Perovskite thin film, perovskite solar cell and preparation method thereof

Abstract

The application discloses a perovskite thin film, a perovskite solar cell and a preparation method thereof. The preparation method of the perovskite thin film comprises the following steps: providing a perovskite precursor solution, wherein the perovskite precursor solution comprises a perovskite precursor, a solvent and a cross-linking agent; coating the perovskite precursor solution on a substrate, removing at least part of the solvent to form a perovskite thin film precursor; preheating the perovskite thin film precursor to 80-120 DEG C; annealing the preheated perovskite thin film precursor to 300-400 DEG C, and the annealing time is 5-15 s, so as to form a perovskite thin film on the substrate. The prepared perovskite thin film effectively improves the crystallinity of the perovskite, reduces the grain boundary, and thus improves the efficiency and stability of the perovskite solar cell; and the preparation method can effectively shorten the preparation time of the perovskite thin film, and greatly improves the production efficiency.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a perovskite thin film, a perovskite solar cell, and a method for preparing the same. Background Technology

[0002] In recent years, with the continuous deepening of research, perovskite solar cells have made rapid progress, with efficiency increasing from the initial 3.8% to over 25%, and are hailed as "new hope in the photovoltaic field".

[0003] The crystallinity of perovskite has always been a key factor affecting device efficiency. Poor crystallinity and excessively small grain size in perovskite lead to numerous grain boundaries, resulting in various defects such as dislocations, impurities, and vacancies formed by broken chemical bonds. These defects negatively impact the efficiency and stability of perovskite solar cells. Therefore, improving the crystallinity of perovskite crystals and reducing grain boundaries is an effective strategy for improving cell efficiency and stability.

[0004] The commonly used annealing temperature for perovskites is generally between 100-200℃. This results in perovskite grains that are small, have poor crystallinity, and generate excessive grain boundaries, leading to numerous defects and affecting the efficiency and stability of solar cells. Using conventional annealing methods in production would consume excessive preparation time, impacting production efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a perovskite thin film, a perovskite solar cell, and a method for preparing the same, thereby improving the crystallinity of perovskite, reducing grain boundaries, and thus improving the efficiency and stability of perovskite solar cells, while effectively shortening the preparation time of the perovskite thin film and increasing production efficiency.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] In a first aspect, the present invention provides a method for preparing a perovskite thin film, comprising:

[0008] A perovskite precursor solution is provided, the perovskite precursor solution comprising a perovskite precursor, a solvent, and a crosslinking agent;

[0009] The perovskite precursor solution is coated onto a substrate, and at least part of the solvent is removed to form a perovskite thin film precursor.

[0010] The perovskite thin film precursor is preheated to 80-120°C;

[0011] The preheated perovskite film precursor is annealed at 300-400°C for 5-15 seconds to form a perovskite film on the substrate.

[0012] Secondly, the present invention also provides a perovskite thin film prepared by the above-described preparation method.

[0013] Thirdly, the present invention also provides a perovskite solar cell, comprising at least a hole transport layer, a perovskite layer and an electron transport layer stacked together, wherein the perovskite layer comprises the aforementioned perovskite thin film.

[0014] Fourthly, the present invention also provides a method for preparing the above-mentioned perovskite solar cell, comprising:

[0015] Provide a conductive substrate;

[0016] The step of forming a first transport layer on the surface of the conductive substrate;

[0017] The step of forming a perovskite thin film on the surface of the first transport layer using the above-described perovskite thin film preparation method is as follows:

[0018] The step of forming a second transport layer on the surface of the perovskite layer; and,

[0019] The step of constructing conductive electrodes on the surface of the second transport layer, wherein the first transport layer and the second transport layer have opposite conductivity characteristics.

[0020] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention include at least the following:

[0021] 1. The perovskite thin film preparation method and perovskite thin film provided by the present invention effectively improve the crystallinity of perovskite and reduce grain boundaries, thereby improving the efficiency and stability of perovskite solar cells.

[0022] 2. The perovskite thin film preparation method provided by the present invention can effectively shorten the preparation time of perovskite thin films and greatly improve production efficiency.

[0023] The above description is merely an overview of the technical solution of the present invention. In order to enable those skilled in the art to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below in conjunction with detailed drawings. Attached Figure Description

[0024] Figure 1 This is an electron microscope image of the surface of a perovskite thin film prepared in a typical embodiment of the present invention;

[0025] Figure 2 This is a surface electron microscope image of the perovskite thin film prepared in a typical comparative case provided by the present invention;

[0026] Figure 3These are the current-voltage characteristic curves of the perovskite thin films prepared according to the embodiments and comparative examples provided by the present invention;

[0027] Figure 4 This is a tracking curve of the efficiency change over time of different perovskite thin-film batteries prepared according to the embodiments and comparative examples provided by the present invention after being stored in a nitrogen glove box for thirty days. Detailed Implementation

[0028] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0030] This invention provides a method for preparing a perovskite thin film, comprising the following steps:

[0031] A perovskite precursor solution is provided, the perovskite precursor solution comprising a perovskite precursor, a solvent, and a crosslinking agent.

[0032] The perovskite precursor solution is coated onto a substrate, and at least a portion of the solvent is removed to form a perovskite thin film precursor.

[0033] The perovskite thin film precursor is preheated to 80-120°C.

[0034] The preheated perovskite film precursor is annealed at 300-400°C for 5-15 seconds to form a perovskite film on the substrate.

[0035] Thermal annealing plays a crucial role in the growth of perovskite crystals. Through long-term research and practice, the inventors of this invention discovered that as the annealing temperature increases, the perovskite grains obtained are larger. However, excessively high temperatures can cause the organic components in the perovskite film to "escape," resulting in component displacement and affecting battery efficiency. Therefore, the inventors of this invention creatively employ a technical solution of doping the perovskite precursor solution with additives that can bind organic ions, combined with an ultra-high temperature instantaneous annealing process, which effectively improves the crystallinity of perovskite, as well as battery efficiency and crystal stability.

[0036] In some embodiments, the crosslinking agent may include one or more of triacrylate crosslinking agents, polyolefin crosslinking agents, and silane crosslinking agents.

[0037] In some embodiments, the crosslinking agent preferably includes one or a combination of two of trimethylolpropane triacrylate and polyethylene.

[0038] In this invention, crosslinking refers to a crosslinked network structure formed by chemical bonds or physical interactions. The crosslinking methods can include physical crosslinking and chemical crosslinking. Chemical crosslinking can be further divided into silane crosslinking and peroxide crosslinking. For example, commonly used polyethylene and silane have the same crosslinking effect.

[0039] In some embodiments, the crosslinking agent in the perovskite precursor solution accounts for 0.1-0.3% of the total molar amount of the perovskite precursor.

[0040] In some embodiments, the perovskite precursor may include any one or a combination of two or more of the following: methylamine perovskite precursor, methylamine-formamidinium mixed perovskite precursor, and ternary mixed perovskite precursor.

[0041] In some embodiments, the concentration of the perovskite precursor in the perovskite precursor solution can be 1.2-1.5 mol / L.

[0042] In some embodiments, the preparation method may include: removing at least a portion of the solvent from the perovskite precursor solution by vacuuming and / or antisolventizing to form a perovskite thin film precursor.

[0043] In some typical application cases, a method for preparing perovskite thin films can be implemented using the following technical solutions:

[0044] Step 1: Prepare a perovskite precursor solution of a certain concentration, using N,N-dimethylformamide, dimethyl sulfoxide or N-methylpyrrolidone as solvent, and add cross-linking additives such as trimethylolpropane triacrylate.

[0045] Step 2: Spin-coat or coat the perovskite solution onto the substrate, remove most of the solvent using vacuum pumping, and obtain a slightly dried perovskite film. Then, use a two-step annealing method: first, heat it on a hot stage at 100°C to allow the perovskite to crystallize completely, obtaining a black α-phase film; then, anneal it at a higher temperature of about 300-400°C for a few seconds to a dozen seconds to remove all the solvent, obtaining a perovskite film with larger grains.

[0046] This process can produce perovskite films with larger grains, effectively reducing grain boundaries and improving the efficiency and stability of solar cells. In addition, its application in production can effectively improve production efficiency.

[0047] The present invention also provides a perovskite thin film prepared by any of the above-described methods, wherein the average grain size of the perovskite thin film is preferably 600-1000 nm.

[0048] This invention also provides a perovskite solar cell, which may include at least a hole transport layer, a perovskite layer and an electron transport layer stacked sequentially, wherein the perovskite layer includes the aforementioned perovskite thin film.

[0049] In some embodiments, the hole transport layer may include any one or a combination of two or more of Spiro-OMeTAD (2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirodifluorene), PEDOT:PSS, P3HT, PTAA, or PCDTBT.

[0050] The present invention also provides a method for preparing the above-mentioned perovskite solar cell, comprising the following steps:

[0051] Provide a conductive substrate.

[0052] The step of forming a first transport layer on the surface of the conductive substrate.

[0053] The step of forming a perovskite thin film on the surface of the first transport layer using any of the above-described methods for preparing perovskite thin films, as a perovskite layer.

[0054] The step of forming a second transport layer on the surface of the perovskite layer.

[0055] And the step of constructing a conductive electrode on the surface of the second transport layer, wherein the first transport layer and the second transport layer have opposite conductivity characteristics.

[0056] The first transport layer mentioned above can be, for example, an electron transport layer, in which case the second transport layer is a hole transport layer. Alternatively, the configuration can be reversed, with the first transport layer being a hole transport layer and the second transport layer being an electron transport layer.

[0057] In some typical applications, the perovskite solar cell device can be either a forward-facing or reverse-facing structure. Its structure consists of: a conductive substrate, a hole or electron transport layer, a perovskite layer, an electron or hole transport layer with opposite conductivity to the aforementioned hole or electron transport layer, and an electrode, stacked sequentially. The preferred materials and thicknesses of each layer are: the conductive substrate is one of FTO conductive glass, ITO conductive glass, FTO conductive plastic, and ITO conductive plastic, wherein the FTO conductive glass thickness is approximately 500 nm, and the ITO conductive glass thickness is approximately 300-400 nm; the buffer layer thickness is 10-20 nm; and the perovskite layer is preferably... MAPbI3 (the structural formula of MA is CH3NH3+) has a thickness of 300–1000 nm; the hole transport layer is any one of Spiro-OMeTAD (2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirodifluorene), PEDOT: PSS, P3HT, PTAA, or PCDTBT, with a thickness of 300–600 nm; the electrode is any one of Ag, Al, Au, or TCO, with a thickness of approximately 100–300 nm.

[0058] The preferred methods for preparing the above layers are as follows: the conductive substrate is prepared using physical vapor deposition, evaporation, or sputtering; the electron transport layer and hole transport layer are prepared using any one of spin coating, spraying, or blade coating; the perovskite layer is prepared using the above methods for preparing perovskite thin films, wherein the solvent is removed using a vacuum degassing method or an anti-solvent method; the conductive electrode can be prepared using vacuum evaporation or vacuum sputtering, and can be a metal electrode, a transparent conductive oxide thin film, or a TCO electrode.

[0059] The technical solution of the present invention will be further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only for illustrating the present invention and do not limit the scope of the present invention.

[0060] Example 1

[0061] This embodiment provides a method for preparing a perovskite thin film, comprising the following steps:

[0062] Step 1: Prepare a MAPbI3 solution of perovskite precursor with a concentration of 1.3 mol / L, and dope it with a certain proportion of trimethylolpropane triacrylate, the concentration of which is 0.2% of the molar concentration of the perovskite precursor. Use N,N-dimethylformamide and N-methylpyrrolidone in a volume ratio of 9:1 as solvents.

[0063] Step 2: Spin-coat the perovskite solution onto the substrate, remove most of the solvent using vacuum pumping to obtain a semi-crystalline perovskite film, and place the semi-crystalline perovskite film on a hot stage and heat it to 100°C to transform it into a black α-phase perovskite film precursor. This preheating step removes most of the solvent, avoiding the phenomenon of residual solvent boiling and the formation of pores in the film caused by direct ultra-high temperature heating. Then, place the perovskite film precursor on a 400°C hot stage for annealing for 5 seconds to obtain a fully crystalline perovskite film.

[0064] The surface electron microscope image of the perovskite thin film is as follows: Figure 1 As shown.

[0065] Example 2

[0066] This embodiment provides a method for preparing a perovskite thin film. The implementation scheme is basically the same as that in Embodiment 1, except that:

[0067] In the perovskite precursor solution, the perovskite precursor is a mixture of methylammonium iodide, formamidinium hydroiodate, cesium iodide and lead iodide in a molar ratio of 0.05:0.85:0.1:1.

[0068] Example 3

[0069] This embodiment provides a method for preparing a perovskite thin film. The implementation scheme is basically the same as that in Embodiment 1, except that:

[0070] In the perovskite precursor solution, the crosslinking agent is polyethylene, which accounts for 0.2% of the molar amount of the perovskite precursor.

[0071] Example 4

[0072] This embodiment provides a method for preparing a perovskite thin film. The implementation scheme is basically the same as that in Embodiment 1, except that:

[0073] The semi-crystalline perovskite film was preheated to 80°C;

[0074] The perovskite film precursor was annealed at 300℃ for 15s to obtain a fully crystalline perovskite film.

[0075] Example 5

[0076] This embodiment provides a method for preparing a perovskite thin film. The implementation scheme is basically the same as that in Embodiment 1, except that:

[0077] The semi-crystalline perovskite film was preheated to 120°C;

[0078] The perovskite film precursor was annealed at 350℃ for 10 seconds to obtain a fully crystalline perovskite film.

[0079] Example 6

[0080] This embodiment provides a method for preparing a perovskite thin film. The implementation scheme is basically the same as that in Embodiment 1, except that:

[0081] The crosslinking agent used is a silane crosslinking agent.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing a perovskite thin film, comprising the following steps:

[0084] Step 1: Prepare an undoped perovskite precursor solution: Prepare the perovskite precursor MAPbI3 by mixing methylammonium iodide and lead iodide in an equimolar ratio. Use N,N-dimethylformamide and N-methylpyrrolidone as solvents with a solvent volume ratio of 9:1 to prepare a perovskite precursor solution of the same concentration as in Step 1 of Example 1.

[0085] Step 2: Spin-coat the perovskite solution onto the substrate, remove most of the solvent by vacuum pumping to obtain a semi-crystalline perovskite film, and anneal the perovskite film on a 100°C heating table for 30 minutes to obtain a fully crystalline perovskite film.

[0086] The surface electron microscope image of the perovskite thin film prepared in this comparative example is shown below. Figure 2 As shown.

[0087] Comparative Example 2

[0088] This comparative example provides a method for preparing a perovskite thin film, comprising the following steps:

[0089] Step 1: Prepare a perovskite precursor solution of the same concentration and type as in Example 1, and dope it with the same compound as in Example 1, and the doping ratio is also the same as in Example 1. Use N,N-dimethylformamide and N-methylpyrrolidone as solvents, with a solvent volume ratio of 9:1.

[0090] Step 2: Spin-coat the perovskite solution onto the substrate, remove most of the solvent by vacuum pumping to obtain a semi-crystalline perovskite film, and anneal the perovskite film on a 100°C heating table for 30 minutes to obtain a fully crystalline perovskite film.

[0091] Comparative Example 3

[0092] This comparative example provides a method for preparing a perovskite thin film, comprising the following steps:

[0093] Step 1: Prepare an undoped perovskite precursor solution. Mix methylammonium iodide and lead iodide to prepare the perovskite precursor MAPbI3. Use N,N-dimethylformamide and N-methylpyrrolidone as solvents with a solvent volume ratio of 9:1 to prepare a perovskite precursor solution of the same concentration as in Step 1 of Example 1.

[0094] Step 2: Spin-coat the perovskite solution onto the substrate, remove most of the solvent by vacuum pumping to obtain a semi-crystalline perovskite film, place the semi-crystalline perovskite film on a hot stage and heat it to 100°C to transform it into a black α-phase perovskite film precursor, and then anneal the perovskite film precursor on a 400°C hot stage for 5 seconds to obtain a fully crystalline perovskite film.

[0095] The solar cells constructed from the perovskite thin films obtained in Example 1 and Comparative Examples 1-3 were subjected to performance testing, and the test results are shown in the table below:

[0096]

[0097] The current-voltage characteristic curves of the perovskite thin films prepared in Example 1 and Comparative Examples 1-3 are shown in the figure. Figure 3 As shown in the curve, the open-circuit voltage, short-circuit current, fill factor, and final efficiency of the perovskite thin film provided in the embodiments of the present invention are significantly improved, indicating that the defects in the perovskite are significantly reduced and the device performance is significantly optimized.

[0098] The cell efficiency of the perovskite thin-film solar cells prepared in Example 1 and Comparative Examples 1-3 over time is shown in the graphs below. Figure 4 As shown in the figure, the perovskite thin-film solar cell prepared in the embodiment exhibits significantly stronger stability than that in the embodiment. To facilitate understanding of the technical effects of this invention, the final results of the above stability tests are listed in the table below:

[0099] sample Standardized efficiency after 30 days Example 1 95.6％ Comparative Example 1 85.1％ Comparative Example 2 93.4％ Comparative Example 3 91.0％

[0100] Based on the above test results, it is clear that the perovskite thin film prepared by the method of the present invention has a significantly larger grain size than that of the prior art, and its crystallization performance is excellent, thereby improving the efficiency and stability of perovskite solar cells. The efficiency of the perovskite solar cells prepared is significantly better than that of the prior art. Furthermore, the annealing time of the perovskite thin film preparation method provided by the present invention is significantly shortened, which can greatly improve production efficiency.

[0101] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite thin film, characterized by, The application relates to a preparation method of a perovskite thin film, and a perovskite solar cell. The application provides a perovskite precursor solution, a substrate, and a perovskite thin film. The perovskite precursor solution comprises a perovskite precursor, a solvent and a cross-linking agent. The perovskite precursor solution is coated on the substrate, and at least part of the solvent is removed to form a perovskite thin film precursor. The perovskite thin film precursor is preheated to 80-120 DEG C. The preheated perovskite thin film precursor is heated to 300-400 DEG C for annealing treatment for 5-15 s, so that a perovskite thin film is formed on the substrate.

2. The production method according to claim 1, characterized by, The cross-linking agent is used to bind the organic components in the perovskite thin film, and avoids component deviation of the perovskite thin film in the annealing process.

3. The preparation method according to claim 2, characterized in that, The cross-linking agent comprises one or a combination of more than two of triacrylate cross-linking agents, polyolefin cross-linking agents and silane cross-linking agents.

4. The production method according to claim 2, characterized by, The cross-linking agent comprises one or a combination of more than two of trimethylolpropane triacrylate and polyethylene.

5. The preparation method according to claim 1, characterized in that, The mole number of the cross-linking agent in the perovskite precursor solution accounts for 0.1-0.3% of the mole number of the perovskite precursor.

6. The production method according to claim 5, wherein The perovskite precursor comprises any one or a combination of more than two of methylamine perovskite precursors, methylamine formamidine mixed perovskite precursors and ternary mixed perovskite precursors.

7. The preparation method according to claim 1, characterized in that, The concentration of the perovskite precursor in the perovskite precursor solution is 1.2-1.5 mol / L. The application also discloses a perovskite solar cell prepared by the preparation method.

8. The perovskite film produced by the production method according to any one of claims 1 to 7, characterized by At least part of the solvent in the perovskite precursor solution is removed by vacuumizing and / or using an anti-solvent to form a perovskite thin film precursor.

9. A perovskite solar cell, characterized by, The average size of the crystal grains in the perovskite thin film is 600-1000 nm.

10. The perovskite solar cell according to claim 9, characterized in that, The perovskite layer comprises the perovskite thin film prepared by the preparation method.

11. The method of producing a perovskite solar cell according to any one of claims 9 to 10, characterized by, The hole transport layer comprises any one or a combination of more than two of Spiro-OMeTAD, PEDOT:PSS, P3HT, PTAA and PCDTBT. The application further discloses a perovskite solar cell. The application provides a perovskite solar cell. The application provides a perovskite solar cell. The application provides a perovskite solar cell. The application provides a perovskite solar cell. The first transport layer and the second transport layer have opposite conductive properties.

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