Thin film photovoltaic cell and preparation method thereof, and photovoltaic module

Abstract

The invention provides a thin film photovoltaic cell, a preparation method and a photovoltaic module, and solves the problem that a sealing adhesive film and a bus bar are easy to fall off in the prior art. The thin-film photovoltaic cell comprises a substrate, a cell structure layer, a bus bar and a sealing adhesive film, wherein the cell structure layer comprises a plurality of cell units; the bus bars are located on the side, away from the substrate, of the battery structure layer and connected with part of the battery units, the bottom faces of the bus bars are attached to the corresponding battery units, and the thickness of the bus bars in the cross section is gradually reduced from the middle area in the cross section to the two side areas in the cross section; the sealant film covers the bus bar and the battery structure layer. At the moment, the surface of the bus bar is smoother, in the process of laminating the sealing adhesive film, the pressure bearing area of the sealing adhesive film at the bus bar is larger, the sealing adhesive film is more easily combined with the surface of the bus bar, and the possibility that the sealing adhesive film falls off from the surface of the bus bar is reduced.

Description

Technical Field

[0001] This invention relates to the technical field of thin-film photovoltaic cells, specifically to a thin-film photovoltaic cell and its preparation method, and a photovoltaic module. Background Technology

[0002] Thin-film photovoltaic (PV) cells are a type of photovoltaic cell fabricated using thin-film technology. When exposed to sunlight, they undergo a photoelectric reaction, converting light energy into electrical energy. Because of their thin-film manufacturing process, thin-film PV cells can easily achieve large-area module fabrication, eliminating the need for post-processing splicing required for crystalline silicon cells.

[0003] However, the performance of current thin-film photovoltaic cells needs to be improved. Summary of the Invention

[0004] In view of this, the present invention aims to provide a thin-film photovoltaic cell and its preparation method, as well as a photovoltaic module.

[0005] In a first aspect, the present invention provides a thin-film photovoltaic cell, comprising: a substrate; a cell structure layer located on one side of the substrate, comprising a plurality of cell cells, each cell comprising a first electrode, a photosensitive structure, and a second electrode sequentially stacked along a direction away from the substrate, wherein at least a portion of the cell cells' second electrodes are electrically connected to the first electrode of an adjacent cell cell; a busbar located on the side of the cell structure layer away from the cell structure layer, electrically connected to the second electrodes of a portion of the cell cells, wherein the bottom surface of the busbar is attached to a corresponding second electrode, and the thickness of the busbar in a cross-section gradually decreases from the middle region of the cross-section to the two sides of the cross-section; a sealing film covering the busbar and the cell structure layer; and a cover plate located on the side of the sealing film away from the substrate.

[0006] In one embodiment, the bottom surface of the busbar is a plane; exemplarily, the busbar includes an upper part having a top surface opposite the bottom surface, the width of the bottom surface being greater than or equal to the width of the top surface; exemplarily, the orthographic projection of the busbar onto the bottom surface coincides with the bottom surface.

[0007] In one embodiment, the top surface is planar and parallel to the bottom surface, and the upper part also has a first side edge, which is inclined and located on both sides of the top surface; exemplarily, the cross-section of the busbar is trapezoidal. In one embodiment, the top surface is curved; exemplarily, the top surface of the busbar is semi-circular or semi-elliptical in cross-section.

[0008] In one embodiment, the busbar includes an upper portion, which includes a first side edge that is inclined. The two first side edges intersect at an end away from the bottom surface. The thickness of the cross-section of the busbar at the first side edge gradually decreases from the middle region to the two side regions. For example, the cross-section of the busbar is triangular.

[0009] In one embodiment, the busbar further includes a lower portion, which includes a second side edge adjacent to the bottom surface. The second side edge is a hypotenuse or a right-angled edge.

[0010] In one embodiment, the height of the busbar within the cross-section is 0.05 mm to 0.2 mm; and / or, the width of the busbar within the cross-section is 2 mm to 5 mm; and / or, the material of the busbar is any one of tin, aluminum, or copper; and / or, the cross-section of the busbar is symmetrically arranged in the width direction.

[0011] In one embodiment, in any two adjacent battery cells, the second electrode of one battery cell is electrically connected to the first electrode of the other battery cell; exemplaryly, the photosensitive structure is any one of a perovskite layer, a cadmium telluride layer, a copper indium gallium selenide layer, and an organic photovoltaic layer; exemplaryly, the peripheral surface of the thin-film photovoltaic cell is further provided with an encapsulating film, which covers the peripheral surface of the battery structure layer and the sealing film layer.

[0012] In a second aspect, the present invention provides a method for fabricating a thin-film photovoltaic cell, comprising: providing a substrate; forming a cell structure layer on one side of the substrate, the cell structure layer including a plurality of cell cells, each cell including a first electrode, a photosensitive structure, and a second electrode sequentially stacked along a direction away from the substrate, wherein at least a portion of the cell cells' second electrodes are electrically connected to the first electrode of an adjacent cell cell; attaching a busbar to the side of the cell structure layer away from the substrate, the busbar being electrically connected to the second electrode of a portion of the cell cells, the bottom surface of the busbar being attached to a corresponding second electrode, and the thickness of the busbar in a cross-section gradually decreasing from the middle region of the cross-section to the two sides of the cross-section; attaching a sealant film to the cell structure layer and the side of the busbar away from the substrate, and then laminating the sealant film to adhere the sealant film to the surface of the busbar and the surface of the cell structure layer; and attaching a cover plate to the side of the sealant film away from the substrate.

[0013] In a third aspect, the present invention provides a photovoltaic module comprising the thin-film photovoltaic cell described above, or a thin-film photovoltaic cell prepared by the method described above.

[0014] In summary, the thin-film photovoltaic cell provided by this invention has at least the following advantages: (1) The flat bottom surface of the busbar is conducive to enhancing the adhesion between the busbar and the second electrode, thereby reducing the contact resistance between the busbar and the corresponding second electrode.

[0015] (2) The busbar has a top surface opposite the bottom surface on the cross-section. The width of the bottom surface is greater than the width of the top surface, which helps to increase the contact area between the busbar and the second electrode and reduce the contact resistance between the busbar and the second electrode.

[0016] (3) The thickness of the busbar in the cross-section gradually decreases from the middle area to the two sides of the cross-section. At this time, the surface of the busbar is smoother. When the sealant film is laminated, the sealant film only needs a small deformation to contact the surface of the busbar, thereby reducing the thickness required for the sealant film and thus reducing the cost. In addition, during the process of laminating the sealant film, the pressure-bearing area of ​​the sealant film at the busbar is larger, and the sealant film is easier to bond with the surface of the busbar, thereby improving the reliability of the bond between the sealant film and the busbar and reducing the possibility of the sealant film falling off the surface of the busbar. At the same time, the thickness of the busbar in the cross-section gradually decreases from the middle area to the two sides of the cross-section, which can also ensure the cross-sectional area of ​​the busbar, take into account the resistance of the busbar, and ensure that the resistance of the busbar is not too small. Attached Figure Description

[0017] Figure 1 The image shown is a planar schematic diagram of a thin-film photovoltaic module.

[0018] Figure 2 The image shown is a cross-sectional view of a thin-film photovoltaic module.

[0019] Figure 3 The image shown is a cross-sectional view of a thin-film photovoltaic module provided in at least one embodiment of the present invention.

[0020] Figure 4 The diagram shown is a schematic diagram of the film layer of the photosensitive structure provided in at least one embodiment of the present invention.

[0021] Figures 5A to 5G Cross-sectional views of some busbars provided for embodiments of the present invention.

[0022] Figure 6 The diagram shows a flowchart of a method for preparing a thin-film photovoltaic module according to at least one embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Substrate; 2. First electrode layer; 21. First isolation trench; 22. First electrode; 3. Photosensitive structure layer; 31. Second isolation trench; 32. Photosensitive structure; 321. Photosensitive layer; 322. Transport layer; 4. Second electrode layer; 41. Third isolation trench; 42. Second electrode; 5. Busbar; 51. Bottom surface; 52. Upper part; 521. Top surface; 522. First side; 53. Lower part; 531. Second side; 6. Sealing film; 7. Encapsulation film; 8. Cover plate; 9. Lead-out electrode; 10. Battery cell. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0026] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. It should be noted that, unless otherwise specified, different features in the embodiments of this application can be combined with each other.

[0027] For ease of understanding, the accompanying diagram shows the mutually orthogonal X, Y, and Z axes. The direction along the X-axis is called the X-direction (also known as the width direction), the direction along the Y-axis is called the Y-direction (also known as the length direction), and the direction along the Z-axis is called the Z-direction (also known as the thickness direction). The Z-direction is the normal direction relative to the plane containing the X and Y directions. Furthermore, the view of various elements parallel to the plane containing the X and Y directions is called a top view. Alternatively, the planes in the X and Y directions can be planes parallel to the display surface of the display panel, and the Z-direction can be a direction parallel to the thickness direction of the display panel.

[0028] For certain elements, terms like "above" or "overhead" are sometimes used when describing the position of an element located in the Z direction, while "below" or "under" is used when describing an element located in the opposite direction. Furthermore, when using terms like "above," "overhead," "below," "under," or "relative" to define the positional relationship between two elements, this includes not only the state where the two elements are directly adjacent but also the state where they are separated by gaps or other elements. Additionally, terms like "first," "second," and "third" are used only for distinguishing descriptions and should not be interpreted as indicating or implying relative importance.

[0029] Figure 1 The image shown is a planar schematic diagram of a thin-film photovoltaic module.

[0030] Figure 2 The image shown is a cross-sectional view of a thin-film photovoltaic module.

[0031] A thin-film photovoltaic cell includes a substrate and a cell structure layer located on one side of the substrate, wherein the cell structure layer is the main component for the photoelectric effect.

[0032] refer to Figure 1 and Figure 2 The battery structure layer includes a first electrode layer 2, a photosensitive structure layer 3, and a second electrode layer 4, sequentially stacked along the direction away from the substrate 1. The first electrode layer 2 has multiple first isolation trenches 21, arranged along the X direction and extending along the Y direction, dividing the first electrode layer 2 into multiple independent first electrodes 22. The photosensitive structure layer 3 has multiple second isolation trenches 31, arranged along the X direction and extending along the Y direction, isolating the photosensitive structure layer 3 into multiple independent photosensitive structures 32. Each second isolation trench 31 corresponds to one first electrode 22 and exposes the corresponding first electrode 22. The second electrode layer 4 covers the second isolation trench 31 and the photosensitive structure layer 3. The second electrode layer 4 has a plurality of third isolation trenches 41, which are arranged along the X direction and extend along the Y direction. The third isolation trenches 41 divide the second electrode layer 4 into a plurality of independent second electrodes 42. Each second electrode 42 corresponds to a photosensitive structure 32 and a first electrode 22, and each second electrode 42 covers a second isolation trench 31.

[0033] The photosensitive structure 32, together with the corresponding first electrode 22 and second electrode 42, constitutes a battery cell 10. In two adjacent battery cells 10, the second electrode 42 of the first battery cell 10 is electrically connected to the first electrode 22 of the second battery cell 10 through a portion filled in the second isolation groove 31, thereby connecting the two adjacent battery cells 10 in series. When multiple battery cells 10 are connected in series in this manner, a larger output power can be output.

[0034] It should be noted that the battery cell 10 extends in the Y direction (i.e., the length direction) and is connected in series in the X direction (i.e., the width direction).

[0035] The battery structure layer has a busbar 5 on the side opposite to the substrate 1. The busbar 5 corresponds to the two outermost battery cells 10 in the X direction, and the busbar 5 is electrically connected to the second electrode 42 of the corresponding battery cell 10. In this way, the photogenerated carriers generated by the series-connected battery cells 10 are combined through the two busbars 5 and then output to the outside.

[0036] The thin-film photovoltaic cell also includes a sealant film 6 and a cover plate 8. The sealant film 6 covers the busbar 5 and the cell structure layer, thereby sealing the side of the busbar 5 and the cell structure layer away from the substrate 1. The cover plate 8 covers the sealant film 6 and is fixed by the sealant film 6. The sealant film 6 is generally encapsulated by lamination, so that the sealant film 6 is in contact with the busbar 5 and the cell structure layer as much as possible, and the sealant film 6 fills into the second isolation groove 31 and the third isolation groove 41 to complete the encapsulation.

[0037] Before lamination, the sealant film 6 is typically laid flat on the surface of the busbar 5 and the battery structure layer. Lamination then causes the sealant film 6 to deform and fill the gaps. After lamination, the side of the sealant film 6 facing away from the substrate 1 is flat. Currently, busbars 5 all use rectangular metal conductors. The sides of the busbar 5 are completely right-angled and relatively high. Therefore, the sealant film 6 needs to generate a large deformation at the sides of the busbar 5 to fill the right-angled edges. Furthermore, the deformation of the sealant film 6 at the right-angled edges of the busbar 5 is localized, thus requiring a thicker sealant film 6 to provide sufficient deformation, which increases the cost of the sealant film 6.

[0038] In addition, the deformation of the sealant film 6 at the bottom of the right-angled edge of the busbar 5 is relatively large, and the pressure during the lamination process is difficult to apply to the right-angled edge of the busbar 5. This results in a poor bonding effect between the right-angled edge of the busbar 5 (especially at the corner where the right-angled edge meets the bottom edge) and the sealant film 6. During subsequent use, the sealant film 6 at this location is prone to rebound and fall off, affecting the overall sealing performance of the thin-film photovoltaic cell.

[0039] Based on this, at least one embodiment of the present invention provides a thin-film photovoltaic cell, comprising: a substrate; a cell structure layer located on one side of the substrate, comprising a plurality of cell cells, wherein each cell cell includes a first electrode, a photosensitive structure, and a second electrode sequentially stacked along a direction away from the substrate, and at least a portion of the second electrodes of the cell cells are electrically connected to the first electrodes of adjacent cell cells; a busbar located on the side of the cell structure layer away from the substrate, electrically connected to the second electrodes of a portion of the cell cells, wherein the bottom surface of the busbar is attached to the corresponding second electrode, and the thickness of the busbar in a cross-section gradually decreases from the middle region of the cross-section to the two sides of the cross-section; and a sealing film covering the busbar and the cell structure layer.

[0040] The following describes some embodiments of the thin-film photovoltaic cells of the present invention through several specific examples.

[0041] Figure 3 The image shown is a cross-sectional view of a thin-film photovoltaic module according to at least one embodiment of the present invention. Additionally, the plan view of the thin-film photovoltaic module provided in the embodiments of the present invention is also shown. Figure 1 resemblance.

[0042] The thin-film photovoltaic cell can be any one of perovskite cells, cadmium telluride cells, copper indium gallium selenide cells, and organic photovoltaic cells.

[0043] refer to Figure 3 A thin-film photovoltaic cell includes a substrate 1, a cell structure layer located on one side of the substrate 1, and a cover plate 8, wherein the cell structure layer is the main component for the photoelectric effect. In a thin-film photovoltaic cell, one side of the substrate 1 serves as the light-incident side, and the other side of the cover plate 8 serves as the backlight side. The substrate 1 is generally made of a transparent material, such as glass.

[0044] The battery structure layer includes a first electrode layer 2, a photosensitive structure layer 3, and a second electrode layer 4, which are sequentially stacked along the direction away from the substrate 1. The material of the first electrode layer 2 can be a transparent conductive material, such as ITO, IWO, IZO, FTO, and other composite transparent conductive materials such as metals and conductive organic compounds. The material of the second electrode layer 4 can be a metal or conductive metal oxide such as ITO, IWO, IZO, FTO, Ag, or Cu.

[0045] The first electrode layer 2 has multiple first isolation trenches 21 arranged along the X direction and extending along the Y direction, dividing the first electrode layer 2 into multiple independent first electrodes 22. The photosensitive structure layer 3 has multiple second isolation trenches 31 arranged along the X direction and extending along the Y direction, dividing the photosensitive structure layer 3 into multiple independent photosensitive structures 32. The second electrode layer 4 has multiple third isolation trenches 41 arranged along the X direction and extending along the Y direction, dividing the second electrode layer 4 into multiple independent second electrodes 42. Each photosensitive structure 32 corresponds to one first electrode 22 and one second electrode 42, and the photosensitive structure 32, together with its corresponding first electrode 22 and second electrode 42, constitutes a battery cell 10. For example, the third isolation trench 41 can also extend in the Z direction to the substrate 1, penetrating the photosensitive structure layer 3. For example, the photosensitive structure 32 can be any one of a perovskite layer, a cadmium telluride layer, a copper indium gallium selenide layer, and an organic photovoltaic layer.

[0046] The battery cells 10 are connected in series and / or in parallel, wherein at least some of the second electrodes 42 of the battery cells 10 are electrically connected to the first electrode 22 of an adjacent battery cell 10. For example, in any two adjacent battery cells 10, the second electrode 42 of one battery cell 10 is electrically connected to the first electrode 22 of the other battery cell 10, thereby achieving series connection of all battery cells 10 in the X direction.

[0047] The photosensitive structure 32 includes a photosensitive layer 321 and transport layers 322 located on both sides of the photosensitive layer 321. The first electrode 22 and the second electrode 42 are electrically connected to different transport layers 322, respectively. The transport layers 322 located on both sides of the photosensitive layer 321 are a hole transport layer 322 and an electron transport layer 322, respectively. The hole transport layer 322 can be a metal oxide such as NiOx, NiOx / Mg, NiOx / Cu, ZnO, or its metal-doped compounds, and the electron transport layer 322 can be one or more combinations of C60, PCBM, SnO2, and other common electron transport layers 322.

[0048] Figure 4 The diagram shown is a schematic diagram of the film layer of the photosensitive structure provided in at least one embodiment of the present invention.

[0049] For example, refer to Figure 4 The photosensitive structure 32 may also include multiple photosensitive layers 321, each photosensitive layer 321 having a transmission layer 322 on both sides, and the transmission layers 322 on the same side of each photosensitive layer 321 having the same type (e.g., both being hole transmission layers 322 or electron transmission layers 322), while the transmission layers 322 on both sides of each photosensitive layer 321 having different types (i.e., being hole transmission layers 322 and electron transmission layers 322, respectively).

[0050] The battery structure layer has a busbar 5 and a sealing film 6 on the side facing away from the substrate 1. The busbar 5 is electrically connected to the second electrode 42 of part of the battery cell 10, and the sealing film 6 covers the busbar 5 and the battery structure layer. The cover plate 8 is located on the side of the sealing film 6 facing away from the substrate 1. For example, the material of the sealing film 6 can be POE (Polyolefin Elastomer).

[0051] The sealing film 6 and the cover plate 8 are also provided with lead-out electrodes 9. The lead-out electrodes 9 penetrate the cover plate 8 and the sealing film 6 along the Z direction and correspond to and are electrically connected to the bus bar 5, thereby leading the bus bar 5 outward for easy electrical connection.

[0052] The bottom surface of the busbar 5 is attached to the corresponding second electrode 42, which helps to reduce the contact resistance between the busbar 5 and the corresponding second electrode 42. For example, the bottom surface of the busbar 5 is flat. Simultaneously, the thickness of the busbar 5 within its cross-section gradually decreases from the middle region to the two sides. That is, the busbar 5 is thickest in the middle region of its cross-section, and the thickness gradually decreases from the middle to the sides. With this design, the surface of the busbar 5 is smoother. When the sealant film 6 is laminated, the sealant film 6 only requires a smaller deformation to contact the surface of the busbar 5, thereby reducing the required thickness of the sealant film 6 and thus reducing costs. Furthermore, during the lamination of the sealant film 6, the pressure-bearing area of ​​the sealant film 6 at the busbar 5 is larger, making it easier for the sealant film 6 to bond with the surface of the busbar 5, thereby improving the reliability of the bond between the sealant film 6 and the busbar 5 and reducing the possibility of the sealant film 6 detaching from the surface of the busbar 5. Meanwhile, the thickness of the busbar 5 gradually decreases from the middle area to the two sides of the cross-section, which can also ensure the cross-sectional area of ​​the busbar 5 and take into account the resistance of the busbar 5, ensuring that the resistance of the busbar is not too small.

[0053] Normally, reference Figures 5A to 5G The height h of the busbar 5 within the cross-section is 0.05mm to 0.2mm, such as 0.05mm, 0.1mm, 0.15mm, 0.2mm, etc.; the width d of the busbar 5 within the cross-section is 2mm to 5mm, such as 2mm, 3mm, 4mm, 5mm, etc. Of course, the height h and width d of the busbar 5 within the cross-section can also be adjusted according to product requirements. The material of the busbar 5 can be any of tin, aluminum, or copper, and can also be other low-resistance conductive materials. For example, the busbars 5 are symmetrically arranged in the X direction (i.e., the width direction of the cross-section of the busbar 5), so that the bonding force between the sealant layer and the busbar 5 on both sides is approximately the same, and the deformation during the lamination process is also approximately the same.

[0054] refer to Figure 5A The busbar 5 includes an upper part 52, which has a top surface 521 opposite to the bottom surface 51. The width of the bottom surface 51 is greater than or equal to the width of the top surface 521, which helps to increase the contact area between the busbar 5 and the second electrode 42 and reduce the contact resistance between the busbar 5 and the second electrode 42. For example, the orthographic projection of the busbar 5 onto the bottom surface 51 coincides with the bottom surface 51, that is, the bottom surface 51 is the widest surface of the busbar 5 in cross-section, which can maximize the contact area between the busbar 5 and the second electrode 42.

[0055] For example, refer to Figure 5AThe top surface 521 of the busbar 5 is parallel to the bottom surface 51. The upper part 52 of the busbar 5 also has a first side 522, which is inclined and located on both sides of the top surface 521. This ensures that the thickness of the busbar 5 gradually decreases from the middle region to the two sides of the cross-section. Among busbars 5 of the same height and width, the busbar 5 with a top surface 521 that is parallel to the bottom surface 51 can have a larger cross-sectional area, thereby reducing the resistance of the busbar 5. In this case, the cross-section of the busbar 5 can be trapezoidal.

[0056] For example, refer to Figure 5B and Figure 5C The top surface 521 of the upper part 52 of the busbar 5 is curved, which increases the smoothness of the top surface 521 of the busbar 5 and helps to improve the reliability of the bonding between the busbar 5 and the sealing film 6. The shape of the top surface 521 of the busbar 5 in cross-section can be semi-circular or semi-elliptical.

[0057] For example, refer to Figure 5D The upper part 52 of the busbar 5 includes only the first side 522, which is inclined. The two first side 522 intersect at the end away from the bottom surface 51. The thickness of the cross-section of the busbar 5 at the first side 522 gradually decreases from the middle region to the two sides. At this time, the cross-section of the busbar 5 can be triangular.

[0058] It should be noted that the busbar 5 may only include the upper part 52, in which case the first side 522 is adjacent to the bottom surface 51, and the shape of the busbar may be as described above, such as trapezoidal, triangular, semi-circular, semi-elliptical, etc. Of course, for reference... Figure 5E The busbar 5 may also include a lower part 53, which includes a second side 531 adjacent to the bottom surface 51. The second side 531 may be a hypotenuse or a right-angled side. When the second side 531 is a hypotenuse, the angle between the second side 531 and the bottom surface 51 is an acute angle; when the second side 531 is a right-angled side, the second side 531 is perpendicular to the bottom surface 51.

[0059] The lower part 53 of the busbar 5 can be combined with the upper part 52 of any shape. For example, see reference. Figures 5E to 5G When the second side 531 of the lower part 53 of the busbar 5 is a right-angled side, the lower part 53 of the busbar 5 is rectangular. At this time, the upper part 52 of the busbar 5 can be any one of the following: semi-circle, semi-ellipse, trapezoid, triangle, etc.

[0060] It should be noted that when the second side 531 of the lower part 53 of the busbar 5 is a right-angled side, the right-angled side reduces the maximum width of the busbar 5 in the cross-section. Compared to the case without a right-angled side, for the same width of the busbar 5, the busbar 5 with a right-angled side has a larger cross-sectional area, which is beneficial to reducing the resistance of the busbar 5. In addition, the height of the right-angled side is generally less than half the height of the busbar 5 to reduce the deformation of the sealing film 6 at the right-angled side, thereby thinning the sealing film 6 and improving the reliability of the adhesion between the sealing film 6 and the right-angled side.

[0061] refer to Figure 3 The thin-film photovoltaic cell also has an encapsulating film 7 on its peripheral surface. The encapsulating film 7 covers the peripheral surface of the cell structure layer and the sealing film 6 layer, thus encapsulating the peripheral surface of the thin-film photovoltaic cell. For example, the cover plate 8 and the substrate 1 extend beyond the cell structure layer and the sealing film 6 layer in both the X and Y directions, providing space for the installation of the encapsulating film 7. For example, the material of the encapsulating film 7 can be butyl rubber.

[0062] In summary, the thin-film photovoltaic cells provided in the embodiments of the present invention have at least the following advantages: (1) The bottom surface of the busbar 5 is flat, which helps to enhance the adhesion between the busbar 5 and the second electrode 42, thereby reducing the contact resistance between the busbar 5 and the corresponding second electrode 42.

[0063] (2) The busbar 5 has a top surface opposite to the bottom surface on the cross-section. The width of the bottom surface is greater than the width of the top surface, which helps to increase the contact area between the busbar 5 and the second electrode 42 and reduce the contact resistance between the busbar 5 and the second electrode 42.

[0064] (3) The thickness of the busbar 5 in the cross-section gradually decreases from the middle area to the two sides of the cross-section. At this time, the surface of the busbar 5 is smoother. When the sealant film 6 is laminated, the sealant film 6 only needs a small deformation to contact the surface of the busbar 5, thereby reducing the required thickness of the sealant film 6 and thus reducing the cost. In addition, during the lamination of the sealant film 6, the pressure-bearing area of ​​the sealant film 6 at the busbar 5 is larger, and the sealant film 6 is easier to bond with the surface of the busbar 5, thereby improving the reliability of the bond between the sealant film 6 and the busbar 5 and reducing the possibility of the sealant film 6 falling off the surface of the busbar 5. At the same time, the thickness of the busbar 5 in the cross-section gradually decreases from the middle area to the two sides of the cross-section, which can also ensure the cross-sectional area of ​​the busbar 5, take into account the resistance of the busbar 5, and ensure that the resistance of the busbar is not too small.

[0065] This invention provides a method for fabricating a thin-film photovoltaic cell, comprising: providing a substrate; forming a cell structure layer on one side of the substrate, the cell structure layer including a plurality of cell cells, each cell including a first electrode, a photosensitive structure, and a second electrode stacked sequentially along a direction away from the substrate, wherein at least a portion of the cell cells' second electrodes are electrically connected to the first electrode of an adjacent cell cell; attaching a busbar to the side of the cell structure layer away from the substrate, the busbar being electrically connected to the second electrode of a portion of the cell cells, the bottom surface of the busbar being attached to a corresponding second electrode, and the thickness of the busbar in a cross-section gradually decreasing from the middle region to the two sides of the cross-section; attaching a sealant film to the cell structure layer and the side of the busbar away from the substrate, and then laminating the sealant film to adhere it to the surface of the busbar and the surface of the cell structure layer; and attaching a cover plate to the side of the sealant film away from the substrate.

[0066] The following is for reference Figure 3 as well as Figure 6 This paper introduces the preparation methods of thin-film photovoltaic cells.

[0067] S100, Provide substrate 1. For example, the material of substrate 1 can be glass.

[0068] S200, A battery structure layer is formed on one side of the substrate 1.

[0069] The battery structure layer includes multiple battery cells 10. Each battery cell 10 includes a first electrode 22, a photosensitive structure 32, and a second electrode 42, which are sequentially stacked along the direction away from the substrate 1. At least some of the second electrodes 42 of the battery cells 10 are electrically connected to the first electrode 22 of an adjacent battery cell 10.

[0070] A first electrode layer 2 is formed on one side of the substrate 1, and a first isolation trench 21 is formed within the first electrode layer 2. Multiple first isolation trenches 21 are arranged along the X direction and extend along the Y direction, dividing the first electrode layer 2 into multiple independent first electrodes 22. For example, the first isolation trenches 21 are formed using a laser etching process. For example, the material of the first electrode layer 2 can be a transparent conductive material, such as ITO, IWO, IZO, FTO, and other composite transparent conductive materials such as metals and conductive organic compounds.

[0071] A photosensitive structure layer 3 is formed on the side of the first electrode layer 2 facing away from the substrate 1, and a plurality of second isolation trenches 31 are formed within the photosensitive structure layer 3. The plurality of second isolation trenches 31 are arranged along the X direction and extend along the Y direction, dividing the photosensitive structure layer 3 into a plurality of independent photosensitive structures 32, each photosensitive structure 32 being electrically connected to a first electrode 22. For example, the plurality of independent photosensitive structures 32 have the same width in the X direction. For example, the second isolation trenches 31 are formed using a laser etching process. For example, each first electrode 22 is exposed by a second isolation trench 31.

[0072] A second electrode layer 4 is formed on the side of the photosensitive structure layer 3 facing away from the substrate 1, and a third isolation trench 41 is formed within the second electrode layer 4. The second electrode layer 4 covers the second isolation trench 31 and the photosensitive structure 32. Multiple third isolation trenches 41 are arranged along the X direction and extend along the Y direction. The third isolation trenches 41 penetrate the second electrode layer 4 in the Z direction, dividing the second electrode layer 4 into multiple independent second electrodes 42. Each second electrode 42 is electrically connected to a photosensitive structure 32. For example, the third isolation trench 41 is formed using a laser etching process. For example, the material of the second electrode layer 4 can be a metal or conductive metal oxide such as ITO, IWO, IZO, FTO, Ag, or Cu.

[0073] When each first electrode 22 is exposed by a second isolation groove 31, each second electrode 42 covers a second isolation groove 31, and the second isolation groove 31 covered by the second electrode 42 in one battery cell 10 exposes the first electrode 22 in the adjacent battery cell 10. At this time, the second electrode 42 in one battery cell 10 can be electrically connected to the first electrode 22 of the adjacent battery cell 10, connecting the two adjacent battery cells 10 in series.

[0074] S300, A busbar 5 is attached to the side of the battery structure layer away from the substrate 1.

[0075] The busbar 5 is electrically connected to the second electrode 42 of part of the battery cell 10. The bottom surface of the busbar 5 is attached to the corresponding second electrode 42, and the thickness of the busbar 5 in the cross-section gradually decreases from the middle region of the cross-section to the two sides of the cross-section.

[0076] The bottom surface of the busbar 5 is attached to the corresponding second electrode 42, which helps to reduce the contact resistance between the busbar 5 and the corresponding second electrode 42.

[0077] Typically, the height of busbar 5 within its cross-section is 0.05mm to 0.2mm, such as 0.05mm, 0.1mm, 0.15mm, 0.2mm, etc.; the width of busbar 5 within its cross-section is 2mm to 5mm, such as 2mm, 3mm, 4mm, 5mm, etc. Of course, the height and width of busbar 5 within its cross-section can also be adjusted according to product requirements. The material of busbar 5 can be any of tin, aluminum, or copper, and can also be other low-resistance conductive materials. For example, busbars 5 can be symmetrically arranged in the X direction (i.e., the width direction of the cross-section of busbar 5).

[0078] refer to Figure 5A The busbar 5 includes an upper part 52, which has a top surface 521 opposite to the bottom surface 51. The width of the bottom surface 51 is greater than or equal to the width of the top surface 521, which helps to increase the contact area between the busbar 5 and the second electrode 42 and reduce the contact resistance between the busbar 5 and the second electrode 42. For example, the orthographic projection of the busbar 5 onto the bottom surface 51 coincides with the bottom surface 51, that is, the bottom surface 51 is the widest surface of the busbar 5 in cross-section, which can maximize the contact area between the busbar 5 and the second electrode 42.

[0079] For example, refer to Figure 5A The top surface 521 of the busbar 5 is parallel to the bottom surface 51. The upper part 52 of the busbar 5 also has a first side 522, which is inclined and located on both sides of the top surface 521. This ensures that the thickness of the busbar 5 gradually decreases from the middle region to the two sides of the cross-section. Among busbars 5 of the same height and width, the busbar 5 with a top surface 521 that is parallel to the bottom surface 51 can have a larger cross-sectional area, thereby reducing the resistance of the busbar 5. In this case, the cross-section of the busbar 5 can be trapezoidal.

[0080] For example, refer to Figure 5B and Figure 5C The top surface 521 of the upper part 52 of the busbar 5 is curved, which increases the smoothness of the top surface 521 of the busbar 5 and helps to improve the reliability of the bonding between the busbar 5 and the sealing film 6. The shape of the top surface 521 of the busbar 5 in cross-section can be semi-circular or semi-elliptical.

[0081] For example, refer to Figure 5D The upper part 52 of the busbar 5 includes only the first side 522, which is inclined. The two first side 522 intersect at the end away from the bottom surface 51. The thickness of the cross-section of the busbar 5 at the first side 522 gradually decreases from the middle region to the two sides. At this time, the cross-section of the busbar 5 can be triangular.

[0082] It should be noted that the busbar 5 may only include the upper part 52, in which case the first side 522 is adjacent to the bottom surface 51, and the shape of the busbar may be as described above, such as trapezoidal, triangular, semi-circular, semi-elliptical, etc. Of course, for reference... Figure 5E The busbar 5 may also include a lower part 53, which includes a second side 531 adjacent to the bottom surface 51. The second side 531 may be a hypotenuse or a right-angled side. When the second side 531 is a hypotenuse, the angle between the second side 531 and the bottom surface 51 is an acute angle; when the second side 531 is a right-angled side, the second side 531 is perpendicular to the bottom surface 51.

[0083] The lower part 53 of the busbar 5 can be combined with the upper part 52 of any shape. For example, see reference. Figures 5E to 5G When the second side 531 of the lower part 53 of the busbar 5 is a right-angled side, the lower part 53 of the busbar 5 is rectangular. At this time, the upper part 52 of the busbar 5 can be any one of the following: semi-circle, semi-ellipse, trapezoid, triangle, etc.

[0084] S400, A sealant film 6 is attached to the battery structure layer and the side of the busbar 5 facing away from the substrate 1, and then the sealant film 6 is laminated.

[0085] After lamination, the sealant film 6 deforms, adhering to the surface of the busbar 5 and the battery structure layer. Because the thickness of the busbar 5 gradually decreases from the center to the sides, its surface is smoother. With the sealant film 6 laminated, it requires only a small deformation to contact the busbar 5 surface, reducing the required thickness and cost. Furthermore, the lamination process increases the pressure-bearing area of ​​the sealant film 6 at the busbar 5, making it easier for it to bond with the surface, improving the reliability of the bond and reducing the likelihood of detachment. Simultaneously, the gradual decrease in thickness from the center to the sides of the busbar 5 ensures a suitable cross-sectional area, balancing the resistance of the busbar and preventing excessively low resistance in the busbar.

[0086] For example, the material of the sealant film 6 can be POE (Polyolefin Elastomer).

[0087] S500, A cover plate 8 is attached to the side of the sealing film 6 away from the substrate 1. After attaching the cover plate 8, an opening can be made in the cover plate 8 and the sealing film 6 to expose the busbar 5, and then an lead electrode 9 is formed in the opening.

[0088] S600, an encapsulating film 7 is formed on the peripheral surface of the battery structure layer and the sealing film 6.

[0089] For example, the cover plate 8 and the substrate 1 extend beyond the battery structure layer and the sealing film 6 layer in both the X and Y directions, providing space for the installation of the encapsulation film 7. For example, the material of the encapsulation film 7 can be butyl rubber.

[0090] In some possible implementations, this application also provides a photovoltaic module, which includes the thin-film photovoltaic cell described in this application, or a thin-film photovoltaic cell prepared by the method described in this application.

[0091] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A thin-film photovoltaic cell, characterized in that, include: substrate; A battery structure layer is located on one side of the substrate and includes multiple battery cells. Each battery cell includes a first electrode, a photosensitive structure, and a second electrode stacked sequentially in a direction away from the substrate. At least a portion of the second electrode of the battery cell is electrically connected to the first electrode of an adjacent battery cell. A busbar is located on the side of the battery structure layer away from the substrate and is electrically connected to the second electrode of a portion of the battery cell. The bottom surface of the busbar is attached to the corresponding second electrode, and the thickness of the busbar in the cross-section gradually decreases from the middle region of the cross-section to the two sides of the cross-section. A sealing film covering the busbar and the battery structure layer.

2. The thin-film photovoltaic cell according to claim 1, characterized in that, The bottom surface of the busbar is a plane; Preferably, the busbar includes an upper part, the upper part having a top surface opposite the bottom surface, and the width of the bottom surface being greater than or equal to the width of the top surface; Preferably, the orthographic projection of the busbar on the bottom surface coincides with the bottom surface.

3. The thin-film photovoltaic cell according to claim 2, characterized in that, The top surface is a plane and parallel to the bottom surface. The upper part also has a first side, which is inclined and located on both sides of the top surface. Preferably, the cross-section of the busbar is trapezoidal.

4. The thin-film photovoltaic cell according to claim 2, characterized in that, The top surface is a curved surface; Preferably, the top surface of the busbar is semi-circular or semi-elliptical in cross-section.

5. The thin-film photovoltaic cell according to claim 1, characterized in that, The busbar includes an upper part, the upper part includes a first side, the first side is inclined, the two first side intersect at one end away from the bottom surface, and the thickness of the cross section of the busbar at the first side gradually decreases from the middle region to the two side regions. Preferably, the cross-section of the busbar is triangular.

6. The thin-film photovoltaic cell according to claim 1, characterized in that, The busbar also includes a lower part, which includes a second side that is adjacent to the bottom surface. The second side is either a hypotenuse or a right-angled side.

7. The thin-film photovoltaic cell according to claim 1, characterized in that, The height of the busbar within the cross-section is 0.05 mm to 0.2 mm; and / or, The width of the busbar within the cross-section is 2mm to 5mm; and / or, The busbar is made of any one of tin, aluminum, or copper; and / or, The cross-section of the busbar is symmetrically arranged in the width direction.

8. The thin-film photovoltaic cell according to claim 1, characterized in that, In any two adjacent battery cells, the second electrode of one battery cell is electrically connected to the first electrode of the other battery cell; Preferably, the photosensitive structure is any one of a perovskite layer, a cadmium telluride layer, a copper indium gallium selenide layer, and an organic photovoltaic layer; Preferably, the peripheral surface of the thin-film photovoltaic cell is further provided with an encapsulating film, which covers the peripheral surface of the cell structure layer and the sealing film layer.

9. A method for preparing a thin-film photovoltaic cell, characterized in that, include: Provide substrate; A battery structure layer is formed on one side of the substrate. The battery structure layer includes a plurality of battery cells. Each battery cell includes a first electrode, a photosensitive structure, and a second electrode stacked sequentially in a direction away from the substrate. At least a portion of the second electrode of the battery cell is electrically connected to the first electrode of an adjacent battery cell. A busbar is attached to the side of the battery structure layer away from the substrate. The busbar is electrically connected to the second electrode of a portion of the battery cell. The bottom surface of the busbar is attached to the corresponding second electrode. The thickness of the busbar in the cross-section gradually decreases from the middle region of the cross-section to the two sides of the cross-section. A sealant film is applied to the battery structure layer and the side of the busbar facing away from the substrate, and then the sealant film is laminated to adhere to the surface of the busbar and the surface of the battery structure layer. A cover plate is attached to the side of the sealant film facing away from the substrate.

10. A photovoltaic module, characterized in that, Includes the thin-film photovoltaic cell as described in any one of claims 1 to 8, or the thin-film photovoltaic cell prepared by the method described in claim 9.

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