A method for preparing CsPbI3 thin films

Abstract

The application provides application of methylammonium iodide in preparation of a black-phase CsPbI3 thin film. The application also provides a preparation method of the CsPbI3 thin film. By introducing methylammonium iodide into a perovskite precursor and combining a vacuum-assisted method, the application overcomes the disadvantage of rapid disorder of CsPbI3 crystallization, and realizes high-quality preparation of the black-phase CsPbI3 thin film at a low temperature.

Description

Technical Field

[0001] This invention belongs to the field of CsPbI3 thin film preparation technology, and relates to the application of methylammonium iodide in the preparation of black phase CsPbI3 thin films and a method for preparing CsPbI3 thin films, especially a method for preparing CsPbI3 thin films. Background Technology

[0002] Perovskite materials have distinguished themselves among numerous novel thin-film solar cell materials due to their superior photoelectric properties, becoming the most commercially promising optoelectronic material. Inorganic CsPbI3 perovskite materials, lacking organic components, exhibit excellent thermal stability. Furthermore, CsPbI3's band gap of approximately 1.7 eV makes it an ideal choice for the tandem layers in existing commercial crystalline silicon solar cells. However, the rapid and disordered crystallization process of CsPbI3 thin films results in a large number of voids and a high defect state density in commonly prepared CsPbI3 films. Additionally, the preparation temperature of black-phase CsPbI3 is typically high, leading to high energy consumption.

[0003] Therefore, how to prepare a high-quality CsPbI3 film, solve the above-mentioned problems of existing CsPbI3 films, and further broaden the application depth and width of CsPbI3 films has become one of the focuses of attention for many forward-looking researchers in this field. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing CsPbI3 thin films. The preparation method provided by the present invention introduces methylammonium iodide (MAI) into the perovskite precursor and combines it with a vacuum-assisted method to overcome the disadvantage of rapid and disordered crystallization of CsPbI3, and achieves high-quality preparation of black phase CsPbI3 thin films at low temperature. Moreover, the process is simple, the conditions are mild, the controllability is good, the operation is strong, and it is more suitable for industrial promotion and application.

[0005] This invention provides the application of methylammonium iodide in the preparation of black phase CsPbI3 thin films.

[0006] Preferably, the raw material used in the preparation includes PbI2;

[0007] The molar ratio of ammonium methyl iodide to PbI₂ is x:1, wherein 0.5 <x<1.5。

[0008] Preferably, the preparation specifically involves using methylammonium iodide in conjunction with vacuum conditions to prepare a black-phase CsPbI3 thin film;

[0009] The specific application is the use of methylammonium iodide in controlling the crystallization process of thin films.

[0010] Preferably, the preparation method includes a vacuum-assisted annealing process;

[0011] The black phase CsPbI3 film includes a γ phase CsPbI3 film.

[0012] Preferably, the application includes applications that reduce the annealing process temperature;

[0013] The annealing temperature is 100–180°C.

[0014] This invention also provides a method for preparing CsPbI3 thin films, comprising the following steps:

[0015] 1) After mixing CsI, PbI2, methylammonium iodide and solvent, a precursor solution is obtained;

[0016] 2) The precursor solution obtained in the above steps is composited on the substrate, kept under vacuum for a period of time, and then taken out for annealing to obtain a black phase CsPbI3 perovskite film.

[0017] Preferably, the molar ratio of CsI to PbI2 is 1:1;

[0018] The molar ratio of PbI2 to methylammonium iodide is 1:x, wherein 0.5 <x<1.5;

[0019] The solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0020] Preferably, the compounding method includes one or more of spin coating, spraying, and coating;

[0021] The thin film formed by the precursor solution on the substrate contains an intermediate phase formed by methyl ammonium iodide and PbI2.

[0022] Preferably, the holding time is specifically 0.5 to 2 minutes;

[0023] The pressure of the vacuum is 0.01 to 10 Pa.

[0024] Preferably, the annealing temperature is 100–180°C;

[0025] The annealing time is 5 to 30 minutes.

[0026] This invention provides the application of methylammonium iodide in the preparation of black-phase CsPbI3 thin films. Compared with the prior art, this invention addresses the aforementioned technical problems of existing CsPbI3 thin films by specifically using methylammonium iodide in the preparation process of black-phase CsPbI3 thin films, thereby achieving high-quality preparation of black-phase CsPbI3 thin films at low temperatures. This invention also provides a method for preparing CsPbI3 thin films by introducing methylammonium iodide (MAI) into the perovskite precursor, and more specifically by combining it with a vacuum-assisted method, overcoming the disadvantage of rapid and disordered crystallization of CsPbI3, and achieving high-quality preparation of black-phase CsPbI3 thin films at low temperatures.

[0027] This invention introduces MAI into the precursor, where it forms an intermediate phase with PbI2 during the preparation process. Simultaneously, a vacuum-assisted method is used to control the crystallization process of CsPbI3. During vacuum-assisted annealing, MAI volatilizes and is removed, allowing Cs to enter the crystal lattice, thus ultimately preparing a black-phase CsPbI3 perovskite thin film at temperatures below 180°C. This invention utilizes MAI and vacuum-assisted annealing to control the crystallization process, resulting in a simple, controllable, and highly reproducible preparation method suitable for industrial production. Furthermore, the annealing temperature of the film is below 180°C, effectively reducing energy consumption. Attached Figure Description

[0028] Figure 1 The X-ray diffraction pattern of the perovskite thin film prepared in Example 1 of this invention;

[0029] Figure 2 The X-ray diffraction pattern of the perovskite thin film prepared in Example 2 of this invention;

[0030] Figure 3 The X-ray diffraction pattern is shown for the perovskite thin film prepared in Comparative Example 1 of this invention. Detailed Implementation

[0031] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.

[0032] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0033] The purity of the raw materials used in this invention is not particularly limited. Preferably, the purity is analytical grade or conventional in the field of inorganic perovskite solar cell preparation.

[0034] All materials of the present invention, their grades and abbreviations are all conventional grades and abbreviations in the art. Each grade and abbreviation is clear and definite in the field of its related uses. Those skilled in the art can obtain them from the market or prepare them by conventional methods according to the grade, abbreviation and corresponding uses.

[0035] All processes of the present invention, their abbreviations are all conventional abbreviations in the art. Each abbreviation is clear and definite in the field of its related uses. Those skilled in the art can understand their conventional process steps according to the abbreviation.

[0036] The present invention provides the application of methylammonium iodide in the preparation of black-phase CsPbI3 thin films.

[0037] In the present invention, the raw materials for the preparation preferably include PbI2.

[0038] In the present invention, the molar ratio of methylammonium iodide to PbI2 is preferably x:1, where preferably 0.5 < x < 1.5, more preferably 0.7 ≤ x ≤ 1.3, and even more preferably 0.9 ≤ x ≤ 1.1.

[0039] In the present invention, the preparation is specifically preferably the combined application of methylammonium iodide and vacuum conditions to prepare black-phase CsPbI3 thin films.

[0040] In the present invention, the application is specifically preferably the application of methylammonium iodide in controlling the film crystallization process.

[0041] In the present invention, the preparation method preferably includes a vacuum-assisted annealing process.

[0042] In the present invention, the black-phase CsPbI3 thin film preferably includes a γ-phase CsPbI3 thin film.

[0043] In the present invention, the application preferably includes the application of reducing the annealing process temperature.

[0044] In the present invention, the temperature of the annealing is preferably 100 - 180 °C, more preferably 110 - 170 °C, even more preferably 120 - 160 °C, and even more preferably 130 - 150 °C.

[0045] The present invention provides a method for preparing a CsPbI3 thin film, comprising the following steps:

[0046] 1) Mix CsI, PbI2, methylammonium iodide and a solvent to obtain a precursor solution;

[0047] 2) Coating the precursor solution obtained in the above step on a substrate, keeping it under vacuum conditions for a period of time, and then taking it out for annealing to obtain a black-phase CsPbI3 perovskite thin film.

[0048] In the present invention, CsI, PbI2, methylammonium iodide and a solvent are first mixed to obtain a precursor solution.

[0049] In the present invention, the molar ratio of CsI to PbI2 is preferably 1:1.

[0050] In the present invention, the molar ratio of PbI2 to methylammonium iodide is preferably 1:x, where preferably 0.5 < x < 1.5, more preferably 0.7 < x < 1.3, and even more preferably 0.9 < x < 1.1.

[0051] In the present invention, the solvent is preferably one or more of N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone, and more preferably N,N-dimethylformamide, dimethyl sulfoxide or N-methylpyrrolidone.

[0052] Finally, the precursor solution obtained in the above steps is compounded on a substrate, kept under vacuum for a period of time, and then taken out for annealing to obtain a black-phase CsPbI3 perovskite film.

[0053] In the present invention, the compounding method preferably includes one or more of spin coating, spraying and coating, and more preferably spin coating, spraying or coating.

[0054] In the film formed by compounding the precursor solution on the substrate in the present invention, it preferably contains an intermediate phase formed by methylammonium iodide and PbI2.

[0055] In the present invention, the period of time for keeping is specifically preferably 0.5 - 2 min, more preferably 0.8 - 1.7 min, and even more preferably 1.1 - 1.4 min.

[0056] In the present invention, the pressure of the vacuum is preferably 0.01 - 10 Pa, more preferably 0.05 - 8 Pa, and even more preferably 0.1 - 5 Pa.

[0057] In the present invention, the annealing temperature is preferably 100 - 180 °C, more preferably 110 - 170 °C, even more preferably 120 - 160 °C, and even more preferably 130 - 150 °C.

[0058] In the present invention, the annealing time is preferably 5 - 30 min, more preferably 10 - 25 min, and even more preferably 15 - 20 min.

[0059] In the present invention, the annealing is preferably carried out in an air atmosphere. Specifically, the relative humidity of the air atmosphere is not higher than 40%.

[0060] This invention aims to complete and refine the overall technical solution, better ensure the operability and controllability of the preparation process, and further improve the performance of CsPbI3 thin films. The specific preparation method of the aforementioned CsPbI3 thin films may include the following steps:

[0061] The improved method for preparing CsPbI3 thin films according to this invention employs the following specific technical solution:

[0062] S1. Mix CsI, PbI2 and MAI, dissolve them in a solvent, and obtain precursor solution A;

[0063] S2. The precursor solution A is coated onto the substrate, and the coated substrate is annealed by vacuum-assisted annealing to remove the solvent and MAI, thereby obtaining a black phase CsPbI3 perovskite thin film.

[0064] Preferably, the molar ratio of CsI to PbI2 in S1 is 1:1.

[0065] Preferably, the molar ratio of PbI2 and MAI in S1 is 1:x, where 0.5 <x<1.5。

[0066] Preferably, the solvent in S1 is at least one of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0067] Preferably, the coating process in S2 is performed using any one of spin coating, spray coating, or application coating.

[0068] Preferably, in S2, the vacuum-assisted annealing involves a vacuuming time of 30s to 2min, an annealing temperature of 100 to 180℃, and an annealing time of 5 to 30min.

[0069] This invention introduces MAI into the precursor and combines it with a vacuum-assisted method to control the CsPbI3 crystallization process, thereby preparing a black-phase CsPbI3 perovskite thin film at temperatures below 180°C. The principle is that during the film formation process of the precursor solution on the substrate, MAI and PbI2 form an intermediate phase. During vacuum-assisted annealing, MAI evaporates and is removed, allowing Cs to enter the crystal lattice, ultimately resulting in a black-phase CsPbI3 thin film.

[0070] The present invention provides the application of methylammonium iodide in the preparation of black-phase CsPbI3 thin films and a method for preparing CsPbI3 thin films. Specifically, the present invention utilizes methylammonium iodide in the preparation of black-phase CsPbI3 thin films, thereby achieving high-quality preparation of black-phase CsPbI3 thin films at low temperatures. The present invention also provides a method for preparing CsPbI3 thin films by introducing methylammonium iodide (MAI) into the perovskite precursor, and more specifically by combining it with a vacuum-assisted method, overcoming the disadvantage of rapid and disordered crystallization of CsPbI3, and achieving high-quality preparation of black-phase CsPbI3 thin films at low temperatures.

[0071] This invention introduces MAI into the precursor, where it forms an intermediate phase with PbI2 during the preparation process. Simultaneously, a vacuum-assisted method is used to control the crystallization process of CsPbI3. During vacuum-assisted annealing, MAI volatilizes and is removed, allowing Cs to enter the crystal lattice, thus ultimately preparing a black-phase CsPbI3 perovskite thin film at temperatures below 180°C. This invention utilizes MAI and vacuum-assisted annealing to control the crystallization process, resulting in a simple, controllable, and highly reproducible preparation method suitable for industrial production. Furthermore, the annealing temperature of the film is below 180°C, effectively reducing energy consumption.

[0072] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, describes the application of methylammonium iodide provided by the present invention in the preparation of black phase CsPbI3 thin films and a method for preparing CsPbI3 thin films. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating procedures. They are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0073] Example 1

[0074] 0.8 mol CsI, 0.8 mol MAI, and 0.8 mol PbI₂ were dissolved in 1 mL LDM / NMP (V / V 9:1) to obtain a perovskite precursor solution. 50 μL of the perovskite precursor was dropped onto a 2 cm × 2 cm FTO substrate and spin-coated at 3000 rpm for 30 s. The substrate was then placed in a vacuum chamber, evacuated to a vacuum level, and held for 1 min before being removed. Annealing at 160 °C for 5 min yielded a perovskite thin film.

[0075] Example 2

[0076] This embodiment is basically the same as Example 1, except that the solvent is DMF.

[0077] Comparative Example 1

[0078] This comparative example is basically the same as Example 1, except that MAI was not added to the precursor.

[0079] Performance testing

[0080] The perovskite films prepared in the embodiments and comparative examples of this invention were characterized by X-ray diffraction, and the results are as follows: Figures 1-3 As shown.

[0081] in, Figure 1 The X-ray diffraction pattern is shown for the perovskite thin film prepared in Example 1 of this invention.

[0082] Figure 2 The X-ray diffraction pattern is shown for the perovskite thin film prepared in Example 2 of this invention.

[0083] Figure 3 The X-ray diffraction pattern is shown for the perovskite thin film prepared in Comparative Example 1 of this invention.

[0084] Depend on Figures 1-3 The comparison shows that the perovskite films prepared in Examples 1 and 2 have characteristic diffraction patterns of black phase CsPbI3, good crystallinity, and no impurity phases; while the perovskite film prepared in Comparative Example 1 has yellow phase CsPbI3.

[0085] The application of methylammonium iodide in the preparation of black-phase CsPbI3 thin films and a method for preparing CsPbI3 thin films provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention, including the best mode, and also to enable any person skilled in the art to practice this invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the textual description of the claims, or if they include equivalent structural elements that are not substantially different from the textual description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for preparing a CsPbI3 thin film, characterized in that, Includes the following steps: 1) A precursor solution is obtained by mixing CsI, PbI2, methylammonium iodide and solvent; The molar ratio of ammonium methyl iodide to PbI₂ is x:1, wherein 0.5 <x<1.5; 2) The precursor solution obtained in the above steps is composited on the substrate, kept under vacuum for a period of time, and then taken out for annealing to obtain a black phase CsPbI3 perovskite film. During the annealing process, the methyl ammonium iodide is volatilized and removed; The ammonium methyl iodide is used to control the thin film crystallization process; The thin film formed by the precursor solution on the substrate contains an intermediate phase formed by methyl ammonium iodide and PbI2.

2. The preparation method according to claim 1, characterized in that, The molar ratio of CsI to PbI2 is 1:

1.

3. The preparation method according to claim 1, characterized in that, The solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

4. The preparation method according to claim 1, characterized in that, The compounding method includes one or more of spin coating, spraying, and coating.

5. The preparation method according to claim 1, characterized in that, The specified holding time is 0.5 to 2 minutes.

6. The preparation method according to claim 1, characterized in that, The pressure of the vacuum is 0.01~10 Pa.

7. The preparation method according to claim 1, characterized in that, The annealing temperature is 100~180℃.

8. The preparation method according to claim 1, characterized in that, The annealing time is 5 to 30 minutes.

9. The preparation method according to claim 1, characterized in that, The black phase CsPbI3 film includes a γ phase CsPbI3 film.

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