A method for improving the performance of perovskite materials

Abstract

The present application provides a method for improving perovskite materials. The method simultaneously performs dual ion doping of cesium ions or barium ions, and fluorine ions or chloride ions on perovskite raw materials. The method uniformly dopes a certain concentration of cesium ions or barium ions with a larger radius to enhance the stability of the perovskite lattice, while uniformly doping a corresponding concentration of fluorine ions or chloride ions with a smaller radius to fill the internal voids of the perovskite lattice, uniformly disperse the stress inside the perovskite material, and effectively reduce the lattice dislocation and microcracks that may be caused by doping with cesium ions or barium ions. In addition, fluorine ions or chloride ions have a significant passivation effect on lattice defects in perovskite materials, thereby reducing non-radiative recombination losses and improving the photoelectric conversion efficiency of perovskite battery components.

Description

Technical Field

[0001] The present application relates to the field of performance optimization of perovskite battery components or perovskite raw materials, and specifically to a method for improving the performance of perovskite materials. Background Art

[0002] Solar cells are photoelectric semiconductor sheets that use sunlight to generate electricity directly. They convert light energy into electrical energy directly through the photoelectric effect or photochemical effect. They have the advantages of high reliability, long life, and high conversion efficiency. With the development of technology, the conversion efficiency of solar cells has been continuously improved, the preparation cost has been continuously reduced, and photovoltaic power generation technology has achieved partial commercial application.

[0003] As the third generation of new concept solar cells, perovskite solar cells have the advantages of high photoelectric conversion efficiency, low cost and flexible processing. In recent years, they have developed rapidly and gradually become comparable to silicon cells, approaching the level of commercial application. Perovskite solar cells are low-cost and simple to prepare. As early as 1958, the study of inorganic perovskite CsPbX3 first proved the unusual photoconductivity of metal halide perovskites, where X is a negative halogen ion (Cl, Br or I). In 1978, the Weber team first studied organic-inorganic hybrid perovskites and found that they have excellent photoelectric properties. In 2009, the Miyasaka team used the mesoporous structure of TiO2 to publish the first research paper on the application of organic-inorganic metal halide perovskites in the field of solar cells, leading people into the research field of organic-inorganic hybrid perovskites. The rapid development in the international arena in the past decade has made organic-inorganic hybrid perovskites leap forward in terms of efficiency and stability. By 2020, the photoelectric conversion efficiency of perovskite solar cells has exceeded 25%.

[0004] Although the photoelectric conversion efficiency of perovskite cells has been improved, there are still the following shortcomings:

[0005] Perovskite materials have insufficient thermal stability and low product yield. Although there is currently a scheme to dope perovskite raw materials with metal ions with a larger radius to improve the stability of the perovskite lattice. However, this scheme is also prone to cause perovskite lattice dislocation and microcracks while doping with metal ions with a larger radius. Of course, even without doping with metal ions with a larger radius, perovskite materials will still produce lattice dislocation and microcracks when preparing thin films. There are defects (microcracks) on the surface of perovskite battery components, which affect the moisture stability of perovskite materials and the improvement of photoelectric conversion efficiency. Although interface modifiers have been used to improve the defects on the surface of the perovskite material layer, microcracks still need to be further eliminated. Summary of the invention

[0006] In view of the above-mentioned deficiencies of perovskite raw materials or perovskite battery components, the present application provides a method for improving the performance of perovskite materials. The method enhances the thermal stability of perovskite crystals by doping positive ions with a relatively large radius, and dopes negative ions with a smaller radius into the remaining gaps in the perovskite lattice to uniformly disperse the stress inside the perovskite material, reduce the generation of lattice dislocation and microcracks, and improve the moisture stability of the perovskite material.

[0007] The method for improving the performance of perovskite materials provided in the present application comprises: spin coating a perovskite precursor solution on a substrate, and forming a perovskite film after annealing; and simultaneously doping the perovskite film with a first doping concentration of cesium ions or barium ions and a second doping concentration of fluorine ions or chloride ions to improve the structural thermal stability and moisture stability of the perovskite material. The radius of cesium ions or barium ions is relatively large, and doping cesium ions or barium ions in the perovskite raw material can enhance the stability of the lattice. Fluorine ions or chloride ions are relatively much smaller, and they are used to fill the gaps left after doping cesium ions or barium ions in the perovskite lattice, uniformly disperse the internal stress of the perovskite material, and reduce the generation of lattice dislocations and microcracks.

[0008] The perovskite precursor solution is prepared by mixing the molecular types The perovskite raw material solution is in the corresponding solvent. For example, the lead-free perovskite The specific preparation of the perovskite raw materials and the corresponding solvents belong to the well-known technology of those skilled in the art and will not be described in detail here.

[0009] Furthermore, the dual doping adopts one or more combinations of the following methods: diffusion, ion implantation, chemical catalytic decomposition, impact ionization, photoionization, thermal ionization, plasma, electrolysis, chemical ionization, vapor deposition or plasma ionization.

[0010] Furthermore, the first doping concentration is controlled to be 3-5% of the number of perovskite material molecules in the perovskite film, and the second doping concentration is controlled to be 0.5%-1% of the number of perovskite material molecules in the perovskite film.

[0011] Furthermore, the dual doping is achieved by vapor deposition, including: placing the perovskite film in a deposition chamber, introducing cesium ion or barium ion precursor vapor and fluorine ion or chloride ion precursor vapor in a proportion corresponding to the number of molecules of the perovskite material in the perovskite film into the deposition chamber; controlling the doping environment conditions in the deposition chamber to achieve uniform doping of the perovskite material in the perovskite film with cesium ions or barium ions, and fluorine ions or chloride ions. or Steam, the precursor steam of the fluoride ion or the chloride ion is or steam.

[0012] Furthermore, the doping environment conditions include: Sedimentation chamber or The steam pressure, temperature, and Sedimentation chamber or In one embodiment, controlling the doping environment conditions in the deposition chamber includes: or The steam pressure is controlled to be less than or equal to 1050 and the deposition temperature is , for 30-60 minutes; at the same time, the or The gas flow rate is maintained at 10-20 sccm.

[0013] The technical solution provided by the present application enhances the thermal stability of the perovskite crystal by doping cesium ions or barium ions with a relatively large radius into the perovskite raw material, and dopes negative ions with a smaller radius into the remaining gaps of the perovskite lattice to uniformly disperse the stress inside the perovskite material, effectively reducing the generation of lattice dislocation and microcracks, and improving the moisture stability of the perovskite material. On this basis, the photoelectric conversion efficiency of the battery assembly made of the perovskite material improved by the method provided by the present application will also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 A flow chart of an embodiment of the method for improving perovskite materials provided in the present application.

[0016] Figure 2a This is an electron microscope image of the same perovskite film after being improved by the method provided in this application. Figure 2b These are electron microscope images of the same perovskite film after doping with a single cesium ion or barium ion. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0018] In such Figure 1 In one embodiment shown, the method for improving the performance of perovskite materials provided in the present application mainly includes the following steps:

[0019] S1. Preparation of perovskite precursor solution. The preparation methods of different perovskite precursor solutions are common knowledge in the relevant field and have been recorded in a large number of patent documents; they will not be described in detail here.

[0020] S2. Use the perovskite precursor solution to spin-coat and anneal on the substrate to form a perovskite film. As the substrate for the deposition of the perovskite film, FTO conductive glass, silicon wafer, etc. can usually be selected. The surface of the substrate needs to be cleaned to remove surface impurities to minimize interface defects, which is conducive to the preparation of high-quality perovskite films. For example, the FTO conductive glass substrate can be cleaned by ultrasonically cleaning the FTO glass substrate with deionized water, detergent, ethanol, and acetone to remove solid impurities on the glass substrate. Remove the residual liquid on the surface of the FTO glass substrate, and after the glass substrate is completely dried, use a plasma cleaning liquid to treat the FTO glass substrate to remove residual organic impurities on the glass surface and improve the hydrophilicity of the glass surface.

[0021] S3. Place the perovskite film in a deposition chamber. Pass a corresponding amount of cesium ion or barium ion precursor vapor and a corresponding amount of fluorine ion or chloride ion precursor vapor to achieve uniform doping of the perovskite material under certain doping environmental conditions. The doping environmental conditions include: Sedimentation chamber or The steam pressure, temperature, and Sedimentation chamber or Gas flow rate of steam.

[0022] The focus of this application is on step S3, through which the perovskite film is simultaneously doped with a first doping concentration of cesium ions or barium ions and a second doping concentration of fluorine ions or chloride ions to improve the structural thermal stability and moisture stability of the perovskite material. Since the radius of cesium ions or barium ions is relatively large, doping cesium ions or barium ions in the perovskite raw material can enhance the stability of the lattice. Fluorine ions or chloride ions are relatively much smaller, and are used to fill the gaps left after doping cesium ions or barium ions in the perovskite lattice, uniformly disperse the internal stress of the perovskite material, and reduce the generation of lattice dislocations and microcracks.

[0023] The dual doping in step S3 is achieved by one or more combinations of the following doping methods: diffusion, ion implantation, chemical catalytic decomposition, collision ionization, photoionization, thermal ionization, plasma, electrolysis, chemical ionization, vapor deposition or plasma ionization.

[0024] Furthermore, the first doping concentration is controlled to be 3-5% of the number of perovskite material molecules in the perovskite film to ensure that the stability of the perovskite material lattice can be improved without introducing too many defects. Correspondingly, the second doping concentration is controlled to be 0.5%-1% of the number of perovskite material molecules in the perovskite film.

[0025] Preferably, the dual doping in step S3 is performed by vapor deposition (CVD) to simultaneously dope cesium ions or barium ions, and fluorine ions or chloride ions in the perovskite raw material to improve the uniformity of doping. The specific implementation is:

[0026] The perovskite film is placed in a deposition chamber, and precursor vapor of cesium ions or barium ions and precursor vapor of fluorine ions or chloride ions in proportion to the number of molecules of the perovskite material in the perovskite film are introduced into the deposition chamber together; the doping environment conditions in the deposition chamber are controlled to achieve uniform doping of the perovskite material in the perovskite film with cesium ions or barium ions, and fluorine ions or chloride ions.

[0027] The precursor vapor of cesium ions or barium ions is or Steam, the precursor steam of the fluoride ion or the chloride ion is or The doping environment conditions include: the vapor pressure and temperature of the deposition chamber, and the gas flow rate of the vapor or the vapor introduced into the deposition chamber. In some embodiments, controlling the doping environment conditions in the deposition chamber includes: adjusting the vapor introduced into the deposition chamber or The steam pressure is controlled to be less than or equal to 1050 and the deposition temperature is , for 30-60 minutes; at the same time, the or The gas flow rate is maintained at 10-20 sccm.

[0028] Figure 2a This is an electron microscope image of the same perovskite film after being improved by the method provided in this application. Figure 2b The electron microscope images of the same perovskite film after single cesium ion or barium ion doping. Figure 2a , Figure 2b From the scanning electron microscope image, it can be seen that the surface cracks of the perovskite material improved by the method provided by the present application are not as clear as those using only a single cesium ion or barium ion (cation with a large radius). That is, the surface of the perovskite material improved by the method provided by the present application is relatively flat and smooth, with good density and high moisture stability.

[0029] The method provided by the present application can effectively reduce the generation of lattice dislocation and microcracks in perovskite materials while enhancing the lattice stability of perovskite materials. In addition, it can also produce a significant passivation effect on the lattice defects in the perovskite material, thereby reducing non-radiative recombination losses and improving the photoelectric conversion efficiency of perovskite battery components.

[0030] Finally, it should be noted that the above description is only a partial embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for improving the performance of perovskite materials, characterized in that: The method comprises: spin coating a perovskite precursor solution on a substrate, and forming a perovskite film after annealing; and simultaneously doping the perovskite film with a first doping concentration of cesium ions or barium ions and a second doping concentration of fluorine ions or chloride ions to improve the structural thermal stability and moisture stability of the perovskite material; wherein the cesium ions or barium ions are used to enhance the stability of the perovskite lattice, and the fluorine ions are used to fill the gaps left in the perovskite lattice after the cesium ions or barium ions are doped, so as to uniformly disperse the internal stress of the perovskite material; the first doping concentration is 3-5% of the number of molecules of the perovskite material in the perovskite film, and the second doping concentration is 0.5%-1% of the number of molecules of the perovskite material in the perovskite film.

2. The method according to claim 1, characterized in that The dual doping is carried out by one or more combinations of the following methods: diffusion, ion implantation, chemical catalytic decomposition, impact ionization, photoionization, thermal ionization, plasma, electrolysis, chemical ionization, vapor deposition or plasma ionization.

3. The method according to claim 2, characterized in that The substrate is FTO conductive glass or silicon wafer.

4. The method according to claim 3, characterized in that Before the perovskite precursor solution is spin-coated on the substrate, the substrate is cleaned and dried.

5. The method according to claim 4, characterized in that The substrate is an FTO glass substrate, and the cleaning process includes: using ultrasonic cleaning to remove solid impurities on the FTO glass substrate, and using plasma cleaning liquid to treat the FTO glass substrate to remove organic impurities.

6. The method according to claim 1, characterized in that The dual doping is achieved by a vapor deposition method, including: placing the perovskite film in In the deposition chamber, a corresponding amount of the molecular number of the perovskite material in the perovskite film is added. or steam, or Steam is introduced into the Deposition chamber; controlling doping environment conditions to achieve uniform doping of the perovskite material in the perovskite film with cesium ions or barium ions, fluorine ions or chloride ions.

7. The method according to claim 6, characterized in that The doping environment conditions include: Sedimentation chamber or The steam pressure, temperature, and Sedimentation chamber or Gas flow rate of steam.

8. The method according to claim 7, characterized in that The controlling of the doping environment conditions comprises: introducing the Sedimentation chamber or Steam pressure is controlled at less than or equal to 1050 , the temperature is 150-200°C; at the same time, the Sedimentation chamber or The gas flow rate of the steam is maintained at 10-20 sccm for a predetermined period of time.

9. The method according to claim 8, characterized in that The predetermined duration is 30 to 60 minutes.

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