Cesium-based perovskite solar cell and method of manufacturing the same

Abstract

This invention relates to the field of perovskite solar cell technology, and more particularly to cesium-based perovskite solar cells and their fabrication methods. In the fabrication process of perovskite solar cells, aromatic nitrile molecules are used in combination with cesium halide as a SAM layer. The two synergistically optimize the crystal quality, interface passivation, and charge transport process of the perovskite layer, reducing non-radiative recombination losses, thereby significantly improving the cell efficiency; Cs + The synergistic effect with halogen elements enhances the water, thermal, and optical stability of the perovskite material interface, ensuring that the device can maintain a high initial efficiency after long-term operation. At the same time, cesium halide optimizes the crystallization process of perovskite, and aromatic nitrile molecules can improve the wetting characteristics of perovskite precursors on SAM substrates. The two work together to promote the formation of more uniform, dense, and high-quality perovskite films and reduce interface defects.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and more particularly to cesium-based perovskite solar cells and their fabrication methods. Background Technology

[0002] Perovskite solar cells (PSCs), as a next-generation photovoltaic technology, have attracted widespread attention due to their high photoelectric conversion efficiency and low fabrication cost. In the inverted (pin) device structure, self-assembled monolayers (SAMs) play a crucial role as the hole transport layer (HTL). Among them, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACz) and its analogues, the PACz series (4PACz, Me-2PACz, MeO-2PACz), are commonly used SAM materials. However, in practical applications, this series of materials has significant limitations, mainly in the following three aspects:

[0003] 1. Poor wettability of perovskite precursor solution: The MeO-4PACz surface has strong hydrophobicity, resulting in a large contact angle of the perovskite precursor solution on its surface, which is not conducive to the formation of a uniform and dense perovskite film. Poor wettability easily leads to micropores and crystallization defects at the buried interface, thereby increasing the nonradiative recombination loss of interfacial charge.

[0004] II. Insufficient interfacial stability, easily desorbed by precursor solvents: PACz molecules in the SAM layer and the substrate (such as NiO) X The bonding strength of SAM (Solid Oxide Atomium) molecules is limited. During the perovskite solution coating process, the solvent can cause some molecules to detach or aggregate, resulting in uneven distribution of the SAM layer. This non-uniformity can lead to local charge transport barriers and leakage current, reducing device efficiency and experimental repeatability.

[0005] 3. High interface defect density: Conventional PACz molecules lack functional groups and cannot effectively passivate perovskite / NiO. X Deep-level traps at the interface lead to severe nonradiative recombination, limiting the open-circuit voltage (V). OC The increase in fill factor (FF) and fill factor (FF).

[0006] In summary, given the limitations of existing technologies and the urgent need to improve the performance of perovskite solar cells in practical applications, it is necessary to develop novel self-assembled monolayers that meet the performance improvement requirements of perovskite solar cells. Summary of the Invention

[0007] The present invention aims to at least solve one of the technical problems existing in the related art. Therefore, the first objective of the present invention is to provide a method for fabricating a cesium-based perovskite solar cell; the second objective of the present invention is to provide a cesium-based perovskite solar cell.

[0008] To achieve the first objective, the technical solution adopted by this invention is as follows:

[0009] The fabrication method of cesium-based perovskite solar cells includes the following steps:

[0010] S100. A hole transport layer is prepared on a conductive glass substrate using spin coating.

[0011] S200. A self-assembled monolayer is prepared on the hole transport layer using spin coating.

[0012] In this step, the precursor solution used in the spin coating method is a mixed alcohol solution composed of aromatic nitrile and cesium halide;

[0013] The structural formula of the aromatic nitrile is shown below:

[0014] ;

[0015] The concentration of aromatic nitriles in the mixed alcohol solution is 0.4–1.0 mg / mL, and the molar ratio of aromatic nitriles to cesium halides is 1:(0.8–1.2).

[0016] S300. A perovskite thin film layer is prepared on the self-assembled monolayer using spin coating.

[0017] S400. Using vacuum evaporation, a passivation modification layer and an electron transport layer are sequentially deposited on the perovskite thin film layer.

[0018] S500. A BCP buffer layer is deposited on the electron transport layer using a vacuum evaporation method.

[0019] Among them, BCP is 2,9-dimethyl-4,7-biphenyl-1,10-o-diazaphenanthroline;

[0020] S600. Using vacuum evaporation, a metal electrode is deposited on the BCP buffer layer.

[0021] Traditional SAM materials (MeO-4PACz) suffer from poor wettability of perovskite precursors, easy desorption, and high defect density, leading to reduced charge transport efficiency at the SAM-perovskite interface. This invention provides an aromatic nitrile with dicyano, alkoxy, and phenoxy structures as a novel SAM material. The ethoxy chain (-OCH2CH2OCH3) exhibits high lipophilicity and polarity, enhancing the wettability of the perovskite precursor solution on the SAM substrate, improving the uniformity of film crystallization, and reducing porosity at the buried interface. The phthalonitrile group can react with the metal oxide substrate NiO. X The formation of strong coordination bonds, along with the phenoxy group providing π-π stacking interaction, enhances the adsorption stability of the molecule on the substrate and resists desorption and scouring caused by the precursor solution. In addition, the phthalonitrile group can also combine with the undercoordinated lead ions generated by halogen vacancies at the perovskite substrate interface, inhibiting ion migration of perovskite under light and heating conditions and reducing the shortening of battery life caused by external environment.

[0022] Furthermore, under high-temperature conditions, the organic cations at the interface of perovskites readily volatilize and generate defects, leading to decreased perovskite lattice instability and consequently a gradual reduction in battery efficiency. By combining cesium halide with the aforementioned aromatic nitrile, Cs... + Both cesium and halogens can compensate for the loss of ionic components at the perovskite interface at high temperatures, inhibiting the high-temperature degradation process of perovskite. Furthermore, the addition of cesium halide enhances the polarity of the aromatic nitrile solution, improving the performance of the SAM precursor solution on NiO. X The wettability on the substrate provides stable initial nucleation sites for perovskite crystallization and inhibits the irreversible degradation of perovskite caused by the loss of ionic components due to high temperature.

[0023] Preferably, in step S100, the hole transport layer is mainly composed of nickel oxide.

[0024] Preferably, in step S200, the concentration of aromatic nitriles in the mixed alcohol solution is 0.4 to 0.8 mg / mL.

[0025] Preferably, in step S200, the concentration of aromatic nitriles in the mixed alcohol solution is 0.6 mg / mL.

[0026] Preferably, in step S200, the cesium halide is selected from cesium bromide.

[0027] Preferably, in step S200, the solvent of the mixed alcohol solution is selected from methanol and / or propanol.

[0028] Preferably, in step S300, the main component of the precursor solution used in the spin coating method is Cs. 0.05 (MA 0.05 FA 0.95 )0.95 Pb(I 0.95 Br 0.05 )3;

[0029] In this context, MA stands for methylamine and FA stands for formamidin.

[0030] Preferably, in step S400, the main component of the passivation modification layer is selected from LiF, and the main component of the electron transport layer is selected from C60.

[0031] Preferably, the passivation modification layer has a thickness of 0.5–1 nm, the electron transport layer has a thickness of 20–25 nm, and the BCP buffer layer has a thickness of 3–5 nm.

[0032] Preferably, in step S600, the metal electrode is an Ag electrode.

[0033] To achieve the second objective, the technical solution adopted by this invention is as follows:

[0034] Cesium-based perovskite solar cells are fabricated using any of the above-described methods for preparing cesium-based perovskite solar cells.

[0035] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0036] This invention provides a cesium-based perovskite solar cell and its preparation method. In the preparation process of the perovskite solar cell, 3-(4-(2-methoxyethoxy)phenoxy)phthalonitrile and cesium halide are used together as the SAM layer, achieving the following technical effects:

[0037] I. Significantly improve photoelectric conversion efficiency: By synergistically optimizing the crystal quality of the perovskite layer, interface passivation, and charge transport process, nonradiative recombination loss is reduced, thereby significantly improving device efficiency;

[0038] II. Improving the operational stability of battery devices: Cs + The presence of halogens enhances the stability of the perovskite material interface, while aromatic nitrile molecules construct a more uniform interface. The two work synergistically to inhibit water, light, and thermal degradation of perovskite, ensuring that the device can maintain a high initial efficiency even after long-term operation.

[0039] III. Improving film quality and optimizing interfacial contact: Cesium halide optimizes the crystallization process of perovskite, and aromatic nitrile molecules improve the wetting characteristics of perovskite precursors on self-assembled monolayer (SAM) substrates. The two work together to promote the formation of more uniform, dense, and high-quality perovskite films and reduce interfacial defects.

[0040] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0041] Figure 1 It is the aromatic nitrile molecule provided in Example 1 of this invention. 1 H NMR spectrum.

[0042] Figure 2 This is a diagram showing the measurement results of the contact angle of SAM layers with different components provided in Example 1 of this invention.

[0043] Figure 3 This is an X-ray photoelectron spectrum (XPS) of the aromatic nitrile (P1) and the N 1s orbital of the aromatic nitrile SAM layer provided in Test Example 2 of the present invention.

[0044] Figure 4 These are scanning electron microscope images of control group 2 and sample 3 provided in test example 3 of this invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention, but cannot be used to limit the scope of this invention.

[0046] In the following embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available, unless otherwise specified, and are carried out in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0047] Example 1

[0048] Preparation of aromatic nitrile molecules The synthetic route is shown below:

[0049] ;

[0050] The preparation process is as follows: 1 mmol of 3-nitrophthalonitrile and 1 mmol of 4-(2-methoxyethoxy)phenol were added to a round-bottom flask containing 10 mL of DMF. The mixture was heated and refluxed at 80 °C with stirring. Simultaneously, 10 mL of 0.2 mmol / mL potassium carbonate DMF solution was slowly added dropwise to the reaction system. After the addition was complete, the reaction was continued for 8 hours. Then, 10 mL of distilled water at 0 °C was added, and a precipitate was formed. The precipitate was filtered, washed with anhydrous ethanol, and then dissolved in ethyl acetate for recrystallization purification to obtain aromatic nitrile molecules. 1 H NMR spectra, such as Figure 1 As shown; its 1 The H NMR characterization data are shown below:

[0051] 1 H NMR (400MHz, CDCl3): δ 3.23 (3H, s), 3.65 (2H, t, J =6.8Hz), 4.18(2H, t, J =6.8Hz), 6.90(2H, ddd, J =8.7, 2.7, 0.5Hz), 7.04 (2H, ddd, J =8.7, 2.7, 0.5Hz), 7.38 (1H, dd, J =8.2, 1.2Hz), 7.61 (1H, dd, J =8.2, 7.7Hz), 7.80 (1H, dd, J =7.7, 1.2Hz).

[0052] Example 2

[0053] The process for fabricating cesium-based perovskite solar cells is as follows:

[0054] I. Pretreatment of FTO (fluorine-doped tin oxide) conductive glass substrate.

[0055] The FTO conductive glass was sequentially immersed in deionized water, acetone, isopropanol and ethanol, and ultrasonically cleaned for 20 minutes each to thoroughly remove surface organic matter, dust and ion contamination. Subsequently, the substrate was dried with high-pressure nitrogen and then annealed at 30°C for 2 hours using a heating plate to obtain a clean conductive glass substrate.

[0056] II. Preparation of a hole transport layer on a conductive glass substrate.

[0057] NiOx nanoparticles were dispersed in deionized water to form a uniform dispersion (10 mg / mL). This dispersion was then added dropwise to the surface of an FTO substrate. After spin-coating at 2500 rpm for 25 seconds, the substrate was annealed at 120°C for 20 minutes to form a dense NiOx layer with a thickness of 20 nm. x Hole transport layer.

[0058] III. In NiO x A SAM layer is fabricated on the hole transport layer.

[0059] The aromatic nitrile molecules prepared in the examples were dissolved in ethanol to prepare aromatic nitrile ethanol solutions (concentrations of 0.2, 0.4, 0.6, 0.8, and 1.0 mg / mL, respectively). Simultaneously, equimolar amounts of CsBr were added to the aromatic nitrile ethanol solutions to dissolve them, yielding SAM layer precursor solutions. In a glove box under nitrogen atmosphere, the SAM layer precursor solution was dropwise added to NiO. x On the surface of the hole transport layer, spin-coating was performed at 3500 rpm for 30 seconds, followed by annealing at 110°C for 10 minutes to obtain a SAM layer with a thickness of approximately 2 nm.

[0060] IV. Fabrication of a perovskite light-absorbing thin film layer on the SAM layer.

[0061] Methylammonium bromide (MABr) (180.5 mg), CsI (66.5 mg), FAI (838.3 mg), and PbI2 (2359.7 mg) were added to a mixed solvent (4 ml, DMF to DMSO volume ratio 5:1) consisting of N,N-dimethylformamide (DMF) and dimethylsulfoxide (DMSO). After mixing thoroughly, a perovskite precursor solution was obtained. Under nitrogen atmosphere, the perovskite precursor solution (0.75 mL) was added dropwise to the surface of the SAM layer. The mixture was kept at 500 rpm for 15 s and then at 4500 rpm for 30 s (450 μL of ethyl acetate was added dropwise as an antisolvent in the last 10 s to promote the crystallization of perovskite). The mixture was then annealed at 100 °C for 15 min to obtain a perovskite thin film layer.

[0062] The molecular formula of the perovskite thin film component is Cs. 0.05 (MA 0.05 FA 0.95 ) 0.95 Pb(I 0.95 Br 0.05 3.

[0063] 5. A passivation modification layer and an electron transport layer are sequentially deposited on the perovskite thin film layer by vapor deposition.

[0064] The substrate with the perovskite film is transferred to a vacuum evaporation equipment. First, an ultrathin LiF layer (0.5-1 nm) is deposited as a passivation modification layer, which helps to reduce interfacial recombination. Then, a C60 layer (20-25 nm thick) is deposited as an electron transport layer.

[0065] 6. Deposit a BCP buffer layer on the electron transport layer.

[0066] A 3-5 nm thick BCP layer is deposited on the C60 layer as a buffer layer between the electrode and the electron transport layer.

[0067] 7. Deposit metal (Ag) electrodes on the BCP buffer layer.

[0068] Finally, a silver layer of approximately 120 nm thickness was deposited on the surface of the BCP buffer layer as a metal electrode by vacuum thermal evaporation to obtain a cesium-based perovskite solar cell. Based on the different concentrations of the aromatic nitrile ethanol solution, the samples were designated as Sample 1 (0.2 mg / mL), Sample 2 (0.4 mg / mL), Sample 3 (0.6 mg / mL), Sample 4 (0.8 mg / mL), and Sample 5 (1.0 mg / mL).

[0069] Comparative Example 1

[0070] Besides NiO x In the process of preparing the SAM layer on the hole transport layer, except that the aromatic nitrile ethanol solution was replaced with Me-4PACz (concentration of 0.6 mg / mL), the rest of the process was the same as in Example 2.

[0071] The perovskite solar cell prepared in Comparative Example 1 is designated as Control Group 1.

[0072] Comparative Example 2

[0073] Besides NiO x During the preparation of the SAM layer on the hole transport layer, the concentration of the aromatic nitrile ethanol solution was 0.6 mg / mL, and CsBr was not added to the aromatic nitrile ethanol solution. The rest of the process was the same as in Example 2.

[0074] The perovskite solar cell prepared in Comparative Example 2 is designated as Control Group 2.

[0075] Test Example 1

[0076] To further confirm that using aromatic nitrile and cesium halide as components of a self-assembled monolayer (SAM layer) can effectively resist moisture erosion of perovskite solar cells, SAM layers prepared with these and Me-4PACz were tested, and the water contact angle of the SAM layers was measured. The results are as follows: Figure 2 As shown;

[0077] Figure A shows the contact angle measurement results when the SAM layer is composed of Me-4PACz, and Figure B shows the contact angle measurement results when the SAM layer is composed of aromatic nitrile and cesium halide (equal molar ratio).

[0078] from Figure 2 It can be seen that when the SAM layer is composed of Me-4PACz, its contact angle is 77.06°; when the SAM layer is composed of aromatic nitrile and cesium halide, its contact angle is 86.19°. This result indicates that the SAM layer composed of aromatic nitrile and cesium halide exhibits strong hydrophobic properties.

[0079] Test Example 2

[0080] To demonstrate the relationship between the aromatic nitrile molecules prepared in Example 1 and NiO x Strong interactions can occur between aromatic nitrile molecules (denoted as P1) and the aromatic nitrile SAM layer prepared according to Comparative Example 2 (denoted as P1 / NiO). x X-ray photoelectron spectroscopy (XPS) was performed, and the results are as follows: Figure 3 As shown in the figure, the N 1s peak of the aromatic nitrile molecule is located near NiO. X Significant displacement (P1 / NiO) was observed after mixing. x The binding energy of N 1s electrons in the sample is shifted by 0.44 eV towards a higher binding energy direction compared to the binding energy of N 1s electrons in P1. This result indicates that the cyano group at the end of P1 binds to NiO. x The terminal oxygen atoms interact strongly, allowing aromatic nitrile molecules to be firmly anchored to the substrate in the form of a monomolecular self-assembled layer.

[0081] Test Example 3

[0082] Scanning electron microscope (SEM) images of the perovskite thin film layers during the preparation process of Example 2 (Sample 3) and Comparative Example 2 (Control Group 2), as shown below. Figure 4 As shown;

[0083] In the figure, A is the SEM image of control group 2, and B is the SEM image of sample 3;

[0084] from Figure 4 As can be seen, the perovskite film in control group 2 has a smaller and more dispersed grain size and a large number of grain boundaries. The perovskite film in sample 3 has significantly larger grains and fewer grain boundaries. This is mainly attributed to the fact that the cesium salt in the SAM layer provides the starting sites for the crystallization of perovskite cations, making the grain distribution on the perovskite film layer more regular and orderly.

[0085] Test Example 4

[0086] The performance of the perovskite solar cells prepared in Example 2, Comparative Example 1, and Comparative Example 2 was tested, as follows:

[0087] I. Battery efficiency testing:

[0088] Each battery was placed under AM 1.5G illumination and JV curve tests were performed. The test results are shown in the table below:

[0089]

[0090] In the table above, Voc (Open-Circuit Voltage) is the open-circuit voltage, Jsc (Short-Circuit Current Density) is the short-circuit current density, FF (Fill Factor) is the fill factor, and PCE (Power Conversion Efficiency) is the photoelectric conversion efficiency.

[0091] The data provided in the table above show that the battery device in control group 2 (SAM layer formed by aromatic nitrile molecules without CsBr doping) has significantly worse electrical performance than that in control group 1 (SAM layer formed by Me-4PACz), while the battery devices in samples 1 to 5 (SAM layer formed by aromatic nitrile molecules doped with CsBr) have significantly improved electrical performance and are significantly better than control group 1.

[0092] II. Testing of hole mobility in the SAM layer.

[0093] The hole mobility of the battery device was tested under dark conditions using an electrochemical workstation and the space charge-confined carrier method (SCLC). The results are shown in the table below:

[0094] Test results of hole mobility in SAM layer

[0095]

[0096] The data provided in the table above show that the hole mobility of samples 1 to 5 is significantly higher than that of control group 2. This result indicates that the synergistic effect of aromatic nitrile and CsBr is beneficial to improving the hole mobility of the SAM layer. When the concentration of the aromatic nitrile ethanol solution is 0.4 mg / mL to 1.0 mg / mL, the hole mobility of samples 2 to 5 is significantly higher than that of control group 1. The SAM layer in the cesium-based perovskite solar cell provided by this invention has a high hole mobility, which is significantly higher than that of control group 1.

[0097] III. Water stability test.

[0098] The battery efficiency of each group of devices was continuously tracked and tested in a dark environment with room temperature and 80% humidity. The test results of the normalized efficiency stability of each group of devices are shown in the table below:

[0099]

[0100] The data provided in the table above show that, as time increases, the efficiency of control group 1 decays significantly faster than that of samples 1 to 5. The efficiency of samples 1 to 5 remains between 90.1% and 92.5% after 2000 hours, which is much higher than that of control group 1. This indicates that the cesium-based perovskite solar cell provided by this invention has excellent water stability.

[0101] IV. Thermal stability test.

[0102] Each group of batteries was placed in a dark environment at 85℃ for continuous aging, and the battery efficiency was tested every 250 hours. The battery thermal stability test results are shown in the table below:

[0103]

[0104] The data provided in the table above show that as time increases, the efficiency decay rate of control group 1 is significantly faster than that of samples 1 to 5. The efficiency of samples 1 to 5 remains between 90.3% and 92.9% after 1250 hours, which is much higher than that of control group 1. This indicates that the cesium-based perovskite solar cell provided by this invention has excellent thermal stability.

[0105] V. Test of photostability.

[0106] The batteries were placed in a nitrogen atmosphere at 65°C and subjected to continuous AM 1.5G light intensity for 1000 hours of aging. Battery efficiency was monitored periodically during this period. The results of the battery light stability test are shown in the table below.

[0107]

[0108] The data provided in the table above show that as time increases, the efficiency decay rate of control group 1 and control group 2 is significantly faster than that of samples 1 to 5. The efficiency of samples 1 to 5 is still maintained between 85.6% and 90.5% after 1000h, which is much higher than that of control group 1 and control group 2. This indicates that the cesium-based perovskite solar cell provided by the present invention has excellent photostability.

[0109] In summary, the cesium-based perovskite solar cell provided by this invention utilizes aromatic nitrile and CsBr to synergistically optimize the crystallinity, interface passivation, and charge transport of the perovskite thin film, reducing non-radiative recombination losses and significantly improving device efficiency. Simultaneously, CsBr improves the wettability of the perovskite precursor on the SAM substrate during the optimized perovskite thin film crystallization process, jointly promoting the formation of a more uniform, dense, high-quality perovskite thin film and reducing interface defects.

[0110] In addition, Cs + With Br - It can improve the thermal stability at the interface of perovskite materials. Aromatic nitrile molecules form a more uniform interface. The synergistic use of the two inhibits the water, heat and photo-induced degradation of perovskite, so that perovskite solar cells can still maintain a high initial efficiency after long-term operation.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a cesium-based perovskite solar cell, characterized by, The method comprises the following steps: S100, preparing a hole transport layer on a conductive glass substrate by a spin coating method; S200, preparing a self-assembled monolayer on the hole transport layer by a spin coating method; In the step, a precursor solution used in the spin coating method is a mixed alcohol solution of aromatic nitrile and cesium halide; The structure of the aromatic nitrile is shown as follows: ； The concentration of the aromatic nitrile in the mixed alcohol solution is 0.4-1.0 mg / mL, and the molar ratio of the aromatic nitrile to the cesium halide is 1:(0.8-1.2); S300, preparing a perovskite film layer on the self-assembled monolayer by a spin coating method; S400, sequentially evaporating a passivation modification layer and an electron transport layer on the perovskite film layer by a vacuum evaporation method; S500, evaporating a BCP buffer layer on the electron transport layer by a vacuum evaporation method; The BCP is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; S600, evaporating a metal electrode on the BCP buffer layer by a vacuum evaporation method.

2. The preparation method of the cesium-based perovskite solar cell according to claim 1, characterized in that, In step S100, the main component of the hole transport layer is selected from nickel oxide.

3. The method for preparing a cesium-based perovskite solar cell as described in claim 1, characterized in that, In step S200, the concentration of the aromatic nitrile in the mixed alcohol solution is 0.4-0.8 mg / mL.

4. The preparation method of the cesium-based perovskite solar cell according to claim 1, characterized in that, In step S200, the cesium halide is selected from cesium bromide.

5. The method for preparing a cesium-based perovskite solar cell as described in claim 1, characterized in that, In step S200, the solvent of the mixed alcohol solution is selected from methanol and / or propanol.

6. The method for preparing a cesium-based perovskite solar cell as described in claim 1, characterized in that, In step S300, the main component of the precursor solution used in the spin coating method is Cs 0.05 (MA 0.05 FA 0.95 ) 0.95 Pb(I 0.95 Br 0.05 )3; The MA is methylamine, and the FA is formamidine.

7. The method for preparing a cesium-based perovskite solar cell as described in claim 1, characterized in that, In step S400, the main component of the passivation modification layer is selected from LiF, and the main component of the electron transport layer is selected from C60.

8. The method for preparing a cesium-based perovskite solar cell as described in claim 1, characterized in that, The thickness of the passivation modification layer is 0.5-1 nm, the thickness of the electron transport layer is 20-25 nm, and the thickness of the BCP buffer layer is 3-5 nm.

9. The method for preparing a cesium-based perovskite solar cell as described in claim 1, characterized in that, In step S600, the metal electrode is an Ag electrode.

10. A cesium-based perovskite solar cell characterized by, The cesium-based perovskite solar cell is prepared by the method of any one of claims 1-9. The cesium-based perovskite solar cell is prepared by the method of any one of claims 1-9.

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