Solar cell, preparation method thereof and photovoltaic module

Abstract

The embodiment of the invention relates to a solar cell, a preparation method thereof and a photovoltaic module. The solar cell comprises a substrate comprising a metal contact region and a non-metal contact region which are adjacent to each other; the first doping layer is located on the substrate and covers the metal contact region and the non-metal contact region; the second doping layer is located on the surface, away from the substrate, of the first doping layer, covers the metal contact region and the non-metal contact region, and comprises carbon elements; the third doping layer is located on the surface, away from the substrate, of the second doping layer in the metal contact region; wherein the doping concentration of the doping element of the first conduction type in the third doping layer is greater than the doping concentration of the doping element of the first conduction type in the second doping layer, and the doping concentration of the doping element of the first conduction type in the second doping layer is greater than the doping concentration of the doping element of the first conduction type in the first doping layer. Under the condition that contact is not changed, parasitic absorption is reduced, and the performance of the solar cell is improved.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of solar cells, and in particular to a solar cell and a preparation method thereof, and a photovoltaic module. Background Art

[0002] The tunneling layer in the Tunnel Oxide Passivated Contact (TOPCON) cell can significantly reduce the recombination of electrons and holes, and increase the cell's opening voltage and current density. A typical TOPCON cell has a double-sided polysilicon doping layer to increase the cell's conversion efficiency. The parasitic absorption of light by the TOPCON cell increases with the increase in the doping concentration and thickness of the polysilicon doping layer. The polysilicon doping layer with a high doping concentration is the basis for the contact between the polysilicon doping layer and the metal electrode. Summary of the invention

[0003] The embodiments of the present disclosure provide a solar cell and a preparation method thereof, and a photovoltaic module, which can optimize the parasitic absorption of the solar cell and improve the conversion efficiency of the solar cell.

[0004] In a first aspect, a solar cell is provided, comprising:

[0005] A substrate, including adjacent metallic contact areas and non-metallic contact areas;

[0006] A first doping layer, located on the substrate and covering the metal contact area and the non-metal contact area;

[0007] A second doping layer, located on a surface of the first doping layer away from the substrate, covering the metal contact area and the non-metal contact area, wherein the second doping layer contains carbon;

[0008] a third doped layer, located in the metal contact region, the second doped layer being away from the surface of the substrate;

[0009] Among them, the doping concentration of the doping element of the first conductivity type in the third doping layer is greater than the doping concentration of the doping element of the first conductivity type in the second doping layer, and the doping concentration of the doping element of the first conductivity type in the second doping layer is greater than the doping concentration of the doping element of the first conductivity type in the first doping layer.

[0010] In one embodiment, the doping concentration of the carbon element in the second doping layer is greater than the doping concentration of the doping element of the first conductivity type.

[0011] In one embodiment, the solar cell further comprises:

[0012] A transparent conductive layer, wherein the transparent conductive layer is located on a surface of the first doped layer in the metal contact region away from the substrate; or the transparent conductive layer is located on a surface of the first doped layer in the metal contact region and the non-metal contact region away from the substrate;

[0013] Wherein, a surface of the transparent conductive layer away from the substrate is adjacent to the second doping layer.

[0014] In one embodiment, the solar cell further comprises:

[0015] a barrier layer, located on a surface of the first doped layer away from the substrate and covering the metal contact area and the non-metal contact area;

[0016] Wherein, a surface of the barrier layer away from the substrate is adjacent to the second doping layer.

[0017] In a second aspect, a method for preparing a solar cell is provided, comprising:

[0018] providing a substrate comprising a contiguous metallic contact region and a non-metallic contact region;

[0019] forming a first doping layer on the substrate, wherein the first doping layer covers the metal contact area and the non-metal contact area;

[0020] forming a second doping layer containing carbon elements on a surface of the first doping layer away from the substrate, wherein the second doping layer covers the metal contact area and the non-metal contact area;

[0021] Forming a third doping layer on a surface of the second doping layer in the metal contact region away from the substrate;

[0022] Among them, the doping concentration of the doping element of the first conductivity type in the third doping layer is greater than the doping concentration of the doping element of the first conductivity type in the second doping layer, and the doping concentration of the doping element of the first conductivity type in the second doping layer is greater than the doping concentration of the doping element of the first conductivity type in the first doping layer.

[0023] In one embodiment, before forming a second doping layer containing carbon elements on a surface of the first doping layer away from the substrate, the method further includes:

[0024] Forming a transparent conductive layer on the surface of the first doped layer in the metal contact area away from the substrate; or forming a transparent conductive layer on the surface of the first doped layer in the metal contact area and the non-metal contact area away from the substrate;

[0025] Wherein, a surface of the transparent conductive layer away from the substrate is adjacent to the second doping layer.

[0026] In one embodiment, the method for preparing a solar cell further includes:

[0027] Processing the surface of the substrate to obtain an arc-shaped surface;

[0028] The arc-shaped surface is close to the first doping layer and / or far away from the first doping layer.

[0029] In one embodiment, before forming the first doping layer on the substrate, the method further includes:

[0030] forming a tunneling layer on the surface of the substrate, wherein the tunneling layer covers the metal contact area and the non-metal contact area;

[0031] Wherein, a surface of the tunneling layer away from the substrate is adjacent to the first doping layer.

[0032] In one embodiment, the step of forming a tunneling layer on the surface of the substrate includes:

[0033] Using a low pressure chemical vapor deposition process, a first tunneling sublayer is formed on the surface of the substrate;

[0034] Using a plasma enhanced chemical vapor deposition process, forming a second tunneling sublayer on a surface of the first tunneling sublayer away from the substrate;

[0035] The process gas of the plasma enhanced chemical vapor deposition process includes nitrous oxide, and the tunneling layer includes the first tunneling sublayer and the second tunneling sublayer.

[0036] In one embodiment, before forming a second doping layer containing carbon elements on a surface of the first doping layer away from the substrate, the method further includes:

[0037] forming a barrier layer on a surface of the first doped layer away from the substrate, wherein the barrier layer covers the metal contact area and the non-metal contact area;

[0038] Wherein, a surface of the barrier layer away from the substrate is adjacent to the second doping layer.

[0039] A photovoltaic assembly comprises a plurality of solar cells as described above, and / or a plurality of solar cells manufactured by the method for manufacturing a solar cell as described above.

[0040] In the above solar cell, the second doping layer containing carbon elements reduces the extinction coefficient, reduces parasitic absorption, increases the fill factor, improves the optical performance of the solar cell, increases the conversion efficiency of the solar cell, and improves the performance of the solar cell. At the same time, the doping concentration of the doping element in the first doping layer and the doping concentration of the doping element in the second doping layer are both less than the doping concentration of the doping element in the third doping layer, and the third doping layer covers the metal contact area, which reduces the parasitic absorption and improves the performance of the solar cell when the contact remains unchanged.

[0041] In the above-mentioned method for preparing a solar cell, the second doping layer containing carbon elements formed on the first doping layer reduces the extinction coefficient, reduces parasitic absorption, increases the fill factor, improves the optical performance of the solar cell, increases the conversion efficiency of the solar cell, and improves the performance of the solar cell. At the same time, the doping concentration of the doping element in the first doping layer and the doping concentration of the doping element in the second doping layer are both less than the doping concentration of the doping element in the third doping layer, and the third doping layer covers the metal contact area, which reduces parasitic absorption and improves the performance of the solar cell when the contact remains unchanged. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or related technologies, the drawings required for use in the embodiments or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] FIG1 is a schematic diagram of a process for preparing a solar cell in some embodiments;

[0044] FIG2 is a cross-sectional schematic diagram of a solar cell in some embodiments;

[0045] Figure 3 are cross-sectional schematic diagrams of solar cells in other embodiments;

[0046] Figure 4 Schematic cross-sectional view of a solar cell in some embodiments.

[0047] Description of reference numerals:

[0048] Substrate 102 , first doping layer 104 , second doping layer 106 , third doping layer 108 , first gate 110 , tunneling layer 112 , barrier layer 202 , transparent conductive layer 302 , tunneling layer 404 , fourth doping layer 406 , fifth doping layer 408 , anti-reflection layer 410 , second gate 412 . DETAILED DESCRIPTION

[0049] In order to facilitate understanding of the embodiments of the present disclosure, the embodiments of the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the embodiments of the present disclosure are shown in the drawings. However, the embodiments of the present disclosure can be implemented in many different forms and are not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the embodiments of the present disclosure more thorough and comprehensive.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the disclosed embodiments belong. The terms used herein in the specification of the disclosed embodiments are only for the purpose of describing specific embodiments and are not intended to limit the disclosed embodiments. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0051] In the description of the embodiments of the present disclosure, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "inside", "outside", etc. indicating orientations or positional relationships are based on the methods or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present disclosure.

[0052] It is understood that the terms "first", "second", etc. used in the present disclosure may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of the present disclosure, a first doped layer may be referred to as a second doped layer, and similarly, a second doped layer may be referred to as a first doped layer. Both the first doped layer and the second doped layer are doped layers, but they are not the same doped layer.

[0053] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present disclosure, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0054] FIG. 1 is a schematic flow chart of a method for preparing a solar cell in some embodiments, and FIG. 2 is a schematic cross-sectional view of a solar cell in some embodiments. As shown in FIG. 1 and FIG. 2, in this embodiment, a method for preparing a solar cell is provided, comprising:

[0055] S102, providing a substrate, wherein the substrate includes adjacent metal contact areas and non-metal contact areas.

[0056] A substrate 102 is provided, the substrate 102 includes adjacent metal contact areas 1 and non-metal contact areas 2, the metal contact area 1 is an area on the substrate 102 where electrodes are formed, the non-metal contact area 2 is an area on the substrate 102 other than the metal contact area 1, adjacent means adjacent and in contact, the substrate 102 has a light-receiving surface and a light-receiving surface that are arranged oppositely, the light-receiving surface is a surface of the solar cell facing the sunlight (light-facing surface), the light-receiving surface is a surface on the substrate that is arranged opposite to the light-receiving surface, the substrate 102 includes a semiconductor doped substrate made of silicon or germanium, etc., a doped compound semiconductor substrate of silicon carbide, silicon germanium, gallium arsenide, indium phosphide, zinc oxide or gallium oxide, etc. As an example, in this embodiment, the constituent material of the substrate is doped single crystal silicon.

[0057] S104, forming a first doping layer on the substrate.

[0058] A first doping layer 104 having a doping element of a first conductivity type is formed on the substrate 102, the first doping layer 104 covers the metal contact area 1 and the non-metal contact area 2, and the first doping layer 104 is in contact with the surface of the substrate 102; or other device layers, such as a tunneling layer, a passivation layer, etc., are arranged between the first doping layer 104 and the surface of the substrate 102. It can be understood that the first conductivity type is N-type or P-type, wherein the N-type doping element includes one or more of phosphorus, arsenic and antimony, and the P-type doping element includes one or more of boron, aluminum, gallium and indium.

[0059] S106, forming a second doping layer containing carbon elements on a surface of the first doping layer away from the substrate.

[0060] A second doping layer 106 having a doping element of the first conductivity type is formed on a surface of the first doping layer 104 away from the substrate 102, a surface of the second doping layer 106 close to the substrate 102 is in contact with a surface of the first doping layer 104 away from the substrate 102, or other device layers are arranged between a surface of the second doping layer 106 close to the substrate 102 and a surface of the first doping layer 104 away from the substrate 102, the second doping layer 106 contains carbon elements, and the second doping layer 106 covers the metal contact area 1 and the non-metal contact area 2, wherein the doping concentration of the doping element of the first conductivity type in the second doping layer 106 is greater than the doping concentration of the doping element of the first conductivity type in the first doping layer 104, and the doping element of the first conductivity type in the second doping layer 106 and the doping element of the first conductivity type in the first doping layer 104 can be the same or different.

[0061] S108, forming a third doping layer on a surface of the second doping layer in the metal contact region away from the substrate.

[0062] A third doping layer 108 having a doping element of the first conductivity type is formed on the surface of the second doping layer 106 away from the substrate 102, and the surface of the third doping layer 108 close to the substrate 102 contacts the surface of the second doping layer 106 away from the substrate 102, and the third doping layer 108 covers the metal contact area 1, wherein the doping concentration of the doping element of the first conductivity type in the third doping layer 108 is greater than the doping concentration of the doping element of the first conductivity type in the second doping layer 106, and the doping element of the first conductivity type in the third doping layer 108 and the doping element of the first conductivity type in the second doping layer 106 can be the same or different. The third doping layer 108 with a high doping concentration is located in the metal contact area 1, and the first gate 110 formed subsequently contacts the third doping layer 108, and the contact between the first gate 110 and the doping layer is not changed. The non-metal contact area 2 is provided with the second doping layer 106 with a low doping concentration and the first doping layer 104 without the third doping layer 108, and the second doping layer 106 contains carbon elements, which increases the filling factor of the solar cell, further reduces parasitic absorption, and improves the optical performance of the solar cell. The first doping layer 104 is disposed between the second doping layer 106 containing carbon elements and the substrate 102 to prevent carbon elements from diffusing between the substrate 102 and the first doping layer 104 and affecting the passivation of the solar cell. Meanwhile, the first doping layer 104 has a passivation effect.

[0063] As an example, in the present embodiment, the doping element of the first conductivity type in the third doping layer 108, the doping element of the first conductivity type in the second doping layer 106 and the doping element of the first conductivity type in the first doping layer 104 are the same; when the first conductivity type is P type, the doping element of the first conductivity type is boron, and when the first conductivity type is N type, the doping element of the first conductivity type is phosphorus.

[0064] In the above-mentioned method for preparing a solar cell, the second doping layer 106 containing carbon elements formed on the first doping layer 104 reduces the extinction coefficient, reduces parasitic absorption, increases the fill factor, improves the optical performance of the solar cell, increases the conversion efficiency of the solar cell, and improves the performance of the solar cell. At the same time, the doping concentration of the doping element in the first doping layer 104 and the doping concentration of the doping element in the second doping layer 106 are both less than the doping concentration of the doping element in the third doping layer 108, and the third doping layer 108 covers the metal contact area 1, and under the condition of unchanged contact, the parasitic absorption is reduced, and the performance of the solar cell is improved.

[0065] As shown in FIG2 , in one embodiment, before forming the first doping layer 104 on the substrate 102, it also includes: forming a tunneling layer 112 on the surface of the substrate 102, the tunneling layer 112 covers the metal contact area 1 and the non-metal contact area 2; wherein the tunneling layer 112 is away from the surface of the substrate 102 and is adjacent to the first doping layer 104. By forming the tunneling layer 112 between the substrate 102 and the first doping layer 104, the surface of the substrate 102 can be passivated, the recombination rate of carriers can be reduced, the collection and transmission efficiency of carriers can be improved, and the photoelectric conversion efficiency and stability of the solar cell can be improved. Exemplarily, the material of the tunneling layer 112 includes silicon dioxide.

[0066] Exemplarily, the tunneling layer 112 is formed on the surface of the substrate 102 by using a chemical vapor deposition process.

[0067] In one embodiment, the step of forming the tunneling layer 112 on the surface of the substrate 102 includes: S202 - S204 .

[0068] S202, forming a first tunneling sublayer on the surface of the substrate by using a low pressure chemical vapor deposition process.

[0069] S204 , forming a second tunneling sublayer on a surface of the first tunneling sublayer away from the substrate by using a plasma enhanced chemical vapor deposition process.

[0070] Specifically, steps S202-S204 are as follows: first, after the surface of the substrate 102 is textured and RCA cleaned, a low-pressure chemical vapor deposition process (LPCVD) is used to thermally oxidize the surface of the substrate 102 to form a first tunneling sublayer; secondly, a plasma-enhanced chemical vapor deposition process is used to form a second tunneling sublayer on the surface of the first tunneling sublayer away from the substrate 102; wherein the tunneling layer 112 includes the first tunneling sublayer and the second tunneling sublayer, and the process gas of the plasma-enhanced chemical vapor deposition process includes nitrous oxide. Furthermore, the process gas of the plasma-enhanced chemical vapor deposition process also includes silane and hydrogen. The first tunneling sublayer has good density, which improves the passivation performance of the tunneling layer 112 and improves the performance of the solar cell.

[0071] Exemplarily, when the material of the first doping layer 104 is phosphorus-doped polysilicon, the first doping layer 104 is formed by a plasma enhanced chemical vapor deposition process in which the process gas includes silane and phosphine, the flow rate of phosphine: the flow rate of silane is equal to 0.04:1-0.1:1, and the thickness of the first doping layer 104 in the direction perpendicular to the substrate 102 is 5nm-15nm. Further, the material of the substrate 102 is N-type single crystal silicon, and the first doping layer 104 and the substrate 102 both have the first conductivity type.

[0072] Figure 3 Schematic cross-sectional views of solar cells in other embodiments, such as Figure 3 As shown, in one embodiment, before forming the second doping layer 106 containing carbon elements on the surface of the first doping layer 104 away from the substrate 102, it also includes: forming a barrier layer 202 on the surface of the first doping layer 104 away from the substrate 102, the barrier layer 202 covers the metal contact area 1 and the non-metal contact area 2; wherein the surface of the barrier layer 202 away from the substrate is adjacent to the second doping layer. Exemplarily, the material of the barrier layer 202 includes silicon dioxide. The barrier layer 202 can prevent the carbon element in the second doping layer 106 from diffusing to the side of the first doping layer 104, thereby reducing the probability that the carbon element affects the passivation effect of the solar cell.

[0073] It is understandable that, when a tunneling layer 112 is formed between the first doping layer 104 and the substrate 102 , the barrier layer 202 can prevent the carbon element in the second doping layer 106 from damaging the tunneling layer 112 and thus affecting the passivation effect.

[0074] Figure 4 is a schematic cross-sectional view of a solar cell in some embodiments, such as Figure 4 As shown, in some embodiments, the method for preparing a solar cell includes: forming a transparent conductive layer 302 on the surface of the first doping layer 104 of the metal contact area 1 away from the substrate 102. The transparent conductive layer 302 is used to adjust the contact between the first doping layer 104 and the second doping layer 106 of the metal contact area 1, improve the passivation of the first doping layer 104 of the metal contact area 1, reduce the probability that the carbon element in the metal contact area 1 affects the passivation effect of the solar cell, and improve the performance of the solar cell. The transparent conductive layer 302 can also block the carbon element in the second doping layer 106 from diffusing to the side of the first doping layer 104, and reduce the probability that the carbon element affects the passivation effect of the solar cell. The doping concentration of the third doping layer 108 of the metal contact area 1 is greater than the doping concentration of the first doping layer 104 and the doping concentration of the second doping layer 106, respectively, which can reduce or offset the influence of the transparent conductive layer 302 on the series resistance of the solar cell, and reduce or do not affect the fill factor of the solar cell while improving the passivation effect of the first doping layer 104. Meanwhile, when the first doping layer 104 is located on the light-facing side of the substrate 102 , the addition of the transparent conductive layer 302 does not affect the light entering the cell.

[0075] like Figure 4As shown, in some embodiments, forming a transparent conductive layer 302 at least on the surface of the first doped layer 104 of the metal contact area 1 away from the substrate 102 includes: forming a transparent conductive layer 302 on the surface of the first doped layer 104 of the metal contact area 1 and the non-metal contact area 2 away from the substrate 102. The transparent conductive layer 302 is used to adjust the contact between the first doped layer 104 and the second doped layer 106 of the metal contact area 1 and the non-metal contact area 2, improve the passivation of the first doped layer 104 of the metal contact area 1 and the non-metal contact area 2, and reduce the probability that the carbon element in the metal contact area 1 and the non-metal contact area 2 affects the passivation effect of the solar cell, so as to further improve the passivation of the first doped layer 104 and further reduce the probability that the carbon element affects the passivation effect of the solar cell, and the transparent conductive layer 302 has a relatively small effect on the fill factor of the solar cell.

[0076] Exemplarily, the transparent conductive layer 302 is formed by a physical vapor deposition process or a plasma deposition process. Further, the thickness of the transparent conductive layer 302 is 10 nm-30 nm.

[0077] like Figure 3 , Figure 4 As shown, exemplarily, a plasma enhanced chemical vapor deposition process is used to sequentially form a second doping layer 106 and a third doping material layer on the surface of the barrier layer 202 or the transparent conductive layer 302 away from the substrate 102, and annealing is performed in a diffusion furnace, wherein the second doping layer 106 and the third doping material layer both cover the metal contact area 1 and the non-metal contact area 2, the third doping material layer is located on the surface of the second doping layer 106 away from the substrate 102, and the doping concentration of the first conductive type doping element in the third doping material layer is greater than the doping concentration of the first conductive type doping element in the second doping layer 106. Then, an etching process, such as a wet etching process, is used to remove the third doping material layer of the non-metal contact area 2, and a third doping layer 108 composed of the third doping material layer of the metal contact area 1 is formed. Exemplarily, in the process of removing the third doping material layer of the non-metal contact area 2, the third doping material layer of the metal contact area 1 is protected by a laser protection or mask protection method.

[0078] Exemplarily, the process temperature of the annealing treatment includes 800° C.-900° C., such as 800° C., 820° C., 850° C., 860° C. and 900° C.; the process time of the annealing treatment includes 10 min-30 min.

[0079] Exemplarily, the material of the second doping layer 106 includes doped polysilicon containing carbon, and the material of the third doping layer 108 includes doped polysilicon. In the case where the material of the second doping layer 106 includes phosphorus-doped polysilicon containing carbon, the second doping layer 106 is formed by a plasma enhanced chemical vapor deposition process in which the process gas includes silane, phosphine and methane, and the flow rate of phosphine: the flow rate of silane: the flow rate of methane is equal to 0.1:1:0.3-0.2:1:1.5. The thickness of the second doping layer 106 in the direction perpendicular to the substrate 102 is 30nm-70nm.

[0080] It is understandable that when a tunneling layer 112 is formed between the first doping layer 104 and the substrate 102 , the transparent conductive layer 302 prevents the carbon element in the second doping layer 106 from damaging the tunneling layer 112 and thus affecting the passivation effect.

[0081] In one embodiment, the method for preparing a solar cell further includes: processing the surface of the substrate 102 to obtain an arc-shaped surface; wherein the arc-shaped surface is close to the first doping layer 104 and / or away from the first doping layer 104. The area of ​​the arc-shaped surface is larger than the area of ​​the pyramid-shaped surface, so that the subsequent tunneling layer 112 or tunneling layer 404 adjacent thereto is more uniform, has a better blocking effect on the doping elements, has a larger process window for preparation, and is easier to meet mass production requirements.

[0082] In one embodiment, the step of treating the surface of the substrate to obtain an arc-shaped surface includes: treating the surface of the substrate using a texturing process to obtain a pyramid-shaped surface; acid-polishing the pyramid-shaped surface to obtain an arc-shaped surface; wherein the acid-polishing reagent includes hydrofluoric acid, nitric acid and deionized water. Exemplarily, the volume ratio of hydrofluoric acid, nitric acid and deionized water is 2:7:13, and the acid-polishing time includes 600 seconds to 900 seconds.

[0083] Figure 4Taking the arc-shaped surface away from the first doping layer 104 as an example, the arc-shaped surface is formed as follows: first, a chain cleaning machine is used to remove the first conductive type of doped glass on the surface of the substrate 102 away from the first doping layer 104, for example, when the first doping layer 104, the second doping layer 106 and the third doping layer 108 are all phosphorus-doped polysilicon, the first conductive type of doped glass is phosphate glass; when the first doping layer 104, the second doping layer 106 and the third doping layer 108 are all boron-doped polysilicon, the first conductive type of doped glass is borate glass. Secondly, the surface of the substrate 102 away from the first doping layer 104 is subjected to secondary texturing to obtain a pyramid-shaped surface; thirdly, the pyramid-shaped surface is subjected to acid polishing for 600 seconds to 900 seconds to obtain an arc-shaped surface 402, and the acid polishing reagent is hydrofluoric acid, nitric acid and deionized water in a volume ratio of 2:7:13.

[0084] like Figure 4 As shown, in some embodiments, the surface of the substrate 102 away from the first doping layer 104 is an arc-shaped surface 402 , and the method for preparing a solar cell further includes: steps S302 - S310 .

[0085] S302 , forming a tunneling layer 404 on a surface of the substrate 102 away from the first doping layer 104 , wherein the tunneling layer 404 is adjacent to the arc-shaped surface 402 .

[0086] RC2 is used to clean the surface of the substrate 102 away from the first doping layer 104 (arc-shaped surface 402); secondly, a low-pressure chemical vapor deposition process is used to form a tunneling layer 404 on the arc-shaped surface 402, and the tunneling layer 404 covers the metal contact area 1 and the non-metal contact area 2. For example, the definition of the tunneling layer 112 can refer to the above definition of the tunneling layer 404.

[0087] S304 , forming a fourth doping layer 406 and a fifth doping layer 408 in the fourth doping layer 406 located in the metal contact region 1 on the surface of the tunneling layer 404 away from the substrate 102 , wherein the surface of the fifth doping layer 408 away from the substrate 102 is flush with the surface of the fourth doping layer 406 away from the substrate 102 .

[0088] Exemplarily, the fourth doped layer 406 includes doped polysilicon of the second conductivity type, and step S304 is specifically as follows: first, a low-pressure chemical vapor deposition process is used to form non-doped polysilicon on the surface of the tunneling layer 404 away from the substrate 102. Secondly, the substrate 102 is placed in a diffusion furnace to diffuse the second conductivity type doping element, so that the non-doped polysilicon becomes a doped polycrystalline material of the second conductivity type, and the second conductivity type doped polycrystalline material away from the surface of the substrate 102 is oxidized to form a doped glass of the second conductivity type, the second conductivity type is opposite to the first conductivity type, and the first conductivity type is N-type, the second conductivity type is P-type, and the second conductivity type doping element is boron element. The doped glass of the second conductivity type is borosilicate glass. Again, using laser doping equipment, a laser doping process is adopted to perform secondary doping on a portion of the doped polycrystalline material located in the metal contact area 1 and close to the doped glass, so that the doping elements in the second conductive type doped glass of the metal contact area 1 enter into the doped polycrystalline material adjacent to it in a direction perpendicular to the substrate 102, and form a fourth doping layer 406 and a fifth doping layer 408 composed of the remaining doped polycrystalline material, the fourth doping layer 406 covers the metal contact area 1 and the non-metallic contact area 2, the fifth doping layer 408 is located in the fourth doping layer 406 of the metal contact area 1, the surface of the fifth doping layer 408 away from the substrate 102 is flush with the surface of the fourth doping layer 406 away from the substrate 102, and the fourth doping layer 406 is spaced between the fifth doping layer 408 and the tunneling layer 404, the doping elements of the second conductive type in the fifth doping layer 408 and the fourth doping layer 406 are the same, and the doping concentration of the second conductive type in the fifth doping layer 408 is greater than the doping concentration of the second conductive type in the fourth doping layer 406. Next, the second conductive type doped glass is removed, for example, by using a chain cleaning machine to clean and remove the second conductive type doped glass, and then polishing is performed.

[0089] S306 , forming an anti-reflection layer 410 on a surface of the fifth doping layer 408 away from the substrate 102 and a surface of the third doping layer 108 away from the substrate 102 , respectively.

[0090] First, RCA is used to clean the surface of the fifth doping layer 408 away from the substrate 102 and the surface of the third doping layer 108 away from the substrate 102; thirdly, a plasma enhanced chemical vapor deposition process is used to form an anti-reflection layer 410 on the surface of the fifth doping layer 408 away from the substrate 102 and the surface of the third doping layer 108 away from the substrate 102, respectively, wherein the anti-reflection layer 410 on the surface of the fifth doping layer 408 extends to cover the surface of the fourth doping layer 406 away from the substrate 102, and the anti-reflection layer 410 on the surface of the third doping layer 108 extends to cover the surface of the second doping layer 106 away from the substrate 102. Exemplarily, the material of the anti-reflection layer 410 includes silicon nitride.

[0091] S308 , forming a first gate 110 on a surface of the anti-reflection layer 410 away from the third doping layer 108 .

[0092] A screen printing process is used to form a first gate 110 on the surface of the anti-reflection layer 410 away from the third doping layer 108. The first gate 110 is located in the metal contact area 1. The first gate 110 penetrates the anti-reflection layer 410 on the third doping layer 108 and contacts the third doping layer 108. Further, in a plane parallel to the substrate 102, the size of the first gate 110 is smaller than the size of the third doping layer 108, thereby avoiding the influence of process errors on the contact between the first gate 110 and the third doping layer 108. Exemplarily, the material of the screen printing process is silver paste. Further, before forming the first gate 110, a laser film opening process is used to form a filling groove on the surface of the anti-reflection layer 410 away from the third doping layer 108, and the third doping layer 108 is exposed at the bottom of the filling groove, thereby reducing the blocking effect of the anti-reflection layer 410 on the silver paste during the screen printing process.

[0093] S310 , forming a second gate 412 on a surface of the anti-reflection layer 410 away from the fifth doping layer 408 .

[0094] A second gate 412 is formed on the surface of the anti-reflection layer 410 away from the fifth doping layer 408 by using a screen printing process. The second gate 412 is located in the metal contact region 1. The second gate 412 penetrates the anti-reflection layer 410 on the fifth doping layer 408 and contacts the fifth doping layer 408. Further, in a plane parallel to the substrate 102, the size of the second gate 412 is smaller than the size of the fifth doping layer 408, so as to avoid the influence of process errors on the contact between the second gate 412 and the fifth doping layer 408. Exemplarily, the material of the screen printing process is silver paste.

[0095] It should be understood that, although the various steps in the flowchart of FIG. 1 are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in FIG. 1 may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps.

[0096] The present disclosure provides a solar cell, and the parts identical or corresponding to those in the embodiment of the preparation method of the solar cell will not be described in detail below.

[0097] As shown in FIG. 2 , in this embodiment, the solar cell includes: a substrate 102, a first doping layer 104, a second doping layer 106 and a third doping layer 108; the substrate 102 includes an adjacent metal contact area 1 and a non-metal contact area 2; the first doping layer 104 is located on the substrate 102 and covers the metal contact area 1 and the non-metal contact area 2; the second doping layer 106 is located on a surface of the first doping layer 104 away from the substrate 102, covers the metal contact area 1 and the non-metal contact area 2, and the second doping layer 106 contains carbon elements; the third doping layer 108 is located on a surface of the second doping layer 106 away from the substrate 102 in the metal contact area 1; wherein the doping concentration of the first conductive type doping element in the third doping layer 108 is greater than the doping concentration of the first conductive type doping element in the second doping layer 106, and the doping concentration of the first conductive type doping element in the second doping layer 106 is greater than the doping concentration of the first conductive type doping element in the first doping layer 104.

[0098] In the above solar cell, the second doping layer 106 containing carbon elements reduces the extinction coefficient, reduces parasitic absorption, increases the fill factor, improves the optical performance of the solar cell, increases the conversion efficiency of the solar cell, and improves the performance of the solar cell. At the same time, the doping concentration of the doping element in the first doping layer 104 and the doping concentration of the doping element in the second doping layer 106 are both less than the doping concentration of the doping element in the third doping layer 108, and the third doping layer 108 covers the metal contact area, and under the condition that the contact remains unchanged, the parasitic absorption is reduced and the performance of the solar cell is improved.

[0099] In one embodiment, the doping concentration of the carbon element in the second doping layer 106 is greater than the doping concentration of the doping element of the first conductivity type, thereby increasing the optimization of the optical performance of the second doping layer 106 .

[0100] like Figure 3 As shown, in one embodiment, the solar cell further includes: a barrier layer 202, the barrier layer 202 is located on the surface of the first doping layer 104 away from the substrate 102, and covers the metal contact area 1 and the non-metal contact area 2; wherein the surface of the barrier layer 202 away from the substrate 102 is adjacent to the second doping layer 106. The barrier layer 202 can prevent the carbon element in the second doping layer 106 from diffusing to the first doping layer 104 side, thereby reducing the probability that the carbon element affects the passivation effect of the solar cell.

[0101] like Figure 4As shown, in one embodiment, the solar cell further comprises: a transparent conductive layer 302, the transparent conductive layer 302 is at least located on the surface of the first doped layer 104 of the metal contact area 1 away from the substrate 102; wherein the surface of the transparent conductive layer 302 away from the substrate 102 is adjacent to the second doped layer 104. The transparent conductive layer 302 can adjust the contact between the first doped layer 104 and the second doped layer 106 on opposite sides of the transparent conductive layer 302, improve the passivation of the first doped layer 104 adjacent to the transparent conductive layer 302, and improve the performance of the solar cell. The transparent conductive layer 302 can also block the carbon element in the second doped layer 106 from diffusing to the first doped layer 104 side, reducing the probability of the carbon element affecting the passivation effect of the solar cell. In addition, the transparent conductive layer 302 has good conductivity, has little effect on the series resistance of the solar cell, and has little effect on the fill factor of the solar cell. At the same time, when the first doped layer 104 is located on the light-facing side of the substrate 102, the addition of the transparent conductive layer 302 does not affect the light entering the cell.

[0102] In some embodiments, the transparent conductive layer 302 is located on the surface of the first doped layer 104 of the metal contact region 1 away from the substrate 102. The contact between the first doped layer 104 and the second doped layer 106 of the metal contact region 1 is adjusted by the transparent conductive layer 302, the passivation of the first doped layer 104 of the metal contact region 1 is improved, and the probability that the carbon element of the metal contact region 1 affects the passivation effect of the solar cell is reduced. The doping concentration of the third doped layer 108 of the metal contact region 1 is greater than the doping concentration of the first doped layer 104 and the doping concentration of the second doped layer 106, respectively, which can reduce or offset the effect of the transparent conductive layer 302 on the series resistance of the solar cell, and reduce or do not affect the fill factor of the solar cell while improving the passivation effect of the first doped layer 104.

[0103] In other embodiments, the transparent conductive layer 302 is located on the surface of the first doped layer 104 of the metal contact area 1 and the non-metal contact area 2 away from the substrate 102. The contact between the first doped layer 104 and the second doped layer 106 of the metal contact area 1 and the non-metal contact area 2 is adjusted by the transparent conductive layer 302, the passivation of the first doped layer 104 of the metal contact area 1 and the non-metal contact area 2 is improved, and the probability that the carbon element in the metal contact area 1 and the non-metal contact area 2 affects the passivation effect of the solar cell is reduced, so as to further improve the passivation of the first doped layer 104 and further reduce the probability that the carbon element affects the passivation effect of the solar cell, and the transparent conductive layer 302 has a relatively small effect on the fill factor of the solar cell.

[0104] like Figure 3As shown, in one embodiment, the solar cell further includes: a tunneling layer 112, the tunneling layer 112 is located on the surface of the substrate 102, covering the metal contact area 1 and the non-metallic contact area 2; wherein the tunneling layer 112 is away from the surface of the substrate 102 and is adjacent to the first doping layer 104.

[0105] In one embodiment, the surface of the substrate 102 close to the first doping layer 104 and / or away from the first doping layer 104 is an arc-shaped surface. Figure 4 Take the surface of the substrate 102 away from the first doping layer 104 as an arc-shaped surface as an example. The area of ​​the arc-shaped surface is larger than the area of ​​the pyramid-shaped surface, so that the subsequent tunneling layer 112 or tunneling layer 404 adjacent thereto is more uniform, has a better blocking effect on the doping elements, has a larger manufacturing process window, and is easier to meet mass production requirements.

[0106] like Figure 4 As shown, in one embodiment, the surface of the substrate 102 away from the first doping layer 104 is an arc-shaped surface 402, and the solar cell further includes: a tunneling layer 404, a fourth doping layer 406 of the second conductivity type, a fifth doping layer 408 of the second conductivity type, an anti-reflection layer 410, a first gate 110 and a second gate 412.

[0107] The tunneling layer 404 is located on the surface of the substrate 102 away from the first doping layer 104 (arc-shaped surface 402), and the tunneling layer 404 covers the metal contact area 1 and the non-metal contact area 2; the fourth doping layer 406 is located on the surface of the tunneling layer 404 away from the substrate 102, covering the metal contact area 1 and the non-metal contact area 2; the fifth doping layer 408 is located in the fourth doping layer 406 of the metal contact area 1, and the surface of the fifth doping layer 408 away from the substrate 102 is flush with the surface of the fourth doping layer 406 away from the substrate 102, and the doping concentration of the second conductive type doping element in the fifth doping layer 408 is greater than the doping concentration of the second conductive type doping element in the fourth doping layer 406, and the second conductive type is opposite to the first conductive type. The anti-reflection layer 410 is respectively located on the surface of the fifth doping layer 408 away from the substrate 102 and the surface of the third doping layer 108 away from the substrate 102. The anti-reflection layer 410 on the surface of the fifth doping layer 408 extends to cover the surface of the fourth doping layer 406 away from the substrate 102, and the anti-reflection layer 410 on the surface of the third doping layer 108 extends to cover the surface of the second doping layer 106 away from the substrate 102. The first gate 110 is located on the surface of the anti-reflection layer 410 away from the third doping layer 108, covers the metal contact area 1, penetrates the anti-reflection layer 410 on the surface of the third doping layer 108, and contacts the third doping layer 108; the second gate 412 is located on the surface of the anti-reflection layer 410 away from the fifth doping layer 408, covers the metal contact area 1, penetrates the anti-reflection layer 410 on the fifth doping layer 408, and contacts the fifth doping layer 408.

[0108] Furthermore, the doping element of the second conductivity type in the fifth doping layer 408 is the same as the doping element of the second conductivity type in the fourth doping layer 406; in a plane parallel to the substrate 102, the size of the first gate 110 is smaller than the size of the third doping layer 108, and the size of the second gate 412 is smaller than the size of the fifth doping layer 408. The influence of process errors on the contact between the first gate 110 and the third doping layer 108 and the contact between the second gate 412 and the fifth doping layer 408 is avoided.

[0109] The present disclosure also provides a photovoltaic component, comprising a number of solar cells as described above, and / or a number of solar cells manufactured using the above-mentioned method for preparing solar cells; the solar cell comprises: a substrate, a first doping layer, a second doping layer and a third doping layer, the substrate comprising adjacent metal contact areas and non-metal contact areas; the first doping layer is located on the substrate and covers the metal contact areas and the non-metal contact areas; the second doping layer is located on a surface of the first doping layer away from the substrate, covers the metal contact areas and the non-metal contact areas, and the second doping layer contains carbon elements; the third doping layer is located on a surface of the second doping layer in the metal contact area away from the substrate; wherein the doping concentration of the first conductive type doping element in the third doping layer is greater than the doping concentration of the first conductive type doping element in the second doping layer, and the doping concentration of the first conductive type doping element in the second doping layer is greater than the doping concentration of the first conductive type doping element in the first doping layer.

[0110] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] The above-mentioned embodiments only express several implementation methods of the embodiments of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the embodiments of the present disclosure, and these all belong to the protection scope of the embodiments of the present disclosure.

Claims

1. A solar cell, characterized in that: include: A substrate, including adjacent metallic contact areas and non-metallic contact areas; A first doping layer, located on the substrate and covering the metal contact area and the non-metal contact area; A second doping layer, located on a surface of the first doping layer away from the substrate, covering the metal contact area and the non-metal contact area, wherein the second doping layer contains carbon; a third doped layer, located in the metal contact region, the second doped layer being away from the surface of the substrate; Among them, the doping concentration of the doping element of the first conductivity type in the third doping layer is greater than the doping concentration of the doping element of the first conductivity type in the second doping layer, and the doping concentration of the doping element of the first conductivity type in the second doping layer is greater than the doping concentration of the doping element of the first conductivity type in the first doping layer.

2. The solar cell according to claim 1, characterized in that The doping concentration of the carbon element in the second doping layer is greater than the doping concentration of the doping element of the first conductivity type.

3. The solar cell according to claim 1, characterized in that The solar cell further comprises: a transparent conductive layer, wherein the transparent conductive layer is located on a surface of the first doped layer in the metal contact region away from the substrate, or the transparent conductive layer is located on a surface of the first doped layer in the metal contact region and the non-metal contact region away from the substrate; Wherein, a surface of the transparent conductive layer away from the substrate is adjacent to the second doping layer.

4. The solar cell according to claim 1, characterized in that The solar cell further comprises: a barrier layer, located on a surface of the first doped layer away from the substrate and covering the metal contact area and the non-metal contact area; Wherein, a surface of the barrier layer away from the substrate is adjacent to the second doping layer.

5. A method for preparing a solar cell, characterized in that: include: providing a substrate comprising a contiguous metallic contact region and a non-metallic contact region; forming a first doping layer on the substrate, wherein the first doping layer covers the metal contact area and the non-metal contact area; forming a second doping layer containing carbon elements on a surface of the first doping layer away from the substrate, wherein the second doping layer covers the metal contact area and the non-metal contact area; Forming a third doping layer on a surface of the second doping layer in the metal contact region away from the substrate; Among them, the doping concentration of the doping element of the first conductivity type in the third doping layer is greater than the doping concentration of the doping element of the first conductivity type in the second doping layer, and the doping concentration of the doping element of the first conductivity type in the second doping layer is greater than the doping concentration of the doping element of the first conductivity type in the first doping layer.

6. The method for preparing a solar cell according to claim 5, characterized in that: Before forming a second doping layer containing carbon elements on a surface of the first doping layer away from the substrate, the method further includes: Forming a transparent conductive layer on the surface of the first doped layer in the metal contact area away from the substrate; or forming a transparent conductive layer on the surface of the first doped layer in the metal contact area and the non-metal contact area away from the substrate; Wherein, a surface of the transparent conductive layer away from the substrate is adjacent to the second doping layer.

7. The method for preparing a solar cell according to claim 5, characterized in that: The method for preparing the solar cell further comprises: Processing the surface of the substrate to obtain an arc-shaped surface; The arc-shaped surface is close to the first doping layer and / or far away from the first doping layer.

8. The method for preparing a solar cell according to claim 5, characterized in that: Before forming the first doping layer on the substrate, the method further includes: forming a tunneling layer on the surface of the substrate, wherein the tunneling layer covers the metal contact area and the non-metal contact area; Wherein, a surface of the tunneling layer away from the substrate is adjacent to the first doping layer.

9. The method for preparing a solar cell according to claim 8, characterized in that: The step of forming a tunneling layer on the surface of the substrate comprises: Using a low pressure chemical vapor deposition process, a first tunneling sublayer is formed on the surface of the substrate; Using a plasma enhanced chemical vapor deposition process, forming a second tunneling sublayer on a surface of the first tunneling sublayer away from the substrate; The process gas of the plasma enhanced chemical vapor deposition process includes nitrous oxide, and the tunneling layer includes the first tunneling sublayer and the second tunneling sublayer.

10. The method for preparing a solar cell according to claim 5, characterized in that: Before forming a second doping layer containing carbon elements on a surface of the first doping layer away from the substrate, the method further includes: forming a barrier layer on a surface of the first doped layer away from the substrate, wherein the barrier layer covers the metal contact area and the non-metal contact area; Wherein, a surface of the barrier layer away from the substrate is adjacent to the second doping layer.

11. A photovoltaic module, characterized in that: The invention comprises a plurality of solar cells according to any one of claims 1 to 4, and / or a plurality of solar cells manufactured by the method for manufacturing a solar cell according to any one of claims 5 to 10.

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