Method for preparing perovskite thin film and method for preparing perovskite solar cell

Abstract

The application is suitable for the technical field of perovskite solar cells, and provides a preparation method of a perovskite thin film and a preparation method of a perovskite solar cell. The preparation method of the perovskite thin film comprises the following steps: applying a perovskite precursor solution on a substrate to obtain a perovskite wet film; placing the perovskite wet film in an anti-solvent containing an additive and used for extracting the perovskite precursor solution, and performing ultrasonic treatment on the anti-solvent; and performing annealing on the treated perovskite wet film to obtain a perovskite thin film. The preparation method of the perovskite thin film can reduce defects of the perovskite thin film, improve the quality of the perovskite thin film, and thus improve the photoelectric conversion efficiency of the perovskite solar cell using the perovskite thin film.

Description

Technical Field

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

[0002] With the increasing depletion of chemical fuel resources, the development and utilization of new energy sources has become a perpetual research direction in the 21st century. The simplicity, safety, pollution-free nature, and inexhaustible availability of solar energy have made it a research hotspot for nearly a century. Since the last century, crystalline silicon solar cells, amorphous silicon solar cells, and thin-film solar cells have gradually emerged, while their persistently high costs have spurred the development of a new generation of high-efficiency solar cells. As the first generation of solar cells, crystalline silicon cells have been approaching their conversion efficiency limit of 29.4%. To overcome this efficiency bottleneck and reduce the manufacturing cost of solar cells, researchers have turned their attention to the third generation of solar cells—perovskite solar cells. The emergence of perovskite cells has pointed to a new direction for the development of the photovoltaic industry. High efficiency and low cost have become the hallmarks of perovskite cells; since 2009, in just 12 years, perovskite cells have achieved a rapid growth rate from 3.8% to 25.5%. Although the photoelectric conversion efficiency of perovskite solar cells can rival that of traditional silicon solar cells, the quality of the perovskite film decreases as the perovskite area increases, which in turn affects the photoelectric performance of perovskite solar cells and thus restricts the industrialization process of perovskite.

[0003] In existing technologies, perovskite thin films are typically prepared using spin coating, slot coating, spraying, or linear vacuum deposition to obtain a wet perovskite film, which is then annealed to crystallize and form a perovskite thin film. However, perovskite films obtained directly from wet perovskite films through annealing often contain numerous voids. These voids act as recombination centers for charge carriers, resulting in poor film quality, low hole and electron transport efficiency, and consequently, low photoelectric conversion efficiency in perovskite solar cells. Summary of the Invention

[0004] This invention provides a method for preparing perovskite thin films, aiming to solve the problem that the perovskite thin films prepared by existing methods are of poor quality, resulting in low photoelectric conversion efficiency of perovskite solar cells.

[0005] This invention is achieved by providing a method for preparing perovskite thin films, comprising the following steps:

[0006] The perovskite precursor solution was coated onto the substrate to obtain a perovskite wet film.

[0007] The perovskite wet film is placed in an antisolvent containing additives and used to extract the perovskite precursor solution, and the antisolvent is subjected to ultrasonic treatment.

[0008] The treated perovskite wet film is annealed to obtain a perovskite thin film.

[0009] Preferably, the solute of the perovskite precursor solution is at least one of ABX3, wherein A is a methylamine group, a formamidinium group or Cs, B is Pb, Sn or Ge, and X is I, Br or Cl, and the solvent of the perovskite precursor solution is one or a combination of dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0010] Preferably, the antisolvent is at least one selected from anisole, chlorobenzene, toluene, isopropanol, ethyl acetate, ethanol, butanol, 1,2-dichlorobenzene, ethyl acrylate, chloroform, butyl acrylate, diethyl ether, m-xylene, toluene, and 1,3,5-trimethylbenzene.

[0011] Preferably, the additive is at least one selected from methylamine vapor, formamidin vapor, 1-butyl-3-methylimidazolium tetrafluoroborate, methylamine formate, methylamine acetate, 1-ethyl-3-methylimidazolium bromine, elemental iodine, and iodides.

[0012] Preferably, the iodide is lead iodide or cesium iodide.

[0013] Preferably, the ultrasonic wave generating power is 5-100W.

[0014] Preferably, the ultrasonic treatment time is 10-30 minutes.

[0015] Preferably, the annealing temperature is 70-150°C.

[0016] Preferably, the annealing time is 5-30 minutes.

[0017] The present invention also provides a method for preparing a perovskite solar cell, comprising the above-mentioned method for preparing a perovskite thin film, and further comprising:

[0018] A second contact layer is prepared on the perovskite thin film;

[0019] An electrode layer is prepared on the second contact layer.

[0020] The method for preparing perovskite thin films provided by this invention involves placing the perovskite wet film in an antisolvent containing additives after preparation, and then subjecting the antisolvent to ultrasonic treatment. The combination of the antisolvent and ultrasonic vibration accelerates the extraction of solvent from the perovskite wet film into the antisolvent, thus accelerating the crystallization of the perovskite wet film. Simultaneously, due to the presence of additives in the antisolvent, the ultrasonic waves cause antisolvent bubbles to carry a large number of additive molecules to the surface of the perovskite intermediate. During subsequent annealing, these molecules disperse at the perovskite grain boundaries and surface, acting as passivating grain boundaries. This allows the additives to effectively fill the surface of the perovskite crystal nuclei, reducing voids in the perovskite film's carrier recombination centers and minimizing defects. Combined with the subsequent annealing process, this passivation of grain boundaries improves the crystallinity of the perovskite film, enhances the hole and electron transport efficiency, and ultimately improves the photoelectric conversion efficiency of perovskite solar cells using this perovskite thin film. Attached Figure Description

[0021] Figure 1 A flowchart illustrating a method for preparing a perovskite thin film according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure for implementing step S2 in a method for preparing a perovskite thin film according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure for implementing step S3 in a method for preparing a perovskite thin film according to an embodiment of the present invention;

[0024] Figure 4 A flowchart illustrating a method for fabricating a perovskite solar cell according to an embodiment of the present invention;

[0025] Figure 5 The graph shows the open-circuit voltage-current density variation curves of a perovskite solar cell prepared by a method provided in this embodiment of the invention and a perovskite solar cell prepared by a conventional method. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] The method for preparing perovskite thin films provided in this invention involves placing the perovskite wet film in an antisolvent containing additives and subjecting it to ultrasonic treatment after preparation. The combination of the antisolvent and ultrasonic vibration accelerates the extraction of solvent from the perovskite wet film into the antisolvent, thus accelerating the crystallization of the perovskite wet film. Simultaneously, due to the presence of additives in the antisolvent, the ultrasonic waves cause antisolvent bubbles to carry a large number of additive molecules to the surface of the perovskite intermediate. During subsequent annealing, these molecules disperse at the perovskite grain boundaries and surface, effectively passivating the grain boundaries. This allows the additives to effectively fill the perovskite crystal nuclei, reducing voids in the perovskite film's carrier recombination centers and minimizing defects. Combined with the subsequent annealing process, this passivation of grain boundaries improves the quality of the perovskite film, enhances the hole and electron transport efficiency, and ultimately improves the photoelectric conversion efficiency of the perovskite solar cell using this perovskite thin film.

[0028] Please refer to Figure 1 The present invention provides a method for preparing a perovskite thin film, comprising the following steps:

[0029] Step S1: Apply the perovskite precursor solution to the substrate to obtain a perovskite wet film.

[0030] In one embodiment of the present invention, the solute of the perovskite precursor solution is at least one of ABX3, wherein A is a methylamine group, a formamidinium group, or Cs, B is Pb, Sn, or Ge, and X is I, Br, or Cl. The solvent of the perovskite precursor solution is one or a combination of dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, and N-methylpyrrolidone. The solute and solvent of the perovskite precursor solution can be selected according to the actual application.

[0031] In a preferred embodiment of the present invention, the solutes of the perovskite precursor solution are lead iodide and methyl ammonium iodide, and the solvents of the perovskite precursor solution are dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0032] As an embodiment of the present invention, the preparation process of the perovskite precursor solution specifically includes: dissolving lead iodide and methyl ammonium iodide in a molar ratio of 1:1 in a mixed solution of DMF and DMSO in a volume ratio of 1:1 and mixing them evenly to obtain the perovskite precursor solution.

[0033] As a preferred embodiment of the present invention, the perovskite precursor solution can be applied to the substrate by spin coating, slot coating, spraying, or linear vacuum deposition to obtain a perovskite wet film.

[0034] In one embodiment of the present invention, the substrate includes a transparent conductive underlayer and a first contact layer coated on the transparent conductive underlayer. A perovskite precursor liquid is coated on the first contact layer to form a perovskite wet film on the first contact layer. The first contact layer can serve as either an electron transport layer or a second contact layer of the perovskite solar cell.

[0035] The substrate preparation process specifically includes: preparing a first contact layer on a transparent conductive substrate to obtain the substrate.

[0036] In this embodiment of the invention, the transparent conductive underlayer is made of at least one of FTO (fluorine-doped tin oxide), ITO (indium-doped tin oxide), AZO (aluminum-doped zinc oxide), ATO (aluminum-doped tin oxide), and IGO (indium-doped gallium oxide). The first contact layer is at least one of N-type semiconductors SnO2, TiO2, and ZnSnO4, or at least one of P-type semiconductors Spiro-oMeTad, NiO, and CuSCN.

[0037] Step S2: Place the perovskite wet film in an antisolvent containing additives and a solvent used to extract the perovskite precursor solution, and subject the antisolvent to ultrasonic treatment.

[0038] In this embodiment of the invention, after the perovskite wet film is prepared, the solvent of the perovskite precursor solution of the perovskite wet film is extracted into the antisolvent by placing the perovskite wet film in an antisolvent containing additives and subjecting it to ultrasonic treatment.

[0039] On the one hand, due to the difference in solubility of the perovskite precursor between the antisolvent and the perovskite precursor solution, after the perovskite wet film is placed in the antisolvent containing additives, a large amount of solvent (DMF / DMSO solvent) in the perovskite wet film will be extracted from the perovskite wet film into the antisolvent. The perovskite wet film that has just entered the antisolvent reacts with the antisolvent to rapidly form a perovskite intermediate (perovskite-DMSO intermediate). The perovskite intermediate adheres to the substrate surface to prevent it from being dispersed and detached from the substrate surface by ultrasonic waves. Because the ultrasonic oscillation transmits the power through the transducer... The acoustic energy of the ultrasonic source is converted into mechanical energy. The antisolvent is continuously radiated by the ultrasonic waves. When the micro-gas in the antisolvent is subjected to a certain degree of sound pressure, it will expand rapidly and then suddenly close. During this process, the moment the bubble closes, a shock wave is generated, which causes high pressure and local high temperature around the bubble and promotes the rapid extraction of polar solvent molecules remaining in the perovskite intermediate bulk phase into the antisolvent. This reduces the amount of wet perovskite film and the residual precursor liquid solvent in the perovskite intermediate bulk phase. At the same time, combined with a low-temperature annealing process, high-quality perovskite films can be obtained.

[0040] On the other hand, due to the presence of additives in the antisolvent, ultrasonic radiation causes antisolvent bubbles to carry a large number of additive molecules into the perovskite intermediate bulk phase and surface. During the subsequent annealing process, these molecules disperse at the perovskite grain boundaries and surface, acting as passivating grain boundaries. This allows the additives to effectively fill the perovskite crystal nuclei surface, reducing voids in the perovskite film's carrier recombination centers. Combined with the subsequent annealing process, this can passivate the grain boundaries, thereby improving the crystal quality of the perovskite film, enhancing the hole and electron transport efficiency, and ultimately improving the photoelectric conversion efficiency of the perovskite solar cell using this perovskite film.

[0041] Please refer to Figure 2 In practical applications, the perovskite wet film 1 is placed in an extraction container 3 containing an antisolvent 2 containing additives. The extraction container 3 is then placed in an ultrasonic cleaner 5 containing an ultrasonic medium 4. In the extraction container 3, the perovskite wet film 1 utilizes the antisolvent 2 to extract the solvent from the perovskite precursor solution. Simultaneously, the ultrasonic cleaner 5 works in conjunction with this process. The ultrasonic waves generated by the ultrasonic cleaner 5 are radiated from the outer wall of the extraction container 3 through the ultrasonic medium 4, ensuring that the antisolvent 2 inside the extraction container 3 is continuously irradiated by the ultrasonic waves, thus accelerating the solvent extraction process of the perovskite precursor solution. Simultaneously, the ultrasonic waves generated by the ultrasonic cleaner 5 cause antisolvent bubbles to carry a large number of additive molecules into the surface of the perovskite intermediate, dispersing the additive molecules at the perovskite grain boundaries and surface, thus passivating the grain boundaries and improving the crystallinity of the perovskite film. This, in turn, improves the photoelectric conversion efficiency of the perovskite solar cell using this perovskite film.

[0042] In one embodiment of the present invention, the antisolvent is at least one selected from anisole, chlorobenzene, toluene, isopropanol, ethyl acetate, ethanol, butanol, 1,2-dichlorobenzene, ethyl acrylate, chloroform, butyl acrylate, diethyl ether, m-xylene, toluene, and 1,3,5-trimethylbenzene. Utilizing the low viscosity of the above-mentioned antisolvents ensures the effective extraction of the solvent from the perovskite wet film, thereby ensuring the crystallinity quality of the perovskite film. The antisolvent can be selected according to the actual application.

[0043] In one embodiment of the present invention, the additive is at least one selected from methylamine vapor, formamidin vapor, 1-butyl-3-methylimidazolium tetrafluoroborate, methylamine formate, methylamine acetate, 1-ethyl-3-methylimidazolium bromine, elemental iodine, and iodides. The additive may be selected according to the actual application.

[0044] In this embodiment, when the additive is a steam additive, the antisolvent is a saturated solution of the steam additive; when the additive is a solid additive, the solid additive can be dissolved and settled by grinding with a ball mill / agate mortar and pestle in the absence of dissolution, and the upper clear solution is taken to ensure the extraction effect of the antisolvent.

[0045] As an embodiment of the present invention, when the additive is a solid additive, the concentration of the solid additive is 1 mg / mL-10 mg / mL.

[0046] As an embodiment of the present invention, the iodide is lead iodide or cesium iodide.

[0047] In one embodiment of the present invention, the ultrasonic wave generating power is 5-100W. The ultrasonic wave power can be set according to actual needs.

[0048] In one embodiment of the present invention, the ultrasonic treatment time is 10-30 minutes. The extraction and ultrasonic treatment are synchronized, meaning both the extraction and ultrasonic treatment times are 10-30 minutes. This ensures that the solvent in the perovskite precursor solution of the perovskite wet film 1 is fully extracted and that the additives are effectively filled onto the surface of the perovskite crystal nuclei, thereby effectively improving the quality of the perovskite film.

[0049] Step S3: Anneal the treated perovskite wet film to obtain a perovskite thin film.

[0050] In this step, the treated perovskite wet film is annealed to allow the perovskite wet film 1 to completely crystallize, thus obtaining a perovskite thin film. For example... Figure 3 As shown, in practical applications, the extracted perovskite wet film 1 is placed in the vacuum device 7 above the heating stage 6 of the annealing equipment. The perovskite wet film 1 in the vacuum device 7 is heated by the heating stage 6 so that the perovskite wet film 1 is completely crystallized to obtain a perovskite thin film.

[0051] In one embodiment of the present invention, the annealing temperature is 70-150°C. Because the perovskite wet film is subjected to ultrasonic treatment in an antisolvent containing additives before annealing, a large amount of solvent in the perovskite precursor solution can be extracted to achieve partial crystallization of the perovskite wet film. Thus, annealing at 70-150°C can achieve complete crystallization of the perovskite wet film, eliminating the need for high-temperature annealing and avoiding damage to the perovskite film structure at high temperatures, thereby further improving the quality of the perovskite film.

[0052] As an embodiment of the present invention, the annealing time is 5-30 minutes, which can achieve complete crystallization of the perovskite wet film and avoid damage to the structure of the perovskite film caused by excessive heating time, thereby further improving the quality of the perovskite film.

[0053] Please refer to Figure 4 The present invention also provides a method for preparing a perovskite solar cell, comprising the above-described method for preparing a perovskite thin film, and further comprising:

[0054] Step S4: Prepare a second contact layer on the perovskite thin film;

[0055] The first contact layer and the second contact layer are respectively at least one of the N-type semiconductors SnO2, TiO2, and ZnSnO4, and at least one of the P-type semiconductors Spiro-oMeTad, NiO, and CuSCN. Specifically, the second contact layer is formed by spin coating on the perovskite thin film. The spin coating speed is controlled at 4000-5000 rpm, and the spin coating time is 25-35 seconds.

[0056] Step S5: Prepare an electrode layer on the second contact layer.

[0057] The thickness of the vapor-deposited electrode layer is 60-80 nm. Specifically, the electrode layer is deposited on the second contact layer by thermal vapor deposition.

[0058] To demonstrate the technical effects achieved by the perovskite solar cell fabrication method of the present invention, the inventors conducted experimental comparison tests on the perovskite solar cells prepared by the method of the present invention and those prepared by conventional perovskite solar cell preparation methods. The specific experimental data are shown in Table 1. In Table 1, the perovskite solar cells of the control group were prepared by conventional perovskite solar cell preparation methods, while the perovskite solar cells of the experimental group were prepared by the perovskite solar cell preparation method of the present invention.

[0059] The open-circuit voltage-current density variation curves of the perovskite solar cells prepared by the method of the present invention and those prepared by conventional methods are shown in the figure below. Figure 5 As shown; where Figure 5 Curve A is the open-circuit voltage-current density variation curve of the perovskite solar cell prepared by the method of the present invention. Figure 5 Curve B represents the open-circuit voltage-current density variation curve of a perovskite solar cell fabricated using traditional perovskite solar cell fabrication methods.

[0060] Table 1

[0061] Classification <![CDATA[V oc (V)]]> <![CDATA[J sc (mA / cm -2 )]]> FF (%) PCE (%) control group 0.95 22.33 62.30 13.22 experimental group 1.02 22.42 73.93 16.91

[0062] Among them, V oc J is the open-circuit voltage. scis the current density; FF is the fill factor; PCE is the battery conversion efficiency.

[0063] From the experimental data in Table 1 above and Figure 5 As shown in the open-circuit voltage-current density curve, compared with perovskite solar cells prepared by traditional methods, the perovskite solar cells prepared by the method of this invention have higher open-circuit voltage, higher current density, larger fill factor, and higher cell conversion efficiency.

[0064] The method for preparing perovskite thin films provided in this invention involves placing the perovskite wet film in an antisolvent containing additives and subjecting it to ultrasonic treatment after preparation. The combination of the antisolvent and ultrasonic vibration accelerates the extraction of solvent from the perovskite wet film into the antisolvent, thus accelerating the crystallization of the perovskite wet film. Simultaneously, due to the presence of additives in the antisolvent, ultrasonic radiation causes antisolvent bubbles to carry a large number of additive molecules into the perovskite intermediate bulk phase and surface. During subsequent annealing, these molecules disperse at the perovskite grain boundaries and surface, effectively passivating the grain boundaries. This allows the additives to effectively fill the perovskite crystal nuclei surface, reducing voids in the perovskite film's carrier recombination centers and thus reducing defects. Combined with the subsequent annealing process, this passivation of grain boundaries improves the quality of the perovskite film, enhances the hole and electron transport efficiency, and ultimately improves the photoelectric conversion efficiency of the perovskite solar cell using this perovskite thin film.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a perovskite thin film, characterized by, The method comprises the following steps: applying a perovskite precursor solution on a substrate to obtain a perovskite wet film; placing the perovskite wet film in an anti-solvent containing an additive and a solvent used for extracting the perovskite precursor solution, the perovskite wet film at the liquid level of the anti-solvent reacts with the anti-solvent to rapidly form a perovskite intermediate, and the anti-solvent is subjected to ultrasonic treatment, the ultrasonic treatment promotes the anti-solvent bubbles to carry the additive molecules to the surface of the perovskite intermediate to passivate the grain boundaries; the additive is at least one of methylamine vapor, formamidine vapor, 1-butyl-3-methylimidazolium tetrafluoroborate, methylamine formate, methylamine acetate, 1-ethyl-3-methylimidazolium chloride, elemental iodine, and iodide; annealing the treated perovskite wet film to obtain a perovskite thin film.

2. The method for preparing a perovskite thin film according to claim 1, characterized in that, The solute of the perovskite precursor solution is at least one of ABX3, wherein A is a methylamine group, a formamidine group, or Cs, B is Pb, Sn, or Ge, and X is I, Br, or Cl; and the solvent of the perovskite precursor solution is one or a combination of dimethylformamide, dimethyl sulfoxide, N, N-dimethylacetamide, and N-methyl pyrrolidone.

3. The method for preparing a perovskite thin film according to claim 1, characterized in that, The anti-solvent is at least one of anisole, chlorobenzene, toluene, isopropyl alcohol, ethyl acetate, ethanol, butanol, 1,2-dichlorobenzene, ethyl acrylate, chloroform, butyl acrylate, diethyl ether, m-xylene, and 1,3,5-trimethylbenzene.

4. The method for preparing a perovskite thin film according to claim 1, characterized in that, The iodide is lead iodide or cesium iodide.

5. The method for preparing a perovskite thin film according to claim 1, characterized in that, The ultrasonic treatment power is 5-100 W.

6. The method of claim 1, wherein the perovskite thin film is prepared by a process comprising: The ultrasonic treatment time is 10-30 minutes.

7. The method for preparing a perovskite thin film according to claim 1, characterized in that, The annealing temperature is 70-150℃.

8. The method for preparing a perovskite thin film according to claim 1, characterized in that, The annealing time is 5-30 minutes.

9. A method of manufacturing a perovskite solar cell, characterized by, The method for preparing the perovskite thin film according to any one of claims 1-8 further comprises: preparing a second contact layer on the perovskite thin film; preparing an electrode layer on the second contact layer.

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