WO2024045597A1

WO2024045597A1 - Solar cell and preparation method therefor

Info

Publication number: WO2024045597A1
Application number: PCT/CN2023/084944
Authority: WO
Inventors: 王金; 余义
Original assignee: 通威太阳能（安徽）有限公司
Priority date: 2022-08-31
Filing date: 2023-03-30
Publication date: 2024-03-07
Also published as: CN115312625A

Abstract

The present application provides a solar cell and a preparation method therefor. The preparation method for the solar cell comprises: providing a solar cell substrate having transparent conductive films; sequentially forming a plurality of copper seed layers on each transparent conductive film by means of physical vapor deposition; and electroplating the outermost copper seed layers to form copper electrodes. The deposition power for forming the innermost copper seed layers is 0.2 kW-0.8 kW, and the deposition power for forming the innermost copper seed layers is less than the deposition power for forming other copper seed layers. In the present application, the plurality of copper seed layers are sequentially deposited on each transparent conductive film, and the deposition power of each copper seed layer is controlled; by means of low-power sputtering of the innermost copper seed layers, bombardment damage to the transparent conductive films and an amorphous silicon layer in the deposition process can be reduced, and a protection effect is achieved; and the copper seed layers can be quickly deposited by means of high-power deposition of the subsequent copper seed layers, so as to meet the mass production speed requirement.

Description

Solar cell and preparation method thereof

This application claims priority to the Chinese patent application filed with the China Patent Office on August 31, 2022, with the application number 2022110527932 and the invention name "Solar Cell and Preparation Method thereof", the entire content of which is incorporated into this application by reference.

Technical field

The present application relates to the field of semiconductor photoelectric conversion technology, and in particular to a solar cell and a preparation method thereof.

Background technique

At present, the non-silicon cost of heterojunction solar cells (Heterojunction with Intrinsic Thin Layer, HJT) is still higher than that of conventional PERC cells (Passivated Emitter and Rear Cell), and mass production needs to solve this problem as soon as possible.

Among non-silicon costs, the cost of silver paste accounts for about 50% of it. Reducing the amount of silver paste or replacing silver grid lines with other electrode materials will bring about huge cost reductions, thereby reaching the cost of heterojunction solar cells. The goal of PERC battery cost parity.

Currently, the main method to replace silver grid electrodes is to form copper electrodes by electroplating copper. Before electroplating to form a copper electrode, a copper layer needs to be added to the surface of the TCO (transparent conductive film) as a seed layer for subsequent Cu electroplating. Currently, PVD (Physical Vapor Deposition) is usually used to form a seed layer for electroplating Cu on the surface of TCO. However, after the copper seed layer is plated on the surface of the TCO through PVD, the efficiency of the heterojunction solar cell will be greatly lost.

Contents of the invention

This application was made in view of the above-mentioned issues, and one of its purposes is to provide a solar cell preparation method that can effectively reduce the impact of the PVD copper plating seed layer on the solar cell efficiency. Thereby improving the photoelectric conversion efficiency of solar cells.

In order to achieve the above objectives, the first aspect of the present application provides a method for preparing a solar cell, including the following steps:

Provide solar cell substrates with transparent conductive films;

sequentially forming a multilayer copper seed layer on the transparent conductive film by physical vapor deposition; and

Electroplating on the outermost copper seed layer forms a copper electrode;

The deposition power of the copper seed layer forming the innermost layer is 0.2KW to 0.8KW, and the deposition power of the copper seed layer forming the innermost layer is smaller than the deposition power of the copper seed layers forming other layers.

The above preparation method can reduce damage to the transparent conductive film and amorphous silicon layer through low-power sputtering of the innermost copper seed layer, and play a protective role; and then cooperate with subsequent high-power deposition to quickly deposit the copper seed layer. Through the above method, the bombardment damage to the amorphous silicon layer and transparent conductive film caused by physical vapor deposition of copper seed layer can be reduced, thereby achieving the purpose of protecting the amorphous silicon layer and transparent conductive film, and solving the heterojunction caused by bombardment. The problem of solar cell efficiency loss; at the same time, the deposition speed of the copper seed layer can be guaranteed to meet the efficiency requirements of mass production.

In any embodiment, the deposition power used to form each of the copper seed layers gradually increases in a direction from the innermost copper seed layer to the outermost copper seed layer. In this way, the gradient film design that allows the copper seed layer to form a stack can not only protect the amorphous silicon layer and the transparent conductive film from being bombarded during the physical vapor deposition coating process, but also better ensure that Deposition rate of copper seed layer.

In any embodiment, in the direction from the innermost copper seed layer to the outermost copper seed layer, the deposition power used to form the outer copper seed layer is the deposition power used to form the adjacent inner copper seed layer. 2 times to 5 times. In this way, while ensuring that the amorphous silicon layer and transparent conductive film will not be bombarded during the physical vapor deposition coating process, the deposition speed of the copper seed layer can be further increased.

In any embodiment, a first copper seed layer, a second copper seed layer and a third copper seed layer are sequentially formed on the transparent conductive film by physical vapor deposition.

In any embodiment, the deposition power to form the first copper seed layer is 0.2KW～0.8KW, the deposition power to form the second copper seed layer is 1.0KW～3.5KW, and the deposition power to form the third copper seed is The deposition power of the layer is 3.6KW~7.5KW.

In any embodiment, the thickness of the first copper seed layer is greater than 5 nm and less than 150 nm. In this way, it can ensure better protection for the amorphous silicon layer and the transparent conductive film, and better avoid bombardment damage to the amorphous silicon layer and the transparent conductive film caused by the subsequent copper seed layer plating process.

In any embodiment, the transmission rate of the substrate forming the second copper seed layer is greater than or equal to the transmission rate of the substrate forming the first copper seed layer, and the transmission rate of the substrate forming the third copper seed layer is greater than or equal to The substrate transmission rate of the second copper seed layer is formed. In this way, the bombardment damage caused to the amorphous silicon layer and transparent conductive film during the coating process can be better reduced, and the deposition speed can be appropriately increased.

In any embodiment, the total thickness of each copper seed layer is 100 nm to 200 nm.

In any embodiment, after electroplating the outermost copper seed layer to form a copper electrode, the preparation method further includes removing the copper seeds in the area of the transparent conductive film other than the area where the copper electrode is formed. layer steps.

In any embodiment, the preparation method of the solar cell substrate includes the following steps:

forming an amorphous silicon layer on a single crystal silicon substrate; and

The transparent conductive film is formed on the amorphous silicon layer.

In any embodiment, before forming the amorphous silicon layer on the single crystal silicon substrate, the method for preparing the solar cell substrate further includes performing a texturing process on the single crystal silicon substrate to form the single crystal silicon layer on the single crystal silicon substrate. The step of forming a textured light-trapping structure on the surface of a silicon substrate.

In any embodiment, forming an amorphous silicon layer on a single crystal silicon substrate includes the following steps:

forming an intrinsic amorphous silicon layer on the single crystal silicon substrate; and

A doped amorphous silicon layer is formed on the intrinsic amorphous silicon layer.

In any embodiment, the amorphous silicon layer is formed on the single crystal silicon substrate by a plasma enhanced chemical vapor deposition method.

In any embodiment, the transparent conductive film is formed on the amorphous silicon layer by a physical vapor deposition method.

A second aspect of the present application provides a solar cell, which is prepared by the solar cell preparation method of the first aspect of the present application. In this way, the solar cell has high photoelectric conversion efficiency.

In any embodiment, the solar cell includes:

Single crystal silicon substrate;

An amorphous silicon layer is provided on at least one surface of the single crystal silicon substrate;

A transparent conductive film disposed on the surface of the amorphous silicon layer facing away from the single crystal silicon substrate;

Multiple layers of copper seed layers are sequentially stacked on the surface of the transparent conductive film facing away from the amorphous silicon layer; and

A copper electrode is provided on the surface of the outermost copper seed layer on the side facing away from the transparent conductive film.

In any embodiment, the amorphous silicon layer includes an intrinsic amorphous silicon layer and a doped amorphous silicon layer, and the intrinsic amorphous silicon layer is provided on the surface of the single crystal silicon substrate, so The doped amorphous silicon layer is disposed on the surface of the intrinsic amorphous silicon layer facing away from the single crystal silicon substrate.

The preparation method of this application is to design a stacked film layer for the copper seed layer on the transparent conductive film, and sequentially deposit it on the transparent conductive film through physical vapor deposition to form a multi-layer copper seed layer, and will form the innermost copper seed layer. The deposition power of the layer is set to 0.2KW~0.8KW, and the deposition power to form the innermost copper seed layer is smaller than the deposition power to form other copper seed layers; through low-power sputtering of the innermost copper seed layer, it can Reduce bombardment to transparent conductive films and amorphous silicon layers Damage, play a protective role; combined with subsequent high-power deposition to quickly deposit the copper seed layer. The method of the present application can be used to solve the problem of heterojunction solar cell efficiency loss caused by bombardment damage during physical vapor deposition of a copper seed layer; at the same time, the deposition speed of the copper seed layer can be guaranteed to meet the efficiency requirements of mass production.

Description of drawings

To better describe and illustrate embodiments and/or examples of the present application, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the drawings should not be construed as limiting the scope of any of the disclosed inventions, the embodiments and/or examples presently described, and the best modes currently understood of these inventions.

FIG. 1 is a schematic structural diagram of a solar cell after forming a copper seed layer according to a preparation method according to an embodiment of the present application.

Explanation of reference symbols:
10. Heterojunction solar cell; 11. Single crystal silicon substrate; 12. Intrinsic amorphous silicon layer; 13a, n-type doped amorphous silicon layer; 13b, p-type doped amorphous silicon layer; 14. Transparent Conductive film; 15a, first copper seed layer; 15b, second copper seed layer; 15c, third copper seed layer.

Detailed ways

In order to make the above objects, features and advantages of the present application more obvious and understandable, the specific implementation modes of the present application are described in detail. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described here. Those skilled in the art can make similar improvements without violating the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. As mentioned herein in the description of this application The terminology used is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased in the market or prepared by existing methods.

In addition, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number or order of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

When describing positional relationships, unless otherwise specified, when an element such as a layer, film or substrate is referred to as being "on" another layer, it can be directly on the other layer or intervening layers may also be present. Furthermore, when a layer is referred to as being "under" another layer, it can be directly underneath, or one or more intervening layers may also be present. It will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

Unless mentioned to the contrary, terms in the singular may include the plural and shall not be construed as being one in number.

The traditional method of plating a copper seed layer on the surface of a transparent conductive film (TCO) through physical vapor deposition will cause a large loss in the efficiency of the heterojunction solar cell 10 . Research has found that the main reason for the above problems is that a larger deposition power (generally 3.5KW) is required when physically vapor depositing the copper seed layer, and a larger deposition power will affect the performance of the heterojunction solar cell 10 The amorphous silicon layer and the transparent conductive film 14 cause bombardment damage, thereby causing a large loss in the efficiency of the heterojunction solar cell 10 .

In order to solve the above problems, some embodiments of the present application provide a method for preparing a heterojunction solar cell 10. The structure of the heterojunction solar cell 10 is as shown in Figure 1 (the copper electrode is not shown).

The preparation method of the heterojunction solar cell 10 includes the following steps S100 to S300.

Step S100: Provide a heterojunction solar cell substrate with a transparent conductive film 14.

Wherein, the heterojunction solar cell substrate includes a single crystal silicon substrate 11, and the front and back sides of the single crystal silicon substrate 11 (that is, the upper surface and the lower surface of the single crystal silicon substrate 11 in Figure 1 respectively) are respectively An intrinsic amorphous silicon layer 12 is provided, an n-type doped amorphous silicon layer 13a is provided on the front intrinsic amorphous silicon layer 12, and a p-type doped amorphous silicon layer 13a is provided on the back intrinsic amorphous silicon layer 12. In the mixed amorphous silicon layer 13b, transparent conductive films 14 are respectively provided on the n-type doped amorphous silicon layer 13a and the p-type doped amorphous silicon layer 13b.

Step S200: sequentially form multiple copper seed layers (15a, 15b, 15c in Figure 1) on the transparent conductive film 14 of the heterojunction solar cell 10 through physical vapor deposition. Among them, the deposition power of the copper seed layer forming the innermost layer (that is, the copper seed layer closest to the transparent conductive film 14) is 0.2KW to 0.8KW, and the deposition power of the copper seed layer forming the innermost layer is smaller than that of the copper seed layer forming other layers. deposition power at the time.

Step S300: Electroplating to form a copper electrode on the outermost copper seed layer on the front and/or back side.

In this application, the copper seed layer on the transparent conductive film 14 is designed with a stacked film layer, and a multi-layer copper seed layer is sequentially deposited on the transparent conductive film 14 through the physical vapor deposition method to form the innermost copper seed layer. The deposition power is set to 0.2KW ~ 0.8KW, and the deposition power to form the innermost copper seed layer is smaller than the deposition power to form other copper seed layers; in this way, the copper seed layer can be deposited at a lower cost than conventional physical vapor deposition. The innermost copper seed layer is deposited under deposition power. Through the low-power sputtering of the innermost copper seed layer, the damage to the transparent conductive film 14 and the amorphous silicon layer can be reduced and play a protective role; combined with the subsequent high-power deposition, the copper seed layer can be quickly deposited, thereby achieving For mass production purposes.

By adopting the above method, the bombardment damage to the amorphous silicon layer and the transparent conductive film 14 caused by physical vapor deposition of the copper seed layer can be reduced, thereby achieving the purpose of protecting the amorphous silicon layer and the transparent conductive film 14 and solving the problem caused by bombardment. The problem of efficiency loss of the heterojunction solar cell 10 is eliminated; at the same time, the deposition speed of the copper seed layer can be guaranteed to meet the efficiency requirements of mass production.

It can be understood that the deposition power of the copper seed layer forming the innermost layer can be, but is not limited to, 0.2KW, 0.3KW, 0.4KW, 0.5KW, 0.6KW, 0.7KW, 0.8KW and other specific values.

In some embodiments, the deposition power used to form each copper seed layer gradually increases in a direction from the innermost copper seed layer to the outermost copper seed layer. That is, from the innermost copper seed layer outward, the deposition power to form each copper seed layer gradually increases. Such an arrangement allows the copper seed layer to form a laminated gradient film design, which can not only well protect the amorphous silicon layer and the transparent conductive film 14 from being bombarded during the physical vapor deposition coating process, but also better to ensure the deposition speed of the copper seed layer.

Further, in some embodiments, in the direction from the innermost copper seed layer to the outermost copper seed layer, the deposition power to form the outer copper seed layer is to form the adjacent inner copper seed layer. 2 to 5 times the deposition power.

After the copper electrode is formed on the outermost copper seed layer by electroplating, the copper seed layer in the area on the transparent conductive film 14 except where the copper electrode is formed can be removed by etching or other methods.

In one specific example, multiple copper seed layers are sequentially formed on the transparent conductive film 14 of the heterojunction solar cell 10, including the following steps S201 to S203:

Step S201: First, form the first copper seed layer 15a on the transparent conductive film 14 by physical vapor deposition.

Specifically, the deposition power when forming the first copper seed layer 15a by physical vapor deposition is 0.2KW to 0.8KW, preferably 0.8KW. Forming the first copper seed layer 15a under this deposition power condition can effectively reduce bombardment damage to the amorphous silicon layer and the transparent conductive film 14 caused by physical vapor deposition plating to form the first copper seed layer 15a.

Further, the thickness of the first copper seed layer 15a is greater than 5 nm and less than 150 nm. Such an arrangement can ensure better protection for the amorphous silicon layer and the transparent conductive film 14, and better avoid bombardment damage to the amorphous silicon layer and the transparent conductive film 14 caused by the subsequent copper seed layer plating process. If the thickness of the first copper seed layer 15a is too thin, it cannot achieve a good protective effect; if The thickness of the first copper seed layer 15a is too thick. Since the deposition power to form the first copper seed layer 15a is low, the overall deposition speed of the copper seed layer will be significantly reduced, which cannot well meet mass production requirements. The thickness of the first copper seed layer 15a can be reasonably set within the above range according to machine capacity requirements and product thickness requirements, and the thickness can be controlled by adjusting the substrate transmission speed and the number of coating turns during physical vapor deposition coating.

In one specific example, the belt speed (i.e., the substrate transmission speed) when depositing the first copper seed layer 15a is 0.9m/min. Ar gas is used as a protective gas during the deposition process. The flow rate of the Ar gas is 1000 sccm. The cavity of the coating equipment is not heated, and the deposition rate is 5 mg/cycle.

Step S202: Form a second copper seed layer 15b on the first copper seed layer 15a by physical vapor deposition.

Specifically, the deposition power when forming the second copper seed layer 15b is 1.0KW˜3.5KW, preferably 1.5KW. The second copper seed layer 15b is formed under this deposition power condition. The deposition power is higher than the deposition rate when forming the first copper seed layer 15a, but is still lower than the deposition rate of the traditional method. In this way, the bombardment damage caused by the coating process to the amorphous silicon layer and the transparent conductive film 14 can be better reduced, and the deposition speed can be appropriately increased.

In one specific example, the belt speed when depositing the second copper seed layer 15b is 0.9m/min. Ar gas is used as a protective gas during the deposition process. The flow rate of the Ar gas is 1000 sccm. During the deposition, the chamber of the coating equipment is not Turn on heating and the deposition rate is 15mg/circle.

Step S203: Form a third copper seed layer 15c on the second copper seed layer 15b by physical vapor deposition.

Specifically, the deposition power when forming the third copper seed layer 15c is 3.6KW˜7.5KW, preferably 3.6KW. The third copper seed layer 15c is formed under this deposition power condition. The deposition power is greater than the deposition rate when forming the second copper seed layer 15b, and is comparable to the deposition rate of the traditional method. In this way, the deposition speed can be significantly increased, and the deposition speed of the entire copper seed layer can better meet the mass production requirements. Due to the protection function of the first copper seed layer 15a and the second copper seed layer 15b, Therefore, using a larger deposition power when forming the third copper seed layer 15c will not cause damage to the amorphous silicon layer and the transparent conductive film 14.

In one specific example, the belt speed when depositing the third copper seed layer 15c is 0.9m/min. Ar gas is used as a protective gas during the deposition process. The flow rate of the Ar gas is 1000 sccm. During the deposition, the chamber of the coating equipment is not Turn on heating and the deposition rate is 30mg/circle.

In order to avoid jamming when the substrate is transferred during the plating process, in this application, it is preferred to make the transfer rate of the substrate forming the second copper seed layer 15b greater than or equal to the transfer rate of the substrate forming the first copper seed layer 15a; forming the third copper The substrate transmission rate of the seed layer 15c is greater than or equal to the substrate transmission rate of the second copper seed layer 15b. In this way, jamming can be effectively avoided.

It should be noted that the number of copper seed layers is not limited to the above-mentioned three-layer structure, and more stacked copper seed layers can also be formed on the third copper seed layer 15c in a similar manner as described above. Of course, in some cases it is also possible to use only a copper seed layer with a two-layer structure. The specific number of layers and the number of deposition turns for each layer can be designed based on the actual PVD machine chamber conditions and the thickness requirements of each copper seed layer for PVD plating.

In this application, in order to ensure good protection for the amorphous silicon layer and the transparent conductive film 14, the thickness of the first copper seed layer 15a needs to be greater than 5 nm, while the thickness of other copper seed layers can be adjusted according to actual needs. , but the total thickness of the copper seed layer should be controlled within the range of 100nm ~ 200nm.

It should be noted that the deposition power when forming the first copper seed layer 15a can be, but is not limited to, 0.2KW, 0.3KW, 0.4KW, 0.5KW, 0.6KW, 0.7KW, 0.8KW and other specific values; forming the second copper The deposition power of the seed layer 15b can be, but is not limited to, 1.0KW, 1.2KW, 1.5KW, 1.8KW, 2.0KW, 2.2KW, 2.5KW, 2.8KW, 3.0KW, 3.2KW, 3.5KW and other specific values; forming The deposition power of the third copper seed layer 15c can be but is not limited to 3.6KW, 4.0KW, 4.5KW, 5.0KW, 5.5KW, 6.0KW, 6.5KW, 7.0KW, 7.5KW and other specific values; the thickness of the first copper seed layer 15a can be but is not limited to 6nm, 20nm, 40nm, 80nm, 100nm, 120nm, 140nm and other specific values; the total thickness of the copper seed layer can be but not limited to Limited to specific values such as 100nm, 120nm, 140nm, 160nm, 180nm, 200nm, etc.

Some embodiments of the present application also provide a heterojunction solar cell 10. The structural diagram of the heterojunction solar cell 10 is shown in Figure 1 (the copper electrode is not shown).

As can be seen from Figure 1, the heterojunction solar cell 10 includes an n-type single crystal silicon substrate 11, on the front (ie, the upper surface in Figure 1) and the back (ie, the lower surface in Figure 1) of the single crystal silicon substrate 11. A layer of intrinsic amorphous silicon layer 12 is provided respectively; an n-type doped amorphous silicon layer 13a is provided on the intrinsic amorphous silicon layer 12 on the front; and a p-type doped amorphous silicon layer 13a is provided on the intrinsic amorphous silicon layer 12 on the back. Doped amorphous silicon layer 13b; a layer of transparent conductive film 14 is respectively provided on the n-type doped amorphous silicon layer 13a and the p-type doped amorphous silicon layer 13b; a third layer of transparent conductive film 14 is provided on the front transparent conductive film 14 in turn. A copper seed layer 15a, a second copper seed layer 15b and a third copper seed layer 15c; similarly, the first copper seed layer 15a, the second copper seed layer 15b and the third copper seed layer 15c are also arranged on the transparent conductive film 14 on the back side. Three copper seed layers 15c.

The first copper seed layer 15a, the second copper seed layer 15b and the third copper seed layer 15c on each transparent conductive film 14 together form a copper seed layer, forming a copper seed layer with a stacked structure. The thickness of the first copper seed layer 15a is greater than 5 nm and less than 150 nm, and the total thickness of each copper seed layer on each transparent conductive film 14 is 100 nm to 200 nm.

It can be understood that the number of copper seed layers in the copper seed layer of the stacked structure is not limited to the above-mentioned three-layer structure, and may also be a two-layer structure or a structure greater than three layers.

The preparation method of the heterojunction solar cell 10 is as follows: first, an intrinsic amorphous silicon layer 12 is formed on the single crystal silicon substrate 11; and then a doped amorphous silicon layer (specifically, It includes an n-type doped amorphous silicon layer 13a and a p-type doped amorphous silicon layer 13b); a transparent conductive film 14 is formed on the doped amorphous silicon layer; and then a copper electrode is formed on the transparent conductive film 14.

Among them, when forming the copper electrode, first physical vapor deposition is performed on the transparent conductive film 14 according to the First, multiple layers of copper seed layers are formed; and then electroplating is performed on the outermost copper seed layer to form copper electrodes. Furthermore, the deposition power of the copper seed layer forming the innermost layer is controlled to 0.2KW to 0.8KW, and the deposition power of the copper seed layer forming the innermost layer is smaller than the deposition power of the copper seed layers forming other layers.

In this way, the bombardment damage caused to the amorphous silicon layer and the transparent conductive film 14 of the heterojunction solar cell 10 during the formation of the copper seed layer by physical vapor deposition can be effectively reduced, thereby effectively reducing the heterogeneous damage after the copper electrode is formed. Junction solar cell 10 efficiency loss.

Specifically, before forming the intrinsic amorphous silicon layer 12 on the monocrystalline silicon substrate 11 , the monocrystalline silicon substrate 11 needs to be textured in a texturing cleaning machine to form a texture on the surface of the monocrystalline silicon substrate 11 . A pyramid-shaped suede light trapping structure is formed on the substrate to reduce the reflectivity of the single crystal silicon substrate 11 and improve light utilization; intrinsic amorphous can be formed through PECVD (Plasma Enhanced Chemical Vapor Deposition, plasma enhanced chemical vapor deposition) The silicon layer 12, the n-type doped amorphous silicon layer 13a and the p-type doped amorphous silicon layer 13b are formed by a physical vapor deposition method. The transparent conductive film 14 is usually an ITO (indium tin oxide) film.

The present application will be further described below with reference to specific examples and comparative examples, but they should not be understood as limiting the protection scope of the present application.

Example 1:

A method for preparing a heterojunction solar cell 10, including the following steps:

Texturing is performed on the n-type single crystal silicon substrate 11 in a texturing cleaning machine; and then an intrinsic amorphous silicon layer 12 is deposited on the front and back sides of the textured single crystal silicon substrate 11 by PECVD; Then, an n-type doped amorphous silicon layer 13a is deposited on the intrinsic amorphous silicon layer 12 on the front side by PECVD, and a p-type doped amorphous silicon layer 13b is deposited on the intrinsic amorphous silicon layer 12 on the back side; and then A transparent conductive film 14 is deposited on the n-type doped amorphous silicon layer 13a and the p-type doped amorphous silicon layer 13b respectively through physical vapor deposition; and then copper electrodes are formed on the front and back transparent conductive films 14 respectively.

Among them, the preparation method of copper electrode is:

The first copper seed layer 15a is deposited on the transparent conductive film 14 using physical vapor deposition. The deposition power of the first copper seed layer 15a is 0.8KW; the substrate transmission rate during the deposition process is 0.9m/min; an Ar atmosphere is used during the deposition process, and the Ar gas flow rate is 1000 sccm; the cavity of the coating equipment is not heated during the deposition process Production, the deposition rate is 5mg/turn, and 6 turns are deposited according to the above process conditions;

Physical vapor deposition is used to deposit the second copper seed layer 15b on the first copper seed layer 15a. The deposition power of the second copper seed layer 15b is 1.6KW; the substrate transmission rate during the deposition process is 0.9m/min; an Ar atmosphere is used during the deposition process, and the Ar gas flow rate is 1000 sccm; the cavity of the coating equipment is not heated during the deposition process Production, the deposition rate is 15mg/circle, and 2 cycles are deposited according to the above process conditions;

Physical vapor deposition is used to deposit the third copper seed layer 15c on the second copper seed layer 15b. The deposition power of the third copper seed layer 15c is 3.6KW; the substrate transmission rate during the deposition process is 0.9m/min; an Ar atmosphere is used during the deposition process, and the Ar gas flow rate is 1000 sccm; the cavity of the coating equipment is not heated during the deposition process Production, the deposition rate is 30mg/circle, and one cycle is deposited according to the above process conditions.

Copper is electroplated on the third copper seed layer 15c to form a copper electrode, thereby manufacturing the heterojunction solar cell 10.

The efficiency (Eta), open circuit voltage (Voc), short circuit current (Isc) and fill factor (FF) of the prepared heterojunction solar cell 10 were tested. Specifically, a halm testing machine is used to perform an IV test to obtain the above electrical performance data of the heterojunction solar cell 10 . The specific test results are shown in Table 1.

Comparative example 1:

A method for preparing a heterojunction solar cell 10. The main steps of the preparation method are the same as those in Embodiment 1. The only difference lies in the preparation method of the copper electrode.

In this comparative example, a process is performed on the transparent conductive film 14 by a physical vapor deposition method. A copper seed layer is deposited under process conditions, and then copper is electroplated on the copper seed layer to form a copper electrode. Among them, the process conditions for depositing the copper seed layer are: the deposition power is 3.5KW; the substrate transmission rate during the deposition process is 0.9m/min; the Ar atmosphere is used during the deposition process, and the Ar gas flow rate is 1000 sccm; the chamber of the coating equipment during the deposition process The body is produced without heating, and the deposition rate is 30mg/circle.

The efficiency (Eta), open circuit voltage (Voc), short circuit current (Isc) and fill factor (FF) of the prepared heterojunction solar cell 10 were tested. The test method was the same as in Example 1. The specific test results are as shown in the table 1 shown.

Table 1 Comparative performance data of heterojunction solar cells 10 of various embodiments and comparative examples

In Table 1, the performance data of the heterojunction solar cell 10 of Comparative Example 1 is used as a benchmark and is set as 0. The performance data of other embodiments are relative data to Comparative Example 1. It can be seen from the data in Table 1 that the performance data such as efficiency and short-circuit current of the heterojunction solar cell 10 in Example 1 of the present application are significantly improved compared to Comparative Example 1 using the traditional method. The efficiency is increased by 0.15%, and the short-circuit current is increased by 40mA.

The technical features of the above-described embodiments can be combined in any way. To simplify the description, 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, All should be considered to be within the scope of this manual.

The above-described embodiments only express several implementation modes of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present application. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims.

Claims

A method for preparing a solar cell, characterized in that it includes the following steps:

Provide solar cell substrates with transparent conductive films;

sequentially forming a multilayer copper seed layer on the transparent conductive film by physical vapor deposition; and

Electroplating on the outermost copper seed layer forms a copper electrode;

The deposition power of the copper seed layer forming the innermost layer is 0.2KW to 0.8KW, and the deposition power of the copper seed layer forming the innermost layer is smaller than the deposition power of the copper seed layers forming other layers.
The method for manufacturing a solar cell according to claim 1, wherein the deposition power for forming each of the copper seed layers gradually increases in a direction from the innermost copper seed layer to the outermost copper seed layer. .
The method for preparing a solar cell according to claim 1 or 2, characterized in that, in the direction from the innermost copper seed layer to the outermost copper seed layer, the deposition power to form the outer copper seed layer is The deposition power of the adjacent inner copper seed layer is 2 to 5 times.
The method for manufacturing a solar cell according to any one of claims 1 to 3, wherein a first copper seed layer, a second copper seed layer and a third copper seed layer are sequentially formed on the transparent conductive film by physical vapor deposition. Copper seed layer.
The method of manufacturing a solar cell according to claim 4, wherein the deposition power to form the first copper seed layer is 0.2KW～0.8KW, and the deposition power to form the second copper seed layer is 1.0KW～ 3.5KW, and the deposition power to form the third copper seed layer is 3.6KW to 7.5KW.
The method for manufacturing a solar cell according to claim 4 or 5, wherein the thickness of the first copper seed layer is greater than 5 nm and less than 150 nm.
The method for manufacturing a solar cell according to any one of claims 4 to 6, wherein the substrate transmission rate for forming the second copper seed layer is greater than or equal to the substrate transmission rate for forming the first copper seed layer. .
The method for manufacturing a solar cell according to any one of claims 4 to 7, wherein the substrate transmission rate for forming the third copper seed layer is greater than or equal to that for forming the second copper seed layer. The matrix transmission rate of the layer.
The method for manufacturing a solar cell according to any one of claims 1 to 8, wherein the total thickness of each copper seed layer is 100 nm to 200 nm.
The method for manufacturing a solar cell according to any one of claims 1 to 9, wherein after electroplating the outermost copper seed layer to form a copper electrode, the method further includes removing the transparent conductive film The step of forming the copper seed layer in a region other than the copper electrode.
The method for preparing a solar cell according to any one of claims 1 to 10, wherein the method for preparing a solar cell substrate includes the following steps:

forming an amorphous silicon layer on a single crystal silicon substrate; and

The transparent conductive film is formed on the amorphous silicon layer.
The method of manufacturing a solar cell according to claim 11, wherein before forming an amorphous silicon layer on a single crystal silicon substrate, the method of manufacturing a solar cell substrate further includes: The step of performing texturing treatment to form a textured light-trapping structure on the surface of the single crystal silicon substrate.
The method for manufacturing a solar cell according to claim 11 or 12, wherein forming an amorphous silicon layer on a single crystal silicon substrate includes the following steps:

forming an intrinsic amorphous silicon layer on the single crystal silicon substrate; and

A doped amorphous silicon layer is formed on the intrinsic amorphous silicon layer.
The method for manufacturing a solar cell according to any one of claims 11 to 13, wherein the amorphous silicon layer is formed on the single crystal silicon substrate by a plasma enhanced chemical vapor deposition method.
The method for manufacturing a solar cell according to any one of claims 11 to 14, wherein the transparent conductive film is formed on the amorphous silicon layer by physical vapor deposition.
A solar cell, characterized in that the solar cell is prepared by the method for producing a solar cell according to any one of claims 1 to 15.
The solar cell according to claim 16, characterized in that it includes:

Single crystal silicon substrate;

An amorphous silicon layer is provided on at least one surface of the single crystal silicon substrate;

A transparent conductive film disposed on the surface of the amorphous silicon layer facing away from the single crystal silicon substrate;

Multiple layers of copper seed layers are sequentially stacked on the surface of the transparent conductive film facing away from the amorphous silicon layer; and

A copper electrode is provided on the surface of the outermost copper seed layer on the side facing away from the transparent conductive film.
The solar cell according to claim 17, wherein the amorphous silicon layer includes an intrinsic amorphous silicon layer and a doped amorphous silicon layer, and the intrinsic amorphous silicon layer is provided on the single crystal silicon On the surface of the substrate, the doped amorphous silicon layer is provided on the surface of the intrinsic amorphous silicon layer facing away from the single crystal silicon substrate.