Perovskite crystalline silicon laminated solar cell, preparation method thereof, photovoltaic module and electric equipment

Abstract

The invention discloses a perovskite crystalline silicon laminated solar cell, a preparation method thereof, a photovoltaic module and electric equipment. The perovskite crystalline silicon laminated solar cell comprises a bottom cell, a hole transport layer, a perovskite layer, a mesoporous electron transport layer, a compact electron transport layer and a conductive substrate which are sequentially laminated. According to the perovskite crystalline silicon laminated solar cell, the mesopore electron transport layer is arranged on the phototropic side of the perovskite layer, and a large number of mesopore structures are arranged in the mesopore electron transport layer; the solvent in the perovskite layer, especially the solvent in the layer center part, can be diffused and discharged through pores in the mesoporous electron transport layer, so that the solvent content in the perovskite layer is reduced, and the stability of the cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly relates to a perovskite-silicon tandem solar cell, a preparation method thereof, a photovoltaic module, and an electrical device. Background Art

[0002] The perovskite-silicon tandem solar cell is also known as a multi-junction solar cell or a multi-layer solar cell, and is a photovoltaic device formed by stacking multiple semiconductor materials with different bandgaps. This structure allows the cell to more effectively absorb and convert different parts of the solar spectrum, thereby improving the overall energy conversion efficiency. The perovskite-silicon tandem solar cell is usually prepared by a solution coating method, which has the advantages of simple process, low cost and high efficiency. However, the perovskite-silicon tandem solar cell prepared by the solution coating method has the problem of poor stability. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this reason, an object of the present invention is to provide a perovskite-silicon tandem solar cell, which has high stability.

[0004] Specifically, a first aspect of the present invention provides a perovskite-silicon tandem solar cell, including: a bottom cell, a hole transport layer, a perovskite layer, a mesoporous electron transport layer, a dense electron transport layer, and a conductive substrate, which are sequentially stacked.

[0005] The perovskite layer is the core layer of the perovskite cell. Improving the stability of the perovskite layer helps to improve the stability of the cell. In the present invention, a mesoporous electron transport layer is provided on the light-facing side of the perovskite layer. This layer has a large number of mesoporous structures. During the preparation of the perovskite-silicon tandem solar cell by the solution coating method, the solvent in the perovskite layer, especially the solvent existing in the central part of the layer, can diffuse and be discharged through the pores in the mesoporous electron transport layer, thereby reducing the solvent content in the perovskite layer and improving the stability of the cell.

[0006] According to some embodiments of the present invention, the porosity of the mesoporous electron transport layer is 5%-40%. During the preparation of the perovskite-silicon tandem solar cell by the solution coating method, the solvent in the layer structure adjacent to the mesoporous electron transport layer can diffuse to the outside of the cell through the pores in the mesoporous electron transport layer, reducing the solvent content in the layer. Therefore, optimizing the porosity of the mesoporous electron transport layer is beneficial to the diffusion and discharge of the solvent, and further beneficial to improving the stability of the cell.

[0007] According to some embodiments of the present invention, the porosity of the mesoporous electron transport layer is 18%-32%. Optimizing the porosity of the mesoporous electron transport layer is beneficial to further improving the diffusion and discharge effect of the solvent and improving the stability of the cell.

[0008] According to some embodiments of the present invention, the thickness of the mesoporous electron transport layer is 1 μm - 5 μm. Optimizing the thickness of the mesoporous electron transport layer is beneficial to improving the diffusion and discharge of the solvent, and enhancing the stability of the battery.

[0009] According to some embodiments of the present invention, the surface of the bottom cell close to the hole transport layer has a matte structure, and the surface of the hole transport layer close to the perovskite layer has a matte structure. The hole transport layer of the present invention is formed on the surface of the matte bottom cell. By controlling the growth thickness of the hole transport layer, the surface of the hole transport layer can also have a matte structure. The matte structure is also beneficial to the diffusion and discharge of the solvent in the perovskite layer, especially the solvent existing in the central part of the layer. Thus, one side of the perovskite layer of the present invention has a mesoporous structure, and the other side has a matte structure, which is conducive to the complete diffusion and discharge of the solvent in the perovskite layer, and improves the stability of the battery.

[0010] According to some embodiments of the present invention, the matte structure of the bottom cell includes a plurality of pyramid structures, and the height of the pyramid structures is above 2 μm. Controlling the height of the pyramid structures within the scope of the present invention is beneficial to making the surface of the hole transport layer formed thereon also have a matte structure, thereby facilitating the complete discharge of the solvent in the perovskite layer and improving the battery stability.

[0011] According to some embodiments of the present invention, the solvent content in the perovskite layer is 0.1 wt% - 1 wt%. The lower the solvent content, the higher the stability of the perovskite layer and the higher the stability of the battery.

[0012] The second aspect of the present invention provides a method for preparing the perovskite-silicon tandem solar cell of the first aspect of the present invention, including the following steps:

[0013] Provide a bottom cell;

[0014] Successively stack and form a hole transport layer and a first perovskite wet film layer on the light-facing side of the bottom cell;

[0015] Provide a conductive substrate;

[0016] Successively stack and form a dense electron transport layer, a mesoporous electron transport layer and a second perovskite wet film layer on the conductive side of the conductive substrate;

[0017] Stack the first perovskite wet film layer and the second perovskite wet film layer in an opposite direction and then perform thermal pressing to obtain the perovskite-silicon tandem solar cell.

[0018] In the present invention, a perovskite wet film layer is respectively formed with a dense electron transport layer, a mesoporous electron transport layer, and a bottom cell to form two sub-cells, and then the two sub-cells are thermally laminated to form a tandem cell. During the preparation process, the solvent in the perovskite wet film layer can diffuse and be discharged through the mesoporous structure in the mesoporous electron transport layer, reducing the solvent content in the perovskite layer and improving the stability of the tandem cell. In addition, the preparation method of the present invention can also reduce the damage to the perovskite layer during the subsequent preparation of the functional layers of the perovskite / crystalline silicon tandem solar cell, and reduce the preparation cost.

[0019] According to some embodiments of the present invention, before forming the dense electron transport layer, the method further includes: preparing an electron transport solution containing an electron transport material, the concentration of the electron transport solution being 0.1 mg / ml - 5 mg / ml, and the average particle size of the electron transport material being 10 nm - 50 nm. The concentration of the electron transport solution and the average particle size of the electron transport material powder itself affect the porosity of the mesoporous electron transport layer. Optimizing these two parameters within the scope of the present invention is beneficial to the complete diffusion and discharge of the solvent in the perovskite layer, and improves the stability of the battery.

[0020] According to some embodiments of the present invention, the concentration of the electron transport solution is 0.5 mg / m1 - 2 mg / ml, and the average particle size of the electron transport material is 15 nm - 30 nm. Optimizing the concentration of the electron transport solution and the average particle size of the electron transport material powder is beneficial to controlling the porosity of the mesoporous electron transport layer to promote the complete diffusion and discharge of the solvent in the perovskite layer, and improves the stability of the battery.

[0021] According to some embodiments of the present invention, forming the mesoporous electron transport layer includes: coating the electron transport solution on the dense electron transport layer and annealing at 450°C - 550°C for 20 min - 40 min. The annealing temperature affects the porosity of the electron transport layer. Optimizing the annealing temperature is beneficial to controlling the porosity of the mesoporous electron transport layer to promote the complete diffusion and discharge of the solvent in the perovskite layer, and improves the stability of the battery.

[0022] The third aspect of the present invention provides a photovoltaic module, including the perovskite / crystalline silicon tandem solar cell of the first aspect of the present invention or the perovskite / crystalline silicon tandem solar cell obtained by the method of the second aspect of the present invention. Due to the adoption of the above perovskite / crystalline silicon tandem solar cell, the photovoltaic module of the present invention also has all the advantages of the above battery, which will not be elaborated here.

[0023] The fourth aspect of the present invention provides an electrical device, including the perovskite / crystalline silicon tandem solar cell of the first aspect of the present invention or the perovskite / crystalline silicon tandem solar cell obtained by the method of the second aspect of the present invention. Due to the adoption of the above perovskite / crystalline silicon tandem solar cell, the electrical device of the present invention also has all the advantages of the above battery, which will not be elaborated here.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0026] Figure 1 is a schematic structural diagram of a perovskite-silicon tandem solar cell according to some embodiments of the present invention.

[0027] Figure 2 is a schematic structural diagram of a perovskite-silicon tandem solar cell according to some other embodiments of the present invention.

[0028] Figure 3 is a flowchart of the preparation of a perovskite-silicon tandem solar cell according to some embodiments of the present invention.

[0029] Reference Signs:

[0030] 1000, perovskite-silicon tandem solar cell; 100, bottom cell; 101, textured surface structure; 200, hole transport layer; 202, pyramid structure; 300, perovskite layer; 301, first perovskite wet film layer; 302, second perovskite wet film layer; 400, mesoporous electron transport layer; 500, dense electron transport layer; 600, conductive substrate; 601, substrate; 602, transparent conductive layer; 700, first electrode; 800, second electrode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0032] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Further, in the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more, and the meaning of "a plurality" is two or more.

[0033] The endpoints and any values in the ranges disclosed in this document are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this document.

[0034] In this document, the term "comprising" or "including" is an open-ended expression, that is, it includes the content specified in the present invention, but does not exclude other aspects of the content.

[0035] Perovskite-silicon tandem solar cells, also known as multi-junction solar cells or multi-layer solar cells, are photovoltaic devices formed by stacking multiple semiconductor materials with different bandgaps. This structure allows the cell to more effectively absorb and convert different parts of the solar spectrum, thereby improving the overall energy conversion efficiency. Perovskite-silicon tandem solar cells are usually prepared by solution coating method, with a simple process, low cost and high efficiency. However, perovskite-silicon tandem solar cells prepared by solution coating method have the problem of poor stability.

[0036] The perovskite layer is the core layer of the perovskite cell. Improving the stability of the perovskite layer helps to improve the stability of the cell. Through research, it is found that a relatively high solvent content in the perovskite layer will cause the stability of the perovskite-silicon tandem solar cell to deteriorate. In order to improve the stability of the perovskite-silicon tandem solar cell, the present invention provides a perovskite-silicon tandem solar cell, in which a mesoporous electron transport layer is provided on the light-facing side of the perovskite layer. This layer has a large number of mesoporous structures. During the process of preparing the perovskite-silicon tandem solar cell by solution coating method, the solvent in the perovskite layer, especially the solvent present in the central part of the layer, can diffuse and discharge through the pores in the mesoporous electron transport layer, thereby reducing the solvent content in the perovskite layer and improving the stability of the cell.

[0037] Specifically, referring to Figure 1 , the first aspect of the present invention provides a perovskite-silicon tandem solar cell 1000, comprising: a bottom cell 100, a hole transport layer 200, a perovskite layer 300, a mesoporous electron transport layer 400, a dense electron transport layer 500, and a conductive substrate 600, which are sequentially stacked.

[0038] In the present invention, the pore diameter of the mesopores is in the range of 2 nm - 50 nm.

[0039] In some embodiments, the porosity of the mesoporous electron transport layer 400 can be 5%-40%. During the preparation of the perovskite / silicon tandem solar cell 1000 by solution coating, the solvents in the layer structure adjacent to the mesoporous electron transport layer 400 can diffuse to the outside of the cell through the pores in the mesoporous electron transport layer 400, reducing the solvent content in the layer. Therefore, optimizing the porosity of the mesoporous electron transport layer 400 is beneficial to the diffusion and discharge of the solvent, and further beneficial to improving the stability of the cell.

[0040] In some specific embodiments, the porosity of the mesoporous electron transport layer 400 can be 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%.

[0041] In some embodiments, the porosity of the mesoporous electron transport layer 400 can be 18%-32%. Optimizing the porosity of the mesoporous electron transport layer 400 is beneficial to further improving the diffusion and discharge effect of the solvent and improving the stability of the cell.

[0042] In some embodiments, the thickness of the mesoporous electron transport layer 400 can be 1 μm - 5 μm. Optimizing the thickness of the mesoporous electron transport layer 400 is beneficial to improving the diffusion and discharge of the solvent and improving the stability of the cell.

[0043] In some specific embodiments, the thickness of the mesoporous electron transport layer 400 can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm.

[0044] In some specific embodiments, the material of the mesoporous electron transport layer 400 includes at least one of titanium tetrachloride (TiCl4), tin dioxide (SnO2), [6,6]-phenyl-C 61 -isobutyl methacrylate (PCBM).

[0045] In some specific embodiments, the material of the compact electron transport layer 500 includes at least one of titanium tetrachloride (TiCl4), tin dioxide (SnO2), [6,6]-phenyl-C 61 -isobutyl methacrylate (PCBM).

[0046] In some specific embodiments, the porosity of the compact electron transport layer 500 can be below 4.5%, such as 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5% or 1%.

[0047] In some specific embodiments, the thickness of the compact electron transport layer 500 can be 0.1 μm - 1 μm, such as 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm.

[0048] In some embodiments, the surface of the bottom cell 100 close to the hole transport layer 200 has a matte structure 101, and the surface of the hole transport layer 200 close to the perovskite layer 300 has a matte structure. The hole transport layer 200 of the present invention is formed on the surface of the matte bottom cell. By controlling the growth thickness of the hole transport layer 200, the surface of the hole transport layer 200 can also have a matte structure, which is also beneficial to the diffusion and discharge of the solvent in the perovskite layer 300, especially the solvent existing in the central part of the layer. Thus, one side of the perovskite layer 300 of the present invention has a mesoporous structure, and the other side has a matte structure, which is beneficial to the complete diffusion and discharge of the solvent in the perovskite layer 300 and improves the stability of the battery.

[0049] In some embodiments, the matte structure 101 of the bottom cell 100 includes a plurality of pyramid structures 202 (such as Figure 2 the structure in the dotted line circle), and the height of the pyramid structure 202 is above 2 μm. Controlling the height of the pyramid structure 202 within the scope of the present invention is beneficial to making the surface of the hole transport layer 200 formed thereon also have a matte structure, thereby facilitating the complete discharge of the solvent in the perovskite layer 300 and improving the battery stability.

[0050] In some specific embodiments, the height of the pyramid structure 202 of the bottom cell 100 is above 2 μm, for example, 2 μm, 3 μm, 4 μm or 5 μm. The height of the pyramid structure 202 can be adjusted by existing known methods. The matte bottom cell with the height of the pyramid structure above 2 μm can be purchased or prepared by methods known in the art.

[0051] In the present invention, the "height of the pyramid structure" refers to the height from the top of the pyramid to the bottom of the pyramid.

[0052] In some embodiments, the bottom cell 100 includes a crystalline silicon bottom cell. A transparent conductive oxide layer may be deposited on the surface of the bottom cell 100 close to the hole transport layer 200. The material of the transparent conductive oxide layer includes one or more of indium tin oxide (ITO), zinc tin oxide (ZTO), and cadmium tin oxide (CTO).

[0053] In some embodiments, the solvent content in the perovskite layer 300 may be 0.1 wt% - 1 wt%, for example, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt% or 1 wt%. The lower the solvent content, the higher the stability of the perovskite layer 300 and the higher the stability of the battery.

[0054] In some embodiments, the solvent content in the perovskite layer 300 may be 0.3% - 0.6%.

[0055] In some embodiments, referring to Figure 2, the conductive substrate 600 includes a substrate 601 and a transparent conductive layer 602. The perovskite-silicon tandem solar cell 1000 further includes: a first electrode 700 disposed on a side of the bottom cell 100 away from the hole transport layer 200; a second electrode 800 connected to the transparent conductive layer 602 of the conductive substrate 600. The present invention does not particularly limit the materials of the first electrode 700 and the second electrode 800, and those skilled in the art can select corresponding conductive materials according to actual needs. For example, the materials of both the first electrode 700 and the second electrode 800 are silver. In some specific embodiments, the second electrode 800 may be a metal strip connected to the transparent conductive layer 602, such as a silver strip. In some specific embodiments, the material of the transparent conductive layer 602 includes one or more of indium tin oxide (ITO), zinc tin oxide (ZTO), and cadmium tin oxide (CTO). The present invention does not particularly limit the material of the substrate 601, and those skilled in the art can select it according to actual needs, such as a glass substrate, etc.

[0056] In some specific embodiments, both surfaces of the bottom cell 100 have a matte structure. The first electrode 700 is disposed on the matte structure of the bottom cell 100.

[0057] In some embodiments, the perovskite layer 300 serves as a light absorption layer and can convert photons into holes and electrons. Its material can be selected from conventional materials in the art, which is not limited herein, and those skilled in the art can select according to actual needs. As some specific examples, the material of the perovskite layer 300 described above can be a three-dimensional structure ABX3-type perovskite material, where A is a monovalent cation, including but not limited to at least one of cesium (Cs), rubidium (Rb), methylammonium (CH3NH3, generally abbreviated as MA), and formamidinium (CH2(NH2)2, generally abbreviated as FA); B is a divalent cation, including but not limited to at least one of lead (Pb), copper (Cu), zinc (Zn), gallium (Ga), tin (Sn), and calcium (Ca); X is a monovalent anion, including but not limited to at least one of iodine (I), bromine (Br), chlorine (Cl), fluorine (F), and thiocyanate ion (SCN).

[0058] In some embodiments, the hole transport layer 200, as a transport layer, can effectively transport holes. Its material can be selected from conventional materials in the art, which is not limited herein, and those skilled in the art can choose according to actual needs. As some specific examples, the hole transport layer 200 material can include at least one of SAM materials and metal-containing semiconductors. Among them, the SAM materials can include at least one of [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), [4-(7H-dibenzocarbazol-7-yl)butyl]phosphonic acid (4PADCB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), 4,4′-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (TAPC). The hole transport layer 200 material can be nickel oxide (NiO x ).

[0059] In some embodiments, the thickness of the hole transport layer 200 can be 1 nm - 10 nm, such as 1 nm, 2 nm, 4 nm, 6 nm, 8 nm or 10 nm.

[0060] The second aspect of the present invention provides a method for preparing the above-mentioned perovskite-silicon tandem solar cell 1000. Refer to Figure 3 , this method includes the following steps:

[0061] Provide the bottom cell 100;

[0062] Form a hole transport layer 200 and a first perovskite wet film layer 301 in sequence on the light-facing side of the bottom cell 100;

[0063] Provide a conductive substrate 600;

[0064] Form a dense electron transport layer 500, a mesoporous electron transport layer 400 and a second perovskite wet film layer 302 in sequence on the conductive side of the conductive substrate 600;

[0065] Overlay the first perovskite wet film layer 301 and the second perovskite wet film layer 302 in opposite directions and then perform thermal pressing to obtain the perovskite-silicon tandem solar cell 1000.

[0066] The present invention forms two sub-cells by using a perovskite wet film layer to form 2 sub-cells with a dense electron transport layer 500, a mesoporous electron transport layer 400, and a bottom cell 100 respectively, and then thermally laminating the 2 sub-cells to form a tandem cell. During the preparation process, the solvent in the perovskite wet film layer can diffuse and discharge through the mesoporous structure in the mesoporous electron transport layer 400, reducing the solvent content in the perovskite layer 300 and improving the stability of the tandem cell. In addition, the preparation method of the present invention can also reduce the damage to the perovskite layer 300 during the subsequent functional layer preparation of the perovskite / crystalline silicon tandem solar cell 1000 and reduce the preparation cost.

[0067] In some embodiments, before forming the dense electron transport layer 500, the method further includes: preparing an electron transport solution containing an electron transport material, the concentration of the electron transport solution can be 0.1 mg / ml - 5 mg / ml, and the average particle size of the electron transport material can be 10 nm - 50 nm. The concentration of the electron transport solution and the average particle size of the electron transport material powder itself affect the porosity of the mesoporous electron transport layer 400. Optimizing these two parameters within the scope of the present invention is beneficial to the complete diffusion and discharge of the solvent in the perovskite layer 300 and improves the stability of the cell.

[0068] In some specific embodiments, the concentration of the electron transport solution can be 0.1 mg / ml, 0.5 mg / ml, 1 mg / ml, 1.5 mg / ml, 2 mg / ml, 2.5 mg / ml, 3 mg / ml, 3.5 mg / ml, 4 mg / ml, 4.5 mg / ml or 5 mg / ml.

[0069] In some specific embodiments, the average particle size of the electron transport material can be 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 50 nm.

[0070] In some embodiments, the concentration of the electron transport solution can be 0.5 mg / ml - 2 mg / ml, and the average particle size of the electron transport material can be 15 nm - 30 nm. Optimizing the concentration of the electron transport solution and the average particle size of the electron transport material powder is beneficial to controlling the porosity of the mesoporous electron transport layer 400 to promote the complete diffusion and discharge of the solvent in the perovskite layer 300 and improve the stability of the cell.

[0071] In some embodiments, forming the mesoporous electron transport layer 400 includes: coating the electron transport solution on the dense electron transport layer 500 and annealing at 450 °C - 550 °C for 20 min - 40 min. The annealing temperature affects the porosity of the electron transport layer. Optimizing the annealing temperature is beneficial to controlling the porosity of the mesoporous electron transport layer 400 to promote the complete diffusion and discharge of the solvent in the perovskite layer 300 and improve the stability of the cell.

[0072] In some specific embodiments, in the step of forming the mesoporous electron transport layer 400, the annealing temperature can be 450 °C, 460 °C, 470 °C, 480 °C, 490 °C, 500 °C, 510 °C, 520 °C, 530 °C, 540 °C or 550 °C. The annealing time can be 20 min, 25 min, 30 min, 35 min or 40 min.

[0073] In some embodiments, forming the dense electron transport layer 500 includes: coating an electron transport solution on the conductive side of the conductive substrate 600 and annealing at 100 °C - 150 °C for 5 min - 20 min.

[0074] In some specific embodiments, in the step of forming the dense electron transport layer 500, the annealing temperature can be 100 °C, 110 °C, 120 °C, 130 °C, 140 °C or 150 °C. The annealing time can be 5 min, 10 min, 15 min or 20 min.

[0075] In some embodiments, the pressing pressure of the hot pressing can be 20 Pa - 2000 Pa, for example, 20 Pa, 50 Pa, 100 Pa, 500 Pa, 1000 Pa, 1500 Pa or 2000 Pa. The "pressing pressure" refers to the pressure applied from the outside.

[0076] In some embodiments, the temperature of the hot pressing can be 100 °C - 160 °C, for example, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C or 160 °C.

[0077] In some embodiments, the time of the hot pressing can be 10 min - 100 min, for example, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min or 100 min.

[0078] In some embodiments, the hot pressing is carried out under a vacuum pressure of 0.01 Pa - 10 Pa. The vacuum pressure can be, for example, 0.01 Pa, 0.1 Pa, 1 Pa, 2 Pa, 4 Pa, 6 Pa, 8 Pa or 10 Pa.

[0079] In some embodiments, the method of the present invention further includes preparing a perovskite precursor solution. In some specific embodiments, preparing the perovskite precursor solution includes mixing at least one of PbI2, PbCl2, CsBr, CsI, PbBr2 with at least one of formamidinium hydroiodide (FAI), formamidinium hydrobromide (FABr), methylammonium bromide (MABr), formamidinium hydrochloride (FACl) in a solvent.

[0080] In some embodiments, forming the perovskite layer 300 includes: coating a perovskite precursor solution onto the hole transport layer 200 or the mesoporous electron transport layer 400 by spin coating, slot die coating, or evaporation coating. The spin coating conditions can be a rotation speed of 2000 rpm - 5000 rpm (such as 2000 rpm, 3000 rpm, 4000 rpm, or 5000 rpm) and a time of 10 s - 60 s (such as 10 s, 20 s, 30 s, 40 s, 50 s, or 60 s).

[0081] The third aspect of the present invention provides a photovoltaic module, including the perovskite-silicon tandem solar cell 1000 of the first aspect of the present invention or the perovskite-silicon tandem solar cell 1000 obtained by the method of the second aspect of the present invention. Due to the adoption of the above perovskite-silicon tandem solar cell 1000, the photovoltaic module of the present invention also has all the advantages of the above battery, which will not be elaborated here.

[0082] The fourth aspect of the present invention provides an electrical device, including the perovskite-silicon tandem solar cell 1000 of the first aspect of the present invention or the perovskite-silicon tandem solar cell 1000 obtained by the method of the second aspect of the present invention. Due to the adoption of the above perovskite-silicon tandem solar cell 1000, the electrical device of the present invention also has all the advantages of the above battery, which will not be elaborated here.

[0083] Specifically, the electrical device can include lighting elements, display elements, mobile devices, etc. Specifically, it can include street lamps, signal indicators, insecticidal lamps, electric fans, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toys can include fixed or mobile electric toys. For example, game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc. The spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0084] Next, the solutions of the present invention will be explained in conjunction with embodiments. Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0085] Example 1

[0086] (1) Wash the glass substrate sputtered with ITO (abbreviated as ITO substrate, i.e., conductive substrate) by ultrasonic cleaning with a mixed solution of deionized water and detergent, deionized water, and ethanol for 15 minutes each in sequence, and then blow it dry with an N2 gun for standby.

[0087] (2) The ethanol solution of TiCl4 with a concentration of 2 mol / ml (the average particle size of the raw material TiCl4 powder is 20 nm) was diluted 128 times by volume with deionized water to obtain an electron transport solution (TiCl4 concentration is 1 mg / ml). The electron transport material was deposited on the surface of the ITO substrate by spin coating. After annealing at 100 °C for 10 min, a dense TiO2 layer (i.e., a dense electron transport layer) was formed, with a thickness of 10 nm.

[0088] (3) The solution prepared in step 2 was spin-coated on the dense electron transport layer, and a mesoporous TiO2 layer (i.e., a mesoporous electron transport layer) with a thickness of 2 μm was obtained through high-temperature sintering at 500 °C for 30 min.

[0089] (4) CsI, MABr, FAI, PbBr2, and PbI2 were dissolved in a mixture of 800 μL of DMF and 200 μL of DMSO to prepare a perovskite precursor solution. Among them, the concentration of CsI was 22.08 mg / ml, the concentration of MABr was 28.55 mg / ml, the concentration of FAI was 238.88 mg / ml, the concentration of PbBr2 was 190.92 mg / ml, and the concentration of PbI2 was 559.57 mg / ml.

[0090] (5) The perovskite precursor solution in step 4 was coated on the mesoporous electron transport layer by spin coating. The spin coating conditions were a rotation speed of 4000 r and a time of 30 s to obtain a perovskite wet film layer, thereby obtaining the first sub-cell. The thickness of the perovskite wet film layer was 600 nm.

[0091] (6) The Me-4PACz ethanol solution with a concentration of 0.5 mg / ml was deposited on the crystalline silicon bottom cell (both sides have a textured structure, where the height of the pyramid structure is 2 μm. The structure of the crystalline silicon bottom cell: from bottom to top, it includes Ag\ITO\α-Si(P)\a-Si(i)\a-Si:H(i)\c-Si\a-Si:H(i)\a-Si:H(n)\nc-Si:H(n+)\nc-Si:H(p+)) by spin coating. The spin coating speed was 4000 rpm / s, the time was 30 s, and annealing was carried out at 100 °C for 10 min to prepare and form a SAMs layer, that is, a hole transport layer, with a thickness of 8 nm.

[0092] (7) The perovskite precursor solution prepared in step 4 was prepared on the hole transport layer by spin coating. The spin coating conditions were a rotation speed of 4000 r and a time of 30 s to obtain a perovskite wet film layer, thereby obtaining the second sub-cell. The thickness of the perovskite wet film layer was 1.2 μm.

[0093] (8) After laminating the first sub-cell and the second sub-cell obtained in Step 5 and Step 7 in the direction where the perovskite wet films face each other, pressing them tightly under a pressure of 1000 Pa, and then annealing them in a vacuum annealing (VCD) device (vacuum pressure is 1 Pa) for 30 minutes, a perovskite / silicon tandem solar cell is fabricated, and the thickness of the perovskite layer is 1.5 μm.

[0094] Examples 2 - 29

[0095] Examples 2 - 29 were all prepared for perovskite / silicon tandem solar cells according to the method described in Example 1, and the differences are listed in Table 1 below.

[0096] Comparative Example 1

[0097] A perovskite / silicon tandem solar cell was prepared according to the method described in Example 1, except that the mesoporous electron transport layer was not formed.

[0098] Comparative Example 2

[0099] A perovskite / silicon tandem solar cell was prepared according to the method described in Example 1, except that a hole transport layer was formed on the conductive substrate, and a dense electron transport layer and a mesoporous electron transport layer were successively formed on the bottom cell. The cell structure was a bottom cell, a dense electron transport layer, a mesoporous electron transport layer, a perovskite layer, a hole transport layer, and a conductive substrate stacked in sequence. The formation method of each layer was the same as that in Example 1.

[0100] Testing Methods

[0101] Porosity Test of Mesoporous Electron Transport Layer:

[0102] The cross-section of the sample was tested by SEM (scanning electron microscope), and the porosity of the thin film was calculated by dividing the void area of the sample by the total area of the material. The results are shown in Table 1 below.

[0103] Thickness Test of Mesoporous Electron Transport Layer:

[0104] The thickness of the mesoporous transport layer can be measured by ellipsometry. The results are shown in Table 1 below.

[0105] Solvent Content Test in Perovskite Layer:

[0106] The test was carried out by thermogravimetric analysis (TGA), and the solvent content in the material was analyzed and calculated using the TGA curve obtained during the test. The results are shown in Table 1 below.

[0107] Battery Stability Test:

[0108] The operating stability of the battery can be measured through the maximum power point tracking (MPPT) test of the battery. A constant bias voltage is applied at the highest power output point in the J-V curve, and it is observed whether the output current of the battery tends to be stable under continuous light illumination and long-term bias voltage. The steady-state efficiency is calculated through the measured stable current (V mp *I mp *100%, V mp 、Imp are the voltage and current corresponding to the maximum power respectively), that is, the MPPT efficiency. The results are shown in Table 1 below.

[0109] Table 1

[0110]

[0111]

[0112]

[0113]

[0114] By comparing the above examples and Comparative Example 1, it can be seen that the present invention provides a mesoporous electron transport layer on the light-facing side of the perovskite layer. This layer has a large number of mesoporous structures. During the preparation of the perovskite / silicon tandem solar cell by the solution coating method, the solvent in the perovskite layer, especially the solvent present in the central part of the layer, can diffuse and be discharged through the pores in the mesoporous electron transport layer, thereby reducing the solvent content in the perovskite layer and improving the stability of the battery.

[0115] By comparing the above examples and Comparative Example 2, it can be seen that the present invention sequentially stacks a textured bottom cell, a hole transport layer, a perovskite layer, a mesoporous electron transport layer, a dense electron transport layer, and a conductive substrate. The hole transport layer has a pyramid structure due to being disposed on the textured surface. The solvent can be discharged through both the hole transport layer and the mesoporous electron transport layer, which is beneficial to the complete diffusion and discharge of the solvent in the perovskite layer and improves the stability of the battery.

[0116] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without conflict, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0117] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A perovskite crystalline silicon tandem solar cell, characterized in that: include: A bottom battery, a hole transport layer, a perovskite layer, a mesoporous electron transport layer, a dense electron transport layer and a conductive substrate are stacked in sequence.

2. The perovskite crystalline silicon tandem solar cell according to claim 1, characterized in that: The porosity of the mesoporous electron transport layer is 5%-40%.

3. The perovskite crystalline silicon tandem solar cell according to claim 2, characterized in that: The porosity of the mesoporous electron transport layer is 18%-32%.

4. The perovskite crystalline silicon tandem solar cell according to any one of claims 1 to 3, characterized in that: The thickness of the mesoporous electron transport layer is 1 μm-5 μm.

5. The perovskite crystalline silicon tandem solar cell according to any one of claims 1 to 3, characterized in that: The surface of the bottom cell close to the hole transport layer has a velvet structure, and the surface of the hole transport layer close to the perovskite layer has a velvet structure.

6. The perovskite crystalline silicon tandem solar cell according to claim 5, characterized in that: The textured structure of the bottom battery includes a plurality of pyramid structures, and the height of the pyramid structures is greater than 2 μm.

7. The perovskite crystalline silicon tandem solar cell according to any one of claims 1 to 3, characterized in that: The solvent content in the perovskite layer is 0.1 wt%-1 wt%.

8. A method for preparing the perovskite crystalline silicon tandem solar cell according to any one of claims 1 to 7, characterized in that: The following steps are involved: Provide bottom battery; On the light-facing side of the bottom cell, a hole transport layer and a first perovskite wet film layer are sequentially stacked; providing a conductive substrate; On the conductive side of the conductive substrate, a dense electron transport layer, a mesoporous electron transport layer and a second perovskite wet film layer are sequentially stacked; The first perovskite wet film layer and the second perovskite wet film layer are overlapped in opposite directions and then heat-pressed to obtain the perovskite crystalline silicon stacked solar cell.

9. The method according to claim 8, characterized in that Before forming the dense electron transport layer, the method further comprises: preparing an electron transport solution containing an electron transport material, wherein the concentration of the electron transport solution is 0.1 mg / ml-5 mg / ml, and the average particle size of the electron transport material is 10 nm-50 nm.

10. The method according to claim 9, characterized in that The concentration of the electron transport solution is 0.5 mg / ml-2 mg / ml, and the average particle size of the electron transport material is 15 nm-30 nm.

11. The method according to claim 9, characterized in that Forming the mesoporous electron transport layer comprises: coating the electron transport solution on the dense electron transport layer, and annealing at 450° C.-550° C. for 20 min-40 min.

12. A photovoltaic module, characterized in that: A perovskite crystalline silicon tandem solar cell comprising the perovskite crystalline silicon tandem solar cell according to any one of claims 1 to 7 or a perovskite crystalline silicon tandem solar cell obtained by the method according to any one of claims 8 to 11.

13. An electrical equipment, characterized in that: A perovskite crystalline silicon tandem solar cell comprising the perovskite crystalline silicon tandem solar cell according to any one of claims 1 to 7 or a perovskite crystalline silicon tandem solar cell obtained by the method according to any one of claims 8 to 11.

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