Flexible tin-lead perovskite solar cell and preparation method thereof

Abstract

The invention belongs to the field of solar cells, and particularly relates to a flexible tin-lead perovskite solar cell and a preparation method thereof.A passivation solution is introduced between a tin-lead perovskite light absorption layer and an electron transport layer for passivation treatment, and due to the fact that the passivation solution contains C = O groups or-NH2, the flexible tin-lead perovskite solar cell can be applied to the field of solar cells. The coordination with Sn < 2 + > and Pb < 2 + > in the perovskite light absorption layer can be simultaneously generated, and the defects existing at the perovskite interface can be obviously passivated. Therefore, the tin-lead perovskite solar cell can play a role in inhibiting oxidation of the perovskite layer, and meanwhile, the non-radiative recombination condition of current carriers is reduced, so that the performance of the tin-lead perovskite solar cell is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the field of solar cells, and in particular relates to a flexible tin-lead perovskite solar cell and a preparation method thereof. Background Art

[0002] Organic metal halide perovskite solar cells have made rapid progress in the past decade due to their excellent optical properties, long carrier lifetime, high carrier mobility and many other excellent properties. At present, the highest certified efficiency of single-junction perovskite solar cells has rapidly increased to over 25%, but the band gap of single-junction perovskite solar cells is between 1.5ev and 1.7ev, and its theoretical maximum efficiency is about 30%. It has now reached 85%, so there is limited room for further improvement. The stacked perovskite solar cells with high and low band gaps can make full use of the solar spectrum and have higher theoretical efficiency, which is called an important way to break through the theoretical limit of single-junction perovskite solar cells.

[0003] Among the many types of stacked perovskite solar cells, all-perovskite solar cells have a lower Young's modulus, are compatible with flexible substrates, and have a higher power-to-weight ratio, which greatly broadens the application range of perovskite solar cells. As an important component of all-perovskite solar cells, high-performance narrow-bandgap perovskite solar cells play an important role in the preparation of efficient and stable all-perovskite solar cells. In narrow-bandgap perovskite solar cells, the introduction of tin will accelerate the crystallization rate of the perovskite light-absorbing layer, thereby affecting its crystallization quality. In addition, perovskite solar cells are multi-layer thin film composite structures, and the interface between the functional layer and the perovskite light-absorbing layer is an important channel for oxygen in the air to enter the battery. Oxygen will cause the Sn in the perovskite layer to 2+ Oxidized to Sn 4+ , and a large number of defects are generated in the interface and bulk phase, and the generation of defects will further aggravate the entry of oxygen and the oxidation of narrow-bandgap tin perovskite solar cells. Therefore, studying how to effectively passivate the defects at the interface and prepare a high-quality perovskite light-absorbing layer is of great significance for obtaining high-performance narrow-bandgap perovskite solar cells. Summary of the invention

[0004] The purpose of the present invention is to provide a flexible tin-lead perovskite solar cell and a preparation method thereof, so as to solve the problem that the Sn in the perovskite layer is degraded due to oxygen in the existing tin-lead perovskite solar cell. 2+ Oxidized to Sn 4+ , and a large number of defects are generated in the interface and bulk phase, causing the problem of low crystallization quality of the perovskite layer, ultimately achieving an improvement in the efficiency of tin-lead perovskite solar cells.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A flexible tin-lead perovskite solar cell comprises a flexible conductive substrate, a hole transport layer, a tin-lead perovskite light absorption layer, an electron transport layer, a buffer layer, and a metal electrode layer which are stacked in sequence from bottom to top, and also comprises an interface passivation layer, wherein the interface passivation layer is embedded between the tin-lead perovskite light absorption layer and the electron transport layer, and the interface passivation layer is an ionic compound, wherein the cation contains an amino group and a benzene ring, and the anion contains -C=O, -OH.

[0007] Furthermore, the interface passivation layer material is one of 4-phenylbutane-1-amine acetate, 2,2,2-trifluoroacetic acid-N-ethylaniline, ammonium benzoate, phenylethylamine acetate, ammonium acetate, dopamine 4-β-D-glucuronic acid, β-hydroxy-α-methylphenethylammonium [R-(R*, R*)]-tartrate hydrogen or a mixture of at least two of them in any proportion.

[0008] Furthermore, the thickness of the tin-lead perovskite light-absorbing layer is 500nm-1000nm, the thickness of the electron transport layer is 50-150nm, the thickness of the buffer layer is 100nm-200nm; and the thickness of the metal electrode is 100nm-200nm.

[0009] Furthermore, the flexible conductive substrate is one or more of ITO conductive glass, FTO conductive glass, ITO-coated flexible transparent plastic PET or nano conductive substrate;

[0010] The electron transport layer is one or more of fullerene or PCBM; the buffer layer is one of TiO2, NiO or YbOx; and the metal electrode is a Cu electrode, an Au electrode or an Ag electrode.

[0011] A method for preparing a flexible tin-lead perovskite solar cell comprises the following steps:

[0012] Step 1, treating the transparent conductive substrate with plasma or ozone for 5 to 40 minutes;

[0013] Step 2: spin-coating a hole transport layer solution on the transparent conductive substrate treated in step 1 to prepare a hole transport layer; the hole transport layer solution includes one or more of (3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT:PSS), 2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACZ), 3-(9-carbazolyl)propionic acid (9CPA), and 9-carbazolylacetic acid (9CAA);

[0014] Step 3, using an anti-solvent method to spin-coat a tin-lead perovskite light absorbing layer precursor solution on the hole-forming surface to prepare a tin-lead perovskite light absorbing layer;

[0015] Step 4, preparing an interface passivation layer on the surface of the tin-lead perovskite light absorbing layer;

[0016] Step 5: sequentially prepare an electron transport layer and a buffer layer on the surface of the interface passivation layer by physical vapor deposition or spin coating;

[0017] Step 6: Prepare a metal electrode on the surface of the buffer layer by using an evaporation coating method or a physical vapor deposition method to obtain a flexible tin-lead perovskite solar cell.

[0018] Furthermore, the tin-lead perovskite light-absorbing layer is prepared according to method one or method two, wherein:

[0019] Method 1 is specifically described as follows: preparing a tin-lead perovskite light-absorbing layer precursor solution, dropping the perovskite precursor solution on the hole transport layer, first spin-coating the dropped perovskite precursor solution at a speed of 500rpm-2000rpm for 5-20s, and then spin-coating the perovskite precursor solution at a speed of 4000rpm-5000rpm for 30-50s, and the total spin-coating time for the two times is 35-60s, wherein 100-200 microliters of anti-solvent is dropped on the surface after a total spin coating of 30-45s, and the spin coating is continued, and after the spin coating is completed, annealing is performed at a temperature of 80°C-120°C for 10-30min to obtain a tin-lead perovskite light-absorbing layer;

[0020] Method 2 is specifically described as follows: prepare a perovskite precursor solution, drop the perovskite precursor solution on the hole transport layer, spin coat the dropped perovskite precursor solution at a speed of 3000-5000 rpm for 40-60 seconds, blow N2 gas flow over the rotating substrate for 30-40 seconds 15-20 seconds after the start of spin coating, anneal at 150°C for 10-20 minutes after the spin coating is completed, and obtain a tin-lead perovskite light absorbing layer.

[0021] Furthermore, the components of the perovskite precursor solution are: a perovskite solution of formamidine iodide (FAI), methylamine iodide (MAI), cesium iodide (CsI), lead iodide (PbI2), stannous iodide (SnI2), stannous fluoride (SnF2), and a solution of an organic solvent, wherein the proportion of each component is: 0.6-0.7 Cs 0.3-0.4 Pb 0.4-0.5 Sn 0.4-0.5 I3, wherein the concentration of PbI2 is 500-650 mg / ml; wherein the organic solvent is a mixed solvent of DMF and DMSO, and the ratio of DMF to DMSO is 3-10:1; and the anti-solvent is one or a mixture of chlorobenzene, ethyl acetate, methyl phenyl ether, and toluene.

[0022] Furthermore, the interface passivation layer is prepared by spin coating, and the specific steps are as follows:

[0023] The passivation material is dissolved in an organic solvent to prepare a passivation solution with a concentration of ≤20 mg / ml, and the passivation solution is spin-coated on the surface of the tin-lead perovskite light-absorbing layer.

[0024] The flexible tin-lead perovskite solar cell and its preparation method of the present invention improve the preparation process of the tin-lead perovskite solar cell light-absorbing layer, that is, by controlling the spin coating speed, and coordinating the time of anti-solvent dripping or air flow blowing, the crystal quality of the perovskite film and the spectral absorption are improved. On this basis, a passivation solution is introduced between the tin-lead perovskite light-absorbing layer and the electron transport layer for passivation treatment. Since the C=O group or -NH2 contained in the passivation solution can simultaneously react with the Sn in the perovskite light-absorbing layer, the passivation solution can be used to passivate the light-absorbing layer of the perovskite. 2+ and Pb 2+ Produce coordination effect, significantly passivate the defects existing at the perovskite interface. Because of this, it can inhibit the oxidation of the perovskite layer, while reducing the non-radiative recombination of carriers, thereby greatly improving the performance of tin-lead perovskite solar cells. The beneficial effects of the present invention are: by introducing a passivation layer, the open circuit voltage and short circuit current of the tin-lead perovskite solar cell can be significantly improved, and the yield of the battery can also be significantly improved, which is undoubtedly more conducive to the long-term use of the battery. In addition, due to the introduction of the passivation layer, the interface defects are reduced, so the long-term stability of the perovskite solar cell is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of a tin-lead perovskite solar cell according to Example 1;

[0026] Figure 2 The current-voltage curve diagram of Example 1 and the comparative example;

[0027] Figure 3 This is a quantum efficiency diagram of Example 1 and a comparative example;

[0028] Figure 4 The Sn-Pb perovskite polycrystalline layer Sn of Example 1 and Comparative Example 2+ XPS spectrum;

[0029] Figure 5 The tin-lead perovskite polycrystalline layer Pb of Example 1 and Comparative Example 2+ XPS spectrum;

[0030] Reference numerals:

[0031] 1 is a glass substrate, 2 is an adhesive layer, 3 is a flexible conductive substrate, 4 is a hole transport layer, 5 is a tin-lead perovskite light absorption layer, 6 is an electron transport layer buffer layer, 7 is a buffer layer, 8 is a metal electrode layer, and 9 is an interface passivation layer. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0033] A flexible tin-lead perovskite solar cell provided in this embodiment includes a flexible conductive substrate 3, a hole transport layer 4, a tin-lead perovskite light absorption layer 5, an electron transport layer 6, a buffer layer 7, and a metal electrode layer 8 stacked in sequence from bottom to top, and also includes an interface passivation layer 9, which is embedded between the tin-lead perovskite light absorption layer 5 and the electron transport layer 6, and the interface passivation layer 9 is an ionic compound, in which the cation contains an amino group and a benzene ring, and the anion contains -C=O, -OH.

[0034] By providing an interface passivation layer 9 between the tin-lead perovskite light absorbing layer 11 and the electron transport layer 6 to passivate defects, the open circuit voltage, short circuit current and yield of the perovskite solar cell are improved, which is more conducive to the long-term use of the perovskite solar cell.

[0035] Specifically:

[0036] Since the benzene ring, -NH2, or C=O group contained in the interface passivation layer 9 can simultaneously react with the Sn in the perovskite light absorption layer, 2+ and Pb 2+ The coordination effect inhibits Sn 2+ In order to prevent the oxidation of the perovskite layer, the interface passivation layer 9 is introduced into the tin-lead perovskite light-absorbing layer 11, which can significantly passivate the defects at the perovskite interface, inhibit the oxidation of the perovskite layer, and reduce the non-radiative recombination of carriers.

[0037] In this embodiment, the interface passivation layer 9 adopts one of 4-phenylbutyl-1-amine acetate, 2,2,2-trifluoroacetic acid-N-ethylaniline, ammonium benzoate, phenylethylamine acetate, ammonium acetate, dopamine 4-β-D-glucuronic acid, β-hydroxy-α-methylphenylethylammonium [R-(R*, R*)]-tartrate hydrogen or at least two of them mixed in any proportion. The thickness of the tin-lead perovskite light absorption layer 11 is 500nm-1000nm, the thickness of the electron transport layer 6 is 50-150nm, the thickness of the buffer layer 7 is 100nm-200nm; the thickness of the metal electrode is 100nm-200nm.

[0038] Embodiment 1

[0039] A method for preparing a tin-lead perovskite solar cell comprises the following steps:

[0040] Step 1: Use an adhesive to adhere the flexible conductive substrate 3 to a glass substrate. The adhesive is one of PDMS, high-temperature double-sided adhesive, PMMA, and polyvinyl alcohol, or a combination of several of them in any proportion.

[0041] Step 2: Plasma or ozone treatment is performed on the transparent conductive substrate for 5 to 40 minutes to improve the wettability of the substrate.

[0042] Step 3: preparing a hole transport layer 4 on a transparent conductive substrate:

[0043] The hole transport layer 4 is prepared from one or more of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT: PSS), 2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACZ), 3-(9-carbazole) propionic acid (9CPA), and 9-carbazole acetic acid (9CAA). In this embodiment, (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT: PSS)) is selected as the hole transport layer 4, and the preparation method is as follows:

[0044] The poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT:PSS) solution is spin-coated on the transparent conductive substrate treated in step 2 by a spin coater, the spin coating speed is 2000rpm-5000rpm, the spin coating time is 20-40s, and after the spin coating is completed, the spin-coated film is placed on a hot table for annealing, the annealing temperature is 80℃-120℃, and the annealing time is 5-30min.

[0045] Step 3: preparing a tin-lead perovskite light absorbing layer 11 on the hole transport layer 4:

[0046] 3.1. Prepare a tin-lead perovskite light absorbing layer 11 precursor solution according to the formula. The components of the perovskite precursor solution are: perovskite solution formamidine iodide (FAI), methylamine iodide (MAI), cesium iodide (CsI), lead iodide (PbI2), stannous iodide (SnI2), stannous fluoride (SnF2), and a solution of an organic solvent, wherein the proportion of each component is: FAI: 0.6-0.7 Cs 0.3-0.4 Pb 0.4- 0.5 Sn 0.4-0.5 I3, wherein the concentration of PbI2 is 500-650 mg / ml; wherein the organic solvent is a mixed solvent of DMF and DMSO, and the ratio of DMF to DMSO is 4:1; and the anti-solvent is one or a mixture of chlorobenzene, ethyl acetate, methyl phenyl ether, and toluene.

[0047] The perovskite precursor solution is dripped onto the hole transport layer 4, and the dripped perovskite precursor solution is spin-coated at a speed of 3000-5000 rpm for 40-60 seconds. The N2 gas flow is turned on for 15-20 seconds after the start of spin coating.

[0048] S is blown over the rotating substrate for 30-40 seconds, and annealed at 150°C for 10-20 minutes after the spin coating is completed, to obtain the tin-lead perovskite light-absorbing layer 11. Since the nitrogen gas flow is introduced to blow over the substrate during spin coating, the solvent in the perovskite precursor solution can be volatilized to a certain extent, so that nucleation centers are formed in the perovskite film, which is more conducive to crystallization in the subsequent annealing process.

[0049] The anti-solvent is one or a mixture of chlorobenzene, ethyl acetate, methyl phenyl ether, and toluene. Chlorobenzene is preferably used as the anti-solvent in this embodiment.

[0050] Step 4: preparing an interface passivation layer 9 on the tin-lead perovskite light absorbing layer 11:

[0051] An appropriate amount of phenylethylamine acetate is dissolved in an organic solvent to prepare a passivation solution with a concentration of 2 mg / ml; the passivation solution is spin-coated on the tin-lead perovskite light-absorbing layer 11 by spin coating, the spin coating speed is 3000rpm-4000rpm, the spin coating time is 20s-40s, and after spin coating, annealing is performed at a temperature of 90°C-110°C.

[0052] Step 5: Prepare the transmission layer and the buffer layer 7 in sequence on the surface of the interface passivation layer 9 by physical vapor deposition.

[0053] Step 6: Prepare a metal electrode on the surface of the buffer layer 7 by physical vapor deposition to obtain a flexible tin-lead perovskite solar cell.

[0054] Embodiment 2

[0055] The preparation method is similar to that of Example 1, except that:

[0056] In step 3: the perovskite precursor solution is dropped onto the hole transport layer 4, and the dropped perovskite precursor solution is first spin-coated at a speed of 500rpm-2000rpm for 5-20s, and then spin-coated at a speed of 4000rpm-5000rpm for 30-50s, and the total spin-coating time for the two times is 35-60s, wherein 100-200 microliters of anti-solvent is dropped onto the surface after a total of 30-45s of spin coating, and the spin coating is continued. After the spin coating is completed, annealing is performed at a temperature of 80°C-120°C for 10-30min to obtain a tin-lead perovskite light absorbing layer 11.

[0057] In step 4: dissolve an appropriate amount of 2,2,2-trifluoroacetic acid-N-ethylaniline in an organic solvent to prepare a passivation solution with a concentration of (5 mg / ml).

[0058] Embodiment 3

[0059] The method is similar to the method in the first embodiment, except that:

[0060] In step 4: an appropriate amount of 4-β-D-glucuronic acid is dissolved in an organic solvent to prepare a passivation solution with a concentration of (8 mg / ml).

[0061] Comparative Example 1

[0062] Similar to Example 1, Example 2, and Example 3, the difference from Example 1 and Example 3 is that no interface passivation layer 9 is provided between the perovskite layer and the hole transport layer 4. Compared with Example 2, the method for preparing the tin-lead perovskite light absorbing layer 11 adopts the preparation method of Example 1, and no interface passivation layer 9 is provided between the perovskite layer and the hole transport layer 4. The structure of Comparative Example 1 is as follows Figure 1 As shown, from bottom to top, they are: glass substrate 1, bonding layer 2, conductive substrate, hole transport layer 4, tin-lead perovskite light absorption layer 11, electron transport layer 6, buffer layer 7, and metal electrode layer 8.

[0063] The voltage-current curves of Example 1 and Comparative Example are shown in Figure 2 , the corresponding performance parameters are shown in Table 1.

[0064] Table 1 Performance comparison table of Example 1 and comparative example

[0065]

[0066] As can be seen from Table 1, compared with the comparative example, Example 1 has greater advantages in short-circuit current, open-circuit voltage, and energy conversion efficiency, which proves that the defects at the bottom interface of the perovskite are effectively passivated through bottom treatment, and the performance of the perovskite solar cell is significantly improved due to the suppression of non-radiative recombination of carriers. Figure 2 The EQE test results of the embodiment and the comparative example are shown. From the results, it can be seen that the EQE integrated current can reach 29.2 mmA / cm 2 , which also verifies the authenticity of the short-circuit current in the JV test.

[0067] Figure 3 , Figure 4 , Figure 5 The XPS spectra of the perovskite light-absorbing layer of Example 1 and the comparative example show that the passivation molecules can make the Sn in the perovskite light-absorbing layer 2+ With Pb 2+ A coordination effect occurs, and it can be seen from the peak separation results that the oxidation of tin is significantly inhibited. The above test results show that since the passivation molecules are anions and cations and contain a variety of functional groups, the cations can fill the A-site ion holes on the surface of the perovskite, and the anions can fill the X-site ion holes on the perovskite. Therefore, after passivation treatment, the passivation of various surface defects can be achieved, the defects can be reduced, and the performance and stability of perovskite solar cells can be improved.

Claims

1. A flexible tin-lead perovskite solar cell, comprising a flexible conductive substrate, a hole transport layer, a tin-lead perovskite light absorption layer, an electron transport layer, a buffer layer, and a metal electrode layer stacked in sequence from bottom to top, characterized in that: It also includes an interface passivation layer, which is embedded between the tin-lead perovskite light absorption layer and the electron transport layer. The interface passivation layer is an ionic compound, in which the cation contains an amino group and a benzene ring, and the anion contains -C=O, -OH.

2. A flexible tin-lead perovskite solar cell according to claim 1, characterized in that: The interface passivation layer material is one of 4-phenylbutane-1-amine acetate, 2,2,2-trifluoroacetic acid-N-ethylaniline, ammonium benzoate, phenylethylamine acetate, ammonium acetate, dopamine 4-β-D-glucuronic acid, β-hydroxy-α-methylphenethylammonium [R-(R*, R*)]-tartrate hydrogen, or a mixture of at least two of them in any proportion.

3. A flexible tin-lead perovskite solar cell according to claim 1, characterized in that: The thickness of the tin-lead perovskite light absorption layer is 500nm-1000nm, the thickness of the electron transport layer is 50-150nm, the thickness of the buffer layer is 100nm-200nm; and the thickness of the metal electrode is 100nm-200nm.

4. A flexible tin-lead perovskite solar cell according to claim 1, characterized in that: The flexible conductive substrate is one or more of ITO conductive glass, FTO conductive glass, flexible transparent plastic PET plated with ITO or a nano conductive substrate.

5. The flexible tin-lead perovskite solar cell according to claim 1, characterized in that: The electron transport layer is one or more of fullerene or PCBM; the buffer layer is one of TiO2, NiO or YbOx; and the metal electrode is a Cu electrode, an Au electrode or an Ag electrode.

6. A method for preparing a flexible tin-lead perovskite solar cell, characterized in that: The following steps are involved: Step 1, treating the transparent conductive substrate with plasma or ozone for 5 to 40 minutes; Step 2: spin-coating the hole transport layer solution on the transparent conductive substrate treated in step 1 to prepare a hole transport layer; The hole transport layer solution includes one or more of (3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT:PSS), 2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACZ), 3-(9-carbazolyl)propionic acid (9CPA), and 9-carbazolylacetic acid (9CAA); Step 3, using an anti-solvent method to spin-coat a tin-lead perovskite light absorbing layer precursor solution on the hole-forming surface to prepare a tin-lead perovskite light absorbing layer; Step 4, preparing an interface passivation layer on the surface of the tin-lead perovskite light absorbing layer; Step 5: sequentially prepare an electron transport layer and a buffer layer on the surface of the interface passivation layer by physical vapor deposition or spin coating; Step 6: Prepare a metal electrode on the surface of the buffer layer by using an evaporation coating method or a physical vapor deposition method to obtain a flexible tin-lead perovskite solar cell.

7. The method for preparing a flexible tin-lead perovskite solar cell according to claim 6, characterized in that: The tin-lead perovskite light-absorbing layer is prepared according to method one or method two, wherein: Method 1 is specifically described as follows: preparing a tin-lead perovskite light-absorbing layer precursor solution, dropping the perovskite precursor solution on the hole transport layer, first spin-coating the dropped perovskite precursor solution at a speed of 500rpm-2000rpm for 5-20s, and then spin-coating the perovskite precursor solution at a speed of 4000rpm-5000rpm for 30-50s, and the total spin-coating time for the two times is 35-60s, wherein 100-200 microliters of anti-solvent is dropped on the surface after a total spin coating of 30-45s, and the spin coating is continued, and after the spin coating is completed, annealing is performed at a temperature of 80°C-120°C for 10-30min to obtain a tin-lead perovskite light-absorbing layer; Method 2 is specifically described as follows: prepare a perovskite precursor solution, drop the perovskite precursor solution on the hole transport layer, spin coat the dropped perovskite precursor solution at a speed of 3000-5000 rpm for 40-60 seconds, blow N2 gas flow over the rotating substrate for 30-40 seconds 15-20 seconds after the start of spin coating, anneal at 150°C for 10-20 minutes after the spin coating is completed, and obtain a tin-lead perovskite light absorbing layer.

8. The method for preparing a flexible tin-lead perovskite solar cell according to claim 7, characterized in that: The components of the perovskite precursor solution are: a perovskite solution of formamidine iodide (FAI), methylamine iodide (MAI), cesium iodide (CsI), lead iodide (PbI2), stannous iodide (SnI2), stannous fluoride (SnF2), and a solution of an organic solvent, wherein the proportion of each component is: FAI 0.6-0.7 Cs 0.3-0.4 Pb 0.4-0.5 Sn 0.4-0.5 I3, wherein the concentration of PbI2 is 500-650 mg / ml; wherein the organic solvent is a mixed solvent of DMF and DMSO, and the ratio of DMF to DMSO is 3-10:1; and the anti-solvent is one or a mixture of chlorobenzene, ethyl acetate, methyl phenyl ether, and toluene.

9. The method for preparing a flexible tin-lead perovskite solar cell according to claim 8, characterized in that: The interface passivation layer is prepared by spin coating, and the specific steps are as follows: The passivation material is dissolved in an organic solvent to prepare a passivation solution with a concentration of ≤20 mg / ml, and the passivation solution is spin-coated on the surface of the tin-lead perovskite light-absorbing layer.

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