A method for preparing perovskite thin films based on spatial thermal gradient annealing and a solar cell

Abstract

The present invention discloses a method for preparing a perovskite thin film based on spatial thermal gradient annealing and a solar cell, having the following characteristics, including the following steps: Step 1, preparing a perovskite precursor solution; Step 2, using the perovskite precursor solution to prepare a pretreated perovskite thin film; Step 3, performing spatial thermal gradient annealing treatment on the pretreated perovskite thin film to obtain a perovskite thin film; Step 4, first performing surface treatment on the perovskite thin film, secondly preparing a hole transport layer of Spiro-OMeTAD, then performing spin coating preparation, and finally depositing a metal electrode to finally obtain a high-efficiency rigid and flexible perovskite solar cell device.

Description

Technical Field

[0001] The present invention belongs to the field of annealing processes, and particularly relates to a method for preparing perovskite thin films based on spatial thermal gradient annealing and a solar cell. Background Art

[0002] For the preparation of organic-inorganic hybrid perovskite thin films, annealing treatment is required. The annealing temperature is generally between 100 - 150 °C. Annealing treatment can improve the crystallization quality of perovskite thin films, such as increasing the grain size and reducing the density of defect states, which is crucial for improving the efficiency of solar cells. Currently, the control of the annealing process mainly includes: (1) gradient annealing on the time scale, that is, first performing low-temperature annealing on the pre-treated perovskite thin film to form an intermediate-phase thin film, and then performing high-temperature annealing; (2) introducing an appropriate solvent atmosphere during the annealing process to slow down crystallization and increase the grain size; (3) vacuum-assisted annealing, that is, first placing the pre-treated perovskite thin film in a vacuum environment for a period of time, and then performing high-temperature annealing to achieve crystallization regulation and obtain high-efficiency solar cells.

[0003] However, in the existing annealing processes, the substrate is completely placed on a hot stage for annealing. This traditional annealing process will introduce a bottom-up temperature gradient in the direction perpendicular to the perovskite thin film. This vertical temperature gradient may cause the perovskite to start crystallizing simultaneously from the top and bottom directions, resulting in more grain boundaries and defects. In particular, the difference in thermal expansion coefficients between the perovskite thin film and the substrate often introduces tensile strain at the interface between the perovskite and the substrate, affecting the device efficiency and stability. Summary of the Invention

[0004] The present invention is made to solve the above problems, and aims to provide a method for preparing perovskite thin films based on spatial thermal gradient annealing and a solar cell.

[0005] The present invention provides a method for preparing perovskite thin films based on spatial thermal gradient annealing, having the following characteristics, including the following steps: Step 1, preparing a perovskite precursor solution; Step 2, using the perovskite precursor solution to prepare a pre-treated perovskite thin film; Step 3, performing spatial thermal gradient annealing on the pre-treated perovskite thin film to obtain a perovskite thin film.

[0006] In the method for preparing perovskite thin films based on spatial thermal gradient annealing provided by the present invention, it may also have the following characteristics: wherein, Step 1 specifically includes the following steps: Step 1-1, according to the perovskite molecular formula (FAPbI3) 0.95 (MAPbBr3) 0.05Based on the stoichiometry shown, the solubility of formamidinium hydroiodide (FAI), lead iodide (PbI2), methylammonium bromide (MABr), and lead bromide (PbBr2) was calculated. Additionally, an excess of PbI2 and 0.3 M - 0.5 M methylammonium chloride (MACl) were added as additives; in Step 1-2, the mixed solution was dissolved. The solvents were dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). After heating and dissolving for 1 - 3 h, it was set aside at a temperature of 50°C - 70°C to obtain the perovskite precursor solution. The solubilities of formamidinium hydroiodide, lead iodide, methylammonium bromide, and lead bromide were 1.4 M, 1.4 M, 0.074 M, and 0.074 M respectively.

[0007] In the method for preparing a perovskite thin film based on spatial thermal gradient annealing provided by the present invention, it may further have the following characteristics: Among them, in Step 1-1, the molar ratio of the additive methylammonium chloride is 20% - 40%, and in Step 1-2, the volume ratio of dimethylformamide to dimethyl sulfoxide is 9:1.

[0008] In the method for preparing a perovskite thin film based on spatial thermal gradient annealing provided by the present invention, it may further have the following characteristics: Among them, Step 2 specifically includes the following steps: Step 2-1, spin-coating a diluted tin oxide solution on the substrate for the first spin-coating; Step 2-2, annealing the substrate under vacuum conditions for 30 - 50 min at an annealing temperature of 70°C - 90°C; Step 2-3, transferring the substrate into a glove box filled with nitrogen, and using a pipette to take 40 - 60 μL of the perovskite precursor solution and drop it on the surface of the cooled substrate; Step 2-4, performing a second spin-coating on the substrate to prepare a pre-treated perovskite thin film.

[0009] In the method for preparing a perovskite thin film based on spatial thermal gradient annealing provided by the present invention, it may further have the following characteristics: Among them, in Step 2-1, the substrate is a rigid glass substrate or a flexible PEN substrate covered with a patterned ITO electrode. The conditions for the first spin-coating are: rotation speed 2500 - 3500 rad / s, time 25 - 35 s. In Step 2-4, the conditions for the second spin-coating are: rotation speed 4500 - 5500 rad / s, time 25 - 35 s, and 250 - 350 μL of diethyl ether is dropped as an anti-solvent 10 - 15 s before the spin-coating stops.

[0010] In the method for preparing a perovskite thin film based on spatial thermal gradient annealing provided by the present invention, it may further have the following characteristics: wherein, in step 3, the pretreated perovskite thin film is transferred from the glove box to the environmental simulation chamber for spatial thermal gradient annealing treatment. The process of spatial thermal gradient annealing treatment is as follows: Step 3-1, one side of the substrate is padded with a wooden chip to create a distance gradient between the substrate and the hot stage, and a temperature gradient is introduced in the in-plane direction parallel to the substrate; Step 3-2, the wooden chip is removed, and the annealing treatment of the pretreated perovskite thin film is continued to obtain the perovskite thin film.

[0011] In the method for preparing a perovskite thin film based on spatial thermal gradient annealing provided by the present invention, it may further have the following characteristics: wherein, the temperature in the environmental simulation chamber is 25-35 °C, and the humidity is 20-40%.

[0012] The present invention provides a solar cell, which has the following characteristics: the solar cell is prepared by performing a series of treatments on the perovskite thin film. The series of treatments are as follows: Step 4, the perovskite thin film is first surface-treated, then the hole transport layer Spiro-OMeTAD is prepared, then the metal electrode is deposited, and finally a high-efficiency rigid and flexible perovskite solar cell device is obtained. The effective area of the solar cell device is 0.1 cm 2 -0.2 cm 2 . The perovskite thin film is prepared by the method for preparing a perovskite thin film based on spatial thermal gradient annealing of the present invention.

[0013] In the solar cell provided by the present invention, it may further have the following characteristics: wherein, the series of treatments specifically include the following steps: Step 4-1, after the annealing of the perovskite thin film is completed, it is immediately transferred to the glove box and waited to be completely cooled; Step 4-2, the cooled perovskite thin film is first spin-coated with a phenylamine iodide salt solution for the third spin-coating; Step 4-3, 30 min after the third spin-coating, the preparation of the hole transport layer Spiro-OMeTAD solution is continued; Step 4-4, 40-60 μL of a Spiro-OMeTAD solution with a concentration of 70-75 mg / mL is taken and dropped on the surface of the perovskite thin film for the fourth spin-coating; Step 4-5, the metal electrode is deposited, and finally a high-efficiency rigid and flexible perovskite solar cell is obtained. Among them, in step 4-3, the Spiro-OMeTAD solution is doped with Li salt, Co salt, and tBP.

[0014] In the solar cell provided by the present invention, it may further have the following characteristics: in step 4-2, the concentration of the phenethylamine iodide salt solution is 3-6 mg / mL, and the solvent is isopropanol. The conditions for the third spin coating are: the rotation speed is 4500-5500 rad / s, and the time is 25-35 s. In step 4-3, the conditions for the fourth spin coating are: the rotation speed is 2500-3500 rad / s, and the time is 25-35 s.

[0015] Functions and effects of the invention

[0016] According to the method for preparing a perovskite thin film based on spatial thermal gradient annealing involved in the present invention, the specific preparation steps are as follows: step 1, preparing a perovskite precursor solution; step 2, using the perovskite precursor solution to prepare a pretreated perovskite thin film; step 3, performing spatial thermal gradient annealing treatment on the pretreated perovskite thin film to obtain a perovskite thin film; the preparation steps of the solar cell are as follows: step 4, first performing surface treatment on the perovskite thin film, secondly preparing a hole transport layer Spiro-OMeTAD, thirdly performing spin coating preparation, and finally depositing a metal electrode, and finally obtaining a high-efficiency rigid or flexible perovskite solar cell device.

[0017] Therefore, in the method for preparing a perovskite thin film based on spatial thermal gradient annealing and the solar cell involved in the present invention, by managing the thermal distribution during the annealing process, a temperature gradient distribution at the spatial scale is introduced on the substrate, effectively regulating the crystallization process and direction of the perovskite, realizing the effective release of strain in the perovskite thin film, and improving the perovskite crystallization quality. Finally, a high-efficiency rigid or flexible perovskite solar cell is obtained.

[0018] In addition, the traditional annealing process for perovskite thin films is directly carried out by completely placing the substrate on a hot plate with a uniformly heated surface. Although there is a uniform thermal distribution in the plane parallel to the substrate, there is a temperature gradient in the direction perpendicular to the substrate. This temperature gradient affects the crystallization process, such as increasing the crystallization rate, causing phase separation, and inducing strain.

[0019] Finally, to solve the adverse effect of the vertical temperature gradient on the crystallization quality of the perovskite thin film, the present invention adopts a spatial thermal gradient annealing process to change the perovskite crystallization direction from the traditional "bottom-up" crystallization to the crystallization from the side of the substrate close to the hot plate to the side away from the hot plate. This method helps to reduce the crystallization rate, increase the grain size, reduce defects, and release the strain in the thin film. Brief description of the drawings

[0020] Figure 1 It is a schematic diagram of the spatial thermal gradient annealing treatment process in Example 1 of the present invention;

[0021] Figure 2It is the structural diagram of the perovskite solar cell device in Embodiment 1 of the present invention;

[0022] Figure 3 It is the comparison diagram of the grain sizes of the perovskite thin films obtained by the spatial thermal gradient annealing process method and the traditional annealing method in Embodiment 1 of the present invention, where Figure 3 (a) of which is the traditional annealing method, Figure 3 (b) of which is the spatial thermal gradient annealing process method;

[0023] Figure 4 It is the comparison diagram of the in-plane tensile strain of the perovskite thin films obtained by the spatial thermal gradient annealing process method and the traditional annealing method in Embodiment 1 of the present invention, where Figure 4 (a) of which is the traditional annealing method, Figure 4 (b) of which is the spatial thermal gradient annealing process method;

[0024] Figure 5 It is the efficiency schematic diagram of the rigid perovskite solar cell and the flexible perovskite solar cell prepared based on the spatial thermal gradient annealing process in Embodiments 1 and 2 of the present invention, where Figure 5 (a) of which is the rigid device, Figure 5 (b) of which is the flexible device;

[0025] Figure 6 It is the schematic diagram of the spatial thermal gradient annealing treatment process in Embodiment 3 of the present invention. Detailed implementation manners

[0026] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the following embodiments will specifically elaborate on a perovskite thin film preparation method and a solar cell based on spatial thermal gradient annealing of the present invention in conjunction with the accompanying drawings.

[0027] <Embodiment 1>

[0028] In this embodiment, a preparation method of a perovskite thin film based on spatial thermal gradient annealing is provided.

[0029] The preparation method of the perovskite thin film based on spatial thermal gradient annealing involved in this embodiment includes the following steps:

[0030] Step S1, preparing a perovskite precursor solution. Specifically, it includes the following steps:

[0031] Step S1-1, according to the perovskite molecular formula (FAPbI3) 0.95 (MAPbBr3) 0.05The stoichiometric ratios shown in the figure were used to calculate the solubilities of FAI, PbI2, MABr, and PbBr2, which were 1.4 M, 1.4 M, 0.074 M, and 0.074 M, respectively. Excess PbI2 and 0.4 M MACl were added as additives.

[0032] Step S1-2, dissolving the mixed solution, the solvent is DMF and DMSO, the volume ratio is 9:1. Heat and dissolve for 2 hours, the temperature is 60°C, and the perovskite precursor solution is obtained.

[0033] Step S2, using a perovskite precursor solution to prepare a pre-treated perovskite film, specifically comprising the following steps:

[0034] Step S2-1, spin coating a diluted SnO2 solution on a rigid glass substrate covered with a patterned ITO electrode, the spin coating conditions being: a rotation speed of 3000 rad / s and a time of 30 seconds.

[0035] Step S2-2, annealing the substrate under vacuum conditions for 40 minutes at an annealing temperature of 80°C.

[0036] Step S2-3, transfer the rigid substrate into a glove box filled with nitrogen, use a pipette to take 50 μL of the perovskite precursor solution, and drop it on the cooled substrate surface.

[0037] Step S2-4, spin coating the substrate, the spin coating conditions are: rotation speed of 5000 rad / s, time of 30 seconds, and 10-15 seconds before stopping the spin coating, 300 μL of ether is added as an anti-solvent.

[0038] Step S3, subjecting the pretreated perovskite film to a spatial thermal gradient annealing treatment to obtain a perovskite film, wherein the pretreated perovskite film is transferred from the glove box to an environmental simulation box (temperature 30° C., humidity 30%) for a spatial thermal gradient annealing treatment.

[0039] Figure 1 It is a schematic diagram of the spatial thermal gradient annealing process in Example 1 of the present invention.

[0040] like Figure 1 As shown, the process of spatial thermal gradient annealing is:

[0041] Step S3-1, one side of the substrate is padded with wood chips so that there is a distance gradient between the substrate and the heat stage, and a temperature gradient is introduced in the in-plane direction parallel to the substrate.

[0042] Step S3-2, removing the wood chips and continuing to anneal the pretreated perovskite film to obtain a perovskite film.

[0043] In the first step, the perovskite crystallization is basically completed, so the spatial thermal gradient distribution has an obvious influence on the perovskite crystallization process. The second-step treatment is to further improve the crystallization quality and remove the residual additives (such as MACl) in the perovskite thin film.

[0044] This embodiment also provides a rigid solar cell photovoltaic device.

[0045] Step S4: First, perform surface treatment on the perovskite thin film, secondly, prepare the hole transport layer Spiro-OMeTAD, then perform spin coating preparation, and finally deposit the metal electrode to finally obtain a high-efficiency rigid perovskite solar cell device. Specifically, it includes the following steps:

[0046] Step S4-1: After the perovskite thin film annealing is completed, immediately transfer it to the glove box and wait for it to cool completely.

[0047] Step S4-2: First, spin coat the cooled perovskite thin film with a solution of phenethylamine iodide (PEAI) for surface treatment. The concentration of PEAI is 5 mg / mL and the solvent is isopropanol. The spin coating conditions are: rotation speed 5000 rad / s, time 30 s.

[0048] Step S4-3: After spin coating for 30 min, continue to prepare the hole transport layer Spiro-OMeTAD.

[0049] Step S4-4: Take 50 μL of a Spiro-OMeTAD solution with a concentration of 72.3 mg / mL (doped with Li salt, Co salt and tBP), drop it on the surface of the perovskite thin film, and perform spin coating preparation. The spin coating conditions are: rotation speed 3000 rad / s, time 30 s.

[0050] Step S4-5: Deposit the metal electrode to finally obtain a high-efficiency rigid perovskite solar cell.

[0051] Figure 2 It is the structural diagram of the perovskite solar cell device in Embodiment 1 of the present invention.

[0052] As Figure 2 shown, the effective area of the device is 0.105 cm 2 .

[0053] Figure 3 It is the comparison diagram of the grain size of the perovskite thin film obtained by the spatial thermal gradient annealing process method and the traditional annealing method in Embodiment 1 of the present invention, where Figure 3 (a) is the traditional annealing method, Figure 3 (b) is the spatial thermal gradient annealing process method.

[0054] As Figure 3As shown, through spatial thermal gradient annealing, the grain size of the perovskite film is finally significantly increased. The increased grain size helps reduce grain boundaries and defects, thereby improving the photovoltaic performance.

[0055] Figure 4 Figure 4 is a comparison diagram of the in-plane tensile strain of the perovskite film obtained by the spatial thermal gradient annealing process method in Example 1 of the present invention and the traditional annealing method, where Figure 4 (a) is the traditional annealing method, Figure 4 (b) is the spatial thermal gradient annealing process method.

[0056] As Figure 4 shown, in the traditional annealing method, due to the interfacial anchoring effect, there is a large in-plane tensile strain from bottom to top. For spatial thermal gradient annealing, since in the initial stage of annealing, during the perovskite crystallization process, the crystal can freely contract, the resulting perovskite film has a smaller tensile strain. And the effective release of the tensile strain helps enhance the stability of the perovskite film and the device.

[0057] <Example 2>

[0058] In this example, a method for preparing a flexible solar cell photovoltaic device based on perovskite film with spatial thermal gradient annealing is provided.

[0059] The method for preparing a flexible solar cell photovoltaic device based on perovskite film with spatial thermal gradient annealing involved in this example is similar to that in Example 1, except that the substrate in step S2-1 and subsequent steps is a flexible PEN substrate.

[0060] Figure 5 Figure 6 is a schematic diagram of the efficiency of the rigid perovskite solar cell and the flexible perovskite solar cell prepared by the spatial thermal gradient annealing process in Examples 1 and 2 of the present invention, where Figure 5 (a) is the rigid device, Figure 5 (b) is the flexible device.

[0061] As Figure 5 shown, based on the spatial thermal gradient annealing process, the efficiencies of the prepared rigid and flexible perovskite solar cells reach 22.83% and 21.04% respectively.

[0062] <Example 3>

[0063] In this example, a method for preparing a perovskite film based on spatial thermal gradient annealing is provided.

[0064] The method for preparing perovskite thin films based on spatial thermal gradient annealing involved in this embodiment is similar to that of Embodiment 1, except that the spatial thermal gradient annealing treatment device in step S3 is different. In this embodiment, it is achieved by designing a heating device with a certain temperature gradient.

[0065] Figure 6 It is a schematic diagram of the spatial thermal gradient annealing treatment process in Embodiment 3 of the present invention.

[0066] As Figure 6 shown, during the first-step annealing, a heating stage with a designed temperature gradient can be used to achieve spatial thermal gradient annealing of the perovskite pre-treatment thin film.

[0067] Functions and effects of the embodiment

[0068] According to the method for preparing perovskite thin films based on spatial thermal gradient annealing involved in the above embodiment, the specific preparation steps are as follows: Step 1, prepare a perovskite precursor solution; Step 2, use the perovskite precursor solution to prepare a pre-treated perovskite thin film; Step 3, perform spatial thermal gradient annealing treatment on the pre-treated perovskite thin film to obtain a perovskite thin film; the preparation steps of a solar cell are as follows: Step 4, first perform surface treatment on the perovskite thin film, secondly prepare a hole transport layer of Spiro-OMeTAD, then perform spin coating preparation, and finally deposit a metal electrode to finally obtain a high-efficiency rigid or flexible perovskite solar cell device.

[0069] Therefore, the method for preparing perovskite thin films based on spatial thermal gradient annealing and the solar cell involved in the above embodiment manage the thermal distribution during annealing to introduce a temperature gradient distribution on a spatial scale on the substrate, effectively regulate the perovskite crystallization process and direction, achieve effective release of strain in the perovskite thin film, and improve the perovskite crystallization quality. Finally, a high-efficiency rigid and flexible perovskite solar cell is obtained.

[0070] In addition, the traditional annealing process for perovskite thin films is to directly place the substrate completely on a hot stage with a uniformly heated surface. Although there is a uniform thermal distribution in the plane parallel to the substrate, there is a temperature gradient in the direction perpendicular to the substrate. This temperature gradient has an impact on the crystallization process, such as increasing the crystallization rate, causing phase separation, and inducing strain.

[0071] Finally, to solve the adverse effect of the vertical temperature gradient on the crystallization quality of the perovskite thin film, the above embodiment adopts a spatial thermal gradient annealing process to change the perovskite crystallization direction from the traditional "bottom-up" crystallization to crystallization from the side of the substrate close to the hot stage to the side away from the hot stage. This method helps to reduce the crystallization rate, increase the grain size, reduce defects, and release the strain in the thin film.

[0072] The above embodiments are preferred examples of the present invention and are not used to limit the protection scope of the present invention.

Claims

1. A method for preparing perovskite thin films based on spatial thermal gradient annealing, characterized in that, It includes the following steps: Step 1, preparing a perovskite precursor solution; Step 2, using the perovskite precursor solution to prepare a pretreated perovskite film on a substrate in a glove box; Step 3, transferring the substrate with the pretreated perovskite film from the glove box to an environmental simulation chamber for spatial thermal gradient annealing treatment to obtain a perovskite film, wherein, the process of performing the spatial thermal gradient annealing treatment is as follows: Step 3-1, propping up one side of the substrate with a wooden chip to create a distance gradient between the substrate and the hot stage, and introducing a temperature gradient in the in-plane direction parallel to the substrate; Step 3-2, removing the wooden chip and continuing the annealing treatment on the pretreated perovskite film to obtain a treated perovskite film.

2. The method for preparing perovskite thin films based on spatial thermal gradient annealing according to claim 1, characterized in that: Wherein, Step 1 specifically includes the following steps: Step 1-1, according to the perovskite molecular formula (FAPbI3) 0.95 (MAPbBr3) 0.05 Dissolve 1.4M formamidinium hydroiodide, 1.4M lead iodide, 0.074M methylammonium bromide, and 0.074M lead bromide in a solvent to obtain a mixed solution according to the stoichiometric ratio shown. Additionally, add an excess of lead iodide and 0.3M - 0.5M methylamine chloride as additives. The solvent is dimethylformamide and dimethyl sulfoxide; Step 1-2, heating the mixed solution obtained in Step 1-1 for 1-3 h and then setting it aside at a temperature of 50°C - 70°C to obtain the perovskite precursor solution.

3. The method for preparing perovskite thin films based on spatial thermal gradient annealing according to claim 2, characterized in that: Wherein, In Step 1-1, the volume ratio of dimethylformamide to dimethyl sulfoxide is 9:

1.

4. The method for preparing perovskite thin films based on spatial thermal gradient annealing according to claim 1, It is characterized in that: wherein, Step 2 specifically includes the following steps: Step 2-1, spin-coating a diluted tin oxide solution on the substrate for the first spin-coating; Step 2-2, annealing the substrate under vacuum conditions for 30-50 min at an annealing temperature of 70°C - 90°C; Step 2-3, transferring the substrate into a glove box filled with nitrogen, using a pipette to take 40-60 μL of the perovskite precursor solution, and dropping it on the cooled surface of the substrate; Step 2-4, performing a second spin-coating on the substrate to prepare the pretreated perovskite film.

5. The method for preparing perovskite thin films based on spatial thermal gradient annealing according to claim 4, characterized in that: Wherein, In Step 2-1, the substrate is a rigid glass substrate or a flexible PEN substrate covered with a patterned ITO electrode, the conditions for the first spin-coating are: rotation speed 2500-3500 rad / s, time 25-35 s, in Step 2-4, the conditions for the second spin-coating are: rotation speed 4500-5500 rad / s, time 25-35 s, and 250-350 μL of ethyl ether is dropped as an anti-solvent 10-15 s before the spin-coating stops.

6. The method for preparing perovskite thin films based on spatial thermal gradient annealing according to claim 1, characterized in that: Wherein, The temperature in the environmental simulation chamber is 25-35°C, and the humidity is 20-40%.

7. A solar cell, characterized in that: The solar cell is prepared by performing a series of treatments on the perovskite film, the series of treatments are: Step 4, first performing surface treatment on the perovskite film, then preparing a hole transport layer of Spiro-OMeTAD, then depositing a metal electrode, and finally obtaining a high-efficiency perovskite solar cell device, The effective area of the solar cell device is 0.1 cm 2 - 0.2 cm 2 , the perovskite film is prepared by the perovskite film preparation method based on spatial thermal gradient annealing described in any one of claims 1-6.

8. The solar cell according to claim 7, wherein: wherein The series of treatments specifically include the following steps: Step 4-1, after the annealing of the treated perovskite film is completed, immediately transfer it into the glove box and wait for it to cool completely; Step 4-2, first spin-coating a phenethylamine iodide salt solution on the cooled perovskite film for the third spin-coating; Step 4-3: 30 minutes after the third spin coating, continue to prepare the hole transport layer Spiro-OMeTAD solution; Step 4-4: Take 40-60 μL of the Spiro-OMeTAD solution with a concentration of 70-75 mg / mL, drop it on the surface of the perovskite film, and perform the fourth spin coating; Step 4-5: Deposit the metal electrode to finally obtain a high-efficiency perovskite solar cell. Among them, in Step 4-3, the Spiro-OMeTAD solution is doped with Li salt, Co salt, and tBP.

9. The solar cell according to claim 8, wherein: wherein In Step 4-2, the concentration of the phenethylamine iodide salt solution is 3-6 mg / mL, and the solvent is isopropanol. The conditions for the third spin coating are: rotation speed 4500-5500 rad / s, time 25-35 s. In Step 4-3, the conditions for the fourth spin coating are: rotation speed 2500-3500 rad / s, time 25-35 s.

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