Perovskite battery, preparation method of electron transport layer of perovskite battery, perovskite battery assembly, laminated battery, power utilization device and power generation device

Abstract

The invention provides a perovskite battery, a preparation method of an electron transport layer of the perovskite battery, a perovskite battery assembly, a laminated battery, a power utilization device and a power generation device. The perovskite cell comprises the following structures which are arranged in a laminated manner: a perovskite layer which comprises perovskite crystal grains; and an electron transport layer, the average roughness of the electron transport layer being 8 nm to 20 nm. According to the perovskite cell provided by the embodiment of the invention, the electron transport layer can better cover perovskite crystal grains, so that the energy conversion efficiency of the perovskite cell is improved; the invention also aims to provide a preparation method of the electron transport layer of the perovskite battery, a perovskite battery assembly, a laminated battery, a power utilization device and a power generation device with the above beneficial effects.

Description

Technical Field

[0001] This application relates to the technical field of perovskite battery devices, and specifically relates to a perovskite battery, a preparation method of an electron transport layer of a perovskite battery, a perovskite battery module, a tandem battery, an electrical device, and a power generation device. Background Art

[0002] Green and environmentally friendly renewable energy is the key direction for the future development of energy technologies. Solar cells based on perovskite batteries can directly convert solar energy into electrical energy under sunlight irradiation, and are new energy technologies that have received increasing attention.

[0003] For perovskite batteries, how to improve the comprehensive performance is the key research direction. Summary of the Invention

[0004] The purpose of this application is to provide a perovskite battery, in which the electron transport layer can better cover the perovskite grains and improve the energy conversion efficiency of the perovskite battery; the purpose of this application is also to provide a preparation method of the electron transport layer of a perovskite battery, a perovskite battery module, a tandem battery, an electrical device, and a power generation device, in which the electron transport layer can better cover the perovskite grains, so as to obtain improved energy conversion efficiency.

[0005] In a first aspect, an embodiment of this application provides a perovskite battery, including the following structures stacked:

[0006] A perovskite layer, including perovskite grains;

[0007] An electron transport layer, wherein the average roughness of the electron transport layer is 8 nm to 20 nm.

[0008] According to the embodiment of this application, the average roughness is a measure of the unevenness or irregularity of the surface, used to describe the minute irregular features or geometric structures on the surface of the perovskite layer. The average roughness is the average value of all height values on the surface, used to represent the overall irregularity of the surface. Usually, the method of area sampling is selected for detection.

[0009] According to the embodiments of the present application, in the prepared perovskite solar cell, the average roughness of the electron transport layer is within the above range, which reduces the exposure of the tops of perovskite grains due to the aggregation of the first electron transport layer in the depressions between perovskite grains, and also removes the tip portions of individual relatively high perovskite grains, so that the electron transport layer completely covers the perovskite grains, reducing the average roughness of the electron transport layer, improving the thickness uniformity of the perovskite layer, and improving the energy conversion efficiency and stability of the perovskite solar cell. It avoids the situation where, directly according to the traditional method, the roughness of the perovskite layer is relatively large, about 30 nm, resulting in a relatively high average roughness of the electron transport layer, such as 28 nm, and the relatively high average roughness of the electron transport layer affects the energy conversion efficiency and stability of the perovskite solar cell.

[0010] In any embodiment of the present application, the average roughness of the perovskite layer is 10 nm to 30 nm, and the average roughness is represented by the standard deviation of the grain lengths of perovskite grains along the thickness direction of the perovskite layer.

[0011] According to the embodiments of the present application, in the prepared perovskite solar cell, the average roughness of the surface of the perovskite layer is within the above range, avoiding the situation where, directly according to the traditional method, the roughness of the perovskite layer is relatively large, such as above 32 nm, which affects the energy conversion efficiency and stability of the perovskite solar cell. For the perovskite solar cell according to the embodiments of the present application, through preparation, the average roughness of the perovskite layer is 10 nm to 30 nm, avoiding the exposure of the tops of perovskite grains due to the aggregation of the first electron transport layer in the depressions between perovskite grains, and also removing the tip portions of individual relatively high perovskite grains, so that the electron transport layer completely covers the perovskite grains, reducing the average roughness of the electron transport layer, improving the thickness uniformity of the perovskite layer, and improving the energy conversion efficiency and stability of the perovskite solar cell.

[0012] In any embodiment of the present application, the average length of perovskite grains along the thickness direction of the perovskite layer is 400 nm to 600 nm.

[0013] According to the embodiments of the present application, the average length of perovskite grains being within the above range is beneficial to the energy conversion efficiency and stability of the perovskite solar cell.

[0014] The present application does not make specific restrictions on the material of the electron transport layer, and any material that can achieve the well-known electron transport layer in the art can be used. In any embodiment of the present application, the electron transport layer includes one or more of organic electron transport materials, inorganic electron transport materials, organic-inorganic hybrid electron transport materials and their derivatives, and optionally includes one or more of imide compounds, quinone compounds, fullerenes and their derivatives, metal oxides, silicon oxides, strontium titanate, calcium titanate, lithium fluoride and calcium fluoride.

[0015] In any embodiment of the present application, the fullerenes and their derivatives include one or more of methyl [6,6]-phenyl C71 butyrate and methyl [6,6]-phenyl C61 butyrate;

[0016] In any embodiment of the present application, the metal elements in the metal oxide include one or more of Mg, Cd, Zn, In, Pb, W, Sb, Bi, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, and Cr.

[0017] In some alternative embodiments, the electron transport layer includes a first electron transport layer and a second electron transport layer. The first electron transport layer includes PC61BM, and the second electron transport layer includes zinc peroxide.

[0018] The present application does not specifically limit the structure of the perovskite battery, and any structure that can achieve the perovskite battery well-known in the art can be used. In any embodiment of the present application, the perovskite battery includes a first electrode, a hole transport layer, a perovskite layer, an electron transport layer, and a second electrode.

[0019] In a second aspect, an embodiment of the present application provides a method for preparing an electron transport layer of a perovskite battery. The preparation method includes:

[0020] Coating a first electron transport layer solution on the surface of the perovskite layer, wherein the perovskite layer includes perovskite grains;

[0021] After drying to remove the solvent in the first electron transport layer solution, coating a polar organic solution on the surface of the perovskite layer; wherein the polar organic solution includes a polar organic solvent that can dissolve perovskite grains;

[0022] After drying to remove the polar organic solvent, continue to coat a second electron transport layer solution on the surface of the perovskite layer;

[0023] After drying to remove the solvent in the second electron transport layer solution, an electron transport layer is formed.

[0024] During the research process, it was found that due to the uneven micro-surface of the perovskite layer caused by the different sizes of the formed perovskite grains, when preparing the electron transport layer, the electron transport layer solution will concentrate between the perovskite grains and it is difficult to form a complete coverage on the protruding parts of the perovskite grains, affecting the performance of the perovskite battery. Analyzing the reasons may be: when the electron transport layer cannot completely cover the surface of the perovskite grains, the electron transport path may be interrupted or restricted; when the electron transport layer cannot completely cover the surface of the perovskite grains, the tetrahedral effect of the perovskite grains may be more significant, resulting in the recombination of photo-generated electrons and holes in a short time, thus reducing the efficiency of the battery. Therefore, coating the first electron transport layer solution on the surface of the perovskite layer can reduce the relatively high average roughness of the perovskite layer surface.

[0025] In order to further reduce the average roughness of the electron transport layer, the presence of a small number of individual large perovskite grains on the surface of the perovskite layer affects the overall performance of the perovskite. After analysis, the reasons may be as follows: A small number of individual large perovskite grains may reduce the light absorption efficiency because light may pass through the grains without being absorbed; A small number of individual large perovskite grains usually introduce grain boundaries or impurities, which may lead to instability of the battery performance. Therefore, a polar organic solution is coated on the surface of the perovskite layer. The polar organic solvent dissolves some of the protruding parts of the perovskite grains, reducing the influence of a small number of individual large perovskite grains on the perovskite layer and the electron transport layer, thereby improving the stability and energy conversion efficiency of the battery. Coating a polar organic solution on the surface of the perovskite layer, the polar organic solvent dissolves some of the protruding parts of the perovskite grains, and controls its influence on the overall performance of the perovskite grains, and also improves the open circuit voltage of the perovskite battery.

[0026] After coating the polar organic solution on the surface of the perovskite layer, a second electron transport layer solution is continuously coated on the surface of the perovskite layer to form an electron transport layer. This electron transport layer can achieve complete coverage of the perovskite grains. The prepared electron transport layer has a more appropriate average thickness, and the average uniformity of the electron transport layer thickness is better, which is beneficial to the carrier transport efficiency and improves the energy conversion efficiency of the battery.

[0027] According to the method of the embodiment of the present application, by coating the first electron transport layer solution, coating the polar organic solution, and coating the second electron transport layer solution, it is avoided that the electron transport layer solution accumulates in the depressions between the perovskite grains, leaving the tops of the perovskite grains exposed. Using the polar organic solution, on the premise of ensuring the stability of the perovskite grains, the tip parts of individual higher perovskite grains are removed, so that the electron transport layer completely covers the perovskite grains, controlling the size and uniformity of the electron transport layer thickness, and improving the energy conversion efficiency and stability of the perovskite-type battery.

[0028] In any implementation manner of the present application, the average roughness of the surface of the perovskite layer is 24 nm to 35 nm.

[0029] The average roughness is a measure of the unevenness or irregularity of the surface, used to describe the minute irregular features or geometric structures on the surface of the perovskite layer. The average roughness is the average value of all height values on the surface, used to represent the overall irregularity of the surface.

[0030] According to the embodiments of the present application, in the preparation of perovskite cells, on the surface of the freshly prepared perovskite layer, the average roughness is within the above range, avoiding the phenomenon that only one layer of electron transport layer solution is coated directly according to the traditional method, resulting in the inability to cover perovskite grains or the aggregation of the electron transport layer solution between perovskite grains, which affects the energy conversion efficiency and stability of the perovskite-type battery.

[0031] In any embodiment of the present application, the polar organic solvent includes one or more of dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, ethanol, isopropanol, acetonitrile, methanol, propanol, and acetone.

[0032] In the embodiments of the present application, the solubility of the polar organic solvent can be quantified by the solubility parameter. The present application can use a polar organic solvent with a suitable solubility parameter, and the solubility parameter can be the Hansen solubility parameter, which can quantitatively describe the type of interaction between the solute and the solvent, and this parameter takes into account dispersion forces, polarization forces, hydrogen bond forces, etc.

[0033] In any embodiment of the present application, the perovskite grains include a compound with the general formula ABX 3 ; the polar organic solution includes one or several of the cation ligand A and the anion ligand X; wherein, A represents a monovalent inorganic cation, organic cation, or organic-inorganic hybrid cation, B represents a divalent inorganic cation, organic cation, or organic-inorganic hybrid cation, and X represents a monovalent inorganic anion, organic anion, or organic-inorganic hybrid anion.

[0034] According to the implementation of the present application, since the perovskite layer includes perovskite grains of a compound with the general formula ABX 3 , dissolving a part of the perovskite grains with a polar solvent and adding the cation ligand A and the anion ligand X arbitrarily in the polar organic solvent can, on the one hand, enhance the stability of the perovskite grains and reduce the damage to the overall structure and performance of the perovskite grains. On the other hand, the polar solvent includes the cation ligand A and the anion ligand X, and in subsequent processes such as drying or evaporation coating, a two-dimensional perovskite compound can be formed, which is a special type of perovskite material, and its crystal structure contains a two-dimensional layered structure. The two-dimensional perovskite compound reduces the impact on the overall structure and performance of the perovskite grains and can improve the performance and stability of the perovskite battery.

[0035] In some alternative embodiments, A includes CH 3 NH 3 + 、CH 3 CH 2 NH 3 + 、(CH 3 )2 CHNH 3 + 、CH(NH 2 ) 2 + 、Ar-CH 3 CH 2 NH 3 + 、Li + 、Na + 、K + 、Rb + 、Cs + one or more of the following.

[0036] In some alternative embodiments, B includes Pb 2+ 、Sn 2+ 、Be 2+ 、Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ 、Zn 2+ 、Ge 2+ 、Fe 2+ 、Co 2+ 、Ni 2+ one or more of the following.

[0037] In some alternative embodiments, X includes one or more of F-, Cl-, Br - 、I-.

[0038] According to the embodiments of the present application, when the types of A, B, and X are within the above ranges, a perovskite layer with better performance can be obtained. The cationic ligand A and the anionic ligand X are present in a polar organic solvent, which is beneficial for the polar organic solvent to dissolve a part of the perovskite grains and stabilize the perovskite grains in the perovskite layer; in addition, the cationic ligand A and the anionic ligand X in the polar organic solvent can form a two-dimensional perovskite compound, which reduces the influence on the overall structure and performance of the perovskite grains and can improve the performance and stability of the perovskite solar cell.

[0039] In any embodiment of the present application, the concentrations of the cationic ligand A and the anionic ligand B in the polar organic solution are respectively 0.5 mg / ml to 10 mg / ml.

[0040] According to the embodiments of the present application, by controlling the concentrations of the cationic ligand A and the anionic ligand B in the polar organic solution within the above ranges, the amount of the formed two-dimensional perovskite compound or the amount of the dissolved perovskite grains can be controlled, thereby reducing the influence on the structure and performance caused by the dissolution of the protruding perovskite grains in part. Controlling the concentrations of the cationic ligand A and the anionic ligand B in the polar organic solution can improve the performance and stability of the perovskite solar cell.

[0041] In the research process, it is found that coating a polar organic solution on the surface of the perovskite layer can remove some protruding parts in the perovskite grains, reducing the phenomenon that the electron transport layer solution cannot completely cover the perovskite grains or accumulates between the perovskite grains. The coating of the polar organic solution in the embodiments of the present application is not specifically limited. In some alternative embodiments, the methods of coating the polar organic solution on the surface of the perovskite layer include vapor deposition, spraying, inkjet printing, slot die coating, and blade coating.

[0042] By controlling the relationship between the coating amount of the polar organic solution and the roughness in the above method, the effect of controlling the amount of perovskite grains dissolved by the polar organic solution can be achieved.

[0043] In any embodiment of the present application, the drying conditions for drying and removing the polar organic solvent satisfy: 1) the drying temperature is 60 - 150 °C; 2) the drying time is 8 - 12 min.

[0044] According to the embodiments of the present application, removing the polar organic solvent with the above temperature and time can achieve the effect of dissolving some perovskite grains, and also takes into account the efficiency in industrial preparation of the electron transport layer.

[0045] In any embodiment of the present application, the electron transport materials in the first electron transport layer solution and the second electron transport layer solution independently include one or more of organic electron transport materials, inorganic electron transport materials, and organic-inorganic hybrid electron transport materials.

[0046] According to the embodiments of the present application, the types of electron transport materials in the first electron transport layer solution and the second electron transport layer solution can be the same or different.

[0047] In any embodiment of the present application, the electron transport material includes one or more of imide compounds, quinone compounds, fullerenes and their derivatives, metal oxides, silicon oxides, strontium titanate, calcium titanate, lithium fluoride, and calcium fluoride.

[0048] In any embodiment of the present application, fullerenes and their derivatives include one or more of [6,6]-phenyl C71 butyric acid methyl ester and [6,6]-phenyl C61 butyric acid methyl ester. The lowest unoccupied molecular orbital (LUMO) energy level of fullerenes and their derivatives can better match the LUMO energy level of the perovskite layer, which is beneficial to promoting electron extraction and transport.

[0049] In any embodiment of the present application, the metal elements in the metal oxide include one or more of Mg, Cd, Zn, In, Pb, W, Sb, Bi, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, and Cr.

[0050] In any embodiment of the present application, the concentration of the first electron transport layer solution is 3 mg / ml to 30 mg / ml.

[0051] According to the embodiments of the present application, controlling the concentration of the first electron transport layer solution within the above range is beneficial to reducing the surface roughness of the perovskite layer, and at the same time cooperating with the perovskite layer to form an energy level difference with a certain gradient, facilitating the movement of carriers.

[0052] In any embodiment of the present application, the coating thickness of the first electron transport layer solution is 5 μm to 20 μm; it can be optionally 8 μm to 12 μm.

[0053] According to the embodiments of the present application, controlling the coating thickness of the first electron transport layer solution within the above range is beneficial to reducing the surface roughness of the perovskite layer, and at the same time cooperating with the perovskite layer to form an energy level difference with a certain gradient, facilitating the movement of carriers.

[0054] In any embodiment of the present application, the coating thickness of the second electron transport layer solution is 3 μm to 15 μm; it can be optionally 5 μm to 12 μm.

[0055] According to the embodiments of the present application, controlling the coating thickness of the second electron transport layer solution within the above range is beneficial to reducing the surface roughness of the perovskite layer, and at the same time cooperating with the perovskite layer to form an energy level difference with a certain gradient, facilitating the movement of carriers.

[0056] In any embodiment of the present application, the concentration of the second electron transport layer solution is 3 mg / ml to 30 mg / ml.

[0057] According to the embodiments of the present application, controlling the concentration of the second electron transport layer solution within the above range is beneficial to reducing the surface roughness of the perovskite layer, and at the same time cooperating with the perovskite layer to form an energy level difference with a certain gradient, facilitating the movement of carriers.

[0058] In any embodiment of the present application, the ratio of the coating thickness of the first electron transport layer solution to the coating thickness of the second electron transport layer solution is (0.5 - 5):1.

[0059] According to the embodiments of the present application, by controlling the ratio of the coating thickness of the first electron transport layer solution to the coating thickness of the second electron transport layer solution within the above range, on the basis of reducing the surface roughness of the perovskite layer, the second electron transport layer solution can be uniformly coated, improving the uniformity of the second electron transport layer formed by the second electron transport layer solution, thereby increasing the carrier transport speed, reducing the carrier transport resistance, and improving the energy efficiency of the perovskite solar cell.

[0060] In the embodiments of the present application, the types of solvents for the first electron transport layer solution and the second electron transport layer solution are not specifically limited and can be selected according to actual requirements. In some alternative embodiments, the solvents in the first electron transport layer solution and the second electron transport layer solution independently include one or more of benzene and its derivatives, alkanes and their derivatives.

[0061] In any embodiment of the present application, benzene and its derivatives include one or more of toluene, chlorobenzene, ortho-dichlorobenzene, ortho-xylene, benzaldehyde, aniline, benzene, benzyl alcohol, benzyl benzoate, tetrahydrothiophene, styrene, anisole.

[0062] In any embodiment of the present application, alkanes and their derivatives include one or more of dichloromethane, chloroform, dipentene, methyl tetrahydrofuran, cyclohexanone.

[0063] In any embodiment of the present application, the first electron transport layer solution and the second electron transport layer solution independently include additives, and the additives include one or more of polystyrene, polymethyl methacrylate, lecithin, Triton, pyridine. The first electron transport layer solution and the second electron transport layer solution include additives of the above types.

[0064] According to the embodiments of the present application, additives of the above types promote the growth of perovskite grains along the (001) direction, reduce defects in the grains, etc., which is beneficial to improving the stability and photoelectric conversion efficiency of perovskite solar cells. The (001) direction refers to a direction of the crystal lattice. In crystallography, the direction of a crystal is described by specifying the Miller indices of the lattice planes. For the perovskite structure, the (001) direction is along the c-axis direction in the lattice.

[0065] In any embodiment of the present application, the coating methods of the first electron transport layer solution and the second electron transport layer solution independently include any one of slot coating method and blade coating method.

[0066] According to the embodiments of the present application, the slot coating method and the blade coating method can better control their coating thickness, precisely control the thickness of the electron transport layer, improve the carrier transport efficiency, and thus improve the performance of perovskite solar cells.

[0067] In any embodiment of the present application, the coating methods of polar organic solvents independently include any one of slot coating method, blade coating method and spraying method.

[0068] According to the embodiments of the present application, the coating method of polar organic solvents can adopt any of the above methods to better control its coating amount and precisely remove part of the convex surface of perovskite grains.

[0069] In a third aspect, an embodiment of the present application provides a perovskite battery module, including the perovskite battery of the second aspect. The perovskite battery module of the embodiment of the present application at least has the advantages of the perovskite battery, can generate electricity stably, and has good energy conversion efficiency.

[0070] In a fourth aspect, an embodiment of the present application provides a tandem battery, including the perovskite battery module of the third aspect, and the tandem battery is used to provide electric energy.

[0071] The tandem battery of the embodiment of the present application at least has the advantages of the perovskite battery module, can stably provide electric energy, and has good energy conversion efficiency.

[0072] In a fifth aspect, an embodiment of the present application provides an electrical device, including the tandem battery of the fourth aspect.

[0073] The electrical device of the embodiment of the present application at least has the advantages of the tandem battery, can stably provide electric energy, and has good energy conversion efficiency.

[0074] In a sixth aspect, an embodiment of the present application provides a power generation device, including the tandem battery of the fourth aspect, for providing electric energy. The power generation device of the embodiment of the present application at least has the advantages of the tandem battery, can generate electricity stably, and has good energy conversion efficiency.

[0075] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. And in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0077] Figure 1 A schematic diagram showing the thickness detection of the perovskite layer in the perovskite battery provided by an embodiment of the present application is shown;

[0078] Figure 2 A schematic cross-sectional structure diagram of the perovskite battery provided by an embodiment of the present application is shown;

[0079] Figure 3 A schematic structural diagram of the method for preparing the electron transport layer of the perovskite battery provided by an embodiment of the present application is shown.

[0080] The drawings of the embodiments of the present application are not necessarily drawn to scale. Detailed implementation manners

[0081] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present application more clearly, and thus are only examples and should not be used to limit the protection scope of the present application.

[0082] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0083] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means two or more, unless otherwise specifically defined.

[0084] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0085] In the description of the embodiments of this application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally indicates that the associated objects before and after are in an "or" relationship.

[0086] In the description of the embodiments of this application, the term "a plurality of" refers to two or more (including two). 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).

[0087] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of the present application.

[0088] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific situations.

[0089] A perovskite solar cell is a solar cell that uses a perovskite compound semiconductor as a light-absorbing material and belongs to the third generation of solar cells. The perovskite photovoltaic cell uses a perovskite compound to absorb photons, generate electron-hole pairs, and the electron-hole pairs are then separated into free carriers. Subsequently, the generated free carriers are respectively transmitted by the transport layer material to achieve photoelectric conversion.

[0090] The working principle of the perovskite solar cell is as follows: Under illumination conditions, photons with energy greater than the bandgap width of the light-absorbing layer are absorbed by the light-absorbing material in the light-absorbing layer, and at the same time, valence band electrons in this layer are excited to the conduction band, leaving holes in the valence band; when the conduction band energy level of the light-absorbing layer is higher than the conduction band energy level of the electron transport layer, the conduction band electrons in the light-absorbing layer will be injected into the conduction band of the electron transport layer and then further transported to the anode and the external circuit; when the valence band energy level of the light-absorbing layer is lower than the valence band energy level of the hole transport layer, the holes in the light-absorbing layer will be injected into the hole transport layer and then further transported to the cathode and the external circuit, thus forming a complete circuit.

[0091] The electron transport material is an important component of the perovskite solar cell and restricts the performance of the perovskite solar cell. Currently, the structure of the electron transport material applied to the perovskite solar cell affects the performance of the perovskite solar cell. For example, the electron transport material cannot completely cover the perovskite layer grains of different sizes, affecting the energy conversion efficiency of the perovskite solar cell.

[0092] In view of this, the present application provides a method for preparing an electron transport layer of a perovskite battery, which can solve the problems that the thickness of the electron transport material is too large or the electron transport material cannot completely cover the perovskite layer grains, and improve the energy conversion efficiency of the perovskite battery.

[0093] Perovskite battery

[0094] In a first aspect, an embodiment of the present application provides a perovskite battery, including the following structures arranged in a stack:

[0095] A perovskite layer, including perovskite grains;

[0096] An electron transport layer, wherein the average roughness of the electron transport layer is 8 nm to 20 nm.

[0097] According to an embodiment of the present application, the average roughness is a measure of the unevenness or irregularity of the surface, used to describe the minute irregular features or geometric structures on the surface of the perovskite layer. The average roughness is the average of all height values on the surface, used to represent the overall irregularity of the surface. Usually, the method of area sampling is selected for detection.

[0098] Optionally, the average roughness of the electron transport layer can be any value or a range composed of 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm.

[0099] According to an embodiment of the present application, in the prepared perovskite battery, when the average roughness of the electron transport layer is within the above range, the phenomenon that the first electron transport layer aggregates in the depressions between the perovskite grains and exposes the tops of the perovskite grains is reduced, and the tip parts of individual higher perovskite grains are removed, so that the electron transport layer completely covers the perovskite grains, reducing the average roughness of the electron transport layer, improving the thickness uniformity of the perovskite layer, and improving the energy conversion efficiency and stability of the perovskite-type battery. It also avoids the large roughness of the perovskite layer, about 32 nm, according to the traditional method directly, and this higher roughness affects the energy conversion efficiency and stability of the perovskite-type battery.

[0100] In some alternative embodiments, the average roughness of the perovskite layer is 10 nm to 20 nm, and the average roughness is represented by the standard deviation of the grain length of the perovskite grains along the thickness direction of the perovskite layer.

[0101] Optionally, the average roughness of the perovskite layer can be any value or a range composed of 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm.

[0102] According to the embodiments of the present application, in the prepared perovskite solar cell, the average roughness of the surface of the perovskite layer is within the above range, reducing the phenomenon that the first electron transport layer aggregates at the depressions between perovskite grains, leaving the tops of perovskite grains exposed, and also removing the tip portions of individual higher perovskite grains, so that the electron transport layer completely covers the perovskite grains, reducing the average roughness of the electron transport layer, improving the thickness uniformity of the perovskite layer, and improving the energy conversion efficiency and stability of the perovskite solar cell. It avoids directly following the traditional method, where the roughness of the perovskite layer is about 32 nm, and this relatively high roughness affects the energy conversion efficiency and stability of the perovskite solar cell.

[0103] The average roughness of the electron transport layer and the average roughness of the perovskite layer can be detected by methods commonly used in the art. For example, an atomic force microscope (AFM) of model Bruker Dimension Ico or a VK-X3000 series profiler of Keyence shape measurement laser microscopy system can be used for detection.

[0104] When detecting the average roughness of the electron transport layer, the electrodes on the surface of the perovskite solar cell can be peeled off. For example, a polyimide high-temperature tape of model 5413D from 3M can be pressed on the surface of the electrode, and the tape can be torn off to remove the electrodes on the surface of the perovskite solar cell.

[0105] When detecting the average roughness of the electron transport layer, the electrodes and the electron transport layer on the surface of the perovskite solar cell can be peeled off. For example, a polyimide high-temperature tape of model 5413D from 3M can be pressed on the surface of the electrode, and the tape can be torn off to remove the electrodes on the surface of the perovskite solar cell. Then, the corresponding solvent can be selected according to the material of the electron transport layer to dissolve the electron transport layer without affecting the perovskite layer, and after drying, the average roughness of the perovskite layer can be detected. For example, the solvent can be one or more of benzene and its derivatives, alkanes and their derivatives; for example, benzene and its derivatives include one or more of toluene, chlorobenzene, o-dichlorobenzene, o-xylene, benzaldehyde, aniline, benzene, benzyl alcohol, benzyl benzoate, tetrahydrothiophene, styrene, anisole; for example, alkanes and their derivatives include one or more of dichloromethane, chloroform, dipentene, methyl tetrahydrofuran, cyclohexanone.

[0106] As an example, an atomic force microscope (AFM) can be used to obtain height information by contacting the sample surface with the cantilever tip, vibrating up and down while scanning the entire surface, and the surface signal obtained is fed back with the standard deviation through computer data processing. The Keyence shape measurement laser microscopy system can also be used. As another example, a triple-scanning method can be used, which employs three different scanning principles: laser confocal, white light interference, and focus variation, for high magnification and low magnification, fine roughness of planar and uneven surfaces, as well as mirror bodies and transparent bodies. VK has the measurement ability to handle a variety of samples (it can measure in the range from 1 nm to 50 mm).

[0107] In some alternative embodiments, the average length of the perovskite grains in the thickness direction of the perovskite layer is 400 nm to 600 nm.

[0108] According to the embodiments of the present application, the average length of the perovskite grains in the thickness direction of the perovskite layer can be understood as the thickness of the perovskite layer. When the average length of the perovskite grains is within the above range, it is beneficial to the energy conversion efficiency and stability of the perovskite solar cell.

[0109] The average length of the perovskite grains in the thickness direction of the perovskite layer can be detected by sampling the interface of the perovskite solar cell along the thickness direction. Then, it is measured with an atomic force microscope (AFM), as Figure 1 shown.

[0110] In some alternative embodiments, the perovskite solar cell includes a first electrode, a hole transport layer, a perovskite layer, an electron transport layer, and a second electrode. In some embodiments, the perovskite solar cell can be a reverse perovskite solar cell or a normal perovskite solar cell.

[0111] The following refers to Figure 2 to describe the embodiments of the perovskite solar cell according to the first aspect of the present application. As Figure 2 shown, the perovskite solar cell 10 includes the following structures stacked in sequence: a first electrode 11; a hole transport layer 13; a perovskite layer 15; an electron transport layer 14; and a second electrode 12.

[0112] In some alternative embodiments of the present application, the first electrode 11 can be used as the cathode of the perovskite solar cell 10 in the charging state or as the anode of the perovskite solar cell 10 in the discharging state. For the convenience of explanation, the following embodiments will be described with the first electrode 11 being the anode in the charging state.

[0113] It can be understood that: if the first electrode 11 is an anode, then the second electrode 12 is a cathode, and the first electrode 11 is close to the substrate while the second electrode 12 is close to the cover plate. In the embodiments of the present application, the materials of the first electrode 11 as the anode and the second electrode 12 as the cathode are not particularly limited and can be any one or more materials known in the art that constitute an anode and a cathode. The materials of the first electrode 11 and the second electrode 12 are also related.

[0114] In some alternative embodiments of the present application, the first electrode 11 can be made of a conductor, and the conductor has a relatively high work function to facilitate the formation of holes. Exemplarily, the conductor can be a metal, a metal oxide, and / or a conductive polymer. For example, in some embodiments, the thickness of the first electrode is 10 nm - 500 nm.

[0115] Exemplarily, the first electrode 11 can be made of a metal. For example, the material of the first electrode 11 includes at least one of nickel (Ni), platinum (Pt), vanadium (V), chromium (Cr), copper (Cu), zinc (Zn), gold (Au), silver (Ag), or their alloys. The first electrode 11 can also be made of a metal oxide. For example, the material of the first electrode 11 includes at least one of zinc oxide (ZnO), indium oxide (In 2 O 3 )), fluorine-doped tin oxide (FTO), indium tin oxide (ITO), nickel oxide (NiO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), and gallium zinc oxide (GZO). The first electrode 11 can also be made of a conductive polymer. For example, the material of the first electrode 11 includes at least one of poly(3-methylthiophene), poly(3,4-(ethylene-1,2-dioxy)thiophene) (PEDOT), polypyrrole, and polyaniline.

[0116] In the embodiments of the present application, the second electrode 12 can also be made of a conductor, and the conductor has a relatively low work function to facilitate the injection of electrons. Exemplarily, the material of the second electrode 12 includes at least one of copper (Cu), magnesium (Mg), aluminum (Al), nickel (Ni), silver (Ag), tin (Sn), chromium (Cr), bismuth (Bi), platinum (Pt), molybdenum (Mo), tungsten (W), or their alloys, carbon (C), graphene, carbon nanotubes, fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), and gallium zinc oxide (GZO). For example, in some embodiments, the thickness of the second electrode is 10 nm - 500 nm.

[0117] In some alternative embodiments, the perovskite grains include a general formula of ABX 3Compound; wherein, A represents a monovalent inorganic cation, organic cation or organic-inorganic hybrid cation, B represents a divalent inorganic cation, organic cation or organic-inorganic hybrid cation, and X represents a monovalent inorganic anion, organic anion or organic-inorganic hybrid anion.

[0118] The perovskite layer 15 contains a perovskite-type compound of the general formula ABX 3 as shown, wherein A is an organic cation, B is a metal cation, and X is a halogen anion or SCN - . In some embodiments, the halogen X includes at least one of chlorine, bromine, and iodine. Perovskite materials with different halogen ions have different bandgaps. The perovskite material with halogen ion I - has the smallest bandgap (generally about 1.5 electron volts), and the perovskite material with halogen ion Cl- has the largest bandgap (generally about 3 electron volts). Moreover, the perovskite material can contain two mixed halogen ions, and the mixing ratio can be continuously adjusted. Therefore, the bandgap of the perovskite material can be continuously adjusted in the range of 1.5 - 3 electron volts, corresponding to an absorbable light wavelength range of about 414 - 820 nanometers, which basically covers the entire visible light spectrum. Charge carriers are generated in the photoelectric conversion sublayer. In some embodiments, the thickness of the perovskite layer is 300nm - 1000nm.

[0119] For example: ABX 3 wherein A can include CH 3 NH 3+ and HC(NH 2 ) 2+ at least one of; in other words, A can be CH 3 NH 3 + , HC(NH 2 ) 2+ or a mixture of the two in any proportion. It can be understood that A can also include metal ions, such as Cs + , Rb + and K + at least one of.

[0120] For example: ABX 3 wherein B can be Pb 2+ , Sn 2+ and Ge 2+ at least one of.

[0121] For example, ABX 3 can be CH 3 NH 3 PbI 3 ; CH 3 NH 3 SnI3 ; CH 3 NH 3 PbI 2 Cl; CH 3 NH 3 PbI 2 Br; CH 3 NH 3 Pb(I 1-x Br x ) 3 (where 0 < x < 1), etc.

[0122] In some embodiments, the organic cation A includes at least one of optionally substituted ammonium ions.

[0123] In some embodiments, examples of the optionally substituted ammonium ions include alkylammonium ions such as methylammonium ion, ethylammonium ion, propylammonium ion, butylammonium ion, pentylammonium ion, hexylammonium ion; amidinium ions such as formamidinium ion; or imidazolium ions.

[0124] In some embodiments, the metal in the metal cation B includes at least one of lead (Pb), cesium (Cs), tin (Sn), zinc (Zn), titanium (Ti), antimony (Sb), bismuth (Bi), nickel (Ni), iron (Fe), cobalt (Co), silver (Ag), copper (Cu), gallium (Ga), germanium (Ge), magnesium (Mg), calcium (Ca), indium (In), aluminum (Al), manganese (Mn), chromium (Cr), molybdenum (Mo), and europium (Eu). B in the general formula ABX 3 selected from the above metal cations can help improve the photoelectric conversion efficiency.

[0125] In some alternative embodiments, the electron transport layer includes one or more of an organic electron transport material, an inorganic electron transport material, an organic-inorganic hybrid electron transport material, and its derivatives, optionally including one or more of imide compounds, quinone compounds, fullerenes and their derivatives, metal oxides, silicon oxides, strontium titanate, calcium titanate, lithium fluoride, and calcium fluoride;

[0126] Optionally, the fullerenes and their derivatives include one or more of [6,6]-phenyl C71 butyric acid methyl ester, [6,6]-phenyl C61 butyric acid methyl ester;

[0127] Optionally, the metal elements in the metal oxides include one or more of Mg, Cd, Zn, In, Pb, W, Sb, Bi, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, and Cr.

[0128] In some alternative embodiments, the electron transport layer includes a first electron transport layer and a second electron transport layer. The first electron transport layer includes PC61BM, and the second electron transport layer includes zinc peroxide. When the electron transport layer is composed of the above two materials, its photoelectric conversion efficiency is relatively high, which is beneficial to the energy conversion of the perovskite battery.

[0129] According to the embodiments of the present application, the first electron transport layer and the second electron transport layer can be made of different materials, which is convenient for the energy level matching of the perovskite layer, the first electron transport layer formed by the first electron transport layer solution, and the second transport layer formed by the second electron transport layer solution.

[0130] According to the method of the embodiments of the present application, by coating the first electron transport layer and the second electron transport layer, it is avoided that they accumulate in the depressions between the perovskite grains, exposing the tops of the perovskite grains, and removing the tip parts of some relatively high perovskite grains, so that the electron transport layer completely covers the perovskite grains, reducing the average roughness of the perovskite grains and improving the energy conversion efficiency and stability of the perovskite-type battery.

[0131] The detection method for the thickness of the second electron transport layer can be as follows: in the second electron transport layer, measure the thickness at 30 points, find the MAX and MIN among these 30 points, and use the formula (MAX - MIN) / AVG to measure. Generally speaking, when the thickness of the second electron transport layer is less than 10%, it has better thickness uniformity.

[0132] The thickness of the electron transport layer of the present application is not specifically limited and can be selected according to actual needs. For example, in some embodiments, the thickness of the electron transport layer is 20 nm - 300 nm.

[0133] In some alternative embodiments of the present application, the electron transport layer 14 includes one or several of imide compounds, quinone compounds, fullerenes and their derivatives, first metal oxides, silicon oxide, strontium titanate, calcium titanate, lithium fluoride, and calcium fluoride. Among them, the metal elements in the first metal oxide include one or several of Mg, Cd, Zn, In, Pb, W, Sb, Bi, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, and Cr. For example, in some embodiments, the thickness of the electron transport layer is 5 nm - 100 nm.

[0134] In some alternative embodiments, the material of the electron transport layer includes [6,6]-phenyl-C61-butyric acid isomethyl ester, C60, cyano-containing poly(phenylacetylene), boron-containing polymers, bathocuproine, bathophenanthroline, aluminum tris(8-hydroxyquinoline), oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic acid compounds, perylene derivatives, phosphine oxide compounds, phosphine sulfide compounds, fluorine-containing phthalocyanines, titanium oxide (TiO 2) Zinc oxide (ZnO), tin oxide (SnO 2 ) Indium oxide (In 2 O 3 ) Gallium oxide (Ga 2 O 3 ) Tin sulfide (SnS), indium sulfide (In 2 O 3 ) Lithium fluoride (LiF), sodium fluoride (NaF), magnesium fluoride (MgF 2 ) and zinc sulfide (ZnS).

[0135] In some alternative embodiments of the present application, the hole transport layer 13 includes one or more of 2,2,7,7-tetra[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene, methoxytriphenylamine-fluoromethylimine, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid, poly(3-hexylthiophene), triphenylene-core triarylamine compounds, 3,4-ethylenedioxythiophene-methoxytriphenylamine, N-(4-anilino)carbazole-spirobifluorene, polythiophene, phosphoric acid-based single molecules, carbazole-based single molecules, sulfonic acid-based single molecules, triphenylamine-based single molecules, aromatic-based single molecules, a second metal oxide, and cuprous thiocyanate, wherein the metal elements in the second metal oxide include one or more of Ni, Mo, and Cu. For example, in some embodiments, the thickness of the hole transport layer 13 is 5 nm - 100 nm.

[0136] According to the embodiments of the present application, the phosphoric acid-based single molecule, carbazole-based single molecule, sulfonic acid-based single molecule, triphenylamine-based single molecule, and aromatic-based single molecule independently represent compounds having the above groups. In the hole transport layer, the groups in the compounds having the above groups play a major role in hole transport.

[0137] The perovskite solar cell of the present application is not limited to the above structure and may further include other functional layers. For example, the perovskite solar cell further includes an interface modification layer for modifying the interfaces of each film layer. In some embodiments, the perovskite solar cell further includes an electrode modification layer for modifying the first electrode to reduce the energy level barrier between the perovskite layer and the first electrode, and to play a role in transporting holes and blocking electrons. In some embodiments, the perovskite solar cell further includes an electrode modification layer for modifying the second electrode to reduce the energy level barrier between the perovskite layer and the second electrode, and to play a role in transporting electrons and blocking holes. In some embodiments, the perovskite solar cell further includes an interface modification layer located between the electron transport layer and the perovskite layer to reduce interface defects and reduce the recombination of electrons and holes at the interface.

[0138] In some embodiments, the perovskite solar cell further includes a substrate and a cover plate, which are disposed opposite to each other and are respectively disposed on the surface of the perovskite solar cell. The substrate can play a role in supporting and protecting the perovskite solar cell to reduce the impact of external forces on the perovskite solar cell and reduce the infiltration of water and oxygen in the external environment.

[0139] It can be understood that the substrate generally needs to have a certain structural strength to support and protect the perovskite solar cell. Therefore, in some alternative embodiments of the present application, the substrate can be a glass substrate, a ceramic substrate or a plastic substrate. In some other embodiments of the present application, the substrate can also be made of metal, such as metals like aluminum, gold, silver, copper, iron, titanium, nickel, etc.

[0140] In some examples, the substrate can be transparent or opaque. Exemplarily, when the substrate is a transparent substrate, that is, when the substrate is a glass substrate, a ceramic substrate or a plastic substrate, it can increase the carrier absorption amount of the perovskite solar cell device and improve the power generation amount of the perovskite solar cell device.

[0141] In some embodiments, the cover plate can protect the perovskite solar cell device and at the same time allow the incident sunlight to pass through and irradiate the perovskite solar cell.

[0142] It can be understood that the cover plate is made of a transparent material, that is, it is a transparent cover plate, which can increase the absorption of the perovskite solar cell for the light beam from the outside. In the present application, the transparent material generally refers to a material with a high light transmittance. Exemplarily, the transparent material can be a soda-lime glass cover plate, an alkali-free glass cover plate, a ceramic cover plate, a transparent plastic cover plate, etc.

[0143] The perovskite solar cell disclosed in the embodiments of the present application can be used as the power source of an electrical device to provide electrical energy for it. The electrical device can be, but is not limited to, fields such as construction, military, travel, national defense, power supply, etc. For example: mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecrafts, photovoltaic greenhouses, solar water heaters, and so on.

[0144] Preparation method of perovskite solar cell

[0145] In a second aspect, the embodiments of the present application provide a preparation method for an electron transport layer of a perovskite solar cell, and the preparation method includes:

[0146] S10. Coating a first electron transport layer solution on the surface of the perovskite layer, wherein the perovskite layer includes perovskite grains;

[0147] S20. After drying to remove the solvent in the first electron transport layer solution, coating a polar organic solution on the surface of the perovskite layer; wherein the polar organic solution includes a polar organic solvent capable of dissolving perovskite grains;

[0148] S30. After drying to remove the polar organic solvent, continue to coat the second electron transport layer solution on the surface of the perovskite layer;

[0149] S40. After drying to remove the solvent in the second electron transport layer solution, an electron transport layer is formed.

[0150] According to the embodiments of the present application, the electron transport layer includes a layer formed by drying processes such as the first electron transport layer solution and the second electron transport layer solution. In some embodiments, the electron transport layer also contains residues formed after drying processes such as polar organic solutions.

[0151] During the research process, it was found that due to the uneven micro-surface of the perovskite layer caused by the different sizes of the perovskite grains formed, when preparing the electron transport layer, the electron transport layer solution would concentrate between the perovskite grains and it was difficult to form a complete coverage on the protruding parts of the perovskite grains, affecting the performance of the perovskite battery. Analyzing the reasons may be as follows: when the electron transport layer cannot completely cover the surface of the perovskite grains, the electron transport path may be interrupted or restricted; when the electron transport layer cannot completely cover the surface of the perovskite grains, the tetrahedral effect of the perovskite grains may be more significant, resulting in the recombination of photo-generated electrons and holes in a short time, thus reducing the efficiency of the battery. Therefore, coating the first electron transport layer solution on the surface of the perovskite layer can reduce the relatively high average roughness of the perovskite layer surface.

[0152] In order to further reduce the average roughness of the perovskite layer surface, a polar organic solution is coated on the perovskite layer surface. The polar organic solvent dissolves some of the protruding parts of the perovskite grains and controls its influence on the overall performance of the perovskite grains, and also improves the open-circuit voltage of the perovskite battery.

[0153] The open-circuit voltage (abbreviated as Voc) of the perovskite battery represents the photovoltaic performance of the battery. The open-circuit voltage is the potential difference generated by the battery when it is not connected to any external circuit load, that is, the voltage of the battery in the open-circuit state. The open-circuit voltage is a key performance parameter of a solar cell because it represents the ability of the battery to effectively convert incident light energy into electrical energy. A higher open-circuit voltage usually corresponds to a higher photoelectric conversion efficiency.

[0154] Further research found that a small number of individual large perovskite grains on the surface of the perovskite layer affect the overall performance of the perovskite. After analysis, the reasons may be as follows: A small number of individual large perovskite grains may reduce the light absorption efficiency because light may pass through the grains without being absorbed; a small number of individual large perovskite grains usually introduce grain boundaries or impurities, which may lead to instability of the battery performance. Therefore, by coating a polar organic solution on the surface of the perovskite layer, the polar organic solvent dissolves some protruding parts of the perovskite grains, reducing the influence of a small number of individual large perovskite grains on the perovskite layer and the electron transport layer, thereby improving the stability and energy conversion efficiency of the battery.

[0155] After coating the polar organic solution on the surface of the perovskite layer, a second electron transport layer solution is continuously coated on the surface of the perovskite layer to form an electron transport layer. This electron transport layer can achieve complete coverage of the perovskite grains. The prepared electron transport layer has a relatively appropriate average thickness and good thickness uniformity, which is beneficial to the carrier transport efficiency and improves the energy conversion efficiency of the battery.

[0156] In addition, the first electron transport layer solution and the second electron transport layer solution can be composed of different materials, which is convenient for the energy level matching of the perovskite layer, the first electron transport layer formed by the first electron transport layer solution, and the second transport layer formed by the second electron transport layer solution.

[0157] According to the method of the embodiment of the present application, by coating the first electron transport layer solution, coating the polar organic solution, and coating the second electron transport layer solution, it is avoided that the electron transport layer solution accumulates in the depressions between the perovskite grains, exposing the tops of the perovskite grains. Using the polar organic solution, on the premise of ensuring the stability of the perovskite grains, the tip parts of individual higher perovskite grains are removed, so that the electron transport layer completely covers the perovskite grains, controlling the size and uniformity of the thickness of the electron transport layer, and improving the energy conversion efficiency and stability of the perovskite-type battery.

[0158] In some optional embodiments, the average roughness of the surface of the perovskite layer is 24 nm to 35 nm.

[0159] The average roughness of the surface of the perovskite layer can be any value or a range composed of 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm.

[0160] According to the embodiments of the present application, on the surface of the prepared perovskite layer, with its average roughness within the above range, in the fresh state when the perovskite layer is neither coated with the first electron transport layer nor treated with a polar organic solvent. The perovskite layer is directly prepared by the conventional method, and for the subsequent electron transport layer, only one layer of electron transport layer solution is coated, resulting in the phenomenon that the perovskite grains cannot be covered or the electron transport layer solution accumulates between the perovskite grains, affecting the energy conversion efficiency and stability of the perovskite solar cell.

[0161] In some embodiments, in the electron transport direction, it can be understood as the thickness direction of the perovskite solar cell.

[0162] In some alternative embodiments, the average length of the perovskite grains in the thickness direction of the perovskite layer is 400 nm to 600 nm.

[0163] In some alternative embodiments, the polar organic solvent includes one or more of dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, ethanol, isopropanol, acetonitrile, methanol, propanol, and acetone.

[0164] According to the embodiments of the present application, the polar organic solvent can be understood as a class of polar organic solvents that can dissolve polar organic substances. The polar organic substance can be understood as perovskite grains in the embodiments of the present application, that is, a compound with the general formula ABX3.

[0165] In the embodiments of the present application, the polar organic solvent can be a commercially available conventional product, generally referring to pure solvents. The purchased polar organic solvents generally have a purity of more than 99%, and the impurities of about 1% basically do not affect the actual use. The dissolving power of the polar organic solvent can be quantified by the solubility parameter. In the present application, a polar organic solvent with a suitable solubility parameter can be used. The solubility parameter can be the Hansen solubility parameter, which can quantitatively describe the type of interaction between the solute and the solvent, and this parameter takes into account the dispersion force, polarization force, hydrogen bond force, etc.

[0166] In some alternative embodiments, the perovskite grains include a compound with the general formula ABX 3 ; the polar organic solution includes one or several of the cation ligand A and the anion ligand X; wherein, A represents a monovalent inorganic cation, organic cation, or organic-inorganic mixed cation, B represents a divalent inorganic cation, organic cation, or organic-inorganic mixed cation, and X represents a monovalent inorganic anion, organic anion, or organic-inorganic mixed anion.

[0167] According to the implementation of the present application, the perovskite layer includes a compound with the general formula ABX 3For the perovskite grains of the compound, a part of the perovskite grains is dissolved using a polar solvent. When optional added cation ligands A and anion ligands X are included in the polar organic solvent, on the one hand, the stability of the perovskite grains can be enhanced, reducing the destruction of the overall structure and properties of the perovskite grains. On the other hand, the polar solvent includes cation ligand A and anion ligand X, and in subsequent processes such as drying or evaporation coating, a two-dimensional perovskite compound can be formed, which is a special type of perovskite material and its crystal structure contains a two-dimensional layered structure. The two-dimensional perovskite compound reduces the influence on the overall structure and properties of the perovskite grains and can improve the performance and stability of the perovskite battery.

[0168] In some alternative embodiments, A includes CH 3 NH 3 + 、CH 3 CH 2 NH 3 + 、(CH 3 ) 2 CHNH 3 + 、CH(NH 2 ) 2 + 、Ar-CH 3 CH 2 NH 3 + 、Li + 、Na + 、K + 、Rb + 、Cs + or one or more of them.

[0169] In some alternative embodiments, B includes Pb 2+ 、Sn 2+ 、Be 2+ 、Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ 、Zn 2+ 、Ge 2+ 、Fe 2+ 、Co 2+ 、Ni 2+ or one or more of them.

[0170] In some alternative embodiments, X includes F - 、Cl - 、Br - 、I - or one or more of them.

[0171] In some alternative embodiments, the polar organic solution includes one or more of MAI ligand, FAI ligand, and PEAI ligand.

[0172] According to an embodiment of the present application, MAI (methylammonium iodide) is an organic ammonium ion, which is commonly used to prepare the perovskite layer of perovskite solar cells. Its chemical formula is CH 3 NH 3 I. FAI (propylammonium iodide) is an organic ammonium ion, and its chemical formula is C 4 H 9 NH 3 I. Similar to MAI, FAI can also be used to prepare the perovskite layer of perovskite solar cells. PEAI is another organic ammonium ion, and its chemical formula is C 3 H 7 NH 2 (CH 2 ) 2 NH 2 I.

[0173] According to an embodiment of the present application, when the types of A, B, and X are within the above ranges, a perovskite layer with better performance can be prepared. The cation ligand A and the anion ligand X are present in the polar organic solvent, which is beneficial for the polar organic solvent to dissolve a part of the perovskite grains and stabilize the perovskite grains in the perovskite layer. In addition, the cation ligand A and the anion ligand X in the polar organic solvent can form a two-dimensional perovskite compound, which reduces the influence on the overall structure and performance of the perovskite grains and can improve the performance and stability of the perovskite battery.

[0174] In some alternative embodiments, the concentrations of the cation ligand A and the anion ligand B in the polar organic solution are 0.5 mg / ml to 10 mg / ml, respectively.

[0175] According to an embodiment of the present application, by controlling the concentrations of the cation ligand A and the anion ligand B in the polar organic solution within the above ranges, the amount of the formed two-dimensional perovskite compound or the amount of the dissolved perovskite grains can be controlled, thereby reducing the influence on its structure and performance caused by the dissolution of some protruding perovskite grains. Controlling the concentrations of the cation ligand A and the anion ligand B in the polar organic solution can improve the performance and stability of the perovskite battery.

[0176] In addition, the cation ligand A and the anion ligand B can combine with free lead iodide to improve the stability of the perovskite battery. When the substances of the above components come into contact, their Gibbs free energy is negative, and at the same time, the reaction environment of the solution is provided, and each component can combine spontaneously.

[0177] In the research process, it is found that coating a polar organic solution on the surface of the perovskite layer can remove some protruding parts in the perovskite grains, reducing the phenomenon that the electron transport layer solution cannot completely cover the perovskite grains or accumulates between the perovskite grains. The coating of the polar organic solution in the embodiments of the present application is not specifically limited. In some alternative embodiments, the methods of coating the polar organic solution on the surface of the perovskite layer include vapor method, spraying method, inkjet printing method, slot coating method and blade coating method.

[0178] In some embodiments, the extrusion speed of the polar organic solution is 100 - 500 μl / s; the moving speed of the die head for extruding the polar organic solution is 10 - 100 mm / s.

[0179] In some embodiments, the vapor method is used to coat the polar organic solution on the surface of the perovskite layer. The vapor is the polar organic solution, and the release speed of the vapor is 1 - 10 L / min.

[0180] According to the embodiments of the present application, by controlling the relationship between the coating amount of the polar organic solution and the roughness, the effect of controlling the amount of perovskite grains dissolved by the polar organic solution can be achieved.

[0181] In some alternative embodiments, the drying conditions for drying and removing the polar organic solvent satisfy: the drying temperature is 60 - 150 °C, and the drying time is 8 - 12 min.

[0182] According to the embodiments of the present application, removing the polar organic solvent by using the above temperature and time can achieve the effect of dissolving some perovskite grains, and also takes into account the efficiency in industrial preparation of the electron transport layer.

[0183] In some alternative embodiments, the electron transport materials in the first electron transport layer solution and the second electron transport layer solution independently include one or more of organic electron transport materials, inorganic electron transport materials, and organic-inorganic hybrid electron transport materials.

[0184] According to the embodiments of the present application, the types of electron transport materials in the first electron transport layer solution and the second electron transport layer solution can be the same or different.

[0185] In some alternative embodiments, the electron transport materials include one or more of imide compounds, quinone compounds, fullerenes and their derivatives, metal oxides, silicon oxides, strontium titanate, calcium titanate, lithium fluoride, and calcium fluoride.

[0186] In some alternative embodiments, the fullerenes and their derivatives include one or more of methyl [6,6]-phenyl C71 butyrate and methyl [6,6]-phenyl C61 butyrate. The bottom energy level of the conduction band of the fullerenes and their derivatives can better match the bottom energy level of the conduction band of the perovskite layer, thereby facilitating the extraction and transport of electrons.

[0187] In some alternative embodiments, the metal elements in the metal oxide include one or more of Mg, Cd, Zn, In, Pb, W, Sb, Bi, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, and Cr.

[0188] In some alternative embodiments, the concentration of the first electron transport layer solution is 3 mg / ml to 30 mg / ml. Optionally, the concentration of the first electron transport layer solution can be any value among 3 mg / ml, 4 mg / ml, 5 mg / ml, 6 mg / ml, 7 mg / ml, 8 mg / ml, 9 mg / ml, 10 mg / ml, 11 mg / ml, 12 mg / ml, 13 mg / ml, 14 mg / ml, 15 mg / ml, 16 mg / ml, 17 mg / ml, 18 mg / ml, 19 mg / ml, 20 mg / ml, 21 mg / ml, 22 mg / ml, 23 mg / ml, 24 mg / ml, 25 mg / ml, 26 mg / ml, 27 mg / ml, 28 mg / ml, 29 mg / ml, 30 mg / ml or the range composed of them.

[0189] According to the embodiments of the present application, controlling the concentration and coating thickness of the first electron transport layer solution within the above ranges is beneficial to reducing the surface roughness of the perovskite layer, and at the same time, cooperating with the perovskite layer to form an energy level difference with a certain gradient, facilitating the movement of carriers.

[0190] In some alternative embodiments, the coating thickness of the first electron transport layer solution is 5 μm to 20 μm; it can be selected as 8 μm to 12 μm.

[0191] The coating thickness of the first electron transport layer solution can be any value among 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or the range composed of them. When the coating thickness of the first electron transport layer solution is within the above range, the thickness of the first electron transport layer in the perovskite battery product can be 8 nm to 12 nm.

[0192] According to the embodiments of the present application, controlling the concentration and coating thickness of the first electron transport layer solution within the above ranges is beneficial to reducing the surface roughness of the perovskite layer. At the same time, in cooperation with the perovskite layer, it forms an energy level difference with a certain gradient, facilitating the movement of carriers.

[0193] In some alternative embodiments, the concentration of the second electron transport layer solution is 3 mg / ml to 30 mg / ml.

[0194] According to the embodiments of the present application, controlling the concentration and thickness of the first electron transport layer solution within the above ranges is beneficial to reducing the surface roughness of the perovskite layer. At the same time, in cooperation with the perovskite layer, it forms an energy level difference with a certain gradient, facilitating the movement of carriers.

[0195] In some alternative embodiments, the coating thickness of the second electron transport layer solution is 3 μm to 15 μm; it can be selected as 5 μm to 12 μm. The coating thickness of the first electron transport layer solution can be any value among 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm or a range composed of them. When the coating thickness of the second electron transport layer solution is within the above ranges, the thickness of the second electron transport layer in the perovskite solar cell product can be 8 nm to 12 nm, and can be 5 nm to 10 nm.

[0196] According to the embodiments of the present application, controlling the coating thickness of the second electron transport layer solution within the above ranges is beneficial to reducing the surface roughness of the perovskite layer. At the same time, in cooperation with the perovskite layer, it forms an energy level difference with a certain gradient, facilitating the movement of carriers.

[0197] As an example, the coating thickness of the second electron transport layer solution and the second electron transport layer solution respectively include PC61BM and o-xylene, and the concentration of PC61BM can be 10 - 13 mg / ml. PC61BM (also known as [6,6]-Phenyl-C61-butyric acid methyl ester) is an organic compound commonly used in the field of organic photovoltaics. It is a fullerene derivative and is related to fullerene C60. The molecular structure of this compound includes a C61 fullerene core with benzene rings and methyl butyrate groups attached around it.

[0198] According to the embodiments of the present application, controlling the concentration and coating thickness of the second electron transport layer solution within the above ranges is beneficial to reducing the surface roughness of the perovskite layer. At the same time, in cooperation with the perovskite layer and the first electron transport layer formed by the first electron transport layer solution, it forms an energy level difference with a certain gradient, facilitating the movement of carriers.

[0199] In some alternative embodiments, the ratio of the coating thickness of the first electron transport layer solution to the coating thickness of the second electron transport layer solution is (0.5 - 5):1.

[0200] According to the embodiments of the present application, by controlling the ratio of the coating thickness of the first electron transport layer solution to the coating thickness of the second electron transport layer solution within the above range, on the basis of reducing the surface roughness of the perovskite layer, the second electron transport layer solution can be uniformly coated, improving the uniformity of the second electron transport layer formed by the second electron transport layer solution, thereby increasing the carrier transport speed and reducing the carrier transport resistance, and improving the energy efficiency of the perovskite solar cell.

[0201] The types of solvents for the first electron transport layer solution and the second electron transport layer solution in the embodiments of the present application are not specifically limited and can be selected according to actual needs. In some alternative embodiments, the solvents in the first electron transport layer solution and the second electron transport layer solution independently include one or more of benzene and its derivatives, alkanes and their derivatives.

[0202] In some alternative embodiments, benzene and its derivatives include one or more of toluene, chlorobenzene, o-dichlorobenzene, o-xylene, benzaldehyde, aniline, benzene, benzyl alcohol, benzyl benzoate, tetrahydrothiophene, styrene, anisole.

[0203] In some alternative embodiments, alkanes and their derivatives include one or more of dichloromethane, chloroform, dipentene, methyltetrahydrofuran, cyclohexanone.

[0204] In some alternative embodiments, the first electron transport layer solution and the second electron transport layer solution independently include additives, and the additives include one or more of polystyrene, polymethyl methacrylate, lecithin, Triton, pyridine. The first electron transport layer solution and the second electron transport layer solution include additives of the above types.

[0205] According to the embodiments of the present application, additives of the above types promote the growth of perovskite grains along the (001) direction, reducing defects in the grains and other advantages, which is beneficial to improving the stability and photoelectric conversion efficiency of the perovskite solar cell. The (001) direction refers to a direction of the crystal lattice. In crystallography, the direction of a crystal is described by specifying the Miller indices of the lattice planes. For the perovskite structure, the (001) direction is along the c-axis direction in the lattice.

[0206] The coating methods of the first electron transport layer solution and the second electron transport layer solution can adopt the commonly used coating methods in the art, and the present application does not make obvious limitations thereto.

[0207] In some alternative embodiments, the coating methods of the first electron transport layer solution and the second electron transport layer solution independently include any one of slot coating method and blade coating method. The slot coating method and the blade coating method can better control their coating thicknesses and precisely control the thickness of the electron transport layer.

[0208] The coating method of the polar organic solvent can adopt the commonly used coating methods in the art, and the present application does not impose obvious limitations on it.

[0209] In some alternative embodiments, the coating methods of the polar organic solvent independently include any one of slot coating method, blade coating method and spraying method. The coating method of the polar organic solvent can adopt any of the above methods to better control its coating amount and precisely remove partial convex surfaces of perovskite grains.

[0210] As an example, when coating the polar organic solvent, the die moving speeds of slot coating, blade coating and spraying are 10-100 mm / s respectively; optionally, the extrusion speed of slot coating is 10-500 μl / s; the scraping distance between the coating head and the substrate during spraying is set to 30-50 cm.

[0211] When spraying the polar organic solvent, a circulating air outlet device can be arranged in the processing chamber, and the circulating air outlet device sprays out the vapor containing the polar organic solvent. The amount of the vapor of the polar solvent to be discharged is judged by the processing time, and nitrogen can also be sprayed by the circulating air outlet device as needed. Further, the air outlet device can be installed at the top of the processing chamber, and whether to discharge the vapor is controlled by an air valve to realize spraying the polar organic solvent.

[0212] Generally speaking, the perovskite solar cell is prepared layer by layer from bottom to top. According to the extraction ability of the perovskite bottom layer material for electrons or holes in the perovskite, the perovskite solar cell is divided into two major categories: the normal (n-i-p) structure and the inverted (p-i-n) structure. The normal structure usually sequentially prepares an electron transport layer, a perovskite layer, a hole transport layer and an anode metal layer on a transparent cathode, while the inverted structure usually sequentially prepares a hole transport layer, a perovskite layer, an electron transport layer and a cathode metal layer on a transparent anode. In some embodiments, the perovskite solar cell is of the inverted structure.

[0213] In the embodiments of the present application, perovskite solar cells can be fabricated using methods known in the art. Exemplarily, the fabrication method of the perovskite solar cell 10 may include: sequentially forming a hole transport layer 13, a perovskite layer 15, an electron transport layer 14, and a second electrode 12 on a transparent or opaque first electrode 11 from bottom to top. Among them, the perovskite layer 15 can be formed using known film-forming methods such as evaporation, sputtering, spin coating, dipping, ion plating, etc. The first electrode can be a transparent cathode, and the second electrode can be an anode metal layer. The first electrode can be a transparent anode, and the second electrode can be a cathode metal layer.

[0214] Perovskite solar cell module

[0215] In a third aspect, an embodiment of the present application provides a perovskite solar cell module, including the perovskite solar cell of the second aspect.

[0216] In the perovskite solar cell module provided by the embodiments of the present application, it may include one perovskite solar cell 10 or multiple perovskite solar cells. If there are multiple perovskite solar cells, the multiple perovskite solar cells can be connected in series, in parallel, or in a hybrid connection. A hybrid connection means that there are both series and parallel connections among the multiple perovskite solar cells.

[0217] The perovskite solar cell module of the embodiment of the present application can be a photovoltaic module. The photovoltaic module includes the perovskite solar cell of the second aspect of the embodiment of the present application. The perovskite solar cell can be used as the power source of the photovoltaic module after processes such as series-parallel connection and encapsulation. In some embodiments, the photovoltaic module includes a single-junction perovskite solar cell, a perovskite-perovskite tandem cell, or a perovskite-silicon tandem cell made of the above-mentioned perovskite solar cell.

[0218] In some embodiments, the perovskite solar cell module includes a protective layer and / or an encapsulation layer.

[0219] [Protective layer]

[0220] The protective layer is disposed between the encapsulation layer and the perovskite solar cell device, and the protective layer contains metal halides and / or organic halides. The metal halides and organic halides in the protective layer can absorb the infiltrated water and oxygen, reduce the erosion of the organic-inorganic perovskite compound in the optoelectronic conversion layer by water and oxygen, thereby improving the stability of the perovskite solar cell, and thus helping to extend the service life of the perovskite solar cell device.

[0221] In some alternative embodiments of the present application, the metal halide has the general formula BX k , where the value of k ranges from 1 to 3. The organic halide has the general formula AX.

[0222] In the above embodiments, the metal halide and the organic halide respectively have the above general formulas, so that while the protective layer absorbs water and oxygen, substances similar to or the same as the precursor substances of the organic-inorganic perovskite compound can also be generated. These substances can react to form a perovskite compound with a function similar to that of the organic-inorganic perovskite compound, so that the perovskite battery still has a long service life in the case of water and oxygen infiltration.

[0223] In the above embodiments, the organic cations in the general formula ABX 3 are the same as or homologues of the organic cations in the general formula AX, which can help the organic halide in the protective layer 15 react with the precursor substances to form an organic-inorganic perovskite compound.

[0224] In some alternative embodiments of the present application, the organic cation includes at least one of an amino group and an amino group derivative, such as an alkylamino group.

[0225] In some alternative embodiments of the present application, the amino group includes at least one of a methylamino group, an ethylamino group, a propylamino group, a butylamino group, a pentylamino group, a hexylamino group, and a formamidinyl group. The amino group derivative includes an imidazolyl group.

[0226] Exemplarily, when the organic cation in the organic-inorganic perovskite compound is the same as the organic cation in the organic halide, the organic cation in the organic-inorganic perovskite compound is methylamine (CH 3 NH - ), then the organic cation in the organic halide is also methylamine (CH 3 NH - ).

[0227] Exemplarily, when the organic cation in the general formula ABX 3 and the organic cation in the general formula AX are homologues, the organic cation in the organic-inorganic perovskite compound is methylamine (CH 3 NH - ), then the organic cation in the organic halide can be ethylamino group (CH 3 CH 2 NH - ), propylamine (CH 3 CH 2 CH 2 NH - ).

[0228] In the embodiments of the present application, the protective layer can be a single-layer structure or a multi-layer structure, and the specific number of layers can be designed according to requirements.

[0229] In some alternative embodiments of the present application, the protective layer comprises at least one of MOF material, activated carbon, montmorillonite, diatomaceous earth, zeolite, molecular sieve, kaolin, ion exchange resin, and zinc 2-methylimidazolate MAF-4 to provide a porous structure.

[0230] [Encapsulation layer]

[0231] The encapsulation layer can encapsulate the perovskite solar cell between the cover plate and the substrate to protect the perovskite solar cell.

[0232] In some alternative embodiments of the present application, the material of the encapsulation layer comprises at least one of thermoplastic encapsulation adhesives, thermosetting encapsulation adhesives, and photocuring encapsulation adhesives.

[0233] Exemplarily, the thermoplastic encapsulation adhesives include at least one of ethylene-vinyl acetate copolymer, polyvinyl butyral, ethylene-octene copolymer, polyisobutylene, polyolefin encapsulation adhesives, and butyl rubber. The thermosetting encapsulation adhesives include at least one of epoxy encapsulation adhesives, silicone encapsulation adhesives, and polyurethane encapsulation adhesives. The photocuring encapsulation adhesives include at least one of ultraviolet light-curing encapsulation adhesives and infrared light-curing encapsulation adhesives.

[0234] Stacked cell

[0235] In a fourth aspect, an embodiment of the present application provides a tandem cell, comprising the perovskite solar cell assembly of the third aspect, and the tandem cell is used to provide electrical energy.

[0236] The above-mentioned tandem cell may include any one of a crystalline silicon-perovskite tandem solar cell or a perovskite-only solar cell. Exemplarily, the above-mentioned crystalline silicon-perovskite tandem solar cell may include a crystalline silicon bottom cell, a composite layer, and a perovskite top cell that are sequentially stacked, wherein the above-mentioned perovskite solar cell may be used as the perovskite top cell in the crystalline silicon-perovskite tandem solar cell. Exemplarily, the above-mentioned perovskite-only solar cell may include a first perovskite cell, a composite layer, and a second perovskite cell that are sequentially stacked, wherein both the first perovskite cell and the second perovskite cell may be the above-mentioned perovskite solar cell of the present application.

[0237] In some alternative embodiments, the solar cell may be a single-junction cell, such as a perovskite solar cell.

[0238] In some alternative embodiments, the stacked cell can be a stacked solar cell. By connecting a wide-bandgap cell and a narrow-bandgap cell in series, the stacked solar cell can more reasonably utilize photons in the full spectrum range and reduce energy loss. Specifically, the stacked solar cell includes a bottom cell and a top cell. The bottom cell has a relatively narrow bandgap and can be a silicon cell or, of course, a perovskite solar cell. The top cell has a relatively wide bandgap and can be a perovskite solar cell. When the stacked solar cell includes a perovskite solar cell, the specific structure and material selection of the perovskite solar cell can be as described in any of the embodiments of the first to third aspects of this application.

[0239] Electric device

[0240] In a fifth aspect, an embodiment of this application provides an electrical device, including the stacked cell of the fourth aspect, for providing electrical energy.

[0241] The electrical device can be, but is not limited to, fields such as construction, military, travel, national defense, and power supply. For example: mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, etc.

[0242] Power generation device

[0243] In a sixth aspect, an embodiment of this application provides a power generation device, including the stacked cell of the fourth aspect, for providing electrical energy. The power generation device of the embodiment of this application at least has the advantages of a perovskite battery, can generate electricity stably, and has good energy conversion efficiency.

[0244] The power generation device can be, but is not limited to, fields such as construction, military, travel, national defense, and power supply. For example: mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, etc.

[0245] The power generation device can be a photovoltaic greenhouse, a solar water heater, a photovoltaic system, etc. Taking the photovoltaic system as an example, the photovoltaic system may include a photovoltaic array, a junction box, and an inverter. The photovoltaic array can be an array combination of multiple above-mentioned perovskite battery modules. For example, multiple above-mentioned perovskite battery modules can form multiple photovoltaic arrays. The photovoltaic arrays are connected to the junction box, and the junction box can collect the current generated by the photovoltaic arrays. The collected current flows through the inverter and is converted into alternating current required by the mains power grid and then connected to the mains network to achieve solar power supply.

[0246] The power generation device can be a photovoltaic system applied in a photovoltaic power station, such as a ground power station, a rooftop power station, a water surface power station, etc. It can also be applied to devices or apparatuses that utilize solar energy for power generation, such as user solar power supplies, solar street lamps, solar cars, solar buildings, and so on. Of course, it can be understood that the application scenarios of the power generation device are not limited to this, that is to say, the power generation device can be applied in all fields that require solar power generation.

[0247] The following embodiments more specifically describe the content disclosed in the present application. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the content disclosed in the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and all instruments used in the embodiments are commercially available.

[0248] Example 1

[0249] An embodiment of the present application provides a method for manufacturing a perovskite battery. The method includes:

[0250] 1) Clean the surface of the FTO conductive glass with a size of 2.0 cm × 2.0 cm twice with acetone and isopropanol in sequence, immerse it in deionized water for ultrasonic treatment for 10 min, then dry it in a blast drying oven, and place it in a glove box (N 2 atmosphere), and use it as the first electrode.

[0251] 2) Prepare the hole transport layer: Spin-coat a 3 wt.% SnO2 nanocolloid solution on the FTO layer at 4000 rpm to 6500 rpm, and then heat it on a constant temperature hot stage at 150 °C for 15 min, with a thickness of 30 to 60 nm.

[0252] 3) Prepare the perovskite layer, including perovskite grains: Spin-coat a mixed DMF solution of 1.5 mol / L FAPbI 3 on the hole transport layer at a speed of 3000 rpm to 4500 rpm, then move it to a constant temperature hot stage and heat it at 100 °C for 30 min. After cooling to room temperature, a perovskite layer is formed with a thickness of 500 nm. The average roughness of the perovskite layer is 30 nm.

[0253] 4) Prepare the electron transport layer:

[0254] First, Figure 3As shown in Figure A, the perovskite layer contains perovskite grains 100. The surface of the perovskite layer is coated with the first electron transport layer solution by a liquid phase method. The moving speed of the slit coating die head is 10 mm / s, and the extrusion speed of the slit coating is 100 μl / s. As Figure 3 As shown in Figure B, the first electron transport layer solution 110 is distributed between the perovskite grains 100, and a relatively thin first electron transport layer is prepared. The tops of the perovskite grains in the perovskite layer are temporarily not covered. After the first electron transport layer is prepared, it is heated at 50 °C to 120 °C. The material of the first electron transport layer is shown in Table 1.

[0255] A polar organic solvent is coated on the surface of the first electron transport layer. The polar organic solvent is ethanol, and it is applied by spraying. The distance between the coating head and the substrate containing the perovskite layer is set to 30 - 50 cm, and the moving speed is set to 10 - 100 mm / s. Two tubes can be introduced at the top of the chamber of the loading base. One tube introduces an inert gas, such as nitrogen or argon, into the chamber; the other tube introduces a polar solvent gas into the chamber. Among them, the introduction timing is set as follows: after the processing of the first electron transport layer is completed, the polar solvent gas is introduced by switch control; among them, the air outlet volume is set to 100 L / min, and the air outlet time is set to 2 minutes. After the introduction time of the polar solvent gas arrives, the tube for the polar solvent gas is closed, and the tube for the inert gas is opened. Among them, the air outlet volume is set to 300 L / min, and the air outlet time is set to 1 - 10 minutes.

[0256] After the preparation of the coating of the polar organic solvent is completed, the part of the perovskite top that is not covered by the electron transport layer has been reacted by the polar solvent. As Figure 3 As shown in Figure C, Figure C includes perovskite grains 100 with dissolved tops, and the first transport layer between the perovskite grains. At this time, the second electron transport layer solution is coated by a liquid phase method. The moving speed of the slit coating die head is 10 mm / s, and the extrusion speed of the slit coating is 100 μl / s. As Figure 3 As shown in Figure D, the second electron transport layer solution 120 is shown, and a second electron transport layer is formed. After the second electron transport layer is prepared, it is heated at 50 °C to 120 °C. The thickness of the second electron transport layer is 5 - 10 nm. The material of the second electron transport layer is shown in Table 1.

[0257] The specific components and concentrations of the electron transport layer are shown in Table 1.

[0258] 6) Prepare the Ag electrode (the second electrode): Put the aforementioned sample into a vacuum coater, and evaporate the Ag electrode on the surface of the hole transport layer obtained under a vacuum condition of 5×10 -4 Pa at an evaporation rate of 0.1 Å / s. The thickness of the Ag electrode is 80 nm.

[0259] Electric field polarization: At a temperature of 80°C to 150°C, an external electric field is applied to the prepared sample, with the electric field strength E ≤ 20 kV / mm, and the electric field direction is perpendicular to the sample substrate plane and points from the electron transport layer to the hole transport layer.

[0260] Next, form the encapsulation layer and the protective layer: Mix the material providing the porous structure with the binder to form a slurry.

[0261] Uniformly coat the slurry on the surface of the encapsulation layer to form the protective layer.

[0262] Edge cleaning: Use a laser marking machine to clean the coating in the area where the edge of the perovskite battery device extends inwards by 0.5 cm.

[0263] Gluing: Stick the encapsulation adhesive on the edge-cleaned area.

[0264] Laminating: The substrate, the perovskite battery device with glue applied.

[0265] Examples 2 - 4

[0266] The difference between this example and Example 1 is that the coating thickness of the polar organic solvent is different, as shown in Table 1.

[0267] Examples 5 - 8

[0268] The difference between this example and Example 1 is that the coating thickness of the first electron transport layer solution is different, as shown in Table 1.

[0269] Examples 9 - 11

[0270] The difference between this example and Example 1 is that the types of the first electron transport layer solution and the second electron transport layer solution are different. The average particle size Dv50 of the solute zinc peroxide in the second electron transport layer solution is 20 nm, and the others are as shown in Table 1.

[0271] Examples 12 - 15

[0272] The difference between this example and Example 1 is that the types of the polar organic solvents are different, as shown in Table 1.

[0273] Example 16

[0274] The difference between this example and Example 1 is that the substances and concentrations contained in the polar organic solvent are different. The polar organic solvent contains the MAI ligand at a concentration of 2 mg / ml.

[0275] In the preparation of perovskite solar cells, an atomic force microscope (AFM) of the Bruker model was used to observe the surface of the device during the preparation of the electron transport layer in Example 16. The sampling area was 25 square micrometers. In Example 16, during the preparation of the perovskite solar cell, when the perovskite layer was prepared, the measured roughness of the perovskite layer surface was 30 nm. Then the first electron transport layer was prepared, and the measured average roughness of the structural surface of the perovskite layer and the first electron transport layer was 19.6 nm. Then, after treating the structure of the perovskite layer and the first electron transport layer with a polar solvent, the measured average roughness of the structural surface of the perovskite layer and the first electron transport layer was 18.9 nm. Then the second electron transport layer was prepared, and the measured average roughness of the surface of the second electron transport layer was 14.4 nm. It can be seen that the surface roughness of the perovskite solar cell in Example 16 showed a decreasing trend during the preparation process.

[0276] Example 17

[0277] The difference between this example and Example 16 is that the substances and concentrations contained in the polar organic solvent are different. The polar organic solvent contains MAI ligand, 2 mg / ml; Triton X-100, 0.5 mg / ml.

[0278] Examples 18 - 19

[0279] The difference between this example and Example 1 is that the ligands and some additives contained in the polar organic solvent are different in type. In Example 18, it is the FAI ligand, and in Example 19, it is the PEAI ligand. As shown in Table 1.

[0280] Examples 20 - 22

[0281] The difference between this example and Example 1 is that the types of perovskite grains in the perovskite layer and the roughness of the perovskite layer are different, as shown in Table 1. The average roughness of the perovskite layer in Example 20 is 27 nm, the average roughness of the perovskite layer in Example 21 is 24 nm, and the average roughness of the perovskite layer in Example 22 is 26 nm.

[0282] Comparative Example 1

[0283] The difference between this comparative example and Example 11 is that only the liquid phase method was used to coat the first electron transport layer solution. The moving speed of the slot die coater was 10 mm / s, and the extrusion speed of the slot coating was 100 μl / s. The second electron transport layer solution and the polar organic solvent were not coated.

[0284] Comparative Example 2

[0285] The difference between this comparative example and Example 20 is as follows: Only the liquid-phase method is used to coat the solution of the first electron transport layer. The moving speed of the slot die coater is 10 mm / s, and the extrusion speed of the slot die coating is 100 μl / s. The solution of the second electron transport layer and the polar organic solvent are not coated, as shown in Table 1.

[0286] Comparative Example 3

[0287] The difference between this comparative example and Example 21 is as follows: Only the liquid-phase method is used to coat the solution of the first electron transport layer. The moving speed of the slot die coater is 10 mm / s, and the extrusion speed of the slot die coating is 100 μl / s. The solution of the second electron transport layer and the polar organic solvent are not coated, as shown in Table 1.

[0288] Comparative Example 4

[0289] The difference between this comparative example and Example 22 is as follows: Only the liquid-phase method is used to coat the solution of the first electron transport layer. The moving speed of the slot die coater is 10 mm / s, and the extrusion speed of the slot die coating is 100 μl / s. The solution of the second electron transport layer and the polar organic solvent are not coated, as shown in Table 1.

[0290] Performance test

[0291] 1) Energy conversion efficiency detection: Under the atmospheric environment, the perovskite solar cell modules of the examples and comparative examples are tested using a solar simulator (OptoSolar) according to the national standard IEC61215. The intensity of the light is calibrated with a crystalline silicon solar cell to reach a solar intensity of one sun, AM 1.5. The battery is connected to a digital source meter, and the photovoltaic conversion efficiency Eff is measured under illumination. Under the atmospheric environment, the solar simulation light source uses an AM1.5G standard light source, and a four-channel digital source meter (Keithley2440) is used to measure the volt-ampere characteristic curve of the battery under the illumination of the light source, and the open-circuit voltage Voc, short-circuit current density Jsc, and fill factor FF (Fill Factor) of the battery are obtained. Thus, the photovoltaic conversion efficiency Eff (Efficiency) of the perovskite solar cell is calculated.

[0292] The energy conversion efficiency is calculated as follows: Eff = Pout / Popt

[0293] = Voc × Jsc × (Vmpp × Jmpp) / (Voc × Jsc)

[0294] = Voc × Jsc × FF

[0295] Where Pout represents the output power of the battery during operation, Popt represents the incident light power, Vmpp represents the maximum power point voltage of the battery, and Jmpp represents the maximum power point current.

[0296] 2) Open-circuit voltage detection: Using an AM1.5G standard light source, the perovskite solar cell modules of the examples and comparative examples were irradiated in an atmospheric environment with normal light for 8 hours, standard light with 80% light intensity for 4 hours, and no light for 12 hours, and the irradiation was cycled in this order for 800 hours. The 24-hour average value of the generated power was calculated.

[0297] 3) Fill factor detection: The FF value will be automatically displayed on the table of the solar simulator. The fill factor (FF) of the perovskite solar cell represents the performance stability and efficiency of the battery.

[0298] The results were recorded in Table 1.

[0299] According to Table 1, the perovskite solar cells prepared in the examples have better energy conversion efficiency, can generate electricity stably, have higher open-circuit voltage and current density, and can provide stable electric power output. The possible reason for the analysis is that the electron transport layer better covers the surface of the perovskite layer, has better average roughness, and the perovskite solar cells prepared in the examples have higher open-circuit voltage.

[0300] Comparing the test results of Examples 11-19 and Comparative Example 1, it can be seen that the perovskite solar cells prepared by the preparation method of the embodiments of the present application have increased open-circuit voltage and improved energy conversion efficiency of the perovskite solar cells.

[0301] Comparing the test results of Example 20 with Comparative Example 2, the test results of Example 21 with Comparative Example 3, and the test results of Example 22 with Comparative Example 4, the perovskite solar cells prepared by the preparation method of the embodiments of the present application have increased open-circuit voltage and improved energy conversion efficiency of the perovskite solar cells.

[0302] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered within the scope of the claims and the specification of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

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Claims

1. A perovskite solar cell, characterized in that, it includes the following structures arranged in a stack: a perovskite layer, including perovskite grains; an electron transport layer, wherein the average roughness of the electron transport layer is 8 nm to 20 nm.

2. The perovskite solar cell according to claim 1, characterized in that, the average roughness of the perovskite layer is 10 nm to 30 nm, and the average roughness is represented by the standard deviation of the grain lengths of the perovskite grains along the thickness direction of the perovskite layer.

3. The perovskite solar cell according to claim 1 or 2, characterized in that, the average length of the perovskite grains along the thickness direction of the perovskite layer is 400 nm to 600 nm.

4. The perovskite solar cell according to any one of claims 1 - 3, characterized in that, the electron transport layer includes one or more of an organic electron transport material, an inorganic electron transport material, an organic-inorganic hybrid electron transport material and its derivatives, and optionally includes one or more of imide compounds, quinone compounds, fullerenes and their derivatives, metal oxides, silicon oxides, strontium titanate, calcium titanate, lithium fluoride and calcium fluoride; optionally, the fullerenes and their derivatives include one or more of [6,6]-phenyl C71 butyric acid methyl ester, [6,6]-phenyl C61 butyric acid methyl ester; optionally, the metal elements in the metal oxides include one or more of Mg, Cd, Zn, In, Pb, W, Sb, Bi, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga and Cr.

5. The perovskite solar cell according to any one of claims 1 - 4, characterized in that, the electron transport layer includes a first electron transport layer and a second electron transport layer, the first electron transport layer includes PC61BM, and the second electron transport layer includes zinc peroxide.

6. The perovskite solar cell according to any one of claims 1 - 5, characterized in that, it sequentially includes a first electrode, a hole transport layer, the perovskite layer, the electron transport layer and a second electrode.

7. A method for preparing an electron transport layer of a perovskite solar cell, characterized in that, it includes: coating a first electron transport layer solution on the surface of the perovskite layer, wherein the perovskite layer includes perovskite grains; after drying to remove the solvent in the first electron transport layer solution, coating a polar organic solution on the surface of the perovskite layer; wherein the polar organic solution includes a polar organic solvent capable of dissolving the perovskite grains; after drying to remove the polar organic solvent, continuously coating a second electron transport layer solution on the surface of the perovskite layer; after drying to remove the solvent in the second electron transport layer solution, an electron transport layer is formed.

8. The preparation method according to claim 7, characterized in that, the average roughness of the surface of the perovskite layer is 24 nm to 35 nm.

9. The preparation method according to any one of claims 7 - 8, characterized in that, the polar organic solvent includes one or more of dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, ethanol, isopropanol, acetonitrile, methanol, propanol, acetone.

10. The preparation method according to claim 7 or 8, characterized in that, The perovskite grains include a compound with a general formula of ABX 3 ; the polar organic solution includes one or more of a cation ligand A and an anion ligand X; wherein, A represents a monovalent inorganic cation, an organic cation or an organic-inorganic hybrid cation, B represents a divalent inorganic cation, an organic cation or an organic-inorganic hybrid cation, and X represents a monovalent inorganic anion, an organic anion or an organic-inorganic hybrid anion; Optionally, A includes CH 3 NH 3 + , CH 3 CH 2 NH 3 + , (CH 3 ) 2 CHNH 3 + , CH(NH 2 ) 2 + , Ar-CH 3 CH 2 NH 3 + , Li + , Na + , K + , Rb + , Cs + or one or more of them; Optionally, B includes Pb 2+ , Sn 2+ , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Zn 2+ , Ge 2+ , Fe 2+ , Co 2+ , Ni 2+ or one or more of the following; Optionally, X includes F - , Cl - , Br - , I - or one or more of them.

11. The preparation method according to claim 10, characterized in that, the concentrations of the cationic ligand and the anionic ligand in the polar organic solution are respectively 0.5 mg / ml to 10 mg / ml.

12. The preparation method according to any one of claims 7-11, characterized in that, the methods of coating the polar organic solution on the surface of the perovskite layer include vapor method, spraying method, inkjet printing method, slot coating method and blade coating method.

13. The preparation method according to any one of claims 7-12, characterized in that, the drying conditions for drying the polar organic solvent satisfy: 1) The drying temperature is 60-150 °C; 2) The drying time is 8-15 min.

14. The preparation method according to any one of claims 7-13, characterized in that, the electron transport materials in the first electron transport layer solution and the second electron transport layer solution respectively independently include one or more of organic electron transport materials, inorganic electron transport materials, and organic-inorganic hybrid electron transport materials, and optionally include one or more of imide compounds, quinone compounds, fullerenes and their derivatives, metal oxides, silicon oxides, strontium titanate, calcium titanate, lithium fluoride and calcium fluoride; optionally, the fullerenes and their derivatives include one or more of [6,6]-phenyl C71 butyric acid methyl ester and [6,6]-phenyl C61 butyric acid methyl ester; optionally, the metal elements in the metal oxides include one or more of Mg, Cd, Zn, In, Pb, W, Sb, Bi, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga and Cr.

15. The preparation method according to any one of claims 7-14, characterized in that, the solvents in the first electron transport layer solution and the second electron transport layer solution respectively independently include one or more of benzene and its derivatives, alkanes and their derivatives; optionally, the benzene and its derivatives include one or more of toluene, chlorobenzene, o-dichlorobenzene, o-xylene, benzaldehyde, aniline, benzene, benzyl alcohol, benzyl benzoate, tetrahydrothiophene, styrene, anisole; optionally, the alkanes and their derivatives include one or more of dichloromethane, chloroform, dipentene, methyl tetrahydrofuran, cyclohexanone.

16. The preparation method according to any one of claims 7-15, characterized in that, the concentration of the first electron transport layer solution is 3 mg / ml to 30 mg / ml; and / or, the concentration of the second electron transport layer solution is 3 mg / ml to 30 mg / ml.

17. The preparation method according to any one of claims 7-16, characterized in that, the first electron transport layer solution and the second electron transport layer solution respectively independently include additives, and the additives include one or more of polystyrene, polymethyl methacrylate, lecithin, Triton, pyridine.

18. The preparation method according to any one of claims 7-17, characterized in that, The ratio of the coating thickness of the first electron transport layer solution to the coating thickness of the second electron transport layer solution is (0.5 - 5):

1.

19. The preparation method according to any one of claims 7 - 18, wherein, the coating thickness of the first electron transport layer solution is 5 μm to 20 μm; optionally 8 μm to 12 μm.

20. The preparation method according to any one of claims 7 - 19, wherein, the coating thickness of the second electron transport layer solution is 3 μm to 15 μm; optionally 5 μm to 12 μm.

21. The preparation method according to any one of claims 7 - 20, wherein, the coating methods of the first electron transport layer solution and the second electron transport layer solution each independently include any one of slot coating method and blade coating method; and / or, the coating methods of the polar organic solvent each independently include any one of slot coating method, blade coating method and spraying method.

22. A perovskite solar cell module, wherein, it includes the perovskite solar cell according to any one of claims 1 - 6 or the perovskite solar cell prepared by the preparation method according to any one of claims 7 - 21.

23. A tandem solar cell, wherein, it includes the perovskite solar cell module according to claim 22, and the tandem solar cell is used for providing electric energy.

24. An electrical device, wherein, it includes the tandem solar cell according to claim 23, and the perovskite solar cell module is used for providing electric energy.

25. A power generation device, wherein, it includes the tandem solar cell according to claim 22, and the perovskite solar cell module is used for providing electric energy.

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