A laminated solar cell and a method of manufacturing and use thereof

Abstract

This invention relates to a tandem solar cell, its fabrication method, and its application. The tandem solar cell comprises a top layer of perovskite cells and a bottom layer of back contact cells stacked sequentially from top to bottom. The perovskite cells include a front glass layer, a first passivation layer, a perovskite composite layer, and a second passivation layer stacked sequentially from top to bottom. The perovskite composite layer includes at least two polar perovskite regions and perovskite electrodes disposed on both sides of each polar perovskite region in a first direction. The back contact cells include a back glass layer, a back electrode layer, and a crystalline silicon layer stacked sequentially from bottom to top. In the solar cell provided by this invention, the perovskite composite layer of the perovskite cell is designed with a specific structure using polar perovskite and perovskite electrodes to form a built-in electric field, driving the directional movement of electron-hole pairs to generate current. Combined with the introduction of the back contact cells, more solar radiation is received, thus improving the performance of the tandem solar cell.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a tandem solar cell, its fabrication method, and its application. Background Technology

[0002] Perovskite-silicon tandem solar cells are a novel photovoltaic cell structure consisting of two or more solar cells with different band gaps stacked together. The perovskite cell acts as the top cell, and the crystalline silicon cell acts as the bottom cell. The perovskite material at the top has a wider band gap, absorbing high-energy photons, while the crystalline silicon at the bottom has a narrower band gap, absorbing low-energy photons (such as red and near-infrared light). This allows for more efficient utilization of the solar spectrum, reduces heat loss, and improves conversion efficiency.

[0003] Existing technology CN119212414A discloses a high-efficiency perovskite-crystalline silicon tandem solar cell module, including a top cell, a bottom cell, and an encapsulation structure. The top cell includes a top electrode, an antireflection layer, a first conductive layer, a buffer layer, an electron transport layer, a perovskite absorber layer, a hole transport layer, and a second conductive layer. The bottom cell includes an n-type doped layer, a first silicon oxide layer, a silicon substrate, a second silicon oxide layer, a p-type doped layer, and a bottom electrode. This prior art improves the perovskite absorber layer by constructing a three-dimensional / two-dimensional hybrid structure, which provides good stability while ensuring high conversion efficiency. The perovskite top cell is then combined with the crystalline silicon bottom cell and encapsulated using an encapsulation structure. The alumina thin film layer effectively suppresses ion migration and phase separation, and blocks the penetration of water and oxygen molecules, thereby improving the overall performance of the perovskite-crystalline silicon tandem solar cell and making it more suitable for harsh environments such as deserts.

[0004] However, the perovskite absorber layer in the existing tandem solar cells described above, which uses a hybrid three-dimensional / two-dimensional structure, and the three-dimensional perovskite layer commonly used in mainstream tandem solar cells, both require the use of materials with different energy levels on both sides of the perovskite layer and the crystalline silicon layer to create a potential difference. Furthermore, an external PN junction needs to be constructed to induce the directional movement of electrons and holes, thereby generating current. On the one hand, the range of electrode materials that can be selected in the current battery structure is limited, requiring consideration of both conductivity and the potential difference between the two electrodes. On the other hand, the interface recombination between the designed electrode materials and the hole transport layer and electron transport layer can lead to energy loss. The hole transport layer and electron transport layer also affect the transmission of sunlight, thus preventing the effective improvement of the tandem solar cell's performance. In addition, because the positive and negative electrodes of crystalline silicon solar cells are usually distributed on the front and back of the cell, the front electrode can also block some incident light, preventing effective light absorption and thus reducing the cell's photoelectric conversion efficiency.

[0005] Therefore, in order to address the shortcomings of the existing technology, providing a tandem solar cell that can reduce energy loss and shading of sunlight to improve the photoelectric conversion efficiency of the cell has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a tandem solar cell, its fabrication method, and its applications. The present invention designs the perovskite composite layer of the top cell, utilizing a specific structure and polar materials to generate a driving force that induces the directional movement of electrons, generating current. This reduces energy loss due to material interface recombination and the shading of sunlight by conductive materials. Combined with the selection of a back-contact cell in the bottom layer, the bottom cell is unobstructed from the front, receiving more solar radiation and effectively improving the photoelectric performance of the tandem solar cell.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a tandem solar cell, the tandem solar cell comprising a top perovskite cell and a bottom back contact cell stacked sequentially from top to bottom;

[0009] The perovskite solar cell comprises, from top to bottom, a front glass layer, a first passivation layer, a perovskite composite layer, and a second passivation layer stacked sequentially; the perovskite composite layer comprises at least two polar perovskite regions and perovskite electrodes disposed on both sides of each polar perovskite region in a first direction; the first direction is perpendicular to the stacking direction of the tandem solar cell.

[0010] The back contact battery includes a back glass layer, a back electrode layer, and a crystalline silicon layer stacked sequentially from bottom to top; the crystalline silicon layer in the back contact battery is in contact with and bonded to the second passivation layer in the perovskite battery.

[0011] The tandem solar cell provided by this invention consists of a back-contact cell as the bottom layer and a perovskite cell as the top layer. The perovskite composite layer, composed of polar perovskite regions and perovskite electrodes, has a specific structure. Under the influence of light, the polar perovskite regions absorb photon energy, causing the perovskite itself to become polar, forming a built-in electric field. This induces the directional movement of electrons and leaves holes. Driven by the built-in electric field, the resulting electron-hole pairs move directionally, generating current. The specific structure and materials of the composite layer generate a driving force that replaces the potential difference generated by the electrode materials in traditional cells. This broadens the selection of electrode materials. Furthermore, it fundamentally solves the cell defect problem caused by the interfacial recombination of different materials between the passivation layer, transport layer, and light-absorbing layer designed to form a potential difference, reducing energy loss due to interfacial recombination and the shading of sunlight by conductive materials, thereby effectively improving the photoelectric conversion efficiency of the cell. In contrast, the back-contact solar cell stacked with a specific perovskite solar cell has both positive and negative electrodes located on the back of the cell, while the entire front surface is used to receive solar radiation energy transmitted through the perovskite layer, further improving the absorption rate of solar radiation energy. This allows the designed stacked solar cell with a specific structure to achieve optimal solar absorption efficiency and photoelectric conversion efficiency.

[0012] Preferably, the polar perovskite in the polar perovskite region has a two-dimensional layered structure.

[0013] The polar perovskite region provided by this invention employs a two-dimensional layered structure. Within this structure, an inorganic framework composed of metal halide octahedra alternates with organic layers composed of organic cations, exhibiting the desirable properties of both inorganic and organic layers. This promotes the directional movement of electron-hole pairs within the perovskite composite layer, facilitating the construction of a built-in electric field. Furthermore, the two-dimensional layered perovskite is a layered semiconductor material with superior photoelectric properties and chemical stability. Compared to three-dimensional perovskites, the two-dimensional layered perovskite has a smaller grain size and a higher surface area, thus exhibiting excellent energy conversion efficiency and photocatalytic performance. Moreover, the polar two-dimensional perovskite itself generates polarity, producing a potential difference even when illuminated with the same electrodes at both ends, thereby driving the directional movement of electron-hole pairs.

[0014] Preferably, the perovskite composite layer further includes an insulating material region.

[0015] Preferably, in the perovskite composite layer, perpendicular to the stacking direction of the tandem solar cell, the perovskite electrodes and the insulating material region separate the polar perovskite regions in a grid-like structure.

[0016] The perovskite composite layer of the present invention distributes the polar perovskite separator layer in a grid pattern through the perovskite electrodes and insulating material regions, which can control the size and crystallinity of individual polar perovskite regions. At the same time, the grid-distributed polar perovskite regions and the perovskite electrodes on both sides can work independently, increasing the passivation effect of the perovskite composite layer and reducing energy loss.

[0017] Preferably, the polar perovskite regions are spaced apart along both the first and second directions, and any two of the first, second, and stacking directions are perpendicular to each other.

[0018] Preferably, the ratio of the size of a single polar perovskite region along the first direction to the size of a single polar perovskite region along the second direction is (1-5):1, for example, 1:1, 2:1, 3:1, 4:1 or 5:1.

[0019] Preferably, the perovskite electrode includes a first perovskite electrode and a second perovskite electrode, wherein the first perovskite electrode is continuously disposed along the second direction, and the second perovskite electrode is discontinuously disposed along the second direction.

[0020] This invention sets up two types of perovskite electrodes, one continuous and one spaced, between polar perovskite regions, combining polar perovskites in partial series and parallel connections. During operation, this increases voltage and reduces current, avoiding the battery temperature rise caused by high current, reducing the heat generated by the battery module, and thus improving the photovoltaic performance of the battery.

[0021] Preferably, the first perovskite electrode is disposed in the two edge regions and the middle region of the perovskite composite layer in the first direction.

[0022] In this invention, the "intermediate region" refers to the area of ​​the perovskite composite layer along the first direction, excluding the two side edge regions.

[0023] Preferably, the first perovskite electrode in the middle region of the perovskite composite layer in the first direction is arranged in pairs.

[0024] In this invention, "paired arrangement" means that the first perovskite electrodes disposed in the middle region of the perovskite composite layer in the first direction are arranged in pairs.

[0025] Preferably, the perovskite composite layer has at least one pair of first perovskite electrodes arranged in a continuous manner in the middle region of the first direction.

[0026] Preferably, the second perovskite electrode is disposed between the first perovskite electrodes along the first direction.

[0027] Preferably, in the first direction, at least one row of second perovskite electrodes is disposed between the first perovskite electrodes disposed on one side edge region and the middle region of the perovskite composite layer, such as one row, two rows, three rows, four rows, five rows or six rows.

[0028] Preferably, in the first direction, at least two rows of polar perovskite regions are provided between the first perovskite electrode located on one side edge region and the middle region of the perovskite composite layer, such as two, three, four, five, or six rows.

[0029] Preferably, in the first direction, the ratio of the size of a single polar perovskite region to the size of the first perovskite electrode is (31-50):1, for example, 31:1, 32:1, 34:1, 36:1, 38:1, 40:1, 42:1, 44:1, 46:1, 48:1 or 50:1, etc.

[0030] Preferably, in the first direction, the ratio of the size of a single polar perovskite region to the size of the second perovskite electrode is (31-50):1, for example, 31:1, 32:1, 34:1, 36:1, 38:1, 40:1, 42:1, 44:1, 46:1, 48:1 or 50:1, etc.

[0031] Preferably, in the second direction, the size of a single polar perovskite region is equal to the size of the second perovskite electrode.

[0032] Preferably, the insulating material region includes a first insulating material region and a second insulating material region.

[0033] Preferably, in the first direction, the first insulating material region is sandwiched between the paired first perovskite electrodes in the middle region of the perovskite composite layer, and the first insulating material region is attached to the paired first perovskite electrodes on both sides in the first direction.

[0034] Preferably, the first insulating material area is continuously disposed along the second direction.

[0035] Preferably, in the first direction, the ratio of the size of a single first perovskite electrode to the size of a single first insulating material region is 1:(1-10), for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, etc.

[0036] Preferably, in the second direction, the size of a single first perovskite electrode is equal to the size of a single first insulating material region.

[0037] Preferably, along the second direction, the second insulating material region is disposed between the spaced-apart second perovskite electrodes and between the spaced-apart polar perovskite regions.

[0038] Preferably, along the second direction, the second insulating material region is also disposed at the edges of the polar perovskite regions at both ends of the perovskite composite layer and at the edges of the second perovskite electrodes at both ends.

[0039] The present invention also provides insulating material regions on one side of the edge of the polar perovskite region and the edge of the second perovskite electrode at both ends of the perovskite composite layer along the second direction.

[0040] Preferably, the second insulating material region and the perovskite electrode divide the polar perovskite region into a grid pattern.

[0041] Preferably, in the second direction, the ratio of the size of a single polar perovskite region to the size of a single second insulating material region is (10-45):1, for example, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1 or 45:1, etc.

[0042] Preferably, in the second direction, the size of the first perovskite electrode is greater than the sum of the total size of the polar perovskite region and the total size of the second insulating material region located between the polar perovskite regions.

[0043] The present invention is arranged in a second direction, wherein the size of the first perovskite electrode is larger than the sum of the total size of the polar perovskite region and the total size of the second insulating material region located between the polar perovskite regions. The purpose is to enable the external busbar to be connected through the extra-large perovskite electrode, thereby allowing the current generated by multiple perovskite sub-cells to be transmitted and collected.

[0044] Preferably, the materials of the first insulating material region and the second insulating material region are independently selected from any one of EVA (ethylene-vinyl acetate copolymer), POE (polyolefin elastomer), or EVA+POE+EVA co-extruded polymer (EPE).

[0045] Preferably, the polar perovskite in the polar perovskite region has the general chemical formula A2M. n-1 Q n X 3n+1 Where A is an organic amine, M is a small-volume cation with porous structure, and Q is Pb. 2+ X is a halide anion, and n takes the values ​​1-4, such as 1, 2, 3 or 4.

[0046] Preferably, the organic amine includes any one or a combination of at least two of ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, n-pentylamine, isopentylamine, p-bromobenzylamine, n-hexylamine, or 4-aminomethylpiperidine.

[0047] Preferably, the small-volume cation with porous structure includes any one or a combination of at least two of the following: methylhydrazine cation, methylamine cation, formamidinium cation, or cesium cation.

[0048] Preferably, the material of the perovskite electrode includes any one or a combination of at least two of copper, silver, gold, or aluminum.

[0049] Preferably, the thickness of the perovskite composite layer in the stacking direction is 100-700 nm, such as 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm or 700 nm.

[0050] Preferably, in the stacking direction, the thicknesses of the polar perovskite region, the perovskite electrode, the first insulating material region, and the second insulating material region are all equal.

[0051] Preferably, in the perovskite solar cell, a first adhesive film layer is further provided between the first passivation layer and the front glass layer.

[0052] Preferably, the thickness of the front glass layer in the stacking direction is 1.6-3.0 mm, for example, 1.6 mm, 2.0 mm, 2.5 mm or 3.0 mm.

[0053] In this invention, the front glass layer can be selected from conventional high-transmittance photovoltaic glass.

[0054] Preferably, the materials of the first passivation layer and the second passivation layer are independently selected from any one or a combination of at least two of ZnO, MgF2, Al2O3 or terpyridine organic macromolecules.

[0055] Preferably, the thicknesses of the first passivation layer and the second passivation layer in the stacking direction are independently selected from 1-10 nm, such as 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm.

[0056] Preferably, the material of the first adhesive film layer includes any one of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), or EVA+POE+EVA co-extruded polymer (EPE).

[0057] Preferably, the thickness of the first adhesive film layer in the lamination direction is 0.3-0.65 mm, such as 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm or 0.65 mm.

[0058] Preferably, in the back contact battery, the back electrode layer includes positive and negative electrodes that are alternately spaced along the first direction.

[0059] Preferably, in the first direction, the distance between the positive electrode and the negative electrode is 5-30 mm, such as 5 mm, 10 mm, 15 mm, 20 mm, 25 mm or 30 mm.

[0060] Preferably, the positive electrode and the negative electrode are arranged continuously in the second direction.

[0061] Preferably, the thickness of the back electrode layer in the stacking direction is 0.1-0.5 mm, such as 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm.

[0062] Preferably, in the back electrode layer, the positive electrode is made of silver.

[0063] Preferably, in the back electrode layer, the negative electrode is made of copper.

[0064] Preferably, in the back contact battery, a second adhesive film layer is further provided between the back glass layer and the back electrode layer.

[0065] Preferably, the material of the second adhesive film layer includes any one of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), or EVA+POE+EVA co-extruded polymer (EPE).

[0066] Preferably, the thickness of the second adhesive film layer in the lamination direction is 0.3-0.65 mm, such as 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm or 0.65 mm.

[0067] Preferably, the positive and negative electrodes, which are alternately spaced along the first direction, are disposed inside the second adhesive film layer and are attached to the surface of the crystalline silicon layer away from the perovskite cell.

[0068] Preferably, the material of the crystalline silicon layer includes any one or a combination of at least two of N-type silicon, P-type silicon, or polycrystalline silicon.

[0069] Preferably, the thickness of the crystalline silicon layer in the stacking direction is 110-180 μm, such as 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm or 180 μm.

[0070] Preferably, the thickness of the rear glass layer in the stacking direction is 1.4-2.5 mm, such as 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm or 2.5 mm.

[0071] In this invention, the rear glass layer can be selected from conventional photovoltaic high-transmittance glass, which is made of soda-lime glass.

[0072] In a second aspect, the present invention provides a method for fabricating a tandem solar cell according to the first aspect, the method comprising the following steps:

[0073] (1) A crystalline silicon layer containing a back electrode layer is disposed on the surface of the rear glass layer; the back electrode layer is disposed facing the rear glass layer;

[0074] (2) A second passivation layer, a perovskite composite layer, a first passivation layer and a front glass layer are sequentially stacked from bottom to top on the surface of the crystalline silicon layer away from the back electrode layer. After hot pressing, the stacked solar cell consisting of the bottom back contact cell and the top perovskite cell is formed.

[0075] The perovskite composite layer includes at least two polar perovskite regions and perovskite electrodes disposed on both sides of each polar perovskite region in a first direction.

[0076] The method for fabricating tandem solar cells provided by this invention involves directly and sequentially setting the perovskite cell layer structure on the crystalline silicon layer of the assembled back contact cell. This effectively shortens the production process of tandem solar cells, and the fabrication method is simple and inexpensive. The designed perovskite composite layer with a specific structure can form a built-in electric field, driving the directional movement of electron-hole pairs, fundamentally solving the problem of external electric field construction and reducing energy loss caused by interfacial recombination of battery materials, as well as reducing shading of sunlight. The back electrode layer of the back contact cell is located on the back side of the cell, and the entire front surface of the cell receives solar radiation transmitted through the perovskite layer, thereby effectively improving the photovoltaic performance of the tandem solar cell.

[0077] Preferably, the specific preparation process of the perovskite composite layer includes:

[0078] Using the surface of the second passivation layer away from the crystalline silicon layer as the first surface, a perovskite electrode material is disposed at the corresponding position on the first surface of the second passivation layer. After drying, the perovskite electrode is obtained. Insulating material is then disposed at the corresponding position on the first surface of the second passivation layer to form an insulating material region. The perovskite electrode and the insulating material region divide the blank area of ​​the first surface of the second passivation layer into a grid. Then, a polar perovskite precursor solution is spin-coated in the blank area of ​​the grid, and after annealing, a polar perovskite region is formed, thus preparing the perovskite composite layer.

[0079] The perovskite composite layer preparation process provided by this invention involves precisely depositing perovskite electrode material and insulating material on the surface of a second passivation layer. On the surface of the second passivation layer, the blank areas without electrode and insulating material regions are divided into a grid pattern using the obtained insulating material regions and perovskite electrodes. A polar perovskite precursor solution is then spin-coated into the grid-like blank areas to obtain polar perovskite regions, thereby preparing a perovskite composite layer with a special structure and specific arrangement. This preparation method is simple, easy to operate, and can prepare perovskite composite layers of any size and structure, while ensuring excellent quality of the prepared perovskite composite layer.

[0080] Preferably, the perovskite electrode includes a first perovskite electrode and a second perovskite electrode, wherein the first perovskite electrode is continuously disposed along the second direction, and the second perovskite electrode is discontinuously disposed along the second direction.

[0081] Preferably, the first perovskite electrode is disposed in the two edge regions and the middle region of the perovskite composite layer in the first direction.

[0082] Preferably, the first perovskite electrode in the middle region of the perovskite composite layer in the first direction is arranged in pairs.

[0083] Preferably, the perovskite composite layer has at least one pair of first perovskite electrodes arranged in a continuous manner in the middle region of the first direction.

[0084] Preferably, the second perovskite electrode is disposed between the first perovskite electrodes along the first direction.

[0085] Preferably, in the second direction, the size of a single polar perovskite region is equal to the size of the second perovskite cell.

[0086] Preferably, the insulating material region includes a first insulating material region and a second insulating material region.

[0087] Preferably, in the first direction, the first insulating material region is sandwiched between the paired first perovskite electrodes in the middle region of the perovskite composite layer, and the first insulating material region is attached to the paired first perovskite electrodes on both sides in the first direction.

[0088] Preferably, the first insulating material area is continuously disposed along the second direction.

[0089] Preferably, in the second direction, the size of a single first perovskite electrode is equal to the size of a single first insulating material region.

[0090] Preferably, along the second direction, the second insulating material region is disposed between the spaced-apart second perovskite electrodes and between the spaced-apart polar perovskite regions.

[0091] Preferably, along the second direction, the second insulating material region is also disposed at the edges of the polar perovskite regions at both ends of the perovskite composite layer and at the edges of the second perovskite electrodes at both ends.

[0092] Preferably, the second insulating material region and the perovskite electrode divide the polar perovskite region into a grid pattern.

[0093] Preferably, the perovskite electrode material is disposed in either spray coating or screen printing.

[0094] Preferably, the insulating material is disposed in either screen coating or screen printing.

[0095] Preferably, in the process of obtaining the perovskite electrode, the drying temperature is 250-400℃, such as 250℃, 275℃, 300℃, 325℃, 350℃, 375℃ or 400℃.

[0096] Preferably, during the formation of the polar perovskite region, the spin coating speed is 500-3000 rpm, such as 500 rpm, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, or 3000 rpm.

[0097] Preferably, the perovskite electrode material comprises any one or a combination of at least two of copper, silver, gold, or aluminum.

[0098] Preferably, the insulating material comprises any one of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), or EVA+POE+EVA co-extruded polymer (EPE).

[0099] Preferably, the polar perovskite precursor solution comprises a polar perovskite precursor material and a protic solvent.

[0100] Preferably, the concentration of the polar perovskite precursor material in the polar perovskite precursor solution is 7.5-22.5 mg / mL, such as 7.5 mg / mL, 10 mg / mL, 12.5 mg / mL, 15 mg / mL, 17.5 mg / mL, 20 mg / mL or 22.5 mg / mL.

[0101] Preferably, the polar perovskite precursor material includes an organic amine, a first precursor material, and a second precursor material.

[0102] Preferably, the molar ratio of the organic amine, the first precursor material, and the second precursor material is (2-3):(1-4):(2-5), wherein the organic amine is selected from the range of "2-3", such as 2, 2.2, 2.4, 2.6, 2.8, or 3, etc.; the first precursor material is selected from the range of "1-4", such as 1, 1.5, 2, 2.5, 3, 3.5, or 4, etc.; and the second precursor material is selected from the range of "2-5", such as 2, 2.5, 3, 3.5, 4, 4.5, or 5, etc.

[0103] This invention regulates the molar ratio of organic amine, the first precursor material, and the second precursor material. If the amount of organic amine added is too high, the chemical formula (A2M) in the formed polar perovskite material will be affected. n-1 Q n X 3n+1 The value of n can only be in the form of n=1. Theoretically, the larger n is, the more inorganic layers there are in the two-dimensional material, and the higher the conductivity. However, the smaller n is, the more it will affect the performance of the polar perovskite material, thus affecting the overall performance of the tandem solar cell. If the amount of organic amine added is too low, it will lead to the synthesis error of the target material, and the two-dimensional layered perovskite structure cannot be prepared. This will cause the perovskite to change from a two-dimensional material to a three-dimensional material. The isotropic properties of the three-dimensional perovskite will lose their polarity, and the built-in electric field will disappear.

[0104] Preferably, the polar perovskite precursor material further includes hydrogen halides.

[0105] Preferably, the concentration of the hydrohalic acid is 30-50 wt%, such as 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%.

[0106] Preferably, the mass ratio of the second precursor material to the hydrohalic acid is 1:(3-7), such as 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5 or 1:7.

[0107] Preferably, the organic amine includes any one or a combination of at least two of ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, n-pentylamine, isopentylamine, p-bromobenzylamine, n-hexylamine, or 4-aminomethylpiperidine.

[0108] Preferably, the first precursor material includes any one or a combination of at least two of methylhydrazine halide, methylamine halide, formamidine halide, or cesium carbonate.

[0109] Preferably, the second precursor material comprises lead halide.

[0110] Preferably, the aprotic solvent includes any one or a combination of at least two of dimethyl sulfoxide, N,N-dimethylformamide, acetone, or N-methyl-2-pyrrolidone.

[0111] Preferably, the annealing temperature is 75-90℃, such as 75℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃ or 90℃.

[0112] Preferably, the annealing time is 10-35 minutes, such as 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, or 35 minutes.

[0113] Preferably, the first passivation layer and the second passivation layer are disposed in an independently comprising any one of coating printing, spraying or vapor deposition.

[0114] Preferably, after the first passivation layer is formed on the surface of the perovskite composite layer away from the second passivation layer, a first adhesive film is also laid on the surface of the first passivation layer away from the perovskite composite layer to form a first adhesive film layer.

[0115] Preferably, in the back contact battery, the back electrode layer includes positive and negative electrodes that are alternately spaced along the first direction.

[0116] Preferably, the fabrication process of the back electrode layer on the crystalline silicon electrode layer includes either coating printing or electroplating.

[0117] Preferably, before the crystalline silicon layer containing the back electrode layer is disposed on the rear glass layer, a second adhesive film is also deposited on the surface of the rear glass layer to form a second adhesive film layer.

[0118] In this invention, after the second adhesive film is laid on the back glass layer, a crystalline silicon layer containing a back electrode layer is placed on the second adhesive film. The back electrode layer and the second adhesive film layer come into contact. During the subsequent hot pressing process, the second adhesive film layer is formed, and at the same time, the back electrode layer is embedded into the interior of the second adhesive film layer.

[0119] Preferably, the temperature of the hot pressing is 80-200℃, such as 80℃, 100℃, 120℃, 140℃, 160℃, 180℃ or 200℃.

[0120] Preferably, the pressure of the hot pressing is 10-40 MPa, such as 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa or 40 MPa.

[0121] Preferably, the hot pressing time is 5-30 minutes, such as 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes.

[0122] Thirdly, the present invention provides a photovoltaic module, the photovoltaic module comprising the tandem solar cells described in the first aspect.

[0123] The photovoltaic module provided by this invention incorporates a tandem solar cell composed of a perovskite cell and a back-contact cell with a specific composition and structure, exhibiting excellent photoelectric conversion efficiency and operational performance.

[0124] Compared with the prior art, the present invention has at least the following beneficial effects:

[0125] (1) In the tandem solar cell provided by this invention, the perovskite composite layer of the perovskite cell adopts a specific structure with polar perovskite regions and perovskite electrodes. Under the action of light, the polar perovskite absorbs photon energy, causing the perovskite itself to become polar, forming a built-in electric field inside, inducing the directional movement of electrons and leaving holes. The directional movement of electron-hole pairs generates current, replacing the potential difference generated by the electrode materials in traditional cells. This can broaden the selection of electrode materials, reduce the energy loss caused by the interface recombination of different materials and the shading of sunlight by conductive materials, thereby effectively improving the photoelectric conversion efficiency of the cell. As for the back contact cell stacked with the perovskite cell of the specific structure, both the positive and negative electrodes are located on the back of the cell, and the entire front area is used to receive solar radiation energy transmitted through the perovskite layer, which improves the absorption rate of solar radiation energy, thereby effectively improving the photoelectric performance of the tandem solar cell.

[0126] (2) The method for preparing tandem solar cells provided by the present invention directly sets the perovskite cell layer structure on the crystalline silicon layer of the assembled back contact cell, which effectively shortens the production process of tandem solar cells. The preparation method is simple and the preparation cost is low. The perovskite composite layer with the specific structure designed can form a built-in electric field to drive the directional movement of electron-hole pairs, fundamentally solving the problem of external electric field construction and reducing the energy loss caused by interfacial recombination of battery materials, as well as reducing the shading of sunlight. The back electrode layer of the back contact cell is set on the back of the cell, and the entire front area of ​​the cell receives solar radiation transmitted through the perovskite layer, thereby effectively improving the photovoltaic performance of the tandem solar cells. Attached Figure Description

[0127] Figure 1 This is a schematic cross-sectional view of the main view of the tandem solar cell structure provided in Example 1.

[0128] Figure 2 This is a top view schematic diagram of the perovskite composite layer structure in the tandem solar cell provided in Example 1.

[0129] Figure 3 This is a schematic cross-sectional view of the main view of the stacked solar cell structure provided in Example 2.

[0130] Figure 4 This is a top view schematic diagram of the perovskite composite layer structure in the tandem solar cell provided in Example 2.

[0131] Wherein, 1 is a perovskite solar cell; 101 is a front glass layer; 102 is a first adhesive film layer; 103 is a first passivation layer; 104 is a polar perovskite region; 105 is a perovskite electrode; 105-1 is a first perovskite electrode; 105-2 is a second perovskite electrode; 106 is an insulating material region; 106-1 is a first insulating material region; 106-2 is a second insulating material region; 107 is a second passivation layer; 2 is a back contact solar cell; 201 is a back glass layer; 202 is a second adhesive film layer; 203 is a back electrode layer; 203-1 is a positive electrode; 203-2 is a negative electrode; 204 is a crystalline silicon layer; X is a first direction; Y is a second direction; Z is a stacking direction.

[0132] Figure 5 These are the current-voltage (IV) curves of the perovskite materials provided in Examples 1 and 8. Detailed Implementation

[0133] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0134] The following embodiments involve photovoltaic high-transmittance glass with a transmittance of 94% for both the front and rear glass layers, and both are made of soda-lime glass.

[0135] Example 1

[0136] This embodiment provides a tandem solar cell, the main view of which is shown below. Figure 1 As shown (it should be noted that, Figure 1 The given structural diagram is only to clearly show the structure of the perovskite crystalline silicon tandem solar cell and does not limit the size or proportion of the structure. The tandem solar cell includes a top layer of perovskite cell 1 and a bottom layer of back contact cell 2 stacked from top to bottom.

[0137] The perovskite solar cell 1 includes a front glass layer 101, a first encapsulant layer 102, a first passivation layer 103, a perovskite composite layer, and a second passivation layer 107, which are stacked sequentially from top to bottom along the stacking direction Z. The specific structure is as follows:

[0138] The front glass layer 101 is a high-transmittance photovoltaic glass with a transmittance of 94% and a thickness of 2.0 mm; the first encapsulant layer 102 is made of EVA+POE+EVA co-extruded polymer (EPE) and has a thickness of 0.65 mm; the first passivation layer 103 is made of ZnO and has a thickness of 10 nm; the second passivation layer 107 is made of ZnO and has a thickness of 10 nm.

[0139] The perovskite composite layer comprises a polar perovskite region 104, a perovskite electrode 105, and an insulating material region 106, with a thickness of 700 nm. A top-view schematic diagram of its structure is shown below. Figure 2 As shown.

[0140] In this configuration, polar perovskite regions 104 are spaced apart along the first direction X and the second direction Y. Perovskite electrodes 105 are located on both sides of the polar perovskite regions 104 along the first direction X. The first direction X and the second direction Y are perpendicular to any two of the stacking directions Z of the tandem solar cells. The polar perovskite in the polar perovskite regions 104 has a two-dimensional layered structure and its chemical formula is (CH3CH2CH2CH2NH2)2(FA). 0.5 (MA) 0.5 In the perovskite composite layer, perpendicular to the stacking direction Z of the tandem solar cell, the perovskite electrode 105 and the insulating material region 106 divide the polar perovskite region 104 into a grid, and the ratio of the size of a single polar perovskite region 104 in the first direction X to the size in the second direction Y is 4:1.

[0141] The polar perovskite region 104 is separated by perovskite electrodes 105 in the first direction X. The perovskite electrodes 105 are disposed on both sides of the polar perovskite region 104 in the first direction X. Each perovskite electrode 105 includes a first perovskite electrode 105-1 continuously disposed along the second direction Y and a second perovskite electrode 105-2 discontinuously disposed along the second direction Y. A continuously disposed first perovskite electrode 105-1 is disposed on each of the two edge regions of the perovskite composite layer in the first direction X. A pair of continuously disposed first perovskite electrodes 105-1 are disposed in the middle region of the perovskite composite layer in the first direction X. The second perovskite electrodes 105-2 are disposed on the two edge regions and the middle region of the perovskite composite layer in the first direction X, where the first perovskite electrodes 105-1 are continuously disposed. Between -1, a row of intermittently arranged second perovskite electrodes 105-2 is provided between the first perovskite electrodes 105-1 located in the edge region and middle region of the perovskite composite layer in the first direction X; two rows of polar perovskite regions 104 are provided between the first perovskite electrodes 105-1 located in the edge region and middle region of the perovskite composite layer in the first direction; in the first direction X, the ratio of the size of a single polar perovskite region 104 to the size of a single first perovskite electrode 105-1 is 35:1, and the ratio of the size of a single polar perovskite region 104 to the size of a single second perovskite electrode 105-2 is 35:1; in the second direction Y, the size of a single polar perovskite region 104 is equal to the size of a single second perovskite electrode 105-2.

[0142] The insulating material region 106 includes a first insulating material region 106-1 and a second insulating material region 106-2. The first insulating material region 106-1 is continuously arranged along the second direction Y. In the first direction X, the first insulating material region 106-1 is sandwiched between paired first perovskite electrodes 105-1 in the middle region of the perovskite composite layer. The first insulating material region 106-1 is attached to the paired first perovskite electrodes 105-1 on both sides in the first direction X. In the first direction X, the ratio of the size of a single first perovskite electrode 105-1 to the size of a single first insulating material region 106-1 is 1:5. In the second direction Y, the size of a single first perovskite electrode 105-1 is equal to the size of a single first insulating material region 106-1. Along the second direction Y, the second insulating material region 106-2 is arranged between intermittently arranged second perovskite electrodes 105-2 and between spaced-out polar perovskite regions 104, and also includes areas in the perovskite composite layer. At the edges of the polar perovskite regions 104 at both ends of the titanium dioxide composite layer and at the edges of the second perovskite electrodes 105-2 at both ends, the second insulating material region 106-2 and the perovskite electrode 105 divide the polar perovskite regions 104 into a grid. In the second direction Y, the ratio of the size of a single polar perovskite region 104 to the size of a single second insulating material region 106-2 is 20:1. In the second direction Y, the size of the first perovskite electrode 105-1 is greater than the sum of the total size of the polar perovskite regions 104 and the total size of the second insulating material regions 106-2 located between the polar perovskite regions 104. The first perovskite electrode 105-1 and the second perovskite electrode 105-2 are both made of metallic copper, and the first insulating material region 106-1 and the second insulating material region 106-2 are both made of EVA+POE+EVA co-extruded polymer (EPE).

[0143] The back contact battery 2 includes a rear glass layer 201, a second adhesive film layer 202, a back electrode layer 203, and a crystalline silicon layer 204, arranged sequentially from bottom to top along the stacking direction Z. The crystalline silicon layer 204 in the back contact battery 2 is bonded to the second passivation layer 107 in the perovskite battery 1. The crystalline silicon layer 204 is made of N-type crystalline silicon and has a thickness of 180 μm. The second adhesive film layer 202 is made of ethylene-vinyl acetate copolymer (EVA) and has a thickness of 0.65 mm. The back electrode layer 203 includes positive electrodes 200 arranged alternately along the first direction X. The positive electrode 203-1 and the negative electrode 203-2 are alternately spaced 10mm apart in the first direction X. The positive electrode 203-1 is made of silver and the negative electrode 203-2 is made of copper. The thickness of the back electrode layer 203 in the stacking direction Z is 0.25mm. The alternating positive electrode 203-1 and negative electrode 203-2 are disposed inside the second adhesive film layer 202 and are bonded to the surface of the crystalline silicon layer 204 away from the perovskite cell 1. The back glass layer 201 is made of photovoltaic high-transmittance glass with a transmittance of 94% and a thickness of 2.0mm.

[0144] This embodiment also provides a method for fabricating the above-mentioned perovskite-silicon tandem solar cell, including the following steps:

[0145] (I) An EVA film is laid on the upper surface of the rear glass layer 201 to form a second film layer 202. Then, a crystalline silicon layer 204 is laid on the surface of the second film layer 202 away from the rear glass layer 201. A positive electrode 203-1 and a negative electrode 203-2 are alternately arranged along the first direction X and continuously arranged along the second direction Y. The positive electrode 203-1 and the negative electrode 203-2 are set on one side surface of the crystalline silicon layer 204 by electroplating. The back electrode layer 203 formed by the positive electrode 203-1 and the negative electrode 203-2 is in contact with the second film layer 202.

[0146] (II) ZnO is sprayed onto the surface of the crystalline silicon layer 204 stacked in step (I) on the side away from the back electrode layer 203 to obtain the second passivation layer 107.

[0147] (III) Mix n-butylamine with formamidine bromide, methylamine bromide and lead bromide in a molar ratio of 2:0.5:0.5:2, add a 30wt% hydrobromic acid solution, wherein the mass ratio of lead bromide to hydrobromic acid solution is 1:5, heat and stir until a transparent solution is obtained, cool and crystallize, remove the precipitate and dry it, then weigh 12mg of the dried product, add anhydrous DMF, stir until clear, prepare a 0.6mL solution, and obtain a polar perovskite precursor solution with a concentration of 20mg / mL for later use.

[0148] (IV) Taking the surface of the second passivation layer 107 away from the crystalline silicon layer 204 as the first surface, metallic copper is sprayed onto the first surface of the second passivation layer 107 at the corresponding positions of the first perovskite electrode 105-1 and the second perovskite electrode 105-2 using a spraying process. After drying at 300°C, the perovskite electrode 105 is obtained. Then, EPE is coated onto the corresponding positions of the first insulating material region 106-1 and the second insulating material region 106-2 on the first surface of the second passivation layer 107 using a screen printing process to obtain the insulating material… Region 106, the perovskite electrode 105 and the insulating material region 106 separate the blank areas on the first surface of the second passivation layer 107 that are not coated with metallic copper and EPE into a grid. Then, the polar perovskite precursor solution obtained in step (III) is spin-coated in the grid-shaped blank areas at a speed of 1000 rpm for 10 s, and then spin-coated at a speed of 2500 rpm for 15 s. After spin-coating, it is annealed at 90°C for 10 min to obtain the polar perovskite region 104, thereby preparing the perovskite composite layer.

[0149] (V) ZnO is sprayed onto the surface of the perovskite composite layer away from the second passivation layer 107 by spraying to obtain a first passivation layer 103 with a thickness of 10 nm. Then, EPE is laid on the surface of the first passivation layer 103 away from the perovskite composite layer to form a first adhesive film layer 102. Next, a front glass layer 101 is disposed on the surface of the first adhesive film layer 102 away from the first passivation layer 103. The layers are then hot-pressed at 100°C and 10 MPa for 30 min to form a tandem solar cell consisting of a bottom back contact cell 2 and a top perovskite cell 1.

[0150] Example 2

[0151] This embodiment provides a tandem solar cell, the main view of which is shown below. Figure 3 As shown (it should be noted that, Figure 3 The given structural diagram is only to clearly show the structure of the perovskite crystalline silicon tandem solar cell and does not limit the size or proportion of the structure. The tandem solar cell includes a top layer of perovskite cell 1 and a bottom layer of back contact cell 2 stacked from top to bottom.

[0152] The perovskite solar cell 1 includes a front glass layer 101, a first encapsulant layer 102, a first passivation layer 103, a perovskite composite layer, and a second passivation layer 107, which are stacked sequentially from top to bottom along the stacking direction Z. The specific structure is as follows:

[0153] The front glass layer 101 is a high-transmittance photovoltaic glass with a transmittance of 94% and a thickness of 1.6 mm; the first encapsulant layer 102 is made of polyolefin elastomer (POE) and has a thickness of 0.3 mm; the first passivation layer 103 is made of Al2O3 and has a thickness of 1 nm; the second passivation layer 107 is made of Al2O3 and has a thickness of 1 nm.

[0154] The perovskite composite layer comprises a polar perovskite region 104, a perovskite electrode 105, and an insulating material region 106, with a thickness of 100 nm. A top-view schematic diagram of its structure is shown below. Figure 4 As shown.

[0155] In this configuration, polar perovskite regions 104 are spaced apart along the first direction X and the second direction Y. Perovskite electrodes 105 are located on both sides of the polar perovskite regions 104 along the first direction X. The first direction X and the second direction Y are perpendicular to any two of the stacking directions Z of the tandem solar cells. The polar perovskite in the polar perovskite region 104 has a two-dimensional layered structure with the chemical formula (CH3CH2CH2CH2NH2)2(MA)Pb2Br7. In the perovskite composite layer perpendicular to the stacking direction Z of the tandem solar cells, the perovskite electrodes 105 and the insulating material region 106 divide the polar perovskite regions 104 into a grid. The ratio of the size of a single polar perovskite region 104 in the first direction X to the size in the second direction Y is 2:1.

[0156] The polar perovskite region 104 is separated by perovskite electrodes 105 in the first direction X. The perovskite electrodes 105 are disposed on both sides of the polar perovskite region 104 in the first direction X. Each perovskite electrode 105 includes a first perovskite electrode 105-1 continuously disposed along the second direction Y and a second perovskite electrode 105-2 discontinuously disposed along the second direction Y. A continuously disposed first perovskite electrode 105-1 is disposed on each of the two edge regions of the perovskite composite layer in the first direction X. A pair of continuously disposed first perovskite electrodes 105-1 are disposed in the middle region of the perovskite composite layer in the first direction X. The second perovskite electrodes 105-2 are disposed on the two edge regions and the middle region of the perovskite composite layer in the first direction X, where the first perovskite electrodes 105-1 are continuously disposed. Between 05-1, in the first direction X, two rows of second perovskite electrodes 105-2 are disposed between the first perovskite 105-1 disposed in the edge region and the middle region of the perovskite composite layer; in the first direction X, three rows of polar perovskite regions 104 are disposed between the first perovskite 105-1 disposed in the edge region and the middle region of the perovskite composite layer; in the first direction X, the ratio of the size of a single polar perovskite region 104 to the size of a single first perovskite electrode 105-1 is 50:1, and the ratio of the size of a single polar perovskite region 104 to the size of a single second perovskite electrode 105-2 is 50:1; in the second direction Y, the size of a single polar perovskite region 104 is equal to the size of a single second perovskite electrode 105-2.

[0157] The insulating material region 106 includes a first insulating material region 106-1 and a second insulating material region 106-2. The first insulating material region 106-1 is continuously arranged along the second direction Y. In the first direction X, the first insulating material region 106-1 is sandwiched between paired first perovskite electrodes 105-1 in the middle region of the perovskite composite layer. The first insulating material region 106-1 is attached to the paired first perovskite electrodes 105-1 on both sides in the first direction X. In the first direction X, the ratio of the size of a single first perovskite electrode 105-1 to the size of a single first insulating material region 106-1 is 1:5. In the second direction Y, the size of a single first perovskite electrode 105-1 is equal to the size of a single first insulating material region 106-1. Along the second direction Y, the second insulating material region 106-2 is arranged between the intermittently arranged second perovskite electrodes 105-2 and the spaced-out polar perovskite regions 104. Between the polar perovskite regions 104 and the edges of the second perovskite electrodes 105-2 at both ends of the perovskite composite layer, the second insulating material region 106-2 and the perovskite electrodes 105 divide the polar perovskite regions 104 into a grid. In the second direction Y, the ratio of the size of a single polar perovskite region 104 to the size of a single second insulating material region 106-2 is 10:1. In the second direction Y, the size of the first perovskite electrode 105-1 is greater than the sum of the total size of the polar perovskite regions 104 and the total size of the second insulating material regions 106-2 located between the polar perovskite regions 104. The first perovskite electrode 105-1 and the second perovskite electrode 105-2 are both made of metallic silver, and the first insulating material region 106-1 and the second insulating material region 106-2 are both made of POE.

[0158] The back contact battery 2 includes a rear glass layer 201, a second adhesive film layer 202, a back electrode layer 203, and a crystalline silicon layer 204, arranged sequentially from bottom to top along the stacking direction Z. The crystalline silicon layer 204 in the back contact battery 2 is bonded to the second passivation layer 107 in the perovskite battery 1. The crystalline silicon layer 204 is made of N-type crystalline silicon and has a thickness of 110 μm. The second adhesive film layer 202 is made of POE and has a thickness of 0.3 mm. The back electrode layer 203 includes a positive electrode 203-1 and a negative electrode 203-1, which are alternately arranged along the first direction X. The alternating spacing of the electrodes 203-2 in the first direction X is 12mm. The positive electrode 203-1 is made of silver, and the negative electrode 203-2 is made of copper. The thickness of the back electrode layer 203 in the stacking direction Z is 0.25mm. The alternating positive electrode 203-1 and negative electrode 203-2 are disposed inside the second adhesive film layer 202 and are bonded to the surface of the crystalline silicon layer 204 away from the perovskite cell 1. The back glass layer 201 is made of photovoltaic high-transmittance glass with a transmittance of 94% and a thickness of 2.0mm.

[0159] This embodiment also provides a method for fabricating the above-mentioned perovskite-silicon tandem solar cell, including the following steps:

[0160] (I) A POE film is laid on the upper surface of the rear glass layer 201 to form a second film layer 202. Then, a crystalline silicon layer 204 is laid on the surface of the second film layer 202 away from the rear glass layer 201. A positive electrode 203-1 and a negative electrode 203-2 are alternately arranged along the first direction X and continuously arranged along the second direction Y. The positive electrode 203-1 and the negative electrode 203-2 are set on one side surface of the crystalline silicon layer 204 by electroplating. The back electrode layer 203 formed by the positive electrode 203-1 and the negative electrode 203-2 is in contact with the second film layer 202.

[0161] (II) Al2O3 is sprayed onto the surface of the crystalline silicon layer 204 stacked in step (I) on the side away from the back electrode layer 203 to obtain the second passivation layer 107.

[0162] (III) Mix n-butylamine with methylamine bromide and lead bromide in a molar ratio of 2:1:2, add a 50wt% hydrobromic acid solution, wherein the mass-volume ratio of lead bromide to hydrobromic acid solution is 1:7, heat and stir until a transparent solution is obtained, cool and crystallize, remove the precipitate and dry it, then weigh 12mg of the dried product, add anhydrous dimethyl sulfoxide, stir until clear, prepare a 1mL solution, and obtain a polar perovskite precursor solution with a concentration of 12mg / mL for later use.

[0163] (IV) Taking the surface of the second passivation layer 107 away from the crystalline silicon layer 204 as the first surface, metallic silver is printed on the first surface of the second passivation layer 107 at the corresponding positions of the first perovskite electrode 105-1 and the second perovskite electrode 105-2 using a screen printing process. After drying at 400°C, the perovskite electrode 105 is obtained. Then, POE is coated on the corresponding positions of the first insulating material region 106-1 and the second insulating material region 106-2 on the first surface of the second passivation layer 107 using a screen printing process to obtain the insulating material… The perovskite electrode 105 and the insulating material region 106 separate the blank areas on the first surface of the second passivation layer 107 that are not coated with metallic silver and POE into a grid. Then, the polar perovskite precursor solution obtained in step (III) is spin-coated in the grid-shaped blank areas at a speed of 1500 rpm for 10 s, and then spin-coated at a speed of 3000 rpm for 10 s. After spin-coating, it is annealed at 75°C for 35 min to obtain the polar perovskite region 104, thereby preparing the perovskite composite layer.

[0164] (V) Al2O3 material is deposited on the surface of the perovskite composite layer away from the second passivation layer 107 by vapor deposition to obtain the first passivation layer 103. Then, POE is laid on the surface of the first passivation layer 103 away from the perovskite composite layer to form the first adhesive film layer 102. Next, the front glass layer 101 is set on the surface of the first adhesive film layer 102 away from the first passivation layer 103. The layers are hot-pressed at 200°C and 40MPa for 5 minutes to form a tandem solar cell consisting of the bottom back contact cell 2 and the top perovskite cell 1.

[0165] Example 3

[0166] The only difference between this embodiment and Example 1 is that the chemical formula of the polar perovskite in polar perovskite region 104 is replaced with (CH3CH2CH2CH2CH2NH2)2(FA)Pb2Br7; correspondingly, the ethylamine in the perovskite precursor solution of the provided preparation method is replaced with n-pentylamine. All other contents are the same as in Example 1.

[0167] Example 4

[0168] The only difference between this embodiment and Example 1 is that the anhydrous DMF in the perovskite precursor solution is replaced with a mixed solvent with a volume ratio of DMF:DMSO = 5:1. All other aspects are the same as in Example 1.

[0169] Example 5

[0170] The only difference between this embodiment and Embodiment 1 is that the second insulating material region 106-2 between the polar perovskite region 104 and the second perovskite electrode 105-1 in the perovskite composite layer is omitted. All other contents are the same as in Embodiment 1.

[0171] Example 6

[0172] The only difference between this embodiment and Embodiment 1 is that, in the second direction Y, the ratio of the size of a single polar perovskite region 104 to the size of a single second insulating material region 106-2 is 55:1. All other aspects are the same as in Embodiment 1.

[0173] Example 7

[0174] The only difference between this embodiment and Embodiment 1 is that, in the first direction X, the ratio of the size of a single polar perovskite region 104 to the size of the first perovskite electrode 105-1 is 60:1, and the ratio of the size of a single polar perovskite region 104 to the size of the second perovskite electrode 105-2 is 60:1. All other contents are the same as in Embodiment 1.

[0175] Example 8

[0176] The only difference between this embodiment and Example 1 is that, in the first direction X, the chemical formula of the polar perovskite region 104 is FAPbBr3; correspondingly, in step (III) of the method for preparing the tandem solar cell, formamidinium bromide and lead bromide are mixed in a molar ratio of 1:2. All other aspects are the same as in Example 1.

[0177] Comparative Example 1

[0178] The only difference between this comparative example and Example 1 is that the battery in this comparative example omits the back contact battery 2 and uses only the perovskite battery 1 as the solar cell. All other aspects are the same as in Example 1.

[0179] Comparative Example 2

[0180] The only difference between this comparative example and Example 1 is that the perovskite cell 1 is omitted in this comparative example, and only the back contact cell 2 is used as the solar cell. All other contents are the same as in Example 1.

[0181] Comparative Example 3

[0182] The only difference between this comparative example and Example 1 is that the second perovskite electrode 105-2 is omitted between the continuously arranged first perovskite electrodes 105-1 in the first direction X, and a continuous polar perovskite region 104 is formed. The second insulating material region 106-2 is omitted in the second direction Y, and a continuous polar perovskite region 104 is also formed. All other contents are the same as in Example 1.

[0183] The solar cells provided in Examples 1-10 and Comparative Examples 1-3 were subjected to performance tests. The test conditions were as follows: the solar cells were placed in an environment at 25°C for 5 minutes, the light source was AM1.5, and the power density was 100 mW / cm². 2 The voltage test range was -10V to 10V, with a delay time of 100ms. The open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and photoelectric conversion efficiency (PEC) were recorded. The test results are shown in Table 1.

[0184] Table 1

[0185]

[0186]

[0187] The test results show that:

[0188] (1) As can be seen from Examples 1 to 4, the present invention designs the perovskite composite layer of the top battery, uses a specific structure and polar material to generate driving force, induces the directional movement of electrons, generates current, reduces the energy loss caused by material interface recombination and the shading of sunlight by conductive materials, and combined with the selection of the back contact battery of the bottom battery, the bottom battery is unshaded on the front, receives more solar radiation, and effectively improves the photoelectric performance of the tandem solar cell.

[0189] (2) By comparing Example 1 and Example 5, it can be seen that if the second insulating material region between the polar perovskite regions is omitted in the present invention, the crystallinity will decrease, the internal defects will increase, the polarity will decrease, the voltage will decrease, the carrier transport will be blocked, the current will decrease, and the photoelectric conversion efficiency will decrease.

[0190] (3) By comparing Example 1 and Example 6, it can be seen that if the ratio of the size of a single polar perovskite region in the second direction to the size of a single second insulating material region is too large, the crystal quality of the perovskite region will be greatly reduced, resulting in a reduction in current output and a loss of some photoelectric conversion.

[0191] (4) By comparing Example 1 and Example 7, it can be seen that if the ratio of the size of a single polar perovskite region in the first direction to the size of a single perovskite electrode is too large, it will cause partial quenching of photogenerated carriers, resulting in voltage loss. At the same time, the crystal quality of the perovskite region will be greatly reduced, resulting in reduced current output and loss of some photoelectric conversion.

[0192] (5) By comparing Example 1 and Example 8, it can be seen that if the chemical formula of the polar perovskite region is replaced with FAPbBr3, the potential difference of the perovskite material will disappear, the transmission of photogenerated carriers will be impaired, and voltage and current will be lost, thereby affecting the photoelectric conversion efficiency.

[0193] Figure 5 The current-voltage curves of the perovskite materials provided in Examples 1 and 8 are given. As can be seen from the figure, the polar perovskite provided in Example 1 generates current when the voltage is 0V, indicating that the polar perovskite provided in Example 1 has an inherent potential difference across its terminals. However, the perovskite material provided in Example 8 does not generate current when the voltage is 0V, indicating that the perovskite provided in Example 8 has no inherent potential difference.

[0194] (6) By comparing Example 1 with Comparative Examples 1-2, it can be seen that the present invention combines the titanium dioxide cell with the back contact cell for photoelectric conversion, thereby improving the photoelectric conversion efficiency of the solar cell. However, the performance of the solar cell will decrease when the perovskite cell or the back contact cell is missing.

[0195] (7) By comparing Example 1 and Comparative Example 3, it can be seen that if the second perovskite electrode set in the first direction of the polar perovskite region is omitted and the second insulating material region in the second direction is omitted, and a polar perovskite region with a continuous structure is set, the size of the single light-absorbing layer formed by the perovskite light absorption will increase, the crystallinity will decrease, and energy will be lost, thereby resulting in a deterioration of the performance of the solar cell.

[0196] In summary, the tandem solar cell provided by this invention employs a specific structure in its perovskite composite layer, featuring polar perovskite regions and perovskite electrodes. Under the influence of light, the polar perovskite regions absorb photon energy, causing the perovskite itself to become polar, creating a built-in electric field that induces the directional movement of electrons and leaves holes. The directional movement of electron-hole pairs generates current, replacing the potential difference generated by electrode materials in traditional cells. This broadens the selection of electrode materials, reduces energy loss caused by interfacial recombination of different materials, and minimizes the shading of sunlight by conductive materials, thereby effectively improving the photoelectric conversion efficiency of the cell. Furthermore, in the back-contact cell tandem with this specific perovskite cell structure, the electrode layers are all located on the back side of the cell, with the entire front surface used to receive solar radiation energy transmitted through the perovskite layer. This increases the absorption rate of solar radiation energy, thereby effectively improving the photoelectric performance of the tandem solar cell.

[0197] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A tandem solar cell, characterized in that, The tandem solar cell includes a top layer of perovskite cells and a bottom layer of back contact cells stacked sequentially from top to bottom. The perovskite solar cell comprises, from top to bottom, a front glass layer, a first passivation layer, a perovskite composite layer, and a second passivation layer stacked sequentially; the perovskite composite layer comprises at least two polar perovskite regions and perovskite electrodes disposed on both sides of each polar perovskite region in a first direction; the first direction is perpendicular to the stacking direction of the tandem solar cell. The back contact battery includes a back glass layer, a back electrode layer, and a crystalline silicon layer stacked sequentially from bottom to top; the crystalline silicon layer in the back contact battery is bonded to the second passivation layer in the perovskite battery.

2. The tandem solar cell according to claim 1, characterized in that, The polar perovskite in the polar perovskite region has a two-dimensional layered structure. Preferably, the perovskite composite layer further includes an insulating material region; Preferably, in the perovskite composite layer, in the stacking direction perpendicular to the stacked solar cell, the perovskite electrode and the insulating material region divide the polar perovskite region into a grid pattern; Preferably, the polar perovskite regions are spaced apart along the first direction and the second direction, and any two of the first direction, the second direction and the stacking direction are perpendicular to each other; Preferably, the ratio of the size of a single polar perovskite region along the first direction to the size of a single polar perovskite region along the second direction is (1-5):1; Preferably, the perovskite electrode includes a first perovskite electrode and a second perovskite electrode, wherein the first perovskite electrode is continuously disposed along the second direction, and the second perovskite electrode is discontinuously disposed along the second direction. Preferably, the first perovskite electrode is disposed in the two side edge regions and the middle region of the perovskite composite layer in the first direction; Preferably, the first perovskite electrode in the middle region of the perovskite composite layer in the first direction is arranged in pairs; Preferably, the perovskite composite layer has at least one pair of first perovskite electrodes arranged in a continuous manner in the middle region of the first direction; Preferably, the second perovskite electrode is disposed between the first perovskite electrodes along the first direction; Preferably, in the first direction, at least one row of second perovskite electrodes is disposed between the first perovskite electrodes disposed in one side edge region and the middle region of the perovskite composite layer; Preferably, in the first direction, at least two rows of polar perovskite regions are provided between the first perovskite electrode located in one side edge region and the middle region of the perovskite composite layer; Preferably, in the first direction, the ratio of the size of a single polar perovskite region to the size of the first perovskite electrode is (31-50):1; Preferably, in the first direction, the ratio of the size of a single polar perovskite region to the size of the second perovskite electrode is (31-50):1; Preferably, in the second direction, the size of a single polar perovskite region is equal to the size of the second perovskite electrode.

3. The tandem solar cell according to claim 2, characterized in that, The insulating material region includes a first insulating material region and a second insulating material region; Preferably, in the first direction, the first insulating material region is sandwiched between the paired first perovskite electrodes in the middle region of the perovskite composite layer, and the first insulating material region is attached to the paired first perovskite electrodes on both sides in the first direction. Preferably, the first insulating material area is continuously disposed along the second direction; Preferably, in the first direction, the ratio of the size of a single first perovskite electrode to the size of a single first insulating material region is 1:(1-10); Preferably, along the second direction, the second insulating material region is disposed between the spaced-apart second perovskite electrodes and between the spaced-apart polar perovskite regions; Preferably, the second insulating material region and the perovskite electrode divide the polar perovskite region into a grid pattern; Preferably, in the second direction, the ratio of the size of a single polar perovskite region to the size of a single second insulating material region is (10-45):1; Preferably, in the second direction, the size of the first perovskite electrode is greater than the sum of the total size of the polar perovskite region and the total size of the second insulating material region located between the polar perovskite regions; Preferably, the materials of the first insulating material region and the second insulating material region are independently selected from any one of EVA, POE, or EVA+POE+EVA co-extruded polymer.

4. The tandem solar cell according to any one of claims 1-3, characterized in that, The polar perovskite in the polar perovskite region has the general chemical formula A2M. n-1 Q n X 3n+1 Where A is an organic amine, M is a small-volume cation with porous structure, and Q is Pb. 2+ X is a halide anion, and n takes values ​​from 1 to 4; Preferably, the organic amine includes any one or a combination of at least two of the following: ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, n-pentylamine, isopentylamine, p-bromobenzylamine, n-hexylamine, or 4-aminomethylpiperidine; Preferably, the small-volume cation with porous structure includes any one or a combination of at least two of the following: methylhydrazine cation, methylamine cation, formamidinium cation, or cesium cation.

5. The tandem solar cell according to any one of claims 1-4, characterized in that, In the perovskite solar cell, a first adhesive film layer is further provided between the first passivation layer and the front glass layer; Preferably, in the back contact battery, the back electrode layer includes positive and negative electrodes that are alternately spaced along the first direction; Preferably, in the back contact battery, a second adhesive film layer is further provided between the back glass layer and the back electrode layer; Preferably, the positive and negative electrodes, which are alternately spaced along the first direction, are disposed inside the second adhesive film layer and are attached to the surface of the crystalline silicon layer away from the perovskite cell.

6. A method for preparing a tandem solar cell according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) A crystalline silicon layer containing a back electrode layer is disposed on the surface of the rear glass layer; the back electrode layer is disposed facing the rear glass layer; (2) A second passivation layer, a perovskite composite layer, a first passivation layer and a front glass layer are sequentially stacked from bottom to top on the surface of the crystalline silicon layer away from the back electrode layer. After hot pressing, the stacked solar cell consisting of the bottom back contact cell and the top perovskite cell is formed. The perovskite composite layer includes at least two polar perovskite regions and perovskite electrodes disposed on both sides of each polar perovskite region in a first direction.

7. The preparation method according to claim 6, characterized in that, The specific preparation process of the perovskite composite layer includes: Using the surface of the second passivation layer away from the crystalline silicon layer as the first surface, a perovskite electrode material is disposed at the corresponding position on the first surface of the second passivation layer. After drying, the perovskite electrode is obtained. Insulating material is then disposed at the corresponding position on the first surface of the second passivation layer to form an insulating material region. The perovskite electrode and the insulating material region divide the blank area of ​​the first surface of the second passivation layer into a grid. Then, a polar perovskite precursor solution is spin-coated in the blank area of ​​the grid, and after annealing, a polar perovskite region is formed, thus preparing the perovskite composite layer. Preferably, the polar perovskite precursor solution comprises a polar perovskite precursor material and a protic solvent; Preferably, the polar perovskite precursor material includes an organic amine, a first precursor material, and a second precursor material; Preferably, the molar ratio of the organic amine, the first precursor material, and the second precursor material is (2-3):(1-4):(2-5); Preferably, the polar perovskite precursor material further includes hydrohalic acid; Preferably, the mass ratio of the second precursor material to the hydrohalic acid is 1:(3-7); Preferably, the organic amine includes any one or a combination of at least two of ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, n-pentylamine, isopentylamine, p-bromobenzylamine, n-hexylamine, or 4-aminomethylpiperidine.

8. The preparation method according to claim 6 or 7, characterized in that, The first passivation layer and the second passivation layer can be formed independently by any one of coating printing, spraying or vapor deposition. Preferably, after the first passivation layer is formed on the surface of the perovskite composite layer away from the second passivation layer, a first adhesive film is also laid on the surface of the first passivation layer away from the perovskite composite layer to form a first adhesive film layer.

9. The preparation method according to any one of claims 6-8, characterized in that, In the back contact battery, the back electrode layer includes positive and negative electrodes that are alternately spaced along the first direction; Preferably, the fabrication process of the back electrode layer on the crystalline silicon layer includes either coating printing or electroplating. Preferably, before the crystalline silicon layer containing the back electrode layer is disposed on the back glass layer, a second adhesive film is also deposited on the surface of the back glass layer to form a second adhesive film layer. Preferably, the temperature of the hot pressing is 80-200℃; Preferably, the pressure of the hot pressing is 10-40 MPa; Preferably, the hot pressing time is 5-30 minutes.

10. A photovoltaic module, characterized in that, The photovoltaic module includes the tandem solar cell as described in any one of claims 1-5.

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