Solar cell and preparation method thereof, photovoltaic module, power generation and power utilization device

Abstract

This application provides a solar cell and its fabrication method, a photovoltaic module, and a power generation and consumption device. The solar cell includes a first electrode, a stacked hole transport layer, a perovskite light-absorbing layer, and a second electrode arranged along a first direction. The stacked hole transport layer and the perovskite light-absorbing layer are stacked between the first and second electrodes, with the stacked hole transport layer disposed on the side of the perovskite light-absorbing layer away from the second electrode. The stacked hole transport layer includes a first hole transport layer and a second hole transport layer, with the second hole transport layer located between the first hole transport layer and the perovskite light-absorbing layer. Both the first and second hole transport layers comprise NiO. x 1 < x < 2; the refractive index of the second hole transport layer is greater than that of the first hole transport layer. The solar cell in this application has improved photoelectric conversion efficiency and stability.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a solar cell and its preparation method, a photovoltaic module, and a power generation and power consumption device. Background Technology

[0002] In recent years, with the increasingly widespread application of solar cells, they have been widely used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, as well as in various fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, and aerospace. With the application and promotion of solar cells, people have increasingly higher requirements for their photoelectric conversion efficiency and stability.

[0003] Therefore, improving the photoelectric conversion efficiency and stability of solar cells has become an urgent problem to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned issues, and its purpose is to provide a solar cell and a method for preparing the same, a photovoltaic module, a power generation and power consumption device, wherein the solar cell has improved photoelectric conversion efficiency and stability.

[0005] To achieve the above objectives, a first aspect of this application provides a solar cell, comprising a first electrode, a stacked hole transport layer, a perovskite light-absorbing layer, and a second electrode arranged along a first direction. The stacked hole transport layer and the perovskite light-absorbing layer are stacked between the first electrode and the second electrode, with the stacked hole transport layer disposed on the side of the perovskite light-absorbing layer away from the second electrode. The stacked hole transport layer includes a first hole transport layer and a second hole transport layer, with the second hole transport layer located between the first hole transport layer and the perovskite light-absorbing layer. Both the first hole transport layer and the second hole transport layer comprise NiO. x , 1 < x < 2; the refractive index of the second hole transport layer is greater than the refractive index of the first hole transport layer.

[0006] In this application, by setting the refractive index of the second hole transport layer to be greater than that of the first hole transport layer, the density of the second hole transport layer is higher than that of the first hole transport layer. In this way, the denser second hole transport layer can block a large number of oxygen atoms from escaping from the first hole transport layer, thereby improving the overall carrier transport capacity and stability of the stacked hole transport layer, and thus improving the photoelectric conversion efficiency and stability of the solar cell.

[0007] In some embodiments, the refractive index of the second hole transport layer is greater than or equal to 2.1; and / or, the refractive index of the first hole transport layer is less than 2.1. Therefore, the second hole transport layer has a higher density, which is more effective in preventing the escape of oxygen atoms from the first hole transport layer, and further improves the photoelectric conversion efficiency and stability of the solar cell.

[0008] In some embodiments, the refractive index of the second hole transport layer is 2.2 to 3.0; and / or, the refractive index of the first hole transport layer is less than 1.0 to 2.0. This is more conducive to improving the photoelectric conversion efficiency and stability of the solar cell.

[0009] In some embodiments, the thickness of the second hole transport layer is less than the thickness of the first hole transport layer. This reduces the impact of the second hole transport layer on carrier transport, improving the carrier transport capability of the stacked hole transport layer, and consequently further enhancing the photoelectric conversion efficiency and stability of the solar cell.

[0010] In some embodiments, the thickness of the second hole transport layer is 0.5 nm to 10 nm. This is beneficial for further improving the photoelectric conversion efficiency and stability of the solar cell.

[0011] In some embodiments, the thickness of the first hole transport layer is 10 nm to 50 nm. This is beneficial for further improving the photoelectric conversion efficiency of the solar cell.

[0012] In some embodiments, the Ni content in the first hole transport layer is based on the total molar content of Ni in the first hole transport layer. 3+ The molar content of Ni is M1. Based on the total molar content of Ni in the second hole transport layer, the molar content of Ni in the second hole transport layer is... 3+ The molar content is M2, where M1 is greater than M2. This is beneficial for further improving the photoelectric conversion efficiency and stability of the solar cell. Furthermore, since the second hole transport layer is adjacent to the perovskite light-absorbing layer, the Ni in the second hole transport layer... 3+ Because of its low content, it is less likely to react with the perovskite material in the perovskite light-absorbing layer at the interface, which helps to improve the stability of the perovskite light-absorbing layer, and thus helps to improve the photoelectric conversion efficiency and stability of the solar cell.

[0013] In some embodiments, the Ni content in the second hole transport layer is based on the total molar content of Ni in the second hole transport layer. 3+ The molar content M2 is 0.1% to 10%. This is beneficial for further improving the photoelectric conversion efficiency and stability of solar cells.

[0014] In some embodiments, the Ni content in the first hole transport layer is based on the total molar content of Ni in the first hole transport layer. 3+ The molar content M1 is 60%–80%. This is beneficial for further improving the photoelectric conversion efficiency and stability of solar cells.

[0015] In some embodiments, the stacked hole transport layer further includes at least one third hole transport layer; the third hole transport layer is located between the first hole transport layer and the second hole transport layer; the refractive index of the third hole transport layer is greater than the refractive index of the first hole transport layer. This is beneficial for further improving the photoelectric conversion efficiency and stability of the solar cell.

[0016] In some embodiments, the refractive index of the third hole transport layer is greater than or equal to 2.1. This is more conducive to improving the photoelectric conversion efficiency and stability of the solar cell.

[0017] In some embodiments, the third hole transport layer comprises NiO. x , 1 < x < 2; Based on the total molar content of Ni in the second hole transport layer, the Ni in the second hole transport layer 3+ The molar content of Ni is M2. Based on the total molar content of Ni in the third hole transport layer, the molar content of Ni in the third hole transport layer is... 3+ The molar content is M3, which is greater than M2. Therefore, the carrier transport capability of the third hole transport layer is better than that of the second hole transport layer, which is beneficial to further improving the photoelectric conversion efficiency and stability of the solar cell.

[0018] In some embodiments, the Ni content in the third hole transport layer is determined based on the total molar content of Ni in the third hole transport layer. 3+ The molar content M3 ranges from 1% to 20%. Therefore, the third hole transport layer exhibits good carrier transport capability, which is beneficial for further improving the photoelectric conversion efficiency of solar cells.

[0019] In some embodiments, one or more of the following conditions are met: (1) the thickness of the second hole transport layer is 0.5 nm to 3 nm; (2) the thickness of the third hole transport layer is 0.5 nm to 7 nm; (3) the sum of the thicknesses of the second hole transport layer and the third hole transport layer is 1 nm to 10 nm. Therefore, the overall carrier transport capability of the stacked hole transport layer is better, which further helps to improve the photoelectric conversion efficiency and stability of the solar cell.

[0020] In some embodiments, the stacked hole transport layer includes multiple third hole transport layers adjacent to the perovskite light-absorbing layer along the first direction, and the Ni content in each third hole transport layer is [value missing]. 3+ The molar content gradually decreases. This is beneficial for improving the carrier transport capability of the stacked hole transport layer, and further beneficial for improving the photoelectric conversion efficiency and stability of the solar cell.

[0021] In some embodiments, the stacked hole transport layer includes multiple third hole transport layers located close to the perovskite light-absorbing layer along the first direction, with the thickness of the third hole transport layer gradually decreasing. This is beneficial for improving the photoelectric conversion efficiency and stability of the solar cell.

[0022] In some embodiments, the stacked hole transport layer includes two layers of the third hole transport layer.

[0023] In some embodiments, the thickness of the stacked hole transport layer is 10.5 nm to 60 nm. This is more conducive to improving the photoelectric conversion efficiency and stability of the solar cell.

[0024] In some embodiments, the perovskite light-absorbing layer comprises a perovskite light-absorbing layer; the perovskite light-absorbing layer comprises at least one of the compounds shown in [A][B][X]3 and [A]2[C][D][X]6, wherein A comprises a monovalent inorganic or organic cation, B comprises a divalent inorganic cation, C comprises a monovalent inorganic cation, D comprises a trivalent inorganic cation, and X comprises a monovalent anion.

[0025] In some embodiments, A includes CH3NH3 + CH(NH2)2 + Li + Na + K + 、Rb + Cs + One or more of the following; B includes Pb 2+ and / or Sn 2+ C includes Li + Na + K + 、Rb + Cs + One or more; X includes F - Cl - ,Br - I - SCN - CNO - OCN -OSCN - SH - OH - CN - SeCN - One or more of them.

[0026] A second aspect of this application provides a method for fabricating a solar cell, comprising: fabricating a first electrode, a stacked hole transport layer, a perovskite light-absorbing layer, and a second electrode arranged along a first direction, wherein the stacked hole transport layer and the perovskite light-absorbing layer are stacked between the first electrode and the second electrode, and the stacked hole transport layer is disposed on the side of the perovskite light-absorbing layer away from the second electrode; wherein the method for fabricating the stacked hole transport layer includes: depositing two layers of NiO on the first electrode. x A first hole transport layer and a second hole transport layer are formed, where 1 < x < 2; the second hole transport layer is disposed on the side of the first hole transport layer away from the first electrode; the refractive index of the second hole transport layer is greater than the refractive index of the first hole transport layer.

[0027] The above method can be used to form a solar cell comprising a first hole transport layer and a second hole transport layer. Since the refractive index of the second hole transport layer is greater than that of the first hole transport layer, the second hole transport layer has a higher density than the first hole transport layer. Therefore, the higher density of the second hole transport layer can prevent oxygen atoms in the first hole transport layer from escaping, which is beneficial to improving the overall carrier transport capacity and stability of the stacked hole transport layer.

[0028] In some embodiments, the first hole transport layer is formed by magnetron sputtering, and / or the second hole transport layer is formed by atomic layer deposition.

[0029] In some embodiments, the method for preparing the stacked hole transport layer further includes: depositing at least one layer of NiO between the first hole transport layer and the second hole transport layer. x 1 < x < 2, forming at least one third hole transport layer; the refractive index of the third hole transport layer is greater than the refractive index of the first hole transport layer.

[0030] In some embodiments, the third hole transport layer is formed by atomic layer deposition.

[0031] A third aspect of this application provides a photovoltaic module, including the solar cell described in the first aspect above, or including a solar cell prepared according to the preparation method described in the second aspect above.

[0032] A fourth aspect of this application provides a power generation device, including the solar cell described in the first aspect above, or including a solar cell prepared according to the preparation method described in the second aspect above.

[0033] The fifth aspect of this application provides an electrical device comprising the solar cell described in the first aspect above, or comprising a solar cell prepared according to the preparation method described in the second aspect above. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a solar cell according to one embodiment of this application. Figure 1 .

[0035] Figure 2 This is a schematic diagram of the structure of a solar cell according to one embodiment of this application. Figure 2 .

[0036] Figure 3 This is a schematic diagram of the structure of a solar cell according to one embodiment of this application. Figure 3 .

[0037] Figure 4 This is the distribution curve of nickel element with depth in the stacked hole transport layer prepared in Example 1.

[0038] Explanation of reference numerals in the attached figures:

[0039] 100: Solar cell; 10: First electrode; 20: Stacked hole transport layer; 201: First hole transport layer; 202: Second hole transport layer; 203: Third hole transport layer; 203-1: First layer of third hole transport layer; 203-2: Second layer of third hole transport layer; 30: Perovskite light-absorbing layer; 50: Second electrode. Detailed Implementation

[0040] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the solar cell and its fabrication method, photovoltaic module, power generation, and power consumption device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0041] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0042] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0043] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0044] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0045] Unless otherwise specified, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0046] Unless otherwise specified, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in this application.

[0047] Unless otherwise specified, the term "arranged / set on" means to provide or set one component on another component. The first component may be provided directly on or set on the second component, or a third component may be present between the first and second components. For example, if the first layer is set on the second layer, this includes cases where there is an intermediate third layer between the first and second layers.

[0048] Against the backdrop of ever-increasing global demand for clean energy, perovskite solar cells have become a research hotspot and development focus in the solar photovoltaic field due to their superior photoelectric conversion efficiency and relatively low cost. The hole transport layer, as a key component of perovskite solar cells, plays a decisive role in the overall performance of the cell. Among many materials suitable for the hole transport layer, nickel oxide has become an indispensable choice due to its suitable band structure, good chemical stability, and excellent compatibility with perovskite materials. Currently, to enable the nickel oxide hole transport layer to have excellent carrier transport capability, excess oxygen atoms are usually introduced into the nickel oxide layer, forming oxygen interstices. Oxygen atoms can oxidize divalent nickel in nickel oxide to trivalent nickel, thereby generating additional holes, improving the carrier transport capability of the hole transport layer, and thus enhancing the photoelectric conversion efficiency of the perovskite solar cell.

[0049] However, the excess oxygen atoms (i.e., oxygen interstitials) in the hole transport layer are mainly concentrated in the grain boundaries and surface regions. This distribution makes the oxygen interstitials metastable, and oxygen atoms easily escape during prolonged storage. This escape of oxygen atoms causes the trivalent nickel in the hole transport layer to convert back to divalent nickel, reducing the carrier transport capacity of the hole transport layer. Furthermore, it significantly reduces the stability of the hole transport layer, thus limiting the photoelectric conversion efficiency and stability of perovskite solar cells.

[0050] To address the aforementioned issues, related technologies employ methods such as applying an interface layer onto the hole transport layer. Specifically, one approach involves preparing an organic interface layer on the hole transport layer, such as a self-assembled molecule or a small organic molecule; another approach involves preparing an inorganic interface layer on the hole transport layer, such as a fluoride or an oxide. Introducing either an organic or inorganic interface layer can, to some extent, suppress oxygen escape and improve the photoelectric conversion efficiency and stability of perovskite solar cells. However, the anchoring between the organic interface layer and the hole transport layer may be poor, and there may be lattice mismatch issues between the inorganic interface layer and the hole transport layer. This can easily introduce new stresses at the interface between the hole transport layer and the inorganic interface layer, similarly affecting its protective effect on the hole transport layer. Therefore, the related technologies that improve the stability of the hole transport layer through interface layer modification have many shortcomings, and their effect on improving the photoelectric conversion efficiency and stability of perovskite solar cells is limited.

[0051] Based on this, this application proposes a solar cell and its fabrication method, a photovoltaic module, a power generation device, and an electrical consumption device. The solar cell in this application has improved photoelectric conversion efficiency and stability. The following provides a more detailed description of this application and its optional embodiments.

[0052] Solar cells

[0053] The first aspect of the embodiments of this application provides a solar cell, such as... Figure 1 As shown, the solar cell 100 includes a first electrode 10, a stacked hole transport layer 20, a perovskite light-absorbing layer 30, and a second electrode 50 arranged along a first direction. The stacked hole transport layer 20 and the perovskite light-absorbing layer 30 are stacked between the first electrode 10 and the second electrode 50, with the stacked hole transport layer 20 disposed on the side of the perovskite light-absorbing layer 30 away from the second electrode 50. The stacked hole transport layer 20 includes a first hole transport layer 201 and a second hole transport layer 202, with the second hole transport layer 202 located between the first hole transport layer 201 and the perovskite light-absorbing layer 30. Both the first hole transport layer 201 and the second hole transport layer 202 comprise NiO. x , 1 < x < 2; the refractive index of the second hole transport layer 202 is greater than the refractive index of the first hole transport layer 201.

[0054] In this paper, the term "refractive index" can be defined as the ratio of the speed of light in a vacuum to the speed of light in a medium. In this application, the refractive indices of the first hole transport layer and the second hole transport layer respectively reflect the packing density of the first hole transport layer and the second hole transport layer. The refractive index and density of the material satisfy the Lorentz-Lorenz formula, as shown in Equation 1 below:

[0055]

[0056] Where n is the refractive index of the material, N A Here, ρ is Avogadro's constant, α is the polarizability of molecules in the substance, ρ is the density of the substance, and M is the molar mass of the substance. As can be seen from Equation 1, the refractive index of a substance depends on the polarizability, density, and molar mass of its molecules. For the same substance, its molar mass and molecular polarizability are usually constant. Therefore, the refractive index of a substance can be used to reflect its density, i.e., its compactness. Thus, in this application, a higher refractive index corresponds to a higher density of the hole transport layer.

[0057] In this application, the refractive indices of the first hole transport layer and the second hole transport layer can be tested using instruments or methods known in the art. For example, a step-by-step stripping method combined with ellipsometer measurement can be used. First, the ellipsometer is used to measure the refractive index N of the stacked hole transport layer to obtain the refractive index N of the stacked hole transport layer.t Thickness D of the stacked hole transport layer t The upper second hole transport layer is then removed using selective etching (such as plasma etching) or mechanical polishing. Before the formal experiment, the etching process is calibrated to determine the etching rate, i.e., the amount of material removed per unit time. By controlling the etching time, the removal progress can be controlled more precisely. After each etching of the second hole transport layer, the remaining structure is measured using an ellipsometer to obtain the current refractive index, thickness, and other optical parameters. Since the refractive indices of different film layers are different, when the measured refractive index is close to the theoretical value of the refractive index of the lower first hole transport layer, it indicates that the upper second hole transport layer has been almost completely removed. The removal and detection process is repeated in the above manner until the upper second hole transport layer is completely removed. Next, the remaining first hole transport layer is measured using an ellipsometer to obtain the refractive index N1 and the thickness D1 of the first hole transport layer. Finally, the refractive index N2 and the thickness D2 of the second hole transport layer are calculated according to the following formulas (2) and (3):

[0058]

[0059] D2 = D t -D1 (3)

[0060] In this application, the solar cell includes a stacked hole transport layer composed of a first hole transport layer and a second hole transport layer. The second hole transport layer is closer to the perovskite light-absorbing layer. By setting the refractive index of the second hole transport layer to be greater than that of the first hole transport layer, the density of the second hole transport layer is higher than that of the first hole transport layer. In this way, the higher density of the second hole transport layer can block a large number of oxygen atoms from escaping from the first hole transport layer, thereby improving the overall carrier transport capacity and stability of the stacked hole transport layer, and thus improving the photoelectric conversion efficiency and stability of the solar cell.

[0061] Understandably, the first direction in this application can be the thickness direction of a regular-shaped (e.g., rectangular) solar cell. In some embodiments, the first direction can also be the light incident direction or the opposite direction of the light incident direction.

[0062] In some embodiments, the refractive index of the second hole transport layer is greater than or equal to 2.1; optionally, the refractive index of the second hole transport layer is 2.2 to 3.0. This reflects a higher density in the second hole transport layer, which is more effective in preventing the escape of oxygen atoms from the first hole transport layer, and thus helps to further improve the photoelectric conversion efficiency and stability of the solar cell. Exemplarily, the refractive index of the second hole transport layer is a value between 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, or any two of these values.

[0063] In some embodiments, the refractive index of the first hole transport layer is less than 2.1; optionally, the refractive index of the first hole transport layer is between 1.0 and 2.0. This results in a lower density and smaller grain size in the first hole transport layer, with a greater number of defects and grain boundaries, which helps to increase hole migration paths, improve hole transport efficiency, and thus enhance the photoelectric conversion efficiency of the solar cell. For example, the refractive index of the first hole transport layer is a value between 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, or any two of these values.

[0064] In some embodiments, the thickness of the second hole transport layer is less than the thickness of the first hole transport layer. In this application, the second hole transport layer has a high density, mainly serving to prevent oxygen atoms from escaping from the first hole transport layer. However, high density can also restrict carrier movement, thus affecting carrier transport. Therefore, controlling the thickness of the second hole transport layer to be smaller than that of the first hole transport layer can weaken the influence of the second hole transport layer on carrier transport, which is beneficial to improving the carrier transport capability of the stacked hole transport layer, and thus further improving the photoelectric conversion efficiency and stability of the solar cell.

[0065] In some embodiments, the thickness of the second hole transport layer is 0.5 nm to 10 nm, optionally 3 nm to 5 nm. The high density of the second hole transport layer can affect the carrier transport capability of the stacked hole transport layer to some extent. Therefore, controlling the thickness of the second hole transport layer within the aforementioned range can improve the overall carrier transport capability of the stacked hole transport layer, which is beneficial for further improving the photoelectric conversion efficiency and stability of the solar cell. For example, the thickness of the second hole transport layer is 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, or any value within a range of two such values.

[0066] In some embodiments, the thickness of the first hole transport layer is 10 nm to 50 nm, optionally 10 nm to 30 nm. In this application, the first hole transport layer has good carrier transport capability. By controlling the thickness of the first hole transport layer within the above range, it is beneficial for the extraction and transport of carriers in the solar cell, thereby improving the carrier transport capability of the stacked hole transport layer. Furthermore, it can maintain high light transmittance, which is beneficial for further improving the photoelectric conversion efficiency of the solar cell. For example, the thickness of the first hole transport layer is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, or a value within a range consisting of any two of these values.

[0067] In this application, the term "layer" refers to any substantially layered structure. A layer may have a thickness that varies along its length. Typically, the thickness of a layer is approximately constant. The "thickness" of a layer as used in this application refers to the average thickness of the layer. It should be understood that layers in this application may have different thicknesses in different directions. Unless otherwise specified, the "thickness" of a "layer" in this application has the meaning commonly understood by those skilled in the art. For example, the thickness of the first hole transport layer and the second hole transport layer can be understood as the thickness of the first hole transport layer and the second hole transport layer along a first direction.

[0068] In this application, the thicknesses of the first hole transport layer and the second hole transport layer can be measured using conventional methods in the art. For example, they can be measured using an ellipsometer.

[0069] In this application, the first hole transport layer and the second hole transport layer include NiO. x , 1 < x < 2. Wherein, Ni exists as divalent nickel (Ni) in both the first and second hole transport layers. 2+ ) and trivalent nickel (Ni 3+ It exists in the form of ). Because Ni releases additional free electrons when it is oxidized from divalent to trivalent (reaction formula: Ni... 2+ →Ni 3+ +e - Therefore, for each trivalent nickel ion present, an additional free electron is generated. These free electrons can move under the influence of an electric field, thereby improving the carrier transport capability. Thus, the Ni in the first and second hole transport layers... 3+ A higher content of this reflects a better transport layer capability of the first and second hole transport layers.

[0070] In some implementations, the Ni content in the first hole transport layer is determined based on the total molar content of Ni in the first hole transport layer. 3+ The molar content of Ni is M1. Based on the total molar content of Ni in the second hole transport layer, the molar content of Ni in the second hole transport layer is...3+ The molar content is M2, where M1 is greater than M2. In this application, the Ni in the second hole transport layer... 3+ The content of Ni in the second hole transport layer is lower than that in the first hole transport layer, reflecting that the first hole transport layer has a higher carrier transport capability, while the content of Ni in the second hole transport layer is lower than that in the first hole transport layer. 3+ The lower oxygen content, meaning fewer excess oxygen atoms in the second hole transport layer, results in less oxygen atom escape and less deterioration of carrier transport capability. This is beneficial for further improving the overall carrier transport capability and stability of the stacked hole transport layer, thus contributing to improved photoelectric conversion efficiency and stability of the solar cell. Furthermore, since the second hole transport layer is adjacent to the perovskite light-absorbing layer, the Ni content in the second hole transport layer... 3+ Because of its low content, it is less likely to react with the perovskite material in the perovskite light-absorbing layer at the interface, which helps to improve the stability of the perovskite light-absorbing layer, and thus helps to improve the photoelectric conversion efficiency and stability of the solar cell.

[0071] In some implementations, the Ni content in the second hole transport layer is determined based on the total molar content of Ni in the second hole transport layer. 3+ The molar content M2 is 0.1% to 10%. Therefore, the Ni content of the second hole transport layer itself... 3+ A lower content of Ni, meaning fewer excess oxygen atoms in the second hole transport layer, results in less oxygen atom escape and less deterioration of carrier transport capability. Furthermore, it has a smaller impact on the stability of the perovskite light-absorbing layer, thus contributing to further improvements in the photoelectric conversion efficiency and stability of the solar cell. For example, based on the total molar content of Ni in the second hole transport layer, the Ni content in the second hole transport layer... 3+ The molar content M2 is 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, or any value within a range of any two values.

[0072] In some implementations, the Ni content in the first hole transport layer is determined based on the total molar content of Ni in the first hole transport layer. 3+ The molar content M1 is 60%–80%, optionally 70%–75%. Ni in the first hole transport layer 3+ The molar content of Ni within the above range reflects that the first hole transport layer has a high carrier transport capacity, which is beneficial to improving the photoelectric conversion efficiency and stability of the solar cell. For example, based on the total molar content of Ni in the first hole transport layer, the Ni content in the first hole transport layer... 3+ The molar content M1 is 60%, 65%, 70%, 75%, 80%, or any value within a range of two such values.

[0073] In this application, Ni in the first hole transport layer and the second hole transport layer 3+ The molar content of nickel can be tested using conventional methods in the field. Specifically, X-ray photoelectron spectroscopy (XPS) is used to determine the elemental composition and chemical state of the sample by measuring the energy and number of photoelectrons excited when the sample surface is irradiated by X-rays, allowing for qualitative and quantitative characterization. Specifically, firstly, XPS testing is performed on the first or second hole transport layer of the sample surface, recording the composition and chemical state of the first or second hole transport layer surface. Then, the XPS-treated first or second hole transport layer surface is etched using an argon ion beam to expose the untested surface. XPS testing is then performed again, followed by further etching. An XPS scan is performed after each etching, recording the elemental composition and chemical state at the current depth. Through repeated etching and measurement, a nickel content distribution curve as a function of depth is constructed. Based on this curve, the nickel content in the first and second hole transport layers can be determined. 3+ content.

[0074] In some embodiments, the stacked hole transport layer further includes at least one third hole transport layer; the third hole transport layer is located between the first hole transport layer and the second hole transport layer; the refractive index of the third hole transport layer is greater than that of the first hole transport layer. In this application, by setting the refractive index of the third hole transport layer to be greater than that of the first hole transport layer, the density of the third hole transport layer is higher than that of the first hole transport layer. This allows the third hole transport layer to further block the escape of oxygen atoms from the first hole transport layer, thereby allowing the Ni atoms in the first hole transport layer to escape. 3+ A higher content of this material is beneficial for further improving the carrier transport capacity and stability of the stacked hole transport layer, which in turn is beneficial for further improving the photoelectric conversion efficiency and stability of the solar cell.

[0075] In some embodiments, the refractive index of the third hole transport layer is greater than or equal to 2.1; alternatively, the refractive index of the third hole transport layer is between 2.1 and 2.5. This results in a higher density of the third hole transport layer, which is more effective in preventing the escape of oxygen atoms from the first hole transport layer, and further improves the photoelectric conversion efficiency and stability of the solar cell. Exemplarily, the refractive index of the third hole transport layer is a value between 2.1, 2.2, 2.3, 2.4, 2.5, or any two of these values.

[0076] In some implementations, the third hole transport layer comprises NiO. x 1 < x < 2, based on the total molar content of Ni in the second hole transport layer, the Ni content in the second hole transport layer... 3+The molar content of Ni is M2, based on the total molar content of Ni in the third hole transport layer. 3+ The molar content is M3, which is greater than M2. Therefore, the carrier transport capability of the third hole transport layer is better than that of the second hole transport layer, which is beneficial to further improving the photoelectric conversion efficiency and stability of the solar cell.

[0077] In some implementations, the Ni content in the third hole transport layer is based on the total molar content of Ni in the third hole transport layer. 3+ The molar content M3 of Ni is 1% to 20%, optionally 1% to 10%. Therefore, the third hole transport layer has good carrier transport capability, which is beneficial for further improving the photoelectric conversion efficiency of the solar cell. For example, based on the total molar content of Ni in the third hole transport layer, the Ni content in the third hole transport layer... 3+ The molar content M3 is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, or any value within a range of two values.

[0078] In some implementations, the stacked hole transport layer includes a third hole transport layer. For example... Figure 2 As shown, the solar cell 100 includes a first electrode 10, a stacked hole transport layer 20, a perovskite light-absorbing layer 30, and a second electrode 50 arranged sequentially along a first direction. The stacked hole transport layer 20 includes a first hole transport layer 201, a third hole transport layer 203, and a second hole transport layer 202 arranged along the first direction. The third hole transport layer 203 is located between the first hole transport layer 201 and the second hole transport layer 202, and the second hole transport layer 202 is located between the third hole transport layer 203 and the perovskite light-absorbing layer 30.

[0079] In some embodiments, when the stacked hole transport layer includes a third hole transport layer, the thickness of the second hole transport layer is 0.5 nm to 3 nm; optionally, it is 1 nm to 2 nm; the thickness of the third hole transport layer is 0.5 nm to 7 nm; optionally, it is 1 nm to 5 nm. The sum of the thicknesses of the second and third hole transport layers is 1 nm to 10 nm; optionally, it is 2 nm to 7 nm. When the thicknesses of the second and third hole transport layers, as well as the sum of their thicknesses, are within the above ranges, the overall carrier transport capability of the stacked hole transport layer is better, which is beneficial for further improving the photoelectric conversion efficiency and stability of the solar cell. For example, the thickness of the second hole transport layer is 0.5nm, 1nm, 2nm, 3nm, or any value within a range of two values; the thickness of the third hole transport layer is 0.5nm, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, or any value within a range of two values; and the sum of the thicknesses of the second and third hole transport layers is 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, or any value within a range of two values.

[0080] In some implementations, the stacked hole transport layer includes two third hole transport layers. For example... Figure 3 As shown, the solar cell 100 includes a first electrode 10, a stacked hole transport layer 20, a perovskite light-absorbing layer 30, and a second electrode 50 arranged sequentially along a first direction. The stacked hole transport layer 20 includes a first hole transport layer 201, a first third hole transport layer 203-1, a second third hole transport layer 203-2, and a second hole transport layer 202 arranged along the first direction. The first third hole transport layer 203-1 is located between the first hole transport layer 201 and the second third hole transport layer 203-2, the second third hole transport layer 203-2 is located between the first third hole transport layer 203-1 and the second hole transport layer 202, and the second hole transport layer 202 is located between the second third hole transport layer 203-2 and the perovskite light-absorbing layer 30.

[0081] In some implementations, please refer to [link / reference]. Figure 3The refractive index of the first third hole transport layer 203-1 is greater than that of the first hole transport layer 201, and the refractive index of the second third hole transport layer 203-2 is greater than that of the first hole transport layer 201. Therefore, both the first and second third hole transport layers 203-1 and 203-2 are denser than the first hole transport layer 201. This allows the escape of oxygen atoms from the first hole transport layer 201 to be blocked, which is more conducive to improving the photoelectric conversion efficiency and stability of the solar cell.

[0082] In some implementations, the refractive index of the first third hole transport layer is greater than or equal to 2.1.

[0083] In some implementations, the refractive index of the second third hole transport layer is greater than or equal to 2.1.

[0084] In some implementations, the Ni content in the first-third hole transport layer is determined based on the total molar content of Ni in the first-third hole transport layer. 3+ The molar content is M3-1, based on the total molar content of Ni in the second hole transport layer, the Ni content in the second hole transport layer is... 3+ The molar content is M2, and M3-1 is greater than M2. This is beneficial for improving the carrier transport capability of the stacked hole transport layer, and further beneficial for improving the photoelectric conversion efficiency and stability of the solar cell.

[0085] In some implementations, the Ni content in the second and third hole transport layers is determined based on the total molar content of Ni in the second and third hole transport layers. 3+ The molar content is M3-2, based on the total molar content of Ni in the second hole transport layer, the Ni content in the second hole transport layer is... 3+ The molar content is M2, and M3-2 is greater than M2. This is beneficial for improving the carrier transport capability of the stacked hole transport layer, and further beneficial for improving the photoelectric conversion efficiency and stability of the solar cell.

[0086] In some implementations, the Ni content in the first-third hole transport layer is determined based on the total molar content of Ni in the first-third hole transport layer. 3+ The molar content is M3-1, based on the total molar content of Ni in the second and third hole transport layers, the Ni content in the second and third hole transport layers is... 3+ The molar content is M3-2, where M3-1 is greater than M3-2. This is beneficial for improving the carrier transport capability of the stacked hole transport layer, and further for improving the photoelectric conversion efficiency and stability of the solar cell.

[0087] In some implementations, the Ni content in the first-third hole transport layer is determined based on the total molar content of Ni in the first-third hole transport layer. 3+ The molar content of Ni is 1% to 20%, optionally 15% to 20%. This is beneficial for improving the carrier transport capability of the stacked hole transport layer, and further beneficial for improving the photoelectric conversion efficiency and stability of the solar cell. For example, based on the total molar content of Ni in the first and third hole transport layers, the Ni content in the first and third hole transport layers... 3+ The molar content is 1%, 3%, 5%, 7%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or any value within a range of two values.

[0088] In some implementations, the Ni content in the second and third hole transport layers is determined based on the total molar content of Ni in the second and third hole transport layers. 3+ The molar content of Ni is 1% to 20%, optionally 10% to 15%. This is beneficial for improving the carrier transport capability of the stacked hole transport layer, and further beneficial for improving the photoelectric conversion efficiency and stability of the solar cell. For example, based on the total molar content of Ni in the second and third hole transport layers, the Ni content in the second and third hole transport layers... 3+ The molar content is 1%, 3%, 5%, 7%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 17%, 19%, 20%, or any value within a range of two values.

[0089] In some embodiments, the stacked hole transport layer includes a first hole transport layer, two third hole transport layers, and a second hole transport layer. The thickness of the second hole transport layer is 0.2 nm to 10 nm; optionally, it is 1 nm to 3 nm. The thickness of the second and third hole transport layers is 0.3 nm to 10 nm; optionally, it is 1 nm to 5 nm. The thickness of the first and third hole transport layers is 0.5 nm to 10 nm; optionally, it is 1 nm to 7 nm. The sum of the thicknesses of the second, second, and third hole transport layers is 1 nm to 10 nm; optionally, it is 3 nm to 8 nm. The thicknesses of the second, first, and third hole transport layers being within the above ranges result in good carrier transport capability of the overall stacked hole transport layer, which is beneficial for further improving the photoelectric conversion efficiency and stability of the solar cell. For example, the thickness of the second hole transport layer is 0.2nm, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, or any value within a range of two such values; the thickness of the second third hole transport layer is 0.3nm, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, or any value within a range of two such values; and the thickness of the first third hole transport layer is 0.5nm, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, or any value within a range of two such values.

[0090] In some implementations, the stacked hole transport layer includes multiple third hole transport layers. For example, the stacked hole transport layer includes three or more third hole transport layers, such as three, four, five or more third hole transport layers.

[0091] In some embodiments, the stacked hole transport layer includes multiple third hole transport layers adjacent to the perovskite light-absorbing layer along a first direction, and the Ni content in each third hole transport layer is based on the total molar content of Ni in each third hole transport layer. 3+ The molar content gradually decreases. This is beneficial for improving the carrier transport capability of the stacked hole transport layer, and further beneficial for improving the photoelectric conversion efficiency and stability of the solar cell.

[0092] In some embodiments, the stacked hole transport layer includes multiple third hole transport layers that are close to the perovskite light-absorbing layer along the first direction, with the thickness of the third hole transport layers gradually decreasing. This is beneficial for improving the photoelectric conversion efficiency and stability of the solar cell.

[0093] It should be noted that the refractive index of the third hole transport layer and the Ni in the third hole transport layer...3+ The testing methods for the molar content and thickness of the third transport layer can be understood by referring to the above-mentioned methods for the first hole transport layer and the second hole transport layer, and will not be repeated here.

[0094] In some embodiments, the thickness of the stacked hole transport layer is 10.5 nm to 60 nm, optionally 20 nm to 30 nm. This is beneficial for improving the photoelectric conversion efficiency and stability of the solar cell. Exemplarily, the thickness of the stacked hole transport layer is 10.5 nm, 11 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, or any value within a range of two such values.

[0095] The term "electrode" refers to a region or layer that is composed of or is substantially composed of electrode material.

[0096] In some implementations, please refer to [link / reference]. Figures 1 to 3 The first electrode 10 is used to collect holes, and the second electrode 50 is used to collect electrons.

[0097] In some embodiments, one of the first electrode 10 and the second electrode 50 is a transparent electrode. This transparent electrode is the first to receive incident light and may also be referred to as the front electrode. Exemplarily, the transparent electrode may include a transparent conductive material. This application does not particularly limit the transparent conductive material. Exemplarily, the transparent conductive material includes one or more of the following: tin oxide, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium-doped zinc oxide (IZO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide, antimony-doped tin oxide, indium-doped tungsten oxide (IWO), indium-doped chromium oxide (ICrO), indium-doped titanium oxide (ITiO), and graphene.

[0098] In some embodiments, the other electrode in the first electrode 10 and the second electrode 50 is the electrode that last receives the incident light, also referred to as the back electrode. The back electrode may include one or more of the following: metal, transparent conductive oxide, metal and its alloy, carbon elemental material, and organic conductive material. Exemplarily, the metal includes one or more of Au, Ag, Cu, Al, Ni, Cr, Bi, Pt, and Mg. Exemplarily, the metal and its alloy include one or more of gold, silver, copper, aluminum, nickel, chromium, bismuth, platinum, magnesium, molybdenum, and tungsten; the transparent conductive oxide includes one or more of indium tin oxide (ITO), lanthanide-doped indium oxide, fluorine-doped tin oxide (FTO), antimony-doped tin oxide, boron-doped zinc oxide (BZO), zinc aluminum oxide (AZO), indium zinc oxide (IZO), gallium zinc oxide (GZO), and indium tungsten oxide (IWO); the carbon elemental material includes one or more of graphite, graphene, and carbon nanotubes; the organic conductive material includes at least one of poly(3,4-ethylenedioxythiophene), polythiophene, and polyacetylene.

[0099] In some embodiments, the first electrode 10 is a transparent electrode that first receives incident light. In this case, the resulting solar cell is a reverse solar cell (pin). In this application, Figures 1 to 3 The solar cell shown is a schematic diagram of an inverted solar cell.

[0100] In some embodiments, the thickness of the transparent electrode is 10 nm to 1000 nm, optionally 80 nm to 700 nm. Exemplarily, the thickness of the transparent electrode is a value between 10 nm, 50 nm, 80 nm, 100 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 1000 nm, or any two of these values. In some embodiments, the thickness of the back electrode is 10 nm to 200 nm, optionally 80 nm to 120 nm. Exemplarily, the thickness of the back electrode is a value between 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, or any two of these values.

[0101] In some implementations, the perovskite light-absorbing layer can generate electron-hole pairs based on the excitation of incident light.

[0102] In some embodiments, the perovskite light-absorbing layer includes at least one of the compounds shown in [A][B][X]3 and [A]2[C][D][X]6, wherein A includes one or more of a monovalent inorganic cation, an organic cation, or a mixed organic-inorganic cation; B includes at least one inorganic divalent cation; C includes at least one inorganic monovalent cation; D includes at least one inorganic trivalent cation; and X includes a monovalent anion.

[0103] For example, inorganic monovalent cations include Li + Na + K + 、Rb + and Cs + One or more of them.

[0104] For example, organic monovalent cations include (NR1R2R3R4). + (R1R2N=CR3R4) + (R1R2N-C(R5)=NR3R4) + Or (R1R2N-C(NR5R6)=NR3R4) + One or more of the following, wherein R1, R2, R3, R4, R5, and R6 are each independently selected from H, substituted or unsubstituted C1 to C20 alkyl groups, or substituted or unsubstituted aryl groups. Optionally, the organic monovalent cation includes one or more of methylamino, ethylamino, propylamino, butylamino, pentamino, hexamino, formamidinyl, and imidazolyl.

[0105] For example, the inorganic divalent cation includes: Pb 2+ Sn 2+ Be 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Zn 2+ 、Ge 2+ Fe 2+ Co 2+ Ni 2+ Cd 2+ Cu 2+ Mn 2+ Pd 2+ Yb 2+ Or Eu 2+ At least one of them.

[0106] For example, inorganic trivalent cations include: Bi 3+ Sb 3+ Cr 3+ Fe 3+ Co3+ Ga 3+ As 3+ Ru 3+ ,Rh 3+ In 3+ Ir 3+ Au 3+ Or Al 3+ At least one of them.

[0107] For example, monovalent anions include F - Cl - ,Br - I - SCN - CNO - OCN - OSCN - SH - OH - CN - SeCN - One or more of them.

[0108] In some embodiments, A includes CH3NH3 + CH(NH2)2 + Li + Na + K + 、Rb + Cs + One or more of the following; B includes Pb 2+ and / or Sn 2+ C includes Li + Na + K + 、Rb + Cs + One or more; X includes F - Cl - ,Br - I - SCN - CNO - OCN - OSCN - SH - OH - CN - SeCN - One or more of them.

[0109] In some embodiments, the perovskite light-absorbing layer includes Cs 0.1 FA 0.9One or more of PbI3, MAPbI3, FAPbI3, CsPbI3, etc., where MA is a methylamino group (CH3NH3). + ), FA is formamidinyl (HC(NH2)2) + ).

[0110] In some embodiments, the thickness of the perovskite light-absorbing layer is 300 nm to 1000 nm, and optionally, it is 400 nm to 600 nm.

[0111] In some embodiments, the solar cell further includes an electron transport layer located between the perovskite light-absorbing layer and the second electrode.

[0112] This application does not specifically limit the electron transport material used in the electron transport layer; commonly used electron transport materials in the art can be used. For example, electron transport materials include at least one of imide compounds, quinone compounds, fullerenes and their derivatives, metal oxides, semiconductor oxides, titanates, fluorides and their derivatives, and materials obtained by doping or passivation. Exemplarily, imide compounds include at least one of phthalimide, succinimide, N-bromosuccinimide, glutarimide, or maleimide. Exemplarily, quinone compounds include at least one of benzoquinone, naphthoquinone, phenanthrenequinone, or anthraquinone. Exemplarily, fullerenes and their derivatives include fullerene C 60 Fullerene C 70 PCBM([6,6]-phenyl-C 61 methyl butyrate), [6,6]-phenyl C 71 Methyl butyrate (PC) 71 At least one of BM. Exemplarily, the metal element in the metal oxide includes at least one of Mg, Cd, Zn, In, Pb, W, Sb, Bi, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, and Cr; optionally, the metal oxide includes at least one of tin oxide (SnO2) and zinc oxide (ZnO). Exemplarily, the semiconductor material oxide includes silicon oxide. Exemplarily, the titanate includes at least one of strontium titanate and calcium titanate. Exemplarily, the fluoride includes at least one of lithium fluoride and calcium fluoride.

[0113] In some embodiments, another hole transport layer may be disposed between the stacked hole transport layer and the perovskite light-absorbing layer to further improve the extraction and transport of hole carriers, and to block the contact between the stacked hole transport layer and the perovskite light-absorbing layer, thereby reducing NiO. x The reaction with perovskite materials improves the photoelectric conversion efficiency and stability of solar cells.

[0114] In this application, other hole transport layer materials may be one or more of the following: carbazole-based monomers or polymers, triphenylamine-based monomers or polymers, aromatic monomers or polymers, 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS), poly3-hexylthiophene (P3HT), triphenylamine with a triphenylene core, 3,4-ethylenedioxythiophene-methoxytriphenylamine ((PEDOT-OMeTPA)), N-(4-aniline)carbazole-spirobifluorene, polythiophene, etc.

[0115] In some embodiments, the solar cell further includes a substrate disposed on the side of the first electrode away from the perovskite light-absorbing layer, the substrate serving to support the solar cell. The substrate may be, but is not limited to, a glass substrate or a flexible substrate. In some embodiments, the material of the flexible substrate layer may be, for example (but not limited to), an organic polymer material, and further, may be a mixture of one or more of the following materials in different proportions: including but not limited to polyvinyl alcohol (PVA), polyester (PET), polyimide (PI), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), etc.

[0116] In some embodiments, the solar cell may further include a hole-blocking layer disposed between the electron transport layer and the second electrode. The hole-blocking layer improves both electron extraction and hole blocking performance.

[0117] In some embodiments, the hole-blocking layer includes a hole-blocking material. This application does not impose any particular limitation on the hole-blocking material; exemplaryly, the hole-blocking material may include one or more of SnO2 and copper bath (BCP, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline).

[0118] This application does not impose any particular limitation on the thickness of the hole blocking layer; a thickness commonly used in the art for hole blocking layers may be adopted. For example, the thickness of the hole blocking layer is 1 nm to 40 nm. Optionally, the thickness of the hole blocking layer is 20 nm.

[0119] In some embodiments, the solar cell further includes a passivation layer disposed on at least one surface of the perovskite light-absorbing layer, which helps to reduce defects at the interface and further improve the performance of the solar cell.

[0120] In some embodiments, the passivation layer may include passivating agents conventionally used in the art for passivating perovskite light-absorbing layers, such as small organic molecules, organic salts, inorganic salts, polymers, etc. Small organic molecule passivating agents include, but are not limited to, phenylethylamine, ethylenediamine, pyridine, butanethiol, 2,5-thiophene dicarboxylic acid, etc. Organic salt passivating materials include, but are not limited to, piperazine iodine, phenylethylamine hydroiodate, dodecyl hydroiodate, guanidine bromide, thiophene ethylamine hydroiodate, ethylenediamine hydroiodate, and oleylamine iodine. Inorganic salt passivating materials include, but are not limited to, zinc chloride, potassium chloride, and gallium chloride. Polymer passivating materials include, but are not limited to, polymethyl methacrylate, polyethylene oxide, polyacrylonitrile, and polyvinyl alcohol.

[0121] Methods for preparing solar cells

[0122] A second aspect of this application provides a method for fabricating a solar cell, used to fabricate the solar cell described in the first aspect above. The method includes: fabricating a first electrode, a stacked hole transport layer, a perovskite light-absorbing layer, and a second electrode arranged along a first direction, wherein the stacked hole transport layer and the perovskite light-absorbing layer are stacked between the first electrode and the second electrode, and the stacked hole transport layer is disposed on the side of the perovskite light-absorbing layer away from the second electrode; wherein the method for fabricating the stacked hole transport layer includes: depositing two layers of NiO on the first electrode. x A first hole transport layer and a second hole transport layer are formed, wherein 1 < x < 2. The first hole transport layer and the second hole transport layer are located between the first electrode and the perovskite light-absorbing layer. The second hole transport layer is disposed on the side of the first hole transport layer away from the first electrode, and the refractive index of the second hole transport layer is greater than that of the first hole transport layer.

[0123] In this application, a solar cell comprising a first hole transport layer and a second hole transport layer can be formed using the above method. Since the refractive index of the second hole transport layer is greater than that of the first hole transport layer, the density of the second hole transport layer is higher than that of the first hole transport layer. Therefore, the higher density of the second hole transport layer can block the escape of oxygen atoms from the first hole transport layer, which is beneficial to improving the overall carrier transport capacity and stability of the stacked hole transport layer.

[0124] This application does not specifically limit the preparation method of other functional layers of solar cells, and may include preparation methods commonly used in the art, such as chemical bath deposition, electrochemical deposition, chemical vapor deposition, physical epitaxial growth, thermal evaporation co-evaporation, atomic layer deposition, magnetron sputtering, precursor liquid spin coating, precursor liquid slot coating, precursor liquid scraping, mechanical pressing, but is not limited thereto.

[0125] In some implementations, the Ni content in the second hole transport layer is determined based on the total molar content of Ni in the second hole transport layer. 3+The molar content of the second hole transport layer is 0.1% to 10%; and / or the refractive index of the second hole transport layer is greater than or equal to 2.1, optionally, the refractive index of the second hole transport layer is 2.2 to 3.0; and / or the thickness of the second hole transport layer is 0.5 nm to 10 nm, optionally, 3 nm to 5 nm.

[0126] In some embodiments, the second hole transport layer can be formed by atomic layer deposition (ALD). ALD is a method in which a precursor is alternately pulsed into a reactor and chemically adsorbed and reacted on a substrate to form a deposited film. In this application, a nickel source and an oxygen source are alternately pulsed into the reactor for ALD, and an inert gas is introduced between the nickel and oxygen sources to purge the reaction chamber. The nickel source can be one or more of bis(cyclopentadienyl)nickel, diketoacetic acid diamine nickel, bis(acetylacetone)nickel, trimethylvinyl nickel, and tetramethylcyclopentadienyl nickel; the oxygen source can be one or more of water, ozone, and hydrogen peroxide; and the inert gas can be one or more of nitrogen and argon. Specifically, in this application, the second hole transport layer can be formed by controlling parameters such as the nickel source exposure time to 0.1 s to 10 s, the oxygen source exposure time to 0.01 s to 1 s, the number of cycles to 5 to 100, and the deposition temperature to 150°C to 250°C. Among them, with a fixed nickel source exposure time, the longer the oxygen source exposure time, the higher the content of trivalent nickel obtained; the more cycles, the greater the thickness of the second hole transport layer obtained; and the higher the deposition temperature, the greater the refractive index of the second hole transport layer obtained.

[0127] In some implementations, the Ni content in the first hole transport layer is determined based on the total molar content of Ni in the first hole transport layer. 3+ The molar content is 60% to 80%, optionally 70% to 75%; and / or, the refractive index of the first hole transport layer is less than 2.1, optionally 1.0 to 2.0; and / or, the thickness of the first hole transport layer is 10 nm to 50 nm, optionally 10 nm to 30 nm.

[0128] In some embodiments, the first hole transport layer can be formed by magnetron sputtering. Magnetron sputtering is a method of forming a deposited film by introducing a magnetic field onto the surface of a cathode target, using the magnetic field to confine charged particles and increase the plasma density. In this application, the target can be a doped or undoped nickel oxide target. Specifically, in this application, the substrate temperature can be controlled at 100°C to 200°C, the sputtering power at 1000W to 2000W, the annealing temperature at 100°C to 400°C, the working gas at a mixture of oxygen and argon, wherein the volume percentage of oxygen in the mixture is 1% to 10%, the stage travel speed at 0.1m / min to 1m / min, and the working pressure at 1×10. -4The first hole transport layer is formed using parameters such as Pa to 0.1 Pa and magnetron sputtering time of 5 min to 25 min. The higher the volume percentage of oxygen in the gas mixture, the higher the content of trivalent nickel in the first hole transport layer. With a constant stage speed, a longer sputtering time results in a thicker first hole transport layer. Higher substrate temperature, higher sputtering power, and higher annealing temperature all contribute to a higher refractive index in the first hole transport layer.

[0129] In some embodiments, the method for preparing the stacked hole transport layer further includes: depositing at least one layer of nickel oxide between the first hole transport layer and the second hole transport layer to form a third hole transport layer; the refractive index of the third hole transport layer is greater than or equal to the refractive index of the first hole transport layer.

[0130] In some embodiments, the third hole transport layer can be formed by atomic layer deposition. The specific formation process is similar to that of the second hole transport layer, except that the oxygen source exposure time is 0.1s to 2s, the deposition temperature is 80℃ to 200℃, and the number of cycles is 5 to 70.

[0131] photovoltaic modules

[0132] A third aspect of this application provides a photovoltaic module, including the solar cell described in the first aspect, or including a solar cell prepared according to the preparation method described in the second aspect. In some embodiments, the photovoltaic module further includes solder strips connecting the solar cells, a junction box for current transmission, and a cell encapsulation component.

[0133] In some embodiments, the battery encapsulation component includes photovoltaic glass. The photovoltaic glass covers the aforementioned solar cell module, serving to protect the solar cells. Simultaneously, the photovoltaic glass possesses excellent light transmittance and high hardness, allowing it to withstand large diurnal temperature variations and harsh weather conditions.

[0134] In some embodiments, the battery encapsulation component includes an ethylene-vinyl acetate copolymer (EVA) film disposed between the photovoltaic glass and the solar cell for bonding the photovoltaic glass and the solar cell.

[0135] In some implementations, the battery encapsulation components include a photovoltaic backsheet. The photovoltaic backsheet serves to protect the solar cell module.

[0136] Optionally, the photovoltaic backsheet material may include a polyvinyl fluoride composite film or a thermoplastic elastic material. The photovoltaic backsheet material possesses properties such as insulation, water resistance, and aging resistance.

[0137] In some implementations, the battery encapsulation component includes a solar aluminum frame, made of aluminum alloy, which features high strength and corrosion resistance. It serves to support and protect the solar cells.

[0138] Power generation unit

[0139] A fourth aspect of the present application provides a power generation device, including the solar cell described in the first aspect above, or including a solar cell prepared according to the preparation method described in the second aspect above.

[0140] Electrical appliances

[0141] A fifth aspect of the embodiments of this application also provides an electrical device, including the solar cell described in the first aspect above, or including a solar cell prepared according to the preparation method described in the second aspect above.

[0142] In some implementations, the electrical appliances include lighting equipment, energy storage equipment, etc., but are not limited to these. For example, electrical appliances include solar water heaters, solar streetlights, solar photovoltaic generators, etc.

[0143] Example

[0144] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0145] Example 1

[0146] Fabrication of solar cells

[0147] Step S1, Preparation of the first electrode: A 2cm*2cm fluorine-doped tin oxide (FTO, 600nm thick) conductive glass block is sequentially cleaned with acetone, isopropanol, and deionized water and then dried. The cleaned conductive glass block is used as the first electrode.

[0148] Step S2, fabrication of the first hole transport layer: Nickel oxide is deposited on the surface of the first electrode using magnetron sputtering as the first hole transport layer, with a thickness of 20 nm; wherein the magnetron sputtering method is performed at a sputtering power of 1800 W, a substrate temperature of 180 °C, an annealing temperature of 350 °C, a working gas mixture of oxygen and argon with oxygen accounting for 3% of the volume in the mixture, a stage speed of 0.4 m / min, a magnetron sputtering time of 10 min, and a working gas pressure of 4 × 10. -4 Under the condition of Pa;

[0149] Step S3, Preparation of the second hole transport layer: Nickel oxide is deposited on the surface of the first hole transport layer using atomic layer deposition (ALD) as the second hole transport layer, with a thickness of 5 nm. During ALD, the nickel source is bis(cyclopentadiene)nickel, the oxygen source is hydrogen peroxide, the nickel source exposure time is 1 s, the oxygen source exposure time is 0.5 s, the working gas is nitrogen, the deposition temperature is 200 °C, the purging time is 15 s, and the cycle count is 50. The first and second hole transport layers constitute a stacked hole transport layer.

[0150] Step S4, prepare the perovskite light-absorbing layer: Cs is coated on the surface of the second hole transport layer using the slit coating method. 0.1 FA 0.9 A PbI3 precursor solution was used to form a perovskite wet film. Then, the perovskite wet film was annealed at 140℃ for 5 min to obtain the perovskite light-absorbing layer Cs. 0.1 FA 0.9 PbI3, the thickness of the perovskite light-absorbing layer is 550 nm;

[0151] Step S5, Fabrication of the electron transport layer: Place the device obtained in step 4 into a vacuum thermal evaporation apparatus and evacuate to a vacuum level of 1 x 10. -4 Pa, and then 30 nm C layers were deposited on the perovskite light-absorbing layer. 60 It forms an electron transport layer and a hole blocking layer with 6nm copper bath (BCP);

[0152] Step S6, Fabrication of the second electrode: Place the device obtained in step 5 into a vacuum thermal evaporation equipment and evacuate to a vacuum level of 1 x 10. -4 Pa, with heat-sinking copper as the second electrode, the thickness of the second electrode being 100 nm.

[0153] Performance characterization of stacked hole transport layers

[0154] (1) Refractive index and thickness test

[0155] The layers above the second hole transport layer in the solar cell were removed using cured adhesive. The refractive indices of the first and second hole transport layers were then measured using an ellipsometer. First, the refractive index N of the stacked hole transport layer was obtained using an ellipsometer. t and the thickness D of the stacked hole transport layer tSpecifically, the incident light wavelength is 300nm–800nm, and the incident angle is 70°. The incident light is adjusted to be linearly polarized using a polarizer. A point is taken every 10nm within the wavelength range. Then, an ellipsometer is used to capture and record the amplitude ratio and phase difference of the reflected light at each point. The theoretically calculated amplitude ratio and phase difference are then fitted with the actually measured amplitude ratio and phase difference using ellipsometer software. Model parameters such as the surface roughness of the stacked hole transport layer are adjusted to minimize the deviation between the theoretical and experimental values ​​(i.e., satisfying a goodness-of-fit (GOF) ≥ 0.95). Finally, the refractive index N of the stacked hole transport layer is obtained. t and the thickness D of the stacked hole transport layer t Secondly, the second hole transport layer is removed using plasma etching technology (see above for the specific removal process). Then, the first hole transport layer is subjected to ellipsometric measurement in the manner described above to obtain the refractive index N1 and the thickness D1 of the first hole transport layer. Finally, the refractive index N2 and the thickness D2 of the second hole transport layer can be calculated according to the above formulas (2) and (3).

[0156] The test results above show that the refractive index N1 of the first hole transport layer in Example 1 is 2.0, and the refractive index N2 of the second hole transport layer is 2.2. The thickness D1 of the first hole transport layer in Example 1 is 20 nm, and the thickness D2 of the second hole transport layer is 5 nm.

[0157] (2)Ni 3+ Content testing

[0158] Methods: The layers above the second hole transport layer in the solar cell were removed using a curing adhesive. X-ray photoelectron spectroscopy (XPS) was used to test the exposed NiOx hole transport layer. Specifically, the surface of the second hole transport layer was first tested using a monochromatic Al Kα X-ray source (energy 1486.6 eV). The XPS analysis area was set to 30 μm to ensure representative coverage of the thin film. The wide scan range was 0–1200 eV, the energy resolution was 0.5–1.0 eV, and the XPS testing depth was 1 nm. Characteristic peaks of all elements on the surface of the second hole transport layer were recorded. The characteristic peak of nickel (Ni 2p orbital, binding energy approximately 850 eV–880 eV) was identified in the full spectrum. 3 / 2 and Ni 2p 1 / 2 Peak fitting was performed to separate different chemical states (Ni). 2+ Ni 3+ The peak position of Ni is obtained by integrating the area of ​​the core energy level peak. 3+ The area ratio of the characteristic peaks is the surface Ni of the second hole transport layer. 3+Content percentage. Subsequently, the surface of the second hole transport layer, which had already undergone XPS, was etched using an argon ion beam to expose the surface that had not been tested by XPS. XPS testing was then performed again, followed by another etching. After each etching, an XPS scan was performed using the same method to record the elemental composition and chemical state at the current depth. Through repeated etching and measurement, a distribution curve of nickel as a function of depth was constructed.

[0159] Figure 4 It is the distribution curve of nickel with depth, from Figure 4 It can be seen that trivalent nickel is uniformly distributed in both the first and second hole transport layers. Test results show that the Ni in the first hole transport layer in Example 1... 3+ The content is 72.0%, Ni in the second hole transport layer 3+ The content is 5.1%. It should be noted that the XPS depth profiling step size is set to 2.5 nm, therefore... Figure 4 The variation in trivalent nickel content at depths of 5nm to 7.5nm is caused by testing factors and can be ignored.

[0160] Solar cell module performance testing

[0161] (1) Photoelectric conversion efficiency (PCE) test

[0162] The photoelectric conversion efficiency was determined using the IV measurement method, and the specific steps are as follows:

[0163] a) Place the test fixture containing the sample cell (i.e. the solar cell prepared in Example 1 above) on the sample holder, so that it is located in the measurement plane, and ensure that the sample cell is located at the center of the emitted light spot of the solar simulator (or the normal of the photovoltaic cell is parallel to the center line of the emitted beam of the solar simulator light source).

[0164] b) The solar simulator from Guangyan was used for testing in accordance with the national standard IEC61215. Specifically, crystalline silicon solar cells were used to correct the light intensity to achieve a solar intensity of AM 1.5, at 100 mW / cm². 2 Under irradiance conditions, a mask is installed on the sample battery to be tested, and the temperature of the sample battery is controlled by a temperature monitoring device so that the temperature of the sample battery is maintained at (30±5℃) during the measurement process.

[0165] c) Set the scan direction, voltage range, scan interval voltage, and scan interval time. Specifically, the scan interval is 10mV, and the interval between two adjacent points is 100ms. Measure the forward and reverse scan current-voltage characteristics of the battery sample and record the short-circuit current J. sc Open circuit voltage V oc Maximum optical output current Jmpp and maximum light output voltage V mpp .

[0166] Next, the photoelectric conversion efficiency is calculated using the following formula:

[0167] Photoelectric conversion efficiency PCE = J sc ×V oc ×FF / Pw;

[0168] Fill factor FF = J sc ×V oc / (J mpp ×V mpp );

[0169] Among them, P w FF is the input power, and FF is the fill factor.

[0170] (2) Stability test

[0171] Photothermal accelerated aging test: Under conditions of 1 sun (one solar intensity) and 95°C, the photoelectric conversion efficiency retention rate of the solar cell prepared in Example 1 was tested after cycling at maximum power voltage for 500 hours.

[0172] Examples 2 to 10

[0173] The solar cell module was prepared using the same method as in Example 1, except that the performance of the first hole transport layer and the second hole transport layer in the solar cell module was adjusted according to Table 1 below:

[0174] In Example 2, the oxygen source exposure time in the atomic layer deposition method in S3 was adjusted to 1 second, so that the Ni in the prepared second hole transport layer... 3+ The molar content is 9.8%;

[0175] In Example 3, the oxygen source exposure time in the atomic layer deposition process of step S3 was adjusted to 0.01 s, so that the Ni in the prepared second hole transport layer... 3+ The molar content is 0.1%;

[0176] In Example 4, the volume percentage of oxygen in the mixed gas during magnetron sputtering in step S2 was adjusted to 2%, so that the Ni in the prepared first hole transport layer... 3+ The molar content is 60.4%; and the oxygen source exposure time in the atomic layer deposition method in step S3 is adjusted to 6s, so that the Ni content in the prepared second hole transport layer is 60.4%. 3+ The molar content is 59.6%;

[0177] In Example 5, the sputtering time in the magnetron sputtering method in step S2 was adjusted to 5 min, so that the thickness of the first hole transport layer was 10 nm; the number of cycles in the atomic layer deposition method in step S3 was adjusted to 10, so that the thickness of the second hole transport layer was 1 nm.

[0178] In Example 6, the number of cycles in the atomic layer deposition method in S3 was adjusted to 100, so that the thickness of the prepared second hole transport layer was 10 nm.

[0179] In Example 7, the sputtering time in the magnetron sputtering method in step S2 was adjusted to 25 min, so that the thickness of the prepared first hole transport layer was 50 nm.

[0180] In Example 8, the number of cycles in the atomic layer deposition method in step S3 was adjusted to 200, so that the thickness of the prepared second hole transport layer was 20 nm.

[0181] In Example 9, the substrate temperature in the magnetron sputtering method in step S2 was adjusted to 100°C, the sputtering power to 1000W, and annealing was not performed, so that the refractive index of the prepared first hole transport layer was 1.0; and the deposition temperature in the atomic layer deposition method in step S3 was adjusted to 250°C, so that the refractive index of the prepared second hole transport layer was 3.0.

[0182] In Example 10, the volume percentage of oxygen in the mixed gas during magnetron sputtering in step S2 was adjusted to 4%, so that the Ni in the prepared first hole transport layer... 3+ The molar content is 79.8%, please refer to Table 1 for details.

[0183] Comparative Example 1

[0184] The solar cell module was prepared using the same method as in Example 1, except that step 3 was omitted and a perovskite light-absorbing layer was formed directly on the first hole transport layer.

[0185] Comparative Example 2

[0186] The solar cell module was prepared using the same method as in Example 1, except that the deposition temperature in the atomic layer deposition method in step S3 was adjusted to 100°C, so that the refractive index of the prepared second hole transport layer was 1.95. Please refer to Table 1 for details.

[0187] The solar cells prepared in Examples 2 to 10 and Comparative Examples 1 and 2 were tested using the same test method as in Example 1, and the results are shown in Table 2.

[0188] Table 1 below shows the relevant performance parameters of the solar cells in Examples 1 to 10 and Comparative Examples 1 and 2, and Table 2 below shows the performance test results of the solar cells in Examples 1 to 10 and Comparative Examples 1 and 2.

[0189] Table 1

[0190]

[0191] Table 2

[0192]

[0193]

[0194] As can be seen from Tables 1 and 2, compared to Comparative Example 1 (without a second hole transport layer) and Comparative Example 2 (where the refractive index of the second hole transport layer is lower than that of the first hole transport layer), Examples 1 to 10 significantly improve the photoelectric conversion efficiency and stability of the solar cells by incorporating a second hole transport layer with a refractive index greater than that of the first hole transport layer. Furthermore, in Example 4, the high trivalent nickel content in the second hole transport layer makes it prone to reacting with the active material in the perovskite light-absorbing layer at the interface, thus affecting the photoelectric conversion efficiency and stability of the solar cell. In Example 9, the lower refractive index of the first hole transport layer results in slightly lower stability compared to Example 1, leading to a slight decrease in the photoelectric conversion efficiency and stability of the solar cell.

[0195] Example 11

[0196] The solar cell module was prepared using the same method as in Example 1, except that after step S2, nickel oxide was deposited on the surface of the first hole transport layer using atomic layer deposition to form a third hole transport layer, and then a second hole transport layer was formed on the surface of the third hole transport layer according to the method in step S3; the first hole transport layer, the third hole transport layer and the second hole transport layer constitute a stacked hole transport layer.

[0197] Specifically, the nickel source used in the formation of the third hole transport layer is bis(cyclopentadiene) nickel, the oxygen source is hydrogen peroxide, the nickel source exposure time is 1s, the oxygen source exposure time is 0.8s, the working gas is nitrogen, the deposition temperature is 190℃, the purging time is 15s, and the number of cycles is 50. The specific parameters of the formed third hole transport layer are shown in Table 3 below.

[0198] Example 12

[0199] The solar cell module was prepared using the same method as in Example 11, except that the number of cycles in the formation of the third hole transport layer was adjusted to 70, so that the thickness of the prepared third hole transport layer was 7 nm. Then, the number of cycles in the atomic layer deposition method in step S3 was adjusted to 30, so that the thickness of the prepared second hole transport layer was 3 nm. Please refer to Table 3 below for details.

[0200] The solar cells prepared in Examples 11 and 12 were tested using the same test method as in Example 1, and the results are shown in Table 4.

[0201] Table 3 below shows the relevant performance parameters of the solar cells in Examples 11 and 12. Table 4 below shows the performance test results of the solar cells in Examples 11 and 12. For ease of comparison, the results of Example 1 are also shown here.

[0202] Table 3

[0203]

[0204] Table 4

[0205]

[0206] As can be seen from Tables 3 and 4, by setting a third hole transport layer between the first and second hole transport layers, the photoelectric conversion efficiency and stability of the solar cell can be further improved. In Example 12, compared to Example 11, the stability of the solar cell is slightly reduced because the thickness of the second hole transport layer is smaller.

[0207] Example 13

[0208] The solar cell module was prepared using the same method as in Example 1, except that after step S2, two layers of nickel oxide were deposited on the surface of the first hole transport layer using atomic layer deposition to form the first third hole transport layer and the second third hole transport layer, respectively. Then, the second hole transport layer was formed on the surface of the second third hole transport layer according to the method in step S3. The first hole transport layer, the first third hole transport layer, the second third hole transport layer, and the second hole transport layer constitute a stacked hole transport layer.

[0209] Specifically, the nickel source used in the formation of the first and third hole transport layers is bis(cyclopentadiene) nickel, the oxygen source is hydrogen peroxide, the nickel source exposure time is 1s, the oxygen source exposure time is 1.5s, the working gas is nitrogen, the deposition temperature is 190℃, the purging time is 15s, and the number of cycles is 40. The specific parameters of the formed first and third hole transport layers are shown in Table 5 below.

[0210] The nickel source used in the formation of the second and third hole transport layers is bis(cyclopentadiene) nickel, the oxygen source is hydrogen peroxide, the nickel source exposure time is 1s, the oxygen source exposure time is 1s, the working gas is nitrogen, the deposition temperature is 190℃, the purging time is 15s, and the number of cycles is 30. The specific parameters of the formed second and third hole transport layers are shown in Table 6 below.

[0211] Then, the number of cycles in the atomic layer deposition method in step S3 is adjusted to 30, so that the thickness of the prepared second hole transport layer is 3nm, as shown in Table 6 below.

[0212] Example 14

[0213] The solar cell module was prepared using the same method as in Example 13, except that the number of cycles in the formation process of the first third hole transport layer was adjusted to 50, resulting in a thickness of 5 nm for the prepared first third hole transport layer. Furthermore, the oxygen source exposure time during the formation process of the first third hole transport layer was adjusted to 2 s, resulting in a higher Ni content in the prepared first third hole transport layer. 3+ The molar content was 19.8%; the oxygen source exposure time during the formation of the second and third hole transport layers was adjusted to 1.5 s, and the number of cycles was 40, so that the Ni content in the prepared second and third hole transport layers was optimal. 3+ The molar content is 15.4% and the thickness is 4 nm. The number of cycles in the atomic layer deposition method in step S3 is adjusted to 10, so that the thickness of the prepared second hole transport layer is 1 nm. Please refer to Tables 5 and 6 below for details.

[0214] The solar cells prepared in Examples 13 and 14 were tested using the same test method as in Example 1, and the results are shown in Table 7.

[0215] Tables 5 and 6 below show the relevant performance parameters of the solar cells in Examples 13 and 14. Table 7 below shows the performance test results of the solar cells in Examples 13 and 14. For ease of comparison, the results of Examples 1 and 11 are also shown here.

[0216] Table 5

[0217]

[0218] Table 6

[0219]

[0220] Table 7

[0221]

[0222] As shown in Tables 5-7, Examples 13 and 14, by incorporating two third hole transport layers, improve the photoelectric conversion efficiency and stability of the solar cells compared to Example 1, which does not have a third hole transport layer. Compared to Example 11, Examples 13 and 14, by introducing an additional third hole transport layer with slightly higher carrier transport capability, improve the photoelectric conversion efficiency of the solar cells. However, this sacrifices the thickness of the second hole transport layer to some extent, resulting in a slight decrease in the stability of the solar cells. In Example 14, the thickness of the second hole transport layer is reduced compared to Example 13, thus the stability of the solar cells is slightly reduced.

[0223] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A solar cell, characterized in that, The device includes a first electrode arranged along a first direction, a stacked hole transport layer, a perovskite light-absorbing layer, and a second electrode. The stacked hole transport layer and the perovskite light-absorbing layer are stacked between the first electrode and the second electrode, and the stacked hole transport layer is disposed on the side of the perovskite light-absorbing layer away from the second electrode. The stacked hole transport layer includes a first hole transport layer and a second hole transport layer, wherein the second hole transport layer is located between the first hole transport layer and the perovskite light-absorbing layer, and both the first hole transport layer and the second hole transport layer comprise NiO. x , 1 < x < 2; The refractive index of the second hole transport layer is greater than that of the first hole transport layer.

2. The solar cell according to claim 1, characterized in that, The refractive index of the second hole transport layer is greater than or equal to 2.1; and / or the refractive index of the first hole transport layer is less than 2.

1.

3. The solar cell according to claim 1 or 2, characterized in that, The refractive index of the second hole transport layer is 2.2 to 3.0; and / or the refractive index of the first hole transport layer is less than 1.0 to 2.

0.

4. The solar cell according to any one of claims 1 to 3, characterized in that, The thickness of the second hole transport layer is less than the thickness of the first hole transport layer.

5. The solar cell according to any one of claims 1 to 4, characterized in that, The thickness of the second hole transport layer is 0.5 nm to 10 nm.

6. The solar cell according to any one of claims 1 to 5, characterized in that, The thickness of the first hole transport layer is 10nm to 50nm.

7. The solar cell according to any one of claims 1 to 6, characterized in that, Based on the total molar content of Ni in the first hole transport layer, the Ni in the first hole transport layer 3+ The molar content of Ni is M1. Based on the total molar content of Ni in the second hole transport layer, the molar content of Ni in the second hole transport layer is... 3+ The molar content is M2, and M1 is greater than M2.

8. The solar cell according to any one of claims 1 to 7, characterized in that, Based on the total molar content of Ni in the second hole transport layer, the Ni in the second hole transport layer 3+ The molar content M2 is 0.1% to 10%.

9. The solar cell according to any one of claims 1 to 8, characterized in that, Based on the total molar content of Ni in the first hole transport layer, the Ni in the first hole transport layer 3+ The molar content M1 is 60%–80%.

10. The solar cell according to any one of claims 1 to 9, characterized in that, The stacked hole transport layer further includes at least one third hole transport layer; the third hole transport layer is located between the first hole transport layer and the second hole transport layer; The refractive index of the third hole transport layer is greater than that of the first hole transport layer.

11. The solar cell according to claim 10, characterized in that, The refractive index of the third hole transport layer is greater than or equal to 2.

1.

12. The solar cell according to claim 10 or 11, characterized in that, The third hole transport layer includes NiO. x , 1 < x < 2; Based on the total molar content of Ni in the second hole transport layer, the Ni in the second hole transport layer 3+ The molar content of Ni is M2. Based on the total molar content of Ni in the third hole transport layer, the molar content of Ni in the third hole transport layer is... 3+ The molar content is M3, and M3 is greater than M2.

13. The solar cell according to any one of claims 10 to 12, characterized in that, Based on the total molar content of Ni in the third hole transport layer, the Ni in the third hole transport layer 3+ The molar content of M3 is 1% to 20%.

14. The solar cell according to any one of claims 10 to 13, characterized in that, One or more of the following conditions must be met: (1) The thickness of the second hole transport layer is 0.5 nm to 3 nm; (2) The thickness of the third hole transport layer is 0.5 nm to 7 nm; (3) The combined thickness of the second hole transport layer and the third hole transport layer is 1 nm to 10 nm.

15. The solar cell according to any one of claims 10 to 14, characterized in that, The stacked hole transport layer includes multiple third hole transport layers, located close to the perovskite light-absorbing layer along the first direction. Based on the total molar content of Ni in each of the third hole transport layers, the Ni content in the third hole transport layer is... 3+ The molar content gradually decreases.

16. The solar cell according to any one of claims 10 to 15, characterized in that, The stacked hole transport layer includes multiple third hole transport layers that are close to the perovskite light-absorbing layer along the first direction, and the thickness of the third hole transport layer gradually decreases.

17. The solar cell according to any one of claims 10 to 16, characterized in that, The stacked hole transport layer includes two layers of the third hole transport layer.

18. The solar cell according to any one of claims 1 to 17, characterized in that, The thickness of the stacked hole transport layer is 10.5 nm to 60 nm.

19. The solar cell according to any one of claims 1 to 18, characterized in that, The perovskite light-absorbing layer includes a perovskite light-absorbing layer; the perovskite light-absorbing layer includes at least one of the compounds shown in [A][B][X]3 and [A]2[C][D][X]6. Wherein, A includes monovalent inorganic or organic cations, B includes divalent inorganic cations, C includes monovalent inorganic cations, D includes trivalent inorganic cations, and X includes monovalent anions.

20. The solar cell according to claim 19, characterized in that, A includes CH3NH3 + CH(NH2)2 + Li + Na + K + 、Rb + Cs + One or more of the following; B includes Pb 2+ and / or Sn 2+ C includes Li + Na + K + 、Rb + Cs + One or more; X includes F - Cl - ,Br - I - SCN - CNO - OCN - OSCN - SH - OH - CN - SeCN - One or more of them.

21. A method for preparing a solar cell, characterized in that, include: A first electrode, a stacked hole transport layer, a perovskite light-absorbing layer, and a second electrode are prepared and arranged along a first direction. The stacked hole transport layer and the perovskite light-absorbing layer are stacked between the first electrode and the second electrode, and the stacked hole transport layer is disposed on the side of the perovskite light-absorbing layer away from the second electrode. The method for preparing the stacked hole transport layer includes: depositing two NiO layers on the first electrode. x Layers, 1 < x < 2, form the first hole transport layer and the second hole transport layer; The second hole transport layer is disposed on the side of the first hole transport layer away from the first electrode; the refractive index of the second hole transport layer is greater than the refractive index of the first hole transport layer.

22. The preparation method according to claim 21, characterized in that, The first hole transport layer is formed by magnetron sputtering, and / or the second hole transport layer is formed by atomic layer deposition.

23. The preparation method according to claim 21 or 22, characterized in that, The method for preparing the stacked hole transport layer further includes: depositing at least one layer of NiO between the first hole transport layer and the second hole transport layer. x 1 < x < 2, forming at least one third hole transport layer; The refractive index of the third hole transport layer is greater than that of the first hole transport layer.

24. The preparation method according to claim 23, characterized in that, The third hole transport layer is prepared by atomic layer deposition.

25. A photovoltaic module, characterized in that, The photovoltaic module includes the solar cell according to any one of claims 1 to 20, or the solar cell prepared by the preparation method according to any one of claims 21 to 24.

26. A power generation device, characterized in that, The power generation device includes a solar cell according to any one of claims 1 to 20, or a solar cell prepared by the preparation method according to any one of claims 21 to 24.

27. An electrical appliance, characterized in that, The electrical device includes a solar cell according to any one of claims 1 to 20, or a solar cell prepared by the preparation method according to any one of claims 21 to 24.

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