Solar cell and its manufacturing method, photovoltaic module

Abstract

To provide, in the field of solar cells, particularly a solar cell, a method for preparing the same, and a photovoltaic module.SOLUTION: A solar cell comprises: a substrate having a first surface; a tunneling layer formed on the first surface; a first doped conductive layer formed on the tunneling layer; a second doped conductive layer formed on the first doped conductive layer, where the second doped conductive layer comprises a plurality of first portions and a plurality of second portions, where a doping element concentration of the first doped conductive layer is lower than a doping element concentration of the first portions, and the doping element concentration of the first portions is lower than a doping element concentration of the second portions; and a plurality of first electrodes each extending along a preset direction, and each electrically contacting corresponding one of the second portions. Embodiments of the present application are advantageous in improving the photoelectric conversion performance of the solar cell.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] TECHNICAL FIELD The present application relates to the field of solar cells, and more particularly to solar cells and methods for fabricating same, and photovoltaic modules. [Background technology]

[0002] Solar cells have good photoelectric conversion ability, and in order to suppress the carrier recombination on the substrate surface in the solar cell and improve the passivation performance for the substrate, a tunnel layer and a doped conductive layer are currently fabricated on the substrate surface, among which the tunnel layer has good chemical passivation effect and the doped conductive layer has good field passivation effect.

[0003] The doping conductive layer is doped with a certain concentration of doping element, which can form a sufficiently high potential barrier between the doping conductive layer and the substrate. This potential barrier makes it easier for the majority carriers in the substrate to tunnel through the tunnel layer, and the minority carriers in the substrate to escape from the interface, reducing the concentration of minority carriers and realizing the selective transport of carriers. Therefore, the doping element concentration in the doping conductive layer plays an important role in the performance of the doping conductive layer, which may affect the performance of the entire solar cell.

[0004] However, the photoelectric conversion performance of current solar cells remains poor. Summary of the Invention [Problem to be solved by the invention]

[0005] In the embodiments of the present application, a solar cell, a manufacturing method thereof, and a photovoltaic module are provided, which are advantageous in improving at least the photoelectric conversion efficiency of the solar cell. [Means for solving the problem]

[0006] In an embodiment of the present application, a solar cell is provided, the solar cell including a substrate having a first surface, a tunnel layer formed on the first surface, a first doped conductive layer formed on a surface of the tunnel layer remote from the substrate, and a second doped conductive layer formed on a side of the first doped conductive layer remote from the substrate, the second doped conductive layer including a plurality of first portions and a plurality of second portions, the first portions and the second portions being alternately arranged along a predetermined direction and a direction perpendicular to a thickness direction of the second doped conductive layer, and each of the first portions and each of the second portions being a predetermined a second doped conductive layer extending along a predetermined direction, where a doping element concentration of the first doped conductive layer is smaller than a doping element concentration of the first portion and a doping element concentration of the first portion is smaller than a doping element concentration of the second portion, where the predetermined direction is parallel to the first surface; and a plurality of first electrodes, each of the plurality of first electrodes extending along the predetermined direction, each of the first electrodes and each of the second portions in a one-to-one correspondence, and one of the first electrodes being in electrical contact with a corresponding one of the second portions.

[0007] In addition, the ratio of the doping element concentration in the first portion to the doping element concentration in the second portion is 1:50 to 3:4.

[0008] Moreover, the ratio of the doping element concentration in the first doped conductive layer to the doping element concentration in the second portion is 1:100 to 1:2.

[0009] The first doped conductive layer further includes a plurality of third portions and a plurality of fourth portions, the third portions and the fourth portions being alternately arranged along a predetermined direction and a direction perpendicular to a thickness direction of the second doped conductive layer, wherein the predetermined direction is parallel to the first surface, the third portions and the fourth portions all extend along the predetermined direction, one of the third portions faces one of the first portions, one of the fourth portions faces one of the second portions, and a doping element concentration of the third portions is smaller than a doping element concentration of the fourth portions.

[0010] In addition, when the doping element type of the first doped conductive layer is N-type, the ratio of the doping element concentration of the third portion to the doping element concentration of the fourth portion is 1:30 to 5:6, and when the doping element type of the first doped conductive layer is P-type, the ratio of the doping element concentration of the third portion to the doping element concentration of the fourth portion is 1:100 to 2:3.

[0011] Moreover, the ratio of the doping element concentration in the fourth portion to the doping element concentration in the second portion is 1:10 to 5:6.

[0012] The doping element type of the first doped conductive layer and the second doped conductive layer is P-type, and the doping element concentration of the first portion is 5×10 18 atom / cm 3 ~5×10 19 atom / cm 3 and the doping element concentration of the second portion is 5×10 19 atom / cm 3 ~3×10 20 atom / cm 3 and the doping element concentration of the first doped conductive layer is 1×10 18 atom / cm 3 ~4.5×10 19 atom / cm 3 It is.

[0013] The doping element type of the first doped conductive layer and the second doped conductive layer is N-type, and the doping element concentration of the first portion is 1×10 20 atom / cm 3 ~2×10 21 atom / cm 3 and the doping element concentration of the second portion is 2×10 20 atom / cm 3 ~5×10 21 atom / cm 3 and the doping element concentration of the first doped conductive layer is 5×10 19 atom / cm3 ~5×10 20 atom / cm 3 It is.

[0014] The semiconductor device further includes a blocking layer, the blocking layer being located between the first doped conductive layer and the second doped conductive layer, the surface of the blocking layer facing the substrate being in contact with the surface of the first doped conductive layer away from the substrate, and the surface of the blocking layer facing the substrate being in contact with the surface of the second doped conductive layer away from the substrate.

[0015] Additionally, the surface of the barrier layer facing away from the substrate is in contact with each of the second portions, and the orthogonal projection of the barrier layer on the first surface overlaps with the orthogonal projection of the second portions on the first surface.

[0016] Furthermore, the surface of the blocking layer away from the substrate is in contact with each of the first portions and each of the second portions, and the orthogonal projection of the blocking layer on the first surface overlaps with the orthogonal projection of each of the first portions on the first surface and the orthogonal projection of each of the second portions on the first surface.

[0017] Additionally, the material of the blocking layer includes at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0018] Also, the material of the first doped conductive layer includes at least one of amorphous silicon, polycrystalline silicon, or silicon carbide, and the material of the second doped conductive layer includes at least one of amorphous silicon, polycrystalline silicon, or silicon carbide.

[0019] Further, the first doped conductive layer is made of first polycrystalline silicon, the first portion is made of second polycrystalline silicon, the second portion is made of third polycrystalline silicon, and an average crystal grain size of the first polycrystalline silicon is larger than an average crystal grain size of the second polycrystalline silicon and is also larger than an average crystal grain size of the third polycrystalline silicon.

[0020] Furthermore, a third portion is made of fourth polycrystalline silicon, the fourth portion is made of fifth polycrystalline silicon, the first portion is made of second polycrystalline silicon, and the second portion is made of third polycrystalline silicon, wherein an average crystal grain size of the fourth polycrystalline silicon is larger than an average crystal grain size of the fifth polycrystalline silicon, an average crystal grain size of the fifth polycrystalline silicon is larger than an average crystal grain size of the third polycrystalline silicon, and an average crystal grain size of the second polycrystalline silicon is larger than an average crystal grain size of the third polycrystalline silicon.

[0021] In addition, the doping element type of the substrate is an N-type doping element, and the second portion includes a main body portion doped with an N-type doping element and an inversion doping portion located within the main body portion and doped with a P-type doping element, and a volume ratio of the inversion doping portion within the main body portion is less than 1 / 2.

[0022] Moreover, the ratio of the thickness of the first doped conductive layer to the thickness of the second doped conductive layer is 2:1 to 1:12.

[0023] In response to the above, an embodiment of the present application further provides a photovoltaic module, the photovoltaic module including at least one cell string formed by connecting a plurality of solar cells as described in any one of the above items, at least one encapsulation layer for covering the at least one cell string, and at least one cover plate for covering the at least one encapsulation layer.

[0024] In response to the above, an embodiment of the present application further provides a method for manufacturing a solar cell, the method for manufacturing the solar cell includes the steps of: providing a substrate having a first surface; forming a tunnel layer on the first surface; forming a first doped conductive layer on the tunnel layer; and forming a second doped conductive layer on the first doped conductive layer, the second doped conductive layer including a plurality of first portions and a plurality of second portions, the first portions and the second portions being alternately arranged along a predetermined direction and a direction perpendicular to a thickness direction of the second doped conductive layer, and each of the first portions and each of the second portions being alternately arranged along a predetermined direction and a direction perpendicular to a thickness direction of the second doped conductive layer, the first doped conductive layer extends along a preset direction, wherein a doping element concentration of the first doped conductive layer is less than a doping element concentration of the first portion, and the doping element concentration of the first portion is less than a doping element concentration of the second portion, wherein the preset direction is parallel to the first surface; and forming a plurality of first electrodes, each of the plurality of first electrodes extending along a preset direction, each of the first electrodes corresponding to each of the second portions in a one-to-one relationship, and one of the first electrodes being in electrical contact with a corresponding one of the second portions.

[0025] Also, before the step of forming the second doped conductive layer, the method further includes forming a blocking layer located on a surface of the first doped conductive layer away from the substrate, the material of the blocking layer including at least one of silicon oxide, silicon nitride, silicon oxynitride or silicon carbide.

[0026] Also, the method of forming the first doped conductive layer, the second doped conductive layer, and the blocking layer includes: forming a first intrinsic silicon layer on a surface of the tunnel layer; forming the blocking layer on the surface of the first intrinsic silicon layer; forming a second intrinsic silicon layer on the surface of the blocking layer; depositing a doping source containing a first doping element on a surface of the second intrinsic silicon layer remote from the substrate; and simultaneously depositing the doping source, by flowing oxygen gas, converting a part of the second intrinsic silicon layer into a glass layer, the glass layer being silicon oxide containing the first doping element; a second doping process for a portion of the glass layer, the first doping element in the glass layer being diffused into the initial second doped conductive layer along a direction perpendicular to the first surface, converting the portion of the initial second doped conductive layer into a second portion of the second doped conductive layer, and a remaining portion of the initial second doped conductive layer forming a first portion.

[0027] The second doping process includes a laser process, in which the laser wavelength used in the laser process is 300 nm to 532 nm, the laser frequency is 120 kHz to 1500 kHz, the scan rate is 1000 mm / s to 40000 mm / s, and the laser energy is 0.1 J / cm 2 ~1.5J / cm 2 It is. Effect of the Invention

[0028] The technical solutions provided in the embodiments of the present application have at least the following advantages:

[0029] In the technical proposal of the solar cell provided in the embodiments of the present application, the first doped conductive layer is closer to the substrate than the second doped conductive layer, and the doping element concentration of the first doped conductive layer is lower than the doping element concentration of the second doped conductive layer, thereby reducing the probability of impurity elements in the first doped conductive layer penetrating into the tunnel layer, ensuring good tunneling performance of the tunnel layer for carriers in the substrate, increasing the number of carriers tunneled into the first doped conductive layer and the second doped conductive layer, improving the carrier collection ability of the first electrode, increasing the open circuit voltage and short circuit current of the solar cell, and improving the photoelectric conversion performance of the solar cell.

[0030] The second doped conductive layer includes a first portion and a second portion, and the doping element concentrations of the first portion and the second portion are both greater than that of the first doped conductive layer, i.e., in a direction perpendicular to the first surface, the first portion and the second portion both form a concentration gradient with the first doped conductive layer, which is helpful in driving the longitudinal transport of carriers, reinforce the transport of carriers in the substrate to the second doped conductive layer, and improve the carrier collection ability of the first electrode, thereby improving the photoelectric conversion performance of the solar cell.

[0031] The doping element concentration in the first portion is smaller than the doping element concentration in the second portion, i.e., a concentration gradient is also formed between the first portion and the second portion in the direction perpendicular to the first surface, which helps to reinforce the lateral transport of carriers in the second doped conductive layer and further improves the carrier collection ability of the first electrode, thereby improving the photoelectric conversion performance of the solar cell.

[0032] Because the doping element concentration in the second part is relatively high, good ohmic contact is formed between the second part and the first electrode, and the contact recombination loss between the first electrode and the second part is reduced; because the doping element concentration in the first part is relatively small, the parasitic absorption of incident light in the first part that is not in contact with the first electrode is reduced, the utilization rate of the substrate for incident light can be increased, and the photoelectric conversion performance of the solar cell can be improved. [Brief description of the drawings]

[0033] One or more embodiments are illustratively described in the figures in the corresponding attached drawings, and these illustrative descriptions are not intended to limit the embodiments, and unless otherwise specified, the figures in the attached drawings do not form a proportional limit. In order to more clearly describe the embodiments of the present disclosure or the technical solutions in the prior art, the following will briefly describe the drawings that need to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and those skilled in the art can obtain other drawings based on these drawings without paying creative labor. [Figure 1] FIG. 1 is a diagram showing a cross-sectional structure of a solar cell. [Diagram 2] FIG. 2 is a diagram showing a top view structure of a solar cell provided according to an embodiment of the present application. [Diagram 3] FIG. 3 is a diagram showing a cross-sectional structure of a first solar cell provided by an embodiment of the present application. [Figure 4] FIG. 4 is a diagram showing a cross-sectional structure of a second solar cell provided by an embodiment of the present application. [Diagram 5] FIG. 5 is a diagram showing a top view configuration of another solar cell provided according to an embodiment of the present application. [Figure 6] FIG. 6 is a diagram showing a cross-sectional structure of a third solar cell provided according to an embodiment of the present application. [Figure 7] FIG. 7 is a diagram showing a cross-sectional structure of a fourth solar cell provided according to an embodiment of the present application. [Figure 8] FIG. 8 is a diagram showing a cross-sectional structure of a fifth solar cell provided according to an embodiment of the present application. [Figure 9] FIG. 9 is a diagram showing a cross-sectional structure of a sixth solar cell provided according to an embodiment of the present application. [Figure 10] FIG. 10 is a diagram showing a cross-sectional structure of a seventh solar cell provided according to an embodiment of the present application. [Figure 11]FIG. 11 is a diagram showing a cross-sectional structure of a photovoltaic module provided according to another embodiment of the present application. [Figure 12] FIG. 12 is a diagram showing a cross-sectional structure corresponding to a step of providing a substrate in a method for manufacturing a solar cell provided according to an embodiment of the present application. [Figure 13] FIG. 13 is a diagram showing a cross-sectional structure corresponding to a step of forming an emitter in a method for manufacturing a solar cell provided according to an embodiment of the present application. [Figure 14] FIG. 14 is a diagram showing a cross-sectional structure corresponding to a step of forming a tunnel layer in a method for manufacturing a solar cell provided according to an embodiment of the present application. [Figure 15] FIG. 15 is a cross-sectional view showing a step of forming an intrinsic silicon layer in a method for manufacturing a solar cell according to an embodiment of the present application. [Figure 16] FIG. 16 is a diagram showing a cross-sectional structure corresponding to a step of forming a glass layer in a method for manufacturing a solar cell provided according to an embodiment of the present application. [Figure 17] FIG. 17 is a diagram showing a cross-sectional structure corresponding to a step of forming an initial silicon doped layer in a method for manufacturing a solar cell provided by an embodiment of the present application. [Figure 18] FIG. 18 is a cross-sectional view illustrating a step of forming a first doped conductive layer and a silicon doped layer in another solar cell manufacturing method provided by an embodiment of the present application. [Figure 19] FIG. 19 is a diagram showing a cross-sectional structure corresponding to a step of forming a first portion and a second portion in a method for manufacturing a solar cell provided by an embodiment of the present application. [Figure 20] FIG. 20 is a diagram showing a cross-sectional structure corresponding to a step of forming a first intrinsic silicon layer in another method for manufacturing a solar cell provided by an embodiment of the present application. [Figure 21] FIG. 21 is a cross-sectional view illustrating a step of forming a blocking layer and a second intrinsic silicon layer in another solar cell manufacturing method provided by an embodiment of the present application. [Figure 22] FIG. 22 is a diagram showing a cross-sectional structure corresponding to a step of forming a glass layer in another method for manufacturing a solar cell provided by an embodiment of the present application. [Diagram 23] FIG. 23 is a cross-sectional view showing a step of forming a first doped conductive layer and an initial second doped conductive layer in another solar cell manufacturing method provided by an embodiment of the present application. [Figure 24] FIG. 24 is a diagram showing a cross-sectional structure corresponding to a step of forming a mask layer in another method for manufacturing a solar cell provided by an embodiment of the present application. [Diagram 25] FIG. 25 is a diagram showing a cross-sectional structure corresponding to a step of forming a first portion 11 and a second portion 12 in a method for manufacturing a solar cell provided by another embodiment of the present application. [Figure 26] FIG. 26 is a diagram showing a cross-sectional structure corresponding to a step of forming a first passivation layer and a second passivation layer in another method for manufacturing a solar cell provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] As can be seen from the background art, conventional solar cells have a problem of low photoelectric conversion efficiency.

[0035] As can be seen from the analysis, one of the reasons for the low photoelectric conversion efficiency of the current solar cell is that, as shown in FIG. 1, currently, in a TOPCON (Tunnel Oxide Passivated Contact) cell, the first surface 1 of the substrate 100 has a passivation contact structure, which includes a tunnel layer 2 and a doped conductive layer 3, where the doped conductive layer 3 has a certain concentration of doping element, thereby forming a band bending on the surface of the substrate 100 and realizing the selective transport of carriers. A metal electrode 4 is in electrical contact with the doped conductive layer 3. The carriers in the substrate 100 are transported into the doped conductive layer 3 and collected by the metal electrode 4. The doping element concentration in the doped conductive layer 3 is an important factor for controlling the performance of the doped conductive layer 3. If the doping concentration is too low, a sufficiently high potential barrier cannot be formed between the doped conductive layer 3 and the substrate 100, and the carriers in the substrate 100 cannot tunnel through the second surface 2, resulting in a sharp drop in the carrier collection efficiency. On the other hand, if the doping element concentration in the doped conductive layer 3 is too high, the parasitic absorption of the incident light in the doped conductive layer 3 increases, the utilization rate of the incident light in the substrate 100 decreases, and the passivation quality of the doped conductive layer 3 is significantly reduced. Therefore, controlling the doping element concentration in the doped conductive layer 3 is the key to improving the photoelectric conversion performance of the solar cell.

[0036] In the embodiment of the present application, a solar cell is provided, in which the doping element concentration of the first doped conductive layer is smaller than the doping element concentration of the second doped conductive layer, thereby reducing the probability that the impurity elements in the first doped conductive layer enter the tunnel layer, and ensuring that the tunnel layer has good tunnel performance. In addition, in a direction perpendicular to the first surface, the first and second parts of the second doped conductive layer both form a concentration gradient with the first doped conductive layer, which is conducive to the vertical transport of carriers, reinforces the transport of carriers in the substrate to the second doped conductive layer, and improves the carrier collection ability of the first electrode. Since the doping element concentration of the first part is smaller than the doping element concentration of the second part, a concentration gradient is also formed between the first and second parts, which is conducive to the lateral transport of carriers in the second doped conductive layer, and further improves the carrier collection ability of the first electrode. In addition, since the doping element concentration of the second portion is relatively high, the contact recombination loss between the first electrode and the second portion can be improved, and since the doping element concentration of the first portion is relatively low, the parasitic absorption of incident light in the first portion not in contact with the first electrode can be reduced, and the utilization rate of the incident light of the substrate can be increased. By adjusting and controlling the doping element concentration of the first doped conductive layer and the doping element concentrations of the first and second portions of the second doped conductive layer, the first doped conductive layer and the first and second portions having different doping element concentrations can interact with each other, improving the carrier transport ability and comprehensively improving the photoelectric conversion performance of the solar cell.

[0037] Hereinafter, each embodiment of the present application will be described in detail with reference to the drawings. However, as will be understood by those skilled in the art, although many technical details are proposed in each embodiment of the present application in order to allow the reader to understand the present application better, the technical solution claimed for protection by the present application can be realized without these technical details and various changes and modifications based on the following embodiments.

[0038] FIG. 2 is a diagram showing a top view structure of a solar cell provided by one embodiment of the present application, FIG. 3 is a diagram showing a cross-sectional structure of a first solar cell provided by one embodiment of the present application, and FIG. 3 is a diagram showing a cross-sectional structure along the AA' direction of FIG. 2.

[0039] As shown in FIG. 2 and FIG. 3, the solar cell includes a substrate 100 having a first surface 1 and a tunnel layer 110 formed on the first surface 1. The solar cell further includes a first doped conductive layer 120 formed on the tunnel layer 110. The solar cell further includes a second doped conductive layer 130 formed on the first doped conductive layer 120, the second doped conductive layer 130 includes a plurality of first portions and a plurality of second portions, each of the first portions 11 and each of the second portions 12 are alternately arranged along a predetermined direction X and a direction perpendicular to a thickness direction of the second doped conductive layer 130, each of the first portions 11 and each of the second portions 12 extend along the predetermined direction X, where the doping element concentration of the first doped conductive layer 120 is smaller than the doping element concentration of the first portion 11, and the doping element concentration of the first portion 11 is smaller than the doping element concentration of the second portion 12, where the predetermined direction X is parallel to the first surface 1. The solar cell further includes a plurality of first electrodes, each of which, a first electrode 140, extends along a predetermined direction X, each of the first electrodes 140 corresponds one-to-one to each of the second portions 12, and one first electrode 140 is in electrical contact with a corresponding second portion 12.

[0040] The substrate 100 is used to receive incident light and generate photo-generated carriers, and in some embodiments, the substrate 100 may be a silicon substrate, and the material of the silicon substrate may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In some embodiments, the material of the substrate 100 may be a semiconductor material. In some embodiments, the material of the substrate 100 may be silicon carbide, an organic material, or a multi-component compound. The multi-component compound may include, but is not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide, and the like.

[0041] In some embodiments, the solar cell may be a TOPCON cell, and the substrate 100 has a second surface 2 opposite the first surface 1. In some embodiments, the solar cell is a bifacial cell, and both the first surface 1 and the second surface 2 can be used to receive incident light. In some embodiments, the solar cell is a monofacial cell, and either the first surface 1 or the second surface 2 can be used to receive incident light.

[0042] In some embodiments, when the solar cell is a monofacial cell and the second surface 2 is a light receiving surface, the second surface 2 of the substrate 100 can be textured, e.g., a pyramidal texture, so that the reflectance of the second surface 2 of the substrate 100 to the incident light is reduced and the absorption utilization rate of the light is increased, since the solar cell is a monofacial cell and the second surface 2 is a light receiving surface. In some embodiments, the first surface 1 of the substrate 100 can be a polished surface, i.e., the first surface 1 of the substrate 100 is flat compared to the second surface 2 of the substrate 100. In some embodiments, when the first surface 1 is a light receiving surface, the first surface 1 can be textured, e.g., a pyramidal texture, and the second surface 2 can be polished. In some embodiments, the solar cell is a monofacial cell and both the first surface 1 and the second surface 2 can be textured, e.g., a pyramidal texture.

[0043] In some embodiments, the solar cell is a bifacial cell, and both the second surface 2 of the substrate 100 and the first surface 1 of the substrate 100 can be pyramidal textured.

[0044] In some embodiments, the substrate 100 includes doping elements, and the type of the doping elements is N-type or P-type, where the N-type elements can be group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb) or arsenic (As), and the P-type elements can be group III elements such as boron (B), aluminum (Al), gallium (Ga) or indium (In). For example, if the substrate 100 is a P-type substrate, the type of the doping elements therein is P-type. Alternatively, if the substrate 100 is an N-type substrate, the type of the doping elements therein is N-type.

[0045] One first electrode 140 is in electrical contact with one second portion 12, and carriers in the substrate 100 are tunneled into the first doped conductive layer 120 through the tunnel layer 110. Carriers in the first doped conductive layer 120 are transported to the second portion 12 and collected by the first electrode 140 in electrical contact with the second portion 12, carriers in the first doped conductive layer 120 can also be transported to the first portion 11, and carriers in the first portion 11 are transported to the second portion 12 and further collected by the first electrode 140 in electrical contact with the second portion 12.

[0046] In some embodiments, the orthogonal projection of the first electrode 140 on the first surface 1 can be located within the orthogonal projection of the second portion 12 on the first surface 1, i.e., the width dimension of the first electrode 140 can be smaller than the width dimension of the second portion 12. In some embodiments, the orthogonal projection of the first electrode 140 on the first surface 1 can overlap with the orthogonal projection of the second portion 12 on the first surface 1. The first portion 11 is a portion of the second doped conductive layer 130 other than the second portion 12.

[0047] The first doped conductive layer 120 and the second doped conductive layer 130 can form a band bending at the first surface 1 and form a built-in electric field, so that the potential barrier for majority carriers is lower than the potential barrier for minority carriers, and holes escape from the interface to reduce the hole concentration, but the majority carriers in the substrate 100 are easily tunneled into the first doped conductive layer 120 and the second doped conductive layer 130 through the tunnel layer 110, thereby realizing selective carrier transport.

[0048] The first doped conductive layer 120 is closer to the tunnel layer 110 than the second doped conductive layer 130, and the doping element concentration of the first doped conductive layer 120 is lower than the doping element concentration of the second doped conductive layer 130, thereby reducing the probability that the impurity elements in the first doped conductive layer 120 will enter the tunnel layer 110, ensuring good tunneling performance of the tunnel layer 110, and thus ensuring that the number of carriers tunneling from the substrate 100 through the tunnel layer 110 is increased, and ensuring good chemical passivation effect of the tunnel layer 110 on the first surface 1.

[0049] The impurity element here refers to the doping element in the first doped conductive layer 120, and if the doping element concentration is too high, the impurity element in the first doped conductive layer 120 will diffuse into the tunnel layer 110 and form an impurity element in the tunnel layer 110, affecting the tunnel performance of the tunnel layer 110, causing the passivation ability of the tunnel layer 110 to the first surface 1 to be rapidly reduced, and the Auger recombination of the first surface 1 to be rapidly increased. In some embodiments, the material of the tunnel layer 110 includes at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon, or polycrystalline silicon.

[0050] The second doped conductive layer 130 includes a first portion 11 and a second portion 12, and the doping element concentrations of the first portion 11 and the second portion 12 are both greater than the doping element concentration of the first doped conductive layer 120, so that the first portion 11 and the second portion 12 form a concentration gradient with the first doped conductive layer 120 in the direction perpendicular to the first surface 1. That is, the second doped conductive layer 130 also forms a surface electric field on the surface of the first doped conductive layer 120, realizing selective transport of carriers in the first doped conductive layer 120 to the second doped conductive layer 130. This reinforces the vertical transport of carriers, reinforces the transport of carriers in the substrate 100 to the second doped conductive layer 130, increases the number of carriers transported to the second doped conductive layer 130, and further increases the number of carriers collected in the first electrode 140, which helps to increase the short-circuit current and open-circuit voltage of the solar cell and improve the photoelectric conversion performance of the solar cell.

[0051] The doping element concentration of the first portion 11 is smaller than that of the second portion 12, so that a concentration gradient is also formed between the first portion 11 and the second portion 12 in a direction perpendicular to the predetermined direction X and the thickness direction of the second doped conductive layer 130, i.e., a built-in electric field is also formed in the second doped conductive layer 130, reinforcing the transport of carriers from the first portion 11 to the second portion 12. Carriers in a portion of the second doped conductive layer 130 that is not in contact with the first electrode 140 are also transported to the second portion 12 and collected by the first electrode 140, further increasing the number of carriers collected by the first electrode 140, and further increasing the short-circuit current and open-circuit voltage of the solar cell.

[0052] The doping element concentration of the second portion 12 is greater than that of the first portion 11, and the sheet resistance of the second portion 12 is smaller than that of the first portion 11. This reduces the contact resistance between the first electrode 140 and the second portion 12, realizing good ohmic contact between the first electrode 140 and the second portion 12, reducing the contact recombination loss between the first electrode 140 and the second portion 12, reducing the transport loss of carriers to the first electrode 140, and helping to improve the collection ability of the first electrode 140 for carriers. The doping element concentration of the first portion 11 is relatively low, which reduces the parasitic absorption of incident light by the first portion 11 that is not in contact with the first electrode 140, increases the utilization rate of the substrate 100 for incident light, and improves the photoelectric conversion performance of the solar cell.

[0053] In some embodiments, the doping element type of the first doped conductive layer 120 is the same as the doping element type of the substrate 100, and the doping element type of the second doped conductive layer 130 is the same as the doping element type of the substrate 100. Thus, the first doped conductive layer 120 and the second doped conductive layer 130 can form a band bending at the first surface 1 of the substrate 100, and realize selective carrier transport. In some embodiments, if the doping element of the substrate 100 is P-type, the doping element type of the first doped conductive layer 120 and the doping element type of the second doped conductive layer 130 are both P-type. In some embodiments, if the doping element of the substrate 100 is N-type, the doping element type of the first doped conductive layer 120 and the doping element type of the second doped conductive layer 130 are both N-type. The doping element of the first doped conductive layer 120 and the doping element of the second doped conductive layer 130 may be the same or different.

[0054] In the embodiment of the present application, the specific doping elements of the first doped conductive layer 120 and the second doped conductive layer 130 are not limited, and the doping element type of the first doped conductive layer 120 and the second doped conductive layer 130 may be the same as the doping element type of the substrate 100, for example, the P-type doping element may be any of the group III elements such as boron (B), aluminum (Al), gallium (Ga) or indium (In), and the N-type doping element may be any of the group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb) or arsenic (As).

[0055] In some embodiments, the ratio of the doping element concentration in the first portion 11 to the doping element concentration in the second portion 12 is between 1:50 and 3:4, and may be, for example, between 1:50 and 1:45, between 1:45 and 1:40, between 1:40 and 1:30, between 1:30 and 1:25, between 1:25 and 1:20, between 1:20 and 1:15, between 1:15 and 1:10, between 1:10 and 1:5, between 1:5 and 1:3, between 1:3 and 1:2, between 1:2 and 2:3, or between 2:3 and 3:4. In the above range, the doping element concentration of the second portion 12 is greater than the doping element concentration of the first portion 11, thereby making the sheet resistance of the second portion 12 smaller than the sheet resistance of the first portion 11, reducing the contact resistance between the second portion 12 and the first electrode 140, improving the ohmic contact between the second portion 12 and the first electrode 140, reducing the metal contact recombination loss between the first electrode 140 and the second portion 12, and reducing the transport loss of carriers to the first electrode 140.

[0056] Within the above range, the doping element concentration of the second portion 12 is not too large compared with the doping element concentration of the first portion 11, thereby preventing the passivation performance of the second portion 12 from being impaired due to the doping element concentration of the second portion 12 being too large, and improving the ohmic contact between the second portion 12 and the first electrode 140, while maintaining good passivation performance of the second portion 12, including passivation for the first surface 1 and passivation between the contact interface between the first electrode 140 and the second electrode.

[0057] In the above range, the doping element concentration of the first portion 11 is smaller than that of the second portion 12, so that the first portion 11 has a weak parasitic absorption ability for incident light and ensures a high absorption utilization ability for incident light of the substrate 100. In addition, the doping element concentration of the first portion 11 is relatively small, and compared with the second portion 12, the first portion 11 has a better passivation performance for the first surface 1, which can reduce Auger recombination on the first surface 1 and inhibit carrier recombination on the first surface 1.

[0058] The second doped conductive layer 130 has a plurality of first portions and a plurality of second portions, the doping element concentration of each first portion 11 among the plurality of first portions is greater than the doping element concentration of each second portion 12 among the plurality of second portions, and the ratio of the doping element concentration of each first portion 11 to each second portion 12 is 1:50 to 3:4.

[0059] In some embodiments, the doping element types of the first doped conductive layer 120 and the second doped conductive layer 130 are both P-type, and the doping element concentration of the first portion 11 is 5×10 18 atom / cm 3 ~5×10 19 atom / cm 3 For example, 5×10 18 atom / cm 3 ~9×10 18 atom / cm 3 , 9×10 18 atom / cm 3 ~1×10 19 atom / cm 3 , 1×10 19 atom / cm 3 ~2×10 19 atom / cm 3 or 2×10 19 atom / cm 3 ~5×10 19 atom / cm 3 The doping element concentration of the second portion 12 may be 5×10 19 atom / cm 3 ~3×10 20 atom / cm3 For example, 5×10 19 atom / cm 3 ~9×10 19 atom / cm 3 , 9×10 19 atom / cm 3 ~1×10 20 atom / cm 3 , 1×10 20 atom / cm 3 ~2×10 20 atom / cm 3 or 2×10 20 atom / cm 3 ~3×10 20 atom / cm 3 When the doping element type is P-type, within the above range, both the first portion 11 and the second portion 12 have good passivation performance, and the sheet resistance of the second portion 12 is low, which helps to improve the ohmic contact between the second portion 12 and the first electrode. In some embodiments, the P-type doping element may be boron, aluminum, nitrogen, gallium, or indium.

[0060] In some embodiments, the doping element types of the first doped conductive layer 120 and the second doped conductive layer 130 are both N-type, and the doping element concentration of the first portion 11 is 1×10 20 atom / cm 3 ~2×10 21 atom / cm 3 For example, 1×10 20 atom / cm 3 ~2×10 20 atom / cm 3 , 2×10 20 atom / cm 3 ~5×10 20 atom / cm 3 , 5×10 20 atom / cm 3 ~9×10 20 atom / cm 3 , 9×10 20 atom / cm 3 ~1×10 21 atom / cm 3or 1×10 21 atom / cm 3 ~2×10 21 atom / cm 3 The doping element concentration of the second portion 12 is 2×1020 atom / cm3 to 5×1021 atom / cm3, for example, 2×10 20 atom / cm 3 ~3×10 20 atom / cm 3 , 3×10 20 atom / cm 3 ~5×10 20 atom / cm 3 , 5×10 20 atom / cm 3 ~9×10 20 atom / cm 3 , 9×10 20 atom / cm 3 ~1×10 21 atom / cm 3 , 1×10 21 atom / cm 3 ~3×10 21 atom / cm 3 or 3×10 20 atom / cm 3 ~5×10 21 atom / cm 3 In some embodiments, the N-type doping element may be phosphorus, bismuth, antimony, or arsenic. When the doping element type is N-type within the above range, both the first portion 11 and the second portion 12 can have good passivation performance, and the sheet resistance of the second portion 12 is low, and the ohmic contact with the first electrode 140 is improved.

[0061] By setting the doping element concentrations of the first portion 11 and the second portion 12 with different types of doping elements, the doping element concentration of the first portion 11 is small within the above range, which weakens the parasitic absorption of the incident light in the first portion 11 and increases the absorption utilization rate of the incident light in the substrate 100. Moreover, within the above range, the first portion 11 has good passivation performance, which prevents the first portion 11 from causing too much Auger recombination at the first surface 1, and suppresses the recombination of carriers at the first surface 1.

[0062] Within the above range, the doping element concentration of the second portion 12 is large and the sheet resistance of the second portion 12 is small, so that good ohmic contact can be formed between the second portion 12 and the first electrode 140, the metal contact recombination loss between the first electrode 140 and the second portion 12 can be improved, and the transport loss during the transport of carriers to the first electrode 140 can be reduced. In addition, within the above range, the doping element concentration of the second portion 12 is not too high, so that it is possible to prevent the doping element concentration of the second portion 12 from being too high, which would cause too much Auger recombination at the first surface 1 and result in serious carrier recombination at the first surface 1.

[0063] Within the above range, a concentration gradient is formed within the second doped conductive layer 130 due to the concentration difference between the first portion 11 and the second portion 12. Due to the presence of this concentration gradient, a built-in electric field is also formed within the second doped conductive layer 130 from the second portion 12 toward the first portion 11, reinforcing the lateral transport of carriers in the first portion 11 into the second portion 12, increasing the collection number of carriers in the first electrode 140, and thus increasing the open circuit voltage and short circuit current of the solar cell, thereby improving the photoelectric conversion performance of the solar cell.

[0064] In the embodiment of the present application, the doping element concentrations of the first portion 11 and the second portion 12 refer to the surface doping concentration of the first portion 11 at a surface distant from the substrate 100 and the surface doping concentration of the second portion 12 at a surface distant from the substrate 100. In addition, when the doping element types of the first doped conductive layer 120 and the second doped conductive layer 130 are both P-type, the doping element concentration of each first portion 11 among the multiple first portions is 5×10 18 atom / cm 3 ~5×10 19 atom / cm 3 and the doping element concentration of each of the second portions 12 is 5×10 19 atom / cm 3 ~3×10 20 atom / cm 3 When the doping element types of the first doped conductive layer and the second doped conductive layer are both N-type, the doping element concentration of each of the first portions 11 among the plurality of first portions is 1×10 20 atom / cm 3 ~2×10 21 atom / cm 3 The doping element concentration of each of the second portions 12 is 2×10 20 atom / cm 3 ~5×10 21 atom / cm 3 It is.

[0065] In some embodiments, the ratio of the doping element concentration of the first doped conductive layer 120 to the doping element concentration of the second portion 12 is 1:100 to 1:2, and may be, for example, 1:100 to 1:85, 1:85 to 1:70, 1:70 to 1:60, 1:60 to 1:50, 1:50 to 1:40, 1:40 to 1:25, 1:25 to 1:15, 1:15 to 1:10, 1:10 to 1:5, or 1:5 to 1:2. Within the above range, the doping element concentration of the first doped conductive layer 120 is smaller than the doping element concentration of the second portion 12, thereby suppressing the diffusion of the doping element in the first doped conductive layer 120 to the tunnel layer 110, preventing the occurrence of problems that impair the tunnel performance and passivation performance of the tunnel layer 110, and the tunnel layer 110 has a good chemical passivation effect on the first surface 1.

[0066] In addition, by arranging the first doped conductive layer 120 close to the tunnel layer 110 and reducing the doping element concentration of the first doped conductive layer 120, the problem of excessive Auger recombination occurring at the first surface 1 due to the doping element concentration of the first doped conductive layer 120 being too high can be avoided, and the recombination of carriers at the first surface 1 can be effectively suppressed.

[0067] In the embodiments of the present application, the doping element concentration of the first doped conductive layer 120 refers to the surface doping concentration of the surface of the first doped conductive layer 120 away from the substrate 100 .

[0068] The ratio of the doping element concentration of the first doped conductive layer 120 to the doping element concentration of each of the second portions 12 is in the range of 1:100 to 1:2.

[0069] In some embodiments, the doping element types of the first doped conductive layer 120 and the second doped conductive layer 130 are both P-type, and the doping element concentration of the first doped conductive layer 120 is 1×10 18 atom / cm 3 ~4.5×10 19 atom / cm 3For example, 1×10 18 atom / cm 3 ~2×10 18 atom / cm 3 , 2×10 18 atom / cm 3 ~5×10 18 atom / cm 3 , 5×10 18 atom / cm 3 ~9×10 18 atom / cm 3 , 9×10 18 atom / cm 3 ~1×10 19 atom / cm 3 , 1×10 19 atom / cm 3 ~3×10 19 atom / cm 3 or 3×10 19 atom / cm 3 ~4.5×10 19 atom / cm 3 The doping element concentration of the second portion 12 may be 5×10 19 atom / cm 3 ~3×10 20 atom / cm 3 For example, 5×10 19 atom / cm 3 ~9×10 19 atom / cm 3 , 9×10 19 atom / cm 3 ~1×10 20 atom / cm 3 , 1×10 20 atom / cm 3 ~2×10 20 atom / cm 3 or 2×10 20 atom / cm 3 ~3×10 20 atom / cm 3 The doping element concentration of the first portion 11 may be 5×10 18 atom / cm 3 ~5×10 19 atom / cm 3 For example, 5×1018 atom / cm 3 ~9×10 18 atom / cm 3 , 9×10 18 atom / cm 3 ~1×10 19 atom / cm 3 , 1×10 19 atom / cm 3 ~2×10 19 atom / cm 3 or 2×10 19 atom / cm 3 ~5×10 19 atom / cm 3 When the doping element type is P-type, within the above range, the first doping conductive layer 120, the first portion 11 and the second portion 12 have good performance, so that the first doping conductive layer 120, the first portion 11 and the second portion 12 can form a band bending at the first surface 1 to realize carrier transport, and the first doping conductive layer 120, the first portion 11 and the second portion 12 all have good passivation performance. In some embodiments, the P-type doping element may be boron, aluminum, nitrogen, gallium or indium.

[0070] In some embodiments, the doping element types of the first doped conductive layer 120 and the second doped conductive layer 130 are both N-type, and the doping element concentration of the first doped conductive layer 120 is 5×10 19 atom / cm 3 ~5×10 20 atom / cm 3 For example, 5×10 19 atom / cm 3 ~9×10 19 atom / cm 3 , 9×10 19 atom / cm 3 ~1×10 20 atom / cm 3 , 1×10 20 atom / cm 3 ~2×10 20 atom / cm 3 or 2×10 20atom / cm 3 ~5×10 20 atom / cm 3 The doping element concentration of the first portion 11 may be 1×10 20 atom / cm 3 ~2×10 21 atom / cm 3 For example, 1×10 20 atom / cm 3 ~2×10 20 atom / cm 3 , 2×10 20 atom / cm 3 ~5×10 20 atom / cm 3 , 5×10 20 atom / cm 3 ~9×10 20 atom / cm 3 , 9×10 20 atom / cm 3 ~1×10 21 atom / cm 3 or 1×10 21 atom / cm 3 ~2×10 21 atom / cm 3 The doping element concentration of the second portion 12 may be 2×10 20 atom / cm 3 ~5×10 21 atom / cm 3 For example, 2×10 20 atom / cm 3 ~3×10 20 atom / cm 3 , 3×10 20 atom / cm 3 ~5×10 20 atom / cm 3 , 5×10 20 atom / cm 3 ~9×10 20 atom / cm 3 , 9×10 20 atom / cm 3 ~1×10 21 atom / cm 3 , 1×10 21 atom / cm 3 ~3×1021 atom / cm 3 or 3×10 20 atom / cm 3 ~5×10 21 atom / cm 3 When the doping element type is N-type, within the above range, the first doping conductive layer, the first portion and the second portion all have good performance, so that the first doping conductive layer 120, the first portion 11 and the second portion 12 can form a band bending at the first surface 1 to realize carrier transport, and the first doping conductive layer 120, the first portion 11 and the second portion 12 all have good passivation performance. In some embodiments, the N-type doping element can be phosphorus, bismuth, antimony or arsenic.

[0071] By setting the range of the doping element concentration of the first doping conductive layer 120, the first portion 11 and the second portion 12 by different kinds of doping elements, the doping element concentration of the first doping conductive layer 120 is smaller than the doping element concentration of the second doping conductive layer 130 within the above range. This reduces the probability that the doping element in the first doping conductive layer 120 is transported to the tunnel layer 110, and the good tunnel performance of the tunnel layer 110 can be maintained. In addition, within the above range, the doping element concentration of the first doping conductive layer 120 is not too small, ensuring that the doping element concentration of the first doping conductive layer 120 is sufficiently high, and a sufficiently high potential barrier can be formed with the substrate 100, so that carriers can reach the first doping conductive layer 120 through the tunnel layer 110.

[0072] In addition, within the above range, the concentration difference between the first doped conductive layer 120 and the first portion 11 and between the first doped conductive layer 120 and the second portion 12 is sufficiently large, and thus a concentration gradient can be formed between the first doped conductive layer 120 and the first portion 11 and between the first doped conductive layer 120 and the second portion 12. Since the doping element concentration of the first portion 11 is greater than that of the first doped conductive layer 120, the first portion 11 can form a surface electric field on the surface of the first doped conductive layer 120, and the second portion 12 can form a surface electric field on the surface of the first doped conductive layer 120, which can enhance the transport of carriers in the first doped conductive layer 120 to the first portion 11 and the second portion 12.

[0073] 4 is a diagram showing a cross-sectional structure of a second solar cell in an embodiment of the present application, and FIG. 4 is a diagram showing a cross-sectional structure along the AA' direction in FIG. 2. In some embodiments, the first doped conductive layer 120 includes a plurality of third portions and a plurality of fourth portions, each of the third portions 13 and each of the fourth portions 14 are alternately arranged along a direction parallel to the first surface 1, each of the third portions 13 and each of the fourth portions 14 extend along a preset direction X, one third portion 13 faces one first portion 11, one fourth portion 14 faces one second portion 12, and the doping element concentration of the third portion 13 is smaller than the doping element concentration of the fourth portion 14. That is, the doping element concentration of the first doped conductive layer 120 facing the first electrode 140 is larger than the doping element concentration of the first doped conductive layer 120 not facing the first electrode 140.

[0074] Since the doping element concentration of the third portion 13 is smaller than that of the fourth portion 14, a concentration gradient is formed between the third portion 13 and the fourth portion 14. Due to the presence of this concentration gradient, a built-in electric field is formed in the first doped conductive layer 120 from the fourth portion 14 to the third portion 13, and the lateral transport of carriers in the third portion 13 to the fourth portion 14 can be strengthened. Since the fourth portion 14 faces the first electrode 140, the transport efficiency of carriers from the fourth portion 14 to the second portion 12 is higher than that of the third portion 13, and more carriers can be collected by the first electrode 140. Based on this, the lateral transport of carriers in the third portion 13 to the fourth portion 14 can be strengthened, and the collection efficiency of the first electrode 140 for carriers can be increased.

[0075] In some embodiments, the doping element type of the first doped conductive layer 120 is P-type, and the ratio of the doping element concentration of the third portion 13 to the doping element concentration of the fourth portion 14 is 1:100 to 2:3, for example, 1:90, 1:80, 1:70, 1:65, 1:55, 1:50, 1:40, 1:30, 1:25, 1:20, 1:18, 1:15, 1:10, 1:5, 1:3 or 2:3. In some embodiments, the doping element type of the first doped conductive layer 120 is N-type, and the ratio of the doping element concentration of the third portion 13 to the doping element concentration of the fourth portion 14 is 1:30 to 5:6, for example, 1:30 to 1:25, 1:25 to 1:20, 1:20 to 1:15, 1:15 to 1:10, 1:10 to 1:8, 1:8 to 1:5, 1:5 to 1:3, 1:3 to 2:3, or 2:3 to 5:6.

[0076] By setting the ratio of the doping element concentration of the third portion 13 and the fourth portion 14 to different values ​​according to different kinds of doping elements, the third portion 13 and the fourth portion 14 have good passivation performance for the first surface 1 whether they are P-type doped or N-type doped. In addition, within the above ratio range, a concentration gradient can be formed between the third portion 13 and the fourth portion 14, and thus the collection efficiency of the carriers of the first electrode 140 can be improved. In some embodiments, the P-type doping element can be boron, aluminum, nitrogen, gallium, or indium. In some embodiments, the N-type doping element can be phosphorus, bismuth, antimony, or arsenic.

[0077] In some embodiments, the doping element type of the first doped conductive layer 120 is P-type, the number of the third portions 13 is multiple, the number of the fourth portions 14 is multiple, and the ratio of the doping element concentration of each of the third portions 13 among the multiple third portions to the doping element concentration of each of the fourth portions 14 among the multiple fourth portions is 1:100 to 2:3. In some embodiments, the doping element type of the first doped conductive layer 120 is N-type, the number of the third portions 13 is multiple, the number of the fourth portions 14 is multiple, and the ratio of the doping element concentration of each of the third portions 13 among the multiple third portions to the doping element concentration of each of the fourth portions 14 among the multiple fourth portions is 1:30 to 5:6.

[0078] Note that the doping element concentrations of the third portion 13 and the fourth portion 14 referred to here are the surface doping concentrations of the surface of the third portion 13 away from the substrate 100 and the surface doping concentrations of the surface of the fourth portion 14 away from the substrate 100.

[0079] In some embodiments, when the doping element type of the first doped conductive layer 120 is P-type, the doping element concentration of each third portion 13 of the plurality of third portions is 1×10 18 atom / cm 3 ~5×10 19 atom / cm 3 For example, 1×1018 atom / cm 3 ~2×10 18 atom / cm 3 , 2×10 18 atom / cm 3 ~5×10 18 atom / cm 3 , 5×10 18 atom / cm 3 ~9×10 18 atom / cm 3 , 9×10 18 atom / cm 3 ~1×10 19 atom / cm 3 , 1×10 19 atom / cm 3 ~3×10 19 atom / cm 3 or 3×10 19 atom / cm 3 ~5×10 19 atom / cm 3 The doping element concentration of each of the fourth portions 14 of the plurality of fourth portions may be 1×10 19 atom / cm 3 ~1×10 20 atom / cm 3 For example, 1×10 19 atom / cm 3 ~2×10 19 atom / cm 3 , 2×10 19 atom / cm 3 ~5×10 19 atom / cm 3 , 5×10 19 atom / cm 3 ~7×10 19 atom / cm 3 , 7×10 19 atom / cm 3 ~9×10 19 atom / cm 3 or 9×10 19 atom / cm 3 ~1×10 20 atom / cm 3 may be also possible.

[0080] In some embodiments, the doping element type of the first doped conductive layer 120 is N-type, and the doping concentration of each third portion 13 of the plurality of third portions is 2×10 19 atom / cm 3 ~5×10 20 atom / cm 3 For example, 2×10 19 atom / cm 3 ~3×10 19 atom / cm 3 , 3×10 19 atom / cm 3 ~5×10 19 atom / cm 3 , 5×10 19 atom / cm 3 ~9×10 19 atom / cm 3 , 9×10 19 atom / cm 3 ~1×10 20 atom / cm 3 , 1×10 20 atom / cm 3 ~3×10 20 atom / cm 3 or 3×10 20 atom / cm 3 ~5×10 20 atom / cm 3 The doping element concentration of each of the fourth portions 14 of the plurality of fourth portions may be 5×10 19 atom / cm 3 ~6×10 20 atom / cm 3 For example, 5×10 19 atom / cm 3 ~7×10 19 atom / cm 3 , 7×10 19 atom / cm 3 ~9×10 19 atom / cm 3 , 9×10 19 atom / cm 3 ~1×10 20 atom / cm 3 , 1×10 20 atom / cm 3 ~3×1020 atom / cm 3 , 3×10 20 atom / cm 3 ~5×10 20 atom / cm 3 or 5×10 20 atom / cm 3 ~6×10 20 atom / cm 3 may be also possible.

[0081] Within the above range, it is ensured that the doping element concentration of the fourth portion 14 is greater than that of the third portion 13, so that the lateral transport of carriers in the third portion 13 to the fourth portion 14 can be strengthened; at the same time, within the above range, the doping element concentrations of the third portion 13 and the fourth portion 14 are not too large, so that the doping element concentration of the entire first doped conductive layer 120 is small, so that the probability of the doping element in the first doped conductive layer 120 being transported to the tunnel layer 110 can be reduced.

[0082] In some embodiments, the ratio of the doping element concentration in the fourth portion 14 to the doping element concentration in the second portion 12 is 1:10 to 5:6, and may be, for example, 1:10 to 1:8, 1:8 to 1:6, 1:6 to 1:4, 1:4 to 1:3, 1:3 to 1:2, 1:2 to 2:3, 2:3 to 3:4, or 3:4 to 5:6. Within this range, the doping element concentration in the fourth portion 14 is smaller than the doping element concentration in the second portion 12, so that a concentration gradient is formed between the fourth portion 14 and the second portion 12, which enhances the transport of carriers in the fourth portion 14 to the second portion 12, and thus enhances the collection ability of the first electrode 140 for carriers in the second portion 12.

[0083] There are multiple fourth portions 14, there are multiple second portions 12, and the ratio of the doping element concentration of each fourth portion 14 among the multiple fourth portions to the doping element concentration of each second portion 12 among the multiple second portions is 1:10 to 5:6.

[0084] In some embodiments, the thickness ratio of the first doped conductive layer 120 and the second doped conductive layer 130 can be controlled to ensure that the first electrode 140 is not easily penetrated through the second doped conductive layer 130, while at the same time ensuring that the total thickness of the first doped conductive layer 120 and the second doped conductive layer 130 is not too large, thereby avoiding the problem of the total thickness of the first doped conductive layer 120 and the second doped conductive layer 130 being too large causing excessive stress to the tunnel layer 110, and maintaining good performance of the tunnel layer 110.

[0085] In some embodiments, the ratio of the thickness d1 of the first doped conductive layer 120 to the thickness d2 of the second doped conductive layer 130 is 2:1 to 1:12, and may be, for example, 2:1 to 3:2, 3:2 to 4:3, 4:3 to 1:1, 1:1 to 1:3, 1:3 to 1:2, 1:2 to 1:5, 1:5 to 1:7, 1:7 to 1:9, or 1:9 to 1:12. Within the above range, it is difficult for the actually manufactured first electrode 140 to penetrate the second doped conductive layer 130 and electrically contact the first doped conductive layer 120, and to achieve good ohmic contact between the first electrode 140 and the second portion 12. Furthermore, the thickness d1 of the first doped conductive layer 120 is not too large, and the total thickness of the first doped conductive layer 120 and the second doped conductive layer 130 is not too large, to avoid excessive stress being applied to the tunnel layer 110 due to the total thickness of the first doped conductive layer 120 and the second doped conductive layer 130 being too large.

[0086] In some embodiments, the material of the first doped conductive layer 120 includes at least one of amorphous silicon, polycrystalline silicon, or silicon carbide. In some embodiments, the first doped conductive layer 120 includes a third portion 13 and a fourth portion 14, and the third portion 13 and the fourth portion 14 are obtained by performing different doping concentrations on different portions of the first doped conductive layer 120, and therefore the third portion 13 and the fourth portion 14 are an integrated structure.

[0087] In some embodiments, the material of the second doped conductive layer 130 includes at least one of amorphous silicon, polycrystalline silicon, or silicon carbide. The first portion 11 and the second portion 12 are obtained by performing different doping concentrations on different portions of the second doped conductive layer 130, and the first portion 11 and the second portion 12 are an integrated structure.

[0088] In some embodiments, the first doped conductive layer 120 is made of a first polycrystalline silicon, the first portion 11 is made of a second polycrystalline silicon, and the second portion 12 is made of a third polycrystalline silicon, and the first polycrystalline silicon has an average grain size larger than the second polycrystalline silicon and larger than the third polycrystalline silicon. The second polycrystalline silicon has an average grain size larger than the third polycrystalline silicon.

[0089] In polycrystalline silicon, silicon atoms are arranged in a number of crystal nuclei in the form of a diamond crystal lattice, and these crystal nuclei grow into crystal grains with different crystal plane orientations, and when these crystal grains combine, they are crystallized into polycrystalline silicon. In other words, the first polycrystalline silicon, the second polycrystalline silicon, and the third polycrystalline silicon are all formed by combining multiple crystal grains. The contact interface between the crystal grains of the first polycrystalline silicon, the second polycrystalline silicon, and the third polycrystalline silicon that have the same structure but different orientations can be called a grain boundary.

[0090] That is, in a unit volume, the grain density of the first polycrystalline silicon in the first doped conductive layer 120 is smaller than the grain density of the second polycrystalline silicon in the second doped conductive layer 130 and the grain density of the third polycrystalline silicon. As a result, the number of grain boundaries in the first doped conductive layer 120 per unit volume is smaller than the number of grain boundaries in the second doped conductive layer 130 per unit volume. The grain boundaries become the diffusion paths of the doping element, and the more the number of grain boundaries, the more the diffusion of the doping element becomes, and the higher the doping element concentration becomes. Since the number of grain boundaries in the first doped conductive layer 120 is relatively small, in the step of actually performing the doping process to form the first doped conductive layer 120, the degree of diffusion of the doping element in the first doped conductive layer 120 is low, and a small doping element concentration in the first doped conductive layer 120 is ensured. Since the number of grain boundaries in the second doped conductive layer 130 is relatively large, the degree of diffusion of the doping element in the second doped conductive layer 130 is high, and the concentration of the doping element in the second doped conductive layer 130 is high.

[0091] Furthermore, the number of crystal grains in the second doped conductive layer 130 per unit volume is greater than the number of crystal grains in the first doped conductive layer 120, i.e., the crystallinity of the second doped conductive layer 130 is high, so that the second doped conductive layer 130 has better passivation performance and can further improve the metal contact composite between the second portion 12 and the first electrode 140.

[0092] As shown in FIG. 4 , in some embodiments, the first doped conductive layer 120 may include a third portion 13 facing the first portion 11 and a fourth portion 14 facing the second portion 12, where the third portion 13 is made of a fourth polycrystalline silicon, the fourth portion 14 is made of a fifth polycrystalline silicon, the first portion 11 is made of a second polycrystalline silicon, and the second portion 12 is made of a third polycrystalline silicon, where an average grain size of the fourth polycrystalline silicon is larger than an average grain size of the fifth polycrystalline silicon, an average grain size of the fifth polycrystalline silicon is larger than an average grain size of the third polycrystalline silicon, an average grain size of the second polycrystalline silicon is larger than an average grain size of the third polycrystalline silicon, and an average grain size of the fifth polycrystalline silicon is larger than an average grain size of the second polycrystalline silicon.

[0093] The average crystal grain size of the fourth polycrystalline silicon is larger than the average crystal grain size of the fifth polycrystalline silicon, i.e., the average crystal grain size in the first doped conductive layer 120 facing the first electrode 140 is smaller than the average crystal grain size in the first doped conductive layer 120 not facing the first electrode 140. As a result, the number of grain boundaries per unit volume in the first doped conductive layer 120 facing the first electrode 140 is larger than the number of grain boundaries per unit volume in the first doped conductive layer 120 not facing the first electrode 140. As a result, in the step of actually performing doping to form the first doped conductive layer 120, the degree of diffusion of the doping element in the first doped conductive layer 120 facing the first electrode 140 is greater than the degree of diffusion of the doping element in the first doped conductive layer 120 not facing the first electrode 140, which helps to realize that the doping element concentration in the third portion 13 is smaller than the doping element concentration in the fourth portion 14, forms a concentration gradient between the third portion 13 and the fourth portion 14, and helps to transport carriers laterally from the third portion 13 to the fourth portion 14.

[0094] In addition, the average grain size of the first polycrystalline silicon, the second polycrystalline silicon, the third polycrystalline silicon, the fourth polycrystalline silicon and the fifth polycrystalline silicon in the embodiments of the present application can be measured in accordance with the Chinese national standard "GB / T6394-2017 Method for Determining Average Grain Size of Metals."

[0095] FIG. 5 is a diagram showing a top view configuration of another solar cell provided by an embodiment of the present application, FIG. 6 is a diagram showing a cross-sectional structure of a third solar cell provided by an embodiment of the present application, and FIG. 6 is a diagram showing a cross-sectional structure along the AA' direction of FIG. 5.

[0096] As shown in Figures 5 and 6, in some embodiments, the doping element type of the substrate 100 is an N-type doping element, and the second portion 12 includes a main body portion 20 doped with an N-type doping element and an inversion doping portion 21 located within the main body portion 20 and doped with a P-type doping element.

[0097] In some embodiments, the material of the first electrode 140 is a metal, and includes any of copper, silver, nickel, or aluminum. The material of the second portion 12 is silicon, and is, for example, any of polycrystalline silicon, amorphous silicon, or single crystal silicon. In the step of actually manufacturing the first electrode 140, a metal paste is first formed, and the metal in the metal paste reacts with oxygen to form metal ions. Under the condition that the metal ions move into the second portion 12 and provide electrons, the metal ions and silicon in the second portion 12 undergo a reduction reaction, reducing the metal ions to metal, and the formed metal is located in the second portion 12, and thus the formed first electrode 140 and the second portion 12 are in electrical contact. However, if the amount of metal formed by reduction is too large, it may cause a problem that the formed first electrode 140 penetrates the entire second portion 12, and thus damage the second portion 12, and further cause the first electrode 140 to contact the substrate 100, which may adversely affect the photoelectric conversion performance of the solar cell.

[0098] The second doped conductive layer 130 includes a main body 20 having an N-type doping element and an inversion doping portion 21 located in the main body 20. The inversion doping portion 21 is doped with a P-type doping element, so that holes in the inversion doping portion 21 are dominant and provide more hole positions. Meanwhile, some of the electrons transported to the second portion 12 are recombined with the holes, and the number of electrons is reduced compared to when the inversion doping portion 21 is not provided. As a result, in the step of actually forming the first electrode 140, the number of electrons supplied is reduced, so that the reaction between the metal ions and silicon is weakened, and the metal ions and silicon are reduced to produce too much metal, which prevents the problem of the metal damaging the second portion 12 too much, and maintains good photoelectric conversion performance of the solar cell.

[0099] In some embodiments, the volume ratio of the inversion doping portion 21 in the body portion 20 is less than 1 / 2. That is, since the inversion doping portion 21 is a minority in the body portion 20, the volume of the body portion 20 is large enough to form a band bending at the first surface 1, and the first electrode 140 can contact many of the body portions 20 to form a metal contact, which helps to ensure the normal transport of carriers in the second portion 12 and the collection of carriers by the first electrode 140.

[0100] FIG. 7 is a diagram showing a cross-sectional structure of a fourth solar cell in one embodiment of the present application, and FIG. 8 is a diagram showing a cross-sectional structure of a fifth solar cell in one embodiment of the present application, and both FIG. 7 and FIG. 8 are diagrams showing cross-sectional structures along the AA' direction in FIG. 2.

[0101] As shown in Figures 7 and 8, in some embodiments, the semiconductor device further includes a blocking layer 150, the blocking layer 150 being located between the first doped conductive layer 120 and the second doped conductive layer 130, the surface of the blocking layer 150 facing the substrate 100 being in contact with the surface of the first doped conductive layer 120 away from the substrate 100, and the surface of the blocking layer 150 facing the substrate 100 being in contact with the surface of the second doped conductive layer 130 facing the substrate 100. Since the doping element concentration of the second doped conductive layer 130 is higher than that of the first doped conductive layer 120, a blocking layer 150 is provided between the first doped conductive layer 120 and the second doped conductive layer 130 to prevent the doping element in the second doped conductive layer 130 from diffusing excessively into the first doped conductive layer 120, and serves to block the diffusion of the doping element in the second doped conductive layer 130 into the first doped conductive layer 120, thereby maintaining a small doping element concentration in the first doped conductive layer 120.

[0102] In addition, in some embodiments, the material of the first electrode 140 includes a metal, the substrate 100 is an N-type substrate 100, and the blocking layer 150 serves to block the transport of electrons in the substrate 100 to the second portion 12, reducing the degree to which metal ions in the metal paste for forming the first electrode 140 react with silicon under conditions for supplying electrons, thereby reducing the probability that the formed first electrode 140 will penetrate the second doped conductive layer 130.

[0103] 7, in some embodiments, the surface of the blocking layer 150 away from the substrate 100 is in contact with each second portion 12, and the orthogonal projection of the blocking layer 150 on the first surface 1 overlaps with the orthogonal projection of the second portion 12 on the first surface 1. That is, the blocking layer 150 is located only between a part of the first doped conductive layer 120 and a part of the second doped conductive layer 130, and faces the second portion 12. This is because the doping element concentration in the second portion 12 is higher than that in the first portion 11. Therefore, by arranging the blocking layer 150 to face only the second portion 12, it is possible to prevent the doping element in the second portion 12, which has a relatively high doping element concentration, from diffusing into the first doped conductive layer 120.

[0104] In some embodiments, the number of barrier layers 150 may be multiple, with each barrier layer 150 of the multiple barrier layers 150 contacting one second portion 12 .

[0105] 8, in some embodiments, the surface of the blocking layer 150 away from the substrate 100 is in contact with each of the first portions 11 and each of the second portions 12, and the orthogonal projection of the blocking layer 150 on the first surface 1 overlaps with the orthogonal projection of each of the first portions 11 on the first surface 1 and the orthogonal projection of each of the second portions 12 on the first surface 1. That is, the front surface of the blocking layer 150 is covered by the surface of the first doped conductive layer 120 away from the substrate 100 and the surface of the second doped conductive layer 130 facing the substrate 100. Thus, the blocking layer 150 plays a role of blocking the doping elements in the first portion 11 and the second portion 12, and can prevent the doping elements in the first portion 11 and the second portion 12 from diffusing into the first doped conductive layer 120.

[0106] In some embodiments, whether the blocking layer 150 faces only the second portion 12 or faces the first portion 11 and the second portion 12, the material of the blocking layer 150 may be a wide band gap material, which can effectively prevent the doping element in the second doped conductive layer 130 from diffusing into the first doped conductive layer 120. In some embodiments, the material of the blocking layer 150 includes at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and magnesium fluoride. By using the above materials, the blocking layer 150 can have a good blocking effect, and can also have a good passivation effect on the first surface 1, thereby suppressing the recombination of carriers on the first surface 1. In addition, these materials have a relatively large hardness, so that in the step of actually manufacturing the first electrode 140, the formed first electrode 140 is less likely to burn through the blocking layer 150 during sintering, and thus the risk of the formed first electrode 140 and the substrate 100 coming into contact can be reduced.

[0107] In some embodiments, whether the blocking layer 150 faces only the second portion 12 or faces both the first portion 11 and the second portion 12, the thickness of the blocking layer 150 is 0.5 nm to 5 nm, and may be, for example, 0.5 nm to 0.8 nm, 0.8 nm to 1 nm, 1 nm to 1.5 nm, 1.5 nm to 2 nm, 2 nm to 2.5 nm, 2.5 nm to 3 nm, 3 nm to 3.5 nm, 3.5 nm to 4 nm, 4 nm to 4.5 nm, or 4.5 nm to 5 nm. Within the above range, the doping elements in the second doped conductive layer 130 can be effectively prevented from diffusing into the first doped conductive layer 120, while not adversely affecting the performance of the entire passivation contact structure composed of the first doped conductive layer 120, the second doped conductive layer 130 and the tunnel layer 110, and the selective transport of carriers in the passivation contact structure and good passivation effect on the first surface 1 can be maintained.

[0108] FIG. 9 is a diagram showing a cross-sectional structure of a sixth solar cell provided by an embodiment of the present application, and FIG. 9 is a diagram showing a cross-sectional structure along the direction AA′ of FIG.

[0109] 9 , in some embodiments, the solar cell further includes a first passivation layer 160, which covers the surfaces of the first portion 11 and the second portion 12 remote from the substrate 100. The first electrode 140 penetrates the first passivation layer 160 and is in electrical contact with the second portion 12. The first passivation layer 160 can provide a good passivation effect for the first surface 1, for example, providing a good chemical passivation for the dangling bonds of the first surface 1, reducing the defect level density of the first surface 1, and suppressing carrier recombination on the first surface 1.

[0110] In some embodiments, the first passivation layer 160 may be a single layer structure. In some embodiments, the first passivation layer 160 may be a multi-layer structure. In some embodiments, the material of the first passivation layer 160 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0111] In some embodiments, the solar cell may include an emitter 170 located at the second surface 2 of the substrate 100. The doping element type of the emitter 170 is opposite to the doping element type of the substrate 100 and forms a PN junction with the substrate 100. In some embodiments, the material of the emitter 170 is the same as the material of the substrate 100.

[0112] FIG. 10 is a diagram showing a cross-sectional structure of a seventh solar cell in one embodiment of the present application, and FIG. 10 is a diagram showing the cross-sectional structure taken along the line AA' in FIG.

[0113] 10, in some embodiments, the solar cell may not have an emitter 170, but may have a second passivation contact structure on the second surface 2, which includes a second tunneling layer 111 and a third doped conductive layer 112 located on the surface of the second tunneling layer 111, so that the solar cell is a double-sided TOPCON cell. The doping element type of the third doped conductive layer 112 is opposite to that of the substrate 100, i.e., the doping element of the third doped conductive layer 112 is P-type, forming a PN junction with the substrate 100.

[0114] In some embodiments, the material of the second tunnel layer 111 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0115] In some embodiments, the material of the third doped conductive layer 112 includes at least one of amorphous silicon, polycrystalline silicon, or silicon carbide.

[0116] As shown in FIGS. 9 and 10, in some embodiments, the solar cell further includes a second passivation layer 180.

[0117] 9, in some embodiments, the emitter 170 is disposed within the substrate 100, and the upper surface of the emitter 170 overlaps the second surface 2. Thus, the second passivation layer 180 is located on the surface of the emitter 170 that is remote from the substrate 100.

[0118] As shown in FIG. 10, in some embodiments, the emitter 170 is not provided in the substrate 100, but a second passivation contact structure is provided. The second passivation layer 180 is located on the surface of the third doped conductive layer 112 that is far from the substrate 100. The second passivation layer 180 is used to provide a good passivation effect for the second surface 2 of the substrate 100, reduce the defect state density of the second surface 2, and effectively inhibit the carrier recombination on the second surface 2 of the substrate 100. In addition, the second passivation layer 180 can provide a reflection reducing effect, which helps to reduce the reflection of the incident light and increase the utilization rate of the incident light.

[0119] In some embodiments, the second passivation layer 180 may be a single layer structure, and in some embodiments, the second passivation layer 180 may be a multi-layer structure. In some embodiments, the material of the second passivation layer 180 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0120] As shown in FIGS. 9-10, some embodiments further include a second electrode 190 located on the second surface 2 of the substrate 100.

[0121] 9, in some embodiments, an emitter 170 is located within the substrate 100. Thus, a second electrode 190 is in electrical contact with the emitter 170 through a second passivation layer 180.

[0122] 10, in some embodiments, there is no emitter 170 in the substrate 100, but a second passivation contact structure is provided, such that the second electrode is in electrical contact with the third doped conductive layer 112 through the second passivation layer 180. In some embodiments, the material of the second electrode may be a metal, such as copper, silver, nickel, or aluminum.

[0123] In the solar cell provided in the above embodiment, the doping element concentration of the first doped conductive layer 120 is smaller than that of the second doped conductive layer, so that the probability of the impurity element in the first doped conductive layer 120 entering the tunnel layer 110 is reduced. In addition, in the direction perpendicular to the first surface 1, the first portion 11 and the second portion 12 of the second doped conductive layer 130 both form a concentration gradient with the first doped conductive layer 120, which helps to drive the vertical transport of carriers and enhance the transport of carriers in the substrate 100 to the second doped conductive layer 130. The doping element concentration of the first portion 11 is smaller than that of the second portion 12, so that a concentration gradient is also formed between the first portion 11 and the second portion 12, which helps to enhance the lateral transport of carriers in the second doped conductive layer 130. Since the doping element concentration of the second portion 12 is relatively high, the contact recombination loss between the first electrode 140 and the second portion 12 can be improved. Since the doping element concentration in the first portion 11 is relatively low, parasitic absorption of incident light in the first portion 11 that is not in contact with the first electrode 140 can be reduced.

[0124] In another aspect of the embodiment of the present application, a photovoltaic module is further provided. As shown in Fig. 11, the photovoltaic module includes a cell string formed by connecting a plurality of solar cells 101 provided in the above embodiment, an encapsulation layer 102 for covering a surface of the cell string, and a cover plate 103 for covering a surface of the encapsulation layer 102 remote from the cell string. The solar cells 101 are electrically connected as a whole or in the form of a plurality of divided slices to form a plurality of cell strings, and the plurality of cell strings are electrically connected in series and / or parallel.

[0125] Specifically, in some embodiments, the plurality of battery strings may be electrically connected to each other via a conduction band 104. The encapsulation layer 102 covers the first surface 1 and the second surface 2 of the substrate 100 of the solar cell 101, and specifically, the encapsulation layer 102 may be an organic encapsulation film such as an ethylene vinyl acetate copolymer (EVA) film, an ethylene octene copolymer (POE) film, a polyethylene terephthalate (PET) film, or a polyvinyl butyral (PVB). In some embodiments, the cover plate 103 may be a cover plate having a light transmitting function, such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate 103 facing the encapsulation layer 102 may be an uneven surface to increase the utilization rate of incident light.

[0126] In addition, the present embodiment further provides a method for manufacturing a solar cell, which is used to manufacture the solar cell provided in the above embodiment.

[0127] As shown in FIG. 12, a substrate 100 having a first surface 1 is provided.

[0128] The substrate 100 is used to receive incident light and generate photo-generated carriers, and the substrate 100 has a first surface 1 and a second surface 2 opposite thereto.

[0129] In some embodiments, the substrate 100 is doped with an N-type doping element, which may be a Group V element such as phosphorus (P), bismuth (Bi), antimony (Sb) or arsenic (As). In some embodiments, the substrate 100 is doped with a P-type doping element, which may be a Group III element such as boron (B), aluminum (Al), gallium (Ga) or indium (In).

[0130] In some embodiments, the second surface 2 of the substrate 100 may be textured, for example a pyramidal texture, which reduces the reflectivity of the second surface 2 of the substrate 100 to the incident light and increases the absorption utilization of the light. The first surface 1 of the substrate 100 may be a polished surface, i.e., the first surface 1 of the substrate 100 is flatter than the second surface 2 of the substrate 100. In some embodiments, both the second surface 2 of the substrate 100 and the first surface 1 of the substrate 100 may be pyramidal textured.

[0131] In some embodiments, the substrate 100 may be subjected to a first doping step, for example an ion implantation step may be performed to diffuse doping elements into the substrate 100 .

[0132] In some embodiments, the solar cell formed is a TOPCON cell.

[0133] 13 , in some embodiments, a method for fabricating a solar cell includes forming an emitter 170 in a substrate 100, the emitter 170 having an upper surface exposed in the substrate 100 and overlying the second surface 2. The emitter 170 has a doping element type opposite to that of the substrate 100 and forms a PN junction with the substrate 100.

[0134] In some embodiments, the method of forming the emitter 170 may include performing a diffusion process on the second surface 2 side of the substrate 100 to diffuse a P-type element from the second surface 2 of the substrate 100 into the portion of the substrate 100, thereby converting the portion of the substrate 100 into which the P-type doping element is diffused into the emitter 170. In some embodiments, the diffusion process may be an ion implantation process. In some embodiments, a phosphorus diffusion process may be performed on the second surface 2 side of the substrate 100.

[0135] As shown in FIG. 14, after the emitter 170 is formed, a tunnel layer 110 is formed on the first surface 1 .

[0136] In some embodiments, the tunnel layer 110 can be formed at the first surface 1 using a deposition process, which may include either atomic layer deposition or chemical vapor deposition.

[0137] In some embodiments, the material of the tunnel layer 110 may include at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon, or polycrystalline silicon.

[0138] As shown in Fig. 15 to Fig. 25, a first doped conductive layer 120 is formed on a tunnel layer 110. A second doped conductive layer 130 is formed on a side of the first doped conductive layer 120 away from the substrate 100. The second doped conductive layer 130 includes a plurality of first portions and a plurality of second portions, and each of the first portions 11 and each of the second portions 12 are alternately arranged along a predetermined direction X and a direction perpendicular to the thickness direction of the second doped conductive layer 130, and each of the first portions 11 and each of the second portions 12 extend along the predetermined direction X, where the doping element concentration of the first doped conductive layer 120 is smaller than the doping element concentration of the first portions 11, and the doping element concentration of the first portions 11 is smaller than the doping element concentration of the second portions 12.

[0139] Compared with the second doped conductive layer 130, the first doped conductive layer 120 is closer to the substrate 100, and the doping element concentration of the first doped conductive layer 120 is lower than the doping element concentration of the second doped conductive layer 130, thereby reducing the probability that the impurity elements in the first doped conductive layer 120 enter the tunnel layer 110.

[0140] In some embodiments, a method of forming the first doped conductive layer 120 and the second doped conductive layer 130 may include the following.

[0141] As shown in FIGS. 15 to 19, an intrinsic silicon layer 30 is formed on the surface of the tunnel layer 110, and in some embodiments, the intrinsic silicon layer 30 may be any of polycrystalline silicon, amorphous silicon, single crystal silicon, or silicon carbide. A first doping process is performed on the intrinsic silicon layer 30 to form an initial silicon doped layer 32. A second doping process is performed on the initial silicon doped layer 32 to diffuse the doping element into only a part of the thickness of the initial silicon doped layer 32 to form a silicon doped layer 33, and the remaining initial silicon doped layer 32 is the first doped conductive layer 120. Finally, a third doping process is performed on a part of the silicon doped layer 33 to form a second portion 12, and the remaining part of the silicon doped layer 33 is the first portion 11.

[0142] In some embodiments, the first doping process may be an ion implantation process. In some embodiments, the second doping process may be a laser doping process, and the wavelength, frequency, energy, or scan rate of the laser may be controlled to control the depth of the doping element in the initial silicon doped layer 32, and thus the thickness of the first doped conductive layer 120 and the silicon doped layer 33 to be formed. In some embodiments, the third doping process may be a laser doping process, and the laser irradiation process may be performed on only a part of the silicon doped layer 33, and the doping element may be re-injected into the part of the silicon doped layer 33 to form the second portion 12 and the first portion 11.

[0143] 15, in some embodiments, the intrinsic silicon layer 30 may be intrinsic polycrystalline silicon, and in the first doping step, a doping source including a first doping element is deposited on the surface of the intrinsic silicon layer 30. In some embodiments, the first doping element is an N-type doping element. In some embodiments, the N-type doping source may be an element or compound including a pentavalent element, such as phosphorus or a compound including phosphorus, such as phosphorus trichloride.

[0144] Before the step of depositing the doping source, a quartz carrier entry process is performed on the substrate 100, and after the substrate 100 enters the quartz carrier, the temperature is raised, the doping source is deposited on the first surface 1 of the substrate 100, and oxygen is flowed in. In some embodiments, the doping source may be nitrogen gas carrying phosphorus trichloride. As shown in FIG. 16, in this step, oxygen reacts with the polycrystalline silicon and converts a part of the thickness of the intrinsic silicon layer 30 into a glass layer 31, and the glass layer 31 is silicon oxide containing a first doping element. For example, if the first doping element is phosphorus, the glass layer 31 is silicon phosphorus glass, that is, silicon oxide containing phosphorus. As shown in FIG. 17, after a large amount of the first doping element is accumulated in the glass layer 31, the temperature is raised and the first doping element accumulated in the glass layer 31 is diffused in a nitrogen atmosphere to diffuse into the intrinsic polycrystalline silicon to form an initial silicon doped layer 32.

[0145] As shown in FIG. 18, in the second doping process, the glass layer 31 is reserved, and laser light is used to irradiate the glass layer 31, so that the first doping element in the laser-treated glass layer 31 is re-diffused into a part of the initial silicon-doped layer 32 to form a first doped conductive layer 120 and a silicon-doped layer 33.

[0146] As shown in FIG. 19 , in the third doping process, the glass layer 31 is still retained, and a portion of the glass layer 31 is irradiated with laser light, so that the first doping element in the laser-treated glass layer 31 is re-diffused into a portion of the silicon-doped layer 33 to form a first portion 11 and a second portion 12.

[0147] In some embodiments, the laser used in the laser process may be an infrared laser, a green laser, or an ultraviolet laser, which may be generated from a CO2 laser, an excimer laser, a titanium sapphire laser, a semiconductor laser, a copper vapor laser, or any other laser capable of emitting laser light.

[0148] The surface of the glass layer 31 is irradiated with laser light emitted from a laser, and the first doping element in the glass layer 31 diffuses into the initial silicon doped layer 32 or the silicon doped layer 33 due to the laser thermal effect.

[0149] After forming the first portion 11 and the second portion 12, the glass layer 31 is removed. The glass layer 31 can be removed by an acid cleaning process.

[0150] 21 , in some embodiments, before the step of forming the second doped conductive layer 130, further includes forming a blocking layer 150 located on a surface of the first doped conductive layer 120 away from the substrate 100, and the material of the blocking layer 150 includes at least one of silicon oxide, silicon nitride, silicon oxynitride, or silicon carbide. The blocking layer 150 serves to block the diffusion of the doping element in the second doped conductive layer 130 into the first doped conductive layer 120, and can maintain a small doping element concentration in the first doped conductive layer 120.

[0151] In some embodiments, a method of forming the first doped conductive layer 120, the second doped conductive layer 130, and the blocking layer 150 includes the following.

[0152] 20, a first intrinsic silicon layer 41 is formed on the surface of the tunnel layer 110. In some embodiments, the first intrinsic silicon layer 41 may be any of polycrystalline silicon, amorphous silicon, single crystal silicon, or silicon carbide. In some embodiments, the first intrinsic silicon layer 41 may be formed on the surface of the tunnel layer 110 using a deposition process, which may be, for example, an atomic layer deposition process.

[0153] As shown in FIG. 21 , a blocking layer 150 is formed on a surface of the first intrinsic silicon layer 41. In some embodiments, the blocking layer 150 can be formed using a deposition process, for example, an atomic layer deposition process or a chemical vapor deposition process. In some embodiments, the blocking layer 150 can be formed on the entire surface of the first intrinsic silicon layer 41 and directly faces the first portion 11 and the second portion 12 that will be formed later. In some embodiments, the blocking layer 150 can be formed on only a portion of the surface of the first intrinsic silicon layer 41 and directly faces the second portion 12 that will be formed later.

[0154] 21, a second intrinsic silicon layer 42 is formed on the surface of the blocking layer 150. In some embodiments, the second intrinsic silicon layer 42 may be any of polycrystalline silicon, amorphous silicon, single crystal silicon, or silicon carbide. In some embodiments, the second intrinsic silicon layer 42 may be formed on the surface of the tunnel layer 110 using a deposition process, which may be, for example, an atomic layer deposition process.

[0155] A doping source containing a first doping element is deposited on the surface of the second intrinsic silicon layer 42 away from the substrate 100. At the same time as depositing the doping source, oxygen gas is introduced to convert a portion of the second intrinsic silicon layer 42 into a glass layer 31. The glass layer 31 is silicon oxide containing the first doping element.

[0156] In some embodiments, the doping source may be an N-type doping source and the first doping element may be an N-type doping element. In some embodiments, the N-type doping source may be an element or compound containing a pentavalent element, such as phosphorus or a phosphorus-containing compound, such as phosphorus trichloride.

[0157] Before the step of depositing the doping source, the substrate 100 is subjected to a quartz carrier entry step, and after entering the quartz carrier, the substrate 100 is heated to a first preset temperature, which may be 500° C. to 900° C. After heating to the first preset temperature, the doping source is deposited on the first surface 1 of the substrate 100, oxygen gas is introduced, and the deposition time of the doping source is 50 s to 800 s, and in some embodiments, the doping source may be nitrogen gas containing phosphorus trichloride, where the concentration of phosphorus trichloride may be 0.1% to 3 wt%, and the flow rate of the nitrogen gas may be 2000 sccm to 4000 sccm.

[0158] 22, in the above steps, oxygen reacts with silicon to convert the second intrinsic silicon layer 42 having a certain thickness into a glass layer 31, and the glass layer 31 is a silicon oxide containing a first doping element. For example, if the first doping element is phosphorus, the glass layer 31 is a phosphorus silicon glass, i.e., a phosphorus-containing silicon oxide, and a large amount of the first doping element is accumulated in the glass layer 31.

[0159] 23, a first doping process is performed, the first doping element accumulated in the glass layer 31 is diffused into the first intrinsic silicon layer 41 to form the first doped conductive layer 120, and the first doping element is diffused into the second intrinsic silicon layer 42 excluding the glass layer 31 to form the initial second doped conductive layer 43. In some embodiments, the first doping process is performed after the temperature is raised to a second preset temperature, and the second preset temperature is higher than the first preset temperature, for example, 900°C to 1200°C, and diffusion is performed in a nitrogen gas atmosphere at the same time, and the first doping element accumulated in the glass layer 31 is diffused into the first intrinsic silicon layer 41 to form the first doped conductive layer 120.

[0160] As can be seen, due to the presence of the blocking layer 150, in the process in which the first doping element in the glass layer 31 diffuses from the second intrinsic silicon layer 42 to the first intrinsic silicon layer 41, the blocking layer 150 acts as a barrier against the first doping element, and the number of doping elements diffusing into the first intrinsic silicon layer 41 is smaller than the number of doping elements diffusing into the second intrinsic silicon layer 42. As a result, the doping element concentration of the formed first doped conductive layer 120 is smaller than the doping element concentration of the initial second doped conductive layer 43.

[0161] As shown in Figures 24 and 25, a second doping process is performed on a portion of the glass layer 31, and the first doping element in the glass layer 31 that has undergone the second doping process diffuses into the initial second doped conductive layer 43 along a direction perpendicular to the first surface 1, converting this portion of the initial second doped conductive layer 43 into the second portion 12 of the second doped conductive layer 130, and the remaining portion of the initial second doped conductive layer 43 forms the first portion 11.

[0162] As shown in FIG. 24 , in some embodiments, before performing the second doping process, a mask layer 50 is formed on the surface of the glass layer 31, the mask layer 50 has a first opening 51, and the first opening 51 is exposed from a portion of the surface of the glass layer 31, and in some embodiments, a photoetching process can be performed on the mask layer 50 to form the first opening 51.

[0163] In some embodiments, the material of mask layer 50 may be either silicon oxide or silicon oxynitride, and a deposition process may be used to form mask layer 50 .

[0164] 25, in some embodiments, a second doping step is performed on the initial second doped conductive layer 43 (see FIG. 24) along the first opening 51, and the first doping element in the glass layer 31 directly facing the first opening 51 is diffused into the initial second doped conductive layer 43 to form the second portion 12 having a relatively high doping concentration, and the remaining part of the initial second doped conductive layer 43 is blocked by the mask layer 50. As a result, the doping element in the glass layer 31 hardly diffuses into this part of the initial second doped conductive layer 43, and the remaining part of the initial second doped conductive layer 43 forms the first portion 11 having a relatively low doping concentration.

[0165] As can be easily understood, since the doping element concentration of the initial second doped conductive layer 43 is greater than the doping element concentration of the first doped conductive layer 120, the doping element concentrations of the formed first portion 11 and second portion 12 are both greater than the doping element concentration of the second doped conductive layer 130.

[0166] In some embodiments, the second doping step includes a laser step. The parameters of the laser step include a laser wavelength of 300 nm to 532 nm, for example, 300 nm to 330 nm, 330 nm to 350 nm, 350 nm to 380 nm, 380 nm to 420 nm, 420 nm to 480 nm, or 480 nm to 532 nm, a laser frequency of 120 kHz to 1500 kHz, for example, 120 kHz to 180 kHz, 180 kHz to 240 kHz, 240 kHz to 330 kHz, 330 kHz to 480 kHz, 480 kHz to 600 kHz, 600 kHz to 700 kHz, 700 kHz to 800 kHz, 800 kHz to 900 kHz, 900 kHz to 1050 kHz, or 1050 kHz to 1200 kHz, and a scan line frequency of 100 kHz to 1200 kHz. The speed is 1000mm / s to 40000mm / s, for example, 1000mm / s to 2000mm / s, 2000mm / s to 5000mm / s, 5000mm / s to 6000mm / s, 6000mm / s to 7500mm / s, 7500mm / s to 9000mm / s, 9000mm / s to 12000mm / s, 12000mm / s to 18000mm / s, 1800 0mm / s~25000mm / s, 25000mm / s~28000mm / s, 28000mm / s~32000mm / s, 32000mm / s~34000mm / s, 34000mm / s~36000mm / s, 36000mm / s~38500mm / s or 38500mm / s~40000mm / s, and the laser energy is 0.1J / cm 2 ~1.5J / cm 2 For example, 0.1 J / cm 2 ~0.3J / cm 2 , 0.3J / cm 2 ~0.5J / cm 2 , 0.5J / cm 2 ~0.8J / cm 2 , 0.8J / cm 2 ~1J / cm 2 , 1J / cm 2 ~1.2J / cm 2 , 1.2J / cm 2 ~1.3J / cm 2 or 1.3 J / cm 2 ~1.5J / cm2 Within the above range, a sufficient laser thermal effect can be generated so that the first doping element in the glass layer 31 diffuses into the initial second doped conductive layer 43 by the laser thermal effect. In addition, within the above range, the degree of diffusion of the first doping element in the glass layer 31 is not too large, and the problem of the first doping element diffusing too much into the first doped conductive layer 120, resulting in an increase in the doping element concentration of the first doped conductive layer 120, is prevented.

[0167] In some embodiments, the parameters of the laser process are controlled to diffuse the first doping element into the first doped conductive layer 120, forming a third portion 13 (see FIG. 4) facing the first portion 11 and a fourth portion 14 (see FIG. 4) facing the second portion 12 in the first doped conductive layer 120, the fourth portion 14 facing the second portion 12, and in the step of performing the laser process to form the second portion 12, a portion of the first doping element diffuses into the first doped conductive layer 120 facing the second portion 12 to form the fourth portion 14 having a relatively high doping element concentration, and the remaining portion of the first doped conductive layer 120 forms the third portion 13 having a relatively low doping element concentration.

[0168] In some embodiments, the parameters of the laser process can be controlled so that the formed crystal grains of the second portion 12 are recrystallized and the average crystal grain size in the second portion 12 is smaller than the average crystal grain size in the first portion 11. This increases the amount of the first doping element diffusing into the second portion 12, making it easier to realize that the doping element concentration in the second portion 12 is greater than the doping element concentration in the first portion 11. In some embodiments, the parameters of the laser process can be controlled so as to recrystallize the crystal grains of the second portion 12 and the fourth portion 14, thereby realizing that the average crystal grain size in the fourth portion 14 is smaller than the average crystal grain size in the third portion 13 and that the doping element concentration in the fourth portion 14 is greater than the doping element concentration in the third portion 13.

[0169] In some embodiments, the laser used in the laser process may be any of an infrared laser, a green laser, or an ultraviolet laser, which may be generated from a CO2 laser, an excimer laser, a Ti:Sapphire laser, a semiconductor laser, a copper vapor laser, or any other laser capable of emitting laser light.

[0170] The surface of the glass layer 31 is irradiated with laser light emitted from a laser, and the first doping element in the glass layer 31 is diffused into the initial second doped conductive layer 43 by the laser thermal effect.

[0171] In some embodiments, after forming the first portion 11 and the second portion 12, the sacrificial layer and the glass layer 31 are removed. In some embodiments, an acid cleaning process may be used to remove the glass layer 31, for example, an HCL solution or an HF solution may be used to clean the sacrificial layer and the glass layer 31 and remove the sacrificial layer and the glass layer 31.

[0172] 26, in some embodiments, the method for manufacturing a solar cell further includes forming a first passivation layer 160 on a surface of the second doped conductive layer 130 away from the substrate 100. In some embodiments, the first passivation layer 160 may have a single layer structure. In some embodiments, the first passivation layer 160 may have a multi-layer structure.

[0173] In some embodiments, the first passivation layer 160 is a single-layer structure, and the material of the first passivation layer 160 may be any one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride. In some embodiments, the first passivation layer 160 is a multi-layer structure, and the material of the first passivation layer 160 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0174] In some embodiments, the method of forming the first passivation layer 160 may include forming the first passivation layer 160 on the surface of the second doped conductive layer 130 using a PECVD (Plasma Enhanced Chemical Vapor Deposition) method.

[0175] In some embodiments, the method further includes forming a second passivation layer 180 on the surface of the emitter 170, and the second passivation layer 180 can have a good passivation effect. In some embodiments, the second passivation layer 180 can have a single-layer structure. In some embodiments, the second passivation layer 180 can have a multi-layer structure.

[0176] In some embodiments, the second passivation layer 180 is a single-layer structure, and the material of the second passivation layer 180 may be any of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride. In some embodiments, the second passivation layer 180 is a multi-layer structure, and the material of the second passivation layer 180 may be at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0177] In some embodiments, a PECVD process may be used to form a second passivation layer 180 on the surface of the emitter 170 .

[0178] As shown in FIG. 9, a plurality of first electrodes are formed, and each of the first electrodes 140 among the plurality of first electrodes extends along a predetermined direction X, each of the first electrodes 140 corresponds one-to-one to each of the second portions 12, and one first electrode 140 is in electrical contact with the corresponding second portion 12.

[0179] In some embodiments, a method of forming the first electrode 140 includes the following.

[0180] A metal paste is formed on the side of each second portion away from the substrate 100. In some embodiments, a screen printing process can be used to print the metal paste on the surface of the first passivation layer 160 facing the second portions. In some embodiments, the metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0181] A sintering process is performed on the metal paste, and the metal paste is burned through a portion of the thickness of the second portion 12 from the side of the second portion 12 away from the substrate 100 to form the first electrode 140. In some embodiments, the metal paste includes a material having a highly corrosive component, such as glass, so that during the sintering process, the corrosive component corrodes the first passivation layer 160 and a portion of the second portion 12, and the metal paste penetrates into the first passivation layer 160 and a portion of the second portion 12.

[0182] In some embodiments, the method further includes forming a second electrode 190, where the second electrode 190 penetrates the second passivation layer 180 and electrically contacts the emitter 170. In some embodiments, the process of forming the second electrode 190 may be the same as the process of forming the first electrode 140, and the above description regarding the method of forming the first electrode 140 may be referred to.

[0183] Although the present application has been disclosed above in preferred embodiments, it does not limit the scope of the claims, and a person skilled in the art may make some possible variations and modifications without departing from the idea of ​​the present application, so the protection scope of the present application should be in accordance with the scope defined by the claims of the present application.

[0184] Those skilled in the art will understand that the above embodiments are specific examples for implementing the present application, but various changes in form and details are possible in practice without departing from the spirit and scope of the present application. Since any person skilled in the art can make changes and modifications without departing from the spirit and scope of the present application, the scope of protection of the present application should be based on the scope limited by the claims.

Claims

1. a substrate having a first surface; a tunnel layer formed on the first surface; a first doped conductive layer formed on a surface of the tunnel layer remote from the substrate; a second doped conductive layer formed on a side of the first doped conductive layer away from the substrate, the second doped conductive layer including a plurality of first portions and a plurality of second portions, the first portions and the second portions being alternately arranged along a predetermined direction and a direction perpendicular to a thickness direction of the second doped conductive layer, and the first portions and the second portions both extending along the predetermined direction, wherein a doping element concentration of the first doped conductive layer is lower than a doping element concentration of the first portions, and a doping element concentration of the first portions is lower than a doping element concentration of the second portions; a plurality of first electrodes, each of which extends along the predetermined direction, each of the first electrodes and each of the second portions are in one-to-one correspondence with each other, and each of the first electrodes is in electrical contact with a corresponding one of the second portions; the predetermined direction is a direction parallel to the first surface and perpendicular to a direction in which the first portions and the second portions are alternately arranged, a ratio of a doping element concentration of the first portion to a doping element concentration of the second portion is 1:50 to 3:4; the first doped conductive layer includes a plurality of third portions and a plurality of fourth portions, the third portions and the fourth portions being alternately arranged along the predetermined direction and a direction perpendicular to a thickness direction of the second doped conductive layer, the predetermined direction being parallel to the first surface, the third portions and the fourth portions both extending along the predetermined direction, one of the third portions facing one of the first portions, one of the fourth portions facing one of the second portions, and a doping element concentration of the third portions being lower than a doping element concentration of the fourth portions; A solar cell characterized by:

2. a ratio of a doping element concentration of the first doped conductive layer to a doping element concentration of the second portion is 1:100 to 1:2; The solar cell according to claim 1 .

3. When the doping element type of the first doped conductive layer is N-type, the ratio of the doping element concentration of the third portion to the doping element concentration of the fourth portion is 1:30 to 5:6, and when the doping element type of the first doped conductive layer is P-type, the ratio of the doping element concentration of the third portion to the doping element concentration of the fourth portion is 1:100 to 2:

3. The solar cell according to claim 2 .

4. the ratio of the doping element concentration of the fourth portion to the doping element concentration of the second portion is 1:10 to 5:6; The solar cell according to claim 3 .

5. a blocking layer, the blocking layer being located between the first doped conductive layer and the second doped conductive layer, the surface of the blocking layer facing the substrate being in contact with the surface of the first doped conductive layer away from the substrate, and the surface of the blocking layer facing the substrate being in contact with the surface of the second doped conductive layer away from the substrate.

5. The solar cell according to claim 1, wherein the first and second electrodes are arranged in a first direction.

6. a surface of the barrier layer facing away from the substrate is in contact with each of the second portions, and an orthogonal projection of the barrier layer on the first surface overlaps with an orthogonal projection of each of the second portions on the first surface. The solar cell according to claim 5 .

7. a surface of the barrier layer away from the substrate is in contact with each of the first portions and each of the second portions, and an orthogonal projection of the barrier layer on the first surface overlaps with an orthogonal projection of each of the first portions on the first surface and an orthogonal projection of each of the second portions on the first surface; The solar cell according to claim 5 .

8. The material of the blocking layer includes at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride; The solar cell according to claim 5 .

9. The material of the first doped conductive layer includes at least one of amorphous silicon, polycrystalline silicon, or silicon carbide, and the material of the second doped conductive layer includes at least one of amorphous silicon, polycrystalline silicon, or silicon carbide. The solar cell according to claim 8 .

10. the first doped conductive layer is made of first polycrystalline silicon, the first portion is made of second polycrystalline silicon, the second portion is made of third polycrystalline silicon, and an average crystal grain size of the first polycrystalline silicon is larger than an average crystal grain size of the second polycrystalline silicon and is also larger than an average crystal grain size of the third polycrystalline silicon; The solar cell according to claim 9 .

11. the third portion is made of fourth polycrystalline silicon, the fourth portion is made of fifth polycrystalline silicon, the first portion is made of second polycrystalline silicon, and the second portion is made of third polycrystalline silicon, wherein an average crystal grain size of the fourth polycrystalline silicon is larger than an average crystal grain size of the fifth polycrystalline silicon, an average crystal grain size of the fifth polycrystalline silicon is larger than an average crystal grain size of the third polycrystalline silicon, and an average crystal grain size of the second polycrystalline silicon is larger than an average crystal grain size of the third polycrystalline silicon; The solar cell according to claim 2 .

12. a ratio of a thickness of the first doped conductive layer to a thickness of the second doped conductive layer is 2:1 to 1:12; 5. The solar cell according to claim 1, wherein the first and second electrodes are arranged in a first direction.

13. At least one battery string formed by connecting a plurality of solar cells according to claim 1; at least one encapsulation layer for covering the at least one battery string; and at least one cover plate for covering the at least one sealing layer. A photovoltaic module comprising:

14. Providing a substrate having a first surface; forming a tunnel layer on the first surface; forming a first doped conductive layer on a surface of the tunnel layer remote from the substrate; forming a second doped conductive layer on a side of the first doped conductive layer away from the substrate, the second doped conductive layer including a plurality of first portions and a plurality of second portions, the first portions and the second portions being alternately arranged along a predetermined direction and a direction perpendicular to a thickness direction of the second doped conductive layer, and the first portions and the second portions both extending along the predetermined direction, wherein a doping element concentration of the first doped conductive layer is lower than a doping element concentration of the first portions, and a doping element concentration of the first portions is lower than a doping element concentration of the second portions; forming a plurality of first electrodes, each of the plurality of first electrodes extending along the predetermined direction, each of the first electrodes corresponding to each of the second portions in a one-to-one relationship, and one of the first electrodes being in electrical contact with a corresponding one of the second portions; the predetermined direction is a direction parallel to the first surface and perpendicular to a direction in which the first portions and the second portions are alternately arranged, a ratio of a doping element concentration of the first portion to a doping element concentration of the second portion is 1:50 to 3:4; the first doped conductive layer includes a plurality of third portions and a plurality of fourth portions, the third portions and the fourth portions being alternately arranged along the predetermined direction and a direction perpendicular to a thickness direction of the second doped conductive layer, the predetermined direction being parallel to the first surface, the third portions and the fourth portions both extending along the predetermined direction, one of the third portions facing one of the first portions, one of the fourth portions facing one of the second portions, and a doping element concentration of the third portions being lower than a doping element concentration of the fourth portions; A method for producing a solar cell comprising the steps of:

15. Before the step of forming the second doped conductive layer, the method further includes forming a blocking layer located on a surface of the first doped conductive layer away from the substrate, the material of the blocking layer including at least one of silicon oxide, silicon nitride, silicon oxynitride, or silicon carbide. The method for producing a solar cell according to claim 14 .

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