Method for preparing perovskite layer, tandem solar cell, and preparation method

Abstract

The present application discloses a method for preparing a perovskite layer, a tandem solar cell, and a preparation method. The method for preparing a perovskite layer comprises the following steps: S1, providing a cell substrate (1), and co-evaporating lead iodide and cesium bromide onto a surface of the cell substrate by a co-evaporation method to obtain a lead iodide / cesium bromide thin film (L1); S2, depositing an ion diffusion material on the surface of the lead iodide / cesium bromide thin film in S1 by a vapor deposition method to obtain an ion diffusion layer (L2); and S3, applying an ammonium salt precursor solution on the surface of the ion diffusion layer in S2 by a spin coating method, and performing annealing to obtain a perovskite layer (302).

Description

Perovskite layer preparation method, laminated solar cell and preparation method

[0001] The present application claims priority to the Chinese patent application No. 2024113431413, filed on September 25, 2024 in the China Patent Office and entitled "Perovskite layer preparation method, laminated solar cell and preparation method", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The statements herein are provided only to enhance understanding of the present application and are not necessarily intended to constitute the prior art.

[0003] The present application relates to the technical field of perovskite laminated solar cells, in particular to a perovskite layer preparation method and a laminated solar cell and a preparation method. BACKGROUND

[0004] Perovskite laminated solar cells are a new type of solar cells with high potential for photoelectric conversion. They use perovskite as a photovoltaic material and are composed of perovskite layers through a laminated structure. Each laminated structure in the laminated solar cell can absorb different wavelengths of sunlight, thereby maximizing the photoelectric conversion efficiency and achieving more efficient use of light energy. The working principle of perovskite laminated solar cells is that when sunlight shines on the perovskite laminated solar cell, the sunlight can be divided into several consecutive parts. The shortest wavelength light is absorbed and utilized by the outermost wide-bandgap material cell, and the longer wavelength light is transmitted to the narrower-bandgap material cell for absorption and utilization, thereby maximizing the conversion of light energy into electrical energy. The band gap of perovskite material in the perovskite layer is small, which can absorb longer wavelength sunlight. In addition, perovskite material also exhibits a high light absorption coefficient. Therefore, perovskite laminated solar cells have been widely used.

[0005] Currently, the preparation methods of perovskite layers include evaporation method, spin coating method, light treatment and plasma treatment method, etc. Among them, the most commonly used methods are evaporation method and spin coating method. Generally, the perovskite layer adopts a two-step co-evaporation method. First, a lead iodide / cesium bromide film is prepared by evaporation method, and then an ammonium salt film is prepared on the lead iodide / cesium bromide film by evaporation method, or a lead iodide / cesium bromide film is first prepared by evaporation method, and then an ammonium salt film is prepared on the lead iodide / cesium bromide film by spin coating method. However, in the ammonium salt films prepared by these two methods, the lead iodide / cesium bromide at the bottom of the lead iodide / cesium bromide film cannot directly contact with the ammonium salt when combined with the lead iodide / cesium bromide film, and it is difficult to react completely. A large amount of lead iodide residue is formed in the lower layer of the perovskite layer. These free lead iodide will form a large number of defects in the perovskite layer, resulting in low quality of the formed perovskite film, thereby affecting the performance of the device.

[0006] Therefore, the perovskite film prepared by the traditional two-step method causes incomplete deposition on the lead iodide / cesium bromide film, so that a large number of defects exist in the perovskite layer, which leads to shortened service life and reduced light absorption rate of the solar cell during use, thereby affecting the performance of the prepared solar cell. SUMMARY

[0007] The perovskite layer preparation method, the stacked solar cell and the preparation method provided by the embodiments of the present application can solve the problem of incomplete deposition on the lead iodide / cesium bromide film, so that a large number of defects exist in the perovskite layer, which leads to shortened service life and reduced light absorption rate of the solar cell during use, thereby affecting the performance of the prepared solar cell.

[0008] The technical solutions adopted by the embodiments of the present application are as follows:

[0009] In a first aspect, a perovskite layer preparation method is provided, which comprises the following steps:

[0010] S1, providing a cell substrate, and using a co-evaporation method to co-evaporate lead iodide and cesium bromide onto the surface of the cell substrate to obtain a lead iodide / cesium bromide film;

[0011] S2, using an evaporation method to evaporate an ion diffusion material on the surface of the lead iodide / cesium bromide film in S1 to obtain an ion diffusion layer;

[0012] S3, using a spin coating method to coat an ammonium salt precursor solution on the surface of the ion diffusion layer in S2, and annealing to obtain the perovskite layer.

[0013] In one embodiment, the cell substrate comprises, from bottom to top, a crystalline silicon bottom cell, a tunneling layer and a hole transport layer, and the lead iodide / cesium bromide film is prepared on the surface of the hole transport layer.

[0014] In one embodiment, the ratio of the evaporation rate of lead iodide to the evaporation rate of lead iodide in the co-evaporation method is (2:1)-(10:1).

[0015] In one embodiment, the evaporation time of the co-evaporation method in step S1 is 1-10000s.

[0016] In one embodiment, the thickness of the lead iodide / cesium bromide film in step S1 is 200-800nm.

[0017] In one embodiment, the ion diffusion material in step S2 is one or more of rubidium fluoride (RbF), potassium fluoride (KF), sodium fluoride (NaF), rubidium chloride (RbCl), potassium chloride (KCl) and sodium chloride (NACl).

[0018] In one embodiment, the vacuum degree of the evaporation in the evaporation method in step S2 is 1×10 -4 -5×10 -4 Pa, the temperature of the evaporation is 50-400℃, and the rate of the evaporation is 0.05-1 Å / S.

[0019] In one embodiment, the thickness of the ion diffusion layer in step S2 is 1-100 nm.

[0020] In one embodiment, the ammonium salt precursor solution in step S3 is a mixed solution of formamidinium iodide (FAI) and formamidinium bromide (FABr).

[0021] In one embodiment, the concentration of the formamidinium iodide (FAI) and formamidinium bromide (FABr) in the solution is 0.5-2 mol / L, and the molar ratio of the formamidinium iodide (FAI) to the formamidinium bromide (FABr) in the solution is (1:10)-(10:1).

[0022] In one embodiment, the ammonium salt precursor solution further comprises an additive, which is methylamine chloride (MACl), and the mass fraction of the methylamine chloride (MACl) accounts for 0.5-50% of the ammonium salt precursor solution.

[0023] In one embodiment, the rotation speed of the spin coating method in step S3 is 1200-6000 rpm, and the spin coating time is 20-120 s.

[0024] In one embodiment, the temperature of the annealing in step S3 is 50-150℃, and the annealing time is 5-40 min.

[0025] In a second aspect, a laminated solar cell is provided, comprising a crystalline silicon bottom cell, a tunneling layer, and a perovskite top cell.

[0026] The perovskite top cell comprises a hole transport layer, a perovskite layer, an electron transport layer, a second transparent electrode layer, a second metal electrode layer, and an anti-reflection layer, and the perovskite layer is prepared by the perovskite preparation method of the first aspect.

[0027] Illustratively, the perovskite layer has an ABX3 structure, where A is an organic cation, including at least one of CH3NH3 + (MA + ), NH2CH=NH2 + (FA + ), CH3CH2NH3 + , or Cs + ;

[0028] B is a metal cation, including at least one of Pb 2+, Sn 2+ , at least one of F

[0029] X is halide anion, including at least one of F - , Cl - , Br - , I - .

[0030] In one embodiment, the crystalline silicon bottom cell can be selected from one of the following crystalline silicon cells: pear cell, topcon cell or HJT, etc.

[0031] Specifically, the crystalline silicon bottom cell comprises, from bottom to top, a first metal electrode layer, a first transparent electrode layer, a P-type base doped layer, a base passivation layer, a textured crystalline silicon substrate, a base surface passivation layer and an N-type base doped layer.

[0032] In one embodiment, the surface of the textured crystalline silicon substrate is provided with a textured structure, which can reduce surface reflection and light escape, improve light capture efficiency, and thus improve photoelectric conversion efficiency.

[0033] In one embodiment, the textured crystalline silicon substrate can be selected from one of the following: intrinsic single crystalline silicon, intrinsic polycrystalline silicon, N-type or P-type single crystalline silicon.

[0034] In one embodiment, the hole transport layer is at least one of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]

[0035] (PTAA), poly-3-hexylthiophene (P3HT), nickel oxide (NiOx), molybdenum trioxide (MoO3), cuprous iodide (CuI), cuprous thiocyanate (CuSCN);

[0036] The electron transport layer is at least one of zinc oxide (ZnO), tin dioxide (SnO2), titanium dioxide (TiO2), [6,6] phenyl C 61 methyl butyrate (PC 61 BM), carbon 60 (C 60 ), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP);

[0037] The first transparent electrode layer and the second transparent electrode layer are at least one of indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO);

[0038] The first metal electrode layer and the second metal electrode layer are at least one of silver (Ag), gold (Au), copper (Cu), aluminum (Al), carbon (C);

[0039] The anti-reflective layer is at least one of magnesium fluoride, lithium fluoride (LiF), sodium fluoride (NaF), silicon oxide (SiO2).

[0040] In one embodiment, a passivation layer is further provided between the perovskite layer and the electron transport layer.

[0041] In one embodiment, the passivation layer includes, but is not limited to, at least one of propylene diamine bromide (PDADBr), butyl chloride amine (BACl), butyl bromide amine (BABr), butyl iodide amine (BAI), N, N-dimethyl-1, 3-propylene diamine hydrochloride (DMePDADCl), decane diamine bromide (DDDADBr); and at least one of magnesium fluoride (MgF), lithium fluoride (LiF), sodium fluoride (NaF).

[0042] In one embodiment, a buffer layer is further provided between the electron transport layer and the second transparent electrode layer.

[0043] In one embodiment, the buffer layer is at least one of zinc oxide (ZnO), tin dioxide (SnO2), titanium dioxide (TiO2).

[0044] In a third aspect, the application provides a preparation method of the laminated solar cell, including the following steps:

[0045] A textured silicon substrate is provided, a base passivation layer is prepared on the back surface of the textured silicon substrate, a P-type base doping layer is prepared on the surface of the base passivation layer, a first transparent electrode layer is prepared on the surface of the P-type base doping layer, and a first metal electrode layer is prepared on the surface of the first transparent electrode layer; and a base surface passivation layer is prepared on the surface of the textured silicon substrate, an N-type base doping layer is prepared on the surface of the base surface passivation layer, a tunneling layer is prepared on the surface of the N-type base doping layer, a hole transport layer is prepared on the surface of the tunneling layer, a perovskite layer is prepared on the surface of the hole transport layer, a passivation layer is prepared on the surface of the perovskite layer, an electron transport layer is prepared on the surface of the passivation layer, a buffer layer is prepared on the surface of the electron transport layer, a second transparent electrode layer is prepared on the surface of the buffer layer, a second metal electrode layer is prepared on the surface of the second transparent electrode layer, and an anti-reflective layer is prepared on the surface of the second metal electrode layer.

[0046] In one embodiment, the perovskite layer is prepared by the above-mentioned perovskite preparation method.

[0047] In order to saturate the dangling bonds on the surface of the textured silicon substrate, reduce the surface activity, increase the cleaning procedure of the surface, avoid the formation of recombination centers due to the introduction of impurities in the surface layer, and thus reduce the surface recombination rate of the minority carriers, a base passivation layer and a base surface passivation layer can be formed on the two surfaces of the textured silicon substrate by using a vapor deposition method, an atomic layer deposition method, or the like.

[0048] In one embodiment, a phosphorus source / nitrogen source is used to diffuse on the textured silicon substrate to form a doped structure, thereby obtaining the P-type base doped layer and the N-type base doped layer, respectively.

[0049] In one embodiment, the first transparent electrode layer is prepared by using a magnetron sputtering method, and the prepared base sample is placed in a magnetron sputtering device for preparation, and the magnetron sputtering power is 50-200 W.

[0050] In one embodiment, the first metal electrode layer is prepared by using an evaporation method, which includes placing the prepared base sample on a mask for evaporation, and the evaporation vacuum degree is 5×10 -5 -2×10 -4 Pa, the evaporation temperature is 500-2000℃, and the evaporation rate is 0.1-5 Å / S.

[0051] In one embodiment, the tunneling layer is used to solve the problem of electrical mismatch and device instability between two series-connected cells. The tunneling layer can be prepared by using one of an atomic layer deposition method, a magnetron sputtering method, or a wet chemical method.

[0052] In one embodiment, the hole transport layer is prepared by using a spin coating method, which includes uniformly coating a hole transport layer dispersion liquid on the surface of the tunneling layer, the spin coating rotation speed is 1000-5000 rpm, and the spin coating time is 10-100 s; after the spin coating is completed, annealing is performed, the annealing temperature is 300-600℃, and the annealing time is 10-50 min.

[0053] Alternatively, the hole transport layer can also be prepared by using a magnetron sputtering method, which specifically includes placing the prepared base sample in a magnetron sputtering device, and controlling the power to be 30-90 W.

[0054] In one embodiment, the passivation layer is prepared by using an evaporation method, which includes evaporating a passivation layer material to the surface of the perovskite layer, the evaporation vacuum degree is 1×10 -4 -5×10 -4 Pa, the evaporation temperature is 50-400℃, the evaporation rate is 0.05-1 Å / S, after the evaporation is completed, annealing is performed, the annealing temperature is 0-150℃, and the annealing time is 0-30 min.

[0055] Alternatively, the passivation layer can also be prepared by spin coating, including preparing a passivation layer dispersion liquid and uniformly coating on the perovskite layer surface, the passivation layer dispersion liquid is prepared by dissolving the passivation layer material in an organic solvent such as but not limited to methanol, ethanol or isopropanol, ultrasonic dissolution and spin coating, the concentration of the passivation layer dispersion liquid is 0.1-6 mg / mL, the ultrasonic time is 0-30 min, the spin coating speed is 1000-7000 rpm, the spin coating time is 20-120 s, after spin coating, annealing is performed, the annealing temperature is 40-160℃, and the annealing time is 5-40 min;

[0056] Alternatively, the passivation layer can also be prepared by spraying, including spraying the passivation layer dispersion liquid on the perovskite layer, the spraying rate is 0-100 cm / s, after spraying, annealing is performed, the annealing temperature is 20-170℃, and the annealing time is 0-30 min;

[0057] In one embodiment, the electron transport layer is prepared by spin coating, specifically, the electron transport layer dispersion liquid is uniformly spin coated on the surface of the passivation layer, the spin coating speed is 500-4000 rpm, and the spin coating time is 10-80 s;

[0058] Alternatively, the electron transport layer can also be prepared by evaporation, the electron transport layer material is evaporated to the surface of the passivation layer, the evaporation vacuum degree is 5×10 -5 -5×10 -4 Pa, the evaporation temperature is 100-400℃, and the evaporation rate is 0.05-1 Å / S;

[0059] In one embodiment, the buffer layer is prepared by atomic layer deposition, including depositing the buffer layer material to the surface of the electron transport layer by using an atomic layer deposition device, the deposition vacuum degree is 0-1×10 4 Pa, the deposition pipe temperature is 50-150℃, and the deposition chamber temperature is 40-150℃;

[0060] Alternatively, the buffer layer can also be prepared by evaporation, the buffer layer material is evaporated to the surface of the electron transport layer, the evaporation vacuum degree is 6×10 -5 -4×10 -4 Pa, the evaporation temperature is 100-500℃, and the evaporation rate is 0.05-1 Å / S;

[0061] In one embodiment, the second transparent electrode layer is prepared by magnetron sputtering, including sputtering the transparent electrode material to the surface of the buffer layer, and the control power is 30-200 W;

[0062] Alternatively, the second transparent electrode layer can also be prepared by evaporation, characterized in that the transparent electrode material is evaporated to the surface of the buffer layer, the evaporation vacuum degree is 1×10 -5-5x10 -4 Pa, the evaporation temperature is 1000-2000℃, and the evaporation rate is 0.05-3 Å / S.

[0063] In one embodiment, the antireflection layer can be prepared by magnetron sputtering or evaporation.

[0064] The method for preparing a perovskite layer, the stacked solar cell and the method for preparing the same provided in the embodiments of the present application have the following beneficial effects: the deposition effect of the ammonium salt in the lead iodide / cesium bromide film is improved by preparing an ion diffusion layer between the lead iodide / cesium bromide film and the ammonium salt film, and the traditional two-step method for preparing the perovskite layer is changed. First, the lead iodide / cesium bromide film is prepared by co-evaporation, and then the ion diffusion material is evaporated onto the surface of the lead iodide / cesium bromide film after the first step of co-evaporation to form an ion diffusion layer. The ion diffusion layer is a halogen ion material such as rubidium fluoride or rubidium chloride, which has a high ion conductivity under high temperature conditions. In addition, the ion radius of the ion diffusion layer material is smaller than the perovskite lattice radius, and the ion diffusion layer material can freely diffuse in the film during the formation of the perovskite, which enables the ammonium salt in the ammonium salt film to react more completely with the lead iodide / cesium bromide film. At the same time, the ion diffusion layer can also passivate the defects in the formation process of the perovskite film, so that a high-quality perovskite film with low defect density is formed, and the performance of the device is improved. BRIEF DESCRIPTION OF DRAWINGS

[0065] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the embodiments or exemplary technical descriptions will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0066] FIG. 1 is a structural schematic diagram of the stacked solar cell described in the present application;

[0067] FIG. 2 is a preparation flowchart of the perovskite layer described in the present application;

[0068] The label in the figure is as follows: 1, cell substrate; 10, crystalline silicon bottom cell; 20, tunneling layer; 30, perovskite top cell; 101, first metal electrode layer; 102, first transparent electrode layer; 103, P-type base doped layer; 104, base passivation layer; 105, textured crystalline silicon substrate; 106, base surface passivation layer; 107, N-type base doped layer; 301, hole transport layer; 302, perovskite layer; 303, passivation layer; 304, electron transport layer; 305, buffer layer; 306, second transparent electrode layer; 307, second metal electrode layer; 308, antireflection layer; L1, lead iodide / cesium bromide film; L2, ion diffusion layer; L3, ammonium salt film. DETAILED DESCRIPTION

[0069] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application.

[0070] It should be noted that when a component is referred to as being "fixed" or "set" on another component, it can be directly on the other component or indirectly on the other component. When a component is referred to as being "connected" to another component, it can be directly or indirectly connected to the other component. The terms "upper", "lower", "left", "right", and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only used for convenience of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. For those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "first", "second" are only used for the purpose of convenience of description, and cannot be understood as indicating or implying relative importance or implying the number of technical features. The meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0071] In order to illustrate the technical solutions provided by the present application, the following will be described in detail with reference to the specific accompanying drawings and embodiments.

[0072] Embodiment 1

[0073] Please refer to FIGS. 1-2, the present embodiment provides a perovskite layer preparation method, comprising the following steps:

[0074] S1, providing a battery substrate 1, using co-evaporation method to co-evaporate lead iodide and cesium bromide onto the surface of the battery substrate 1 to obtain a 440 nm lead iodide / cesium bromide film L1, the evaporation rate of the lead iodide is 8 A / s, the evaporation rate of the cesium bromide is 0.8 A / s, and the total evaporation time is 1000 s;

[0075] S2, on the surface of the lead iodide / cesium bromide film L1 in S1, using evaporation method to evaporate rubidium fluoride to obtain a 1 nm ion diffusion layer L2, the vacuum degree of the evaporation is 1x10 -4 Pa, the evaporation temperature is 400℃, and the evaporation rate is 0.05 Å / s;

[0076] S3, on the surface of the ion diffusion layer L2 in S2, an ammonium salt precursor solution is coated by spin coating, and annealing is performed to obtain the perovskite layer L3; the rotation speed of spin coating is 5000 rpm, the spin coating time is 30 s, the annealing temperature is 150 DEG C, the annealing time is 10 min, the molar ratio of formamidinium iodide (FAI) to formamidinium bromide (FABr) in the ammonium salt precursor solution is 1:4.7, the ammonium salt precursor solution further comprises an additive, the additive is methylamine chloride (MACl), the mass fraction of the methylamine chloride (MACl) accounts for 10% of the formamidinium iodide (FAI) and formamidinium bromide (FABr) solution, and the concentration of the formamidinium iodide (FAI) and formamidinium bromide (FABr) in the ammonium salt precursor solution is 1 mol / L.

[0077] The embodiment also provides a laminated solar cell, which comprises a crystalline silicon bottom cell 10, a tunneling layer 20, and a perovskite top cell 30; the crystalline silicon bottom cell 10 comprises, from bottom to top, a first metal electrode layer 101, a first transparent electrode layer 102, a P-type base doped layer 103, a base passivation layer 104, a textured crystalline silicon substrate 105, a base surface passivation layer 106, and an N-type base doped layer 107; the perovskite top cell 30 comprises, from bottom to top, a hole transport layer 301, a perovskite layer 302, a passivation layer 303, an electron transport layer 304, a buffer layer 305, a second transparent electrode layer 306, a second metal electrode layer 307, and an anti-reflection layer 308; the perovskite layer is prepared by the perovskite preparation method described above.

[0078] The embodiment also provides a preparation method of the laminated solar cell, which comprises the following steps.

[0079] S(1), providing a textured crystalline silicon substrate 105, preparing a base passivation layer 104 on the back surface of the textured crystalline silicon substrate 105, and diffusing a phosphorus source on the base passivation layer 104 to form a P-type base doped layer 103; preparing a base surface passivation layer 106 on the surface of the textured crystalline silicon substrate 105, and diffusing a nitrogen source on the base surface passivation layer 106 to form an N-type base doped layer 107;

[0080] S(2), preparation of the first transparent electrode layer 102:

[0081] The first transparent electrode layer 102 is prepared on the surface of the P-type base doped layer 103 by a magnetron sputtering method, and the thickness of the first transparent electrode layer 102 is 100 nm; the target material of the magnetron sputtering method is indium tin oxide (ITO), the power of the magnetron sputtering method is 60 W, and the running time of the magnetron sputtering method is 1.5 h;

[0082] S(3), preparation of the first metal electrode layer 101:

[0083] The substrate sample prepared in the above step is placed on a mask plate, and silver (Ag) is evaporated on the surface of the first transparent electrode layer 102 by an evaporation method to prepare the first metal electrode layer 101, and the thickness of the first metal electrode layer 101 is 200 nm, wherein the vacuum degree of the evaporation method is 2x10 -4 Pa, the temperature is 800°C, and the evaporation rate is 2.5Å / S.

[0084] S(4), preparation of the tunneling layer 20:

[0085] The tunneling layer 20 is prepared on the surface of the N-type substrate doped layer 107, and the thickness of the tunneling layer 20 is 40 nm, wherein the power of the magnetron sputtering is 60 W, and the running time is 1 h.

[0086] S(5), preparation of the hole transport layer 301:

[0087] The tunneling layer 20 is cleaned by a UV-ozone cleaning machine for 15 min, 0.05 mol of NiOx powder is dissolved in 1 mL of ultrapure water, and ultrasonic oscillation is performed for 20 min to prepare a hole transport layer dispersion liquid, and the hole transport layer dispersion liquid is uniformly coated on the surface of the tunneling layer 20 after ultrasonic oscillation for 20 min, and the hole transport layer 301 is prepared by spin coating and then annealing, and the thickness of the hole transport layer 301 is 20 nm, wherein the spin coating speed of the spin coating method is 2000 rpm, the spin coating time is 40 s, the solution amount of spin coating is 100 ul, the annealing temperature is 450°C, and the annealing time is 30 min.

[0088] S(6), preparation of the perovskite layer 302:

[0089] Lead iodide and cesium bromide are evaporated onto the surface of the hole transport layer 301 by a co-evaporation method to obtain a lead iodide / cesium bromide film L1, rubidium fluoride is evaporated onto the surface of the lead iodide / cesium bromide film L1 by an evaporation method to form an ion diffusion layer L2, and the ammonium salt precursor solution is coated onto the surface of the ion diffusion layer L2 by a spin coating method to prepare an ammonium salt film L3 on the surface of the ion diffusion layer L2, and the perovskite layer 302 is obtained after annealing, and the thickness of the perovskite layer 302 is 440 nm, wherein the evaporation rate of lead iodide in the co-evaporation method is 8A / s, the evaporation rate of lead iodide in the co-evaporation method is 0.8A / s, the ratio of the evaporation rate of lead iodide in the co-evaporation method to the evaporation rate of lead iodide is 10:1, the evaporation time of the co-evaporation method is 1000 s, and the vacuum degree of the evaporation method is 1x10 -4Pa, the evaporation temperature is 400 DEG C, the evaporation rate is 0.05 angstrom / s, the thickness of the ion diffusion layer L2 is 1 nm, the spin coating speed of the spin coating method is 5000 rpm, the spin coating time is 30 s, the annealing temperature is 150 DEG C, the annealing time is 10 min, the molar ratio of formamidinium iodide (FAI) and formamidinium bromide (FABr) in the formamidinium iodide (FAI) and formamidinium bromide (FABr) solution is 1:4.7, the formamidinium iodide (FAI) and formamidinium bromide (FABr) solution further comprises an additive, the additive is methylamine chloride (MACl), the mass fraction of the methylamine chloride (MACl) accounts for 10% of the formamidinium iodide (FAI) and formamidinium bromide (FABr) solution, and the concentration of the formamidinium iodide (FAI) and formamidinium bromide (FABr) solution is 1 mol / L;

[0090] S (7), preparation of the passivation layer 303:

[0091] The substrate sample prepared in the above step is placed on a mask plate, 3 mg of propylene diamine iodine is evaporated to the surface of the perovskite layer 302 by using an evaporation method, and annealing is performed to prepare the passivation layer 302, and the thickness of the passivation layer 302 is 4 nm, wherein the evaporation vacuum degree is 2*10 -4 Pa, the evaporation temperature is 80 DEG C, the evaporation rate is 0.1 angstrom / s, the annealing temperature is 100 DEG C, and the annealing time is 8 min;

[0092] S (8), preparation of the electron transport layer 304:

[0093] C 60 The electron transport layer 304 is prepared by evaporating SnO2 to the surface of the passivation layer 303, and the thickness of the electron transport layer 304 is 20 nm, wherein the evaporation vacuum degree is 1*10 -4 Pa, the evaporation temperature is 200 DEG C, and the evaporation rate is 0.1 angstrom / s;

[0094] S (9), preparation of the buffer layer 305:

[0095] The buffer layer 305 is prepared by depositing SnO2 to the surface of the electron transport layer 304 by using an atomic layer deposition method and an atomic layer deposition device, and the thickness of the buffer layer 305 is 15 nm, wherein the deposition vacuum degree is 0.5*10 4 Pa, the pipeline temperature of the deposition is 70 DEG C, and the temperature of the deposition cavity is 60 DEG C;

[0096] S (10), preparation of the second transparent electrode layer 306:

[0097] The second transparent electrode layer 306 is prepared on the surface of the buffer layer 305 by a magnetron sputtering method, and has a thickness of 100 nm. In the magnetron sputtering method, the target material is indium tin oxide (ITO), the power is 50 W, and the operation time is 1 h.

[0098] S (11), preparation of the second metal electrode layer 307:

[0099] The substrate sample prepared in the previous step is placed on a mask plate, and silver (Ag) is evaporated on the surface of the second transparent electrode layer 306 by an evaporation method to prepare the second metal electrode layer 307, which has a thickness of 100 nm. In the evaporation method, the vacuum degree is 2x10 -4 Pa, the temperature is 800℃, and the evaporation rate is 0.1 Å / S.

[0100] S (12), preparation of the anti-reflection layer 308:

[0101] The substrate sample prepared in the previous step is placed on a mask plate, and magnesium fluoride is evaporated on the surface of the second metal electrode layer 307 by an evaporation method, and then annealing is performed to prepare the anti-reflection layer 308, which has a thickness of 100 nm. In the evaporation method, the vacuum degree is 2x10 -4 Pa, the evaporation temperature is 80℃, the evaporation rate is 2 Å / S, the annealing temperature is 100℃, and the annealing time is 8 min, to obtain a stacked solar cell.

[0102] Example 2

[0103] The preparation process of the stacked solar cell in this example is the same as that described in Example 2, except that the thickness of the ion diffusion layer L2 in this example is 2 nm.

[0104] Example 3

[0105] The preparation process of the stacked solar cell in this example is the same as that described in Example 2, except that the thickness of the ion diffusion layer L2 in this example is 3 nm.

[0106] Comparative Example 1

[0107] The preparation method of the stacked solar cell in this comparative example is basically the same as that in Example 2, except that the preparation process of the perovskite layer in this comparative example is as follows:

[0108] The lead iodide and cesium bromide are evaporated onto the surface of the hole transport layer by a co-evaporation method to prepare a lead iodide / cesium bromide film on the surface of the hole transport layer, the ammonium salt precursor solution is coated onto the surface of the lead iodide / cesium bromide film by a spin coating method to prepare an ammonium salt film on the surface of the lead iodide / cesium bromide film, and the perovskite layer is obtained after annealing, and the thickness of the perovskite layer is 400 nm. In the co-evaporation method, the evaporation rate of the lead iodide is 8 A / s, the evaporation rate of the lead iodide is 0.8 A / s, the ratio of the evaporation rate of the lead iodide to the evaporation rate of the lead iodide is 10:1, the evaporation time of the co-evaporation method is 1000 s, the spin coating speed of the spin coating method is 5000 rpm, the spin coating time is 30 s, the annealing temperature is 150 DEG C, the annealing time is 10 min, the molar ratio of the formamidinium iodide (FAI) to the formamidinium bromide (FABr) in the formamidinium iodide (FAI) and formamidinium bromide (FABr) solution is 1:4.7, the formamidinium iodide (FAI) and formamidinium bromide (FABr) solution further comprises an additive, the additive is methylamine chloride (MACl), the mass fraction of the methylamine chloride (MACl) accounts for 10% of the formamidinium iodide (FAI) and formamidinium bromide (FABr) solution, and the concentration of the formamidinium iodide (FAI) and formamidinium bromide (FABr) solution is 1 mol / L.

[0109] The obtained laminated solar cells in Examples 1-3 and Comparative Example 1 are tested, the test conditions are as follows: a standard sunlight intensity calibration is performed by using a solar simulator, and the IV test of the device with an area of 1.0 cm 2 is performed for a long period of time, the starting voltage is set to 1.95 V, the cut-off voltage is set to 0 V, the range is set to 100 mA, and the results are retained to two decimal places. The test results are shown in Table 1.

[0110] Table 1 is the performance of the laminated solar cells in Examples 1-3 and Comparative Example 1

[0111]

[0112] The performance of the stacked solar cells in Examples 1-3 and Comparative Example 1 is shown in Table 1. The stacked solar cells in Examples 1-3 have high photoelectric conversion efficiency and low decay rate. The preparation of the ion diffusion layer is introduced in the traditional two-step method. The ion radius of the ion diffusion molecule is smaller than the radius of the perovskite lattice, which can freely diffuse inside the thin film, effectively promote the generation of perovskite crystals, and improve the quality of the generated thin film. The device prepared by this method has better performance and stability. The effect is best when the thickness of the ion diffusion layer is set to 2 nm, which is reflected in the best photoelectric conversion efficiency, open circuit voltage and short circuit current density of the device obtained in Example 2, and has a lower decay rate. In contrast, the perovskite layer in Comparative Example 1 is only prepared by a two-step method, which has low photoelectric conversion efficiency and significantly improved decay rate.

[0113] The above only describes optional embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. A method for preparing a perovskite layer, characterized by, The preparation method comprises the following steps: S1, providing a battery substrate, co-evaporating lead iodide and cesium bromide to the surface of the battery substrate by co-evaporation method to obtain a lead iodide / cesium bromide film; S2, evaporating ion diffusion material on the surface of the lead iodide / cesium bromide film in S1 by evaporation method to obtain an ion diffusion layer; S3, coating ammonium salt precursor solution on the surface of the ion diffusion layer in S2 by spin coating method, and annealing to obtain the perovskite layer.

2. The method for preparing a perovskite layer according to claim 1, characterized in that, The battery substrate comprises a crystalline silicon bottom cell, a tunneling layer and a hole transport layer from bottom to top, and the lead iodide / cesium bromide film is on the surface of the hole transport layer.

3. The method for preparing a perovskite layer according to claim 1, characterized in that, The ratio of the evaporation rate of lead iodide to the evaporation rate of lead iodide in the co-evaporation method is (2:1)-(10:1).

4. The method for preparing a perovskite layer according to claim 1, characterized in that, The ion diffusion material in step S2 is one or more of rubidium fluoride (RbF), potassium fluoride (KF), sodium fluoride (NaF), rubidium chloride (RbCl), potassium chloride (KCl), and sodium chloride (NaCl).

5. The method for preparing a perovskite layer according to claim 1, characterized in that, The vacuum degree of the evaporation in the evaporation method in the step S2 is 1x10 -4 -5x10 -4 Pa, the temperature of the evaporation is 50-400℃, and the rate of the evaporation is 0.05-1Å / S.

6. The method for preparing a perovskite layer according to claim 1, characterized in that, The thickness of the ion diffusion layer in step S2 is 1-100 nm.

7. The method for preparing a perovskite layer according to claim 1, characterized in that, The ammonium salt precursor solution in step S3 is a mixed solution of formamidinium iodide (FAI) and formamidinium bromide (FABr).

8. The method of claim 7, wherein, The molar ratio of formamidinium iodide (FAI) to formamidinium bromide (FABr) in the mixed solution is 1:10 to 10:1, and the concentration is 0.5-2 mol / L.

9. The method for preparing a perovskite layer according to claim 1, characterized in that, The annealing temperature in step S3 is 50-150℃, and the annealing time is 5-40 min.

10. A stacked solar cell, characterized by The crystalline silicon bottom cell, the tunneling layer, and the perovskite top cell, the perovskite top cell comprising a hole transport layer, a perovskite layer, an electron transport layer, a second transparent electrode layer, a second metal electrode layer, and an anti-reflection layer, the perovskite layer being prepared by the perovskite preparation method of any one of claims 1-9.

11. The tandem solar cell according to claim 10, wherein The crystalline silicon bottom cell comprises a first metal electrode layer, a first transparent conductive layer, a P-type doped silicon layer, a back surface passivation layer, a textured crystalline silicon substrate, a front surface passivation layer, and an N-type doped silicon layer from the back light side to the tunneling junction layer side.

12. The tandem solar cell of claim 10, wherein, A passivation layer is provided between the perovskite layer and the electron transport layer.

13. The tandem solar cell of claim 10, wherein, A buffer layer is provided between the electron transport layer and the transparent conductive layer.

14. A method of fabricating the stacked solar cell of claim 10, wherein, The preparation method comprises the following steps: A textured crystalline silicon substrate is provided, a base passivation layer is prepared on the back surface of the textured crystalline silicon substrate, a P-type base doped layer is prepared on the surface of the base passivation layer, a first transparent electrode layer is prepared on the surface of the P-type base doped layer, and a first metal electrode layer is prepared on the surface of the first transparent electrode layer; A base surface passivation layer is prepared on the surface of the textured crystalline silicon substrate, an N-type base doped layer is prepared on the surface of the base surface passivation layer, a tunneling layer is prepared on the surface of the N-type base doped layer, a hole transport layer is prepared on the surface of the tunneling layer, a perovskite layer is prepared on the surface of the hole transport layer, a passivation layer is prepared on the surface of the perovskite layer, an electron transport layer is prepared on the surface of the passivation layer, a buffer layer is prepared on the surface of the electron transport layer, a second transparent electrode layer is prepared on the surface of the buffer layer, a second metal electrode layer is prepared on the surface of the second transparent electrode layer, and an anti-reflection layer is prepared on the surface of the second metal electrode layer.

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