Solar cell and method for preparing the same

Abstract

The present invention discloses a solar cell and a preparation method thereof. The preparation method comprises the following steps: step (1) providing a cell substrate, preparing an electrically connected back main grid electrode and a back fine grid electrode on the back of the cell substrate, and drying them; step (2) preparing an electrically connected front main grid electrode and a front fine grid electrode on the front of the cell substrate, and drying them; step (3) sintering the back main grid electrode, the back fine grid electrode, the front main grid electrode and the front fine grid electrode on the cell substrate to form an ohmic contact to achieve current output. The cell efficiency of the solar cell prepared by the preparation method of the present invention is higher than 25.5%.

Description

Technical Field

[0001] The present invention relates to the field of new energy and photovoltaic technology, and in particular to a solar cell and a preparation method thereof. Background Art

[0002] In the production of photovoltaic modules, solar cells are made into PN junctions that can generate electricity by light after processes such as texturing, diffusion and plasma enhanced chemical vapor deposition (PECVD), and the positive and negative electrodes can form ohmic contacts at both ends of the PN junction to achieve current output. The electrodes of solar cells are composed of two parts: the main grid line and the fine grid line. The main grid line is directly connected to the external lead of the battery, and the fine grid line guides the collection of current and summarizes it to the main grid line. It is made into a narrow and thin grid line to overcome the resistance of the diffusion layer. There are many metallization methods for manufacturing electrodes, and screen printing is the most mature and common production process. Screen printing is to print the slurry on the material to be printed after the elastic deformation of the screen by squeezing the screen with a scraper. Solar cells mainly use this screen printing process to print the back electrode, back electric field and positive electrode. Screen printing in the prior art will cause various changes in the morphology of the grid electrode due to the influence of a series of screen parameters and printing parameters such as the size of the mesh knot, wire diameter width, opening width and tension size, making it difficult to achieve an ideal shape. Summary of the invention

[0003] Based on this, it is necessary to provide a method for preparing a solar cell. The method for preparing a solar cell of the present invention adopts a screen printing process to prepare a back electrode and a positive electrode, and the grid line electrode has morphological features of different heights and widths in different regions, which provides a certain theoretical basis for the development, research and upgrading of solar electrodes in the future.

[0004] An embodiment of the present application provides a method for preparing a solar cell.

[0005] A method for preparing a solar cell comprises the following steps:

[0006] Step (1) providing a battery substrate, preparing an electrically connected back main grid electrode and a back fine grid electrode on the back side of the battery substrate, and drying the back main grid electrode, wherein the height and width of a first region on the back main grid electrode are different from the height and width of a region outside the first region, and / or the height and width of a second region on the back fine grid electrode are different from the height and width of a region outside the second region;

[0007] Step (2) preparing an electrically connected front main grid electrode and a front fine grid electrode on the front side of the battery substrate, and drying them, wherein the height and width of the third region on the front main grid electrode are different from the height and width of the region outside the third region, and / or the height and width of the fourth region on the front fine grid electrode are different from the height and width of the region outside the fourth region;

[0008] Step (3) sintering the back main grid electrode, the back fine grid electrode, the front main grid electrode and the front fine grid electrode on the battery substrate to form an ohmic contact;

[0009] In some embodiments, the back main gate electrode includes a first back main gate electrode and a second back main gate electrode, the height of the first back main gate electrode is different from the height of the second back main gate electrode, and / or the width of the first back main gate electrode is different from the width of the second back main gate electrode.

[0010] In some embodiments, the height of the first back main gate electrode is 1 μm to 20 μm, wherein the maximum height of the first back main gate electrode is 6 μm to 20 μm, the minimum height of the first back main gate electrode is 1 μm to 6 μm, and the height of the second back main gate electrode is less than the height of the first back main gate electrode.

[0011] In some embodiments, the width of the first back main gate electrode is 5μm to 100μm, wherein the maximum width of the first back main gate electrode is 10μm to 100μm, the minimum width of the first back main gate electrode is 5μm to 95μm, and the width of the second back main gate electrode is smaller than the width of the first back main gate electrode.

[0012] In some embodiments, the back main gate electrode includes a back main gate third electrode, the back main gate third electrode is in a non-connected state with the back main gate first electrode and the back main gate second electrode, the height of the back main gate third electrode is less than 20μm, and the height of the back main gate third electrode is less than the height of the back main gate second electrode, the width of the back main gate third electrode is less than 95μm, and the width of the back main gate third electrode is less than the width of the back main gate second electrode.

[0013] In some embodiments, the back fine gate electrode includes a back fine gate first electrode and a back fine gate second electrode, the height of the back fine gate first electrode is different from the height of the back fine gate second electrode, the height of the back fine gate first electrode is smaller than the height of the back main gate first electrode, and the width of the back fine gate first electrode is smaller than the width of the back main gate first electrode; the height of the back fine gate second electrode is smaller than the height of the back main gate second electrode, and the width of the back fine gate second electrode is smaller than the width of the back main gate second electrode.

[0014] In some embodiments, the back fine gate electrode includes a back fine gate third electrode, the back fine gate third electrode is in a non-connected state with the back fine gate first electrode and the back fine gate second electrode, and the height of the back fine gate third electrode is smaller than the height of the back fine gate second electrode, and the width of the back fine gate third electrode is smaller than the width of the back fine gate second electrode.

[0015] In some embodiments, the front main gate electrode includes a front main gate first electrode and a front main gate second electrode, the front fine gate electrode includes a front fine gate first electrode and a front fine gate second electrode, the height of the front main gate first electrode is different from the height of the front main gate second electrode, and / or the width of the front main gate first electrode is different from the width of the front main gate second electrode.

[0016] In some embodiments, the height of the first front main grid electrode is 1 μm to 20 μm, wherein the maximum height of the first front main grid electrode is 6 μm to 20 μm, the minimum height of the first front main grid electrode is 1 μm to 6 μm, and the height of the second front main grid electrode is less than the height of the first front main grid electrode.

[0017] In some embodiments, the width of the first front main grid electrode is 5 μm to 100 μm, wherein the maximum width of the first front main grid electrode is 10 μm to 100 μm, the minimum width of the first front main grid electrode is 5 μm to 95 μm, and the width of the second front main grid electrode is smaller than the width of the first front main grid electrode.

[0018] In some embodiments, the front main gate electrode includes a front main gate third electrode, the front main gate third electrode is in a non-connected state with the front main gate first electrode and the front main gate second electrode, the height of the front main gate third electrode is less than 20 μm, and the height of the front main gate third electrode is less than the height of the front main gate second electrode, the width of the front main gate third electrode is less than 95 μm, and the width of the front main gate third electrode is less than the width of the front main gate second electrode.

[0019] In some embodiments, the front fine gate electrode includes a front fine gate first electrode and a front fine gate second electrode, the height of the front fine gate first electrode is different from the height of the front fine gate second electrode, the height of the front fine gate first electrode is smaller than the height of the front main gate first electrode, and the width of the front fine gate first electrode is smaller than the width of the front main gate first electrode; the height of the front fine gate second electrode is smaller than the height of the front main gate second electrode, and the width of the front fine gate second electrode is smaller than the width of the front main gate second electrode.

[0020] In some embodiments, the front fine gate electrode includes a front fine gate third electrode, the front fine gate third electrode is in a non-connected state with the front fine gate first electrode and the front fine gate second electrode, and the height of the front fine gate third electrode is smaller than the height of the front fine gate second electrode, and the width of the front fine gate third electrode is smaller than the width of the front fine gate second electrode.

[0021] In some of the embodiments, during the sintering heat treatment in step (3), the sintering peak temperature is not less than 800° C. and the sintering time is 1 min to 2 min.

[0022] In some of the embodiments, the method for preparing the solar cell further comprises step (4) testing and sorting.

[0023] In some embodiments, when providing a battery substrate in step (1), the following steps are included:

[0024] S1, cleaning and texturing a silicon substrate of a predetermined thickness;

[0025] S2. Preparing a diffusion square resistance of 140Ω / □ on the front side of the silicon substrate through a boron diffusion process;

[0026] S3, cleaning the back side of the silicon substrate to remove the borosilicate glass layer;

[0027] S4, performing oxidation treatment on the back side of the silicon substrate to form a silicon oxide layer, and depositing an n+ polysilicon layer on the silicon oxide layer;

[0028] S5. Depositing a front dielectric passivation film and a front anti-reflection film on the front side of the silicon substrate, and depositing a back dielectric passivation film and a back anti-reflection film on the back side of the silicon substrate to obtain the battery substrate.

[0029] An embodiment of the present application also provides a solar cell.

[0030] A solar cell is prepared by adopting the preparation method.

[0031] An embodiment of the present application also provides a solar cell.

[0032] A solar cell, comprising a cell substrate, wherein the back side of the cell substrate is connected to a back main grid electrode and a back fine grid electrode, wherein the height and width of a first region on the back main grid electrode are different from the height and width of a region other than the first region, and / or the height and width of a second region on the back fine grid electrode are different from the height and width of a region other than the second region;

[0033] The front side of the battery substrate is connected to a front main grid electrode and a front fine grid electrode, wherein the height and width of the third region on the front main grid electrode are different from the height and width of the region outside the third region, and / or the height and width of the fourth region on the front fine grid electrode are different from the height and width of the region outside the fourth region.

[0034] In some embodiments, the back main gate electrode includes a first back main gate electrode and a second back main gate electrode, the height of the first back main gate electrode is different from the height of the second back main gate electrode, and / or the width of the first back main gate electrode is different from the width of the second back main gate electrode.

[0035] In some embodiments, the back main gate electrode includes a back main gate third electrode, the back main gate third electrode is in a non-connected state with the back main gate first electrode and the back main gate second electrode, the height of the back main gate third electrode is smaller than the height of the back main gate second electrode, and the width of the back main gate third electrode is smaller than the width of the back main gate second electrode.

[0036] In some embodiments, the back fine gate electrode includes a back fine gate first electrode and a back fine gate second electrode, the height of the back fine gate first electrode is different from the height of the back fine gate second electrode, the height of the back fine gate first electrode is smaller than the height of the back main gate first electrode, and the width of the back fine gate first electrode is smaller than the width of the back main gate first electrode; the height of the back fine gate second electrode is smaller than the height of the back main gate second electrode, and the width of the back fine gate second electrode is smaller than the width of the back main gate second electrode.

[0037] In some embodiments, the back fine gate electrode includes a back fine gate third electrode, the back fine gate third electrode is in a non-connected state with the back fine gate first electrode and the back fine gate second electrode, and the height of the back fine gate third electrode is smaller than the height of the back fine gate second electrode, and the width of the back fine gate third electrode is smaller than the width of the back fine gate second electrode.

[0038] In some embodiments, the front main gate electrode includes a front main gate first electrode and a front main gate second electrode, the front fine gate electrode includes a front fine gate first electrode and a front fine gate second electrode, the height of the front main gate first electrode is different from the height of the front main gate second electrode, and / or the width of the front main gate first electrode is different from the width of the front main gate second electrode.

[0039] In some embodiments, the front main gate electrode includes a front main gate third electrode, the front main gate third electrode is in a non-connected state with the front main gate first electrode and the front main gate second electrode, the height of the front main gate third electrode is smaller than the height of the front main gate second electrode, and the width of the front main gate third electrode is smaller than the width of the front main gate second electrode.

[0040] In some embodiments, the front fine gate electrode includes a front fine gate first electrode and a front fine gate second electrode, the height of the front fine gate first electrode is different from the height of the front fine gate second electrode, the height of the front fine gate first electrode is smaller than the height of the front main gate first electrode, and the width of the front fine gate first electrode is smaller than the width of the front main gate first electrode; the height of the front fine gate second electrode is smaller than the height of the front main gate second electrode, and the width of the front fine gate second electrode is smaller than the width of the front main gate second electrode.

[0041] In some embodiments, the front fine gate electrode includes a front fine gate third electrode, the front fine gate third electrode is in a non-connected state with the front fine gate first electrode and the front fine gate second electrode, and the height of the front fine gate third electrode is smaller than the height of the front fine gate second electrode, and the width of the front fine gate third electrode is smaller than the width of the front fine gate second electrode.

[0042] The preparation method of the above-mentioned solar cell adopts a screen printing process to prepare a main gate electrode and a fine gate electrode on the front and back sides of the cell substrate respectively. The main gate electrodes and / or fine gate electrodes on the front and back sides have morphological characteristics of different heights and widths in different regions. The main gate electrodes and / or fine gate electrodes on the front and back sides cooperate to form ohmic contacts at both ends of the PN junction to achieve the function of current output. The solar cell prepared by the above-mentioned preparation method of the solar cell has a stable morphological state of the main gate electrodes and / or fine gate electrodes on the front and back sides, and the cell efficiency is higher than 25.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0044] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings. In the following description, the same reference numerals represent the same parts.

[0045] Figure 1A schematic diagram of a method for preparing a solar cell according to an embodiment of the present invention;

[0046] Figure 2 A schematic side view of a first electrode of a back main grid according to an embodiment of the present invention;

[0047] Figure 3 A schematic side view of a back main gate electrode according to an embodiment of the present invention;

[0048] Figure 4 This is a front schematic diagram of a back main gate electrode according to an embodiment of the present invention;

[0049] Figure 5 This is a side SEM schematic diagram of the back main gate electrode according to an embodiment of the present invention;

[0050] Figure 6 This is a front SEM schematic diagram of a back main gate electrode according to an embodiment of the present invention;

[0051] Figure 7 The figure is a schematic diagram of the solar cell structure according to one embodiment of the present invention.

[0052] Description of Reference Numerals

[0053] 1. Solar cell; 10. n-type silicon wafer substrate; 20. p+ emitter; 30. AlOx passivation film; 40. front dielectric passivation film and anti-reflection film; 50. tunneling oxide layer; 60. n+ polysilicon layer; 70. back dielectric passivation film and anti-reflection film; 100. back main gate electrode; 101. back main gate first electrode; 102. back main gate second electrode; 103. back main gate third electrode; 104. back fine gate first electrode; 105. back fine gate second electrode; 106. back fine gate third electrode; 201. front main gate first electrode; 202. front main gate second electrode; 203. front main gate third electrode; 204. front fine gate first electrode; 205. front fine gate second electrode; 206. front fine gate third electrode. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0055] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0056] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0058] In the description of the present invention, "several" means more than one, "many" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0060] The present application provides a method for preparing a solar cell to solve the problem in the prior art that the screen printing, due to the influence of a series of screen parameters and printing parameters such as mesh size, wire width, opening width and tension, causes the morphology of the grid electrode to change in various ways, making it difficult to achieve an ideal shape. The method for preparing a solar cell will be described below in conjunction with the accompanying drawings.

[0061] The method for preparing the solar cell provided in the embodiments of the present application is exemplary, please refer to Figure 1 As shown, Figure 1 A schematic diagram of a method for preparing a solar cell provided in an embodiment of the present application. The method for preparing a solar cell of the present application can be used for preparing solar cells.

[0062] In order to more clearly illustrate the method for preparing a solar cell, the method for preparing a solar cell will be introduced below with reference to the accompanying drawings.

[0063] A solar cell, comprising a cell substrate, wherein the back side of the cell substrate is connected with a back main grid electrode 10 and a back fine grid electrode, wherein the height and width of a first region on the back main grid electrode 10 are different from the height and width of a region other than the first region, and / or the height and width of a second region on the back fine grid electrode are different from the height and width of a region other than the second region;

[0064] The front side of the battery substrate is connected to a front main grid electrode and a front fine grid electrode, wherein the height and width of the third region on the front main grid electrode are different from the height and width of the region outside the third region, and / or the height and width of the fourth region on the front fine grid electrode are different from the height and width of the region outside the fourth region.

[0065] For example, see Figure 1 As shown, the above-mentioned method for preparing the solar cell comprises the following steps:

[0066] Step (1) provides a battery substrate, prepares an electrically connected back main grid electrode 10 and a back fine grid electrode on the back side of the battery substrate, and performs a drying process, wherein the height and width of the first area on the back main grid electrode 10 are different from the height and width of the area outside the first area, and / or the height and width of the second area on the back fine grid electrode are different from the height and width of the area outside the second area.

[0067] Step (2) prepares an electrically connected front main grid electrode and a front fine grid electrode on the front side of the battery substrate, and performs a drying process, wherein the height and width of the third region on the front main grid electrode are different from the height and width of the region outside the third region, and / or the height and width of the fourth region on the front fine grid electrode are different from the height and width of the region outside the fourth region.

[0068] Step (3) sintering the back main grid electrode, the back fine grid electrode, the front main grid electrode and the front fine grid electrode on the battery substrate to form an ohmic contact to achieve current output;

[0069] It should be noted that the specific locations of the first area, the second area, the third area and the fourth area can be set as needed.

[0070] In some embodiments, the back main gate electrode 10 includes a first back main gate electrode 101 and a second back main gate electrode 102. The height of the first back main gate electrode 101 is different from the height of the second back main gate electrode 102.

[0071] In some embodiments, the number of the back main gate second electrode 102 can be multiple.

[0072] In some embodiments, the width of the back busbar first electrode 101 is different from the width of the back busbar second electrode 102 .

[0073] In some embodiments, the height of the back main grid first electrode 101 is 1 μm to 20 μm, for example, Figure 2 H1, H2, H3, H4 and H5 are shown. Among them, the maximum height H5 of the back main grid first electrode 101 is 6μm to 20μm, and the minimum height H2 of the back main grid first electrode 101 is 1μm to 6μm. The height of the back main grid second electrode 102 is less than the height of the back main grid first electrode 101. For example, see Figure 3 As shown, the heights H6, H7 and H8 of the back main grid second electrode 102 are shown. Figure 5 As shown, the height of the back main gate electrode 10 composed of the actually printed back main gate first electrode and the back main gate second electrode 102 is not flat, and the difference between the highest point and the lowest point of the back main gate electrode 10 is about 5 μm.

[0074] In some embodiments, the width of the back main grid first electrode 101 is 5 μm to 100 μm. Figure 4 As shown, the maximum width W1 of the back main grid first electrode 101 is 10 μm to 100 μm. The minimum width W2 of the back main grid first electrode 101 is 5 μm to 95 μm. The width of the back main grid second electrode 102 is smaller than the width of the back main grid first electrode 101. Figure 6 As shown, the width of the back main gate electrode 10 composed of the back main gate first electrode 101 and the back main gate second electrode 102 is not flat, and the difference between the widest part and the narrowest part of the back main gate electrode 10 is about 5 μm.

[0075] In some embodiments, the back main gate electrode 10 includes a back main gate third electrode 103. The back main gate third electrode 103 is in a non-connected state with the back main gate first electrode 101 and the back main gate second electrode 102. Figure 6 As shown, it can be clearly seen that in addition to the back main grid first electrode 101, there are a number of back main grid second electrodes 102 connected to the back main grid first electrode 101, and a number of back main grid third electrodes 103 that are not connected to the back main grid first electrode 101 and the back main grid second electrode 102. The height of the back main grid third electrode 103 is less than 20 μm, and the height of the back main grid third electrode 103 is less than the height of the back main grid second electrode 102, see Figure 3 The height H9 of the back main grid third electrode 103 is shown. The width of the back main grid third electrode 103 is less than 95 μm, and the width of the back main grid third electrode 103 is less than the width of the back main grid second electrode 102 .

[0076] In some embodiments, the number of the back main grid third electrode 103 may be multiple.

[0077] In one embodiment of the present application, the back main grid second electrode 102 in the back main grid electrode 10 is of an irregular shape. In addition to the back main grid first electrode 101 and the back main grid second electrode 102, the back main grid electrode 10 preferably also includes a plurality of back main grid third electrodes 103 that are not connected to the back main grid first electrode 101 and the back main grid second electrode 102, the back main grid third electrode 103 is of an irregular shape, and the height and width of the back main grid third electrode 103 are respectively smaller than the back main grid first electrode 101; the back main grid first electrode 101 and the plurality of irregularly shaped back main grid second electrodes 102 and the plurality of back main grid third electrodes 103 together constitute the body of the back main grid electrode 10 on the back side, so as to form an ohmic contact on the battery substrate.

[0078] In some embodiments, the back fine gate electrode includes a back fine gate first electrode and a back fine gate second electrode. The height of the back fine gate first electrode is different from the height of the back fine gate second electrode. The height of the back fine gate first electrode is less than the height of the back main gate first electrode 101. The width of the back fine gate first electrode is less than the width of the back main gate first electrode 101. The height of the back fine gate second electrode is less than the height of the back main gate second electrode 102. The width of the back fine gate second electrode is less than the width of the back main gate second electrode 102.

[0079] In some embodiments, the back fine gate electrode includes a back fine gate third electrode, the back fine gate third electrode is in a non-connected state with the back fine gate first electrode and the back fine gate second electrode, and the height of the back fine gate third electrode is smaller than the height of the back fine gate second electrode, and the width of the back fine gate third electrode is smaller than the width of the back fine gate second electrode.

[0080] In some of the embodiments, the number of the back side fine grid first electrodes and the number of the back side fine grid second electrodes can be set according to actual needs.

[0081] In some embodiments, the front main grid electrode includes a front main grid first electrode and a front main grid second electrode. The front fine grid electrode includes a front fine grid first electrode and a front fine grid second electrode. The height of the front main grid first electrode is different from the height of the front main grid second electrode.

[0082] In some embodiments, the number of the front main grid second electrodes may be multiple.

[0083] In some of the embodiments, the width of the first front busbar electrode is different from the width of the second front busbar electrode.

[0084] In some embodiments, the height of the first front main grid electrode is 1 μm to 20 μm. The maximum height of the first front main grid electrode is 6 μm to 20 μm. The minimum height of the first front main grid electrode is 1 μm to 6 μm. The height of the second front main grid electrode is less than the height of the first front main grid electrode.

[0085] In some embodiments, the width of the first front main grid electrode is 5 μm to 100 μm, wherein the maximum width of the first front main grid electrode is 10 μm to 100 μm, the minimum width of the first front main grid electrode is 5 μm to 95 μm, and the width of the second front main grid electrode is smaller than the width of the first front main grid electrode.

[0086] In some embodiments, the front main grid electrode includes a front main grid third electrode. The front main grid third electrode is in a non-connected state with the front main grid first electrode and the front main grid second electrode. The height of the front main grid third electrode is less than 20 μm, and the height of the front main grid third electrode is less than the height of the front main grid second electrode. The width of the front main grid third electrode is less than 95 μm. The width of the front main grid third electrode is less than the width of the front main grid second electrode.

[0087] In some of the embodiments, the number of the front main grid third electrodes may be multiple.

[0088] In one embodiment of the present application, the front main grid second electrode in the front main grid electrode is of irregular shape. In addition to the front main grid first electrode and the front main grid second electrode, the front main grid electrode preferably also includes a plurality of front main grid third electrodes that are not connected to the front main grid first electrode and the front main grid second electrode, the front main grid third electrode is of irregular shape, and the height and width of the front main grid third electrode are respectively smaller than the front main grid first electrode; the front main grid first electrode and the plurality of irregularly shaped front main grid second electrodes and the plurality of front main grid third electrodes together constitute the main body of the front main grid electrode, so as to form an ohmic contact on the battery substrate.

[0089] In some embodiments, the front fine grid electrode includes a front fine grid first electrode and a front fine grid second electrode. The height of the front fine grid first electrode is different from the height of the front fine grid second electrode. The height of the front fine grid first electrode is less than the height of the front main grid first electrode. The width of the front fine grid first electrode is less than the width of the front main grid first electrode. The height of the front fine grid second electrode is less than the height of the front main grid second electrode, and the width of the front fine grid second electrode is less than the width of the front main grid second electrode.

[0090] In some embodiments, the front fine gate electrode includes a front fine gate third electrode, the front fine gate third electrode is in a non-connected state with the front fine gate first electrode and the front fine gate second electrode, and the height of the front fine gate third electrode is smaller than the height of the front fine gate second electrode, and the width of the front fine gate third electrode is smaller than the width of the front fine gate second electrode.

[0091] In some of the embodiments, the number of the front fine grid first electrodes and the number of the front fine grid second electrodes can be set according to actual needs.

[0092] In some of the embodiments, during the sintering heat treatment in step (3), the sintering peak temperature is not less than 800° C. and the sintering time is 1 min to 2 min.

[0093] In some embodiments, when providing a battery substrate in step (1), the following steps are included:

[0094] S1, cleaning and texturing a silicon substrate of a predetermined thickness;

[0095] S2. Prepare a diffusion square resistance of 140Ω / □ on the front side of the silicon substrate through a boron diffusion process;

[0096] S3, cleaning the back side of the silicon substrate to remove the borosilicate glass layer;

[0097] S4, performing oxidation treatment on the back side of the silicon substrate to form a silicon oxide layer, and depositing an n+ polysilicon layer on the silicon oxide layer;

[0098] S5. Depositing a front dielectric passivation film and a front anti-reflection film on the front side of the silicon substrate, and depositing a back dielectric passivation film and a back anti-reflection film on the back side of the silicon substrate to obtain a battery substrate.

[0099] For example, in one specific example, when providing a battery substrate in step (1), the following steps are included:

[0100] S1. Cleaning and texturing an N-type single crystal silicon wafer with a thickness of 140 μm;

[0101] S2. Prepare a diffusion square resistance of 140Ω / □ on the front side of the N-type single crystal silicon wafer through a boron diffusion process;

[0102] S3, cleaning the back side of the N-type single crystal silicon wafer to remove the silicon glass layer;

[0103] S4, performing oxidation treatment on the back side of the N-type single crystal silicon wafer to form a silicon oxide layer, and depositing an n+ polysilicon layer on the silicon oxide layer;

[0104] S5. Depositing a front dielectric passivation film and a front anti-reflection film on the front side of the N-type single crystal silicon wafer, and depositing a back dielectric passivation film and a back anti-reflection film on the back side of the N-type single crystal silicon wafer to obtain a battery substrate.

[0105] In some of the embodiments, when printing the back main grid first electrode 101, the back main grid second electrode 102 and the back main grid third electrode 103 on the battery substrate, the height and width corresponding to each electrode are achieved by selecting the film thickness, yarn thickness, opening and other parameters of the printing screen. Similarly, when printing the back fine grid first electrode, the back fine grid second electrode and the back fine grid third electrode on the battery substrate, when printing the front main grid first electrode, the front main grid second electrode and the front main grid third electrode on the battery substrate, when printing the front fine grid first electrode, the front fine grid second electrode and the front fine grid third electrode on the battery substrate, the height and width corresponding to each electrode are achieved by selecting the film thickness, yarn thickness, opening and other parameters of the printing screen.

[0106] For example, when printing the back main grid first electrode 101, the back main grid second electrode 102 and the back main grid third electrode 103 on the battery substrate, the maximum height H5 of the back main grid first electrode 101 is 20μm, the maximum width W1 of the back main grid first electrode 101 is 100μm, the height of the back main grid third electrode 103 is less than 1μm, and the width of the back main grid third electrode 103 is 2μm. Correspondingly, the line diameter of the back main grid printing screen is 5μm~25μm, the film thickness is 2μm~16μm, the yarn thickness is 9μm~21μm, and the opening is 10μm~100μm.

[0107] In some of the embodiments, the method for preparing solar cells further includes step (4) testing and sorting.

[0108] In some of the embodiments, the test sorting specifically includes: online IV test and EL test. After the online IV test and EL test are completed, the grades and excellent products are subdivided on the online slicing machine.

[0109] An embodiment of the present application further provides a solar cell 1 .

[0110] A solar cell 1 is prepared by the above-mentioned preparation method.

[0111] In some of these embodiments, see Figure 7 As shown, the solar cell 1 comprises an n-type silicon wafer substrate 10, and a p+ emitter 20, an AlOx passivation film 30, a front dielectric passivation film and an anti-reflection film 40 are sequentially stacked and connected on the front side of the n-type silicon wafer substrate 10; a front main grid first electrode 201, a front main grid second electrode 202, a front main grid third electrode 203, a front fine grid first electrode 204, a front fine grid second electrode 205, and a front fine grid third electrode 206 are arranged on the front side of the n-type silicon wafer substrate 10;

[0112] The back side of the n-type silicon wafer substrate 10 is sequentially stacked with a tunneling oxide layer 50, an n+ polysilicon layer 60, a front dielectric passivation film and an anti-reflection film 70; the back side of the n-type silicon wafer substrate 10 is provided with a back main gate first electrode 101, a back main gate second electrode 102, a back main gate third electrode 103, a back fine gate first electrode 104, a back fine gate second electrode 105, and a back fine gate third electrode 106.

[0113] The above-mentioned method for preparing solar cells adopts screen printing technology to prepare main grid electrodes and fine grid electrodes on the front and back of the cell substrate respectively. The main grid electrodes and / or fine grid electrodes on the front and back have different height and width morphological features in different regions. The main grid electrodes and / or fine grid electrodes on the front and back cooperate to form ohmic contacts to achieve the function of current output. The cell efficiency of the solar cell prepared by the above-mentioned method for preparing solar cells is higher than 25.5%. The above-mentioned method for preparing solar cells, the electrode performance and microstructure of mass-produced cells have laid a foundation for subsequent research in the industry. The above-mentioned method for preparing solar cells marks the method of preparing the metal electrodes of solar cells by screen printing and the microstructure of forming the metal electrodes, which is somewhat different from the traditional metal electrodes. The actual printed metal electrodes have the above-mentioned types of electrodes with different morphologies, which cooperate with each other to form ohmic contacts with the emitter and collect current.

[0114] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0115] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0116] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a solar cell, characterized in that: The steps include: Step (1) providing a battery substrate, preparing an electrically connected back main grid electrode and a back fine grid electrode on the back side of the battery substrate, and drying the back main grid electrode, wherein the height and width of a first region on the back main grid electrode are different from the height and width of a region outside the first region, and / or the height and width of a second region on the back fine grid electrode are different from the height and width of a region outside the second region; Step (2) preparing an electrically connected front main grid electrode and a front fine grid electrode on the front side of the battery substrate, and drying them, wherein the height and width of the third region on the front main grid electrode are different from the height and width of the region outside the third region, and / or the height and width of the fourth region on the front fine grid electrode are different from the height and width of the region outside the fourth region; Step (3) sintering the back main grid electrode, the back fine grid electrode, the front main grid electrode and the front fine grid electrode on the battery substrate to form an ohmic contact; The back main gate electrode includes a first back main gate electrode, a second back main gate electrode and a third back main gate electrode, wherein the third back main gate electrode is in a non-connected state with the first back main gate electrode and the second back main gate electrode.

2. The method for preparing a solar cell according to claim 1, characterized in that: The height of the first back main grid electrode is different from the height of the second back main grid electrode, and / or the width of the first back main grid electrode is different from the width of the second back main grid electrode.

3. The method for preparing a solar cell according to claim 2, characterized in that: The height of the first back main grid electrode is 1 μm to 20 μm, wherein the maximum height of the first back main grid electrode is 6 μm to 20 μm, the minimum height of the first back main grid electrode is 1 μm to 6 μm, and the height of the second back main grid electrode is less than the height of the first back main grid electrode.

4. The method for preparing a solar cell according to claim 2, characterized in that: The width of the first back main grid electrode is 5 μm to 100 μm, wherein the maximum width of the first back main grid electrode is 10 μm to 100 μm, the minimum width of the first back main grid electrode is 5 μm to 95 μm, and the width of the second back main grid electrode is smaller than the width of the first back main grid electrode.

5. The method for preparing a solar cell according to any one of claims 1 to 4, characterized in that: The height of the third electrode of the back main grid is less than 20 μm, and the height of the third electrode of the back main grid is less than the height of the second electrode of the back main grid. The width of the third electrode of the back main grid is less than 95 μm, and the width of the third electrode of the back main grid is less than the width of the second electrode of the back main grid.

6. The method for preparing a solar cell according to any one of claims 1 to 4, characterized in that: The back fine gate electrode includes a back fine gate first electrode and a back fine gate second electrode. The height of the back fine gate first electrode is different from the height of the back fine gate second electrode. The height of the back fine gate first electrode is smaller than the height of the back main gate first electrode, and the width of the back fine gate first electrode is smaller than the width of the back main gate first electrode; the height of the back fine gate second electrode is smaller than the height of the back main gate second electrode, and the width of the back fine gate second electrode is smaller than the width of the back main gate second electrode.

7. The method for preparing a solar cell according to claim 6, characterized in that: The back fine gate electrode includes a back fine gate third electrode, the back fine gate third electrode is in a non-connected state with the back fine gate first electrode and the back fine gate second electrode, and the height of the back fine gate third electrode is smaller than the height of the back fine gate second electrode, and the width of the back fine gate third electrode is smaller than the width of the back fine gate second electrode.

8. The method for preparing a solar cell according to any one of claims 1 to 4, characterized in that: The front main gate electrode includes a first front main gate electrode and a second front main gate electrode, the front fine gate electrode includes a first front fine gate electrode and a second front fine gate electrode, the height of the first front main gate electrode is different from the height of the second front main gate electrode, and / or the width of the first front main gate electrode is different from the width of the second front main gate electrode.

9. The method for preparing a solar cell according to claim 8, characterized in that: The height of the first front main grid electrode is 1 μm to 20 μm, wherein the maximum height of the first front main grid electrode is 6 μm to 20 μm, the minimum height of the first front main grid electrode is 1 μm to 6 μm, and the height of the second front main grid electrode is less than the height of the first front main grid electrode.

10. The method for preparing a solar cell according to claim 8, characterized in that: The width of the first front main grid electrode is 5 μm to 100 μm, wherein the maximum width of the first front main grid electrode is 10 μm to 100 μm, the minimum width of the first front main grid electrode is 5 μm to 95 μm, and the width of the second front main grid electrode is smaller than the width of the first front main grid electrode.

11. The method for preparing a solar cell according to claim 8, characterized in that: The front main gate electrode includes a front main gate third electrode, and the front main gate third electrode is in a non-connected state with the front main gate first electrode and the front main gate second electrode. The height of the front main gate third electrode is less than 20 μm, and the height of the front main gate third electrode is less than the height of the front main gate second electrode. The width of the front main gate third electrode is less than 95 μm, and the width of the front main gate third electrode is less than the width of the front main gate second electrode.

12. The method for preparing a solar cell according to claim 8, characterized in that: The front fine grid electrode includes a front fine grid first electrode and a front fine grid second electrode. The height of the front fine grid first electrode is different from the height of the front fine grid second electrode. The height of the front fine grid first electrode is smaller than the height of the front main grid first electrode, and the width of the front fine grid first electrode is smaller than the width of the front main grid first electrode. The height of the front fine grid second electrode is smaller than the height of the front main grid second electrode, and the width of the front fine grid second electrode is smaller than the width of the front main grid second electrode.

13. The method for preparing a solar cell according to claim 12, characterized in that: The front fine grid electrode includes a front fine grid third electrode, the front fine grid third electrode is in a non-connected state with the front fine grid first electrode and the front fine grid second electrode, and the height of the front fine grid third electrode is smaller than the height of the front fine grid second electrode, and the width of the front fine grid third electrode is smaller than the width of the front fine grid second electrode.

14. The method for preparing a solar cell according to any one of claims 1 to 4, 7, 9 to 13, characterized in that: During the sintering heat treatment in step (3), the sintering peak temperature is not less than 800° C. and the sintering time is 1 min to 2 min; And / or, also includes step (4) testing and sorting.

15. A solar cell, characterized in that: The preparation method is described in any one of claims 1 to 14.

16. A solar cell, characterized in that: A battery substrate is included, wherein the back side of the battery substrate is connected to a back main grid electrode and a back fine grid electrode, wherein the height and width of a first region on the back main grid electrode are different from the height and width of a region other than the first region, and / or the height and width of a second region on the back fine grid electrode are different from the height and width of a region other than the second region; The front side of the battery substrate is connected to a front main grid electrode and a front fine grid electrode, wherein the height and width of the third region on the front main grid electrode are different from the height and width of the region outside the third region, and / or the height and width of the fourth region on the front fine grid electrode are different from the height and width of the region outside the fourth region; The back main gate electrode includes a first back main gate electrode, a second back main gate electrode and a third back main gate electrode, wherein the third back main gate electrode is in a non-connected state with the first back main gate electrode and the second back main gate electrode.

17. The solar cell according to claim 16, characterized in that: The solar cell also meets at least one of the following conditions: (1) The height of the first back main grid electrode is different from the height of the second back main grid electrode, and / or the width of the first back main grid electrode is different from the width of the second back main grid electrode; (2) the back fine gate electrode comprises a back fine gate first electrode and a back fine gate second electrode, the height of the back fine gate first electrode is different from the height of the back fine gate second electrode, the height of the back fine gate first electrode is smaller than the height of the back main gate first electrode, and the width of the back fine gate first electrode is smaller than the width of the back main gate first electrode; the height of the back fine gate second electrode is smaller than the height of the back main gate second electrode, and the width of the back fine gate second electrode is smaller than the width of the back main gate second electrode; (3) the front main grid electrode includes a first front main grid electrode and a second front main grid electrode, the front fine grid electrode includes a first front fine grid electrode and a second front fine grid electrode, the height of the first front main grid electrode is different from the height of the second front main grid electrode, and / or the width of the first front main grid electrode is different from the width of the second front main grid electrode; (4) The front fine grid electrode includes a front fine grid first electrode and a front fine grid second electrode, the height of the front fine grid first electrode is different from the height of the front fine grid second electrode, the height of the front fine grid first electrode is smaller than the height of the front main grid first electrode, and the width of the front fine grid first electrode is smaller than the width of the front main grid first electrode; the height of the front fine grid second electrode is smaller than the height of the front main grid second electrode, and the width of the front fine grid second electrode is smaller than the width of the front main grid second electrode.

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