Solar cell and method of manufacturing the same, stacked cell, and photovoltaic module

Abstract

The application relates to a solar cell and a manufacturing method thereof, a laminated cell and a photovoltaic module. The solar cell comprises a substrate with a first surface and a second surface arranged oppositely; a first tunneling layer located on one side of the second surface; and a first doped semiconductor layer located on one side of the first tunneling layer away from the substrate; wherein the first doped semiconductor layer is doped with boron elements and gallium elements, and in the direction in which the first surface points to the second surface, the doping concentration of the boron elements gradually decreases, and the doping concentration of the gallium elements gradually increases. The application can improve the performance of the solar cell.

Description

Technical Field

[0001] This application relates to the field of solar cell manufacturing technology, and in particular to a solar cell and its manufacturing method, tandem cells and photovoltaic modules. Background Technology

[0002] Solar energy, as an emerging energy source, has advantages over traditional fossil fuels in many aspects, including inexhaustibility, cleanliness, and environmental friendliness. Currently, a major method of utilizing solar energy is through solar cell modules that convert received light energy into electrical energy. These modules can be large-area solar panels formed by connecting several solar cells (or photovoltaic cells, or photovoltaic modules) in series, encapsulating them, and arranging them in an array. When a solar cell absorbs light energy, opposite charges accumulate at its terminals, generating a "photovoltaic voltage," also known as the "photovoltaic effect." Under the influence of the photovoltaic effect, an electromotive force is generated at the terminals of the solar cell, thus converting light energy into electrical energy.

[0003] However, the performance of solar cells still needs further improvement. Summary of the Invention

[0004] Therefore, it is necessary to provide a solar cell, its manufacturing method, and a photovoltaic module to address the issue of how to improve the performance of solar cells.

[0005] In a first aspect, this application provides a solar cell, comprising:

[0006] The substrate has a first surface and a second surface disposed opposite to each other;

[0007] The first tunneling layer is located on one side of the second surface;

[0008] The first doped semiconductor layer is located on the side of the first tunneling layer away from the substrate;

[0009] In this process, the first doped semiconductor layer is doped with boron and gallium. In the direction from the first surface to the second surface, the doping concentration of boron gradually decreases and the doping concentration of gallium gradually increases.

[0010] In some embodiments, the first doped semiconductor layer has a first sub-surface portion close to the first surface and a second sub-surface portion away from the first surface;

[0011] In the first sub-surface portion, the doping concentration of boron is greater than the doping concentration of gallium.

[0012] In the second sub-surface portion, the doping concentration of boron is greater than that of gallium.

[0013] In some embodiments, the boron doping concentration in the first doped semiconductor layer is 1 × 10⁻⁶. 20 cm -3 -5×10 19 cm -3 .

[0014] In some embodiments, the gallium doping concentration in the first doped semiconductor layer is 1 × 10⁻⁶. 18 cm -3 -1×10 19 cm -3 .

[0015] In some embodiments, the boron doping concentration on the first sub-surface is 0.7 × 10⁻⁶. 20 cm -3 -1.5×10 20 cm -3 ; and / or,

[0016] In the first sub-surface portion, the gallium doping concentration is 0.5 × 10⁻⁶. 18 cm -3 -3×10 18 cm -3 .

[0017] In some embodiments, the boron doping concentration on the second sub-surface is 3 × 10⁻⁶. 19 cm -3 -8×10 19 cm -3 ; and / or,

[0018] In the second sub-surface portion, the gallium doping concentration is 0.7 × 10⁻⁶. 19 cm -3 -2×10 19 cm -3 .

[0019] In some embodiments, the material of the first tunneling layer includes silicon oxide, and the material of the first doped semiconductor layer includes polycrystalline silicon; and / or,

[0020] The thickness of the first tunneling layer is 1nm-2nm, and the thickness of the first doped semiconductor layer is 50nm-150nm.

[0021] In some embodiments, the first doped semiconductor layer is further doped with hydrogen, and the hydrogen doping concentration is 1 × 10⁻⁶. 19 cm -3 -1×10 20 cm -3 .

[0022] Secondly, based on the same concept, this application also provides a method for manufacturing a solar cell, comprising:

[0023] A substrate is provided, the substrate having a first surface and a second surface disposed opposite to each other;

[0024] A first tunneling layer is formed on the second surface;

[0025] A first pre-defined doped semiconductor layer is formed on the side of the first tunneling layer away from the substrate;

[0026] Boron and gallium are doped in the first preset doped semiconductor layer to form a first doped semiconductor layer; in the direction from the first surface to the second surface, the doping concentration of boron gradually decreases and the doping concentration of gallium gradually increases.

[0027] In some embodiments, the step of doping boron and gallium elements in the first preset doped semiconductor layer includes:

[0028] Boron is doped into the first preset doped semiconductor layer by ion implantation, with an ion implantation kinetic energy of 10keV-30keV.

[0029] Gallium is doped into the first preset doped semiconductor layer by ion implantation, with an ion implantation kinetic energy of 30keV-50keV.

[0030] In some embodiments, the step of doping boron and gallium elements in the first preset doped semiconductor layer includes:

[0031] In the first preset doped semiconductor layer, boron and gallium elements are simultaneously doped using diffusion processes with boron and gallium sources at a temperature of 800℃-950℃ for a time of 30min-60min.

[0032] In some embodiments, after the step of doping boron and gallium in the first preset doped semiconductor layer, the method further includes:

[0033] Laser annealing, wherein the wavelength of the laser is 300nm-1200nm, the energy density is 1J / cm²-3J / cm², the scanning speed is 50mm / s-200mm / s, and the annealing atmosphere is nitrogen.

[0034] In some embodiments, after the laser annealing step, the method further includes:

[0035] Hydrogen plasma passivation treatment, with a radio frequency power of 300W-500W, a time of 10min-30min, and a hydrogen flow rate of 50sccm-100sccm.

[0036] Thirdly, this application provides a stacked battery, comprising a top battery, an adhesive layer, and a bottom battery stacked sequentially, wherein the bottom battery is a solar cell as described in any of the above-mentioned applications.

[0037] Fourthly, this application provides a photovoltaic module, comprising:

[0038] A battery string is formed by connecting multiple solar cells as described in any one of the above descriptions, or by connecting multiple solar cells manufactured by the manufacturing method of any one of the above descriptions, or by connecting the tandem cells described above.

[0039] A connecting component for electrically connecting two adjacent solar cells;

[0040] An encapsulating film is used to cover the surface of the battery string;

[0041] A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

[0042] In this embodiment, the first doped semiconductor layer is doped with boron and gallium. In the direction from the first surface to the second surface (the third direction), the boron doping concentration gradually decreases, while the gallium doping concentration gradually increases. Firstly, by introducing gallium to partially replace boron, the formation of BO bond complexes in the substrate is reduced, thereby improving or solving the problem of light-induced degradation (LID). Secondly, through gradient doping design, a high boron concentration is maintained near the first tunneling layer to ensure low contact resistance, while the gallium concentration is increased further away from the first tunneling layer to suppress boron diffusion, thereby optimizing carrier transport performance. Thirdly, combined with the solar cell manufacturing method of this embodiment, the solar cell manufacturing process is compatible with existing production lines, providing a mass-producible doping and passivation synergistic process, avoiding high equipment modification costs. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments or exemplary embodiments of this application, the drawings used in the description of the embodiments or exemplary embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A schematic diagram of the cross-sectional structure of a first type of solar cell provided in some embodiments of this application.

[0045] Figure 2 for Figure 1 A partially enlarged schematic diagram of the film layer on one side of the second surface.

[0046] Figure 3 This is a schematic diagram of the cross-sectional structure of a second type of solar cell provided in some embodiments of this application.

[0047] Figure 4 This is a schematic diagram of the cross-sectional structure of a third type of solar cell provided in some embodiments of this application.

[0048] Figure 5 This is a schematic diagram of the process steps for manufacturing a solar cell according to an embodiment of this application.

[0049] Figure 6 This is a schematic diagram of another process step in a method for manufacturing a solar cell provided in an embodiment of this application.

[0050] Figure 7 This is a schematic diagram showing the comparison results between the embodiments of this application and related technologies.

[0051] Figure 8 This is a schematic diagram of the structure of a photovoltaic module provided in an embodiment of this application.

[0052] Reference numerals: Photovoltaic module 200; Solar cell 100; Substrate 11; First tunneling layer 21; First doped semiconductor layer 22; First surface 111; Second surface 112; Boron a1; Gallium a2; First sub-surface 211; Second sub-surface 212; First passivation layer 23; First electrode 24; Emitter layer 12; Second passivation layer 13; Second electrode 14; Second tunneling layer 31; Second doped conductive layer 32; Second passivation layer 33; Second electrode 34;

[0053] First direction Y; Second direction X; Third direction Y1; First sub-surface 2101; Second sub-surface 2102; Textured surface R1; Battery string 203; Connecting component 204; Encapsulating film 202; Cover plate 201. Detailed Implementation

[0054] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0055] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0056] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0057] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0058] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0059] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0060] See Figures 1 to 4 . Figure 1 A schematic diagram of the cross-sectional structure of a first type of solar cell provided in some embodiments of this application. Figure 2 for Figure 1 A partially enlarged schematic diagram of the film layer on one side of the second surface. Figure 3 This is a schematic diagram of the cross-sectional structure of a second type of solar cell provided in some embodiments of this application. Figure 4 This is a schematic diagram of the cross-sectional structure of a third type of solar cell provided in some embodiments of this application.

[0061] It should be noted that, Figure 2 for Figure 1 , Figure 3 , Figure 4 Example: A partially enlarged schematic diagram of the film layer on one side of the second surface.

[0062] In a first aspect, this application provides a solar cell 100, which includes a substrate 11, a first tunneling layer 21, and a first doped semiconductor layer 22. The substrate 11 has a first surface 111 and a second surface 112 disposed opposite to each other; the first tunneling layer 21 is located on one side of the second surface 112; the first doped semiconductor layer 22 is located on the side of the first tunneling layer 21 away from the substrate 11; wherein the first doped semiconductor layer 22 is doped with boron and gallium, and in the direction from the first surface 111 to the second surface 112, the doping concentration of boron gradually decreases and the doping concentration of gallium gradually increases.

[0063] For example, the substrate 11 may contain doped elements, which can be N-type or P-type. N-type elements can be Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), while P-type elements can be Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In). For instance, when the substrate 11 is a P-type substrate, its internal doped element type is P-type. Similarly, when the substrate 11 is an N-type substrate, its internal doped element type is N-type.

[0064] For example, the substrate 11 has a first surface 111 and a second surface 112 disposed opposite to each other. The first surface 111 and the second surface 112 are disposed opposite to each other along the thickness direction of the substrate 11. Both the first surface 111 and the second surface 112 can be used to receive incident light.

[0065] For example, in some embodiments, such as Figure 1 As shown, the first surface 111 of the substrate 11 (e.g., the first surface 111 is the front) is the main light-receiving surface, and the second surface 112 of the substrate 11 is the secondary light-receiving surface (e.g., the second surface 112 is the back).

[0066] For example, in some other embodiments, such as Figure 3 As shown, the second surface 112 of the substrate 11 (e.g., the second surface 112 is the front side) is the main light-receiving surface, and the first surface 111 of the substrate 11 is the secondary light-receiving surface (e.g., the first surface 111 is the back side).

[0067] It is understandable that the terms "light-receiving surface" and "back-lighting surface" are relative. The light-receiving surface is specifically the surface on the substrate 11 of a solar cell or photovoltaic module that is primarily exposed to sunlight. With the development of solar cell technology, the back-lighting surface also receives energy from sunlight, mainly from reflected or scattered light from the surrounding environment.

[0068] For example, such as Figures 1 to 4 As shown, the first direction Y is perpendicular to the plane where the second surface 112 is located, and the first direction Y is also the thickness direction of the substrate 11.

[0069] For example, such as Figures 1 to 4 As shown, the second direction X is parallel to the plane containing the second surface 112, and the second direction X is also perpendicular to the thickness of the substrate 11.

[0070] For example, such as Figures 1 to 4 As shown, the direction from the first surface 111 to the second surface 112 is the third direction Y1, which is parallel to the first direction Y.

[0071] For example, such as Figure 2 As shown, Figure 2 The diagram illustrates that the first doped semiconductor layer 22 is doped with boron element a1 and gallium element a2. In the direction from the first surface 111 to the second surface 112 (third direction Y1), the doping concentration of boron element a1 gradually decreases, while the doping concentration of gallium element a2 gradually increases.

[0072] For example, such as Figure 2As shown, the first doped semiconductor layer 22 has a first sub-surface portion 211 near the first surface 111 / second surface 112, and a second sub-surface portion 212 away from the first surface 111 / second surface 112. The doping concentration of boron element a1 in the first sub-surface portion 211 is greater than the doping concentration of boron element a1 in the second sub-surface portion 212. The doping concentration of gallium element a2 in the first sub-surface portion 211 is less than the doping concentration of gallium element a2 in the second sub-surface portion 212.

[0073] For example, in related technologies, the first doped semiconductor layer 22 is doped with boron only, and the doping concentration of boron is uniform in the third direction Y1. However, after each process step, BO complexes are easily formed in the substrate 11, which leads to the problem of light-induced degradation (LID). Boron diffusion is also easily formed on the side away from the substrate 11, which reduces the carrier transport performance.

[0074] In this embodiment, the first doped semiconductor layer 22 is doped with boron and gallium. Along the direction from the first surface 111 to the second surface 112 (third direction Y1), the boron doping concentration gradually decreases, while the gallium doping concentration gradually increases. Firstly, by introducing gallium to partially replace boron, the formation of BO bond complexes in the substrate 11 is reduced, thereby improving or solving the problem of light-induced degradation (LID). Secondly, through gradient doping design, a high boron concentration is maintained near the first tunneling layer 21 to ensure low contact resistance, while the gallium concentration is increased away from the first tunneling layer 21 to suppress boron diffusion, thereby optimizing carrier transport performance. Thirdly, combined with the solar cell manufacturing method of this embodiment, the manufacturing process of the solar cell 100 is compatible with existing production lines, providing a mass-producible doping and passivation synergistic process, avoiding high equipment modification costs.

[0075] In some implementations, such as Figure 1 and Figure 2 As shown, the first doped semiconductor layer 22 has a first sub-surface portion 211 close to the first surface 111 and a second sub-surface portion 212 away from the first surface 111; in the first sub-surface portion 211, the doping concentration of boron is greater than the doping concentration of gallium; in the second sub-surface portion 212, the doping concentration of boron is greater than the doping concentration of gallium.

[0076] For example, such as Figure 2As shown, the first doped semiconductor layer 22 has a first sub-surface portion 211 near the first surface 111 and a second sub-surface portion 212 away from the first surface 111. The first sub-surface portion 211 is the first end of the first doped semiconductor layer 22 near the first surface 111 in the first direction Y. The second sub-surface portion 212 is the second end of the first doped semiconductor layer 22 away from the first surface 111 in the first direction Y. The first doped semiconductor layer 22 includes a first sub-surface 2101 near the first surface 111 and a second sub-surface 2102 away from the first surface 111. For example, any value within the range of 20nm-30nm extending inward from the first sub-surface 2101 constitutes the first sub-surface portion 211. For example, any value within the range of 20nm-30nm extending inward from the second sub-surface 2102 constitutes the second sub-surface 2102.

[0077] For example, such as Figure 2 As shown, in the first sub-surface portion 211, the doping concentration of boron is greater than that of gallium; in the second sub-surface portion 212, the doping concentration of boron is greater than that of gallium, thus maintaining the dominant doping effect of boron.

[0078] In some implementations, such as Figures 1 to 4 As shown, in the first doped semiconductor layer 22, the boron doping concentration is 1×10⁻⁶. 20 cm -3 -5×10 19 cm -3 .

[0079] For example, in the first doped semiconductor layer 22, the boron doping concentration is 1 × 10⁻⁶. 20 cm -3 -5×10 19 cm -3 The boron doping concentration can be 5 × 10⁻⁶. 19 cm -3 5.5×10 19 cm -3 6×10 19 cm -3 6.5×10 19 cm -3 7×10 19 cm -3 7.5×10 19 cm -3 8×10 19 cm -3 8.5×10 19 cm -3 9×10 19 cm -39.5×10 19 cm -3 1×10 20 cm -3 Any value in the range.

[0080] In some implementations, such as Figures 1 to 4 As shown, in the first doped semiconductor layer 22, the gallium doping concentration is 1×10⁻⁶. 18 cm -3 -1×10 19 cm -3 .

[0081] For example, in the first doped semiconductor layer 22, the gallium doping concentration can be 1 × 10⁻⁶. 18 cm -3 2×10 18 cm -3 3×10 18 cm -3 4×10 18 cm -3 5×10 18 cm -3 6×10 18 cm -3 7×10 18 cm -3 8×10 18 cm -3 9×10 18 cm -3 1×10 19 cm -3 Any value in the range.

[0082] For example, such as Figures 1 to 4 As shown, in the first doped semiconductor layer 22, the boron doping concentration is 1×10⁻⁶. 20 cm -3 -5×10 19 cm -3 The gallium doping concentration is 1×10⁻⁶. 18 cm -3 -1×10 19 cm -3 .

[0083] For example, such as Figures 1 to 4 As shown, in the first aspect, the boron doping concentration in the first sub-surface portion 211 is 1 × 10⁻⁶. 20 cm -3 Or, in the vicinity of this value, the gallium doping concentration is 1×10⁻⁶. 18 cm -3At or around this value, the boron doping concentration is high (compared to the boron doping of the second sub-surface 212), while the gallium doping concentration is low (compared to the gallium doping of the second sub-surface 212). The boron and gallium elements work synergistically. The higher concentration of boron doping ensures good electrical connection performance with the first electrode 24, guaranteeing low resistance conduction. The lower concentration of gallium doping suppresses the formation of BO pairs. This concentration of gallium is sufficient to compete with boron at the atomic scale, preferentially combining with interstitial oxygen in the substrate or occupying key positions, thereby fundamentally preventing the formation of BO pairs, the culprit of light-induced degradation (LID). Furthermore, excessively high boron concentrations can exceed the solid solubility of boron in the substrate 11, leading to defects such as boron clusters, which can become recombination centers and potentially damage the ultrathin tunneling oxide layer. Low gallium doping concentrations can avoid interfering with tunneling, while excessively high gallium doping concentrations may introduce too many defects and Coulomb scattering, interfering with the hole tunneling process and increasing resistance. Setting boron and gallium doping in the first sub-surface portion 211 within the aforementioned range or values ​​can improve or avoid these problems.

[0084] For example, such as Figures 1 to 4 As shown, in the second aspect, the boron doping concentration in the second sub-surface portion 212 is 5 × 10⁻⁶. 19 cm -3 Or, in the vicinity of this value, the gallium doping concentration is 1×10⁻⁶. 19 cm -3 At or near this value, the boron doping concentration is low (compared to the boron doping of the first sub-surface 211), while the gallium doping concentration is high (compared to the gallium doping of the first sub-surface 211). Boron and gallium work synergistically; the higher gallium concentration suppresses boron diffusion, and the higher gallium concentration further "fixes" and "stabilizes" boron atoms, forming an effective diffusion barrier layer. This prevents unfavorable diffusion of boron in any direction during long-term operation or high-temperature processes, significantly reducing boron diffusion into the bulk region of the substrate 11 during subsequent high-temperature processes. This avoids the formation of a dead layer due to boron diffusion and prevents a reduction in the minority carrier lifetime of the substrate 11's bulk region. Furthermore, this boron concentration is sufficient to ensure good lateral conductivity of the first doped semiconductor layer 22, ensuring uniform current collection. This gallium concentration is close to the solid solubility limit of gallium in the substrate 11, maximizing its "barrier" effect without generating harmful gallium clusters. This improves the thermal stability and long-term reliability of the doped structure, ensuring the durability of battery performance.

[0085] Therefore, by performing gradient co-doping of boron and gallium in the first doped semiconductor layer 22 on the third-direction Y1, the following synergistic effect is generated: using boron to achieve excellent electrical performance (conduction and field passivation), and using gallium to build a strong defense system (anti-attenuation and stable structure), the first doped semiconductor layer 22 is no longer a simple conductive layer in the traditional sense, but a "smart" composite functional layer that integrates efficient carrier transport, top-level surface passivation and intrinsic anti-attenuation functions.

[0086] In some implementations, such as Figures 1 to 4 As shown, in the first sub-surface portion 211, the boron doping concentration is 0.7 × 10⁻⁶. 20 cm -3 -1.5×10 20 cm -3 ; and / or, in the first sub-surface portion 211, the gallium doping concentration is 0.5 × 10⁻⁶. 18 cm -3 -3×10 18 cm -3 After considering process variations, the boron doping concentration in the first sub-surface portion 211 is 1×10⁻⁶. 20 cm -3 Or, near this value, the gallium doping concentration is 1×10⁻⁶. 18 cm -3 Alternatively, based on values ​​near this range, the doping concentrations of boron and gallium can be set within this range.

[0087] For example, in the first sub-surface portion 211, the boron doping concentration can be 0.7 × 10⁻⁶. 20 cm -3 0.8×10 20 cm -3 0.9×10 20 cm -3 1×10 20 cm -3 1.1×10 20 cm -3 1.2×10 20 cm -3 1.3×10 20 cm -3 1.4×10 20 cm -3 1.5×10 20 cm -3 Any value in the range.

[0088] For example, in the first sub-surface portion 211, the gallium doping concentration can be 0.5 × 10⁻⁶. 18 cm-3 0.8×10 18 cm -3 1×10 18 cm -3 1.2×10 18 cm -3 1.5×10 18 cm -3 1.8×10 18 cm -3 2×10 18 cm -3 2.3×10 18 cm -3 2.5×10 18 cm -3 2.8×10 18 cm -3 3×10 18 cm -3 Any value in the range.

[0089] In some implementations, such as Figures 1 to 4 As shown, in the second sub-surface portion 212, the boron doping concentration is 3 × 10⁻⁶. 19 cm -3 -8×10 19 cm -3 ; and / or, in the second sub-surface portion 212, the gallium doping concentration is 0.7 × 10⁻⁶. 19 cm -3 -2×10 19 cm -3 After considering process fluctuations, the boron doping concentration in the first sub-surface portion 211 is 5 × 10⁻⁶. 19 cm -3 Or, near this value, the gallium doping concentration is 1×10⁻⁶. 19 cm -3 Alternatively, based on values ​​near this range, the doping concentrations of boron and gallium can be set within this range.

[0090] For example, in the second sub-surface portion 212, the boron doping concentration can be 3 × 10⁻⁶. 19 cm -3 3.5×10 19 cm -3 4×10 19 cm -3 4.5×10 19 cm -3 5×10 19 cm -3 5.5×10 19 cm -3 6×10 19cm -3 6.5×10 19 cm -3 7×10 19 cm -3 7.5×10 19 cm -3 8×10 19 cm -3 Any value in the range.

[0091] For example, in the second sub-surface portion 212, the gallium doping concentration can be 0.7 × 10⁻⁶. 19 cm -3 0.9×10 19 cm -3 1×10 19 cm -3 1.2×10 19 cm -3 1.5×10 19 cm -3 1.8×10 19 cm -3 2×10 19 cm -3 Any value in the range.

[0092] For example, by co-doping boron and gallium in the first doped semiconductor layer 22 on the third-party Y1 according to the above concentration range, the following synergistic effect is generated: excellent electrical performance (conduction and field passivation) is achieved using boron, and a strong defense system (anti-attenuation and stable structure) is constructed using gallium. This makes the first doped semiconductor layer 22 no longer a simple conductive layer in the traditional sense, but a "smart" composite functional layer integrating efficient carrier transport, top-level surface passivation, and intrinsic anti-attenuation functions. More specifically, it includes: 1) excellent resistance to photo-induced attenuation: the LID attenuation rate is reduced from >1% of traditional B doping to <0.5%, or even lower; sufficient gallium atoms (>5×10⁻⁶) at the interface. 17 cm -3 1) Like a "goalkeeper," it preferentially interacts with oxygen, fundamentally inhibiting the formation of BO pairs. 2) High open-circuit voltage and excellent passivation effect enhance Voc: On the one hand, it has a low interface state density; the introduction of gallium and hydrogen passivation (described in subsequent examples) synergistically significantly reduce interface recombination; on the other hand, it has excellent bulk passivation, with an upper limit of surface gallium concentration (<2×10⁻⁶). 19 cm -3 This prevents the formation of gallium clusters and avoids new bulk recombination centers; at the same time, the gradient distribution of boron reduces its diffusion into the bulk region of the substrate, protecting the minority carrier lifetime of the bulk region. 3) Low series resistance and high fill factor: High boron concentration at the interface (>7×10⁻⁶) 19 cm-3 This ensures excellent ohmic contact; moderate gallium concentration (interface <3×10⁻⁶) 18 cm -3 4) Excellent process window and stability: The concentration range is set to take into account actual process fluctuations and is not a fragile "singularity"; the low diffusion coefficient and "barrier layer" effect of gallium ensure that the doping distribution remains stable during high-temperature processes and long-term operation; hydrogen passivation (described in subsequent examples) can effectively stabilize the doped structure and repair minor damage introduced during the process.

[0093] In some implementations, such as Figures 1 to 4 As shown, the material of the first tunneling layer 21 includes silicon oxide, and the material of the first doped semiconductor layer 22 includes polycrystalline silicon; and / or, the thickness of the first tunneling layer 21 is 1nm-2nm, and the thickness of the first doped semiconductor layer 22 is 50nm-150nm.

[0094] For example, the thickness of the first tunneling layer 21 is 1nm-2nm, and the thickness of the first tunneling layer 21 can be any value among 1nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, and 2nm.

[0095] For example, the thickness of the first doped semiconductor layer 22 is 50nm-150nm, and the thickness of the first doped semiconductor layer 22 can be any value among 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, and 150nm.

[0096] In some implementations, such as Figures 1 to 4 As shown, the first doped semiconductor layer 22 is also doped with hydrogen, and the hydrogen doping concentration is 1×10⁻⁶. 19 cm -3 -1×10 20 cm -3 .

[0097] For example, the first doped semiconductor layer 22 can be subjected to a hydrogen passivation process to further reduce the interface state density and decrease carrier recombination losses. The hydrogen doping concentration can be 1 × 10⁻⁶. 19 cm -3 2×10 19 cm -3 3×10 19 cm -3 4×10 19 cm -3 5×10 19 cm-3 6×10 19 cm -3 7×10 19 cm -3 8×10 19 cm -3 9×10 19 cm -3 1×10 20 cm -3 Any value in the range.

[0098] It should be noted that, as Figure 1 and Figure 3 As shown, the solar cell 100 may further include a first passivation layer 23 and a first electrode 24. The first passivation layer 23 is located on the side of the first doped semiconductor layer 22 away from the substrate 11, and the first electrode 24 is located on the side of the first passivation layer 23 away from the substrate 11. The first electrode 24 is electrically connected to the first doped semiconductor layer 22. The material of the first passivation layer 23 may include at least one of silicon oxide, silicon nitride, and silicon oxynitride.

[0099] It should be noted that, as Figure 1 and Figure 3 As shown, the solar cell 100 of this application is illustrated using an oxide-passivated contact (TOPCon) cell as an example. The first tunneling layer 21 and the first doped semiconductor layer 22 can also be applied to other types of solar cells, such as BC cells.

[0100] It should be noted that, as Figure 1 and Figure 3 As shown, the solar cell 100 also includes an emitter layer 12, a second passivation layer 13, and a second electrode 14. The emitter layer 12 is located on one side of the first surface 111, the second passivation layer 13 is located on the side of the emitter layer 12 away from the substrate 11, and the second electrode 14 is located on the side of the second passivation layer 13 away from the substrate 11. The second electrode 14 is electrically connected to the emitter layer 12.

[0101] It should be noted that in some implementation methods, such as Figure 1 In the TOPCon battery, the first surface 111 of the substrate 11 is the front side, and the first surface 111 may also have multiple textured structures R1. The textured structures R1 can be pyramidal structures or inverted pyramidal structures, which are not limited here. In some other embodiments, such as Figure 3 In the TOPCon battery, the second surface 112 of the substrate 11 is the front side, and the second surface 112 may also have multiple textured structures R1. The textured structure R1 can be a pyramid structure or an inverted pyramid structure, which is not limited here.

[0102] It should be noted that, as Figure 4 As shown, the solar cell 100 further includes a second tunneling layer 31, a second doped conductive layer 32, a second passivation layer 33, and a second electrode 34. The second tunneling layer 31 is located on one side of the first surface 111, the second doped conductive layer 32 is located on the side of the second tunneling layer 31 away from the substrate 11, the second passivation layer 33 is located on the side of the second doped conductive layer 32 away from the substrate 11, and the second electrode 34 is located on the side of the second passivation layer 33 away from the substrate 11. The second electrode 34 is electrically connected to the second doped conductive layer 32. Figure 4 This illustrates a double-sided oxide-passivated contact battery (double-sided TOPCon).

[0103] It should be noted that, in Figure 4 The schematic double-sided oxide passivated contact cell (double-sided TOPCon) may include a second doped conductive layer 32, which may include polycrystalline silicon and may be doped with phosphorus, but is not limited thereto.

[0104] Please see Figure 5 and Figure 6 , Figure 5 This is a schematic diagram of the process steps for manufacturing a solar cell according to an embodiment of this application. Figure 6 This is a schematic diagram of another process step in a method for manufacturing a solar cell provided in an embodiment of this application.

[0105] Secondly, based on the same application concept, such as Figure 5 and Figure 6 As shown, this application also provides a method for manufacturing a solar cell, and the solar cell 100 of any of the above claims can be manufactured using this method. Figure 5 As shown, the method for manufacturing a solar cell includes steps S100, S200, S300, and S400.

[0106] Step S100: A substrate is provided, the substrate having a first surface and a second surface disposed opposite to each other.

[0107] For example, a substrate 11 is provided, the substrate 11 having a first surface 111 and a second surface 112 disposed opposite to each other.

[0108] Step S200: A first tunneling layer is formed on the second surface.

[0109] For example, a first tunneling layer 21 is formed on the second surface 112.

[0110] Step S300: A first preset doped semiconductor layer is formed on the side of the first tunneling layer away from the substrate.

[0111] For example, a first pre-defined doped semiconductor layer is formed on the side of the first tunneling layer 21 away from the substrate 11.

[0112] For example, the first preset doped semiconductor layer is a film layer of the first doped semiconductor layer 22 before the doping of boron and gallium elements, and the first preset doped semiconductor layer can be a polycrystalline silicon film layer.

[0113] In step S400, boron and gallium are doped into the first preset doped semiconductor layer to form a first doped semiconductor layer; in the direction from the first surface to the second surface, the doping concentration of boron gradually decreases and the doping concentration of gallium gradually increases.

[0114] For example, boron and gallium are doped in a first pre-defined doped semiconductor layer to form a first doped semiconductor layer 22; in the direction from the first surface 111 to the second surface 112, the doping concentration of boron gradually decreases and the doping concentration of gallium gradually increases.

[0115] For example, in step S400, boron and gallium are doped in the first preset doped semiconductor layer to form the first doped semiconductor layer 22. In the third direction Y1, the doping concentration of boron gradually decreases and the doping concentration of gallium gradually increases.

[0116] It should be noted that the solar cell manufacturing method can manufacture any of the above-mentioned solar cells 100 and have the beneficial effects described above.

[0117] In some embodiments, the step of doping boron and gallium in the first preset doped semiconductor layer (step S400) includes: doping boron in the first preset doped semiconductor layer by an ion implantation process with an ion implantation kinetic energy of 10keV-30keV; and doping gallium in the first preset doped semiconductor layer by an ion implantation process with an ion implantation kinetic energy of 30keV-50keV.

[0118] For example, boron is doped into the first preset doped semiconductor layer by an ion implantation process, and the ion implantation kinetic energy can be any value among 10keV, 12keV, 15keV, 18keV, 20keV, 22keV, 25keV, 28keV, and 30keV.

[0119] For example, gallium is doped into the first preset doped semiconductor layer by an ion implantation process, and the ion implantation kinetic energy can be any value among 30keV, 35keV, 40keV, 45keV, and 50keV.

[0120] For example, gallium and boron have different atomic masses. At the same implantation energy, heavier gallium ions will be implanted much shallower than lighter boron ions. When doping into the first preset doped semiconductor layer, it is desirable that boron and gallium can be distributed in approximately the same depth range to achieve a synergistic effect. Therefore, by setting the above two different / appropriate ion implantation energies for boron and gallium, it is possible to make the heavier gallium ions reach a similar / the same depth as the lighter boron ions.

[0121] For example, in ion implantation processes, gradient distribution can be achieved using tilted implantation.

[0122] In some embodiments, the step of doping boron and gallium in the first preset doped semiconductor layer (step S400) includes: simultaneously doping boron and gallium in the first preset doped semiconductor layer by diffusion processes using boron and gallium sources, at a temperature of 800°C-950°C for 30-60 minutes.

[0123] For example, a mixed solid source of boron nitride (BN) and potassium oxide (Ga2O3) can be used, and diffusion can be performed at 800-950℃ for 30-60 min, with the doping gradient achieved by controlling the temperature gradient.

[0124] In some implementations, such as Figure 6 As shown, after the step of doping boron and gallium elements in the first preset doped semiconductor layer (step S400), the method further includes: step S500, laser annealing, wherein the wavelength of the laser is 300nm-1200nm, the energy density is 1J / cm²-3J / cm², the scanning speed is 50mm / s-200mm / s, and the annealing atmosphere is nitrogen.

[0125] For example, the laser annealing process described above can activate dopant atoms. By employing a low-temperature activation process, laser annealing selectively activates the dopant, avoiding Ga aggregation caused by high-temperature processes, reducing thermal budget, and improving production efficiency.

[0126] In some implementations, such as Figure 6 As shown, after the laser annealing step (step S500), the process further includes: step S600, hydrogen plasma passivation treatment, with a radio frequency power of 300W-500W, a time of 10min-30min, and a hydrogen flow rate of 50sccm-100sccm.

[0127] For example, hydrogen plasma passivation treatment at a temperature of 350°C. o C-450 oC. RF power is 300W-500W, time is 10min-30min, and hydrogen flow rate is 50sccm-100sccm. Appropriate temperature and RF power can, on the one hand, prevent insufficient diffusion of hydrogen atoms in silicon and polycrystalline silicon networks, thus avoiding their inability to effectively migrate to the interface to remove passivation defects (such as dangling bonds), resulting in poor passivation. On the other hand, it can prevent faster hydrogen diffusion, avoiding hydrogen escape (preventing the breakage of Si-H and Ga-H bonds that have already been passivated due to thermal vibration, allowing hydrogen atoms to escape from the structure), thus avoiding a "de-passivation" effect. Furthermore, it avoids dopant redistribution. For finely gradient doped structures formed by laser annealing, excessively high temperatures can cause unnecessary redistribution of boron (B) and gallium (Ga) atoms, disrupting the designed gradient distribution.

[0128] Please see Figure 7 , Figure 7 This is a schematic diagram comparing the embodiments of this application with related technologies. Embodiments 1 and 2 obtained solar cell 100 using the above-described solar cell manufacturing method. In embodiment 1, boron and gallium are doped using an ion implantation process in step S400, while in embodiment 2, boron and gallium are doped using a diffusion process in step S400. The comparative example is a solar cell in the related technology where only boron is doped in the first doped semiconductor layer 22. Figure 7 As can be seen from the comparison, the light-induced degradation (LID) in Examples 1 and 2 is significantly improved, and the conversion efficiency is improved. This shows that the solar cell 100 of any one of the above claims of this application, or the manufacturing method of any one of the solar cells, can effectively improve the light-induced degradation (LID), improve the conversion efficiency of the solar cell, and improve the performance of the solar cell.

[0129] Thirdly, based on the same concept, this application also provides a stacked battery, which includes a top battery, an adhesive layer and a bottom battery stacked sequentially, wherein the bottom battery is a solar cell 100 of any of the above.

[0130] For example, in some embodiments, the top cell can be a perovskite solar cell, which includes: a first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an antireflection layer stacked together. The first transport layer is directly opposite the bottom cell. The first transport layer can be either an electron transport layer or a hole transport layer, and the second transport layer can be either an electron transport layer or a hole transport layer.

[0131] It should be noted that the tandem cell of this application is based on the same concept as the solar cell 100 of any of the above claims, and the tandem cell has the same or similar effects as the solar cell 100 of any of the above claims, which will not be repeated here.

[0132] Please see Figure 8 , Figure 8 This is a schematic diagram of the structure of a photovoltaic module provided in an embodiment of this application.

[0133] Fourthly, based on the same application concept, this application also provides a photovoltaic module 200, which includes: a battery string 203, which is formed by connecting a plurality of solar cells 100 as described above, or by connecting solar cells 100 manufactured by a method for manufacturing a plurality of solar cells as described above, or by connecting tandem cells as described above; a connecting member 204 for electrically connecting two adjacent solar cells 100; an encapsulating film 202 for covering the surface of the battery string 203; and a cover plate 201 for covering the surface of the encapsulating film 202 facing away from the surface of the battery string 203.

[0134] For example, in some embodiments, the connecting component 204 may include a conductive strip, through which multiple battery strings 203 can be electrically connected. An encapsulating film 202 covers both the front and back sides of the solar cell or tandem solar cell.

[0135] For example, in some embodiments, the encapsulating film 202 may be an organic encapsulating film such as ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene coelastomer (POE) film, or polyethylene terephthalate (PET) film.

[0136] For example, in some embodiments, the cover plate 201 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function.

[0137] For example, in some embodiments, the surface of the cover plate 201 facing the encapsulation layer can be an uneven surface, thereby increasing the utilization of incident light.

[0138] It should be noted that the photovoltaic module 200 of this application and the solar cell 100 of any of the above claims are based on the same application concept, and the photovoltaic module 200 and the solar cell 100 of any of the above claims have the same or similar effects, which will not be repeated here.

[0139] 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.

[0140] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, include: The substrate has a first surface and a second surface disposed opposite to each other; The first tunneling layer is located on one side of the second surface; The first doped semiconductor layer is located on the side of the first tunneling layer away from the substrate; In this process, the first doped semiconductor layer is doped with boron and gallium, and in the direction from the first surface to the second surface, the doping concentration of boron gradually decreases and the doping concentration of gallium gradually increases. The first doped semiconductor layer has a first sub-surface portion close to the first surface and a second sub-surface portion away from the first surface; In the first sub-surface portion, the doping concentration of boron is greater than the doping concentration of gallium. In the second sub-surface portion, the doping concentration of boron is greater than that of gallium.

2. The solar cell according to claim 1, characterized in that, In the first doped semiconductor layer, the boron doping concentration is 1 × 10⁻⁶. 20 cm -3 -5×10 19 cm -3 .

3. The solar cell according to claim 1, characterized in that, In the first doped semiconductor layer, the gallium doping concentration is 1×10⁻⁶. 18 cm -3 -1×10 19 cm -3 .

4. The solar cell according to claim 1, characterized in that, In the first sub-surface portion, the boron doping concentration is 0.7 × 10⁻⁶. 20 cm -3 -1.5×10 20 cm -3 ; and / or, In the first sub-surface portion, the gallium doping concentration is 0.5 × 10⁻⁶. 18 cm -3 -3×10 18 cm -3 .

5. The solar cell according to claim 1, characterized in that, In the second sub-surface portion, the boron doping concentration is 3 × 10⁻⁶. 19 cm -3 -8×10 19 cm -3 ; and / or, In the second sub-surface portion, the gallium doping concentration is 0.7 × 10⁻⁶. 19 cm -3 -2×10 19 cm -3 .

6. The solar cell according to claim 1, characterized in that, The material of the first tunneling layer includes silicon oxide, and the material of the first doped semiconductor layer includes polycrystalline silicon; and / or, The thickness of the first tunneling layer is 1nm-2nm, and the thickness of the first doped semiconductor layer is 50nm-150nm.

7. The solar cell according to claim 1, characterized in that, The first doped semiconductor layer is also doped with hydrogen, and the hydrogen doping concentration is 1×10⁻⁶. 19 cm -3 -1×10 20 cm -3 .

8. A method for manufacturing a solar cell, characterized in that, include: A substrate is provided, the substrate having a first surface and a second surface disposed opposite to each other; A first tunneling layer is formed on the second surface; A first pre-defined doped semiconductor layer is formed on the side of the first tunneling layer away from the substrate; Boron and gallium are doped in the first pre-defined doped semiconductor layer to form a first doped semiconductor layer; in the direction from the first surface to the second surface, the doping concentration of boron gradually decreases and the doping concentration of gallium gradually increases; the first doped semiconductor layer has a first sub-surface portion close to the first surface and a second sub-surface portion away from the first surface; in the first sub-surface portion, the doping concentration of boron is greater than the doping concentration of gallium; in the second sub-surface portion, the doping concentration of boron is greater than the doping concentration of gallium.

9. The method for manufacturing a solar cell according to claim 8, characterized in that, The step of doping boron and gallium elements in the first preset doped semiconductor layer includes: Boron is doped into the first preset doped semiconductor layer by ion implantation, with an ion implantation kinetic energy of 10keV-30keV. Gallium is doped into the first preset doped semiconductor layer by ion implantation, with an ion implantation kinetic energy of 30keV-50keV.

10. The method for manufacturing a solar cell according to claim 8, characterized in that, The step of doping boron and gallium elements in the first preset doped semiconductor layer includes: In the first preset doped semiconductor layer, boron and gallium elements are simultaneously doped using diffusion processes with boron and gallium sources at a temperature of 800℃-950℃ for a time of 30min-60min.

11. The method for manufacturing a solar cell according to claim 8, characterized in that, After the step of doping boron and gallium elements in the first preset doped semiconductor layer, the method further includes: Laser annealing, wherein the wavelength of the laser is 300nm-1200nm, the energy density is 1J / cm²-3J / cm², the scanning speed is 50mm / s-200mm / s, and the annealing atmosphere is nitrogen.

12. The method for manufacturing a solar cell according to claim 11, characterized in that, Following the laser annealing step, the method further includes: Hydrogen plasma passivation treatment, with a radio frequency power of 300W-500W, a time of 10min-30min, and a hydrogen flow rate of 50sccm-100sccm.

13. A stacked battery, characterized in that, It includes a top cell, an adhesive layer, and a bottom cell stacked in sequence, wherein the bottom cell is a solar cell as described in any one of claims 1 to 7.

14. A photovoltaic module, characterized in that, include: A battery string, consisting of multiple solar cells connected as described in any one of claims 1 to 7, or multiple solar cells manufactured by the method of manufacturing solar cells as described in any one of claims 8 to 12, or multiple tandem solar cells as described in claim 13; a connecting member for electrically connecting two adjacent solar cells; An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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