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

Abstract

The invention discloses a solar cell and a preparation method thereof, a power utilization device and a power generation device, the solar cell comprises a first electrode layer, a functional layer and a second electrode layer which are stacked in sequence, the functional layer comprises a perovskite layer and an electron transport layer, the chemical formula of the perovskite layer is AB (IxBr1-x-mYm) 3, x is greater than 0 and less than 1, m is greater than or equal to 0 and less than or equal to 0.05, the A ions comprise inorganic or organic or organic-inorganic mixed monovalent cations, the B ions comprise inorganic divalent cations, the Y ions comprise inorganic or organic or organic-inorganic mixed monovalent anions, and the perovskite layer comprises a first region close to one side of the electron transport layer and a second region away from one side of the electron transport layer. X of the first region is smaller than x of the second region. According to the invention, the Br element content of one side, close to the electron transport layer, in the perovskite layer is regulated to be greater than the I element content, so that the surface of the perovskite layer close to one side of the electron transport layer generates compression stress, the migration barrier of iodine ions to the electrode layer is increased, and the stability of the solar cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and particularly to a solar cell, a preparation method thereof, a photovoltaic device, an electrical device, and a power generation device. Background Art

[0002] As a third-generation solar cell, a perovskite solar cell uses a perovskite material as a light-absorbing layer material, and has significant performance advantages such as a high light absorption coefficient, carrier mobility, a direct and adjustable optical bandgap, etc. However, for a halide perovskite solar cell, iodide ions in the perovskite layer are likely to migrate to the electrode layer and corrode the electrode, resulting in instability of the solar cell. Summary of the Invention

[0003] In view of the above technical problems, the present application provides a solar cell, a preparation method thereof, a photovoltaic device, an electrical device, and a power generation device to solve the problem of instability of the solar cell.

[0004] The first technical solution adopted by the present application is: to provide a solar cell, which includes a first electrode layer, a functional layer, and a second electrode layer that are sequentially stacked. The functional layer includes a perovskite layer and an electron transport layer. The chemical formula of the perovskite layer is AB(I x Br 1-x-m Y m )3, where 0 < x < 1 and 0 ≤ m ≤ 0.05. Here, A ions include inorganic, organic, or organic-inorganic hybrid monovalent cations, B ions include inorganic divalent cations, Y ions include inorganic, organic, or organic-inorganic hybrid monovalent anions. The perovskite layer includes a first region close to the electron transport layer and a second region far from the electron transport layer, and x in the first region is less than x in the second region.

[0005] In the technical solution of the embodiment of the present application, the functional layer in the solar cell includes a perovskite layer and an electron transport layer. The chemical formula of the perovskite layer is AB(I x Br 1-x-m Y m )3. The side of the perovskite layer close to the electron transport layer is the first region, and the side of the perovskite layer far from the electron transport layer is the second region. Among them, x in the first region is less than x in the second region, that is, the molar ratio of Br element in the first region to the total of Br element and I element is greater than the molar ratio of Br element in the second region to the total of Br element and I element. Since the radius of a bromine atom is smaller than that of an iodine atom, the unit cell of the perovskite close to the electron transport layer is small, and compressive stress is generated on the surface of the perovskite close to the electron transport layer, increasing the migration barrier for iodide ions to migrate to the electrode layer. Thereby, the risk of iodide ions migrating to the electrode layer corresponding to the electron transport layer is weakened, thus improving the stability of the solar cell.

[0006] In some implementations, x < 0.5 in the first region and x > 0.5 in the second region.

[0007] In the technical solution of this application embodiment, in the first region, x < 0.5, the molar ratio of Br element in Br element and I element is greater than the molar ratio of I element in Br element and I element, and the first region forms a bromine-rich region; in the second region, x > 0.5, the molar ratio of Br element in Br element and I element is less than the molar ratio of I element in Br element and I element, and the second region forms an iodine-rich region. Since the radius of bromine atom is smaller than the radius of iodine atom, compressive stress is generated on the surface of perovskite near the electron transport layer, which increases the migration barrier of iodine ions to the electrode layer, thereby weakening the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, thereby improving the stability of the solar cell.

[0008] In some implementations, x gradually decreases in the first and second regions along the direction from the perovskite layer toward the electron transport layer.

[0009] In the technical solution of this application embodiment, along the direction from the perovskite layer to the electron transport layer, x gradually decreases, the molar ratio of I element in Br element and I element gradually decreases, and the molar ratio of Br element in Br element and I element gradually increases. Since the radius of bromine atom is smaller than that of iodine atom, along the direction from the perovskite layer to the electron transport layer, the compressive stress generated in the perovskite layer gradually increases, and the migration barrier of iodine ions to the electrode layer also gradually increases. This more effectively weakens the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, thereby improving the stability of the solar cell.

[0010] In some implementations, at the interface of the perovskite layer near the electron transport layer, 0.35 ≤ x ≤ 0.45.

[0011] In the technical solution of this application embodiment, at the interface of the perovskite layer near the electron transport layer, when x is within the aforementioned range, not only can bromine reduce the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, but iodine can also improve the defects of the perovskite layer, thereby enhancing the stability of the solar cell. Furthermore, when x is within the aforementioned range, the resulting gradient bandgap not only increases the Fermi level and reduces energy level mismatch with the electron transport layer, but also provides an effective built-in electric field, improving carrier extraction efficiency and enhancing solar cell performance.

[0012] In some implementations, at the interface of the perovskite layer on the side away from the electron transport layer, 0.6 ≤ x < 1.

[0013] In the technical solution of this application embodiment, on the interface of the perovskite layer away from the electron transport layer, when x is within the above range, not only can bromine reduce the risk of iodine ions migrating to the electrode layer, but iodine can also improve the defects of the perovskite layer, thereby improving the stability of the solar cell.

[0014] In some embodiments, the thickness of the first region in the thickness direction of the perovskite layer is 10% to 50%.

[0015] In the technical solution of this application embodiment, the thickness of the first region is within the above-mentioned range, which not only reduces the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, but also improves the structural stability of the perovskite layer, thereby enhancing the stability of the solar cell.

[0016] In some embodiments, the thickness of the first region in the thickness direction of the perovskite layer is 10% to 20%.

[0017] In some embodiments, the second region accounts for 50% to 90% of the thickness in the thickness direction of the perovskite layer.

[0018] In the technical solution of this application embodiment, the thickness of the second region is within the above-mentioned range, which not only reduces the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, but also improves the structural stability of the perovskite layer, thereby enhancing the stability of the solar cell.

[0019] In some embodiments, the second region accounts for 50% to 60% of the thickness in the thickness direction of the perovskite layer.

[0020] In some embodiments, the perovskite layer further includes an intermediate region located between the first region and the second region, in which x = 0.5.

[0021] In the technical solution of this application embodiment, the perovskite layer also includes an intermediate region located between the first region and the second region. In the intermediate region, x = 0.5, the ratio of iodine ions to bromide ions is equal, so the intermediate region can act as an intermediate barrier layer to block the migration of halogens between the first region and the second region. The intermediate region can also control the changes in the chemical composition and band gap of the perovskite within a small range, thereby improving the structural stability of the perovskite layer and thus enhancing the stability of the solar cell.

[0022] In some implementations, the thickness of the intermediate region in the thickness direction of the perovskite layer is greater than 0 and less than or equal to 50%.

[0023] In the technical solution of this application embodiment, the thickness of the intermediate region is within the above-mentioned range, which not only blocks the halogen migration between the first region and the second region, but also controls the changes in the chemical composition and band gap of the perovskite within a small range, thereby improving the structural stability of the perovskite layer and thus enhancing the stability of the solar cell.

[0024] In some embodiments, the thickness of the first region in the thickness direction of the perovskite layer is 10% to 40%.

[0025] In the technical solution of this application embodiment, when there is an intermediate region, the thickness ratio of the first region is 10% to 40%. The thickness ratio is within the above range, which not only reduces the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, but also improves the structural stability of the perovskite layer, thereby improving the stability of the solar cell.

[0026] In some embodiments, the second region accounts for 40% to 60% of the thickness in the thickness direction of the perovskite layer.

[0027] In the technical solution of this application embodiment, when there is an intermediate region, the thickness of the second region accounts for 40% to 60%. The thickness is within the above range, which not only reduces the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, but also improves the structural stability of the perovskite layer, thereby improving the stability of the solar cell.

[0028] In some embodiments, the thickness of the perovskite layer is 400 nm to 1000 nm.

[0029] In some embodiments, the A ion includes MA + FA + GA + Cs + 、Rb + At least one of them; and / or, B ions include Pb 2+ Sn 2+ Ca 2+ 、Sr 2+ Cd 2+ Cu 2+ Ni 2+ Mn 2+、 Fe 2+ Co 2+ Pd 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of the following, Y ions include F - Cl - SCN - BF4 - PF6 -at least one of

[0030] The second technical solution adopted in this application is: to provide a method for preparing a solar cell for preparing the solar cell of any one of the above, including: providing a first electrode layer; providing a perovskite layer on the first electrode layer, and the chemical formula of the perovskite layer is AB(I x Br 1-x-m Y m )3, 0 < x < 1, 0 ≤ m ≤ 0.05, A ions include A' ions and / or A" ions, A' ions are inorganic monovalent cations, A" ions are organic monovalent cations, B ions include inorganic divalent cations, and Y ions include inorganic or organic or organic-inorganic mixed monovalent anions. Among them, including: using the evaporation method, the evaporation source at least includes BI2 and BBr2, and also includes evaporating or coating at least one of A'I and / or A"I to obtain the perovskite layer; wherein, the evaporation rate of BBr2 gradually increases relative to the evaporation rate of BI2 or first gradually increases, then remains constant, and then gradually increases; providing an electron transport layer on the perovskite layer; and providing a second electrode layer on the electron transport layer.

[0031] In the technical solution of the embodiment of this application, by using the above-provided preparation method to prepare the perovskite layer, the evaporation rates of each raw material can be controlled, and the precise control of the composition and constitution of the perovskite layer can be achieved. At the same time, according to the above-provided evaporation rate control method, the molar ratio of Br element on the side of the perovskite layer close to the electron transport layer in Br element and I element is greater than the molar ratio of Br element on the side of the perovskite layer far from the electron transport layer in Br element and I element. Since the radius of the bromine atom is smaller than the radius of the iodine atom, the unit cell of the perovskite on the side close to the electron transport layer is small, and compressive stress is generated on the surface of the perovskite on the side close to the electron transport layer, increasing the migration barrier of iodine ions migrating to the electrode layer, thereby weakening the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, and thus improving the stability of the solar cell.

[0032] In some embodiments, the evaporation rate S1 of A'I is The evaporation rate S2 of A"I is The evaporation rate S3 of BI2 is The evaporation rate S4 of BBr2 is The acceleration a of the evaporation rate S4 of BBr2 is

[0033] In the technical solution of the embodiment of the present application, through the above-provided control method, the molar ratio of Br element on the side of the perovskite layer close to the electron transport layer in Br element and I element is greater than that of Br element on the side far from the electron transport layer in Br element and I element. Since the radius of the bromine atom is smaller than that of the iodine atom, the unit cell of the perovskite on the side close to the electron transport layer is small, and compressive stress is generated on the surface of the perovskite on the side close to the electron transport layer, increasing the migration barrier of iodide ions migrating to the electrode layer. Thereby, the risk of iodide ions migrating to the electrode layer corresponding to the electron transport layer is weakened, thus improving the stability of the solar cell.

[0034] The third technical solution adopted in the present application is: providing a preparation method of a solar cell for preparing the solar cell of any one of the above, including: providing a first electrode layer; disposing an electron transport layer on the first electrode layer; disposing a perovskite layer on the electron transport layer, and the chemical formula of the perovskite layer is AB(I x Br 1-x-m Y m )3, 0 < x < 1, 0 ≤ m ≤ 0.05, A ions include A' ions and / or A" ions, A' ions are inorganic monovalent cations, A" ions are organic monovalent cations, B ions include inorganic divalent cations, and Y ions include inorganic or organic or organic-inorganic mixed monovalent anions. Among them, it includes: adopting the evaporation method, the evaporation source at least includes BI2 and BBr2, and also includes evaporating or coating at least one of A'I and / or A"I to obtain the perovskite layer; wherein, the evaporation rate of BBr2 gradually decreases relative to the evaporation rate of BI2 or first gradually decreases, then remains constant, and then gradually decreases; disposing a second electrode layer on the perovskite layer.

[0035] In the technical solution of the embodiment of the present application, the evaporation rates of each raw material can be controlled to achieve precise control of the composition and constitution of the perovskite layer. At the same time, according to the above-provided evaporation rate control method, the molar ratio of Br element on the side of the perovskite layer close to the electron transport layer in Br element and I element is greater than that of Br element on the side far from the electron transport layer in Br element and I element. Since the radius of the bromine atom is smaller than that of the iodine atom, the unit cell of the perovskite on the side close to the electron transport layer is small, and compressive stress is generated on the surface of the perovskite on the side close to the electron transport layer, increasing the migration barrier of iodide ions migrating to the electrode layer. Thereby, the risk of iodide ions migrating to the electrode layer corresponding to the electron transport layer is weakened, thus improving the stability of the solar cell.

[0036] In some embodiments, the evaporation rate S1 of A'I is The evaporation rate S2 of A"I is The evaporation rate S3 of BI2 is The evaporation rate S4 of BBr2 is The acceleration b of the BBr2 evaporation rate S4 is...

[0037] In the technical solution of this application embodiment, through the control method provided above, the molar ratio of Br element in Br element and I element on the side of the perovskite layer near the electron transport layer is greater than the molar ratio of Br element in Br element and I element on the side away from the electron transport layer. Since the radius of bromine atom is smaller than the radius of iodine atom, the perovskite cell on the side near the electron transport layer is smaller, and compressive stress is generated on the surface of the perovskite on the side near the electron transport layer, which increases the migration barrier of iodine ions to the electrode layer, thereby weakening the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, thereby improving the stability of the solar cell.

[0038] The fourth technical solution adopted in this application is: to provide a photovoltaic device, including the solar cell as described above or a method for preparing the solar cell as described above.

[0039] The fifth technical solution adopted in this application is: to provide an electrical device, including the solar cell as described above or a method for preparing the solar cell as described above.

[0040] Since the device of this application includes the solar cell provided in this application, it has at least the same advantages as the solar cell.

[0041] The sixth technical solution adopted in this application is: providing a solar cell including the solar cell described above or a method for preparing a solar cell including the solar cell described above.

[0042] Since the device of this application includes the solar cell provided in this application, it has at least the same advantages as the solar cell.

[0043] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0044] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0045] Figure 1 This is a schematic diagram of the structure of a solar cell according to an embodiment of this application;

[0046] Figure 2 This is a schematic diagram of the structure of a solar cell according to an embodiment of this application;

[0047] Figure 3 This is a schematic diagram of the structure of a solar cell according to an embodiment of this application;

[0048] Figure 4 This is a schematic diagram of the structure of a solar cell according to an embodiment of this application;

[0049] Figure 5 This is a schematic diagram of the structure of a photovoltaic device according to an embodiment of this application;

[0050] Figure 6 This is a schematic diagram of the structure of an electrical device according to an embodiment of this application;

[0051] Figure 7 This is a schematic diagram of the structure of a power generation device according to an embodiment of this application;

[0052] Figure 8 This is a schematic diagram of the vapor deposition rate according to an embodiment of this application;

[0053] Figure 9 This is a schematic diagram showing the distribution of bromine in a perovskite according to an embodiment of this application;

[0054] Figure 10 This is a schematic diagram showing the distribution of iodine in a perovskite according to an embodiment of this application;

[0055] Figure 11 This is an X-ray diffraction pattern of an embodiment of this application.

[0056] Marker explanation:

[0057] Solar cell 100, first electrode layer 101, functional layer 102, second electrode layer 103, perovskite layer 1021, electron transport layer 1022, hole transport layer 1023, first region A, second region B, intermediate region C, photovoltaic device 1000, power consumption device 2000, power generation device 3000. Detailed Implementation

[0058] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0060] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0061] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0062] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0063] In related technologies, halogenated hydrocarbons are used as the halogen source for ion exchange. However, the halogenated hydrocarbons have poor compatibility with the perovskite layer and electron transport layer, resulting in energy level mismatch and affecting electron transport efficiency. Furthermore, the commonly used ion exchange process is achieved through solution immersion, but perovskite has poor water and oxygen stability, and solution immersion will cause a decline in the quality of the perovskite film.

[0064] Reference Figure 1 The first technical solution adopted in this application is: to provide a solar cell 100, which includes a first electrode layer 101, a functional layer 102, and a second electrode layer 103 stacked sequentially. The functional layer 102 includes a perovskite layer 1021 and an electron transport layer 1022. The chemical formula of the perovskite layer 1021 is AB(I x Br 1-x-m Y m)3, 0 < x < 1, 0 ≤ m ≤ 0.05, where A ions include inorganic, organic, or organic-inorganic hybrid monovalent cations, B ions include inorganic divalent cations, Y ions include inorganic, organic, or organic-inorganic hybrid monovalent anions, and the perovskite layer 1021 includes a first region A closer to the electron transport layer 1022 and a second region B farther from the electron transport layer 1022, and the x of the first region A is less than the x of the second region B.

[0065] In the technical solution of the embodiment of the present application, the functional layer 102 in the solar cell 100 includes a perovskite layer 1021 and an electron transport layer 1022, and the chemical formula of the perovskite layer 1021 is AB(I x Br 1-x-m Y m )3. The side of the perovskite layer 1021 closer to the electron transport layer 1022 is the first region A, and the side of the perovskite layer 1021 farther from the electron transport layer 1022 is the second region B. Among them, the x of the first region A is less than the x of the second region B, that is, the molar ratio of the Br element in the first region A to the Br and I elements is greater than the molar ratio of the Br element in the second region B to the Br and I elements. Since the radius of the bromine atom is smaller than the radius of the iodine atom, the unit cell of the perovskite closer to the electron transport layer 1022 is small, and compressive stress is generated on the surface of the perovskite closer to the electron transport layer 1022, increasing the migration barrier for iodide ions to migrate to the second electrode layer 103. Thereby, the risk of iodide ions migrating to the second electrode layer 103 is weakened, thus improving the stability of the solar cell 100.

[0066] The solar cell 100 disclosed in the embodiment of the present application can be used in power-consuming devices or power-generating devices for photovoltaic conversion. The power-consuming devices can be, but are not limited to, mobile phones, tablets, laptop computers, electric toys, electric tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toys can include fixed or mobile electric toys, for example, game consoles, electric vehicle toys, electric ship toys, and electric plane toys, etc., and the spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc. The power-generating device can include the solar cell 100 and an energy storage device, and the energy storage device can be a secondary battery.

[0067] In some embodiments, in the first region A, x < 0.5, and in the second region B, x > 0.5.

[0068] In the technical solution of this application embodiment, in the first region A, x < 0.5, the molar ratio of Br element in Br element and I element is greater than the molar ratio of I element in Br element and I element, and the first region A forms a bromine-rich region; in the second region B, x > 0.5, the molar ratio of Br element in Br element and I element is less than the molar ratio of I element in Br element and I element, and the second region B forms an iodine-rich region. Since the radius of bromine atom is smaller than the radius of iodine atom, compressive stress is generated on the surface of perovskite near the electron transport layer 1022, which increases the migration barrier of iodine ions to the second electrode layer 103, thereby weakening the risk of iodine ions migrating to the second electrode layer 103 and improving the stability of solar cell 100.

[0069] It should be noted that the content of Y ions is low, between 0 ≤ m ≤ 0.05, and Y ions can be introduced through additives or doping.

[0070] In some embodiments, x gradually decreases in the first region A and the second region B along the direction from the perovskite layer 1021 toward the electron transport layer 1022.

[0071] In the technical solution of this application embodiment, along the direction from the perovskite layer 1021 toward the electron transport layer 1022, x gradually decreases, the molar ratio of I element in Br element and I element gradually decreases, and the molar ratio of Br element in Br element and I element gradually increases. Since the radius of bromine atom is smaller than that of iodine atom, along the direction from the perovskite layer 1021 toward the electron transport layer 1022, the compressive stress generated in the perovskite layer 1021 gradually increases, and the migration barrier of iodine ions to the electrode layer also gradually increases. This more effectively weakens the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer 1022, thereby improving the stability of the solar cell 100.

[0072] In some embodiments, "x gradually decreasing" means that the molar ratio of element I in Br and element I generally decreases in the direction of the perovskite layer 1021 toward the electron transport layer 1022. This decreasing trend can be linear, non-linear, or it can be a trend where the molar ratio of element I in Br and element I first decreases, then remains constant, and finally decreases again. No limitations are imposed here.

[0073] In some implementations, at the interface of the perovskite layer near the electron transport layer, 0.35 ≤ x ≤ 0.45.

[0074] In the technical solution of this application embodiment, at the interface of the perovskite layer near the electron transport layer, when x is within the aforementioned range, not only can bromine reduce the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer 1022, but iodine can also improve the defects of the perovskite layer 1021, thereby enhancing the stability of the solar cell 100. Furthermore, when x is within the aforementioned range, the resulting gradient bandgap not only increases the Fermi level and reduces the energy level mismatch with the electron transport layer 1022, but also provides an effective built-in electric field, improving carrier extraction efficiency and enhancing the performance of the solar cell 100. In the first region A, the value of x can be 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.42, 0.45, etc.

[0075] In some implementations, at the interface of the perovskite layer on the side away from the electron transport layer, 0.6 ≤ x < 1.

[0076] In the technical solution of this application embodiment, at the interface on the side of the perovskite layer away from the electron transport layer, when x is within the aforementioned range, not only can bromine reduce the risk of iodine ions migrating to the electrode layer, but iodine can also improve the defects of the perovskite layer 1021, thereby enhancing the stability of the solar cell 100. In the second region B, the value of x can be 0.6, 0.65, 0.70, 0.78, 0.85, 0.9, 0.95, 0.99, etc.

[0077] In some embodiments, the thickness of the first region A in the thickness direction of the perovskite layer 1021 is 10% to 50%.

[0078] In the technical solution of this application embodiment, the thickness of the first region A is within the above-mentioned range, which not only reduces the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer 1022, but also improves the structural stability of the perovskite layer 1021, thereby enhancing the stability of the solar cell 100. The thickness percentage of the first region A in the thickness direction of the perovskite layer 1021 can be 10%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 35%, 40%, 45%, 50%, or any range of two of the above values, such as 10%–18%, 18%–25%, 25%–30%, 20%–28%, 30%–50%, etc.

[0079] Preferably, the thickness of the first region A in the thickness direction of the perovskite layer is 10% to 20%.

[0080] In some embodiments, the second region B accounts for 50% to 90% of the thickness in the thickness direction of the perovskite layer 1021.

[0081] In the technical solution of this application embodiment, the thickness of the second region B is within the above-mentioned range, which not only reduces the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, but also improves the structural stability of the perovskite layer 1021, thereby enhancing the stability of the solar cell 100. The thickness percentage of the second region B in the thickness direction of the perovskite layer 1021 can be 50%, 52%, 55%, 58%, 60%, 65%, 78%, 85%, 90%, etc., or a range composed of any two of the above values, such as 50%~78%, 78%~90%, 55%~85%, etc.

[0082] Preferably, the thickness of the second region B in the thickness direction of the perovskite layer is 50% to 60%.

[0083] In some implementations, refer to Figure 4 The perovskite layer 1021 also includes an intermediate region C located between the first region A and the second region B, where x = 0.5.

[0084] In the technical solution of this application embodiment, the perovskite layer 1021 further includes an intermediate region C located between the first region A and the second region B. In the intermediate region C, x = 0.5, the ratio of iodine ions to bromide ions is roughly equal. Therefore, the intermediate region C can act as an intermediate barrier layer to block the migration of halogens between the first region A and the second region B. The intermediate region C can also control the changes in the chemical composition and band gap of the perovskite within a small range, thereby improving the structural stability of the perovskite layer 1021 and thus enhancing the stability of the solar cell 100.

[0085] In some embodiments, the thickness of the intermediate region C in the thickness direction of the perovskite layer 1021 is greater than 0 and less than or equal to 50%.

[0086] In the technical solution of this application embodiment, the thickness of the intermediate region C is within the aforementioned range. This not only blocks the halogen migration of the first region A and the second region B, but also controls the changes in the chemical composition and band gap of the perovskite within a small range, thereby improving the structural stability of the perovskite layer 1021 and thus enhancing the stability of the solar cell 100. The thickness percentage of the intermediate region C in the thickness direction of the perovskite layer 1021 can be 2%, 10%, 15%, 21%, 26%, 35%, 38%, 42%, 50%, etc., or a range composed of any two of the above values, such as 2%~10%, 10%~35%, 35%~42%, 42%~58%, 21%~38%, etc.

[0087] In some embodiments, the thickness of the first region in the thickness direction of the perovskite layer is 10% to 40%.

[0088] In the technical solution of this application embodiment, when there is an intermediate region, the thickness ratio of the first region is 10% to 40%. The thickness ratio is within the above range, which not only reduces the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, but also improves the structural stability of the perovskite layer, thereby improving the stability of the solar cell.

[0089] When an intermediate region exists, the thickness of the first region can be a percentage of 10%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 35%, or 40%, or a range of any two of the above values, such as 10%–18%, 18%–25%, 25%–30%, 20%–28%, or 30%–40%.

[0090] In some embodiments, the second region accounts for 40% to 60% of the thickness in the thickness direction of the perovskite layer.

[0091] In the technical solution of this application embodiment, when there is an intermediate region, the thickness of the second region accounts for 40% to 60%. The thickness is within the above range, which not only reduces the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer, but also improves the structural stability of the perovskite layer, thereby improving the stability of the solar cell.

[0092] When an intermediate region exists, the thickness percentage of the second region B in the thickness direction of the perovskite layer 1021 can be 40%, 45%, 48%, 52%, 55%, 58%, 60%, or any range of any two of the above values, such as 40% to 52%, 52% to 60%, 48% to 58%, etc.

[0093] In some embodiments, the thickness of the perovskite layer is 400 nm to 1000 nm. The thickness of the perovskite layer can be 400 nm, 460 nm, 500 nm, 530 nm, 660 nm, 780 nm, 800 nm, 980 nm, 1000 nm, etc., or a range of any two of the above values, such as 400 nm to 530 nm, 530 nm to 780 nm, 780 nm to 1000 nm, 460 nm to 660 nm, 500 nm to 800 nm, 660 nm to 980 nm, etc.

[0094] In some embodiments, the A ion includes MA + (methylamine cation), FA + (formamidinium cation), GA + (guanidinium cation), Cs + 、Rb + At least one of them; and / or, B ions include Pb 2+ Sn 2+ Ca 2+ 、Sr2+ Cd 2+ Cu 2+ Ni 2+ Mn 2+、 Fe 2+ Co 2+ Pd 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them.

[0095] In some implementations, refer to Figure 2 The solar cell 100 is an inverted perovskite solar cell. The functional layer 102 also includes a hole transport layer 1023. The inverted perovskite solar cell 100 includes a first electrode layer 101, a hole transport layer 1023, a perovskite layer 1021, an electron transport layer 1022, and a second electrode layer 103 stacked in sequence. The first electrode layer 101 is in the direction of light incident.

[0096] In some implementations, refer to Figure 3 The solar cell 100 is a formal perovskite solar cell. The functional layer 102 also includes a hole transport layer 1023. The formal perovskite solar cell 100 includes a first electrode layer 101, an electron transport layer 1022, a perovskite layer 1021, a hole transport layer 1023, and a second electrode layer 103 stacked in sequence. The first electrode layer 101 is in the direction of light incident.

[0097] The first electrode layer 101 includes a transparent conductive substrate. The transparent conductive substrate is used to extract photogenerated carriers. The transparent conductive substrate includes, but is not limited to, one of the following materials: FTO (fluorine-doped tin oxide), ITO (indium tin oxide), AZO (aluminum-doped zinc oxide), BZO (boron-doped zinc oxide), and IZO (indium-doped zinc oxide).

[0098] Electron transport layer 1022 performs the function of extracting electrons and blocking holes. Electron transport layer 1022 is at least one of the following materials and their derivatives, or materials obtained by doping or passivation: [6,6]-phenyl C 61 Methyl butyrate (PC) 61 BM), [6,6]-phenyl C 71 Methyl butyrate (PC) 71 BM), fullerene C60 (C60), fullerene C70 (C70), tin dioxide (SnO2), zinc oxide (ZnO), etc.

[0099] The hole transport layer 1023 is at least one of the following materials, their derivatives, and the materials obtained by doping or passivation thereof: nickel oxide, 2,2',7,7'-tetrakis(N,N-p-methoxyanilino)-9,9'-spirobifluorene (Spiro-OMeTAD), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACz), and other materials that have been reported in patents or literature.

[0100] The material of the second electrode layer 103 is an organic or inorganic or organic-inorganic hybrid conductive material, including but not limited to one or more of the following materials: Ag, Cu, C, Au, Al, ITO, AZO, BZO, IZO.

[0101] It should be noted that corresponding modification layers can be inserted between layers. For example, a passivation layer is inserted between the perovskite layer 1021 and the hole transport layer 1023, and / or between the perovskite layer 1021 and the electron transport layer 1022 to passivate the defects of the perovskite layer 1021, which can further improve the performance of the solar cell. For example, a hole blocking layer for blocking holes is inserted on the side of the electron transport layer 1022 away from the perovskite layer 1021, and the material can include SnO2, bathocuproine (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, BCP), etc.

[0102] The second technical solution adopted in this application is: to provide a preparation method of a solar cell 100 for preparing the solar cell 100 of any one of the above, including: providing a first electrode layer 101; setting a perovskite layer 1021 on the first electrode layer 101, and the chemical formula of the perovskite layer 1021 is AB(I x Br 1-x-m Y m )3, 0 < x < 1, 0 ≤ m ≤ 0.05, A ions include A' ions and / or A" ions, A' ions are inorganic monovalent cations, A" ions are organic monovalent cations, B ions include inorganic divalent cations, and Y ions include inorganic or organic or organic-inorganic hybrid monovalent anions. Among them, the method includes: using the evaporation method, the evaporation source at least includes BI2 and BBr2, and also includes evaporating or coating at least one of A'I and / or A"I to obtain the perovskite layer 1021; wherein, the evaporation rate of BBr2 gradually increases relative to the evaporation rate of BI2, or first gradually increases, then remains constant, and then gradually increases; setting an electron transport layer 1022 on the perovskite layer 1021; and setting a second electrode layer 103 on the electron transport layer 1022.

[0103] In some embodiments, in the step of providing the first electrode layer 101, the first electrode layer 101 may be a first electrode layer 101 disposed on the substrate structure.

[0104] In the technical solution of this application embodiment, the preparation method provided above for preparing the perovskite layer 1021 can control the evaporation rate of each raw material, thereby achieving precise control of the composition and structure of the perovskite layer 1021. At the same time, according to the evaporation rate control method provided above, the molar ratio of Br element in Br element and I element on the side of the perovskite layer 1021 near the electron transport layer 1022 is greater than the molar ratio of Br element in Br element and I element on the side away from the electron transport layer 1022. Since the radius of bromine atom is smaller than the radius of iodine atom, the perovskite cell on the side near the electron transport layer 1022 is smaller, and compressive stress is generated on the surface of the perovskite on the side near the electron transport layer 1022, which increases the migration barrier of iodine ions to the electrode layer, thereby weakening the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer 1022, thereby improving the stability of the solar cell 100.

[0105] In some embodiments, a vapor deposition method is used, wherein the vapor deposition source includes at least BI2 and BBr2, and further includes vapor deposition or coating of at least one of A'I and / or A”I to obtain the perovskite layer 1021, comprising: co-evaporating A'I, BI2 and BBr2, annealing, to obtain the perovskite layer 1021; or co-evaporating A'I, BI2 and BBr2 to obtain a preform layer, then vapor deposition of A”I, annealing, to obtain the perovskite layer 1021; or co-evaporating BI2 and BBr2 to obtain a preform layer, then vapor deposition of A”I, annealing, to obtain the perovskite layer 1021; or co-evaporating A”I, BI2 and BBr2 to obtain the perovskite layer 1021.

[0106] In some embodiments, the evaporation rate of BBr2 gradually increases relative to the evaporation rate of BI2, or first gradually increases, then remains constant, and then gradually increases again. Specifically, this includes: the evaporation rates of A'I, A”I, and BI2 are each independently constant, and the evaporation rate of BBr2 gradually increases, or first gradually increases, then remains constant, and then gradually increases again; or, the evaporation rates of A'I, A”I, and BBr2 are each independently constant, and the evaporation rate of BI2 gradually decreases, or first gradually decreases, then remains constant, and then gradually decreases again.

[0107] In some embodiments, the evaporation rate S1 of A'I is The evaporation rate S2 of A”I is The evaporation rate S3 of BI2 is The evaporation rate S4 of BBr2 is The acceleration a of the BBr2 evaporation rate S4 is

[0108] In the technical solution of this application embodiment, through the control method provided above, the molar ratio of Br element in Br element and I element on the side of perovskite layer 1021 near electron transport layer 1022 is greater than the molar ratio of Br element in Br element and I element on the side away from electron transport layer 1022. Since the radius of bromine atom is smaller than the radius of iodine atom, the perovskite cell on the side near electron transport layer 1022 is smaller, and compressive stress is generated on the surface of perovskite on the side near electron transport layer 1022, which increases the migration barrier of iodine ions to the electrode layer, thereby weakening the risk of iodine ions migrating to the electrode layer corresponding to electron transport layer 1022, thereby improving the stability of solar cell 100.

[0109] The evaporation rate S1 of A'I can be etc., or a range consisting of any two of the above values, for example wait.

[0110] The evaporation rate S2 of A”I can be etc., or a range consisting of any two of the above values, for example wait.

[0111] The evaporation rate S3 of BI2 can be etc., or a range consisting of any two of the above values, for example wait.

[0112] The evaporation rate S4 of BBr2 can be... etc., or a range consisting of any two of the above values, for example The acceleration a of the BBr2 evaporation rate S4 can be... etc., or a range consisting of any two of the above values, for example wait.

[0113] The third technical solution adopted in this application is: providing a method for preparing a solar cell 100, used to prepare the solar cell 100 according to any of the above, including: providing a first electrode layer 101; disposing an electron transport layer 1022 on the first electrode layer 101; and disposing a perovskite layer 1021 on the electron transport layer 1022, wherein the chemical formula of the perovskite layer 1021 is AB(I x Br z Y m)3, x+z+m=1, 0≤m≤0.05, A ions include A' ions and / or A” ions, A' ions are inorganic monovalent cations, A” ions are organic monovalent cations, B ions include inorganic divalent cations, Y ions include inorganic or organic or mixed organic-inorganic monovalent anions, wherein: a vapor deposition method is used, the vapor deposition source includes at least BI2 and BBr2, and at least one of A'I and / or A”I is vapor deposited or coated to obtain a perovskite layer 1021; wherein, the vapor deposition rate of BBr2 gradually decreases relative to the vapor deposition rate of BI2 or first gradually decreases, then remains constant, and then gradually decreases again; a second electrode layer 103 is provided on the perovskite layer 1021.

[0114] In some embodiments, in the step of providing the first electrode layer 101, the first electrode layer 101 may be a first electrode layer 101 disposed on the substrate structure.

[0115] In the technical solution of this application embodiment, the evaporation rate of each raw material can be controlled to achieve precise control of the composition and structure of the perovskite layer 1021. At the same time, according to the evaporation rate control method provided above, the molar ratio of Br element in Br element and I element on the side of the perovskite layer 1021 near the electron transport layer 1022 is greater than the molar ratio of Br element in Br element and I element on the side away from the electron transport layer 1022. Since the radius of bromine atom is smaller than the radius of iodine atom, the perovskite cell on the side near the electron transport layer 1022 is smaller, and compressive stress is generated on the surface of the perovskite on the side near the electron transport layer 1022, which increases the migration barrier of iodine ions to the electrode layer, thereby weakening the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer 1022, thereby improving the stability of the solar cell 100.

[0116] In some embodiments, a vapor deposition method is used, wherein the vapor deposition source includes at least BI2 and BBr2, and further includes the step of vapor deposition or coating of at least one of A'I and / or A”I to obtain the perovskite layer 1021, including: co-evaporating A'I, BI2 and BBr2, annealing, to obtain the perovskite layer 1021; or co-evaporating A'I, BI2 and BBr2 to obtain a preform layer, then vapor deposition of A”I, annealing, to obtain the perovskite layer 1021; or co-evaporating BI2 and BBr2 to obtain a preform layer, then vapor deposition of A”I, annealing, to obtain the perovskite layer 1021; or co-evaporating A”I, BI2 and BBr2, annealing, to obtain the perovskite layer 1021.

[0117] In some embodiments, the evaporation rate of BBr2 gradually decreases relative to the evaporation rate of BI2, or first gradually decreases, then remains constant, and then gradually decreases again. Specifically, this includes: the evaporation rates of A'I, A”I, and BI2 are each independently constant, and the evaporation rate of BBr2 gradually decreases, or first gradually decreases, then remains constant, and then gradually decreases again; or, the evaporation rates of A'I, A”I, and BBr2 are each independently constant, and the evaporation rate of BI2 gradually increases, or first gradually increases, then remains constant, and then gradually increases again.

[0118] In some embodiments, the evaporation rate S1 of A'I is The evaporation rate S2 of A”I is The evaporation rate S3 of BI2 is The evaporation rate S4 of BBr2 is The acceleration b of the BBr2 evaporation rate S4 is...

[0119] In the technical solution of this application embodiment, through the control method provided above, the molar ratio of Br element in Br element and I element on the side of perovskite layer 1021 near electron transport layer 1022 is greater than the molar ratio of Br element in Br element and I element on the side away from electron transport layer 1022. Since the radius of bromine atom is smaller than the radius of iodine atom, the perovskite cell on the side near electron transport layer 1022 is smaller, and compressive stress is generated on the surface of perovskite on the side near electron transport layer 1022, which increases the migration barrier of iodine ions to the electrode layer, thereby weakening the risk of iodine ions migrating to the electrode layer corresponding to electron transport layer 1022, thereby improving the stability of solar cell 100.

[0120] The evaporation rate S1 of A'I can be etc., or a range consisting of any two of the above values, for example wait.

[0121] The evaporation rate S2 of A”I can be etc., or a range consisting of any two of the above values, for example wait.

[0122] The evaporation rate S3 of BI2 can be etc., or a range consisting of any two of the above values, for example wait.

[0123] The evaporation rate S4 of BBr2 can be... etc., or a range consisting of any two of the above values, for example The acceleration b of the evaporation rate S4 of BBr2 can be... etc., or a range consisting of any two of the above values, for example wait.

[0124] Reference Figure 5 This application also provides a photovoltaic device 1000, including the solar cell 100 as described above or the solar cell 100 prepared by the method described above.

[0125] See Figure 6 This application also provides an electrical device 2000, including the solar cell 100 as described above or the solar cell 100 prepared by the method described above.

[0126] In this application, the solar cell 100 serves as the power source for the aforementioned electrical device 2000; alternatively, the solar cell 100 can serve as an energy storage unit for the aforementioned electrical device 2000. As an example, the electrical device 2000 can be a lighting element, a display element, or an automobile, etc.

[0127] See Figure 7 This application also provides a power generation device 3000, including the solar cell 100 as described above or the solar cell 100 prepared by the method described above. The power generation device 3000 may include the solar cell 100 and an energy storage device, which may be a secondary battery.

[0128] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0129] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0130] Example 1:

[0131] (1) Preparation of conductive glass electrode: The glass on which a transparent conductive film (fluorine-doped tin oxide FTO with a thickness of 600 nm) has been prepared is cleaned by washing with acetone-alcohol-deionized water in sequence; and then dried for later use.

[0132] (2) Preparation of hole transport layer: 2 mg of [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphoric acid (MeO-4PACz) was added to 4 mL of ethanol solvent and stirred. The ethanol solution of MeO-4PACz was spin-coated onto the first electrode layer at a spin speed of 4000 rpm for 30 s. Then it was transferred to a hot plate and annealed at 100 °C for 10 min to form the first carrier transport layer with a thickness of 2 nm.

[0133] (3) Preparation of the perovskite layer: Cesium iodide (CsI), lead iodide (PbI2), and lead bromide (PbBr2) were co-evaporated and deposited on the surface of the hole transport layer to obtain an inorganic layer, wherein, as a reference... Figure 8 CsI ​​initial evaporation rate The rate is constant; the PbI2 evaporation rate is The rate is constant; the initial evaporation rate of PbBr2 is according to The constant growth rate increased to The evaporation time was 460s; followed by constant-rate evaporation for 230s; and finally... The constant growth rate increased to The evaporation time was 90 s; at the end of the evaporation, the PbBr2 rate was... The total evaporation thickness is 260 nm; then, 250 nm of FAI is evaporated onto the inorganic layer surface at a evaporation rate of [missing information]. Transferred to a hot plate and annealed at 150°C for 15 min to obtain the perovskite layer FA. 0.9 Cs 0.1 Pb(I x Br 1-x )3, with a thickness of 510nm.

[0134] (4) Preparation of electron transport layer / hole blocking layer / second electrode: 25nm C60 (electron transport layer) / 7nm BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, hole blocking layer) / 80nm Cu were deposited on the perovskite substrate prepared in step (3) using a vapor deposition equipment.

[0135] Example 2

[0136] Similar to Example 1, the difference is:

[0137] Step (3) of Example 1 is adjusted to: co-evaporating and depositing lead iodide (PbI2) and lead bromide (PbBr2) on the surface of the hole transport layer to obtain an inorganic layer, wherein the PbI2 evaporation rate is... The rate is constant; the initial evaporation rate of PbBr2 is according to The constant growth rate increased to The evaporation time was 460s; followed by constant-rate evaporation for 230s; and finally... The constant growth rate increased to The evaporation time was 90 s; at the end of the evaporation, the PbBr2 rate was... The total evaporation thickness is 240 nm; then, 270 nm of FAI is evaporated onto the inorganic layer surface at a evaporation rate of [missing information]. Transferred to a hot plate and annealed at 150°C for 15 min to obtain a perovskite layer FAPb(I x Br 1-x )3, with a thickness of 510nm.

[0138] Example 3

[0139] Similar to Example 1, the difference is:

[0140] Step (3) of Example 1 is adjusted to: co-evaporating and depositing formamidinium iodide (FAI), lead iodide (PbI2), and lead bromide (PbBr2) on the surface of the hole transport layer, wherein the FAI evaporation rate is... The rate is constant; the PbI2 evaporation rate is The rate is constant; the initial evaporation rate of PbBr2 is according to The constant growth rate increased to The evaporation time was 460s; followed by constant-rate evaporation for 230s; and finally... The constant growth rate increased to The evaporation time was 90 s; at the end of the evaporation, the PbBr2 rate was... The total vapor deposition thickness was 500 nm; the layer was transferred to a hot plate and annealed at 150 °C for 15 min to obtain a perovskite layer FAPb(I x Br 1-x 3.

[0141] Example 4

[0142] Similar to Example 1, the difference is:

[0143] Step (3) of Example 1 is adjusted to: co-evaporating and depositing cesium iodide (CsI), lead iodide (PbI2), and lead bromide (PbBr2) on the surface of the hole transport layer, wherein the CsI evaporation rate is... The rate is constant; the PbI2 evaporation rate is The rate is constant; the initial evaporation rate of PbBr2 is according to The constant growth rate increased to The evaporation time was 460s; followed by constant-rate evaporation for 230s; and finally... The constant growth rate increased to The evaporation time was 90 s; at the end of the evaporation, the PbBr2 rate was... The total evaporation thickness was 500 nm; the layer was transferred to a hot plate and annealed at 150 °C for 15 min to obtain a perovskite layer CsPb(I) x Br 1-x 3.

[0144] Example 5

[0145] Similar to Example 1, the difference is:

[0146] Step (3) of Example 1 is adjusted to: co-evaporating and depositing cesium iodide (CsI), lead iodide (PbI2), and lead bromide (PbBr2) on the surface of the hole transport layer to obtain an inorganic layer, wherein, as reference Figure 8 CsI ​​initial evaporation rate The rate is constant; the PbI2 evaporation rate is The rate is constant; the initial evaporation rate of PbBr2 is according to The constant growth rate increased to The evaporation time was 1205s; followed by constant-rate evaporation for 600s; finally, the evaporation was carried out at a constant rate. The constant growth rate increased to The evaporation time was 78 s; at the end of the evaporation, the PbBr2 rate was... The total evaporation thickness is 260 nm; then, 250 nm of FAI is evaporated onto the inorganic layer surface at a evaporation rate of [missing information]. Transferred to a hot plate and annealed at 150°C for 15 min to obtain the perovskite layer FA. 0.9 Cs 0.1 Pb(I x Br 1-x )3, with a thickness of 510nm.

[0147] Example 6

[0148] Similar to Example 1, the difference is:

[0149] Step (3) of Example 1 is adjusted to: co-evaporating and depositing cesium iodide (CsI), lead iodide (PbI2), and lead bromide (PbBr2) on the surface of the hole transport layer to obtain an inorganic layer, wherein, as reference Figure 8 CsI ​​initial evaporation rate The rate is constant; the PbI2 evaporation rate is The rate is constant; the initial evaporation rate of PbBr2 is according to The constant growth rate increased to The evaporation time was 371 s; followed by constant rate evaporation for 153 s; finally, with The constant growth rate increased to The evaporation time was 179 s; at the end of the evaporation, the PbBr2 rate was... The total evaporation thickness is 260 nm; then, 250 nm of FAI is evaporated onto the inorganic layer surface at a evaporation rate of [missing information]. Transferred to a hot plate and annealed at 150°C for 15 min to obtain the perovskite layer FA. 0.9 Cs 0.1 Pb(I x Br 1-x )3, with a thickness of 510nm.

[0150] Example 7

[0151] Similar to Example 1, the difference is:

[0152] Step (3) of Example 1 is adjusted to: co-evaporating and depositing cesium iodide (CsI), lead iodide (PbI2), and lead bromide (PbBr2) on the surface of the hole transport layer to obtain an inorganic layer, wherein, as reference Figure 8 CsI ​​initial evaporation rate The rate is constant; the PbI2 evaporation rate is The rate is constant; the initial evaporation rate of PbBr2 is according to The constant growth rate increased to The evaporation time was 557 s; followed by constant rate evaporation for 229 s; and finally... The constant growth rate increased to The evaporation time was 45 s; at the end of the evaporation, the PbBr2 rate was... The total evaporation thickness is 260 nm; then, 250 nm of FAI is evaporated onto the inorganic layer surface at a evaporation rate of [missing information]. Transferred to a hot plate and annealed at 150°C for 15 min to obtain the perovskite layer FA. 0.9 Cs 0.1 Pb(I x Br 1-x )3, with a thickness of 510nm.

[0153] Example 8

[0154] Similar to Example 1, the difference is:

[0155] Step (3) of Example 1 is adjusted to: co-evaporating and depositing cesium iodide (CsI), lead iodide (PbI2), and lead bromide (PbBr2) on the surface of the hole transport layer to obtain an inorganic layer, wherein, as reference Figure 8 CsI ​​initial evaporation rate The rate is constant; the PbI2 evaporation rate is The rate is constant; the initial evaporation rate of PbBr2 is according to The constant growth rate increased to The evaporation time was 557 seconds; subsequently, with The constant growth rate increased to The evaporation time was 179 s; at the end of the evaporation, the PbBr2 rate was... The total evaporation thickness is 260 nm; then, 250 nm of FAI is evaporated onto the inorganic layer surface at a evaporation rate of [missing information]. Transferred to a hot plate and annealed at 150°C for 15 min to obtain the perovskite layer FA. 0.9 Cs 0.1 Pb(I x Br 1-x )3, with a thickness of 510nm.

[0156] Comparative Example 1

[0157] Similar to Example 1, the difference is:

[0158] Step (3) of Example 1 is adjusted to: co-evaporating and depositing cesium iodide (CsI), lead iodide (PbI2), and lead bromide (PbBr2) on the surface of the hole transport layer to obtain an inorganic layer, wherein the initial evaporation rate of CsI is... The rate is constant; the PbI2 evaporation rate is The deposition rate is constant; the deposition rate of PbBr2 is... The deposition rate was constant; the total deposition thickness was 260 nm; then, 250 nm of FAI was deposited on the inorganic layer surface at a deposition rate of [missing information]. Transferred to a hot plate and annealed at 150°C for 15 min to obtain the perovskite layer FA. 0.9 Cs 0.1 Pb(I 0.5 Br 0.5 )3, with a thickness of 510nm.

[0159] Battery performance tests were conducted on the battery devices 1 to 9 obtained from Examples 1 to 8 and Comparative Example 1, and the results are shown in Table 1.

[0160] Test method:

[0161] 1. Photoelectric conversion efficiency test method: Under standard simulated sunlight (AM1.5G, 100mW / cm²), 2Under irradiation, battery performance is tested to obtain the IV curve. Based on the IV curve and data from the testing equipment, the short-circuit current Jsc (unit: mA / cm²) can be calculated. 2 The open-circuit voltage Voc (in V), maximum light output current Jmpp (in mA), and maximum light output voltage Vmpp (in V) are given. The fill factor FF (in %) is calculated using the formula FF = Jsc × Voc / (Jmpp × Vmpp). The photoelectric conversion efficiency PCE (in %) is calculated using the formula PCE = Jsc × Voc × FF / Pw; Pw represents the input power (in mW).

[0162] 2. EDS Element Testing Method

[0163] Qualitative and quantitative analysis of elements in the test area was performed using scanning electron microscopy. The elemental proportions were calculated based on the peak areas of each element in the energy dispersive spectroscopy (EDS) results.

[0164] 3. X-ray diffraction testing method

[0165] The structural stability of the perovskite was analyzed using X-ray diffraction. The X-ray diffraction (XRD) patterns of the thin films were obtained using a Bruker D8 ADVANCE X-ray diffractometer operating at 40 kV and 40 mA, with a Cu target and Cu-Kα radiation at wavelengths of [wavelength missing].

[0166] Table 1 Battery Performance Tests (IV Tests)

[0167]

[0168]

[0169] Reference Figure 9 and Figure 10 The distribution of Br and I elements in the perovskite layer obtained by EDS elemental analysis in Example 1 is shown. Figure 9 In Example 1, the distribution of Br element in the perovskite layer shows that the first region A is a bromine-rich region. Figure 10 The distribution of element I in the perovskite layer in Example 1 shows that the second region B forms an iodine-rich area.

[0170] The distribution of Br and I elements in Example 1 is shown in Table 2.

[0171] Reference Figure 11 The image shown is the X-ray diffraction (XRD) pattern of Example 1. The XRD results show that no other perovskite phase diffraction peaks were generated after 30 days of storage, indicating that the solar cell 100 has good stability.

[0172] Table 2 Elemental Ratios (EDS Test)

[0173]

[0174] As can be seen from the data in Table 1, the solar cell devices in Examples 1-8 all controlled the evaporation rate of each raw material to prepare the perovskite layer, and their efficiency on day 1 and photoelectric conversion efficiency on day 30 were higher than those of Comparative Example 1. This indicates that by using the preparation method provided in this application to prepare the perovskite layer and controlling the evaporation rate of each raw material, the composition and structure of the perovskite layer can be precisely controlled. This results in a greater molar ratio of Br to I on the side of the perovskite layer closer to the electron transport layer than on the side farther from the electron transport layer. Since the radius of a bromine atom is smaller than that of an iodine atom, the perovskite cell on the side closer to the electron transport layer is smaller, and compressive stress is generated on the surface of the perovskite on the side closer to the electron transport layer. This increases the migration barrier for iodine ions to migrate to the electrode layer, thereby reducing the risk of iodine ions migrating to the electrode layer corresponding to the electron transport layer and improving the stability of the solar cell.

[0175] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A solar cell, characterized in that, The solar cell includes a first electrode layer, a functional layer, and a second electrode layer which are stacked in sequence. The functional layer includes a perovskite layer and an electron transport layer. The chemical formula of the perovskite layer is AB(I x Br 1-x-m Y m )3, where 0 < x < 1 and 0 ≤ m ≤ 0.

05. Here, the A ions include inorganic, organic, or organic-inorganic hybrid monovalent cations, the B ions include inorganic divalent cations, and the Y ions include inorganic, organic, or organic-inorganic hybrid monovalent anions. The perovskite layer includes a first region closer to the electron transport layer and a second region farther from the electron transport layer, and the x value of the first region is less than that of the second region.

2. The solar cell as described in claim 1, characterized in that, In the first region, x < 0.5, and in the second region, x > 0.

5.

3. The solar cell as described in claim 1 or 2, characterized in that, In the first and second regions, x gradually decreases along the direction from the perovskite layer toward the electron transport layer.

4. The solar cell according to any one of claims 1 to 3, characterized in that, On the interface of the perovskite layer near the electron transport layer, 0.35≤x≤0.

45.

5. The solar cell according to any one of claims 1 to 4, characterized in that, On the interface of the perovskite layer away from the electron transport layer, 0.6 ≤ x < 1.

6. The solar cell according to any one of claims 1 to 5, characterized in that, The thickness of the first region in the thickness direction of the perovskite layer is 10% to 50%.

7. The solar cell according to any one of claims 1 to 5, characterized in that, The thickness of the first region in the thickness direction of the perovskite layer is 10% to 20%.

8. The solar cell according to any one of claims 1 to 7, characterized in that, The second region accounts for 50% to 90% of the thickness in the thickness direction of the perovskite layer.

9. The solar cell according to any one of claims 1 to 8, characterized in that, The second region accounts for 50% to 60% of the thickness in the thickness direction of the perovskite layer.

10. The solar cell according to any one of claims 1 to 5, characterized in that, The perovskite layer also includes an intermediate region located between the first region and the second region, where x = 0.

5.

11. The solar cell as claimed in claim 10, characterized in that, The thickness of the intermediate region in the direction of the perovskite layer is greater than 0 and less than or equal to 50%.

12. The solar cell as claimed in claim 10, characterized in that, The thickness of the first region in the thickness direction of the perovskite layer is 10% to 40%.

13. The solar cell as claimed in claim 10, characterized in that, The second region accounts for 40% to 60% of the thickness in the thickness direction of the perovskite layer.

14. The solar cell according to claims 1 to 13, characterized in that, The thickness of the perovskite layer is 400 nm to 1000 nm.

15. The solar cell according to any one of claims 1 to 14, characterized in that, The A ion includes methylamine cation, formamidinium cation, guanidine cation, and Cs cation. + 、Rb + One or more of the following; and / or, the B ions include Pb. 2+ Sn 2+ Ca 2+ 、Sr 2+ Cd 2+ Cu 2+ Ni 2+ Mn 2+、 Fe 2+ Co 2+ Pd 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of the following, wherein the Y ion includes F - Cl - SCN - BF4 - PF6 - One or more of them.

16. A method for preparing a solar cell, used to prepare a solar cell as described in any one of claims 1 to 15, characterized in that, include: Provide a first electrode layer; A perovskite layer is disposed on the first electrode layer, the chemical formula of which is AB(I) x Br 1-x-m Y m 3, 0 < x < 1, 0 ≤ m ≤ 0.05, A ions include A' ions and / or A” ions, wherein A' ions are inorganic monovalent cations, A” ions are organic monovalent cations, B ions include inorganic divalent cations, and Y ions include inorganic, organic, or mixed organic-inorganic monovalent anions, wherein: The perovskite layer is obtained by vapor deposition, wherein the vapor deposition source includes at least BI2 and BBr2, and also includes vapor deposition or coating of at least one of A'I and / or A”I. Among them, the evaporation rate of BBr2 gradually increases relative to the evaporation rate of BI2, or first gradually increases, then remains constant, and then gradually increases again; An electron transport layer is disposed on the perovskite layer; and A second electrode layer is disposed on the electron transport layer.

17. The method for preparing a solar cell as described in claim 16, characterized in that, The evaporation rate S1 of A'I is The evaporation rate S2 of A”I is The evaporation rate S3 of BI2 is The evaporation rate S4 of BBr2 is The acceleration a of the BBr2 evaporation rate S4 is 18. A method for preparing a solar cell, used to prepare a solar cell as described in any one of claims 1 to 15, characterized in that, include: Provide a first electrode layer; An electron transport layer is disposed on the first electrode layer; A perovskite layer is provided on the electron transport layer, and the chemical formula of the perovskite layer is AB(I x Br 1-x-m Y m )3, 0 < x < 1, 0 ≤ m ≤ 0.

05. The A ions include A' ions and / or A" ions. The A' ions are inorganic monovalent cations, and the A" ions are organic monovalent cations. The B ions include inorganic divalent cations, and the Y ions include inorganic or organic or organic-inorganic hybrid monovalent anions, where, including: The perovskite layer is obtained by vapor deposition, wherein the vapor deposition source includes at least BI2 and BBr2, and also includes vapor deposition or coating of at least one of A'I and / or A”I. Among them, the evaporation rate of BBr2 gradually decreases relative to the evaporation rate of BI2, or first gradually decreases, then remains constant, and then gradually decreases again. A second electrode layer is disposed on the perovskite layer.

19. The method for preparing a solar cell as described in claim 18, characterized in that, The evaporation rate S1 of A'I is The evaporation rate S2 of A”I is The evaporation rate S3 of BI2 is The evaporation rate S4 of BBr2 is The acceleration b of the BBr2 evaporation rate S4 is...

20. A photovoltaic device, characterized in that, The solar cell includes any one of claims 1 to 15, or the method of preparing the solar cell includes any one of claims 16 to 19.

21. An electrical appliance, characterized in that, The solar cell includes any one of claims 1 to 15, or the method of preparing the solar cell includes any one of claims 16 to 19.

22. A power generation device, characterized in that, The solar cell includes any one of claims 1 to 15, or the method of preparing the solar cell includes any one of claims 16 to 19.

Images