A cztsses solar cell string and a solar cell module including the same

Abstract

This invention provides a CZTSSe solar cell string and a CZTSSe solar cell module with a series structure. The CZTSSe solar cell string includes at least two CZTSSe solar sub-cells connected in series. Each CZTSSe solar sub-cell includes a bottom electrode, a CZTSSe light-absorbing layer, a buffer layer, a transparent conductive layer, and a top electrode stacked sequentially from bottom to top. The bottom electrode has a double-sided conductive structure. Every two adjacent CZTSSe solar sub-cells are connected in series by a flexible solid conductive adhesive bonding layer. The two opposite surfaces of the flexible solid conductive adhesive bonding layer are connected to the bottom electrode of the preceding CZTSSe solar sub-cell and the top electrode of the following CZTSSe solar sub-cell, respectively. Using the flexible solid conductive adhesive bonding layer as the conductive material between sub-cells achieves a high-efficiency, low-cost, large-area flexible photovoltaic module.

Description

Technical Field

[0001] This invention relates generally to the technical field of copper-zinc-tin-sulfur-selenium solar cell modules, and in particular to a CZTSSe solar cell string with a series structure and a CZTSSe solar cell module including the CZTSSe solar cell string. Background Technology

[0002] With the rapid development of human society, people's demand for energy is increasing day by day. However, the current global energy structure is still dominated by fossil fuels with high pollution and high carbon emissions, leading to global warming and frequent abnormal weather events in recent years. Therefore, developing clean energy has become an inevitable path. Solar cells can directly convert solar energy into electrical energy, making them an ideal form of energy utilization. Copper-zinc-tin-sulfur-selenium (Cu2ZnSn(S,Se)4, abbreviated as CZTSSe) solar cells, as a new type of thin-film solar cell, have advantages such as low manufacturing cost, high abundance of constituent elements on Earth, and high process compatibility, and have attracted increasing attention. After the past two decades of development, the highest power conversion efficiency (PCE) of CZTSSe solar cells has approached 15%, demonstrating its potential for industrialization.

[0003] However, most current CZTSSe solar cell technologies are based on small-area devices, making them unsuitable for large-scale module production. The most widely used module technology in the thin-film solar cell field is laser scribing. This technology requires extremely high uniformity in a single large-area thin film. Furthermore, because CZTSSe films are on the micrometer scale, significant thermal effects occur during laser etching, demanding extremely high precision, which substantially increases equipment costs and process repeatability. Therefore, developing a photovoltaic module technology more suitable for CZTSSe solar cells is crucial. Summary of the Invention

[0004] In view of the above problems, the present invention proposes a CZTSSe solar cell string with a series structure that overcomes or at least partially solves the above problems, and a CZTSSe solar cell module including the CZTSSe solar cell string.

[0005] One object of the present invention is to provide a CZTSSe solar cell string and a CZTSSe solar cell module with high fabrication efficiency.

[0006] Another objective of this invention is to reduce the uniformity requirements of the components for large-area thin films and increase the yield rate.

[0007] Another objective of this invention is to significantly reduce the weight of photovoltaic modules.

[0008] Another object of the present invention is to realize a flexible, bendable solar cell.

[0009] In particular, according to one aspect of the present invention, a CZTSSe solar cell string with a series structure is provided, comprising at least two CZTSSe solar sub-cells connected in series, each of the CZTSSe solar sub-cells comprising a bottom electrode, a CZTSSe light-absorbing layer, a buffer layer, a transparent conductive layer and a top electrode stacked sequentially from bottom to top; wherein the bottom electrode has a double-sided conductive structure; every two adjacent CZTSSe solar sub-cells are connected in series by a flexible solid conductive adhesive connecting layer, the two opposite surfaces of the flexible solid conductive adhesive connecting layer being connected to the bottom electrode of the preceding CZTSSe solar sub-cell and the top electrode of the following CZTSSe solar sub-cell, respectively.

[0010] Optionally, the flexible solid conductive adhesive bonding layer is strip-shaped, including a flexible conductive strip and two conductive adhesive layers respectively coated on two surfaces of the flexible conductive strip. The two conductive adhesive layers are respectively connected to the bottom electrode of the previous CZTSSe solar sub-cell and the top electrode of the subsequent CZTSSe solar sub-cell.

[0011] Optionally, the thickness of the flexible conductive strip is less than 100 μm;

[0012] The flexible conductive strip is made of Cu, Ag, Al, or graphite.

[0013] Optionally, the conductive adhesive layer is made of an adhesive mixed with conductive nanoparticles; wherein

[0014] The adhesive includes at least one selected from epoxy resin, silicone, and acrylate.

[0015] The conductive nanoparticles include at least one selected from silver nanoparticles, aluminum nanoparticles, and copper nanoparticles.

[0016] Optionally, the bottom electrode is a double-sided conductive metal foil substrate;

[0017] The metal foil is a molybdenum foil, a titanium foil, or a stainless steel foil sputtered with molybdenum;

[0018] The thickness of the metal foil is 10–200 μm.

[0019] Optionally, the at least two CZTSSe solar sub-cells are arranged in a shingled configuration.

[0020] According to another aspect of the present invention, a CZTSSe solar cell module is also provided, comprising, from top to bottom, a first encapsulation film, a first encapsulating adhesive, a CZTSSe solar cell module, a second encapsulating adhesive, and a second encapsulation film; wherein

[0021] The CZTSSe solar cell module consists of a single CZTSSe solar cell string as described above; or

[0022] The CZTSSe solar cell module is composed of at least two of the aforementioned CZTSSe solar cells connected in series and parallel.

[0023] Optionally, each of the CZTSSe solar cell strings is provided with a first wire extending outward from the top electrode of the CZTSSe solar cell at its first end and a second wire extending outward from the bottom electrode of the CZTSSe solar cell at its last end.

[0024] In the case where the CZTSSe solar cell module is composed of at least two CZTSSe solar cell strings connected in parallel, the parallel connection is achieved by welding the first wires of every two adjacent CZTSSe solar cell strings together and welding their second wires together.

[0025] Optionally, the first wire and the second wire may be made of the same or different materials;

[0026] The first and second conductors are double-sided conductive metal strips or metal conductors;

[0027] The metal strip is Ag strip, Al strip, Cu strip, conductive adhesive tape, or graphite strip;

[0028] The metal wire is an Ag wire, a Cu wire, or an Al wire.

[0029] Optionally, the material of the first encapsulation film is a transparent organic encapsulation material, which includes at least one of polyethylene terephthalate (PET), ethylene-tetrafluoroethylene copolymer (ETFE), polyethylene naphthalate (PEN), and polyimide (PI).

[0030] The second encapsulation film is made of an organic encapsulation material, which includes at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), ethylene-tetrafluoroethylene copolymer (ETFE), and polyvinylidene fluoride (PVF).

[0031] The first encapsulant and the second encapsulant may be made of the same or different materials, and the materials of the first encapsulant and the second encapsulant include at least one of ethylene-vinyl acetate copolymer (EVA), polyolefin thermoplastic elastomer (POE), and EPE three-layer film.

[0032] The CZTSSe solar cell string and CZTSSe solar cell module provided by this invention employ at least two CZTSSe solar sub-cells connected in series to form the CZTSSe solar cell string, and adjacent CZTSSe solar sub-cells are connected in series through a flexible solid conductive adhesive connecting layer. Compared with traditional thermosetting conductive adhesive, using a flexible solid conductive adhesive connecting layer as the conductive material between sub-cells can significantly reduce the difficulty of cell series connection and shorten the silver paste curing cycle. It can also avoid damage to the CZTSSe solar cells during the high-temperature annealing process, thereby significantly improving the manufacturing efficiency. Furthermore, the use of the flexible solid conductive adhesive connecting layer can also facilitate the realization of splicable flexible photovoltaic modules.

[0033] Furthermore, the flexible solid conductive adhesive bonding layer includes a flexible conductive strip and two conductive adhesive layers respectively coated on two surfaces of the flexible conductive strip. The conductive adhesive layers are made of an adhesive mixed with conductive nanoparticles. By using low-cost flexible conductive strip and conductive adhesive layer materials, the cost of battery strings and modules can be reduced.

[0034] Furthermore, the bottom electrode of each CZTSSe solar sub-cell is a double-sided conductive metal foil substrate. Compared to traditional glass substrates, the use of metal foil substrates can significantly reduce the weight of photovoltaic modules.

[0035] Furthermore, by using a flexible solid conductive adhesive connecting layer to connect at least two CZTSSe solar sub-cells in series to form a CZTSSe solar cell string, and further connecting at least two CZTSSe solar cell strings in parallel to form a CZTSSe solar cell module, a CZTSSe solar cell module is finally formed. This reduces the uniformity requirements of the module for large-area thin films and increases the yield rate.

[0036] Furthermore, the structure in which CZTSSe solar sub-cells are connected in series by a flexible solid conductive adhesive layer and the structure in which CZTSSe solar cell strings are connected in parallel by wire welding realizes a flexible and bendable solar cell.

[0037] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below.

[0038] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0039] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0040] Figure 1 This is a schematic diagram of a CZTSSe solar cell string with a series structure according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the structure of a flexible solid conductive adhesive bonding layer according to an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the structure of a CZTSSe solar cell module according to an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the structure of a CZTSSe solar cell module in a CZTSSe solar cell module according to an embodiment of the present invention. Detailed Implementation

[0044] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0045] In view of the aforementioned problems, the present invention provides a CZTSSe solar cell string 100 with a series structure.

[0046] Figure 1 This is a schematic diagram of the structure of a CZTSSe solar cell string 100 with a series structure according to an embodiment of the present invention.

[0047] See Figure 1As shown, in one embodiment, the CZTSSe solar cell string 100 of the present invention includes at least two CZTSSe solar sub-cells 110 connected in series. Each CZTSSe solar sub-cell 110 includes a bottom electrode 111, a CZTSSe light-absorbing layer 112, a buffer layer 113, a transparent conductive layer 114 (also referred to as a window layer), and a top electrode 115 stacked sequentially from bottom to top. The bottom electrode 111 has a double-sided conductive structure. Every two adjacent CZTSSe solar sub-cells 110 are connected in series by a flexible solid conductive adhesive connecting layer 116. Specifically, the two opposite surfaces of the flexible solid conductive adhesive connecting layer 116 are respectively connected to the bottom electrode 111 of the preceding CZTSSe solar sub-cell 110 and the top electrode 115 of the following CZTSSe solar sub-cell 110, thereby connecting the two CZTSSe solar sub-cells 110 in series.

[0048] In the CZTSSe solar cell string 100 provided in this embodiment of the invention, at least two CZTSSe solar sub-cells 110 are connected in series to form the CZTSSe solar cell string 100, and adjacent CZTSSe solar sub-cells 110 are connected in series by a flexible solid conductive adhesive connecting layer 116. Compared with traditional thermosetting conductive adhesive, using the flexible solid conductive adhesive connecting layer 116 as the conductive material between sub-cells can significantly reduce the difficulty of cell series connection and shorten the silver paste curing cycle. It can also avoid the damage to the CZTSSe solar cells caused by the high-temperature annealing process, thereby significantly improving the manufacturing efficiency. Furthermore, the use of the flexible solid conductive adhesive connecting layer 116 can also facilitate the realization of splicable flexible photovoltaic modules.

[0049] In some embodiments, the flexible solid conductive adhesive bonding layer 116 is strip-shaped to more easily attach the bottom electrode 111 and top electrode 115 of the CZTSSe solar sub-cell 110.

[0050] Figure 2 This is a schematic diagram of the structure of a flexible solid conductive adhesive bonding layer 116 according to an embodiment of the present invention. Figure 2 As shown, in some embodiments, the flexible solid conductive adhesive connecting layer 116 includes a flexible conductive strip 1161 and two conductive adhesive layers 1162 respectively coated on the two surfaces of the flexible conductive strip 1161. That is, the flexible solid conductive adhesive connecting layer 116 has a conductive adhesive / flexible conductive strip / conductive adhesive structure. The two conductive adhesive layers 1162 are respectively connected to the bottom electrode 111 of the preceding CZTSSe solar sub-cell 110 and the top electrode 115 of the following CZTSSe solar sub-cell 110, thereby realizing convenient series connection of CZTSSe solar sub-cells 110 while achieving flexible series connection with low electrical loss between sub-cells.

[0051] In some embodiments, the thickness of the flexible conductive strip 1161 is less than 100 μm, for example, 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm, or 10 μm.

[0052] In some embodiments, the material of the flexible conductive strip 1161 may be Cu, Ag, Al or graphite, thereby better balancing conductivity and flexibility.

[0053] In some embodiments, the conductive adhesive layer 1162 may be made of an adhesive mixed with conductive nanoparticles. The adhesive may include at least one selected from epoxy resins, silicone rubbers, acrylates, etc. The conductive nanoparticles may include at least one selected from silver nanoparticles, aluminum nanoparticles, copper nanoparticles, etc.

[0054] Specifically, the materials of the conductive adhesive layer 1162 include, but are not limited to, epoxy resin adhesive mixed with silver nanoparticles, epoxy resin adhesive mixed with aluminum nanoparticles, silicone adhesive mixed with silver nanoparticles, and acrylate mixed with copper nanoparticles.

[0055] By using low-cost flexible conductive strip 1161 material and conductive adhesive layer 1162 material, the cost of battery strings and modules can be reduced.

[0056] In some embodiments, the thickness of each conductive adhesive layer 1162 may be less than 100 μm, for example, 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm, or 10 μm. This ensures the flexibility of the entire flexible solid conductive adhesive bonding layer 116.

[0057] In some embodiments, the bottom electrode 111 is a double-sided conductive metal foil substrate. Compared with conventional glass substrates, the use of metal foil substrates can significantly reduce the weight of photovoltaic modules.

[0058] In some embodiments, the metal foil may be molybdenum foil, titanium foil, or stainless steel foil sputtered with molybdenum, etc.

[0059] In some embodiments, the thickness of the metal foil is 10 to 200 μm, such as 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, etc.

[0060] Preferably, the thickness of the metal foil is 50–100 μm.

[0061] In some embodiments, the thickness of the CZTSSe light absorption layer 112 is 0.5 to 5 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, etc.

[0062] In some optional embodiments, the precursor of the CZTSSe light-absorbing layer 112 can be prepared by solution method, sputtering method, multi-step co-evaporation method, electrochemical deposition method, etc. The CZTSSe light-absorbing layer 112 can be prepared by post-selenization method, co-evaporation method (such as multi-step co-evaporation method) or single crystal method.

[0063] In some embodiments, the material of the buffer layer 113 may include, but is not limited to, cadmium sulfide (CdS), zinc oxysulfide (Zn(O,S)), zinc tin oxysulfide (ZnSnO3), and zinc cadmium sulfide (Zn). x Cd 1-x S), etc.

[0064] In some embodiments, the thickness of the buffer layer 113 is 10 to 100 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or 90 nm.

[0065] In some alternative embodiments, the buffer layer 113 may be prepared by chemical bath deposition, magnetron sputtering, thermal evaporation or atomic layer deposition.

[0066] In some embodiments, the transparent conductive layer 114 may have a dual-layer structure (not shown in the figure), comprising a high-resistance anti-leakage layer connected to the buffer layer 113 and a low-resistance conductive transport layer connected to the top electrode 115.

[0067] Alternatively, the transparent conductive layer 114 can be prepared by magnetron sputtering.

[0068] In some embodiments, the materials of the high-resistance anti-leakage layer include, but are not limited to, zinc oxide (ZnO) and zinc magnesium oxide (ZnO). x Mg 1-x Materials include O, tin oxide (SnO2), etc. The thickness of the high-resistance anti-leakage layer is 5-100nm, such as 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, and 90nm.

[0069] In some embodiments, the low-resistance conductive transport layer may be an aluminum-doped zinc oxide (AZO) layer, a tin-doped indium oxide (ITO) layer, or a zinc-doped indium oxide (IZO) layer. The thickness of the low-resistance conductive transport layer is 50–1500 nm, for example, 100 nm, 300 nm, 500 nm, 800 nm, 1000 nm, 1200 nm, 1300 nm, or 1400 nm.

[0070] In some embodiments, the material of the top electrode 115 includes, but is not limited to, Ag, Ni / Al, Ni / Cu, Au, etc.

[0071] In some alternative embodiments, the top electrode 115 may be prepared by thermal evaporation deposition or electroplating.

[0072] In one specific embodiment, the top electrode 115 is a Ni / Al electrode, wherein the Ni layer thickness is 5-100 nm and the Al layer thickness is 0.1-10 μm.

[0073] See also Figure 1 In some embodiments, each CZTSSe solar subcell 110 may also include an antireflection layer 117 disposed on top of the transparent conductive layer 114.

[0074] The antireflection layer 117 may be made of materials including but not limited to magnesium fluoride (MgF2), lithium fluoride (LiF), silicon dioxide (SiO2), silicon nitride (Si3N4), etc.

[0075] In some embodiments, the at least two CZTSSe solar sub-cells 110 in the solar cell string 100 are arranged in a shingled configuration. This arrangement facilitates series connection between sub-cells while ensuring that each sub-cell has the largest possible light-receiving area.

[0076] Based on the same technical concept, the present invention also provides a CZTSSe solar cell module 10, which can be fabricated based on the aforementioned CZTSSe solar cell string 100.

[0077] Figure 3 This is a schematic diagram of the structure of a CZTSSe solar cell module 10 according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of the CZTSSe solar cell module 140 in the CZTSSe solar cell module 10 according to an embodiment of the present invention.

[0078] See Figure 3 As shown, the CZTSSe solar cell module 10 generally includes, from top to bottom, a first encapsulation film 120, a first encapsulating adhesive 130, a CZTSSe solar cell module 140, a second encapsulating adhesive 150, and a second encapsulation film 160.

[0079] The first encapsulation film 120 can be made of a transparent organic encapsulation material to ensure its light transmittance.

[0080] In some embodiments, the material of the first encapsulation film 120 may include, but is not limited to, at least one of polyethylene terephthalate (PET), ethylene-tetrafluoroethylene copolymer (ETFE), polyethylene naphthalate (PEN), polyimide (PI), etc.

[0081] Since the second encapsulation film 160 is located on the back of the solar cell module 10, there are no specific requirements for the light transmittance of the material of the second encapsulation film 160, and general organic encapsulation materials can be used.

[0082] In some embodiments, the material of the second encapsulation film 160 may include, but is not limited to, at least one of PET, ETFE, PEN, PI, polyvinylidene fluoride (PVF), etc.

[0083] The first encapsulant 130 and the second encapsulant 150 may be made of the same or different transparent encapsulating materials.

[0084] In some embodiments, the materials of the first encapsulant 130 and the second encapsulant 150 may include at least one of ethylene-vinyl acetate copolymer (EVA), polyolefin thermoplastic elastomer (POE), and EPE (EVA-POE-EVA) three-layer film.

[0085] In some embodiments, the CZTSSe solar cell module 140 consists of a single CZTSSe solar cell string 100 as described above, such as Figure 3 As shown.

[0086] In other embodiments, the CZTSSe solar cell module 140 is formed by connecting at least two of the aforementioned CZTSSe solar cell strings 100 in parallel. For example, as... Figure 4 As shown, in one specific embodiment, the CZTSSe solar cell module 140 is composed of three CZTSSe solar cell strings 100 connected in parallel.

[0087] By using a flexible solid conductive adhesive connecting layer 116 to connect at least two CZTSSe solar sub-cells 110 in series to form a CZTSSe solar cell string 100, and further connecting at least two CZTSSe solar cell strings 100 in parallel to form a CZTSSe solar cell module 140, a CZTSSe solar cell module 10 is finally formed, which reduces the uniformity requirements of the module for large-area thin films and increases the yield.

[0088] Furthermore, each CZTSSe solar cell string 100 is provided with a first wire 170 extending outward from the top electrode 115 of the CZTSSe solar cell 110 at its first end and a second wire 180 extending outward from the bottom electrode 111 of the CZTSSe solar cell 110 at its last end.

[0089] In the case where a CZTSSe solar cell module 140 is composed of a single CZTSSe solar cell string 100, the first wire 170 and the second wire 180 are directly used as lead wires of the CZTSSe solar cell assembly 10.

[0090] When the CZTSSe solar cell module 140 is composed of at least two CZTSSe solar cell strings 100 connected in parallel, the CZTSSe solar cell strings 100 can also be connected in parallel by welding the first wire 170 and the second wire 180 respectively. For example, Figure 4 As shown, the first wires 170 of every two adjacent CZTSSe solar cell strings 100 are welded together, and the second wires 180 of these two CZTSSe solar cell strings 100 are also welded together.

[0091] The CZTSSe solar sub-cells 110 are connected in series by a flexible solid conductive adhesive layer 116, and the CZTSSe solar cell strings 100 are connected in parallel by wire welding, thus realizing a flexible and bendable solar cell.

[0092] The first conductor 170 and the second conductor 180 may be made of the same or different materials.

[0093] In some embodiments, the first conductor 170 and the second conductor 180 are double-sided conductive metal strips or metal wires.

[0094] Specifically, the metal strip can be Ag strip, Al strip, Cu strip, conductive adhesive tape, or graphite strip, etc.

[0095] Metallic conductors can be Ag, Cu, or Al, etc.

[0096] This invention uses low-cost CZTSSe photovoltaic cell material, which can reduce raw material costs.

[0097] The technical features in the above embodiments can be combined arbitrarily. For the sake of simplicity, not all possible combinations in the above embodiments are described in detail. However, any combination of these technical features that does not contradict each other should be considered within the scope of this specification.

[0098] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0099] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A CZTSSe solar cell string with a series structure, comprising at least two CZTSSe solar sub-cells connected in series, each of the CZTSSe solar sub-cells comprising, from bottom to top, a bottom electrode, a CZTSSe light-absorbing layer, a buffer layer, a transparent conductive layer, and a top electrode stacked sequentially; characterized in that, The bottom electrode has a double-sided conductive structure; each pair of adjacent CZTSSe solar sub-cells are connected in series by a flexible solid conductive adhesive connecting layer, and the two opposite surfaces of the flexible solid conductive adhesive connecting layer are respectively connected to the bottom electrode of the previous CZTSSe solar sub-cell and the top electrode of the next CZTSSe solar sub-cell.

2. The CZTSSe solar cell string according to claim 1, characterized in that, The flexible solid conductive adhesive bonding layer is strip-shaped, including a flexible conductive strip and two conductive adhesive layers respectively coated on two surfaces of the flexible conductive strip. The two conductive adhesive layers are respectively connected to the bottom electrode of the previous CZTSSe solar sub-cell and the top electrode of the next CZTSSe solar sub-cell.

3. The CZTSSe solar cell string according to claim 2, characterized in that, The thickness of the flexible conductive strip is less than 100 μm; The flexible conductive strip is made of Cu, Ag, Al, or graphite.

4. The CZTSSe solar cell string of claim 2, wherein, The conductive adhesive layer is made of an adhesive mixed with conductive nanoparticles; wherein The adhesive includes at least one selected from epoxy resin, silicone, and acrylate. The conductive nanoparticles include at least one selected from silver nanoparticles, aluminum nanoparticles, and copper nanoparticles.

5. The CZTSSe solar cell string of claim 1, wherein, The bottom electrode is a double-sided conductive metal foil substrate; The metal foil is a molybdenum foil, a titanium foil, or a stainless steel foil sputtered with molybdenum; The thickness of the metal foil is 10–200 μm.

6. The CZTSSe solar cell string according to any one of claims 1-5, characterized in that, The at least two CZTSSe solar sub-cells are arranged in a shingled configuration.

7. A CZTSSe solar cell module characterized by, It includes, from top to bottom, a first encapsulation film, a first encapsulating adhesive, a CZTSSe solar cell module, a second encapsulating adhesive, and a second encapsulation film; wherein The CZTSSe solar cell module consists of a single CZTSSe solar cell string according to any one of claims 1-6; or The CZTSSe solar cell module is composed of at least two CZTSSe solar cells connected in series and parallel according to any one of claims 1-6.

8. The CZTSSe solar cell module according to claim 7, characterized by, Each of the CZTSSe solar cell strings is provided with a first wire extending outward from the top electrode of the CZTSSe solar cell at its first end and a second wire extending outward from the bottom electrode of the CZTSSe solar cell at its last end. In the case where the CZTSSe solar cell module is composed of at least two CZTSSe solar cell strings connected in parallel, the parallel connection is achieved by welding the first wires of every two adjacent CZTSSe solar cell strings together and welding their second wires together.

9. The CZTSSe solar cell module according to claim 8, characterized by, The first wire and the second wire may be made of the same or different materials; The first and second conductors are double-sided conductive metal strips or metal conductors; The metal strip is Ag strip, Al strip, Cu strip, conductive adhesive tape, or graphite strip; The metal wire is an Ag wire, a Cu wire, or an Al wire.

10. The CZTSSe solar cell module according to claim 7, characterized in that, The first encapsulation film is made of a transparent organic encapsulation material, which includes at least one of polyethylene terephthalate (PET), ethylene-tetrafluoroethylene copolymer (ETFE), polyethylene naphthalate (PEN), and polyimide (PI). The second encapsulation film is made of an organic encapsulation material, which includes at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), ethylene-tetrafluoroethylene copolymer (ETFE), and polyvinylidene fluoride (PVF). The first encapsulant and the second encapsulant may be made of the same or different materials, and the materials of the first encapsulant and the second encapsulant include at least one of ethylene-vinyl acetate copolymer (EVA), polyolefin thermoplastic elastomer (POE), and EPE three-layer film.

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