Three-terminal laminated solar cell and photovoltaic module
By setting a smaller perovskite top cell in a three-terminal tandem solar cell and optimizing the light-receiving surface structure, the problem of limited photoelectric conversion efficiency of BC cells was solved, and higher photoelectric conversion efficiency and cell efficiency were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WUHU GCL INTEGRATED NEW ENERGY TECH CO LTD
- Filing Date
- 2025-04-07
- Publication Date
- 2026-04-28
AI Technical Summary
The photoelectric conversion efficiency of existing perovskite cells is limited by bandgap constraints, and short-wavelength light energy is not fully utilized. Furthermore, large-size perovskite cells are difficult to fabricate or of poor quality, which affects the efficiency of stacked cells.
A three-terminal tandem solar cell is designed, with a smaller perovskite top cell placed on the light-receiving surface of the BC bottom cell. The total area of the perovskite top cell does not exceed 0.5 times the area of the light-receiving surface of the BC bottom cell. By combining the optimization of the polished and textured surfaces, the reflectivity is reduced and the current of the BC bottom cell is increased.
It improves the photoelectric conversion efficiency of three-terminal tandem solar cells, enhances the cell efficiency of perovskite top cells and BC bottom cells, and improves the overall cell performance and stability.
Smart Images
Figure CN224178549U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of solar cell technology, specifically to a three-terminal tandem solar cell and a photovoltaic module. Background Technology
[0002] Back-contact (BC) cells have no grid lines on the front, maximizing light energy utilization. However, due to the bandgap limitation of a single BC cell, only a portion of the light at the short-wavelength end is utilized. BC cells can only absorb energy matching the bandgap width; the excess energy is lost as heat, limiting their photoelectric conversion efficiency. The theoretical limit of BC cell efficiency is approximately 28.7%. To improve efficiency, tandem cells are commonly used, such as integrating perovskite cells onto crystalline silicon cells. Furthermore, BC-perovskite tandem solar cells are three-terminal cells. Compared to two-terminal cells, the top and bottom cells of a three-terminal tandem cell can output current independently without current matching, resulting in higher efficiency. However, large-size perovskite cells are difficult to fabricate, or the fabrication quality is poor, hindering improvements in tandem cell efficiency. Utility Model Content
[0003] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one objective of this invention is to provide a three-terminal tandem solar cell with high photoelectric conversion efficiency.
[0004] In one aspect, this invention provides a three-terminal tandem solar cell. According to an embodiment of this invention, the three-terminal tandem solar cell includes: a BC bottom cell; at least one perovskite top cell, wherein the at least one perovskite top cell is disposed on the light-receiving surface of the BC bottom cell, and the 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, by using a relatively small perovskite top cell, the short-wavelength absorption advantage of the perovskite top cell is fully utilized while increasing the area of the light-receiving surface of the BC bottom cell that can directly absorb light (i.e., the area of the light-receiving surface of the BC bottom cell where the perovskite top cell is not disposed). When light is incident, the reflectivity is reduced, the current of the BC bottom cell is increased, thereby contributing to improving the photoelectric conversion efficiency of the three-terminal tandem solar cell.
[0005] According to an embodiment of the present invention, the ratio of the total area of all the 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.
[0006] According to an embodiment of the present invention, a three-terminal tandem solar cell includes a plurality of the aforementioned perovskite top cells, and the plurality of the aforementioned perovskite top cells are arranged at intervals.
[0007] According to embodiments of the present invention, the BC battery includes a TBC battery, an HBC battery, or a hybrid BC battery.
[0008] According to an embodiment of the present invention, the light-receiving surface of the BC bottom cell includes a textured area and at least one polished area, and the perovskite top cell is located in the polished area.
[0009] According to embodiments of the present invention, a plurality of the perovskite top cells are symmetrically arranged, and / or the shape of the perovskite top cells includes at least one of square, circular, elliptical, triangular, pentagonal, and hexagonal.
[0010] According to an embodiment of the present invention, the BC-based solar cell includes: a silicon substrate having a light-receiving surface and a back-lighting surface disposed opposite to each other, the back side having N-regions and P-regions disposed at intervals, and the light-receiving surface having a textured surface and a polished surface; a first passivation layer disposed on the textured surface of the silicon substrate; an anti-reflection film disposed on the 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-type bottom battery includes: a P-type doped silicon substrate having a light-receiving surface and a back-lighting surface disposed opposite to each other, the back surface having an N-region and a P-region, and the light-receiving surface having a textured surface and a polished surface; a first passivation layer disposed on the textured surface of the P-type doped silicon substrate; an anti-reflection film disposed on the 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 polycrystalline silicon layer disposed on the side of the N-type heavily doped layer away from the P-type doped silicon substrate; in the direction away from the P-type doped silicon substrate, the N-region is sequentially provided with a tunneling layer, a second N-type doped polycrystalline silicon layer, a second passivation layer, and a first electrode; in the direction away from the P-type doped silicon substrate, the P-region is sequentially provided with a second passivation layer and a second electrode, and the P-region has a textured surface.
[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, this utility model provides a photovoltaic module. According to an embodiment of this utility model, the photovoltaic module includes the three-terminal tandem solar cell described above. Therefore, this photovoltaic module has better cell efficiency and stability. Those skilled in the art will understand that this photovoltaic module possesses all the features and advantages of the three-terminal tandem solar cell described above, which will not be elaborated further here.
[0014] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0015] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0016] Figure 1 This is a schematic diagram of the structure of a three-terminal stacked solar cell in one embodiment of this utility model.
[0017] Figure 2 This is a schematic diagram of the structure of a three-terminal stacked solar cell in another embodiment of this utility model.
[0018] Figure 3 This is a schematic diagram of the structure of a three-terminal stacked solar cell in another embodiment of this utility model.
[0019] Figure 4 This is a schematic diagram of the structure of a three-terminal stacked solar cell in another embodiment of this utility model.
[0020] Figure 5 This is a schematic diagram of the structure of a three-terminal stacked solar cell in another embodiment of this utility model.
[0021] Figure 6 This is a schematic diagram of the structure of a three-terminal stacked solar cell in another embodiment of this utility model.
[0022] Figure 7 This is a schematic diagram of the structure of a three-terminal stacked solar cell in another embodiment of this utility model.
[0023] Figure 8 This is a schematic diagram of the structure of a three-terminal stacked solar cell in another embodiment of this utility model.
[0024] Figure 9a and Figure 9b This is a schematic diagram of the process for fabricating a three-terminal tandem solar cell in another embodiment of this utility model.
[0025] Figure 10 This is a schematic diagram of the process for fabricating a three-terminal tandem solar cell in another embodiment of this utility model. Detailed Implementation
[0026] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the field or in accordance with the product manual.
[0027] The present invention will now be described 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.
[0028] In one aspect, this utility model provides a three-terminal tandem solar cell. According to an embodiment of this utility model, referring to… Figure 1 and Figure 2 The three-terminal tandem solar cell includes: a BC bottom cell 10; and at least one perovskite top cell 20. The at least one perovskite top cell 20 is disposed on the light-receiving surface of the BC bottom cell 10, and the ratio of the total area of the 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. Thus, by using a relatively small perovskite top cell, the short-wavelength absorption advantage of the perovskite top cell is fully utilized, while increasing the area of the BC bottom cell's light-receiving surface that can directly absorb light (i.e., the area of the BC bottom cell's light-receiving surface without the perovskite top cell). When light is incident, this reduces reflectivity, increases the current of the BC bottom cell, and thus helps to improve the photoelectric conversion efficiency of the three-terminal tandem solar cell.
[0029] It should be noted that the "light-receiving surface area" mentioned above includes the sum of the area where the perovskite top cell is set and the area where the perovskite top cell is not set. Of course, the "area where the perovskite top cell is not set" here only refers to the area of the light-receiving surface of the BC bottom cell where the top cell is not set, and does not include other areas such as the backlight or sides.
[0030] According to some embodiments of this 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. This allows for a better balance between the light-receiving area of the perovskite top cells and the area of the BC bottom cells that can directly receive light, thus improving the photoelectric conversion efficiency of the three-terminal tandem solar cell.
[0031] According to some embodiments of this utility model, refer to Figure 3 and Figure 4The 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 to stack the perovskite top cell 20, that is, the perovskite top cell 20 is located in the polished surface region 12. Thus, by setting the perovskite top cell in the polished surface region, the smooth surface is conducive to the preparation of the perovskite light-absorbing layer and other layer structures, thereby helping to obtain a perovskite top cell with good quality and performance, improving the cell manufacturing yield and cell efficiency. Moreover, the textured surface region without the perovskite top cell is the textured surface of the BC bottom cell. After setting the anti-reflection film on the textured surface, the reflectivity can be effectively reduced when light is incident, thereby increasing the current of the BC bottom cell. This results in higher cell efficiency for both the perovskite top cell and the crystalline silicon BC bottom cell, thus comprehensively improving the overall efficiency of the three-terminal stacked solar cell.
[0032] It should be noted that the term "polished surface" here is in contrast to the textured surface. The polished surface area refers to the non-textured area that has not undergone textured treatment and is a flat and smooth surface.
[0033] According to some embodiments of the present invention, a tandem solar cell may include multiple small-sized perovskite top cells, with the light-receiving surface area of the BC bottom cell being 182mm*210mm, and the area of a single perovskite top cell being 10mm*10mm, totaling 114 to 191 cells. According to other embodiments of the present invention, a tandem solar cell may also include only one perovskite top cell, with the light-receiving surface area of the BC bottom cell being 182mm*210mm, and the area of the perovskite top cell being 11466-19110mm². 2 Its specific dimensions can be flexibly set according to its shape.
[0034] According to some embodiments of this utility model, the BC battery includes a TBC battery, an HBC battery, or a hybrid BC battery. Those skilled in the art will understand that a TBC battery can be a conventional TBC battery, such as one where both the P-region and N-region have a topcon structure, or it can be an improved TBC battery, such as one where the P-region is directly fabricated on the silicon substrate without a topcon structure, while the N-region uses a topcon structure, thereby reducing costs and improving the passivation effect of the P-region. An HBC battery is a BC battery where both the P-region and N-region on the back side have an HJT structure. A hybrid BC battery refers to a BC battery where one of the P-regions and N-region on the back side has a topcon structure, and the other has an HJT structure. Furthermore, the BC bottom battery of this utility model can also be a BC battery structure from other conventional technologies. The structure of the BC bottom battery in a three-terminal tandem solar cell is described in detail below based on some specific embodiments:
[0035] In some embodiments, refer to Figure 5 ( Figure 5(Taking only one perovskite top cell as an example), the BC bottom cell includes: a silicon substrate 110, which has a light-receiving surface and a back-lighting surface disposed opposite to each other. The back-lighting surface has N-regions and P-regions disposed at intervals. The light-receiving surface of the silicon substrate 110 has a textured surface and a polished surface; a first passivation layer 119, which is disposed on the textured surface of the silicon substrate 110; an anti-reflection film 111, which is disposed on the side of the first passivation layer 119 away from the silicon substrate; and a first N-type doped polycrystalline silicon. (N-poly) layer 112, the first N-type doped polysilicon layer 112 is disposed on the polished surface of the light-receiving surface; in the direction away from the silicon substrate 110, the N region is sequentially disposed of 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 the direction away from the silicon substrate, the P region is sequentially disposed of a tunneling layer 113, a P-type doped polysilicon (P-poly) layer 117, a second passivation layer 115 and a second electrode 118.
[0036] The silicon substrate mentioned above can be an N-type doped silicon substrate or a P-type doped silicon substrate. Additionally, the back surface region of the gap between the P-region and the N-region can be configured with a textured surface.
[0037] In other embodiments, reference is made to Figure 6 ( Figure 6 (Taking only one perovskite top cell as an example), the TBC cell, an improvement on the BC bottom cell, for example, where the P-region is directly fabricated on a P-type doped silicon substrate, has the following structure: a P-type doped silicon substrate 101, which has a light-receiving surface and a back-lighting surface arranged opposite each other. The back-lighting surface has N-regions and P-regions, and the light-receiving surface has a textured surface and a polished surface; a first passivation layer 119, which is disposed on the textured surface of the P-type doped silicon substrate 101; an anti-reflection film 111, which is disposed on the side of the first passivation layer 119 away from the P-type doped silicon substrate 101; and an N-type heavily doped... A doped layer 1100, an N-type heavily doped layer 1100 is disposed on the polished surface of the light-receiving surface; a first N-type doped polysilicon layer 112 is disposed 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, a tunneling layer 113, a second N-type doped polysilicon layer 114, a second passivation layer 115 and a first electrode 116 are sequentially disposed in the N region; in the direction away from the P-type doped silicon substrate 101, a second passivation layer 115 and a second electrode 118 are sequentially disposed in the P region, and the P region has a textured structure.
[0038] According to some embodiments of this utility model, in the two structures described above, the antireflective 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, and silicon oxide; the material of the tunneling layer can be silicon oxide; the first passivation layer and the second passivation layer can each be a single-layer structure or a multi-layer stacked structure, and their materials can each be at least one of materials including aluminum oxide, silicon nitride, silicon oxide, and silicon oxynitride; the materials of the first electrode and the second electrode can each be metal electrodes prepared with silver paste and / or aluminum paste.
[0039] According to some embodiments of the present invention, in the above-mentioned three-terminal tandem solar cell, the P region of the BC bottom cell is used as the positive terminal, the N region is used as the first negative terminal, and the perovskite top cell has a second negative terminal, which constitutes the three terminals of the tandem solar cell. The positive terminal and the first negative terminal can form a circuit, and the positive terminal and the second negative terminal can form another circuit.
[0040] According to some embodiments of this utility model, refer to Figure 2 and Figure 4 The three-terminal tandem solar cell includes multiple perovskite top cells 20, which are spaced apart. This allows for the placement of more small-sized perovskite top cells 20 on the light-receiving surface of the BC bottom cell. The smaller perovskite top cells have better fabrication quality, which helps improve the overall fabrication efficiency and cell efficiency of the three-terminal tandem solar cell.
[0041] According to some embodiments of the present invention, multiple perovskite top cells are symmetrically arranged (such as including but not limited to symmetrical arrangement of dots, radial divergent arrangement, oblique symmetrical arrangement, etc.), and / or the shape of the perovskite top cells includes at least one of square, circular, elliptical, triangular, pentagonal, and hexagonal.
[0042] According to some embodiments of this utility model, there are no special requirements for the structure of the perovskite top cell. Those skilled in the art can flexibly select a suitable perovskite cell structure based on existing technical means.
[0043] According to some embodiments of this utility model, refer to Figure 7 and Figure 8 A conductive layer 21 is also included between the BC bottom cell and the perovskite top cell.
[0044] In some specific embodiments, reference is made to Figure 7 and Figure 8 In the direction away from the bottom BC 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, an encapsulation film 26, and an electrode 27.
[0045] The conductive layer 21 and the transparent conductive layer 25 can be transparent conductive materials (TCOs), 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).
[0046] In some embodiments, one of the first charge transport layer 22 and the second charge transport layer 24 can be an electron transport layer, and the other can be a hole transport layer. In some embodiments, the hole transport layer is a self-assembled hole transport layer with a thickness of 0.5–2 nm, and the hole transport material includes [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACz), (4-(3,6-dimethyl-9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz), [4-(9H-carbazole-9-yl)butyl]phosphonic acid (4PACz), and (4-(3,6-dibromo-9H-carbazole-9-yl)butyl)phosphonic acid (Br-4PACz). At least one of Cz), [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz), (2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl)phosphonic acid (Me-2PACz), (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-dibromo-9H-carbazole-9-yl)ethyl)phosphonic acid (Br-2PACz), and [4-(7H-dibenzocarbazole-7-yl)butyl]phosphonic acid (4PADCB). The above-mentioned self-assembled hole transport material is anchored to the surface of the transparent electrode layer by a condensation reaction between the phosphonic acid groups in the molecule and the hydroxyl groups on the surface. Furthermore, the technical solution of this invention provides a better improvement effect on solar cells with self-assembled hole transport layers. In some other embodiments of this invention, the hole transport layer can also be a non-self-assembled hole transport layer, and its material may include nickel oxide (NiO). x, 1≤x≤2), cuprous iodide (CuI), cuprous oxide (Cu2O), cuprous thiocyanate (CuSCN), 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), 2,2',7,7'-tetratetra(di-p-tolylamino)spiro-9,9'-difluorene (Spiro-TTB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACz), (4-(3,6-dimethyl ... (4-(9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz), (4-(3,6-dibromo-9H-carbazole-9-yl)butyl)phosphonic acid (Br-4PACz), (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACz), (2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl)phosphonic acid (Me-2PACz), (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-dibromo-9H-carbazole-9-yl)ethyl)phosphonic acid (Br-2PACz), etc.
[0047] In some embodiments, the electron transport material of the electron transport layer includes, but is not limited to, tin oxide, fullerenes and their derivatives, imide compounds, quinone compounds, etc. Exemplarily, the imide compounds include at least one selected from phthalimide, succinimide, N-bromosuccinimide, glutarimide, or maleimide; exemplarily, the quinone compounds include at least one selected from 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 At least one of BM). 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 be a C60 layer with a thickness of 5-20 nm and a tin oxide layer with a thickness of 15-20 nm. The tin oxide layer can protect the C60 in subsequent processes.
[0048] In some embodiments, the material structure of the perovskite light-absorbing layer can be ABX3, wherein A is a monovalent cation, including but not limited to one or a mixture of several monovalent cations selected from cesium (Cs), rubidium (Rb), methylamino (CH3NH3), and formamidinyl (CH2(NH2)2); B is a divalent cation, including but not limited to one or a mixture of several divalent cations selected from lead (Pb) and tin (Sn); and X is a monovalent anion, including but not limited to one or a mixture of several monovalent anions selected from iodine (I), bromine (Br), chloride (Cl), fluorine (F), and thiocyanate (SCN). According to some embodiments of the present invention, the thickness of the perovskite light-absorbing layer is 500-700 nm, and the band gap is 1.3 to 3.0 eV.
[0049] In some embodiments, the encapsulation film may be made of metal oxides (such as aluminum oxide or silicon oxide), glass, or epoxy resin.
[0050] In some embodiments, the electrode material may be a silver electrode, an aluminum electrode, or the like.
[0051] In another aspect, this utility model provides a method for manufacturing the aforementioned three-terminal tandem solar cell. According to an embodiment of this utility model, the method for manufacturing a three-terminal tandem solar cell includes:
[0052] S100: Manufacturing BC-bottom batteries;
[0053] According to an embodiment of this utility model, a method for fabricating a BC-bottom solar cell includes: fabricating a textured area on the light-receiving surface of the BC-bottom solar cell, excluding the polished area, wherein a perovskite top solar cell is formed on the surface of the conductive layer in the polished area. Thus, by setting the perovskite top solar cell on a smooth and flat polished area, the smooth surface facilitates the fabrication of the perovskite light-absorbing layer and other layer structures, thereby contributing to obtaining a high-quality, high-performance perovskite top solar cell and improving the cell's manufacturing yield and efficiency. Furthermore, by using the textured area without the perovskite top solar cell as the textured surface of the BC-bottom solar cell, and by setting an anti-reflection film on the textured surface, the reflectivity can be effectively reduced when light is incident, thereby increasing the current of the BC-bottom solar cell. This results in both the perovskite top solar cell and the crystalline silicon BC-bottom solar cell having higher cell efficiency, thus comprehensively improving the overall efficiency of the three-terminal tandem solar cell.
[0054] According to some embodiments of this utility model, the BC battery includes a TBC battery, an HBC battery, or a hybrid BC battery. Those skilled in the art will understand that a TBC battery can be a conventional TBC battery, such as one where both the P-region and N-region have a topcon structure, or it can be an improved TBC battery, such as one where the P-region is directly fabricated on the silicon substrate without a topcon structure, while the N-region uses a topcon structure, thereby reducing costs and improving the passivation effect of the P-region. An HBC battery is a BC battery where both the P-region and N-region on the back side have an HJT structure. A hybrid BC battery refers to a BC battery where one of the P-regions and N-region on the back side has a topcon structure, and the other has an HJT structure. Furthermore, the BC bottom battery of this utility model can also be a BC battery structure from other conventional technologies. The following describes in detail the fabrication method of the BC bottom battery in a three-terminal tandem solar cell based on some specific embodiments:
[0055] In some embodiments, refer to Figure 9a and Figure 9b ( Figure 9a and Figure 9b (Taking only one perovskite top cell as an example, the fabrication of a BC bottom cell includes:)
[0056] S110: Provide a silicon substrate 110, polish the surface of the silicon substrate, and then deposit a tunnel oxide layer 113 on the backlight side.
[0057] S111: A P-type doped polysilicon layer 117 is deposited on the light-receiving side and the back-light-receiving side (or only on the back-light-receiving side) of the silicon substrate 110, and a borosilicate glass (BSG) 1170 is formed on the surface of the P-type doped polysilicon layer.
[0058] In some embodiments, the method for depositing the P-type doped polysilicon layer described above can be chemical vapor deposition (such as low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD)), and then annealing can be used to obtain the P-type doped polysilicon layer 117.
[0059] S112: By using a laser to remove borosilicate glass from a portion of the backlight surface, leaving only the borosilicate glass in the P area, the borosilicate glass can be patterned.
[0060] S113: Chain-type removal of borosilicate glass on the light-receiving surface, and groove-type removal of the P-type doped polysilicon layer 117 exposed after laser removal of the borosilicate glass on the back-lighting surface and the P-type doped polysilicon layer 117 on the light-receiving surface.
[0061] S114: An N-type doped polysilicon layer 1124 is deposited on the light-receiving surface and the back-light-receiving surface, and a layer of phosphosilicate glass (PSG) 11240 is formed on the surface of the N-type doped polysilicon layer 1124.
[0062] In some embodiments, the method for depositing the N-type doped polysilicon layer described above can be chemical vapor deposition (such as low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD)), and then annealing can be used to obtain the N-type doped polysilicon layer.
[0063] S115: The phosphorus silicate glass in a portion of the light-receiving surface is removed by laser, leaving only the polished area (i.e. the area where the perovskite top cell needs to be fabricated) of the phosphorus silicate glass on the light-receiving surface. The phosphorus silicate glass in the backlighting surface is removed by laser, leaving only the area where the second N-type doped polycrystalline silicon layer needs to be formed on the backlighting surface, thus achieving patterning of the phosphorus silicate glass.
[0064] S116: A grooved mill is used to texturize the area on the light-receiving surface where no perovskite top cell is set, and to texturize the area between the N-region and the P-region on the backlight surface. At the same time, the N-type doped polysilicon layer in the area on the light-receiving surface where no perovskite top cell is set is partially removed to obtain the first N-type doped polysilicon layer 112. The N-type doped polysilicon layer exposed by the phosphosilicate glass on the backlight surface is partially removed to obtain the second N-type doped polysilicon layer 114.
[0065] S117; Cleaning removes any remaining borosilicate glass and phosphosilicate glass.
[0066] S118: A first passivation layer 119 and an anti-reflection film 111 are sequentially deposited on the textured surface of the light-receiving side, and a second passivation layer 115 is deposited on the back-lighting side.
[0067] S119: Metallize and sinter on the back surface to obtain the first electrode 117 and the second electrode 118, thus obtaining the BC bottom cell.
[0068] It should be noted that the above manufacturing steps are only a specific embodiment of the manufacturing process. The order of some steps may be adjusted according to the actual situation, provided that the process conditions allow.
[0069] In other embodiments, reference is made to Figure 10 ( Figure 10 (Taking only one perovskite top cell as an example, the fabrication of a BC bottom cell includes:)
[0070] S120: Provide a P-type doped silicon substrate 101, polish the surface of the P-type doped silicon substrate, and then deposit a tunnel oxide layer 113 on the backlight side.
[0071] S121: A polished surface region needs to be formed in the light-receiving surface of the P-type doped silicon substrate 101 for N-type heavy doping, resulting in an N-type heavy doped layer 1100.
[0072] S122: An N-type doped polysilicon layer 1124 is deposited on the light-receiving surface and the back-lighting surface (or only on the back-lighting surface) of a P-type doped silicon substrate 101, and a layer of phosphosilicate glass (PSG) 11240 is formed on the surface of the N-type doped polysilicon layer 1124.
[0073] In some embodiments, the method for depositing the N-type doped polysilicon layer 1124 described above can be chemical vapor deposition (such as low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD)), and then annealing can be used to obtain the N-type doped polysilicon layer 1124.
[0074] S123: The back phosphorus glass is patterned by removing a portion of the phosphorus glass on the back surface using a laser, leaving only the phosphorus glass in the N region; at the same time, the back phosphorus glass is patterned by removing a portion of the phosphorus glass on the light-receiving surface using a laser, leaving only the phosphorus glass in the area directly above the N-type heavily doped layer 1100.
[0075] S124: The N-type doped polysilicon layer 1124 exposed by the phosphate silicon glass on the light-receiving surface and the backlight surface is removed by the groove. A first N-type doped polysilicon layer 112 is obtained on the light-receiving surface and a second N-type doped polysilicon layer 114 is obtained on the backlight surface. Texturing is performed on the surface of the light-receiving surface where a textured surface needs to be formed, and texturing is performed on the P-region of the backlight surface.
[0076] S125; Cleaning removes any remaining phosphosilicate glass.
[0077] S126: A first passivation layer 119 and an anti-reflection film 111 are sequentially deposited on the textured surface of the light-receiving side, and a second passivation layer 115 is deposited on the back-lighting side.
[0078] S127: Metallize and sinter on the back surface to obtain the first electrode 117 and the second electrode 118, thus obtaining a BC bottom cell.
[0079] It should be noted that the above manufacturing steps are only a specific embodiment of the manufacturing process. The order of some steps may be adjusted according to the actual situation, provided that the process conditions allow.
[0080] S200: At least one perovskite top cell is fabricated 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.
[0081] According to some embodiments of this utility model, there are no special requirements for the structure of the perovskite top cell. Those skilled in the art can flexibly select a suitable perovskite cell structure based on existing technical means.
[0082] In some specific embodiments, reference is made to Figure 7 and Figure 8 In the direction away from the bottom BC 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, an encapsulation film 26, and an electrode 27.
[0083] According to some embodiments of this utility model, refer to Figure 7 and Figure 8 Before fabricating the perovskite top cell, a conductive layer 21 is formed on the polished surface region of the BC bottom cell (i.e., the surface of the first N-type doped polycrystalline silicon layer 112) to connect the bottom cell and the top cell.
[0084] In some embodiments, a method for fabricating a perovskite top cell (taking an inverted perovskite structure as an example) includes:
[0085] S210: A hole transport layer (i.e., the first charge transport layer 22) is formed on the side of the conductive layer 21 away from the BC bottom cell using a solution method or vapor deposition method.
[0086] In some specific embodiments, the solution method can be spin coating, spray coating, printing, or other methods.
[0087] S220: A perovskite light-absorbing layer 23 is formed on the side of the hole transport layer away from the bottom of the BC cell.
[0088] In some specific embodiments, the method of forming the perovskite light-absorbing layer 23 may include: coating a perovskite precursor solution onto 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.
[0089] S230: An electron transport layer (i.e., a second charge transport layer 24) is formed on the side of the perovskite light-absorbing layer 23 away from the bottom of the BC cell.
[0090] In some specific embodiments, single-layer or multi-layer electron transport layers can be prepared by vacuum evaporation and atomic deposition.
[0091] S240: A transparent conductive layer 25 is formed on the side of the electron transport layer away from the bottom of the BC battery.
[0092] S250: An encapsulation film 26 and an electrode 27 are formed on the side of the transparent conductive layer 25 away from the BC bottom cell.
[0093] In some specific embodiments, electrode 27 can be prepared by thermal evaporation or screen printing.
[0094] 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. Those skilled in the art can flexibly set them according to existing technical means and common knowledge, and no restrictions are imposed here.
[0095] According to embodiments of this invention, in the above-described preparation method, by forming a relatively small perovskite top cell, the short-wavelength absorption advantage of the perovskite top cell is fully utilized while increasing the area of the BC bottom cell's light-receiving surface that can directly absorb light (i.e., the area of the BC bottom cell's light-receiving surface without the perovskite top cell). When light is incident, the reflectivity is reduced, increasing the current of the BC bottom cell, thereby contributing to improved photoelectric conversion efficiency. Furthermore, a certain polished surface area is retained on the light-receiving surface of the BC bottom cell, and the perovskite top cell is formed in this polished area. The smooth surface facilitates the preparation of the perovskite light-absorbing layer and other layer structures, thus contributing to obtaining a high-quality, high-performance perovskite top cell and improving the cell's manufacturing yield and efficiency. Moreover, the textured surface area without the perovskite top cell is used as the textured surface of the BC bottom cell. After setting an anti-reflection film on the textured surface, the reflectivity is effectively reduced when light is incident, thereby increasing the current of the BC bottom cell. This results in both the perovskite top cell and the crystalline silicon BC bottom cell having higher cell efficiencies, thus comprehensively improving the overall efficiency of the three-terminal tandem solar cell.
[0096] In another aspect, this utility model provides a photovoltaic module. According to an embodiment of this utility model, the photovoltaic module includes the three-terminal tandem solar cell described above. Therefore, this photovoltaic module has better cell efficiency and stability. Those skilled in the art will understand that this photovoltaic module possesses all the features and advantages of the three-terminal tandem solar cell described above, and will not be elaborated further here.
[0097] Example
[0098] The fabrication method for a three-terminal tandem solar cell includes:
[0099] An N-type doped silicon substrate is provided, and the surface of the N-type doped silicon substrate is polished. Then, a tunnel oxide layer with a thickness of 1.9 nm is deposited on the back surface by LPCVD. The deposition temperature is 610℃ and the time is 680s.
[0100] Amorphous silicon layers were deposited on the light-receiving and back-light-receiving surfaces of a silicon substrate using LPCVD at 550°C for 8000 s, resulting in an amorphous silicon thickness of 360 nm. Following the LPCVD process, a boron diffusion process was performed, crystallizing at 960°C for 5000 s to convert the amorphous silicon to a polycrystalline state. Diffusion was then carried out at 830°C for 700 s, followed by a further diffusion at 960°C for 500 s to obtain a P-type doped polycrystalline silicon layer. This layer was then oxidized at 960°C for 1200 s to form a borosilicate glass (BSG) layer on its surface.
[0101] The borosilicate glass on the back side is removed by laser, leaving only the borosilicate glass in the P-region, thus achieving patterning of the borosilicate glass. The laser wavelength is 532nm, the pulse duration is 1μs, the pulse energy is 90μJ, and the frequency is 550kHz.
[0102] The borosilicate glass on the front side is removed by a chain process (the acid solution is composed of HF and H2O in a volume ratio of 3:2, the pickling time is 40s, and the acid solution temperature is 30℃). The P-type doped polycrystalline silicon layer exposed after the laser removal of the borosilicate glass on the back side and the P-type doped polycrystalline silicon layer on the front side are removed by a tank process (the alkaline polishing tank temperature is 60℃, the process time is 450s, and the alkaline solution is composed of H2O, NaOH, and texturing additives in a volume ratio of 300:12:5, where the NaOH concentration is about 3%).
[0103] An amorphous silicon layer was formed by LPCVD at a temperature of 610℃ for 3500s, resulting in an amorphous silicon layer thickness of 280nm. Then, a phosphorus diffusion process was performed, with diffusion at 860℃ for 1550s and then at 880℃ for 400s, depositing a 280nm thick N-type doped polycrystalline silicon layer on both the light-receiving and back-light-receiving surfaces. Finally, the surface of the N-type doped polycrystalline silicon layer was oxidized at 900℃ for 600s to form a 50nm thick phosphosilicate glass (PSG).
[0104] The phosphosilicate glass is patterned by removing a portion of the front side area using a laser, leaving only the second area (the area where the perovskite top cell needs to be fabricated) of the phosphosilicate glass on the front side. The phosphosilicate glass on the back side is also removed by laser, leaving only the area where the second N-type doped polycrystalline silicon layer needs to be formed on the back side. The laser conditions are: wavelength 532nm, pulse 1μs, pulse energy 90μJ, and frequency 500kHz.
[0105] A wet alkaline texturing tank is used to texturize the area on the front side where no perovskite top cell is set, and to texturize the area between the N-region and P-region on the back side. At the same time, the N-type doped polycrystalline silicon layer in the area on the front side where no perovskite top cell is set is partially removed to obtain the first N-type doped polycrystalline silicon layer. The N-type doped polycrystalline silicon layer exposed by the phosphosilicate glass on the back side is partially removed to obtain the second N-type doped polycrystalline silicon layer.
[0106] The remaining borosilicate glass and phosphosilicate glass were removed by cleaning in a wet acid bath (acid bath temperature of 40℃, time of 120s, acid solution of H2O and HF in a volume ratio of 3:2).
[0107] On the textured surface of the light-receiving side, a 4 nm aluminum oxide passivation layer is deposited using atomic layer deposition (ALD). Then, 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 are sequentially deposited using PECVD to obtain an antireflection film with a total thickness of 70-85 nm and a refractive index of 2.1. On the backlight side, 20 nm silicon nitride 1, 29 nm silicon nitride 2, and 35 nm silicon nitride are sequentially deposited using PECVD to obtain a passivation layer.
[0108] Metallization and sintering are performed on the backlight surface to obtain the first electrode-silver electrode and the second electrode-silver electrode, thereby obtaining the BC-bottom battery. The structural schematic diagram is shown below. Figure 5 As shown;
[0109] A TCO conductive layer with a thickness of 15 nm is deposited on the surface of the first N-type doped polycrystalline silicon layer on the front side of the BC bottom cell.
[0110] Me-4PACZ solution was coated on the surface of the conductive layer and then annealed at 100℃ for 10 min to obtain a self-assembled monomolecular hole transport layer.
[0111] A perovskite precursor solution was dropped onto the surface of the hole transport layer and spin-coated at 2000 rpm for 30 seconds. Immediately after spin-coating, the battery substrate was placed on a hot plate at 100°C for annealing for 10 minutes to allow the perovskite crystals to fully crystallize and form a perovskite light-absorbing layer with a thickness of 600 nm. The preparation method of the perovskite precursor solution included: weighing methylamine lead iodide (CH3NH3PbI3), chlorobenzamine lead iodide (C6H5CH2NH3PbI3), and cesium bromide (CsBr) in a molar ratio of 1:1:1, and dissolving them in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) with a volume ratio of DMF to DMSO of 4:1 to prepare a perovskite precursor solution with a concentration of 0.1.5 M. The solution was stirred in a glove box for about 12 hours to ensure that the solute was fully dissolved.
[0112] A 15 nm thick C60 layer was obtained by vacuum evaporation on the surface of the perovskite light-absorbing layer, and then an 8 nm thick tin oxide layer was deposited by ALD to obtain the electron transport layer.
[0113] A 50 nm thick ITO layer was deposited on the surface of the electron transport layer by magnetron sputtering.
[0114] A silver electrode with a thickness of 100 nm was deposited on the surface of the ITO layer by thermal evaporation, wherein the silver evaporation rate was 0.1 nm / s;
[0115] An encapsulation film was fabricated to obtain a square perovskite top cell.
[0116] The area of the light-receiving surface of the BC bottom cell is 182mm*210mm, and the area of a single perovskite top cell is 10mm*10mm. Multiple perovskite top cells are uniformly arrayed on the light-receiving surface of the BC bottom cell, so that the ratio of the area of the perovskite top cell to the area of the light-receiving surface of the BC bottom cell is 0.3 to 0.5.
[0117] Using the same fabrication process, the overall performance of three-terminal tandem solar cells with different numbers of perovskite top cells on the same size bottom cell was evaluated. 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 overall performance of the tandem solar cell is optimal. The overall performance takes into account factors such as the difficulty of adapting the top and bottom cells, the cell conversion efficiency, and the ease of fabrication.
[0118] The terms "first" and "second" used in this document are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature marked "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0119] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0120] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled 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 tandem solar cell, characterized in that, include: BC bottom battery; At least one perovskite top cell, wherein at least one of the perovskite top cells is disposed 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.
2. The three-terminal tandem solar cell according to claim 1, characterized in that, The 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.
3. The three-terminal tandem solar cell according to claim 1, characterized in that, It includes multiple perovskite top cells, and the multiple perovskite top cells are spaced apart.
4. The three-terminal tandem solar cell according to any one of claims 1 to 3, characterized in that, The BC bottom battery includes TBC batteries, HBC batteries, or hybrid BC batteries.
5. The three-terminal tandem solar cell according to claim 4, characterized in that, The light-receiving surface of the BC bottom cell includes a textured area and at least one polished area, and the perovskite top cell is located in the polished area.
6. The three-terminal tandem solar cell according to claim 3, characterized in that, The perovskite top cells are arranged symmetrically, and / or the shape of the perovskite top cells includes at least one of square, circular, elliptical, triangular, pentagonal, and hexagonal.
7. The three-terminal tandem solar cell according to claim 5, characterized in that, The BC bottom battery includes: A silicon substrate having a light-receiving surface and a back-lighting surface disposed opposite to each other, the back-lighting surface having N-regions and P-regions disposed at intervals, and the light-receiving surface having a textured surface and a polished surface; A first passivation layer is disposed on the textured surface of the silicon substrate; An antireflective coating is disposed on the side of the first passivation layer away from the silicon substrate; A first N-type doped polysilicon layer is disposed on the polished surface of the silicon substrate; In the 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 the direction away from the silicon substrate, the P region is sequentially provided with the tunneling layer, the P-type doped polysilicon layer, the second passivation layer, and the second electrode.
8. The three-terminal tandem solar cell according to claim 5, characterized in that, The BC bottom battery includes: The P-type doped silicon substrate has a light-receiving surface and a back-lighting surface arranged opposite to each other. The back-lighting surface has N-regions and P-regions. The light-receiving surface has a textured surface and a polished surface. A first passivation layer is disposed on the textured surface of the P-type doped silicon substrate; An antireflective coating is disposed on the side of the first passivation layer away from the P-type doped silicon substrate; An N-type heavily doped layer is disposed on the polished surface; A first N-type doped polysilicon layer is disposed on the side of the heavily doped N-type layer away from the P-type doped silicon substrate; In the 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 the direction away from the P-type doped silicon substrate, the P region is sequentially provided with the second passivation layer and the second electrode, and the P region has a textured surface.
9. The three-terminal tandem solar cell according to claim 5, characterized in that, A conductive layer is also included between the BC bottom cell and the perovskite top cell.
10. A photovoltaic module, characterized in that, The three-terminal tandem solar cell includes any one of claims 1 to 9.