Preparation method of solar cell

Abstract

The invention relates to the technical field of solar cells, particularly provides a preparation method of a solar cell, and aims to solve the problem of how to further improve the passivation quality of the solar cell. In order to achieve the purpose, after a first passivation layer is deposited on any surface of the solar cell, laughing gas is introduced into the first passivation layer for oxidation treatment; and / or after a second passivation layer is deposited on any one surface, ammonia gas is introduced into the second passivation layer for hydrogenation treatment. According to the invention, oxidation treatment is carried out on the first passivation layer, so that the purposes of reducing oxygen defects and recombination loss of the first passivation layer and improving the passivation quality of the first passivation layer are achieved; the second passivation layer is subjected to hydrotreating, so that the purposes of reducing dangling bonds on the surface of the second passivation layer and improving the passivation quality of the second passivation layer are achieved, and an effective solution is provided for further improving the passivation quality of the solar cell.

Description

Technical Field

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

[0002] With the widespread use of solar cells, how to improve the passivation quality of solar cells has become a research hotspot for solar cells. At present, high-efficiency solar cells such as TopCon (Tunnel Oxide Passivated Contact) cells and BC (Back Contact) structure cells often use aluminum oxide (AlOx) or silicon oxide for passivation treatment, and then stack silicon nitride (SiNx). For example, TopCon uses silicon oxide, polycrystalline silicon (poly) and silicon nitride to achieve cell passivation. However, there is still room for further improvement in the passivation quality of the above solar cells.

[0003] Accordingly, the art needs a new solar cell preparation solution to solve the above problems. Summary of the invention

[0004] The present application aims to solve the above technical problem, that is, to solve the problem of how to further improve the passivation quality of solar cells.

[0005] In a first aspect, the present application provides a method for preparing a solar cell, comprising: after a first passivation layer is deposited on any surface of the solar cell to form a first passivation layer, nitrous oxide is introduced into the first passivation layer for oxidation treatment, and any surface is any surface of a first surface and a second surface of a solar cell substrate that are relatively arranged; and / or, after a second passivation layer is deposited on any surface to form a second passivation layer, ammonia is introduced into the second passivation layer for hydrogenation treatment.

[0006] In a technical solution of the method for preparing the solar cell, when the first passivation layer is oxidized by introducing nitrous oxide, the method further comprises: introducing an inert gas to oxidize the first passivation layer.

[0007] In a technical solution of the above-mentioned method for preparing solar cells, the inert gas is argon, and the ratio of argon to nitrous oxide is between 1:5 and 4:5.

[0008] In a technical solution of the above-mentioned method for preparing a solar cell, the first passivation layer at least includes: an aluminum oxide layer, and the second passivation layer at least includes: a silicon oxide layer.

[0009] In a technical solution of the above-mentioned method for preparing the solar cell, the first passivation layer is oxidized by introducing laughing gas, and the process further includes: during the annealing process of the first passivation layer, or after the annealing process is completed, the first passivation layer is oxidized by introducing laughing gas.

[0010] In a technical solution of the above-mentioned method for preparing the solar cell, the flow rate of the laughing gas introduced is between 7000sccm and 17000sccm and the introduction time is between 100 seconds and 700 seconds.

[0011] In a technical solution of the above-mentioned method for preparing solar cells, the flow rate of the introduced ammonia gas is between 7000 sccm and 17000 sccm and the introduction time is between 100 seconds and 700 seconds.

[0012] In a second aspect, the present application provides a method for preparing a TopCon cell, comprising: forming a first passivation layer on a first surface of a substrate; forming a second passivation layer on a second surface of the substrate; oxidizing the first passivation layer using the method for preparing a solar cell as described in the first aspect or any corresponding technical solution thereof; and / or hydrogenating the second passivation layer using the method for preparing a solar cell as described in the first aspect or any corresponding technical solution thereof; and forming electrodes on the first passivation layer and the second passivation layer, respectively.

[0013] In a third aspect, the present application provides a method for preparing a TBC battery, comprising: forming a second passivation layer on the second surface of a substrate; forming an alternately arranged p-region and an n-region on the second passivation layer based on an isolation region; forming a first passivation layer on the alternately arranged p-region and n-region; forming an electrode on the first passivation layer; after forming the second passivation layer on the second surface of the substrate, hydrogenating the second passivation layer using the method for preparing a solar cell as described in the first aspect or any corresponding technical solution thereof, and / or oxidizing the first passivation layer using the method for preparing a solar cell as described in the first aspect or any corresponding technical solution thereof after forming the first passivation layer on the alternately arranged p-region and n-region.

[0015] The above one or more technical solutions of this application have at least one or more of the following Beneficial effects:

[0016] In the technical solution of the present application, by passing laughing gas through the first passivation layer for oxidation treatment, oxygen ions are injected into the first passivation layer to reduce oxygen defects and composite losses, thereby improving the passivation quality of the first passivation layer; or, by passing ammonia through the second passivation layer for hydrogenation treatment, hydrogen ions are injected into the second passivation layer to reduce surface dangling bonds, thereby improving the passivation quality of the second passivation layer. This method achieves the purpose of improving the passivation quality of solar cells, increasing the cell opening voltage, and improving the cell conversion efficiency, and provides an effective solution for further improving the passivation quality of solar cells.

[0017] In the technical solution for implementing the present application, nitrous oxide and an inert gas are introduced into the first passivation layer for oxidation treatment. Since the inert gas does not participate in the reaction, the gas flow rate is increased, the reaction rate of nitrous oxide is increased, and the deposition rate is reduced under the condition of a constant pressure and a constant nitrous oxide flow rate. This allows more oxygen atoms to be injected into the surface of the first passivation layer and reduces the thickness of the oxide layer generated on the surface, thereby achieving a better passivation effect with less nitrous oxide.

[0018] In the technical solution for implementing the present application, the purpose of further improving the passivation quality of solar cells is achieved by controlling the flow range and time range of the introduction of nitrous oxide or ammonia, or controlling the ratio of inert gas to nitrous oxide within a preset ratio range. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 It is a schematic flow chart of the main steps of a method for preparing a solar cell according to an embodiment of the present application;

[0021] Figure 2 A schematic flow chart of the main steps of a method for preparing a TopCon battery according to an embodiment of the present application;

[0022] Figure 3 is a schematic diagram of the structure of a TopCon battery prepared according to a method for preparing a TopCon battery according to an embodiment of the present application;

[0023] Figure 4 This is a schematic diagram of a double-sided poly TopCon battery structure according to an embodiment of the present application;

[0024] Figure 5 It is a schematic flow chart of the main steps of a method for preparing a TBC battery according to an embodiment of the present application;

[0025] Figure 6 It is a schematic diagram of the structure of a TBC battery prepared according to a method for preparing a TBC battery according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

[0027] It should be noted that, in the description of the present application, the terms "first", "second" etc. are used to distinguish similar objects, and need not be used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable in appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, the process, method, system, product or equipment comprising a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0028] The terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two components, a wireless connection, or a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances. In addition, if the meaning of "and / or" appears in this application, it includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0029] In the embodiments of the present application, a method for preparing a solar cell is provided. Figure 1 , Figure 1 FIG. 1 is a schematic flow chart of the main steps of a method for preparing a solar cell according to an embodiment of the present application. Figure 1 As shown, it mainly includes the following steps S101:

[0030] Step S101, after a first passivation layer is deposited on any surface of the solar cell to form a first passivation layer, nitrous oxide is introduced into the first passivation layer for oxidation treatment, and the any surface is any surface of a first surface and a second surface of the solar cell substrate that are relatively arranged; and / or, after a second passivation layer is deposited on any surface to form a second passivation layer, ammonia is introduced into the second passivation layer for hydrogenation treatment.

[0031] In this embodiment, the first passivation layer and the second passivation layer represent two types of passivation layers. Specifically, the first passivation layer needs to be oxidized by the introduction of nitrous oxide, that is, by injecting oxygen ions into the first passivation layer, reducing oxygen defects in the first passivation layer, thereby reducing carrier recombination losses, thereby achieving the effect of improving the passivation quality of the first passivation layer. The second passivation layer needs to be hydrogenated by the introduction of ammonia, that is, by injecting hydrogen ions into the second passivation layer, reducing dangling bonds on the surface of the second passivation layer, thereby improving the passivation quality of the second passivation layer.

[0032] Specifically, the above step S101 includes the following situations:

[0033] (1) A first passivation layer is formed on any surface of the solar cell substrate, and laughing gas can be introduced to oxidize the first passivation layer.

[0034] (2) A second passivation layer is formed on any surface of the solar cell substrate. Ammonia gas can be introduced to hydrogenate the second passivation layer.

[0035] (3) The first passivation layer is formed on two surfaces of the solar cell substrate that are arranged opposite to each other. At this time, laughing gas can be introduced into both of the first passivation layers formed on the two surfaces for oxidation treatment; or laughing gas can be introduced into one of the first passivation layers for oxidation treatment. When selecting one of the first passivation layers on the first surface and the second surface for oxidation treatment, the side with greater benefits can be optimized based on cost.

[0036] (4) The second passivation layer is formed on two surfaces of the solar cell substrate that are arranged opposite to each other. In this case, ammonia gas can be introduced into the second passivation layers formed on both surfaces for hydrogenation treatment; or ammonia gas can be introduced into one of the second passivation layers for hydrogenation treatment. When one of the second passivation layers on the first surface and the second surface is selected for hydrogenation treatment, the aspect with greater benefits can be optimized based on cost.

[0037] (5) A first passivation layer and a second passivation layer are formed on two surfaces of the solar cell substrate that are arranged opposite to each other. In this case, after the first passivation layer is formed, laughing gas is introduced to perform oxidation treatment, and after the second passivation layer is formed, ammonia is introduced to perform hydrogenation treatment. Alternatively, the first passivation layer and the second passivation layer can be selected to perform oxidation or hydrogenation treatment based on cost and benefit.

[0038] (6) A first passivation layer and a second passivation layer (or a second passivation layer and a first passivation layer) are formed on either surface of the solar cell substrate. In this case, after the first passivation layer is formed, nitrous oxide may be introduced for oxidation treatment, and after the second passivation layer is formed, ammonia may be introduced for hydrogenation treatment. Alternatively, the first passivation layer and the second passivation layer may be selected for oxidation or hydrogenation based on cost and benefit.

[0039] It should be noted that the first passivation layer and the second passivation layer can exist in the form of a single layer or multiple layers in the solar cell. When there are multiple passivation layers, the first passivation layer and the second passivation layer can be stacked in any order. When it is necessary to improve the passivation performance of the solar cell passivation layer, one or more passivation layers can be selected for optimization. The specific optimization method is to introduce corresponding gases for oxidation or hydrogenation according to the type of passivation layer.

[0040] Based on the above step S101, this embodiment achieves the effect of injecting oxygen ions into the first passivation layer by passing laughing gas through the first passivation layer for oxidation treatment, so as to reduce oxygen defects and composite losses in the first passivation layer, thereby improving the passivation quality of the first passivation layer. And / or, by passing ammonia through the second passivation layer for hydrogenation treatment, hydrogen ions are injected into the second passivation layer to reduce dangling bonds on the surface of the second passivation layer, thereby improving the passivation quality of the second passivation layer. This method achieves the purpose of improving the passivation quality of solar cells, increasing the cell opening voltage, and improving the cell conversion efficiency, and provides an effective solution for further improving the passivation quality of solar cells.

[0041] In an optional technical solution, the first passivation layer includes at least an aluminum oxide layer, and the second passivation layer includes at least a silicon oxide layer. It is understandable that the present application does not impose specific restrictions on the first passivation layer and the second passivation layer. As long as the optimization principle is the same, the method of the present application can be used to improve the passivation quality of the passivation layer. As an example, the first passivation layer can be aluminum oxide (Al x O y ) layer, the second passivation layer can be silicon oxide (Si x O y ) layer or tunnel oxide layer, namely, ultra-thin silicon oxide and polysilicon layer (SiO2+poly).

[0042] In an optional technical solution, when the first passivation layer is oxidized by introducing nitrous oxide, the method further includes: introducing an inert gas to oxidize the first passivation layer.

[0043] In this embodiment, the inert gas refers to a gas that does not participate in the current reaction. When a certain pressure and a constant flow rate of nitrous oxide are introduced, the inert gas can dilute the nitrous oxide and increase the gas flow rate, thereby increasing the oxygen ions pushed into the oxide layer (such as an aluminum oxide passivation layer) and reducing the oxygen ion deposition rate, thereby reducing the thickness of the oxide layer generated on the battery surface and avoiding the problem of the oxide layer being too thick affecting the battery contact performance.

[0044] In one embodiment, the inert gas that can be used includes but is not limited to argon and hydrogen, and nitrous oxide can also be replaced by ozone.

[0045] In one implementation, taking the TopCon cell as an example, Table 1 is a cell performance data table of a solar cell passivation layer optimization comparison experiment: Table 1. Solar cell passivation layer optimization comparison experiment cell performance data table Voc(mV) Jsc(A) FF(%) EFF(%) Experiment 1 733 15.99 85 26.1 Experiment 2 735 15.96 85 26.12 Experiment 3 734.5 15.97 85.2 26.18

[0046] In the above Table 1, Experiment 1 is the battery data obtained by using the conventional preparation method; Experiment 2 is the battery data obtained after the first passivation layer and the second passivation layer are formed, respectively, by introducing nitrous oxide and ammonia for treatment; Experiment 3 is the battery data obtained after the first passivation layer is formed, by introducing nitrous oxide and argon, and by introducing ammonia for treatment after the second passivation layer is formed, based on Experiment 1.

[0047] Among them, Voc is the open circuit voltage, which refers to the output voltage of the battery when there is no load, and the unit is millivolt (mV). Generally, the higher the open circuit voltage, the greater the potential difference of the battery and the greater the output power; Jsc is the short circuit current density, which refers to the current density generated per unit area when the output voltage of the solar cell is 0V under standard test conditions, and the unit is ampere (A). Generally speaking, the greater the short circuit current density of the solar cell, the higher its output power and efficiency; FF is the fill factor, which refers to the ratio of the product of the current and voltage when the battery has maximum output power to the product of the short circuit current and open circuit voltage, and the unit is percentage (%). The higher the fill factor, the more light is absorbed and converted into electrical energy, and the better the performance of the solar cell; EFF is the cell conversion efficiency, which refers to the efficiency of the solar cell in converting solar radiation into electrical energy, usually expressed as a percentage (%). The higher the conversion efficiency, the better the performance of the solar cell.

[0048] According to Table 1 above, the optimization treatment of the first passivation layer and the second passivation layer by introducing laughing gas and argon respectively (Experiment 2) has been improved in terms of open circuit voltage and battery conversion efficiency compared with the TopCon battery prepared by the conventional method (Experiment 1). The oxidation treatment of the first passivation layer by introducing argon when introducing laughing gas (Experiment 3) has been improved in terms of open circuit voltage, fill factor, and battery conversion efficiency compared with the TopCon battery prepared by the conventional method (Experiment 1). In addition, compared with Experiment 2, not only the short-circuit current has been improved in Experiment 3, but the fill factor and battery conversion efficiency have also been further improved.

[0049] In an optional technical solution, the ratio of the inert gas to the laughing gas is within a preset ratio range.

[0050] In this embodiment, the overall oxygen concentration can be increased by modulating the ratio of nitrous oxide and argon gas, so that more oxygen atoms in the nitrous oxide can enter the surface of the oxide layer, which plays a promoting role, thereby reducing oxygen defects on the surface of the oxide layer, and releasing more hydrogen ions, thereby stabilizing the surface of the silicon material, achieving the purpose of achieving a better passivation effect with less nitrous oxide.

[0051] In an optional technical solution, the inert gas is argon, and the preset ratio range is one-fifth to four-fifths.

[0052] In this embodiment, the preset ratio range of argon gas to nitrous oxide is one-fifth to four-fifths, such as the ratio of argon gas to nitrous oxide is 1:5, 2:5, 3:5, 4:5, and a preferred ratio range is two-fifths to three-fifths.

[0053] In an optional technical solution, the step of introducing laughing gas into the first passivation layer for oxidation treatment further includes: introducing laughing gas into the first passivation layer for oxidation treatment during the annealing process of the first passivation layer or after the annealing process is completed.

[0054] In the present embodiment, annealing refers to exposing the battery to a high temperature environment to improve the performance of the battery by heat. The defects in the battery material (such as defects in the grains, holes in the oxide, etc.) can be reduced by annealing. Wherein, the first passivation layer such as aluminum oxide usually requires annealing after deposition. During the aluminum oxide annealing process, or after the annealing is completed, laughing gas can be introduced into it for oxidation to enhance the passivation effect of the aluminum oxide passivation layer.

[0055] In an optional technical solution, the flow rate of the laughing gas is between 7000 sccm and 17000 sccm and the introduction time is between 100 seconds and 700 seconds.

[0056] In the present embodiment, the flow of laughing gas is between 7000sccm and 17000sccm, wherein, sccm represents standard cubic centimeter per minute, and the time of introduction is between 100 seconds and 700 seconds. Exemplary, the flow of laughing gas is 7000sccm, 9000sccm, 11000sccm, 13000ccm, 15000ccm or 17000sccm, and the time of introduction is 120 seconds, 200 seconds, 280 seconds, 360 seconds, 440 seconds, 520 seconds or 600 seconds. As a preferred embodiment, the flow of laughing gas is between 8000sccm and 16000sccm and the time of introduction is between 120 seconds and 600 seconds.

[0057] In one embodiment, a PECVD (Plasma Enhance Chemical Vapour Deposition) device may be used with a power of 1.3 kW to 1.6 kW to deposit a first passivation layer, and then 8000 sccm to 16000 sccm of laughing gas may be introduced for 120 s to 600 s.

[0058] In an optional technical solution, the flow rate of the introduced ammonia gas is between 7000 sccm and 17000 sccm and the introduction time is between 100 seconds and 700 seconds.

[0059] In the present embodiment, the flow rate of ammonia gas is between 7000sccm and 17000sccm, and the time of passage is between 100 seconds and 700 seconds. Exemplarily, the flow rate of ammonia gas is 7000sccm, 9000sccm, 11000sccm, 13000ccm, 15000ccm or 17000sccm, and the time of passage is 120 seconds, 200 seconds, 280 seconds, 360 seconds, 440 seconds, 520 seconds or 600 seconds. As a preferred embodiment, the flow rate of ammonia gas is between 8000sccm and 16000sccm and the time of passage is between 120 seconds and 600 seconds.

[0060] In one embodiment, a PECVD (Plasma Enhance Chemical Vapour Deposition) device may be used with a power of 1.3 kW to 1.6 kW to deposit the second passivation layer, and then 8000 sccm to 16000 sccm of ammonia gas may be introduced for 120 s to 600 s.

[0061] In this embodiment, by controlling the flow range and time range of the laughing gas or ammonia gas, or controlling the ratio of the inert gas to the laughing gas within a preset ratio range, the purpose of further improving the passivation quality of the solar cell passivation layer is achieved.

[0062] It is understandable that the above-mentioned method for preparing solar cells can be applied in the preparation process of various solar cells, such as TopCon cells, TopCon cells with double-sided poly structures, and cells with BC structures, such as TBC cells.

[0063] Tunneling oxide passivation contact (TopCon) cells are generally N-substrates. The unique tunneling characteristics of the tunneling layer can significantly reduce the recombination of electrons and holes, greatly increasing the opening voltage and current density of the cell. In particular, the limit efficiency of double-sided poly structure TOPCON cells is around 28.5%, which is closest to the limit efficiency of silicon 29%. How to further optimize the TopCon cell process and improve cell efficiency is one of the hot topics in the photovoltaic industry today.

[0064] Furthermore, the present application also provides a method for preparing a TopCon battery, see the attached Figure 2 , Figure 2 FIG. 1 is a schematic flow chart of the main steps of a method for preparing a TopCon battery according to an embodiment of the present application. Figure 2 As shown, the embodiment of the present application mainly includes the following steps S201 to S204:

[0065] Step S201, forming a first passivation layer on a first surface of a substrate.

[0066] Step S202, forming a second passivation layer on the second surface of the substrate.

[0067] Step S203, oxidizing the first passivation layer by using the solar cell preparation method in the first aspect or any corresponding technical solution above; and / or, hydrogenating the second passivation layer by using the solar cell preparation method in the first aspect or any corresponding technical solution above.

[0068] Step S204: forming electrodes on the first passivation layer and the second passivation layer respectively.

[0069] Specifically, the first passivation layer is aluminum oxide, for example, and the second passivation layer is a tunneling oxide layer, that is, an ultra-thin silicon oxide and doped polysilicon layer. After the first passivation layer is formed on the first surface of the substrate, the first passivation layer is oxidized by passing nitrous oxide (or nitrous oxide and argon) into the first passivation layer using the solar cell preparation method in any of the above technical solutions. And / or, the second passivation layer is hydrogenated by passing ammonia into the second passivation layer using the solar cell preparation method in any of the above technical solutions. For details, please refer to Figure 1The steps in the illustrated embodiment are not described in detail here. Metal electrodes are formed on the first passivation layer and the second passivation layer after the optimization process, respectively. The process of forming the metal electrodes can refer to the prior art and is not described in detail here.

[0070] In an optional embodiment, Figure 3 Schematic diagram of the structure of a TopCon battery prepared according to a method for preparing a TopCon battery in one embodiment of the present application, such as Figure 3 As shown, the preparation process of TopCon battery is as follows:

[0071] Step S301: Figure 3 The Si (such as N-type silicon wafer) is textured and cleaned, and then sent to the boron diffusion machine for boron diffusion. This process will generate P+ (B diffusion) area and BSG (Boro-silicate Glass). Among them, the cleaning can adopt the industrial standard wet cleaning process.

[0072] Step S302: Since the diffusion process will form a diffusion layer on the surface and periphery of the silicon wafer, the peripheral diffusion layer is prone to short circuit, and the surface diffusion layer and surface finish will affect the battery conversion efficiency. Therefore, after step S301, it is necessary to clean and remove the BSG layer and the back PN junction generated during the diffusion doping process of the Si wafer, and perform polishing to avoid the above problems.

[0073] Step S303, further cleaning the battery.

[0074] Step S304, using PECVD to deposit a SiO2 layer and a PE-N poly layer on the back of the battery. Similar to step S301, this process will form PSG (Phosphoro-silicate Glass) on the surface and periphery of the silicon wafer.

[0075] Step S305, after step S304, placing the battery on an annealing machine to perform annealing treatment on the battery, and crystallizing the pe-n poly into N poly-Si.

[0076] Step S306, cleaning to remove the PSG plating and performing polishing.

[0077] Step S307, cleaning the battery.

[0078] Step S308: using ALD (Atomic Layer Deposition) equipment to deposit AlO on the front of the battery. x layer.

[0079] Step S309: PECVD is used at a power of 1.3-1.6 kW to deposit AlO on the front side of the battery. xThe layer is annealed and oxidized, such as by passing 8000-16000 sccm of nitrous oxide for 120-600 seconds. The specific steps can be found in other embodiments of the present application and will not be repeated here. x Layer, SiN x The layer can reduce the reflection of sunlight and increase the light absorption rate of the battery.

[0080] Step S310, using PECVD at a power of 1.3-1.6kw to perform hydrogenation treatment on the back side of the battery (tunnel oxide layer), such as passing 8000-16000sccm of ammonia for 120-600s. The specific steps can be found in other embodiments of this application and will not be repeated here. Then SiN is deposited on the back side. x layer.

[0081] Step S311, screen printing and sintering are performed on the front and back sides of the battery to form Ag electrodes.

[0082] For the front side of the battery, the SiN x Before deposition, laughing gas was introduced for oxidation treatment. Due to plasma oxidation, the energy released caused the OH chain to break, that is, the Al-OH ratio was reduced and the O-Al-O ratio was increased, thereby reducing oxygen defects and releasing more H to improve the passivation effect, ultimately achieving the goal of increasing AlO x For the purpose of passivation effect, the above optimization treatment increases the open circuit voltage of the battery by about 1mv. x Before deposition, ammonia is introduced into the polysilicon and SiO2 layers for hydrogenation treatment, which increases the H content in the second passivation layer, reduces the density of unsaturated dangling bonds, and enhances the passivation effect. The battery open circuit voltage is increased by about 1mv. The front and back of the battery are optimized at the same time, and the battery open voltage is increased by about 1.4-1.7mv, and the efficiency is increased by about 0.1%. In summary, the TopCon battery prepared through the above steps not only improves the quality of the passivation layer, but also improves the open circuit voltage and battery conversion efficiency.

[0083] Optional, Figure 4 Schematic diagram of a double-sided poly TopCon battery structure according to an embodiment of the present application. Figure 4 As shown in the figure, the double-sided poly TopCon cell forms tunnel oxide layers on the two opposite surfaces of the substrate, namely, an ultra-thin silicon oxide layer (SiO2) and a polysilicon layer (poly-Si). Unlike the single-sided poly TopCon cell, one side is Ppoly-Si, i.e., a P-doped polysilicon layer, and the other side is N poly-Si, i.e., an N-doped polysilicon layer.

[0084] According to the method for preparing solar cells in any of the above technical solutions, for double-sided poly TopCon cells, during the preparation process, ammonia gas can be introduced into the front and / or back SiO2 layer (tunneling oxide layer) for hydrogenation treatment to improve the passivation performance of the cell.

[0085] Furthermore, the present application also provides a method for preparing a TBC battery. Figure 5 , Figure 5 FIG. 1 is a flow chart of the main steps of a method for preparing a TBC battery according to an embodiment of the present application. Figure 5 As shown, the preparation method of the TBC battery mainly includes the following steps:

[0086] Step S501: forming a second passivation layer on the second surface of the substrate.

[0087] Step S502 , forming alternately arranged p-regions and n-regions on the second passivation layer based on the isolation region.

[0088] Step S503 , forming a first passivation layer on the alternately arranged p-regions and n-regions.

[0089] Step S504: forming an electrode on the first passivation layer.

[0090] Step S505, after forming a second passivation layer on the second surface of the substrate, the second passivation layer is hydrogenated by using the method for preparing a solar cell in the first aspect or any corresponding technical solution thereof, and / or after forming a first passivation layer on the spaced p-region and n-region, the first passivation layer is oxidized by using the method for preparing a solar cell in the first aspect or any corresponding technical solution thereof.

[0091] It should be noted that TBC cells are a fusion of TopCon and BC technologies, and part of the process is the same as TOPCon, that is, the back side uses a tunnel oxide layer as a passivation layer. Figure 6 To explain the above steps:

[0092] In this embodiment, a second passivation layer (SiO2) is formed on the second surface of the substrate (Si); a p-region and an n-region arranged at intervals are formed on the second passivation layer based on an isolation region (such as a Si substrate), such as Figure 6 The p-poly and n-poly in the substrate; forming a first passivation layer (AlO x ); then forming an electrode on the first passivation layer, such as Figure 6 The n-electrode and the p-electrode in the.

[0093] It should be noted that one treatment method is, after forming the second passivation layer on the second surface of the substrate in the above step S501, the second passivation layer is subjected to hydrogenation treatment by using the solar cell preparation method in any of the above technical solutions. After forming the first passivation layer on the p-region and n-region arranged at intervals in the above step S503, the first passivation layer is subjected to oxidation treatment by using the solar cell preparation method in any of the above technical solutions. For specific steps, please refer to the steps of other embodiments of the present application, which will not be repeated here.

[0094] Another processing method is to select to form the second passivation layer on the substrate second surface or to form a step in the first passivation layer on the p district and the n district arranged at intervals, and then feed ammonia or laughing gas to hydrogenate or oxidize it. With reference to other embodiments above, can select based on processing cost and optimizing income.

[0095] It is understandable that other process flows, such as cleaning and texturing, masking, laser grooving, forming a first passivation layer or a second passivation layer on the first surface, forming an anti-reflection layer (SiN) on the first surface and the second surface, x The methods of metallization and the like can all be referred to the prior art and will not be described in detail here.

[0096] Compared with the conventional preparation method, the TBC battery prepared by the above steps not only has improved quality of the passivation layer, but also has further improved open circuit voltage and battery conversion efficiency.

[0097] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effect of the present application, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders. These changes are within the scope of protection of the present application.

[0098] So far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present application.

Claims

1. A method for preparing a solar cell, characterized in that: include: After a first passivation layer is deposited on any surface of the solar cell to form a first passivation layer, the first passivation layer is oxidized by introducing laughing gas, wherein the any surface is any one of a first surface and a second surface of the solar cell substrate that are arranged opposite to each other; And / or, after a second passivation layer is deposited on any surface, ammonia gas is introduced into the second passivation layer for hydrogenation treatment.

2. The method for preparing a solar cell according to claim 1, characterized in that: When the first passivation layer is subjected to an oxidation treatment by introducing laughing gas, the method further comprises: An inert gas is introduced to oxidize the first passivation layer.

3. The method for preparing a solar cell according to claim 2, characterized in that: The inert gas is argon, and the ratio of argon to nitrous oxide is between 1:5 and 4:

5.

4. The method for preparing a solar cell according to claim 1, characterized in that: The first passivation layer at least includes an aluminum oxide layer, and the second passivation layer at least includes a silicon oxide layer.

5. The method for preparing a solar cell according to claim 1, characterized in that: The first passivation layer is introduced with laughing gas for oxidation treatment, and further comprises: During the annealing process of the first passivation layer, or after the annealing process is completed, laughing gas is introduced into the first passivation layer for oxidation treatment.

6. The method for preparing a solar cell according to claim 1, characterized in that: The flow rate of the laughing gas is between 7000 sccm and 17000 sccm and the introduction time is between 100 seconds and 700 seconds.

7. The method for preparing a solar cell according to claim 1, characterized in that: The flow rate of the ammonia gas is between 7000 sccm and 17000 sccm, and the introduction time is between 100 seconds and 700 seconds.

8. A method for preparing a TopCon battery, characterized in that: include: forming a first passivation layer on the first surface of the substrate; forming a second passivation layer on the second surface of the substrate; The first passivation layer is oxidized by the method for preparing a solar cell according to any one of claims 1 to 7; and / or, hydrogenating the second passivation layer using the method for preparing a solar cell according to any one of claims 1 to 7; Electrodes are formed on the first passivation layer and the second passivation layer, respectively.

9. A method for preparing a TBC battery, characterized in that: include: forming a second passivation layer on the second surface of the substrate; forming a p-region and an n-region arranged at intervals on the second passivation layer based on the isolation region; forming a first passivation layer on the p-region and the n-region arranged at intervals; forming an electrode on the first passivation layer; After forming a second passivation layer on the second surface of the substrate, the second passivation layer is hydrogenated by the method for preparing a solar cell as described in any one of claims 1 to 7, and / or after forming a first passivation layer on the spaced p-region and n-region, the first passivation layer is oxidized by the method for preparing a solar cell as described in any one of claims 1 to 7.

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