Solar cell preparation method and solar cell

Abstract

The invention relates to the technical field of solar cells, and discloses a solar cell preparation method and a solar cell, and the solar cell preparation method comprises the steps: providing an initial fragmented cell sheet with a cross section; performing oxidation treatment on the cross section to form an oxide layer; forming a hydrogen-containing passivation layer on the surface, far away from the cross section, of the oxide layer; and performing hydrogen passivation activation treatment on the surface, far away from the oxide layer, of the hydrogen-containing passivation layer so as to release hydrogen ions in the hydrogen-containing passivation layer to the cross section, thereby forming a passivated fragmented battery piece. The cross section of an initial fragmented battery piece is subjected to oxidation treatment to form an oxidation layer, dangling bonds on the cross section are saturated, the passivation effect is improved, the surface, away from the oxidation layer, of a hydrogen-containing passivation layer is subjected to hydrogen passivation activation treatment, hydrogen ions in the hydrogen-containing passivation layer are released to the cross section, the damaged area of the cross section is passivated, and defects in the cross section are repaired. Therefore, the performance of the fragmented battery piece is improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and particularly relates to a method for preparing a solar cell and a solar cell. Background Art

[0002] Currently, the technology for preparing half-cut or multi-cut cells has the advantages of reducing the internal resistance of solar cells and improving the conversion efficiency of solar cells, and is widely used in the preparation process of solar cells. In the process of preparing half-cut or multi-cut cell components in related technologies, the conventional process is to divide the cell wafer into multiple pieces through laser scribing technology, and use ALD (Atomic Layer Deposition) technology to deposit a hybrid passivation layer on the cross-section.

[0003] However, the passivation effect of the cross-section of the existing cut cell wafers is poor, resulting in poor performance of the cell wafers. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a method for preparing a solar cell and a solar cell, so as to improve the passivation effect of the cross-section of the cut cell wafers and improve the performance of the cut cell wafers.

[0005] To solve the above technical problems, the embodiments of the present application provide a method for preparing a solar cell, including: providing an initial cut cell wafer with a cross-section; performing an oxidation treatment on the cross-section to form an oxide layer; forming a hydrogen-containing passivation layer on the surface of the oxide layer away from the cross-section; performing a hydrogen passivation activation treatment on the surface of the hydrogen-containing passivation layer away from the oxide layer to release hydrogen ions in the hydrogen-containing passivation layer to the cross-section, forming a passivated cut cell wafer.

[0006] The embodiments of the present application also provide a solar cell, including: the passivated cut cell wafer prepared by the method for preparing a solar cell as described above.

[0007] In some embodiments, the performing an oxidation treatment on the cross-section to form an oxide layer includes: performing a first preheating treatment on the cross-section to form an initial oxide layer on the cross-section; performing a second oxidation treatment on the initial oxide layer, and the initial oxide layer is oxidized to form the oxide layer.

[0008] In some embodiments, the second oxidation treatment is: performing a first laser treatment on the initial oxide layer in an oxygen-rich environment.

[0009] In some embodiments, the hydrogen passivation activation treatment is: a second laser treatment; the energy of the second laser treatment is lower than the energy of the first laser treatment.

[0010] In some embodiments, before performing the hydrogen passivation activation treatment on the surface of the hydrogen-containing passivation layer away from the oxide layer, it includes: performing a second preheating treatment on the surface of the hydrogen-containing passivation layer away from the oxide layer; the temperature of the second preheating treatment is lower than the temperature of the first preheating treatment.

[0011] In some embodiments, the thickness of the hydrogen-containing passivation layer is greater than the thickness of the oxide layer; the thickness of the oxide layer is 5 nm to 10 nm, and the thickness of the hydrogen-containing passivation layer is 5 nm to 50 nm.

[0012] In some embodiments, the power of the first laser treatment is 150 W to 300 W, and the temperature of the first laser treatment is 500 °C to 1000 °C; the power of the second laser treatment is 80 W to 150 W, and the temperature of the second laser treatment is 300 °C to 750 °C.

[0013] In some embodiments, the temperature of the first preheating treatment is 100 °C to 300 °C; the temperature of the second preheating treatment is 50 °C to 100 °C.

[0014] In some embodiments, the duration of the first preheating treatment is longer than the duration of the second oxidation treatment; the duration of the first preheating treatment is 600 s to 900 s; the duration of the second oxidation treatment is 100 s to 500 s.

[0015] The technical solutions provided by the embodiments of the present application have at least the following advantages: In the embodiments of the present application, an oxide layer is formed by performing an oxidation treatment on the cross-section of the initial sliced cell to saturate the dangling bonds on the cross-section and improve the passivation effect; after depositing a hydrogen-containing passivation layer on the oxide layer, a hydrogen passivation activation treatment is performed on the surface of the hydrogen-containing passivation layer away from the oxide layer to release hydrogen ions in the hydrogen-containing passivation layer to the cross-section, so as to passivate the cross-section damage area, repair the internal defects of the cross-section, form a passivated sliced cell, and improve the passivation effect of the sliced cell, thereby improving the performance of the sliced cell. Description of the Drawings

[0016] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the drawings in the figures do not constitute a proportional limitation.

[0017] Figure 1 It is a schematic structural diagram of a micron-scale crack at the cross-section of a sliced cell in the related art; Figure 2 It is a schematic structural diagram of a hybrid passivation layer thin film in the related art; Figure 3Schematic diagram for bisecting a solar cell; Figure 4 Schematic diagram for quartering a solar cell; Figure 5 Schematic diagram of the structure after the first preheating treatment in the solar cell preparation method provided in this embodiment; Figure 6 Schematic diagram of the structure after the second oxidation treatment in the solar cell preparation method provided in this embodiment; Figure 7 Schematic diagram of the structure after forming a hydrogen-containing passivation layer in the solar cell preparation method provided in this embodiment; Figure 8 Schematic diagram of the structure after the hydrogen passivation activation treatment in the solar cell preparation method provided in this embodiment; Figure 9 Schematic diagram of the structure of the hydrogen-containing passivation layer provided in this embodiment. Detailed implementation manners

[0018] As can be seen from the background art, the passivation effect of the cross-section of the existing segmented solar cells is poor, resulting in poor performance of the solar cells.

[0019] Through analysis and research, it is found that: in the preparation process of the currently known segmented solar cells, the conventional process is to divide the solar cell into two symmetric half-cells or multiple segments by laser scribing, and then deposit a mixed passivation layer film on the cross-section for passivation, and deliver it to the module for encapsulation and welding. However, the current laser scribing process will generate a thermal affected zone and a crack mechanical damage zone with a micron-level depth at the cross-section of the segmented solar cell. As Figure 1 shown, it is a schematic diagram of the micron-level crack structure at the cross-section of the segmented solar cell in the related art. Due to Figure 1 a large number of dangling bonds will be exposed in the micron-level crack region shown to form recombination centers, and the internal defects in the damage zone are serious and need to be repaired by certain means to obtain higher module power. In the related art, the ALD technology is used to deposit a mixed passivation layer. As Figure 2 shown, it is a schematic diagram of the structure of the mixed passivation layer film in the related art. However, the conventional ALD technology is usually used to passivate a relatively flat surface structure. In the cross-section structure, due to the too large surface roughness and the serious damage zone, it is very difficult for the single ALD low-temperature process to passivate the deep part of the damage zone, and a large number of hydrogen ions are concentrated in the film after low-temperature deposition of the film, and no obvious repair effect is exerted on the cross-section damage zone. Therefore, Figure 2 the low-temperature deposited mixed passivation layer film shown has poor density and poor passivation.

[0020] In order to improve the passivation effect of the cross-section of segmented solar cells and enhance the performance of the solar cells, an embodiment of the present application provides a method for manufacturing a solar cell. An oxidation layer is formed by oxidizing the cross-section of the initial segmented solar cell to saturate the dangling bonds on the cross-section and improve the passivation effect. After depositing a hydrogen-containing passivation layer on the oxidation layer, a hydrogen passivation activation treatment is performed on the surface of the hydrogen-containing passivation layer away from the oxidation layer to release hydrogen ions in the hydrogen-containing passivation layer to the cross-section, passivate the damaged area of the cross-section, repair the internal defects of the cross-section, form a passivated segmented solar cell, improve the passivation effect of the segmented solar cell, and thus enhance the performance of the segmented solar cell.

[0021] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality of" is more than two, unless otherwise clearly and specifically defined.

[0022] Referring to "embodiments" herein means that the specific features, structures, or characteristics described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0023] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B may mean: the existence of A, the simultaneous existence of A and B, and the existence of B. Additionally, the character " / " in this document generally represents an "or" relationship between the associated objects before and after.

[0024] In the description of the embodiments of the present disclosure, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of sheets" refers to more than two sheets (including two sheets).

[0025] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and does not indicate or imply that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the embodiments of the present disclosure.

[0026] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific situations.

[0027] In the corresponding drawings of the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layer are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component can be "directly" on the surface of another component, or there can be a third component between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of another component, nor on a partial edge of the entire surface.

[0028] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when components such as layers, films, regions, or plates are referred to as "on / located on" another component, it can be "directly on" another component (that is, located on the surface of another component and there is no other component between the two), or there can be another component between them. In addition, when components such as layers, films, regions, or plates are "directly located on" another component, or when components such as layers, films, regions, or plates are located on the surface of another component, it means that there is no other component between them.

[0029] Figures 3 to 8 Structural schematic diagrams corresponding to the steps of a method for preparing a solar cell provided in this embodiment.

[0030] Reference Figure 3 、 Figure 4 , Figure 3 is a schematic diagram of bisecting a battery cell, Figure 4 is a schematic diagram of quartering a battery cell. This embodiment provides an initial segmented battery cell 100 with a cross-section 101.

[0031] The initial segmented cell 100 of this embodiment is formed by laser scribing. A high-power density laser beam is used to irradiate the cell electrode material, causing it to rapidly heat up to melting, vaporization, or combustion, thereby cutting the cell to form the initial segmented cell 100. In other embodiments, the initial segmented cell 100 can also be obtained by other cutting processes, such as blade cutting, stamping cutting, wire saw cutting, etc., as long as there are micron-level cracks at the cross-section 101 of the initial segmented cell 100 as Figure 1 shown.

[0032] The cell is composed of a substrate material, a P-N junction, a front surface electrode, a back surface electrode, a passivation layer, and an antireflection layer. The substrate material is the main support of the cell and the generation layer of photo-generated carriers, and the substrate material is single-crystalline silicon or polycrystalline silicon; the P-N junction is composed of P-type and N-type regions and is used to separate photo-generated carriers; the front surface electrode is used to collect photo-generated carriers and transmit current, generally formed by screen printing silver paste; the back surface electrode is used to collect current and provide an electric field, generally composed of aluminum or other metal materials; the passivation layer is a thin film coated on the front and back surfaces of the cell to reduce surface recombination and improve cell efficiency; the antireflection layer is used to reduce light reflection and improve light absorption efficiency, generally materials such as silicon nitride SiNx.

[0033] In the production process of photovoltaic cells, the cell segmentation process is in the latter stage of cell production, that is, after the basic manufacturing process of the cell is completed, the cell is segmented. The basic manufacturing process of the cell includes: texturing, diffusion, coating, screen printing, sintering, etc. Before segmenting the cell, it is necessary to obtain the user's requirements for the photovoltaic module and segment the cell according to the photovoltaic module requirements to adapt to different sizes of photovoltaic modules; after segmenting the cell, the segmented cells are assembled to form a photovoltaic module.

[0034] After the cell is segmented, the initial segmented cell 100 of this embodiment is formed. The initial segmented cell 100 of this embodiment can be a half cell or a multi-segmented cell, which is specifically set according to actual needs. In the case where the initial segmented cell 100 is a half cell, there is only a cross-section on one side of the initial segmented cell 100, as Figure 3 shown, which is a schematic diagram of bisecting the cell. The cell is cut into two symmetric pieces, and there is only a cross-section 101 on one side of the initial segmented cell 100; in the case where the initial segmented cell 100 can be a half cell or a multi-segmented cell, there are cross-sections on multiple sides of the initial segmented cell 100, as Figure 4As shown, it is a schematic diagram of quartering the cell. The cell is cut into four pieces, and the initial segmented cell 100 has two adjacent cross-sections 101. The initial segmented cell 100 in this embodiment can also be a six-segmented cell, an eight-segmented cell, etc., and the specific cutting quantity is set according to actual requirements.

[0035] Reference Figure 3 , in this embodiment, the initial segmented cell 100 is a half cell for illustration purposes, that is, there is a cross-section 101 only on one side of the initial segmented cell 100 (i.e., Figure 3 the right side in Figure 3 ). In actual applications, when the initial segmented cell 100 is a multi-segmented cell, cross-sections 101 after cutting can also exist on other sides of the initial segmented cell 100 (i.e.,

[0036] the left side, the upper surface, and the lower surface in

[0037] ). The initial segmented cell 100 in this embodiment is still composed of a base material, a P-N junction, a front surface electrode, a back surface electrode, a passivation layer, and an antireflection layer. The initial segmented cell 100 after cutting can reduce the single-string current, reduce current loss, and at the same time improve the anti-mechanical load performance of the formed photovoltaic module. Figure 1 As shown in 2 , due to the micron-scale cracks in the initial segmented cell 100, a large number of Si-SiO Figure 2 dangling bonds are formed to form recombination centers, resulting in a too large roughness of the cross-section 101 and a relatively serious damage area. Referring to

[0038] , the deposited hybrid passivation layer in the related art cannot play an obvious repair role in the damaged area of the cross-section 101, resulting in poor denseness of the hybrid passivation layer film and poor passivation, resulting in a poor passivation effect on the cross-section of the initial segmented cell 100 after scribing. Figure 5 , Figure 6 , the cross-section 101 is oxidized to form an oxide layer 103.

[0039] In this embodiment, by oxidizing the cross-section of the initial segmented cell 100, an oxide layer 103 is formed, effectively passivating the surface states at the cross-section 101 of the initial segmented cell 100, reducing the recombination of some carriers, and improving the passivation effect of the cross-section 101 of the initial segmented cell 100; at the same time, the oxide layer 103 can block the diffusion of impurity atoms into the silicon substrate of the initial segmented cell 100, avoiding the diffusion of other atoms except hydrogen ions to the silicon substrate during the subsequent hydrogen passivation activation treatment, thereby maintaining a good passivation effect on the cross-section 101 of the initial segmented cell 100.

[0040] The oxide layer 103 in this embodiment is formed by oxidizing a part of the silicon substrate at the cross-section 101 to form silicon dioxide. After the cross-section 101 is oxidized, a dense oxide layer 103, i.e., silicon dioxide, is generated on the cross-section 101 to fully saturate the dangling bonds at the Si-SiO2 interface, improving the passivation effect of the oxide layer 103.

[0041] Since the higher the density of the oxide layer 103, the better the passivation effect of the cross-section 101 of the initial segmented cell 100. To further improve the passivation effect of the cross-section 101, two oxidation treatments are performed in this embodiment, namely the first preheating treatment and the second oxidation treatment, so as to improve the density of the oxide layer 103.

[0042] Reference Figure 5 , Figure 5 is a schematic structural diagram after the first preheating treatment in the method for preparing a solar cell provided in this embodiment. In this embodiment, the cross-section 101 is subjected to the first preheating treatment to form an initial oxide layer 102 on the cross-section 101.

[0043] To reduce the actual power of the subsequent first laser treatment and reduce the negative thermal damage effect of the first laser treatment on the cross-section 101, in this embodiment, before the first laser treatment, the cross-section 101 is subjected to the first preheating treatment to form an initial oxide layer 102 on the cross-section. Thus, before the first laser treatment, the cross-section 101 is first preheated. This can not only form the initial oxide layer 102, which is equivalent to pre-forming part of the oxide layer 103, reducing the time for the subsequent first laser treatment to form the oxide layer 103 and improving the efficiency of the first laser treatment, but also preheat the temperature of the cross-section 101 to the first preset temperature, reducing the actual power of the subsequent first laser treatment, thereby reducing the negative thermal damage effect of the first laser treatment on the cross-section 101, and thus improving the passivation effect of the formed oxide layer 103.

[0044] Before performing the first preheating treatment in this embodiment, the cross-section 101 of the initial segmented cell 100 is placed in a fixed fixture, and the cross-section 101 is placed in an ozone environment to perform the first preheating treatment. The ozone concentration ranges from 800 ppm to 1200 ppm. For example, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm. By setting the ozone concentration within this range, on the one hand, it provides a rich oxygen environment for preheating oxidation of the cross-section 101, which can not only improve the efficiency of the first preheating treatment, but also make the thickness of the generated initial oxide layer 102 uniform and dense, forming an initial oxide layer 102 with uniform and dense thickness. On the other hand, it can also avoid excessive oxidation of the cross-section 101 caused by too high ozone concentration, reduce the probability of defects in the cross-section 101 due to excessive oxidation, and thus improve the performance of the finally formed segmented cell, such as reducing recombination, improving carrier transport, increasing open voltage and fill factor, and increasing power, etc.

[0045] In addition, ozone, as a strong oxidant, can decompose various pollutants in a short time, making the cross-section 101 reach a high cleanliness. By setting the ozone concentration within this range in this embodiment, it can also effectively remove impurities and organic pollutants on the cross-section 101 and avoid damaging the cross-section 101.

[0046] In some embodiments, the preheating temperature of the first preheating treatment is from 100 °C to 300 °C. For example, 100 °C, 150 °C, 200 °C, 250 °C, 300 °C. By setting the temperature of the first preheating treatment within this range, on the one hand, the temperature of the cross-section 101 can be quickly preheated to the first preset temperature, reducing the actual power of the subsequent first laser treatment and avoiding damage to the cross-section 101 caused by too high power of the first laser treatment. On the other hand, it avoids the temperature of the cross-section 101 changing too fast due to too high preheating temperature, ensures uniform temperature distribution of the cross-section 101, reduces performance differences caused by local overheating or overcooling, provides a cross-section 101 with uniform temperature for the subsequent first laser treatment, improves the denseness of the generated oxide layer 103, and improves the passivation effect of the oxide layer 103.

[0047] In some embodiments, the duration of the first preheating treatment is from 600 s to 900 s. For example, 600 s, 650 s, 700 s, 750 s, 800 s, 850 s, 900 s. By setting the duration of the first preheating treatment within this range, on the one hand, it ensures the uniform temperature of the cross-section 101 after the first preheating treatment and improves the denseness of the oxide layer 103 generated by the first laser treatment. On the other hand, it avoids the problem of performance attenuation of the finally formed segmented cell caused by too long time of the first preheating treatment and improves the performance of the segmented cell.

[0048] After the first preheating treatment of the cross-section 101 of the initial segmented cell 100 in this embodiment, an initial oxide layer 102 is formed on the cross-section 101, which is equivalent to pre-forming a partial oxide layer 103, reducing the time for forming the oxide layer 103 in the subsequent first laser treatment. In some embodiments, the thickness of the initial oxide layer 102 is 1 nm to 3 nm, for example, 1 nm, 2 nm, 3 nm. By setting the thickness of the initial oxide layer 102 within this range, on the one hand, a partial oxide layer 103 can be pre-formed, reducing the time for forming the oxide layer 103 in the subsequent first laser treatment and improving the efficiency of the first laser treatment. On the other hand, it avoids the problem that the initial oxide layer 102 has poor passivation due to its relatively large thickness, resulting in the inability of the subsequent first laser treatment to effectively perform deep oxidation, thereby improving the passivation effect of the subsequently formed oxide layer 103.

[0049] Reference Figure 6 , Figure 6 FIG. 7 is a schematic structural diagram after the second oxidation treatment in the method for preparing a solar cell provided in this embodiment. In this embodiment, the initial oxide layer 102 is subjected to a second oxidation treatment, and the initial oxide layer 102 is oxidized to form an oxide layer 103.

[0050] After forming the initial oxide layer 102 on the cross-section 101 in this embodiment, the initial oxide layer 102 is subjected to a second oxidation treatment to increase the thickness and density of the initial oxide layer 102 to form an oxide layer 103, thereby forming an oxide layer 103 with uniform thickness and high density. Among them, the second oxidation treatment generates a denser oxide layer 103 relative to the first preheating treatment to fully saturate the dangling bonds at the Si—SiO 2 interface, improving the performance of the finally formed segmented cell, including reducing recombination, improving carrier transport, increasing the open voltage and fill factor, and increasing the power.

[0051] In some embodiments, the second oxidation treatment is: in an oxygen-rich environment, the initial oxide layer 102 is subjected to a first laser treatment. The oxygen-rich environment is an environment of an oxygen-containing liquid, so that the initial oxide layer 102 can be further oxidized to obtain an oxide layer with higher density. The first laser treatment in this embodiment can be realized by a red or green continuous-wave laser, and can also be realized by a picosecond or nanosecond laser. The laser irradiates the cross-section 101 perpendicular to the cross-section, and the shape of the light spot is circular or square. The range of the circular diameter or the square size is 1 mm to 2 mm. At the same time, hydrogen peroxide is sprayed on the cross-section 101 to provide an oxygen-rich environment on the high-temperature cross-section 101, and the purity of the hydrogen peroxide is 30%-40%. In other embodiments, other oxygen-containing liquids can also be sprayed on the cross-section, such as: ozone water, etc.

[0052] In some embodiments, the power of the first laser treatment is from 150 W to 300 W, for example, 150 W, 200 W, 250 W, 300 W. Since the cross-section 101 is preheated for the first time before the first laser treatment so that the temperature of the cross-section 101 reaches the first preset temperature and the temperature distribution of the cross-section 101 is uniform, therefore, the actual power of the first laser treatment can be set relatively low. Even if the power of the first laser treatment is set within this range, a uniform and dense oxide layer 103 can be formed on the cross-section 101; at the same time, when the power of the first laser treatment is set within this range, the negative effect of thermal damage caused by the laser to the cross-section 101 can also be reduced, and the performance of the finally formed segmented battery chip can be improved.

[0053] In some embodiments, during the first laser treatment, the scanning speed of the laser is from 1000 mm / s to 30000 mm / s, for example, 1000 mm / s, 1500 mm / s, 2000 mm / s, 2500 mm / s, 3000 mm / s. By setting the scanning speed of the laser within this range, on the one hand, the problem of uneven thickness of the formed oxide layer 103 caused by too fast scanning speed can be avoided, and on the other hand, the problem of excessive thermal damage to the cross-section 101 caused by too slow scanning speed can be avoided, thereby improving the passivation effect of the formed oxide layer 103.

[0054] In some embodiments, the temperature of the first laser treatment is from 500 °C to 1000 °C, for example, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C. By setting the temperature of the first laser treatment within this range, on the one hand, the density of the generated oxide layer 103 can be improved, and the passivation effect of the oxide layer 103 can be enhanced. On the other hand, heat accumulation can be reduced, and the problem of unnecessary thermal damage to the segmented battery chip caused by too high temperature of the first laser treatment can be avoided, thereby improving the performance of the finally formed segmented battery chip.

[0055] In some embodiments, the duration of the first preheating treatment is greater than the duration of the second oxidation treatment. By this setting, on the one hand, the temperature of the cross-section 101 obtained by the first preheating treatment can be relatively uniform, and the uniformity and density of the initial oxide layer 102 can also be improved. On the other hand, since the cross-section 101 has been preheated by the first preheating treatment, even if the duration of the second oxidation treatment is set shorter, an oxide layer 103 with uniform thickness and density can be generated. At the same time, the problem of thermal damage caused by too high temperature of the first laser treatment can also be avoided, and the performance of the segmented battery chip can be improved.

[0056] In some embodiments, the duration of the first laser treatment is from 100 s to 500 s, for example, 100 s, 200 s, 300 s, 400 s, 500 s. By setting the duration of the first laser treatment within this range, on the one hand, it can ensure that the thickness of the formed oxide layer 103 is uniform and has good compactness. On the other hand, it can avoid the problem of thermal damage to the cross-section 101 caused by too long a duration of the first laser treatment, and improve the performance of the finally formed segmented solar cell.

[0057] In some embodiments, the thickness of the oxide layer 103 is from 5 nm to 10 nm, for example, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm. By setting the thickness of the oxide layer 103 within this range, on the one hand, a relatively compact oxide layer 103 can be formed, improving the passivation effect of the oxide layer 103 and fully saturating the dangling bonds at the Si - SiO 2 interface of the silicon substrate. On the other hand, it can also avoid the situation where the hydrogen ions in the subsequent hydrogen passivation layer cannot effectively diffuse to the cross-section 101 due to too thick an oxide layer 103. Thus, the hydrogen ions in the subsequent hydrogen-containing passivation layer can be effectively released to the cross-section 101 to passivate the damaged area of the cross-section 101, repair the internal defects of the cross-section 101, improve the passivation effect of the segmented solar cell, and improve the performance of the segmented solar cell.

[0058] Reference Figure 7 , Figure 7 is a schematic structural diagram after forming the hydrogen-containing passivation layer in the solar cell preparation method provided in this embodiment. In this embodiment, a hydrogen-containing passivation layer 104 is formed on the surface of the oxide layer 103 away from the cross-section.

[0059] In this embodiment, by forming a hydrogen-containing passivation layer 104 on the surface of the oxide layer 103 away from the cross-section, a source of hydrogen ions 105 is provided for subsequent hydrogen passivation activation treatment, so as to release the hydrogen ions 105 in the hydrogen-containing passivation layer 104 to the cross-section 101, to passivate the damaged area of the cross-section 101, repair the internal defects of the cross-section 101, improve the passivation effect of the segmented solar cell, and improve the performance of the segmented solar cell.

[0060] In some embodiments, a conventional ALD low-temperature deposition of the hydrogen-containing passivation layer can be used, or other methods can also be used for deposition, such as PECVD (Plasma Enhanced Chemical Vapor Deposition), CVD (Chemical Vapor Deposition), PCVD (Photo Chemical Vapor Deposition), PVD (Physical Vapor Deposition), laser-induced deposition, etc.

[0061] In some embodiments, the hydrogen-containing passivation layer 104 may be alumina, and the hydrogen-containing passivation layer 104 may also be other hydrogen-containing materials, such as hydrogenated silicon nitride, hydrogenated amorphous silicon, hydrogenated silicon oxide, titanium dioxide, zinc oxide, etc.

[0062] In some embodiments, the thickness of the hydrogen-containing passivation layer 104 is greater than the thickness of the oxide layer 103. By such a setting, it can be ensured that the hydrogen-containing passivation layer 104 can provide a sufficient source of hydrogen ions 105 to penetrate the oxide layer 103, so that the hydrogen ions 105 in the hydrogen-containing passivation layer 104 can be effectively released to the cross-section 101 to passivate the damaged area of the cross-section 101, repair the internal defects of the cross-section 101, and improve the passivation effect of the segmented cell.

[0063] In some embodiments, the thickness of the hydrogen-containing passivation layer 104 is 5 nm to 50 nm, such as 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm. By setting the thickness of the hydrogen-containing passivation layer 104 within this range, on the one hand, the hydrogen-containing passivation layer 104 can provide a sufficient source of hydrogen ions 105, so that the hydrogen ions 105 in the hydrogen-containing passivation layer 104 can be effectively released to the cross-section 101 to passivate the damaged area of the cross-section 101, repair the internal defects of the cross-section 101, and improve the passivation effect of the segmented cell. On the other hand, during the subsequent second laser treatment process, the surface state density of the segmented cell can be effectively reduced, the surface defects of the segmented cell can be reduced, and the performance of the surface of the formed segmented cell can be improved.

[0064] Since the lower the deposition temperature of the hydrogen-containing passivation layer 104, the higher the content of hydrogen ions 105 in the hydrogen-containing passivation layer 104. In some embodiments, the process temperature for depositing the hydrogen-containing passivation layer 104 is 200 °C to 300 °C, such as 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C. By setting the process temperature for depositing the hydrogen-containing passivation layer 104 within this range, the deposition temperature of the hydrogen-containing passivation layer 104 can be made lower, which can increase the content of hydrogen ions 105 in the hydrogen-containing passivation layer 104. At the same time, the hydrogen-containing passivation layer 104 deposited at a low temperature can more effectively passivate the defects on the surface of the segmented cell and reduce the surface recombination rate of the segmented cell. In addition, by setting the process temperature for depositing the hydrogen-containing passivation layer 104 within this range, the distribution of hydrogen ions 105 in the hydrogen-containing passivation layer 104 can be made relatively uniform. Thus, during the subsequent second laser treatment process, the uniformly distributed hydrogen ions 105 can uniformly expand to the cross-section 101, better passivate the damaged area of the cross-section 101, repair the internal defects of the cross-section 101, improve the passivation effect of the segmented cell, and improve the performance of the segmented cell.

[0065] After depositing the hydrogen-containing passivation layer 104 in this embodiment, a second preheating treatment is performed on the surface of the hydrogen-containing passivation layer 104 away from the oxide layer 103.

[0066] By performing a second preheating treatment on the surface of the hydrogen-containing passivation layer 104 away from the oxide layer 103 in this embodiment, the hydrogen-containing passivation layer 104 can be preheated in advance so that the hydrogen-containing passivation layer 104 is preheated to a second preset temperature, reducing the actual power of the subsequent second laser treatment, thereby reducing the negative thermal damage effect of the second laser treatment on the hydrogen-containing passivation layer 104, and thus improving the passivation effect of the formed hydrogen-containing passivation layer 104.

[0067] In some embodiments, the temperature of the second preheating treatment is lower than the temperature of the first preheating treatment, that is, the second preset temperature is lower than the first preset temperature. Since the subsequent second laser treatment is to release hydrogen ions in the hydrogen-containing passivation layer 104 into the internal damage area of the cross-section 101 to repair internal lattice defects, the power of the second laser treatment is small, and the corresponding temperature of the second preheating treatment is also small. The first laser treatment is for deep oxidation, and the second oxidation treatment requires a relatively high temperature. Therefore, the power of the first laser treatment is larger than that of the second laser treatment, and the corresponding temperature of the first preheating treatment is also larger than that of the second preheating treatment. Through this setting, it can be ensured that the second preheating treatment can reduce the power of the subsequent second laser treatment while also ensuring that the temperature of the second preheating treatment is small, reducing the negative thermal damage effect of the second preheating treatment on the hydrogen-containing passivation layer 104, and thus improving the passivation effect of the formed hydrogen-containing passivation layer 104.

[0068] In some embodiments, the temperature of the second preheating treatment is 50°C to 100°C. For example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C. By setting the temperature of the second preheating treatment within this range, on the one hand, the preheating of the hydrogen-containing passivation layer 104 can be realized, reducing the power of the subsequent second laser treatment and avoiding damage to the hydrogen-containing passivation layer 104 caused by too high power of the second laser treatment. On the other hand, it can also avoid the rapid temperature change of the hydrogen-containing passivation layer 104 caused by too high temperature of the second preheating treatment, ensure the uniform temperature distribution of the hydrogen-containing passivation layer 104, reduce the performance differences caused by local overheating or overcooling, provide a hydrogen-containing passivation layer 104 with uniform temperature for the subsequent second laser treatment, and improve the passivation effect of the formed segmented solar cell.

[0069] Reference Figure 8 , Figure 8 is a schematic structural diagram after hydrogen passivation activation treatment in the solar cell preparation method provided in this embodiment. In this embodiment, a hydrogen passivation activation treatment is performed on the surface of the hydrogen-containing passivation layer 104 away from the oxide layer 103 to release hydrogen ions 105 in the hydrogen-containing passivation layer 104 to the cross-section 101 to form a passivated segmented solar cell.

[0070] In this embodiment, by performing a hydrogen passivation activation treatment on the hydrogen-containing passivation layer 104, hydrogen ions 105 in the hydrogen-containing passivation layer 104 are released to the cross-section 101 to passivate the damaged area of the cross-section 101, repair internal defects in the cross-section 101, form a passivated segmented cell, improve the passivation effect of the segmented cell, and improve the performance of the segmented cell.

[0071] In some embodiments, the hydrogen passivation activation treatment is: a second laser treatment. The second laser treatment in this embodiment can be implemented by a red or green continuous-wave laser, and can also be implemented by a picosecond or nanosecond laser. The laser irradiates the hydrogen-containing passivation layer 104 perpendicular to the cross-section, and the spot shape is circular or square. The range of the circular diameter or the square size is 1 mm to 2 mm to activate the hydrogen ions 105 enriched in the hydrogen-containing passivation layer 104 deposited at low temperature, so that the hydrogen ions 105 are released into the damaged area inside the cross-section 101 to repair internal lattice defects.

[0072] In some embodiments, the energy of the second laser treatment is lower than that of the first laser treatment. Since the first laser treatment is for deep oxidation to form the oxide layer 103, and the second laser treatment is for releasing hydrogen ions in the hydrogen-containing passivation layer 104 into the damaged area inside the cross-section 101 to repair internal lattice defects, the energy of the first laser treatment is greater than that of the second laser treatment. That is, the power of the second laser treatment is lower than that of the first laser treatment, and the temperature of the second laser treatment is lower than that of the first laser treatment. Through this setting, the second laser treatment can release the hydrogen ions in the hydrogen-containing passivation layer 104 to the cross-section 101 to passivate the damaged area of the cross-section 101 and repair internal defects in the cross-section 101, and at the same time, it can also avoid damage to the surface of the hydrogen-containing passivation layer 104 caused by too high energy of the second laser treatment, and improve the performance of the segmented cell.

[0073] In some embodiments, the power of the second laser treatment is 80 W to 150 W, for example, 80 W, 90 W, 100 W, 110 W, 120 W, 130 W, 140 W, 150 W. Since the cross-section 101 is subjected to a second preheating treatment before the second laser treatment to make the temperature of the hydrogen-containing passivation layer 104 reach the second preset temperature and the temperature distribution of the hydrogen-containing passivation layer 104 is uniform, the actual power of the second laser treatment can be set lower to reduce the power consumption of the second laser treatment. And even if the power of the second laser treatment is set within this range, the hydrogen ions 105 enriched in the hydrogen-containing passivation layer 104 can be released to the cross-section 101. At the same time, when the power of the second laser treatment is set within this range, it can also reduce the negative thermal damage effect of the laser on the hydrogen-containing passivation layer 104 and improve the performance of the finally formed segmented cell.

[0074] In some embodiments, during the second laser treatment process, the scanning speed of the laser is 1000 mm / s - 30000 mm / s. For example, 1000 mm / s, 1500 mm / s, 2000 mm / s, 2500 mm / s, 3000 mm / s. By setting the scanning speed of the laser within this range, on the one hand, it is possible to avoid the problem of uneven hydrogen ions released to the cross-section 101 due to too fast scanning speed. On the other hand, it is possible to avoid the problem of excessive thermal damage to the hydrogen-containing passivation layer 104 due to too slow scanning speed, thereby improving the quality of the surface of the hydrogen-containing passivation layer 104 and enhancing the passivation effect of the hydrogen-containing passivation layer 104.

[0075] In some embodiments, the temperature of the second laser treatment is 300 °C to 750 °C. For example, 300 °C, 350 °C, 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, 650 °C, 700 °C, 750 °C. By setting the temperature of the second laser treatment within this range, on the one hand, it is possible to activate the hydrogen ions 105 enriched in the hydrogen-containing passivation layer 104 deposited at low temperature, ensuring that the hydrogen ions 105 of the hydrogen-containing passivation layer 104 can be quickly released into the damaged area inside the cross-section 101 to repair the internal lattice defects. On the other hand, since the cross-section 101 is subjected to a second preheating treatment before the second laser treatment to make the temperature of the hydrogen-containing passivation layer 104 reach the second preset temperature, the temperature of the second laser treatment is relatively low. During the second laser treatment process, heat accumulation can be reduced, avoiding unnecessary thermal damage to the segmented solar cell due to too high temperature of the second laser treatment, and improving the performance of the finally formed segmented solar cell.

[0076] In this embodiment, through the above-mentioned method for preparing a solar cell, first, the cross-section 101 of the initial segmented solar cell 100 after division is subjected to a first preheating treatment to form an initial oxide layer 102 with a nanoscale thickness. Then, the initial oxide layer 102 is subjected to a first laser treatment. By using the instantaneous release of the focused laser energy to heat the initial oxide layer 102 while spraying strong oxidizing chemical reagents such as hydrogen peroxide, the inward diffusion of oxygen to the damaged area of the silicon substrate is further enhanced, saturating the Si-SiO 2 dangling bonds to form a denser oxide layer 103 and improving the passivation effect of the oxide layer 103; after depositing the hydrogen-containing passivation layer 104, the hydrogen-containing passivation layer 104 is subjected to a second laser treatment to activate the inward diffusion of the hydrogen ions 105 enriched in the hydrogen-containing passivation layer 104, thereby saturating the dangling bonds in the heat-affected zone and crack damage zone generated during the scribing process and the first laser treatment, repairing the lattice defects, and improving the performance of the segmented solar cell.

[0077] In this embodiment, through the above-mentioned method for preparing a solar cell, compared with the solution of only using the ALD technology to deposit a mixed passivation layer in the related art, the performance of the finally formed segmented solar cell is further improved, such as Figure 9As shown, it is a schematic structural diagram of the hydrogen-containing passivation layer of this embodiment. It can be seen that the hydrogen-containing passivation layer 104 formed in this embodiment has good compactness and better passivation effect, thereby improving the performance of the formed segmented cell, including reducing recombination, improving carrier transport, increasing the open voltage and fill factor, and increasing the power, etc. Among them, by using the preparation method of the solar cell of this embodiment, the open voltage of the prepared segmented cell is increased by 0.3 mV to 0.8 mV, the fill factor is increased by 0.05 to 0.15, the efficiency of the segmented cell is increased by 0.05% to 0.1%, and the power of the photovoltaic module formed by the segmented cell is increased by 0.5 W to 1 W.

[0078] Another embodiment of the present application provides a solar cell, as Figure 8 shown, it is a schematic structural diagram of the solar cell of this embodiment. The solar cell includes: a passivated segmented cell prepared by the solar cell preparation method of the above embodiment.

[0079] The segmented cell includes an initial segmented cell 100, the initial segmented cell 100 has a cross-section 101; an oxide layer 103, the oxide layer covers the cross-section; a hydrogen-containing passivation layer 104, the hydrogen-containing passivation layer covers the surface of the oxide layer 103 away from the cross-section 101.

[0080] Referring to Figures 3 to 8 , the segmented cell in the solar cell of this embodiment is prepared by the solar cell preparation method of the above embodiment. The oxide layer 103 is formed by oxidizing the cross-section 101 of the initial segmented cell. The oxide layer 103 can saturate the dangling bonds on the cross-section and improve the passivation effect; after depositing the hydrogen-containing passivation layer 104 on the oxide layer 103, a hydrogen passivation activation treatment is performed on the surface of the hydrogen-containing passivation layer 104 away from the oxide layer 103 to release the hydrogen ions 105 in the hydrogen-containing passivation layer 104 to the cross-section 101, so as to passivate the damaged area of the cross-section 101 and repair the internal defects of the cross-section 101, forming a passivated segmented cell and improving the passivation effect and performance of the segmented cell.

[0081] After being assembled, the solar cells of this embodiment will form a photovoltaic module. During the assembly process of the photovoltaic module, welding tapes are formed on the segmented solar cells, and the segmented solar cells are welded together through the welding tapes to form a battery string. Multiple battery strings are connected in series or in parallel according to the design requirements to form a complete battery module string, and then operations such as lamination, lamination, edge trimming, framing, and installing a junction box are carried out respectively to form a photovoltaic module. Since the photovoltaic module is composed of the solar cells of this embodiment, and because the solar cells of this embodiment have a good passivation effect, the power of the formed photovoltaic module is improved. Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present application, and in actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A method for preparing a solar cell, characterized in that: include: Providing an initially sliced ​​battery sheet having a cross section; performing oxidation treatment on the cross section to form an oxide layer; forming a hydrogen-containing passivation layer on a surface of the oxide layer away from the cross section; A hydrogen passivation activation treatment is performed on the surface of the hydrogen-containing passivation layer away from the oxide layer to release hydrogen ions in the hydrogen-containing passivation layer to the cross section to form a passivated sliced ​​battery cell.

2. The method for preparing a solar cell according to claim 1, characterized in that: The step of performing oxidation treatment on the cross section to form an oxide layer comprises: performing a first preheating treatment on the cross section to form an initial oxide layer on the cross section; The initial oxide layer is subjected to a second oxidation treatment, and the initial oxide layer is oxidized to form the oxide layer.

3. The method for preparing a solar cell according to claim 2, characterized in that: The second oxidation treatment is: performing a first laser treatment on the initial oxide layer in an oxygen-rich environment.

4. The method for preparing a solar cell according to claim 3, characterized in that: The hydrogen passivation activation treatment is: a second laser treatment; the energy of the second laser treatment is lower than the energy of the first laser treatment.

5. The method for preparing a solar cell according to claim 2, characterized in that: Before performing hydrogen passivation activation treatment on the surface of the hydrogen-containing passivation layer away from the oxide layer, the method comprises: A second preheating treatment is performed on the surface of the hydrogen-containing passivation layer away from the oxide layer; the temperature of the second preheating treatment is lower than the temperature of the first preheating treatment.

6. The method for preparing a solar cell according to claim 1, characterized in that: The thickness of the hydrogen-containing passivation layer is greater than that of the oxide layer; the thickness of the oxide layer is 5 nm to 10 nm, and the thickness of the hydrogen-containing passivation layer is 5 nm to 50 nm.

7. The method for preparing a solar cell according to claim 4, characterized in that: The power of the first laser treatment is 150W to 300W, and the temperature of the first laser treatment is 500°C to 1000°C; the power of the second laser treatment is 80W to 150W, and the temperature of the second laser treatment is 300°C to 750°C.

8. The method for preparing a solar cell according to claim 5, characterized in that: The temperature of the first preheating treatment is 100°C to 300°C; the temperature of the second preheating treatment is 50°C to 100°C.

9. The method for preparing a solar cell according to claim 2 or 3, characterized in that: The duration of the first preheating treatment is longer than that of the second oxidation treatment; the duration of the first preheating treatment is 600s to 900s; the duration of the second oxidation treatment is 100s to 500s.

10. A solar cell, characterized in that: include: The passivated split cell prepared by the solar cell preparation method according to any one of claims 1 to 9.

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