior crystallinity. These results indicate that the PbI2 film treated with PhOAaCl can effectively promote the full reaction between cations and PbI2, thereby avoiding the presence of residual PbI2 in the perovskite film and providing a guarantee for improving the photoelectric performance of perovskite solar cell devices.

[0094] 5. The perovskite films obtained in Examples 2, 2, 5, and 8 of this invention were tested using scanning electron microscopy (SEM), and the results are as follows: Figure 5 As shown. Figure 5The SEM test results of the perovskite films obtained in Examples 2, 2, 5, and 8 of this invention are presented to investigate the influence of PhOAaCl on the morphology and structure of the perovskite films.

[0095] Depend on Figure 5 It can be seen that the crystal quality of the original perovskite film is significantly lower than that of the perovskite films treated with PhOAaCl, MeOAaCl, and PhAaCl. The original perovskite film exhibits characteristics of incomplete conversion, namely, the presence of residual PbI2 and numerous pinholes. In contrast, the perovskite film treated with PhOAaCl has a more uniform morphology, larger grain size, smoother surface, and no residual PbI2, exhibiting excellent crystal quality. This is beneficial for good interfacial contact between the film and the hole transport layer (HTL), which is crucial for improving the photoelectric conversion efficiency of perovskite solar cell devices.

[0096] 6. The photoelectric performance of the perovskite solar cell devices obtained in Examples 3, 3, 6, and 9 of this invention was tested, and the results are as follows: Figure 6 As shown. Figure 6 The perovskite solar cell devices obtained in Examples 3, 3, 6, and 9 of this invention are compared with standard silicon solar cells. JV The test results of the characteristic curves were used to investigate the effect of PhOAaCl on the performance of perovskite solar cell devices. The detailed photoelectric performance parameters are summarized in Table 1.

[0097] Table 1 Test Results

[0098] from Figure 6 As shown in Table 1, the perovskite solar cell device prepared by PhOAaCl to reduce the surface energy of PbI2 achieves a photoelectric conversion efficiency of 26.47%, significantly higher than that obtained in Comparative Examples 3, 6, and 9. Compared with the perovskite solar cell devices obtained in Comparative Examples 3, 6, and 9, the perovskite solar cell device obtained in Example 3 also shows significantly improved open-circuit voltage (Voc=1.19 V) and fill factor (FF=84.39%). This indicates that the method of preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochloride (PhOAaCl) can effectively promote the solid-liquid interface reaction between the cation solution and PbI2, thereby improving the crystal quality and phase purity of the perovskite thin film and significantly enhancing the photoelectric performance of the perovskite solar cell device.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides, characterized in that, include: A modified PbI2 solution was obtained by stirring a raw material system consisting of lead iodide and arylamidine hydrochloride. The modified PbI2 solution was coated on the substrate surface, and a PbI2 film was obtained after a first annealing treatment. A cationic solution was coated on the surface of the PbI2 film, followed by a second annealing treatment to obtain a perovskite film.

2. The method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides according to claim 1, characterized in that, The aryl amidine hydrochloride is 2-phenoxyacetamine hydrochloride.

3. The method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides according to claim 1, characterized in that, The molar ratio of lead iodide to arylamidine hydrochloride is 100:(2-4).

4. The method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides according to claim 1, characterized in that, The raw material system also includes a first solvent, which is at least one of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

5. The method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides according to claim 1, characterized in that, During the stirring process, the temperature is 40–80 °C and the time is 2–8 h. And / or, the stirring process is carried out in nitrogen.

6. The method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides according to claim 1, characterized in that, In the first annealing process, the temperature is 60–70 °C and the time is 10–300 s.

7. The method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides according to claim 1, characterized in that, The cationic solution is prepared by dissolving a cationic substance in a second solvent; the cationic substance is at least one of formamidine iodide, methylamine chloride, and methylamine iodide, and the second solvent is at least one of isopropanol, methanol, and ethanol; And / or, the concentration of the cation solution is 100–110 mg / mL.

8. The method for preparing perovskite thin films by reducing the surface energy of PbI2 using arylamidine hydrochlorides according to claim 1, characterized in that, In the second annealing process, the temperature is 120–150 °C and the time is 10–30 min; And / or, the second annealing treatment is performed under ambient humidity conditions of 20% ≤ RH ≤ 40%.

9. A perovskite thin film, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. A perovskite solar cell device, comprising a perovskite light-absorbing layer, characterized in that, The perovskite film according to claim 9 is used as the perovskite light-absorbing layer.

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