Solar cells, tandem cells and photovoltaic modules

Abstract

This application relates to the field of solar cells, and discloses a solar cell, a tandem solar cell, and a photovoltaic module. The solar cell includes: a substrate having a first surface and a second surface disposed opposite each other along its thickness direction; the first surface having alternately arranged first and second doped regions; an isolation region being provided between the first and second doped regions, the isolation region including a plurality of isolation units arranged along the extension direction of the isolation region; at least one isolation unit including: a first isolation region and a second isolation region connected to the first isolation region; along the extension direction of the isolation region, the two sides of the isolation unit are respectively adjacent to the first and second doped regions; through the above method, this application can improve passivation performance, photoelectric conversion efficiency, and reliability while ensuring electrical isolation effect.

Description

Technical Field

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

[0002] In existing back-contact solar cell fabrication technologies, to prevent direct conduction of charge carriers between the N-type and P-type doped regions, which would hinder effective carrier collection, an isolation region is required at the boundary between the two regions. The design of this isolation region directly impacts cell performance, production feasibility, and reliability. Current technologies typically employ a single isolation region structure, which has the following drawbacks: 1. During the fabrication of back contact batteries, the isolation area is prone to microscopic leakage channels due to local damage (such as uneven laser etching, wet corrosion defects, or impurity contamination). Since traditional isolation areas are mostly continuous single-morphology structures, once a local failure occurs in a certain place, the leakage current of the entire isolation area will increase sharply, resulting in the scrapping of the entire battery and severely restricting the mass production yield of back contact batteries.

[0003] 2. Limited photoelectric conversion efficiency: The isolation region of a single structure cannot meet the passivation requirements of different regions, the carrier recombination rate is high, and the single reflection characteristics can easily lead to light escape.

[0004] 3. High difficulty in thinning: If a highly textured surface is used, the amount of material removed during processing is large, which can easily cause the thickness loss of the battery cell to exceed the standard, hindering the production of thinner cells.

[0005] 4. Insufficient reliability: The isolation area of ​​a single structure is prone to stress concentration. During the preparation, packaging and use, the stress concentration area is prone to cracks, which reduces the battery life.

[0006] Therefore, how to improve the passivation performance of the isolation zone and the photoelectric conversion efficiency of solar cells while ensuring battery safety has become an urgent problem to be solved in the field of solar cell technology. Summary of the Invention

[0007] This application provides a solar cell, a tandem cell, and a photovoltaic module that can improve passivation performance, photoelectric conversion efficiency, and reliability while ensuring electrical isolation.

[0008] To solve the above-mentioned technical problems, one technical solution adopted in this application is: to provide a solar cell, comprising: A substrate having a first surface and a second surface disposed opposite to each other along the thickness direction, wherein the first surface is provided with alternating first doped regions and second doped regions; An isolation region is provided between the first doped region and the second doped region, and the isolation region includes a plurality of isolation units arranged along the extension direction of the isolation region; At least one of the isolation units includes: a first isolation region and a second isolation region connected to the first isolation region; along the extending direction of the isolation region, the two sides of the isolation unit are respectively adjacent to the first doped region and the second doped region.

[0009] According to one embodiment of this application, in a plane perpendicular to the thickness direction of the substrate, the first isolation region is at least partially circumferentially disposed around the outside of the second isolation region.

[0010] According to one embodiment of this application, the first isolation region and the second isolation region are arranged sequentially in a plane perpendicular to the thickness direction of the substrate.

[0011] According to one embodiment of this application, the first isolation region is discretely distributed around the second isolation region in a plane perpendicular to the thickness direction of the substrate.

[0012] According to one embodiment of this application, the solar cell is a back-contact solar cell; The first doped region and the second doped region have opposite doping types.

[0013] According to one embodiment of this application, along the thickness direction, with the surface of the second doped region away from the substrate as the reference plane, the maximum etching depth of the first isolation region in the thickness direction is H1, and the minimum etching depth of the second isolation region in the thickness direction is H2, and H1>H2.

[0014] According to one embodiment of this application, the maximum etching depth H1 of the first isolation region in the thickness direction satisfies: 1.0 μm ≤ H1 ≤ 3.0 μm; and the minimum etching depth H2 of the second isolation region in the thickness direction satisfies: 0.5 μm ≤ H2 ≤ 2.0 μm.

[0015] According to one embodiment of this application, the reflectivity of the first isolation zone is R1, and the reflectivity of the second isolation zone is R2, where R1 < R2.

[0016] According to one embodiment of this application, the surface of the first isolation area is a pyramidal velvet structure, and the surface of the second isolation area is a polished surface, or a composite structure surface composed of a polished surface and a pyramidal velvet-like surface.

[0017] According to one embodiment of this application, when the surface of the second isolation region is a composite surface composed of a polished surface and a pyramid-like micro-textured surface, the pyramid-like micro-textured surface density of the second isolation region is less than the pyramid-like textured surface density of the first isolation region, and the surface roughness of the second isolation region is less than the surface roughness of the first isolation region.

[0018] According to one embodiment of this application, the width of the isolation zone is 20–500 μm along the extending direction perpendicular to the isolation zone; The ratio of the vertical projected area of ​​the first isolation zone to that of the second isolation zone on the first surface is 1:10–20:1.

[0019] According to one embodiment of this application, in the thickness direction, from the side away from the substrate to the side closer to the substrate, a first doped region is sequentially stacked with a first doped layer and a first interface passivation layer, and a second doped region is sequentially stacked with a second doped layer and a second interface passivation layer. The surfaces of the first doped layer, the second doped layer, and the isolation region are provided with passivation and antireflection layers.

[0020] To solve the above-mentioned technical problems, another technical solution adopted in this application is: to provide a stacked battery, comprising: Top cell, which can be a perovskite cell, cadmium telluride solar cell, copper indium gallium selenide solar cell, or gallium arsenide solar cell; Intermediate connecting layer; and The bottom battery is the aforementioned solar cell; The top battery, the intermediate connecting layer, and the bottom battery are stacked and connected.

[0021] To solve the above-mentioned technical problems, another technical solution adopted in this application is to provide a photovoltaic module, including the solar cell or the tandem cell.

[0022] The beneficial effects of this application are as follows: By designing the isolation region as multiple arranged isolation units, and at least one isolation unit simultaneously containing a first isolation region and a second isolation region, this application significantly reduces the impact of local defects on the isolation region. This isolation unit-based design can greatly reduce the loss of cell yield caused by local failure of the isolation region. In addition, the first isolation region is located on the periphery of the second isolation region. The first isolation region is used to isolate the first doped region and the second doped region and absorb more light. The second isolation region is used to reduce the etching weight of the cell and improve the passivation performance. The two isolation regions together improve the reliability of the solar cell. Furthermore, the embedded distribution of the second isolation region disperses the stress in the isolation region, avoids crack defects caused by stress concentration, and extends the service life of the cell. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a solar cell according to an embodiment of this application.

[0024] Figure 2 This is a schematic diagram of the structure of a solar cell according to another embodiment of this application.

[0025] Figure 3 This is a partial structural schematic diagram of a solar cell according to an embodiment of this application.

[0026] Figure 4 This is a schematic diagram of the isolation unit in an embodiment of this application.

[0027] Figure 5 This is a schematic diagram of the structure of the battery string in the photovoltaic module according to an embodiment of this application.

[0028] Figure 6 This is a schematic diagram of the structure of a photovoltaic module according to an embodiment of this application.

[0029] Figure 7 This is a topographical diagram of a solar cell according to an embodiment of this application. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0031] The terms "first," "second," and "third" in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0032] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] A solar cell is a semiconductor device that converts the light energy of sunlight into electrical energy. Specifically, when a solar cell is in operation, sunlight shines on the semiconductor PN junction of the solar cell, generating photogenerated carriers and forming new electron-hole pairs. Under the influence of the built-in electric field of the PN junction, photogenerated holes flow to the P-region, and photogenerated electrons flow to the N-region, thus forming a current when an external circuit is connected. A solar cell with both the positive and negative electrodes located on the back of the cell is called a back-contact solar cell.

[0034] In solar cells, an isolation region is often placed between the P-region and the N-region to effectively prevent short circuits. Most existing isolation regions in solar cells have a single textured or planar structure. If a localized failure occurs in any part of the isolation region, the leakage current of the entire isolation region will increase sharply, rendering the entire cell unusable and severely limiting the mass production yield of back-contact solar cells. Furthermore, a single isolation region structure cannot simultaneously meet the optical and passivation requirements of the isolation region, nor can it effectively distribute the stress on the solar cell, easily leading to cracks and reducing product reliability.

[0035] To address the aforementioned problems, this application provides a solar cell, such as... Figure 1 and Figure 2 As shown, the solar cell 100 includes a substrate 10, which has a first surface 10a and a second surface 10b disposed opposite to each other along the thickness direction S1. In one embodiment, the first surface 10a is a backlight surface and the second surface 10b is a light-receiving surface.

[0036] The first surface 10a has alternating first doped regions 11 and second doped regions 12, with an isolation region 13 between the first doped regions 11 and the second doped regions 12. In one embodiment, the solar cell 100 is a back-contact solar cell; the doping types of the first doped regions 11 and the second doped regions 12 are opposite. In another embodiment, the substrate 10 is an N-type semiconductor (such as N-type single-crystal silicon), the first doped region 11 is a P-type conductive region (such as a P+ region), and the second doped region 12 is an N-type conductive region (such as an N+ region).

[0037] like Figure 3As shown in the figure, in the present application, the lateral setting of the substrate 10 in the horizontal direction is denoted as the first direction S2, for example, the width direction of the substrate 10, and the longitudinal setting perpendicular to the first direction S2 in the horizontal direction is denoted as the second direction S3, for example, the length direction of the substrate 10. Both the first direction S2 and the second direction S3 are perpendicular to the thickness direction S1.

[0038] As Figure 3 shown, the isolation region 13 includes a plurality of isolation units arranged along the extension direction of the isolation region 13 (i.e., the second direction S3). At least one isolation unit includes a first isolation region 131 and a second isolation region 132 connected to the first isolation region 131. Along the extension direction of the isolation region 13 (i.e., the second direction S3), both sides of the isolation unit are adjacent to the first doping region 11 and the second doping region 12 respectively. <0000​​​​​​​​​​​​​​​​​​Exemplarily, the first isolation region 131 has a "partially surrounding" structure with respect to the second isolation region 132. For example, the first isolation region 131 has a "U" - shaped structure (as shown in (c) of Figure 4 and (d) of 4), a "C" - shaped structure or an "L" - shaped structure.

[0044] Exemplarily, the first isolation region 131 has a "fully surrounding" structure with respect to the second isolation region 132. "Fully surrounding" can be understood as that the first isolation region 131 surrounds the peripheral side of the second isolation region 132. The position of the second isolation region 132 in the isolation unit is not specifically limited, that is, the distance between the peripheral side of the second isolation region 132 and the first isolation region 131 can be equal or unequal. For example, the isolation unit has a "hui" - shaped structure (as shown in (f) of Figure 4 and (g) of 4). In this embodiment, the first isolation region 131 surrounds the peripheral side of the second isolation region 132, forming a kind of mosaic distribution. Along the extension direction of the isolation region 13, both sides of the first isolation region 131 are adjacent to the first doping region 11 and the second doping region 12 respectively. The first isolation region 131 is used to isolate the first doping region 11 and the second doping region 12 and absorb more light. The second isolation region 132 is used to reduce the etching weight of the cell and improve the passivation performance. The two isolation regions together improve the reliability of the solar cell. In addition, the mosaic distribution of the second isolation region 132 disperses the stress of the isolation region, avoids crack defects caused by stress concentration, and prolongs the service life of the battery.

[0045] In some embodiments, as shown in Figure 1 , along the thickness direction S1, the present application measures the dimensions with the surface of the second doping region 12 away from the substrate 100 as the reference plane, that is, the surface of the doping region closest to the substrate 100. The maximum etching depth of the first isolation region 131 in the thickness direction S1 is H1, and the minimum etching depth of the second isolation region 132 in the thickness direction S1 is H2, and H1 > H2 is satisfied.

[0046] As an embodiment, the maximum etching depth H1 of the first isolation region 131 in the thickness direction S1 satisfies: 1.0μm ≤ H1 ≤ 3.0μm; the minimum etching depth H2 of the second isolation region 132 in the thickness direction S1 satisfies: 0.5μm ≤ H2 ≤ 2.0μm.

[0047] By reducing the height of H2 relative to H1, the present application retains more silicon material thickness in the second isolation region 132 on the premise of ensuring good electrical isolation of the first isolation region 131, reduces the etching weight of the cell during the film - opening process, and adapts to the future trend of thinner wafer production.

[0048] In the same solar cell 100, the structures of each isolation unit can be exactly the same, or they can differ to some extent depending on the actual process requirements. For example, one or more of the following parameters of different isolation units may not be exactly the same: etching depth, surface roughness, reflectivity, or planar projected area ratio.

[0049] In some embodiments, the surface of the first isolation region 131 is a pyramidal textured structure with low reflectivity (preferably 8%–15%, the reflectivity being a test value of a certain wavelength before coating), which can absorb more ambient light and reflect the light to the adjacent first doped region 11 or second doped region 12, thereby generating more electron-hole pairs using the photovoltaic effect, thus increasing the battery short-circuit current.

[0050] In some embodiments, the surface of the second isolation region 132 is a polished surface, or a composite structure surface composed of a polished surface and a pyramid-like micro-textured surface. Unlike the fully textured structure of traditional isolation regions, this design increases the surface smoothness of the isolation region 13, thereby significantly improving the passivation performance of the isolation region 13, effectively reducing the number of surface defects in the isolation region 13, and improving the working performance of the solar cell 100.

[0051] It should be noted that if the entire isolation zone 13 is a polished structure, different isolation unit structures can also be obtained through this method. In this case, both the first isolation zone 131 and the second isolation zone 132 are polished surface structures.

[0052] As one implementation method, such as Figure 1 As shown, the surface of the second isolation region 132 can be curved after etching. As another implementation, such as... Figure 2 As shown, the surface of the second isolation region 132 can be nearly planar after etching.

[0053] In one implementation, the height of the pyramid in the first isolation zone 131 is 0.3–1.5 μm, and the size of the base is 0.5–1.5 μm; the height of the pyramid-like structure in the second isolation zone 132 is 0.05–0.6 μm, and the size of the base is 0.05–0.8 μm.

[0054] In some embodiments, the pyramid-like microtextured surface density of the second isolation region 132 is less than that of the pyramid-like microtextured surface density of the first isolation region 131, and the surface roughness of the second isolation region 132 is less than that of the first isolation region 131. This is beneficial for subsequent deposition of a high-quality passivation film, significantly improving the passivation performance of the isolation region 13 and reducing the number of surface defect states.

[0055] In some embodiments, the reflectivity R2 of the second isolation region 132 is greater than the reflectivity R1 of the first isolation region 131. As an implementation, the reflectivity R1 of the first isolation region 131 is 8% - 15%, and the reflectivity R2 of the second isolation region 132 is 20% - 45%. Since the first isolation region 131 is adjacent to the first doping region 11 and the second doping region 12, the first isolation region 131 with a low reflectivity absorbs more light and then reflects it to the adjacent first doping region 11 and second doping region 12, generating more electron-hole pairs by the photovoltaic effect, thereby increasing the current of the solar cell 100 and further obtaining a solar cell 100 with a high photoelectric conversion efficiency.

[0056] In some embodiments, along the direction perpendicular to the extension direction of the isolation region 13 (i.e., the second direction S3), the width of the isolation region 13 is 20 - 500 μm.

[0057] In some embodiments, the ratio of the perpendicular projection area of the first isolation region 131 to the second isolation region 132 on the first surface 10a is 1:10 - 20:1.

[0058] The distributions of the first isolation region 131 and the second isolation region 132 have a certain ratio within the isolation region 13. If the area ratio of the first isolation region 131 is too small, the isolation effect will be poor and the leakage risk will increase significantly. If the area ratio of the second isolation region 132 is too small, the significance of improving the passivation performance of the isolation region 13 is limited.

[0059] In this application, by changing the size, energy distribution, and overlap rate of the light spot during the laser etching process, the ratio of the perpendicular projection area, width, and etching depth of the first isolation region 131 and the second isolation region 132 on the substrate 10 are adjusted.

[0060] In some embodiments, the energy distribution of the light spot can be adjusted. For example, it can be adjusted to a "return" - shaped light spot with high energy in the outer periphery and low energy in the middle, or the outer and middle energies can be adjusted to change gradually. The etching patterns are as shown in Figure 4 (f) of Figure 4 and (g) of Figure 4 shown. On this basis, by adjusting the width of the light spot along the width direction of the isolation region 13, the widths of the first isolation region 131 and the second isolation region 132 can be changed, and thus a combination of different topography depths along the width direction of the isolation region 13 can be obtained; Figure 4 It can be understood that the light spot can also be adjusted to a "mesh" - shaped one, that is, the first isolation region 131 is distributed on the front and back sides or left and right sides of the second isolation region 132. The etching patterns are as shown in Figure 4 (a) of Figure 4As shown in (d) thereof, the specific adjustment scheme is similar to the above; it can also be adjusted to a "cross" shape, and the etching pattern is as shown in Figure 4 of (e).

[0061] In some other embodiments, different combinations of isolation regions with different morphologies and depths can also be obtained by setting the light spots to overlap or partially overlap. Taking the "square frame" shape as an example, the edge portions of the two light spots in the laser walking direction can be adjusted to overlap, so as to obtain a third isolation region (not shown in the figure) with a depth different from that of the first isolation region 131 and the second isolation region 132, and the depth of the third isolation region is deeper. Those skilled in the art can adjust it according to their needs, and will not be elaborated one by one.

[0062] By optimizing the height, reflectivity and area ratio relationship of the first isolation region 131 and the second isolation region 132, the present application realizes the effective utilization of light and the efficient conversion of energy, and significantly improves the photoelectric conversion efficiency of the solar cell 100.

[0063] As shown in Figure 1 and Figure 2 In the thickness direction S1, from the side far away from the substrate 10 to the side close to the substrate 10, a first doping layer 111 and a first interface passivation layer 112 are sequentially stacked in the first doping region 11, and a second doping layer 121 and a second interface passivation layer 122 are sequentially stacked in the second doping region 12; a passivation and antireflection layer 130 is provided on the surfaces of the first doping layer 111, the second doping layer 121 and the isolation region 13.

[0064] As an embodiment, the first doping layer 111 and the second doping layer 121 can be doped polysilicon layers, and the thickness is generally 50-500 nm. The thicknesses of the first doping layer 111 and the second doping layer 121 are the same or different.

[0065] As an embodiment, the passivation and antireflection layer 130 is composed of an oxide layer and a nitride layer, the thickness of the oxide layer is 2-5 nm, and the thickness of the nitride layer is 50-120 nm. <关于专利文本的翻译,有以下几点需要注意:1. 专利文本通常使用专业术语和特定的语言结构,因此翻译时需要准确理解原文的含义,并使用相应的专业术语进行翻译。 2. 对于一些特定的技术术语和缩写,需要根据上下文进行准确的翻译,以确保译文的准确性和专业性。 3. 专利文本的语言通常较为正式和严谨,因此翻译时需要注意语言的规范性和逻辑性,避免出现错别字、语病等问题。 4. 在翻译过程中,需要注意保留原文的格式和排版,以确保译文的可读性和专业性。 5. 对于一些不确定的术语或翻译,可以参考相关的专利文献或专业词典,以获取更准确的翻译。 6. 在翻译完成后,需要进行仔细的校对和审核,以确保译文的准确性和专业性。 7. 专利文本的翻译需要具备一定的专业知识和语言能力,因此建议由专业的翻译人员或相关领域的专家进行翻译。 8. 在翻译过程中,需要注意保护原文的知识产权,不得擅自抄袭或篡改原文内容。 9. 专利文本的翻译需要遵循相关的法律法规和翻译标准,以确保译文的合法性和规范性。 10. 在翻译完成后,需要将译文提交给相关的部门或机构进行审核和备案,以确保译文的有效性和可使用性。

[0066] As an embodiment, the thicknesses of the first interface passivation layer 112 and the second interface passivation layer 122 are 1-3 nm, and the material can be silicon oxide, etc., which is used to reduce the interface state density. The first interface passivation layer 112 and the second interface passivation layer 122 of the present application can not only reduce the dangling bonds and defect states on the silicon surface and improve the passivation effect, but also allow majority carriers to pass through and effectively block minority carriers, and have the dual functions of "passivation + selective tunneling".

[0067] When the solar cell 100 is operating normally, the first doped region 11 and the second doped region 12 provide photogenerated holes. The isolation region 13 is located between the first doped region 11 and the second doped region 12 to separate conductive regions of different polarities. The first isolation region 131 has a deeper etching depth and plays a major role in electrical isolation. Moreover, the first isolation region 131 has low reflectivity, which allows it to absorb more light and excite the doped regions adjacent to it to generate electron-hole pairs, thereby increasing the cell current. The second isolation region 132 has a lower etching depth than the first isolation region 131. Under the premise that the first isolation region 131 effectively isolates the first doped region 11 and the second doped region 12, reducing the etching depth of the second isolation region 132 can increase the thickness of the substrate 10 corresponding to the isolation region 13. This is beneficial for using a thinner substrate 10 based on the original process, thereby reducing production costs. In addition, reducing the height difference between the isolation region 13 and the doped regions helps to disperse the stress on the cell, reduce the cell breakage rate, and thus improve the reliability of the product.

[0068] One embodiment of this application provides a stacked battery, which includes a top battery, an intermediate connecting layer and a bottom battery, wherein the intermediate connecting layer is connected between the top battery and the bottom battery.

[0069] The top cell is one of a perovskite cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell, and the bottom cell is the aforementioned solar cell 100.

[0070] In some implementations, the interlayer can be a transparent material with a high refractive index. To reduce light reflection and absorption at the interlayer interface and achieve good conductivity to minimize the impact of series resistance on device performance, the interlayer typically needs to have high light transmittance. For example, the interlayer can be a transparent conductive metal oxide thin film (ITO).

[0071] One embodiment of this application provides a photovoltaic module 200. Please refer to [link / reference]. Figure 5 and Figure 6 As shown, it includes a battery string 201, an encapsulating film 202, and a cover plate 203. Please refer to [the provided text]. Figure 5 As shown, the battery string 201 is formed by connecting multiple solar cells 100 as described above, or the battery string 201 is formed by connecting multiple stacked cells as described above; the encapsulating film 202 is used to cover the surface of the battery string 201; the cover plate 203 is used to cover the surface of the encapsulating film 202 away from the surface of the battery string 201.

[0072] In some embodiments, multiple solar cells 100 can be electrically connected to each other by solder strips 20, which are connected to each pair of adjacent solar cells 100. The solder strips 20 are connected to the front surface of the first solar cell 100 and the back surface of the second solar cell 100, respectively.

[0073] In some embodiments, the solar cells 100 may be spaced apart, and during string bonding, the solder strip 20 extends from the front surface of the first solar cell 100 to the gap, passes through the gap, and extends to the back surface of the second solar cell 100.

[0074] In some embodiments, no gap is provided between the solar cells 100, that is, two adjacent solar cells 100 overlap each other.

[0075] In some embodiments, the encapsulating film 202 includes a first encapsulating film and a second encapsulating film. The first encapsulating film covers one of the front or back sides of the solar cell 100, and the second encapsulating film covers the other of the front or back sides of the solar cell 100. Specifically, at least one of the first or second encapsulating film can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film.

[0076] Example 1 The method for preparing the solar cell in Example 1 includes the following steps: Step 1-1: Provide a clean semiconductor substrate. The semiconductor substrate is an N-type single crystal silicon wafer. Polish the first and second surfaces of the semiconductor substrate using an alkaline solution. The polishing solution used for polishing is a mixed solution of potassium hydroxide with a mass fraction of 1.5% and polishing additive with a mass fraction of 0.5%. Step 1-2: Sequentially deposit a first interface passivation layer, a first doped layer, and a first oxide layer on the first surface of the semiconductor substrate; the first interface passivation layer, the first doped layer, and the first oxide layer at the predetermined first doping region position constitute the first doping region, wherein the first interface passivation layer is an intrinsic amorphous silicon layer or a silicon oxide layer, preferably with a thickness of 1.5 nm, and the first doped layer is a P-type doped polycrystalline silicon layer (Poly-Si) with a thickness of 300 nm; Steps 1-3: Remove the first interface passivation layer, first doped layer and first oxide layer corresponding to the second doped region and isolation region using laser etching and wet etching. The laser power is 75W, the wet etching solution is a 3.0% potassium hydroxide or sodium hydroxide solution, the etching temperature is 70℃, and the etching time is 150s. Steps 1-4: Deposit a second interface passivation layer, a second doping layer, and a second oxide layer on the first surface of the semiconductor substrate in sequence; the second interface passivation layer, the second doping layer, and the second oxide layer at the preset position of the second doping region constitute the second doping region. Among them, the second interface passivation layer is an intrinsic amorphous silicon layer or a silicon oxide layer, and its thickness is preferably 1.5 nm. The second doping layer is an N-type doped polysilicon layer (Poly-Si) with a thickness of 300 nm. Steps 1-5: Use laser etching and wet etching to remove the second interface passivation layer, the second doping layer, and the second oxide layer corresponding to the first doping region and the isolation region, and form a textured structure in the isolation region of the semiconductor substrate; the laser spot in the laser etching is adjusted to a "return" shape, the energy of the outer periphery of the outer spot is higher than the energy of the middle laser, the overall laser power is 50 W, and the spot size is an approximate square spot of 200 μm. The wet etching solution is a mixed solution of potassium hydroxide with a mass fraction of 0.5% and a texturing additive with a mass fraction of 0.5%. The etching temperature is 70 °C, and the etching time is 400 s, forming an isolation region with an area ratio of the first isolation region to the second isolation region of 1:10. The depth of the first isolation region is 4.5 μm, and the depth of the second isolation region is 2.0 μm; the morphology of the isolation region is as Figure 7 shown; Steps 1-6: Deposit a passivation and antireflection layer on the surface of the semiconductor substrate. Among them, the passivation and antireflection layer is a stacked structure, including: an oxide layer (with a thickness of 5 nm) and a nitride layer (with a thickness of 80 nm) in sequence. Steps 1-7: Print corresponding metal electrodes on the first doping region and the second doping region of the semiconductor substrate, including the first electrode and the second electrode, and obtain a solar cell after sintering and optical injection.

[0077] Example 2 The difference from Example 1 is the different morphology of the spot. Specifically: Steps 1-5: Use laser etching and wet etching to remove the second interface passivation layer, the second doping layer, and the second oxide layer corresponding to the first doping region and the isolation region, and form a textured structure in the isolation region of the semiconductor substrate; the laser spot in the laser etching is adjusted to a "return" shape, the energy of the outer periphery of the outer spot is higher than the energy of the middle laser, the overall laser power is 50 W, and the spot size is an approximate square spot of 200 μm. The wet etching solution is a mixed solution of potassium hydroxide with a mass fraction of 0.5% and a texturing additive with a mass fraction of 0.5%. The etching temperature is 70 °C, and the etching time is 400 s, forming an isolation region with an area ratio of the first isolation region to the second isolation region of 1:1. The depth of the first isolation region is 3.5 μm, and the depth of the second isolation region is 1.6 μm.

[0078] Example 3 The difference from Example 1 is the different morphology of the spot. Specifically: Steps 1-5: Use laser etching and wet etching to remove the second interface passivation layer, the second doping layer, and the second oxide layer corresponding to the first doping region and the isolation region, and form a textured structure in the isolation region of the semiconductor substrate; the laser spot in the laser etching is adjusted to a "return" shape, the energy of the outer periphery of the outer spot is higher than the energy of the middle laser, the overall laser power is 50 W, the spot size is an approximately square spot with a size of 200 μm, the wet etching solution is a mixed solution of potassium hydroxide with a mass fraction of 0.5% and a texturing additive with a mass fraction of 0.5%, the etching temperature is 70 °C, the etching time is 400 s, and an isolation region with an area ratio of the first isolation region to the second isolation region of 20:1 is formed, the depth of the first isolation region is 2.7 μm, and the depth of the second isolation region is 2.3 μm.

[0079] Example 4 The difference from Example 1 is the different morphology of the spot. As shown in the figure, specifically: Steps 1-5: Use laser etching and wet etching to remove the second interface passivation layer, the second doping layer, and the second oxide layer corresponding to the first doping region and the isolation region, and form a textured structure in the isolation region of the semiconductor substrate; the laser spot in the laser etching is adjusted to an "eye" shape, as Figure 4 (b) The energy of the outer periphery of the upper and lower spots is higher than the energy of the middle laser, the overall laser power is 50 W, the spot size is an approximately square spot with a size of 200 μm, the wet etching solution is a mixed solution of potassium hydroxide with a mass fraction of 0.5% and a texturing additive with a mass fraction of 0.5%, the etching temperature is 70 °C, the etching time is 400 s, and an isolation region with an area ratio of the first isolation region to the second isolation region of 2:1 is formed, the depth of the first isolation region is 3.1 μm, and the depth of the second isolation region is 1.8 μm.

[0080] Example 5 The difference from Example 1 is the different morphology of the spot. As shown in the figure, specifically: Steps 1-5: Use laser etching and wet etching to remove the second interface passivation layer, the second doping layer, and the second oxide layer corresponding to the first doping region and the isolation region, and form a textured structure in the isolation region of the semiconductor substrate; the laser spot in the laser etching is adjusted to a "cross" shape, the energy of the outer periphery of the upper and lower spots is higher than the energy of the middle laser, the overall laser power is 50 W, the spot size is an approximately square spot with a size of 200 μm, the wet etching solution is a mixed solution of potassium hydroxide with a mass fraction of 0.5% and a texturing additive with a mass fraction of 0.5%, the etching temperature is 70 °C, the etching time is 400 s, and an isolation region with an area ratio of the first isolation region to the second isolation region of 1.6:1 is formed, the depth of the first isolation region is 3.3 μm, and the depth of the second isolation region is 1.7 μm.

[0081] Comparative Example 1 The difference from Example 1 is that a single isolation zone with a depth of 2.5 μm is formed in steps 1-5.

[0082] Performance testing The performance of the solar cells from Examples 1-5 and Comparative Example 1 was compared and tested. The test conditions were as follows: Using a pulsed solar simulator, under ambient temperatures of 25°C, AM1.5 atmospheric mass, and a solar irradiance of 1000 W / m², the electrical performance parameters of the battery, including photoelectric conversion efficiency (Eta), fill factor (FF), open-circuit voltage (Voc), short-circuit current (Isc), and reverse current (IRev2), were measured. The test results are shown in Table 1. Table 1 is a comparison table of performance test results between the examples and the comparative examples.

[0083] The above are merely embodiments of this application and do not limit the scope of this patent application. Any equivalent structural or procedural changes made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A solar cell, characterized in that, include: A substrate having a first surface and a second surface disposed opposite to each other along the thickness direction, wherein the first surface is provided with alternating first doped regions and second doped regions; An isolation region is provided between the first doped region and the second doped region, and the isolation region includes a plurality of isolation units arranged along the extension direction of the isolation region; At least one of the isolation units includes: a first isolation zone and a second isolation zone connected to the first isolation zone; Along the extending direction of the isolation region, the two sides of the isolation unit are adjacent to the first doped region and the second doped region, respectively.

2. The solar cell according to claim 1, characterized in that, In a plane perpendicular to the thickness direction of the substrate, the first isolation region is at least partially circumferentially disposed around the outside of the second isolation region.

3. The solar cell according to claim 1, characterized in that, The first isolation region and the second isolation region are arranged sequentially in a plane perpendicular to the thickness direction of the substrate.

4. The solar cell according to claim 1, characterized in that, In a plane perpendicular to the thickness direction of the substrate, the first isolation region is discretely distributed around the second isolation region.

5. The solar cell according to claim 1, characterized in that, The solar cell is a back-contact solar cell; The first doped region and the second doped region have opposite doping types.

6. The solar cell according to claim 1, characterized in that, Along the thickness direction, with the surface of the second doped region away from the substrate as the reference plane, the maximum etching depth of the first isolation region in the thickness direction is H1, and the minimum etching depth of the second isolation region in the thickness direction is H2, and H1 > H2.

7. The solar cell according to claim 6, characterized in that, The maximum etching depth H1 of the first isolation region in the thickness direction satisfies: 1.0μm ≤ H1 ≤ 3.0μm; the minimum etching depth H2 of the second isolation region in the thickness direction satisfies: 0.5μm ≤ H2 ≤ 2.0μm.

8. The solar cell according to claim 1, characterized in that, The reflectivity of the first isolation zone is R1, and the reflectivity of the second isolation zone is R2, where R1 < R2.

9. The solar cell according to claim 1, characterized in that, The surface of the first isolation zone is a pyramidal velvet structure, and the surface of the second isolation zone is a polished surface, or a composite structure surface composed of a polished surface and a pyramidal micro-velvet surface.

10. The solar cell according to claim 9, characterized in that, When the surface of the second isolation zone is a composite structure composed of a polished surface and a pyramid-like micro-textured surface, the density of the pyramid-like micro-textured surface of the second isolation zone is less than the density of the pyramid-like textured surface of the first isolation zone, and the surface roughness of the second isolation zone is less than the surface roughness of the first isolation zone.

11. The solar cell according to claim 1, characterized in that, Along the extension direction perpendicular to the isolation zone, the width of the isolation zone is 20–500 μm; The ratio of the vertical projected area of ​​the first isolation zone to that of the second isolation zone on the first surface is 1:10–20:

1.

12. The solar cell according to claim 1, characterized in that, In the thickness direction, from the side away from the substrate to the side closer to the substrate, a first doped layer and a first interface passivation layer are sequentially stacked in the first doped region, and a second doped layer and a second interface passivation layer are sequentially stacked in the second doped region. The surfaces of the first doped layer, the second doped layer, and the isolation region are provided with passivation and antireflection layers.

13. A stacked battery, characterized in that, include: Top cell, which can be a perovskite cell, cadmium telluride solar cell, copper indium gallium selenide solar cell, or gallium arsenide solar cell; Intermediate connection layer; and The base cell is the solar cell according to any one of claims 1-12; The top battery, the intermediate connecting layer, and the bottom battery are stacked and connected.

14. A photovoltaic module, characterized in that, Includes the solar cell according to any one of claims 1-12, or the tandem cell according to claim 13.

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