A flexible tin-lead perovskite solar cell and its fabrication method

Abstract

This invention belongs to the field of solar cells, specifically a flexible tin-lead perovskite solar cell and its preparation method. Passivation is achieved by introducing a passivation solution between the tin-lead perovskite light-absorbing layer and the electron transport layer. Due to the C=O groups or -NH2 contained in the passivation solution, the Sn in the perovskite light-absorbing layer can simultaneously react with the Sn in the perovskite light-absorbing layer. 2+ and Pb 2+ It generates coordination interactions, significantly passivating defects at the perovskite interface. Therefore, it can inhibit the oxidation of the perovskite layer and reduce non-radiative recombination of charge carriers, thereby greatly improving the performance of tin-lead perovskite solar cells.

Description

Technical Field

[0001] This invention belongs to the field of solar cells, specifically relating to a flexible tin-lead perovskite solar cell and its preparation method. Background Technology

[0002] Organometal halide perovskite solar cells have made rapid progress over the past decade due to their excellent optical performance, long carrier lifetime, and high carrier mobility. Currently, the highest certified efficiency of single-junction perovskite solar cells has rapidly increased to over 25%. However, the bandgap of single-junction perovskite solar cells is between 1.5 eV and 1.7 eV, and their theoretical maximum efficiency is approximately 30%, currently reaching 85%, so further improvement is limited. Tandem perovskite solar cells, which combine high and low bandgap structures, can fully utilize the solar spectrum and possess higher theoretical efficiencies, representing an important approach to breaking the theoretical limits of single-junction perovskite solar cells.

[0003] Among various types of tandem perovskite solar cells, all-perovskite solar cells have a lower Young's modulus, are compatible with flexible substrates, and possess a higher power-to-weight ratio, greatly expanding the application range of perovskite solar cells. As a crucial component of all-perovskite solar cells, high-performance narrow-bandgap perovskite solar cells play a vital role in fabricating efficient and stable all-perovskite solar cells. In narrow-bandgap perovskite solar cells, the introduction of tin accelerates the crystallization rate of the perovskite light-absorbing layer, thus affecting its crystal quality. Furthermore, perovskite solar cells are multilayer thin-film composite structures, and the interface between the functional layer and the perovskite light-absorbing layer is a significant channel for oxygen from the air to enter the cell. Oxygen causes Sn in the perovskite layer to... 2+ Oxidized to Sn 4+ Furthermore, numerous defects are generated at the interface and in the bulk phase, which in turn exacerbate oxygen ingress and oxidation in narrow-bandgap tin perovskite solar cells. Therefore, researching effective passivation techniques for interface defects and fabricating high-quality perovskite light-absorbing layers is of great significance for obtaining high-performance narrow-bandgap perovskite solar cells. Summary of the Invention

[0004] The purpose of this invention is to provide a flexible tin-lead perovskite solar cell and its fabrication method, in order to solve the problem in existing tin-lead perovskite solar cells where oxygen causes Sn in the perovskite layer to become trapped. 2+ Oxidized to Sn 4+ This process generates numerous defects at the interface and in the bulk phase, leading to low crystal quality of the perovskite layer. Ultimately, this resulted in improved efficiency of tin-lead perovskite solar cells.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A flexible tin-lead perovskite solar cell includes, from bottom to top, a flexible conductive substrate, a hole transport layer, a tin-lead perovskite light-absorbing layer, an electron transport layer, a buffer layer, and a metal electrode layer, and further includes an interface passivation layer embedded between the tin-lead perovskite light-absorbing layer and the electron transport layer. 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 and -OH.

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

[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, flexible transparent plastic PET coated with ITO, 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 fabricating a flexible tin-lead perovskite solar cell includes the following steps:

[0012] Step 1: Treat the transparent conductive substrate with plasma or ozone for 5–40 minutes;

[0013] Step 2: The hole transport layer solution is spin-coated onto the transparent conductive substrate treated in Step 1 to prepare the 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)ethylphosphonic acid (2PACZ), 3-(9-carbazole)propionic acid (9CPA), and 9-carbazole acetic acid (9CAA).

[0014] Step 3: Spin-coat the tin-lead perovskite light-absorbing layer precursor solution onto the cavity surface using the anti-solvent method to prepare the tin-lead perovskite light-absorbing layer;

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

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

[0017] Step 6: Prepare a metal electrode on the surface of the buffer layer using evaporation coating or physical vapor deposition 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: Prepare a tin-lead perovskite light-absorbing layer precursor solution. Drop the perovskite precursor solution onto the hole transport layer. First, spin-coat the dropped perovskite precursor solution at a speed of 500 rpm-2000 rpm for 5-20 seconds, and then spin-coat the perovskite precursor solution at a speed of 4000 rpm-5000 rpm for 30-50 seconds. The total spin-coating time is 35-60 seconds. After a total spin-coating time of 30-45 seconds, drop 100-200 μL of anti-solvent onto the surface and continue spin-coating. After spin-coating, anneal at a temperature of 80℃-120℃ for 10-30 minutes to obtain the tin-lead perovskite light-absorbing layer.

[0020] Method 2 is specifically described as follows: Prepare a perovskite precursor solution, drop the perovskite precursor solution onto the hole transport layer, spin coat the drop-on perovskite precursor solution at a speed of 3000-5000 rpm for 40-60 seconds, blow N2 gas through the rotating substrate for 30-40 seconds after the spin coating begins (15-20 seconds after the spin coating begins), and anneal at 150℃ for 10-20 minutes after the spin coating is completed to obtain a tin-lead perovskite light-absorbing layer.

[0021] Furthermore, the perovskite precursor solution comprises: a solution of formamidine iodide (FAI), methylamine iodide (MAI), cesium iodide (CsI), lead iodide (PbI2), stannous iodide (SnI2), stannous fluoride (SnF2), and an organic solvent, wherein the proportions of each component are: FA... 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 mixture of DMF and DMSO, and the ratio of DMF to DMSO is 3-10:1; wherein the antisolvent is one or a mixture of several 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 was dissolved in an organic solvent to prepare a passivation solution with a concentration ≤20mg / ml. The passivation solution was then spin-coated onto the surface of the tin-lead perovskite light-absorbing layer.

[0024] The flexible tin-lead perovskite solar cell and its fabrication method of the present invention improve the fabrication process of the light-absorbing layer of the tin-lead perovskite solar cell by controlling the spin-coating speed and the time of antisolvent drop addition or airflow blowing, thereby enhancing the crystallinity quality and spectral absorption of the perovskite film. Furthermore, by introducing a passivation solution between the tin-lead perovskite light-absorbing layer and the electron transport layer for passivation treatment, the C=O groups or -NH2 contained in the passivation solution can simultaneously react with the Sn in the perovskite light-absorbing layer. 2+ and Pb 2+ The passivation layer generates coordination, significantly passivating defects at the perovskite interface. Therefore, it inhibits oxidation of the perovskite layer and reduces non-radiative recombination of charge carriers, thereby greatly improving the performance of tin-lead perovskite solar cells. The beneficial effects of this invention are: by introducing a passivation layer, the open-circuit voltage and short-circuit current of tin-lead perovskite solar cells can be significantly improved, and the cell yield can also be significantly increased, which is undoubtedly more conducive to long-term use of the cells. Furthermore, since the introduction of the passivation layer reduces interface defects, the long-term stability of the perovskite solar cell is also improved. Attached Figure Description

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

[0026] Figure 2 Examples 1 and 2 (comparative examples) are shown in the current-voltage curve diagrams.

[0027] Figure 3 Quantum efficiency diagrams for Example 1 and the comparative exception;

[0028] Figure 4 The tin-lead perovskite polycrystalline layer Sn of Example 1 and the comparative example 2+ XPS diagrams;

[0029] Figure 5 The polycrystalline Pb-lead perovskite of Example 1 and the comparative example are shown. 2+ XPS diagrams;

[0030] Figure label:

[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-absorbing 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 Implementation

[0032] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0033] This embodiment provides a flexible tin-lead perovskite solar cell, comprising, from bottom to top, a flexible conductive substrate 3, a hole transport layer 4, a tin-lead perovskite light-absorbing layer 5, an electron transport layer 6, a buffer layer 7, and a metal electrode layer 8, and further comprising an interface passivation layer 9, which is embedded between the tin-lead perovskite light-absorbing layer 5 and the electron transport layer 6. The interface passivation layer 9 is an ionic compound, wherein the cation contains an amino group and a benzene ring, and the anion contains -C=O and -OH.

[0034] By setting an interface passivation layer 9 between the tin-lead perovskite light-absorbing layer 11 and the electron transport layer 6, defects are passivated, which improves the open-circuit voltage, short-circuit current, and yield of perovskite solar cells, thus making them more suitable for long-term use.

[0035] Specifically:

[0036] Because the benzene ring, -NH2, or C=O group contained in the interface passivation layer 9 can simultaneously react with Sn in the perovskite light-absorbing layer. 2+ and Pb 2+ Coordination occurs, inhibiting Sn 2+ To mitigate oxidation, an interface passivation layer 9 is introduced into the tin-lead perovskite light-absorbing layer 11, which can significantly passivate defects at the perovskite interface, suppress the oxidation of the perovskite layer, and reduce nonradiative recombination of charge carriers.

[0037] In this embodiment, the interface passivation layer 9 is made of one or a mixture of at least two of the following: 4-phenylbut-1-amine acetate, 2,2,2-trifluoroacetic acid-N-ethylaniline, ammonium benzoate, phenethylamine acetate, ammonium acetate, dopamine 4-β-D-glucuronic acid, and β-hydroxy-α-methylphenylethylammonium [R-(R*,R*)]-hydrogen tartrate. The thickness of the tin-lead perovskite light-absorbing 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, and the thickness of the metal electrode is 100nm-200nm.

[0038] Example 1

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

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

[0041] Step 2: Treat the transparent conductive substrate with plasma or ozone for 5–40 minutes to improve the wettability of the substrate.

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

[0043] The hole transport layer 4 is prepared from one or more of the following materials: poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT: PSS), 2-(9H-carbazole-9-yl)ethylphosphonic 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 was spin-coated onto the transparent conductive substrate treated in step 2 using a spin coater. The spin-coating speed was 2000 rpm-5000 rpm and the spin-coating time was 20-40 s. After spin-coating, the spin-coated film was placed on a hot plate for annealing at a temperature of 80℃-120℃ for 5-30 min.

[0045] Step 3: Prepare 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: a solution of formamidine iodide (FAI), methylamine iodide (MAI), cesium iodide (CsI), lead iodide (PbI2), stannous iodide (SnI2), stannous fluoride (SnF2), and an organic solvent, wherein the proportions of each component are: FA... 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 mixture of DMF and DMSO in a ratio of 4:1; and the antisolvent is one or a mixture of chlorobenzene, ethyl acetate, methyl phenyl ether, and toluene.

[0047] The perovskite precursor solution was drop-added onto hole transport layer 4, and spin-coated at 3000-5000 rpm for 40-60 seconds. N2 gas flow was introduced 15-20 seconds after the start of spin-coating.

[0048] Spin-coating is performed by blowing nitrogen gas through a rotating substrate for 30-40 seconds. After spin-coating, the substrate is annealed at 150°C for 10-20 minutes to obtain the tin-lead perovskite light-absorbing layer 11. The introduction of nitrogen gas through the spin-coated substrate allows for some evaporation of the solvent in the perovskite precursor solution, creating nucleation centers in the perovskite film and facilitating crystallization during subsequent annealing.

[0049] The antisolvent is one or a mixture of several of chlorobenzene, ethyl acetate, methyl phenyl ether, and toluene. Chlorobenzene is preferred as the antisolvent in this embodiment.

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

[0051] A suitable amount of phenylethylamine acetate was dissolved in an organic solvent to prepare a passivation solution with a concentration of 2 mg / ml. The passivation solution was then spin-coated onto the tin-lead perovskite light-absorbing layer 11 using a spin-coating method. The spin-coating speed was 3000 rpm-4000 rpm and the spin-coating time was 20 s-40 s. After spin-coating, the layer was annealed at a temperature of 90℃-110℃.

[0052] Step 5: Prepare the transport layer and buffer layer 7 sequentially on the surface of the interface passivation layer 9 using physical vapor deposition.

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

[0054] Example 2

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

[0056] In step 3: the perovskite precursor solution is dropped onto the hole transport layer 4. The dropped perovskite precursor solution is first spin-coated at a speed of 500 rpm-2000 rpm for 5-20 s, and then spin-coated at a speed of 4000 rpm-5000 rpm for 30-50 s. The total spin-coating time is 35-60 s. After the total spin-coating time is 30-45 s, 100-200 μL of anti-solvent is dropped onto the surface and spin-coating continues. After spin-coating is completed, the layer is annealed at a temperature of 80℃-120℃ for 10-30 min to obtain the 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] Example 3

[0059] Similar to the method in Example 1, the only difference is:

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

[0061] Comparative Example 1

[0062] Similar to Examples 1, 2, and 3, the difference from Examples 1 and 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 is the same as that in 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, the layers are: glass substrate 1, adhesive layer 2, conductive substrate, hole transport layer 4, tin-lead perovskite light-absorbing layer 11, electron transport layer 6, buffer layer 7, and metal electrode layer 8.

[0063] The voltage-current curves for Example 1 and the comparative example are shown below. Figure 2 The corresponding performance parameters are shown in Table 1.

[0064] Table 1. Performance Comparison of Example 1 and Comparative Example

[0065]

[0066] As shown in Table 1, Example 1 has significant advantages over the comparative example in terms of short-circuit current, open-circuit voltage, and energy conversion efficiency. This demonstrates that the defects at the bottom interface of the perovskite were effectively passivated through bottom treatment. As the non-radiative recombination of charge carriers was suppressed, the performance of the perovskite solar cell was significantly improved. Figure 2 The EQE test results for the examples and comparative examples show that the EQE integrated current can reach 29.2 mmA / cm. 2 This 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 absorbing layer in Example 1 and the comparative example are shown. The test results indicate that the passivation molecules can reduce the Sn content in the perovskite absorbing layer. 2+ With Pb 2+ Coordination occurs, and the peak results show that tin oxidation is significantly suppressed. The above test results indicate that since the passivation molecules are cations and anions and contain a variety of functional groups, the cations can fill the A-site ion holes on the perovskite surface, and the anions can fill the X-site ion holes on the perovskite surface. Therefore, after passivation treatment, a variety of surface defects can be passivated. The reduction of defects improves the performance and stability of perovskite solar cells.

Claims

1. A flexible tin-lead perovskite solar cell, comprising, from bottom to top, a flexible conductive substrate, a hole transport layer, a tin-lead perovskite light-absorbing layer, an electron transport layer, a buffer layer, and a metal electrode layer, characterized in that: It also includes an interface passivation layer, which is embedded between the tin-lead perovskite light-absorbing layer and the electron transport layer. 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 and -OH. The interface passivation layer material is one or a mixture of at least two of the following in any proportion: 4-phenylbut-1-amine acetate, 2,2,2-trifluoroacetic acid-N-ethylaniline, ammonium benzoate, phenethylamine acetate, ammonium acetate, dopamine 4-β-D-glucuronic acid, and β-hydroxy-α-methylphenylethylammonium [R-(R*,R*)]-hydrogen tartrate. 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.

2. The flexible tin-lead perovskite solar cell according to claim 1, characterized in that: 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.

3. The 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, ITO-coated flexible transparent plastic PET, or nano-conductive substrate.

4. A flexible tin-lead perovskite solar cell according to claim 1, characterized in that, The fabrication method of this flexible tin-lead perovskite solar cell includes the following steps: Step 1: Treat the transparent conductive substrate with plasma or ozone for 5–40 minutes; Step 2: The hole transport layer solution is spin-coated onto the transparent conductive substrate treated in Step 1 to prepare the 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)ethylphosphonic acid (2PACZ), 3-(9-carbazole)propionic acid (9CPA), and 9-carbazole acetic acid (9CAA). Step 3: Spin-coat the tin-lead perovskite light-absorbing layer precursor solution onto the cavity surface using the anti-solvent method to prepare the tin-lead perovskite light-absorbing layer; Step 4: Prepare an interface passivation layer on the surface of the tin-lead perovskite light-absorbing layer; Step 5: Prepare an electron transport layer and a buffer layer sequentially on the surface of the interface passivation layer using physical vapor deposition or spin coating. Step 6: Prepare a metal electrode on the surface of the buffer layer using evaporation coating or physical vapor deposition to obtain a flexible tin-lead perovskite solar cell.

5. The flexible tin-lead perovskite solar cell according to claim 4 is 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: Prepare a tin-lead perovskite light-absorbing layer precursor solution. Drop the perovskite precursor solution onto the hole transport layer. First, spin-coat the dropped perovskite precursor solution at a speed of 500 rpm-2000 rpm for 5-20 seconds, and then spin-coat the perovskite precursor solution at a speed of 4000 rpm-5000 rpm for 30-50 seconds. The total spin-coating time is 35-60 seconds. After a total spin-coating time of 30-45 seconds, drop 100-200 μL of anti-solvent onto the surface and continue spin-coating. After spin-coating, anneal at a temperature of 80℃-120℃ for 10-30 minutes to obtain the tin-lead perovskite light-absorbing layer. Method 2 is specifically described as follows: Prepare a perovskite precursor solution, drop the perovskite precursor solution onto 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 through the rotating substrate for 30-40 seconds after the spin-coating begins (15-20 seconds after the start of the spin-coating), and anneal at 150℃ for 10-20 minutes after the spin-coating is completed to obtain a tin-lead perovskite light-absorbing layer.

6. The flexible tin-lead perovskite solar cell according to claim 5 is characterized in that: The perovskite precursor solution comprises: a solution of formamidine iodide (FAI), methylamine iodide (MAI), cesium iodide (CsI), lead iodide (PbI2), stannous iodide (SnI2), stannous fluoride (SnF2), and an organic solvent, wherein the proportions of each component are as follows: FA 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 mixture of DMF and DMSO, and the ratio of DMF to DMSO is 3-10:1; wherein the antisolvent is one or a mixture of several of chlorobenzene, ethyl acetate, methyl phenyl ether, and toluene.

7. A flexible tin-lead perovskite solar cell according to claim 6, characterized in that: The interface passivation layer was prepared by spin coating, and the specific steps are as follows: The passivation material was dissolved in an organic solvent to prepare a passivation solution with a concentration ≤20mg / ml. The passivation solution was then spin-coated onto the surface of the tin-lead perovskite light-absorbing layer.

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