Back contact laminated solar cell and cell module

Abstract

The invention relates to the technical field of solar cells, and discloses a back contact laminated solar cell and a cell module. The cell comprises a substrate layer, a first carrier transport layer, a second carrier transport layer, a first light absorption layer and / or a second light absorption layer, a first electrode and a second electrode, wherein the substrate layer comprises a light receiving surface and a backlight surface; the first carrier transport layer is arranged in the first area of the backlight surface; the second carrier transport layer is arranged in the second region; the first light absorption layer with the band gap width larger than that of the substrate layer is arranged on the light receiving surface; the second light absorption layer with the band gap width smaller than that of the substrate layer is arranged on the backlight face, the first electrode is connected with the first carrier transmission layer, and the second electrode is connected with the second carrier transmission layer. The first light absorption layer and the second light absorption layer can be arranged on the light receiving face and the backlight face respectively, band gaps are gradually decreased from top to bottom, absorption of light of different wave bands can be enhanced, and the photoelectric conversion efficiency and the power generation performance are improved.

Description

Back-contact tandem solar cells and modules Technical Field

[0001] This disclosure relates to the field of solar cell technology, specifically to back-contact tandem solar cells and cell modules. Background Technology

[0002] Back-contact technology places the front-side grid electrodes on the back of the cell, avoiding light loss due to grid shading. This allows for full absorption of incident light, resulting in a theoretical maximum efficiency of 29.1%, making it the closest single-junction cell technology to the theoretical limit (~29.56%). Further applications of back-contact solar cells primarily utilize three cell structures: TBC, HBC, and HTBC.

[0003] The TBC cell structure integrates the tunneling oxide / doped polycrystalline silicon passivation contact technology of TOPCon cells with the back contact solar cell structure; the HBC cell structure integrates the intrinsic amorphous silicon / doped amorphous silicon passivation contact technology of HJT cells with the back contact solar cell structure; the HTBC cell structure combines the tunneling oxide / doped polycrystalline silicon passivation contact technology of TOPCon cells with the intrinsic amorphous silicon / doped amorphous silicon passivation contact technology of HJT cells in different polarity regions preset on the back surface, respectively, to minimize gold / semiconductor contact recombination while ensuring that optical performance is not reduced, thereby obtaining the best cell performance.

[0004] However, the aforementioned TBC, HBC, and HTBC battery structures all require additional vacuum equipment, which undoubtedly increases investment costs and slows down their mass production progress. More importantly, the photoelectric conversion efficiency and power generation performance of these battery structures are approaching their limits, and how to further improve their photoelectric conversion efficiency and power generation performance has become one of the urgent problems to be solved. Summary of the Invention

[0005] This disclosure provides a back-contact tandem solar cell and cell module to solve the problem that the photoelectric conversion efficiency and power generation performance of existing solar cells are difficult to improve further, and the mass production process is slow.

[0006] In a first aspect, this disclosure provides a back-contact tandem solar cell, comprising: a substrate layer, a first carrier transport layer, a second carrier transport layer, a first light-absorbing layer and / or a second light-absorbing layer, a first electrode, and a second electrode. The substrate layer includes a light-receiving surface and a back-lighting surface disposed opposite to each other. The back-lighting surface includes alternating first and second regions. The first carrier transport layer is disposed in the first region of the back-lighting surface. The second carrier transport layer is disposed in the second region of the back-lighting surface, and the first and second carrier transport layers have opposite conductivity types. The first light-absorbing layer is disposed on the light-receiving surface of the substrate layer, and the band gap width of the first light-absorbing layer is greater than the band gap width of the substrate layer. The second light-absorbing layer is adapted to be disposed on at least a portion of the back-lighting surface of the substrate layer, and the first and second carrier transport layers are disposed on the second light-absorbing layer, with the band gap width of the second light-absorbing layer being smaller than the band gap width of the substrate layer. The first electrode is connected to the first carrier transport layer, and the second electrode is connected to the second carrier transport layer.

[0007] Beneficial effects: This disclosure includes a first light-absorbing layer with a bandgap width greater than that of the substrate on the light-receiving surface of the substrate, and / or a second light-absorbing layer with a bandgap width smaller than that of the substrate on the back-lighting surface of the substrate. The first light-absorbing layer helps to enhance the absorption of short-wavelength light on the light-receiving side, and the second light-absorbing layer enhances the absorption of long-wavelength light on the back-lighting side. This can form a double-layer structure from top to bottom, consisting of a first light-absorbing layer and a substrate, a double-layer structure of the substrate and a second light-absorbing layer, and a three-layer structure with the bandgap width decreasing sequentially from the first light-absorbing layer to the substrate and the second light-absorbing layer. Compared with a single-layer light-absorbing layer, such a multi-layer structure can further enhance the absorption and conversion of light of different wavelengths, greatly improving the power generation efficiency of the battery. In other words, when external sunlight strikes the light-receiving side of the battery, it first passes through the first light absorption layer with a relatively large band gap to fully absorb short-wavelength light; then it enters the crystalline silicon material of the substrate layer with a smaller band gap to further absorb mid-wavelength light; and then it can pass through the second light absorption layer with an even smaller band gap to absorb long-wavelength light. Ultimately, this enhances the battery's utilization of incident sunlight of different wavelengths, improving photoelectric conversion efficiency and power generation performance.

[0008] Moreover, compared to conventional two-, three-, or four-terminal tandem solar cells, the solar cell disclosed in this invention features a back-contact structure, reducing front-side shading. Furthermore, the upper surface of the bottom cell directly stacks a first light-absorbing layer, and the lower surface directly forms a second light-absorbing layer, eliminating the need for an additional carrier transport layer. In other words, the back-contact solar cell of this invention directly forms a first light-absorbing layer with a bandgap wider than the bandgap of the crystalline silicon material and a second light-absorbing layer with a bandgap narrower than the bandgap of the crystalline silicon material on the surface of the back-contact crystalline silicon bottom cell, providing a new approach for the application of tandem solar cells and back-contact solar cells.

[0009] In one alternative embodiment, the first light-absorbing layer includes a wide-bandgap perovskite light-absorbing layer with a bandgap width greater than that of the substrate, and / or the second light-absorbing layer includes a narrow-bandgap perovskite light-absorbing layer with a bandgap width less than that of the substrate.

[0010] Beneficial effects: In this disclosure, the first light-absorbing layer is a perovskite material layer with a band gap wider than that of the crystalline silicon material in the substrate layer, i.e., a wide-bandgap perovskite light-absorbing layer. Furthermore, by adjusting the composition or proportion of the perovskite material, the overall band gap width of the material can be changed to absorb more short-wavelength light. The second light-absorbing layer is a perovskite material layer with a band gap narrower than that of the crystalline silicon material in the substrate layer, i.e., a narrow-bandgap perovskite light-absorbing layer. Similarly, the overall band gap width can be changed by adjusting the composition or proportion of the perovskite material, thus forming a back-contact tandem solar cell with a top wide-bandgap perovskite light-absorbing layer, a middle crystalline silicon light-absorbing layer, and a bottom narrow-bandgap perovskite light-absorbing layer, providing a new solution for overcoming the power bottleneck of tandem solar cells.

[0011] In one optional embodiment, the first light-absorbing layer includes a single-layer first photoactive layer; or the first light-absorbing layer includes multiple stacked first photoactive layers, with the band gap width of the multiple first photoactive layers gradually decreasing along the incident direction of sunlight; the second light-absorbing layer includes a single-layer second photoactive layer; or the second light-absorbing layer includes multiple stacked second photoactive layers, with the band gap width of the multiple second photoactive layers gradually decreasing along the incident direction of sunlight.

[0012] Beneficial effects: Setting a single-layer first photoactive layer in the first light absorption layer helps to achieve the initial capture of short-wavelength light and ensure the stability of long-wavelength light absorption; alternatively, setting multiple first photoactive layers with gradually decreasing band gaps can further achieve the absorption of short-wavelength light in different bands. Similarly, setting a single-layer second photoactive layer in the second light absorption layer helps to achieve the initial capture of long-wavelength light and ensure the stability of long-wavelength light absorption; alternatively, setting multiple second photoactive layers with gradually decreasing band gaps can further achieve the absorption of long-wavelength light in different bands, further improving the capture and absorption of light across the entire wavelength range, and greatly enhancing photoelectric conversion efficiency and power generation efficiency.

[0013] In one optional embodiment, it further includes: a first interconnect layer disposed between the light-receiving surface of the first light-absorbing layer and the substrate layer, and / or the first interconnect layer disposed between adjacent photoactive layers; and / or a second interconnect layer located between the backlight surface of the second light-absorbing layer and the substrate layer, and / or the second interconnect layer disposed between adjacent second photoactive layers.

[0014] Beneficial effects: The first interconnect layer helps enhance the carrier transport efficiency and conduction effect between the light-receiving surfaces of the first light-absorbing layer and the substrate layer, as well as between different first photoactive layers of the first light-absorbing layer. The second interconnect layer helps enhance the carrier transport efficiency between the substrate layer and the first and second carrier transport layers, or enhances the carrier transport efficiency and conduction effect between the second light-absorbing layer and the substrate layer, as well as between different second photoactive layers of the second light-absorbing layer.

[0015] In one optional embodiment, a functional composite layer is further included, disposed on the first light absorption layer; the functional composite layer includes a passivation layer and / or an antireflection layer, wherein the passivation layer is adapted to be disposed on the first light absorption layer, and the antireflection layer is adapted to be disposed on the passivation layer.

[0016] Beneficial effects: The passivation layer can be made of aluminum oxide and / or silicon nitride, enhancing the passivation contact between the light-receiving surface of the first light-absorbing layer or substrate and a film layer such as an anti-reflection layer disposed on the passivation layer, thereby reducing surface recombination efficiency. The anti-reflection layer can be a TCO material layer, reducing light reflection of incident sunlight and increasing light absorption. Furthermore, a functional composite layer disposed on the surface of the first light-absorbing layer relatively far from the substrate layer also helps to protect the first light-absorbing layer.

[0017] In one alternative embodiment, the functional composite layer is further provided extending from the edge of the light-receiving surface toward the edge of the backlighting surface.

[0018] Beneficial effects: The functional composite layer on the outermost side of the battery's light-receiving surface also covers part of the battery's side surface, such as the sidewall of the first light-absorbing layer, or continues to cover the sidewall of the substrate layer, to ensure the performance of the water vapor-sensitive perovskite first light-absorbing layer.

[0019] In one optional embodiment, the first carrier transport layer includes one or more of a doped polycrystalline silicon layer, a doped amorphous silicon layer, and a charge transport layer of a perovskite solar cell; the second carrier transport layer includes one or more of a doped polycrystalline silicon layer, a doped amorphous silicon layer, and a charge transport layer of a perovskite solar cell; the charge transport layer of the perovskite solar cell includes a hole transport layer or an electron transport layer.

[0020] Beneficial effects: With the first light absorption layer set on the light-receiving side of the battery substrate, the first and second carrier transport layers on the backlight side can adopt carrier transport structures of different battery types and be used in different process requirements and scenarios.

[0021] In an optional embodiment, when the first carrier transport layer includes a charge transport layer of doped amorphous silicon or a perovskite cell, and the second carrier transport layer includes a charge transport layer of doped amorphous silicon or a perovskite cell, the embodiment further includes: a first transparent conductive layer disposed on the side surface of the first carrier transport layer away from the substrate layer, and a first electrode connected to the first transparent conductive layer; and a second transparent conductive layer disposed on the side surface of the second carrier transport layer away from the substrate layer, and a second electrode connected to the second transparent conductive layer.

[0022] Beneficial effects: The first transparent conductive layer and the second transparent conductive layer respectively cover the lower surface of the first carrier transport layer and the lower surface of the second carrier transport layer, thereby achieving efficient carrier transport between the carrier transport layer and the electrode.

[0023] In one alternative embodiment, an isolation groove is formed between the first carrier transport layer and the second carrier transport layer; the first transparent conductive layer further extends laterally to cover at least a portion of the bottom surface of the isolation groove, and / or the second transparent conductive layer further extends laterally to cover at least a portion of the bottom surface of the isolation groove.

[0024] Beneficial effects: When an isolation groove is formed between the first and second carrier transport layers, the first transparent conductive layer extends laterally to cover at least a portion of the bottom surface of the isolation groove, and the second transparent conductive layer also extends laterally to cover at least a portion of the bottom surface of the isolation groove. On the one hand, the extended first and second transparent conductive layers can achieve omnidirectional carrier transport; on the other hand, the extended first and second transparent conductive layers can also effectively protect the second light-absorbing layer, ensuring the performance of the perovskite material layer.

[0025] Secondly, this disclosure also provides a back-contact tandem solar cell module, comprising: a plurality of the aforementioned back-contact tandem solar cells.

[0026] Beneficial effects: The back-contact tandem solar cell disclosed herein includes: a crystalline silicon substrate layer and a first light-absorbing layer covering the light-receiving side of the crystalline silicon substrate layer and / or a second light-absorbing layer covering the back-light-receiving side of the crystalline silicon substrate layer, wherein the band gap width of the first light-absorbing layer is greater than the band gap width of the substrate layer, and the band gap width of the second light-absorbing layer is less than the band gap width of the substrate layer. When sunlight strikes the light-receiving side of the cell, it first passes through a first light-absorbing layer with a relatively large bandgap, achieving full absorption of short-wavelength light. Then, it enters the crystalline silicon material of the substrate layer with a smaller bandgap, further absorbing mid-wavelength light. Afterward, it can enter a second light-absorbing layer with an even smaller bandgap, absorbing long-wavelength light. Ultimately, this enhances the cell's utilization of incident sunlight of different wavelengths, improving the cell's photoelectric conversion efficiency and power generation performance. This can form a back-contact tandem solar cell with a top wide-bandgap perovskite light-absorbing layer, a middle crystalline silicon light-absorbing layer, and a bottom narrow-bandgap perovskite light-absorbing layer. This provides a new solution for breaking through the power bottleneck of tandem cells and cell modules. Cell modules formed by such cells have extremely high prospects for mass production applications. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 is a schematic diagram of a back-contact tandem solar cell according to an embodiment of the present disclosure, wherein a first light-absorbing layer is provided on the light-receiving surface and a carrier transport layer of the TOPCcon cell type is provided on one side of the back-lighting surface; Figure 2 is a schematic diagram of a back-contact tandem solar cell according to an embodiment of the present disclosure, wherein a first light-absorbing layer is provided on the light-receiving surface and an HJT cell type carrier transport layer is provided on one side of the back-lighting surface; Figure 3 is a schematic diagram of a back-contact tandem solar cell according to an embodiment of the present disclosure, wherein a first light-absorbing layer is provided on the light-receiving surface and a perovskite cell type carrier transport layer is provided on one side of the back-lighting surface; Figure 4 is a schematic diagram of a back-contact tandem solar cell according to an embodiment of the present disclosure, wherein a first light-absorbing layer is provided on the light-receiving surface and... Figure 5 is a schematic diagram of a back-contact tandem solar cell with an HJT cell-type carrier transport layer and a perovskite cell-type carrier transport layer integrated on one side of the backlight surface; Figure 6 is a schematic diagram of a back-contact tandem solar cell with a first light-absorbing layer on the light-receiving surface and a second light-absorbing layer on the backlight surface, and a perovskite cell-type carrier transport layer on one side of the backlight surface; Figure 7 is a schematic diagram of a back-contact tandem solar cell with the second light-absorbing layer covering the entire backlight surface according to an embodiment of the present disclosure. Figure 8 is a schematic diagram of the structure of a back-contact tandem solar cell according to an embodiment of the present disclosure, wherein a first interconnect layer is disposed between the light-receiving surface and the first light-absorbing layer; Figure 9 is a schematic diagram of the structure of a back-contact tandem solar cell according to an embodiment of the present disclosure, wherein the first light-absorbing layer includes multiple first photoactive layers; Figure 10 is a schematic diagram of the structure of a back-contact tandem solar cell according to an embodiment of the present disclosure, wherein a second interconnect layer is directly disposed between the back-lighting surface and the first carrier transport layer and the second carrier transport layer when the second light-receiving surface is not disposed; Figure 11 is a schematic diagram of the structure of a back-contact tandem solar cell according to an embodiment of the present disclosure, wherein a second light-receiving layer is disposed between the back-lighting surface and the second light-absorbing layer; Figure 12 is a schematic diagram of a back-contact tandem solar cell with a second interconnect layer between the layers in an embodiment of this disclosure. It shows the structure of the back-contact tandem solar cell where a carrier transport layer of type HJT cell and a carrier transport layer of type perovskite cell are integrated on one side of the back surface, with only a second interconnect layer between the carrier transport layer of type perovskite cell and the substrate layer. Figure 13 is a schematic diagram of a back-contact tandem solar cell where the first transparent conductive layer and the second transparent conductive layer extend to the bottom surface of the isolation groove portion in an embodiment of this disclosure. Figure 14 is a schematic diagram of a conventional back-contact solar cell. Figure 15 is a schematic diagram of a conventional tandem solar cell.

[0029] Explanation of reference numerals in the attached figures: 1. Substrate layer; 101. Light-receiving surface; 102. Backlight-receiving surface; A. First region; B. Second region; 2. First carrier transport layer; 201. n-type doped polycrystalline silicon layer; 201a. First tunneling oxide layer; 202. n-type doped amorphous silicon layer; 202a. First intrinsic amorphous silicon layer; 203. Electron transport layer; 3. Second carrier transport layer; 301. p-type doped polycrystalline silicon layer; 301a. Second tunneling oxide layer; 302. p-type doped amorphous silicon layer; 302a. Second intrinsic amorphous silicon layer ; 303, Hole transport layer; C, Isolation groove; 4, First light absorption layer; 401, First photoactive layer; 5, Second light absorption layer; 601, First electrode; 602, Second electrode; 7, First interconnect layer; 8, Second interconnect layer; 9, Functional composite layer; 10, Transparent conductive layer; 1001, First transparent conductive layer; 1002, Second transparent conductive layer; 1003, Spacer space; 100, Bottom cell; 11, Substrate; 12, Doped layer; 13, Passivation antireflection layer; 200, Interconnect layer; 300, Top cell. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0031] Among related technologies, TBC, HBC, and HTBC battery structures require additional vacuum equipment in their fabrication processes compared to conventional back-contact solar cells, increasing investment costs and hindering their mass production. More importantly, the photoelectric conversion efficiency and power generation performance of these battery structures are approaching their limits, making it crucial to further improve their photoelectric conversion efficiency and power generation performance one of the most pressing issues to be addressed.

[0032] In recent years, perovskite thin film materials have been widely used in the field of solar cells, and the development momentum of perovskite thin film batteries is very strong. This is not only due to their low manufacturing cost, but also because of the high passivation performance of their electron transport layer 203 and hole transport layer 303, resulting in high photoelectric conversion efficiency of the fabricated cells. Moreover, the theoretical efficiency of tandem cells formed by combining perovskite thin film solar cells with crystalline silicon solar cells can reach 46%, which points to a research and development direction for further development of solar cell technology.

[0033] Based on this, as shown in Figures 1 to 13, embodiments of this disclosure provide a back-contact tandem solar cell, comprising: a substrate layer 1, a first carrier transport layer 2, a second carrier transport layer 3, a first light absorption layer 4 and / or a second light absorption layer 5, a first electrode 601, and a second electrode 602. The substrate layer 1 includes a light-receiving surface 101 and a back-lighting surface 102 disposed opposite to each other. The back-lighting surface 102 includes an alternately spaced first region A and a second region B. The first carrier transport layer 2 is disposed in the first region A of the back-lighting surface 102; the second carrier transport layer 3 is disposed in the second region B of the back-lighting surface 102. In domain B, the first carrier transport layer 2 and the second carrier transport layer 3 have opposite conductivity types; the first light absorption layer 4 is disposed on the light-receiving surface 101 of the substrate layer 1, and the band gap width of the first light absorption layer 4 is greater than the band gap width of the substrate layer 1; the second light absorption layer 5 is adapted to be disposed on at least a portion of the backlight surface 102 of the substrate layer 1, the first carrier transport layer 2 and the second carrier transport layer 3 are disposed on the second light absorption layer 5, and the band gap width of the second light absorption layer 5 is less than the band gap width of the substrate layer 1; the first electrode 601 is connected to the first carrier transport layer 2, and the second electrode 602 is connected to the second carrier transport layer 3.

[0034] The aforementioned substrate 1 can be a silicon substrate. The light-receiving surface 101 of the substrate 1 is used to directly receive sunlight, while the back-lighting surface 102 is divided into an alternately arranged first region A and a second region B. The first region A is provided with a first carrier transport layer 2, and the second region B is provided with a second carrier transport layer 3. Of the first carrier transport layer 2 and the second carrier transport layer 3, one of them is mainly used to transport hole carriers and has a p-type conductivity, while the other is mainly used to transport electron carriers and has an n-type conductivity. In this disclosure, the first carrier transport layer 2 is mainly used to transport electron carriers, and the second carrier transport layer 3 is mainly used to transport hole carriers as an example. In this disclosure, a first light-absorbing layer 4 with a bandgap width greater than that of the substrate 1 is provided on the light-receiving surface 101 of the substrate 1 to enhance the utilization rate of short-wavelength sunlight on the light-receiving surface 101 side; a second light-absorbing layer 5 with a bandgap width smaller than that of the substrate 1 can also be provided on the back-lighting surface 102 side to enhance the utilization rate of long-wavelength light on the back-lighting surface 102 side. The larger the bandgap width, the more short-wavelength light is absorbed, forming a three-layer structure in which the bandgap widths of the first light-absorbing layer 4, the substrate 1, and the second light-absorbing layer 5 decrease sequentially from top to bottom, as shown in Figures 6 and 7. Compared with the superposition of single or double light-absorbing layers, this three-layer structure can maximize the absorption and conversion of light of different wavelengths, greatly improving the power generation efficiency of the battery. In other words, when external sunlight strikes the light-receiving surface 101 of the battery, it first passes through the first light-absorbing layer 4, which has a relatively large bandgap, to fully absorb short-wavelength light. Then, it enters the crystalline silicon material of the substrate layer 1, which has a smaller bandgap, to further absorb mid-wavelength light. Afterward, it passes through the second light-absorbing layer 5, which has the smallest bandgap, to absorb long-wavelength light. This ultimately enhances the battery's utilization of incident sunlight of different wavelengths, improving photoelectric conversion efficiency and power generation performance. The materials of the first light-absorbing layer 4 and the second light-absorbing layer 5 can be perovskite or other materials, as long as they meet the bandgap requirements.

[0035] Of course, in other embodiments, the first light absorption layer 4 may be provided only on the light-receiving surface 101 side of the substrate 1, and the second light absorption layer 5 may not be provided on the backlight surface 102 side, as shown in Figures 1 to 4; or the second light absorption layer 5 may be provided only on the backlight surface 102 side of the substrate 1, and the first light absorption layer 4 may not be provided on the light-receiving surface 101 side, as shown in Figure 5.

[0036] It should be understood that, compared to conventional two-terminal, three-terminal, or four-terminal tandem solar cells, the solar cell disclosed in this invention features a back-contact structure, reducing front-side shading. Furthermore, the first light-absorbing layer 4 is directly stacked on the upper surface of the bottom cell, eliminating the need for an additional carrier transport layer. In other words, the back-contact solar cell of this invention has a cell structure in which a first light-absorbing layer 4 with a bandgap width greater than that of the crystalline silicon cell and a second light-absorbing layer 5 with a bandgap width smaller than that of the crystalline silicon cell are directly formed on the surface of the back-contact crystalline silicon bottom cell. This provides a new approach for the application of tandem solar cells and back-contact solar cells.

[0037] In one embodiment, the second light-absorbing layer 5 may only cover the first and second regions of the backlight surface, as shown in Figures 5 and 6; or it may fully cover the backlight surface 102 of the substrate layer 1, that is, in addition to covering the first region A and the second region B which are in contact with the first carrier transport layer 2 and the second carrier transport layer 3 respectively, it may also cover the gap between the first region A and the second region B, as shown in Figure 7, thereby further increasing the area of ​​the second light-absorbing layer 5 and improving light absorption and the power generation efficiency of the battery.

[0038] Referring to Figures 1 to 4, taking the first light absorption layer 4 provided on the light-receiving surface 101 of the substrate layer 1 as an example, the first carrier transport layer 2 may include one or more of a doped polycrystalline silicon layer, a doped amorphous silicon layer, and a charge transport layer of a perovskite solar cell; the second carrier transport layer 3 may also include one or more of a doped polycrystalline silicon layer, a doped amorphous silicon layer, and a charge transport layer of a perovskite solar cell; the charge transport layer of the perovskite solar cell includes a hole transport layer 303 or an electron transport layer 203.

[0039] As shown in Figure 1, in one embodiment, both the first carrier transport layer 2 and the second carrier transport layer 3 are made of doped polysilicon from a TOPCon cell. In this case, a tunneling oxide layer is also provided between the doped polysilicon layer and the substrate layer 1 to achieve passivation contact. Exemplarily, the first carrier transport layer 2 includes a first tunneling oxide layer 201a and an n-type doped polysilicon layer 201 stacked together, and the second carrier transport layer 3 includes a second tunneling oxide layer 301a and a p-type doped polysilicon layer 301 stacked together.

[0040] As shown in Figure 2, in another embodiment, both the first carrier transport layer 2 and the second carrier transport layer 3 are made of doped amorphous silicon from an HJT battery as doping layers. In this case, an intrinsic amorphous silicon layer is also disposed between the doped amorphous silicon layer and the substrate layer 1 to achieve passivation contact. For example, the first carrier transport layer 2 includes a first intrinsic amorphous silicon layer 202a and an n-type doped amorphous silicon layer 202 stacked together, and the second carrier transport layer 3 includes a second intrinsic amorphous silicon layer 302a and a p-type doped amorphous silicon layer 302 stacked together.

[0041] As shown in Figure 3, in another embodiment, both the first carrier transport layer 2 and the second carrier transport layer 3 are selected as charge transport layers of a perovskite solar cell. Exemplarily, the first carrier transport layer 2 includes an electron transport layer 203 of a perovskite solar cell, and the second carrier transport layer 3 includes a hole transport layer 303 of a perovskite solar cell. The electron transport layer 203 can be made of one or more of the following: titanium dioxide (TiO2), tin dioxide (SnO2), zinc oxide (ZnO), Phenyl-C61-Butyric Acid Methyl Ester (PCBM), C60, barium stannate (BaSnO3), and indium gallium zinc oxide; the hole transport layer 303 can be made of one or more of the following: polytriarylamine (PTAA), 2,2',7,7'-tetratetra[n,n-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Sprio-OMeTAD), nickel oxide (NiOx), cuprous thiocyanate (CuSCN), cuprous iodide (CuI), and PEDOT:PSS (an aqueous solution of a polymer composed of PEDOT and PSS, where PEDOT is a polymer of EDOT (3,4-ethylenedioxythiophene monomer) and PSS is polystyrene sulfonate).

[0042] For ease of description, the following explanation will use the example of a perovskite solar cell charge transport layer as the first carrier transport layer 2 and the second carrier transport layer 3.

[0043] Of course, in other embodiments, the first carrier transport layer 2 and the second carrier transport layer 3 may also adopt carrier transport structures of different battery types. For example, the first carrier transport layer 2 includes the first intrinsic amorphous silicon layer 202a and the n-type doped amorphous silicon layer 202 of the HJT battery, while the second carrier transport layer 3 includes the hole transport layer 303 of the perovskite battery, as shown in Figure 4.

[0044] In one embodiment, the first light absorption layer 4 includes a wide bandgap perovskite light absorption layer with a bandgap width greater than that of the substrate layer 1, and / or the second light absorption layer 5 includes a narrow bandgap perovskite light absorption layer with a bandgap width less than that of the substrate layer 1.

[0045] The bandgap width of the crystalline silicon substrate 1 is typically ~1.12 eV. This disclosure specifies that the first light-absorbing layer 4 is a perovskite material layer with a bandgap width greater than that of the crystalline silicon material, i.e., a wide-bandgap perovskite light-absorbing layer, in order to absorb more short-wavelength light. The overall bandgap width of the material can be changed by adjusting the composition or proportion of the perovskite material. Therefore, firstly, the wide-bandgap perovskite light-absorbing layer in this disclosure can use halides with high bromine (Br) or chlorine (Cl) content, such as MAPbBr3. These halides have strong electron affinity and a wider energy bandwidth, thus resulting in a wider bandgap than crystalline silicon. Secondly, the wide-bandgap perovskite light-absorbing layer in this disclosure uses lead (Pb) as the main metal cation, or it can be doped with tin (Sn) or germanium (Ge) to adjust the bandwidth, for example, forming MAGeBr3. Thirdly, the wide-bandgap perovskite light-absorbing layer in this disclosure also uses small-radius cations, such as methylammonium (MA) and cesium (Cs), which are beneficial for improving crystal stability and bandgap width. In addition, the wide-bandgap perovskite light-absorbing layer can further modulate the bandgap by mixing halides (such as Br and Cl), for example, forming MAPb(Br) x Cl1 x 3.

[0046] The second light-absorbing layer 5 is a narrow-bandgap perovskite light-absorbing layer made of crystalline silicon material with a bandgap width smaller than that of the substrate layer 1. Firstly, the halogen element primarily used in this disclosure is iodine (I), for example, forming MAPbI3. Iodine has a larger ionic radius, resulting in better band overlap and thus a narrower bandgap. Secondly, the narrow-bandgap perovskite light-absorbing layer can use tin (Sn) to partially or completely replace lead as the metal cation to reduce the bandgap, for example, forming MASnI3. Thirdly, the narrow-bandgap perovskite light-absorbing layer uses large-radius cations, such as formamidinium (FA), which can reduce internal crystal stress and lower the bandgap. This facilitates the formation of a back-contact tandem solar cell with a top wide-bandgap perovskite light-absorbing layer, a middle crystalline silicon light-absorbing layer, and a bottom narrow-bandgap perovskite light-absorbing layer, providing a new solution to overcome the power bottleneck of tandem solar cells.

[0047] In one embodiment, as shown in Figures 1 to 4, 6 and 7, the first light-absorbing layer 4 includes a single-layer first photoactive layer.

[0048] At this point, the first photoactive layer of the single layer can be a perovskite light absorption layer with different band gap widths after the above-mentioned regulation, but its band gap width satisfies the condition that it is greater than the band gap width of crystalline silicon material.

[0049] As shown in Figure 8, based on the above scheme, in one embodiment, a first interconnect layer 7 can also be provided between the first light absorption layer 4 and the light-receiving surface 101 of the substrate layer 1 to improve the carrier transmission efficiency and conduction effect between the first light absorption layer 4 and the substrate layer 1.

[0050] In another embodiment, as shown in FIG9, the first light-absorbing layer 4 mentioned above includes multiple layers of first photoactive layers 401 stacked together; along the incident direction of sunlight, the band gap width of the multiple layers of first photoactive layers 401 gradually decreases.

[0051] Taking the first light-absorbing layer 4, which includes two first photoactive layers 401, as an example, the bandgap width of the first photoactive layer 401 relatively far from the substrate layer 1 is greater than the bandgap width of the first photoactive layer 401 relatively close to the substrate layer 1. Simultaneously, the bandgap width of the first photoactive layer 401 closest to the substrate layer 1 is greater than the bandgap width of the substrate layer 1. By setting multiple layers of first photoactive layers on one side of the light-receiving surface 101 in the incident direction of sunlight, the capture and absorption of light across the entire wavelength range is further improved, significantly enhancing photoelectric conversion efficiency and power generation efficiency. For example, the multiple layers of first photoactive layers 401 can be perovskite light-absorbing layers with different bandgap widths, or light-absorbing layers of other materials, as long as the bandgap width decreases from top to bottom and is greater than the bandgap width of crystalline silicon.

[0052] As shown in Figure 9, based on the above scheme, in one embodiment, a first interconnect layer 7 can be provided between the first light-absorbing layer 4 and the light-receiving surface 101 of the substrate layer 1, as well as between adjacent first photoactive layers, to improve the carrier transport efficiency and conduction effect between each layer. Of course, it is also possible to provide the first interconnect layer 7 only between adjacent first photoactive layers 401, or only between the substrate layer 1 and the bottommost first photoactive layer 401.

[0053] The first interconnect layer 7 mentioned above can be a transparent conductive film (TCO-based) material, such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), or aluminum-doped zinc oxide (AZO), etc.

[0054] Similarly, in one embodiment, the second light-absorbing layer 5 described above may include a single-layer second photoactive layer. In this case, the single-layer second photoactive layer may be a perovskite light-absorbing layer with a different bandgap width after the above-described adjustment, but its bandgap width satisfies the condition that it is smaller than the bandgap width of crystalline silicon.

[0055] Based on the above scheme, as shown in Figure 11, in one embodiment, a second interconnect layer 8 can also be provided between the second light absorption layer 5 and the backlight surface 102 of the substrate layer 1 to improve the carrier transmission efficiency and conduction effect between the second light absorption layer 5 and the substrate layer 1.

[0056] In another embodiment, the second light-absorbing layer 5 described above includes multiple layers of second photoactive layers stacked together; the band gap width of the multiple layers of second light-absorbing layers gradually decreases along the incident direction of sunlight.

[0057] Taking the second light-absorbing layer 5, which includes two second photoactive layers, as an example, the bandgap width of the second photoactive layer relatively far from the substrate layer 1 is smaller than the bandgap width of the second photoactive layer relatively close to the substrate layer 1. Simultaneously, the bandgap width of the second photoactive layer closest to the substrate layer 1 is smaller than the bandgap width of the substrate layer 1. By setting multiple layers of second photoactive layers on the backlight side 102 in the direction of sunlight incidence, the capture and absorption of light across the entire wavelength range is further improved, significantly enhancing photoelectric conversion efficiency and power generation efficiency. For example, the multiple layers of second photoactive layers can be perovskite light-absorbing layers with different bandgap widths, or light-absorbing layers of other materials, as long as the bandgap width decreases from top to bottom and is smaller than the bandgap width of crystalline silicon.

[0058] Based on the above scheme, in one embodiment, a second interconnect layer 8 can be provided between the second light absorption layer 5 and the backlight surface 102 of the substrate layer 1, as well as between adjacent second photoactive layers, to improve the carrier transport efficiency and conduction effect between each layer. Of course, it is also possible to provide the second interconnect layer 8 only between adjacent second photoactive layers, or only between the substrate layer 1 and the uppermost second photoactive layer.

[0059] The aforementioned second interconnect layer 8 can also be a transparent conductive film (TCO-based) material, such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), or aluminum-doped zinc oxide (AZO), etc.

[0060] In one embodiment, as shown in Figure 10, when the second light absorption layer is not provided, a second interconnect layer 8 can be directly provided between the first carrier transport layer 2 and the second carrier transport layer 3, which employs the electron transport layer 203 and the hole transport layer 303 of a perovskite solar cell, and the substrate layer 1, to enhance the carrier transport efficiency between the substrate layer 1 and the first carrier transport layer 2 and the second carrier transport layer 3. Of course, it is also possible that only one of the first carrier transport layer 2 or the second carrier transport layer 3 is provided between the substrate layer 1 and the second interconnect layer 8. For example, as shown in Figure 12, the first carrier transport layer 2 is selected from the first intrinsic amorphous silicon layer 202a and the n-type doped amorphous silicon layer 202 of an HJT solar cell, and the second interconnect layer 8 may not be provided between it and the substrate layer 1, because the intrinsic amorphous silicon layer itself has good carrier transport efficiency; the second carrier transport layer 3 is the hole transport layer 303 of a perovskite solar cell, and the second interconnect layer 8 is provided between it and the substrate layer 1 to enhance the collection and transport of hole carriers.

[0061] In one embodiment, as shown in Figures 1 to 12, the aforementioned back-contact tandem solar cell further includes: a functional composite layer 9 disposed on the side surface of the first light-absorbing layer 4 that is relatively far from the substrate layer 1. The functional composite layer 9 includes a passivation layer and an antireflection layer. The passivation layer is adapted to be disposed on the first light-absorbing layer 4, and the antireflection layer is adapted to be disposed on the passivation layer.

[0062] The passivation layer can be made of aluminum oxide and / or silicon nitride, enhancing the passivation contact between the light-receiving surface of the first light-absorbing layer or substrate and a film layer such as an anti-reflection layer disposed on the passivation layer, thereby reducing surface recombination efficiency. The anti-reflection layer material can also be a transparent conductive film material, such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), or aluminum-doped zinc oxide (AZO), etc. Its material composition can be the same as or different from the first interconnect layer 7, depending on process requirements, reducing light reflection from incident sunlight and increasing light absorption. Furthermore, the functional composite layer 9 can also protect the first light-absorbing layer 4.

[0063] Of course, the aforementioned functional composite layer 9 may also include only the anti-reflection layer or only the passivation layer.

[0064] In one embodiment, the functional composite layer 9 is further provided by extending from the edge of the side where the light-receiving surface 101 is located toward the edge of the side where the backlight surface 102 is located.

[0065] That is, the outermost functional composite layer 9 of the battery light-receiving surface 101 also covers part of the side of the battery, such as at least covering the side wall of the first light-absorbing layer 4, or continuing to cover the side wall of the substrate layer 1, to ensure that the performance of the water vapor-sensitive perovskite first light-absorbing layer 4 is not affected.

[0066] As shown in Figures 2 to 11, in one embodiment, when the first carrier transport layer 2 and the second carrier transport layer 3 are not TOPCon cells, the aforementioned back-contact stacked solar cell further includes: a first transparent conductive layer 1001 and a second transparent conductive layer 1002. The first transparent conductive layer 1001 is disposed on the side surface of the first carrier transport layer 2 away from the substrate layer 1, and the first electrode 601 is connected to the first transparent conductive layer 1001. The second transparent conductive layer 1002 is disposed on the side surface of the second carrier transport layer 3 away from the substrate layer 1, and the second electrode 602 is connected to the second transparent conductive layer 1002.

[0067] The first transparent conductive layer 1001 and the second transparent conductive layer 1002 respectively cover the lower surface of the first carrier transport layer 2 and the lower surface of the second carrier transport layer 3, thereby achieving efficient carrier transport between the carrier transport layer and the electrode. The same material or different materials can be selected, such as indium tin oxide (ITO) material in TCO system materials, or fluorine-doped tin oxide (FTO) material, or aluminum-doped zinc oxide (AZO) material, etc.

[0068] Of course, the transparent conductive layer 10 can be configured accordingly for different battery types. For example, in the TOPCon battery type shown in Figure 1, a transparent conductive layer is usually not provided, but aluminum oxide and silicon nitride materials (not shown in the figure) are provided instead. For example, in the HJT battery type shown in Figure 2, there is usually no isolation groove C between the first carrier transport layer 2 and the second carrier transport layer 3, and the sidewalls are in direct contact. The second carrier transport layer 3 may even extend and cover part of the first carrier transport layer 2. In this case, the entire transparent conductive layer 10 forms a small opening on the second carrier transport layer 3, which can form a first transparent conductive layer 1001 and a second transparent conductive layer 1002 that are connected to the first carrier transport layer 2 and the second carrier transport layer 3, but do not completely correspond to or cover them.

[0069] Furthermore, in one embodiment, as shown in FIG13, when an isolation groove C is formed between the first carrier transport layer 2 and the second carrier transport layer 3, the first transparent conductive layer 1001 extends to both sides to cover at least part of the bottom surface of the isolation groove C, and / or the second transparent conductive layer 1002 extends to both sides to cover at least part of the bottom surface of the isolation groove C.

[0070] On the one hand, the extended first transparent conductive layer 1001 and the second transparent conductive layer 1002 can achieve omnidirectional carrier transport. On the other hand, the extended first transparent conductive layer 1001 and the second transparent conductive layer 1002 can also effectively protect the second light absorption layer 5, ensuring the performance of the perovskite light absorption material.

[0071] In summary, based on the back-contact tandem solar cell scheme of this disclosure and conventional schemes, comparative cells with different structures and cells from the embodiments of this disclosure were selected for electrical performance testing. The electrical performance test data of different comparative cells and cells from the embodiments of this disclosure are as follows: Table 1 Electrical performance test results of each comparative cell and embodiment cell

[0072] First, Comparative Example 1 is a conventional back-contact solar cell structure. The carrier transport layer on the back surface is a doped polycrystalline silicon layer, and the crystalline silicon substrate layer serves as the photoactive layer. No additional light-absorbing layer is provided, as shown in Figure 14. Comparative Example 2 is a conventional two-terminal tandem solar cell structure. A perovskite top cell is placed on top of the crystalline silicon bottom cell, and the two are connected by an interconnect layer. The perovskite top cell includes a perovskite light-absorbing layer and electron transport and hole transport layers located on either side of the perovskite light-absorbing layer, as shown in Figure 15. As shown in the table above, Comparative Example 1 has higher short-circuit current density (Jsc) and fill factor (FF) than Comparative Example 2, while Comparative Example 2 has higher conversion efficiency (η) and open-circuit voltage (Voc) than Comparative Example 1.

[0073] In Example 1, the second light absorption layer 5 is provided only on the back light surface 102 side of the substrate layer 1, and the second light absorption layer 5 is a narrow bandgap perovskite light absorption layer. The first light absorption layer 4 is not provided on the light-receiving surface 101 side. That is, the cell in Example 1 is a back contact tandem solar cell including a crystalline silicon light absorption layer and a narrow bandgap perovskite light absorption layer. For the battery of Example 1, a back-contact tandem solar cell with a double light absorption layer is realized by constructing a narrow bandgap light absorption layer on one side of the back light surface 102 of the crystalline silicon substrate layer 1. It can fully absorb incident light in the mid-to-long wavelength range. In addition, the light-receiving surface 101 is unblocked by grid lines. As shown in the table above, the battery of Example 1 has higher electrical performance parameters in short-circuit current density (Jsc) and fill factor (FF) than the battery of Comparative Example 1 with a single light absorption layer. In terms of electrical performance parameters in conversion efficiency (η) and open-circuit voltage (Voc), it has higher electrical performance parameters than the battery of Comparative Example 2, which has grid lines blocking one side of the light-receiving surface and a top battery with a perovskite light absorption layer and charge transport layers on both sides of the crystalline silicon light absorption layer.

[0074] In Example 2, a first light-absorbing layer 4 is provided only on the light-receiving surface 101 side of the substrate 1, and the first light-absorbing layer 4 is a wide-bandgap perovskite light-absorbing layer. No second light-absorbing layer 5 is provided on the back-lighting surface 102 side. That is, Example 2 is a back-contact tandem solar cell including a wide-bandgap perovskite light-absorbing layer and a crystalline silicon light-absorbing layer. For Example 2, by constructing a wide-bandgap light-absorbing layer on the light-receiving surface 101 side of the crystalline silicon substrate 1, a back-contact tandem solar cell with dual light-absorbing layers is achieved, which can fully absorb incident light in the mid-to-short wavelength range. Since the number of short-wavelength photons in solar incident light is significantly higher than the number of long-wavelength photons, fully utilizing short-wavelength incident light is more important than long-wavelength incident light, resulting in Example 2 having higher performance parameters than Example 1.

[0075] Example 3 is a battery based on Example 2, with a single-layer first interconnect layer 7 disposed between the light-receiving surface 101 of the substrate layer 1 and the first light-absorbing layer 4. The first interconnect layer 7 is a back-contact tandem solar cell with a TCO material layer. For Example 3, the introduction of the first interconnect layer 7 between the wide bandgap light-absorbing layer and the crystalline silicon light-absorbing layer, based on Example 2, enables efficient transport of photogenerated carriers generated in both parts, increasing the battery's collection performance. As shown in the table above, all battery performance parameters are improved compared to Example 2.

[0076] Example 4 is a back-contact tandem solar cell based on Example 2, with the first light-absorbing layer 4 configured as a multi-layered first photoactive layer 401. The band gap of the multi-layered first photoactive layer 401 gradually decreases along the light incident direction. In Example 4, by establishing a multi-layered wide-bandgap perovskite light-absorbing layer with decreasing band gap, the gradient-changing light-absorbing layer structure better facilitates the full absorption of incident light by each light-absorbing layer. Therefore, Example 4's battery performance parameters are superior to those of Examples 2 and 3.

[0077] In Example 5, a first light-absorbing layer 4 is disposed on the light-receiving surface 101 side of the substrate 1, and a second light-absorbing layer 5 is disposed on the back-lighting surface 102 side. The first light-absorbing layer 4 is a wide-bandgap perovskite light-absorbing layer, and the second light-absorbing layer 5 is a narrow-bandgap perovskite light-absorbing layer. Therefore, Example 5 is a back-contact tandem solar cell comprising a wide-bandgap perovskite light-absorbing layer, a crystalline silicon light-absorbing layer, and a narrow-bandgap perovskite light-absorbing layer. Example 5 forms a tandem solar cell with three light-absorbing layers, ensuring sufficient absorption of incident light at all wavelengths. As shown in the table above, the cell performance is optimal. Embodiments of this disclosure also provide a back-contact tandem solar cell module, comprising: a plurality of the aforementioned back-contact tandem solar cells.

[0078] The aforementioned back-contact tandem solar cell includes: a crystalline silicon substrate 1 and a first light-absorbing layer 4 covering one side of the light-receiving surface 101 of the crystalline silicon substrate 1 and / or a second light-absorbing layer 5 covering one side of the back-lighting surface 102 of the crystalline silicon substrate 1. The band gap width of the first light-absorbing layer 4 is greater than the band gap width of the substrate 1, and the band gap width of the second light-absorbing layer 5 is less than the band gap width of the substrate 1. When sunlight strikes the light-receiving surface 101 of the battery, it first passes through the first light-absorbing layer 4 with a relatively large bandgap, achieving full absorption of short-wavelength light. Then, it enters the crystalline silicon material of the substrate layer 1 with a smaller bandgap, further absorbing mid-wavelength light. Afterward, it can enter the second light-absorbing layer 5 with an even smaller bandgap, achieving absorption of long-wavelength light. Ultimately, this enhances the battery's utilization of incident sunlight of different wavelengths, improving the battery's photoelectric conversion efficiency and power generation performance. This can form a back-contact tandem solar cell with a top wide-bandgap perovskite light-absorbing layer, a middle crystalline silicon light-absorbing layer, and a bottom narrow-bandgap perovskite light-absorbing layer, providing a new solution for breaking through the power bottleneck of tandem cells and battery modules. Such a battery, when used in a module, has extremely high prospects for mass production applications.

[0079] Further functional descriptions of the above structures are the same as those of the corresponding embodiments described above, and will not be repeated here.

[0080] Although embodiments of the present disclosure have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present disclosure, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A back-contact tandem solar cell, characterized in that, Includes: a substrate layer, the substrate layer including a light-receiving surface and a back-lighting surface disposed opposite to each other, the back-lighting surface including a first region and a second region arranged alternately; and a first carrier transport layer disposed in the first region of the back-lighting surface; A second carrier transport layer is disposed in the second region of the backlight surface, wherein the first carrier transport layer and the second carrier transport layer have opposite conductivity types; a first light absorption layer and / or a second light absorption layer, wherein the first light absorption layer is adapted to be disposed on the light-receiving surface of the substrate layer, and the band gap width of the first light absorption layer is greater than the band gap width of the substrate layer; the second light absorption layer is adapted to be disposed on at least a portion of the backlight surface of the substrate layer, wherein the first carrier transport layer and the second carrier transport layer are disposed on the second light absorption layer, and the band gap width of the second light absorption layer is smaller than the band gap width of the substrate layer; a first electrode and a second electrode, wherein the first electrode is connected to the first carrier transport layer, and the second electrode is connected to the second carrier transport layer.

2. The back-contact tandem solar cell according to claim 1, characterized in that, The first light absorption layer includes a wide bandgap perovskite light absorption layer with a bandgap width greater than that of the substrate layer, and / or the second light absorption layer includes a narrow bandgap perovskite light absorption layer with a bandgap width smaller than that of the substrate layer.

3. The back-contact tandem solar cell according to claim 1, characterized in that, The first light-absorbing layer includes a single-layer first photoactive layer; or the first light-absorbing layer includes multiple stacked first photoactive layers, wherein the band gap width of the multiple first photoactive layers gradually decreases along the incident direction of sunlight; the second light-absorbing layer includes a single-layer second photoactive layer; or the second light-absorbing layer includes multiple stacked second photoactive layers, wherein the band gap width of the multiple second photoactive layers gradually decreases along the incident direction of sunlight.

4. The back-contact tandem solar cell according to claim 3, characterized in that, Also includes: A first interconnect layer is disposed between the first light-absorbing layer and the light-receiving surface of the substrate layer, and / or the first interconnect layer is disposed between adjacent first photoactive layers; And / or a second interconnect layer, the second interconnect layer being located between the second light-absorbing layer and the backlight surface of the substrate layer, and / or the second interconnect layer being disposed between adjacent second photoactive layers.

5. The back-contact tandem solar cell according to claim 1, characterized in that, Also includes: A functional composite layer is disposed on the first light-absorbing layer; The functional composite layer includes a passivation layer and / or an antireflection layer, wherein the passivation layer is adapted to be disposed on the first light absorption layer, and the antireflection layer is adapted to be disposed on the passivation layer.

6. The back-contact tandem solar cell according to claim 5, characterized in that, The functional composite layer is further provided by extending from the edge of the light-receiving surface toward the edge of the backlighting surface.

7. The back-contact tandem solar cell according to any one of claims 1-6, characterized in that, The first carrier transport layer includes one or more of a doped polycrystalline silicon layer, a doped amorphous silicon layer, and a charge transport layer of a perovskite solar cell; the second carrier transport layer includes one or more of a doped polycrystalline silicon layer, a doped amorphous silicon layer, and a charge transport layer of a perovskite solar cell; the charge transport layer of the perovskite solar cell includes a hole transport layer or an electron transport layer.

8. The back-contact tandem solar cell according to claim 1, characterized in that, When the first carrier transport layer includes a charge transport layer of doped amorphous silicon or a perovskite solar cell, and the second carrier transport layer includes a charge transport layer of doped amorphous silicon or a perovskite solar cell, the system further includes: a first transparent conductive layer disposed on the side surface of the first carrier transport layer facing away from the substrate layer, wherein the first electrode is connected to the first transparent conductive layer; and a second transparent conductive layer disposed on the side surface of the second carrier transport layer facing away from the substrate layer, wherein the second electrode is connected to the second transparent conductive layer.

9. The back-contact tandem solar cell according to claim 8, characterized in that, An isolation groove is formed between the first carrier transport layer and the second carrier transport layer; the first transparent conductive layer extends to both sides to cover at least a portion of the bottom surface of the isolation groove, and / or the second transparent conductive layer extends to both sides to cover at least a portion of the bottom surface of the isolation groove.

10. A back-contact tandem solar cell module, characterized in that, include: The back-contact tandem solar cell according to any one of claims 1 to 9.

Images