Preparation method of tin dioxide electron transport layer, battery material and application

Abstract

The application discloses a preparation method of a tin dioxide electron transport layer, a battery material and application, and relates to the technical field of photoelectric materials. The preparation method of the tin dioxide electron transport layer comprises the following steps: using a precursor solution formed by Sn(N(CH3)2)4 and a first solvent to prepare the tin dioxide electron transport layer on a conductive base material. The inventor improves the preparation method of the tin dioxide electron transport layer, adopts a solution method to replace a traditional gas phase method, can significantly improve the preparation efficiency of the tin dioxide electron transport layer, the process is simple, the preparation period of the solar cell can be shortened, and the electronic transport performance of the prepared device is also better. In addition, the preparation method provided in the embodiment of the application can perform a reaction at a lower heat treatment temperature, and energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic materials, and in particular to a preparation method of a tin dioxide electron transport layer, battery materials and applications. Background Art

[0002] Perovskite solar cells are a new type of solar cell technology that has flourished in the photovoltaic field in recent years. They are mainly composed of FTO conductive glass, electron transport layer, perovskite absorption layer, hole transport layer and counter electrode.

[0003] Commonly used electron transport layers in perovskite solar cells include inorganic materials such as TiO2, ZnO, and SnO2. Compared to TiO2 and ZnO electron transport layers, SnO2 exhibits higher carrier mobility and lower thermal treatment temperatures, and its device performance is stable under UV illumination. Traditional tin source precursors for SnO2 electron transport layers include SnCl2·2H2O, SnCl4·5H2O, tin powder, and commercially available SnO2 aqueous sols. These are mixed with a suitable solvent to form a precursor solution, which is then spin-coated and annealed to form the SnO2 electron transport layer.

[0004] Existing methods for preparing SnO2 electron transport layers generally have the following problems: complex process, high heat treatment temperature, and the performance of the prepared batteries needs to be improved.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing a tin dioxide electron transport layer and a battery material having the tin dioxide electron transport layer, which has a short preparation cycle and can be reacted under lower temperature conditions.

[0007] Another object of the present invention is to provide a solar cell and a method for preparing the same, which also have the advantages of a short preparation cycle, low energy consumption, and good electrical transmission performance.

[0008] The present invention is achieved in that:

[0009] In a first aspect, the present invention provides a method for preparing a tin dioxide electron transport layer, comprising: preparing a tin dioxide electron transport layer on a conductive substrate using a precursor solution formed by Sn(N(CH3)2)4 and a first solvent.

[0010] In a second aspect, the present invention provides a battery material having a tin dioxide electron transport layer, comprising a conductive substrate and a tin dioxide electron transport layer attached to the conductive substrate, wherein the tin dioxide electron transport layer is prepared by the preparation method in the aforementioned embodiment.

[0011] In a third aspect, the present invention provides a method for preparing a solar cell, comprising: forming a tin dioxide electron transport layer on a conductive substrate using the preparation method in the aforementioned embodiment, and then sequentially forming a light absorbing layer and a counter electrode layer on the tin dioxide electron transport layer.

[0012] In a fourth aspect, the present invention provides a solar cell prepared by the above-mentioned preparation method.

[0013] The present invention has the following beneficial effects: The inventors have improved the preparation method of the tin dioxide electron transport layer, adopting a solution method instead of the traditional vapor phase method, which can significantly improve the preparation efficiency of the tin dioxide electron transport layer. The process is simple, which can shorten the preparation cycle of solar cells, and the resulting device also has good electron transport performance. In addition, the preparation method provided by the embodiment of the present invention can be carried out at a lower heat treatment temperature, reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 Schematic diagram of the device structure of the perovskite solar cell provided in Examples 1 to 6 of the present application;

[0016] Figure 2 Field emission scanning electron micrographs of the SnO2 electron transport layer provided in Examples 1 to 6 of the present application;

[0017] Figure 3 X-ray diffraction patterns of the SnO2 electron transport layers provided in Examples 1 to 6 of the present application;

[0018] Figure 4 The current density-voltage curve of the perovskite solar cell prepared in Examples 1-3;

[0019] Figure 5 The current density-voltage curves of the perovskite solar cells prepared in Example 1 and Examples 4-6 are shown;

[0020] Figure 6 1 is a current density-voltage curve diagram of the perovskite solar cells prepared in Example 1 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0021] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0022] An embodiment of the present invention provides a method for preparing a solar cell, comprising: forming a tin dioxide electron transport layer on a conductive substrate, and then sequentially forming a light absorption layer and a counter electrode layer on the tin dioxide electron transport layer. The inventors have improved the preparation process for the tin dioxide electron transport layer, adopting a solution method for preparation, which has a fast reaction rate, shortens preparation time, and can be carried out at a lower heat treatment temperature, thereby reducing process energy consumption.

[0023] S1. Formation of tin dioxide electron transport layer

[0024] An embodiment of the present invention provides a method for preparing a tin dioxide electron transport layer, including: preparing a tin dioxide electron transport layer on a conductive substrate using a precursor solution formed from Sn(N(CH3)2)4 and a first solvent. The inventors creatively used Sn(N(CH3)2)4 as a reaction raw material to obtain tin dioxide by reacting with air or oxygen. The reaction proceeds rapidly and can be performed at a relatively low heat treatment temperature. Compared with existing technologies, this is a new approach to preparing tin dioxide transport layers.

[0025] Specifically, Sn(N(CH3)2)4 is a commercially available raw material, such as the product with CAS No. 1066-77-9 from J&K Company.

[0026] Furthermore, the concentration of Sn(N(CH3)2)4 in the precursor solution is 0.05-0.2M, preferably 0.10-0.15M. The first solvent is an alcoholic organic solvent, preferably, the first solvent is selected from at least one of ethanol, methanol, propanol, and ethylene glycol. The concentration of Sn(N(CH3)2)4 has a significant impact on the performance of the electron transport layer. If the concentration is too low, the film layer will be incomplete and leakage will occur easily. If the concentration is too high, the reaction will be too fast, and the film layer will be too thick, which will affect the electrical transport performance.

[0027] In actual operation, the precursor solution is coated on a conductive substrate and then annealed at 100-180°C. The annealing time can be 10-60 minutes, preferably 25-35 minutes, and the annealing temperature is 100-150°C. The preparation method provided in the embodiment of the present invention can be carried out at 100-150°C, which is a relatively low reaction temperature.

[0028] Specifically, the reaction temperature can be 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, etc., or any value between the above adjacent temperature values; the annealing time can be 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, etc., or any value between the above adjacent time values.

[0029] In some embodiments, the precursor solution is applied to the conductive substrate by spin coating, initially at a spin coating speed of 800-1200 rpm for 5-7 seconds (e.g., 5 seconds, 6 seconds, 7 seconds, etc.), and then at a spin coating speed of 3500-4500 rpm for 25-35 seconds (e.g., 25 seconds, 30 seconds, 35 seconds, etc.). A slower spin coating speed is used initially to prevent splashing at the beginning of the coating process. Once a film is slowly formed, the spin coating speed is increased to obtain a uniform film layer.

[0030] In some embodiments, the conductive substrate is FTO conductive glass. In other embodiments, it can also be other conductive materials or other conductive glasses.

[0031] In a preferred embodiment, the conductive substrate is pre-treated before the precursor solution is applied to clean the surface. If the conductive substrate itself has a high degree of cleanliness, pre-treatment is not required.

[0032] Specifically, the pretreatment process includes ultrasonically cleaning the conductive substrate using water, acetone, ethanol, and isopropyl alcohol, with each cleaning time lasting 20-40 minutes. Ultrasonic cleaning using these reagents is performed separately to enhance the cleaning effect. Specifically, each cleaning time can be 20 minutes, 30 minutes, 40 minutes, or any other value between these adjacent time values.

[0033] In some embodiments, the pre-treatment process further includes: subjecting the cleaned conductive substrate to ultraviolet ozone treatment for 15-25 minutes (eg, 15 minutes, 20 minutes, 25 minutes, etc.) to achieve a sterilization effect.

[0034] S2. Formation of light-absorbing layer

[0035] A light absorbing layer is formed on the tin dioxide electron transport layer. The light absorbing layer can be prepared using existing technology and is not limited here.

[0036] In some embodiments, the light-absorbing layer is a perovskite light-absorbing layer, which can give the battery better performance due to the advantages of the perovskite material itself, such as low cost, wide band gap, high carrier mobility, etc.

[0037] Furthermore, the preparation process of the light-absorbing layer includes: coating a perovskite solution on the surface of the tin dioxide electron transport layer, and then annealing it at 100-180°C for 25-35 minutes. The heat treatment temperature can be 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, etc., or any value between the above adjacent temperature values; the annealing time can be 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc., or any value between the above adjacent time values.

[0038] In some embodiments, the perovskite solution is first coated at a spin coating speed of 800-1200 rpm for 5-7 seconds, then at a spin coating speed of 3500-4500 rpm for 25-35 seconds, and chlorobenzene is added after 16 seconds of spin coating. Similar to the formation process of the tin dioxide electron transport layer, both adopt a method of first slow spin coating and then fast spin coating to prevent splashing at the beginning of spin coating and quickly form a uniform film layer. By adding chlorobenzene, the electron transport efficiency of the device can be further improved.

[0039] Furthermore, the perovskite solution is prepared by dissolving a material satisfying the structural formula ABX3 in a second solvent; wherein, in the structural formula ABX3, A is selected from at least one of Cs, CH3NH3, and C4H9NH3; B is selected from at least one of Pb and Sn; and X is selected from at least one of Cl, Br, and I. The perovskite raw materials can be prepared using existing techniques. For example, in some embodiments, the perovskite solution can be prepared by dissolving PbI2 and CH3NH3I in a second solvent.

[0040] Furthermore, the molar ratio of PbI2 to CH3NH3I is 0.95-1.10:1, and the total concentration of PbI2 and CH3NH3I in the perovskite solution is 1.2-1.4 M. The performance of the battery is improved by controlling the concentration and ratio of the raw materials. Specifically, the molar ratio of PbI2 to CH3NH3I can be 0.95:1, 1.05:1, 1.10:1, etc., and the total concentration can be 1.2 M, 1.3 M, 1.4 M, etc. In actual operation, PbI2 and CH3NH3I are mixed and stirred in the second solvent for 7-9 hours.

[0041] Furthermore, the second solvent is selected from at least one of N,N-dimethylformamide and dimethyl sulfoxide. In some embodiments, the second solvent includes N,N-dimethylformamide and dimethyl sulfoxide, and the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is 8-10:1, such as 8:1, 9:1, 10:1, etc.

[0042] S3. Formation of the electrode layer

[0043] A counter electrode layer is formed on the light absorbing layer. The material of the counter electrode layer may also be made from existing technology and is not limited here.

[0044] In some embodiments, the counter electrode is selected from at least one of a gold counter electrode layer, a silver counter electrode layer, and a carbon counter electrode layer, such as a carbon counter electrode. Carbon material is a preferred counter electrode material due to its advantages such as low cost, high conductivity, low temperature preparation process, and good hole collection ability.

[0045] An embodiment of the present invention provides a battery material having a tin dioxide electron transport layer, comprising a conductive substrate and a tin dioxide electron transport layer attached to the conductive substrate, wherein the tin dioxide electron transport layer is prepared by the preparation method of the aforementioned embodiment and is an intermediate material for preparing solar cells.

[0046] It should be noted that the application of this cell in perovskite solar cells can achieve a high open-circuit voltage and a photoelectric conversion efficiency of up to 14.69%, with excellent cell repeatability. The SnO2 electron transport layer preparation method of the present invention is relatively simple, and the heat treatment temperature is relatively low, which is conducive to the application and promotion of flexible battery technology. Furthermore, SnO2 has a larger band gap width and more stable chemical properties than TiO2, which is beneficial for improving the performance and photostability of the battery.

[0047] An embodiment of the present invention further provides a solar cell, which is prepared by the above preparation method and has the advantages of short preparation cycle, low energy consumption and good battery performance.

[0048] In some embodiments, it may be a flexible battery.

[0049] In some embodiments, the solar cell has a multilayer structure, which includes FTO conductive glass (350 nm), SnO2 electron transport layer (30-90 nm), perovskite light absorption layer (420 nm) and carbon counter electrode layer (28 μm).

[0050] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0051] Example 1

[0052] This embodiment provides a method for preparing a solar cell, comprising the following steps:

[0053] (1) FTO conductive glass cleaning. Ultrasonic cleaning of FTO conductive glass was performed with deionized water, acetone, anhydrous ethanol, and isopropyl alcohol for 30 min each, followed by drying with a hair dryer and UV ozone treatment for 20 min.

[0054] (2) Preparation of SnO2 electron transport layer. Spin-coat the SnO2 electron transport layer on the FTO surface treated in step (1): Prepare a precursor solution by mixing Sn(N(CH3)2)4 and ethanol solution in a certain ratio, then stir for 2 hours. The precursor solution concentration is 0.15M. Spin-coat the SnO2 precursor solution at a low speed of 1000 rpm for 6 seconds and a high speed of 4000 rpm for 30 seconds. After spin coating, anneal at 100°C for 30 minutes.

[0055] (3) Prepare a perovskite light-absorbing layer on the surface of the above-mentioned SnO2 electron transport layer. Dissolve CH3NH3I and PbI2 (molar ratio of 1:1) in a mixed solution of N,N-dimethylformamide and dimethyl ethyl sulfone and stir for 8 hours to obtain a perovskite solution. The volume ratio of N,N-dimethylformamide and dimethyl ethyl sulfone is 9:1, and the total concentration of CH3NH3I and PbI2 is 1.3 M. Then, spin-coat the above-mentioned perovskite solution on the surface of the SnO2 electron transport layer. First, spin-coat at a low speed of 1000 rpm for 6 seconds, and then spin-coat at a high speed of 4000 rpm for 30 seconds. 100 μL of chlorobenzene is quickly added 16 seconds after the start of spin coating. After the spin coating is completed, anneal at 100°C for 10 minutes.

[0056] (4) Prepare a carbon counter electrode on the surface of the perovskite light absorbing layer. Scrape 0.06 cm on the perovskite light absorbing layer by screen printing. 2 Low temperature carbon slurry.

[0057] The structure of the prepared perovskite solar cell device is as follows Figure 1 As shown, they are FTO conductive glass, SnO2 electron transport layer, perovskite light absorption layer and carbon counter electrode layer.

[0058] Example 2

[0059] This embodiment provides a method for preparing a solar cell, which differs from the embodiment 1 only in that the annealing temperature during the preparation of the SnO2 electron transport layer is 150°C.

[0060] Example 3

[0061] This embodiment provides a method for preparing a solar cell, which differs from the first embodiment only in that the annealing temperature during the preparation of the SnO2 electron transport layer is 180°C.

[0062] Example 4

[0063] This embodiment provides a method for preparing a solar cell. The only difference from Example 1 is the preparation of the SnO2 electron transport layer, which is as follows:

[0064] A precursor solution of Sn(N(CH3)2)4 and ethanol solution was prepared in a specific ratio and stirred for 2 hours. The concentration of Sn(N(CH3)2)4 was 0.05 M. The SnO2 precursor solution was spin-coated at a low speed of 1000 rpm for 6 seconds and a high speed of 4000 rpm for 30 seconds. After spin coating, the solution was annealed at 150°C for 30 minutes.

[0065] Example 5

[0066] This embodiment of the present invention provides a method for preparing a solar cell, which differs from Example 4 only in that the concentration of Sn(N(CH3)2)4 in the precursor solution is 0.1M.

[0067] Example 6

[0068] This embodiment provides a method for preparing a solar cell, which differs from Example 4 only in that the concentration of Sn(N(CH3)2)4 in the precursor solution is 0.2M.

[0069] Comparative Example 1

[0070] This comparative example provides a method for preparing a solar cell, which differs from Example 1 only in that the tin source used is SnO2 commercial aqueous sol, and the SnO2 precursor solution is prepared by SnO2 commercial aqueous sol and water in a volume ratio of 1:3.5.

[0071] Comparative Example 2

[0072] This comparative example provides a method for preparing a solar cell, which differs from Example 1 only in that the tin source used is SnCl2·2H2O, and the SnO2 precursor solution is prepared by SnCl2·2H2O and ethanol in a molar ratio of 1:3.

[0073] Comparative Example 3

[0074] This comparative example provides a method for preparing a solar cell, which adopts the existing preparation process. The only difference from Example 1 is that the tin source used is SnCl4·5H2O, and the SnO2 precursor solution is prepared by SnCl4·5H2O and isopropyl alcohol with a concentration of 0.075M.

[0075] Test Example 1

[0076] The field emission scanning electron microscopy images of the SnO2 electron transport layers prepared in test examples 1-6 showed roughly the same results. Figure 2 This is the test result of Example 1.

[0077] Depend on Figure 2 It can be seen that the surface of the SnO2 electron transport layer in the perovskite solar cell provided in this embodiment is dense and has no pinholes.

[0078] Test Example 2

[0079] The X-ray diffraction patterns of the SnO2 electron transport layers prepared in Examples 1-6 were tested, and the results were roughly the same. Figure 3 This is the test result of Example 1.

[0080] Depend on Figure 3 It can be seen that the SnO2 in the SnO2 electron transport layer of the perovskite solar cell provided in this embodiment has a rutile phase structure.

[0081] Test Example 3

[0082] The current density-voltage curves of the solar cells prepared in the test examples 1-6 are shown in FIG. Figure 4-5 and Table 1. Test method: at AM 1.5, active layer effective area 0.06cm 2 The battery is tested under the following conditions.

[0083] Table 1 Statistical results of photoelectric performance parameters of the prepared perovskite solar cells

[0084]

[0085]

[0086] As shown in Table 1, it can be seen that the photoelectric conversion efficiency of the planar perovskite solar cell with the SnO2 electron transport layer prepared in Example 1 is 13.41%, the open circuit voltage is 1.089 V, and the short circuit current density is 19.18 mA / cm 2 The planar perovskite solar cell with SnO2 electron transport layer prepared in Example 2 has a photoelectric conversion efficiency of 14.00%, an open circuit voltage of 1.102 V, and a current density of 19.07 mA / cm 2 , the filling factor is 66.62%.

[0087] The planar perovskite solar cell with SnO2 electron transport layer prepared in Example 3 has a photoelectric conversion efficiency of 11.55%, an open circuit voltage of 0.975 V, and a current density of 18.43 mA / cm 2 , the filling factor is 64.28%.

[0088] pass Figure 4 It can be seen that the filling factor of the planar perovskite solar cell with SnO2 electron transport layer annealing temperature of 150℃ is significantly larger than that of annealing temperature of 100℃ and 180℃, and the photoelectric conversion efficiency is higher. The appropriate annealing temperature is 100-150℃.

[0089] As shown in Table 1, it can be seen that the photoelectric conversion efficiency of the planar perovskite solar cell with the SnO2 electron transport layer prepared in Example 4 is 13.19%, the open circuit voltage is 1.04 V, and the short circuit current density is 19.50 mA / cm 2 , the filling factor is 65.04%.

[0090] The photoelectric conversion efficiency of the planar perovskite solar cell with SnO2 electron transport layer prepared in Example 5 is 14.69%, the open circuit voltage is 1.09 V, and the current density is 19.7 mA / cm 2 , the filling factor is 68.41%.

[0091] The photoelectric conversion efficiency of the planar perovskite solar cell with SnO2 electron transport layer prepared in Example 6 is 13.50%, the open circuit voltage is 1.089V, and the current density is 19.18mA / cm 2 , the filling factor is 64.63%.

[0092] pass Figure 5 It can be seen that the filling factor of the planar perovskite solar cell with SnO2 electron transport layer having a precursor concentration of 0.10M and 0.15M is significantly larger than that with a precursor concentration of 0.05M and 0.20M, and the photoelectric conversion efficiency is higher.

[0093] Test Example 4

[0094] The current density-voltage curves of the solar cells prepared in Example 1 and Comparative Examples 1-3 are shown in FIG. Figure 6 The test method is the same as that of Test Example 3, and the test results are shown in Table 1.

[0095] By comparison with the examples, it can be seen that when the electron transport layer is prepared using commercial aqueous sol, the open circuit voltage and photoelectric conversion efficiency of the device are low, the short circuit current density of the device prepared using SnCl2·2H2O and SnCl4·5H2O is large, and the photoelectric conversion efficiency is high, while the open circuit voltage of the device prepared using Sn(NMe2)4 is high and the photoelectric conversion efficiency is the highest.

[0096] In summary, the present invention provides a method for preparing a tin dioxide electron transport layer, a battery material, and its application. Using a solution-processed SnO2 thin film as the electron transport layer in a perovskite solar cell, high photoelectric conversion efficiency is achieved. In this carbon-counter-electrode perovskite solar cell without a hole transport material, the SnO2 film is very dense and can effectively block holes, reducing the recombination of electron-hole pairs, thereby improving the fill factor.

[0097] The method in the embodiment of the present invention is more reproducible than perovskite cells using SnO2 electron transport layers prepared by the traditional solution method. It also has a simple preparation process, low heat treatment temperature, and good stability. Most importantly, the prepared solar cells have excellent performance and huge potential applications. This also demonstrates the feasibility of using perovskite photovoltaic cells based on this SnO2 electron transport layer in industrial production such as flexible batteries.

[0098] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a tin dioxide electron transport layer, characterized in that: include: A tin dioxide electron transport layer is prepared on a conductive substrate using a precursor solution formed by Sn(N(CH3)2)4 and a first solvent; The concentration of Sn(N(CH3)2)4 in the precursor solution is 0.05-0.2M; The precursor solution is coated on the conductive substrate, and then annealed at 100-180° C.

2. The preparation method according to claim 1, characterized in that The annealing time of the annealing treatment is 25-35 minutes, and the annealing temperature is 100-180°C.

3. The preparation method according to claim 1, characterized in that The precursor solution is coated on the conductive substrate by spin coating, first at a spin coating speed of 800-1200 rpm for 5-7 s, and then at a spin coating speed of 3500-4500 rpm for 25-35 s.

4. The preparation method according to claim 1, characterized in that The conductive substrate is FTO conductive glass.

5. The preparation method according to claim 1, characterized in that The concentration of Sn(N(CH3)2)4 in the precursor solution is 0.10-0.15M.

6. The preparation method according to claim 1, characterized in that The first solvent is an alcohol organic solvent.

7. The preparation method according to claim 6, characterized in that The first solvent is selected from at least one of ethanol, methanol, propanol, and ethylene glycol.

8. The preparation method according to claim 1, characterized in that The method further includes pre-treating the conductive substrate before coating the precursor solution.

9. The preparation method according to claim 8, characterized in that The pretreatment process includes: ultrasonically cleaning the conductive substrate with water, acetone, ethanol and isopropyl alcohol in sequence, with each cleaning time being 20-40 minutes.

10. The preparation method according to claim 9, characterized in that The pre-treatment process further includes: subjecting the cleaned conductive substrate to ultraviolet ozone treatment for 15-25 minutes.

11. A battery material having a tin dioxide electron transport layer, characterized in that: The invention comprises a conductive substrate and a tin dioxide electron transport layer attached to the conductive substrate, wherein the tin dioxide electron transport layer is prepared by the preparation method according to any one of claims 1 to 10.

12. A method for preparing a solar cell, characterized in that: include: A tin dioxide electron transport layer is formed on a conductive substrate by using the preparation method according to any one of claims 1 to 10, and then a light absorption layer and a counter electrode layer are sequentially formed on the tin dioxide electron transport layer.

13. The preparation method according to claim 12, characterized in that The light absorbing layer is a perovskite light absorbing layer.

14. The preparation method according to claim 13, characterized in that The preparation process of the light absorbing layer includes: coating a perovskite solution on the surface of the tin dioxide electron transport layer, and then performing an annealing treatment at 100-180° C. for 25-35 minutes.

15. The preparation method according to claim 14, characterized in that During the coating process of the perovskite solution, the coating was first performed at a coating speed of 800-1200 rpm for 5-7 s, then at a coating speed of 3500-4500 rpm for 25-35 s, and chlorobenzene was added after 16 s of coating.

16. The preparation method according to claim 14, characterized in that The perovskite solution is prepared by dissolving a material having a total structural formula satisfying ABX3 in a second solvent; Wherein, in the structural formula ABX3, A is selected from at least one of Cs, CH3NH3 and C4H9NH3; B is selected from at least one of Pb and Sn; and X is selected from at least one of Cl, Br and I.

17. The preparation method according to claim 16, characterized in that The perovskite solution is prepared by dissolving PbI2 and CH3NH3I in the second solvent.

18. The preparation method according to claim 17, characterized in that: The molar ratio of PbI2 to CH3NH3I is 0.95-1.10:1, and the total concentration of PbI2 and CH3NH3I in the perovskite solution is 1.2-1.4M.

19. The preparation method according to claim 17, characterized in that The second solvent is selected from at least one of N,N-dimethylformamide and dimethyl sulfoxide.

20. The preparation method according to claim 19, characterized in that The second solvent includes N,N-dimethylformamide and dimethyl sulfoxide, and the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is 8-10:

1.

21. The preparation method according to claim 12, characterized in that The counter electrode is selected from at least one of a gold counter electrode layer, a silver counter electrode layer and a carbon counter electrode layer.

22. A solar cell, characterized in that: It is prepared by the preparation method according to any one of claims 12 to 21.

23. The solar cell according to claim 22, characterized in that The solar cell has a multi-layer structure, which includes FTO conductive glass, SnO2 electron transport layer, perovskite light absorption layer and carbon counter electrode layer in sequence.

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