Solar cell and preparation method thereof

Abstract

The invention provides a solar cell and a preparation method thereof, relates to the technical field of photovoltaics, and can solve the technical problems of screen printing plate damage and cell performance reduction in a cell screen printing process in the prior art. The preparation method of the solar cell provided by the embodiment of the invention comprises the following steps: S1, providing a silicon-based substrate; s2, respectively forming functional layers on the front surface and the back surface of the silicon-based substrate; s3, forming a protective layer on the functional layer on at least one side surface of the silicon-based substrate; and S4, forming an electrode on the functional layer on the front surface and / or the back surface in a silk-screen printing manner to prepare the solar cell.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and particularly to a solar cell and a method for preparing the same. Background Art

[0002] In the existing preparation process of solar cells, it is a common preparation process to form a transparent conductive layer on the surface of a battery wafer and then form battery electrodes by screen printing electrodes on the surface of the transparent conductive layer. However, due to the presence of dust generated during the process of the technological process or particles in the environmental cleanliness on the surface of the transparent conductive layer, during the screen printing process, after the screen plate of the screen printing is used for a long time, the dust and particles are likely to cause damage to the printing screen plate, especially the screen plate made of metal mesh cloth. Furthermore, the damaged screen plate is likely to damage the functional layer of the battery wafer. Thus, while the service life of the screen plate is affected, the performance of the prepared battery will also decline.

[0003] In view of the above technical problems, by adding a purging device in the whole-line equipment to purge and remove dust and particles, it will increase the production cycle and cannot completely remove dust and particles. In addition, or by replacing the screen plate to restore the battery efficiency. However, frequent replacement of the screen plate results in low screen plate productivity, reduced production efficiency, and increased production costs.

[0004] Therefore, in the battery printing process of solar cells, how to ensure low cost and short production cycle without sacrificing the screen plate life and battery efficiency is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] The purpose of the present invention is to provide a solar cell and a method for preparing the same, so as to solve the technical problems of screen plate damage and reduced battery performance in the existing battery screen printing process.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is as follows:

[0007] The first aspect embodiment of the present invention provides a method for preparing a solar cell, including:

[0008] Step S1: Providing a silicon-based substrate;

[0009] Step S2: Respectively forming functional layers on the front and back surfaces of the silicon-based substrate;

[0010] Step S3: Forming a protective layer on the functional layer on at least one side surface of the silicon-based substrate;

[0011] Step S4: Forming electrodes on the functional layer on the front and / or back surfaces by screen printing to obtain the solar cell.

[0012] Further, step S3 specifically includes:

[0013] Pattern-print a protective paste on the functional layer on at least one side surface of the silicon-based substrate, and after curing, form a patterned protective layer with an opening, wherein the coating area of the protective paste is the area other than the electrode reserved position.

[0014] Further, step S3 specifically includes:

[0015] Print a protective paste on the functional layer on at least one side surface of the silicon-based substrate, and after curing, form the protective layer, the protective layer covers the electrode reserved position, and then through patterning to form a patterned protective layer with an opening, and the opening exposes the electrode reserved position.

[0016] Further, step S3 further includes:

[0017] A to-be-etched area with a width of 1 - 500 μm is formed between the edge of the protective layer on the back surface of the silicon-based substrate and the edge of the corresponding functional layer. After curing and before forming the opening, use the protective layer as a mask to etch the corresponding functional layer of the to-be-etched area.

[0018] Further, the patterning process includes a laser etching process or a chemical etching process.

[0019] Further, forming electrodes on the functional layer on the front and / or back surfaces by screen printing includes:

[0020] On the patterned protective layer with an opening, by screen printing, screen print a metal paste at the position where the opening exposes the electrode reserved position, and after the metal paste cures, form the electrode.

[0021] Further, step S3 specifically includes:

[0022] Screen print a protective layer paste and cure to form a protective layer, and the protective layer covers the electrode reserved position;

[0023] Forming electrodes on the functional layer on the front and / or back surfaces by screen printing specifically includes:

[0024] By screen printing, print a metal paste on the electrode reserved position of the protective layer, and then sinter it so that the metal paste passes through the protective layer and is electrically connected to the functional layer, and after the metal paste cures, form the electrode.

[0025] Further, the protective paste contains a light conversion material.

[0026] Furthermore, the light transmittance of the protective layer is greater than 95%.

[0027] In a second aspect of the embodiments of the present invention, a solar cell is provided, which is prepared by the preparation method of the solar cell according to any one of the embodiments of the first aspect.

[0028] The present invention provides a preparation method of a solar cell. Before forming an electrode on a functional layer by screen printing, a protective layer is pre-set on the functional layer. By printing a protective paste on the functional layer and forming a protective layer after the protective paste is cured, dust or microparticles generated on the surface of the functional layer in the original cell deposition process can be fixed and covered, avoiding damage to the screen plate during the screen printing of the electrode, thereby improving the efficiency stability of the printing process and increasing the service life of the screen plate.

[0029] From the following detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more clearly aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Some specific embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings in an exemplary but non-limiting manner. The same reference numerals in the drawings denote the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale.

[0031] In the drawings:

[0032] Figure 1 is a flowchart of the preparation method of the solar cell according to the embodiment of the present invention;

[0033] Figure 2 is a schematic structural diagram of the solar cell according to the first embodiment of the present invention;

[0034] Figure 3 is a schematic structural diagram of the solar cell according to the second embodiment of the present invention;

[0035] Figure 4a is a schematic structural diagram of the solar cell according to the third embodiment of the present invention when forming a functional layer;

[0036] Figure 4b is a schematic structural diagram of the solar cell according to the third embodiment of the present invention when forming a patterned protective layer;

[0037] Figure 5a is a schematic diagram of the solar cell according to the fourth embodiment of the present invention when plating functional layers on the front and back;

[0038] Figure 5b is a schematic diagram of the solar cell according to the fourth embodiment of the present invention when printing protective layers on the front and back;

[0039] Figure 5c Schematic diagram of the solar cell according to the fourth embodiment of the present invention during back etching of the protective layer;

[0040] Figure 5d Schematic diagram of the solar cell according to the fourth embodiment of the present invention during formation of patterned protective layers on the front and back sides;

[0041] Figure 5e Schematic diagram of the solar cell according to the fourth embodiment of the present invention during printing of metal paste.

[0042] Description of reference numerals:

[0043] Silicon-based substrate - 1; functional layer - 2; first sub-functional film layer - 21; second sub-functional film layer - 22; area to be etched - 23; protective layer - 3; opening - 31; electrode - 4. Detailed implementation manners

[0044] In the description of this embodiment, it should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "height", "upper", "lower", "left", "right", "vertical", "horizontal", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0045] As a specific embodiment of the present invention, as Figure 1 shown, the method for preparing a solar cell according to the first aspect embodiment of the present invention may include:

[0046] Step S1: Provide a silicon-based substrate;

[0047] Step S2: Form functional layers on the front and back surfaces of the silicon-based substrate respectively;

[0048] Step S3: Form a protective layer on the functional layer on at least one side surface of the silicon-based substrate;

[0049] Step S4: Form electrodes on the functional layer on the front and / or back surfaces by screen printing to obtain a solar cell.

[0050] First embodiment

[0051] Specifically, when preparing a solar cell by the method for preparing a solar cell according to the embodiment of the present invention, as Figure 2As shown, first, a functional layer 2 is formed on the front and back surfaces of the silicon-based substrate 1. Herein, the functional layer 2 may include a first sub-functional film layer 21 located on the front or back surface of the silicon-based substrate 1 (for example, when the solar cell is a heterojunction solar cell, the first sub-functional film layer 21 includes a passivation layer and a doping layer, the front doping layer is an n-type doping layer, and the back doping layer is a p-type doping layer), and a second sub-functional film layer 22 (i.e., a transparent conductive film layer) located on the surface of the first sub-functional film layer 21, which is not specifically limited herein. Secondly, a protective layer 3 is provided on the second sub-functional film layer 22 on the front or back surface of the silicon-based substrate 1 by screen printing, or protective layers 3 are provided on the second sub-functional film layers 22 on both the front and back surfaces of the silicon-based substrate 1.

[0052] Finally, an electrode 4 is printed and formed on the functional layer 2 corresponding to the provided protective layer 3 by screen printing, thereby manufacturing a solar cell.

[0053] That is to say, in the preparation method of the solar cell according to the embodiment of the present invention, before printing and forming an electrode on the functional layer by screen printing, a protective layer is further provided on the functional layer in advance. By printing a protective paste on the functional layer, after the protective paste is cured, a protective layer is formed, and the protective layer is retained in the subsequent process without being removed. It can fix and cover the dust or microparticles generated on the surface of the functional layer in the original cell deposition process, avoiding the damage to the screen caused by the dust or particles during screen printing of the electrode, thereby improving the efficiency stability of the printing process and increasing the service life of the screen.

[0054] In addition, the preparation method of the present invention also avoids the need to frequently replace the screen in the existing screen printing process to resume normal production, improves the production capacity of the screen, and reduces the production cost.

[0055] Second Embodiment

[0056] In some embodiments, as Figure 3 described, for the preparation of low-temperature curing batteries (such as HJT heterojunction batteries, IBC batteries, perovskite batteries, etc.), step S3 may specifically include:

[0057] Pattern printing a protective paste on the functional layer 2 on at least one side surface of the silicon-based substrate, and after curing, a patterned protective layer 3 with an opening 31 is formed, wherein the coating area of the protective paste is the area other than the electrode reserved position.

[0058] That is to say, after the functional layer 2 is formed on the front and back surfaces of the silicon-based substrate 1 respectively, a protective paste is pattern printed directly on the functional layer 2 corresponding to the electrode reserved position on the corresponding functional layer 2 of the silicon-based substrate 1, that is, the protective paste is coated on the area other than the electrode reserved position on the functional layer on the front and / or back surface of the silicon-based substrate, and after the protective paste is cured, a patterned protective layer 3 with an opening 31 is formed.

[0059] Then, an electrode 4 is printed on the functional layer 2 provided with the protective layer 3 by screen printing, thereby manufacturing a solar cell.

[0060] Third Embodiment

[0061] In some other embodiments, for the preparation of low-temperature-cured batteries (such as HJT heterojunction batteries, IBC batteries, perovskite batteries, etc.), step S3 may specifically further include:

[0062] Print a protective paste on the functional layer 2 on at least one side surface of the silicon-based substrate 1, and after curing, form a protective layer 3. The protective layer 3 covers the electrode reserved position, and then through patterning, a patterned protective layer with openings is formed.

[0063] That is to say, as Figure 4a shown, after forming the functional layer 2 on the front and back surfaces of the silicon-based substrate 1 respectively, directly print the protective paste on the corresponding functional layer 2 of the silicon-based substrate 1 as a whole. After curing, the formed protective layer 3 covers the electrode reserved position, and then through patterning for the corresponding electrode reserved position, a patterned protective layer 3 with an opening 31 is formed, obtaining the structure as Figure 4b shown, wherein the patterning includes a laser etching process or a chemical etching process.

[0064] Then, an electrode 4 is printed on the functional layer 2 provided with the protective layer 3 by screen printing, thereby manufacturing a solar cell.

[0065] Fourth Embodiment

[0066] In some embodiments, for low-temperature-cured batteries, especially HJT heterojunction batteries, step S3 may further include:

[0067] A to-be-etched area with a width of 1 - 500 μm is formed between the edge of the protective layer on the back surface of the silicon-based substrate and the edge of the corresponding functional layer. After curing and before forming the opening, use the protective layer 3 as a mask to etch the functional layer of the corresponding to-be-etched area.

[0068] It should be noted that when setting the to-be-etched area on the back surface of the silicon-based substrate, when forming the protective layer on the back surface, it is necessary to cover the electrode reserved area, that is, after forming the protective layer 3, first etch the back transparent conductive layer in the back edge area of the solar cell, and then pattern the protective layer 3 to form an opening exposing the area for printing the electrode.

[0069] As an example, the following process steps are specifically adopted:

[0070] First, as Figure 5aAs shown in the figure, a functional layer 2 (including a first sub-functional film layer 21 composed of a passivation layer and a doping layer and a second sub-functional film layer 22 composed of a transparent conductive layer) is formed on the front and back surfaces of the silicon-based substrate 1 respectively;

[0071] Secondly, as Figure 5b shown in the figure, a protective layer 3 is printed on the functional layer 2 (i.e., the second sub-functional film layer 22) on the front and back surfaces of the silicon-based substrate 1. Among them, the edge of the protective layer 3 on the back surface of the silicon-based substrate 1 is shorter than the edge of the second sub-functional film layer 22 on the same side, so that a to-be-etched area 23 with a width of 1 - 500 μm is formed between the edge of the protective layer 3 and the edge of the second sub-functional film layer 22. That is to say, a width area of 1 - 500 μm is left unprinted with the protective layer slurry from the edge of the second sub-functional film layer 22 and is cured.

[0072] Then, as Figure 5c shown in the figure, the second sub-functional film layer 22 corresponding to the to-be-etched area 23 can be etched by using the protective layer 3 as a mask. Specifically, this etching process at least etches away the transparent conductive layer of the to-be-etched area 23. It should be noted that due to the phenomenon of overplating during the preparation of the transparent conductive layers on the front and back of the solar cell, the transparent conductive layers on the front and back may be electrically connected, which may affect the efficiency of the solar cell. Therefore, it is necessary to electrically isolate the transparent conductive layers on the front and back. In the existing technology, an additional etching process is required. In the present invention, the protective layer 3 can play the role of a mask during the process of cutting off the back transparent conductive layer and is retained, and then plays the role of protecting the screen plate during the subsequent printing process.

[0073] Furthermore, as Figure 5d shown in the figure, then a patterned protective layer 3 with an opening 31 is formed by patterning the corresponding electrode reserved position, where the patterning process includes a laser etching process or a chemical etching process.

[0074] Finally, as Figure 5e shown in the figure, metal paste is printed on the functional layer 2 on the front and back surfaces of the silicon-based substrate 1 by screen printing to form electrodes 4 (the electrodes 4 pass through the protective layer 3 and are electrically connected to the second sub-functional film layer 22), and a solar cell is manufactured.

[0075] That is to say, the preparation method of the present invention is also applicable to the back etching in the HJT process. By utilizing the acid corrosion resistance of the protective layer 3, it is used as an etching mask layer and does not need to be removed as the protective layer of the screen printing plate, thus avoiding the electrical connection between the front and back sides of the battery. In addition, in the process of HJT batteries, the unilateral width of the carrier mask area of the second sub-functional film layer is between 350 μm and 850 μm, and it is difficult to further reduce it due to the influence of automatic wafer loading. However, the printed protective layer can control the unilateral mask area within a narrower range, improving the utilization rate and electrical performance of the battery chips. At the same time, the protective layer does not need to be cleaned and removed, reducing the damage to the screen printing plate in the screen printing process.

[0076] It should be noted that in the HJT battery process, the above-mentioned edge etching process occurs before the patterning process.

[0077] Fifth Embodiment

[0078] In some embodiments, when preparing a low-temperature curing battery, by means of screen printing, electrodes are formed on the functional layers on the front and / or back sides, which may include:

[0079] On the patterned protective layer with openings, by means of screen printing, metal paste is screen printed at the positions of the openings, and after the metal paste is cured, electrodes are formed.

[0080] That is to say, when preparing a low-temperature curing battery, such as an HJT battery, it is necessary to print metal paste at the positions corresponding to the openings on the patterned protective layer with openings, and after the metal paste is cured, electrodes are formed, thereby obtaining the battery.

[0081] Sixth Embodiment

[0082] In some embodiments, when preparing a high-temperature sintered battery, such as a Topcon battery, a PERC battery, etc., step S3 may specifically include:

[0083] By screen printing the protective layer paste and curing to form a protective layer, the protective layer covers the electrode reserved positions;

[0084] By means of screen printing, electrodes are formed on the functional layers on the front and / or back sides, specifically including:

[0085] By means of screen printing, metal paste is printed at the electrode reserved positions of the protective layer, and then sintered, so that the metal paste passes through the protective layer 3 and is electrically connected to the functional layer, and after the metal paste is cured, electrodes are formed.

[0086] Seventh Embodiment

[0087] In some embodiments, the protective paste may contain a light conversion material.

[0088] Specifically, since the protective layer is not removed in the later process steps, light conversion materials such as rare earth materials, quantum dot materials, and phosphors can also be added to the protective paste. By adding the light conversion materials, ultraviolet light passing through the battery absorption layer can be converted into infrared light that the battery can absorb, thereby increasing the overall light absorption of the battery. This protective layer can serve as a mask during the process of scribing the edge transparent conductive layer, protect the screen printing stencil during the process of printing the electrodes, and at the same time, serve as a light conversion material layer in the formation of the solar cell structure to further increase the light conversion efficiency.

[0089] Eighth Embodiment

[0090] In some embodiments, the light transmittance of the protective layer is greater than 95%.

[0091] That is to say, the protective layer is made of a transparent material. Thus, the protective layer with a high light transmittance can improve the overall light absorption rate of the battery, thereby improving the conversion efficiency of the battery.

[0092] Ninth Embodiment

[0093] An embodiment of the second aspect of the present invention provides a solar cell prepared by the preparation method of the solar cell according to any one of the embodiments of the first aspect above.

[0094] At this point, those skilled in the art should recognize that although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived from the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and determined to cover all these other variations or modifications.

Claims

1. A method for preparing a solar cell, characterized in that: include: Step S1: providing a silicon-based substrate; Step S2: forming functional layers on the front and back sides of the silicon-based substrate respectively; Step S3: forming a protective layer on the functional layer on at least one side of the silicon-based substrate; Step S4: forming electrodes on the functional layer on the front and / or back side by screen printing to obtain the solar cell.

2. The method for preparing a solar cell according to claim 1, characterized in that: The step S3 specifically includes: A protective paste is patterned and printed on the functional layer on at least one side of the silicon-based substrate, and a patterned protective layer with openings is formed after curing, wherein the coating area of ​​the protective paste is the area outside the reserved position of the electrode.

3. The method for preparing a solar cell according to claim 1, characterized in that: The step S3 specifically includes: A protective slurry is printed on the functional layer on at least one side of the silicon-based substrate, and the protective layer is formed after curing, and the protective layer covers the reserved electrode position. Then, a graphic protective layer with an opening is formed through a graphic treatment, and the opening exposes the reserved electrode position.

4. The method for preparing a solar cell according to claim 3, characterized in that: The step S3 further comprises: An etching area with a width of 1-500 μm is formed between the edge of the protective layer on the back of the silicon-based substrate and the edge of the corresponding functional layer. After solidification and before forming the opening, the functional layer corresponding to the etching area is etched using the protective layer as a mask.

5. The method for preparing a solar cell according to claim 3, characterized in that: The patterning process includes a laser etching process or a chemical etching process.

6. The method for preparing a solar cell according to claim 2 or 3, characterized in that: The method of forming electrodes on the functional layer on the front and / or back side by screen printing comprises: On the patterned protection layer with the opening, metal paste is screen-printed at the reserved position of the electrode exposed by the opening by screen printing, and the metal paste is solidified to form the electrode.

7. The method for preparing a solar cell according to claim 1, characterized in that: The step S3 specifically includes: A protective layer slurry is screen-printed and solidified to form a protective layer, wherein the protective layer covers the reserved position of the electrode; The forming of electrodes on the functional layer on the front and / or back side by screen printing specifically includes: The metal paste is printed on the reserved position of the electrode on the protective layer by screen printing, and then sintered, so that the metal paste passes through the protective layer and is electrically connected to the functional layer. The metal paste is solidified to form the electrode.

8. The method for preparing a solar cell according to claim 2 or 3, characterized in that: The protective paste contains a light conversion material.

9. The method for preparing a solar cell according to claim 1, characterized in that: The light transmittance of the protective layer is greater than 95%.

10. A solar cell, characterized in that: The solar cell is prepared by the method for preparing the solar cell according to any one of claims 1 to 9.

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