Solar cell and its manufacturing method

Abstract

The present application provides a solar cell and a method for manufacturing the same. The solar cell includes a front electrode and a back electrode. Both the front electrode and the back electrode include main grids and fine grids. In the front electrode and the back electrode, the mass content of the conductive metal in the fine grid is greater than that in the main grid. The present application adjusts the content of the conductive metal in the main grid and the fine grid of the solar cell, thereby reducing the usage amount of precious metals and having a good contact effect between the main grid and the fine grid, effectively reducing the manufacturing cost.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic devices, and particularly to a solar cell and a preparation method thereof. Background Art

[0002] Solar crystalline silicon cells are divided into N-type cells and P-type cells according to the properties of silicon wafers. The difference between P-type cells and N-type cells lies in the raw material silicon wafers and cell preparation technologies. The raw material of P-type cells is P-type silicon wafers, and the raw material of N-type cells is N-type silicon. P-type silicon wafers are made by doping boron elements in silicon materials, and N-type silicon wafers are made by doping phosphorus elements in silicon materials.

[0003] Among the commercially produced crystalline silicon solar cells, P-type cells are mainly PERC cells, and N-type cells are mainly TOPCon cells. In the preparation process of solar cells, the non-silicon cost is high in the metalization process. High silver content is used in both the fine grids and main grids formed by metalization, and the contact effect between the main grid and the fine grid is poor. Therefore, how to provide a metalized grid line with low silver content has become an urgent technical problem to be solved at present. Summary of the Invention

[0004] Based on this, it is necessary to provide a solar cell and a preparation method thereof, which can adjust the content of conductive metals in the main grid and fine grid of the solar cell, thereby reducing the usage of precious metal silver and effectively reducing the preparation cost.

[0005] In a first aspect, the present application provides a solar cell. The solar cell includes a front electrode and a back electrode. Both the front electrode and the back electrode include a main grid and a fine grid. In the front electrode and the back electrode, the mass content of the conductive metal in the fine grid is greater than the mass content of the conductive metal in the main grid.

[0006] In some embodiments, the mass content of the conductive metal in the main grid of the front electrode is greater than the mass content of the conductive metal in the main grid of the back electrode.

[0007] In some embodiments, the mass content of the conductive metal in the main grid of the front electrode is 70% - 93%.

[0008] In some embodiments, the mass content of the conductive technology in the main grid of the back electrode is 55% - 82%.

[0009] In some embodiments, the mass content of the conductive metal in the fine grid of the front electrode is 82% - 95%.

[0010] In some embodiments, the mass content of the conductive metal in the fine grid of the back electrode is 88% - 95%.

[0011] In some embodiments, the solar cell is an N-type solar cell, and both the front electrode and the back electrode further include a glass amorphous material.

[0012] In some embodiments, the mass content of silver in the main grid of the front electrode is 70% - 82%, and the mass content of the glass amorphous material is 18% - 30%.

[0013] In some embodiments, the mass content of silver in the main grid of the back electrode is 70% - 82%, and the mass content of the glass amorphous material is 18% - 30%.

[0014] In some embodiments, the mass content of silver in the fine grid of the front electrode is 82% - 89%, the mass content of aluminum is 0 - 3%, and the mass content of the glass amorphous material is 11% - 15%.

[0015] In some embodiments, the content of silver in the fine grid of the back electrode is 88% - 95%, and the mass content of the glass amorphous material is 5% - 12%.

[0016] In some embodiments, in the N-type solar cell, the fine grid of the front electrode contains spherical silver crystal particles, spiky silver-aluminum alloy, and amorphous particles.

[0017] In some embodiments, in the N-type solar cell, the glass amorphous material includes at least one of silicon dioxide, lead oxide, iron oxide, zinc oxide, cobalt oxide, tellurium oxide, and barium oxide.

[0018] In some embodiments, the solar cell is a P-type solar cell, and both the front electrode and the back electrode further include a glass amorphous material.

[0019] In some embodiments, the mass content of silver in the main grid of the front electrode is 70% - 93%, and the mass content of the glass amorphous material is 7% - 30%.

[0020] In some embodiments, the mass content of silver in the main grid of the back electrode is 55% - 80%, and the mass content of the glass amorphous material is 20% - 45%.

[0021] In some embodiments, the mass content of silver in the fine grid of the front electrode is 85% - 95%, and the mass content of the glass amorphous material is 5% - 15%.

[0022] In some embodiments, the content of silver in the fine grid of the back electrode is 88% - 92%, and the mass content of the glass amorphous material is 8% - 12%.

[0023] In some embodiments, in the P-type solar cell, the glass amorphous material includes at least one of silicon dioxide, lead oxide, iron oxide, zinc oxide, cobalt oxide, tellurium oxide, and barium oxide.

[0024] In a second aspect, the present application provides a method for manufacturing a solar cell as described in the first aspect, and the manufacturing method includes:

[0025] Sinter the front and back surfaces of the cell sheet to form a front electrode and a back electrode respectively.

[0026] In some embodiments, the sintering temperature of the front electrode is 680°C to 760°C.

[0027] In some embodiments, the sintering temperature of the back electrode is 640°C to 720°C.

[0028] Compared with the traditional technology, the present application has at least the following beneficial effects:

[0029] In the present application, the content of the conductive metal in the fine grid is controlled to be greater than that in the main grid. During the metallization process, the difference in the glass transition points of the glass amorphous materials in the main grid and the fine grid can be increased, and the interaction of the glass amorphous materials in the main grid and the fine grid can be reduced, so that the contact effect between the main grid and the fine grid is better. While reducing the metallization cost, the photoelectric conversion efficiency of the solar cell can also be improved. Specific Embodiments

[0030] The following further describes the present invention in detail in conjunction with embodiments and examples. These embodiments and examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The purpose of providing these embodiments and examples is to make the understanding of the disclosed content of the present invention more thorough and comprehensive. It should also be understood that the present invention can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without departing from the connotation of the present invention, and the equivalent forms obtained also fall within the protection scope of the present invention. In addition, in the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. It should be understood that the present invention can be implemented without one or more of these details.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] In the present invention, "optionally", "optional", and "option" mean "may or may not be present", that is, any one of the two alternative options of "present" or "absent" is selected. If the term "optional" appears multiple times in a technical solution, without special instructions and without contradictions or mutual restrictions, each "optional" is independent of each other.

[0033] In the present invention, in "the first aspect", "the second aspect", etc., the terms "first", "second", etc. are only for descriptive purposes and cannot be construed as indicating or implying relative importance or quantity, nor can they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive listing and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0034] In the present invention, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open-ended technical solution containing the listed features.

[0035] In the present invention, regarding a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values within this numerical interval is considered continuous, and it includes the two numerical endpoints of this numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within this numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" is allowed to broadly include quantitative intervals such as percentage intervals, ratio intervals, and ratio value intervals.

[0036] All the documents mentioned in the present invention are cited as references in this application, just as if each document is cited separately as a reference. Unless it conflicts with the invention purpose and / or technical solution of this application, the cited documents related to the present invention are cited in their entirety and for all purposes. When the present invention involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the present invention involves cited documents, the examples and preferred methods of the relevant technical features cited can also be incorporated as references into this application, but only to the extent that the present invention can be implemented. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or be modified adaptively according to the description in this application.

[0037] In the traditional technology, the electrodes in solar cells include conductive metals and glass amorphous materials. In the metallization of N-type and P-type solar cells, the silver content in the main grid and fine grid is high, resulting in high metallization process costs. Moreover, the contact effect between the main grid and the fine grid in the metallization structure of traditional solar cells is poor. Therefore, the principle of reducing the non-silicon cost and improving the cell efficiency in this application is as follows: 1. Fine grid of the front electrode: By reducing the silver content and increasing the content of inorganic glass powder, when passing through the sintering furnace, due to the reduction of silver content, the glass powder will obtain more energy, making the sintered linear shape denser, thereby improving the FF. 2. Main grid of the front electrode and main grid of the back electrode: By reducing the silver content and changing the composition of the inorganic glass powder, the difference in the glass transition point of the inorganic glass powder in the main grid and the glass transition point of the inorganic glass powder in the front and back fine grids is increased, reducing the interaction between the two glass powders, so that the contact part between the main grid and the fine grid is better, thereby improving the FF. 3. Fine grid of the back electrode: By reducing the aluminum content, the glass powder will obtain more energy, making the sintered linear shape denser, thereby improving the FF. Finally, the preparation cost is reduced and the metallization effect is improved.

[0038] In a first aspect of the present application, a solar cell is provided. The solar cell includes a front electrode and a back electrode. Both the front electrode and the back electrode include a main grid and a fine grid. In the front electrode and the back electrode, the mass content of the conductive metal in the fine grid is greater than the mass content of the conductive metal in the main grid.

[0039] In the present application, by controlling the content of the conductive metal in the fine grid to be greater than that in the main grid, during the metallization process, the difference in the glass transition point of the glass amorphous material in the main grid and the glass transition point of the glass amorphous material in the fine grid can be increased, reducing the interaction between the glass amorphous materials in the main grid and the fine grid, so that the contact effect between the main grid and the fine grid is better. While reducing the metallization cost, the photoelectric conversion efficiency of the solar cell can also be improved.

[0040] In some embodiments, the mass content of the conductive metal in the main grid of the front electrode is greater than the mass content of the conductive metal in the main grid of the back electrode.

[0041] It can be understood that the conductive metal refers to a metal material with conductive properties. In some embodiments, the conductive metal includes at least one of silver and aluminum.

[0042] In some embodiments, the mass content of the conductive metal in the main grid of the front electrode is 70% - 93%, for example, it can be 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 89%, 90%, 91%, 92% or 93%.

[0043] In some embodiments, the mass content of the conductive technology in the main grid of the back electrode is 55% to 82%, for example, it can be 55%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80% or 82%.

[0044] In some embodiments, the mass content of the conductive metal in the fine grid of the front electrode is 82% to 95%, for example, it can be 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95%.

[0045] In some embodiments, the mass content of the conductive metal in the fine grid of the back electrode is 88% to 95%, for example, it can be 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95%.

[0046] In this application, the content of the conductive metal in the main grid can be reduced to 55%, and the content of the conductive metal in the fine grid can be reduced to 82%. Compared with the traditional technology where the content of the conductive metal in the metallization of solar cells needs to be about 90%, the amount of the conductive metal used in the metallization process is effectively reduced, and the cost is reduced by 5% to 20%.

[0047] In some embodiments, the solar cell is an N-type solar cell, and both the front electrode and the back electrode further include a glass amorphous material.

[0048] In some embodiments, the mass content of silver in the main grid of the front electrode is 70% to 82%, for example, it can be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81% or 82%.

[0049] Optionally, the mass content of the glass amorphous material in the main grid of the front electrode is 18% to 30%, for example, it can be 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%.

[0050] In some embodiments, the mass content of silver in the main grid of the back electrode is 70% to 82%, for example, it can be 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81% or 82%.

[0051] Optionally, the mass content of the glass amorphous material in the main grid of the back electrode is 18% to 30%, for example, it can be 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%.

[0052] The front main grid and the back main grid in the N-type solar cell of the present application include: 70% - 82% silver crystal particles, these silver crystals are spherical or quasi-spherical, and the silver crystal particles are tangent or separated from each other; 18% - 30% glass amorphous component, the inorganic glass amorphous material is in contact with the silver crystal particles, and the inorganic glass amorphous component ensures that the silver crystal particles will not fall off the surface of the cell.

[0053] In some embodiments, the mass content of silver in the fine grid of the front electrode is 82% - 89%, for example, it can be 82%, 83%, 84%, 85%, 86%, 87%, 88% or 89%.

[0054] Optionally, the mass content of aluminum in the fine grid of the front electrode is 0 - 3%, for example, it can be 0, 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, 1.8%, 2.1%, 2.4%, 2.7% or 3.0%.

[0055] Optionally, the mass content of the glass amorphous material in the fine grid of the front electrode is 11% - 15%, for example, it can be 11.0%, 11.4%, 11.8%, 12.2%, 12.6%, 13.0%, 13.4%, 13.8%, 14.2%, 14.6% or 15.0%.

[0056] In the N-type solar cell of the present application, the fine grid of the front electrode includes: 82% - 89% silver crystal particles, these silver crystals are spherical or quasi-spherical, and the silver crystal particles are tangent or separated from each other; 0 - 3% silver-aluminum alloy, and part of the silver-aluminum alloy presents a spiky structure; 11% - 15% silver + aluminum + glass amorphous structure.

[0057] In some embodiments, the content of silver in the fine grid of the back electrode is 88% - 95%, for example, it can be 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95%.

[0058] Optionally, the mass content of the glass amorphous material in the fine grid of the back electrode is 5% - 12%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10% or 12%.

[0059] In the N-type solar cell of the present application, the back fine grid includes: 88% - 95% silver crystal particles, these silver crystals are spherical or quasi-spherical, and their diameters are between 10 nm and 1000 nm, and the silver crystal particles are tangent or separated from each other.

[0060] In some embodiments, in the N-type solar cell, the fine grid of the front electrode contains spherical silver crystal particles, spiky silver-aluminum alloy and amorphous particles.

[0061] In some embodiments, in the N-type solar cell, the glass amorphous material includes at least one of silicon dioxide, lead oxide, iron oxide, zinc oxide, cobalt oxide, tellurium oxide, and barium oxide.

[0062] In some embodiments, the solar cell is a P-type solar cell, and the front electrode and the back electrode both further include a glass amorphous material.

[0063] In some embodiments, the mass content of silver in the main grid of the front electrode is 70% to 93%, for example, it can be 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, or 93%.

[0064] Optionally, the mass content of the glass amorphous material in the main grid of the front electrode is 7% to 30%, for example, it can be 7%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, or 30%.

[0065] In the P-type solar cell of the present application, the front main grid includes: 70% to 93% of silver crystal grains, these silver crystals are spherical or quasi-spherical, and the silver crystal grains are tangent or separated from each other; 7% to 30% of a glass amorphous component; the inorganic glass amorphous component is in contact with the silver crystal grains, and the inorganic glass amorphous component ensures that the silver crystal grains will not fall off from the surface of the cell.

[0066] In some embodiments, the mass content of silver in the main grid of the back electrode is 55% to 80%, for example, it can be 55%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, or 80%.

[0067] Optionally, the mass content of the glass amorphous material in the main grid of the back electrode is 20% to 45%, for example, it can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, or 45%.

[0068] In the P-type solar cell of the present application, the back main grid includes: 55% to 80% of silver crystal grains, these silver crystals are spherical or quasi-spherical, and the silver crystal grains are tangent or separated from each other; 20% to 45% of a glass amorphous component. The inorganic glass amorphous component is in contact with the silver crystal grains, and the inorganic glass amorphous component ensures that the silver crystal grains will not fall off from the surface of the cell.

[0069] In some embodiments, the mass content of silver in the fine grid of the front electrode is 85% to 95%, for example, it can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95%.

[0070] Optionally, the mass content of the glass amorphous material in the fine grid of the front electrode is 5% to 15%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%.

[0071] In the P-type solar cell of the present application, the fine grid of the front electrode includes: 85% to 95% of silver crystal grains, these silver crystals are spherical or quasi-spherical, and the silver crystal grains are tangent or separated from each other; 5% to 15% of the glass amorphous structure.

[0072] In some embodiments, the content of silver in the fine grid of the back electrode is 88% to 92%, for example, it can be 88.0%, 88.4%, 89.2%, 89.6%, 90.0%, 90.4%, 90.8%, 91.2%, 91.6% or 92.0%.

[0073] Optionally, the mass content of the glass amorphous material in the fine grid of the back electrode is 8% to 12%, for example, it can be 8.0%, 8.4%, 8.8%, 9.2%, 9.6%, 10.0%, 10.4%, 10.8%, 11.2%, 11.6% or 12.0%.

[0074] In the P-type solar cell of the present application, the back fine grid includes: 88% to 92% of aluminum particles, these aluminum particles are spherical or quasi-spherical, and the aluminum particles are tangent or separated from each other; 8% to 12% of the glass amorphous component.

[0075] In some embodiments, in the P-type solar cell, the glass amorphous material includes at least one of silicon dioxide, lead oxide, iron oxide, zinc oxide, cobalt oxide, tellurium oxide and barium oxide.

[0076] The second aspect of the present application provides a method for manufacturing a solar cell as described in the first aspect, and the manufacturing method includes:

[0077] Sinter the front and back of the cell sheet to form a front electrode and a back electrode respectively.

[0078] In some embodiments, the sintering temperature of the front electrode is 680°C to 760°C, for example, it can be 680°C, 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C or 760°C.

[0079] In some embodiments, the sintering temperature of the back electrode is 640°C to 720°C, and for example, it can be 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C or 720°C.

[0080] The embodiments of the present invention will be described in detail below in conjunction with the embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. For the experimental methods without specific conditions in the following embodiments, the guidance given in the present invention is preferably referred to, and it can also be in accordance with the experimental manuals or conventional conditions in the art, or in accordance with the conditions recommended by the manufacturer, or referring to the experimental methods known in the art.

[0081] In the following embodiments, the TOPCon solar cell: has a size of 210 mm × 182 mm, includes an N-type silicon wafer with a thickness of 130 μm, and a boron-diffused emitter with a thickness of 2.5 μm, an alumina layer with a thickness of 10 nm, and a SiN x layer with a thickness of 90 nm are sequentially arranged on one side surface of the N-type silicon wafer, and a SiO2 tunneling layer with a thickness of 4 nm, a polysilicon layer with a thickness of 100 nm, and a SiN x layer with a thickness of 85 nm are sequentially arranged on the other side surface of the N-type silicon wafer, and a front electrode and a back electrode are arranged on both sides of the TOPCon cell.

[0082] The PERC solar cell: has a size of 210 mm × 210 mm, includes a P-type silicon wafer with a thickness of 145 μm, and a phosphorus-diffused emitter with a thickness of 0.3 μm and a SiN x layer with a thickness of 75 nm are sequentially arranged on one side surface of the P-type silicon wafer, and an alumina layer with a thickness of 12 nm and a SiN x layer with a thickness of 85 nm are sequentially arranged on the other side surface of the P-type silicon wafer, and a front electrode and a back electrode are arranged on both sides of the PERC cell.

[0083] Example 1

[0084] This example provides a TOPCon solar cell, and the solar cell includes a front electrode and a back electrode. In the front electrode, the main grid includes 75% silver crystal grains and 25% glass amorphous material; the fine grid includes 82% silver crystal grains, 3% silver-aluminum alloy, and 15% silver + aluminum + glass amorphous material amorphous structure; in the back electrode, the main grid includes 70% silver crystal grains and 30% glass amorphous material; the fine grid includes 88% silver crystal grains and 12% glass amorphous material. The glass amorphous material includes 90% silicon dioxide, 8% lead oxide, 0.2% iron oxide, 0.8% zinc oxide, 0.2% cobalt oxide, 0.1% tellurium oxide, and 0.7% barium oxide.

[0085] This embodiment also provides a method for manufacturing the above-mentioned solar cell, including:

[0086] Coating pastes on the front and back surfaces of the solar cell respectively, with the sintering temperature of the front electrode being 740 °C and that of the back electrode being 700 °C, to obtain the said solar cell.

[0087] Example 2

[0088] Manufacture a solar cell according to the method of Example 1, the difference being only that in the front electrode, the main grid includes 82% silver crystal grains and 18% glass amorphous material; the fine grid includes 89% silver crystal grains and 11% silver + glass amorphous material amorphous structure; in the back electrode, the main grid includes 80% silver crystal grains and 20% glass amorphous material; the fine grid includes 95% silver crystal grains and 5% glass amorphous material.

[0089] Example 3

[0090] Manufacture a solar cell according to the method of Example 1, the difference being only that in the front electrode, the main grid includes 80% silver crystal grains and 20% glass amorphous material; the fine grid includes 87% silver crystal grains, 2% silver-aluminum alloy and 11% silver + aluminum + glass amorphous material amorphous structure; in the back electrode, the main grid includes 75% silver crystal grains and 25% glass amorphous material; the fine grid includes 90% silver crystal grains and 10% glass amorphous material.

[0091] Example 4

[0092] This embodiment provides a PERC solar cell, the front surface of the solar cell including a front electrode and a back electrode. In the front electrode, the main grid includes 93% silver crystal grains and 7% glass amorphous material; the fine grid includes 95% silver crystal grains and 5% glass amorphous material; in the back electrode, the main grid includes 80% silver crystal grains and 20% glass amorphous material, and the fine grid includes 92% aluminum grains and 8% glass amorphous material. The glass amorphous material includes 90% silicon dioxide, 4% tellurium oxide, 3% lead oxide, 1.8% zinc oxide, 0.2% cobalt oxide, 1% barium oxide.

[0093] This embodiment also provides a method for manufacturing the above-mentioned solar cell, including:

[0094] Coating pastes on the front and back surfaces of the solar cell respectively, with the sintering temperature of the front electrode being 730 °C and that of the back electrode being 710 °C, and obtaining the said solar cell after sintering.

[0095] Example 5

[0096] The solar cell is prepared according to the method of Example 4, except that in the front electrode, the main grid comprises 70% silver crystal particles and 30% glass amorphous material; the fine grid comprises 85% silver crystal particles and 15% glass amorphous material; in the back electrode, the main grid comprises 55% silver crystal particles and 45% glass amorphous material; the fine grid comprises 88% aluminum particles and 12% glass amorphous material.

[0097] Example 6

[0098] The solar cell is prepared according to the method of Example 4, except that in the front electrode, the main grid comprises 79% silver crystal particles and 21% glass amorphous material; the fine grid comprises 88% silver crystal particles and 12% glass amorphous material; in the back main grid, it comprises 73% silver crystal particles and 37% glass amorphous material; the fine grid comprises 89% aluminum particles and 11% glass amorphous material.

[0099] Example 7

[0100] The solar cell is prepared according to the method of Example 1, except that the composition of the main grid of the front electrode is the same as that of the main grid of the back electrode, both being 75% silver crystal particles and 25% glass amorphous material.

[0101] Example 8

[0102] The solar cell is prepared according to the method of Example 1, except that the silver content in the main grid of the front electrode is less than that in the main grid of the back electrode, and the main grid of the back electrode comprises 80% silver crystal particles.

[0103] Example 9

[0104] The solar cell is prepared according to the method of Example 4, except that the composition of the main grid of the front electrode is the same as that of the main grid of the back electrode, both being 80% silver crystal particles and 20% glass amorphous material.

[0105] Example 10

[0106] The solar cell is prepared according to the method of Example 4, except that the silver content in the main grid of the front electrode is less than that in the main grid of the back electrode, and the main grid of the front electrode comprises 75% silver crystal particles.

[0107] Comparative Example 1

[0108] The solar cell is prepared according to the method of Example 1, except that in the front electrode and the back electrode, the silver content in the main grid and the fine grid is the same, both being 75% silver crystal particles and 25% glass amorphous material.

[0109] Comparative Example 2

[0110] The solar cell is prepared according to the method of Example 1, except that in the front electrode and the back electrode, the silver content in the main grid is greater than that in the fine grid, specifically including:

[0111] The main grid of the front electrode includes 88% silver crystal particles and 12% glass amorphous material; the fine grid includes 75% silver crystal particles, 3% silver-aluminum alloy, and 22% silver + aluminum + glass amorphous material amorphous structure; the main grid of the back electrode includes 82% silver crystal particles and 18% glass amorphous material; the fine grid includes 70% silver crystal particles and 30% glass amorphous material.

[0112] Comparative Example 3

[0113] The solar cell is prepared according to the method of Example 1, except that in the front electrode and the back electrode, the silver content in the main grid is greater than that in the fine grid, specifically including:

[0114] The main grid of the front electrode includes 95% silver crystal particles and 5% glass amorphous material; the fine grid includes 93% silver crystal particles, 2% silver-aluminum alloy, and 5% silver + aluminum + glass amorphous material amorphous structure; the main grid in the back electrode includes 93% silver crystal particles and 7% glass amorphous material; the fine grid includes 97% silver crystal particles and 3% glass amorphous material.

[0115] Comparative Example 4

[0116] The solar cell is prepared according to the method of Example 4, except that in the front electrode and the back electrode, the silver content in the main grid and the fine grid is the same, both being 75% silver crystal particles and 25% glass amorphous material.

[0117] Comparative Example 5

[0118] The solar cell is prepared according to the method of Example 4, except that in the front electrode and the back electrode, the silver content in the main grid is greater than that in the fine grid, specifically including:

[0119] The main grid in the front electrode includes 88% silver crystal particles and 12% glass amorphous material; the fine grid includes 75% silver crystal particles and 25% glass amorphous material; the main grid in the back electrode includes 78% silver crystal particles and 22% glass amorphous material; the fine grid includes 76% aluminum particles and 24% glass amorphous material.

[0120] Comparative Example 6

[0121] The solar cell is prepared according to the method of Example 4, except that in the front electrode and the back electrode, the silver content in the main grid is greater than that in the fine grid, specifically including:

[0122] The main grid in the front electrode includes 95% silver crystal particles and 5% glass amorphous material, and the fine grid includes 93% silver crystal particles and 7% glass amorphous material; the main grid on the back includes 92% silver crystal particles and 8% glass amorphous material; the fine grid includes 80% aluminum particles and 20% glass amorphous material.

[0123] Perform performance tests on the above-prepared solar cells. The test methods include:

[0124] Under standard test conditions (AM1.5, 25°C, 1000 W / m 2 ²), test the photoelectric conversion efficiency and fill factor (FF). The test results are shown in Table 1.

[0125] Table 1

[0126] Number Photovoltaic conversion efficiency (%) Fill factor (%) Example 1 25.5 86.5 Example 2 25.7 86 Example 3 25.6 85.5 Example 4 23.5 81.5 Example 5 23.6 82 Example 6 23.55 81.8 Example 7 25.45 86.3 Example 8 25.43 86.2 Example 9 23.44 81.3 Example 10 23.41 81.2 Comparative Example 1 25.3 85.6 Comparative Example 2 25.4 86 Comparative Example 3 25.47 86.2 Comparative Example 4 23.2 80.3 Comparative Example 5 23.4 81 Comparative Example 6 23.45 81.2

[0127] It can be seen from the above table that:

[0128] It can be seen from the above examples and comparative examples that: reducing the silver content in the fine grid of the front electrode and increasing the content of inorganic glass powder. During the sintering process, due to the reduction of silver content, the glass powder will obtain more energy, making the sintered wire type denser, thus improving the FF. By adjusting the size relationship of the silver content in the main grid and the fine grid, not only the silver content is reduced and the cost is lowered, but also the composition of the inorganic glass powder is changed, increasing the difference in the glass transition point of the inorganic glass powder in the main grid and the glass transition point of the inorganic glass powder in the front and back fine grids, reducing the interaction between the two glass powders, so that the contact part between the main grid and the fine grid is better and the FF is improved. In the P-type solar cell, reducing the aluminum content in the back fine grid, the glass powder will obtain more energy, making the sintered wire type denser, thus improving the FF. In summary, the non-silicon cost of the solar cell in this application can be reduced by 5% - 20%, and the photoelectric conversion efficiency can be increased by about 0.05%.

[0129] In this application, it is controlled that the content of the conductive metal in the fine grid is greater than that in the main grid. During the metallization process, it can increase the difference in the glass transition point of the glass amorphous material in the main grid and the glass transition point of the glass amorphous material in the fine grid, reduce the interaction between the glass amorphous materials in the main grid and the fine grid, so that the contact effect between the main grid and the fine grid is better. While reducing the metallization cost, it can also improve the photoelectric conversion efficiency of the solar cell.

[0130] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0131] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A solar cell, characterized in that, The solar cell includes a front electrode and a back electrode. Both the front electrode and the back electrode include main grids and fine grids. In the front electrode and the back electrode, the mass content of the conductive metal in the fine grid is greater than that in the main grid; the mass content of the conductive metal in the main grid of the front electrode is greater than that in the main grid of the back electrode; The solar cell satisfies one of the following conditions: (1) The solar cell is an N-type solar cell. The main grids of the front electrode and the back electrode include silver and glass amorphous material. The mass content of silver in the main grid of the front electrode is 70% - 82%, and the mass content of the glass amorphous material is 18% - 30%; the mass content of silver in the main grid of the back electrode is 70% - 82%, and the mass content of the glass amorphous material is 18% - 30%; (2) The solar cell is a P-type solar cell. The main grids of the front electrode and the back electrode include silver and glass amorphous material. The mass content of silver in the main grid of the front electrode is 70% - 93%, and the mass content of the glass amorphous material is 7% - 30%; the mass content of silver in the main grid of the back electrode is 55% - 80%, and the mass content of the glass amorphous material is 20% - 45%.

2. The solar cell according to claim 1, wherein, The solar cell satisfies at least one of the following conditions: (1) The mass content of the conductive metal in the fine grid of the front electrode is 82% - 95%; (2) The mass content of the conductive metal in the fine grid of the back electrode is 88% - 95%.

3. The solar cell according to claim 1 or 2, characterized in that, The solar cell is an N-type solar cell. The fine grids of the front electrode and the back electrode include a conductive metal and a glass amorphous material. The solar cell satisfies at least one of the following conditions: (1) The mass content of silver in the fine grid of the front electrode is 82% - 89%, the mass content of aluminum is 0 - 3%, and the mass content of the glass amorphous material is 11% - 15%; (2) The content of silver in the fine grid of the back electrode is 88% - 95%, and the mass content of the glass amorphous material is 5% - 12%.

4. The solar cell according to claim 3, wherein In the N-type solar cell, the fine grid of the front electrode contains spherical silver crystal particles, spiky silver-aluminum alloy, and amorphous particles.

5. The solar cell according to claim 3, wherein In the N-type solar cell, the glass amorphous material includes at least one of silicon dioxide, lead oxide, iron oxide, zinc oxide, cobalt oxide, tellurium oxide, and barium oxide.

6. The solar cell according to claim 1 or 2, characterized in that, The solar cell is a P-type solar cell. The fine grids of the front electrode and the back electrode include a conductive metal and a glass amorphous material. The solar cell satisfies at least one of the following conditions: (1) The mass content of silver in the fine grid of the front electrode is 85% - 95%, and the mass content of the glass amorphous material is 5% - 15%; (2) The content of aluminum in the fine grid of the back electrode is 88% - 92%, and the mass content of the glass amorphous material is 8% - 12%.

7. The solar cell according to claim 6, wherein, In the P-type solar cell, the glass amorphous material includes at least one of silicon dioxide, lead oxide, iron oxide, zinc oxide, cobalt oxide, tellurium oxide, and barium oxide.

8. A method for preparing a solar cell according to any one of claims 1-7, characterized in that, The preparation method includes: A front electrode and a back electrode are respectively sintered on the front and back surfaces of the battery cell.

9. The preparation method according to claim 8, wherein, The preparation method satisfies at least one of the following conditions: (1) The sintering temperature of the front electrode is 680°C to 760°C; (2) The sintering temperature of the back electrode is 640°C to 720°C.