Tandem solar cell, and preparation method therefor and use thereof

Abstract

The present application relates to a tandem solar cell, and a preparation method therefor and the use thereof. The tandem solar cell comprises a first electrode, a first light-absorbing layer, a composite layer, a second light-absorbing layer and a second electrode that are stacked, wherein the composite layer comprises metal composite particles, which comprise metal particles and organic active substances disposed on surfaces of the metal particles. The tandem solar cell has excellent photoelectric conversion efficiency.

Description

Stacked solar cell and preparation method and application thereof

[0001] Related applications

[0002] The present application claims priority to the Chinese patent application No. 2024108671169, filed on June 28, 2024, and entitled "Stacked solar cell and preparation method and application thereof", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of batteries, and in particular to a stacked solar cell and a preparation method and application thereof. BACKGROUND

[0004] Solar cells have excellent photoelectric properties and high efficiency advantages, and have become the focus of next-generation photovoltaic technology research.

[0005] To meet the requirements of marketization and large-scale production, solar cells are developing towards high efficiency, low cost, and simplified preparation process. Among them, the stacked solar cell constructed by combining layers in series with wide / narrow bandgap perovskite sub-cells has the advantages of high efficiency and low cost, and is an important development direction of next-generation photovoltaic technology. However, the traditional composite layer has a low composite rate, which greatly limits the improvement of the performance of the stacked solar cell.

[0006] Therefore, the traditional technology still needs to be improved. SUMMARY

[0007] Therefore, it is necessary to provide a stacked solar cell and a preparation method and application thereof, which aims to improve the photoelectric conversion efficiency of the battery.

[0008] The present application is achieved by the following technical solutions.

[0009] In a first aspect of the present application, a stacked solar cell is provided, which comprises a first electrode, a first light-absorbing layer, a composite layer, a second light-absorbing layer, and a second electrode arranged in layers; the composite layer comprises metal composite particles, and the metal composite particles comprise metal particles and organic active substances arranged on the surface of the metal particles.

[0010] The metal composite particles contained in the composite layer of the above stacked solar cell include metal particles and an organic active substance provided on the surface of the metal particles. On the one hand, the organic active substance can improve the contact between the composite layer and other functional layers such as the light-absorbing layer, which is equivalent to forming a buffer zone between the metal particles and other functional layers such as the light-absorbing layer, thereby reducing the series resistance and further improving the fill factor FF of the cell. On the other hand, the organic active substance also plays a role in improving the dispersibility of the metal particles, thereby making the metal composite particles in the composite layer relatively loose and further improving the recombination rate of the composite layer. In this way, the photoelectric conversion efficiency of the cell can be improved.

[0011] In some embodiments, the organic active substance includes at least one of a reducing active agent, an ionic surfactant, a polyolefin, a polyethylene glycol, a polyethylene wax, a vinyl bis-stearamide, a monoglyceride stearate, and a glycerol tristearate. The reducing active agent has reducing property and contains an acid ion. Alternatively, the organic active substance includes a reducing active agent having reducing property and containing an acid ion. The reducing active agent can act as a reducing agent in the preparation of the metal particles, thereby reducing the metal salt to form the metal particles, and further act as a stabilizer to be provided on the surface of the metal particles. Therefore, no other reducing agent needs to be added during the preparation process. The ionic surfactant has an ionic group that can be adsorbed on the surface of the metal particles.

[0012] In some embodiments, the reducing active agent includes at least one of a citrate and an ascorbic acid. In some embodiments, the average particle size of the metal particles is 2 nm to 30 nm.

[0013] In some embodiments, the average particle size of the metal particles is 2 nm to 10 nm.

[0014] The metal particles in the composite layer in this particle size range can improve the light transmittance of the composite layer, thereby improving the photoelectric conversion efficiency of the cell.

[0015] In some embodiments, the thickness of the composite layer is 2 nm to 90 nm.

[0016] In some embodiments, the thickness of the composite layer is 2 nm to 20 nm.

[0017] The thickness of the composite layer in this range can have both high light transmittance and high recombination rate.

[0018] In some embodiments, the composite layer is located on part or all of the surface of the first light-absorbing layer.

[0019] In some embodiments, the stacked solar cell satisfies one or more of the following (1) and (2):

[0020] (1) the metal particles include at least one of gold particles, silver particles, platinum particles, and copper particles;

[0021] (2) the morphology of the metal particles includes at least one of a spherical shape, a quasi-spherical shape, a flower shape, a rod shape, a cubic shape, a hexagonal shape, a triangular shape, and an irregular shape.

[0022] In some embodiments, the mass ratio of the metal particles to the organic active substance is 1:(0.1-10).

[0023] In some embodiments, each of the first light-absorbing layer and the second light-absorbing layer independently includes a perovskite material, the perovskite material including at least one of ABX3and A2CDX6;

[0024] wherein A includes at least one of a monovalent inorganic cation and a monovalent organic cation;

[0025] B includes at least one of a divalent inorganic cation and a divalent organic cation;

[0026] C includes at least one of a monovalent inorganic cation and a monovalent organic cation;

[0027] D includes at least one of a trivalent inorganic cation and a trivalent organic cation;

[0028] X includes at least one of a monovalent inorganic anion and an organic anion.

[0029] In some embodiments, A includes at least one of Li + , Na + , K + , Rb + , Cs + , a methylamine ion, an ethylamine ion, a propylamine ion, a butylamine ion, a pentylamine ion, a hexylamine ion, a formamidinium ion, and an imidazolium ion;

[0030] B includes at least one of a lead ion, a tin ion, a zinc ion, a titanium ion, an antimony ion, a bismuth ion, a nickel ion, an iron ion, a cobalt ion, a silver ion, a copper ion, a gallium ion, a germanium ion, a magnesium ion, a calcium ion, an indium ion, an aluminum ion, a manganese ion, a chromium ion, a molybdenum ion, and an europium ion;

[0031] C includes at least one of Cs + , Ag + , K + , and Rb + ;

[0032] D includes Bi 3+ , Ni 3+ , Fe 3+ , Sb3+ In 3+ and Cu 3+ ;

[0033] X includes at least one of I - , Br - , Cl - , SCN - , HCOO - , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , CN - .

[0034] In some embodiments, the first light-absorbing layer is a wide-bandgap perovskite light-absorbing layer, and the second light-absorbing layer is a narrow-bandgap perovskite light-absorbing layer.

[0035] In some embodiments, the second light-absorbing layer is in direct contact with the composite layer.

[0036] Since the composite layer in the present application contains the above-mentioned metal composite particles, the composite layer can be in direct contact with the narrow-bandgap perovskite, and can serve as both a composite layer and a hole transport layer, and has a higher recombination rate and a higher optical transmittance than ITO. Therefore, in some embodiments of the present application, the hole transport layer between the second light-absorbing layer and the composite layer can be omitted or not provided, thereby omitting a functional layer, reducing the overall series resistance of the stacked solar cell, and thereby improving the overall light absorption of the stacked solar cell.

[0037] In some embodiments, the stacked solar cell satisfies one or more of the following (1) and (4):

[0038] (1) The stacked solar cell further comprises a first charge transport layer, which is disposed between the first electrode and the first light-absorbing layer;

[0039] (2) The stacked solar cell further comprises a second charge transport layer, which is disposed between the first light-absorbing layer and the composite layer;

[0040] (3) The stacked solar cell further comprises a third charge transport layer, which is disposed between the second light-absorbing layer and the composite layer;

[0041] (4) The stacked solar cell further comprises a fourth charge transport layer, which is disposed between the second light-absorbing layer and the second electrode.

[0042] In some embodiments, the stacked solar cell satisfies one or both of the following (1) and (2):

[0043] (1) the stacked solar cell includes the first charge transport layer and the second charge transport layer, one of which is a hole transport layer and the other of which is an electron transport layer;

[0044] (2) the stacked solar cell includes the third charge transport layer and the fourth charge transport layer, one of which is a hole transport layer and the other of which is an electron transport layer.

[0045] In some embodiments, the stacked solar cell satisfies one or both of the following (1) and (2):

[0046] (1) the hole transport layer includes one or more of 2,2',7,7'-tetra(N,N-p-methoxyanilino)-9,9'-spirobifluorene, methoxytriphenylamine-fluoromethylformamidine, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid, poly 3-hexyl thiophene, triptycene-core triphenylamine, 3,4-ethylenedioxythiophene-methoxytriphenylamine, N-(4-anilino)carbazole-spirobifluorene, polythiophene, phosphonic hole transport material, carbazolyl hole transport material, sulfonic hole transport material, a first metal oxide, cuprous iodide, and cuprous thiocyanate, the metal element in the first metal oxide including at least one of Ni, Mo, and Cu;

[0047] (2) the electron transport layer includes at least one of an imide compound, a quinone compound, fullerene and a derivative thereof, methoxytriphenylamine-fluoromethylformamidine, calcium titanate, lithium fluoride, calcium fluoride, a second metal oxide, silicon oxide, strontium titanate, cuprous thiocyanate; the metal element in the second metal oxide including at least one of Mg, Ni, Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, and Cr.

[0048] In some embodiments, the stacked solar cell further includes a metal diffusion inhibiting layer, the metal diffusion inhibiting layer satisfying one or both of the following (1) and (2):

[0049] (1) the metal diffusion inhibiting layer is provided between the second charge transport layer and the recombination layer;

[0050] (2) the metal diffusion inhibiting layer is provided between the third charge transport layer and the recombination layer.

[0051] The metal diffusion inhibiting layer can separate the composite layer from the charge transport layer, reduce the risk of damage to the charge transport layer, and thus improve the stability of the battery.

[0052] In some embodiments, the metal diffusion inhibiting layer satisfies one or both of the following (1) and (2):

[0053] (1) the thickness of the metal diffusion inhibiting layer is 5-10 nm;

[0054] (2) the metal diffusion inhibiting layer comprises at least one of a transparent conductive oxide and a carbon element material.

[0055] In a second aspect, the application provides a method for preparing the laminated solar cell provided in the first aspect, comprising the following steps:

[0056] sequentially forming the first electrode, the composite layer, and the second electrode to prepare the laminated solar cell;

[0057] The step of forming the composite layer comprises the following steps:

[0058] applying a dispersion liquid containing metal composite particles to the surface of the first electrode to form the composite layer; wherein the metal composite particles comprise metal particles and an organic active substance provided on the surface of the metal particles.

[0059] In some embodiments, in the dispersion liquid, the concentration of the metal particles is 0.01-10 mg / mL, and the concentration of the organic active substance is 0.005-50 mg / mL.

[0060] In some embodiments, the method for preparing the dispersion liquid containing metal composite particles comprises the following steps:

[0061] carrying out a reduction reaction of a metal salt and the organic active substance in a solvent to prepare a dispersion liquid containing metal composite particles;

[0062] The reduction reaction can or can not involve metal seeds.

[0063] In some embodiments, the preparation method satisfies one or both of the following (1) and (2):

[0064] (1) the molar ratio of the metal element in the metal salt to the organic active substance is 1:(0.1-5);

[0065] (2) the temperature of the reduction reaction is 50-300℃.

[0066] In a third aspect, the present application provides a photovoltaic module comprising the laminated solar cell of the first aspect or the laminated solar cell prepared by the method of the second aspect.

[0067] In a fourth aspect, the present application provides a photovoltaic system comprising the photovoltaic module of the third aspect.

[0068] In a fifth aspect, the present application provides an electric device comprising the laminated solar cell of the first aspect or the laminated solar cell prepared by the method of the second aspect or the photovoltaic module of the third aspect.

[0069] In a sixth aspect, the present application provides a power generation device comprising the laminated solar cell of the first aspect or the laminated solar cell prepared by the method of the second aspect or the photovoltaic module of the third aspect. BRIEF DESCRIPTION OF DRAWINGS

[0070] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description. The accompanying drawings are included to provide a description of preferred embodiments, and are not intended to limit the scope of the present application. Furthermore, the same reference numerals are used throughout the drawings to represent similar components. In the drawings:

[0071] FIG. 1 is a schematic diagram of the cross-sectional structure of a laminated solar cell according to an embodiment of the present application;

[0072] FIG. 2 is a scanning electron microscope image of the composite layer of Example 1 of the present application;

[0073] FIG. 3 is a scanning electron microscope image of the composite layer of Comparative Example 2 of the present application.

[0074] Reference Signs List: 10, laminated solar cell; 11, first electrode; 12, first charge transport layer; 13, first light absorbing layer; 14, second charge transport layer; 15, composite layer; 16, third charge transport layer; 17, second light absorbing layer; 18, fourth charge transport layer; 19, second electrode. DETAILED DESCRIPTION

[0075] Embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0076] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise noted, the terms "including" and "comprising" are open-ended and do not exclude the presence of unrecited elements or limitations.

[0077] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0078] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0079] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0080] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

[0081] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as limiting the embodiments of the present application. The orientation or position of the device or element indicated, and therefore cannot be understood as limiting the embodiments of the present application.

[0082] In the description of the embodiments of the present application, unless specifically defined and limited otherwise, the terms "mount", "connected", "connection", "fixed", and similar terms are to be construed broadly and are not limited to the meaning of the man skilled in the art, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0083] In the present application, unless otherwise specified, "room temperature" generally refers to 4-30°C, further refers to 20±5°C.

[0084] In the conventional technology, a conductive metal such as gold or a transparent conductive oxide such as tin-doped indium oxide (ITO) is often used to prepare the composite layer. However, due to the surface characteristics of the evaporated Au or ITO, it is difficult to form a good contact with the functional layer such as the narrow-bandgap perovskite, which reduces the carrier extraction efficiency and increases the series resistance, thereby limiting the improvement of the battery performance.

[0085] An embodiment of the present application provides a stacked solar cell. The stacked solar cell includes a first electrode, a first light-absorbing layer, a composite layer, a second light-absorbing layer, and a second electrode which are stacked. The composite layer includes metal composite particles, and the metal composite particles include metal particles and an organic active substance provided on the surface of the metal particles.

[0086] In the above-mentioned stacked solar cell, the metal composite particles contained in the composite layer include metal particles and an organic active substance provided on the surface of the metal particles. On the one hand, the organic active substance can improve the contact between the composite layer and other functional layers such as the light-absorbing layer, which is equivalent to forming a buffer zone between the metal particles and other functional layers such as the light-absorbing layer, thereby reducing the series resistance and further improving the fill factor FF of the battery. On the other hand, the organic active substance also plays a role in improving the dispersity of the metal particles, so that the metal composite particles in the composite layer are relatively loose, thereby improving the recombination rate of the composite layer. In this way, the photoelectric conversion efficiency of the battery can be improved.

[0087] It should be noted that in the above-mentioned "organic active substance provided on the surface of the metal particles", the metal particles and the organic active substance are suspended and loaded on the surface of the metal particles by electrostatic adsorption or chemical adsorption force.

[0088] In some embodiments, the organic active substance includes at least one of a reducing active agent, an ionic surfactant, a polyolefin, a polyethylene glycol, a polyethylene wax, a vinyl bis-stearamide, a monoglyceride stearate, and a glycerol tristearate. The reducing active agent has reducing property and contains an acid ion.

[0089] As an example, the reducing active agent includes, but is not limited to, at least one of citrate and ascorbic acid. The above-mentioned organic active substance can not only be used as a reducing agent to reduce metal salt to form metal particles in the preparation process of metal particles, but also be used as a stabilizer to be arranged on the surface of metal particles, so that other reducing agents do not need to be added in the preparation process. In addition, since the above-mentioned organic active substance is an ionic compound and has an acid radical ion, it is partially charged, which can further improve the contact between the composite layer and other functional layers such as the light-absorbing layer, and can also improve the dispersibility of the metal particles, further reduce the compactness of the composite layer, improve the compounding rate of the composite layer, and thus improve the photoelectric conversion efficiency of the battery.

[0090] In some embodiments, the ionic surfactant includes at least one of an anionic surfactant and a cationic surfactant. The ionic surfactant includes, but is not limited to, at least one of cetyltrimethylammonium chloride (CTAC), cetyltrimethylammonium bromide (CTAB), and dodecyltrimethylammonium bromide (DTAB). The ionic surfactant has an ionic group that can be adsorbed on the surface of the metal particles.

[0091] In some embodiments, the polyolefin includes, but is not limited to, at least one of polyethylene homopolymer, polyethylene copolymer, polypropylene, and polystyrene. The polyolefin, polyethylene glycol, polyethylene wax, vinyl bis-stearamide, stearic acid monoglyceride, and glycerol tri-stearate are good dispersants and can be adsorbed on the surface of the metal particles.

[0092] In the preparation process of the metal composite particles, if the organic active substance includes at least one of the ionic surfactant, the polyolefin, the polyethylene glycol, the polyethylene wax, the vinyl bis-stearamide, the stearic acid monoglyceride, and the glycerol tri-stearate, in addition to adding these organic active substances, a reducing agent is generally also needed to be added.

[0093] In some embodiments, the metal particles are nano-metal particles. Further, the average particle size of the metal particles is 2 nm to 30 nm, which can be, as an example, 2 nm, 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, or a range formed by any two of the above-mentioned values as end values, and the like hereinafter; further, the average particle size of the metal particles is 2 nm to 10 nm. The metal particles in the composite layer in this particle size range can improve the light transmittance of the composite layer, thereby being beneficial to the photoelectric conversion efficiency of the battery.

[0094] In some embodiments, the above-mentioned average particle size refers to the average value measured after the actual gold particles are measured.

[0095] In some embodiments, the composite layer has a thickness of 2 nm to 90 nm, for example, the thickness can be 2 nm, 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm. Further, the thickness of the composite layer is 2 nm to 20 nm. The thickness of the composite layer in this range can have both high light transmittance and high recombination rate.

[0096] In some embodiments, the composite layer is located on part or all of the surface of the first light-absorbing layer. In other words, the composite layer can be partially or fully covered on the first light-absorbing layer. Since the composite layer has a higher requirement for longitudinal conductivity in the thickness direction and a lower requirement for transverse conductivity, the composite layer on the first light-absorbing layer can be continuous or discontinuous. In a specific example, the composite layer is partially covered on the first light-absorbing layer, i.e., the composite layer is not fully covered on the surface of the first light-absorbing layer; specifically, the area ratio of the covered area to the uncovered area is 4 to 9:1, for example, the area ratio can be 4:1, 5:1, 6:1, 7:1, 8:1, 9:1.

[0097] The composite layer of the present application is prepared by a solution method, which has a higher porosity and thus a higher recombination rate than the composite layer prepared by an evaporation method or a sputtering method. In addition, since the particle size of the metal particles is in the nanometer level, the composite layer can have both high light transmittance and high recombination rate.

[0098] In some embodiments, the metal particles include at least one of gold particles, silver particles, platinum particles, and copper particles.

[0099] In some embodiments, the morphology of the metal particles includes at least one of spherical, quasi-spherical, flower-shaped, rod-shaped, cubic, hexagonal, triangular, and irregular shapes.

[0100] In some embodiments, the mass ratio of the metal particles to the organic active substance is 1:(0.5-50). Further, the mass ratio is 1:0.1-0.8. Generally, the organic active substance is in excess, and the metal surface can adsorb a limited amount of the organic active substance, so the mass ratio of the metal particles to the organic active substance in the composite layer is in the above range.

[0101] It can be understood that the above-mentioned stacked solar cell can be used in a solar cell including but not limited to a perovskite cell. In the perovskite stacked cell, at least one of the first light-absorbing layer and the second light-absorbing layer is a perovskite light-absorbing layer. Further, the stacked solar cell is a full perovskite stacked cell, i.e., both the first light-absorbing layer and the second light-absorbing layer are perovskite light-absorbing layers.

[0102] In some embodiments, each of the first light-absorbing layer and the second light-absorbing layer independently comprises a perovskite material comprising at least one of ABX3and A2CDX6, wherein A comprises at least one of a monovalent inorganic cation and a monovalent organic cation, B comprises at least one of a divalent inorganic cation and a divalent organic cation, C comprises at least one of a monovalent inorganic cation and a monovalent organic cation, D comprises at least one of a trivalent inorganic cation and a trivalent organic cation, and X comprises at least one of a monovalent inorganic anion and an organic anion.

[0103] It is appreciated that the materials in the first light-absorbing layer and the second light-absorbing layer can be the same or different.

[0104] In some embodiments, A comprises at least one of Li + , Na + , K + , Rb + , Cs + , a methylamine ion, an ethylamine ion, a propylamine ion, a butylamine ion, a pentylamine ion, a hexylamine ion, a formamidinium ion, and an imidazolium ion; B comprises at least one of a lead ion, a tin ion, a zinc ion, a titanium ion, an antimony ion, a bismuth ion, a nickel ion, an iron ion, a cobalt ion, a silver ion, a copper ion, a gallium ion, a germanium ion, a magnesium ion, a calcium ion, an indium ion, an aluminum ion, a manganese ion, a chromium ion, a molybdenum ion, and an europium ion; C comprises at least one of Cs + , Ag + , K + , and Rb + (a rubidium ion); D comprises at least one of Bi 3+ , Ni 3+ , Fe 3+ , Sb 3+ , In 3+ , and Cu 3+ ; and X comprises at least one of I - , Br - , Cl - , SCN - , HCOO - , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , CN - .

[0105] In some embodiments, the first light-absorbing layer is a wide-bandgap perovskite light-absorbing layer, the second light-absorbing layer is a narrow-bandgap perovskite light-absorbing layer, and the second light-absorbing layer is in direct contact with the composite layer. Since the composite layer contains the metal composite particles described above, the composite layer can be in direct contact with the narrow-bandgap perovskite, which can serve as both a composite layer and a hole transport layer, and has a higher recombination rate and a higher optical transmittance than ITO. Therefore, in some embodiments, the hole transport layer between the second light-absorbing layer and the composite layer can be omitted, which reduces the overall series resistance of the stacked solar cell and improves the overall light absorption of the stacked solar cell.

[0106] It can be understood that in some other embodiments of the present application, a hole transport layer can also be provided between the second light-absorbing layer and the composite layer.

[0107] In some embodiments, the first light-absorbing layer is a wide-bandgap perovskite light-absorbing layer, the second light-absorbing layer is a narrow-bandgap perovskite light-absorbing layer, and the first electrode is a transparent electrode, which facilitates the incidence of sunlight from the side of the wide-bandgap perovskite light-absorbing layer.

[0108] It can be understood that the "wide-bandgap" and "narrow-bandgap" in the above light-absorbing layer are relative, i.e., the bandgap of the first light-absorbing layer is greater than that of the second light-absorbing layer. In this way, sunlight is incident from the side of the wide-bandgap perovskite light-absorbing layer, in which the shorter-wavelength light is first absorbed and utilized by the wide-bandgap perovskite light-absorbing layer, and the longer-wavelength light can be transmitted into the narrow-bandgap perovskite light-absorbing layer and absorbed and utilized by the narrow-bandgap perovskite light-absorbing layer with a narrower bandgap, thereby maximizing the conversion of light energy into electrical energy and improving the utilization of light sources.

[0109] It can be understood that the above-mentioned solar cell can include but is not limited to the above-mentioned two light-absorbing layers, and three or more cells can be provided as needed to form a stacked cell. In some embodiments, the bandgap of the perovskite material in the narrow-bandgap perovskite light-absorbing layer is 0.9 eV to 1.6 eV, and the bandgap of the perovskite material in the wide-bandgap perovskite light-absorbing layer is 1.60 eV to 2.5 eV.

[0110] In some embodiments, the stacked solar cell further comprises a first charge transport layer disposed between the first electrode and the first light-absorbing layer.

[0111] In some embodiments, the stacked solar cell further comprises a second charge transport layer disposed between the first light-absorbing layer and the composite layer.

[0112] In some embodiments, the stacked solar cell further comprises a third charge transport layer disposed between the second light-absorbing layer and the composite layer.

[0113] In some embodiments, the tandem solar cell further comprises a fourth charge transport layer disposed between the second light absorbing layer and the second electrode.

[0114] In some embodiments, the tandem solar cell comprises a first charge transport layer and a second charge transport layer, one of the first and second charge transport layers is a hole transport layer and the other is an electron transport layer.

[0115] In some embodiments, the tandem solar cell comprises a third charge transport layer and the fourth charge transport layer, one of the third and fourth charge transport layers is a hole transport layer and the other is an electron transport layer.

[0116] The electron transport layer can enhance the separation and transport efficiency of electrons and holes, thereby effectively improving the conversion efficiency of the cell and prolonging the service life of the cell. The provision of the hole transport layer helps to extract and transport electrons / holes, which is conducive to improving the efficiency of the cell.

[0117] It can be understood that the components in the two layers of hole transport layers can be the same or different, and various hole transport materials commonly used in the art can be used; specifically, the hole transport layer comprises one or more of 2,2',7,7'-tetra(N,N-p-methoxyanilino)-9,9'-spirobifluorene, methoxytriphenylamine-fluoromethylformamide, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid, poly 3-hexyl thiophene, triptycene-core triphenylamine, 3,4-ethylenedioxythiophene-methoxytriphenylamine, N-(4-aniline)carbazole-spirobifluorene, polythiophene, phosphonic hole transport material, carbazolyl hole transport material, sulfonic hole transport material, a first metal oxide, cuprous iodide and cuprous thiocyanate, and the metal element in the first metal oxide includes at least one of Ni, Mo and Cu. Among them, the phosphonic hole transport material includes [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACz).

[0118] It can be understood that the components in the two layers of electron transport layers can be the same or different, and various electron transport materials commonly used in the art can be used; specifically, the electron transport layer comprises at least one of an imide compound, a quinone compound, fullerene and its derivative, methoxytriphenylamine-fluoromethylformamide, calcium titanate, lithium fluoride, calcium fluoride, a second metal oxide, silicon oxide, strontium titanate, cuprous thiocyanate; the metal element in the second metal oxide includes at least one of Mg, Ni, Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga and Cr.

[0119] Referring to FIG. 1, a stacked solar cell 10 according to an embodiment includes a first electrode 11, a first charge transport layer 12, a first light absorbing layer 13, a second charge transport layer 14, a recombination layer 15, a third charge transport layer 16, a second light absorbing layer 17, a fourth charge transport layer 18, and a second electrode 19, which are sequentially stacked.

[0120] In some embodiments, the first electrode and the second electrode can employ electrode materials commonly used in the art, including transparent conductive electrode materials and conductive metal materials; including but not limited to at least one of the following materials: fluorine-doped tin dioxide (FTO), tin-doped indium oxide (ITO), boron-doped zinc oxide (BZO) and aluminum zinc oxide (AZO), indium zinc oxide (IZO), tungsten-doped indium oxide (IWO), Ag, Cu, C, Au, Al, ITO, AZO, BZO, IZO, FTO, IWO.

[0121] In some embodiments, the first charge transport layer has a thickness of 0.01 nm to 200 nm, for example, 0.01 nm, 0.05 nm, 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, or 200 nm.

[0122] In some embodiments, the second charge transport layer has a thickness of 5 nm to 200 nm, for example, 5 nm, 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, or 200 nm.

[0123] In some embodiments, the third charge transport layer has a thickness of 0.01 nm to 200 nm, for example, 0.01 nm, 0.05 nm, 0.1 nm, 0.5 nm, 1 nm, 5 nm, 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, or 200 nm.

[0124] In some embodiments, the fourth charge transport layer has a thickness of 5 nm to 200 nm, for example, 5 nm, 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, or 200 nm.

[0125] In some embodiments, the first light absorbing layer has a thickness of 200 nm to 700 nm, for example, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, or 700 nm.

[0126] In some embodiments, the second light-absorbing layer has a thickness of 500 nm to 2000 nm, for example, 500 nm, 600 nm, 700 nm, 800 nm, 1000 nm, 1200 nm, 1500 nm, or 2000 nm.

[0127] In some embodiments, the stacked solar cell further comprises a metal diffusion barrier layer. Further, the metal diffusion barrier layer is disposed between the second charge transport layer and the recombination layer; and / or, the metal diffusion barrier layer is disposed between the third charge transport layer and the recombination layer. The metal diffusion barrier layer can separate the recombination layer from the charge transport layer, reduce the risk of damage to the charge transport layer, and thus improve the stability of the cell.

[0128] In some embodiments, the metal diffusion barrier layer has a thickness of 5 nm to 10 nm, for example, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or 10 nm, or any range defined by any two of the foregoing values.

[0129] In some embodiments, the metal diffusion barrier layer comprises at least one of a transparent conductive oxide and an elemental carbon material. Optionally, the transparent conductive oxide comprises at least one of fluorine-doped tin dioxide (FTO), tin-doped indium oxide (ITO), boron-doped zinc oxide (BZO), aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), and tungsten-doped indium oxide (IWO).

[0130] It is understood that the thickness of the metal diffusion barrier layer refers to the thickness of one metal diffusion barrier layer. When a metal diffusion barrier layer is disposed between the second charge transport layer and the recombination layer, and between the third charge transport layer and the recombination layer, the thickness of each metal diffusion barrier layer is independently selected from 5 nm to 10 nm, and the thickness and composition of each metal diffusion barrier layer can be the same or different.

[0131] In an embodiment of the present application, a method for preparing the stacked solar cell is also provided, comprising the following step S10.

[0132] Step S10: sequentially forming the first electrode, the recombination layer, and the second electrode to prepare the stacked solar cell.

[0133] The step of forming the recombination layer comprises the following step S12.

[0134] Step S12: coating the dispersion liquid containing the metal composite particles on the surface of the first electrode to form the recombination layer.

[0135] The solution coating method is used to form the composite layer, which is not only conducive to forming the metal composite particles containing the organic active substance, but also improves the contact between the composite layer and other functional layers such as the light-absorbing layer, which is equivalent to forming a buffer zone between the metal particles and other functional layers such as the light-absorbing layer, thereby reducing the series resistance and further improving the fill factor FF of the battery. Moreover, compared with the composite layer prepared by the evaporation method or the sputtering method, the composite layer prepared by the solution coating method has higher porosity, and thus has higher composite rate. In this way, the photoelectric conversion efficiency of the prepared battery can be improved.

[0136] In some embodiments, step S12 comprises the following steps: reducing the metal salt and the organic active substance in the solvent to prepare a dispersion liquid containing the metal composite particles. In the above preparation method, the metal salt and the organic active substance are reduced in the solvent, and the organic active substance can act as a reducing agent to reduce the metal salt to form the metal particles, and further act as a stabilizer to be arranged on the surface of the metal particles. The prepared dispersion liquid contains the metal composite particles, and the metal composite particles comprise the metal particles and the organic active substance arranged on the surface of the metal particles. After the dispersion liquid is coated on the surface of the first electrode and dried, the metal composite particles are loaded on the surface of the metal particles.

[0137] The above dispersion liquid containing the metal composite particles can be purchased, prepared by a known preparation method, or prepared by the above preparation method of the present application.

[0138] In some embodiments, in the dispersion liquid, the concentration of the metal particles is 0.01 mg / mL to 10 mg / mL, and the concentration of the organic active substance is 0.005 mg / mL to 50 mg / mL. For example, the concentration of the metal particles can be 0.01 mg / mL, 0.02 mg / mL, 0.05 mg / mL, 0.1 mg / mL, 0.5 mg / mL, 1 mg / mL, 5 mg / mL, or 10 mg / mL. For example, the concentration of the organic active substance can be 0.005 mg / mL, 0.01 mg / mL, 0.02 mg / mL, 0.05 mg / mL, 0.1 mg / mL, 0.5 mg / mL, 1 mg / mL, 5 mg / mL, 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL, or 50 mg / mL.

[0139] Further, in the dispersion liquid, the molar ratio of the metal element in the metal salt to the organic active substance is 1:(0.1-5), for example, 1:0.1, 1:0.5, 1:1, 1:1.1, 1:1.2, 1:1.5, 1:2, 1:3, 1:4, or 1:5. Further, the molar ratio is 1:(1.1-1.2).

[0140] In some embodiments, the temperature of the reduction reaction is between 50°C and 300°C. Further, the time of the reduction reaction can be between 10 and 30 minutes. As an example, the temperature of the reduction reaction can be 50°C, 60°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, 230°C, 250°C, 300°C. As an example, the time of the reduction reaction can be 10, 15, 20, 30 minutes.

[0141] In some embodiments, the metal ion in the metal salt includes, but is not limited to, at least one of gold ion, silver ion, platinum ion, and copper ion. Further, the metal salt includes, but is not limited to, at least one of chloroauric acid, chloroplatinic acid, silver nitrate, copper nitrate.

[0142] In some embodiments, metal seeds are added in the reduction reaction. The metal seeds induce the formation of metal particles. The metal seeds can be commercially available or prepared by known methods. In a specific example, a metal salt solution is taken, and PVP and metal seeds are mixed. Then, ascorbic acid, citrate, or other organic active substances are added to perform the reduction reaction, and gold nanoparticle dispersion is obtained.

[0143] Further, in the reduction reaction, other surfactants can be added in addition to the organic active substances described above. The surfactants include, but are not limited to, polyvinylpyrrolidone (PVP).

[0144] It is understood that metal seeds can not be added in the reduction reaction. In a specific example, a metal salt solution is taken, and ascorbic acid, citrate, or other organic active substances are added to perform the reduction reaction, and gold nanoparticle dispersion is obtained.

[0145] In some embodiments, after the step of the reduction reaction, a step of centrifugal treatment of the reaction solution obtained in the reaction is further included. After the centrifugal treatment, part of the supernatant is removed, and the purpose of concentration of the reaction solution is achieved.

[0146] Further, the concentrated dispersion obtained after the centrifugal treatment is directly subjected to subsequent coating treatment without solid-liquid separation and water washing, so as to retain the citrate in the dispersion as much as possible. The coating treatment includes, but is not limited to, spin coating, spraying, blade coating, and slot coating.

[0147] In some embodiments, the centrifugal treatment is performed at a speed of 10,000 rpm to 20,000 rpm for 10 minutes to 600 minutes.

[0148] In some embodiments, after the step of coating, a step of annealing treatment of the wet film after coating is further included. In this way, water and other solvents in the wet film are removed, and a dry composite layer is formed.

[0149] Further, the temperature of the annealing treatment is 50-100℃, and the time is 2-30 minutes, which can remove most of the water and other solvents in the wet film.

[0150] It can be understood that each functional layer of the above-mentioned stacked solar cell can be prepared by a conventional preparation method in the art. For example, the preparation process of the first charge transport layer, the second charge transport layer, the third charge transport layer, the fourth charge transport layer, the first light absorption layer, and the second light absorption layer can adopt any one of the conventional preparation methods in the art, including solution method and solid deposition method. The solution method includes any one of spin coating, spraying, blade coating, and slot coating, etc. The solid deposition method includes any one of vacuum evaporation, sputtering deposition, plasma deposition, and ion deposition.

[0151] In an embodiment of the present application, a photovoltaic module is also provided, which comprises the above-mentioned stacked solar cell or the stacked solar cell prepared by the above-mentioned preparation method of the stacked solar cell.

[0152] In the above-mentioned photovoltaic module, one or more stacked solar cells are included, which can be selected according to the specific application scenario. Further, in the above-mentioned photovoltaic module, a plurality of stacked solar cells are included, which are connected in series or in parallel to form a cell piece.

[0153] In some embodiments, the above-mentioned photovoltaic module further comprises a photovoltaic glass layer, an adhesive layer, and a back plate.

[0154] The two surfaces of the cell piece are respectively provided with an adhesive layer. The surface of one of the adhesive layers away from the cell piece is provided with a back plate, and the surface of the other adhesive layer away from the cell piece is provided with a photovoltaic glass layer.

[0155] The photovoltaic glass layer and the back plate are used to protect the solar cell, and are sealed, insulated, and waterproof. The adhesive layer plays a role of bonding the photovoltaic glass layer and the cell piece, and bonding the back plate and the cell piece.

[0156] Optionally, the material of the photovoltaic glass layer is tempered glass, the material of the back plate is TPT (polyvinyl fluoride) or TPE (thermoplastic elastomer), and the material of the adhesive layer is EVA (polyethylene-polyvinyl acetate copolymer).

[0157] Further, the above-mentioned photovoltaic module further comprises a junction box and an outer frame.

[0158] The junction box is used to protect the power generation system of the entire photovoltaic module, and it is equivalent to a current transfer station. When a short circuit occurs in the cell piece, the junction box will automatically disconnect the short-circuited cell string.

[0159] The outer frame can play a role of supporting and protecting the entire photovoltaic module. The frame can be made of aluminum alloy, which has excellent strength and corrosion resistance.

[0160] Further, the connection between the frame and other parts of the photovoltaic module is bonded and sealed by silica gel. The photovoltaic module can convert solar energy into electric energy, which can be stored in a battery or used to drive a load.

[0161] In some embodiments, the photovoltaic module is a solar cell panel.

[0162] In an embodiment of the present application, a photovoltaic system is also provided, which includes the photovoltaic module.

[0163] The photovoltaic system uses the photovoltaic effect of the solar cell in the photovoltaic module to directly convert solar radiation energy into electric energy, which has high efficiency. Further, the photovoltaic system is a photovoltaic power generation system.

[0164] The photovoltaic module is the core part of the photovoltaic power generation system. In the photovoltaic system, one or more photovoltaic modules are included, which can be selected according to the specific application scenario. Further, when multiple photovoltaic modules are included in the photovoltaic system, the multiple photovoltaic modules form a photovoltaic array.

[0165] The photovoltaic system can be an independent photovoltaic power generation system or a grid-connected photovoltaic power generation system.

[0166] The independent photovoltaic power generation system includes a photovoltaic array, a battery pack, a charge controller, a power electronic converter (inverter), a load, etc. Its working principle is that solar radiation energy is first converted into electric energy by the photovoltaic array, and then the electric energy is converted by the power electronic converter to supply power to the load. At the same time, the excess electric energy is stored in the energy storage device in the form of chemical energy through the charge controller. In this way, when the sunlight is insufficient, the energy stored in the battery can be converted into AC 220V, 50Hz electric energy through the power electronic inverter, filtering and power transformer to supply the AC load.

[0167] The grid-connected photovoltaic power generation system includes a photovoltaic array, a high-frequency DC / DC boost circuit, a power electronic converter (inverter), and system monitoring. Its working principle is that solar radiation energy is converted by the photovoltaic array, and then converted into high-voltage direct current through the high-frequency DC / DC boost circuit. Then, the high-voltage direct current is inverted by the power electronic inverter to output a sinusoidal alternating current with the same frequency and voltage as the grid voltage.

[0168] The two photovoltaic power generation systems have different characteristics and can be selected according to the specific application scenario.

[0169] In an embodiment of the present application, an electric device is also provided, which includes the laminated solar cell or the laminated solar cell prepared by the preparation method of the laminated solar cell or the photovoltaic module.

[0170] The above-mentioned power utilization device can be, but is not limited to, a mobile device, an electric vehicle, an electric train, a ship and a satellite, an energy storage system, etc.

[0171] In some embodiments, the mobile device can be a mobile phone or a notebook computer, etc.

[0172] In some embodiments, the electric vehicle includes, but is not limited to, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.

[0173] Another embodiment of the present application further provides a power generation device comprising the above-mentioned laminated solar cell or the laminated solar cell prepared by the above-mentioned method for preparing a laminated solar cell or the above-mentioned photovoltaic module.

[0174] The above-mentioned power generation device can be, but is not limited to, a solar generator set, etc.

[0175] The present application will be described in detail below with reference to specific embodiments, but the present application is not limited to the following embodiments. It should be understood that the appended claims generalize the scope of the present application, and those skilled in the art should realize that certain changes to the embodiments of the present application will be covered by the spirit and scope of the claims of the present application.

[0176] The following are specific embodiments.

[0177] Embodiment 1

[0178] (1) Preparation of the dispersion solution:

[0179] In a 100 mL round bottle flask equipped with a condenser, 3.3 mL of HAuCl4 solution (25.4 mmol / L) was added, followed by 50 mL of ultrapure water. Under stirring, it was heated to boiling, and then 5 mL of sodium citrate solution (38.8 mmol / L) was quickly injected. After one minute, the color of the solution changed from light yellow to black. The solution was kept at 100°C for 15 minutes until it turned wine red. The reaction solution was gradually cooled to room temperature and then centrifuged at 11000 RPM for 10 min. Part of the supernatant was removed to obtain a concentrated dispersion solution, which was stored at 4°C for standby.

[0180] The concentration of gold particles in the dispersion solution was 0.01 mg / mL, and the concentration of citrate was 0.02 mg / mL, as determined by ion chromatography.

[0181] (2) Preparation of the laminated solar cell, the specific steps are as follows:

[0182] 1. The material of the first electrode is indium tin oxide (ITO). The indium tin oxide (ITO) is cleaned with acetone-alcohol-deionized water in sequence and then dried for later use.

[0183] 2. First charge transport layer (first hole transport layer): [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphoric acid (MeO-4PACz) was added to ethanol solvent and stirred to obtain an ethanol solution of MeO-4PACz. The ethanol solution of MeO-4PACz was spin-coated onto the surface of the first electrode at a spin speed of 4000 rpm for 30 s. Then, it was transferred to a hot plate and annealed at 100 °C for 10 min to form the first charge transport layer.

[0184] 3. First Absorbing Layer: 3 mg FAI, 59 mg FABr, 46 mg CsI, 25 mg CsBr, 428 mg PbI2, and 209 mg PbBr2 were added to 1 mL of a mixture of DMF and DMSO (DMF to DMSO volume ratio 3:1). The mixture was stirred at 600 rpm for 8 hours using a magnetic stirrer, filtered, and the perovskite precursor solution was obtained. 100 μL of the perovskite precursor solution was spin-coated onto the above-mentioned layer. On the first charge transport layer, spin coating is first performed at a speed of 2000 rpm and an acceleration of 200 rpm / s for 10 s, then at a speed of 4000 rpm and an acceleration of 1000 rpm / s for 25 s. Then, 200 μL of chlorobenzene is added dropwise to the spin-coated perovskite precursor solution, followed by spin coating of the perovskite precursor solution at a speed of 4000 rpm for 15 s. Finally, the solution is transferred to a hot stage and annealed at 100 °C for 15 min to form the first light-absorbing layer.

[0185] 4. Second charge transport layer (first electron transport layer): A 20 nm thick SnO2 layer is prepared on the first light-absorbing layer using an atomic layer deposition (ALD) device as the second charge transport layer.

[0186] 5. Composite layer: The dispersion prepared above is spin-coated on the second charge transport layer at a spin coating speed of 4000 rpm and an acceleration of 1000 rpm / s for 30 s, and finally dried at 100℃ for 10 min to obtain the composite layer.

[0187] 6. Third charge transport layer (second hole transport layer): Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is spin-coated onto the above composite layer at a spin speed of 4000 rpm for 30 s. Then, it is transferred to a hot plate and annealed at 150°C for 10 min to form the third charge transport layer.

[0188] 7、the second light-absorbing layer: 2 mg of CH(NH2)2I, 85 mg of CH3NH2I, 4 mg of PbI2, 335 mg of SnI2, and 0.5 mg of MeO-4PACz were added to 1 mL of a mixed solvent of DMF and DMSO (volume ratio of DMF to DMSO was 3:1), stirred on a magnetic stirrer at a speed of 600 rpm for 2 h, filtered, and a perovskite precursor solution was prepared; 100 μL of the perovskite precursor solution was spin-coated onto the third carrier transport layer (first spin-coating at a speed of 1000 rpm and an acceleration of 200 rpm / s for 10 s, and then second spin-coating at a speed of 3000 rpm and an acceleration of 1000 rpm / s for 20 s), then 350 μL of ethyl acetate was added dropwise to the spin-coated perovskite precursor solution, and then the perovskite precursor solution was spin-coated again (spin-coating at a speed of 4000 rpm for 20 s), and then transferred to a hot stage for annealing at 100°C for 10 min to form the second light-absorbing layer.

[0189] 8、the fourth charge transport layer (second electron transport layer): a layer of 10 nm thick bathocuproine (BCP) was evaporated on the second light-absorbing layer as the fourth charge transport layer.

[0190] 9、a layer of 100 nm thick copper (Cu) was evaporated on the fourth charge transport layer as the second electrode to prepare the stacked solar cell.

[0191] (3) Characterization test: the thickness of the composite layer was tested by SEM, and the average thickness was obtained by multiple sampling tests, as shown in Table 1. The average particle size of the gold particles in the composite layer was tested by SEM, and the average particle size of the metal particles was obtained by averaging the particle sizes of multiple gold particles, as shown in Table 1.

[0192] The composite layer prepared above was observed under a scanning electron microscope, and the scanning electron microscope image is shown in FIG. 2. The types and contents of metal elements and organic active substances were determined by EDX (X-ray energy spectrum) sampling, and the results showed that the granular substance formed on the surface was gold particles and contained sodium citrate.

[0193] In addition, the scanning electron microscope results of the composite layer showed that the area ratio of the covered area of the composite layer to the area not covered by the composite layer was 6:1.

[0194] (4) Performance test: the photoelectric conversion efficiency was determined by I-V measurement method, and the specific steps were as follows:

[0195] a) The test fixture with the sample cell was placed on the sample holder, so that it was located in the measurement plane, and the sample cell was ensured to be located at the center position of the exit light spot of the solar simulator (or the normal line of the photovoltaic cell was parallel to the center line of the light source exit light beam of the solar simulator);

[0196] b) Test in accordance with national standard IEC 61215 using a solar simulator with an irradiance of 1000 W / m 2 2, calibrated with a crystalline silicon solar cell to give an AM 1.5 solar spectrum at 1000 W / m m 2. The sample cell is masked and temperature controlled to maintain the sample temperature at (30±5) °C during the measurement.

[0197] c) Set the scan direction, voltage range, scan interval voltage and scan interval time. It is recommended that the scan interval is not greater than 0.02 V, and the interval time between adjacent points is not less than 0.3 s. Measure the forward and reverse scan current-voltage characteristics of the sample cell, and record the maximum power point current V oc , open circuit voltage V sc and short circuit current J m .

[0198] Calculation formula: fill factor FF = J m ×V oc / V sc ×J oc , electrical conversion efficiency PCE = V sc ×J in ×FF / P in . P 3 is the incident light intensity (1000 W / m 2 ).

[0199] d) Aging test to evaluate the stability of the cell.

[0200] Place the perovskite solar cell at 65 °C under continuous irradiation of a light source of 100 mW / cm 2 2, and track the change of its photoelectric conversion efficiency with aging time. The time required for its photoelectric conversion efficiency to decay to 80% of the initial efficiency is recorded as T 80 , and the size of this parameter indicates the stability of the perovskite solar cell (the test results are rounded to the nearest integer multiple of 10).

[0201] The specific test results are shown in Table 1.

[0202] Examples 2-7

[0203] Examples 2-7 are basically the same as Example 1, except that at least one of the gold particle size and the thickness of the composite layer is different, as shown in Table 1.

[0204] The gold particle size can be adjusted by adjusting the amount of sodium citrate solution added in the preparation of the dispersion in step (1) to make the average particle size of the gold particles in the prepared dispersion different; the thickness of the composite layer can be achieved by adjusting the spin coating time during the preparation of the composite layer.

[0205] The remaining steps are the same as in Example 1, and the specific results are shown in Table 1.

[0206] Example 8

[0207] The same as Example 1, except that in the preparation of the stacked solar cell in step (2), the preparation of the third charge transport layer (second hole transport layer) is omitted, i.e. no second hole transport layer is provided between the composite layer and the second light absorbing layer, and the composite layer and the second light absorbing layer are in direct contact.

[0208] Example 9

[0209] Example 9 is basically the same as Example 1, except that in the preparation of the stacked solar cell in step (2), before the preparation of the third charge transport layer, the following steps are further included:

[0210] A layer of 5 nm ITO is prepared on the composite layer using an ALD device as a metal diffusion inhibiting layer.

[0211] The other steps and conditions are the same as in Example 1, and the specific results are shown in Table 1.

[0212] Example 10

[0213] Example 10 is basically the same as Example 1, except that in the preparation of the stacked solar cell in step (2), before the preparation of the composite layer, the following steps are further included:

[0214] A layer of 5 nm ITO is prepared on the second charge transport layer using an ALD device as a metal diffusion inhibiting layer.

[0215] The other steps and conditions are the same as in Example 1, and the specific results are shown in Table 1.

[0216] Example 11

[0217] Example 11 is basically the same as Example 1, except that in step (1) the preparation of the dispersion is as follows:

[0218] Take 1 mL of 50 mol·L -1AuCl4 solution, diluted with deionized water to 35 mL, 555.0 mg PVP was added, the mixture was stirred at 0°C for 30 min, then Au-1.9 seed (i.e. seed with size of 1.9 nm) was added, the mixture was stirred for another 30 min, then 1 mL freshly prepared ascorbic acid solution (5.0 mmol·L -1 ) was added dropwise, after the addition was completed, the mixture was stirred for another 2 h, centrifuged, and the solution containing gold particles was reserved to obtain a gold nanoparticle dispersion.

[0219] The other steps and conditions were the same as in Example 1, and the specific results can be seen in Table 1.

[0220] Comparative Example 1

[0221] Comparative Example 1 was basically the same as Example 1, except that in step (2) the preparation of the composite layer of the tandem solar cell was as follows:

[0222] A layer of 1 nm elemental gold (Au) was evaporated on the second charge transport layer as the composite layer using an evaporation device.

[0223] The remaining steps were the same as in Example 1, and the specific results can be seen in Table 1.

[0224] Comparative Example 2

[0225] Comparative Example 2 was basically the same as Example 1, except that in step (1) the dispersion was prepared as follows:

[0226] First, 5 mg of metallic indium was dissolved in 10 mL of a hydrochloric acid solution, and then tin tetrachloride was dissolved in the indium chloride hydrochloric acid solution. After stirring to uniformity, 2.23 mg of triethanolamine, 10 mL of distilled water, and 1.5 mg of polyvinylpyrrolidone were added to a three-necked flask, and the pH value was adjusted with hydrochloric acid. The three-necked flask was then placed in an 80°C constant-temperature bath, and the prepared indium-tin mixed hydrochloric acid solution was added dropwise to the above solution. White silk precipitate was produced, and the pH value gradually increased. Ammonia water was continuously added under strong stirring to keep the bottom solution at a constant pH value. After the indium-tin mixed hydrochloric acid solution was added dropwise, the stirring was continued, and after 10 min, the solution containing indium-tin hydroxide was centrifuged, and the precipitate was washed with water and then centrifuged again. This process was repeated 3-5 times, and the centrifuged indium-tin hydroxide precipitate was dried. The ITO particles were obtained by heat treatment of the dried indium-tin hydroxide precipitate at 150°C under a nitrogen atmosphere for 2 hours. The ITO nanoparticles dispersion was obtained by adding the ITO particles to an IPA solvent (isopropyl alcohol) and adding 2 mg of a polyethylene glycol dispersant and stirring under ultrasonic conditions.

[0227] The remaining steps were the same as in Example 1, and the specific results can be seen in Table 1. The scanning electron microscope image of the composite layer is shown in FIG. 3.

[0228] The parameters and performance test results of some embodiments and comparative examples are shown in Table 1.

[0229] Table 1

[0230] From the test results of Examples 1-11 and Comparative Examples 1-2 in the above table, it can be seen that the use of the composite layer containing specific components in the present application can improve the photoelectric conversion efficiency of the battery.

[0231] The technical features of the above-described embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict, they should be considered as falling within the scope of the present disclosure.

[0232] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A tandem solar cell, comprising a first electrode, a first light-absorbing layer, a composite layer, a second light-absorbing layer, and a second electrode stacked together; the composite layer comprising metal composite particles, wherein the metal composite particles comprise metal particles and an organic active substance disposed on the surface of the metal particles.

2. The tandem solar cell as described in claim 1, wherein, The organic active substance includes at least one of reducing surfactants, ionic surfactants, polyolefins, polyethylene glycol, polyethylene wax, vinyl bis-stearamide, glyceryl monostearate, and glyceryl tristearate, wherein the reducing surfactant is reducing and contains an acid radical ion.

3. The tandem solar cell according to any one of claims 1 to 2, wherein, The reducing surfactant includes at least one of citrate and ascorbic acid.

4. The tandem solar cell according to any one of claims 1 to 3, wherein, The average particle size of the metal particles is 2 nm to 30 nm.

5. The tandem solar cell as described in claim 4, wherein, The average particle size of the metal particles is 2 nm to 10 nm.

6. The tandem solar cell according to any one of claims 1 to 5, wherein, The thickness of the composite layer is 2nm to 90nm.

7. The tandem solar cell as claimed in claim 6, wherein, The thickness of the composite layer is 2nm to 20nm.

8. The tandem solar cell according to any one of claims 1 to 7, wherein, The composite layer is located on part or all of the surface of the first light-absorbing layer.

9. The tandem solar cell according to any one of claims 1 to 8, wherein, The stacked solar cell satisfies one or more of the following conditions (1) and (2): (1) The metal particles include at least one of gold particles, silver particles, platinum particles and copper particles; (2) The morphology of the metal particles includes at least one of the following: spherical, near-spherical, flower-shaped, rod-shaped, cubic, hexagonal, triangular and irregular shapes.

10. The tandem solar cell according to any one of claims 1 to 9, wherein, The mass ratio of the metal particles to the organic active substance is 1:(0.1-10).

11. The tandem solar cell according to any one of claims 1 to 10, wherein, The first light-absorbing layer and the second light-absorbing layer each independently comprise a perovskite material, wherein the perovskite material comprises at least one of ABX3 and A2CDX6; Wherein, A includes at least one of monovalent inorganic cations and monovalent organic cations; B includes at least one of divalent inorganic cations and divalent organic cations; C includes at least one of monovalent inorganic cations and monovalent organic cations; D includes at least one of trivalent inorganic cations and trivalent organic cations; X includes at least one of monovalent inorganic anions and organic anions.

12. The tandem solar cell of claim 11, wherein, A includes Li + Na + K + 、Rb + Cs + At least one of the following: methylamine ion, ethylamine ion, propylamine ion, butylamine ion, pentamine ion, hexamine ion, formamidinium ion, and imidazole ion; B includes at least one of the following: lead ion, tin ion, zinc ion, titanium ion, antimony ion, bismuth ion, nickel ion, iron ion, cobalt ion, silver ion, copper ion, gallium ion, germanium ion, magnesium ion, calcium ion, indium ion, aluminum ion, manganese ion, chromium ion, molybdenum ion, and europium ion; C includes Cs + Ag + K + and Rb + At least one of them; D includes Bi 3+ Ni 3+ Fe 3+ Sb 3+ In 3+ , and Cu 3+ At least one of them; X includes I - ,Br - Cl - SCN - HCOO - CH3COO - CF3COO - CH3SO3 - CF3SO3 - CN - At least one of them.

13. The tandem solar cell according to any one of claims 1 to 12, wherein, The first light-absorbing layer is a wide-bandgap perovskite light-absorbing layer, and the second light-absorbing layer is a narrow-bandgap perovskite light-absorbing layer.

14. The tandem solar cell of claim 13, wherein, The second light-absorbing layer is in direct contact with the composite layer.

15. The tandem solar cell according to any one of claims 1 to 14, wherein, The stacked solar cell satisfies one or more of the following conditions (1) and (4): (1) The stacked solar cell further includes a first charge transport layer, which is disposed between the first electrode and the first light-absorbing layer; (2) The stacked solar cell further includes a second charge transport layer, which is disposed between the first light-absorbing layer and the composite layer; (3) The stacked solar cell further includes a third charge transport layer, which is disposed between the second light-absorbing layer and the composite layer; (4) The stacked solar cell further includes a fourth charge transport layer, which is disposed between the second light-absorbing layer and the second electrode.

16. The tandem solar cell of claim 15, wherein, The stacked solar cell satisfies one or both of the following conditions (1) and (2): (1) The stacked solar cell includes a first charge transport layer and a second charge transport layer, wherein one of the first charge transport layer and the second charge transport layer is a hole transport layer and the other is an electron transport layer; (2) The stacked solar cell includes the third charge transport layer and the fourth charge transport layer, wherein one of the third charge transport layer and the fourth charge transport layer is a hole transport layer and the other is an electron transport layer.

17. The tandem solar cell of claim 16, wherein, The stacked solar cell satisfies one or both of the following conditions (1) and (2): (1) The hole transport layer comprises one or more of 2,2',7,7'-tetratetra(N,N-p-methoxyaniline)-9,9'-spirodifluorene, methoxytriphenylamine-fluoroformamidinium, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly(3,4-ethylenedioxythiophene): polystyrene sulfonic acid, poly3-hexylthiophene, triphenylamine with a triphenylene core, 3,4-ethylenedioxythiophene-methoxytriphenylamine, N-(4-aniline)carbazole-spirodifluorene, polythiophene, phosphate-based hole transport material, carbazole-based hole transport material, sulfonic acid-based hole transport material, a first metal oxide, cuprous iodide, and cuprous thiocyanate, wherein the metal element in the first metal oxide comprises at least one of Ni, Mo, and Cu; (2) The electron transport layer comprises at least one of imide compounds, quinone compounds, fullerenes and their derivatives, methoxytriphenylamine-fluoroformamidine, calcium titanate, lithium fluoride, calcium fluoride, second metal oxide, silicon oxide, strontium titanate, and cuprous thiocyanate; the metal element in the second metal oxide comprises at least one of Mg, Ni, Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, and Cr.

18. The tandem solar cell according to any one of claims 15 to 17, wherein, The stacked solar cell further includes a metal diffusion suppression layer, which satisfies one or both of the following conditions (1) to (2): (1) The metal diffusion suppression layer is disposed between the second charge transport layer and the composite layer; (2) The metal diffusion suppression layer is disposed between the third charge transport layer and the composite layer.

19. The tandem solar cell of claim 18, wherein, The suppression metal layer satisfies one or both of the following conditions (1) to (2): (1) The thickness of the metal diffusion suppression layer is 5 nm to 10 nm; (2) The metal diffusion suppression layer includes at least one of transparent conductive oxide and carbon elemental material.

20. The method for preparing a tandem solar cell according to any one of claims 1 to 19, wherein, Includes the following steps: The first electrode, the composite layer, and the second electrode are formed sequentially to prepare the stacked solar cell; The steps for forming the composite layer include the following: A dispersion containing metal composite particles is coated onto the surface of the first electrode to form the composite layer; wherein the metal composite particles include metal particles and organic active substances disposed on the surface of the metal particles.

21. The method for preparing a tandem solar cell as described in claim 20, wherein, In the dispersion, the concentration of the metal particles is 0.01 mg / mL to 10 mg / mL, and the concentration of the organic active substance is 0.005 mg / mL to 50 mg / mL.

22. The method for preparing a tandem solar cell according to any one of claims 20-21, wherein, The method for preparing the dispersion containing metal composite particles includes the following steps: A dispersion containing metal composite particles is prepared by reducing the metal salt with the organic active substance in a solvent. Metal seed crystals may or may not be added to the reduction reaction.

23. The method for preparing a tandem solar cell as described in claim 22, wherein, The preparation method satisfies one or two of the conditions in (1) to (2): (1) The molar ratio of the metal element in the metal salt to the organic active substance is 1:(0.1~5); (2) The temperature of the reduction reaction is 50℃~300℃.

24. A photovoltaic module, wherein, This includes tandem solar cells prepared by any one of claims 1 to 19 or by any one of claims 20 to 23.

25. A photovoltaic system, wherein, Including the photovoltaic module as described in claim 24.

26. An electrical appliance, wherein, This includes tandem solar cells as described in any one of claims 1 to 19, tandem solar cells prepared by any one of claims 20 to 23, or photovoltaic modules as described in claim 24.

27. A power generation device, wherein, This includes tandem solar cells as described in any one of claims 1 to 19, tandem solar cells prepared by any one of claims 20 to 23, or photovoltaic modules as described in claim 24.

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