Solar cells and photovoltaic modules

Abstract

This application provides a solar cell and photovoltaic module, belonging to the field of solar cells. The solar cell comprises a solar cell body, at least one copper electrode located on at least one surface of the cell body, and at least two epitaxial regions. The copper electrode comprises a main region, wherein two epitaxial regions are adjacent to the main region and extend outward from both sides of the main region. At least one epitaxial region comprises a plurality of copper nanoparticles, wherein the copper nanoparticles are non-spherical. Based on improvements to the copper nanoparticle structure within the epitaxial region, this application, when applied to solar cells, exhibits superior light utilization efficiency, thereby improving cell performance.

Description

Technical Field

[0001] The present application relates to the field of solar cells, and in particular, to a solar cell and a photovoltaic module. Background Art

[0002] Solar energy is one of the important renewable energy sources, with the characteristics of being pollution-free, renewable and having huge reserves.

[0003] Photovoltaic power generation is an environmentally friendly renewable energy technology that converts sunlight into electricity through solar cells. As an important renewable energy generation method, photovoltaic power generation has experienced rapid growth. This development has placed higher demands on battery costs, with battery metallization costs accounting for a significant portion of this cost. Conductive silver paste is widely used in solar cells to collect and transport charge carriers. However, the high cost of silver metal has led to attempts to replace it with other metals. Copper, a base metal with comparable conductivity to silver, offers lower costs.

[0004] However, copper electrodes still suffer from low light utilization efficiency. Designing copper electrodes to further improve light utilization efficiency has become an urgent issue. Summary of the Invention

[0005] In view of this, in order to at least partially solve the above-mentioned technical problems, the present application provides a solar cell and a photovoltaic module.

[0006] According to an embodiment of one aspect of the present application, a solar cell is provided, comprising a cell body, at least one copper electrode located on at least one surface of the cell body, and at least two epitaxial regions, wherein the copper electrode comprises a main body region, wherein two epitaxial regions are adjacent to the main body region and extend outward from both sides of the main body region; at least one epitaxial region has a plurality of copper nanoparticles; wherein the copper nanoparticles are non-spherical copper nanoparticles.

[0007] According to another embodiment of the present application, a photovoltaic assembly is provided, comprising the aforementioned solar cell and a plurality of electrical connection lines, wherein the plurality of electrical connection lines electrically connect adjacent solar cells.

[0008] According to the solar cell of the present application, the epitaxial region includes multiple non-spherical copper nanoparticles. When formed on the solar cell, the non-spherical copper nanoparticles reflect some of the light incident on the epitaxial region back into the cell body, resulting in better light utilization and improved performance. Furthermore, the presence of the epitaxial region enhances the bonding strength between the copper electrode and the cell body, establishing more reliable and reliable electron conduction paths between the copper electrode and the cell body, helping to reduce interfacial resistance and improve the overall conductivity and reliability of the cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other objects, features and advantages of the present application will become more apparent through the following description of the embodiments of the present application with reference to the accompanying drawings.

[0010] Figure 1 A schematic cross-sectional view of a copper electrode of a solar cell according to an embodiment of the present application is shown;

[0011] Figure 2 A scanning electron microscope image of an epitaxial region of a solar cell according to an embodiment of the present application is shown;

[0012] Figure 3 Shows a scanning electron microscope and elemental analysis diagram of the epitaxial region of a solar cell according to an embodiment of the present application;

[0013] Figure 4 Shown Figure 3 A partial enlarged view of Figure a.

[0014] In the accompanying drawings, the meanings of the reference numerals are as follows:

[0015] 1-Copper electrode;

[0016] 11- Main area;

[0017] 111-main body;

[0018] 112-marginal part;

[0019] 2- epitaxial region;

[0020] 3-Battery body. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present application. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present application.

[0022] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0023] When expressions such as “at least one of A, B, and C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, “a system having at least one of A, B, and C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.). When expressions such as “at least one of A, B, or C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, “a system having at least one of A, B, or C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.).

[0024] In recent years, solar cells have been widely used due to their high photoelectric conversion efficiency. Conductive silver paste is currently widely used to prepare the electrodes in solar cells. The high cost of silver contributes to the overall high cost of solar cells. Since copper also has high conductivity, related technologies have often attempted to at least partially replace silver with copper or silver-clad copper.

[0025] During the implementation of the present invention, it was discovered that a certain amount of solvent was required to ensure smooth copper paste printing. During the copper paste printing process, the flow of solvent drives the migration of the copper paste, which, after solidification, forms epitaxial regions on both sides of the electrode main area. However, the copper nanoparticles in the epitaxial regions are mostly spherical, which has a limited effect on improving light utilization.

[0026] Furthermore, in order to solve the above-mentioned problems, during the printing process, copper precursor compounds are used for printing and non-spherical copper nanoparticles are formed in the epitaxial region after sintering. When sunlight is incident on the non-spherical copper nanoparticles, the light is further effectively reflected and / or scattered into the battery body, thereby improving the light utilization rate; and the presence of the epitaxial region improves the bonding strength between the copper electrode and the battery body.

[0027] Specifically, according to an embodiment of one aspect of the present application, a solar cell is provided, comprising a cell body, at least one copper electrode located on at least one surface of the cell body, and at least two epitaxial regions. Figure 1 FIG1 shows a cross-sectional schematic diagram of a copper electrode of a solar cell according to an embodiment of the present application. Figure 1 As shown, the copper electrode 1 includes a main region 11, wherein two epitaxial regions 2 are adjacent to the main region 11, and the epitaxial regions 2 extend outward from both sides of the main region 11; at least one epitaxial region 2 has multiple copper nanoparticles; the copper nanoparticles are non-spherical copper nanoparticles.

[0028] In some embodiments, as Figure 1 As shown, the main region 11 includes a main portion 111 and edge portions 112 located on both sides of the main portion 111. The epitaxial region 2 contacts and extends outward from the edge portions 112. When printing and preparing the electrode, due to the influence of gravity, the edge portions 112 formed have a certain width.

[0029] The interface between the main region 11 and the epitaxial region 2 can be determined using a scanning electron microscope. Because the displacement of the epitaxial region 2 is caused by the flow of copper nanoparticles driven by the solvent, the copper slurry coverage height also varies significantly between the epitaxial region 2 and the main region 11. Scanning electron microscope images show a distinct color difference between the epitaxial region 2 and the main region 11, creating a clear boundary. Furthermore, the epitaxial region 2 and the adjacent non-electrode region (i.e., the area outside the epitaxial region 2) also exhibit a distinct color difference. Figure 2 The scanning electron microscope image of the epitaxial region of the solar cell according to the embodiment of the present application is shown. Figure 2 As shown, it can be seen that the dark area on the left side of the dotted line is the epitaxial region 2.

[0030] According to an embodiment of the present application, during the process of printing copper paste to prepare a copper electrode, the solvent in the copper paste carries copper precursor compound particles (for example, cuprous hydride nanoparticles) and diffuses on both sides of the main region 11 of the copper electrode. After solidification and sintering, the solvent evaporates to form an epitaxial region 2 having non-spherical copper nanoparticles. Non-spherical copper nanoparticles have multi-dimensional reflective interfaces, and the normal directions of different surfaces are different, which can reflect incident light to different angles. When light is irradiated to a solar cell, part of the light is reflected by the copper nanoparticles back to the battery body 3 for reuse, thereby improving light utilization efficiency. At the same time, the thickness of the epitaxial region 2 is relatively thin, so that light can pass through the epitaxial region 2 and enter the battery body 3 by reflection and / or scattering, further improving the light utilization efficiency of the battery body 3.

[0031] In addition, the epitaxial region 2 extends in a direction away from the main region 11 , and because there are a plurality of non-spherical copper nanoparticles, it helps to reflect more incident light at different angles to the battery body 3 .

[0032] For example, oblique incident light can be reflected by one non-spherical copper nanoparticle to another copper nanoparticle, and then reflected by another non-spherical copper nanoparticle into the battery body 3. Alternatively, vertical incident light can be reflected by the side of the non-spherical copper nanoparticle and enter the active layer of the battery body 3, such as the transparent conductive oxide layer (TCO layer), at an oblique angle, extending the propagation distance of light within the battery body 3 and improving the light absorption rate.

[0033] It should be noted that the term "spherical" often refers to a geometric shape that is roughly (or nearly) spherical, such as a sphere or ellipsoid. Non-spherical copper nanoparticles exhibit a certain degree of anisotropy. Their unique surface morphology disrupts the optical symmetry of spherical particles, transforming the conventional light path from a single incident-escape to one with one or more reflections and absorptions. Combined with the provision of the epitaxial region 2, this strengthens the bond between the copper electrode 1 and the cell body 3, allowing the subsequently fabricated solar cell to achieve both high electrical conductivity and mechanical stability while improving light utilization. This provides a new approach to base metallization in solar cells.

[0034] It should be noted that non-spherical copper nanoparticles have geometric asymmetry. The shapes of non-spherical copper nanoparticles can be, for example, rods, cubes, triangular pieces, polyhedrons, etc. The above shapes break the symmetry and have different curvature radii, edges, and sharp angles, making the scattering and / or reflection directions more random and diverse. Light can be scattered and / or reflected to a wider angle range, such as sideways. Such multi-directional, wide-angle scattering and / or reflection makes it more likely that light that might have been directly reflected and escaped will be redirected to the interior of the battery body, thereby improving light utilization.

[0035] Furthermore, the non-spherical copper nanoparticles are located on the epitaxial regions 2 extending from both sides of the main region 11, as shown in FIG. Figure 1 As shown, the non-spherical copper nanoparticles are placed very close to the cell body 3, especially the copper electrode 1 located at the edge of the cell. Such an epitaxial region 2 is particularly close to the edge or side areas of the cell body 3, further improving light utilization. Typically, in conventional solar cells, such areas, especially the edge areas, are prone to incident light loss. In this case, the non-spherical nanoparticles in the epitaxial region 2 efficiently scatter light that might otherwise escape from the side of the cell back into the cell body 3, further reducing reflection losses and extending the effective propagation path of photons within the light absorption layer of the cell body 3 (such as the TCO layer).

[0036] Based on the above situation, more incident light energy is effectively utilized by the solar cell and converted into electrical energy, which improves the overall light utilization and photoelectric conversion efficiency of the subsequent solar cell, helps to capture large-angle incident light and reduce edge loss.

[0037] In some embodiments, the copper nanoparticles are polyhedral copper nanoparticles or rotator copper nanoparticles. Polyhedral copper nanoparticles have relatively sharp edges and a multi-faceted structure. Based on the special morphology of the polyhedral copper nanoparticles, the curvature radius of the corners and edges is smaller, which helps to couple more photon energy into the battery body 3, improves the light absorption efficiency, and can match the absorption requirements of the battery across the entire wavelength range. The rotator copper nanoparticles have an anisotropic structure, which helps to achieve selective control of incident light of different wavelengths. The surface curvature of the rotator copper nanoparticles changes continuously, reducing the reflection loss that may be caused by the abrupt interface and improving the capture efficiency of large-angle incident light.

[0038] For example, the polyhedral copper nanoparticles may be at least one of a cube, an octahedron, a prism, and a truncated pyramid. The rotating copper nanoparticles may be at least one of a rod, a disk, a tree, or a truncated pyramid.

[0039] In some embodiments, a polyhedral copper nanoparticle has at least four surfaces. A polyhedral copper nanoparticle can be understood as a three-dimensional structure surrounded by multiple planar polygons, whose components primarily include planes, edges, and vertices. When a polyhedral copper nanoparticle has four surfaces, it can be, for example, a regular tetrahedron. A solid-of-rotation copper nanoparticle is a solid formed by rotating a planar figure around an axis of rotation, and its surface includes at least one of a curved surface and / or a flat surface. A solid-of-rotation copper nanoparticle has at least two surfaces. When a solid-of-rotation copper nanoparticle has two surfaces, it can be, for example, at least one of a cone or a rod (cylinder).

[0040] For example, the number of surfaces of a polyhedral copper nanoparticle can be 4, 5, 6, 7, or 8, which is not limited in this application. The number of surfaces of a rotating copper nanoparticle can be 2, 3, or 4, which is not limited in this application.

[0041] In some embodiments, the contour lines of the copper nanoparticle surface include at least one of a straight line and an arc. The contour lines of the copper nanoparticle surface can be understood as boundary characteristic lines that describe the geometric shape of the copper nanoparticle surface at a microscopic scale. The contour lines can be observed by observing the edge of the particle using a scanning electron microscope image or by extracting a height change curve using an atomic force microscope.

[0042] Figure 3 The scanning electron microscope and elemental analysis diagram of the epitaxial region of the solar cell according to the embodiment of the present application are shown. Figure 4 Shown Figure 3 A partial enlarged view of Figure a.

[0043] like Figure 4As shown, it can be seen that the shape of the surface of the copper nanoparticles includes any one of a triangle, a trapezoid, a rhombus, a square, a rectangle, an arch, and a hexagon. It is understood that the vertices of the above shapes may have chamfers. For example, the surface of the copper nanoparticles may be a triangle, a triangle with chamfers at the vertices, a trapezoid, a trapezoid with chamfers at the vertices, a rhombus, a rhombus with chamfers at the vertices, a square, a square with chamfers at the vertices, a rectangle, a rectangle with chamfers at the vertices, an arch, an arch with chamfers at the vertices, a hexagon, a hexagon with chamfers at the vertices, etc., and this application does not specifically limit this.

[0044] In some embodiments, the average particle size of the copper nanoparticles is 10 to 100 nm. It is understood that the average particle size of the copper nanoparticles can be obtained by randomly sampling 100 copper nanoparticles from a scanning electron microscope image or a transmission electron microscope image, photographing the image, measuring the longest and shortest lengths of each copper nanoparticle, and then calculating the arithmetic mean of these lengths. Of course, a different number of copper nanoparticles can be sampled as needed, and this application does not impose any particular limitation on this.

[0045] The longest direction can be understood as the longest geometric dimension of the copper nanoparticle in three-dimensional space, and the shortest direction can be understood as the shortest geometric dimension of the copper nanoparticle in three-dimensional space. For example, taking the copper nanoparticle as a rotating copper nanoparticle as an example, such as a rod-shaped copper nanoparticle, the longest direction can be understood as the direction of its main axis, and the shortest direction can be understood as the radial direction perpendicular to its main axis. Taking the copper nanoparticle as a polyhedral nanoparticle as an example, such as a cube or a cuboid, the straight-line distance between two opposite vertices can be understood as the length of the longest direction, and the straight-line distance between the two closest vertices is the length of the shortest direction.

[0046] If the average particle size of the copper nanoparticles is too small, the reflection area will be reduced, affecting the reflectivity of light reflected to the battery body 3; if the average particle size of the copper nanoparticles is too large, the binding force between the copper nanoparticles and the battery body 3 will be reduced, and the gaps between the copper nanoparticles will be larger, which will also reduce the reflectivity of light reflected to the battery body 3.

[0047] For example, if Figure 4 As shown (partially enlarged view of Example 1), for example, a tangent line (dashed line) can be drawn to a vertex P on the surface of a copper nanoparticle. A tangent line (dashed line) can also be drawn to the copper nanoparticle at its opposite point, Q. The direction perpendicular to the two tangent lines (which can be understood as the normal direction of the two dashed lines), that is, the straight-line distance between the two vertices P and Q, is the longest length of the copper nanoparticle.

[0048] It should be noted that the aforementioned copper electrode 1 is typically formed by printing a copper paste, such as by screen printing, followed by light curing or thermal curing. During the curing process, the copper precursor particles carried by the solvent in the copper paste diffuse along both sides of the main region 11, thereby forming the epitaxial region 2 on the surface of the battery body 3. Furthermore, copper nanoparticles refer to particles primarily composed of zero-valent copper.

[0049] In some embodiments, the width ratio of any main region 11 to any epitaxial region 2 is 4:1 to 12:1. This arrangement allows the main region 11 to collect carriers from the cell body 3, while the epitaxial region 2 enhances sunlight utilization, further improving the cell's photoelectric conversion efficiency. If this ratio is too high, the main region 11 will be too wide, resulting in limited improvement in light utilization by the copper nanoparticles in the epitaxial region 2. If this ratio is too low, the main region 11 will be too narrow, making it difficult to fully collect the photocurrent generated in the cell body 3.

[0050] It should be noted that the width direction of the main region 11 and the epitaxial region 2 can be understood as the direction of the cross section along the extension direction of the two regions, and can also be understood as follows: Figure 1 The cross-sectional direction shown (i.e. Figure 1 left and right directions in the .

[0051] Optionally, the width ratio of any main region 11 to any epitaxial region 2 is 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1 or 12:1, or a range between any two of the above values.

[0052] In some embodiments, the width of any epitaxial region 2 is 10 to 60 μm, and the width of any main region 11 is 40 to 280 μm. This arrangement can better collect incident light and further strengthen the bonding strength between the copper electrode 1 and the battery body 3. If the epitaxial region 2 is set too wide, the organic matter such as resin in the copper paste will cover a large area after curing, blocking the light absorption of the battery body 3. Its impact on light blocking is greater than the benefit of using non-spherical copper nanoparticles, thereby reducing the photoelectric conversion efficiency; if the width of the epitaxial region 2 is too narrow, the light receiving area of ​​the non-spherical copper nanoparticles is small, making it difficult to reflect its advantages in directions such as light reflection and scattering. The method for measuring the width of the epitaxial region 2 and the main region 11 is not limited in this application. Conventional selections can be made in this field based on actual needs, and a scanning electron microscope can be used for image capture. For example, the width of the electrode main body area 11 can be obtained by SEM measurement. The width of the bottom of the copper electrode in a certain area within the SEM measurement field is measured, and 10 areas are continuously measured to calculate the average value, thereby obtaining the width of the main body area 11 of the copper electrode.

[0053] Optionally, the width of any epitaxial region 2 may be, for example, 10 μm, 20 μm, 30 μm, 40 μm, 43 μm, 50 μm or 60 μm, or a range between any two of the above values.

[0054] Optionally, the width of any main region 11 can be, for example, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 205μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 266μm, 270μm or 280μm, or a range between any two of the above values.

[0055] It can be understood that when the width of the main region 11 is wider, the widths of the corresponding epitaxial regions 2 on both sides are also correspondingly wider.

[0056] In some embodiments, the distribution density of copper nanoparticles in the epitaxial region 2 is 1 to 100 per μm. 2 The distribution density can be understood as 1 to 100 copper nanoparticles per square micron within the epitaxial region 2. This arrangement ensures that copper nanoparticles reflect and / or scatter incident light within each square micron, further improving the uniformity of light utilization within the epitaxial region 2, allowing the incident light to be fully absorbed and converted into photocurrent. It should be noted that the above distribution density can be controlled by controlling the composition and content of the organic solvent in the copper slurry, as is conventional in the art.

[0057] Optionally, the distribution density of copper nanoparticles in the epitaxial region 2 is 1 per μm. 2 , 10 / μm 2 , 15 / μm 2 , 20 / μm 2 , 25 / μm 2 , 30 / μm 2 , 35 / μm 2 , 40 / μm 2 , 45 / μm 2 , 50 / μm 2 , 55 / μm 2 , 60 / μm 2 , 65 / μm 2 , 70 / μm 2 , 75 / μm 2 , 80 / μm 2 , 85 / μm 2, 90 / μm 2 , 95 / μm 2 or 100 / μm 2 etc., or a range between any two of the above values.

[0058] It should be noted that during the flow of the solvent, the above-mentioned non-spherical copper nanoparticles are also distributed in the edge portion 112. In the area of ​​the edge portion 112 close to the epitaxial region 2, the non-spherical copper nanoparticles can also reflect the incident light into the battery body 3 to a certain extent, thereby improving the light utilization efficiency of the solar cell.

[0059] According to another embodiment of the present application, a method for preparing the solar cell as described above is provided, and the method includes operations 1 to 3.

[0060] In operation 1, copper precursor particles, a solvent, an organic resin, and optionally elemental copper particles are mixed to obtain a mixture.

[0061] In operation 2, the above mixture is heated and melted to obtain copper slurry.

[0062] In operation 3, copper paste is printed on the surface of the battery body by printing, and sintered to convert the copper precursor particles into non-spherical copper nanoparticles to obtain a solar cell.

[0063] According to the embodiments of the present application, driven by the solvent, the copper precursor particles extend away from the copper electrode, forming a main region 11 and two epitaxial regions 2. The two epitaxial regions 2 are located on either side of the main region 11 (which can be understood as perpendicular to the extension direction of the copper electrode 1). The sintering process converts the copper precursor particles into non-spherical copper nanoparticles. When subsequently used in solar cells, as previously described, they can improve the utilization rate of incident light.

[0064] In some embodiments, the printing method may be screen printing, for example.

[0065] In some embodiments, the copper precursor particles can be non-spherical copper nanoparticles, spherical cuprous hydride nanoparticles, or non-spherical cuprous hydride nanoparticles. When the copper precursor particles are spherical cuprous hydride nanoparticles, a surface protectant (e.g., polyvinyl pyrrolidone (PVP)) can be added to the copper slurry. Under the guidance of the surface protectant, the copper atoms recrystallize into non-spherical nanoparticles after the spherical cuprous hydride nanoparticles decompose.

[0066] In some embodiments, the average particle size of the cuprous hydride nanoparticles is 1 to 100 nm. This configuration sufficiently reduces the surface melting temperature of the cuprous hydride nanoparticles, facilitating surface melting. Furthermore, during the sintering stage of the copper slurry, at least a portion of the cuprous hydride nanoparticles decomposes into copper upon heating.

[0067] It is understood that, as mentioned above, the average particle size of cuprous hydride nanoparticles can be obtained by randomly selecting 100 particles from a scanning electron microscope image or a transmission electron microscope image, measuring their particle size values ​​by image capture, and then calculating the average of the above particle size values.

[0068] It should be noted that cuprous hydride nanoparticles are reducible and are less susceptible to oxidation in air than copper particles, making them relatively more stable and having excellent shelf life. Furthermore, cuprous hydride nanoparticles can decompose into elemental copper at temperatures between 60 and 100°C.

[0069] It should be noted that the cuprous hydride nanoparticles can be partially or completely converted into elemental copper, preferably completely converted into elemental copper.

[0070] Preferably, the shape of the cuprous hydride nanoparticles is the same as that of the aforementioned copper nanoparticles. This arrangement ensures that the epitaxial region has more non-spherical copper nanoparticles, thereby enhancing the light absorption effect.

[0071] In some embodiments, the solvent includes at least one of an alcohol compound, an ether compound, a ketone compound, and water. Preferably, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, hexanol, cyclohexanol, cyclohexanone, cyclohexanol, terpineol, ethylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and diethylene glycol can use one or more of ethylene glycol monoethyl ether acetate and diethylene glycol monobutyl ether acetate. As the copper paste used for screen printing, from the perspective of making the viscosity range appropriate, the mass content of the solvent in the copper paste is preferably 1 to 10wt%.

[0072] For example, the mass content of the solvent in the copper paste may be 1 wt %, 2 wt %, 4 wt %, 6 wt %, 8 wt % or 10 wt %.

[0073] In some embodiments, the organic resin may include, for example, a thermosetting resin. The present application does not particularly limit the type of thermosetting resin. For example, the organic resin may be at least one of a phenolic resin, an epoxy resin, a polyester resin, a vinyl resin, a phthalate resin, an oligonucleotide acrylate resin, a xylene resin, a bismuth triazine resin, a polyurethane, a melamine resin, a silicone resin, an acrylic resin, an oxetane resin, and an oxazine resin. From the perspective of facilitating adhesion to the battery body 3, at least one of a phenolic resin, an epoxy resin, and an unsaturated polyester resin is preferred. The mass content of the organic resin in the copper paste is preferably 1 to 15 wt%.

[0074] For example, the mass content of the organic resin in the copper paste may be 1 wt %, 2 wt %, 4 wt %, 6 wt %, 8 wt %, 10 wt %, 12 wt %, 14 wt % or 15 wt %.

[0075] In some embodiments, the copper slurry may contain only cuprous hydride nanoparticles without elemental copper particles. From the perspective of enhancing the conductivity of the copper electrode, it is preferred to add elemental copper particles, thereby allowing the accumulation of copper particles of different sizes to form a more compact electrode. When added, the particle size of the elemental copper particles is larger than the cuprous hydride nanoparticles. When elemental copper particles are present, the cuprous hydride nanoparticles may be first coated onto the elemental copper particles. Alternatively, during printing, the elemental copper particles may be printed first, followed by the cuprous hydride nanoparticles.

[0076] Furthermore, the particle size of the elemental copper particles ranges from 100 nm to 10 μm. This configuration enhances the conductivity of the copper electrode and may allow cuprous hydride to adhere to the surface of the elemental copper particles during the sintering process, further improving its current transmission effect.

[0077] The method for measuring the particle size range of the elemental copper particles is substantially the same as the method for measuring the average particle size of the aforementioned copper nanoparticles, and will not be repeated here.

[0078] In some embodiments, since elemental copper particles are easily oxidized in air, the copper slurry may further include an organic coating agent, which is used to coat the surface of the cuprous hydride nanoparticles or elemental copper particles to reduce surface oxidation.

[0079] Furthermore, the organic coating agent is selected from compounds having 1 to 50 carbon atoms and containing at least one of an amino group, an amide group, a thiol group, a carboxyl group, a hydroxyl group, a carbonyl group, a thioether group, and an etheroxy group, with the aforementioned groups being located at the ends of the organic coating agent. Examples of compounds containing amino or amide groups include at least one of octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, oleylamine, benzylamine, octadecylamide, and oleamide. Examples of organic compounds containing thiol or thioether groups include at least one of decanethiol, dodecanethiol, trimethylbenzylmercaptan, butylbenzylmercaptan, and dihexyl sulfide. The organic compound containing hydroxyl, carboxyl, carbonyl and etheroxy groups can be, for example, at least one of dodecanediol, hexadecanediol, dodecanoic acid, octadecanoic acid, oleic acid, formic acid, linoleic acid, linolenic acid, dodecanedione, dibenzoylmethane, ethylene glycol monodecyl ether, diethylene glycol monodecyl ether, triethylene glycol monodecyl ether, tetraethylene glycol monodecyl ether, ethylene glycol monododecyl ether, diethylene glycol monododecyl ether, triethylene glycol monododecyl ether, tetraethylene glycol monododecyl ether, ethylene glycol monohexadecyl ether and diethylene glycol monohexadecyl ether.

[0080] In some embodiments, the copper slurry may further include a reducing agent. From the perspective of a good reduction effect of copper ions, the reducing agent is preferably a metal hydride or hypophosphorous acid, more preferably hypophosphorous acid. The metal hydride may be selected from any one of lithium aluminum hydride, lithium borohydride, sodium borohydride, lithium hydride, potassium hydride, and calcium hydride, more preferably lithium aluminum hydride, lithium borohydride, or sodium borohydride.

[0081] Below, taking the copper electrode as the collecting electrode as an example, the process of preparing the collecting electrode by screen printing is exemplified: preparing a copper paste containing copper precursor powder; using a screen template with a specific pattern, which is used to define the position and shape of the collecting electrode; the copper paste is pressed onto the surface of the battery body 3 through the screen template to form a patterned structure of the collecting electrode; driven by the solvent, the collecting electrode forms a main area and epitaxial areas on both sides of the main area; the solvent in the copper paste is removed by heating and drying, and then high-temperature sintering is performed to achieve good contact between the collecting electrode and the battery body 3, and the copper nanoparticles located in the epitaxial area are non-spherical copper nanoparticles.

[0082] In some embodiments, the mass content of the reducing agent is 0.1 to 15 wt %, which provides a sufficient reducing environment and prevents copper oxidation.

[0083] Optionally, the mass content of the reducing agent may be, for example, 0.1 wt%, 1 wt%, 3 wt%, 5 wt%, 7 wt%, 9 wt%, 11 wt%, 13 wt% or 15 wt%, or a range consisting of any two of the above values.

[0084] In some embodiments, the solar cell is selected from any one of a back contact solar cell, a heterojunction solar cell, and a tunnel oxide layer passivation contact cell.

[0085] According to the embodiments of the present application, the solar cell of the present application may be a bifacial cell, such as an HJT solar cell (heterojunction solar cell), a TOPCon solar cell (tunneling oxide passivation contact cell), or a back-contact solar cell. Furthermore, the back-contact solar cell may be a traditional IBC solar cell (interdigitated back-contact solar cell), or a TBC solar cell (TOPCon back-contact solar cell), an HBC solar cell (heterojunction back-contact solar cell), or a hybrid solar cell (i.e., wherein the PN passivation is a different passivation material, for example, a combination of polycrystalline silicon passivation and amorphous / microcrystalline passivation).

[0086] The solar cell comprises a cell body 3 , which at least comprises a semiconductor substrate and a doping layer on the semiconductor substrate, wherein the semiconductor substrate is a rectangular or square structure.

[0087] The material of the semiconductor substrate can be selected from materials such as silicon (Si) or germanium (Ge) or materials such as gallium arsenide (GaAs). Obviously, in terms of conductivity type, the semiconductor substrate can be an intrinsic semiconductor substrate, an n-type semiconductor substrate, or a p-type semiconductor substrate. Preferably, the semiconductor substrate is a p-type semiconductor substrate or an n-type semiconductor substrate. Compared with the intrinsic semiconductor substrate, the p-type semiconductor substrate or the n-type semiconductor substrate has better conductivity, so that the solar cell finally produced has a lower body resistivity, thereby improving the efficiency of the solar cell.

[0088] Furthermore, an n-type semiconductor substrate may be selected, which has the advantages of long minority carrier lifetime, no light decay, and good weak light performance.

[0089] The cell body 3 of the HJT solar cell has a first surface and a second surface disposed opposite each other. The first surface may be the backlight side, and the second surface may be the light-receiving side. The doped layer includes an n-doped region and a p-doped region. The n-doped region is located on the first surface, and the p-doped region is located on the second surface. The n-doped region and the p-doped region may be interchanged as needed, without specific limitation.

[0090] The cell body 3 of the TOPCon solar cell has a first surface and a second surface arranged opposite each other. The first surface can be the backlight side, and the second surface can be the light-receiving side. A tunneling oxide layer is also provided on the surface of the semiconductor substrate. A doped layer is located on the surface of the tunneling oxide layer away from the semiconductor substrate. The doped layer includes an n-doped region and a p-doped region. The n-doped region is located on the first surface, and the p-doped region is located on the second surface. The two can also be interchanged as needed and are not specifically limited here. In addition, a passivation layer is provided on the side of the n-doped region and the p-doped region facing away from the semiconductor substrate, and a copper electrode is formed on the passivation layer.

[0091] The cell body 3 of the above-mentioned IBC solar cell comprises n-doped regions and p-doped regions arranged alternately along a first direction on a semiconductor substrate to form an interdigitated doping structure. Electrode structures are arranged alternately in the n-doped regions and the p-doped regions.

[0092] The cell body 3 of the TBC solar cell comprises a tunneling oxide layer disposed on a semiconductor substrate, and n-doped and p-doped regions formed from a doped polysilicon layer. The stacked tunneling oxide layer and doped polysilicon layer form a TOPCon structure. Compared to IBC solar cells, the TBC solar cell offers a longer carrier lifetime and lower surface recombination, thereby improving the photoelectric conversion efficiency of the TBC solar cell.

[0093] Furthermore, the TBC solar cell also includes a third region (gap region) on the cell body 3. Neither the n-doped region nor the p-doped region extends into this third region. The third region serves to isolate the n-doped and p-doped regions to prevent leakage. A passivation layer is provided on the side of the n-doped and p-doped regions facing away from the semiconductor substrate. A collector electrode is provided on the surface of the passivation layer facing away from the semiconductor substrate. The passivation layer comprises one or more stacked layers of silicon nitride, silicon oxynitride, and silicon oxide.

[0094] The cell body 3 of the aforementioned HBC solar cell comprises an n-doped region and a p-doped region disposed on a semiconductor substrate to form a heterojunction structure. The n-doped region includes, but is not limited to, microcrystalline silicon or amorphous silicon (to provide electrons), while the p-doped region may also be made of microcrystalline silicon or amorphous silicon (e.g., using boron as a dopant to provide holes). HBC solar cells help improve carrier lifetime and reduce surface recombination. Furthermore, a transparent conductive oxide layer (TCO) may be disposed between the surfaces of the n-doped and p-doped regions and the electrodes. This facilitates carrier collection in the doped regions and also provides a certain degree of anti-reflection.

[0095] The cell body 3 of the hybrid solar cell may adopt a layer structure similar to that of an IBC cell or a TBC cell, and a corresponding passivation layer structure is configured thereon, such as a combination of at least two of polycrystalline silicon passivation, amorphous silicon passivation and microcrystalline silicon passivation.

[0096] The main material of the doping layer can be selected from silicon (Si), germanium (Ge), silicon carbide (SiC x ) or gallium arsenide (GaAs) and other semiconductor materials, which can be amorphous, microcrystalline, single crystal, nanocrystalline, or polycrystalline. Donor impurities such as phosphorus (P), arsenic (As), or antimony (Sb) are introduced into the aforementioned semiconductor materials to form an n-doped region. Acceptor impurities such as boron (B), aluminum (Al), or gallium (Ga) are introduced into the aforementioned semiconductor materials to form a p-doped region.

[0097] The doped layer can be formed on the semiconductor substrate by deposition, and can also be formed in the semiconductor substrate by diffusion, ion implantation, etc.

[0098] In some embodiments, the electrodes are collecting electrodes and / or bus electrodes. The collecting electrodes can be called fine grids, collecting grid lines, auxiliary grids, etc., and multiple collecting electrodes are located on at least one surface of the battery body 3. The multiple collecting electrodes are spaced apart in a first direction (not shown in the figure) and extend along a second direction (not shown in the figure) that intersects with the first direction. The bus electrode extends along the second direction, and the bus electrode is in direct contact and electrically connected to the collecting electrode of the same polarity. The bus electrode is electrically isolated from the collecting electrodes of different polarities. The bus electrode is located on the side close to the battery body 3 and is electrically connected to the electrical connection line through a joint. The extension direction of the bus electrode intersects with the extension direction of the collecting electrode, and preferably the extension directions of the two are perpendicular. The bus electrode or the collecting electrode is fixed to and electrically connected to the electrical connection line.

[0099] In some embodiments, setting the copper electrode as a collecting electrode and / or a bus electrode helps to improve the current collection efficiency of the collecting electrode and / or the bus electrode through the reflection and / or scattering effect of the non-spherical particles in the epitaxial region 2, thereby improving the photoelectric conversion efficiency.

[0100] It should be noted that the solar cell of the present application may adopt a busbar-less (no busbar, i.e., 0BB) structure, that is, the collecting electrode may be directly connected to the external electrical connection wire by welding without passing through the busbar.

[0101] The following is an explanation of the collector electrode using different batteries as examples.

[0102] In some embodiments, when the solar cell is a back-contact solar cell, the first semiconductor layer and the second semiconductor layer (which can be understood as the n-doped region and p-doped region mentioned above) and the collector electrode (gate line) are formed on the backlight side of the solar cell. The collector electrode includes a first collector electrode and a second collector electrode. The first collector electrode is located on the surface of the first semiconductor layer, and the second collector electrode is located on the surface of the second semiconductor layer. This facilitates the collector electrodes to conduct electrons or holes, forming current.

[0103] In some embodiments, when the solar cell is a heterojunction solar cell (HJT), the solar cell includes a first surface and a second surface, the first semiconductor layer is located on the first surface, and the second semiconductor layer is located on the second surface. The collector electrode includes a first collector electrode and a second collector electrode, the first collector electrode is located on the surface of the first semiconductor layer, and the second collector electrode is located on the surface of the second semiconductor layer, and the first collector electrode and the second collector electrode have opposite polarities.

[0104] In some embodiments, the solar cell may further include a transparent conductive layer, which is located on the side of the first semiconductor layer and / or the second semiconductor layer facing away from the semiconductor substrate. The transparent conductive layer has a high electrical conductivity and can promptly conduct the collected carriers to reduce the carrier recombination rate.

[0105] It is possible to choose whether to provide a transparent conductive layer on the side of the first semiconductor layer away from the semiconductor substrate as needed. For example, if the first semiconductor layer is doped polycrystalline silicon, the side of the first semiconductor layer away from the semiconductor substrate may or may not be provided with a transparent conductive layer. If the first semiconductor layer is one or more of doped amorphous silicon, doped microcrystalline silicon, or doped nanocrystalline silicon, a transparent conductive layer may be provided on the side of the first semiconductor layer away from the semiconductor substrate. Similarly, it is possible to choose whether to provide a transparent conductive layer on the side of the second semiconductor layer away from the semiconductor substrate as needed. For example, if the second semiconductor layer is one or more of doped amorphous silicon, doped microcrystalline silicon, or doped nanocrystalline silicon, a transparent conductive layer may be provided on the side of the second semiconductor layer away from the semiconductor substrate.

[0106] The material of the transparent conductive layer may be, but is not limited to, indium tin oxide (ITO), tungsten-doped tin oxide (VTTO), tungsten-doped indium oxide (IWO), molybdenum-doped indium oxide (IMO), or tin oxide fluoride (TOF). Optionally, the transparent conductive layer may be a single layer structure formed from one of these materials, or a stacked structure formed from two or more of these materials.

[0107] In some embodiments, when the solar cell has a transparent conductive layer, the epitaxial region 2 of the electrode is formed on a surface of the transparent conductive layer away from the semiconductor substrate.

[0108] It should be noted that the present application does not impose any particular limitation on the thickness of the transparent conductive layer.

[0109] In some embodiments, the surface of the battery body 3 has a velvet structure, and the copper electrode 1 is located on the surface of the velvet structure. Thus, the micron-sized velvet structure has a confinement effect, which helps to form non-spherical copper nanoparticles during electrode sintering.

[0110] In some embodiments, the velvet structure includes a plurality of pyramids, each of which includes a tower bottom and a tower top arranged in a direction away from the surface of the battery body 3. Figures 2 to 4 As shown, a pyramid morphology can be observed. Gaps exist between the bottom boundaries of at least some adjacent pyramids in the plurality of pyramids. Copper nanoparticles in the electrode are located in the gaps between adjacent pyramids.

[0111] In some embodiments, the pyramids in the velvet structure may be upright pyramid structures and / or inverted pyramid structures.

[0112] In the case where the solar cell includes a transparent conductive layer, the transparent conductive layer is formed on the textured structure.

[0113] In some embodiments, the number of copper nanoparticles in at least a portion of the gap is greater than or equal to 1.

[0114] In some embodiments, as Figure 4 As shown, during printing, the copper precursor compound accumulates with the organic resin at the base of the pyramid. As the copper paste solidifies, it preferentially precipitates in the copper ion-rich area, i.e., the base of the pyramid. Compared to spherical metal particles, the non-spherical copper nanoparticles in epitaxial region 2 adhere to the transparent conductive layer on the pyramid surface. The various surfaces of their polyhedral structure form an angle with the inclined pyramid surface. Due to the different angles, they have a better light trapping effect, which increases the light-receiving area of ​​the cell, thereby effectively improving the cell's absorption and utilization of light, thereby increasing the cell's collected current.

[0115] In some embodiments, one surface of the battery body 3 may have a velvet structure, with the main region 11 and epitaxial region 2 of the copper electrode 1 (which can be understood as the collector electrode here) formed on the velvet structure. This configuration increases the surface area of ​​the surface, thereby increasing the contact area between the main region 11 and the epitaxial region 2 and the surface, further improving the adhesion of the copper electrode 1 to the surface while reducing the contact resistance of the copper electrode 1, thereby ensuring the efficiency of current collection and transmission. Furthermore, the velvet structure has a light-trapping effect. Therefore, when the surface has a velvet structure, the reflectivity of light can be reduced, which helps more light be refracted from the light-facing surface into the semiconductor substrate and absorbed and utilized by the semiconductor substrate, thereby improving the photoelectric conversion efficiency of the solar cell.

[0116] According to an embodiment of yet another aspect of the present application, a photovoltaic assembly is provided, comprising the solar cell as described above, and a plurality of electrical connection lines, wherein the plurality of electrical connection lines electrically connect adjacent solar cells.

[0117] According to an embodiment of the present application, the aforementioned solar cells are connected in series to form a solar cell string; and a packaging structure is disposed around the periphery of the solar cell string.

[0118] In some embodiments, the encapsulation structure may include a backsheet or back glass, an encapsulation film, a glass panel, etc. to enhance the stability of the solar cell string. The glass panel is located on the front of the solar cell string, and the backsheet is located on the back of the solar cell string, both of which provide protection. The adhesive film is used to bond the solar cell string to the glass panel and backsheet, providing a secure bond.

[0119] In some embodiments, multiple electrical connection lines (also called welding strips or interconnecting strips, which can be metal wires, metal lines, etc.) include first electrical connection lines and second electrical connection lines extending along a first direction and alternately arranged in a second direction. The cross-section of the electrical connection line can be circular or quasi-circular, elliptical, square, triangular, other polygonal, etc. The wire diameter or width of the electrical connection line ranges from 200 to 1200 μm. For example, the circular electrical connection line is preferably 220 to 350 μm, and particularly preferably 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, 300 μm, 310 μm, 320 μm, and 330 μm. The maximum width of the square or rectangular electrical connection line is preferably 500 to 800 μm, and particularly preferably 600 μm.

[0120] In a photovoltaic module, the polarity of the electrical connection line of the adjacent preceding solar cell is opposite to the polarity of the electrical connection line of the connected succeeding solar cell to achieve current transmission.

[0121] The present application will be further described below by way of examples, drawings, and related test experiments and results thereof. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may also be implemented without these specific details. Moreover, in the absence of conflict, the details in the following embodiments may be arbitrarily combined into other feasible embodiments.

[0122] It should be noted that the following specific examples are for illustration only and the scope of protection of this application is not limited thereto. The chemicals and raw materials used in the following examples were either commercially available or prepared in-house using recognized processing methods.

[0123] Example 1

[0124] Preparation process of copper slurry:

[0125] A copper slurry was prepared by mixing 100g of elemental copper particles with a particle size range of 200nm to 1000nm, 200g of cuprous hydride nanoparticles with an average particle size of 60nm, 0.4g of bisphenol F epoxy resin, 0.15g of dicyandiamide curing agent, 0.2g of 2-propylimidazole, 0.05g of oleic acid dispersant, and 0.3g of diethylene glycol butyl ether acetate solvent. The copper hydride (CuH) was shaped as triangular and quadrangular prisms. After stirring, the mixture was poured into a three-roll mill and milled to obtain a homogeneous slurry. The slurry was then screen-printed onto a semiconductor substrate and cured by heating at 300°C for 3 seconds. This resulted in the formation of copper electrode lines with epitaxial regions, driven by the solvent and organic resin.

[0126] Scanning electron microscope images show that the width of the main region is 266 μm, the width of the epitaxial region is 43 μm, and the distribution density of copper nanoparticles in the epitaxial region is 50 / μm. 2 . Figure 3 The scanning electron microscope and elemental analysis diagrams of the epitaxial region of the solar cell according to the embodiment of the present application are shown, wherein a shows a scanning electron microscope diagram; b shows an elemental analysis diagram. Figure 4 Shown Figure 3 A partial enlarged view of Figure a. Figure 3 Figure a and Figure 4 As shown in Figure 2, it is confirmed that there are non-spherical nanoparticles in the voids near the base of the pyramid. Figure 3 As shown in b, elemental analysis further confirmed that the non-spherical particles here are copper nanoparticles.

[0127] Example 2

[0128] The preparation process of Example 2 is substantially the same as that of Example 1, except that the average particle size of the added cuprous hydride nanoparticles is 120 nm, and a copper grid line with an epitaxial region is prepared; scanning electron microscopy shows that the width of the main region is 205 μm, the width of the epitaxial region is 20 μm, and the distribution density of the copper nanoparticles in the epitaxial region is 30 particles / μm. 2 , non-spherical nanoparticles were found in the voids near the base of the pyramid. Elemental analysis further confirmed that the non-spherical particles were copper nanoparticles.

[0129] Comparative Example 1

[0130] The preparation process of Comparative Example 1 is substantially the same as that of Example 1, except that no cuprous hydride nanoparticles are added to prepare the copper grid lines.

[0131] Comparative Example 2

[0132] The preparation process of Comparative Example 2 is substantially the same as that of Example 1, except that the added cuprous hydride nanoparticles are spherical, and a copper grid line with an epitaxial region is prepared.

[0133] The solar cells prepared in Examples 1-2 and Comparative Examples 1-2 were respectively assembled into solar cell strings. The performance comparison of the solar cells in the above examples and comparative examples is shown in Table 1 below.

[0134] Table 1

[0135]

[0136] From the battery performance results, it can be seen that the photoelectric conversion efficiency, short-circuit current and fill factor of the solar cells of Examples 1 and 2 are higher than those of the comparative example, and the series resistance is lower than that of the comparative example. Figure 3~Figure 4 As shown, the epitaxial regions of the solar cells prepared in Examples 1 and 2 form non-spherical copper nanoparticles. These non-spherical copper nanoparticles have excellent reflection and / or scattering properties for incident light, improving the photoelectric conversion efficiency of the solar cells compared to Comparative Examples 1 and 2. Furthermore, the presence of the epitaxial regions further reduces the contact resistance of the solar cells, contributing to the widespread application of base metalization in the solar cell industry.

[0137] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of this application. It should be understood that the above is only a specific embodiment of this application and is not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A solar cell, characterized in that: The invention comprises a battery body, at least one copper electrode located on at least one surface of the battery body, and at least two epitaxial regions, wherein the copper electrode comprises a main body region, wherein two epitaxial regions are adjacent to the main body region and extend outward from both sides of the main body region, and at least one epitaxial region comprises a plurality of copper nanoparticles; Wherein, the copper nanoparticles are non-spherical copper nanoparticles.

2. The solar cell according to claim 1, wherein The copper nanoparticles are polyhedral copper nanoparticles or rotating copper nanoparticles.

3. The solar cell according to claim 2, wherein The polyhedral copper nanoparticles have at least four surfaces; the rotating copper nanoparticles have at least two surfaces.

4. The solar cell according to claim 3, characterized in that The contour lines of the surfaces of the copper nanoparticles include at least one of straight lines and arcs.

5. The solar cell according to claim 3, characterized in that The average particle size of the copper nanoparticles is 10-100 nm.

6. The solar cell according to any one of claims 1 to 5, characterized in that The width ratio of any one of the main regions to any one of the epitaxial regions is 4:1 to 12:

1.

7. The solar cell according to any one of claims 1 to 5, characterized in that The width of any one of the epitaxial regions is 10-60 μm.

8. The solar cell according to any one of claims 1 to 5, characterized in that The width of any one of the main regions is 40-280 μm.

9. The solar cell according to any one of claims 1 to 5, characterized in that The distribution density of the copper nanoparticles in the epitaxial region is 1 to 100 per μm. 2 .

10. The solar cell according to claim 1, wherein The copper electrode is a collector electrode and / or a bus electrode.

11. The solar cell according to claim 1 or 10, characterized in that The surface of the battery body has a velvet structure, and the copper electrode is located on the surface of the velvet structure.

12. The solar cell according to claim 1 or 10, characterized in that The solar cell is selected from any one of a back contact solar cell, a heterojunction solar cell, and a tunnel oxide layer passivation contact cell.

13. A photovoltaic module, characterized in that: The solar cell comprises the solar cell according to any one of claims 1 to 12, and a plurality of electrical connection lines, wherein the plurality of electrical connection lines electrically connect adjacent solar cells.

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