Back contact solar cell, preparation method thereof and photovoltaic module

Abstract

The invention discloses a back contact solar cell, a preparation method thereof and a photovoltaic module, and belongs to the technical field of solar cells. The back contact solar cell includes: a silicon substrate; a first region of the first surface of the silicon substrate comprises a first doped polycrystalline silicon layer; a second region of the first surface of the silicon substrate comprises a second doped polycrystalline silicon layer; the second surface is provided with a passivation antireflection layer; the first doped polycrystalline silicon layer comprises a first doping element, the second doped polycrystalline silicon layer comprises a second doping element, the first doped polycrystalline silicon layer is a P-type doped polycrystalline silicon layer, and the second doped polycrystalline silicon layer is an N-type doped polycrystalline silicon layer. The impurity concentration N110, corresponding to the first region, of the silicon substrate, the impurity concentration N130, corresponding to the isolation region, of the silicon substrate and the impurity concentration N120, corresponding to the second region, of the silicon substrate meet the condition that N130 is smaller than or equal to N120lt; n110, the recombination of current carriers in the isolation region can be reduced, so that the efficiency of the back contact solar cell can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and more specifically, to a back-contact solar cell and a preparation method thereof, and a photovoltaic module. Background Art

[0002] Back contact solar (BC) cells refer to solar cells with no electrodes on the light-facing side of the cell, and both the positive and negative electrodes are set on the back side of the cell, which can reduce the shading of the electrodes on the cell, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell. TBC cells are BC cells with Topcon structure for both polarities in the back structure of the cell, which have high open circuit voltage and fill factor while having high current, thus having high cell efficiency.

[0003] The concentration of impurities in the silicon substrate of the TBC cell is crucial to the efficiency of the TBC cell. Therefore, how to control the concentration of impurities to further improve the efficiency of the TBC cell is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present application is to provide a back-contact solar cell to reduce the concentration of impurities in a silicon substrate and improve the efficiency of the back-contact solar cell.

[0005] In order to achieve the above objectives, the present application provides a back-contact solar cell and a preparation method thereof, and a photovoltaic module.

[0006] In a first aspect, a back-contact solar cell is provided, comprising: a silicon substrate, the silicon substrate having a first surface and a second surface opposite to each other, the first surface being provided with a first region, a second region and an isolation region located between the first region and the second region; the first region comprising a first tunneling oxide layer, a first doped polysilicon layer, a first passivation layer and a first electrode sequentially arranged along the thickness direction of the silicon substrate; the second region comprising a second tunneling oxide layer, a second doped polysilicon layer, a second passivation layer and a second electrode sequentially arranged along the thickness direction of the silicon substrate; the second surface being provided with a passivation anti-reflection layer; the first doped polysilicon layer comprising a first doping element, the second doped polysilicon layer comprising a second doping element, the first doped polysilicon layer being a P-type doped polysilicon layer, and the second doped polysilicon layer being an N-type doped polysilicon layer; wherein a surface of the isolation region close to the second region comprises the second doping element, and the sum of the concentrations of the first doping element and the second doping element on a surface of the silicon substrate close to the passivation anti-reflection layer is less than 1×10 16 atom / cm 3; The silicon substrate includes impurities, and the impurities include at least one of iron, nickel, and chromium. The concentration N of the impurities in the silicon substrate corresponding to the first region 110 , the concentration N of the impurities in the silicon substrate corresponding to the isolation region 130 , the concentration N of the impurities in the silicon substrate corresponding to the second region 120 satisfy: N 130 ≤ N 120 < N 110 .

[0007] In an embodiment of the present application, the first doped polysilicon layer is a P-type doped polysilicon layer, the second doped polysilicon layer is an N-type doped polysilicon layer, the surface of the isolation region close to the second region includes a second doping element, and the sum of the concentrations of the first doping element and the second doping element in the passivation antireflection layer is less than 1×10 16 atom / cm 3 , and the concentrations of the impurities in each region of the silicon substrate satisfy the above range, which is beneficial to reducing the recombination of carriers in the isolation region, and thus beneficial to improving the efficiency of the back contact solar cell.

[0008] In some embodiments, the diffusion depth of the second doping element in the silicon substrate is less than the diffusion depth of the first doping element in the silicon substrate. The diffusion depth of the first doping element in the silicon substrate is 0.05 μm to 0.6 μm, and the diffusion depth of the second doping element in the silicon substrate is 0.03 μm to 0.3 μm. In this way, it is beneficial to reduce the concentration of impurities in the silicon substrate, reduce the recombination of minority carriers, increase the lifetime of minority carriers, and at the same time avoid or reduce the damage to the first tunneling oxide layer and the second tunneling oxide layer, thereby being beneficial to improving the efficiency of the back contact solar cell.

[0009] In some embodiments, the diffusion depth of the first doping element in the silicon substrate is 0.1 μm to 0.2 μm, and the diffusion depth of the second doping element in the silicon substrate is 0.03 μm to 0.08 μm.

[0010] By controlling the diffusion depths of the first doping element and the second doping element in the silicon substrate to satisfy the above range, the concentration of impurities in the silicon substrate can be reduced, and the damage to the first tunneling oxide layer and the second tunneling oxide layer can be avoided or reduced, which is beneficial to improving the efficiency of the back contact solar cell.

[0011] In some embodiments, the diffusion depth of the second doping element in the silicon substrate is 0.03 μm to 0.05 μm. In this way, the damage to the second tunneling oxide layer can be further reduced while reducing the concentration of impurities in the silicon substrate, which is beneficial to improving the efficiency of the back contact solar cell.

[0012] In some embodiments, the concentration N of impurities in the silicon substrate corresponding to the first region 110 , the concentration N of impurities in the silicon substrate corresponding to the isolation region 130 , and the concentration N of impurities in the silicon substrate corresponding to the second region 120 satisfy at least one of the following conditions: 1×10 10 atom / cm 3 ≤N 110 ≤1×10 16 atom / cm 3 ; 1×10 8 atom / cm 3 ≤N 120 ≤1×10 16 atom / cm 3 ; 1×10 8 atom / cm 3 ≤N 130 ≤1×10 16 atom / cm 3 .

[0013] In the above technical solution, the first region, the second region, and the isolation region of the silicon substrate have a low impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0014] In some embodiments, the concentration N of impurities on the surface of the silicon substrate close to the passivation antireflection layer 101 satisfies: N 101 ≤N 120 <N 110 . In this way, the surface of the silicon substrate close to the passivation antireflection layer has a low impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0015] In some embodiments, the concentration N of impurities on the surface of the silicon substrate close to the passivation antireflection layer 101 satisfies 1×10 10 atom / cm 3 ≤N 101 ≤1×10 15 atom / cm 3 . In this way, the surface of the silicon substrate close to the passivation antireflection layer has a low impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0016] In some embodiments, the concentration N of impurities on the surface of the silicon substrate close to the passivation antireflection layer 101The concentration N of impurities in the isolation region corresponding to the silicon substrate 130 is the same. In this way, the surface of the silicon substrate close to the passivation antireflection layer has a lower impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0017] In some embodiments, along the thickness direction of the silicon substrate, in the direction pointing from the central position of the silicon substrate to the first surface or the second surface, the concentration of impurities in the silicon substrate gradually increases. In this way, the central position of the silicon substrate has a lower impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0018] In some embodiments, the first doping element includes element B, and the second doping element includes element P. Element B and element P are beneficial to absorbing impurities in the silicon substrate, which is beneficial to reducing the concentration of impurities in the silicon substrate, so that the back-contact solar cell has a higher efficiency.

[0019] In a second aspect, a method for manufacturing a back-contact solar cell is provided, including: preparing a first tunneling oxide layer and a first polysilicon layer on a first surface of a silicon substrate; doping a first doping source into the silicon substrate provided with the first polysilicon layer by means of thermal diffusion to obtain the first doped polysilicon layer, wherein the thermal diffusion temperature of the first doping source is 910°C to 1000°C, and the thermal diffusion time of the first doping source is 10 min to 60 min; etching a second region of the silicon substrate provided with the first doped polysilicon layer and the first tunneling oxide layer to expose the second region of the silicon substrate; preparing a second tunneling oxide layer and a second polysilicon layer on a first surface of the second region of the silicon substrate; doping a second doping source into the silicon substrate provided with the second polysilicon layer by means of thermal diffusion to obtain the second doped polysilicon layer, wherein the thermal diffusion temperature of the second doping source is 850°C to 920°C, and the thermal diffusion time of the second doping source is 3 min to 60 min; providing an isolation region between the first doped polysilicon layer and the second doped polysilicon layer; respectively providing a first passivation layer and a second passivation layer on the surfaces of the first doped polysilicon layer and the second doped polysilicon layer; and respectively preparing a first electrode and a second electrode on the surfaces of the first passivation layer and the second passivation layer.

[0020] In the above embodiments, by controlling the thermal diffusion time and thermal diffusion temperature of the first doping source and the second doping source, it is beneficial for the doping elements to diffuse to the corresponding positions of the silicon substrate, so that a better effect of absorbing impurities in the silicon substrate can be achieved, reducing the impurities in the silicon substrate, which is beneficial to improving the efficiency of the back-contact solar cell. In addition, this manufacturing method does not require additional steps to process the back-contact solar cell, which is beneficial to simplifying the manufacturing process of the back-contact solar cell.

[0021] In some embodiments, the thermal diffusion temperature of the first doping source is 960°C to 980°C, and the thermal diffusion time of the first doping source is 20 min to 40 min; the thermal diffusion temperature of the second doping source is 890°C to 910°C, and the thermal diffusion time of the second doping source is 5 min to 30 min. In this way, it is beneficial to further reduce the concentration of impurities in the silicon substrate, and at the same time avoid or reduce the damage to the first tunneling oxide layer and the second tunneling oxide layer, so that the back-contact solar cell has a higher efficiency.

[0022] In some embodiments, the first doping source includes BCl3, and the second doping source includes POCl3. Elements B and P are beneficial to absorb impurities in the silicon substrate, which is beneficial to reducing the concentration of impurities in the silicon substrate, so that the back-contact solar cell has a higher efficiency.

[0023] In a third aspect, a photovoltaic module is provided, including the back-contact solar cell in the first aspect and any of its embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the drawings.

[0025] Figure 1 It is a schematic structural diagram of a back-contact solar cell according to an embodiment of the present application; Figure 2 It is a schematic diagram of a method for manufacturing a back-contact solar cell according to an embodiment of the present application.

[0026] Reference numerals: 100: back-contact solar cell; 1: silicon substrate; 110: first region; 120: second region; 130: isolation region; 2: first tunneling oxide layer; 3: first doped polysilicon layer; 71: first passivation layer; 8: first electrode; 4: second tunneling oxide layer; 5: second doped polysilicon layer; 72: second passivation layer; 9: second electrode; 6: passivation antireflection layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The back-contact solar cell, its preparation method, and the implementation manner of the photovoltaic module of the present application have been described in detail with appropriate reference to the accompanying drawings, but there may be cases where unnecessary details are omitted. For example, there are cases where the detailed description of well-known matters and the repeated description of actually identical structures are omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0028] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The range defined in this way can include or exclude the end values and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are understood to be also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when a certain parameter is expressed as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] If there is no special instruction, all the implementation manners and optional implementation manners of the present application can be combined with each other to form a new technical solution.

[0030] If there is no special instruction, all the technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0031] If there is no special instruction, all the steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0032] Back contact solar (BC) cells refer to solar cells with no electrodes on the light-facing side of the cell, and both the positive and negative electrodes are set on the back side of the cell, which can reduce the shading of the electrodes on the cell, increase the short-circuit current of the cell, and improve the energy conversion efficiency of the cell. TBC cells are BC cells with Topcon structure for both polarities in the back structure of the cell, which have high open circuit voltage and fill factor while having high current, thus having high cell efficiency.

[0033] The concentration of impurities in the silicon substrate of the TBC cell is crucial to the efficiency of the TBC cell. Therefore, how to control the concentration of impurities to further improve the efficiency of the TBC cell is a technical problem that needs to be solved urgently.

[0034] In view of this, an embodiment of the present application provides a back-contact solar cell, comprising: a silicon substrate, the silicon substrate having a first surface and a second surface opposite to each other; the first surface is provided with a first region, a second region and an isolation region located between the first region and the second region; the first region comprises a first tunneling oxide layer, a first doped polycrystalline silicon layer, a first passivation layer and a first electrode sequentially arranged along the thickness direction of the silicon substrate; the second region comprises a second tunneling oxide layer, a second doped polycrystalline silicon layer, a second passivation layer and a second electrode sequentially arranged along the thickness direction of the silicon substrate; the second surface is provided with a passivation anti-reflection layer; the first doped polycrystalline silicon layer comprises a first doping element, the second doped polycrystalline silicon layer comprises a second doping element, the first doped polycrystalline silicon layer is a P-type doped polycrystalline silicon layer, and the second doped polycrystalline silicon layer is an N-type doped polycrystalline silicon layer; wherein a surface of the isolation region close to the second region comprises the second doping element, and the sum of the concentrations of the first doping element and the second doping element of the surface of the silicon substrate close to the passivation anti-reflection layer is less than 1×10 16 atom / cm 3 The silicon substrate includes impurities, the impurities include at least one of iron, nickel, and chromium, and the concentration of impurities in the first region of the silicon substrate corresponding to N 110 , the concentration of impurities in the isolation region of the silicon substrate N 130 , the concentration N of impurities in the second region of the silicon substrate 120 Satisfy: N 130 ≤N 120 <N 110 This helps reduce the recombination of carriers in the isolation region, thereby improving the efficiency of the back-contact solar cell.

[0035] Figure 1 FIG. 1 is a schematic diagram of the structure of a back-contact solar cell according to an embodiment of the present application. Figure 1 As shown, the back-contact solar cell 100 includes a silicon substrate 1 having a first surface and a second surface opposite to each other.

[0036] The first surface is provided with a first region 110, a second region 120, and an isolation region 130 located between the first region 110 and the second region 120.

[0037] Along the first direction, the isolation region 130 is located between the first region 110 and the second region 120 to insulate and isolate the first region 110 and the second region 120. For example, the first direction is Figure 1 the x direction in

[0038] The isolation region 130 may be a groove that is recessed from the first surface toward the second surface. As an example, the depth of the groove is 1 μm to 5 μm. For example, the depth of the groove is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or any value within the above range.

[0039] The first region 110 includes a first tunneling oxide layer 2, a first doped polysilicon layer 3, a first passivation layer 71, and a first electrode 8 that are sequentially arranged along the thickness direction of the silicon substrate 1.

[0040] The material of the first tunneling oxide layer 2 may include SiO2, the material of the first doped polysilicon layer 3 may be polysilicon with a doping element, the material of the first passivation layer 71 may include aluminum oxide (Al2O3), silicon nitride (SiN x ), silicon oxynitride (SiON), or silicon oxide (SiO y ), or one or more of them, and the material of the first electrode 8 may include a metal, such as silver.

[0041] The second region 120 includes a second tunneling oxide layer 4, a second doped polysilicon layer 5, a second passivation layer 72, and a second electrode 9 that are sequentially arranged along the thickness direction of the silicon substrate 1.

[0042] The second doped polysilicon layer 5 and the first doped polysilicon layer 3 have opposite polarities, and the first electrode 8 and the second electrode 9 can be used to collect majority carriers and minority carriers, respectively.

[0043] The material of the second tunneling oxide layer 4 may include SiO2, the material of the second doped polysilicon layer 5 may be polysilicon with a doping element, the material of the second passivation layer 72 may include aluminum oxide (Al2O3), silicon nitride (SiN x ), silicon oxynitride (SiON), or silicon oxide (SiO y ), or one or more of them, and the material of the second electrode 9 may include a metal, such as silver.

[0044] A passivation and antireflection layer 6 is provided on the second surface of the silicon substrate. The provision of the passivation and antireflection layer 6 on the second surface is beneficial to reducing the reflection of sunlight on the second surface, facilitating the back-contact solar cell to absorb more sunlight and improving the efficiency.

[0045] The first doped polysilicon layer 3 includes a first doping element, and the second doped polysilicon layer 5 includes a second doping element. The first doped polysilicon layer 3 is a P-type doped polysilicon layer, and the second doped polysilicon layer 5 is an N-type doped polysilicon layer.

[0046] Through the setting of the first doping element, the first doped polysilicon layer 3 is a P-type doped polysilicon layer. Through the setting of the second doping element, the second doped polysilicon layer 5 is an N-type doped polysilicon layer. For example, the first doping element includes element B, and the second doping element includes element P.

[0047] In the process of preparing the first doped polysilicon layer 3 with the first doping element and preparing the second doped polysilicon layer 5 with the second doping element, the first doping element and the second doping element will diffuse into the silicon substrate. The doping element has a certain ability to absorb impurities, which can reduce the concentration of impurities in the silicon substrate.

[0048] The surface of the isolation region 130 close to the second region 120 includes the second doping element.

[0049] As an example, after doping the first polysilicon layer and the second polysilicon layer with the first doping element and the second doping element, the surface of the isolation region 130 close to the second region 120 includes the second doping element. For example, when the isolation region 130 is a groove, the side wall of the groove close to the second region 120 contains the second doping element.

[0050] The sum of the concentrations of the first doping element and the second doping element on the surface of the silicon substrate 1 close to the passivation and antireflection layer 6 is less than 1×10 16 atom / cm 3 . For example, the concentrations of the first doping element and the second doping element on the surface of the silicon substrate 1 close to the passivation and antireflection layer 6 are 0 or close to 0, that is to say, the surface of the silicon substrate 1 close to the passivation and antireflection layer 6 hardly includes the first doping element and the second doping element.

[0051] The silicon substrate 1 includes impurities, and the impurities include at least one of iron, nickel, and chromium. The concentration N 110 of the impurities in the silicon substrate 1 corresponding to the first region 110, the concentration N 130 of the impurities in the silicon substrate 1 corresponding to the isolation region 130, and the concentration N 120 of the impurities in the silicon substrate 1 corresponding to the second region 120 satisfy: N 130 ≤N 120 <N 110 .

[0052] The impurities in the silicon substrate are elements other than silicon and doping elements, such as iron, nickel, and chromium.

[0053] The silicon substrate may have different impurity concentrations at different positions. For example, the impurity concentration corresponding to the first region 110 of the silicon substrate is greater than the impurity concentration corresponding to the second region 120 of the silicon substrate.

[0054] In the embodiments of the present application, the first doped polysilicon layer is a P-type doped polysilicon layer, the second doped polysilicon layer is an N-type doped polysilicon layer, the surface of the isolation region close to the second region includes a second doping element, and the sum of the concentrations of the first doping element and the second doping element in the passivation and antireflection layer is less than 1×10 16 atom / cm 3 , and the impurity concentrations in each region of the silicon substrate satisfy the above range, which is beneficial to reducing the recombination of carriers in the isolation region, thereby being beneficial to improving the efficiency of the back-contact solar cell.

[0055] In some embodiments, the diffusion depth of the second doping element in the silicon substrate 1 is less than the diffusion depth of the first doping element in the silicon substrate 1. The diffusion depth of the first doping element in the silicon substrate 1 is 0.05 μm to 0.6 μm, and the diffusion depth of the second doping element in the silicon substrate 1 is 0.03 μm to 0.3 μm.

[0056] The diffusion depth of the first doping element in the silicon substrate 1 can be 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, or any value within the above range. The diffusion depth of the second doping element in the silicon substrate 1 can be 0.03 μm, 0.04 μm, 0.06 μm, 0.08 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, or any value within the above range.

[0057] The diffusion depth of the first doping element in the silicon substrate can be the distance between the surface of the first tunneling oxide layer 2 away from the silicon substrate and the position in the silicon substrate having the first doping element; the diffusion depth of the second doping element in the silicon substrate can be the distance between the surface of the second tunneling oxide layer 4 away from the silicon substrate and the position in the silicon substrate having the second doping element.

[0058] When the diffusion depth of the first doping element in the silicon substrate is greater than or equal to 0.05 μm, it has a good effect of absorbing impurities in the silicon substrate, which is beneficial to improving the efficiency of the back-contact solar cell; when the diffusion depth of the first doping element in the silicon substrate is less than or equal to 0.6 μm, while having a good effect of absorbing impurities, it can also reduce the damage to the first tunneling oxide layer 2, which is beneficial to improving the efficiency of the back-contact solar cell.

[0059] When the diffusion depth of the second doping element in the silicon substrate is greater than or equal to 0.03 μm, it has a good effect of absorbing impurities in the silicon substrate, which is beneficial to improving the efficiency of the back-contact solar cell; when the diffusion depth of the second doping element in the silicon substrate is less than or equal to 0.3 μm, while having a good effect of absorbing impurities, it can also reduce the damage to the second tunneling oxide layer 4, which is beneficial to improving the efficiency of the back-contact solar cell.

[0060] In some embodiments, the diffusion depth of the first doping element in the silicon substrate 1 is 0.1 μm to 0.2 μm, and the diffusion depth of the second doping element in the silicon substrate 1 is 0.03 μm to 0.8 μm.

[0061] In the above embodiments, by controlling the diffusion depth of the first doping element in the silicon substrate 1 and the diffusion depth of the second doping element in the silicon substrate 1 to meet the above ranges, the concentration of impurities in the silicon substrate 1 can be reduced, and the damage to the first tunneling oxide layer 2 and the second tunneling oxide layer 4 can be avoided or reduced, which is beneficial to improving the efficiency of the back-contact solar cell.

[0062] In some embodiments, the diffusion depth of the second doping element in the silicon substrate 1 is 0.03 μm to 0.05 μm. In this way, while reducing the concentration of impurities in the silicon substrate, the damage to the second tunneling oxide layer can be further reduced, which is beneficial to improving the efficiency of the back-contact solar cell.

[0063] In some embodiments, the impurity concentration N of the silicon substrate 1 corresponding to the first region 110 110 and the impurity concentration N of the silicon substrate 1 corresponding to the isolation region 130 130 and the impurity concentration N of the silicon substrate 1 corresponding to the second region 120 120 satisfy at least one of the following conditions: 1×10 10 atom / cm 3 ≤N 110 ≤1×10 16 atom / cm 3 ; 1×10 8 atom / cm 3 ≤N120 ≤ 1×10 16 atom / cm 3 ; 1×10 8 atom / cm 3 ≤ N 130 ≤ 1×10 16 atom / cm 3 .

[0064] The concentration N of impurities in the silicon substrate 1 corresponding to the first region 110 110 can be 1×10 10 atom / cm 3 , 1×10 11 atom / cm 3 , 1×10 12 atom / cm 3 , 1×10 13 atom / cm 3 , 1×10 14 atom / cm 3 , 1×10 15 atom / cm 3 , 1×10 16 atom / cm 3 or any value within the above range. The concentration N of impurities in the silicon substrate 1 corresponding to the second region 120 120 can be 1×10 8 atom / cm 3 , 1×10 9 atom / cm 3 , 1×10 10 atom / cm 3 , 1×10 11 atom / cm 3 , 1×10 12 atom / cm 3 , 1×10 13 atom / cm 3 , 1×10 14 atom / cm 3 , 1×10 15 atom / cm 3 , 1×10 16 atom / cm 3 or any value within the above range. The concentration N of impurities in the silicon substrate 1 corresponding to the isolation region 130 130 can be 1×10 8 atom / cm 3 , 1×10 9 atom / cm 3 , 1×1010 atoms / cm 3 、1×10 11 atoms / cm 3 、1×10 12 atoms / cm 3 、1×10 13 atoms / cm 3 、1×10 14 atoms / cm 3 、1×10 15 atoms / cm 3 、1×10 16 atoms / cm 3 or any value within the above range.

[0065] In the above technical solution, the first region 110, the second region 120, and the isolation region 130 of the silicon substrate 1 have a low impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0066] In some embodiments, the concentration N of impurities on the surface of the silicon substrate 1 close to the passivation antireflection layer 6 101 satisfies: N 101 ≤ N 120 < N 110 . In this way, the surface of the silicon substrate 1 close to the passivation antireflection layer 6 has a low impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0067] In some embodiments, the concentration N of impurities on the surface of the silicon substrate 1 close to the passivation antireflection layer 6 101 satisfies 1×10 10 atoms / cm 3 ≤ N 101 ≤ 1×10 15 atoms / cm 3 .

[0068] N 101 can be 1×10 10 atoms / cm 3 、1×10 11 atoms / cm 3 、1×10 12 atoms / cm 3 、1×10 13 atoms / cm 3 、1×10 14 atoms / cm 3 、1×10 15 atoms / cm 3 or any value within the above range.

[0069] In this embodiment, the surface of the silicon substrate close to the passivation and antireflection layer has a low impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0070] In some embodiments, the concentration N of impurities on the surface of the silicon substrate 1 close to the passivation and antireflection layer 6 101 is the same as the concentration N of impurities in the corresponding isolation region of the silicon substrate. 130 In this way, the surface of the silicon substrate close to the passivation and antireflection layer has a low impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0071] In some embodiments, the concentration N of impurities on the surface of the silicon substrate 1 close to the passivation and antireflection layer 6 101 is close to the concentration N of impurities in the corresponding isolation region of the silicon substrate. 130 In some embodiments, along the thickness direction of the silicon substrate 1, in the direction from the central position of the silicon substrate 1 to the first surface or the second surface, the concentration of impurities in the silicon substrate 1 gradually increases. In this way, the central position of the silicon substrate 1 has a low impurity concentration, which is beneficial to improving the efficiency of the back-contact solar cell.

[0072] In some embodiments, the first doping element includes element B, and the second doping element includes element P. Elements B and P are beneficial to absorbing impurities in the silicon substrate 1, which is beneficial to reducing the concentration of impurities in the silicon substrate 1, so that the back-contact solar cell has a high efficiency.

[0073] In some embodiments, there is a height difference between the first tunneling oxide layer 2 and the second tunneling oxide layer 4, and the value of the height difference is 0.05 μm to 3 μm. In this way, it is convenient for the preparation of the back-contact solar cell.

[0074] The value of the height difference between the first tunneling oxide layer 2 and the second tunneling oxide layer 4 can be 0.05 μm, 0.08 μm, 0.1 μm, 0.12 μm, 0.15 μm, 0.18 μm, 0.2 μm, 0.22 μm, 0.25 μm, 0.28 μm, 0.3 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm or any value within the above range.

[0075]

[0076] Figure 2 Figure 2 is a schematic diagram of a method for manufacturing a back-contact solar cell according to an embodiment of the present application. The present application provides a method for manufacturing a back-contact solar cell. For example, as Figure 2 shown, the method 200 for manufacturing a back-contact solar cell includes the following steps.

[0077] Step 210, preparing a first tunneling oxide layer 2 and a first polysilicon layer on the first surface of the silicon substrate 1.

[0078] As an example, before step 210, the silicon wafer is polished with an alkaline solution to remove the damaged layer and form a flat planar structure, so as to obtain the silicon substrate 1 and prepare the first tunneling oxide layer 2 and the first polysilicon layer on the first surface of the silicon substrate 1.

[0079] As an example, in step 210, the first tunneling oxide layer 2 is first prepared on the first surface of the silicon substrate 1, and then the first polysilicon layer is prepared. Specifically, an LPCVD device is used to deposit the first tunneling oxide layer 2 and the first polysilicon layer on the first surface of the silicon substrate 1. Among them, the material of the first tunneling oxide layer 2 includes SiO2. The deposition temperature of the first tunneling oxide layer 2 can be 550°C to 650°C, the thickness of the first tunneling oxide layer 2 is 0.5 nm to 2.5 nm, the deposition temperature of the first polysilicon layer can be 550°C to 650°C, and the thickness of the first polysilicon layer is 100 nm to 400 nm.

[0080] In step 220, the first doping source is doped into the silicon substrate 1 provided with the first polysilicon layer by means of thermal diffusion to obtain the first doped polysilicon layer 3. The thermal diffusion temperature of the first doping source is 910°C to 1000°C, and the thermal diffusion time of the first doping source is 10 min to 60 min.

[0081] As an example, during the process of preparing the first doped polysilicon layer 3, the addition of the first doping source will form a B-containing thin film with a certain thickness (which can also be called BSG), and then the BSG can be removed by means of laser or etching slurry.

[0082] In step 230, the second region 120 of the silicon substrate 1 provided with the first doped polysilicon layer 3 and the first tunneling oxide layer 2 is etched to expose the second region 120 of the silicon substrate 1.

[0083] As an example, in step 230, in addition to exposing the second region 120 of the silicon substrate 1, the isolation region 130 can also be exposed.

[0084] As an example, at least part of the BSG is removed according to a specific pattern to expose the first doped polysilicon layer 3 corresponding to the second region 120.

[0085] In step 240, a second tunneling oxide layer 4 and a second polysilicon layer are prepared on the first surface of the second region 120 of the silicon substrate 1.

[0086] As an example, when removing the first doped polysilicon layer in the exposed second region 120 by using an alkali solution plus an additive to form a polished topography, a height difference is formed between the part where the BSG region is not removed and the part where the BSG region is removed. The range of the height difference can be 0.05 μm to 0.3 μm, and the thickness of the part where the BSG region is not removed is about 10 nm to 30 nm.

[0087] As an example, after forming the height difference, a second tunneling oxide layer 4 and a second polysilicon layer are deposited by using an LPCVD device. Among them, the material of the second tunneling oxide layer 4 includes SiO2. The deposition temperature of the second tunneling oxide layer 4 can be 550 °C to 650 °C, the thickness of the second tunneling oxide layer 4 is 0.5 nm to 2.5 nm, the deposition temperature of the second polysilicon layer can be 550 °C to 650 °C, and the thickness of the second polysilicon layer is 100 nm to 300 nm.

[0088] Step 250: Dope the second doping source into the silicon substrate 1 provided with the second polysilicon layer by using thermal diffusion to obtain a second doped polysilicon layer 5. The thermal diffusion temperature of the second doping source is 850 °C to 920 °C, and the thermal diffusion time of the second doping source is 3 min to 60 min.

[0089] During the preparation of the second doped polysilicon layer 5, a film including P (which can also be called PSG) is formed. The thickness of the PSG region is 40 nm to 60 nm. Then, the PSG region (such as the PSG region corresponding to the first region and at least part of the PSG region corresponding to the second region) can be removed by using a laser. During the preparation of the second doped polysilicon layer 5, a second doped polysilicon layer is also correspondingly formed in the part of the silicon substrate corresponding to the first region. In order to facilitate obtaining the back-contact solar cell of the present application, the second doped polysilicon layer formed in the first region can be removed by using a laser or an etching method.

[0090] Step 260: Set an isolation region 130 between the first doped polysilicon layer 3 and the second doped polysilicon layer 5.

[0091] The isolation region 130 can be a groove extending along the thickness direction of the silicon substrate. The depth of the groove is 1 μm to 3 μm. Correspondingly, the plating around the second surface of the silicon substrate is removed by using a chain machine, and then it is placed in a trough texturing tank to complete texturing, so as to form a pyramid-shaped textured surface on the front surface to obtain a passivation and antireflection layer 6.

[0092] Step 270: Set a first passivation layer 71 and a second passivation layer 72 on the surfaces of the first doped polysilicon layer 3 and the second doped polysilicon layer 5 respectively.

[0093] The materials of the first passivation layer 71 and the second passivation layer 72 can include aluminum oxide (Al2O3), silicon nitride (SiN x), silicon oxynitride (SiON) or silicon dioxide (SiO x ), or two or more of them.

[0094] Step 280, prepare a first electrode 8 and a second electrode 9 on the surfaces of the first passivation layer 71 and the second passivation layer 72 respectively.

[0095] As an example, print silver paste on the surfaces of the first passivation layer 71 and the second passivation layer 72, and after sintering, obtain the first electrode 8 and the second electrode 9.

[0096] In the above embodiments, by controlling the thermal diffusion time and thermal diffusion temperature of the first doping source and the second doping source, it is beneficial for the doping elements to diffuse to the corresponding positions of the silicon substrate 1, so that the impurities in the silicon substrate 1 can be absorbed better, reducing the impurities in the silicon substrate 1 and being beneficial to improving the efficiency of the back-contact solar cell. In addition, this preparation method does not require additional steps to process the back-contact solar cell (such as pre-removing impurities from the silicon substrate before preparing the first tunneling oxide layer), which is beneficial to simplifying the preparation process of the back-contact solar cell.

[0097] In some embodiments, the thermal diffusion temperature of the first doping source is 960 °C to 980 °C, and the thermal diffusion time of the first doping source is 20 min to 40 min; the thermal diffusion temperature of the second doping source is 890 °C to 910 °C, and the thermal diffusion time of the second doping source is 5 min to 30 min. In this way, it is beneficial to further reduce the concentration of impurities in the silicon substrate 1, and at the same time avoid or reduce the damage to the first tunneling oxide layer 2 and the second tunneling oxide layer 4, so that the back-contact solar cell has a higher efficiency.

[0098] In some embodiments, the first doping source includes BCl3, and the second doping source includes POCl3. Elements B and P are beneficial to absorbing impurities in the silicon substrate 1, which is beneficial to reducing the concentration of impurities in the silicon substrate 1, so that the back-contact solar cell has a higher efficiency.

[0099] This application provides a photovoltaic module, including the back-contact solar cell in any embodiment.

[0100] Hereinafter, the embodiments of this application will be described. The embodiments described below are exemplary and are only used to explain this application and should not be construed as a limitation to this application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. For reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0101] In Embodiment 1, the preparation method of the back-contact battery is as follows.

[0102] (1)Polishing: The silicon wafer is polished with an alkaline solution to remove the damaged layer and form a flat planar structure to obtain a silicon substrate. (2)Deposition: A first tunneling oxide layer (SiO2) and a first polysilicon layer are deposited on the first surface of the silicon substrate using an LPCVD device. The thickness of the first tunneling oxide layer is 1.5 nm, the deposition temperature is 615 °C, the thickness of the first polysilicon layer is 300 nm, and the deposition temperature is 570 °C. (3)Boron diffusion: The silicon substrate with the first polysilicon layer deposited is doped by thermal diffusion to form a P-type doped region with a certain boron silicate glass film (also known as BSG). The diffusion source is BCl3, the diffusion temperature is 970 °C, and the diffusion time is 25 min. (4)Patterning 1: The BSG formed in step 3 is removed according to a specific pattern using a laser or etching paste to expose the P-type doped region (the first doped polysilicon layer). (5)Alkaline polishing: The exposed P-type doped region in step 4 is removed to form a polished morphology, while the region where the BSG is not removed is retained, thereby forming a height difference (GAP). The GAP ranges from 1 μm, and the remaining thickness of the BSG in the non-removed region is 25 nm. (6)Deposition: A second tunneling layer (SiO2) and a second polysilicon layer are deposited on the silicon substrate after step 5 using an LPCVD device. The thickness of the second tunneling oxide layer is 1.5 nm, the deposition temperature is 600 °C, the thickness of the second polysilicon layer is 200 nm, and the deposition temperature is 605 °C. (7)Phosphorus diffusion: The silicon substrate in step 6 is placed in a diffusion furnace. The diffusion source is POCl3, and after diffusion, an N-type doped region (the second doped polysilicon layer) with a certain thickness of phosphorus silicate glass film (also known as PSG) is formed. The diffusion temperature is 900 °C, and the diffusion time is 10 min. (8)Patterning 2: The PSG on the P-type doped region and part of the N-type doped region is removed using a laser. (9)Chain stripping and post-texturing: The silicon substrate is stripped of the overplating on the second surface using a chain machine and then placed in a trough-type texturing tank to complete texturing, forming a pyramid-shaped textured surface on the front. In addition, the N-type doped layer on the P-type doped region on the second surface of the silicon substrate is also removed synchronously, and grooves (isolation regions) are formed between the P-type doped region and the N-type doped region. (10)Passivation: A passivation film is deposited on the second surface to prepare a surface passivation layer. The material of the surface passivation layer is a stacked passivation film of alumina and silicon nitride. (11)Electrode preparation: Electrode paste is printed on the surface of the surface passivation layer at the positions corresponding to the P-type doped region and the N-type doped region, and after sintering, the first electrode and the second electrode are obtained. The electrode paste includes silver.

[0103] Example 2-3 is different from Example 1 in that the diffusion temperatures and times of boron diffusion and phosphorus diffusion are different.

[0104] In Example 2, the diffusion temperature of boron diffusion is 960 °C and the diffusion time is 30 min; the diffusion temperature of phosphorus diffusion is 890 °C and the diffusion time is 10 min.

[0105] In Example 3, the diffusion temperature of boron diffusion is 980 °C and the diffusion time is 20 min; the diffusion temperature of phosphorus diffusion is 910 °C and the diffusion time is 10 min.

[0106] Example 4-5 is different from Example 1 in that the diffusion temperatures and times of boron diffusion and phosphorus diffusion are different, and the diffusion depths of the first doping source and the second doping source are different.

[0107] In Example 4, the diffusion temperature of boron diffusion is 900 °C and the diffusion time is 30 min; the diffusion temperature of phosphorus diffusion is 840 °C and the diffusion time is 20 min.

[0108] In Example 5, the diffusion temperature of boron diffusion is 1020 °C and the diffusion time is 20 min; the diffusion temperature of phosphorus diffusion is 930 °C and the diffusion time is 10 min.

[0109] Performance tests were carried out on the back-contact solar cell, and the test conditions and results are as follows.

[0110] Specifically, under the irradiation of standard simulated sunlight (AM1.5G, 1000 W / m 2 ), performance tests were carried out on the back-contact solar cell to obtain the I-V curve. According to the I-V curve and the data fed back by the test equipment, the short-circuit current Jsc, open-circuit voltage Voc, maximum light output voltage Vmpp, and maximum power point current Impp can be obtained. The fill factor FF of the back-contact solar cell is calculated by the formula FF = (Jmpp × Vmpp) / (Jsc × Voc). The conversion efficiency Eff of the back-contact solar cell is calculated by the formula Eff = Jsc × Voc × FF / Pin, where Pin is the input power.

[0111] In Table 1, D1 is the diffusion depth of the first doping element B element in the silicon substrate, D2 is the diffusion depth of the second doping element P element in the silicon substrate, N 110 is the concentration of impurities in the silicon substrate in the first region, N 120 is the concentration of impurities in the silicon substrate in the second region, N 130 is the concentration of impurities in the silicon substrate in the isolation region, and E is the efficiency of the back-contact solar cell.

[0112] Table 1 Test results of examples

[0113] As shown in Examples 1-5, set N 130 ≤ N 120 < N 110 , the back-contact solar cell has a high efficiency.

[0114] As shown in Examples 1-3 and Example 4, by setting the diffusion depth of the first doping element in the silicon substrate to be greater than or equal to 0.05 μm, the diffusion depth of the second doping element in the silicon substrate to be greater than or equal to 0.03 μm and the diffusion depth of the first doping element in the silicon substrate to be greater than the diffusion depth of the second doping element in the silicon substrate, it is beneficial to reduce the impurity concentration in the silicon substrate and improve the efficiency of the back-contact solar cell; as shown in Examples 1-3 and Example 5, by setting the diffusion depth of the first doping element in the silicon substrate to be less than or equal to 0.6 μm, the diffusion depth of the second doping element in the silicon substrate to be less than or equal to 0.3 μm and the diffusion depth of the first doping element in the silicon substrate to be greater than the diffusion depth of the second doping element in the silicon substrate, it is beneficial to reduce the damage to the first tunneling oxide layer and the second tunneling oxide layer while reducing the impurities in the silicon substrate, thereby being beneficial to improving the efficiency of the back-contact solar cell.

[0115] (1) Test method for diffusion depth The electrochemical capacitance-voltage (ECV) method is used to test the diffusion depths of the first doping element and the second doping element. As an example, the back-contact solar cell is tested, the position where the characteristic element (such as B) in the first doping element cannot be detected in the first region is recorded, and the distance between this position and the first tunneling oxide layer is recorded, which is used as the diffusion depth of the first doping element; the position where the characteristic element (such as P) in the second doping element cannot be detected in the second region is recorded, and the distance between this position and the second tunneling oxide layer is recorded, which is used as the diffusion depth of the second doping element.

[0116] (2) Test method for impurity concentration The inductively coupled plasma mass spectrometry (ICP-MS) is used to test the impurity concentrations at different positions of the silicon substrate.

[0117] It should be noted that this application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments with the same structure in essence as the technical idea and achieving the same effect within the scope of the technical solution of this application are all included in the technical scope of this application. In addition, within the scope of not departing from the gist of this application, various modifications that can be conceived by those skilled in the art to the embodiments, as well as other ways constructed by combining some constituent elements in the embodiments, are also included in the scope of this application.

Claims

1. A back-contact solar cell, characterized in that, Comprising: A silicon substrate (1), the silicon substrate (1) having opposite first and second surfaces, the first surface being provided with a first region (110), a second region (120), and an isolation region (130) located between the first region (110) and the second region (120); The first region (110) includes a first tunneling oxide layer (2), a first doped polysilicon layer (3), a first passivation layer (71), and a first electrode (8) sequentially arranged along the thickness direction of the silicon substrate (1); The second region (120) includes a second tunneling oxide layer (4), a second doped polysilicon layer (5), a second passivation layer (72), and a second electrode (9) sequentially arranged along the thickness direction of the silicon substrate (1); The second surface is provided with a passivation and antireflection layer (6); The first doped polysilicon layer (3) includes a first doping element, the second doped polysilicon layer (5) includes a second doping element, the first doped polysilicon layer (3) is a P-type doped polysilicon layer, and the second doped polysilicon layer (5) is an N-type doped polysilicon layer; Wherein, a surface of the isolation region (130) close to the second region (120) includes the second doping element, and the sum of the concentrations of the first doping element and the second doping element on a surface of the silicon substrate close to the passivation antireflection layer (6) is less than 1×10 16 atom / cm 3 ; The silicon substrate (1) includes impurities, and the impurities include at least one of iron, nickel, and chromium. The concentration N of the impurities in the silicon substrate (1) corresponding to the first region (110) 110 , the concentration N of the impurities in the silicon substrate (1) corresponding to the isolation region (130) 130 , the concentration N of the impurities in the silicon substrate (1) corresponding to the second region (120) 120 satisfies: N 130 ≤N 120 <N 110 .

2. The back-contact solar cell according to claim 1, characterized in that, The diffusion depth of the second doping element in the silicon substrate (1) is less than the diffusion depth of the first doping element in the silicon substrate (1), the diffusion depth of the first doping element in the silicon substrate (1) is 0.05 μm to 0.6 μm, and the diffusion depth of the second doping element in the silicon substrate (1) is 0.03 μm to 0.3 μm.

3. The back contact solar cell according to claim 2, wherein, The diffusion depth of the first doping element in the silicon substrate (1) is 0.1 μm to 0.2 μm, and the diffusion depth of the second doping element in the silicon substrate (1) is 0.03 μm to 0.08 μm.

4. The back-contact solar cell according to claim 3, characterized in that, The diffusion depth of the second doping element in the silicon substrate (1) is 0.03 μm to 0.05 μm.

5. The back contact solar cell according to claim 1, characterized in that, The concentration N of impurities in the silicon substrate (1) corresponding to the first region (110) 110 The concentration N of impurities in the silicon substrate (1) corresponding to the isolation region (130) 130 The concentration N of impurities in the silicon substrate (1) corresponding to the second region (120) 120 Satisfies at least one of the following conditions: 1×10 10 atoms / cm 3 ≤N 110 ≤1×10 16 atoms / cm 3 ; 1×10 8 atom / cm 3 ≤N 120 ≤1×10 16 atom / cm 3 ; 1×10 8 atom / cm 3 ≤N 130 ≤1×10 16 atom / cm 3 。 6. The back contact solar cell according to claim 5, wherein The concentration N of impurities on the surface of the silicon substrate close to the passivation antireflection layer (6) 101 satisfies: N 101 ≤N 120 <N 110 .

7. The back-contact solar cell according to claim 1, characterized in that, The concentration N of impurities on the surface of the silicon substrate close to the passivation antireflection layer (6) 101 satisfies 1×10 10 atom / cm 3 ≤N 101 ≤1×10 15 atom / cm 3 .

8. The back-contact solar cell according to claim 1, characterized in that, The concentration N of impurities on the surface of the silicon substrate close to the passivation and antireflection layer (6) 101 is the same as the concentration N of impurities in the silicon substrate (1) corresponding to the isolation region (130). 130 Same.

9. The back-contact solar cell according to claim 1, wherein, Along the thickness direction of the silicon substrate (1), in the direction from the central position of the silicon substrate (1) towards the first surface or the second surface, the concentration of impurities in the silicon substrate (1) gradually increases.

10. The back-contact solar cell according to claim 1, wherein The first doping element includes B element, and the second doping element includes P element.

11. A method for preparing a back-contact solar cell, characterized in that, Comprising: Preparing a first tunneling oxide layer (2) and a first polysilicon layer on the first surface of the silicon substrate (1); Doping the first doping source into the silicon substrate (1) provided with the first polysilicon layer by thermal diffusion to obtain a first doped polysilicon layer (3), the thermal diffusion temperature of the first doping source being 910 °C to 1000 °C, and the thermal diffusion time of the first doping source being 10 min to 60 min; Etching the second region (120) of the silicon substrate (1) provided with the first doped polysilicon layer (3) and the first tunneling oxide layer (2) to expose the second region (120) of the silicon substrate (1); Preparing a second tunneling oxide layer (4) and a second polysilicon layer on the first surface of the second region (120) of the silicon substrate (1); The second dopant source is doped into the silicon substrate (1) provided with the second polysilicon layer by means of thermal diffusion to obtain a second doped polysilicon layer (5). The thermal diffusion temperature of the second dopant source is 850 °C to 920 °C, and the thermal diffusion time of the second dopant source is 3 min to 60 min; An isolation region (130) is provided between the first doped polysilicon layer (3) and the second doped polysilicon layer (5); A first passivation layer (71) and a second passivation layer (72) are respectively provided on the surfaces of the first doped polysilicon layer (3) and the second doped polysilicon layer (5); A first electrode (8) and a second electrode (9) are respectively fabricated on the surfaces of the first passivation layer (71) and the second passivation layer (72).

12. The manufacturing method of the back-contact solar cell according to claim 11, characterized in that, The thermal diffusion temperature of the first dopant source is 960 °C to 980 °C, and the thermal diffusion time of the first dopant source is 20 min to 40 min; The thermal diffusion temperature of the second dopant source is 890 °C to 910 °C, and the thermal diffusion time of the second dopant source is 5 min to 30 min.

13. The manufacturing method of the back-contact solar cell according to claim 11, characterized in that, The first dopant source includes BCl3, and the second dopant source includes POCl3.

14. A photovoltaic module, characterized in that, Comprising a back-contact solar cell according to any one of claims 1-10.

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