Solar cell and photovoltaic module

Abstract

Provided in the present application are a solar cell and a photovoltaic module. The solar cell comprises a silicon wafer and an anti-reflective structure, wherein the anti-reflective structure comprises a first anti-reflective coating disposed on a surface of the silicon wafer and a second anti-reflective coating disposed on a surface of the first anti-reflective coating. The refractive index of the first anti-reflective coating is n1, and the refractive index of the second anti-reflective coating is n2, n1 and n2 satisfying one of the following relationships: (a) -0.4≤n2-n1≤-0.05; and (b) 0.1≤n2-n1≤0.4. On the basis of the design of a dual-anti-reflective-coating structure and the difference between the refractive indexes of the two anti-reflective coatings being within the above range, the dual-anti-reflective-coating structure as a whole has a stronger color-tuning effect. When there is a certain difference between the thickness of the edge of the cell and the thickness of the center of the cell, the colors of the edge and center of the cell remain consistent within a wider thickness range, and the colors of a contact point region and the other regions also remain consistent within the wider thickness range, such that the blue edge phenomenon and contact point marks are weakened or even completely masked, thereby improving the color uniformity and aesthetics of a surface of the solar cell.

Description

Solar cells and photovoltaic modules Technical Field

[0001] This application relates to the field of photovoltaic technology, and more particularly to a solar cell and a photovoltaic module. Background Technology

[0002] A thin film with reduced reflectivity is usually placed on the surface of solar cells. This film is called an anti-reflective coating. The anti-reflective coating can reduce the reflectivity of solar cells and improve cell efficiency.

[0003] Currently, common antireflective coating solutions include textured surface antireflection and / or antireflective coating antireflection. For example, pyramid textured surfaces achieve antireflection by changing the surface structure and the light path; silicon nitride or silicon oxide films are used as antireflective films to increase light transmission and achieve antireflection. However, all of the above antireflective structures have problems such as difficulty in color matching, uneven surface color, obvious blue edges, and significant markings. Summary of the Invention

[0004] The purpose of this application is to provide a solar cell and a photovoltaic module to solve the technical problems of existing cells, such as obvious blue edges, uneven surface color, and significant markings.

[0005] To achieve the above objectives, in a first aspect, this application provides a solar cell comprising: a silicon wafer and an anti-reflection structure disposed on the surface of the silicon wafer. The anti-reflection structure includes a first anti-reflection layer disposed on the surface of the silicon wafer and a second anti-reflection layer disposed on the surface of the first anti-reflection layer. The refractive index of the first anti-reflection layer is n1, and the refractive index of the second anti-reflection layer is n2, wherein n1 and n2 satisfy one of the following relationships: (a) -0.4 ≤ n2 - n1 ≤ -0.05; (b) 0.1 ≤ n2 - n1 ≤ 0.4.

[0006] Based on a dual antireflective layer structure design consisting of a second and a first antireflective layer, and setting the difference in refractive index between the two layers within the range of relationship (a) or (b), the dual antireflective layer structure possesses a strong color-adjusting effect, ensuring that different parts of the solar cell maintain the same color across a wide thickness range. In other words, even when there is a certain difference in thickness between the edge and center of the solar cell, this application, based on the difference in refractive index between the upper second antireflective layer and the lower first antireflective layer satisfying relationship (a) or (b), ensures that the edge and center regions of the solar cell maintain a consistent color across a wide thickness range, and the color of the obstruction area remains consistent with other areas across a wide thickness range. This weakens or even completely masks blue edges and obstruction marks, thereby improving the color uniformity and aesthetics of the solar cell surface. Furthermore, since the solar cell of this application has a wide tolerance range for thickness differences in different regions, under suitable process conditions, it can ensure a consistent color ratio between high and low incident angles. Therefore, this application can also mitigate thickness variations caused by different viewing angles and the resulting color differences.

[0007] As one possible implementation, 1.6 ≤ n² ≤ 2.6.

[0008] Based on relation (a) or relation (b), and the refractive index n2 of the second antireflection layer within the above range, the refractive index n2 of the second antireflection layer can be matched with the refractive index n1 of the first antireflection layer, and the refractive index n2 of the second antireflection layer can be made slightly higher or slightly lower than the refractive index n1 of the first antireflection layer, so that the second antireflection layer and the first antireflection layer as a whole form a refractive index gradient structure, thereby significantly enhancing the overall color-tuning effect of the double-layer antireflection structure. This ensures that the color change of the solar cell of this application under incident light irradiation can adapt to a wider thickness range.

[0009] As one possible implementation, at least one of the first and second antireflection layers is made of one, two, or three compounds selected from rare earth element compounds and / or transition metal compounds.

[0010] Because the first and / or second antireflective layers are made of rare earth element compounds and transition metal compounds, their refractive indices can reach a suitable range (e.g., 1.6 to 2.6). Therefore, the second and first antireflective layers can form a special refractive index gradient structure, which can significantly increase the light absorption capacity of the solar cell. Furthermore, the special refractive index of this type of material allows for a double antireflective layer structure with a refractive index difference of 0.1 to 0.4. This facilitates the selection of rare earth elements or transition metal elements in the first and / or second antireflective layers, as well as the control of the thickness of the first and / or second antireflective layers. This allows for the reduction of blue light reflectivity, the increase of near-infrared light absorption efficiency, or the increase of red and green light reflectivity, thereby suppressing the efficiency degradation of the solar cell and adjusting the cell color.

[0011] As one possible implementation, the rare earth element in the rare earth compound includes one, two, or three of the following: Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. This arrangement provides a wider variety of rare earth elements, facilitating the selection of appropriate elements based on different practical needs and improving the applicability of the solar cell provided in this application to various application scenarios.

[0012] As one possible implementation, the transition metal element in the transition metal compound includes one, two, or three of the following: Ti, V, Cu, Zn, Mo, W, Co, Ni, and Re. This arrangement provides a wider variety of transition metal elements, facilitating the selection of appropriate transition metal elements based on different practical needs, and improving the applicability of the solar cell provided in this application to various application scenarios.

[0013] As one possible implementation, the thickness of the first anti-reflection layer is H1, and the thickness of the second anti-reflection layer is H2. H1 and H2 satisfy the following functional relationship: H1 + H 2＝ H+c. Where H is the total thickness of the first and second antireflection layers that give the solar cell a specific color, and c is the thickness tolerance that gives the solar cell a specific color.

[0014] Functional relation H1+H 2＝ H+c is a derived relationship based on the refractive index difference between the first and second antireflection layers and Fresnel's law. The color change of a solar cell exhibits a periodic variation with thickness. Based on the newly added second antireflection layer, the color change period, median total thickness, and thickness range of the solar cell vary with the refractive index difference between the two antireflection layers. This is based on the functional relationship H1+H. 2＝H+c allows for rapid adjustment of the thickness of the first and second antireflection layers, enabling solar cells to display specific colors and meet the needs of different practical applications.

[0015] As one possible implementation, 0 < H2 < 180nm, H = 140nm, and -40nm < c < 40nm. This configuration facilitates the realization of a black solar cell and a black module.

[0016] As one possible implementation, the second antireflection layer includes an edge region and a central region located inside the edge region. The thickness of the central region is h1, and the thickness of the edge region is h2, wherein h1 and h2 satisfy the following relationship: 0nm≤h1-h2≤40nm.

[0017] When forming the second antireflection layer, due to limitations or influences in the process conditions, there may be thickness differences between the edge and central regions of the second antireflection layer. Since the second antireflection layer in this application is a new film structure formed on top of the first antireflection layer, the design of a double antireflection layer structure, based on the second and first antireflection layers, allows the refractive index relationship between the two to satisfy (a) or (b). This ensures that when the thickness difference between the edge and central regions of the second antireflection layer is within the aforementioned wider range, the color of the edge and central regions of the solar cell can remain essentially consistent under incident light. This weakens or even completely masks the blue edge phenomenon, thereby improving the color uniformity and aesthetics of the solar cell surface. Compared to existing antireflection structures, the thickness difference between the edge and central regions of the second antireflection layer in this application has a wider range of selectable values. For example, in order to reduce color differences between different regions, the tolerance for the thickness difference between the edge and middle regions of the antireflection structure film layer in existing batteries is less than 10 nm, while the upper limit of the tolerance for the thickness difference between the edge and middle regions of the second antireflection layer in this application can be set to 40 nm. This not only enables the solar cell of this application to have or even surpass the color uniformity effect of existing batteries, but also reduces the process difficulty of manufacturing the second antireflection layer.

[0018] As one possible implementation, the silicon wafer includes a substrate and a textured structure formed on the surface of the substrate, with an anti-reflection structure disposed on the surface of the textured structure. This arrangement can improve the light-trapping effect of the substrate surface and increase the light utilization rate of the solar cell.

[0019] Secondly, this application provides another type of solar cell, which includes a silicon wafer and an anti-reflection structure disposed on the surface of the silicon wafer. In the wavelength range of incident light from 380 nm to 1100 nm, the reflectivity variation curve of the solar cell has two troughs, including a first trough and a second trough.

[0020] By reducing the reflectivity of incident light in specific wavelengths (i.e., creating a trough in the incident light within a specific wavelength range) according to actual needs, and maintaining or even increasing the reflectivity of other wavelengths, the ratio of different wavelengths of incident light that can be visually received can be adjusted, thereby achieving the adjustment of the cell's color. The reflectivity variation curve of a solar cell has double troughs, resulting in stronger adjustment capabilities. Furthermore, the ratio of light wavelengths that the cell can receive and utilize can be adjusted; for example, increasing the light absorption efficiency in the near-infrared region of the cell can increase the current and improve the working performance of the solar cell.

[0021] As one possible implementation, there is a peak between the first and second troughs. Specifically, the first trough is located in the wavelength range of 380 nm to 500 nm; and / or, the second trough is located in the wavelength range of 800 nm to 1100 nm. Alternatively, the peak is located in the wavelength range of 400 nm to 800 nm.

[0022] It's understandable that different wavelengths of light correspond to different colors; for example, 600nm to 700nm is red light, 500nm to 570nm is green light, and 400nm to 470nm is blue light. When a battery exhibits a blue edge effect, a reflectivity curve characterized by dual troughs can be designed so that the first trough falls within the 380nm to 500nm wavelength range. In this case, the reflectivity in the blue light band is lower, weakening the blue light intensity of the battery and reducing the relative difference in blue light intensity between the central and edge regions, thus minimizing color difference between them. Furthermore, the peak in the reflectivity curve can be located within the 400nm to 800nm ​​wavelength range, i.e., within the visible light range. Adjusting the peak position and intensity allows for control over the battery's color and brightness to meet the requirements of different color batteries in various practical applications. When the characteristics of a wavelength peak between 500nm and 700nm and a first trough between 380nm and 500nm are simultaneously satisfied, adjusting the ratio of the three primary colors—blue, red, and green—to 1:1:1 can create a near-black solar cell, forming a black module. Furthermore, when the cell exhibits a blue edge phenomenon, setting the wavelength peak between 500nm and 700nm increases the reflectivity of the antireflective structure in the red and green light regions, thus diluting the blue light ratio and reducing the difference in blue light between the edge and center regions of the cell, potentially even eliminating the blue edge phenomenon. Setting the second trough within the range of 800nm ​​to 1100nm enhances the cell's absorption efficiency for near-infrared incident light, thereby increasing the current and helping the cell maintain higher efficiency. Because the wavelength range in which the first trough may occur and the wavelength range in which the first peak may occur partially overlap, it should be understood that for the reflectivity change curve of the same battery, the wavelengths of the first trough and the peak will not overlap. However, for the reflectivity change curves of different batteries, the wavelength range in which the first trough may occur and the wavelength range in which the first peak may occur may partially overlap. That is, the wavelength corresponding to the first trough of the reflectivity change curve of one battery is equal to the wavelength corresponding to the peak of the reflectivity change curve of another battery. For example, the wavelength corresponding to the first trough of the reflectivity change curve of one battery is 410 nm, and the wavelength corresponding to the peak of the reflectivity change curve of another battery is 410 nm.

[0023] As one possible implementation, the reflectivity corresponding to the wave crest is less than 5%, and / or the reflectivity corresponding to the second wave trough is less than 2.1%.

[0024] When the reflectivity corresponding to the peak is less than 5%, it is conducive to the formation of a black cell and the realization of a black module. When the reflectivity corresponding to the peak is greater than or equal to 5%, the reflection of red and green light is stronger, which is not conducive to the formation of a black cell and the realization of a black module. In addition, compared with the first trough, the second trough is in the near-infrared light range. Therefore, when the reflectivity corresponding to the second trough is less than 2.1%, the cell has a better promoting effect on the absorption of near-infrared light, which can effectively improve the cell conversion efficiency. It can be understood that the smaller the reflectivity corresponding to the second trough, the higher the absorption rate of near-infrared light, and the higher the cell efficiency.

[0025] As one possible implementation, the difference between the reflectivity corresponding to the wave crest and the reflectivity corresponding to the first wave trough is greater than or equal to 0.01 and less than 5%; and / or, the difference between the reflectivity corresponding to the wave crest and the reflectivity corresponding to the second wave trough is greater than or equal to 0.01% and less than 5%.

[0026] When the difference between the reflectance corresponding to the peak and the reflectance corresponding to the first trough is within the aforementioned range, it is beneficial to form a black battery and a black component. The reflectance corresponding to a specific wavelength of incident light (e.g., 500nm to 700nm) is greater than the reflectance of another specific wavelength of incident light (e.g., 380nm to 500nm), meaning different reflectances for different colors of incident light. This allows for adjustable proportions of the three primary colors (red, blue, and green), thereby enabling adjustment of the battery color. Simultaneously, it avoids excessively large differences that would prevent the battery from forming a black color and thus prevent the formation of a black component.

[0027] When the difference between the reflectance corresponding to the peak and the reflectance corresponding to the second trough is within the above range, it can prevent the high reflectance of the peak from causing excessive reduction in battery efficiency.

[0028] One possible implementation is to set the reflectivity of the first trough to be greater than that of the second trough. This setting ensures that the reflectivity of the first trough has a certain value to adjust the color, allowing the battery color to meet practical requirements. Simultaneously, it ensures that the reflectivity of the second trough is low, which helps guarantee better absorption of near-infrared light by the battery, thus maintaining battery efficiency.

[0029] As one possible implementation, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to incident light at a wavelength of 380nm is greater than the reflectivity corresponding to the peak. This setting achieves a match between the cell's color adjustment objective and its efficiency.

[0030] As one possible implementation, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to incident light at a wavelength of 1100 nm is greater than the reflectivity corresponding to the peak. This setting allows the cell efficiency to be maintained at a relatively good level.

[0031] As one possible implementation, in the reflectivity variation curve of a solar cell, the reflectivity value corresponding to incident light with a wavelength of 1100 nm is greater than the reflectivity corresponding to incident light with a wavelength of 380 nm.

[0032] As one possible implementation, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to incident light with a wavelength of 380nm is greater than the reflectivity corresponding to the first trough and the second trough. The application principle of the beneficial effect in this case can be referred to the application principle of the beneficial effect of the reflectivity corresponding to incident light with a wavelength of 380nm being greater than the reflectivity corresponding to the peak, as described above, and will not be repeated here.

[0033] As one possible implementation, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to incident light with a wavelength of 1100 nm is greater than the reflectivity corresponding to the first trough and the second trough. The application principle of the beneficial effect in this case can be referred to the application principle of the beneficial effect of the reflectivity corresponding to incident light with a wavelength of 1100 nm being greater than the reflectivity corresponding to the peak, as described above, and will not be repeated here.

[0034] As one possible implementation, within the wavelength range of incident light from 380nm to 1100nm, the reflectivity variation curve of the solar cell shows a trend of decreasing, increasing, decreasing again, and increasing again as the wavelength increases.

[0035] The anti-reflection structure of this application can achieve three functions through the characteristics of double troughs: selecting specific colors, unifying the colors at the edges and center, and achieving near-infrared light absorption gain from 700nm to 1000nm (the characteristic of this gain range is that the wavelength of the enhanced light is slightly lower than the wavelength corresponding to the energy band of crystalline silicon). In order to adjust the color, the purpose of suppressing the efficiency degradation of solar cells can be achieved, thereby improving the working performance of solar cells.

[0036] As one possible implementation, the anti-reflection structure includes a first anti-reflection layer and a second anti-reflection layer, wherein the first anti-reflection layer is disposed on the surface of the silicon wafer, and the second anti-reflection layer is disposed on the surface of the first anti-reflection layer away from the silicon wafer.

[0037] As one possible implementation, the thickness of the first anti-reflection layer is H1, and the thickness of the second anti-reflection layer is H2. H1 and H2 satisfy the following functional relationship: H1 + H 2＝ H+c. Where H is the total thickness of the first and second antireflection layers that give the solar cell a specific color, and c is the thickness tolerance that gives the solar cell a specific color.

[0038] Functional relation H1+H 2＝H+c is a derived relationship based on the refractive index difference between the first and second antireflection layers and Fresnel's law. The color change of a solar cell exhibits a periodic variation with thickness. Based on the newly added second antireflection layer, the color change period, median total thickness, and thickness range of the solar cell vary with the refractive index difference between the two antireflection layers. This is based on the functional relationship H1+H. 2＝ H+c allows for rapid adjustment of the thickness of the first and second antireflection layers, enabling solar cells to display specific colors and meet the needs of different practical applications.

[0039] As one possible implementation, 0 < H2 < 180nm, H = 140nm, and -40nm < c < 40nm. This configuration facilitates the realization of a black solar cell and a black module.

[0040] As one possible implementation, the second antireflection layer includes an edge region and a central region located inside the edge region. The thickness of the central region is h1, and the thickness of the edge region is h2, wherein h1 and h2 satisfy the following relationship: 0nm≤h1-h2≤40nm.

[0041] When forming the second antireflective layer, thickness differences may exist between the edge and central regions due to limitations or influences in the process conditions. Since the second antireflective layer in this application is a new film structure formed on top of the first antireflective layer, the design utilizes a dual antireflective layer structure. By adjusting the refractive index and / or thickness of both layers, the resulting antireflective structure exhibits a double-valley reflectance variation curve, thereby adjusting the cell color. Compared to existing antireflective structures, the thickness difference between the edge and central regions of the second antireflective layer in this application has a wider range of options. For example, to reduce color differences between different regions, the tolerance for the thickness difference between the edge and central regions of the antireflective structure in existing cells is less than 10 nm, while the upper limit of the tolerance for the thickness difference between the edge and central regions of the second antireflective layer in this application can be set to 40 nm. This not only enables the solar cell of this application to achieve or even surpass the color uniformity effect of existing cells but also reduces the manufacturing difficulty of the second antireflective layer.

[0042] As one possible implementation, the silicon wafer includes a substrate and a textured structure formed on the surface of the substrate, with an anti-reflection structure disposed on the surface of the textured structure. This arrangement can improve the light-trapping effect of the substrate surface and increase the light utilization rate of the solar cell.

[0043] Thirdly, this application also provides another type of solar cell, which includes a silicon wafer and an anti-reflection structure disposed on the surface of the silicon wafer. The anti-reflection structure includes a first anti-reflection layer disposed on the surface of the silicon wafer and a second anti-reflection layer disposed on the surface of the first anti-reflection layer. The second anti-reflection layer includes an edge region and a central region located inside the edge region, the thickness of the central region is h1, and the thickness of the edge region is h2, wherein h1 and h2 satisfy the following relationship: 0nm ≤ h1 - h2 ≤ 40nm.

[0044] The beneficial effects of the third aspect and its various implementations in this application can be found in the analysis of the beneficial effects of the first and second aspects and their corresponding implementations, and will not be repeated here.

[0045] Fourthly, this application provides a photovoltaic module, which includes solar cells as provided in the first to third aspects and various implementations thereof.

[0046] The beneficial effects of the fourth aspect and its various implementations in this application can be found in the analysis of the beneficial effects of the first to third aspects and their various implementations, and will not be repeated here. Attached Figure Description

[0047] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0048] Figure 1 is a schematic diagram of the structure of the solar cell provided in an embodiment of this application;

[0049] Figure 2 is a schematic diagram of the structure of the second antireflection layer provided in an embodiment of this application;

[0050] Figure 3 is a comparison of the reflectivity of the antireflection structure of the solar cell provided in this application embodiment with the reflectivity of existing antireflection structures.

[0051] Figure reference numerals: 100 is solar cell, 10 is silicon wafer, 11 is main body, 12 is textured structure, 20 is first antireflection layer, 30 is second antireflection layer, 31 is edge region, and 32 is central region. Detailed Implementation

[0052] The embodiments of this application will now 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 this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0053] The accompanying drawings illustrate various structural schematics according to embodiments of this application. These drawings are not to scale, and some details have been enlarged and may have been omitted for clarity. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0054] In the context of this application, when a layer / element is referred to as being "on top of" another layer / element, the layer / element can be directly on top of the other layer / element, or there can be an intermediate layer / element between them. Furthermore, if a layer / element is "on top of" another layer / element in one orientation, then when the orientation is reversed, the layer / element can be "below" the other layer / element. To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0055] Furthermore, the terms "first" and "second" are used 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 as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0056] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0057] In a first aspect, embodiments of this application provide a solar cell. Figure 1 is a schematic structural diagram of a solar cell provided according to one embodiment of this application. Referring to Figure 1, the solar cell 100 provided in this application embodiment includes a silicon wafer 10 and an anti-reflection structure sequentially disposed along its thickness direction. The anti-reflection structure includes a first anti-reflection layer 20 disposed on the surface of the silicon wafer 10 and a second anti-reflection layer 30 disposed on the surface of the first anti-reflection layer 20.

[0058] In the actual manufacturing process, the first antireflection layer 20 can be a film structure (also called an antireflection film) set on the surface of the silicon wafer 10 by physical vapor deposition (PVD) or chemical vapor deposition (CVD), and the second antireflection layer 30 can also be a film structure (also called an antireflection film) set on the surface of the first antireflection layer 20 by PVD, CVD, or other methods.

[0059] In the solar cell 100 of this application embodiment, the refractive index of the first antireflection layer 20 is n1, and the refractive index of the second antireflection layer 30 is n2. n1 and n2 satisfy the following relationship (a) or (b).

[0060] (a): -0.4 ≤ n2 - n1 ≤ -0.05, meaning the refractive index of the upper second antireflection layer 30 can be slightly lower than the refractive index of the lower first antireflection layer 20. In this case, the second antireflection layer 30 and the first antireflection layer 20 together form a refractive index gradient structure. For example, n2 - n1 can be -0.4, -0.35, -0.32, -0.3, -0.25, -0.23, -0.2, -0.15, -0.1, -0.05, etc.

[0061] (b): 0.1 ≤ n2 - n1 ≤ 0.4, meaning the refractive index of the upper second antireflection layer 30 can be slightly higher than the refractive index of the lower first antireflection layer 20. In this case, the second antireflection layer 30 and the first antireflection layer 20 together form a refractive index gradient structure. For example, n2 - n1 can be 0.1, 0.15, 0.18, 0.2, 0.23, 0.25, 0.3, 0.35, 0.38, 0.4, etc.

[0062] It should be noted that the refractive index n1 of the first antireflection layer 20 and the refractive index n2 of the second antireflection layer 30 can be determined by, after knowing the materials of the first antireflection layer 20 and the second antireflection layer 30, by using known and accepted testing methods (e.g., by consulting scientific literature and databases, such as refractiveindex.info, by estimating through effective medium theory, by using a spectroscopic ellipsometer, or by using reflection / transmission spectroscopy analysis, etc.) to obtain the magnitude of the refractive index n1 of the first antireflection layer 20 and the refractive index n2 of the second antireflection layer 30, and then by deducing the magnitude of the difference between n2 and n1.

[0063] Furthermore, due to the inherent thickness difference (e.g., 10 nm) between the edge and center regions of solar cells in related technologies, existing antireflection structures result in higher blue light reflectivity at the edges of the solar cell compared to the center under incident light (especially strong light). This makes the edge regions appear whiter and more bluish than the center, a phenomenon known as the "blue edge phenomenon." Moreover, antireflection structures are typically formed on the silicon wafer of solar cells through coating. During the coating process, fixing points are usually required. After coating, the film thickness at these fixing points is thinner and the color differs from other areas, creating a noticeable mark. This results in a distinct fixing point mark on the solar cell.

[0064] In this embodiment, based on the dual antireflection layer structure design of the second antireflection layer 30 and the first antireflection layer 20, and setting the difference in refractive index between the two within the range of relationship (a) or relationship (b), the dual antireflection layer structure as a whole has a strong color-tuning effect, thereby ensuring that different parts of the solar cell still present the same color over a wide thickness range. In other words, the color change of the solar cell 100 under incident light irradiation in this embodiment has a wide tolerance range for thickness differences in different regions. Therefore, even when there is a certain difference in thickness between the edge region and the middle region of the solar cell, this embodiment, based on the difference in refractive index between the upper second antireflection layer 30 and the lower first antireflection layer 20, ensures that the edge region and the middle region of the solar cell maintain the same color over a wide thickness range, and the color of the stuck area remains consistent with other areas over a wide thickness range. This weakens or even completely covers the blue edge phenomenon and stuck mark, thereby improving the color uniformity and aesthetics of the surface of the solar cell 100. In addition, since the solar cell 100 of this application embodiment has a wide tolerance range for thickness, under suitable process conditions, it is possible to ensure that the color ratio is consistent between high incident angle (side view) and low incident angle (front view). Thus, this application embodiment can also mitigate the thickness variation caused by different viewing angles and the resulting color difference problem.

[0065] Referring to Figure 1, exemplarily, the silicon wafer 10 may include a body 11 and a textured structure 12 formed on the surface of the body 11, with an anti-reflection structure disposed on the surface of the textured structure 12. This configuration alters the surface structure of the silicon wafer 10, achieving an anti-reflection effect by changing the light path of incident light, thereby improving the light absorption rate of the silicon wafer and increasing the conversion efficiency of the solar cell. The textured structure 12 can be a pyramidal textured structure, a perforated textured structure, or a V-groove textured structure, etc.

[0066] Of course, the surface of a silicon wafer can also be flat.

[0067] For the first antireflection layer 20 and the second antireflection layer 30, the specific values ​​of the refractive index n1 of the first antireflection layer 20 and the refractive index n2 of the second antireflection layer 30, the thickness of the first antireflection layer 20 and the second antireflection layer 30, and the materials of the first antireflection layer 20 and the second antireflection layer 30 can be determined according to the color requirements, light trapping requirements and other practical needs of the solar cell in the actual application scenario, as long as n1 and n2 satisfy either relationship (a) or relationship (b).

[0068] In some embodiments, 1.6 ≤ n2 ≤ 2.6. For example, n2 can be 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, 2.05, 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.5, 2.6, etc.

[0069] The value of n1 can be determined based on relations (a) and (b), the range of n2, and the actual situation. For example, in the embodiments of this application, n1 can satisfy: 2.0≤n1≤2.8.

[0070] Based on relation (a) or relation (b), and the refractive index n2 of the second antireflection layer 30 within the above range, the refractive index n1 of the first antireflection layer 20 can be matched with the refractive index n2 of the second antireflection layer 30, and the refractive index n2 of the second antireflection layer 30 can be made slightly higher or slightly lower than the refractive index n1 of the first antireflection layer 20, so that the second antireflection layer 30 and the first antireflection layer 20 are formed as a refractive index gradient structure, thereby significantly enhancing the overall color-tuning effect of the double-layer antireflection structure. This ensures that the color change of the solar cell 100 in this embodiment of the present application adapts to a wider thickness range under incident light irradiation. Alternatively, based on relation (a) or relation (b), and the refractive index n1 of the first antireflection layer 20 within a certain range, the refractive index n2 of the second antireflection layer 30 can be matched with the refractive index n1 of the first antireflection layer 20, and the refractive index n2 of the second antireflection layer 30 can be made slightly higher or slightly lower than the refractive index n1 of the first antireflection layer 20, so that the second antireflection layer 30 and the first antireflection layer 20 are formed as a refractive index gradient structure, thereby significantly enhancing the overall color-tuning effect of the double-layer antireflection structure. This ensures that the color change of the solar cell 100 in this embodiment of the present application adapts to a wider thickness range under incident light irradiation.

[0071] For example, when the refractive index n1 of the first antireflection layer 20 is selected as 2.0, the refractive index n2 of the second antireflection layer 30 can be 1.6 to 1.95 or 2.1 to 2.4. Optionally, n2 can be 1.7 to 1.9 or 2.2 to 2.3.

[0072] In some embodiments, at least one of the first antireflection layer 20 and the second antireflection layer 30 may be made of one, two, or three compounds selected from rare earth element compounds and / or transition metal compounds. It is understood that rare earth element compounds refer to compounds composed of rare earth elements and other non-rare earth elements, and transition metal compounds refer to compounds composed of transition metal elements and other non-transition metal elements. With this configuration, since the first antireflection layer 20 and / or the second antireflection layer 30 are made of rare earth element compounds and transition metal compounds, the refractive index of the first antireflection layer 20 and / or the second antireflection layer 30 can reach a suitable range (e.g., 1.6 to 2.6). Therefore, the second antireflection layer 30 and the first antireflection layer 20 can form a special refractive index gradient structure, which can significantly increase the light absorption capacity of the solar cell 100. Furthermore, the special refractive index of this type of material can achieve a double antireflection layer structure with a refractive index difference of 0.1 to 0.4. This allows for the reduction of blue light reflection, the increase of near-infrared light absorption, and the increase of red and green light reflectivity by specifically selecting rare earth elements or transition metal elements in the first antireflection layer 20 and / or the second antireflection layer 30, as well as by controlling the thickness of the first antireflection layer 20 and / or the second antireflection layer 30. This can suppress the efficiency degradation of the solar cell 100 and adjust the cell color at the same time.

[0073] The types of rare earth elements in rare earth element compounds and transition metal elements in transition metal compounds can be determined based on the requirements for the refractive indices of the first antireflection layer 20 and the second antireflection layer 30, as well as other practical needs. The materials of the first antireflection layer 20 and the second antireflection layer 30 can be the same or different. When the materials of the first antireflection layer 20 and the second antireflection layer 30 are the same, the refractive indices of the first antireflection layer 20 and the second antireflection layer 30 can be adjusted by adjusting their thicknesses, etc., so that the refractive indices n1 of the first antireflection layer 20 and n2 of the second antireflection layer 30 satisfy the above relationship (a) or relationship (b).

[0074] For example, the rare earth elements in the rare earth element compound may include one, two or three of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

[0075] For example, the transition metal element in the transition metal compound may include one, two or three of Ti, V, Cu, Zn, Mo, W, Co, Ni and Re.

[0076] In some embodiments, the material of the first antireflection layer 20 may be silicon nitride. In some embodiments, the material of the first antireflection layer 20 may be one, two, or three compounds, which may be selected from rare earth element compounds and / or transition metal compounds. In some embodiments, the material of the first antireflection layer 20 may be silicon nitride and at least one compound selected from rare earth element compounds and / or transition metal compounds.

[0077] For example, the second antireflective layer 30 can be cerium oxide (CeO2), yttrium oxide, tungsten oxide, etc., so that the refractive index n2 of the second antireflective layer 30 can be between 1.6 and 2.6. In addition, cerium oxide, yttrium oxide, and tungsten oxide are heat-resistant, meaning that their optical properties are not affected by high temperatures and will not change during the manufacturing process and application. They also have the function of absorbing ultraviolet rays, which can reduce the UV decay of the solar cell 100, improve the ultraviolet tolerance of the cell, and have better applicability to areas with strong ultraviolet radiation (deep space, plateaus, high latitudes, deserts).

[0078] Optionally, the first antireflection layer 20 can be made of silicon nitride, and the second antireflection layer 30 can be made of rare earth element compounds (such as CeO2).

[0079] Optionally, the first antireflection layer 20 can be made of silicon nitride, and the second antireflection layer 30 can be made of a transition metal compound.

[0080] Optionally, the material of the first antireflection layer 20 can be a rare earth element compound (such as CeO2), and the material of the second antireflection layer 30 can be a transition metal compound.

[0081] Optionally, the material of the first antireflection layer 20 can be a transition metal compound, and the material of the second antireflection layer 30 can be a rare earth element compound (such as CeO2).

[0082] Optionally, the material of the first antireflection layer 20 can be a transition metal compound, and the material of the second antireflection layer 30 can be a transition metal compound.

[0083] Optionally, the material of the first antireflection layer 20 can be a rare earth element compound (such as CeO2), and the material of the second antireflection layer 30 can be a rare earth element compound (such as CeO2 and / or Nd2O3).

[0084] Optionally, the material of the first antireflection layer 20 can be a rare earth element compound (such as CeO2), and the material of the second antireflection layer 30 can be silicon nitride.

[0085] Based on the dual antireflection layer structure design of the second antireflection layer 30 and the first antireflection layer 20, the second antireflection layer 30 and the first antireflection layer 20 in this embodiment of the application have more material options. By selecting specific materials for the first antireflection layer 20 and the second antireflection layer 30 and adjusting the thickness of the first antireflection layer 20 and the second antireflection layer 30, the peak position and peak value of the reflectivity change curve of the dual antireflection layer structure can be controlled, thereby achieving the adjustment of battery efficiency and color.

[0086] Furthermore, by adjusting the thickness of the second antireflection layer 30, the transmittance or reflectance at a specific wavelength (specific color) can be selectively increased. Secondly, the surface color of the cell formed by the first antireflection layer 20 with different thicknesses is different. Therefore, by matching the first antireflection layer 20 with a second antireflection layer 30 of a specific thickness, the proportions of the three primary colors (red, green, and blue) can be adjusted, thus forming a solar cell 100 of a specific color. Based on this, the thicknesses of the first antireflection layer 20 and the second antireflection layer 30 can be set according to the requirements of the cell color and the absorption efficiency of incident light at a specific wavelength in the actual application scenario.

[0087] Figure 2 is a schematic diagram of the structure of a second antireflection layer according to one embodiment of this application. Referring to Figure 2, the second antireflection layer 30 includes an edge region 31 and a central region 32 located inside the edge region 31. The thickness of the central region 32 is h1, and the thickness of the edge region 31 is h2.

[0088] For example, h1 and h2 can satisfy the following relationship: 0nm ≤ h1 - h2 ≤ 40nm. For example, the value of h1 - h2 can be 0nm, 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, etc. With this setting, when forming the second antireflection layer 30, due to the limitations or influences of process conditions, there will be a thickness difference between the edge region 31 and the central region 32 of the second antireflection layer 30. Since the second antireflection layer 30 in this embodiment is a new film structure formed on the basis of the first antireflection layer 20, based on the double antireflection layer structure design composed of the second antireflection layer 30 and the first antireflection layer 20, by adjusting the refractive index relationship between the two to satisfy (a) or (b) so that the thickness difference between the edge region 31 and the middle region 32 of the second antireflection layer 30 is within the aforementioned wider range, the colors of the edge region 31 and the middle region 32 can be basically consistent under the illumination of incident light, thereby weakening or even completely masking the blue edge phenomenon, thus improving the color uniformity and aesthetics of the surface of the solar cell 100. Alternatively, by making the antireflection structure composed of the two have a reflectivity change curve with double-valley characteristics, the color of the cell can be adjusted. Compared with the existing antireflection structure, the thickness difference between the edge region 31 and the middle region 32 of the second antireflection layer 30 has a wider range of selection. For example, in order to reduce color differences between different regions, the thickness difference between the edge region and the middle region of the film layer in the existing antireflection structure needs to be less than 10nm. However, the upper limit of the tolerance for the thickness difference between the edge region 31 and the middle region 32 of the second antireflection layer 30 in this embodiment can be set to 40nm. This not only enables the solar cell of this application to have or even surpass the color uniformity effect of the existing cells, but also reduces the process difficulty of manufacturing the second antireflection layer.

[0089] It should be noted that the thicknesses of the first antireflection layer 20 and the second antireflection layer 30 can be measured using an ellipsometer, and / or obtained by acquiring SEM images and labeling them. When the thickness of the central region of the second antireflection layer is the same as that of the edge region, its color-correcting effect and its ability to improve the absorption efficiency of specific wavelengths are better.

[0090] In this embodiment, by matching the refractive indices of the first antireflective layer 20 and the second antireflective layer 30, the blue light reflectivity of the edge region 31 of the second antireflective layer 30 can be reduced by 2% compared to the edge region of the existing single antireflective layer structure. Furthermore, under the dual antireflective layer structure design, the proportion of blue light difference in the reflected light is diluted, resulting in a smaller impact and a more uniform surface color of the solar cell 100. Additionally, improvements to the PVD and CVD tooling can be made to use grooves without jamming points to achieve full-surface coating, ensuring unobstructed front surfaces. Therefore, after coating, the entire surface is covered by the second antireflective layer 30, resulting in a single-color surface on the solar cell 100 without jamming points or blue edges.

[0091] In some embodiments, the thickness of the first antireflection layer 20 is H1, and the thickness of the second antireflection layer 30 is H2, wherein H1 and H2 satisfy the following functional relationship: H1 + H2 2＝ H+c. Where H is the total thickness of the first antireflection layer 20 and the second antireflection layer 30 that give the solar cell 100 a specific color, and c is a constant and is the thickness tolerance (also called the thickness variation range) that gives the solar cell 100 a specific color.

[0092] It should be noted that H is the median (or mean) of the total thickness of the first antireflective layer 20 and the second antireflective layer 30, and different H values ​​correspond to different colors of solar cells 100. H1 is the thickness value corresponding to a certain part of the first antireflective layer 20, and H2 is the thickness value corresponding to a certain part of the second antireflective layer 30, with H1 and H2 representing the same area of ​​the cell. Different ranges of c also correspond to different colors of solar cells 100. For example, when 0 < H2 < 180 nm, c is -40 nm to 40 nm, and H = 140, it is advantageous to make the solar cell 100 appear black, which is beneficial for realizing a black module.

[0093] The functional relationship between H1+H2 and H is derived from Fresnel's law based on the refractive index difference between the first antireflection layer 20 and the second antireflection layer 30. The color change of the solar cell 100 exhibits a periodic variation with thickness. Based on the newly added second antireflection layer 30, the color change period, median total thickness, and thickness range of the solar cell 100 vary with the refractive index difference between the first antireflection layer 20 and the second antireflection layer 30.

[0094] Based on the above functional relationship between H1+H2 and H, the thickness of the first antireflection layer 20 and the second antireflection layer 30 can be quickly adjusted so that the solar cell 100 can display a specific color.

[0095] In some embodiments, 0 < H2 ≤ 300 nm, for example, H2 can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, etc. Optionally, 50 nm ≤ H2 ≤ 80 nm. This setting can prevent the thickness H2 of the second antireflection layer 30 from being too large, which would lead to broadband antireflection failure and changes in the color adjustment mechanism, ensuring that the battery color function can be achieved by adjusting the thickness H1 of the first antireflection layer 20 and the thickness H2 of the second antireflection layer 30 within an appropriate range.

[0096] In some instances, for a specific color solar cell 100, the H value of the solar cell 100 will change as the materials of the second antireflective layer 30 and the first antireflective layer 20 are varied. For example, H can be 20nm, 50nm, 70nm, 95nm, or 150nm.

[0097] Based on the dual antireflection layer structure design consisting of the second antireflection layer 30 and the first antireflection layer 20, the edge region 31 and the middle region 32 of the second antireflection layer 30 can be basically the same color under this thickness condition, so the color uniformity of the solar cell 100 after coating is good.

[0098] The following example illustrates the impact of the material and thickness selection of the first antireflection layer 20 and the second antireflection layer 30 on the color of the solar cell 100.

[0099] Table 1 Relationship between silicon nitride thickness and battery color

[0100] Table 2. Effect of CeO2 thickness on battery color

[0101] Table 3. Matching relationship between silicon nitride film thickness and CeO2 film thickness in black batteries.

[0102] In Tables 1-3, "Battery 1 color" refers to the color of the front of a battery with a silicon nitride film layer but without CeO2, POE, or glass. "Battery 2 color" refers to the color of the front of a battery with both silicon nitride and CeO2 film layers. "Module color" refers to the color of the front of a battery with silicon nitride, CeO2, POE, and glass. When the battery structure and film materials differ, the above relationship between thickness and color will deviate to some extent, and color transitions may occur during thickness changes. The previous example of battery 3 using black as an example is not limited to black; it can also be yellow, red, or other target colors.

[0103] This embodiment of the application, through thickness and material matching between the second antireflection layer 30 and the first antireflection layer 20, can selectively increase the reflectivity or transmittance of certain visible light, balancing the proportions of the three primary colors (red, green, and blue). This ensures that the difference in visible light reflectivity of the solar cell 100 does not exceed 1.5%, thereby forming a black solar cell 100, which is beneficial for forming a black module. This method can also increase the reflectivity of specific colors, thereby forming solar cells 100 of specific colors.

[0104] Secondly, embodiments of this application provide another type of solar cell. The solar cell includes a silicon wafer and an anti-reflection structure disposed on the surface of the silicon wafer. As shown in Figure 3, within the wavelength range of incident light from 380 nm to 1100 nm, the reflectivity variation curve of the solar cell has two troughs, comprising a first trough and a second trough. A peak exists between the first trough and the second trough.

[0105] It should be noted that Figure 3 is a comparison of the reflectivity of the antireflection structure of the solar cell 100 provided according to one embodiment of this application with the reflectivity of existing antireflection structures. In the figure, the curve marked "SiNx+CeO2 cell" represents the reflectivity variation curve of the antireflection structure of the solar cell 100 according to this embodiment, and the curve marked "SiNx cell" represents the reflectivity variation curve of existing antireflection structures. In the specific embodiment corresponding to Figure 3, the existing cell uses a silicon nitride layer as the antireflection structure (i.e., a single antireflection layer structure). For existing single antireflection layer structure cells, in the wavelength range of incident light from 300nm to 1100nm, the reflectivity of the silicon nitride single antireflection layer structure shows a decreasing, increasing, and then increasing trend with increasing wavelength, forming a reflectivity variation curve characterized by a single trough. Although single antireflective layer structures can achieve a specific target color on the front side by adjusting the chromaticity distribution, the thickness difference between the edge and center regions of the solar cell still leads to a significant blue edge problem, manifested as approximately 2% higher blue light reflectance on the reflectance curve (the edge region has approximately 5% reflectance of 400nm blue light, while the center region has approximately 3% reflectance; these wavelength and reflectance data are examples and not absolute values). Furthermore, solar cells experience higher losses in the visible or near-infrared light bands, resulting in substantial efficiency losses. Additionally, in existing solar cells, the difference in silicon nitride antireflective layer thickness between the center and edge regions causes different film colors in these two regions; the edge region has a thicker silicon nitride antireflective layer than the center region, resulting in a bluish tint to the edge region.

[0106] In this embodiment, within the wavelength range of incident light from 380nm to 1100nm, the reflectivity curve of the solar cell exhibits a double trough (i.e., a first trough and a second trough). That is, within the wavelength range of incident light from 380nm to 1100nm, the reflectivity curve of the solar cell shows a decreasing, increasing, decreasing again, and increasing again trend as the wavelength increases. The reflectivity of specific wavelengths of incident light can be reduced (i.e., the reflectivity of the incident light can be made to form a trough in a specific wavelength range) according to actual needs, while maintaining or even increasing the reflectivity of other wavelengths, thereby adjusting the ratio of different wavelengths of incident light that can be visually received, and thus achieving adjustment of the cell's color. The double trough in the reflectivity curve of the solar cell enhances its ability to adjust cell color. Furthermore, it allows adjustment of the ratio of light wavelengths that the cell can receive and utilize. For example, increasing the light absorption efficiency in the near-infrared region of the cell can increase the current and improve the working performance of the solar cell.

[0107] It should be noted that the first and second troughs represent the locations of the lowest reflectance points within the selected wavelength range on the reflectance variation curve of the solar cell. The peaks represent the locations of the highest reflectance points within the selected wavelength range on the reflectance variation curve of the solar cell.

[0108] According to the principle of the three primary colors of red, green and blue, the colors presented by solar cells vary depending on the proportion of different colors of light. This is because the reflectivity of different wavelengths of light can be determined based on the requirements of solar cells in actual application scenarios, such as the reflectivity of the first trough, peak and second trough in the curve and their corresponding reflectivity values. This allows for the adjustment of the cell color and the control of the absorption efficiency of incident light at specific wavelengths.

[0109] For example, the first trough can be located in the wavelength range of 380nm to 500nm; and / or, the second trough can be located in the wavelength range of 800nm ​​to 1100nm. Alternatively, the peak can be located in the wavelength range of 400nm to 800nm. It is understood that different wavelengths correspond to different colors; for example, 600nm to 700nm is red light, 500nm to 570nm is green light, and 400nm to 470nm is blue light. In the case of a blue edge phenomenon in the battery, the reflectivity change curve characterized by double troughs can be set so that the first trough is located in the wavelength range of 380nm to 500nm. At this time, the reflectivity in the blue light band of the reflectivity change curve is lower, which can weaken the blue light intensity of the battery and reduce the relative difference in blue light intensity between the central and edge regions of the battery, thereby reducing the color difference between the central and edge regions of the battery. Furthermore, the peak in the reflectivity variation curve can be located within the wavelength range of 400nm to 800nm, meaning the peak falls within the visible light range. Adjusting the peak position and intensity can control the battery's color and brightness to meet the requirements of different colored batteries in various practical applications. When the characteristics of a peak between 500nm and 700nm and a first trough between 380nm and 500nm are simultaneously satisfied, adjusting the ratio of the three primary colors—blue, red, and green—to 1:1:1 can create a black battery cell, forming a black module to meet the requirements of different colored batteries in various practical applications. Additionally, when the battery exhibits a blue edge phenomenon, setting the peak between 500nm and 700nm can increase the reflectivity of the antireflective structure in red and green light, thereby diluting the blue light ratio and reducing the difference in blue light between the edge and center regions of the battery, potentially even eliminating the blue edge phenomenon. Setting the second trough within the range of 800nm ​​to 1100nm enhances the battery's absorption efficiency for near-infrared incident light, thereby increasing the current and helping the battery maintain higher efficiency. When the first trough, peak, and second trough are within the above range, color adjustment can be achieved better, and battery efficiency can be optimized.

[0110] It should be noted that, since the wavelength range in which the first trough may occur and the wavelength range in which the first peak may occur partially overlap, it should be understood that for the reflectivity change curve of the same battery, the wavelengths of the first trough and the peak will not overlap. However, for the reflectivity change curves of different batteries, the wavelength range in which the first trough may occur and the wavelength range in which the first peak may occur may partially overlap. That is, the wavelength corresponding to the first trough of the reflectivity change curve of one battery is equal to the wavelength corresponding to the peak of the reflectivity change curve of another battery. For example, the wavelength corresponding to the first trough of the reflectivity change curve of one battery is 410 nm, and the wavelength corresponding to the peak of the reflectivity change curve of another battery is 410 nm.

[0111] Optionally, when the solar cell is black, and / or the module formed based on the solar cell is a black module, within the wavelength range of 380nm to 1000nm, the first trough and peak are located in the 380nm to 700nm band, and the second trough is located in the 800nm ​​to 1000nm band. With this configuration, the first trough and peak are located in the visible light region. The relative positions of the peak and the first trough can be adjusted by controlling the thickness, thereby regulating the red, blue, and green reflectivity ratios and thus changing the color of the cell and module. The second trough in the reflectivity variation curve characterized by two troughs is located in the 800nm ​​to 1000nm band, enhancing the light absorption in the near-infrared region of the cell, thereby increasing the current and maintaining higher cell efficiency.

[0112] For example, when the solar cell is black, and / or the module formed based on the solar cell is a black module, the first trough in the reflectance variation curve characterized by double troughs can be set within the wavelength range of 380nm to 500nm. This setting reduces the corresponding blue light reflectance, thus weakening the blue light intensity in the central and edge regions of the cell, reducing the relative difference, and decreasing the color difference between the central and edge regions. Furthermore, in the double-trough reflectance curve, the first peak can be set between 500nm and 700nm. This setting enhances the reflectance corresponding to red and green light (the peak reflectance is approximately 2% to 6%). In the case of existing single antireflection layers, the visible light reflection spectrum is red, blue, and green, with reflectances of approximately 0.5%, 4%, and 0.5%, respectively, with blue light being dominant. The antireflection structure in this application has a reflectance spectrum of red, blue, and green, with reflectances of approximately 3% to 5%, 3% to 5%, and 3% to 5%, respectively, and the reflectance ratio of red, blue, and green is close to 1:1:1. At this point, if the blue light intensity at the edge of the battery increases by 2% compared to the central region, under the existing single antireflective layer of silicon nitride, the blue light intensity increases by more than 50%, resulting in the edge region becoming significantly bluer and brighter than the central region, i.e., a blue edge phenomenon occurs. However, for the antireflective layer structure in this application, even if the blue light reflectivity increases by 2% due to the difference in film thickness between the edge and central regions, the red, blue, and green reflectivity ratio is close to 2:1:1, and the overall blue light reflectivity only increases by 20%. That is, the proportion of the increase in blue light reflectivity relative to the overall increase is much smaller than that of the existing single antireflective layer, which can dilute the blue light ratio, reduce the difference in blue light intensity between the edge and central regions of the battery, and thus eliminate the blue edge.

[0113] In practical applications, the reflectivity corresponding to the first trough can be greater than that corresponding to the second trough. This setting ensures that the reflectivity at the first trough has a certain magnitude to balance the color, allowing the battery to meet practical requirements. Simultaneously, the lower reflectivity at the second trough helps ensure good absorption of near-infrared light, guaranteeing higher battery efficiency.

[0114] Alternatively, the reflectivity corresponding to the first trough can be equal to or less than the reflectivity corresponding to the second trough.

[0115] For example, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to incident light with a wavelength of 380 nm can be greater than the reflectivity corresponding to the peak. This setting allows the reflectivity corresponding to the peak to be less than the reflectivity corresponding to incident light with a wavelength of 380 nm. While achieving the cell's color adjustment purpose by ensuring a higher reflectivity for the incident light at the peak, it also reduces excessive reflection of the incident light at the peak, thus improving the cell's conversion efficiency.

[0116] For example, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to incident light with a wavelength of 380 nm can be greater than the reflectivity corresponding to the first trough and the second trough. The application principle of the beneficial effect in this case can refer to the application principle of the beneficial effect of the reflectivity corresponding to incident light with a wavelength of 380 nm being greater than the reflectivity corresponding to the peak, as described above, and will not be repeated here.

[0117] For example, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to incident light with a wavelength of 1100 nm can be greater than the reflectivity corresponding to the peak. This setting allows the cell efficiency to be maintained at a good level.

[0118] Alternatively, the reflectivity of incident light with a wavelength of 1100 nm can also be less than that of the peak.

[0119] For example, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to incident light with a wavelength of 1100 nm can be greater than the reflectivity corresponding to the first trough and the second trough. The application principle of the beneficial effect in this case can refer to the application principle of the beneficial effect that the reflectivity corresponding to incident light with a wavelength of 1100 nm can be greater than the reflectivity corresponding to the peak, as described above, and will not be repeated here.

[0120] For example, in the reflectance variation curve of a solar cell, the reflectance corresponding to incident light with a wavelength of 1100 nm can be greater than the reflectance corresponding to incident light with a wavelength of 380 nm. Alternatively, the reflectance corresponding to incident light with a wavelength of 1100 nm can also be equal to the reflectance corresponding to incident light with a wavelength of 380 nm.

[0121] For example, in the reflectivity variation curve of a solar cell, the difference between the reflectivity corresponding to the peak and the reflectivity corresponding to the first trough can be greater than or equal to 0.01% and less than 5%. For instance, the difference between the reflectivity corresponding to the peak and the reflectivity corresponding to the first trough can be 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 4.9%, etc. This setting is beneficial for making the cell black and for forming a black module. The reflectivity for incident light of a specific wavelength (e.g., 500nm to 700nm) is greater than the reflectivity for another specific wavelength (e.g., 380nm to 500nm), meaning the reflectivity for different colors of incident light is different. This allows for adjustable ratios of the three primary colors (red, blue, and green), thereby enabling adjustment of the cell color while avoiding excessively large differences that would prevent the cell from becoming black and thus prevent the formation of a black module.

[0122] For example, in the reflectivity variation curve of a solar cell, the difference between the reflectivity corresponding to the peak and the reflectivity corresponding to the second trough can be greater than or equal to 0.01% and less than 5%. For instance, the difference between the reflectivity corresponding to the peak and the reflectivity corresponding to the second trough can be 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 4.9%, etc. This setting can prevent high peak reflectivity from causing excessive reduction in cell efficiency.

[0123] For example, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to the peak can be less than 5%. For instance, the reflectivity corresponding to the peak can be 3.5%, 3.6%, 3.7%, 3.8%, 4%, 4.2%, 4.5%, 4.7%, or 4.9%, etc. This setting prevents the cell from having excessively high reflectivity corresponding to the peak, which would result in high reflectivity of red and green light, hindering the formation of a black cell and facilitating the creation of a black module. When the reflectivity corresponding to the peak is greater than or equal to 5%, the reflection of red and green light is strong, which is unfavorable for forming a black cell and thus a black module.

[0124] For example, in the reflectivity variation curve of a solar cell, the reflectivity corresponding to the second trough can be less than 2.1%. For instance, the reflectivity corresponding to the second trough can be 1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%, etc. This configuration better promotes the absorption of near-infrared light by the cell, effectively improving the cell's conversion efficiency.

[0125] The anti-reflection structure of this application can achieve three functions through the characteristics of double troughs: selecting specific colors, unifying the colors at the edges and center, and achieving near-infrared light absorption gain from 700nm to 1000nm (the characteristic of this gain range is that the wavelength of the enhanced light is slightly lower than the wavelength corresponding to the energy band of crystalline silicon). In order to adjust the color, the purpose of suppressing the efficiency degradation of solar cells can be achieved, thereby improving the working performance of solar cells.

[0126] In practical applications, the solar cell provided by the second aspect of this application can obtain an altered antireflection structure by optimizing the cell film structure. The antireflection structure can be a single-layer antireflection structure, and by adjusting the material, thickness, and manufacturing process of the antireflection structure, the reflectivity variation curve of the solar cell can have double troughs in the wavelength range of incident light from 380nm to 1100nm. Alternatively, the antireflection structure can be a multilayer structure, and by adjusting the material, thickness, refractive index, and reflectivity of different antireflection layers, the reflectivity variation curve of the solar cell can also have double troughs in the wavelength range of incident light from 380nm to 1100nm. Ultimately, this allows for the control of the reflectivity of the solar cell for different wavelengths of incident light, thereby controlling the color of the cell.

[0127] For example, as shown in Figure 1, the antireflection structure may also include a first antireflection layer 20 and a second antireflection layer 30. The first antireflection layer 20 is disposed on the surface of the silicon wafer 10, and the second antireflection layer 30 is disposed on the surface of the first antireflection layer 20 facing away from the silicon wafer 10. With this configuration, the antireflection structure is a two-layer structure. By adjusting the material and thickness of the second antireflection layer 30 (see the first and third aspects), the reflectivity of the solar cell for different wavelengths of incident light can be controlled, thereby controlling the color of the cell and the absorption efficiency for specific wavelengths of incident light, and improving the working performance of the solar cell.

[0128] It should be noted that Figure 3 was obtained under a specific example where the first antireflection layer 20 of the solar cell 100 provided in this application is a silicon nitride layer and the second antireflection layer 30 is a cerium oxide layer. Compared to a single silicon nitride antireflection layer structure, this application embodiment forms a double antireflection layer structure by adding a cerium oxide antireflection layer on the side of the silicon nitride layer facing away from the silicon wafer. Referring to Figure 3, the reflectivity of the double antireflection layer structure can achieve a double-trough characteristic (the first trough is around 480nm, and the second trough is around 930nm). Specifically, the reflectivity at 480nm is 0.75%, at 600nm it is 1.29%, and at 930nm it is 0.37%, with the reflectivity at 480nm and 930nm being lower than that at 600nm. In contrast, existing cells, tested under a single silicon nitride antireflection layer, exhibit a single trough (around 460nm) in their corresponding reflectivity curves.

[0129] Referring to Figure 3, the wavelength range for selective antireflection enhancement between the two troughs is the wavelength required to achieve a specific target color for the solar cell 100. When black is the target color, under the specific test structure corresponding to Figure 3, the reflectivity of red and green light in the 450nm–750nm range can be increased by approximately 2% by adjusting the CeO2 thickness. This allows the solar cell 100 to appear black, resulting in a black module. That is, selectively increasing the reflectivity of a specific color ensures that the difference between the reflectivity curve of the solar cell 100 and the reflectivity curve of a black (or near-black) material in the visible light range is less than 1.5%, thus achieving the target color. Furthermore, the fact that the lowest reflectivity value in the 700nm–1000nm near-infrared region is reduced by more than 1% compared to a single antireflection layer is a characteristic of achieving near-infrared light absorption gain through the two troughs.

[0130] Therefore, by adjusting the thickness of the second antireflection layer 30, the transmittance or reflectance at a specific wavelength (specific color) can be selectively increased. Secondly, the cell surface formed by the first antireflection layer 20 of different thicknesses has different colors. Therefore, by matching the first antireflection layer 20 with the second antireflection layer 30 of a specific thickness, the proportions of the three primary colors of red, green and blue can be adjusted, and a solar cell 100 of a specific color can be formed.

[0131] As for the setting principle and beneficial effects of the different thicknesses of the first antireflective layer 20 and the second antireflective layer 30, please refer to the setting principle and beneficial effects of the different thicknesses of the first antireflective layer 20 and the second antireflective layer 30 in the first aspect above, which will not be repeated here.

[0132] Referring to Figure 2, the second antireflection layer 30 includes an edge region 31 and a central region 32 located inside the edge region 31. The thickness of the central region 32 is h1, and the thickness of the edge region 31 is h2. For example, h1 and h2 can satisfy the following relationship: 0nm ≤ h1 - h2 ≤ 40nm. For instance, the values ​​of h1 - h2 can be 0nm, 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, etc. This configuration allows for a wider range of choices for the thickness difference between the edge region 31 and the central region 32 of the second antireflection layer 30 compared to existing antireflection structures. For example, in order to adjust the color of the battery, the thickness difference between the edge region and the middle region of the film layer in the existing antireflection structure needs to be less than 10nm. However, the upper limit of the tolerance for the thickness difference between the edge region 31 and the middle region 32 of the second antireflection layer 30 in this embodiment can be set to 40nm. This not only enables the solar cell of this application to have or even surpass the color uniformity effect of the existing battery, but also reduces the process difficulty of manufacturing the second antireflection layer.

[0133] In some embodiments, the thickness of the first antireflection layer 20 is H1, and the thickness of the second antireflection layer 30 is H2, wherein H1 and H2 satisfy the following functional relationship: H1 + H2 2＝ H+c. Where H is the total thickness of the first antireflective layer 20 and the second antireflective layer 30 that give the solar cell 100 a specific color, and c is a constant and is the thickness tolerance (also called the thickness variation range) that gives the solar cell 100 a specific color. The specific meanings of H1, H2 and H can be found in the previous text.

[0134] The functional relationship between H1+H2 and H is derived from Fresnel's law based on the refractive index difference between the first antireflective layer 20 and the second antireflective layer 30. The color change of the solar cell 100 exhibits a periodic variation with thickness. Based on the newly added second antireflective layer 30, the color change period, median total thickness, and thickness range of the solar cell 100 change with the refractive index difference between the two antireflective layers. Based on the functional relationship between H1+H2 and H, the thicknesses of the first antireflective layer 20 and the second antireflective layer 30 can be quickly adjusted to enable the solar cell 100 to display a specific color.

[0135] For example, when 0 < H2 < 180 nm, c is -40 nm to 40 nm and H = 140, it is advantageous for the solar cell 100 to appear black, which is beneficial for forming a black module.

[0136] In some embodiments, 0 < H2 ≤ 300 nm, for example, H2 can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, etc. Optionally, 50 nm ≤ H2 ≤ 80 nm. This setting can prevent the thickness H2 of the second antireflection layer 30 from being too large, which would lead to broadband antireflection failure and changes in the color adjustment mechanism, ensuring that the battery color function can be achieved by adjusting the thickness H1 of the first antireflection layer 20 and the thickness H2 of the second antireflection layer 30 within an appropriate range.

[0137] This embodiment of the application, through thickness and material matching between the second antireflection layer 30 and the first antireflection layer 20, can selectively increase the reflectivity or transmittance of certain visible light, balancing the proportions of the three primary colors (red, green, and blue). This ensures that the difference in visible light reflectivity of the solar cell 100 does not exceed 1.5%, thereby forming a black solar cell 100, which is beneficial for creating a black module. This method can also increase the reflectivity of specific colors, thereby forming solar cells 100 of specific colors.

[0138] Thirdly, this application also provides another type of solar cell, the solar cell 100 including a silicon wafer 10 and an anti-reflection structure disposed on the surface of the silicon wafer 10. The anti-reflection structure includes a first anti-reflection layer 20 disposed on the surface of the silicon wafer 10 and a second anti-reflection layer 30 disposed on the surface of the first anti-reflection layer 20. The second anti-reflection layer 30 includes an edge region 31 and a central region 32 located inside the edge region 31. The thickness of the central region 32 is h1, and the thickness of the edge region 31 is h2, wherein h1 and h2 satisfy the following relationship: 0nm ≤ h1 - h2 ≤ 40nm.

[0139] For example, the thickness of the first antireflection layer 20 is H1, and the thickness of the second antireflection layer 30 is H2. H1 and H2 satisfy the following functional relationship: H1 + H2 2＝ H+c. Where H is the total thickness of the first antireflection layer 20 and the second antireflection layer 30 that give the solar cell a specific color, and c is the thickness tolerance that gives the solar cell a specific color.

[0140] For example, 0 < H2 ≤ 300nm. For instance, H2 can be 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 100nm, 150nm, 200nm, 250nm, 300nm, etc. Optionally, 50nm ≤ H2 ≤ 80nm.

[0141] For example, the second antireflection layer 30 is cerium oxide, H = 140 nm, and -40 nm < c < 40 nm, so that the solar cell appears black, which is beneficial for realizing black modules.

[0142] For example, in the wavelength range of incident light from 380 nm to 1100 nm, the reflectivity variation curve of the solar cell has two troughs, which include a first trough and a second trough.

[0143] For example, there is a peak between the first trough and the second trough. The first trough is located in the wavelength range of 380 nm to 500 nm; and / or, the second trough is located in the wavelength range of 800 nm to 1100 nm. Alternatively, the peak is located in the wavelength range of 400 nm to 800 nm.

[0144] For example, the refractive index of the first antireflection layer is n1, and the refractive index of the second antireflection layer is n2. n1 and n2 satisfy one of the following relationships: (a) -0.4 ≤ n2 - n1 ≤ -0.05; (b) 0.1 ≤ n2 - n1 ≤ 0.4.

[0145] For example, 1.6 ≤ n2 ≤ 2.6.

[0146] The beneficial effects of the third aspect and its various implementations in this application can be found in the analysis of the beneficial effects of the first or second aspect and their corresponding implementations, and will not be repeated here.

[0147] Fourthly, embodiments of this application provide a photovoltaic module. The photovoltaic module of this application includes a structure comprising stacked photovoltaic tempered glass, encapsulating film, photovoltaic cell strings, and a photovoltaic backsheet or photovoltaic backsheet glass, for photovoltaic power generation. The photovoltaic cell string includes at least one solar cell 100.

[0148] Specifically, the number of solar cells 100 in a photovoltaic cell string can be one or more. When the number of solar cells 100 in a photovoltaic cell string is more than one, the multiple solar cells 100 can be connected in series, in parallel, or in series and parallel combination to form a photovoltaic cell string.

[0149] The encapsulant film is placed between the photovoltaic tempered glass and the solar cells 100 of the photovoltaic cell string. It is usually an EVA film or a POE film. The refractive index of the encapsulant film is generally in the range of 1.4 to 1.7. Therefore, changing the type of encapsulant film or increasing the number of layers of encapsulant film usually does not affect the optical performance of the photovoltaic module.

[0150] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0151] The embodiments of this application have been described above. However, these embodiments are merely for clarity and are not intended to limit the scope of this application. The scope of this application is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this application, and all such substitutions and modifications should fall within the scope of this application.

Claims

1. A solar cell, comprising: A silicon wafer, and an anti-reflection structure disposed on the surface of the silicon wafer; the anti-reflection structure includes a first anti-reflection layer disposed on the surface of the silicon wafer, and a second anti-reflection layer disposed on the surface of the first anti-reflection layer; Wherein, the refractive index of the first antireflection layer is n1, the refractive index of the second antireflection layer is n2, and n1 and n2 satisfy one of the following relationships: (a): -0.4≤n2-n1≤-0.05; (b): 0.1≤n2-n1≤0.

4.

2. The solar cell of claim 1, wherein, 1.6≤n2≤2.6。 3. The solar cell according to claim 1, wherein, The material of at least one of the first antireflection layer and the second antireflection layer is one, two or three compounds, and the compounds are selected from rare earth element compounds and / or transition metal compounds.

4. The solar cell of claim 3, wherein, The rare earth elements in the rare earth element compounds include one, two, or three of the following: Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. And / or, the transition metal element in the transition metal compound includes one, two or three of Ti, V, Cu, Zn, Mo, W, Co, Ni, and Re.

5. A solar cell comprising: The silicon wafer and the anti-reflection structure disposed on the surface of the silicon wafer; the reflectivity variation curve of the solar cell has two troughs in the wavelength range of incident light from 380 nm to 1100 nm, the two troughs including a first trough and a second trough.

6. The solar cell according to claim 5, wherein, There is a peak between the first trough and the second trough; Wherein, the first trough is located in the wavelength range of 380nm to 500nm; and / or, the second trough is located in the wavelength range of 800nm ​​to 1100nm; and / or, the peak is located in the wavelength range of 400nm to 800nm.

7. The solar cell according to claim 6, wherein, The reflectivity corresponding to the wave crest is less than 5%, and / or the reflectivity corresponding to the second wave trough is less than 2.1%.

8. The solar cell according to claim 6, wherein, The difference between the reflectivity corresponding to the wave crest and the reflectivity corresponding to the first wave trough is greater than or equal to 0.01% and less than or equal to 4.9%. And / or, the difference between the reflectivity corresponding to the wave crest and the reflectivity corresponding to the second wave trough is greater than or equal to 0.01% and less than 5%; And / or, the reflectivity corresponding to the first trough is greater than the reflectivity corresponding to the second trough.

9. The solar cell of claim 6, wherein, In the reflectivity variation curve of the solar cell, the reflectivity corresponding to incident light with a wavelength of 380 nm is greater than the reflectivity corresponding to the peak. And / or, in the reflectivity variation curve of the solar cell, the reflectivity corresponding to incident light with a wavelength of 1100 nm is greater than the reflectivity corresponding to the peak.

10. The solar cell of claim 5, wherein, In the reflectivity variation curve of the solar cell, the reflectivity corresponding to incident light with a wavelength of 1100 nm is greater than that corresponding to incident light with a wavelength of 380 nm. And / or, in the reflectivity variation curve of the solar cell, the reflectivity corresponding to incident light with a wavelength of 380 nm is greater than the reflectivity corresponding to the first trough and the reflectivity corresponding to the second trough; And / or, in the reflectivity variation curve of the solar cell, the reflectivity corresponding to incident light with a wavelength of 1100 nm is greater than the reflectivity corresponding to the first trough and the reflectivity corresponding to the second trough.

11. The solar cell according to claim 5, wherein, Within the wavelength range of incident light from 380nm to 1100nm, the reflectivity curve of the solar cell shows a decreasing, increasing, decreasing again, and increasing again trend as the wavelength increases.

12. The solar cell according to claim 5, wherein, The anti-reflection structure includes a first anti-reflection layer and a second anti-reflection layer, wherein the first anti-reflection layer is disposed on the surface of the silicon wafer, and the second anti-reflection layer is disposed on the surface of the first anti-reflection layer away from the silicon wafer.

13. The solar cell of claim 1 or claim 12, wherein, The thickness of the first antireflection layer is H1, and the thickness of the second antireflection layer is H2. H1 and H2 satisfy the following functional relationship: H1 + H2 = H + c; Wherein, H is the total thickness of the first antireflection layer and the second antireflection layer that gives the solar cell a specific color, and c is the thickness tolerance that gives the solar cell the specific color.

14. The solar cell according to claim 13, wherein, 0 < H2 < 180 nm; H = 140 nm, and -40 nm < c < 40 nm.

15. The solar cell according to claim 1 or claim 12, wherein, The second antireflection layer includes an edge region and a central region located inside the edge region. The thickness of the central region is h1, and the thickness of the edge region is h2, wherein h1 and h2 satisfy the following relationship: 0nm≤h1-h2≤40nm.

16. The solar cell according to claim 1 or claim 12, wherein, The silicon wafer includes a body and a textured structure formed on the surface of the body, wherein the anti-reflection structure is disposed on the surface of the textured structure.

17. A photovoltaic module, comprising: The solar cell, the encapsulating film, and the glass according to any one of claims 1 to 16; wherein the encapsulating film is disposed between the glass and the solar cell.

18. The photovoltaic module according to claim 17, wherein, Within the wavelength range of incident light from 380 nm to 1100 nm, the reflectivity variation curve of the solar cell includes a first trough and a second trough, as well as a peak located between the first trough and the second trough; the reflectivity corresponding to the peak is less than 5%, and the reflectivity corresponding to the second trough is less than 2.1%, so that the solar cell appears black when seen through the film and the glass.

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