Solar cell and photovoltaic module

Abstract

The embodiment of the present application relates to the technical field of solar cells, in particular to a solar cell and a photovoltaic module, the solar cell comprising: a substrate having a first surface, the first surface having a metal pattern region and a non-metal pattern region; a first doped layer located in the substrate, the substrate exposing a top surface of the first doped layer, the top surface of the first doped layer being coincident with at least part of the non-metal pattern region, the first doped layer having a doping element concentration greater than a doping element concentration of a region in the substrate other than the first doped layer; a tunneling layer covering the metal pattern region; a doped conductive layer comprising a first portion and a second portion, the first portion being located on a surface of the tunneling layer away from the substrate, and the second portion being located on the top surface of the first doped layer; and a first electrode opposite the metal pattern region, the first electrode being in electrical contact with the first portion. The embodiment of the present application is conducive to improving the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

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

[0002] Solar cells possess excellent photoelectric conversion capabilities. Currently, tunneling layers and doped conductive layers are fabricated on the substrate surface to suppress carrier recombination on the substrate surface and enhance passivation. The tunneling layer provides good chemical passivation, while the doped conductive layer provides good field passivation. Furthermore, to transport and collect photogenerated carriers generated by the solar cell, electrodes electrically contacting the doped conductive layer are fabricated for carrier collection. The carrier transport path typically involves transport from the substrate to the tunneling layer, tunneling through the tunneling layer to the doped conductive layer, and then being collected by the electrodes electrically contacting the doped conductive layer. Enhancing carrier transport and collection capabilities plays a crucial role in improving the photoelectric conversion performance of solar cells.

[0003] However, solar cells have poor photoelectric conversion performance. Summary of the Invention

[0004] This application provides a solar cell and a photovoltaic module, which at least helps to improve the photoelectric conversion efficiency of the solar cell.

[0005] This application provides a solar cell, comprising: a substrate having a first surface, the first surface having a metallic patterned region and a non-metallic patterned region; a first doped layer located within the substrate, the substrate exposing the top surface of the first doped layer, the top surface of the first doped layer overlapping at least a portion of the non-metallic patterned region, the doping element concentration of the first doped layer being greater than the doping element concentration of the region within the substrate excluding the first doped layer; a tunneling layer covering the metallic patterned region; a doped conductive layer including a first portion and a second portion, the first portion being located on the surface of the tunneling layer away from the substrate, and the second portion being located on the top surface of the first doped layer; and a first electrode facing the metallic patterned region, the first electrode being in electrical contact with the first portion.

[0006] In addition, the top surface of the first doped layer coincides with part of the non-metallic patterned region.

[0007] In addition, the top surface of the first doped layer coincides with the entire non-metallic patterned region.

[0008] In addition, the tunneling layer and the first doped layer are arranged alternately along a first direction, which is the direction from the metal pattern region to the non-metal pattern region.

[0009] In addition, the sidewall of the tunneling layer along the first direction is flush with the sidewall of the first doped layer along the first direction.

[0010] Additionally, along the first direction, a portion of the sidewall of the second part contacts the sidewall of the tunneling layer.

[0011] In addition, the thickness of the first part is the same as the thickness of the second part.

[0012] In addition, the ratio of the doping element concentration of the first doped layer to the doping element concentration of the region in the substrate other than the first doped layer is 10:1 to 1000:1.

[0013] In addition, the doping element concentration of the first doped layer is 1×10 18 atom / cm 3 ~5×10 20 atom / cm 3 .

[0014] In addition, the solar cell also includes: a second doped layer located within the substrate, the second doped layer and the first doped layer being arranged alternately, and the top surface of the second doped layer being in contact with the surface of the tunneling layer facing the substrate, the doping element concentration of the second doped layer being less than the doping element concentration of the first doped layer, and greater than the doping element concentration of the region within the substrate excluding the second doped layer and the first doped layer.

[0015] In addition, the ratio of the doping element concentration of the first doped layer to the doping element concentration of the second doped layer is 5:1 to 200:1.

[0016] In addition, the doping element concentration of the second doped layer is 1×10 16 atom / cm 3 ~1×10 20 atom / cm 3 .

[0017] In addition, the thickness of the first doped layer is greater than the thickness of the second doped layer.

[0018] In addition, the ratio of the thickness of the first doped layer to the thickness of the second doped layer is 1.5:1 to 6:1.

[0019] 21. In addition, in the direction from the metal pattern region to the non-metal pattern region, the ratio of the width of the second doped layer to the width of the first doped layer is 5:1 to 20:1.

[0020] In addition, the solar cell also includes: a first passivation layer, the first passivation layer covering the surface of the doped conductive layer away from the substrate, and the first electrode penetrating the first passivation layer to make electrical contact with the doped conductive layer.

[0021] Additionally, the substrate has a second surface opposite to the first surface, and the height of the top surface of the first passivation layer opposite to the first portion relative to the second surface is higher than the height of the top surface of the first passivation layer opposite to the second portion relative to the second surface.

[0022] In addition, the materials doped with conductive layers include at least one of amorphous silicon, polycrystalline silicon, and silicon carbide.

[0023] In addition, the material of the tunneling layer includes at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon, or polycrystalline silicon.

[0024] Accordingly, this application also provides a photovoltaic module, including a battery string, which is formed by connecting a plurality of solar cells as described in any one of the above claims; an encapsulation layer for covering the surface of the battery string, and a cover plate for covering the surface of the encapsulation layer away from the battery string.

[0025] The technical solution provided in this application has at least the following advantages:

[0026] In the solar cell technical solution provided in this application embodiment, a first doped layer is located within the substrate, and the top surface of the first doped layer overlaps with at least a portion of the non-metallic pattern region. The doping element concentration of the first doped layer is greater than the doping element concentration in the substrate excluding the first doped layer, so that the presence of the first doped layer can form a back electric field in the substrate directly opposite the non-metallic pattern region. A second portion of the doped conductive layer is located on the top surface of the first doped layer, i.e., in contact with the top surface of the first doped layer. Under the potential of the back electric field, it can enhance the transport of charge carriers in the substrate to the second portion, thereby enhancing the transport of charge carriers in the substrate directly opposite the non-metallic pattern region to the first electrode, and improving the photoelectric conversion efficiency of the solar cell.

[0027] Furthermore, the first electrode is in electrical contact with the first portion, and the tunneling layer on the metal pattern region is in contact with the first portion of the doped conductive layer, which can reduce the high recombination loss caused by the contact between the first electrode and the first portion. Meanwhile, the first doped layer on the non-metallic pattern region is in direct contact with the second portion, which avoids the tunneling layer's obstruction of carrier transport, further enhancing carrier transport and improving the photoelectric conversion efficiency of the solar cell. Attached Figure Description

[0028] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0029] Figure 1 This is a schematic diagram of a cross-sectional structure of a solar cell;

[0030] Figure 2 A cross-sectional structural schematic diagram of a solar cell provided in an embodiment of this application;

[0031] Figure 3 This is a schematic diagram of carrier transport in a solar cell provided in one embodiment of this application;

[0032] Figure 4 A cross-sectional structural schematic diagram of another solar cell provided in an embodiment of this application;

[0033] Figure 5 A cross-sectional structural schematic diagram of another solar cell provided in an embodiment of this application;

[0034] Figure 6 A cross-sectional structural schematic diagram of another solar cell provided in an embodiment of this application;

[0035] Figure 7 A cross-sectional structural schematic diagram of a photovoltaic module provided for another embodiment of this application;

[0036] Figure 8 This is a cross-sectional structural diagram corresponding to the step of providing a substrate in a method for fabricating a solar cell according to an embodiment of this application;

[0037] Figure 9 This is a schematic cross-sectional view of the step of forming the emitter in a method for fabricating a solar cell according to an embodiment of this application.

[0038] Figure 10 This is a schematic cross-sectional view of the step of forming the initial tunneling layer in a method for fabricating a solar cell according to an embodiment of this application.

[0039] Figure 11 This is a cross-sectional structural diagram corresponding to the step of forming a mask layer in a method for fabricating a solar cell according to an embodiment of this application;

[0040] Figure 12 This is a cross-sectional structural diagram corresponding to the step of forming the first opening in a method for fabricating a solar cell according to an embodiment of this application;

[0041] Figure 13This is a schematic cross-sectional view of the step of forming a tunneling layer in a method for fabricating a solar cell according to an embodiment of this application.

[0042] Figure 14 This is a schematic cross-sectional view of the step of forming the first doped layer in a method for fabricating a solar cell according to an embodiment of this application.

[0043] Figure 15 This is a cross-sectional structural diagram corresponding to the step of forming a doped conductive layer in a method for fabricating a solar cell according to an embodiment of this application;

[0044] Figure 16 This is a schematic cross-sectional view of the step of forming an initial first doped layer in a method for fabricating a solar cell according to an embodiment of this application.

[0045] Figure 17 This is a schematic cross-sectional view of the step of forming a dopant layer in another method for fabricating a solar cell according to an embodiment of this application.

[0046] Figure 18 This is a cross-sectional structural schematic diagram corresponding to the steps of forming a first doped layer, a second doped layer, and a doped conductive layer in another method for fabricating a solar cell according to an embodiment of this application.

[0047] Figure 19 This is a cross-sectional structural diagram corresponding to the steps of forming a first passivation layer and a second passivation layer in a method for fabricating a solar cell according to an embodiment of this application. Detailed Implementation

[0048] As is known from the background technology, current solar cells suffer from low photoelectric conversion efficiency.

[0049] Analysis revealed that one of the reasons for the low photoelectric conversion efficiency of current solar cells is that... Figure 1 In traditional TOPCon (Tunnel Oxide Passivated Contact) solar cells, a tunneling layer 2 and a doped conductive layer 3 are disposed on one surface of the substrate 1, with the electrode 4 in electrical contact with the doped conductive layer 3. Charge carriers in the substrate 1 must first be transported to the tunneling layer 2, then to the doped conductive layer 3, and finally to the electrode 4. For the region directly opposite the electrode 4, charge carriers can be transported vertically from the substrate 1 through the tunneling layer 2 to the electrode 4 in the doped conductive layer 3 along the direction from the substrate 1 to the electrode 4, resulting in relatively smooth transport. However, for the region not directly opposite the electrode 4, charge carriers must first pass through the tunneling layer 2 and then be transported laterally through the doped conductive layer 3 to reach the electrode 4, thus hindering current transport.

[0050] This application provides a solar cell with a first doped layer located within a substrate, the top surface of which overlaps with a non-metallic patterned region. The doping concentration of the first doped layer is greater than that of other regions in the substrate, allowing the presence of the first doped layer to create a back electric field. A second portion of the doped conductive layer is located on the top surface of the first doped layer, i.e., in contact with it. Under the potential of the back electric field, it enhances the transport of charge carriers from the substrate to the second portion, thereby enhancing overall charge carrier transport and improving the photoelectric conversion efficiency of the solar cell. Furthermore, the first electrode is in electrical contact with the first portion, and a tunneling layer is formed on the metallic patterned region that contacts the first portion of the doped conductive layer, reducing the high recombination loss caused by the contact between the first electrode and the first portion. The direct contact between the first doped layer on the non-metallic patterned region and the second portion avoids the obstruction of charge carrier transport by the tunneling layer, further enhancing charge carrier transport and improving the photoelectric conversion efficiency of the solar cell.

[0051] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0052] Figure 2 This is a cross-sectional structural diagram of a first type of solar cell provided in an embodiment of this application.

[0053] refer to Figure 2 The solar cell includes: a substrate 100 having a first surface, the first surface having a metallic patterned region 10 and a non-metallic patterned region 11. The solar cell also includes: a first doped layer 110 located within the substrate 100, with the top surface of the first doped layer 110 exposed on the substrate 100, the top surface of the first doped layer 110 overlapping at least partially with the non-metallic patterned region 11, and the doping element concentration of the first doped layer 110 being greater than the doping element concentration of the regions within the substrate 100 excluding the first doped layer 110. The solar cell further includes: a tunneling layer 120 covering the metallic patterned region 10. The solar cell also includes: a doped conductive layer 130 including a first portion 131 and a second portion 132, the first portion 131 being located on the surface of the tunneling layer 120 away from the substrate 100, and the second portion 132 being located on the top surface of the first doped layer 110. The solar cell further includes: a first electrode 140 facing the metallic patterned region 10, the first electrode 140 being in electrical contact with the first portion 131.

[0054] The first doped layer 110 is located within the substrate 100, the substrate 100 exposes the top surface of the first doped layer 110, and the top surface of the first doped layer 110 coincides with at least a portion of the non-metallic pattern region 11. That is, the top surface of the first doped layer 110 is part of the first surface, and the first doped layer 110 is directly opposite to at least a portion of the non-metallic pattern region 11.

[0055] In some embodiments, the material of the first doped layer 110 is the same as the material of the substrate 100.

[0056] The concentration of doped elements in the first doped layer 110 is greater than the doping concentration in the substrate 100 excluding the first doped layer 110. In other words, there is a concentration difference between the concentration of doped elements in the first doped layer 110 and the concentration of doped elements in the substrate 100 excluding the first doped layer 110, and the existence of this concentration difference can form a back electric field in the substrate 100 opposite to the non-metallic pattern region 11.

[0057] The doped conductive layer 130 includes a first portion 131 and a second portion 132, wherein the second portion 132 is located on the top surface of the first doped layer 110, that is, the second portion 132 is in direct contact with the top surface of the first doped layer 110.

[0058] refer to Figure 3 Under the influence of the back electric field potential, it is possible to enhance the flow of charge carriers in the substrate 100 to the second part 132 (reference). Figure 2 This enhances the transmission of charge carriers in the substrate 100, which is directly opposite the non-metallic pattern region 11, to the first electrode 140, thereby improving the photoelectric conversion efficiency of the solar cell.

[0059] The first electrode 140 is in electrical contact with the first portion 131, and a tunneling layer 120 is provided on the metal pattern region 10 to contact the first portion 131 of the doped conductive layer 130, which can reduce the high recombination loss caused by the contact between the first electrode 140 and the first portion 131.

[0060] The first doped layer 110 on the non-metallic patterned region 11 is in direct contact with the second part 132. That is, no tunneling layer 120 is provided between the second part 132 and the first doped layer 110. This can avoid the obstruction of carrier transport caused by the tunneling layer 120, further improve the transport of carriers, and further improve the photoelectric conversion efficiency of the solar cell.

[0061] The substrate 100 is used to receive incident light and generate photogenerated carriers. In some embodiments, the substrate 100 may be a silicon substrate, and the material of the silicon substrate may include at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 100 may also be silicon carbide, organic materials, or multi-component compounds. Multi-component compounds may include, but are not limited to, materials such as perovskite, gallium arsenide, cadmium telluride, and copper indium selenide.

[0062] The first electrode 140 is located within the first portion 131 and is in electrical contact with the first portion 131. Photogenerated carriers generated in the substrate 100 are transported from the substrate 100 to the doped conductive layer 130 and then to the first electrode 140. The first electrode 140 is used to collect the photogenerated carriers.

[0063] In some embodiments, the solar cell has a plurality of first electrodes 140, and the plurality of first electrodes 140 are arranged at intervals along a first direction. The metallic patterned region 10 is the region on the first surface directly opposite the first electrode 140, and the non-metallic patterned region 11 can be the region on the first surface directly opposite the gap between two adjacent first electrodes 140. Figure 2 The metal pattern area 10 and non-metal pattern area 11 shown are for illustrative purposes only. In reality, on the first surface, there can be multiple metal pattern areas 10 and non-metal pattern areas 11, and the metal pattern areas 10 and non-metal pattern areas 11 are arranged alternately along the first direction.

[0064] In the embodiments of this application, the first electrode 140 being directly opposite the metal pattern region 10 means that the orthographic projection of the first electrode 140 on the first surface falls into or coincides with the metal pattern region 10, and not merely that the projection of the center of the first electrode 140 on the first surface coincides with the center of the metal pattern region 10.

[0065] In some embodiments, the solar cell can be a TOPCON cell, and the substrate 100 has a second surface opposite to the first surface. Both the first and second surfaces can be used to receive incident light or reflect light. In some embodiments, the substrate 100 contains dopant elements, which are either N-type or P-type. The N-type element can be a group V element such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), and the P-type element can be a group III element such as boron (B), aluminum (Al), gallium (Ga), or gallium (In). For example, when the substrate 100 is a P-type substrate, the internal dopant element is P-type. Alternatively, when the substrate 100 is an N-type substrate, the internal dopant element is N-type.

[0066] In some embodiments, the doping element type of the first doped layer 110 is the same as the doping element type of the region of the substrate 100 other than the first doped layer 110. That is, in some embodiments, the doping element type of the first doped layer 110 is P-type, and the doping element type of the region of the substrate 100 other than the first doped layer 110 is also P-type. The P-type element can be a group III element such as boron (B), aluminum (Al), gallium (Ga), or gallium (In). In some embodiments, the doping element type of the first doped layer 110 is N-type, and the doping element type of the region of the substrate 100 other than the first doped layer 110 is also N-type. The N-type element can be a group V element such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As).

[0067] refer to Figure 2 In some embodiments, the top surface of the first doped layer 110 overlaps with a portion of the non-metallic patterned region 11. That is, the first doped layer 110 is disposed only in the substrate 100 directly opposite the portion of the non-metallic patterned region 11. In some embodiments, a tunneling layer 120 may be disposed in a region of the non-metallic patterned region 11 that does not overlap with the top surface of the first doped layer 110, through which charge carriers in the substrate 100 directly opposite the tunneling layer 120 tunnel to the doped conductive layer 130.

[0068] It is easy to understand that although the tunneling layer 120 restricts carrier transport to some extent, it also provides good passivation for the first surface, reducing carrier recombination. Based on this, the top surface of the first doped layer 110 overlaps with a portion of the non-metallic patterned region 11, enhancing carrier transport in the substrate 100 directly opposite the non-metallic patterned region 11. The remaining portion of the non-metallic patterned region 11 that does not overlap with the top surface of the first doped layer 110 can be provided with the tunneling layer 120, which provides good chemical passivation for this portion of the non-metallic patterned region 11.

[0069] refer to Figure 4 In some embodiments, the top surface of the first doped layer 110 coincides with the entire non-metallic patterned region 11. That is, the entire top surface of the first doped layer 110 serves as the non-metallic patterned region 11 of the first surface, resulting in a large area proportion of the top surface of the first doped layer 110 on the first surface. This allows the back electric field formed by the first doped layer 110 in the substrate 100 to have a large area, enabling all charge carriers in the substrate 100 directly opposite the non-metallic patterned region 11 to be smoothly transported to the first electrode 140 in the doped conductive layer 130 under the influence of the back electric field potential. This enhances the charge carrier collection capability of the first electrode 140, thereby improving the photoelectric conversion performance of the solar cell.

[0070] There is a concentration difference between the doping element concentration of the first doped layer 110 and the doping element concentration of the region of the substrate 100 other than the first doped layer 110. The presence of this concentration difference can form a back electric field in the substrate 100 opposite to the non-metallic pattern region 11.

[0071] The concentration difference between the dopant concentration of the first doped layer 110 and the dopant concentration in the region of the substrate 100 excluding the first doped layer 110 needs to be set relatively large, such that the concentration difference is sufficient to form a back electric field. On the other hand, the concentration difference between the dopant concentration of the first doped layer 110 and the dopant concentration in the region of the substrate 100 excluding the first doped layer 110 should not be set too large, to prevent the problem of too many carrier recombination centers being generated on the top surface of the first doped layer 110 due to excessive dopant concentration.

[0072] In some embodiments, the ratio of the dopant concentration of the first doped layer 110 to the dopant concentration of the region within the substrate 100 excluding the first doped layer 110 is 10:1 to 1000:1, for example, it can be 10:1 to 20:1, 20:1 to 50:1, 50:1 to 100:1, 200:1 to 300:1, 300:1 to 380:1, 380:1 to 500:1, 500:1 to 600:1, 600:1 to 700:1, 700:1 to 800:1, 800:1 to 900:1, or 900:1 to 1000:1. Within this range, a large doping concentration difference can be achieved between the doping element concentrations of the first doped layer 110 and the doping element concentrations of the first doped layer 110. The existence of this doping concentration difference is sufficient to form a back electric field. Under the potential of the back electric field, the transport of charge carriers in the substrate 100 opposite to the first doped layer 110 to the doped conductive layer 130 can be enhanced, thereby improving the charge carrier collection capability of the first electrode 140.

[0073] In some embodiments, the dopant concentration of the first doped layer 110 is 1 × 10⁻⁶. 18 atom / cm 3 ~5×10 20 atom / cm 3 For example, it can be 1×10 18 atom / cm 3 ~1.25×10 18 atom / cm 3 1.25×10 18 atom / cm 3 ~1.5×10 18 atom / cm 3 1.5×10 18 atom / cm 3~5×10 18 atom / cm 3 5×10 18 atom / cm 3 ~1×10 19 atom / cm 3 1×10 19 atom / cm 3 ~1.5×10 19 atom / cm 3 1.5×10 19 atom / cm 3 ~5×10 19 atom / cm 3 Or 5×10 19 atom / cm 3 ~1×10 20 atom / cm 3 Within this range, the doping concentration of the first doped layer 110 is not excessively high compared to the doping concentration of the substrate 100, thus avoiding the problem of excessive carrier recombination centers being generated on the top surface of the first doped layer 110 due to the doping concentration of the substrate 100 not being too high. Simultaneously, within the aforementioned range, the first doped layer 110 has a sufficiently high doping concentration to form a back electric field in the substrate 100.

[0074] refer to Figure 5 In some embodiments, the solar cell further includes: a second doped layer 190 located within the substrate 100, the second doped layer 190 and the first doped layer 110 being arranged alternately, and the top surface of the second doped layer 190 being in contact with the surface of the tunneling layer 120 facing the substrate 100, the doping element concentration of the second doped layer 190 being less than the doping element concentration of the first doped layer 110, and greater than the doping element concentration of the region within the substrate 100 excluding the second doped layer 190 and the first doped layer 110.

[0075] The substrate 100 exposes the top surface of the second doped layer 190. In some embodiments, if the top surface of the first doped layer 110 coincides with the entire non-metallic patterned region 11, then the top surface of the second doped layer 190 may coincide with the metallic patterned region 10. In some embodiments, if the top surface of the first doped layer 110 coincides with a portion of the non-metallic patterned region 11, then the top surface of the second doped layer 190 may coincide with the metallic patterned region 10 and with regions of the non-metallic patterned region 11 that do not coincide with the top surface of the first doped layer 110. In some embodiments, the material of the second doped layer 190 is the same as the material of the substrate 100.

[0076] It is easy to see that the second doped layer 190 is directly opposite the metal pattern region 10. Setting the doping concentration of the second doped layer 190 to be greater than the doping concentration in the substrate 100 excluding the second doped layer 190 and the first doped layer 110 allows the formation of a concentration gradient from the second doped layer 190 to the substrate 100 excluding the second doped layer 190 and the first doped layer 110, thereby forming a high-low junction. In some embodiments, the doping element type of the second doped layer 190 is the same as that of the substrate 100, thus creating a concentration gradient of the same doping element type within the substrate 100. This creates a potential barrier effect for the carriers in the substrate 100 opposite the metal pattern region 10, reducing carrier recombination in the metal pattern region 10 and enhancing the carrier collection capability of the metal pattern region 10.

[0077] In some embodiments, the doping element type of the second doped layer 190 is the same as that of the first doped layer 110. In some embodiments, the doping element type of the second doped layer 190 and the first doped layer 110 can both be p-type, and the p-type element can be a group III element such as boron (B), aluminum (Al), gallium (Ga), or gallium (In). In some embodiments, the doping element type of the second doped layer 190 and the first doped layer 110 can both be n-type, and the n-type element can be a group V element such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As).

[0078] Since the first electrode 140 faces the metal pattern region 10, there is a high recombination loss between the first electrode 140 and the first portion 131 of the doped conductive layer 130. If the dopant concentration of the second doped layer 190 is too high, it may lead to excessive Auger recombination in the metal pattern region 10, resulting in too many carrier recombination centers and exacerbating the carrier recombination problem. However, the first electrode 140 does not face the non-metallic pattern region 11, meaning that the recombination loss in the second portion 132 of the doped conductive layer 130 is less. Therefore, the dopant concentration of the second doped layer 190 is set lower than that of the first doped layer 110, making the second doped layer 190 lightly doped. This enhances carrier transport without causing severe carrier recombination in the metal pattern region 10. The first doped layer 110 is heavily doped, which significantly enhances carrier transport in the substrate 100 facing the non-metallic pattern region 11, improving the carrier collection capability of the first electrode 140.

[0079] In some embodiments, the ratio of the dopant concentration of the first doped layer 110 to the dopant concentration of the second doped layer 190 is 5:1 to 200:1, for example, it can be 5:1 to 10:1, 10:1 to 50:1, 50:1 to 80:1, 80:1 to 100:1, 100:1 to 130:1, 130:1 to 150:1, 150:1 to 180:1, or 180:1 to 200:1. Within the above range, the dopant concentration of the second doped layer 190 is smaller than that of the first doped layer 110, thereby forming a dopant concentration gradient between the second doped layer 190 and the first doped layer 110. This creates an electric field pointing from the first doped layer 110 to the second doped layer 190, which can enhance the lateral transport capability of charge carriers in the substrate 100 from the second doped layer 190 to the first doped layer 110, further enhancing the transport of charge carriers. Furthermore, within the aforementioned range, the doping element concentration of the second doped layer 190 is not excessively higher than that of the first doped layer 110, thus preventing severe carrier recombination in the metal pattern region 10 due to excessive doping element concentration in the second doped layer 190.

[0080] In some embodiments, the ratio of the dopant concentration of the second doped layer 190 to the dopant concentration of the region of the substrate 100 other than the second doped layer 190 and the first doped layer 110 is 2:1 to 50:1, for example, it can be 2:1 to 5:1, 5:1 to 10:1, 10:1 to 20:1, 20:1 to 25:1, 25:1 to 30:1, 30:1 to 40:1, 40:1 to 45:1 or 45:1 to 50:1.

[0081] In some embodiments, the dopant concentration of the second doped layer 190 is 1 × 10⁻⁶. 16 atom / cm 3 ~1×10 20 atom / cm 3 For example, it can be 1×10 16 atom / cm 3 ~1.5×10 16 atom / cm 3 1.5×10 16 atom / cm 3 ~1×10 17 atom / cm 3 1×10 17 atom / cm 3 ~1.5×10 17 atom / cm 3 1.5×10 17 atom / cm 3 ~1×1018 atom / cm 3 1×10 18 atom / cm 3 ~1.25×10 18 atom / cm 3 1.25×10 18 atom / cm 3 ~1.5×10 18 atom / cm 3 1.5×10 18 atom / cm 3 ~1×10 19 atom / cm 3 1×10 19 atom / cm 3 ~1.25×10 19 atom / cm 3 Or 1.25×10 19 atom / cm 3 ~1×10 20 atom / cm 3 Within this range, the doping concentration of the second doped layer 190 is greater than that of the substrate 100, thereby enabling the formation of a high-low junction within the substrate 100. This creates a potential barrier effect on the carriers within the substrate 100 opposite the metal pattern region 10, reducing carrier recombination in the metal pattern region 10 and enhancing its carrier collection capability. Furthermore, within this range, the doping concentration of the second doped layer 190 is prevented from becoming excessively high, thus avoiding the formation of numerous carrier recombination centers in the metal pattern region 10 and the resulting severe carrier recombination problem.

[0082] In some embodiments, the thickness of the first doped layer 110 is greater than the thickness of the second doped layer 190. Here, thickness refers to the thickness of the first doped layer 110 along the direction from the doped conductive layer 130 to the substrate 100, and the thickness of the second doped layer 190. A larger thickness of the first doped layer 110 results in a deeper back electric field formed by the first doped layer 110 in the substrate 100. This allows charge carriers in the substrate 100, even those far from the first surface, to be transported to the first doped layer 110 via the back electric field, and then to the first portion 131 of the doped conductive layer 130, thereby enhancing the overall charge carrier transport capability in the substrate 100. A smaller thickness of the second doped conductive layer 130 results in fewer dopants with a high concentration in the second doped conductive layer 130, avoiding the problem of increased recombination losses at the contact portion between the first electrode 140 and the first portion 131 due to excessive dopant concentration in the second doped conductive layer 130.

[0083] In some embodiments, the ratio of the thickness of the first doped layer 110 to the thickness of the second doped layer 190 is 1.5:1 to 6:1, for example, it can be 1.5:1 to 2:1, 2:1 to 2.5:1, 2.5:1 to 3:1, 3:1 to 3.5:1, 3.5:1 to 4:1, 4:1 to 4.5:1, 4.5:1 to 5:1, 5:1 to 5.5:1, or 5.5:1 to 6:1. Within this range, the first doped layer 110 can effectively enhance carrier transport in the substrate 100 opposite to the non-metallic patterned region 11. And within the above range, the second doped layer 190 enhances carrier transport in the substrate 100 of the metallic patterned region 10 while minimizing carrier recombination in the metallic patterned region 10.

[0084] In some embodiments, in the direction from the metal pattern region 10 to the non-metal pattern region 11, the ratio of the width of the second doped layer 190 to the width of the first doped layer 110 is 5:1 to 20:1, for example, it can be 5:1 to 6:1, 6:1 to 7:1, 7:1 to 8:1, 8:1 to 9:1, 9:1 to 10:1, 10:1 to 11:1, 11:1 to 12:1, 12:1 to 13:1, 13:1 to 14:1, 14:1 to 15:1, 15:1 to 16:1, 16:1 to 17:1, 17:1 to 18:1, 18:1 to 19:1, or 19:1 to 20:1. Within this range, the width of the second doped layer 190 is larger than the width of the first doped layer 110, thereby giving the second doped layer 190 a larger effective range. This increases the number of charge carriers transported through the second doped layer 190, enhancing charge carrier transport. Since the dopant concentration of the first doped layer 110 is greater than that of the second doped layer 190, Auger recombination is more likely to occur on the first surface of the first doped layer 110. Therefore, setting the width of the first doped layer 110 to be smaller than the width of the second doped layer 190 avoids the problem of excessive charge carrier recombination centers on the first surface due to an excessively large area of ​​the first doped layer 110.

[0085] The tunneling layer 120 is located in the metal pattern region 10, and the first electrode 140 is located within the first portion 131 of the doped conductive layer 130, directly opposite the tunneling layer 120. The tunneling layer 120 and the doped conductive layer 130 form a passivation contact structure. The tunneling layer 120 can perform chemical passivation, and the doped conductive layer 130 can form band bending on the first surface to achieve selective carrier transport, thereby reducing the high recombination loss caused by the contact between the first electrode 140 and the first portion 131.

[0086] refer to Figure 2 , Figure 4 as well as Figure 5 In some embodiments, the tunneling layer 120 may be staggered with the first doped layer 110 along a first direction, which is the direction from the metal pattern region 10 to the non-metal pattern region 11. That is, the orthographic projection of the tunneling layer 120 on the first surface does not coincide with the top surface of the first doped layer 110. In this way, the tunneling layer 120 is not located on the top surface of the first doped layer 110, thereby enabling the top surface of the first doped layer 110 to directly contact the second portion 132 of the doped conductive layer 130, avoiding the problem of the tunneling layer 120 restricting the transport of charge carriers transported through the first doped layer 110.

[0087] It is worth noting that in some embodiments, regardless of whether the top surface of the first doped layer 110 coincides with a portion of the non-metallic pattern region 11 or the top surface of the first doped layer 110 coincides with the entire non-metallic pattern region 11, the tunneling layer 120 is arranged alternately with the first doped layer 110 along the first direction.

[0088] refer to Figure 6 In some embodiments, the tunneling layer 120 may also be located on a portion of the top surface of the first doped layer 110. For example, the tunneling layer 120 may extend to a portion of the non-metallic pattern region 11 and coincide with the side region along the first direction on the top surface of the first doped layer 110.

[0089] In some embodiments, the material of the tunneling layer 120 includes at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon, or polycrystalline silicon.

[0090] In some embodiments, the sidewalls of the tunneling layer 120 along the first direction are flush with the sidewalls of the first doped layer 110 along the first direction. This ensures that the area on the first surface, except for the top surface of the first doped layer 110, is covered by the tunneling layer 120, enhancing carrier transport in the first doped layer 110 while maintaining good passivation of the first surface. This avoids the problem of the tunneling layer 120 failing to chemically passivate the first surface corresponding to the gap due to the gap between its sidewalls in the first direction and those of the first doped layer 110, and also avoids the problem of impaired carrier transport in the substrate 100 corresponding to the gap because the substrate 100 also lacks the first doped layer 110.

[0091] In some embodiments, along the first direction, a portion of the sidewall of the second portion 132 contacts the sidewall of the tunneling layer 120. That is, along the first direction, the second portion 132 and the tunneling layer 120 may be arranged alternately.

[0092] In some embodiments, the number of first electrodes 140 of the solar cell is multiple, and the multiple first electrodes 140 are arranged at intervals along a first direction. The metallic patterned region 10 is the region on the first surface directly opposite the first electrode 140, and the non-metallic patterned region 11 can be the region on the first surface directly opposite the gap between two adjacent first electrodes 140. That is, on the first surface, the number of both metallic patterned regions 10 and non-metallic patterned regions 11 can be multiple, and the metallic patterned regions 10 and non-metallic patterned regions 11 are arranged alternately along the first direction. This results in the number of tunneling layers 120 being multiple, the multiple tunneling layers 120 being arranged at intervals along the first direction, and one tunneling layer 120 being located on a metallic patterned region 10. A second portion 132 is located between two adjacent tunneling layers 120, and the sidewall of the second portion 132 in the first direction is in contact with the sidewall of each of the two adjacent tunneling layers 120 facing the second portion 132. This ensures close contact between the second portion 132 and the tunneling layer 120, providing effective chemical passivation of the first surface and enhancing carrier transport. It prevents situations where gaps exist between the second portion 132 and the tunneling layer 120, resulting in the first surface corresponding to the gap not being covered by the tunneling layer 120, leading to severe carrier recombination at the gap, or where the first surface corresponding to the gap is not covered by the second portion 132, thus hindering carrier transport in the substrate 100 corresponding to the gap.

[0093] In some embodiments, the thickness of the first portion 131 is the same as the thickness of the second portion 132. It is understood that both the first portion 131 and the second portion 132 belong to the doped conductive layer 130, and the doped conductive layer 130 is a continuous film. The first portion 131 can be understood as the portion of the doped conductive layer 130 located at the top of the tunneling layer 120, and the second portion 132 can be understood as the portion of the doped conductive layer 130 located at the top surface of the first doped layer 110. Setting the first portion 131 and the second portion 132 to have the same thickness allows for the fabrication of both portions in a single step during the actual fabrication process, saving process steps.

[0094] It is understood that since the first portion 131 is located on the top surface of the tunneling layer 120 and the second portion 132 is located on the top surface of the first doped layer 110, that is, the second portion 132 is located on the first surface. If the thickness of the first portion 131 and the thickness of the second portion 132 are the same, then due to the certain thickness of the tunneling layer 120, there is a height difference between the surface of the second portion 132 away from the substrate 100 and the surface of the first portion 131 away from the substrate 100. In some embodiments, the height of the surface of the second portion 132 away from the substrate 100 relative to the second surface is lower than the height of the surface of the first portion 131 away from the substrate 100 relative to the second surface.

[0095] In some embodiments, the dopant element type of the doped conductive layer 130 is the same as that of the substrate 100, and the dopant element concentration of the doped conductive layer 130 is greater than that of the substrate 100, thereby enabling band bending to be formed on the first surface and achieving selective transport of charge carriers. In some embodiments, the dopant element concentration of the doped conductive layer 130 is greater than that of the first doped layer 110, thereby enabling band bending to be formed on the top surface of the first doped layer 110 and achieving selective transport of charge carriers transported via the first doped layer 110.

[0096] In some embodiments, the material of the doped conductive layer 130 includes at least one of amorphous silicon, polycrystalline silicon, and silicon carbide.

[0097] refer to Figure 2 In some embodiments, the solar cell further includes a first passivation layer 150, which covers the surface of the doped conductive layer 130 away from the substrate 100, and a first electrode 140 penetrates the first passivation layer 150 to make electrical contact with the doped conductive layer 130. The first passivation layer 150 can provide a good passivation effect on the first surface, for example, it can effectively chemically passivate the dangling bonds on the first surface, reduce the defect state density of the first surface, and suppress carrier recombination on the first surface.

[0098] In some embodiments, the first passivation layer 150 may be a single-layer structure. In some embodiments, the first passivation layer 150 may also be a multi-layer structure. In some embodiments, the material of the first passivation layer 150 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0099] In some embodiments, the substrate 100 has a second surface opposite to the first surface, and the height of the top surface of the first passivation layer 150 opposite to the first portion 131 relative to the second surface is higher than the height of the top surface of the first passivation layer 150 opposite to the second portion 132 relative to the second surface. It is understood that in some embodiments, the thickness of the first portion 131 is equal to the thickness of the second portion 132, such that the height of the surface of the second portion 132 away from the substrate 100 relative to the second surface is lower than the height of the surface of the first portion 131 away from the substrate 100 relative to the second surface. Based on this, in the actual process of fabricating the first passivation layer 150, since the first passivation layer 150 located on the surface of the first portion 131 and the surface of the second portion 132 are formed simultaneously in one step, the shape of the first passivation layer 150 will continue the morphology of the doped conductive layer 130. That is, in the first passivation layer 150, the height of the top surface of the first passivation layer 150 opposite to the first portion 131 relative to the second surface is higher than the height of the top surface of the first passivation layer 150 opposite to the second portion 132 relative to the second surface.

[0100] It is worth noting that the top surface of the first passivation layer 150 referred to here is the surface of the first passivation layer 150 that is away from the substrate 100.

[0101] In some embodiments, the system further includes an emitter 160 located within a substrate 100, with the top surface of the emitter 160 exposed and coinciding with a second surface. The doping type of the emitter 160 is opposite to that of the substrate 100, and the emitter 160 forms a PN junction with the substrate 100. In some embodiments, the material of the emitter 160 is the same as that of the substrate 100.

[0102] In some embodiments, the system further includes a second passivation layer 170, which is located on the surface of the emitter 160 away from the substrate 100. The second passivation layer 170 provides a good passivation effect on the second surface of the substrate 100, reduces the defect state density on the second surface, and effectively suppresses carrier recombination on the back side of the substrate 100. The second passivation layer 170 also provides a good anti-reflection effect, which helps to reduce the reflection of incident light and improve the utilization rate of incident light.

[0103] In some embodiments, the second passivation layer 170 may be a single-layer structure, while in other embodiments, the second passivation layer 170 may be a multi-layer structure. In some embodiments, the material of the second passivation layer 170 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0104] In some embodiments, the device further includes a second electrode 180, which is located on the second surface of the substrate 100 and penetrates the second passivation layer 170 to make electrical contact with the emitter 160.

[0105] In some embodiments, the first electrode 140 may be made of a metal, such as copper, silver, nickel, or aluminum. In some embodiments, the second electrode 180 may be made of a metal, such as copper, silver, nickel, or aluminum.

[0106] In the solar cell provided in the above embodiment, a first doped layer 110 is disposed within the substrate 100, and the top surface of the first doped layer 110 coincides with the non-metallic pattern region 11. The doping element concentration of the first doped layer 110 is greater than the doping element concentration in the substrate 100 excluding the first doped layer 110, so that the presence of the first doped layer 110 can form a back electric field. The second portion 132 of the doped conductive layer 130 is located on the top surface of the first doped layer 110, i.e., in contact with the top surface of the first doped layer 110. Under the potential of the back electric field, it can enhance the transport of charge carriers in the substrate 100 to the second portion 132, thereby enhancing the overall transport of charge carriers and improving the photoelectric conversion efficiency of the solar cell. In addition, the first electrode 140 is in electrical contact with the first portion 131, and a tunneling layer 120 is disposed on the metallic pattern region 10 in contact with the first portion 131 of the doped conductive layer 130, which can reduce the high recombination loss caused by the contact between the first electrode 140 and the first portion 131. The first doped layer 110 on the non-metallic patterned region 11 is in direct contact with the second part 132, which can avoid the obstruction of carrier transport caused by the tunneling layer 120, further improve the carrier transport, and further improve the photoelectric conversion efficiency of the solar cell.

[0107] Accordingly, another aspect of the embodiments of this application also provides a photovoltaic module, with reference to... Figure 7 The photovoltaic module includes: a cell string, which is formed by connecting multiple solar cells 101 provided in the above embodiments; an encapsulation layer 102 for covering the surface of the cell string; and a cover plate 103 for covering the surface of the encapsulation layer 102 away from the cell string. The solar cells 101 are electrically connected in the form of a whole cell or multiple segments to form multiple cell strings, and the multiple cell strings are electrically connected in series and / or parallel.

[0108] Specifically, in some embodiments, multiple battery strings can be electrically connected via conductive strips 104. The encapsulation layer 102 covers the surface and back of the substrate 100 of the solar cell 101. Specifically, the encapsulation layer 102 can be an organic encapsulation film such as ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene copolymer elastomer (POE) film, polyethylene terephthalate (PET) film, or polyvinyl butyral (PVB). In some embodiments, the cover plate 103 can be a light-transmitting cover plate such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate 103 facing the encapsulation layer 102 can be an uneven surface, thereby increasing the utilization rate of incident light.

[0109] Accordingly, this application also provides a method for preparing a solar cell, which can be used to prepare the solar cell provided in the above embodiments. The method for preparing the solar cell includes:

[0110] refer to Figure 8 A substrate 100 is provided, the substrate 100 having a first surface having a metallic patterned region 10 and a non-metallic patterned region 11.

[0111] The substrate 100 is used to receive incident light and generate photogenerated carriers. The substrate 100 has a second surface opposite to the first surface. Both the first and second surfaces of the substrate 100 can be used to receive incident light or reflect light. In some embodiments, the substrate 100 can be a silicon substrate, and the material of the substrate 100 can include at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0112] In some embodiments, the substrate 100 may be an N-type semiconductor substrate 100, and the doping element of the substrate 100 may be any one of phosphorus, arsenic or antimony.

[0113] In some embodiments, the substrate 100 may also be a P-type semiconductor substrate 100, and the doping element of the substrate 100 may be any one of boron, gallium, or indium. The substrate 100 has a second surface opposite to the first surface, and both the first and second surfaces can be used to receive incident light or reflect light. In some embodiments, the second surface of the substrate 100 may be configured as a pyramidal textured surface to reduce the reflectivity of the second surface of the substrate 100 to incident light, thereby increasing the light absorption and utilization rate.

[0114] In some embodiments, the substrate 100 may be subjected to a doping process, such as an ion implantation process, to diffuse dopant elements into the substrate 100.

[0115] In some embodiments, the formed solar cell is a TOPCON cell.

[0116] refer to Figure 9 In some embodiments, the method for fabricating a solar cell includes: forming an emitter 160 in a substrate 100, wherein the top surface of the emitter 160 is exposed in the substrate 100 and coincides with a second surface. The doping type of the emitter 160 is opposite to that of the substrate 100, and a PN junction is formed with the substrate 100.

[0117] In some embodiments, the method of forming the emitter 160 may include performing a diffusion process on a second surface of the substrate 100 to diffuse a dopant element into a portion of the substrate 100 to form the emitter 160. In some embodiments, the diffusion process may be an ion implantation process.

[0118] In some embodiments, when the substrate 100 is an N-type substrate, the second surface of the substrate 100 may be subjected to boron diffusion treatment, and when the substrate 100 is a P-type substrate, the second surface of the substrate 100 may be subjected to phosphorus diffusion treatment.

[0119] refer to Figure 10 After the emitter 160 is formed, an initial tunneling layer 13 is formed on the first surface in a direction away from the substrate 100.

[0120] In some embodiments, an initial tunneling layer 13 may be formed on the first surface using a deposition process, which may include either atomic layer deposition or chemical vapor deposition.

[0121] In some embodiments, the material of the initial tunneling layer 13 may include at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon, or polycrystalline silicon.

[0122] refer to Figures 11 to 13 The initial tunneling layer 13 is patterned to form the tunneling layer 120. In some embodiments, the method of patterning the initial tunneling layer 13 may include:

[0123] refer to Figure 11 A mask layer 14 is formed on the surface of the initial tunneling layer 13 away from the substrate 100. In some embodiments, a deposition process, such as atomic layer deposition, may be used to form the mask layer 14 on the surface of the initial tunneling layer 13. In some embodiments, the material of the mask layer 14 may be silicon oxide.

[0124] refer to Figure 12 The mask layer 14 is patterned to form a first opening 20 in the mask layer 14, the first opening 20 exposing a portion of the initial tunneling layer 13. In some embodiments, the process of patterning the mask layer 14 may include a photolithography process.

[0125] refer to Figure 13 The initial tunneling layer 13 is etched along the first opening 20 until the first surface is exposed, so that a first groove 21 is formed in the initial tunneling layer 13, and the remaining first groove 21 exposes part of the first surface, and the remaining initial tunneling layer 13 forms a tunneling layer 120. That is, there are multiple tunneling layers 120, and the multiple tunneling layers 120 are arranged at intervals along the same direction.

[0126] refer to Figure 14 The method for preparing a solar cell further includes forming a first doped layer 110 in a substrate 100, wherein the doping element concentration of the first doped layer 110 is greater than the doping element concentration in the region of the substrate 100 excluding the first doped layer 110.

[0127] In some embodiments, the first doped layer 110 may be formed after the tunneling layer 120 is formed.

[0128] In some embodiments, the method for forming the first doped layer 110 may be as follows: after forming the tunneling layer 120, the mask layer 14 located on the surface of the tunneling layer 120 away from the substrate 100 is not removed temporarily, so that the mask layer 14 can protect the surface of the tunneling layer 120 during the subsequent doping process of the substrate 100; a doping process is performed on the first surface exposed by the first groove 21 to implant dopant elements into the first surface exposed by the first groove 21. In some embodiments, the doping process may be an ion implantation process. In some embodiments, the type of dopant element implanted into the first surface exposed by the first groove 21 is the same as the type of dopant element in the substrate 100. After implanting dopant elements into the substrate 100, the substrate 100 is annealed to form the first doped layer 110.

[0129] In some embodiments, the dopant concentration of the first doped layer 110 can be 1 × 10⁻⁶. 18 atom / cm 3 ~5×10 20 atom / cm 3 For example, it can be 1×10 18 atom / cm 3 ~1.5×10 18 atom / cm 3 1.5×10 18 atom / cm 3 ~1×10 19 atom / cm 3 1×10 19 atom / cm 3 ~1.5×10 19 atom / cm 3 Or 1.5 × 10 19 atom / cm 3 ~1×10 20 atom / cm 3 The doping concentration in the region of substrate 100 other than the first doped layer 110 can be 1×10⁻⁶. 15 atom / cm 3 ~1×10 18 atom / cm 3 For example, it can be 1×10 15 atom / cm 3 ~1.5×10 15 atom / cm 3 1.5×10 15 atom / cm 3 ~1×10 16 atom / cm 3 1×10 16atom / cm 3 ~1.5×10 16 atom / cm 3 1.5×10 16 atom / cm 3 ~1×10 17 atom / cm 3 Or 1×10 17 atom / cm 3 ~1×10 18 atom / cm 3 .

[0130] In some embodiments, the depth of diffusion of the dopant element into the substrate 100 can be controlled by controlling the ion implantation process time, for example, from 3 to 5 minutes, thereby controlling the thickness of the first doped layer 110 formed.

[0131] It is easy to see that, due to the re-implantation of doping elements into the substrate 100, the doping element concentration of the substrate 100 after the second ion implantation is relatively large, while the doping element concentration after only one ion implantation is relatively small, thus forming a heavily doped first doped layer 110.

[0132] Since the first groove 21 only exposes part of the first surface, and the first surface not exposed by the first groove 21 has not undergone a doping process, the first doped layer 110 is not formed in the substrate 100 covered by the tunneling layer 120.

[0133] After the first doped layer 110 is formed, the mask layer 14 is removed. In some embodiments, the mask layer 14 can be removed by an acid washing process, for example, by using HF solution or HCl solution to clean the mask layer 14 and remove it.

[0134] refer to Figure 15 After removing the mask layer 14, a doped conductive layer 130 is formed on the surface of the tunneling layer 120 and in the first groove 21 using a deposition process. The doped conductive layer 130 fills the first groove 21. The doped conductive layer 130 located on the surface of the tunneling layer 120 can be a first part 131 of the doped conductive layer 130, and the doped conductive layer 130 located in the first groove 21 can be a second part 132 of the doped conductive layer 130. The second part 132 is in contact with the top surface of the first doped layer 110.

[0135] The method of forming the doped conductive layer 130 may include:

[0136] A dopable layer is formed on the surface of the tunneling layer 120 and in the first groove 21 using a deposition process. During the deposition process, a dopant element is implanted into the dopable layer using an in-situ deposition process to form a pristine doped conductive layer. The deposition process and the dopant element implantation process are performed simultaneously, which can save process time and improve process efficiency.

[0137] After implanting dopant elements into the dopable layer, the original doped conductive layer is annealed to form the doped conductive layer 130. The annealing process activates the dopant elements in the original doped conductive layer, forming activated dopant elements.

[0138] In some embodiments, the dopant type implanted into the dopant layer is the same as the dopant type of the substrate 100.

[0139] In some embodiments, the material of the doped layer may be any one of amorphous silicon, polycrystalline silicon, microcrystalline silicon, or silicon carbide.

[0140] It is understandable that, since the dopable layer is formed in the same deposition process, the surface of the dopable layer located in the first groove 21 is recessed towards the first surface compared to the surface of the dopable layer located in the tunneling layer 120, so that in the finally formed doped conductive layer 130, the height of the surface of the second part 132 away from the substrate 100 relative to the second surface is lower than the height of the surface of the first part 131 away from the substrate 100 relative to the second surface.

[0141] refer to Figures 16 to 18 In some embodiments, the method for fabricating a solar cell further includes: forming a second doped layer 190 in a substrate 100. Alternatively, an initial first doped layer 110 may be formed after forming a tunneling layer 120. In the step of forming a doped conductive layer 130, the second doped layer 190 may be formed and the initial first doped layer 110 may be converted into a first doped layer 110.

[0142] refer to Figures 16 to 18 In some embodiments, the methods for forming the first doped layer 110 and the second doped layer 190 include:

[0143] refer to Figure 16 After the tunneling layer 120 is formed, the first surface exposed by the first groove 21 is subjected to a doping process to form an initial first doped layer 15 in the substrate.

[0144] In some embodiments, the method for forming the initial first doped layer 15 may refer to the method for forming the first doped conductive layer 130 described above, except that the doping element concentration of the initial first doped layer 15 is less than the doping element concentration of the first doped layer 110.

[0145] refer to Figure 17A dopable layer 16 is formed on the surface of the tunneling layer 120. Then, the dopable layer is subjected to a doping process to transform it into a doped conductive layer. During the process of implanting dopants into the dopable layer 16, the concentration of the implanted dopants is controlled so that some dopants diffuse from the first surface to the initial first doped layer 15 in the substrate 100 and to the region other than the initial first doped layer 15.

[0146] refer to Figure 18 Annealing is performed on the original doped conductive layer and the substrate 100. After annealing, the original doped conductive layer is transformed into a doped conductive layer 130, the initial first doped layer 15 is transformed into a first doped layer 110, and the area other than the initial first doped layer 15 is transformed into a second doped layer 190.

[0147] Understandably, since the initial first doped layer 15 has already undergone two ion implantations, during the implantation of dopant elements into the dopable layer 16, the initial first doped layer 15 is ion implanted again. Compared to the second doped layer 190, which only underwent two ion implantations (the first during the formation of the substrate 100, and the second during the implantation of dopant elements into the dopable layer 16), the dopant concentration of the second doped layer 190 is lower than that of the first doped layer 110, but higher than the dopant concentration of all other dopant elements in the substrate 100 besides the first doped layer 110 and the second doped layer 190. The thickness of the second doped layer 190 is less than that of the first doped layer 110.

[0148] In some embodiments, during the implantation of dopant elements into the dopable layer 16, the concentration of the implanted dopant elements is controlled to be 1.25 × 10⁻⁶. 16 atom / cm 3 ~1×10 20 atom / cm 3 For example, it can be 1.25 × 10 16 atom / cm 3 ~1×10 17 atom / cm 3 1×10 17 atom / cm 3 ~5×10 17 atom / cm 3 5×10 17 atom / cm 3 ~1×10 18 atom / cm 3 1×10 18 atom / cm 3 ~1.5×10 18 atom / cm 3 1.5×1018 atom / cm 3 ~1×10 19 atom / cm 3 Or 1×10 19 atom / cm 3 ~1×10 20 atom / cm 3 Within this range, on the one hand, it is possible to form a doped conductive layer 130 that meets the desired requirements; on the other hand, it is sufficient to diffuse some of the doped elements into the substrate 100 to form a first doped layer 110 and a second doped layer 190.

[0149] refer to Figure 19 In some embodiments, the method for fabricating a solar cell further includes forming a first passivation layer 150 on the surface of the doped conductive layer 130 away from the substrate 100. In some embodiments, the first passivation layer 150 may be a single-layer structure. In some embodiments, the first passivation layer 150 may also be a multilayer structure.

[0150] In some embodiments, the first passivation layer 150 is a single-layer structure, and the material of the first passivation layer 150 may be one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride. In some embodiments, the first passivation layer 150 is a multilayer structure, and the material of the first passivation layer 150 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0151] In some embodiments, the method of forming the first passivation layer 150 may include forming the first passivation layer 150 on the surface of the doped conductive layer 130 using a PECVD (Plasma Enhanced Chemical Vapor Deposition) method.

[0152] In some embodiments, the method further includes forming a second passivation layer 170 on the surface of the emitter 160, wherein the second passivation layer 170 can provide a better passivation effect. In some embodiments, the second passivation layer 170 can be a single-layer structure. In some embodiments, the second passivation layer 170 can also be a multi-layer structure.

[0153] In some embodiments, the second passivation layer 170 is a single-layer structure, and the material of the second passivation layer 170 may be one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride. In some embodiments, the second passivation layer 170 is a multilayer structure, and the material of the second passivation layer 170 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0154] In some embodiments, a second passivation layer 170 may be formed on the surface of the emitter 160 using a PECVD process.

[0155] refer to Figure 2 In some embodiments, the method further includes forming a first electrode 140, which penetrates the first passivation layer 150 and makes electrical contact with the doped conductive layer 130.

[0156] In some embodiments, the method of forming the first electrode 140 includes: printing a conductive paste on the surface of a first passivation layer 150 opposite to the metal pattern region 10, for example, using a screen printing process. The conductive paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel. A sintering process is then performed on the conductive paste on the surface of the first passivation layer 150, causing the conductive paste to penetrate into the first passivation layer 150 and the partially doped conductive layer 130, forming an electrical contact with the doped conductive layer 130.

[0157] In some embodiments, the method further includes forming a second electrode 180, the second electrode 180 penetrating the second passivation layer 170 and making electrical contact with the emitter 160. In some embodiments, the process for forming the second electrode 180 may be the same as the process for forming the first electrode 140, and reference may be made to the above description of the method for forming the first electrode 140.

[0158] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

[0159] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes can be made in form and detail without departing from the spirit and scope of this application. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: The substrate has a first surface, the first surface having a metallic patterned area and a non-metallic patterned area; A first doped layer is located within the substrate, the substrate exposes the top surface of the first doped layer, the top surface of the first doped layer coincides with at least a portion of the non-metallic pattern region, and the doping element concentration of the first doped layer is greater than the doping element concentration of the region within the substrate other than the first doped layer. A tunneling layer covers the area of ​​the metal pattern; A doped conductive layer includes a first portion and a second portion, wherein the first portion is located on the surface of the tunneling layer away from the substrate, and the second portion is located on the top surface of the first doped layer; The first electrode is directly opposite the metal pattern area, and the first electrode is in electrical contact with the first portion; The tunneling layer and the first doped layer are arranged alternately along a first direction, where the first direction is the direction from the metal pattern region to the non-metal pattern region. The concentration of doped elements in the doped conductive layer is greater than the concentration of doped elements in the first doped layer.

2. The solar cell according to claim 1, characterized in that, The top surface of the first doped layer coincides with a portion of the non-metallic patterned region.

3. The solar cell according to claim 1, characterized in that, The top surface of the first doped layer coincides with the entire non-metallic pattern region.

4. The solar cell according to claim 1, characterized in that, The sidewall of the tunneling layer along the first direction is flush with the sidewall of the first doped layer along the first direction.

5. The solar cell according to claim 1, characterized in that, Along the first direction, a portion of the sidewall of the second part contacts the sidewall of the tunneling layer.

6. The solar cell according to claim 5, characterized in that, The thickness of the first part is the same as the thickness of the second part.

7. The solar cell according to claim 1, characterized in that, The ratio of the doping element concentration of the first doped layer to the doping element concentration of the region of the substrate other than the first doped layer is 10:1 to 1000:

1.

8. The solar cell according to claim 7, characterized in that, The doping concentration of the first doped layer is 1×10 18 atom / cm 3 ~5×10 20 atom / cm 3 .

9. The solar cell according to claim 1, characterized in that, Also includes: A second doped layer is located within the substrate. The second doped layer and the first doped layer are arranged alternately, and the top surface of the second doped layer is in contact with the surface of the tunneling layer facing the substrate. The doping element concentration of the second doped layer is less than that of the first doped layer, but greater than that of the doping element concentration in the region of the substrate excluding the second doped layer and the first doped layer.

10. The solar cell according to claim 9, characterized in that, The ratio of the doping element concentration of the first doped layer to the doping element concentration of the second doped layer is 5:1 to 200:

1.

11. The solar cell according to claim 10, characterized in that, The doping concentration of the second doped layer is 1×10 16 atom / cm 3 ~1×10 20 atom / cm 3 .

12. The solar cell according to claim 9, characterized in that, The thickness of the first doped layer is greater than the thickness of the second doped layer.

13. The solar cell according to claim 12, characterized in that, The ratio of the thickness of the first doped layer to the thickness of the second doped layer is 1.5:1 to 6:

1.

14. The solar cell according to claim 9 or 12, characterized in that, In the direction from the metal pattern region to the non-metal pattern region, the ratio of the width of the second doped layer to the width of the first doped layer is 5:1 to 20:

1.

15. The solar cell according to claim 1, characterized in that, Also includes: A first passivation layer covers the surface of the doped conductive layer away from the substrate, and the first electrode penetrates the first passivation layer to make electrical contact with the doped conductive layer.

16. The solar cell according to claim 15, characterized in that, The substrate has a second surface opposite to the first surface, and the height of the top surface of the first passivation layer opposite the first portion relative to the second surface is higher than the height of the top surface of the first passivation layer opposite the second portion relative to the second surface.

17. The solar cell according to claim 1, characterized in that, The material of the doped conductive layer includes at least one of amorphous silicon, polycrystalline silicon, and silicon carbide.

18. The solar cell according to claim 1, characterized in that, The material of the tunneling layer includes at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon, or polycrystalline silicon.

19. A photovoltaic module, characterized in that, include: A battery string, wherein the battery string is formed by connecting a plurality of solar cells as described in any one of claims 1 to 18; Encapsulation layer, the encapsulation layer being used to cover the surface of the battery string; A cover plate for covering the surface of the encapsulation layer away from the battery string.

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