Three-terminal laminated solar cell, manufacturing method and photovoltaic module

Abstract

The invention provides a three-terminal laminated solar cell, a manufacturing method and a photovoltaic module. The three-terminal laminated solar cell comprises: a BC bottom cell; the at least one perovskite top cell is arranged on the light receiving surface of the BC bottom cell, and the area ratio of the total area of the at least one perovskite top cell to the area of the light receiving surface of the BC bottom cell is less than or equal to 0.5. Thus, the perovskite top cell with a relatively small area is arranged, the short wave absorption advantage of the perovskite top cell is fully played, the area capable of directly absorbing light in the light receiving surface of the BC bottom cell (namely the area of the region where the perovskite top cell is not arranged in the light receiving surface of the BC bottom cell) is increased, and when light is incident, the reflectivity is reduced, the current of the BC bottom cell is increased, and the light absorption efficiency of the BC bottom cell is improved. Therefore, the photoelectric conversion efficiency of the three-terminal laminated solar cell can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular, to a three-terminal stacked solar cell, a manufacturing method thereof, and a photovoltaic module. Background Art

[0002] A BC cell (Back Contact cell) has no grid lines on the front side, which can maximize the utilization of light energy. However, due to the bandgap limitation of a single BC cell, only part of the light in the short-wave band is utilized. A BC cell can only absorb the energy that matches the bandgap width, and the excess part cannot be utilized but is lost in the form of heat energy, which limits its photoelectric conversion efficiency. The theoretical limit of the BC cell efficiency is about 28.7%. To improve the cell efficiency, stacked cells are usually adopted. For example, a perovskite cell is integrated on a crystalline silicon cell, and the solar cell with a BC cell and a perovskite cell stacked is a three-terminal cell. Compared with a two-terminal cell, the currents of the top cell and the bottom cell of the three-terminal stacked cell can be output separately without current matching, and it has a higher cell efficiency. However, large-sized perovskite cells are difficult to fabricate, or the fabricated quality is poor, which is not conducive to improving the efficiency of the stacked cell. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems in the related art to some extent. For this purpose, an object of the present invention is to provide a three-terminal stacked solar cell, and this stacked solar cell has a relatively high photoelectric conversion efficiency.

[0004] In one aspect of the present invention, the present invention provides a three-terminal stacked solar cell. According to an embodiment of the present invention, the three-terminal stacked solar cell includes: a BC bottom cell; at least one perovskite top cell, at least one of the perovskite top cells is disposed on a light-receiving surface of the BC bottom cell, and the area ratio of the total area of at least one of the perovskite top cells to the area of the light-receiving surface of the BC bottom cell is less than or equal to 0.5. Thus, by setting a perovskite top cell with a relatively small area, while giving full play to the short-wave absorption advantage of the perovskite top cell, the area that can directly absorb light in the light-receiving surface of the BC bottom cell (that is, the area of the region in the light-receiving surface of the BC bottom cell where no perovskite top cell is provided) is increased. When light is incident, the reflectivity is reduced, the current of the BC bottom cell is increased, and thus it helps to improve the photoelectric conversion efficiency of the three-terminal stacked solar cell.

[0005] According to an embodiment of the present invention, the area ratio of the total area of all the perovskite top cells to the area of the light-receiving surface of the BC bottom cell is 0.3 to 0.5.

[0006] According to an embodiment of the present invention, the three-terminal stacked solar cell includes a plurality of the perovskite top cells, and the plurality of the perovskite top cells are arranged at intervals.

[0007] According to an embodiment of the present invention, the BC cell includes a TBC cell, an HBC cell, or a hybrid BC cell.

[0008] According to an embodiment of the present invention, the light-receiving surface of the BC bottom cell includes a matte surface area and at least one polished surface area, and the perovskite top cell is located in the polished surface area.

[0009] According to an embodiment of the present invention, a plurality of the perovskite top cells are symmetrically arranged, and / or the shape of the perovskite top cell includes at least one of a square, a circle, an ellipse, a triangle, a pentagon, and a hexagon.

[0010] According to an embodiment of the present invention, the BC bottom cell includes: a silicon substrate having a light-receiving surface and a backlight surface disposed opposite to each other, the back surface having an N region and a P region disposed at intervals, and the light-receiving surface having a matte surface and a polished surface; a first passivation layer disposed on the matte surface of the silicon substrate; an antireflection film disposed on a side of the first passivation layer away from the silicon substrate; a first N-type doped polysilicon layer disposed on the polished surface of the silicon substrate; in a direction away from the silicon substrate, the N region is sequentially provided with a tunneling layer, a second N-type doped polysilicon layer, a second passivation layer, and a first electrode; in a direction away from the silicon substrate, the P region is sequentially provided with the tunneling layer, a P-type doped polysilicon layer, the second passivation layer, and a second electrode.

[0011] According to an embodiment of the present invention, the BC bottom cell includes: a P-type doped silicon substrate having a light-receiving surface and a backlight surface disposed opposite to each other, the back surface having an N region and a P region, and the light-receiving surface having a matte surface and a polished surface; a first passivation layer disposed on the matte surface of the P-type doped silicon substrate; an antireflection film disposed on a side of the first passivation layer away from the P-type doped silicon substrate; an N-type heavily doped layer disposed on the polished surface; a first N-type doped polysilicon layer disposed on a side of the N-type heavily doped layer away from the P-type doped silicon substrate; in a direction away from the P-type doped silicon substrate, the N region is sequentially provided with a tunneling layer, a second N-type doped polysilicon layer, a second passivation layer, and a first electrode; in a direction away from the P-type doped silicon substrate, the P region is sequentially provided with the second passivation layer and a second electrode, and the P region is matte.

[0012] According to an embodiment of the present invention, a conductive layer is further included between the BC bottom cell and the perovskite top cell.

[0013] In another aspect of the present invention, the present invention provides a method for manufacturing the three-terminal stacked solar cell described above. According to an embodiment of the present invention, the method for manufacturing a three-terminal stacked solar cell includes: manufacturing a BC bottom cell; manufacturing at least one perovskite top cell on the light-receiving surface of the BC bottom cell, and the area ratio of the total area of at least one perovskite top cell to the area of the light-receiving surface of the BC bottom cell is less than or equal to 0.5. In this way, by setting a perovskite top cell with a relatively small area, while fully exerting the short-wave absorption advantage of the perovskite top cell, the area of the light-receiving surface of the BC bottom cell that can directly receive light is increased, so that the overall stacked solar cell can obtain more light absorption and improve the photoelectric conversion efficiency of the cell.

[0014] According to an embodiment of the present invention, the method for manufacturing the BC bottom cell includes: manufacturing a textured area in the area of the light-receiving surface of the BC bottom cell except for the polished surface area, wherein the perovskite top cell is formed on the surface of the conductive layer in the polished surface area.

[0015] In still another aspect of the present invention, the present invention provides a photovoltaic module. According to an embodiment of the present invention, the photovoltaic module includes the three-terminal stacked solar cell described above. Thus, the photovoltaic module has better cell efficiency and stability. Those skilled in the art can understand that the photovoltaic module has all the features and advantages of the three-terminal stacked solar cell described above, and will not be elaborated herein too much.

[0016] The additional aspects and advantages of the present invention will be partially given in the following description, partially will become obvious from the following description, or will be understood through the practice of the present invention. Description of the Drawings

[0017] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, wherein:

[0018] Figure 1 is a schematic structural diagram of a three-terminal stacked solar cell in an embodiment of the present invention.

[0019] Figure 2 is a schematic structural diagram of a three-terminal stacked solar cell in another embodiment of the present invention.

[0020] Figure 3 is a schematic structural diagram of a three-terminal stacked solar cell in still another embodiment of the present invention.

[0021] Figure 4 is a schematic structural diagram of a three-terminal stacked solar cell in still another embodiment of the present invention.

[0022] Figure 5It is a schematic structural diagram of a three-terminal tandem solar cell in another embodiment of the present invention.

[0023] Figure 6 It is a schematic structural diagram of a three-terminal tandem solar cell in another embodiment of the present invention.

[0024] Figure 7 It is a schematic structural diagram of a three-terminal tandem solar cell in another embodiment of the present invention.

[0025] Figure 8 It is a schematic structural diagram of a three-terminal tandem solar cell in another embodiment of the present invention.

[0026] Figure 9a and Figure 9b It is a schematic flow diagram of manufacturing a three-terminal tandem solar cell in another embodiment of the present invention.

[0027] Figure 10 It is a schematic flow diagram of manufacturing a three-terminal tandem solar cell in another embodiment of the present invention. Detailed implementation manners

[0028] The solutions of the present invention will be explained below 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 this field or according to the product specifications.

[0029] The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0030] In one aspect of the present invention, the present invention provides a three-terminal tandem solar cell. According to an embodiment of the present invention, referring to Figure 1 and Figure 2 , the three-terminal tandem solar cell includes: a BC bottom cell 10; at least one perovskite top cell 20, and at least one perovskite top cell 20 is disposed on the light-receiving surface of the BC bottom cell 10, and the area ratio of the total area of at least one perovskite top cell 20 to the area of the light-receiving surface of the BC bottom cell 10 is less than or equal to 0.5. In this way, by setting a perovskite top cell with a relatively small area, while giving full play to the short-wave absorption advantage of the perovskite top cell, the area that can directly absorb light in the light-receiving surface of the BC bottom cell (that is, the area of the region in the light-receiving surface of the BC bottom cell where no perovskite top cell is disposed) is increased. When light is incident, the reflectivity is reduced, the current of the BC bottom cell is increased, and thus it is helpful to improve the photoelectric conversion efficiency of the three-terminal tandem solar cell.

[0031] It should be noted that the above-mentioned "light-receiving surface area" includes the sum of the area of the perovskite top cell region and the area of the region without the perovskite top cell. Of course, here the "region without the perovskite top cell" only refers to the region without the top cell in the light-receiving surface of the BC bottom cell, and does not include other regions such as the backlight surface or the side surface.

[0032] According to some embodiments of the present invention, the ratio of the total area of all perovskite top cells to the area of the light-receiving surface equal to the area of the BC bottom cell is 0.3 to 0.5. Thus, it is possible to better balance the light-receiving area of the perovskite top cell and the area of the light-receiving surface of the BC bottom cell that can directly receive light, and better improve the photoelectric conversion efficiency of the three-terminal stacked solar cell.

[0033] According to some embodiments of the present invention, referring to Figure 3 and Figure 4 , the light-receiving surface of the BC bottom cell 10 includes a textured surface region 11 and at least one polished surface region 12. The polished surface region 12 is used for stacking the perovskite top cell 20, that is, the perovskite top cell 20 is located in the polished surface region 12. Thus, by arranging the perovskite top cell in the polished surface region, the flat and smooth surface is conducive to the preparation of the perovskite light-absorbing layer and other layer structures, which helps to obtain a perovskite top cell with good quality and performance, and improve the production yield and cell efficiency of the cell; moreover, the textured surface region without the perovskite top cell is the textured surface of the BC bottom cell. After setting an antireflection film on the textured surface, when light is incident, the reflectivity can be effectively reduced, and thus the current of the BC bottom cell can be increased, so that both the perovskite top cell and the crystalline silicon BC bottom cell have higher cell efficiency, and the overall efficiency of the three-terminal stacked solar cell is comprehensively improved.

[0034] It should be noted that here the "polished surface" is relative to the textured surface, that is, the polished surface region is a non-textured surface region that has not undergone texturing treatment and is a flat and smooth surface.

[0035] According to some embodiments of the present invention, the stacked solar cell may include a plurality of small-sized perovskite top cells. The area of the light-receiving surface of the BC bottom cell is 182mm * 210mm, and the area of a single perovskite top cell may be 10mm * 10mm, with a total of 114 to 191; according to some other embodiments of the present invention, the stacked solar cell may also include only one perovskite top cell. The area of the light-receiving surface of the BC bottom cell is 182mm * 210mm, and the area of the perovskite top cell is 11466 - 19110mm 2 , and its specific size can be flexibly set according to its shape.

[0036] According to some embodiments of the present invention, the BC cell includes a TBC cell, an HBC cell, or a hybrid BC cell. Among them, those skilled in the art can understand that the TBC cell can be a traditional conventional TBC cell, for example, both the P region and the N region are of the topcon structure, or it can be an improved TBC cell, for example, the P region is directly prepared on the silicon substrate without using the topcon structure, while the N region uses the topcon structure, thereby reducing costs and improving the passivation effect of the P region; the HBC cell is a BC cell in which both the P region and the N region on the back are of the HJT structure; the hybrid BC cell refers to a BC cell in which one of the P region and the N region on the back is of the topcon structure and the other is of the HJT structure. Further, the above BC bottom cell of the present invention can also be a BC cell structure in other conventional technologies. The following will introduce in detail the structure of the BC bottom cell in the three-terminal stacked solar cell according to some specific embodiments:

[0037] In some embodiments, referring to Figure 5 ( Figure 5 only showing one perovskite top cell as an example), the BC bottom cell includes: a silicon substrate 110, the silicon substrate 110 having a light-receiving surface and a backlight surface arranged opposite to each other, the backlight surface having an N region and a P region arranged at intervals, and the light-receiving surface of the silicon substrate 110 having a textured surface and a polished surface; a first passivation layer 119, the first passivation layer 119 being disposed on the textured surface of the silicon substrate 110; an antireflection film 111, the antireflection film 111 being disposed on a side of the first passivation layer 119 away from the silicon substrate; a first N-type doped polysilicon (N-poly) layer 112, the first N-type doped polysilicon layer 112 being disposed on the polished surface of the light-receiving surface; in a direction away from the silicon substrate 110, the N region is sequentially provided with a tunneling layer 113, a second N-type doped polysilicon (N-poly) layer 114, a second passivation layer 115, and a first electrode 116; in a direction away from the silicon substrate, the P region is sequentially provided with a tunneling layer 113, a P-type doped polysilicon (P-poly) layer 117, a second passivation layer 115, and a second electrode 118.

[0038] Among them, the above silicon substrate can be an N-type doped silicon substrate or a P-type doped silicon substrate. In addition, the back region of the gap between the P region and the N region can be set to a textured structure.

[0039] In some other embodiments, referring to Figure 6 ( Figure 6(only taking one perovskite top cell as an example), the improved TBC cell of the BC bottom cell, for example, the P region is directly prepared on a P-type doped silicon substrate, and its structure includes: a P-type doped silicon substrate 101, the P-type doped silicon substrate 101 has a light-receiving surface and a backlight surface arranged oppositely, the backlight surface has an N region and a P region, and the light-receiving surface has a textured surface and a polished surface; a first passivation layer 119, the first passivation layer 119 is arranged on the textured surface of the P-type doped silicon substrate 101; an antireflection film 111, the antireflection film 111 is arranged on the side of the first passivation layer 119 away from the P-type doped silicon substrate 101; an N-type heavily doped layer 1100, the N-type heavily doped layer 1100 is arranged on the polished surface of the light-receiving surface; a first N-type doped polysilicon layer 112, the first N-type doped polysilicon layer 112 is arranged on the side of the N-type heavily doped layer 1100 away from the P-type doped silicon substrate 101; in the direction away from the P-type doped silicon substrate 101, the N region is sequentially provided with a tunneling layer 113, a second N-type doped polysilicon layer 114, a second passivation layer 115, and a first electrode 116; in the direction away from the P-type doped silicon substrate 101, the P region is sequentially provided with a second passivation layer 115 and a second electrode 118, and the P region is a textured structure.

[0040] According to some embodiments of the present invention, in the above two structures, the antireflection film can be a single-layer structure or a multi-layer stacked structure, and its material can be at least one of materials including aluminum oxide, lithium fluoride, magnesium fluoride, tin oxide, etc.; the material of the tunneling layer can be silicon oxide; the first passivation layer and the second passivation layer can be respectively a single-layer structure or a multi-layer stacked structure, and their materials can be respectively at least one of materials including aluminum oxide, silicon nitride, silicon oxide, silicon oxynitride, etc.; the materials of the first electrode and the second electrode can be metal electrodes prepared by silver paste and / or aluminum paste respectively.

[0041] According to some embodiments of the present invention, in the above three-terminal stacked solar cell, the P region in the BC bottom cell serves as the positive extreme, the N region serves as the first negative extreme, and the perovskite top cell has a second negative extreme, constituting the three terminals of the stacked solar cell. The positive extreme and the first negative extreme can form one circuit, and the positive extreme can also form another circuit with the second negative extreme.

[0042] According to some embodiments of the present invention, referring to Figure 2 and Figure 4 , the three-terminal stacked solar cell includes a plurality of perovskite top cells 20, and the plurality of perovskite top cells 20 are arranged at intervals. Thus, by arranging a plurality of small-sized perovskite top cells 20 on the light-receiving surface of the BC bottom cell, the production quality of the small-sized perovskite top cells is relatively good, which helps to improve the overall production efficiency and cell efficiency of the three-terminal stacked solar cell.

[0043] According to some embodiments of the present invention, multiple perovskite top cells are symmetrically arranged (such as, including but not limited to, symmetric arrangement modes such as dot matrix symmetric arrangement, meandering divergent arrangement, and diagonal symmetric arrangement), and / or the shape of the perovskite top cell includes at least one of square, circular, elliptical, triangular, pentagonal, and hexagonal.

[0044] According to some embodiments of the present invention, there are no special requirements for the structure of the perovskite top cell, and those skilled in the art can flexibly select a suitable structure for the perovskite cell according to existing technical means.

[0045] According to some embodiments of the present invention, referring to Figure 7 and Figure 8 , a conductive layer 21 is further included between the BC bottom cell and the perovskite top cell.

[0046] In some specific embodiments, referring to Figure 7 and Figure 8 , in the direction away from the BC bottom cell, the perovskite top cell sequentially includes a first charge transport layer 22, a perovskite light-absorbing layer 23, a second charge transport layer 24, a transparent conductive layer 25, a packaging film 26, and an electrode 27.

[0047] Among them, the conductive layer 21 and the transparent conductive layer 25 can be transparent conductive materials (TCO), including but not limited to one or more of FTO (fluorine-doped tin oxide), ITO (indium tin oxide), AZO (aluminum-doped zinc oxide), BZO (boron-doped zinc oxide), IZO (indium zinc oxide), IGZO (indium gallium zinc oxide), and ATO (antimony tin oxide).

[0048] In some embodiments, one of the first charge transport layer 22 and the second charge transport layer 24 may be an electron transport layer, and the other may be a hole transport layer. In some embodiments, the hole transport layer is a self-assembled hole transport layer with a thickness of 0.5 to 2 nm. The hole transport material includes at least one of [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACz), (4-(3,6-dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid (Me-4PACz), [4-(9H-carbazol-9-yl)butyl]phosphonic acid (4PACz), (4-(3,6-dibromo-9H-carbazol-9-yl)butyl)phosphonic acid (Br-4PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), (2-(3,6-dimethyl-9H-carbazol-9-yl)ethyl)phosphonic acid (Me-2PACz), (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-dibromo-9H-carbazol-9-yl)ethyl)phosphonic acid (Br-2PACz), [4-(7H-dibenzocarbazol-7-yl)butyl]phosphonic acid (4PADCB). The above self-assembled hole transport material is anchored on the surface of the transparent electrode layer by a condensation reaction between the phosphonic acid group in the molecule and the hydroxyl group on the surface of the transparent electrode layer. Moreover, the technical solution of the present invention has a better improvement effect on the solar cell with a self-assembled hole transport layer. In some other embodiments of the present invention, the hole transport layer may also be a non-self-assembled hole transport layer, and its material may include nickel oxide (NiO x, where \(1\leq x\leq2\)), cuprous iodide (CuI), cuprous oxide (Cu₂O), cuprous thiocyanate (CuSCN), 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), 2,2',7,7'-tetrakis(di-p-tolylamino)spiro-9,9'-bifluorene (Spiro-TTB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACz), (4-(3,6-dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid (Me-4PACz), [4-(9H-carbazol-9-yl)butyl]phosphonic acid (4PACz), (4-(3,6-dibromo-9H-carbazol-9-yl)butyl)phosphonic acid (Br-4PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), (2-(3,6-dimethyl-9H-carbazol-9-yl)ethyl)phosphonic acid (Me-2PACz), (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-dibromo-9H-carbazol-9-yl)ethyl)phosphonic acid (Br-2PACz), or one or more of the like.

[0049] In some embodiments, the electron transport materials of the electron transport layer include, but are not limited to, tin oxide, fullerenes and their derivatives, imide compounds, quinone compounds, etc. Exemplarily, the imide compounds include at least one of phthalimide, succinimide, N-bromosuccinimide, glutarimide, or maleimide; Exemplarily, the quinone compounds include at least one of benzoquinone, naphthoquinone, phenanthrenequinone, or anthraquinone; Exemplarily, the fullerenes and their derivatives include fullerene C 60 , fullerene C 70 , PCBM ([6,6]-phenyl-C 61 -methyl butyrate), [6,6]-phenyl C 71 methyl butyrate (PC 71 BM), or at least one of them. Further, the electron transport layer can be a single-layer structure, or a double-layer or triple-layer structure. In some specific embodiments, the electron transport layer can include a C60 layer with a thickness of 5 - 20 nm and a tin oxide layer with a thickness of 15 - 20 nm. The setting of the tin oxide layer can protect C60 in subsequent processes.

[0050] In some embodiments, the material structure of the perovskite light-absorbing layer may be ABX3, where A is a monovalent cation, including but not limited to one or a mixture of several monovalent cations such as cesium (Cs), rubidium (Rb), methylammonium (CH3NH3), and formamidinium (CH2(NH2)2); B is a divalent cation, including but not limited to one or a mixture of several divalent cations such as lead (Pb) and tin (Sn); and X is a monovalent anion, including but not limited to one or a mixture of several monovalent anions such as iodine (I), bromine (Br), chlorine (Cl), fluorine (F), and thiocyanate ion (SCN). According to some embodiments of the present invention, the thickness of the perovskite light-absorbing layer is 500 - 700 nm, and the bandgap is 1.3 to 3.0 eV.

[0051] In some embodiments, the material of the encapsulation film may be metal oxide (such as materials like alumina or silica), glass, epoxy resin, etc.

[0052] In some embodiments, the material of the electrode may be a silver electrode, an aluminum electrode, etc.

[0053] On the other hand, the present invention provides a method for manufacturing the three-terminal stacked solar cell described above. According to an embodiment of the present invention, the method for manufacturing a three-terminal stacked solar cell includes:

[0054] S100: Manufacturing a BC bottom cell;

[0055] According to an embodiment of the present invention, the method for manufacturing a BC bottom cell includes: manufacturing a textured area in the area of the light-receiving surface of the BC bottom cell except for the polished surface area, where the perovskite top cell is formed on the surface of the conductive layer in the polished surface area. Thus, the perovskite top cell is arranged in the smooth and flat polished surface area. The smooth and flat surface is conducive to the preparation of the perovskite light-absorbing layer and other layer structures, which helps to obtain a perovskite top cell with good quality and performance, improving the production yield and efficiency of the cell. Moreover, the textured area without the perovskite top cell is the texture of the BC bottom cell. After a antireflection film is arranged on the texture, when light is incident, the reflectivity can be effectively reduced, thereby increasing the current of the BC bottom cell, enabling both the perovskite top cell and the crystalline silicon BC bottom cell to have higher cell efficiency, and comprehensively improving the overall efficiency of the three-terminal stacked solar cell.

[0056] According to some embodiments of the present invention, the BC cell includes a TBC cell, an HBC cell, or a hybrid BC cell. Among them, those skilled in the art can understand that the TBC cell can be a traditional conventional TBC cell, for example, both the P region and the N region are of the topcon structure, or it can be an improved TBC cell, for example, the P region is directly prepared on the silicon substrate without using the topcon structure, while the N region uses the topcon structure, thereby reducing costs and improving the passivation effect of the P region; the HBC cell is a BC cell in which both the P region and the N region on the back are of the HJT structure; the hybrid BC cell refers to a BC cell in which one of the P region and the N region on the back is of the topcon structure and the other is of the HJT structure. Further, the above BC bottom cell of the present invention can also be a BC cell structure in other conventional technologies. The following introduces in detail the preparation method of the BC bottom cell in the three-terminal stacked solar cell according to some specific embodiments:

[0057] In some embodiments, referring to Figure 9a and Figure 9b ( Figure 9a and Figure 9b only showing a perovskite top cell as an example), the preparation of the BC bottom cell includes:

[0058] S110: Provide a silicon substrate 110, polish the surface of the silicon substrate, and then deposit a tunneling oxide layer 113 on the backlight surface.

[0059] S111: Deposit a P-type doped polysilicon layer 117 on the light-receiving surface and the backlight surface (or only on the backlight surface) of the silicon substrate 110, and form a layer of borosilicate glass (BSG) 1170 on the surface of the P-type doped polysilicon layer.

[0060] In some embodiments, the method of depositing the P-type doped polysilicon layer can be chemical vapor deposition (such as low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD)), and then the P-type doped polysilicon layer 117 can be obtained through annealing.

[0061] S112: Remove the borosilicate glass in part of the area on the backlight surface by laser, and only retain the borosilicate glass in the P region to achieve patterning of the borosilicate glass.

[0062] S113: Chain-remove the borosilicate glass on the light-receiving surface, and trough-remove the P-type doped polysilicon layer 117 exposed on the backlight surface after laser removal of the borosilicate glass and the P-type doped polysilicon layer 117 on the light-receiving surface.

[0063] S114: Deposit an N-type doped polysilicon layer 1124 on the light-receiving surface and the backlight surface, and form a layer of phosphosilicate glass (PSG) 11240 on the surface of the N-type doped polysilicon layer 1124.

[0064] In some embodiments, the method for depositing the N-type doped polysilicon layer described above may be chemical vapor deposition (such as low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD)), and then an N-type doped polysilicon layer can be obtained through annealing.

[0065] S115: Remove the phosphosilicate glass in a partial area of the light-receiving surface through laser, leaving only the phosphosilicate glass in the polished surface area (i.e., the area where the perovskite top cell needs to be fabricated) on the light-receiving surface, and remove the phosphosilicate glass in a partial area of the backlight surface through laser, leaving only the phosphosilicate glass at the area where the second N-type doped polysilicon layer needs to be formed on the backlight surface, thereby realizing patterning of the phosphosilicate glass.

[0066] S116: Use a grooving machine to texture the area on the light-receiving surface where no perovskite top cell is provided, and texture the area between the N region and the P region on the backlight surface. At the same time, partially remove the N-type doped polysilicon layer in the area on the light-receiving surface where no perovskite top cell is provided to obtain the first N-type doped polysilicon layer 112, and remove the partially exposed N-type doped polysilicon layer on the backlight surface by the phosphosilicate glass to obtain the second N-type doped polysilicon layer 114.

[0067] S117; Clean and remove the remaining borosilicate glass and phosphosilicate glass.

[0068] S118: Deposit a first passivation layer 119 and an antireflection film 111 on the textured surface of the light-receiving surface in sequence, and deposit a second passivation layer 115 on the backlight surface.

[0069] S119: Metallize and sinter on the backlight surface to obtain a first electrode 117 and a second electrode 118, and obtain a BC bottom cell.

[0070] It should be noted that the above manufacturing steps are only the manufacturing steps of a specific embodiment, and some step sequences can be adjusted according to actual situations under the allowable process conditions.

[0071] In some other embodiments, referring to Figure 10 ( Figure 10 taking only one perovskite top cell as an example), the preparation of the BC bottom cell includes:

[0072] S120: Provide a P-type doped silicon substrate 101, polish the surface of the P-type doped silicon substrate, and then deposit a tunneling oxide layer 113 on the backlight surface.

[0073] S121: Perform N-type heavy doping on the area where a polished surface needs to be formed in the light-receiving surface of the P-type doped silicon substrate 101 to obtain an N-type heavy doping layer 1100.

[0074] S122: Deposit an N-type doped polysilicon layer 1124 on the light-receiving surface and the backlight surface (or only on the backlight surface) of the P-type doped silicon substrate 101, and at the same time, form a layer of phosphosilicate glass (PSG) 11240 on the surface of the N-type doped polysilicon layer 1124.

[0075] In some embodiments, the method for depositing the N-type doped polysilicon layer 1124 may be chemical vapor deposition (such as low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD)), and then the N-type doped polysilicon layer 1124 can be obtained through annealing.

[0076] S123: Remove the phosphosilicate glass in some areas of the backlight surface through a laser, only retain the phosphosilicate glass in the N region, and achieve patterning of the back phosphosilicate glass; at the same time, remove the phosphosilicate glass in some areas of the light-receiving surface through a laser, only retain the phosphosilicate glass in the area directly above the N-type heavily doped layer 1100, and achieve patterning of the front phosphosilicate glass.

[0077] S124: Etch the N-type doped polysilicon layer 1124 exposed by the phosphosilicate glass on the light-receiving surface and the backlight surface. Obtain a first N-type doped polysilicon layer 112 on the light-receiving surface and a second N-type doped polysilicon layer 114 on the backlight surface respectively, and perform texturing on the light-receiving surface where a textured surface needs to be formed, and perform texturing on the P region of the backlight surface.

[0078] S125: Clean and remove the remaining phosphosilicate glass.

[0079] S126: Deposit a first passivation layer 119 and an antireflection film 111 in sequence on the textured surface of the light-receiving surface, and deposit a second passivation layer 115 on the backlight surface.

[0080] S127: Metallize and sinter on the backlight surface to obtain a first electrode 117 and a second electrode 118, and obtain a BC bottom cell.

[0081] It should be noted that the above manufacturing steps are only the manufacturing steps of a specific embodiment, and some step sequences can be adjusted according to the actual situation under the allowable process conditions.

[0082] S200: Fabricate at least one perovskite top cell on the light-receiving surface of the BC bottom cell, and the area ratio of the total area of the at least one perovskite top cell to the area of the light-receiving surface of the BC bottom cell is less than or equal to 0.5.

[0083] According to some embodiments of the present invention, there is no special requirement for the structure of the perovskite top cell, and those skilled in the art can flexibly select a suitable structure of the perovskite cell according to existing technical means.

[0084] In some specific embodiments, refer to Figure 7 andFigure 8 , in the direction away from the BC bottom cell, the perovskite top cell sequentially includes a first charge transport layer 22, a perovskite light-absorbing layer 23, a second charge transport layer 24, a transparent conductive layer 25, a packaging film 26, and an electrode 27.

[0085] According to some embodiments of the present invention, referring to Figure 7 and Figure 8 , before fabricating the perovskite top cell, it further includes forming a conductive layer 21 on the polished surface area of the BC bottom cell (i.e., the surface of the first N-type doped polysilicon layer 112) to connect the bottom cell and the top cell.

[0086] In some embodiments, the method of fabricating a perovskite top cell (taking the top cell as a reverse perovskite structure as an example) includes:

[0087] S210: Form a hole transport layer (i.e., the first charge transport layer 22) on the side of the conductive layer 21 away from the BC bottom cell by a solution method or a vapor deposition method.

[0088] In some specific embodiments, the solution method can be a spin coating method, a spraying method, printing, etc.

[0089] S220: Form a perovskite light-absorbing layer 23 on the side of the hole transport layer away from the BC bottom cell.

[0090] In some specific embodiments, the method of forming the perovskite light-absorbing layer 23 may include: coating the perovskite precursor solution on the side of the hole transport layer away from the BC bottom cell, and then annealing and crystallizing at a certain temperature to obtain the perovskite light-absorbing layer 23.

[0091] S230: Form an electron transport layer (i.e., the second charge transport layer 24) on the side of the perovskite light-absorbing layer 23 away from the BC bottom cell.

[0092] In some specific embodiments, a single-layer structure or a multi-layer structure electron transport layer can be prepared by a vacuum evaporation method and an atomic deposition method.

[0093] S240: Form a transparent conductive layer 25 on the side of the electron transport layer away from the BC bottom cell.

[0094] S250: Form a packaging film 26 and an electrode 27 on the side of the transparent conductive layer 25 away from the BC bottom cell.

[0095] In some specific embodiments, the electrode 27 can be prepared by thermal evaporation or screen printing.

[0096] It should be noted that there are no special requirements for the specific process parameters and conditions for preparing the BC bottom cell and the perovskite top cell above. Those skilled in the art can flexibly set them according to the existing technical means and common general knowledge, and no limiting requirements are made here.

[0097] According to an embodiment of the present invention, in the above preparation method, by forming a perovskite top cell with a relatively small area, while fully exerting the short-wave absorption advantage of the perovskite top cell, the area that can directly absorb light in the light-receiving surface of the BC bottom cell is increased (that is, the area region in the light-receiving surface of the BC bottom cell where the perovskite top cell is not provided). When light is incident, the reflectivity is reduced, the current of the BC bottom cell is increased, and thus the photoelectric conversion efficiency of the cell is improved. Furthermore, a certain polished surface region is reserved on the light-receiving surface of the BC bottom cell, and the perovskite top cell is formed in the polished surface region. The flat and smooth surface is conducive to the preparation of the perovskite light-absorbing layer and other layer structures, and thus helps to obtain a perovskite top cell with good quality and performance, improving the production yield and efficiency of the cell. Moreover, the textured surface of the BC bottom cell is provided in the textured surface region where the perovskite top cell is not provided. After an antireflection film is provided on the textured surface, when light is incident, the reflectivity can be effectively reduced, and thus the current of the BC bottom cell can be increased, enabling both the perovskite top cell and the crystalline silicon BC bottom cell to have higher cell efficiency, and thus comprehensively improving the overall efficiency of the three-terminal stacked solar cell.

[0098] In another aspect of the present invention, the present invention provides a photovoltaic module. According to an embodiment of the present invention, the photovoltaic module includes the three-terminal stacked solar cell described above. Thus, the photovoltaic module has better cell efficiency and stability. Those skilled in the art can understand that the photovoltaic module has all the features and advantages of the three-terminal stacked solar cell described above, and will not be elaborated here too much.

[0099] Embodiment

[0100] The manufacturing method for manufacturing a three-terminal stacked solar cell includes:

[0101] Providing an N-type doped silicon substrate, polishing the surface of the N-type doped silicon substrate, and then depositing a tunneling oxide layer with a thickness of 1.9 nm on the backlight surface by LPCVD, wherein the deposition temperature is 610 °C and the time is 680 s;

[0102] An amorphous silicon layer is deposited on the light-receiving surface and the backlight surface of the silicon substrate by LPCVD at a temperature of 550 °C for 8000 s, and the thickness of the amorphous silicon is 360 nm. After the LPCVD process, a boron diffusion process is carried out, crystallized at 960 °C for 5000 s, the amorphous silicon is transformed into a polycrystalline state, diffused at 830 °C for 700 s, and then heated to 960 °C and pushed for 500 s to obtain a P-type doped polycrystalline silicon layer, and oxidized at 960 °C for 1200 s to form a borosilicate glass (BSG) layer on the surface of the P-type doped polycrystalline silicon layer;

[0103] The borosilicate glass in some areas on the back is removed by laser, and only the borosilicate glass in the P region is retained to achieve patterning of the borosilicate glass. Among them, the laser wavelength is 532 nm, the pulse is 1 μs, the pulse energy is 90 μj, and the frequency is 550 kHz;

[0104] The borosilicate glass on the front is removed by chain type (the acid solution is composed of HF and H2O in a volume ratio of 3:2, the pickling time is 40 s, and the temperature of the acid solution is 30 °C), and the P-type doped polycrystalline silicon layer exposed after the borosilicate glass on the back is removed by laser and the P-type doped polycrystalline silicon layer on the front are removed by tank type (the temperature of the alkali polishing tank is 60 °C, the process time is 450 s, the alkali solution is composed of H2O, NaOH and a texturing additive in a volume ratio of 300:12:5, and the concentration of NaOH is about 3%);

[0105] An amorphous silicon layer is formed by LPCVD at a temperature of 610 °C for 3500 s, and the thickness of the amorphous silicon layer is 280 nm. Then a phosphorus diffusion process is carried out, diffused at 860 °C for 1550 s, and then heated to 880 °C and pushed for 400 s to deposit a 280-nm-thick N-type doped polycrystalline silicon layer on the light-receiving surface and the backlight surface, and oxidized at 900 °C for 600 s on the surface of the N-type doped polycrystalline silicon layer to form a 50-nm-thick phosphosilicate glass (PSG);

[0106] The phosphosilicate glass in some areas on the front is removed by laser, and only the phosphosilicate glass in the second area (i.e., the area where the perovskite top cell needs to be fabricated) is retained on the front, and the phosphosilicate glass in some areas on the back is removed by laser, and only the phosphosilicate glass in the area where the second N-type doped polycrystalline silicon layer needs to be formed is retained on the back to achieve patterning of the phosphosilicate glass. Among them, the laser conditions are: wavelength 532 nm, pulse 1 μs, pulse energy 90 μj, frequency 500 kHz;

[0107] Wet chemical texturing is carried out on the area of the front where the perovskite top cell is not set and on the area between the N region and the P region on the back. At the same time, part of the N-type doped polycrystalline silicon layer in the area of the front where the perovskite top cell is not set is removed to obtain the first N-type doped polycrystalline silicon layer, and part of the N-type doped polycrystalline silicon layer exposed by the phosphosilicate glass on the back is removed to obtain the second N-type doped polycrystalline silicon layer.

[0108] Use a wet acid bath (acid bath temperature is 40°C, time is 120 s, acid solution is composed of H2O and HF in a volume ratio of 3:2) to clean and remove the remaining borosilicate glass and phosphosilicate glass;

[0109] Deposit a 4-nm aluminum oxide passivation layer on the textured surface of the light-receiving surface by atomic layer deposition, and then deposit 10-nm silicon nitride 1, 12-nm silicon nitride 2, 15-nm silicon nitride 3, 10-nm silicon oxynitride 1, 17-nm silicon oxynitride 2, and 12-nm silicon oxide in sequence by PECVD to obtain an antireflection film. The total thickness of the antireflection film is 70 - 85 nm and the refractive index is 2.1; on the backlight surface, deposit 20-nm silicon nitride 1, 29-nm silicon nitride 2, and 35-nm silicon nitride in sequence by PECVD to obtain a passivation layer.

[0110] Metalize and sinter on the backlight surface to obtain the first electrode - silver electrode and the second electrode - silver electrode, and then obtain the BC bottom cell. The structural schematic diagram is as Figure 5 shown;

[0111] Deposit a TCO conductive layer on the surface of the first N-type doped polysilicon layer on the front of the BC bottom cell, and the thickness of the conductive layer is 15 nm;

[0112] Coat the Me-4PACZ solution on the surface of the conductive layer, and then anneal at 100°C for 10 min to obtain a self-assembled single-molecule hole transport layer;

[0113] Drop the perovskite precursor solution on the surface of the hole transport layer, spin-coat at a speed of 2000 revolutions per minute for 30 s, and immediately put the cell substrate on a hot plate at 100°C for annealing for 10 minutes after spin-coating to make the perovskite crystals fully crystallize to form a 600-nm-thick perovskite light-absorbing layer. Among them, the preparation method of the perovskite precursor solution includes: weighing methylammonium lead iodide (CH3NH3PbI3), chlorobenzylammonium lead iodide (C6H5CH2NH3PbI3), and cesium bromide (CsBr) according to a molar ratio of 1:1:1, and dissolving them in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The volume ratio of DMF to DMSO is 4:1, and a perovskite precursor solution with a concentration of 01.5 M is prepared, and it is stirred in a glove box for about 12 hours to ensure that the solute is fully dissolved;

[0114] Vacuum deposit a 15-nm-thick C60 layer on the surface of the perovskite light-absorbing layer, and then deposit a layer of 8-nm-thick tin oxide layer by ALD method to obtain an electron transport layer;

[0115] Deposit a 50-nm-thick ITO layer on the surface of the electron transport layer by magnetron sputtering;

[0116] A silver electrode with a thickness of 100 nm is deposited on the surface of the ITO layer by thermal evaporation, where the silver evaporation rate is 0.1 nm / s;

[0117] A packaging film is fabricated to obtain a square perovskite top cell.

[0118] Among them, the light-receiving surface area of the BC bottom cell is 182 mm × 210 mm, and the area of a single perovskite top cell is 10 mm × 10 mm. A plurality of perovskite top cells are uniformly arranged in an array on the light-receiving surface of the BC bottom cell, such that the area ratio of the perovskite top cell to the light-receiving surface area of the BC bottom cell is 0.3 to 0.5.

[0119] The comprehensive performance of a three-terminal tandem solar cell obtained by setting different numbers of perovskite top cells on a bottom cell of the same size is evaluated using the same preparation process. When the area ratio of the total area of the top cell to the light-receiving surface area of the bottom cell is between 0.3 and 0.5, the comprehensive performance of the tandem solar cell is the best. The comprehensive performance takes into account the matching difficulty between the top and bottom cells, the cell conversion efficiency, the manufacturing difficulty, etc.

[0120] The terms "first" and "second" in the text are for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0121] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means 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 contradiction, 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.

[0122] 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 three-terminal stacked solar cell, characterized in that, Comprising: BC bottom cell; At least one perovskite top cell, at least one of the perovskite top cells being disposed on a light-receiving surface of the BC bottom cell, and an area ratio of a total area of at least one of the perovskite top cells to an area of the light-receiving surface of the BC bottom cell being less than or equal to 0.

5.

2. The three-terminal stacked solar cell according to claim 1, characterized in that, An area ratio of a total area of all the perovskite top cells to an area of the light-receiving surface of the BC bottom cell is 0.3 to 0.

5.

3. The three-terminal stacked solar cell according to claim 1, wherein, Including a plurality of the perovskite top cells, and the plurality of the perovskite top cells are spaced apart.

4. The three-terminal laminated solar cell according to any one of claims 1 to 3, characterized in that The BC cell includes a TBC cell, an HBC cell or a hybrid BC cell.

5. The three-terminal stacked solar cell according to claim 4, wherein, The light-receiving surface of the BC bottom cell includes a matte surface area and at least one polished surface area, and the perovskite top cell is located in the polished surface area.

6. The three-terminal stacked solar cell according to claim 3, wherein The plurality of perovskite top cells are symmetrically arranged, and / or a shape of the perovskite top cell includes at least one of a square, a circle, an ellipse, a triangle, a pentagon, and a hexagon.

7. The three-terminal stacked solar cell according to claim 5, wherein The BC bottom cell includes: A silicon substrate having the light-receiving surface and a backlight surface disposed opposite to each other, the backlight surface having an N region and a P region disposed at intervals, and the light-receiving surface having a matte surface and a polished surface; A first passivation layer disposed on the matte surface of the silicon substrate; An antireflection film disposed on a side of the first passivation layer away from the silicon substrate; A first N-type doped polysilicon layer disposed on the polished surface of the silicon substrate; In a direction away from the silicon substrate, the N region is sequentially provided with a tunneling layer, a second N-type doped polysilicon layer, a second passivation layer, and a first electrode; In a direction away from the silicon substrate, the P region is sequentially provided with the tunneling layer, a P-type doped polysilicon layer, the second passivation layer, and a second electrode.

8. The three-terminal stacked solar cell according to claim 5, wherein, The BC bottom cell includes: A P-type doped silicon substrate having a light-receiving surface and a backlight surface disposed opposite to each other, the backlight surface having an N region and a P region, and the light-receiving surface having a matte surface and a polished surface; A first passivation layer disposed on the matte surface of the P-type doped silicon substrate; An antireflection film disposed on a side of the first passivation layer away from the P-type doped silicon substrate; An N-type heavily doped layer disposed on the polished surface; A first N-type doped polysilicon layer disposed on a side of the N-type heavily doped layer away from the P-type doped silicon substrate; In a direction away from the P-type doped silicon substrate, the N region is sequentially provided with a tunneling layer, a second N-type doped polysilicon layer, a second passivation layer, and a first electrode; In a direction away from the P-type doped silicon substrate, the P region is sequentially provided with the second passivation layer and a second electrode, and the P region is matte.

9. The three-terminal stacked solar cell according to claim 5, wherein, A conductive layer is further included between the BC bottom cell and the perovskite top cell.

10. A method for fabricating a three-terminal stacked solar cell according to any one of claims 1 to 9, characterized in that, Including: Fabricating a BC bottom cell; Fabricating at least one perovskite top cell on a light-receiving surface of the BC bottom cell, and an area ratio of a total area of at least one of the perovskite top cells to an area of the light-receiving surface of the BC bottom cell being less than or equal to 0.

5.

11. The method according to claim 10, wherein The method for fabricating the BC bottom cell includes: fabricating a textured region in a region of the light-receiving surface of the BC bottom cell other than the polished surface region, wherein the perovskite top cell is formed on the surface of the conductive layer in the polished surface region.

12. A photovoltaic module, characterized in that, A three-terminal stacked solar cell according to any one of claims 1 to 9.

Images