WO2020258884A1

WO2020258884A1 - Method for manufacturing crystalline silicon solar cell and crystalline silicon solar cell

Info

Publication number: WO2020258884A1
Application number: PCT/CN2020/074314
Authority: WO
Inventors: 张洪超; 童洪波; 李华; 刘继宇
Original assignee: 泰州隆基乐叶光伏科技有限公司
Priority date: 2019-06-24
Filing date: 2020-02-05
Publication date: 2020-12-30

Abstract

Disclosed are a method for manufacturing a crystalline silicon solar cell and a crystalline silicon solar cell. The method comprises the following steps: providing a cell precursor, the cell precursor comprising a crystalline silicon solar cell substrate, and a dielectric layer formed on the front and/or back of the crystalline silicon solar cell substrate, the dielectric layer being provided with a gate electrode electroplating region and an electroplating contact forming region that expose the crystalline silicon solar cell substrate; performing sintering in the electroplating contact forming region of the cell precursor to form an electroplating contact; and electroplating the cell precursor formed with the electroplating contact to form a metal electrode layer in the gate electrode electroplating region, during electroplating, the electroplating contact being electrically connected to the negative electrode of an electroplating device. The solution implements electroplating without a seed layer.

Description

Method for manufacturing crystalline silicon solar cell and crystalline silicon solar cell

This application requires that it be submitted to the Chinese Patent Office on June 24, 2019, the application number is 201910548673.3, the title of the invention is "Method for manufacturing back-contact solar cells and back-contact solar cells", and the Chinese Patent Office on June 24, 2019, The priority of the Chinese patent application with the application number 201910548287.4 and the title of the invention is "Method for manufacturing crystalline silicon solar cell and crystalline silicon solar cell", the entire content of which is incorporated in this application by reference.

Technical field

The present invention generally relates to the technical field of solar photovoltaic power generation, in particular to a method for manufacturing a crystalline silicon solar cell and a crystalline silicon solar cell.

Background technique

Crystal silicon solar cells are currently the solar cells with the highest market share due to their high energy conversion efficiency. How to improve the photoelectric conversion efficiency of crystalline silicon solar cells while reducing their production costs is the biggest problem facing the industry. At present, in large-scale crystalline silicon solar cell manufacturing, screen printing is usually used to realize the metallization process of crystalline silicon solar cells. However, the precision of screen printing is limited, and the topography of printed electrodes fluctuates. After printing and sintering, the electrodes are widened. Large, resulting in a relatively low height and width of the grid formed, thereby reducing the effective light-receiving area of the light-receiving surface of the crystalline silicon solar cell, and the series resistance of the crystalline silicon solar cell made by screen printing is relatively large.

Through electroplating or light-induced electroplating, the grid of crystalline silicon solar cells can be selectively formed, effectively reducing the shading of the grid and effectively reducing the resistance of the grid and the series resistance of the crystalline silicon solar cell. At present, electroless plating and light-induced electroplating technology are used to replace the traditional screen printing technology, and a uniform and dense plating layer can be formed by electroplating nickel and copper with good efficiency.

The existing electroplating technology to form the grid lines and electrodes of crystalline silicon solar cells requires printing or electroless plating on a seed layer, and then electroplating on the seed layer by light-induced electroplating or electroplating to form electrodes, which need to be supplemented by light conditions and masks , The operation is complicated and the production efficiency is low.

Summary of the invention

In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a method for manufacturing a crystalline silicon solar cell and a crystalline silicon solar cell that can form a metal electrode layer by electroplating without forming a seed layer.

In the first aspect, the present invention provides a method for manufacturing a crystalline silicon solar cell, including the following steps:

A battery precursor is provided; the battery precursor includes a crystalline silicon solar cell substrate, and a dielectric layer formed on the front and/or back of the crystalline silicon solar cell substrate; the dielectric layer is provided with exposed The gate electrode electroplating area and the electroplating contact forming area of the crystalline silicon solar cell substrate;

Sintering in the electroplating contact formation area of the battery precursor to form electroplating contacts;

Electroplating the battery precursor formed with the electroplating contacts to form a metal electrode layer in the gate electrode electroplating area, and the electroplating contacts are electrically connected with the negative electrode of the electroplating equipment during electroplating.

In a second aspect, the present invention provides a crystalline silicon solar cell prepared by the above method, comprising a crystalline silicon solar cell substrate, and a dielectric layer is formed on the front and/or back of the crystalline silicon solar cell substrate; The electric layer is provided with a gate electrode plating area and a plating contact forming area exposing the substrate of the crystalline silicon solar cell. The gate electrode plating area is deposited with a metal electrode layer, the metal electrode layer and the crystal The silicon solar cell substrate is in ohmic contact, and the electroplated contact forming area is sintered to form electroplated contacts.

In the above solution, the method for manufacturing a crystalline silicon solar cell is sintered to form electroplated contacts, and the electroplated contacts formed by sintering are in ohmic contact with the substrate of the crystalline silicon solar cell, so that there is no need to prepare an electroplating seed layer during electroplating, which simplifies the process flow and solves This solves the problem that the cells cannot be electroplated because they are not conductive.

The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented in accordance with the content of the description, and in order to make the above and other objectives, features and advantages of the present invention more obvious and understandable. In the following, specific embodiments of the present invention are specifically cited.

Description of the drawings

By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, purposes and advantages of the present application will become more apparent:

FIG. 1 is a flowchart of a method for manufacturing a crystalline silicon solar cell according to an embodiment of the present invention;

2 is a front view of a battery precursor provided by an embodiment of the present invention;

Figure 3 is a cross-sectional view of Figure 2 A-A;

4 is a schematic diagram of the structure of FIG. 3 after forming a metal electrode layer;

5 is a flowchart of another method for manufacturing a crystalline silicon solar cell according to an embodiment of the present invention;

Figure 6 is a front view of another battery precursor provided by an embodiment of the present invention;

Fig. 7 is a B-B sectional view of Fig. 6.

Specific embodiment

The application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described here are only used to explain the related invention, but not to limit the invention. In addition, it should be noted that, for ease of description, only the parts related to the invention are shown in the drawings.

It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other if there is no conflict. Hereinafter, the present application will be described in detail with reference to the drawings and in conjunction with embodiments.

Example one

As shown in Fig. 1, a method for manufacturing a crystalline silicon solar cell provided by the present invention includes the following steps:

S11: Provide a battery precursor; the battery precursor includes a crystalline silicon solar cell substrate, and a dielectric layer formed on the front and/or back of the crystalline silicon solar cell substrate; the dielectric layer is provided with The gate electrode plating area and the plating contact forming area of the crystalline silicon solar cell substrate are exposed.

As shown in Figures 2 to 4, the dielectric layer 5 can be formed on the front and/or back of the crystalline silicon solar cell substrate 1 by deposition. In this embodiment, the dielectric layer is formed on both the front and the back. 5. Herein, any one or any combination of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, silicon carbide, amorphous silicon, and polysilicon may be used to form the dielectric layer 5.

The dielectric layer 5 may have a single-layer structure or a multi-layer structure, such as a three-layer or three-layer structure. As an achievable way, the dielectric layer of the multilayer structure can be, but is not limited to, silicon oxide layer/silicon oxynitride layer/silicon nitride layer, silicon oxide layer/aluminum oxide layer/silicon nitride layer, aluminum oxide layer/nitrogen A laminated structure of aluminum oxide layer/silicon nitride layer, silicon oxide layer/silicon carbide layer/silicon nitride layer.

The dielectric layer is patterned according to a predetermined pattern, and a grid electrode electroplating area and an electroplating contact forming area are opened that expose the substrate of the crystalline silicon solar cell sheet.

As an achievable way, the gate line electrode electroplating area includes a fine gate electroplating area and a main grid electroplating area, the fine gate electroplating area includes a plurality of thin grid forming opening areas, and the main grid electroplating area includes a plurality of bus grid forming openings Area, the thin grid forming film opening area 2 and the main grid forming film opening area 3 intersect.

The dielectric layer 5 can be patterned by means of hydrofluoric acid, laser, or the like. For example, the dielectric layer 5 is processed by laser ablation to form the thin grid forming open film area 2, the main grid forming open film area 3, and the plating contact forming area 4 exposing the crystalline silicon solar cell substrate 1 described above.

It is used for electroplating to form the thin grid in the thin grid forming open film area 2, and the number of the fine grid forming open film area 2 can be 100-200.

It is used to form the main grid by electroplating in the main grid forming opening area 3, and the number of the main grid forming opening area 3 can be 3-30.

The thin grid is used to collect the current generated by the solar cell. The main grid is used to collect the current collected by the fine grid and to interconnect the cells.

The width of the area to be plated between the fine grid forming open film area 2 and the main grid forming open film area 3 is adjusted by changing the size of the laser spot, the laser power, the number of laser ablation times, or the interval of the laser pulse. For example, the open film area 3 of the main grid forming requires a wider gap, usually between 300 microns and 1 mm, which requires higher laser power, larger laser spot size, multiple laser ablation and slower use The processing speed. The shape of the thin grid forming film opening region 2 may be a strip pattern with a uniform width, and the shape of the bus grid forming film opening region 3 may be a strip pattern with a uniform width or may be an irregular pattern with different widths.

As a preferred method, the thin gate forming opening area 2 and the main grid forming opening area 3 intersect in a vertical manner, so that the formed thin gate and the main grid are perpendicular to each other. Of course, it is also possible to intersect in a non-perpendicular way.

S12: Sintering to form electroplated contacts in the electroplated contact forming area of the battery precursor.

The following two methods can be used to form electroplated contacts:

The first type: printing electrode paste in the electroplating contact forming area 4, as one of the possible ways, the electrode paste can be silver paste, and the electrode paste can be sintered to form electroplated contacts, of course, the electrode paste can also be sintered by laser Material to form electrode contacts, in this case, laser sintering can be understood as a way to achieve sintering; or,

The second type: Laying metal powder or alloy powder in the electroplating contact formation area 4, and forming electroplating contacts by laser sintering.

The shape of the electroplating contact forming area 4 includes, but is not limited to, a bar shape, a circle, a square, a character shape, or any irregular pattern. The size of the electroplating contact forming area 4 does not need to be large, so as to facilitate the connection with the negative electrode of the power supply.

As a preferred way, the electroplating contact formation area 4 is close to the edge of the crystalline silicon solar cell substrate, so as not to affect the appearance of the crystalline silicon solar cell. As another achievable way, the electroplating contact formation area 4 can also be formed in the main grid forming opening film area 3.

After sintering to form an electroplated contact, the electroplated contact is in ohmic contact with the crystalline silicon solar cell substrate 1 so that there is no need to prepare an electroplating seed layer during electroplating, which simplifies the process flow and solves the problem that the cell cannot be electroplated because the cell is not conductive .

S13: Electroplating the battery precursor formed with the electroplating contacts to form a metal electrode layer in the gate electrode electroplating area, and the electroplating contacts are electrically connected to the negative electrode of the electroplating equipment during electroplating.

Generally, before the metal electrode layer 6 is formed by electroplating, the surface of the patterned crystalline silicon solar cell substrate 1 needs to be cleaned. Generally, a fluorine-containing solution with a certain mass concentration can be used to clean the surface of the crystalline silicon solar cell substrate 1. The cleaning time ranges from a few seconds to a few minutes, and the length of the cleaning time depends on the concentration of the cleaning solution. In an embodiment, the crystalline silicon solar cell substrate 1 is cleaned with a hydrofluoric acid solution, the mass concentration of the hydrofluoric acid solution used can be 0.5%-10%, and the cleaning time can be 5 to 300 seconds.

Put the cleaned crystalline silicon solar cell substrate 1 into the electroplating tank as the electroplating equipment, connect the electroplating contact to the negative electrode of the electroplating tank, and start forming the film opening area in each fine grid of the crystalline silicon solar cell substrate 1 after power on A metal electrode layer 6 is formed inside 2 and in each main grid forming opening area 3.

As one of the achievable ways, electroplating contacts are formed on the dielectric layers on the front and back sides, and the electroplating contacts on the front and back sides are connected to the same negative electrode, so that the front side of the crystalline silicon solar cell substrate 1 is A metal electrode layer is formed at the same time as the back side to improve plating efficiency.

As another achievable way, electroplating contacts are formed on both the front and back dielectric layers, and the electroplating contacts on the front and back are connected to different negative electrodes. The current magnitude of each negative electrode can be individually controlled to control the metal electrode layer 6 The deposition speed and thickness to improve the quality of electroplating.

As yet another achievable manner, electroplated contacts are formed on both the front and back dielectric layers 5, and the electroplated contacts on the front and back are alternately connected to the same negative electrode. That is, one of the front and back electroplating contacts is connected to the negative electrode. After a certain period of electroplating, the negative electrode is connected to the other electroplating contact, and after a certain period of electroplating, it is connected to the connection in the previous electroplating period. The electroplated contacts on the front and back are alternately connected in this way until the end of electroplating. For example, but not limited to, during electroplating, first connect the front electroplating contact to the negative electrode of the electroplating tank, and deposit the metal electrode layer 6 on both sides of the crystalline silicon solar cell substrate 1 at the same time. Since only the front electroplating contact is connected to the negative electrode, both sides The deposition rate is inconsistent. It is necessary to remove the negative electrode from the electroplated contact on the front side after a period of electroplating, and switch to the electroplated contact on the back side, and increase the deposition rate with the aid of current. At this time, the negative electrode is not connected. The deposition rate on one side is lower than the deposition rate on the side where the negative electrode is connected. After a period of deposition, the negative electrode can be removed from the electroplated contact on the back and switched to the electroplated contact on the front, and so on. , Until the end of electroplating.

You can alternately connect the negative electrode of the power supply to the electroplated contacts on the front and back when depositing each layer of metal, or you can not swap when depositing the first thinner metal layer, and alternate when depositing the second thicker metal layer Connect the front and back of the battery, and deposit through alternate connection method to ensure the thickness and quality of the metal electrode layer on the front and back of the final battery.

The metal electrode layer 6 generally includes a stack of two, three or more layers of metal, and the thickness of the bottom metal layer is generally less than 3 microns. One type of metal is deposited in each electroplating tank. After each metal is deposited, the crystalline silicon solar cell substrate 1 needs to be cleaned, and then enter the next electroplating tank to deposit another metal layer. The cleaning here is generally done by deionized water. In some cases, the metal electrode layer 6 may also have a single-layer structure.

Wherein, the metal electrode layer 6 includes Ni layer/Ag layer, Co layer/Ag layer, Ni layer/Cu layer, Co layer/Cu layer, Ni layer/Cu layer/Sn layer, Co layer/Cu layer/Sn layer, Ni Any one of layer/Cu layer/Ag layer and Co layer/Cu layer/Ag layer electrode.

Further, the temperature of the plating solution during electroplating is 20-100°C. Using a temperature in this range can ensure that the electroplating solution has better electrical conductivity, and improve the dispersion ability and deposition reaction speed of the electroplating solution.

Further, it also includes after electroplating, annealing the crystalline silicon solar cell substrate on which the metal electrode layer is formed, so that the metal electrode layer and the crystalline silicon solar cell substrate form an ohmic contact to Strengthen the bonding force between the metal electrode layer and the silicon of the crystalline silicon solar cell substrate.

For the case where the bottom plating metal is nickel, low-resistance nickel silicide (NiSi) is formed after annealing; for the case where the bottom plating metal is cobalt, low-resistance cobalt silicide (CoSi ₂ ) is formed after annealing.

Among them, the temperature of the annealing treatment is 200°C to 900°C, and the annealing treatment time can range from a few seconds to a few minutes, depending on the temperature of the annealing treatment and the requirements of the process. In one embodiment, the underlying electroplating metal is nickel, the annealing temperature is 370°C, and the annealing time is 3 minutes. In another embodiment where the underlying electroplating metal is nickel, the annealing temperature is 500°C, and the annealing time is 30s. The ohmic contact layer can be formed under different annealing treatment temperatures and annealing times to achieve good ohmic contact.

The above annealing treatment can be divided into one annealing treatment and two annealing treatments, and during the two annealing treatments, the annealing temperature of the latter one is higher than the annealing temperature of the previous one. In one embodiment, a two-step annealing process is used to form a low-resistance nickel silicide. The first annealing temperature is 260°C to 310°C for 30 seconds, and the second annealing temperature is 400°C to 500°C for 30 seconds. . A two-step annealing process is used to form cobalt silicide. The first annealing process temperature is 400°C to 550°C, and the second annealing process temperature is 700°C to 850°C. The two-step annealing treatment can effectively inhibit ion diffusion and reduce damage to the crystalline silicon solar cell substrate. The silicide film has low resistivity and uniform properties, and can form a smooth morphology between the metal silicide and the crystalline silicon solar cell substrate.

In summary, the electroplated contacts formed by sintering are in ohmic contact with the substrate of the crystalline silicon solar cell, which eliminates the need to prepare an electroplating seed layer during electroplating, simplifies the process flow, and solves the problem of incapability of electroplating due to non-conductive cells.

Example two

At least referring to FIG. 4, an embodiment of the present invention also provides a crystalline silicon solar cell prepared by using the above-mentioned method embodiment 1, including a crystalline silicon solar cell substrate 1, and the front and/or back of the crystalline silicon solar cell substrate 1 are formed with Dielectric layer 5; The dielectric layer 5 is provided with a grid electrode plating area and a plating contact formation area exposing the substrate of the crystalline silicon solar cell. The grid electrode plating area is deposited with a metal electrode layer 6, a metal electrode layer 6 and The substrate of the crystalline silicon solar cell sheet 1 is in ohmic contact, and the electroplated contact forming area is sintered to form electroplated contacts.

For the preparation method and effect of the crystalline silicon solar cell, refer to the first embodiment of the above method, which will not be repeated here.

Example three

As shown in Figures 5-7, the present invention provides another method for manufacturing a crystalline silicon solar cell. The cell precursor includes the crystalline silicon solar cell substrate and the substrate formed on the crystalline silicon solar cell substrate. The dielectric layer on the back, that is, the crystalline silicon solar cell is a back contact solar cell, and the method includes the following steps:

S21: Provide a battery precursor; the battery precursor includes a crystalline silicon solar cell substrate 1, a back doped layer formed on the back of the crystalline silicon solar cell substrate 1, and a dielectric layer 5 formed on the back doped layer, the back doped The layer includes a p-type doped layer region 7 and an n-type doped layer region 8. The p-type doped layer region 7 and the n-type doped layer region 8 are arranged interdigitally or spaced apart, and the dielectric layer 5 is provided with The positive electrode plating region 9 of the p-type doped layer region 7 is exposed, and the negative electrode plating region 10 of the n-type doped layer region 8 is exposed.

The front side referred to in this article is the side facing the sun when the back-contact solar cell is in use, and the back side is the side facing away from the sun.

For example, the p-type doped layer region 7 and the n-type doped layer region 8 are arranged interdigitally at intervals. Of course, a non-interdigital structure may also be used, such as a stripe structure arranged at intervals. This article takes the interdigital structure as an example. The back doped layer can be formed by using a low pressure chemical vapor deposition method to deposit an intrinsic polysilicon layer on the back of the crystalline silicon solar cell substrate 1. The thickness of the intrinsic polysilicon layer may be 100 nm, 150 nm, etc., for example. Then screen printing the boron-containing doped paste is used for coating, and the material coating area of the boron-containing doped paste appears at intervals in preparation for the subsequent formation of an interdigitated structure. After coating the boron-containing doped slurry, the backside p-type doped layer region 7 is prepared by thermal diffusion at 900°C. In addition, during the preparation of the p-type doped layer region 7, a sufficient amount of oxygen is introduced into the furnace to at least oxidize the intrinsic polysilicon that is not coated with the boron-containing doped slurry at 900°C to form a relatively high temperature. Thick silicon oxide oxide layer. Then, a silicon oxide etching mask is used to partially open the film on the oxide layer, and the region to be prepared for the n-type doped layer region 8 is reserved for localization. Subsequently, the open film area is etched and cleaned, and then POCl ₃ thermal diffusion is performed to form the back n-type doped layer area 8. So far, the p-type doped layer region 7 and the n-type doped layer region 8 having an interdigitated structure are formed. Among them, in the process of forming the p-type doped layer region 7, there is no need to perform high-concentration boron doping on the p-type doped layer region 7 to form better contact with the subsequent aluminum-containing electrode, and there is no need High temperature advances. Thereby, the temperature of the process can be lowered, thereby avoiding the negative effects caused by the higher temperature thermal process.

After the back doped layer is prepared, a dielectric layer is formed on the back doped layer. Of course, a dielectric layer can also be formed on the front surface of the substrate.

The material of the dielectric layer 5 may be any one or any combination of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, silicon carbide, amorphous silicon, and polysilicon.

The dielectric layer 5 can be a single-layer structure or a multi-layer structure, such as a two-layer structure. 5-15nm aluminum oxide can be deposited on the back doped layer by ALD (Atomic Layer Deposition) as the back passivation. The deposition layer, for example, 5nm, 10nm or 15nm, etc., and then on the back passivation layer by PECVD (Plasma Enhanced Chemical Vapor Deposition; enhanced plasma chemical vapor deposition) deposition of 60-90nm thick silicon nitride, such as 70nm, 85nm Wait.

As an achievable way, the dielectric layer 5 of the multilayer structure can be, but is not limited to, silicon oxide layer/silicon oxynitride layer/silicon nitride layer, silicon oxide layer/aluminum oxide layer/silicon nitride layer, aluminum oxide layer/ A laminated structure of aluminum oxynitride layer/silicon nitride layer, silicon oxide layer/silicon carbide layer/silicon nitride layer.

After the preparation of the dielectric layer is completed, the dielectric layer 5 on the back of the back doped layer is patterned to form a positive electrode electroplating region 9 exposing the p-type doped layer region 7 and the n-type doped layer region is exposed 8 negative electrode plating area 10;

For example, by laser etching, the dielectric layer 5 on the back of the back doped layer is etched according to a predetermined pattern to form a positive electrode electroplating area 9 that exposes the p-type doped layer region 7 and exposes the n-type doped The negative electrode plating area 10 of the layer area 8.

As an achievable way, the negative electrode electroplating area 10 is located in the n-type doped layer area 8, the positive electrode electroplating area 9 is located in the p-type doped layer area 7, and the negative electrode electroplating area 10 is in the same shape as the positive electrode electroplating area 9 Interdigitated spaced. That is, the negative electrode electroplating area 10 includes a plurality of side-by-side negative electrode fine grid line opening regions 11 and a negative electrode connection line opening region 12 connected to the negative electrode fine grid line opening regions 11, and the positive electrode electroplating region 9 includes multiple side-by-side A positive electrode thin gate line opening area 13 and a positive electrode connection line opening area 14 connected to the positive electrode thin gate line opening area 13 are provided.

The widths of the negative electrode electroplating area 10 and the positive electrode electroplating area 9 are adjusted by changing the size of the laser spot, the laser power, the number of laser ablations, or the interval of the laser pulse.

S22: Sintering at least a part of at least one of the positive electrode electroplating zone 9 and the negative electrode electroplating zone 10 to form an electroplated contact, and the electroplated contact forms an ohmic contact with the back doped layer while firing.

For example, a part of the negative electrode electroplating zone 10 can be sintered to form a plating contact; it can also be sintered in a part of the positive electrode electroplating zone 9 to form a plating contact; it can also be in the negative electrode electroplating zone 10. A part of the area is sintered to form electroplated contacts, and a part of the area of the positive electrode electroplating area 9 is sintered to form electroplated contacts.

The following methods can be used to form electroplated contacts:

The electrode paste is printed on at least part of the positive electrode electroplating zone 9 and/or the negative electrode electroplating zone 10. As one of the possible implementations, the electrode paste can be silver paste, and the electrode paste is sintered to form electroplated contacts. Electroplating contacts can be formed by laser sintering electrode paste; or,

At least part of the positive electrode electroplating zone 9 and/or the negative electrode electroplating zone 10 is laid with metal powder or alloy powder, and electroplated contacts are formed by laser sintering.

The shape of the electroplated contacts is strip, circle, square, polygon or character shape or any irregular figure. The size of the electroplating contact does not need to be large, so as to facilitate the connection with the negative electrode of the power supply.

S23: Electroplating the battery precursor formed with electroplating contacts to form a metal electrode layer 6 in the positive electrode electroplating area 9 and the negative electrode electroplating area 10, and the electroplating contacts are electrically connected to the negative electrode of the electroplating equipment during electroplating.

Generally, before the metal electrode layer 6 is formed by electroplating, the surface of the patterned crystalline silicon solar cell substrate 1 needs to be cleaned. Generally, a fluorine-containing solution with a certain mass concentration can be used to clean the surface of the crystalline silicon solar cell substrate 1. The cleaning time ranges from a few seconds to a few minutes, and the length of the cleaning time depends on the concentration of the cleaning solution. In one embodiment, the crystalline silicon solar cell substrate 1 is cleaned with a hydrofluoric acid solution. The mass concentration of the hydrofluoric acid solution used may be 0.5%-10%, and the cleaning time may be 5-300 seconds.

Put the cleaned crystalline silicon solar cell substrate 1 into the electroplating tank as the electroplating equipment, and connect the electroplating contact to the negative electrode of the electroplating tank. After power on, start in each negative electrode electroplating area 10 of the crystalline silicon solar cell substrate 1 And a metal electrode layer 6 is formed in each positive electrode electroplating area 9.

The temperature of the plating solution during electroplating is 20-100°C. For different plating metals, the temperature of the plating solution can be different. With other appropriate processes, such as current density, increasing the temperature of the electroplating solution can increase the upper limit of the cathode current density. The increase of the cathode current density will increase the cathode polarization, make the coating crystal smaller, and accelerate the deposition and reaction speed. However, the solution temperature is not as high as possible. Too high electroplating solution temperature will reduce the cathodic polarization and make the coating crystal coarser. As a preferred solution, the temperature of the electroplating solution is 25-80°C. Using a temperature in this range can ensure that the electroplating solution has good conductivity, improve the dispersion ability and deposition reaction speed of the electroplating solution, reduce pinholes, reduce the internal stress of the coating, and improve the uniformity of the coating.

After electroplating, the crystalline silicon solar cell substrate 1 on which the metal electrode layer 6 is formed is annealed to make the metal electrode layer 6 and the back doped layer form an ohmic contact. Specifically, an ohmic contact layer is formed between the metal electrode layer 6 and the corresponding p-type doped layer region 7 and the n-type doped layer region 8 to enhance the bonding force between the metal electrode layer 6 and the silicon of the back doped layer .

In summary, the manufacturing method of the crystalline silicon solar cell forms electroplating contacts, so that there is no need to prepare an electroplating seed layer during electroplating, which simplifies the process flow and solves the problem that the solar cell cannot be electroplated without a seed layer.

Example four

At least referring to FIG. 7, another crystalline silicon solar cell provided by this embodiment, namely a back contact solar cell, includes a crystalline silicon solar cell substrate 1, a back doped layer formed on the back of the crystalline silicon solar cell substrate 1 And the dielectric layer 5 formed on the back doped layer. The back doped layer includes a p-type doped layer region 7 and an n-type doped layer region 8. The p-type doped layer region 7 and the n-type doped layer region 8 are Interdigitally arranged or spaced apart, the dielectric layer 105 is provided with a positive electrode electroplating region exposing the p-type doped layer region 7 and a negative electrode electroplating region exposing the n-type doped layer region 8; at least in the positive At least part of one of the electrode electroplating area and the negative electrode electroplating area is sintered to form an electroplating contact, and the electroplating contact is in ohmic contact with the back doped layer; the positive electrode electroplating area and the negative electrode electroplating area are deposited with a metal electrode layer 6, metal The electrode layer 6 is in ohmic contact with the back doped layer.

For the preparation method and effect of the crystalline silicon solar cell, refer to the third embodiment of the above method, which will not be repeated here.

The above description is only a preferred embodiment of the application and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solution formed by the specific combination of the above technical features, and should also cover the above technical features or their technical solutions without departing from the inventive concept. Other technical solutions formed by any combination of equivalent features. For example, the above-mentioned features and the technical features disclosed in this application (but not limited to) with similar functions are mutually replaced to form a technical solution.

Claims

A method for manufacturing a crystalline silicon solar cell is characterized by comprising the following steps:

A battery precursor is provided; the battery precursor includes a crystalline silicon solar cell substrate, and a dielectric layer formed on the front and/or back of the crystalline silicon solar cell substrate; the dielectric layer is provided with exposed The gate electrode electroplating area and the electroplating contact forming area of the crystalline silicon solar cell substrate;

Sintering in the electroplating contact formation area of the battery precursor to form electroplating contacts;

Electroplating the battery precursor formed with the electroplating contacts to form a metal electrode layer in the gate electrode electroplating area, and the electroplating contacts are electrically connected with the negative electrode of the electroplating equipment during electroplating.
The method for manufacturing a crystalline silicon solar cell according to claim 1, wherein the gate electrode electroplating area includes a fine grid electroplating area and a main grid electroplating area, and the fine grid electroplating area includes a plurality of thin grid forming openings. Film area, the main grid electroplating area includes a plurality of main grid forming film opening areas, and the fine grid forming film opening area intersects the bus grid forming film opening area.
The method for manufacturing a crystalline silicon solar cell according to claim 1 or 2, wherein the electroplated contacts are formed on both the front and back dielectric layers;

During electroplating, the electroplating contacts on the front and back sides are connected to the same negative electrode;

or,

During electroplating, the electroplating contacts on the front and back sides are connected to different negative electrodes;

or,

During electroplating, one of the electroplated contacts on the front and back sides is connected to the negative electrode. After a certain period of electroplating, the negative electrode is connected to the other electroplated contact, and after electroplating for another predetermined time, then Switch to the electroplating contacts connected in the last electroplating period, and then alternately connect the electroplated contacts on the front and back until the end of electroplating.
The method for manufacturing a crystalline silicon solar cell according to claim 1, wherein the electroplating contact formation area is close to the edge of the crystalline silicon solar cell substrate.
The method for manufacturing a crystalline silicon solar cell according to claim 1, wherein the step of forming electroplated contacts by sintering in the electroplated contact forming area of the battery precursor comprises:

Printing electrode paste in the electroplating contact forming area, and sintering the electrode paste to form the electroplating contact;

or,

Laying metal powder or alloy powder on the electroplating contact forming area, and forming the electroplating contact by laser sintering.
The method of manufacturing a crystalline silicon solar cell according to claim 1, further comprising after electroplating,

Annealing is performed on the crystalline silicon solar cell substrate on which the metal electrode layer is formed, so that the metal electrode layer and the crystalline silicon solar cell substrate form an ohmic contact.
The method for manufacturing a crystalline silicon solar cell according to claim 1, wherein when the crystalline silicon solar cell is a back contact cell, the method comprises the following steps:

The battery precursor is provided; the battery precursor includes the crystalline silicon solar cell substrate, a back doped layer formed on the back of the crystalline silicon solar cell substrate, and a dielectric formed on the back doped layer Layer, the back doped layer includes a p-type doped layer region and an n-type doped layer region, the p-type doped layer region and the n-type doped layer region are arranged interdigitally or spaced apart, The dielectric layer is provided with a positive electrode electroplating area exposing the p-type doped layer area, and a negative electrode electroplating area exposing the n-type doped layer area;

Sintering at least part of at least one of the positive electrode electroplating area and the negative electrode electroplating area to form the electroplating contact, and making the electroplating contact form an ohmic contact with the back doped layer;

Electroplating the battery precursor formed with the electroplating contact to form the metal electrode layer in the positive electrode electroplating area and the negative electrode electroplating area, the electroplating contact and the electroplating equipment during electroplating The negative electrode is electrically connected.
7. The method of manufacturing a crystalline silicon solar cell according to claim 7, wherein the negative electrode electroplating area is located in the n-type doped layer area, and the positive electrode electroplating area is located in the p-type doped layer. In the region, and the negative electrode electroplating area and the positive electrode electroplating area are arranged interdigitally at intervals.
The method of manufacturing a crystalline silicon solar cell according to claim 7 or 8, wherein at least a part of at least one of the positive electrode electroplating area and the negative electrode electroplating area is sintered to form the electroplating Contacts, including:

Printing electrode paste at least in at least part of one of the positive electrode electroplating area and the negative electrode electroplating area, and sintering the electrode paste to form the electroplating contact;

or,

Laying metal powder or alloy powder on at least part of at least one of the positive electrode electroplating area and the negative electrode electroplating area, and forming the electroplated contact by laser sintering.
8. The method of manufacturing a crystalline silicon solar cell according to claim 7, further comprising after electroplating,

Annealing the substrate on which the metal electrode layer is formed is performed to make the metal electrode layer and the back doped layer form an ohmic contact.
The method for manufacturing a crystalline silicon solar cell according to claim 9, wherein the shape of the electroplated contact is a bar, a circle, a square, a polygon, or a character shape.
8. The method for manufacturing a crystalline silicon solar cell according to claim 7, wherein the negative electrode electroplating area and the positive electrode electroplating area are formed by laser etching.
The method for manufacturing a crystalline silicon solar cell according to claim 1 or 7, wherein the temperature of the electroplating solution during electroplating is 20-100°C.
The method for manufacturing a crystalline silicon solar cell according to claim 1 or 7, wherein the metal electrode layer comprises Ni layer/Ag layer, Co layer/Ag layer, Ni layer/Cu layer, Co layer/Cu layer , Ni layer/Cu layer/Sn layer, Co layer/Cu layer/Sn layer, Ni layer/Cu layer/Ag layer, and Co layer/Cu layer/Ag layer electrode.
The method for manufacturing a crystalline silicon solar cell according to claim 6 or 10, wherein the temperature of the annealing treatment is 200°C to 900°C.
The method for manufacturing a crystalline silicon solar cell according to claim 6 or 10, wherein the annealing treatment includes two annealings before and after, and the annealing temperature of the latter annealing is higher than the annealing temperature of the previous annealing.
A crystalline silicon solar cell characterized by being prepared by the method of any one of claims 1-16.