Perovskite solar cell and preparation method thereof, photovoltaic module

Abstract

The application discloses a perovskite solar cell, a preparation method thereof and a photovoltaic module. The perovskite solar cell comprises a perovskite layer, the material of the perovskite layer is organic-inorganic perovskite, the perovskite layer comprises a bulk perovskite region and a surface perovskite region, and the two regions have metal atoms and halogen atoms; the surface perovskite of the surface perovskite region and the bulk perovskite of the bulk perovskite region at least satisfy one of the following relationships: (1) the atomic percentage of the metal atoms in A1 position of the surface perovskite region is a1, the atomic percentage of the metal atoms in A2 position of the bulk perovskite region is a2, and a1 is greater than a2; (2) the atomic percentage of the halogen atoms in X1 position of the surface perovskite region is x1, the atomic percentage of the halogen atoms in X2 position of the bulk perovskite region is x2, the halogen atoms are chlorine atoms and / or bromine atoms, and x1 is greater than x2. The application can improve the ability of the perovskite layer to resist water and oxygen corrosion.

Description

Technical Field

[0001] This application relates to the technical field of solar cells, and more particularly to a perovskite solar cell and its preparation method, as well as a photovoltaic module. Background Technology

[0002] The perovskite material in perovskite solar cells is very sensitive to moisture and oxygen, and is very easy to degrade in air containing water and oxygen, which leads to a decrease in the stability of the perovskite layer and severely limits the further improvement of the performance of perovskite solar cells. Summary of the Invention

[0003] To improve the stability of the perovskite layer and enable it to better resist water and oxygen erosion, this application provides a perovskite solar cell, its preparation method, and a photovoltaic module.

[0004] In a first aspect, embodiments of this application provide a perovskite solar cell.

[0005] A perovskite solar cell includes a perovskite layer made of organic-inorganic perovskite. The perovskite layer comprises a central bulk perovskite region and surface perovskite regions located on either side of the bulk perovskite region. Both the surface perovskite regions and the bulk perovskite regions contain metal atoms and halogen atoms. At least one of the following relationships is satisfied between the surface perovskite in the surface perovskite regions and the bulk perovskite in the bulk perovskite regions: (1) The atomic percentage of the metal atoms in the surface perovskite region at the A1 position is a1, and the atomic percentage of the metal atoms in the bulk perovskite region at the A2 position is a2, wherein a1 is greater than a2; (2) The percentage of halogen atoms at position X1 in the surface perovskite region is x1, the percentage of halogen atoms at position X2 in the bulk perovskite region is x2, the halogen atoms are chlorine atoms and / or bromine atoms, and x1 is greater than x2. Wherein, the A1 site is the A cation site of the surface perovskite in the surface perovskite region, the A2 site is the A cation site of the bulk perovskite in the bulk perovskite region, the X1 site is the anion site of the surface perovskite in the surface perovskite region, and the X2 site is the anion site of the bulk perovskite in the bulk perovskite region.

[0006] As an optional implementation, in the embodiments of this application, a1 is 10%~86%, and a2 is 2%~9%; And / or, x1 is 10%~50%, and x2 is 2%~9%.

[0007] As an optional implementation, in the embodiments of this application, the metal atoms include one or more combinations of Li, Na, K, Rb, Cs, Ag, Au, Cu, Tl, Pb, Sn, Ge, Mg, Ca, Sr, Ba, Zn, Cd, Hg, Ni, Co, Fe, Mn, Bi, Sb, In, Ga, Al, Cr, and rare earth metals.

[0008] As an optional implementation, in the embodiments of this application, along the direction from the bulk perovskite region to the surface perovskite region, the atomic percentage of the metal atoms in the surface perovskite region at the Al sites increases, and / or, the atomic percentage of the halogen atoms in the surface perovskite region at the anion sites increases.

[0009] As an optional implementation, in the embodiments of this application, along the direction from the bulk perovskite region to the surface perovskite region, the atomic percentage of the metal atoms in the surface perovskite region at the Al sites increases in a gradient, and / or, the atomic percentage of the halogen atoms in the surface perovskite region at the anion sites increases in a gradient. The surface perovskite region has a first perovskite sub-region to an Nth perovskite sub-region arranged sequentially away from the bulk perovskite region. Along the direction from the bulk perovskite region to the surface perovskite region, the thickness of the first perovskite sub-region to the Nth perovskite sub-region decreases layer by layer, where N is a positive integer greater than or equal to 2.

[0010] As an optional implementation, in an embodiment of this application, the surface perovskite region includes a first perovskite sub-region, a second perovskite sub-region, and a third perovskite sub-region disposed sequentially away from the bulk perovskite region, wherein: The thickness of the first perovskite sub-region is 3 nm to 10 nm, the atomic percentage of the metal atoms at the A1 site is 10% to 30%, and the atomic percentage of the halogen atoms at the X1 site is 10% to 20%. The thickness of the second perovskite sub-region is 2 nm to 10 nm, the atomic percentage of the metal atoms at the A1 site is 30% to 50%, and the atomic percentage of the halogen atoms at the X1 site is 20% to 30%. The thickness of the third perovskite sub-region is 0.1 nm to 8 nm, the atomic percentage of the metal atoms at the A1 site is 50% to 86%, and the atomic percentage of the halogen atoms at the X1 site is 30% to 50%.

[0011] As an optional implementation, in the embodiments of this application, the roughness of the side of the surface perovskite region facing away from the bulk perovskite region is less than 40 nm. And / or, the thickness of the surface perovskite region is 5 nm to 28 nm.

[0012] As an optional implementation, in an embodiment of this application, the side of the surface perovskite region facing away from the bulk perovskite region is covered with a sealing layer, wherein: The material of the sealing layer includes one or more combinations of silicon nitride, silicon oxynitride and aluminum oxide, and / or the thickness of the sealing layer is 0.2 mm to 2 mm.

[0013] As an optional implementation, in the embodiments of this application, the perovskite layer includes an active photoelectric conversion region at the center and an inactive photoelectric conversion region at the edge, and the perovskite layer satisfies at least one of the following conditions: (1) The area of ​​the active photoelectric conversion region accounts for more than 90% of the total area of ​​the perovskite layer; (2) The width of the inactive photoelectric conversion region is less than or equal to 2 mm; (3) The difference in fill factor between the active photoelectric conversion region and the inactive photoelectric conversion region is greater than or equal to 10%.

[0014] As an optional implementation, in the embodiments of this application, the perovskite solar cell includes a perovskite single-junction solar cell or a perovskite tandem solar cell, and the perovskite tandem solar cell includes any one of perovskite-silicon tandem solar cell, perovskite-copper indium gallium selenide tandem cell, and perovskite-organic tandem cell. The perovskite single-junction solar cell includes the following structure: Transparent conductive substrate; A first transport layer disposed on the transparent conductive substrate; The perovskite layer is disposed on the side of the first transport layer opposite to the transparent conductive substrate; A second transport layer is also provided on the side of the perovskite layer away from the transparent conductive substrate. One of the first transport layer and the second transport layer is an electron transport layer, and the other is a hole transport layer. A first electrode is disposed on the side of the second transport layer away from the transparent conductive substrate, and the first electrode forms an ohmic contact with the second transport layer. A second electrode is disposed on the transparent conductive substrate, and the transparent conductive substrate forms an ohmic contact with the second electrode. The perovskite tandem solar cell includes the following structure: The bottom battery is any one of silicon bottom battery, copper indium gallium selenide bottom battery, and organic bottom battery; The bottom battery is provided with a carrier intermediate composite layer; A first transport layer is provided on the side of the charge carrier intermediate composite layer opposite to the bottom battery; The perovskite layer is disposed on the side of the first transport layer opposite to the bottom cell; A second transport layer is provided on the side of the perovskite layer away from the bottom cell. One of the first transport layer and the second transport layer is an electron transport layer, and the other is a hole transport layer. A transparent conductive layer is provided on the side of the second transmission layer that is away from the bottom battery; A first electrode is disposed on the transparent conductive layer, so that the first electrode and the transparent conductive layer form an ohmic contact.

[0015] Secondly, embodiments of this application provide a method for preparing a perovskite solar cell.

[0016] A method for fabricating a perovskite solar cell includes the following steps: A perovskite initial layer is provided, wherein the material of the perovskite initial layer is an organic-inorganic perovskite; Atom diffusion is performed on the sides of the initial perovskite layer to form a perovskite layer. The perovskite layer includes a central bulk perovskite region and surface perovskite regions located on the sides of the bulk perovskite region. The atoms include metal atoms and halogen atoms, such that the surface perovskite in the surface perovskite regions and the bulk perovskite in the bulk perovskite regions satisfy at least one of the following relationships: (1) The atomic percentage of the metal atoms in the surface perovskite region at the A1 position is a1, and the atomic percentage of the metal atoms in the bulk perovskite region at the A2 position is a2, wherein a1 is greater than a2; (2) The percentage of halogen atoms at position X1 in the surface perovskite region is x1, the percentage of halogen atoms at position X2 in the bulk perovskite region is x2, the halogen atoms are chlorine atoms and / or bromine atoms, and x1 is greater than x2. The A1 site is the A cation site of the surface perovskite in the surface perovskite region, the A2 site is the A cation site of the bulk perovskite in the bulk perovskite region, the X1 site is the anion site of the surface perovskite in the surface perovskite region, and the X2 site is the anion site of the bulk perovskite in the bulk perovskite region.

[0017] As an optional implementation, in the embodiments of this application, before the step of performing atomic diffusion treatment on the side of the perovskite initial layer and after the step of providing the perovskite initial layer, the preparation method further includes: cutting the side of the perovskite initial layer to remove the inactive photoelectric conversion region located at the circumferential edge of the perovskite initial layer, and retaining the active photoelectric conversion region located at the center of the perovskite initial layer, wherein the width of the inactive photoelectric conversion region removed by the cutting process is 0.2 mm to 10 mm.

[0018] As an optional implementation, in an embodiment of this application, the step of providing the perovskite initial layer is: preparing a perovskite top cell with the perovskite initial layer. As an optional implementation, in an embodiment of this application, before the step of performing atomic diffusion treatment on the sides of the perovskite initial layer, a protective adhesive layer is applied to the top surface of the perovskite top cell; after the step of performing atomic diffusion treatment on the sides of the perovskite initial layer, the protective adhesive layer is removed, wherein: The thickness of the protective adhesive layer is 2 mm to 15 mm, and / or the protective adhesive layer includes one or a combination of two of polymethyl methacrylate and polyimide.

[0019] As an optional implementation, in the embodiments of this application, the step of performing atomic diffusion treatment on the side of the perovskite initial layer includes: depositing a metal halide layer with a thickness of 5 nm to 28 nm on the side of the perovskite initial layer, annealing at 100°C to 150°C for 1 min to 10 min, so that the metal halide in the metal halide layer diffuses into the perovskite initial layer to obtain the surface perovskite region, wherein the percentage of metal atoms at the A1 site in the surface perovskite region increases continuously in a gradient along the direction away from the bulk perovskite region; The method of depositing the metal halide layer includes any one of vapor deposition, reactive plasma deposition, physical vapor deposition, and atomic layer deposition. The metal halide includes one or more combinations of CsCl, CsBr, RbCl, RbBr, KCl, KBr, PbCl2, and PbBr2.

[0020] As an optional implementation, in an embodiment of this application, the step of performing atomic diffusion treatment on the side surface of the perovskite initial layer includes: Deposition of metal halide sublayer: A first metal halide sublayer is deposited on the side of the initial perovskite layer; Annealing treatment: Perform a first annealing treatment to allow the metal halide of the first metal halide sublayer to diffuse into the perovskite initial layer; The steps of depositing the metal halide sublayer and the annealing treatment are repeated at least once to obtain the surface perovskite region, wherein the atomic percentage of the metal atoms at the A1 site in the surface perovskite region increases continuously in a gradient away from the bulk perovskite region. The method of depositing the metal halide sublayer includes any one of vapor deposition, reactive plasma deposition, physical vapor deposition, and atomic layer deposition. The metal halide includes one or more combinations of CsCl, CsBr, RbCl, RbBr, KCl, KBr, PbCl2, and PbBr2.

[0021] As an optional implementation, in the embodiments of this application, during the steps of cyclically depositing the metal halide sublayer and the annealing treatment: The thickness of the metal halide sublayer deposited earlier is less than the thickness of the metal halide sublayer deposited later; The temperature of the annealing process performed earlier is higher than the temperature of the annealing process performed later; The time taken for the annealing process performed earlier is less than the time taken for the annealing process performed later.

[0022] As an optional implementation, in the embodiments of this application, the metal halide deposition and annealing steps are cycled three times, wherein: The thickness of the first metal halide sublayer is 3 nm to 10 nm, and the first annealing treatment is annealing at 130°C to 150°C for 1 min to 3 min; The thickness of the second metal halide sublayer is 2 nm to 10 nm, and the second annealing treatment is annealing at 100℃ to 130℃ for 2 min to 5 min. The thickness of the third metal halide sublayer is 0.1 nm to 8 nm, and the third annealing treatment is annealing at 25℃ to 100℃ for 5 min to 20 min; After the step of performing atomic diffusion treatment on the side of the initial perovskite layer, the resulting surface perovskite region includes a first perovskite sub-region, a second perovskite sub-region, and a third perovskite sub-region arranged sequentially away from the bulk perovskite region, wherein: The thickness of the first perovskite sub-region is 3 nm to 10 nm, the atomic percentage of the metal atoms at the A1 site is 10% to 30%, and the atomic percentage of the halogen atoms at the X1 site is 10% to 20%. The thickness of the second perovskite sub-region is 2 nm to 10 nm, the atomic percentage of the metal atoms at the A1 site is 30% to 50%, and the atomic percentage of the halogen atoms at the X1 site is 20% to 30%. The thickness of the third perovskite sub-region is 0.1 nm to 8 nm, the atomic percentage of the metal atoms at the A1 site is 50% to 86%, and the atomic percentage of the halogen atoms at the X1 site is 30% to 50%.

[0023] As an optional implementation, in an embodiment of this application, after the atomic diffusion treatment step, a sealing layer is deposited on the side of the perovskite layer, such that the sealing layer covers the surface of the surface perovskite region away from the bulk perovskite region.

[0024] Thirdly, embodiments of this application provide a photovoltaic module.

[0025] A photovoltaic module includes a perovskite solar cell as described in the first aspect or a perovskite solar cell prepared by the preparation method described in the second aspect.

[0026] Compared with the prior art, the beneficial effects of this application are as follows: This application achieves a synergistic improvement in the photoelectric conversion efficiency and stability of solar cells by regulating the composition of the surface perovskite region within the perovskite layer. This is achieved by increasing the proportion of metal atoms at A-cation sites or specific halogen atoms (i.e., chlorine and / or bromine atoms) at anion sites in the surface perovskite. Specifically, by increasing the content of metal atoms or specific halogen atoms in the surface perovskite, this application can passivate the dangling bonds at A-cation sites and anion sites, respectively, effectively reducing interface defects in the perovskite layer and suppressing carrier recombination, thereby directly improving the photoelectric conversion efficiency of the solar cell. Furthermore, the metal atoms or specific halogen atoms enriched in the surface perovskite region can also weaken the binding force between the surface perovskite and water and oxygen, forming a better barrier against water and oxygen erosion. Maintaining a low content of metal atoms or specific halogen atoms in the bulk region can maintain efficient carrier transport, ultimately significantly enhancing the overall stability of the solar cell while ensuring efficient carrier transport. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1This is a schematic diagram of the structure of the first type of solar cell disclosed in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the second type of solar cell disclosed in the embodiments of this application; Figure 3 This is a schematic diagram of the perovskite layer structure from a top-down view, as disclosed in the embodiments of this application; Figure 4 This is a schematic diagram of the structure of the inactive photoelectric conversion region and the active photoelectric conversion region in the initial layer of the perovskite disclosed in the embodiments of this application; Figure 5 This is a schematic diagram of the structure before and after atomic diffusion treatment of the perovskite initial layer disclosed in the embodiments of this application; Figure 6 This is an XPS test result graph showing the percentage of Cs atoms at the A site in Embodiment 1 of this application; Figure 7 This is an XPS test result graph showing the atomic percentage of Cl at the X position in Example 1 of this application.

[0029] Icons: 1. Perovskite layer; 11. Bulk perovskite region; 12. Surface perovskite region; 121. First perovskite sub-region; 122. Second perovskite sub-region; 123. Third perovskite sub-region; 1A. Initial perovskite layer; 1a. Active photoelectric conversion region; 1b. Inactive photoelectric conversion region; 13. Sealing layer; 2. Transparent conductive substrate; 3. First transport layer; 4. Second transport layer; 5. First electrode; 6. Second electrode; 7. Bottom cell; 8. Carrier intermediate recombination layer; 9. Transparent conductive layer. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. 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.

[0031] Organic cations possess superior carrier mobility and diffusion length. Applying organic cations to perovskite materials to form organic-inorganic perovskite materials can enhance carrier transport capabilities and reduce non-radiative recombination. However, organic-inorganic perovskite materials are susceptible to corrosion and degradation by moisture and oxygen in the environment, leading to instability of the perovskite layer. The sides of the perovskite layer, in particular, are exposed and more vulnerable to moisture and oxygen erosion.

[0032] To address the aforementioned shortcomings and improve the stability of the perovskite layer, this application provides a perovskite solar cell, its fabrication method, and a photovoltaic module. The technical solution of this application will be further described below with reference to embodiments and accompanying drawings.

[0033] In a first aspect, embodiments of this application provide a perovskite solar cell.

[0034] Reference Figure 1 or Figure 2 The perovskite solar cell shown includes a perovskite layer 1, which is made of organic-inorganic perovskite, combined with... Figure 3 The schematic diagram of the perovskite layer 1 from a top-down perspective shows that the perovskite layer 1 includes a central bulk perovskite region 11 and surface perovskite regions 12 located on the sides of the bulk perovskite region 11. Both the surface perovskite region 12 and the bulk perovskite region 11 contain metal atoms and halogen atoms. At least one of the following relationships must be satisfied between the surface perovskite of the surface perovskite region 12 and the bulk perovskite of the bulk perovskite region 11: (1) The percentage of metal atoms in the surface perovskite region 12 at the A1 position is a1, and the percentage of metal atoms in the bulk perovskite region 11 at the A2 position is a2. a1 is greater than a2. (2) The percentage of halogen atoms at position X1 in the surface perovskite region 12 is x1, and the percentage of halogen atoms at position X2 in the bulk perovskite region 11 is x2. The halogen atoms are chlorine atoms and / or bromine atoms, and x1 is greater than x2. Wherein, A1 site is the A cation site of the surface perovskite in the surface perovskite region 12, A2 site is the A cation site of the bulk perovskite in the bulk perovskite region 11, X1 site is the anion site of the surface perovskite in the surface perovskite region 12, and X2 site is the anion site of the bulk perovskite in the bulk perovskite region 11.

[0035] Compared to the bulk perovskite region 11, this application can simultaneously improve the defect passivation effect and water and oxygen resistance of the surface perovskite by increasing the proportion of metal atoms at A cation sites in the surface perovskite, or by increasing the proportion of specific halogen atoms (i.e. chlorine atoms and / or bromine atoms) at anion sites in the surface perovskite, thereby further improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0036] Specifically, the increase in metal atoms in the surface perovskite effectively passivates the dangling bonds at the A cation sites, thereby reducing interfacial recombination of charge carriers and lowering interfacial defects in perovskite layer 1. The increase in chlorine and / or bromine atoms in the surface perovskite effectively passivates the dangling bonds at the anion sites, reducing interfacial defects in perovskite layer 1. Furthermore, the increase in metal atoms and specific halogen atoms (chlorine and / or bromine atoms) weakens the binding force between the surface perovskite and water and oxygen, making the surface perovskite less reactive with water and oxygen, thus improving the stability of the surface perovskite against water and oxygen erosion, and consequently improving the overall stability of perovskite layer 1. In addition, the atomic percentage of metal atoms at the A cation sites and the atomic percentage of halogen atoms at the anion sites in the bulk perovskite region 11 of this application remain low, which is beneficial for better charge carrier transport.

[0037] In summary, through the combined action of the surface perovskite region 12 and the bulk perovskite region 11, this application achieves a synergistic improvement in the photoelectric conversion efficiency and stability of perovskite solar cells.

[0038] It should be noted that the typical organic-inorganic perovskite has the structural formula ABX3. The A-cation site mentioned in this application refers to the A-position cation in ABX3. The A-position cation contains both organic and inorganic cations. The organic cations include monovalent organic cations such as methylamine cations or formamidinium cations, and the inorganic cations include monovalent metal ions such as cesium ions and rubidium ions. The B-position cation in ABX3 includes divalent metal cations such as lead ions. The anion site mentioned in this application refers to the anion (X) site in ABX3, and the anions include chloride ions, bromide ions, or iodide ions. Furthermore, in embodiments of this application, the B-position cation can undergo heterovalent substitution, i.e., it can be doped with a trivalent metal cation (such as Bi). 3+ Sb 3+ In 3+ (And rare earth metal ions, etc.). When trivalent metal cations partially replace divalent metal cations occupying B-site cations, the charge balance and phase stability of the overall perovskite structure are maintained through a charge compensation mechanism that forms A-site cation vacancies in the perovskite lattice.

[0039] In some embodiments, a1 is 10%~86%, a2 is 2%~9%; and / or, x1 is 10%~50%, x2 is 2%~9%.

[0040] By controlling a1 between 10% and 86%, it is beneficial to form a surface perovskite phase with a higher metal atom occupancy in the surface perovskite region 12, thereby improving the defect passivation effect and water and oxygen resistance of the surface perovskite. For example, a1 can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 86%, etc.

[0041] By controlling x1 between 10% and 50%, the anionic sites of chlorine or bromine atoms in the surface perovskite are increased, which can better reduce the possibility of the surface perovskite reacting with water and oxygen. For example, x1 can be 10%, 20%, 30%, 40%, 50%, etc.

[0042] Controlling a2 to a value between 2% and 9% or x2 to a value between 2% and 9% can improve the carrier transport performance of bulk perovskites and better promote carrier transport. For example, a2 can be 2%, 4%, 6%, 9%, etc.; x2 can be 2%, 4%, 6%, 9%, etc.

[0043] Furthermore, the content of metal atoms and halogen atoms in the surface perovskite region 12 can maintain a relatively uniform atomic percentage, or it can exhibit a certain gradient variation. In this application, a1 is 10%~86%, and x1 is 10%~50%, meaning that in the surface perovskite region 12, the atomic percentage of metal atoms at the A cation sites varies gradient within the range of 10%~86%, and the atomic percentage of halogen atoms at the anion sites varies gradient within the range of 10%~50%. The distribution of metal atoms and halogen atoms in the bulk perovskite region 11 is relatively uniform, with a small overall content variation. Among them, a2 is 2%~9%, meaning that the atomic percentage of metal atoms at the A cation sites in the bulk perovskite can be any point within the range of 2%~9%, and x2 is 2%~9%, meaning that the atomic percentage of halogen atoms at the anion sites in the bulk perovskite is any point within the range of 2%~9%.

[0044] In some embodiments, the metal atoms include one or more combinations of Li, Na, K, Rb, Cs, Ag, Au, Cu, Tl, Pb, Sn, Ge, Mg, Ca, Sr, Ba, Zn, Cd, Hg, Ni, Co, Fe, Mn, Bi, Sb, In, Ga, Al, Cr, and rare earth metals.

[0045] Metal atoms such as Cs, Pb, Rb, and K can passivate the dangling bonds at the A or B cation sites of the surface perovskite, thereby improving the stability of the surface perovskite region 12. Some metal atoms (such as Li, Na, K, Rb, Cs, Ag, Au, Cu, Tl, Ce, and Hg) can effectively increase the atomic percentage of the metal atom at the A cation site by occupying it, thus enhancing the surface perovskite's resistance to water and oxygen erosion.

[0046] Furthermore, when Cu and Tl occupy the A cation site, they tend to be monovalent Cu. + and Tl + It exists in the form of Cu. When Cu occupies a B cation site, Cu tends to exist as Cu in the divalent form.2+ It exists in the form of Bi, Sb, In, Ga, and Al occupying the B cation site, and they tend to exist in the form of Bi. 3+ Sb 3+ In 3+ Ga 3+ Al 3+ It exists in the form of Ni. When Ni, Co, and Fe occupy the B cation site, it can exist as Ni. 2+ Co 2+ Fe 2+ It exists in the form of Ni, and can also be expressed as Ni. 3+ Co 3+ Fe 3+ It exists in the form of.

[0047] In some embodiments, along the direction from the bulk perovskite region 11 to the surface perovskite region 12, the atomic percentage of metal atoms at the A1 sites in the surface perovskite region 12 increases, and / or, the atomic percentage of halogen atoms at the anion sites in the surface perovskite region 12 increases.

[0048] The surface perovskite region 12, located near the bulk perovskite region 11, has a lower percentage of metal atoms at the Al sites or specific halogen atoms at the anion sites. This reduces the amount of metal atoms or specific halogen atoms diffusing into the bulk perovskite region 11, thereby improving carrier transport performance. The surface of the surface perovskite region 12, further away from the bulk perovskite region 11, is enriched with more metal atoms or specific halogen atoms. This allows for the formation of a perovskite phase dominated by metal atoms or specific halogen atoms in the surface perovskite region 12, enhancing its resistance to water and oxygen erosion in the environment.

[0049] In some embodiments, along the direction from the bulk perovskite region 11 to the surface perovskite region 12, the atomic percentage of metal atoms at the Al sites in the surface perovskite region 12 increases in a gradient, and / or, the atomic percentage of halogen atoms at the anion sites in the surface perovskite region 12 increases in a gradient. The surface perovskite region 12 has a first perovskite sub-region 121 to an Nth perovskite sub-region arranged sequentially away from the bulk perovskite region 11. Along the direction from the bulk perovskite region 11 to the surface perovskite region 12, the thickness of the first perovskite sub-region 121 to the Nth perovskite sub-region decreases layer by layer, where N is a positive integer greater than or equal to 2.

[0050] The first perovskite sub-region 121, which is close to the bulk perovskite region 11, mainly contributes to the passivation effect. Therefore, the first perovskite sub-region 121 has the thickest thickness, and the atomic percentage of metal atoms at the Al site and the atomic percentage of specific halogen atoms at the anion site are moderate, which can contribute to a better passivation effect.

[0051] The Nth perovskite subregion primarily contributes to resistance to water and oxygen erosion in the environment, requiring higher stability from the perovskite material and relatively lower thickness. Therefore, the Nth perovskite subregion exhibits the highest percentage of metal atoms at the A1 sites and the highest percentage of specific halogen atoms at the anion sites, and is relatively thin.

[0052] When N is greater than 2, the intermediate layer between the first perovskite sub-region 121 and the Nth perovskite sub-region plays a transitional role. It needs to balance the passivation effect and the resistance to water and oxygen erosion. Therefore, the thickness of the intermediate layer, the atomic percentage of metal atoms at the A1 site, and the atomic percentage of specific halogen atoms at the anion site are between the corresponding parameters of the first perovskite sub-region 121 and the Nth perovskite sub-region.

[0053] Reference Figure 3 In some embodiments, the surface perovskite region 12 includes a first perovskite sub-region 121, a second perovskite sub-region 122, and a third perovskite sub-region 123 disposed sequentially away from the bulk perovskite region 11, wherein: The thickness h1 of the first perovskite subregion 121 is 3 nm to 10 nm, the atomic percentage of metal atoms at the A1 site is 10% to 30%, and the atomic percentage of halogen atoms at the X1 site is 10% to 20%. The thickness h2 of the second perovskite subregion 122 is 2 nm to 10 nm, the atomic percentage of metal atoms at the A1 site is 30% to 50%, and the atomic percentage of halogen atoms at the X1 site is 20% to 30%. The thickness h3 of the third perovskite subregion 123 is 0.1 nm to 8 nm, the atomic percentage of metal atoms at the A1 site is 50% to 86%, and the atomic percentage of halogen atoms at the X1 site is 30% to 50%.

[0054] When the thicknesses of the first perovskite sub-region 121, the second perovskite sub-region 122, and the third perovskite sub-region 123, as well as the atomic percentage of metal atoms at the A1 site and the atomic percentage of specific halogen atoms at the X1 site of each layer, are within the aforementioned thickness range, defects in the surface perovskite region can be better passivated, while simultaneously enhancing the resistance of the surface perovskite region 12 to water and oxygen erosion. For example, the thickness h1 of the first perovskite sub-region 121 can be 3 nm, 5 nm, 7 nm, 9 nm, 10 nm, etc., the atomic percentage of metal atoms at the A1 site can be 10%, 15%, 20%, 25%, 30%, etc., and the atomic percentage of halogen atoms at the X1 site can be 10%, 12%, 14%, 16%, 18%, 20%, etc.; the thickness h2 of the second perovskite sub-region 122 can be 2 nm, 3 nm, 5 nm, 7 nm, 9 nm, 10 nm, etc., the atomic percentage of metal atoms at the A1 site is 30%, 35%, 40%, 45%, 50%, etc., and the atomic percentage of halogen atoms at the X1 site is 20%, 25%, 30%; the thickness h3 of the third perovskite sub-region 123 can be 0.1 nm, 2 nm, 3 nm, 5 nm, 7 nm, 8 nm, etc. The percentage of metal atoms at the A1 position can be 50%, 55%, 65%, 75%, 86%, etc., and the percentage of halogen atoms at the X1 position can be 30%, 35%, 40%, 45%, 50%, etc.

[0055] In some embodiments, the roughness of the side surface of the surface perovskite region 12 away from the bulk perovskite region 11 is less than 40 nm. By controlling the atomic percentage of metal atoms at the A1 site and the atomic percentage of specific halogen atoms at the X1 site of the surface perovskite, more metal atoms and specific halogen atoms are enriched on the side surface of the surface perovskite region 12 away from the bulk perovskite region 11, thus effectively reducing the surface roughness of the side surface of the surface perovskite region 12 to less than 40 nm.

[0056] It should be noted that the surface roughness of the surface perovskite region 12 away from the bulk perovskite region 11, such as the side surface, can be tested by atomic force microscopy (AFM).

[0057] In some embodiments, such as Figure 3 As shown, the thickness of the surface perovskite region 12 is H, where H ranges from 5 nm to 28 nm. This thickness of the surface perovskite region 12 can better resist water and oxygen erosion, thus improving the stability of the bulk perovskite region 11. For example, H can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 28 nm, etc.

[0058] Reference Figure 1 or Figure 2 In some embodiments, the surface perovskite region 12 is covered with a sealing layer 13 on the side opposite to the bulk perovskite region 11. The sealing layer 13 is made of one or more of silicon nitride, silicon oxynitride, and aluminum oxide. Silicon nitride, silicon oxynitride, and aluminum oxide can all form a sealing layer 13 with good water and oxygen barrier effects, thereby better sealing the perovskite layer 1 and preventing the perovskite layer 1 from contacting water and oxygen in the environment, thus reducing the possibility of the perovskite layer 1 coming into contact with water and oxygen.

[0059] Furthermore, referring to Figure 1 or Figure 2 The thickness d of the sealing layer 13 is 0.2 mm to 2 mm. Through the cooperation of the sealing layer 13 of the aforementioned thickness and the surface perovskite region 12, the overall stability of the perovskite layer 1 is significantly improved. For example, d can be 0.2 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc.

[0060] Furthermore, referring to Figure 1 or Figure 2 The sealing layer 13 can also cover the sides of other functional layers besides the perovskite layer, such as the electron transport layer, hole transport layer, and transparent conductive layer, to further reduce the impact of water and oxygen on other functional layers.

[0061] Reference Figure 4 In some embodiments, the perovskite layer 1 includes an active photoelectric conversion region 1a located at the center and an inactive photoelectric conversion region 1b located at the edge. The perovskite layer 1 satisfies at least one of the following conditions: (1) The area of ​​the active photoelectric conversion region 1a accounts for more than 90% of the total area of ​​the perovskite layer 1; (2) The width of the inactive photoelectric conversion region 1b is less than or equal to 2 mm; (3) The difference in fill factor between the active photoelectric conversion region 1a and the inactive photoelectric conversion region 1b is greater than or equal to 10%.

[0062] This application effectively controls the proportion of the active photoelectric conversion region 1a in the perovskite layer 1 by making the area of ​​the active photoelectric conversion region 1a account for more than 90% of the total area of ​​the perovskite layer 1, or making the width of the inactive photoelectric conversion region 1b less than or equal to 2 mm, or making the difference in fill factor between the active photoelectric conversion region 1a and the inactive photoelectric conversion region 1b greater than or equal to 10%. This results in a higher proportion of the active photoelectric conversion region 1a in the perovskite layer 1, thereby improving the photoelectric conversion efficiency of the final solar cell device. For example, in this application, the area of ​​the active photoelectric conversion region 1a can account for 90%, 92%, 94%, 96%, 98%, 99%, etc.; the width of the inactive photoelectric conversion region 1b can be 2 mm, 1 mm, 0.5 mm, 0.1 mm, etc.; and the difference in fill factor between the active photoelectric conversion region 1a and the inactive photoelectric conversion region 1b can be 10%, 15%, 20%, etc.

[0063] Furthermore, by cutting the perovskite layer 1, the inactive photoelectric conversion region 1b in the perovskite layer 1 can be effectively reduced.

[0064] Within the perovskite layer 1, the optical signal, thickness, and chemical composition at different locations can be measured to distinguish between the active photoelectric conversion region 1a and the inactive photoelectric conversion region 1b. Testing methods include photoluminescence (PL / PL mapping), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The active photoelectric conversion region 1a, located at the center, exhibits a strong optical signal, uniform thickness, and a more uniform chemical composition, closely approximating the ideal stoichiometry of the perovskite material. In contrast, the inactive photoelectric conversion region 1b at the edges shows a significantly weakened optical signal, uneven thickness, and uneven chemical composition. Furthermore, due to the migration and aggregation of halogen atoms, phase separation such as bromine-rich or iodine-rich phases may occur.

[0065] In some embodiments, the perovskite solar cell includes a perovskite single-junction solar cell or a perovskite tandem solar cell. The perovskite tandem solar cell includes any one of perovskite-silicon tandem solar cells, perovskite-copper indium gallium selenide tandem solar cells, and perovskite-organic tandem solar cells. The solution of this application can be applied to a variety of solar cells.

[0066] Furthermore, referring to Figure 2 Perovskite single-junction solar cells include the following structures: 2. Transparent conductive substrate; The first transport layer 3 is disposed on the transparent conductive substrate 2; The perovskite layer 1 is disposed on the side of the first transport layer 3 opposite to the transparent conductive substrate 2; A second transport layer 4 is also provided on the side of the perovskite layer 1 away from the transparent conductive substrate 2. One of the first transport layer 3 and the second transport layer 4 is an electron transport layer and the other is a hole transport layer. For example, the second transport layer 4 can be an electron transport layer and the first transport layer 3 can be a hole transport layer. A first electrode 5 is disposed on the side of the second transmission layer 4 away from the transparent conductive substrate 2. The first electrode 5 forms an ohmic contact with the second transmission layer 4. A second electrode 6 is disposed on the transparent conductive substrate 2. The transparent conductive substrate 2 forms an ohmic contact with the second electrode 6.

[0067] Furthermore, referring to Figure 1 Perovskite tandem solar cells include the following structures: The bottom cell 7 is any one of silicon bottom cell 7, copper indium gallium selenide bottom cell 7, and organic bottom cell 7; A carrier intermediate composite layer 8 is provided on the bottom battery 7; A first transport layer 3 is provided on the side of the intermediate recombination layer 8 away from the bottom cell 7; The perovskite layer 1 is disposed on the side of the first transport layer 3 away from the bottom cell 7; A second transport layer 4 is provided on the side of the perovskite layer 1 away from the bottom cell 7. One of the first transport layer 3 and the second transport layer 4 is an electron transport layer and the other is a hole transport layer. For example, the second transport layer 4 can be an electron transport layer and the first transport layer 3 can be a hole transport layer. A transparent conductive layer 9 is provided on the side of the second transmission layer 4 that is away from the bottom battery 7; A first electrode 5 is disposed on the transparent conductive layer 9, so that the first electrode 5 and the transparent conductive layer 9 form an ohmic contact.

[0068] Furthermore, in perovskite single-junction solar cells, the transparent conductive substrate 2 can be made of transparent conductive oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO). The transparent conductive oxides can be prepared by magnetron sputtering or atomic vapor deposition (ALD).

[0069] In perovskite tandem solar cells, both the intermediate carrier recombination layer 8 and the transparent conductive layer 9 can be made of transparent conductive oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO). These transparent conductive oxides can be prepared by magnetron sputtering or atomic vapor deposition (ALD). Furthermore, the thickness of the intermediate carrier recombination layer 8 is 2 nm to 30 nm, and the thickness of the transparent conductive layer 9 is 30 nm to 150 nm.

[0070] The bottom battery 7 also includes a second electrode 6 disposed opposite to the first electrode 5. The first electrode 5 and the second electrode 6 are both made of metallic materials with good electrical conductivity, such as silver and copper, and the first electrode 5 and the second electrode 6 can be prepared by physical vapor deposition (PVD).

[0071] The bottom cell 7 includes a heterojunction bottom cell 7, a passivated contact bottom cell 7, etc.; furthermore, the bottom cell 7 can be a commercially available heterojunction cell. When the bottom cell 7 is a heterojunction bottom cell 7, the surface of the heterojunction bottom cell 7 has a textured structure, and the height of the textured structure can be 1.5μm, 2μm, etc.

[0072] Furthermore, the hole transport layer in the perovskite solar cell structure is mainly responsible for hole collection and transport, and requires high hole mobility. It can be nickel oxide, and the main preparation methods of nickel oxide are solution spin coating, magnetron sputtering, vacuum deposition, etc. The material of the hole transport layer can also be 2,2',7,7'-tetratetra(N,N-di-p-tolyl)amino-9,9-spirodifluorene (Spiro-TTB), etc.

[0073] The surface of the hole transport layer can be provided with a hole passivation layer. The material of the hole passivation layer can be a self-assembled monomolecular material, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] or other materials with high hole mobility. The self-assembled monomolecular material can be [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), 4-(9H-carbazole-9-yl)butylphosphonic acid (4PACz), etc.

[0074] Secondly, embodiments of this application provide a method for preparing a perovskite solar cell.

[0075] A method for fabricating a perovskite solar cell, referring to... Figure 5 This includes the following steps: Provide such as Figure 5 The perovskite initial layer 1A shown in Figure (a) is made of organic-inorganic perovskite. Atomic diffusion treatment was performed on the side of the initial perovskite layer 1A to form a structure like... Figure 5 Figure (b) shows a perovskite layer 1, which includes a central bulk perovskite region 11 and surface perovskite regions 12 located on the sides of the bulk perovskite region 11. The atoms include metal atoms and halogen atoms, such that the surface perovskite of the surface perovskite region 12 and the bulk perovskite of the bulk perovskite region 11 satisfy at least one of the following relationships: (1) The percentage of metal atoms in the surface perovskite region 12 at the A1 position is a1, and the percentage of metal atoms in the bulk perovskite region 11 at the A2 position is a2. a1 is greater than a2. (2) The percentage of halogen atoms at position X1 in the surface perovskite region 12 is x1, and the percentage of halogen atoms at position X2 in the bulk perovskite region 11 is x2. The halogen atoms are chlorine atoms and / or bromine atoms, and x1 is greater than x2. The A1 site is the A cation site of the surface perovskite in the surface perovskite region 12, the A2 site is the A cation site of the bulk perovskite in the bulk perovskite region 11, the X1 site is the anion site of the surface perovskite in the surface perovskite region 12, and the X2 site is the anion site of the bulk perovskite in the bulk perovskite region 11.

[0076] It should be noted that the initial perovskite layer 1A of this application is the initial layer before atomic diffusion treatment. The initial perovskite layer 1A has a relatively uniform composition distribution and does not form a bulk perovskite region 11 and a surface perovskite region 12 where the atomic percentage of metal atoms at the A cation sites or the atomic percentage of halogen atoms at the anion sites differs significantly.

[0077] By diffusion treatment of metal atoms and / or specific halogen atoms into the initial perovskite layer 1A, a perovskite layer 1 with a surface perovskite region 12 and a bulk perovskite region 11 can be formed. After the diffusion of metal atoms and / or specific halogen atoms, the content of metal atoms and / or specific halogen atoms in the surface perovskite region 12 is significantly increased compared to the bulk perovskite region 11. The bulk perovskite region 11 is largely unaffected by the diffusion of metal atoms and / or specific halogen atoms, maintaining a relatively uniform compositional distribution.

[0078] The diffusion of metal atoms and / or specific halogen atoms can effectively passivate the metal dangling bonds or halogen dangling bonds of the surface perovskite region 12, thereby improving the passivation quality of the surface perovskite region 12. Furthermore, after the diffusion of metal atoms and / or specific halogen atoms, the binding ability of the surface perovskite with water and oxygen decreases, which reduces the surface perovskite's ability to react with water and oxygen, thus promoting the overall stability of the perovskite layer 1.

[0079] In some embodiments, before the step of providing the initial perovskite layer 1A through atomic diffusion treatment on its sides, and after the step of providing the initial perovskite layer 1A, the preparation method further includes: cutting the sides of the initial perovskite layer 1A to remove the inactive photoelectric conversion region 1b located at the circumferential edge of the initial perovskite layer 1A, retaining the active photoelectric conversion region 1a located at the center of the initial perovskite layer 1A. The width of the inactive photoelectric conversion region 1b removed by the cutting process is 0.2 mm to 10 mm, so as to facilitate the subsequent formation of... Figure 4The area ratio of the inactive photoelectric conversion region 1b in the perovskite layer 1 shown is significantly low. For example, the width of the inactive photoelectric conversion region 1b removed by the cutting process can be 0.2 mm, 2 mm, 6 mm, 10 mm, etc.

[0080] Inhomogeneous perovskite deposition is prone to occur in the edge deposition region on the side of the perovskite initial layer 1A, especially when preparing a large-area perovskite initial layer 1A (e.g., enlarging the area of ​​the perovskite initial layer 1A to 105 mm x 210 mm), resulting in inhomogeneous perovskite composition. Removing the non-uniformly composed edge deposition region through cutting can effectively reduce edge defects in the perovskite initial layer 1A and decrease carrier recombination.

[0081] Furthermore, the cutting process can be laser cutting. Laser cutting can employ an infrared laser with a power of 5W to 200W, which causes minimal damage to the bottom cell 7 (especially the crystalline silicon bottom cell 7). After cutting, the surface roughness of the perovskite initial layer 1A is less than 100 nm (characterized by atomic force microscopy).

[0082] After the cutting process, the inactive photoelectric conversion region 1b in the perovskite layer 1 is effectively reduced, while the proportion of the active photoelectric conversion region 1a is increased, which can further improve the photoelectric conversion efficiency of the final solar cell device.

[0083] In some embodiments, the step of providing the perovskite initial layer 1A is: fabricating a perovskite top cell with the perovskite initial layer 1A. Regarding the step of performing atomic diffusion treatment on the side surface of the perovskite initial layer 1A, after the perovskite top cell is fabricated, both the upper and lower surfaces of the perovskite initial layer 1A are covered by functional films, but the side surface is exposed, and this side surface is not a weak point susceptible to water and oxygen erosion. This application performs atomic diffusion treatment on this exposed side surface, which helps to improve the resistance of the surface perovskite region 12 to water and oxygen erosion, thereby improving the stability of the side surface of the perovskite layer 1 in this application.

[0084] Furthermore, the cutting process can be carried out after the perovskite top cell is fabricated. When cutting away the inactive photoelectric conversion region 1b of the perovskite layer 1, a portion of the functional layers with a larger area than the perovskite layer 1 can also be removed simultaneously during the cutting process, such as self-assembled molecular layers, passivation layers, electron transport layers, etc.

[0085] In some embodiments, a protective adhesive layer is applied to the top surface of the perovskite top cell before the atomic diffusion treatment of the side surface of the initial perovskite layer 1A, and the protective adhesive layer is removed after the atomic diffusion treatment of the side surface of the initial perovskite layer 1A, wherein: The thickness of the protective adhesive layer is 2 mm to 15 mm, and / or the protective adhesive layer includes one or a combination of two of polymethyl methacrylate and polyimide.

[0086] Applying a protective adhesive layer to the top surface of the perovskite top cell effectively blocks the diffusion of metal halides to the top surface, preventing them from diffusing inwards from the top surface. For example, the thickness of the protective adhesive layer can be 2 mm, 6 mm, 12 mm, 15 mm, etc.

[0087] In some embodiments, the step of performing atomic diffusion treatment on the side of the initial perovskite layer 1A includes: depositing a metal halide layer with a thickness of 5 nm to 28 nm on the side of the initial perovskite layer 1A, and annealing it at 100°C to 150°C for 1 min to 10 min, so that the metal halide in the metal halide layer diffuses into the initial perovskite layer 1A to obtain a surface perovskite region 12, wherein the percentage of metal atoms at the A1 site in the surface perovskite region 12 increases continuously in a gradient along the direction away from the bulk perovskite region 11. The methods for depositing metal halide layers include any one of vapor deposition, reactive plasma deposition, physical vapor deposition, and atomic layer deposition. Metal halides include one or more combinations of CsCl, CsBr, RbCl, RbBr, KCl, KBr, PbCl2, and PbBr2.

[0088] It should be noted that the perovskite initial layer 1A in this application is the film layer before atomic diffusion treatment. The perovskite initial layer 1A can be a film layer after cutting, and the side of the atomic diffusion treatment is the side of the perovskite initial layer 1A after cutting; and the perovskite initial layer 1A can also be a film layer without cutting, and the side of the atomic diffusion treatment is the side of the perovskite initial layer 1A without cutting.

[0089] In the surface perovskite region 12 formed by the above method, the content of metal atoms in the surface perovskite near the bulk perovskite region 11 is relatively low, which can better passivate the defects of the surface perovskite and is conducive to the transport of charge carriers. On the other hand, the concentration of metal atoms in the surface perovskite far from the bulk perovskite region 11 is high, which is conducive to improving the water and oxygen resistance of the surface perovskite.

[0090] For example, the thickness of the metal halide layer deposited on the side of the perovskite initial layer 1A can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 28 nm, etc. The annealing temperature can be 100℃, 120℃, 130℃, 150℃, etc. The annealing time can be 1 min, 4 min, 7 min, 10 min, etc.

[0091] In some embodiments, the step of performing atomic diffusion treatment on the sidewalls of the perovskite initial layer 1A includes: Deposition of metal halide sublayer: The first metal halide sublayer is deposited on the side of the initial perovskite layer 1A; Annealing treatment: Perform a first annealing treatment to allow the metal halide of the first metal halide sublayer to diffuse into the perovskite initial layer 1A; The metal halide sublayer deposition and annealing process is repeated at least once to obtain the surface perovskite region 12, wherein the percentage of metal atoms at the A1 site in the surface perovskite region 12 increases continuously in a gradient away from the bulk perovskite region 11. The methods for depositing metal halide sublayers include any one of the following: vapor deposition, reactive plasma deposition, physical vapor deposition, and atomic layer deposition. Metal halides include one or more combinations of CsCl, CsBr, RbCl, RbBr, KCl, KBr, PbCl2, and PbBr2.

[0092] By segmenting the deposition of metal halide sublayers, perovskite subregions with better gradient differences can be designed in the surface perovskite region 12. This is more conducive to forming a surface perovskite with significantly increased metal atom content and specific halogen atom content on the side away from the bulk perovskite region 11, thereby improving the surface perovskite's resistance to water and oxygen erosion. Furthermore, it ensures that the metal atom content of the surface perovskite near the bulk perovskite region 11 is kept at a low level, thereby improving the carrier transport effect.

[0093] In some embodiments, during the steps of cyclically depositing and annealing the metal halide sublayer: The thickness of the first deposited metal halide sublayer is less than the thickness of the later deposited metal halide sublayer; The temperature of the annealing process performed earlier is higher than the temperature of the annealing process performed later. The time required for the earlier annealing process is less than the time required for the later annealing process.

[0094] By coordinating the above process parameters, the thickness of the pre-deposited metal halide sublayer is made thinner, the annealing temperature is higher, and the annealing time is shorter, which is conducive to the diffusion of an appropriate amount of metal halide to the surface perovskite region 12, so as to fully achieve passivation, while preventing it from diffusing into the interior of the perovskite body phase. With increased thickness of the subsequently deposited metal halide sublayer, lower annealing temperatures and longer annealing times are required. On the one hand, it can reduce the risk of metal halides diffusing into the perovskite bulk phase. On the other hand, it is beneficial for metal atoms and halogen atoms to accumulate more in the surface perovskite region 12, which is far away from the bulk perovskite layer 1, thereby further enhancing the resistance of the surface perovskite region 12 to water and oxygen erosion. Furthermore, the lower annealing temperature and longer annealing time are beneficial to improving the perovskite crystal quality of the surface perovskite region 12 and further passivating the defects of the surface perovskite region 12.

[0095] In some embodiments, the metal halide deposition and annealing steps are repeated three times, wherein: The thickness of the first metal halide sublayer is 3 nm to 10 nm, and the first annealing treatment is annealing at 130℃ to 150℃ for 1 min to 3 min; The thickness of the second metal halide sublayer is 2 nm to 10 nm, and the second annealing treatment is annealing at 100℃ to 130℃ for 2 min to 5 min. The thickness of the third metal halide sublayer is 0.1 nm to 8 nm, and the third annealing treatment is annealing at 25℃ to 100℃ for 5 min to 20 min; After performing atomic diffusion treatment on the side of the initial perovskite layer 1A, the resulting surface perovskite region 12 includes a first perovskite sub-region 121, a second perovskite sub-region 122, and a third perovskite sub-region 123 arranged sequentially away from the bulk perovskite region 11, wherein: The thickness of the first perovskite subregion 121 is 3 nm to 10 nm, the atomic percentage of metal atoms at the A1 site is 10% to 30%, and the atomic percentage of halogen atoms at the X1 site is 10% to 20%. The thickness of the second perovskite subregion 122 is 2 nm to 10 nm, the atomic percentage of metal atoms at the A1 site is 30% to 50%, and the atomic percentage of halogen atoms at the X1 site is 20% to 30%. The thickness of the third perovskite subregion 123 is 0.1 nm to 8 nm, the atomic percentage of metal atoms at the A1 site is 50% to 86%, and the atomic percentage of halogen atoms at the X1 site is 30% to 50%.

[0096] The first metal halide sublayer is the thinnest and has a higher annealing temperature, which promotes the full diffusion of metal halides, thereby effectively passivating the dangling bonds in the surface perovskite region 12. Subsequently, the thickness of the second and third metal halide sublayers increases sequentially, while the annealing temperatures decrease sequentially, which slows down the diffusion of metal halides and creates a significant gradient difference in metal halides in the perovskite region 11, far from the bulk phase. This is beneficial for the formation of a perovskite phase with a significant increase in metal atoms or specific halogen atoms in the surface perovskite region 12, thus making the surface perovskite in the region far from the bulk phase more stable and more effectively resistant to water and oxygen erosion.

[0097] In some embodiments, after the atomic diffusion process, a sealing layer 13 is deposited on the side of the perovskite layer 1, such that the sealing layer 13 covers the surface perovskite region 12 away from the surface of the bulk perovskite region 11.

[0098] The sealing layer 13 can physically block water and oxygen, thereby reducing the possibility of the surface perovskite region 12 coming into contact with water and oxygen, and further improving the overall stability of the perovskite layer 1.

[0099] Thirdly, embodiments of this application provide a photovoltaic module.

[0100] A photovoltaic module includes a perovskite solar cell as mentioned in the first aspect or a perovskite solar cell prepared by the preparation method mentioned in the second aspect.

[0101] The technical solution of this application will be further described below with reference to more specific embodiments.

[0102] Example 1 This application provides a perovskite solar cell, which includes a heterojunction bottom cell and a perovskite top cell disposed on the heterojunction bottom cell. The perovskite top cell includes: The intermediate recombination layer of charge carriers is stacked on the heterojunction bottom cell and is made of indium zinc oxide with a thickness of 15 nm. Hole transport layer, stacked on the side of the intermediate carrier recombination layer away from the heterojunction bottom cell, is made of nickel oxide and has a thickness of 15 nm. Hole modification layer, stacked on the side of hole transport layer away from heterojunction bottom cell, is made of 4PACz and is a single-molecule self-assembled layer. A perovskite layer, stacked on the side of the hole-modifying layer away from the heterojunction base cell, has a thickness of 850 nm. The preparation method of the perovskite layer includes the following steps: First, a lead iodide framework layer was prepared by vapor deposition: PbI2, CsBr and RbBr were co-deposited using a vacuum thermal evaporation coating instrument to obtain a lead iodide framework layer. The evaporation ratio of PbI2, CsBr and RbBr was 10:1:1, and the thickness of the lead iodide framework layer was 550 nm. FAI, FABr, MAI and MACl were dissolved in isopropanol in a molar ratio of 50:30:10:10 to prepare an organic cationic solution, which was then coated onto the lead iodide framework layer by solution method, and finally annealed to obtain a perovskite layer. A passivation layer, stacked on the side of the perovskite layer away from the heterojunction bottom cell, is made of LiF and has a thickness of 2 nm. An electron transport layer is stacked on the side of the passivation layer away from the heterojunction bottom cell. The material is C60 and the thickness is 20nm. A buffer layer, stacked on the side of the electron transport layer away from the heterojunction bottom cell, is made of tin oxide and has a thickness of 20 nm. A transparent conductive layer, stacked on the side of the electron transport layer away from the heterojunction bottom cell, is made of indium tin oxide and has a thickness of 80 nm. The first electrode is patterned on the side of the transparent conductive layer away from the heterojunction bottom cell, and is made of silver with a thickness of 200 nm. An antireflection layer is disposed on the side of the transparent conductive layer away from the heterojunction bottom cell and in the area where the first electrode is not disposed. The material is LiF and the thickness is 110 nm. After the solar cell with the above structure is fabricated, a cutting process is performed: an infrared laser with a power of 100 W is used to cut the side of the perovskite layer to remove the inactive photoelectric conversion region at the circumferential edge and retain the active photoelectric conversion region. After the cutting process, the width of the inactive photoelectric conversion region is less than or equal to 2 mm. A protective adhesive layer with a thickness of 2 mm and made of polymethyl methacrylate was applied to the top surface of the perovskite top cell and annealed at 80°C for 5 min to ensure full and tight contact. Atomic diffusion treatment is performed: the perovskite layer before metal halide vapor deposition is used as the initial perovskite layer. The solar cell is placed in the vapor deposition apparatus, and a 5 nm CsCl layer is deposited on the side of the initial perovskite layer. The layer is annealed at 150 °C for 1 min. Then, a 7 nm CsCl layer is deposited on the side of the initial perovskite layer. The layer is annealed at 130 °C for 2 min. Then, an 8 nm CsCl layer is deposited on the side of the initial perovskite layer. The layer is annealed at 100 °C for 5 min to obtain the perovskite layer. The perovskite layer includes the bulk perovskite region and the surface perovskite region located on the side of the bulk perovskite region with a compositional gradient diffusion. Finally, remove the protective adhesive layer.

[0103] Example 2 This application provides a perovskite solar cell, which differs from Example 1 in that PbCl2 is used instead of CsCl in the atomic diffusion process, while the rest remains the same as Example 1.

[0104] Example 3 This application provides a perovskite solar cell, which differs from Example 1 in that: after atomic diffusion treatment and before removing the protective adhesive layer, a sealing layer is deposited: a silicon nitride layer with a thickness of 0.5 mm is evaporated onto the side of the perovskite layer and annealed at 100°C for 5 min to increase the density of the silicon nitride layer. The roughness of the silicon nitride layer is greater than 150 nm, and the rest is consistent with Example 1.

[0105] Comparative Example 1 This application provides a perovskite solar cell as a comparative example. The difference between this cell and Example 1 is that the steps of covering the protective layer, atomic diffusion treatment, and removing the protective adhesive layer are omitted. The rest is the same as Example 1.

[0106] Experiment 1 Compositional testing of perovskite layers The perovskite layer was etched and tested using XPS cluster mode to detect the changes in the atomic percentages of Cs and Cl at different depths in the perovskite cross-section.

[0107] The percentage of Cs atoms at the A site and / or the percentage of Cl atoms at the X site in the surface perovskite region differs at different depths. Therefore, the percentage of Cs atoms at the A site on the surface of the surface perovskite region away from the bulk perovskite region (i.e., the outermost surface) is denoted as a1, where a1 is the percentage of Cs atoms at the A site when the etching time is 0. Similarly, the percentage of Cl atoms at the X site on the surface of the surface perovskite region away from the bulk perovskite region (i.e., the outermost surface) is denoted as x1, where x1 is the percentage of Cl atoms at the A site when the etching time is 0.

[0108] Correspondingly, due to the good uniformity of the atomic percentages of Cs atoms at the A-site and Cl atoms at the X-site in the bulk perovskite region, the proportions at different depths are basically consistent. Therefore, as the etching time increases, the atomic percentages of Cs atoms at the A-site and Cl atoms at the X-site do not change significantly and remain stable overall. This stable phase can be considered to correspond to the bulk perovskite region, and the atomic percentage of Cs atoms at the A-site in the bulk perovskite region can be denoted as a2, and the atomic percentage of Cl atoms at the X-site as x2.

[0109] Experiment 2 Electrical performance testing of perovskite solar cells The electrical performance of perovskite solar cells was tested using the Wavelabs solar simulator under the following conditions: AM1.5, 1000 W / m. 2 The test environment temperature was 25℃. Before the test, the intensity of sunlight simulated by the light source was calibrated using a standard silicon cell, and the photoelectric conversion efficiency (Eff) of the solar cell was recorded.

[0110] Experiment 3 Stability testing of perovskite solar cells Test conditions: According to the IEC 62891:2020 international standard, a bias voltage (the magnitude of the bias voltage is Vmpp of the device) was applied to the perovskite solar cell and it was placed under a standard AM1.5G solar irradiance (1000W / m²). 2 The test was conducted under the following conditions (tracking current, efficiency, and power) for a continuous testing time of 500 h. The initial maximum power output of the solar cell was denoted as MPPT0, and the maximum power output of the solar cell at the 500th h was denoted as MPPT1 (the test time was 500 h). The ratio of MPPT1 to MPPT0 was the retention ratio of the initial power at the maximum power point of the solar cell at 500 h, denoted as d.

[0111] The test results of Experiments 1 to 3 are shown in Table 1. The XPS curves for the atomic percentages of Cs atoms at the A-site and Cl atoms at the X-site in Example 1 are shown in Table 1. Figure 6 , Figure 7 .

[0112] Table 1

[0113] pass Figure 6 , Figure 7 It can be seen that during the etching time range of 0 s to 100 s, the atomic percentage of Cs at the A site and the atomic percentage of Cl at the X site decrease with increasing etching time. This indicates that the atomic percentages of Cs at the A site and Cl at the X site in the surface perovskite region decrease along the direction closer to the bulk perovskite region. Furthermore, when the etching time exceeds 100 s, the atomic percentages of Cs at the A site and Cl at the X site do not change significantly, indicating that the atomic percentages of Cs at the A site and Cl at the X site in the bulk perovskite region remain stable.

[0114] A comparison of the data from Example 1 and Comparative Example 1 shows that increasing the atomic percentage of Cs at the A site and the atomic percentage of Cl at the X site in the surface perovskite region can effectively improve the photoelectric conversion efficiency and stability of perovskite solar cells.

[0115] The data from Examples 1, 2, and Comparative Example 1 show that in Example 2, PbCl2 is used, where lead atoms act as B-site cations, having a relatively small impact on A-site cations. Therefore, the values ​​of a1 and a2 in Table 1 do not change significantly. Using PbCl2 only increases the percentage of Cl atoms at the X-site in the surface perovskite region. Compared to Comparative Example 1, the perovskite solar cell in Example 2 also shows a significant improvement in photoelectric conversion efficiency and stability. However, compared to Example 1, the improvement in both photoelectric conversion efficiency and stability in Example 2 is less pronounced.

[0116] A comparison of Examples 1 and 3 shows that by setting a sealing layer on the side surface of the perovskite layer, the stability of the perovskite solar cell can be further improved.

[0117] The technical solutions disclosed in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A perovskite solar cell, characterized in that, The perovskite layer comprises an organic-inorganic perovskite layer, wherein the perovskite layer includes a central bulk perovskite region and surface perovskite regions located on the sides of the bulk perovskite region. Both the surface perovskite regions and the bulk perovskite regions contain metal atoms and halogen atoms. At least one of the following relationships must be satisfied between the surface perovskite in the surface perovskite regions and the bulk perovskite in the bulk perovskite regions: (1) The atomic percentage of the metal atoms in the surface perovskite region at the A1 position is a1, and the atomic percentage of the metal atoms in the bulk perovskite region at the A2 position is a2, wherein a1 is greater than a2; (2) The percentage of halogen atoms at position X1 in the surface perovskite region is x1, the percentage of halogen atoms at position X2 in the bulk perovskite region is x2, the halogen atoms are chlorine atoms and / or bromine atoms, and x1 is greater than x2. Wherein, the A1 site is the A cation site of the surface perovskite in the surface perovskite region, the A2 site is the A cation site of the bulk perovskite in the bulk perovskite region, the X1 site is the anion site of the surface perovskite in the surface perovskite region, and the X2 site is the anion site of the bulk perovskite in the bulk perovskite region.

2. The perovskite solar cell according to claim 1, characterized in that, a1 is 10%~86%, and a2 is 2%~9%; And / or, x1 is 10%~50%, and x2 is 2%~9%.

3. The perovskite solar cell according to claim 1, characterized in that, The metal atoms include one or more combinations of Li, Na, K, Rb, Cs, Ag, Au, Cu, Tl, Pb, Sn, Ge, Mg, Ca, Sr, Ba, Zn, Cd, Hg, Ni, Co, Fe, Mn, Bi, Sb, In, Ga, Al, Cr, and rare earth metals.

4. The perovskite solar cell according to claim 1, characterized in that, Along the direction from the bulk perovskite region to the surface perovskite region, the atomic percentage of the metal atoms in the surface perovskite region at the Al sites increases, and / or, the atomic percentage of the halogen atoms in the surface perovskite region at the anion sites increases.

5. The perovskite solar cell according to claim 4, characterized in that, Along the direction from the bulk perovskite region to the surface perovskite region, the atomic percentage of the metal atoms in the surface perovskite region at the Al sites increases in a gradient, and / or, the atomic percentage of the halogen atoms in the surface perovskite region at the anion sites increases in a gradient. The surface perovskite region has a first perovskite sub-region to an Nth perovskite sub-region arranged sequentially away from the bulk perovskite region. Along the direction from the bulk perovskite region to the surface perovskite region, the thickness of the first perovskite sub-region to the Nth perovskite sub-region decreases layer by layer, where N is a positive integer greater than or equal to 2.

6. The perovskite solar cell according to claim 5, characterized in that, The surface perovskite region includes a first perovskite sub-region, a second perovskite sub-region, and a third perovskite sub-region arranged sequentially away from the bulk perovskite region, wherein: The thickness of the first perovskite sub-region is 3 nm to 10 nm, the atomic percentage of the metal atoms at the A1 site is 10% to 30%, and the atomic percentage of the halogen atoms at the X1 site is 10% to 20%. The thickness of the second perovskite sub-region is 2 nm to 10 nm, the atomic percentage of the metal atoms at the A1 site is 30% to 50%, and the atomic percentage of the halogen atoms at the X1 site is 20% to 30%. The thickness of the third perovskite sub-region is 0.1 nm to 8 nm, the atomic percentage of the metal atoms at the A1 site is 50% to 86%, and the atomic percentage of the halogen atoms at the X1 site is 30% to 50%.

7. The perovskite solar cell according to claim 1, characterized in that, The roughness of the side of the surface perovskite region away from the bulk perovskite region is less than 40 nm. And / or, the thickness of the surface perovskite region is 5 nm to 28 nm.

8. The perovskite solar cell according to claim 1, characterized in that, The surface perovskite region is covered with a sealing layer on the side facing away from the bulk perovskite region, wherein: The material of the sealing layer includes one or more combinations of silicon nitride, silicon oxynitride and aluminum oxide, and / or the thickness of the sealing layer is 0.2 mm to 2 mm.

9. The perovskite solar cell according to claim 1, characterized in that, The perovskite layer comprises an active photoelectric conversion region at the center and an inactive photoelectric conversion region at the edge, and the perovskite layer satisfies at least one of the following conditions: (1) The area of ​​the active photoelectric conversion region accounts for more than 90% of the total area of ​​the perovskite layer; (2) The width of the inactive photoelectric conversion region is less than or equal to 2 mm; (3) The difference in fill factor between the active photoelectric conversion region and the inactive photoelectric conversion region is greater than or equal to 10%.

10. The perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell includes a perovskite single-junction solar cell or a perovskite tandem solar cell, and the perovskite tandem solar cell includes any one of perovskite-silicon tandem solar cell, perovskite-copper indium gallium selenide tandem solar cell, and perovskite-organic tandem solar cell. The perovskite single-junction solar cell includes the following structure: Transparent conductive substrate; A first transport layer disposed on the transparent conductive substrate; The perovskite layer is disposed on the side of the first transport layer opposite to the transparent conductive substrate; A second transport layer is also provided on the side of the perovskite layer away from the transparent conductive substrate. One of the first transport layer and the second transport layer is an electron transport layer, and the other is a hole transport layer. A first electrode is disposed on the side of the second transport layer away from the transparent conductive substrate, and the first electrode forms an ohmic contact with the second transport layer. A second electrode is disposed on the transparent conductive substrate, and the transparent conductive substrate forms an ohmic contact with the second electrode. The perovskite tandem solar cell includes the following structure: The bottom battery is any one of silicon bottom battery, copper indium gallium selenide bottom battery, and organic bottom battery; The bottom battery is provided with a carrier intermediate composite layer; A first transport layer is provided on the side of the charge carrier intermediate composite layer opposite to the bottom battery; The perovskite layer is disposed on the side of the first transport layer opposite to the bottom cell; A second transport layer is provided on the side of the perovskite layer opposite to the bottom cell. One of the first transport layer and the second transport layer is an electron transport layer, and the other is a hole transport layer. A transparent conductive layer is provided on the side of the second transmission layer that is away from the bottom battery; A first electrode is disposed on the transparent conductive layer, so that the first electrode and the transparent conductive layer form an ohmic contact.

11. A method for preparing a perovskite solar cell, characterized in that, Includes the following steps: A perovskite initial layer is provided, wherein the material of the perovskite initial layer is an organic-inorganic perovskite; Atom diffusion is performed on the sides of the initial perovskite layer to form a perovskite layer. The perovskite layer includes a central bulk perovskite region and surface perovskite regions located on the sides of the bulk perovskite region. The atoms include metal atoms and halogen atoms, such that the surface perovskite in the surface perovskite regions and the bulk perovskite in the bulk perovskite regions satisfy at least one of the following relationships: (1) The atomic percentage of the metal atoms in the surface perovskite region at the A1 position is a1, and the atomic percentage of the metal atoms in the bulk perovskite region at the A2 position is a2, wherein a1 is greater than a2; (2) The percentage of halogen atoms at position X1 in the surface perovskite region is x1, the percentage of halogen atoms at position X2 in the bulk perovskite region is x2, the halogen atoms are chlorine atoms and / or bromine atoms, and x1 is greater than x2. The A1 site is the A cation site of the surface perovskite in the surface perovskite region, the A2 site is the A cation site of the bulk perovskite in the bulk perovskite region, the X1 site is the anion site of the surface perovskite in the surface perovskite region, and the X2 site is the anion site of the bulk perovskite in the bulk perovskite region.

12. The method for preparing a perovskite solar cell according to claim 11, characterized in that, Before the step of performing atomic diffusion treatment on the side of the perovskite initial layer and after the step of providing the perovskite initial layer, the preparation method further includes: cutting the side of the perovskite initial layer to remove the inactive photoelectric conversion region located at the circumferential edge of the perovskite initial layer, while retaining the active photoelectric conversion region located at the center of the perovskite initial layer, wherein the width of the inactive photoelectric conversion region removed by the cutting process is 0.2 mm to 10 mm.

13. The method for preparing a perovskite solar cell according to claim 11, characterized in that, The step of providing the initial perovskite layer is as follows: preparing a perovskite top cell with the initial perovskite layer.

14. The method for preparing a perovskite solar cell according to claim 13, characterized in that, Before the step of performing atomic diffusion treatment on the sides of the initial perovskite layer, a protective adhesive layer is applied to the top surface of the perovskite top cell. After the step of performing atomic diffusion treatment on the sides of the initial perovskite layer, the protective adhesive layer is removed, wherein: The thickness of the protective adhesive layer is 2 mm to 15 mm, and / or the protective adhesive layer includes one or a combination of two of polymethyl methacrylate and polyimide.

15. The method for preparing a perovskite solar cell according to claim 11, characterized in that, The step of performing atomic diffusion treatment on the side of the initial perovskite layer includes: depositing a metal halide layer with a thickness of 5 nm to 28 nm on the side of the initial perovskite layer, annealing it at 100°C to 150°C for 1 min to 10 min, so that the metal halide in the metal halide layer diffuses into the initial perovskite layer to obtain the surface perovskite region, wherein the percentage of metal atoms at the A1 site in the surface perovskite region increases continuously in a gradient along the direction away from the bulk perovskite region; The method of depositing the metal halide layer includes any one of vapor deposition, reactive plasma deposition, physical vapor deposition, and atomic layer deposition. The metal halide includes one or more combinations of CsCl, CsBr, RbCl, RbBr, KCl, KBr, PbCl2, and PbBr2.

16. The method for preparing a perovskite solar cell according to claim 11, characterized in that, The step of performing atomic diffusion treatment on the side surface of the initial perovskite layer includes: Deposition of metal halide sublayer: A first metal halide sublayer is deposited on the side of the initial perovskite layer; Annealing treatment: Perform a first annealing treatment to allow the metal halide of the first metal halide sublayer to diffuse into the perovskite initial layer; The steps of depositing the metal halide sublayer and the annealing treatment are repeated at least once to obtain the surface perovskite region, wherein the atomic percentage of the metal atoms at the A1 site in the surface perovskite region increases continuously in a gradient away from the bulk perovskite region. The method of depositing the metal halide sublayer includes any one of vapor deposition, reactive plasma deposition, physical vapor deposition, and atomic layer deposition. The metal halide includes one or more combinations of CsCl, CsBr, RbCl, RbBr, KCl, KBr, PbCl2, and PbBr2.

17. The method for preparing a perovskite solar cell according to claim 16, characterized in that, In the steps of depositing the metal halide sublayer and the annealing treatment in the cycle: The thickness of the metal halide sublayer deposited earlier is less than the thickness of the metal halide sublayer deposited later; The temperature of the annealing process performed earlier is higher than the temperature of the annealing process performed later; The time taken for the annealing process performed earlier is less than the time taken for the annealing process performed later.

18. The method for preparing a perovskite solar cell according to claim 17, characterized in that, The deposition of the metal halide and the annealing process are repeated three times, wherein: The thickness of the first metal halide sublayer is 3 nm to 10 nm, and the first annealing treatment is annealing at 130°C to 150°C for 1 min to 3 min; The thickness of the second metal halide sublayer is 2 nm to 10 nm, and the second annealing treatment is annealing at 100℃ to 130℃ for 2 min to 5 min. The thickness of the third metal halide sublayer is 0.1 nm to 8 nm, and the third annealing treatment is annealing at 25℃ to 100℃ for 5 min to 20 min; After the step of performing atomic diffusion treatment on the side of the initial perovskite layer, the resulting surface perovskite region includes a first perovskite sub-region, a second perovskite sub-region, and a third perovskite sub-region arranged sequentially away from the bulk perovskite region, wherein: The thickness of the first perovskite sub-region is 3 nm to 10 nm, the atomic percentage of the metal atoms at the A1 site is 10% to 30%, and the atomic percentage of the halogen atoms at the X1 site is 10% to 20%. The thickness of the second perovskite sub-region is 2 nm to 10 nm, the atomic percentage of the metal atoms at the A1 site is 30% to 50%, and the atomic percentage of the halogen atoms at the X1 site is 20% to 30%. The thickness of the third perovskite sub-region is 0.1 nm to 8 nm, the atomic percentage of the metal atoms at the A1 site is 50% to 86%, and the atomic percentage of the halogen atoms at the X1 site is 30% to 50%.

19. The method for preparing a perovskite solar cell according to claim 11, characterized in that, Following the atomic diffusion treatment step, a sealing layer is deposited on the side of the perovskite layer, such that the sealing layer covers the surface of the surface perovskite region away from the bulk perovskite region.

20. A photovoltaic module, characterized in that, This includes perovskite solar cells as described in any one of claims 1-10 or perovskite solar cells prepared by the preparation method as described in any one of claims 11-19.

Images