Perovskite solar cell and preparation method thereof

Abstract

This invention discloses a perovskite solar cell and its fabrication method, relating to the field of solar cell technology. A perovskite precursor solution is obtained by mixing a hydrate additive, a perovskite material, and a first solvent. A perovskite absorber layer is then prepared using this perovskite precursor solution. Alternatively, a passivation layer solution is obtained by mixing a hydrate additive, a passivation layer material, and a second solvent. A passivation layer is then prepared using this passivation layer solution, and the passivation layer is in contact with the light-facing surface of the perovskite absorber layer. The hydrate additive has the general structural formula ABnH2O, where A is K. + Na + NH4 + Co 2+ Ca 2+ One or more of them, where B is Cl ‑ I ‑ H2PO4 ‑ and HPO4 2‑ One of them, where n is 1-20. This hydrate additive can effectively passivate defects in the perovskite absorber layer, reduce the defect density of the perovskite absorber layer, reduce non-radiative recombination, and promote ordered grain growth.

Description

Technical Field

[0001] This invention relates to a perovskite solar cell and its fabrication method, and relates to the field of solar cell technology. Background Technology

[0002] Perovskite materials possess excellent photoelectric properties, including high absorption coefficient, low exciton binding energy, long carrier lifetime, high carrier mobility, and tunable bandgap, making them ideal for use as light-absorbing layers in solar cells. However, most widely used perovskite thin films are prepared using solution processing techniques, which inevitably introduce high-density defects during film crystallization. These defects include point defects and extended defects, which can be further classified into shallow-level and deep-level defects. These various types of defects are the main cause of severe non-radiative recombination within the device, thus limiting the improvement of photovoltaic characteristics and stability of solar cell devices.

[0003] Polycrystalline perovskite films prepared by solution methods consist of numerous grains ranging in size from hundreds of nanometers to micrometers. Perovskite grain boundaries and surfaces typically contain many dangling bonds and charged uncoordinated ion defects. These defects become nonradiative recombination centers for photogenerated carriers, trapping them and causing energy loss within the device. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a perovskite solar cell and a method for preparing the same, in order to solve the technical problem that the high density defects generated during the crystallization process of perovskite limit the improvement of the photovoltaic characteristics and stability of solar cell devices.

[0005] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions: In a first aspect, embodiments of the present invention provide a method for preparing a perovskite solar cell, comprising: A perovskite precursor solution is obtained by mixing hydrate additives, perovskite materials and a first solvent, and a perovskite absorber layer is prepared by using the perovskite precursor solution. And / or, A passivation layer solution is obtained by mixing hydrate additives, passivation layer material, and a second solvent. A passivation layer is prepared by using the passivation layer solution, and the passivation layer is in contact with the light-facing surface of the perovskite absorption layer. Among them, the hydrate additive has the general structural formula AB nH2O, where A is K + Na + NH4 + Co 2+ Ca 2+ One or more of them, where B is Cl - I - H2PO4- and HPO4 2- One of them, where n is 1-20.

[0006] Optionally, n can be 1-12.

[0007] Optionally, the hydrate additive is selected from one or more of the following: NaI 2H2O, CaCl2 6H2O, CaHPO4 2H2O, K2HPO4 3H2O, Na2HPO4 2H2O, Na2HPO4 7H2O, Na2HPO4 12H2O, NaNH4HPO4·4H2O, CoCl2 6H2O.

[0008] Optionally, the amount of hydrate additive added to the perovskite precursor solution is 0.1 mM to 10 mM.

[0009] Optionally, the amount of hydrate additive added to the passivation layer solution is 0.1 mM to 10 mM.

[0010] Optionally, the perovskite material is of type ABX3, where A stands for MA. + FA + Cs + 、Rb + MDA 2+ One or more of them, where B is Pb 2+ Sn 2+ One or more of them, where X is I - ,Br - Cl - One or more of them.

[0011] Optionally, the passivation layer material is selected from one or more of phenylethyl iodide, 1,3-diaminopropane dihydroiodate, and ethylenediamine dihydroiodide.

[0012] Optionally, the perovskite absorber layer is prepared by a solution method; and / or, the passivation layer is prepared by a solution method.

[0013] Optionally, the perovskite solar cell is a single-junction perovskite solar cell or a tandem perovskite solar cell.

[0014] Secondly, embodiments of the present invention provide a perovskite solar cell, which is prepared using the perovskite solar cell preparation method described in any of the above embodiments.

[0015] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects: This invention relates to the preparation of a perovskite absorber layer for a perovskite solar cell by introducing a hydrate additive into the perovskite precursor solution; alternatively, by introducing a hydrate additive into the passivation layer solution; or by introducing a hydrate additive into both the perovskite precursor solution and the passivation layer solution. The hydrate additive is a hydrate based on anion and cation compounds. This type of hydrate additive possesses both "dual passivation" and "slow-release micro-water" functions, effectively passivating defects in the perovskite absorber layer, reducing the defect density, minimizing non-radiative recombination, and promoting ordered grain growth, thus significantly improving the photovoltaic performance of the perovskite solar cell. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell according to an embodiment of the present invention; Figure 2 This is a surface SEM (scanning electron microscope) image of the perovskite absorber layer prepared in Example 1 of this invention; Figure 3 This is a surface SEM image of the perovskite absorber layer prepared in Comparative Example 1; Figure 4 These are the PL (photoluminescence) spectra of the perovskite light-absorbing layers of Embodiment 1 and Comparative Examples 1 and 2 of the present invention; Figure 5 These are the PL spectra of the perovskite light-absorbing layers of Embodiment 1 and Comparative Examples 1, 3, 4, and 5 of the present invention.

[0017] Figure label: 10 - Substrate; 20 - Hole transport layer; 30 - Perovskite absorber layer; 40 - Passivation layer; 50 - Electron transport layer; 60 - Barrier layer; 70 - Conductive layer. Detailed Implementation

[0018] Whether for single-junction perovskite solar cells or tandem perovskite solar cells (two-terminal, three-terminal, or four-terminal tandem cells), the performance of the perovskite absorber layer directly affects the performance of the solar cell (such as photoelectric conversion efficiency, carrier collection capacity, carrier transport capacity, and cell stability). Therefore, fabricating a high-performance perovskite absorber layer helps improve the performance of perovskite solar cells. Among these improvements, addressing the structural defects of the perovskite absorber layer is the core issue that needs to be resolved to enhance the photovoltaic characteristics and stability of perovskite solar cells.

[0019] This invention provides a novel preparation method for perovskite absorber layers and / or passivation layers to improve the structural defects of perovskite absorber layers.

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. The embodiments of the present invention are described in detail below. It should also be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Furthermore, unless otherwise explicitly stated, all reagents used in the following embodiments are commercially available or can be synthesized according to known methods, and reaction conditions not listed are readily available to those skilled in the art.

[0022] The method for fabricating perovskite solar cells provided in this invention includes the following steps: A perovskite precursor solution is obtained by mixing hydrate additives, perovskite materials and a first solvent, and a perovskite absorber layer is prepared by using the perovskite precursor solution. And / or, A passivation layer solution is obtained by mixing hydrate additives, passivation layer material, and a second solvent. A passivation layer is prepared by using the passivation layer solution, and the passivation layer is in contact with the light-facing surface of the perovskite absorption layer. Among them, the hydrate additive has the general structural formula AB nH2O, where A is K + Na + NH4 + Co 2+ Ca 2+ One or more of them, where B is Cl - I - H2PO4 - and HPO4 2- One of them, where n is 1-20.

[0023] This invention relates to the preparation of a perovskite absorber layer for a perovskite solar cell by introducing a hydrated additive into the perovskite precursor solution; alternatively, by introducing a hydrated additive into the passivation layer solution; or by introducing a hydrated additive into both the perovskite precursor solution and the passivation layer solution. The hydrated additive is based on anionic and cationic compounds, possessing both "dual passivation" and "slow-release micro-water" functions. It effectively passivates defects in the perovskite absorber layer, reduces the defect density, decreases non-radiative recombination, and promotes ordered grain growth, thus significantly improving the photovoltaic performance of the perovskite solar cell. Furthermore, this hydrated additive avoids the over-wetting and morphology deterioration caused by direct water addition, providing a new approach for achieving high-efficiency and stable perovskite solar cells using additives containing crystal water.

[0024] It should be noted that this perovskite solar cell can be a single-junction perovskite solar cell or a tandem perovskite solar cell. The tandem perovskite solar cell can be a perovskite / crystalline silicon tandem solar cell, a perovskite / perovskite tandem solar cell, or a perovskite / CIGS tandem solar cell. Tandem perovskite solar cells include two-terminal tandem cells, three-terminal tandem cells, and four-terminal tandem cells. The passivation layer is located on at least a portion of the surface of the perovskite absorber layer. Taking a single-junction inverted perovskite solar cell as an example, such as... Figure 1 As shown, the perovskite solar cell includes a substrate 10, a hole transport layer 20, a perovskite absorber layer 30, a passivation layer 40, an electron transport layer 50, a barrier layer 60, and a conductive layer 70 stacked sequentially.

[0025] In some embodiments of the present invention, a hydrate additive can be added to the perovskite precursor solution, and a perovskite absorber layer can be prepared from the perovskite precursor solution with the added hydrate additive. On one hand, the cation in the hydrate additive, namely K... + Na + NH4 + Co 2+ Ca 2+ One or more of these can effectively passivate anion defects (low-coordination I in halide perovskites). - Inverse PbI 3- and cationic MA + Vacancies), cations interact electrostatically with negatively charged defects at the grain boundaries and surface of perovskite films through ionic bonds; the anions in this hydrate additive, namely Cl... - I - H2PO4 -and HPO4 2- One of them can effectively passivate positively charged cation defects (such as low-coordination Pb). 2+ (and halide vacancies). On the other hand, trace amounts of water of crystallization (n = 1-20) form a "micro-water reactor" in the perovskite precursor solution, which can promote the orderly growth of grains, forming larger and more uniform grains and reducing the number of grain boundaries; moreover, the water of crystallization is released in stoichiometric proportions, avoiding perovskite decomposition caused by local water excess. This type of additive has both "dual passivation" and "slow-release micro-water" functions, which can effectively passivate defects in the perovskite absorber layer, reduce the defect density of the perovskite absorber layer, reduce non-radiative recombination, and promote orderly grain growth. Therefore, this hydrate additive can significantly improve the photovoltaic performance of perovskite solar cells.

[0026] In some embodiments of the present invention, a hydrate additive can be added to the passivation layer solution, and the passivation layer of the perovskite solar cell can be prepared by using the passivation layer solution with the added hydrate additive. When the hydrate additive is added to the passivation layer solution on the surface of the perovskite absorber layer, its water of crystallization will be released by heat during the heat treatment (annealing) after the passivation layer is prepared, optimizing and modifying the perovskite surface, creating an interface that is easier to passivate, thereby enhancing the passivation effect of the anions and cations and the passivation layer on the perovskite absorber layer, jointly achieving efficient passivation of interface defects, thereby significantly improving the open-circuit voltage, fill factor and overall photoelectric conversion efficiency of the photovoltaic device.

[0027] In some embodiments of the present invention, hydrate additives can be added to both the perovskite precursor solution and the passivation layer solution. The perovskite absorber layer is prepared using the perovskite precursor solution with the added hydrate additive, and the passivation layer of the perovskite solar cell is prepared using the passivation layer solution with the added hydrate additive. This allows for more efficient passivation of interface defects, thereby significantly improving the open-circuit voltage, fill factor, and overall photoelectric conversion efficiency of the photovoltaic device.

[0028] Optionally, n is 1-12. On the one hand, hydrate additives with 1-12 molecules of water of crystallization can form a stable "micro-water reactor" in the perovskite precursor solution, effectively promoting the orderly growth of grains, forming larger and more uniform grains, reducing the number of grain boundaries, and releasing the water of crystallization in stoichiometric proportions, avoiding perovskite decomposition caused by local water excess. On the other hand, during the heat treatment (annealing) process after the preparation of the passivation layer, the water of crystallization of hydrate additives with 1-12 molecules of water of crystallization is released by heat, optimizing and modifying the perovskite surface, creating an interface that is easier to passivate, thereby enhancing the passivation effect of anions and cations and the passivation layer on the perovskite absorber layer, jointly achieving efficient passivation of interface defects, thereby significantly improving the open-circuit voltage, fill factor and overall photoelectric conversion efficiency of photovoltaic devices.

[0029] Preferably, in some embodiments of the present invention, the hydrate additive is selected from one or more of the following: NaI 2H2O, CaCl2 6H2O, CaHPO4 2H2O, K2HPO4 3H2O, Na2HPO4 2H2O, Na2HPO4 7H2O, Na2HPO4 12H2O, NaNH4HPO4·4H2O, CoCl2 6H₂O. One or more of these hydrate additives are added to the perovskite precursor solution and / or passivation layer solution. The cations in these hydrate additives can effectively passivate anionic defects (low-coordination I₂ in halide perovskites). - Inverse PbI 3- and cationic MA + Vacancies), cations interact electrostatically with negatively charged defects at the grain boundaries and surface of perovskite films through ionic bonds; the anions in this hydrate additive can effectively passivate positively charged cation defects (such as low-coordinated Pb). 2+ (and halide vacancies); In addition, the water of crystallization in these hydrate additives can not only form a stable "micro-water reactor" in the perovskite precursor solution, effectively promoting the orderly growth of grains, forming larger and more uniform grains, and reducing the number of grain boundaries, but also release the water of crystallization in stoichiometric proportions, avoiding perovskite decomposition caused by local water excess; it can also optimize and modify the perovskite surface, creating an interface that is easier to passivate, thereby enhancing the passivation effect of anions and cations and the passivation layer on the perovskite absorption layer, jointly achieving efficient passivation of interface defects, thereby significantly improving the open-circuit voltage, fill factor and overall photoelectric conversion efficiency of photovoltaic devices.

[0030] Optionally, the amount of hydrate additive added to the perovskite precursor solution is 0.1 mM-10 mM. At this concentration, the hydrate additive can effectively passivate anion defects (low-coordination I in halide perovskites). - Inverse PbI 3- and cationic MA + The cations interact electrostatically with negatively charged defects at the grain boundaries and surface of the perovskite film via ionic bonds; the anions in this hydrate additive can effectively passivate positively charged cation defects (such as low-coordinated Pb). 2+(and halide vacancies); additionally, a stable "micro-water reactor" can be formed in the perovskite precursor solution, effectively promoting ordered grain growth, forming larger and more uniform grains, reducing the number of grain boundaries, and releasing crystal water in stoichiometric proportions, avoiding perovskite decomposition caused by localized water excess. Preferably, the amount of hydrate additive added to the perovskite precursor solution is 0.5 mM, 1 mM, 2 mM, 2.5 mM, 4 mM, 4.5 mM, 6 mM, 8 mM, or 10 mM, etc.

[0031] Optionally, the amount of hydrate additive added to the passivation layer solution is 0.1 mM-10 mM. At this concentration, the hydrate additive can optimize and modify the perovskite surface, creating an interface that is more easily passivated. This enhances the passivation effect of the anions and cations, as well as the passivation layer, on the perovskite absorber layer, jointly achieving efficient passivation of interface defects. This significantly improves the open-circuit voltage, fill factor, and overall photoelectric conversion efficiency of the photovoltaic device. Preferably, the amount of hydrate additive added to the passivation layer solution is 0.5 mM, 0.8 mM, 1 mM, 1.5 mM, 2 mM, 3 mM, 4 mM, 6 mM, or 10 mM, etc.

[0032] Optionally, the perovskite material is of type ABX3, where A stands for MA. + (methylamine ion), FA + (formamidinium ion), Cs + (cesium ion), Rb + (rubidium ion), MDA 2+ One or more of (methylene diammonium ion), where B is Pb. 2+ (lead ions), Sn 2+ One or more of (tin ions), where X is I. - (iodide ion), Br - (bromine ion), Cl - One or more of (chloride ions). Optionally, the perovskite absorber layer is prepared using a solution method, such as spin coating, slot coating, inkjet printing, or blade coating. Optionally, the passivation layer material is selected from one or more of phenylethyl ammonium iodide (PEAI), 1,3-diaminopropane dihydroiodate (PDAI2), and ethylenediamine dihydroiodide (EDAI2). Optionally, the passivation layer is prepared using a solution method, such as spin coating, slot coating, inkjet printing, or blade coating.

[0033] The following describes in detail, with reference to specific embodiments, a method for fabricating a perovskite solar cell provided by the present invention.

[0034] Example 1

[0035] Step 1: Use ITO (Indium Tin Oxide) glass as a substrate and clean it. Specifically, the cleaning steps include ultrasonic cleaning for 20 minutes each with cleaning agent, deionized water, acetone, and anhydrous ethanol, followed by drying with a nitrogen gun.

[0036] Step 2: Perform ozone plasma surface treatment on the cleaned and dried ITO surface for 10 minutes. This treatment method uses the strong oxidizing properties of ozone generated under microwaves to clean the residual organic matter and other impurities on the ITO surface. At the same time, it can increase the oxygen vacancies on the ITO surface, thereby increasing the work function of the ITO surface.

[0037] Step 3: Spin-coat a hole transport layer, such as a solution of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz) at a concentration of 0.5 mg / mL, using anhydrous ethanol as the solvent, at a spin speed of 4000 rpm for 30 s, onto the ITO surface treated in Step 2. Then anneal at 100°C for 10 min to form the hole transport layer.

[0038] Step 4: Fabricate a perovskite absorber layer on the hole transport layer described above. Specifically, the fabrication process of the perovskite absorber layer includes: Weigh 192.91 mg of FAI, 23.73 mg of MABr, 451.79 mg of PbI2, 154.14 mg of PbBr2, 18.19 mg of CsI, and 0.91 mg (4 mM) of K2HPO4. Dissolve 3H₂O in 1 mL of DMF:DMSO = 4:1 (volume ratio) and stir for several hours to obtain a perovskite precursor solution. Take 100 µL of the above perovskite precursor solution and spin-coat it onto the surface of the hole transport layer at 3500 rpm for 40 s. Then, add 150 µL of the antisolvent ethyl acetate at 30 s and anneal at 100 °C for 20 min.

[0039] Step 5: Prepare a passivation layer on the perovskite absorber layer. Specifically, the preparation process of the passivation layer includes: Weigh 1 mg of 1,3-diaminopropane dihydroiodate (PDAI2) and dissolve it in 1 mL of isopropanol to obtain a passivation layer solution with a concentration of 1 mg / mL. Take 80 µL of the passivation layer solution and spin-coat it onto the perovskite absorber layer at a speed of 4000 rpm for 30 s, and then anneal it at 100°C for 5 min.

[0040] Step 6: Deposit an electron transport layer C on the surface of the passivation layer using vacuum evaporation. 60 Among them, vapor deposition is carried out under a vacuum of 5×10 -4 The process was carried out under Pa conditions, with an evaporation rate of 0.2 Å / s and an electron transport layer thickness of approximately 20 nm.

[0041] Step 7: Deposit a barrier layer, such as (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), on the surface of the electron transport layer using vacuum evaporation, wherein the evaporation is performed at a vacuum degree of 5 × 10⁻⁶. -4 The process was carried out under Pa conditions, with an evaporation rate of 0.1 Å / s and a barrier layer thickness of approximately 8 nm.

[0042] Step 8: Deposit a conductive layer, such as a silver metal electrode, on the barrier layer using vacuum evaporation, wherein the evaporation is performed at a vacuum degree of 5 × 10⁻⁶. -4 The process was carried out under Pa conditions, with an evaporation rate of 1 Å / s and a conductive layer thickness of approximately 100 nm.

[0043] Example 2

[0044] The difference between this embodiment and Embodiment 1 is as follows: Step 4: Fabricate a perovskite absorber layer on the hole transport layer described above. Specifically, the fabrication process of the perovskite absorber layer includes: Weigh 192.91 mg of FAI, 23.73 mg of MABr, 451.79 mg of PbI₂, 154.14 mg of PbBr₂, and 18.19 mg of CsI, and dissolve them in 1 mL of DMF:DMSO = 4:1 (volume ratio). Stir for several hours to obtain a perovskite precursor solution. Take 100 µL of the above perovskite precursor solution and spin-coat it onto the surface of the hole transport layer at 3500 rpm for 40 s. Then, add 150 µL of the antisolvent ethyl acetate dropwise at 30 s and anneal at 100 °C for 20 min.

[0045] Step 5: Prepare a passivation layer on the perovskite absorber layer. Specifically, the preparation process of the passivation layer includes: Weigh 1 mg of 1,3-diaminopropane dihydroiodate (PDAI2) and 0.46 mg (2 mM) of K2HPO4. Dissolve 3H2O together with 1 mL of isopropanol to obtain a passivation layer solution. Take 80 µL of the passivation layer solution and spin-coat it onto the perovskite absorber layer at 4000 rpm for 30 s, and then anneal it at 100°C for 5 min.

[0046] Example 3

[0047] The difference between this embodiment and Embodiment 1 is as follows: Step 5: Prepare a passivation layer on the perovskite absorber layer. Specifically, the preparation process of the passivation layer includes: Weigh 1 mg of 1,3-diaminopropane dihydroiodate (PDAI2) and 0.46 mg (2 mM) of K2HPO4. Dissolve 3H2O together with 1 mL of isopropanol to obtain a passivation layer solution. Take 80 µL of the passivation layer solution and spin-coat it onto the perovskite absorber layer at 4000 rpm for 30 s, and then anneal it at 100°C for 5 min.

[0048] Example 4

[0049] Step 1: A heterojunction crystalline silicon substrate is used as the base. The heterojunction substrate includes, starting from the back light side, a back metal electrode, a back highly conductive transparent conductive film, a back P-type microcrystalline silicon film, a back intrinsic amorphous silicon film, a silicon substrate, a front intrinsic amorphous silicon film, and a front n-type microcrystalline silicon film.

[0050] Step 2: An ITO composite layer with a thickness of 10 nm is prepared on the light-facing side (i.e., the front n-type microcrystalline silicon film) of the heterojunction bottom cell by magnetron sputtering.

[0051] Step 3: Spin-coat a hole transport layer, such as a solution of (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz) at a concentration of 0.5 mg / mL, using anhydrous ethanol as the solvent, at a spin speed of 4000 rpm for 30 s, and then anneal at 100 °C for 10 min to form the hole transport layer.

[0052] Step 4: Fabricate a perovskite absorber layer on the hole transport layer described above. Specifically, the fabrication process of the perovskite absorber layer includes: Weigh 192.91 mg of FAI, 23.73 mg of MABr, 451.79 mg of PbI2, 154.14 mg of PbBr2, 18.19 mg of CsI, and 0.91 mg (4 mM) of K2HPO4. Dissolve 3H₂O in 1 mL of DMF:DMSO = 4:1 (volume ratio) and stir for several hours to obtain a perovskite precursor solution. Take 100 µL of the above perovskite precursor solution and spin-coat it onto the surface of the hole transport layer at 3500 rpm for 40 s. Then, add 150 µL of the antisolvent ethyl acetate at 30 s and anneal at 100 °C for 20 min.

[0053] Step 5: Preparation of perovskite passivation layer: Weigh 1 mg of 1,3-diaminopropane dihydroiodate (PDAI2) and dissolve it in 1 mL of isopropanol to obtain a passivation layer solution. Take 80 µL of the passivation layer solution and spin-coat it onto the perovskite absorber layer at 4000 rpm for 30 s, and anneal it at 100°C for 5 min.

[0054] Step 6: Deposit an electron transport layer C on the surface of the passivation layer using vacuum evaporation. 60 Among them, vapor deposition is carried out under a vacuum of 5×10 -4The process was carried out under Pa conditions, with an evaporation rate of 0.2 Å / s and an electron transport layer thickness of approximately 20 nm.

[0055] Step 7: Prepare a buffer SnO2 layer with a thickness of 15 nm by ALD (atomic layer deposition).

[0056] Step 8: Prepare a conductive layer on the barrier layer: for example, prepare an indium zinc oxide layer by magnetron sputtering, or prepare a metal electrode layer by vapor deposition or screen printing.

[0057] Example 5

[0058] The difference between this embodiment and embodiment 4 is as follows: Step 4: Fabricate a perovskite absorber layer on the hole transport layer described above. Specifically, the fabrication process of the perovskite absorber layer includes: Weigh 192.91 mg of FAI, 23.73 mg of MABr, 451.79 mg of PbI₂, 154.14 mg of PbBr₂, and 18.19 mg of CsI, and dissolve them in 1 mL of DMF:DMSO = 4:1 (volume ratio). Stir for several hours to obtain a perovskite precursor solution. Take 100 µL of the above perovskite precursor solution and spin-coat it onto the surface of the hole transport layer at 3500 rpm for 40 s. Then, add 150 µL of the antisolvent ethyl acetate dropwise at 30 s and anneal at 100 °C for 20 min.

[0059] Step 5: Prepare a passivation layer on the perovskite absorber layer. Specifically, the preparation process of the passivation layer includes: Weigh 1 mg of 1,3-diaminopropane dihydroiodate (PDAI2) and 0.46 mg (2 mM) of K2HPO4. Dissolve 3H2O together with 1 mL of isopropanol to obtain a passivation layer solution. Take 80 µL of the passivation layer solution and spin-coat it onto the perovskite absorber layer at 4000 rpm for 30 s, and then anneal it at 100°C for 5 min.

[0060] Example 6

[0061] The difference between this embodiment and embodiment 4 is as follows: Step 5: Prepare a passivation layer on the perovskite absorber layer. Specifically, the preparation process of the passivation layer includes: Weigh 1 mg of 1,3-diaminopropane dihydroiodate (PDAI2) and 0.46 mg (2 mM) of K2HPO4. Dissolve 3H2O together with 1 mL of isopropanol to obtain a passivation layer solution. Take 80 µL of the passivation layer solution and spin-coat it onto the perovskite absorber layer at 4000 rpm for 30 s, and then anneal it at 100°C for 5 min.

[0062] Example 7

[0063] The difference between this embodiment and Embodiment 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. The 3H2O was replaced with 0.69 mg (4 mM) of CaHPO4·2H2O, and the rest of the preparation methods and parameters remained the same as in Example 1.

[0064] Example 8

[0065] The difference between this embodiment and Embodiment 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. The 3H2O was replaced with 0.88 mg (4 mM) of CaCl2·6H2O, and the rest of the preparation methods and parameters remained the same as in Example 1.

[0066] Example 9

[0067] The difference between this embodiment and Embodiment 1 is that, in step 4, 0.91 mg (4 mM) of K2HPO4 is added. The 3H2O was replaced with 1.43 mg (4 mM) of Na2HPO4·12H2O, and the rest of the preparation methods and parameters remained the same as in Example 1.

[0068] Example 10

[0069] The difference between this embodiment and Embodiment 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. Replace 3H2O with 0.46 mg (2 mM) of K2HPO4. 3H2O, the rest of the preparation methods and parameters are consistent with those in Example 1.

[0070] Example 11

[0071] The difference between this embodiment and Embodiment 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. 3H2O was replaced with 1.83 mg (8 mM) of K2HPO4. 3H2O, the rest of the preparation methods and parameters are consistent with those in Example 1.

[0072] Example 12

[0073] The difference between this embodiment and Embodiment 2 is that in step 5, 0.46 mg (2 mM) of K2HPO4... 3H2O was replaced with 0.37 mg (2 mM) of NaI. 2H2O, the rest of the preparation methods and parameters are consistent with those in Example 1.

[0074] Example 13

[0075] The difference between this embodiment and Embodiment 2 is that in step 5, 0.46 mg (2 mM) of K2HPO4... The 3H2O was replaced with 0.42 mg (2 mM) of NaNH4HPO4·4H2O, and the rest of the preparation methods and parameters remained the same as in Example 1.

[0076] Example 14

[0077] The difference between this embodiment and Embodiment 2 is that in step 5, 0.46 mg (2 mM) of K2HPO4... Replace 3H2O with 0.48 mg (2 mM) of CoCl2 6H2O, the rest of the preparation methods and parameters are consistent with those in Example 1.

[0078] Example 15

[0079] The difference between this embodiment and Embodiment 2 is that in step 5, 0.46 mg (2 mM) of K2HPO4... Replace 3H2O with 0.23 mg (1 mM) of K2HPO4. 3H2O, the rest of the preparation methods and parameters are consistent with those in Example 1.

[0080] Example 16

[0081] The difference between this embodiment and Embodiment 2 is that in step 5, 0.46 mg (2 mM) of K2HPO4... Replace 3H2O with 0.69 mg (3 mM) of K2HPO4. 3H2O, the rest of the preparation methods and parameters are consistent with those in Example 1.

[0082] Comparative Example 1

[0083] The difference between this comparative example and Example 1 is as follows: Step 4: Weigh 192.91 mg of FAI, 23.73 mg of MABr, 451.79 mg of PbI2, 154.14 mg of PbBr2, and 18.19 mg of CsI, dissolve them in 1 mL of DMF:DMSO = 4:1 (volume ratio), and stir for several hours to obtain a perovskite precursor solution. Take 100 µL of the above perovskite precursor solution and spin-coat it onto the surface of the hole transport layer at 3500 rpm for 40 s. At the 30th s, add 150 µL of the antisolvent ethyl acetate, and anneal at 100 °C for 20 min.

[0084] Comparative Example 2

[0085] The difference between this comparative example and Example 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. 3H2O was replaced with 0.70 mg (4 mM) of K2HPO4, and the rest of the preparation methods and parameters remained the same as in Example 1.

[0086] Comparative Example 3

[0087] The difference between this comparative example and Example 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. Replace 3H2O with 1µL of H2O, and keep the rest of the preparation method and parameters the same as in Example 1.

[0088] Comparative Example 4

[0089] The difference between this comparative example and Example 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. Replace 3H2O with 3µL of H2O, and keep the rest of the preparation method and parameters the same as in Example 1.

[0090] Comparative Example 5

[0091] The difference between this comparative example and Example 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. Replace 3H2O with 5µL of H2O, and keep the rest of the preparation method and parameters the same as in Example 1.

[0092] Comparative Example 6

[0093] The difference between this comparative example and Example 4 is as follows: Step 4: Weigh 192.91 mg of FAI, 23.73 mg of MABr, 451.79 mg of PbI2, 154.14 mg of PbBr2, and 18.19 mg of CsI, dissolve them in 1 mL of DMF:DMSO = 4:1 (volume ratio), and stir for several hours to obtain a perovskite precursor solution. Take 100 µL of the above perovskite precursor solution and spin-coat it onto the surface of the hole transport layer at 3500 rpm for 40 s. At the 30th s, add 150 µL of the antisolvent ethyl acetate, and anneal at 100 °C for 20 min.

[0094] Comparative Example 7

[0095] The difference between this comparative example and Example 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. Replace 3H₂O with 0.68 mg (4 mM) CuCl₂ 2H2O, the rest of the preparation methods and parameters are consistent with those in Example 1.

[0096] Comparative Example 8

[0097] The difference between this comparative example and Example 1 is that in step 4, 0.91 mg (4 mM) of K2HPO4 is added. 3H2O was replaced with 1.52 mg (4 mM) of Pb(CH3CO2)2. 3H2O, the rest of the preparation methods and parameters are consistent with those in Example 1.

[0098] Furthermore, the properties of the materials and devices in Examples 1-16 and Comparative Examples 1-8 were tested as follows.

[0099] The test examples of this application used a simulated light source system to test the single-junction wide-bandgap perovskite solar cells prepared in Examples 1-3, 7-16 and Comparative Examples 1-5, 7-8. The relevant performance test results are shown in Table 1. Table 1

[0100] Note: The average values ​​in Table 1 are calculated based on 10 devices as the test baseline.

[0101] As can be seen from the above test results, Examples 1, 2 and 3 respectively used the hydrate of anionic and cationic compounds, K2HPO4. K₂HPO₄ was added to the perovskite precursor solution to prepare the perovskite absorber layer, to the passivation layer solution to prepare the passivation layer, and simultaneously to both the perovskite precursor solution and the passivation layer solution to prepare both the absorber layer and the passivation layer. This was compared to the method without K₂HPO₄. The wide-bandgap single-junction perovskite solar cell provided by Comparative Example 1 with 3H2O and the wide-bandgap single-junction perovskite solar cell prepared by Comparative Example 2 with added anhydrous K2HPO4 have higher open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (PCE).

[0102] Thanks to the dual passivation and slow-release micro-water functions of this hydrate additive, it can effectively passivate defects at perovskite grain boundaries and surfaces, reducing non-radiative recombination and thus significantly improving battery performance. Furthermore, with increasing H2O dosage (Comparative Examples 3-5), the open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) of the device decrease sharply. Since the concentration of directly added H2O is difficult to control precisely, it easily leads to perovskite phase decomposition (such as the formation of PbI2). However, the crystal water content in this hydrate additive is trace and its release is stoichiometric and controllable, thereby avoiding localized water excess.

[0103] Examples 7-9 involve adding hydrates of anionic and cationic compounds, namely CaHPO4, to perovskite precursor solutions. 2H2O, CaCl2 6H2O, Na2HPO4 The wide-bandgap single-junction perovskite solar cells prepared by 12H2O also have higher open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) compared to Comparative Example 1.

[0104] Examples 10-11: 2 mM and 8 mM of the hydrates K2HPO4 of anionic and cationic compounds were added to the perovskite precursor solution, respectively. The wide-bandgap single-junction perovskite solar cells prepared by 3H2O also have higher open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) compared to Comparative Example 1.

[0105] Examples 12-16: hydrated NaI of anionic and cationic compounds were added to the passivation layer solution, respectively. 2H2O (2mM), NaNH4HPO4·4H2O (2mM), CoCl2 6H2O (2mM), K2HPO4 3H2O (1mM), K2HPO4 The wide-bandgap single-junction perovskite solar cells prepared by 3H2O (3mM) also have higher open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) compared to Comparative Example 1.

[0106] Comparative Examples 7 and 8 respectively added the hydrates of anionic and cationic compounds CuCl2·2H2O and Pb(CH3CO2)2 to the perovskite precursor solution. The wide-bandgap single-junction perovskite solar cell prepared by 3H2O showed a decrease in open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) compared to Comparative Example 1. Among these, Cu²⁺… + Introducing deep-level recombination centers into perovskites, with excess Pb² + Lead clusters may form, which also introduces deep-level traps, therefore Cu² + and Pb² + Introducing CH3COO as a cation not only fails to passivate the device but also introduces deep-level recombination centers, leading to a decline in device performance. Additionally, CH3COO... - It is prone to decomposition during heat treatment and cannot form a stable passivation layer.

[0107] The morphology of the perovskite absorber layers prepared in Example 1 and Comparative Example 1 was observed by scanning electron microscopy (SEM), as follows: Figure 2 and Figure 3 As shown, the hydrate additive K2HPO4 was not added. The perovskite absorber layer corresponding to Comparative Example 1 of 3H2O ( Figure 3 The grain size of the perovskite absorber layer in Example 1, which contains hydrate additives, exhibits significant inhomogeneity and is relatively small; while the perovskite absorber layer in Example 1, which contains hydrate additives, shows significant inhomogeneity. Figure 2 The film grain size is more uniform, and the overall grain size is also slightly larger.

[0108] The perovskite absorption layers prepared in Example 1 and Comparative Examples 1 and 2 were tested according to the present invention. Figure 4 As shown, the PL intensity of Example 1 is significantly increased compared to Comparative Examples 1 and 2, indicating that the interaction between the hydrate additive and the perovskite effectively passivates the defects in the perovskite absorber layer.

[0109] The perovskite absorption layers prepared in Example 1 and Comparative Examples 1, 3, 4 and 5 were tested according to the present invention. Figure 5 As shown, the PL intensity of Example 1 is significantly increased compared to Comparative Examples 1, 3, 4, and 5, indicating that the interaction between the hydrate additive and the perovskite effectively passivates defects in the perovskite absorber layer. Furthermore, in Comparative Examples 3-5, the PL intensity significantly decreases with increasing H2O dosage, indicating that the additional H2O reduces the quality of the perovskite absorber layer and increases defects.

[0110] The perovskite / crystalline silicon tandem solar cells obtained in Examples 4-6 and Comparative Example 6 were tested using a simulated light source system. The relevant performance test results are shown in Table 2. Table 2

[0111] Note: The average values ​​in Table 2 are calculated based on 8 devices as the test benchmark.

[0112] As can be seen from the above test results, Examples 4, 5 and 6 respectively used the hydrate of anionic and cationic compounds, K2HPO4. K₂HPO₄ was added to the perovskite precursor solution to prepare the perovskite absorber layer, to the passivation layer solution to prepare the passivation layer, and simultaneously to both the perovskite precursor solution and the passivation layer solution to prepare both the absorber layer and the passivation layer. This was compared to the method without K₂HPO₄. The perovskite / crystalline silicon tandem solar cell prepared by Comparative Example 6 with 3H2O has higher open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE).

[0113] The above steps are provided only to help understand the structure, method, and core ideas of this invention. Those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A method for preparing a perovskite solar cell, characterized in that, include: A perovskite precursor solution is obtained by mixing hydrate additives, perovskite materials and a first solvent, and a perovskite absorber layer is prepared by using the perovskite precursor solution. And / or, A passivation layer solution is obtained by mixing a hydrate additive, a passivation layer material, and a second solvent. A passivation layer is prepared by using the passivation layer solution, and the passivation layer is in contact with the light-facing surface of the perovskite absorption layer. The hydrate additive has the general structural formula AB. nH2O, where A is K + Na + NH4 + Co 2+ Ca 2+ One or more of them, where B is Cl - I - H2PO4 - and HPO4 2- One of them, where n is 1-20.

2. The method for preparing a perovskite solar cell according to claim 1, characterized in that, n is 1-12.

3. The method for preparing a perovskite solar cell according to claim 2, characterized in that, The hydrate additive is selected from one or more of the following: NaI 2H2O、CaCl2 6H2O、CaHPO4 2H2O、K2HPO4 3H2O、Na2HPO4 2H2O、Na2HPO4 7H2O、Na2HPO4 12H2O、NaNH4HPO4·4H2O、CoCl2 6H2O。 4. The method for preparing a perovskite solar cell according to claim 1, characterized in that, In the perovskite precursor solution, the amount of the hydrate additive added is 0.1 mM-10 mM.

5. The method for preparing a perovskite solar cell according to claim 1, characterized in that, In the passivation layer solution, the amount of the hydrate additive is 0.1 mM-10 mM.

6. The method for preparing a perovskite solar cell according to claim 1, characterized in that, The perovskite material is of type ABX3, where A stands for MA. + FA + Cs + 、Rb + MDA 2+ One or more of them, where B is Pb 2+ Sn 2+ One or more of them, where X is I - ,Br - Cl - One or more of them.

7. The method for preparing a perovskite solar cell according to claim 1, characterized in that, The passivation layer material is selected from one or more of phenylethyl iodide, 1,3-diaminopropane dihydroiodate, and ethylenediamine dihydroiodide.

8. The method for preparing a perovskite solar cell according to claim 1, characterized in that, The perovskite absorber layer is prepared by a solution method; and / or, the passivation layer is prepared by a solution method.

9. The method for preparing a perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell is a single-junction perovskite solar cell or a tandem perovskite solar cell.

10. A perovskite solar cell, characterized in that, The perovskite solar cell was prepared using the method described in any one of claims 1-9.

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